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A N A T O M Y, 
 
 DESCRIPTIVE AND SURGICAL 
 
 BY 
 
 HENRY KiEAY, F.R.S., 
 
 FELLOW OF THE ROYAL COLLEOE OF SUROEONS; LECTURER ON ANATOMY AT ST. QEORGk's 
 HOSPITAL MEDICAL SCHOOL, LONDON. 
 
 EDITED BY 
 
 T. PICKERING PICK, F.R.C.S., 
 
 CONSULTING SURGEON TO ST. GEORGe's HOSPITAL AND TO THE VICTORIA HOSPITAL FOR CHILDREN, LONDON; 
 H. M. INSPECTOR OF ,\NATOMY IN ENGLAND AND WALES, 
 
 AND 
 
 ROBERT HOWDEN, M.A., M.B., CM., 
 
 PROFESSOR OF ANATOMY IN THE UNIVERSITY OF DURHAM; EXAMINER IN ANATOMY IN THE UNIVERSITIES 
 OF DURHAM AND EDINBURGH, AND TO THE BOARD OF EDUCATION, SOUTH KENSINGTON. 
 
 NEW AMERICAN EDITION. 
 
 THOROUGHLY REVISED AND RE-EDITED WITH ADDITIONS 
 
 BY 
 
 JOHN CHALMERS Da COSTA, M.D„, 
 
 PROFESSOR OF PRINCIPLES OF SURGERY AND PROFESSOR OF CLINICAL SURGERY I .V JEFFERSON MEDICAL COLLEGE 
 PHILADELPHIA; SURGEON TO THE PHILADELPHIA HOSPITAL; CONSULTING SURGEON 
 
 TO ST Joseph's hospital 
 
 ILLUSTRATED WITH 1132 ELABORATE ENGRAVINGS. 
 
 6^77 
 
 I.EA BROTHERS & CO., 
 PHILADELPHIA AND NEW YORK. 
 
Copyright, 1905, by Lea Brothers & Co, 
 Copyright, 1907, by T.ea Brothers & Co. 
 
 Revised, printed and copyrighted, 1905. Reprinted, 1906. 
 Reprinted with alterations and recopyrighted, August, 1907. 
 

 THIS 
 
 NEW AMERICAN EDITION OF GRAY'S ANATOMY 
 
 IS DEDICATED TO 
 
 WILLIAM W. KEEN, M.D, LL.D., Hon. F.KC.S. [Eng. and Edin.] 
 
 THE DISTINGUISHED PROFESSOR OF SURGERY IN JEFFERSON 
 MEDICAL COLLEGE 
 
 AS AN EVIDENCE OF 
 
 THE ADMIRATION, THE AFFECTION AND THE GRATITUDE OF HIS COLLEAGUE 
 
 AND FORMER ASSISTANT 
 
 THE EDITOR 
 
 74978 
 
PREFACE. 
 
 In this revision of Gray's Anatomy, the Editor has endeavored to reflect the 
 development of the subject since the appearance of the last edition, and has 
 sought to accoinpHsh this without sacrificing those practical and didactic char- 
 acteristics that have ever been the most notable features of the book. Radical 
 innovations were undesirable, and original exposition was neither desirable nor 
 possible. The P^ditor is responsible for some eliminations, many alterations, 
 and a great number of additions; and it has been deemed unwise even to attempt 
 to designate, by brackets or any other device, so great a number of changes and 
 additions. 
 
 In order that its pages might represent the world's best knowledge, American, 
 English, French, and German text-books, monographs, and journal-articles have 
 been freely consulted. In using statements from these numerous sources, the 
 aim has been to give, in every instance, proper credit to the author. If, in some 
 cases, this has not been done, the failure is the result of accident, and never of 
 design. 
 
 Among the many works thus utilized may be mentioned the three composite 
 treatises edited by Gerrish, Cunningham, and Morris, respectively; Poirier and 
 Charpy, Testut, Spalteholz (which has recently been translated into English 
 and edited by Professor Barker); Hughes's Practical Anatomy, edited and coni- 
 pleted by Keith; McClellan's Regional Anatomy; Deaver's Surgical Anatomy ; 
 Treves's Applied Anatomy; Owens's* Manual of Anatomy; Eisendrath's Clinical 
 Anatomy; Byron Robinson, on the Peritoneum; and the text-books of Quain 
 and MacAUister. Special credit is due to the chapter on the "Lymphatics" in 
 Poirier and Charpy (translated and edited by Leaf) ; to the admirable section 
 on the "Nervous System," written by Professor Cunningham in his text-book; 
 and to Professor Santee's extremely valuable monograph on the Anatomy of the 
 Brain and Spinal Cord. 
 
 The Latin, new or international nomenclature has been introduced in 
 parentheses, following the names still currently used in English-speaking coun- 
 tries. This system of coupling the current and the new names answers the needs 
 of all students, and will facilitate the much-to-be-desired adoption of the new 
 nomenclature. The Latin nomenclature was recommended by an international 
 (committee, was published by Wilhelm His, and has been generally accepted by 
 anatomists. Owing to its accuracy and its simplicity, it seems destined eventu- 
 ally to succeed the older methods of designation; but in this country at least, 
 the older nomenclature is still too firmly fixed to be entirely and suddenly 
 abandoned. 
 
 Gray's Anatomy has been noted for the extent and the elaborate nature of its 
 illustrations. This new edition exceeds its predecessor in the number of engrav- 
 ings and in the use of colors. The series now aggregates over eleven hundred, of 
 which about five hundred are new in this edition. Particular acknowledgment for 
 originals is due to Spalteholz, Cunningham, Poirier and Charpy, Testut, Gerrish, 
 Byron Robinson, and the Atlas of Human Anatomy by Carl Toldt, assisted by 
 
 (V) 
 
vi PREFACE 
 
 A. D. Rosa (recently translated into English and edited by M. Eden Paul). The 
 pictures taken from these various sources have been re-engraved, and in some 
 instances have been modified. 
 
 In this edition the special articles on "Histology" and "Embryology," hitherto 
 placed at the end of the book, have been eliminated. The extent, the importance, 
 and the technical nature of these great subjects have led to the creation of special 
 chairs for their teaching; and it seems desirable that the text-books used by 
 the students should be those written by men devoted to these specialties. No 
 single volume, in these days, can offer adequate instruction on anatomy, histology, 
 and embryology; and to attempt it would be unwise. The bearings of histology 
 and embryology upon anatomy are close and highly important. The Editor has 
 set forth the essential points of these subjects when the elucidation of the text 
 demanded it by means of resumes. For these, he has drawn chiefly upon the 
 excellent sections in the previous edition of Cray (which were edited by Robert 
 Howden), supplementing them from the Hisiology and Microscopic Anatomy 
 by Szymonowicz (translated by John Bruce MacCallum), the text-book of 
 Histology by Bohm and von Davidoff (edited by G. Carl Huber), and the text- 
 book of Embryology by John Clement Heisler. The clear and instructive surgical 
 notes of Mr. Pick have, of course, been retained; although, here and there, they 
 have been modified or added to, in accordance with the views of the day. 
 Because of an oversight the foot-notes, thirty-five in number, from page 49 to 
 page 497 inclusive, are not credited to the Editors of the 15th English edition. 
 Subsequent to page 497 proper credit is given for foot-notes from the English 
 editors. 
 
 The Editor desires cordially to express his sense of indebtedness and gratitude 
 to Dr. Howard Dehoney, Senior Assistant Demonstrator of Anatomy in the 
 Jefferson Medical College, for his able and conscientious aid and collaboration. 
 When a book has been edited many times by many men, the views and the 
 style of the author are sure to be more or less obscured. The Editor of this 
 edition hopes that Gray's Anatomy has not suffered too many things at his 
 hands. 
 
 John Chalmers Da Costa. 
 
 Philadelphia, 1905. 
 
PUBLISHERS' NOTE. 
 
 Henry Gray ilied young, but left in his masterpiece imperishable evidence 
 of his two-fold genius, on the one hand a profound capacity to grasp the struc- 
 ture of the human body, and on the other an equal insight into the mind and 
 the best method of imparting knowledge. His work immediately attained its 
 merited pre-eminence, a position which the many excellent treatises of the past 
 fifty years have only rendered more conspicuous. 
 
 During this period fretiuent revisions have kept Gray always abreast of the 
 active development of its subject. Among its editors it has numbered many 
 of the ablest anatomists on both sides of the Atlantic. The services of Dr. 
 Da Costa were sought by the Publishers by reason of his combined qualifications 
 as an anatomist, a teacher and a surgeon. He has borne in mind the Author's 
 original purpose, namely, to facilitate to the utmost the work of instructors and 
 students, antl to afford the physician and surgeon the assistance necessary in 
 practice. He has revised every page, elaborating the text where necessary to 
 cover the latest developments, and to ensure due proportion, and has greatly 
 enriched the illustrations both in number and in the use of col )rs. The names 
 of the parts are engraved directly upon them, a feature original with Gray and 
 peculiar to hi? work. The advantage is obvious. Ample directions are given 
 for dissection. The new nomenclature has been introduced in parentheses 
 following the names still in common use, an arrangement preferable to either system 
 alone. The book is thoroughly organized in its headings and with heavy type 
 catchwords in the text, so that the student readily gains a knowledge of the parts 
 in their anatomical dependence. 
 
 From the foregoing outline it is not difficult to appreciate the reasons for the 
 fact often observed that Gray is the easiest work from which to teach, to learn, 
 to prepare for examinations for collegiate degrees and state licenses, and to use 
 for reference in the practice of medicine and surgery. 
 
 Grateful acknowledgment is made by the Publishers to Dr. William T. Eckley, 
 Dr D. Kerfoot Shute, Dr. E. C. Henry, Dr. William Keiller, Dr. A. Primrose. 
 Dr Samuel H. Childs, Dr. William D. Sumpter, Dr. William Perrin Nicolson, Dr. 
 Charles L. Mix, Dr. L. F. Barker, Dr. Norman E. Jobes, Dr. John E. Hays, Dr, 
 A. C. Pole. Dr. Isaac R. Trimble, Prof. J. P. McMurrich, Dr. Daniel Da Ferte, 
 Dr. Kenneth Gonsolus, Dr, George J. Gordon, Dr. Norman Driesbach, Dr. 
 Charles A. Erdman, Dr. George H. Hoxie, Dr. Howard Hill, Prof. A. C. Eycle- 
 shymer. Dr. Peter Potter, Dr. Robert J. Terry, Dr. V. P. Blair, Dr. Joseph D. 
 Craig, Dr. James A. Gibson, Dr. Abram T. Kerr, Dr. George M. Price. Dr. Josiah 
 Medbery, Dr. Louis D. Barbot, Dr. Elmer E. Francis, Dr. Samuel S. Briggs, 
 Dr. Ira C. Chase, Dr. Henry C. Tinkham, Dr William P. Mathews, Dr. William 
 G. Doern, and many other eminent anatomists and teachers whose kindly criti- 
 cisms and intelligent suggestions have aided so materially in bringing Gray to 
 its present excellence. 
 
 (vii) 
 
CONTENTS. 
 
 DESCRIPTIVE AND SURGICAL ANATOMY. 
 
 OSTEOLOGY— THE SKELETON. 
 
 PAGE 
 
 The Skeleton 33 
 
 Number of the Bones 33 
 
 Form of Bones 33 
 
 Long Bones 33 
 
 Short Bones 33 
 
 Flat Bones 34 
 
 Irregular Bones 34 
 
 Surfaces of Bones 34 
 
 Structure of Bone 34 
 
 Bloodvessels of Bone 39 
 
 Chemical Composition of Bone .... 41 
 
 Ossification and Growth of Bone ... 42 
 
 The Vertebk.\l or Spin.\l, Column. 
 
 General Characters of a Vertebra. 
 
 The Cervical Vertebrie 49 
 
 Atlas 50 
 
 Axis 52 
 
 Seventh Cervical 53 
 
 The Thoracic or Dorsal Vertebra; ... 53 
 
 Peculiar Dorsal Vertebrae .... 55 
 
 The Lumbar Vertebrte 56 
 
 Structure of the Vertebra; 58 
 
 Development of the Vertebrsje .... 58 
 
 I3evelopnient of the Atlas 59 
 
 Development of the Axis 59 
 
 Development of the Seventh Cervical . . 60 
 Development of the Lumbar Vertebrae . 60 
 Progress of Ossification in the Spine Gener- 
 ally 60 
 
 The Sacral and Coccygeal Vertebra; . 61 
 
 Sacrum 61 
 
 Differences in the Sacrum of the 
 
 Male and Female .... 64 
 
 Peculiarities of the Sacrum 64 
 
 Coccyx 65 
 
 The Vertebral Column or Spine in General . 67 
 
 Surface Form of the Vertebral Column . . 69 
 
 Surgical Anatomy of the Vertebral Column 69 
 
 The Skull. 
 
 The Cerebral Cranium. 
 
 The Occipital Bone ; 71 
 
 The Parietal Bone 76 
 
 The Frontal Bone 79 
 
 Vertical Portion of the Frontal Bone . 79 
 Horizontal or Orbital Portion of the 
 
 Frontal Bone 81 
 
 The Temporal Bone 83 
 
 Sfjuamous Portion of the Temporal 
 
 Bone 83 
 
 The Mastoid Portion of the Temporal 
 
 Bone 85 
 
 The Petrous Portion of the Temporal 
 
 Bone 88 
 
 PACK 
 
 The Sphenoid Bone 92 
 
 The Body of the Sphenoid Bone . . 92 
 The Greater or Temporal Wings of the 
 
 Sphenoid Bone 95 
 
 The Lesser or Orbital Wings of the 
 
 Sphenoid Bone 96 
 
 The Pterygoid Processes of the Sphe- 
 noid Bone 96 
 
 The Sphenoidal Spongy Bone ... 97 
 
 The Ethmoid Bone 98 
 
 The Horizontal Lamina or Cribriform 
 
 Plate of the Ethmoid Bone ... 99 
 The Vertical or Perpendicular Lamina 
 
 or Plate of the Ethmoid Bone . 100 
 The Lateral Mass or Labyrinth of the 
 
 Ethmoid Bone 100 
 
 Development of the Cranium .... 102 
 
 The Fontanelles 102 
 
 Supernumerary or Wormian Bones . 103 
 
 Congenital Fissures and Gaps . . 104 
 
 Bones of the Face. 
 
 The Nasal Bones . 104 
 
 The Superior Maxillary Bones .... 105 
 The Body of the Superior Maxilla . 105 
 The Processes of the Superior Maxillse 109 
 Malar Process of the Superior Max- 
 illa 109 
 
 Nasal Process of the Superior Max- 
 illa 109 
 
 Alveolar Process of the Superior 
 
 Maxilla 109 
 
 Palate Process of the Superior 
 
 Maxilla 110 
 
 Changes Produced in the Upper Jaw by Age 112 
 
 The Lachrvmal Bone 112 
 
 The Malar" Bone 113 
 
 The Palate Bone 115 
 
 The Horizontal Plate of the Palate 
 
 Bone 116 
 
 The Vertical or Perpendicular Plate of 
 
 the Palate Bone 117 
 
 The Inferior Turbinated Bone . 119 
 
 The Vomer 120 
 
 The Maxillary Bone, Inferior Maxilla, Man- 
 dible or Lower Jaw 122 
 
 The Horizontal Portion or Body of the 
 
 Mandible 122 
 
 The Perpendicular Portion or Rami of 
 
 the Mandible 124 
 
 Changes Produced in the Lower Jaw by 
 
 Age ".125 
 
 The Sutures 127 
 
 The Skidl as a Whole. 
 
 The Vertex of the Skull 129 
 
 The Base of the Skull 130 
 
CONTENTS 
 
 PAGK 
 
 The Lateral Region of tlie Skull . . . 136 
 
 The Temporal Fossa 137 
 
 The Mastoid Portion 138 
 
 The Zygomatic or Infratemporal Fossa 138 
 The Spheno-maxillary or Pterygo-pala- 
 
 tine Fossa 139 
 
 The Anterior Region of the Skull . ^ 139 
 
 Orbits, Orbital Cavities or Orbital Fosste 140 
 
 The Nasal Cavity 142 
 
 Difference in Size and Form of the Cranium 146 
 
 Surface Form of the Skull 147 
 
 P'ixed Points for Measurement of the Skull 149 
 
 Surgical Anatomy of the Skull .... 149 
 
 The Hyoid or Lingual Bone 153 
 
 The Thor.^^x. 
 
 The Sternum 155 
 
 The Ribs 159 
 
 Common Characters of the Ribs . . 161 
 
 Peculiar Ribs 162 
 
 The Costal Cartilages 164 
 
 Surface Form of the Chest 165 
 
 Surgical Anatomy of the Chest . . . . 165 
 
 The Upper Extremity. 
 The Shoulder Girdle. 
 
 The Clavicle 167 
 
 Surface Form of the Clavicle . . . 170 
 
 Surgical Anatomy of the Clavicle . . 170 
 
 The Scapula 171 
 
 Surface Form of the Scapula 176 
 
 Surgical Anatomy of the Scapula . . 177 
 
 The Arm. 
 
 The Humerus .7 .177 
 
 Surface Form of the Humerus . . . 183 
 
 Surgical Anatomy of the Humerus 183 
 
 The Forearm. 
 
 The Ulna 184 
 
 Surface Form of the Ulna . . 189 
 
 The Radius 190 
 
 Surface Form of the Radius . . 192 
 Surgical Anatomy of the Radius and 
 
 Ulna 192 
 
 The Hand. 
 
 The Carpus . 193 
 
 Common Characters of the Carpal Bones 193 
 
 Bones of the Upper Row . 195 
 
 Scaphoid or Navicular Bone . . 195 
 
 Semilunar Bone 196 
 
 Cuneiform Bone 197 
 
 Pisiform Bone 197 
 
 Bones of the Lower Row . . 198 
 
 Trapezium 198 
 
 Trapezoid 198 
 
 Os Magnum 199 
 
 Unciform 199 
 
 PAGE 
 
 The Metacarpus . . 7 . ." 7 . . 200 
 Common Characters of the Metacarpal 
 
 Bones 200 
 
 PecuUar Characters of the Metacarpal 
 
 Bones 201 
 
 The Phalanges of the Hand 204 
 
 Surface Form of the Bones of the Hand 204 
 
 Surgical Anatomy of the Bones of the Hand 205 
 
 Development of the liones of the Hand . 205 
 
 The Lower Extremity. 
 The Pelvic Girdle. 
 
 The Os Innominatum 207 
 
 The Ilium 207 
 
 The Ischium 210 
 
 The Pubis 212 
 
 The Cotyloid Cavity or Acetabulum . 213 
 
 The Obturator or Thyroid Foramen . 214 
 
 The Pelvis 215 
 
 The False Pelvis 215 
 
 The True Pelvis 216 
 
 Position of the PelvLs 218 
 
 Axes of the Pelvis 218 
 
 Differences between the Male and the 
 
 Female Pelvis 219. 
 
 Surface Form of the Pelvis .... 220 
 
 Surgical Anatomy of the Pelvis . 220 
 
 The Thigh. 
 
 The Femur or Thigh Bone 221 
 
 Surface Form of the Femur . . . 229 
 
 Surgical Anatomy of the Femur . 229 
 
 The Leg. 
 
 The Patella or Knee-cap 230 
 
 Surface Form of the Patella . . .231 
 
 Surgical Anatomy of the Patella . 231 
 
 The Tibia or Shin Bone 233 
 
 Surface Form of the Tibia .... 236 
 
 The Fibula or Calf Bone 237 
 
 Surface Form of the Fibula . 239 
 
 Surgical Anatomy of Bones of the Leg 239 
 
 The Foot. 
 
 The Tarsus 242 
 
 The Calcaneus or Heel Bone . 242 
 
 The Astragalus or Ankle Bone . . 244 
 
 The Cuboid 245 
 
 Scaphoid or Navicular Bone . 246 
 
 Cuneiform or Wedge Bones .... 247 
 
 The Metatarsal Bones 249 
 
 Common Characters of Metatarsal Bones 249 
 
 Peculiar Characters of Metatarsal Bones 249 
 
 The Phalanges of the Foot 252 
 
 Development of the Foot 253 
 
 Construction of the Foot a-s a Whole . 254 
 
 Surface Form of the Foot 255 
 
 Surgical Anatomy of the Foot .... 256 
 
 Sesamoid Bones 257 
 
 THE ARTICULATIONS OR JOINTS. 
 
 Structures Composing the Joints . . 259 
 
 Bone 259 
 
 Cartilage . . . . . . . 259 
 
 Ligament.s 261 
 
 Synovial Membranes 262 
 
 Forms of Articulation: 
 
 Synarthrosis 264 
 
 Amphiarthrosis 264 
 
 Diarthrosis 265 
 
 The Kinds of Movement Admitted in 
 
 Joints 266 
 
 Ligamentous Action of Muscles .... 268 
 
 Articulations of the Trunk. 
 
 .\rticulations of the Vertebral Column . 269 
 
 Articulations of the Atlas with the Axis . 274 
 
 Articidations of the Spine with the Cranium. 
 
 Articulation of the Atlas with the Occipital 
 
 Bone .276 
 
 Articulation of the Axis with the Occipital 
 
 Bone 278 
 
 Surgical Anatomv of Articulations of the 
 
 Spine . . ■ 279 
 
CONTENTS 
 
 XI 
 
 290 
 290 
 
 290 
 292 
 292 
 
 Articulation of the Lower Jaw or the Tem- 
 
 poro-inandibular Articulation 280 
 
 Surface Form 282 
 
 Surgical Anatomy 282 
 
 Articulations of the Ribs with the Vertebrje 
 
 or tlie Costo-vortebral Articulations . . 283 
 Articulation of the Cartilages of the Ribs 
 with the Sternum, etc., or the Costo- 
 
 sternal Articulations 287 
 
 Articulations of the Cartilages of the 
 Ribs with Each Other or the Inter- 
 chondral Articulations .... 289 
 Articulations of the Ribs with tiieir (Car- 
 tilages or the Costo-chondral Artic- 
 ulations 
 
 Articulations of the Sternum .... 
 Articulations of the Vertebral Column with 
 
 the Pelvis 
 
 Articulations of the Pelvis 
 
 Articulation of the Sacrum and Ilium . 
 Ligaments passing between the Sacnnn 
 
 and Ischium 292 
 
 Articulation of the Sacrum and Coccy.x 294 
 Articulation of the Ossa Pubis . . 296 
 
 Articul.\tio.ns of the Uppek E.xtremity. 
 
 Sterno-clavicular Articulation .... 237 
 
 Surface Form 299 
 
 Surgical Anatomy 299 
 
 Acromio-clavicular Articulation or Scapulo- 
 clavicular Articulation .... 299 
 
 Surface Form 301 
 
 Surgical Anatomy 301 
 
 Proper Ligaments of the Scapula . . . 301 
 
 The Shoulder-joint 303 
 
 Surface Form of the Shoulder-joint 307 
 Surgical Anatomy of the Shoulder- 
 joint 307 
 
 The El bow- joint 308 
 
 Surface Form of tlie Elbow-joint . . 312 
 
 Surgical Anatomy of the Elbow-joint . 312 
 
 Radio-ulnar Articulation 313 
 
 Superior or Pro.ximal Radio-ulnar Artic- 
 ulation 314 
 
 Surface Form 314 
 
 Surgical Anatomy 314 
 
 Middle Radio-ulnar Ligaments . . . 314 
 Inferior or Distal Radio-ulnar Artic- 
 ulation 315 
 
 Surface Form 317 
 
 Radio-carpal or Wrist-joint 317 
 
 Surface Form of V/rist-joint . . . 318 
 
 Surgical Anatomy o" Wrist-joint . . 318 
 
 Articulations of the Carpus 319 
 
 Articulations of the First Row of Carpal 
 
 Bones 319 
 
 Articulations of the Second Row of Car- 
 pal Bones 319 
 
 Articulations of the Two Rows of Car- 
 pal Bones 320 
 
 PAGE 
 
 Carpo-metacarpal Articulations . . . . 321 
 Articulation of the Metacarpal Bone of 
 
 the Thumb with the Trapezium . 321 
 Articulations of the Metacarpal Bones of 
 
 the Four Inner Fingers witli the Carpus 322 
 Articulations of the Metacarpal Bones 
 
 with Each Other 324 
 
 Metacarpo-phalangeal Articulations . 324 
 Surface Form of Metacarpo-phalangeal 
 
 Articulations 324 
 
 Articulations of the Phalanges .... 325 
 
 Articul.\tioxs of the Lower Extre.mity. 
 
 The Hip-joint 325 
 
 Surface Form of the Hip-joint . . 333 
 
 Surgical Anatomy of the Hip-joint . 333 
 
 Tlie Knee-joint 334 
 
 Surface Form of the Knee-joint . 343 
 
 Surgical Anatomy of the Knee-joint . 343 
 
 Tibio-fibular Articulation 345 
 
 Superior Tibio-fibular Articulation 345 
 Middle Tibio-fibular Ligament or Inter- 
 osseous Membrane 346 
 
 Inferior Tibio-fibular Articulation . . 346 
 
 The Tibl-o-tar.sal Articulation or Ankle-joint 347 
 
 Surface Form of Ankle-joint . 351 
 
 Surgical Anatomy of Ankle-joint . 351 
 
 Articulations of the Tarsus 352 
 
 Articulation of the Os Calcis and A.s- 
 tragalus or the Calcaneo-astragaloid 
 
 Articulation . 352 
 
 Articulation of the Os Calcis with the 
 Cuboid or the Calcaneo-cuboid Artic- 
 ulation 353 
 
 The Ligaments connecting the Os Calcis 
 and Scaphoid or the Calcaneo- 
 
 scaphoid Articulation Ligaments 353 
 
 Surgical Anatomy 354 
 
 Articulation of the Astragalus with the 
 Scaphoid Bone or the Astragalo- 
 
 scaphoid Articulation .... 354 
 The Articulation of the Scaphoid with 
 
 the Cuneiform Bones 355 
 
 The Articulation of the Scaphoid with 
 
 the Cuboid 355 
 
 The Articulations of the Cuneiform 
 Bones with Each Other or the Inter- 
 cuneiform Articulations .... 355 
 The Articulation of the External Cunei- 
 form Bone with the Cuboid . 356 
 
 Surgical Anatomy 356 
 
 Tarso-metatarsal Articulations .... 357 
 Articulations of the Metatarsal Bones with 
 
 Each Other 358 
 
 The Synovial Membranes in the Tarsal 
 
 and Metatarsal Joints 358 
 
 Metatarso-phalangeal Articulations . . 359 
 
 Articulations of the Phalanges .... 359 
 
 Surface Form 360 
 
 Surgical Anatomy 360 
 
 THE MUSCI.es and FASCLE. 
 
 Oeneral Description of Muscles .... 361 
 
 General Description of Tendons . . . 363 
 
 General l)(>scri])ti()n of Aponeuroses . . 363 
 
 General Descrijition of Fasciae .... 364 
 
 Muscles .\xd F.\,sci.« of the Cr.\nium .\nd 
 Face. 
 
 Subdivision into Groups 365 
 
 The Cranial Region 366 
 
 Dissection 366 
 
 Superficial Fascia 366 
 
 Surgical Anatomy 367 
 
 The Occipito-frontalis 367 
 
 Surgical Anatomy 368 
 
 Tlie Auricular Region ...... 369 
 
 Dissection 369 
 
 Attrahens Auriculam or Aurem . 369 
 
 Attollens Auriculam or Aurem . . . 369 
 
 Retrahens Auriculam or Aurem . . 369 
 
 The Palpebral Region 370 
 
 Dissection 370 
 
 Orbicularis Palpebraruni .... 370 
 
 Corrugator Supercilii 371 
 
 Levator Palpebral 371 
 
 Tensor Tarsi or Horner's Muscle . . 371 
 
 The Orbital Region 372 
 
 Levator Palpebrse Superioris . . . 372 
 
 Superior Rectus 373 
 
 Inferior Rectus 373 
 
xu 
 
 CONTENTS 
 
 The Orbital Region — 
 
 External Rectus 373 
 
 Superior Oblique 373 
 
 Inferior Oblique 374 
 
 Fascia; of the Orbit 374 
 
 Surgical Anatomy 575 
 
 The >Jasal Region 575 
 
 Pyraniidalis Nasi 375 
 
 Levator Labii Superioris Alaeque Nasi 375 
 
 Dilator Naris Posterior 376 
 
 Dilator Naris Anterior 376 
 
 Compressor Nasi 376 
 
 Compressor Narium Minor .... 376 
 
 Depressor Alas Nasi 376 
 
 The Superior Maxillary Region .... 376 
 
 Levator Labii Superioris .... 376 
 
 Levator Anguli Oris 377 
 
 Zygomaticus Major 377 
 
 Zygomaticus Minor 377 
 
 The Mandibular Region 377 
 
 Dissection 377 
 
 Levator Labii Inferioris or Levator 
 
 Menti 378 
 
 Depressor Labii Inferioris or Quadratus 
 
 Menti 378 
 
 Depre.ssor Anguli Oris or Triangularis 
 
 Menti 378 
 
 The Intermaxillary Region 378 
 
 Dissection 378 
 
 Orbicularis Oris 378 
 
 Buccinator 380 
 
 Risorius or Santorini's Muscle . . . 380 
 
 The Tenaporo-mandibular Region . 381 
 
 Masseteric Fascia 381 
 
 Masse ter Muscle 381 
 
 Temporal Fascia 381 
 
 Dissection 382 
 
 Temporal Muscle 382 
 
 The Pterygo-mandibular Region 383 
 
 Dissection 383 
 
 External Pterygoid Muscle .... 383 
 
 Internal Pters'goid Muscle .... 383 
 
 Surface Form of Muscles of Head and Face 385 
 
 MUSCLE.S AND FaSCIvI'" OF THE NeCK. 
 
 Subdivision in Groups . . . . 385 
 
 The Superficial Cervical Region .... 386 
 
 Dissection 386 
 
 Superficial Cervical Fascia .... 386 
 
 Platysma Myoides 386 
 
 Deep Cervical Fascia 387 
 
 Surgical Anatomy 380 
 
 St«mo-mastoid orSterno-cleido-mastoid 389 
 
 Surface Form 391 
 
 Surgical Anatomy 391 
 
 The Infra-hyoid Region 391 
 
 Dissection 391 
 
 Stemo-hyoid 391 
 
 Sterno-thvroid 392 
 
 Thyro-liybid 392 
 
 Omo-hyoid 393 
 
 The Supra-iivoid Region 393 
 
 Dissection 393 
 
 Diga-stric 393 
 
 Stvlo-hvoid 394 
 
 Mylo-hyoid 394 
 
 Dissection 395 
 
 Genio-hyoid 395 
 
 The Lingual" Region . . . . . . 396 
 
 Di-ssection 396 
 
 Genio-hyo-glossus 396 
 
 Hyo-glossus 397 
 
 Chondro-glossus 397 
 
 Stylo-glossus 397 
 
 Palato-glossus or Constrictor Isthmi 
 
 Faucium 398 
 
 Muscular Substance of the Tongue . 398 
 
 Surgical Anatomy 400 
 
 The Pharyngeal Region 400 
 
 Dissection 400 
 
 Inferior Constrictor 400 
 
 Middle Constrictor 401 
 
 Superior Constrictor 401 
 
 Stylo-pliaryngeus 403 
 
 The Palatal Region 403 
 
 Dissection 403 
 
 Levator Palati 4(J3 
 
 Circumflexus or Tensor Palati . . . 404 
 
 Palatine Aponeurosis 404 
 
 Azygos Uvula' 405 
 
 Palato-glossus or Constrictor Isthmi 
 
 Faucium 405 
 
 Palato-pharyngeus 405 
 
 Salpingo-pharyngeus 405 
 
 Surgical Anatomy 406 
 
 The Anterior Vertebral Region .... 406 
 Rectus Capitis Anticus Major or Longus 
 
 Capitis 406 
 
 Rectus Capitis Anticus Minor . . 407 
 
 Rectus Capitis Lateralis .... 407 
 
 Longus Colli 407 
 
 The Lateral Vertebral Region .... 408 
 
 Scalenus Anticus 408 
 
 Scalenus Posticus 409 
 
 Surface Form of Muscles of the Neck . . 409 
 
 Muscles and Fasci-k of the Trunk. 
 
 Subdivision into Groups 41t) 
 
 Muscles of the Back. 
 
 Subdivision into Groups 410 
 
 The Urst Layer 410 
 
 Dissection 410 
 
 Superficial Fascia 411 
 
 Deep Fascia 411 
 
 Trapezius 411 
 
 Ligamentum Nuchse 413 
 
 Latissimus Dorsi 413 
 
 The Second Layer 414 
 
 Dissection 414 
 
 Levator Anguli SrapulsD .... 414 
 
 Rhomboideus Minor 414 
 
 Rhomboideus Major 414 
 
 The Third Layer 415 
 
 Dissection 415 
 
 Serratus Posticus Superior . . . . 415 
 
 Serratiis Posticus Inferior . . . 415 
 
 Vertebral Aponeurosis 416 
 
 Lumbar Fascia or Aponeurosis . 416 
 
 Splenius 416 
 
 Splenius Capitis 416 
 
 Splenius Colli 416 
 
 The Fourth Layer 417 
 
 Dissection 417 
 
 Erector Spinse 417 
 
 lUo-costalis or Sacro-lumbalis . 419 
 Musculus Accessorius ad Ilio-cos- 
 
 talem 419 
 
 Cervicalis Ascendens .... 419 
 
 Longissimus Dorsi 419 
 
 Transversalis Cervicis or Trans- 
 
 versalis Colli 419 
 
 Trachelo-mastoid 419 
 
 Spinalis Dorsi 419 
 
 Spinalis Colli 420 
 
 Complexus 420 
 
 The Fifth Layer 420 
 
 Dissection 420 
 
 Semispinalis Dorsi 421 
 
 Semispinalis Colli 421 
 
 Multifidus Spina; 421 
 
 Rotatores Spinse 421 
 
 Supraspinales 421 
 
 Interspinales 421 
 
 Extensor Coccygis 422 
 
 Intertransversales 422 
 
 Rectus Capitis Posticus Major . . 422 
 
CONTENTS 
 
 The Fifth Layer— 
 
 Rectus Capitis Posticus Minor . 
 Obliquus Capitis Inferior 
 Obliquus Capitis Superior 
 
 Surface Form of Muscles of the Back 
 
 PAGE 
 
 422 
 422 
 422 
 424 
 
 Muscles and Fasciae of the Thorax. 
 
 Intercostal Fascia 424 
 
 Intercostal Mviscles 425 
 
 External Intercostals 425 
 
 Internal Intercostals 425 
 
 Infracostales 425 
 
 Triangularis Sterni 425 
 
 Levatores Costarum 426 
 
 Diaphragm 427 
 
 Ligainentum Arcuatura Internum . . 427 
 
 Ligamentum Arcuatum Externum . 427 
 
 Central Tendon of the Diaphragm . . 429 
 
 The Openings of the Diaphragm . 429 
 
 Muscles of Inspiration and Expiration 432 
 
 Muscles of the Abdomen. 
 
 The Superficial Muscles of the Abdomen . 432 
 
 Dissection 432 
 
 Superficial Fascia 433 
 
 Deep Fascia 433 
 
 External or Descending Oblique . 433 
 Aponeurosis of External Oblitiue . 434 
 External Abdominal Ring . . 436 
 External Pillar or Inferior Crus . 436 
 Internal Pillar or Superior Crus . 436 
 Intercolumnar Fibres .... 436 
 Poupart's Ligament .... 436 
 Gimbernat's Ligament 437 
 Triangular Fascia or CoUes's Liga- 
 ment 437 
 
 Ligament of Cooper .... 437 
 
 Suspensory Ligament of the Penis 437 
 
 Suspensory Ligament of the Clitoris 437 
 
 Internal or Ascending Oblique . . . 437 
 
 Aponeurosis of Internal Oblique . 439 
 
 Cremaster Muscle 439 
 
 Transversalis 442 
 
 Dissection 442 
 
 Rectus Abdominis 442 
 
 Pyramidalis 444 
 
 The Linea Alba 444 
 
 The Lineae Semilunares . . . 445 
 
 The Lineae Trans\'ers;e .... 445 
 
 The Transversalis Fascia .... 445 
 
 Internal or Deep Abdominal Ring . 446 
 
 The Inguinal or Spermatic Canal . . 448 
 
 The Deep Crural Arch 448 
 
 Cooper's Ligament 448 
 
 Surface Forms of Muscles of the Abdomen 448 
 
 The Deep Muscles of the Abdomen . 449 
 
 The Fascia Covering the Quadratus 
 
 Lumborum 449 
 
 Quadratus Lumborum 449 
 
 Muscles of the Pelvic Outlet: 
 
 The Muscles of the Ischio-rectal Region . 449 
 
 The Corrugator Cutis Ani .... 449 
 
 External Sphincter Ani 450 
 
 Internal Sphincter Ani 451 
 
 Levator Ani 451 
 
 Pubococcygeus Muscle .... 452 
 
 Iliococcygeus Muscle .... 454 
 
 Coccygeus 455 
 
 The Muscles and Fasciae of the Perinaeum in 
 
 the Male 455 
 
 Superficial Fascia 455 
 
 The Central Tendinous Point of the 
 
 Perinaeum 456 
 
 Transversus Perinei Superficialis . . 457 
 
 Accelerator Urinae 457 
 
 Erector Penis 458 
 
 Triangular Ivigament .... 458 
 
 Compressor or Constrictor Urethras . 460 
 
 PAGE 
 
 The Muscles of the Perinaeum in the Female 460 
 
 Transversus Perinei Superficialis . . 460 
 
 Sphincter Vaginje 461 
 
 Erector Clitoridis 461 
 
 Triangular Ligament .... 462 
 
 Compressor Urethras 462 
 
 Muscles and Fascitk of the Uppeu 
 Extremity. 
 
 Subdivision into Groups 462 
 
 Dissection of Pectoral Region and Axilla . 463 
 
 The Mziscles and Fascice of the Thoracic 
 Region. 
 
 The Anterior Thoracic Region .... 463 
 
 Superficial Fascia 463 
 
 Deep Fascia 463 
 
 Pectoralis Major 464 
 
 Dissection 467 
 
 Costo-coracoid Membrane or Clavipec- 
 
 toral P^ascia 467 
 
 Pectoralis Minor 468 
 
 Subclavius 468 
 
 The Lateral Thoracic Region .... 468 
 
 Serratus Magnus 468 
 
 Surgical Anatomy 469 
 
 Dissection 470 
 
 Muscles and Fascia: of Shoulder and Arm. 
 
 Superficial Fascia 470 
 
 Deep Fascia 470 
 
 The Acromial Region 470 
 
 Deep Fascia 470 
 
 Deltoid 470 
 
 Surgical Anatomy 471 
 
 The Anterior Scapular Region .... 471 
 
 Dissection 471 
 
 The Subscapular Fascia 471 
 
 Sub.scapularis 471 
 
 The Posterior Scapular Region .... 472 
 
 Dissection 472 
 
 Supraspinatus Fascia 472 
 
 Supraspinatus Muscle 472 
 
 Infraspinatus Fascia 472 
 
 Infraspinatus Muscle 472 
 
 Teres Minor 473 
 
 Teres Major 474 
 
 The Mii.icles and Fasciae of the Arm. 
 
 The Anterior Humeral Region .... 474 
 
 Dissection 474 
 
 Deep Fascia 474 
 
 Coraco-brachialis 475 
 
 Biceps or Biceps Flexor Cubiti . 475 
 
 Brachialis Anticus 476 
 
 The Postesrior Humeral Region .... 477 
 
 Triceps or Triceps Extensor Cubiti 477 
 
 Subanconeus 478 
 
 Surgical Anatomy 478 
 
 Muscles and Fascice of the Forearm. 
 
 Dissection 478 
 
 Deep Fascia 478 
 
 The Anterior Radio-ulnar Region . 479 
 
 The Superficial Layer 479 
 
 Pronator Radii Teres .... 479 
 
 Surgical Anatomy .... 479 
 
 Flexor Carpi Radialis .... 479 
 
 Palmaris Longus 480 
 
 Flexor Carpi Ulnari.s .... 480 
 
 Flexor Sublimis Digitorum 481 
 
 The Deep Layer 482 
 
 Dissection 482 
 
 Flexor Profundus Digitorum . 482 
 
 Flexor Longus Pollicis .... 482 
 
 Pronator Quadratus .... 483 
 
 Surgical Anatomy 484 
 
XIV 
 
 CONTENTS 
 
 The Radial Region 484 
 
 Dissection 484 
 
 Supinator Longus 484 
 
 Extensor Carpi Radialis Longior . . 485 
 
 Extensor Carpi Radialis Brevior . . 485 
 
 The Posterior Radio-uhiar Region . . 486 
 
 The Superficial Layer 486 
 
 Extensor Communis IJigitoruni . 486 
 
 Extensor Minimi Digiti . . . 487 
 
 Extensor Carpi Ulnaris . . . 487 
 
 Anconeus 487 
 
 The Deep Layer 487 
 
 Supinator Radii Brevis . 487 
 
 Extensor Ossis Metacarpi PoUicis 489 
 
 Extensor Brevis Pollicis . . . 489 
 
 Extensor Longus Pollicis . . . 489 
 
 Extensor Indicis 490 
 
 Surgical Anatomy 490 
 
 Muscles and Fasciae of the. Hand. 
 
 Dissection 491 
 
 Ligamentum Carpi Volare 491 
 
 Anterior Annular Ligament 491 
 
 The Synovial Membranes of the Flexor Ten- 
 dons at the Wrist 492 
 
 Surgical Anatomy 492 
 
 Burs* about the Hand and Wrist . . . 492 
 
 Posterior Annular Ligament 493 
 
 The Deep Palmar Fascia 493 
 
 The Superficial Transverse Ligament of 
 
 the Fingers 494 
 
 Surgical Anatomy 494 
 
 The Radial Region 495 
 
 Abductor Pollicis 495 
 
 Opponens Pollicis 496 
 
 Flexor Brevis Pollicis 497 
 
 Adductor Obliquus Pollicis .... 497 
 
 Adductor Transversus Pollicis . . . 497 
 
 The Ulnar Region 498 
 
 Palmaris Brevis 498 
 
 Abductor Minimi Digiti 498 
 
 Flexor Brevis Minimi Digiti . . . 498 
 
 Opponens Minimi Digiti .... 498 
 
 T,he Middle Palmar Region 499 
 
 Lumbricales 499 
 
 Interossei 499 
 
 Surface Form of Muscles of the Upper Ex- 
 tremity 500 
 
 Surgical Anatomy of Muscles of the Upper 
 
 Extremity ;:03 
 
 Muscles and Fasci.e of the Lower 
 
 Extremity. 
 
 Subdivision into Groups 507 
 
 Muscles and Fascice of the Iliac Region. 
 
 Dissection 508 
 
 Iliac Fascia 508 
 
 Psoas Magnus 509 
 
 Psoas Parvus 510 
 
 Iliacus 510 
 
 Surgical Anatomy 511 
 
 Muscles and Fasciae of the Thigh. 
 
 The Anterior Femoral Region . . . . 512 
 
 Dissection 512 
 
 Superficial Fascia 512 
 
 Deep Fascia or Fascia Lata . . . 513 
 
 Surgical Anatomy 515 
 
 Tensor Fasciae Femoris 515 
 
 Sartorius 516 
 
 Quadriceps Extensor 516 
 
 Rectus J'emoris 516 
 
 Vastus Extern us 517 
 
 Vastus Intern us 517 
 
 Crureus 517 
 
 Subcrureus 518 
 
 Surgical Anatomy 518 
 
 PAGK 
 
 The Internal Femoral Region .... 519 
 
 Dissection 51& 
 
 Gracilis 519 
 
 Pectineus 519 
 
 Adductor Longus 519 
 
 Adductor Brevis 520 
 
 Adductor Magnus 520 
 
 Hunter's Canal 521 
 
 Surgical Anatomy 522 
 
 The Muscles and Fasciae of the Hip. 
 
 The Gluteal Region 522 
 
 Dissection .522 
 
 Gluteus Maximus 523 
 
 Gluteus Medius 523 
 
 Gluteus Minimus 523 
 
 Pyriformis 524 
 
 Obturator Internus 525 
 
 GemelU 526 
 
 Gemellus Superior 526 
 
 Gemellus Inferior 527 
 
 Quad rat us Femoris 527 
 
 Obturator Externus 528 
 
 Surgical Anatomy 528 
 
 The Posterior Femoral Region .... 529 
 
 Dissection 529 
 
 Biceps or Biceps Flexor Cruris . . . 529 
 
 Semitendinosus 530 
 
 Semimembranosus 530 
 
 Surgical Anatomy 531 
 
 Muscles and Fasciae of the Leg. 
 
 The Anterior Tibio-fibular Region . . . 531 
 
 Dissection 532 
 
 Deep Fascia of the Leg 532 
 
 Tibialis Anticus 532 
 
 Extensor Proprius Hallucis .... 532 
 
 Extensor Longus Digitorum . . . 533 
 
 Peroneus Tertius 534 
 
 The Posterior Tibio-fibular Region . . . 534 
 
 Dissection 534 
 
 The Superficial Layer 534 
 
 Gastrocnemius 534 
 
 Soleus 535 
 
 Tendo-Achillis 535 
 
 The Deep Layer 537 
 
 Dissection 537 
 
 Deep Transverse Fascia . . . 537 
 
 Popliteus 537 
 
 Flexor Longus Hallucis . . . 538 
 
 Flexor Longus Digitorum . . . 538 
 
 Tibialis Posticus 538 
 
 The Fibular Region 539 
 
 Dissection 539 
 
 Peroneus Longiis 539 
 
 Peroneus Brevis 540 
 
 Surgical Anatomy of Tendons around Ankle 541 
 
 Muscles and Fascice of the Foot. * 
 
 Dissection 541 
 
 Anterior Annular Ligament 541 
 
 Internal Annular Ligament 542 
 
 External Annular Ligament 542 
 
 Dissection of the Sole of the Foot . . . 542 
 
 Plantar Fascia 542 
 
 Central Portion of Plantar Fascia . 542 
 
 Lateral Portions of Plantar Fascia . 543 
 
 Bursse about the Ankle and Pool . 543 
 
 Surgical Anatomy 543 
 
 The Dorsal Region 543 
 
 Fascia 543 
 
 Extensor Brevis Digitonun .... 543 
 
 The Plantar Region 544 
 
 The First Layer 544 
 
 Dissection 544 
 
 Abductor Hallucis 544 
 
 Flexor Brevis Digitorum . . 544 
 Fibrous Sheaths of the Flexor 
 
 Tendons 545 
 
 Abductor Minimi Digiti . . . 545 
 
CONTENTS 
 
 XV 
 
 PAOK 
 
 The Plantar Region — 
 
 The Second Layer . ; 7 ". . . 546 
 
 Flexor Accessorius 546 
 
 Lumbricales 546 
 
 The Third Layer 546 
 
 Flexor Brevis Hallucis .... 546 
 
 Adductor Obliquus Hallucis . 546 
 
 Flexor Brevis Minimi Digiti . 547 
 
 Adductor Tran.sversus Hallucis 548 
 
 PAaB 
 
 The Plantar Region — 
 
 The P'ourth Layer 548 
 
 Interossei Muscles 548 
 
 rjorsal Interossei .... 548 
 Plantar Interossei . . 548 
 Surface Form of Muscles of the Lower Ex- 
 tremity 549 
 
 Surgical Anatomy of Muscles of the Lower 
 
 Extremity 551 
 
 THE Br>OOD-V.\SCULAR SYSTEM. 
 
 The Circulation of the Blood .... 555 
 
 The Cavity of the Thorax 556 
 
 The Upper Opening of the Thorax . . 556 
 
 The Lower Opening of the Thorax . . . 556 
 
 The Pericardium. 
 
 Structure of the Pericardium .... 558 
 
 Fibrous Layer 558 
 
 Serous Pericardium 560 
 
 Arteries of the Pericardium .... 561 
 
 Nerves of the Pericardium .... 581 
 
 The Vestigial Fold of the Pericardium 561 
 
 Surgical Anato.-ny of the Pericardium . . 561 
 
 The Heart. 
 
 Position of the Heart 562 
 
 Size and Weight of the Heart .... 564 
 
 Capacity of the Cavities of the Heart . . 564 
 
 Fat upon the Heart 564 
 
 Component Parts of the Heart .... 565 
 
 Right Auricle 565 
 
 Left Auricle 568 
 
 Right Ventricle 569 
 
 Left Ventricle 571 
 
 Structure of the Heart 574 
 
 Endocardium 574 
 
 Myocardium 574 
 
 Muscular Structure of the Heart . . 575 
 
 Fibres of the Auricles .... 575 
 
 Fibres of the Ventricles . . . 575 
 
 Ves.sels and Nerves of the Heart . . . 577 
 
 Surface Form of the Heart 577 
 
 Surgical Anatomy of the Heart .... 578 
 
 Peculiarities of Vascular System in Foetus. 578 
 
 The Foramen Ovale 578 
 
 The Eustachian Valve 578 
 
 The Ductus Arteriosus 579 
 
 The Umbilical Arteries 579 
 
 P'cetal Circulation 579 
 
 Changes in the Vascular System at Birth . 581 
 
 THE ARTERIES. 
 
 Distribution of the Arteries ." 7 .' . 583 
 
 Anastomosis of the Arteries 583 
 
 Histology of the Capillaries and Arteries . 584 
 
 Blood-vessels of the Blood-vessel Wall 586 
 
 Lymphatics of Arteries 586 
 
 Nerves of Arteries 586 
 
 Arterial Sheath 586 
 
 Pulmonary Artery. 
 
 Right Pulmonary Artery 587 
 
 Left Pulmonary Artery 587 
 
 The Aorta. 
 
 The Ascending Aorta. 
 
 Relations of the Ascending Aorta 589 
 
 Branches of the Ascending Aorta . . 590 
 
 The Coronary Arteries 590 
 
 Right Coronary Artery 590 
 
 Left Coronary Artery 590 
 
 Peculiarities of Coronary Arteries . 591 
 
 The Arch of the Aorta. 
 
 Relations of the Arch of the Aorta . 591 
 
 Peculiarities of the Arch of the Aorta . 591 
 
 Surgical Anatomy of the Arch of the Aorta 592 
 
 Branches of the Arch of the Aorta . 593 
 
 Peculiarities of the Branches . 593 
 
 The Innominate Artery 593 
 
 Relations 593 
 
 Branches 594 
 
 Thyroidea Ima 594 
 
 Peculiarities . 594 
 
 Surgical Anatomy 594 
 
 Arteries of the Head and Neck. 
 
 The Common Carotid Artery. 
 
 Relations of the Common Carotid Artery . 596 
 
 Peculiarities of the Common Carotid Arterv 598 
 
 Surface Marking of the Common Carotid 
 
 Artery 593 
 
 Surgical Anatomy of the Common Carotid 
 
 Artery 593 
 
 The External Carotid Artery .... 600 
 
 Relations 600 
 
 Surface Marking 601 
 
 Surgical Anatomy 601 
 
 Branches 601 
 
 Superior Thyroid Artery 601 
 
 Branches ...... 602 
 
 Surgical Anatomy .... 603 
 
 Lingual Artery 603 
 
 Relations 603 
 
 Branches 603 
 
 Surgical Anatomy .... 604 
 
 Facial or External Maxillary Artery 604 
 
 Relations '. 605 
 
 Branches 60.5 
 
 Peculiarities 607 
 
 Surgical Anatomy .... 607 
 
 Occipital Artery . . . 608 
 
 Branches 609 
 
 Posterior Auricular Arterv 609 
 
 Branches 610 
 
 Ascending Pharyngeal Artery 610 
 
 Branches " 610 
 
 Surgical .\natomy . . .611 
 
 Superficial Temporal Artery . .611 
 
 Branches 611 
 
 Surgical Anatomy . . .612 
 
 Internal Maxillary Art«ry . 612 
 
 Branches of First Portion 613 
 
 Surgical Anatomy 614 
 
 Branches of Second Portion . 614 
 
 Branches of Third Portion 615 
 
 Surgical Anatomy 615 
 
 Surgical Anatomy of the Triangles of the 
 
 Neck 616 
 
 Anterior Triangle of the Nock . 616 
 
 Posterior Triangle of the Neck . 618 
 
CONTENTS 
 
 PAGE 
 
 The Internal Carotid Artery . . 619 
 
 Cervical Portion 620 
 
 Relations 620 
 
 Petrous Portion 620 
 
 Cavernous Portion 621 
 
 Cerebral Portion 621 
 
 Peculiarities 621 
 
 Surgical Anatomy 621 
 
 Branches 621 
 
 Tympanic 622 
 
 Arteriaj Receptaculi .... 622 
 
 Anterior Meningeal .... 622 
 
 Ophthahnic 622 
 
 Branches 622 
 
 Anterior Cerebral 626 
 
 Branches 626 
 
 Middle Cerebral 627 
 
 Branches 628 
 
 Posterior Communicating . . 628 
 
 Anterior Choroid 628 
 
 The Bloodvessels of the Brain. 
 
 The Central Ganglionic System .... 630 
 The Cortical Arterial System . . . .631 
 
 Arteries of the Upper Extremity. 
 
 The Subclavian Artery. 
 
 First Part of the Right Subclavian Artery . 632 
 
 Relations 632 
 
 First Part of the Left Subclavian Artery . 633 
 
 Relations 633 
 
 Second and Third Parts of Subclavian Artery 633 
 
 Relations 634 
 
 Third Portion of the Subclavian Artery . 634 
 
 Peculiarities of the Subclavian Artery . . 635 
 
 Surface Marking of the Subclavian Artery . 635 
 
 Surgical Anatomy of the Subclavian Artery 635 
 
 Branches of the Subclavian Artery . . . 637 
 
 Vertebral Artery 637 
 
 Relations 637 
 
 Branches 638 
 
 Surgical Anatomy 639 
 
 Basilar Artery 639 
 
 Branches 639 
 
 Circle of AA'illis 640 
 
 Tliyroid Axis 640 
 
 Branches 641 
 
 Internal Mammary Artery .... 643 
 
 Relations 644 
 
 Branches 644 
 
 Surgical Anatomy 644 
 
 Superior Intercostal Artery . . . . 645 
 
 Deep Cervical Branch .... 645 
 
 Surgical Anatomy of the Axilla .... 645 
 
 Boundaries 645 
 
 Contents 646 
 
 Surgical Anatomy 646 
 
 The Axillary Artery. 
 
 Relations of the Axillary Artery 7 . . 648 
 
 Peculiarities of the Axillary Artery 649 
 
 Surface Marking of the Axillary Artery 649 
 
 Surgical Anatomy of the Axillary Arterj' . 649 
 
 Branches of the Axillary Artery . . . 650 
 
 Superior Thoracic Artery .... 650 
 Acromial Thoracic Arterv or Thoracic 
 
 Axis ........ 651 
 
 Branches 651 
 
 Long Thoracic or External Mammary 
 
 Artery 651 
 
 Alar Thoracic Artery 651 
 
 Subscapular Artery ." 651 
 
 Circumflex Arteries . ' 651 
 
 The Brachial Artery. 
 
 Relations of the Brachial Artery . . . 652 
 
 Surgical Anatomy of the Bend of the Elbow 653 
 
 Peculiarities of the Brachial Artery . 653 
 
 Surface Marking of the Brachial Artery 654 
 
 Surgical Anatomy of the Brachial Artery . 654 
 
 PAGE 
 
 Branches of the Brachial Artery . . 655 
 
 Superior Profunda Artery .... 655 
 
 Nutrient Artery ........ 656 
 
 Inferior Profunda Artery .... 656 
 
 Anastomotica Magna 656 
 
 Muscular Branches 656 
 
 The Anastomosis around the Elbow-joint 657 
 
 The Radial Artery 557 
 
 Relations 657 
 
 The Deep Palmar Arch 658 
 
 Peculiarities 658 
 
 Surface Marking 658 
 
 Surgical Anatomy 658 
 
 Branches 659 
 
 Radial Recurrent 659 
 
 Muscular Branches 659 
 
 Anterior Radial Carpal . . 659 
 
 Superficialis Vola; 659 
 
 Posterior Radial Carpal . . 659 
 
 Dorsalis Pollicis 659 
 
 Dorsalis Indicis 659 
 
 Princeps Pollicis 660 
 
 Radialis Indicis 660 
 
 Perforating Arteries .... 660 
 
 Palmar Interosseous .... 660 
 
 Palmar Recurrent Branches . 660 
 
 The Ulnar Artery 660 
 
 Relations 661 
 
 Peculiarities 661 
 
 Surface Marking 661 
 
 Surgical Anatomy 661 
 
 Branches 662 
 
 Anterior Ulnar Recurrent . . . 662 
 
 Posterior Ulnar Recurrent 662 
 
 Interosseous Artery .... 662 
 
 Muscular Branches 663 
 
 Anterior Carpal 663 
 
 Posterior Carpal 663 
 
 Deep Palmar Arch 664 
 
 Superficial Palmar Arch . . 664 
 
 Relations 664 
 
 Branches 664 
 
 Surface Marking .... 665 
 
 Surgical Anatomy .... 665 
 
 Arteries of the Trunk. 
 
 The Descending Aorta. 
 
 The Thoracic Aorta 665 
 
 Relations 665 
 
 Surface Marking 666 
 
 Surgical Anatomy 666 
 
 Branches 666 
 
 Bronchial Arteries 666 
 
 (Esophageal Arteries .... 666 
 
 Pericardiac Arteries .... 666 
 
 Posterior Mediastinal Arteries . 666 
 
 Interco.stal Arteries and Branches 667 
 
 Surgical Anatomy .... 668 
 
 The Abdominal Aorta 668 
 
 Relations 669 
 
 Surface Marking 670 
 
 Surgical Anatomy 670 
 
 Branches 671 
 
 The C(»liac Axis or Artery . . 671 
 
 Relations 671 
 
 Branches 671 
 
 Surgical Anatomy .... 674 
 
 The Superior Mesenteric Artery 675 
 
 Branches 675 
 
 Blood-supply of the Right Iliac 
 
 Fossa 676 
 
 The Inferior Mesenteric Artery . 677 
 
 Suprarenal Artery 678 
 
 The Renal Arteries .... 678 
 
 The Spermatic Arteries 679 
 
 The Ovarian Arteries .... 680 
 
 The Inferior Phrenic Arteries . . 680 
 
 The Lumbar Arteries .... 680 
 
 Branches 681 
 
CONTENTS 
 
 The Comtrion Iliac Arlrrics. 
 Branches of Coinuiou Iliac Arteries 
 Peculiarities of Coininou Iliac Arteries. 
 Surface Marking of Conunon Iliac Arteries 
 Surgical Anatomy of Common Iliac Arteries 
 
 The Internal Iliac Artery 
 
 Relations 
 
 Peculiarities 
 
 Surgical Anatomy 
 
 Branches 
 
 Superior Vesical Artery 
 MidfUe Vesical Artery .... 
 Inferior Vesical .\rtery .... 
 Middle Ilseniorrhoidal .Vrtery 
 
 Uterine Artery 
 
 Vaginal Artery 
 
 Surgical Anatomy .... 
 
 Obturator Artery 
 
 Branches 
 
 Peculiarities 
 
 Internal Pudic Artery .... 
 
 Relations 
 
 Peculiarities 
 
 Surgical Anatomy .... 
 
 Branches 
 
 Sciatic Artery 
 
 Branches 
 
 Lateral Sacral Artery .... 
 
 Branches 
 
 Gluteal Artery 
 
 Branches 
 
 Surface Marking .... 
 Surgical .\natomy .... 
 
 The External Iliac Artery 
 
 Relations 
 
 Surface Marking 
 
 Surgical Anatomy 
 
 Branches 
 
 Int,eriial or Deep Epigastric .\rt(!ry 
 
 Branches 
 
 Peci'.liarities 
 
 Surgical .-Vnat-omy .... 
 Deep Circumflex Iliac Artery . 
 
 682 
 
 682 
 
 682 
 
 682 
 
 683 
 
 683 
 
 685 
 
 685 
 
 686 
 
 686 
 
 686 
 
 686 
 
 687 
 
 687 
 
 687 
 
 688 
 
 688 
 
 ()88 
 
 68!) 
 
 689 
 
 690 
 
 690 
 
 690 
 
 690 
 
 692 
 
 693 
 
 693 
 
 693 
 
 694 
 
 694 
 
 694 
 
 694 
 
 694 
 
 694 
 
 695 
 
 695 
 
 696 
 
 696 
 
 696 
 
 696 
 
 697 
 
 697 
 
 Arteriks of the Lower Extremity. 
 The Femoral Artery. 
 
 Scarpa's Triangle 697 
 
 Hunter's ('anal or the .\dductor Canal . 698 
 
 The Common Femoral .\rtery .... 699 
 
 Relations 700 
 
 The Superficial Femoral Artery .... 700 
 
 Relations " . . . . 700 
 
 Peculiarities 700 
 
 Surface Marking 701 
 
 Surgical Anatomy ...... 701 
 
 Branches 704 
 
 Superficial Epigastric .... 704 
 
 Superfici.al Circumflex Iliac . 704 
 
 Superficial External Pudic . . 704 
 
 Deep External Pudic .... 704 
 
 Deep Femoral or Profunda Femoris 704 
 
 Relations 704 
 
 Branches 705 
 
 The Superficial Femoral Artery — 
 
 Muscular Branches 707 
 
 Auastomotica Magna .... 707 
 
 Branches 707 
 
 The Popliteal Artery. 
 
 The Popliteal Space 707 
 
 Dissection 707 
 
 Boundaries 707 
 
 Position of Contained Parts . . . 708 
 
 PecuUarities 70e 
 
 Surface Marking 709 
 
 Surgical Anatomy 709 
 
 Branches 710 
 
 Superior Muscular Branches . 710 
 
 Inferior Muscular Branches . 710 
 Cutaneous liranches . . .710 
 
 Superior Articular Arteries . . 710 
 Azygos Articular Artery . .711 
 
 Inferior Articular Arteries . . 711 
 
 Circumpatellar Anastomosis . . 711 
 
 The Anterior Tibial Artery 711 
 
 Relations 711 
 
 Peculiarities 712 
 
 Surface Marking 712 
 
 Surgical Anatomy 712 
 
 Branches 712 
 
 Posterior Recurrent Tibial 713 
 
 Superior Fibular 713 
 
 Anterior Recurrent Tibial . 713 
 
 Muscular Branches 713 
 
 Malleolar .\rteries 713 
 
 The Dorsalis Pedis Artery 714 
 
 Relations 714 
 
 Peculiarities 715 
 
 Surface Marking 715 
 
 Surgical Anatomy 715 
 
 Branches 715 
 
 Cutaneous Branches 715 
 
 Tarsal Artery 715 
 
 Metatarsal .\rtery 715 
 
 Communicating .\rtery . . . 716 
 
 The Posterior Tibial Artery 716 
 
 Relations 716 
 
 Peculiarities 717 
 
 Surface Marking 717 
 
 Surgical Anatomy 717 
 
 Branches 717 
 
 Peroneal Artery 717 
 
 Relations 718 
 
 Peculiarities 718 
 
 Branches 718 
 
 Cutaneous Branches . . . . 718 
 
 Nutrient Artery 719 
 
 Muscular Branches 719 
 
 Communicating Branch . 719 
 Malleolar or Internal Malleolar 
 
 Artery 719 
 
 Internal Calcanean Arteries . 719 
 
 Internal Plantar Artery . 719 
 
 External Plantar Artery . . 720 
 
 Surface Marking .... 720 
 
 Surgical Anatomy .... 720 
 
 Branches 720 
 
 THE VEINS. 
 
 Subdivisions of the Veins 721 
 
 Anastomosis of Veins 722 
 
 Histology of the Veins 723 
 
 The Superficial or Cutaneous Veins . . . 723 
 
 The Deep Veins 723 
 
 The Pulmon.\ry Vkins. 
 
 The Systemic Veins. 
 
 Vein.s of the Head and Neck. 
 
 Veins of the p'.xt,<;rior of the Head and Face 725 
 
 Veins of the Exterior of the Head and Face — 
 
 Frontal Vein 725 
 
 Supraorbital Vein 726 
 
 Angular Vein 726 
 
 Anterior Facial Vein ..... 726 
 
 Common Facial Vein 726 
 
 Superficial Temporal Vein .... 727 
 The Pterygoid Plexus and the Internal 
 
 Maxillary Vein 727 
 
 Temporo-maxillary Vein .... 727 
 
 Posterior Auricular Vein .... 727 
 
 Occipital Vein 727 
 
XVlll 
 
 CONTENT!^ 
 
 The Veins of the Neck 728 
 
 External Jugular Vein 728 
 
 Posterior External Jugular Vein . 728 
 
 Anterior Jugular Vein 728 
 
 Internal Jugular Vein 729 
 
 Lingual Veins 729 
 
 Pharyngeal Veins 730 
 
 Superior Thyroid Vein .... 730 
 
 Middle Thyroid Vein .... 730 
 Veins of the Thyroid Gland . .731 
 
 Surgical Anatoniv 732 
 
 Vertebral Vei.i . ." 732 
 
 Anterior Vertebral or Anterior 
 
 Deep Cervical Vein .... 733 
 Posterior Vertebral or Posterior 
 
 Deep Cervical Vein .... 733 
 
 The Veins of the Diploe 733 
 
 The Meningeal Veins 734 
 
 The Cerebral Vein 734 
 
 Superficial or Cortical Cerebral Veins . 735 
 
 Superior Cerebral Veins . . 735 
 
 Median Cerebral Veins .... 735 
 
 Inferior Cerebral Veins 735 
 
 Deep Cerebral, Central or Ventricular 
 
 Veins, Veins of Galen . 735 
 
 Vena Corporis Striati .... 735 
 
 Choroid Vein 735 
 
 Basilar Vein 735 
 
 Superficial Orebellar Veins .... 730 
 
 Deep Cerebellar Veins 736 
 
 Veins of the Pons Varoli 736 
 
 Veins of the Medulla Oblongata . 736 
 The Sinuses of the Dura Mater, Ophthalmic 
 
 Veins and Emissary Veins . . 730 
 
 Superior Longitudinal Sinus . . 736 
 
 Torcular Etrcphili 737 
 
 Inferior Longitudinal Sinus .... 738 
 
 Straight Sinus 738 
 
 Lateral Sinus 738 
 
 Surgical Anatomy 739 
 
 Occipital Sinus 7S9 
 
 Cavernous Sinus 739 
 
 Surgical Anatomy 740 
 
 Spheno-parietal Sinus or Sinus Ala- 
 
 Parva} 740 
 
 Ophthalmic Veins 740 
 
 Circular Sinus 742 
 
 Superior Petrosal Sinus 742 
 
 Inferior Petrosal Sinus 742 
 
 Transverse or Basilar Sinus . . . 743 
 
 Emissary Veins 743 
 
 Surgical Anatomy 743 
 
 Veins of the Upper Extremity and Thorax. 
 
 The Superficial Veins of Upper Extremity . 745 
 Superficial Veins of the Hand and Fin- 
 gers 745 
 
 Anterior Ulnar Vein 745 
 
 Posterior or Dorsal Ulnar Vein . 745 
 
 Common Ulnar Vein 745 
 
 Radial Vein 745 
 
 Median Vein 745 
 
 Median Cephalic Vein 740 
 
 Median Basilic Vein .... 746 
 
 Basilic Vein 746 
 
 Cephalic Vein 747 
 
 The Deep Veins of the Upper Extremity . 747 
 
 Interosseous Veins 747 
 
 Deep Palmar Veins 747 
 
 Brachial Veins 747 
 
 Axillary Vein 747 
 
 Branches 748 
 
 Surgical Anatomy 748 
 
 Subclavian Vein 749 
 
 Innominate or Brachio-cephalic Veins 750 
 
 Right Innominate Vein 750 
 
 Left Innominate Vein 750 
 
 Peculiarities 7,50 
 
 The Deep Veins of the Upper Extremity — 
 
 Internal Mammary Vein 750 
 
 Inferior Thyroid Veins 751 
 
 Intercostal Veins 752 
 
 Superior Vena Cava 752 
 
 Relations 752 
 
 Azygos Veins 752 
 
 Surgical Anatomy 753 
 
 Bronchial Veins 753 
 
 The Spinal Veins 753 
 
 Dorsi-spinal Veins 753 
 
 Meningo-rachidian Veins .... 754 
 Veins of the Bodies of the Vertebrip or 
 
 Vense Basis Vertebrarum .... 755 
 Veins of the Spinal Cord or Medulli- 
 
 spinal Veins 755 
 
 Veins of the Lower Extremiiy, Abdomen 
 and Pelvis. 
 
 The Superficial Veins of the Lower Extrem- 
 ity 756 
 
 The Superficial Veins of the Foot . . 756 
 
 Internal or Long Saphenous Vein . 756 
 
 External or Sliort Saphenous Vein . 756 
 
 Surgical Anatomy 757 
 
 The Deep Veins of the Lower Extremity . 758 
 
 The Deep Veins of the Foot . . . 758 
 
 Posterior Tibial Veins 758 
 
 Anterior Tibial Veins 758 
 
 PopHteal Vein 758 
 
 Femoral Vein 758 
 
 External Iliac Vein 759 
 
 Deep Epigastric Vein 759 
 
 Deep Circumflex Iliac Vein . . 759 
 
 Hypogastric or Internal Iliac Vein 760 
 
 Surgical Anatomy 761 
 
 Obturator Vein 761 
 
 Sciatic Veins 761 
 
 Gluteal Veins 761 
 
 Superior Vesical Plexus .... 761 
 
 Prostatic or Prostatico-vesical Plexus . 761 
 
 Inferior Vesical Plexus 762 
 
 Surgical Anatomy 762 
 
 The Dorsal Veins of the Penis . . . 762 
 
 The Vaginal Plexuses and Veins . . 763 
 
 The Uterine Plexuses and Veins . 763 
 
 Common lUac Vein 764 
 
 Peculiarities 764 
 
 Ascending or Inferior Vena Cava . . 764 
 
 Relations 764 
 
 Peculiarities 764 
 
 Lumbar Veins 765 
 
 Spermatic Veins 765 
 
 Surgical Anatomy . . 766 
 
 Ovarian Veins 766 
 
 Renal Veins 767 
 
 Suprarenal Veins 767 
 
 Phrenic Veins 767 
 
 Hepatic Veins 767 
 
 The Portal System of Veins. 
 
 Superior Mesenteric Vein 768 
 
 Splenic Vein 768 
 
 Inferior Mesenteric Vein 768 
 
 Gastric Veins 768 
 
 Cystic Vein 769 
 
 Portal Vein 769 
 
 The Cardiac Veins. 
 
 Great Cardiac or Left Coronary Vein . . 770 
 
 Posterior or Middle Cardiac Vein 771 
 
 Left Cardiac Vein 771 
 
 Anterior Cardiac Vein 771 
 
 Right Cardiac or Small Coronary Vein . . 771 
 
 Coronary Sinus 771 
 
 Venaj Thebe.sii 771 
 
CONTENTS 
 
 XIX 
 
 THE LYMPHATIC SYSTEM. 
 
 PAQE 
 
 Subdivision into Superficial and Deep Sets 773 
 Lymphatic or Conglobate Glands . 774 
 
 The Thoracic Duct and the Right 
 Lymphatic Duct. 
 
 Radicals of Origin and Tributaries of Tho- 
 racic Duct 777 
 
 Structure of the Thoracic Duct .... 778 
 
 The Right Lymphatic Duct 778 
 
 Tributaries 779 
 
 Lymphatics of thk Cranial Region, Face 
 and Neck. 
 
 The Lymphatic Glancis of the Head and 
 
 Face 780 
 
 The Occipital or Suboccipital Glands . 780 
 The Posterior Auricular, Retro-auricu- 
 lar or Mastoid Glands .... 780 
 
 Parotid Lymph Glands 781 
 
 The Subparotid Glands 782 
 
 The Internal Maxillary or Zj'gomatic 
 
 Glands 782 
 
 The Facial Glands or Genial Glands . 782 
 The Lymphatic Vessels of the Cranial Region 782 
 The Lymphatic Vessels of the Face, the In- 
 terior of the No.se, Tongue, Floor of the 
 Mouth, Pharynx, Larynx and Thyroid 
 
 Gland 782 
 
 The Lymphatic Glands of the Neck . . 784 
 The Superficial Cervical Glands . . 784 
 The Submaxillary or Lateral Supra- 
 hyoid Glands 784 
 
 The Submental or Median Suprahyoid 
 
 Glands 785 
 
 The Retro-pharyngeal or Post-pharyn- 
 
 geal Glands 785 
 
 The Deep Cervical, (^arotid, or Sterno- 
 
 mastoid Glands 786 
 
 The Lymphatic Vessels of the Neck . 787 
 Surgical Anatomy 787 
 
 The Lymphatics of the Upper Extre.viity. 
 
 The Lymphatic Glands of the Upper Ex- 
 tremity 788 
 
 The Superficial Lymphatic Glands . 788 
 The Deep Lymphatic or the Axillary 
 
 Glands .' 790 
 
 The Lymphatic Vessels of the Upper Ex- 
 
 "tremity 792 
 
 The Superficial Lymphatic Vessels of 
 
 the Upper Extremity 792 
 
 The Deep Lymphatic Vessels of the 
 
 Upper" Extremity .... 792 
 Surgical Anatomy 792 
 
 The Lymphatics of the Lower Extremity. 
 
 The Lymphatic Glands of the Lower Ex- 
 
 • tremity 793 
 
 The Superficial Inguinal Lymphatic 
 
 Glands 793 
 
 Surgical Anatomy 794 
 
 The Deep Lymphatic Glands of the 
 
 Lower Extremity .... 795 
 The Deep Inguinal or Deep Fem- 
 oral Lymphatic Glands . . . 795 
 The Anterior Tibial Gland . 795 
 The Popliteal Glands .... 795 
 The Gluteal and Ischiatic Glands 797 
 The Lymphatic Vessels of the Lower Ex- 
 tremity 797 
 
 The Superficial liymphatic Vessels of 
 
 the Lower Extremity 797 
 
 The Deep Lymphatic Vessels of the 
 
 Lower Extremity 797 
 
 The Lymph.\tics of the Pelvis and 
 Abdomen. 
 
 The Iliac or llio-pelvic Glands .... 797 
 The External Iliac Glands .... 797 
 The Internal Iliac or Hypogastric Glands 799 
 The Common Iliac Gland .... 799 
 The Abdomino-aortic Glands .... 799 
 The Right Juxta-aortic Glands . . 800 
 The Left Ju.xta-aortic Glands . 800 
 
 The Retro-aortic Glands .... 800 
 The Pre-aortic Glands 800 
 
 The Glands along the Mesenteric 
 
 Arteries 800 
 
 The Glands connected with the 
 
 Coeliac Axis and its Branches . 800 
 
 The Gastric Glands 800 
 
 The Splenic Glands 800 
 
 The Hepatic Glands .... 801 
 The Lymphatic Vessels of the Abdomen and 
 
 Pelvis 801 
 
 The Superficial Lymphatic Vessels of 
 
 the Walls of the Abdomen . . 801 
 
 The Superficial Lymphatic Vessels 
 
 of the Gluteal Region . . . 801 
 
 The Superficial Lymphatic Vessels 
 
 of the Scrotum and Perina;um . 801 
 
 The Superficial Lymphatic Vessels 
 
 of the Penis 801 
 
 The Deep Lymphatic Vessels of the 
 
 Abdominal Wall 801 
 
 The Lymphatic Ves.sels of the Um- 
 bilicus 802 
 
 The Lymphatic Vessels of the Peri- 
 toneum 802 
 
 The- Lymphatic Vessels of the 
 
 Bladder 802 
 
 The Lymphatic Vessels of the Pros- 
 tate Gland 803 
 
 The Lymphatic Vessels of the Male 
 
 Urethra 803 
 
 The Lymphatic Vessels of the F'e- 
 
 male Urethra 803 
 
 The Lymphatic Vessels of the 
 
 Uterus 803 
 
 The Lymphatic Vessels of the Fal- 
 lopian Tube 804 
 
 The Lymphatic Vessels of the 
 
 Ovary 804 
 
 The Lymphatic Vessels of the 
 Vagina 804 
 
 The Lymphatic Vessels of the 
 
 Testicle 804 
 
 The Lymphatic Vessels of the 
 
 Vas Deferens 804 
 
 The Lymphatic Vessels of the 
 
 Seminal Vesicles 804 
 
 The Lymphatic Ves.sels of the 
 Kidney, Ureter, and Suprarenal 
 Capsule 804 
 
 The Lymphatic Vessels of the Liver 805 
 
 The Lymphatic Vessels of the 
 
 Bile-ducts 806 
 
 The Lymphatic Vessels of the 
 
 Stomach 806 
 
 The Lymphatic Vessels of the 
 
 Pancreas 807 
 
 The Lymphatic Vessels of the 
 
 Spleen 807 
 
 The Lymph,\tic System of the Intestines. 
 
 The Lymphatic Glands of the Small Intestine 807 
 
 The Ijymphatic Vessels of the Small Intestine 808 
 
 The Lymphatic Glands of the Large Intestine 808 
 
 The Colic Glands 808 
 
 The Rectal Glands 809 
 
XX 
 
 CONTENTS 
 
 The Lymphatic Vessels of the Large Intestine 809 
 
 Lymphatics of the Anus and Rectum . . 809 
 
 The Lymphatics of the Thorax. 
 
 The Lymphatic Glands of the Thoracic Wall 
 
 or the Parietal Lymphatics . . . 810 
 
 The Internal Mammary Glands . . 810 
 
 The Intercostal Glands 810 
 
 The Diaphragmatic Lymphatics . . 810 
 
 The Visceral Lymphatics . . . .811 
 
 The Anterior Mediastinal Glands . 811 
 
 The Posterior Mediastinal Glands 812 
 
 The Peritracheo-bronchial Glands 812 
 
 The Lymphatic Vessels of the Thoracic Wail 
 The Cutaneous Lymphatics 
 Lymphatics of the Mammary Gland . 
 Lymphatics of the Great Pectoral 
 
 Muscle 
 
 Surgical Anatomy 
 
 The Pulmonary Lymphatics 
 The Pleural Lymphatics 
 The Cardiac Lymphatics .... 
 The Thymic Lymphatic Vessels 
 The Lymphatic Vessels of the (Esoph- 
 agus 
 
 The Lymphatic Vessels of the Thoracic 
 Trachea 
 
 PAGE 
 
 812 
 812 
 812 
 
 814 
 814 
 815 
 815 
 815 
 815 
 
 815 
 
 815 
 
 THE NERVOUS SYSTExM. 
 
 Structure of the Cerebro-spinal Nervous 
 
 System 817 
 
 Nerve-cells or the Cell-bodies of the 
 
 Neurones 818 
 
 Unipolar cells 820 
 
 Bipolar cells 820 
 
 Multipolar cells 821 
 
 The Axone 821 
 
 The Dendrites 821 
 
 The Theory of Neurones . . . .821 
 
 Nerve-fibres 822 
 
 Development of Nerve-cells and Fibres . 823 
 
 Chemical Composition of Nervous Tissue . 824 
 
 Origin and Termination of Nerves . . . 826 
 
 Peripheral Termination of Nerves . . 826 
 
 Termination in Fibrilla; 827 
 
 Neuro-tendinous Spindles .... 829 
 
 Neuro-muscular Spindles .... 829 
 
 The Cerebro-spinal Axis. 
 
 The Spinal Cord and its Membranes. 
 
 Dissection 832 
 
 Membranes of the Cord. 
 
 The Spinal Dura Mater 832 
 
 Structure 834 
 
 The Arachnoid Membrane 834 
 
 Structure 834 
 
 The Pia Mater of the Cord . . . . .835 
 
 Structure 835 
 
 Surgical Anatomy 836 
 
 The Spinal Cord. 
 
 Fissures and Grooves 837 
 
 Columns of the Cord 838 
 
 Structures of the Cord 839 
 
 Blood Supply of the Cord 840 
 
 Minute Anatomy of the Cord .... 840 
 
 The Meninges or Meningeal Membranes of 
 the Brain. 
 
 Dissection 847 
 
 The Dura Mater of the Brain .... 847 
 
 Structure 848 
 
 Processes of the Dura Mater . . . 849 
 
 The Arachnoid Membrane 851 
 
 The Subarachnoid Space .... 852 
 
 Structure 853 
 
 GlanduliB Pacchioni, Luschka's Villi or the 
 
 Arachnoid Villi 854 
 
 The Pia Mater of the Brain 854 
 
 The Velum Interpositum or the Tela 
 
 Chorioidea Superior 854 
 
 The Brain. 
 The Development of the Brain .... 857 
 General Considerations and Divisions . . 864 
 The Hemispheres of the Cerebrum . . . 864 
 The Constituent Parts of the Hemi- 
 sphere 864 
 
 The Hemispheres of the Cerebrum — 
 
 The Surface of the Cerebrum . . .865 
 Fissures and Sulci of the Outer Surface 
 
 of the Hemisphere 865 
 
 The Lobes on the External Surface 869 
 The Fissures, Sulci and Lobes of the 
 
 Mesial and Tentorial Surfaces . 869 
 
 The Frontal Lobe 872 
 
 The Parietal Lobe 875 
 
 The Occipital Lobe 876 
 
 The Temporal Lobe 877 
 
 The Central Lobe or Island of Reil 
 
 (Insula) 878 
 
 Limbic Lobe 878 
 
 The Olfactory Lobe or Rhinencephalon 880 
 
 Under Surface or Base of Encephalon . 881 
 General Arrangement of the Parts 
 
 composing the Cerebrum .... 885 
 
 Fibres of tlie Internal Capsule . . . 892 
 
 The Inter-brain 901 
 
 The Third Ventricle 901 
 
 The Optic Thalamus 903 
 
 The Pineal Bodj-, Epiphysis Cerebri, 
 
 Conarium or Pineal Gland . . . 905 
 
 The Mid-brain 906 
 
 Crusta or Pes 907 
 
 The Tegmentum 908 
 
 The Substantia Nigra 910 
 
 The Corpora or Tubercula Quadri- 
 
 gemina 911 
 
 The Corpora Geniculata 911 
 
 The Aqueduct of Sylvius or Iter a Tertio 
 
 ad Quartum Ventriculum . . . 912 
 
 Subthalamic region 913 
 
 Structure of the Cerebrum . . 913 
 
 The Hind-brain 922 
 
 Pons Varolii 923 
 
 The Cerebellum or Little Brain . . 926 
 
 The Medulla Oblongata 938 
 
 The Pyramid 939 
 
 The Lateral Colunm or Lateral Area . 940 
 The Olive, Olivary Body or Olivary 
 
 Eminence 941 
 
 The Funiculus or Fasciculus of Ro- 
 lando 941 
 
 The Cuneate Fasciculus .... 941 
 
 The Fasciculus Gracilis 941 
 
 The Restiform Body 941 
 
 The Posterior Surface of the Medulla 
 
 Oblongata 942 
 
 The Fourth Ventricle 942 
 
 The Roof or Posterior Wall . 943 
 
 The Floor or Anterior Wall . 944 
 The Internal Structure of the Medulla 
 
 Oblongata 945 
 
 The Posterior Area .... 946 
 
 The Lower Part of the Medulla .. 946 
 
 The Upper Part of the Medulla . 948 
 
 Cerebral Localization and Topography. 
 Cranio-cerebral Topography 
 
 954 
 
CONTENTS 
 
 XXI 
 
 The Nerve-paths. 
 
 The Motor, Efferent or Descending Tract . 959 
 
 The Sensory, Afferent or Ascending Tract . 961 
 
 The Spinal Nerves. 
 
 The Roots of the Spinal Nerves . . . 965 
 
 The Anterior or Ventral Root . . . 965 
 
 The Posterior or Dorsal Root . . . 965 
 
 The GangUa of the Spinal Nerves . . . 966 
 
 Distribution of the Spinal Nerves . . . 967 
 
 Points of Emergence of the Spinal Nerve . 967 
 
 The Cervical Nerves. 
 
 The Roots of the Cervical Nerves ... 968 
 The Posterior or Dorsal Division of the 
 
 Cervical Nerves 968 
 
 The Anterior Divi.sion of the Cervical Nerves 971 
 
 The Cervical Plexus 972 
 
 Superficial Branches 972 
 
 Deep Branches, Internal Series . . 974 
 
 Surgical Anatomy 976 
 
 Deep Branches, External Series . . 976 
 
 Surgical Anatomy 977 
 
 The Brachial Plexus 977 
 
 Relations 980 
 
 Branches 981 
 
 Surgical Anatomy 991 
 
 The Thoracic or Dorsal Nerves. 
 
 The Roots of the Thoracic or Dorsal Nerves 993 
 The Posterior Divisions of the Thoracic or 
 
 Dorsal Nerves 993 
 
 The Internal Branches 993 
 
 The External Branches 993 
 
 The Cutaneous Branches .... 993 
 The Anterior Divisions of the Thoracic or 
 
 Dorsal Nerves or the Intercostal 
 
 Nerves 993 
 
 The Anterior Division of the First 
 
 Thoracic or First Dorsal Nerve . . 995 
 The Anterior Divisions of the Upper 
 
 Thoracic or Dorsal Nerves . . . 995 
 The Anterior Divisions of the Lower 
 
 Thoracic or Dorsal Nerves . . . 996 
 
 The Last Thoracic or Dorsal Nerve 996 
 
 Surgical Anatomy 996 
 
 The Lumbar Nerves. 
 
 The Roots of the Lmnbar Nerves . . . 997 
 The Posterior Divisions of the Lumbar 
 
 Nerves 997 
 
 Internal Branches 998 
 
 External Branches 998 
 
 The Anterior Divisions of the Lumbar Nerves 998 
 
 The Lumbar Plexus 998 
 
 Branches 999 
 
 The Sacral and Coccygeal Nerves. 
 
 The Roots of the Upper Sacral Nerves . 1006 
 
 The Posterior Divisions of the Sacral Nerves 1006 
 
 The Upper Sacral Nerves .... 1006 
 
 The Lower Sacral Nerves .... 1007 
 
 The Anterior Divisions of the Sacral Nerves 1007 
 The Posterior Divisions of the Coccvgeal 
 
 Nerve ". . 1008 
 
 The Anterior Division of the Coccygeal 
 
 Nerve 1009 
 
 The Sacral or Sciatic Plexus and the Pudic 
 
 or Pudendal Plexus 1009 
 
 Branches . ■■. 1010 
 
 Surgical Anatomy 1017 
 
 The Cerebral or Cranial Nerves. 
 
 The First or Olfactory Nerve. 
 
 Surgical Anatomy 1021 
 
 The Second or Optic Nerve. 
 
 The Optic Tract 1021 
 
 The Optic Commissure 1021 
 
 The Optic Path 1022 
 
 Surgical Anatomy 1022 
 
 The Third or Motor Oculi Nerve. 
 Surgical Anatomy 
 
 1025 
 
 The Fourth or Trochlear Nerve. 
 
 Branches of Communication 1026 
 
 Branches of Distribution 1026 
 
 Surgical Anatomy 1026 
 
 The Fifth, Trigeminal or Trifacial Nerve. 
 
 The Gasserian or Semilunar Ganglion . . 1027 
 
 Ophthalmic Nerve 1028 
 
 Branches 1028 
 
 The Superior Maxillary Nerve .... 1031 
 
 Branches 1032 
 
 The Mandibular or Inferior Maxillary Nerve 1036 
 
 Branches 1036 
 
 Surface Marking 1041 
 
 Surgical Anatomy 1041 
 
 The Sixth or Abducent Nerve. 
 
 Branches of Communication 1043 
 
 Surgical Anatomy 1044 
 
 The Seventh or Facial Nerve. 
 Branches of Communication . . . . 
 
 Branches of Distribution 
 
 Surgical Anatomy 
 
 The Eighth or Auditory Nerve. 
 The Origin of the Eighth Nerve 
 
 The Auditory Paths 
 
 Surgical Anatomy 
 
 Tlie Ninth or Glosso-Pharyngeal Nerve 
 The Superior or Jugular Ganglion 
 The Inferior or Petrous Ganglion 
 
 Branches of Communication 
 
 Branches of Distribution 
 The Gustatory Path . . • . 
 Surgical Anatomy 
 
 1046 
 1046 
 1049 
 
 1050 
 1053 
 1054 
 
 1056 
 1056 
 1056 
 1056 
 1056 
 1057 
 
 The Tenth or Pneumogastric Nerve. 
 The Ganglion of the Root of the Pneumo- 
 gastric Nerve 1059 
 
 Connecting Branches 1059 
 
 The Ganglion of the Trunk of the Pneumo- 
 gastric Nerve 1059 
 
 Connecting Branches 1059 
 
 Surgical Anatomy 1062 
 
 The Eleventh or Spinal Accessory Nerve. 
 The Bulbar or Accessory Part of the Spinal 
 
 Accessory Nerve 1063 
 
 The Spinal Portion of the Spinal Accessory 
 
 Nerve 1063 
 
 Surgical Anatomy 1063 
 
 The Twelfth or Hypoglossal Nerve. 
 
 Branches of Communication 1065 
 
 Branches of Distribution 1066 
 
 Surgical Anatomy 1066 
 
 The Symp.\thetic Nftrve. 
 Structure of the Sympathetic System 
 
 1068 
 
 The Gangliated Cord. 
 
 The Cervical Portion of the Gangliated Cord 1071 
 
 The Superior Cervical Ganglion . 1072 
 
 The Inferior Cervical Ganglion . . 1077 
 
 Surgical Anatomy 1077 
 
XXll 
 
 CONTENTS 
 
 The Thoracic Portion of the Gangliated Cord 1078 \ The Cardiac Plexus- 
 
 The Lumbar Portion of the Garighated Cord 1079 
 The Pelvic or Sacral Portion of the GangU- 
 
 ated Cord 1080 
 
 The Great Plexuses of the Sympathctics . 
 
 The Cardiac Plexus 1081 
 
 The Great or Deep Cardiac Plexus . 1081 
 
 The Superficial or Anterior Cardiac 
 
 Plexus 1081 
 
 The Pulmonary Plexus 1081 
 
 The CEsophageal Plexus 1082 
 
 The Epigastric or Solar Plexus .... 1083 
 
 The Hypogastric Plexus 1085 
 
 The Pelvic or Sacral Plexus .... 1086 
 
 THE ORGANS OF SPECIAL SENSE. 
 
 The Tongue. 
 
 The Body 1087 
 
 The Base or Root 1087 
 
 The Apex or Tip 1087 
 
 The Margin of the Tongue 1087 
 
 The Under or Inferior Surface .... 1087 
 
 Structure of the Tongue 1088 
 
 Surgical Anatomy 1093 
 
 The Nose. 
 The Outer Nose. 
 
 Structure 1096 
 
 The Nasal Fossce. 
 
 The Anterior Nares 1098 
 
 The Posterior Nares 1098 
 
 Outer Wall 1099 
 
 The Inner Wall 1100 
 
 Surgical Anatomy 1102 
 
 The Eye. 
 
 The Fascia or Capsule of T^non . . . 1103 
 
 The Tunics of the Eye. 
 The Fibrous or External Coat : The Sclerotic 
 
 and Cornea 1107 
 
 The Sclera or Sclerotic Coat . . 1107 
 
 The Cornea 1108 
 
 Dissection 1111 
 
 The Choroid, Ciliary Body, and Iris; the 
 
 Tunica Media; the Uveal Tract . . 1111 
 
 The Choroid 1111 
 
 The Ciliary Body 1115 
 
 The Iris . . V 1117 
 
 The Tunica Interna or Retina . . .. 1120 
 
 The Refracting Media. 
 
 The Aqueous Humor 1128 
 
 The Vitreous Body 1129 
 
 The Crystalline Lens 1130 
 
 Surgical Anatomy of the Eye . . . . 1134 
 
 The Appendages of the Eye. 
 
 The Eyebrow 1137 
 
 The Eyelid 1137 
 
 The Meibomian or Tarsal Glands . . 1139 
 
 The Conjunctiva 1140 
 
 The Lachrymal Apparatus 1141 
 
 The Lachrymal Glands 1141 
 
 The Lachrymal Sac 1142 
 
 The Nasal Duct 1142 
 
 Surface Form 1142 
 
 Surgical Anatomy 1143 
 
 The Ear. 
 The External Ear. 
 
 The Pinna or Auricle 1144 
 
 Structure of the Pinna 1146 
 
 The External Auditory Canal .... 1148 
 
 The Cartilaginous Portion .... 1148 
 
 The Osseous Portion 1149 
 
 Surface Form 1150 
 
 The Middle Ear, Drum or Tympanum. 
 
 The Tympanic Cavity 1150 
 
 The Drumhead or Membrana Tympani . 1155 
 
 The Ossicles of the Tympanum .... 1158 
 
 The Malleus or Hammer . . . .1158 
 
 The Incus or Anvil 1159 
 
 The Stapes or Stirrup 1160 
 
 The Internal Ear or Labyrinth. 
 
 The Osseous Labyrinth 1164 
 
 The Vestibule 1164 
 
 The Semicircular Canals .... 1165 
 
 The Cochlea 1165 
 
 The Membranous Labyrinth 1169 
 
 The Utricle 1169 
 
 The Saccule 1170 
 
 The Membranous Semicircular Canals . 1170 
 
 Surgical Anatomy .1176 
 
 The Skin. 
 
 The Corium, Cutis Vera, Dermis or True 
 
 Skin 1180 
 
 The Cuticle, Scarf Skin or Epidermis . .1181 
 
 The Appendages of the Skin .... 1185 
 
 The Nails 1185 
 
 The Hairs 1187 
 
 The Sudoriferous or Sweat-glands . . 1190 
 
 The Sebaceous Glands 1191 
 
 THE ORGANS OF DIGESTION. 
 
 The AlLIMENTARY C.\N.\L. 
 
 The Mouth, Oral or Buccal Cavity. 
 
 The Vestibule 
 
 The Cavity of the Mouth Proper 
 
 The Lips 
 
 The Cheeks 
 
 The Gums .^ 
 
 The Teeth 
 
 General Characters 
 
 Temporary, Deciduous or Milk Teeth 
 
 Permanent Teeth 
 
 Arrangement of the Teeth . 
 
 Structure of the Teeth .... 
 
 Development of the Teeth . 
 The Palate 
 
 The Hard Palate 
 
 1194 
 1194 
 1194 
 1195 
 1195 
 1195 
 1195 
 1196 
 1196 
 1198 
 1200 
 1204 
 1210 
 1210 
 
 The Palate— 
 
 The Soft Palate or Velum Pendulum 
 
 Palati 1211 
 
 The Tonsil or Amvgdala .... 1213 
 
 The Salivarv Glands ." 1214 
 
 The Parotid Gland 1214 
 
 Surface Form ...'... 1215 
 
 The Submaxillary Gland .... 1216 
 
 The Sublingual Gland 1217 
 
 Structure of Salivary Glands . . . 1217 
 
 Surface Form 1219 
 
 The Pharynx. 
 
 The Nasal Part 1221 
 
 The Oral Part 1221 
 
 The Larvngeal Part 1222 
 
 Structure 1222 
 
CONTENTS 
 
 XXlll 
 
 PAGE 
 
 Surgical Anatomy of the Mouth, Cheeks, 
 Lips, Gums, Tonsils, Palate, Salivary 
 Glands and Pharynx 1224 
 
 The (Esophagus. 
 
 Relations 1227 
 
 Anomalies 1228 
 
 Structure 1228 
 
 Movements antl Innervations of the (Esoph- 
 agus 1230 
 
 Surgical Anatomy 1230 
 
 Thk Audomen. 
 
 Boundaries 1231 
 
 Development of the Alimentary Canal, Vis- 
 cera and Peritoneum 1235 
 
 Development of the Alimentary Canal . . 1236 
 
 The Peritoneum. 
 
 Structure of the Peritoneum .... 1245 
 
 Retro-peritoneal Fossae 1260 
 
 Surgical Anatomy 1264 
 
 The Stomach. 
 
 Relations of the Stomach 1269 
 
 Surfaces 1269 
 
 The Cardia 1270 
 
 The Pylorus 1270 
 
 Alterations in Position 1271 
 
 Supports of the Stomach 1272 
 
 Structure 1273 
 
 Movements and Innervation of Stomach . 1280 
 
 Surface Form 1280 
 
 Surgical Anatomy 1280 
 
 The Small Intestine. 
 
 The Duodenum 1282 
 
 The First or Superior Portion . . , 1284 
 The Second or Descending Portion . 1285 
 The Third, Pre-aortic, Horizontal or 
 
 Transverse Portion 1285 
 
 The Fourth or Ascending Portion . 1286 
 
 The Jejunum and Ileum 1289 
 
 Differences between the Jejvmum and 
 
 Ileum 1289 
 
 The Jejunum 1289 
 
 The Ileum 1289 
 
 Structure of the Small Intestine, including 
 the Duodenum 1290 
 
 PAGE 
 
 The Large hUestine. 
 
 The CiECum 13(M) 
 
 The Vermiform Appendix .... 1303 
 The Ileo-caical Valve or the Valve of 
 
 Bauhin 1308 
 
 The Colon 1309 
 
 The Ascending Colon 1309 
 
 The Transverse Colon 1309 
 
 The Descending Colon 1309 
 
 The Sigmoid Flexure, Pelvic Colon or 
 
 Sigmoid Colon 1311 
 
 The Rectum 1312 
 
 The Common Anal Canal . .1315 
 
 Structure of the Large Intestine . . 1316 
 
 Movements and Innervations of the Intes- 
 tines 1322 
 
 Surface Form of the Intestines .... 1323 
 
 Surgical Anatomy of the Intestines . 1324 
 
 The Liver. 
 
 The Superior Area or Surface .... 1327 
 
 The Anterior Area or Surface .... 1327 
 
 The Lateral or Right Area or Surface . . 1329 
 
 The Under or Visceral Area or Surface . 1329 
 
 The Posterior Area or Surface .... 1329 
 
 Fissures of the Liver 1331 
 
 Lobes of the Liver 1332 
 
 Supports and Movability of the Liver . . 1334 
 
 Abnormalities of the Liver 1335 
 
 Structure of the Liver 1337 
 
 The Excretory Apparatus of the Liver . 1342 
 
 The Hepatic Duct 1342 
 
 The Gall-bladder 1342 
 
 The Cystic Duct 1344 
 
 Surface Relations of the Liver .... 1346 
 
 Surgical Anatomy of the Liver .... 1346 
 
 The Pancreas. 
 
 Dissection 1348 
 
 The Right Extremity or Head of the Pan- 
 creas 1348 
 
 The Neck of the Pancreas 1350 
 
 The Body and Tail of the Pancrea-s . .1350 
 
 Structure of the Pancreas 1352 
 
 Surface Form 1353 
 
 Surgical Anatomy 1353 
 
 The Spleen. 
 
 Surface of the Spleen 1354 
 
 Supports and Movability of the Spleen . 1356 
 
 Surface Form 1359 
 
 Surgical Anatomy 1359 
 
 ORGANS OF VOICE AND RESPIRATION. 
 
 The Larynx. 
 
 The Cartilages of the Larynx .... 1362 
 
 The Thyroid Cartilage 1362 
 
 The Cricoid Cartilage 1363 
 
 The Arytenoid Cartilages .... 1364 
 The Cornicula Laryngis or Cartilages 
 
 of Santorini 1365 
 
 The Cuneiform Cartilages or Cartilages 
 
 of Wri.sberg 1365 
 
 The Epiglottis or the Cartilage of Epi- 
 glottis 1365 
 
 Structure of the Larynx 1365 
 
 Interior of the Larynx 1368 
 
 The Tk.\che.'V and Bronchi. 
 
 Relations 1376 
 
 The Right Bronchus 1376 
 
 The Left Bronchus 1378 
 
 Structure of the Trachea 1378 
 
 Surface Form of Larynx 1380 
 
 Surgical Anatomy of Larynx and Trachea . 1381 
 
 The Pi.eur^. 
 
 Reflections of the Pleura 1384 
 
 Structure of the Pleura 1387 
 
 Surgical Anatomy 1387 
 
 The Mediastinal, Space. Interpleural Space 
 OR Mediastinum. 
 
 The Superior Mediastinum ..... 1388 
 
 The Anterior Mediastinum 1389 
 
 The Middle Mediastinum 1389 
 
 The Posterior Mediastinum 1389 
 
 The Lungs. 
 
 Apex of the Lungs 1390 
 
 Base of the Lungs 1391 
 
 Surfaces of the I.,ungs 1391 
 
 Borders of the Lungs 1392 
 
 Lobes of the Limgs 1392 
 
XXIV 
 
 CONTENTS 
 
 PAGE 
 
 The Root of the Lung 1394 
 
 The Fu^tal Lung 1394 
 
 Structure of tlie Lung 1394 
 
 The Bronchus 1395 
 
 Changes in tlie Structure of the Bronchi in 
 
 the Lungs 1395 
 
 Surface Form of the Lungs 1397 
 
 Surgical Anatomy of the Lungs . . 1397 
 
 THE DUCTLESS GLANDS. 
 
 The Thyroid Body or Gland. 
 
 Accessory Thyroids 1403 
 
 Structure of the Thyroid 1403 
 
 Surgical Anatomy 1405 
 
 Parathyroids 1408 
 
 Structure of 1406 
 
 The Thymus Gland. 
 Structure of the Thymus Gland . . 1408 
 
 The Carotid Gland or Carotid Body. 
 
 Surgical Anatomy 1409 
 
 The Coccygeal Gland or Coccygeal Body 1410 
 
 THE URINARY ORGANS. 
 
 The Kidneys. 
 
 Surfaces of the Kidneys 1412 
 
 Borders of the Kidneys 1415 
 
 General Structure of the Kdney . . 1415 
 
 Surface Form 1425 
 
 Surgical Anatomy 1425 
 
 The Ureter. 
 
 The Ureter Proper 1426 
 
 Relations of the Ureter 1427 
 
 Structure of the Ureter 1427 
 
 Surgical Anatomy 1428 
 
 The Suprarenal Capsule or Gland. 
 
 Relations of the Suprarenal Capsule . . 1428 
 
 Accessory Suprarenal Glands .... 1430 
 
 Structure of Suprarenal Glands .... 1430 
 
 The Cavity of the Pelvis. 
 
 Boundaries 1431 
 
 Contents 1431 
 
 The Urinary Bladder. 
 
 Surfaces 1433 
 
 The Fundus or Base 1433 
 
 The Summit or Apex 1435 
 
 The Urachus or Middle Umbilical Ligament 1435 
 
 Structure of tlie Bladder 1437 
 
 Objects Seen on the Inner Surface of Bladder 1 438 
 
 Surface Form 1440 
 
 Surgical Anatomy 1440 
 
 The Male Urethra. 
 The First or Prostatic Portion .... 1441 
 The Second, Muscular or Membranous Por- 
 tion 1442 
 
 The Third, Penile, Pendulous, Cavernous or 
 
 Spongy Portion 1443 
 
 Structure of Male Urethra 1444 
 
 Surgical Anatomy 1445 
 
 The Female Bladder and Urethra. 
 
 The Female Urethra 1446 
 
 Structure 1446 
 
 THE MALE ORGANS OF GENERATION. 
 
 The Prostate Gland. 
 
 The Base 1451 
 
 The Apex 1451 
 
 Surfaces 1451 
 
 The Lateral Lobes 1451 
 
 The So-called Middle Lobe 1451 
 
 Structure 1452 
 
 Surgical Anatomy 1452 
 
 Cowper's Glands. 
 
 Structure 1453 
 
 The Penis. 
 
 The Root 1454 
 
 The Body of the Penis 1455 
 
 Structure of the Penis 1455 
 
 Surgical Anatomy 1460 
 
 The Testicles and their Coverings. 
 
 Descent of the Testis. 
 
 Surgical Anatomy 1462 
 
 The Coverings of the Testicle. 
 
 The Testicular Bag or Scrotum .... 1462 
 
 The Intercolumnar or Spermatic Fascia . 1463 
 
 The Cremasteric Fascia 1464 
 
 The Infundibuliform Fascia 1464 
 
 The Tunica Vaginalis 1465 
 
 The Spermatic Cord. 
 
 Structure 1466 
 
 Surgical Anatomy 1468 
 
 The Testicles. 
 
 Structure of the Testicle and Epididymis . 1471 
 
 Surgical Anatomy 1473 
 
 The Seminal Vesicles. 
 
 The Ejaculatory Ducts 1476 
 
 Structure . '. 1476 
 
 THE FEMAIvE ORGANS OF GENERATION. 
 
 External Organs. 
 The Mons Veneris . 7 .' 7 7 . . . 1477 
 
 The Large Lips or Labia Majora 
 
 The Small Lips, Nymphae or Labia Minora 
 
 1477 
 1478 
 
 The Vestibule 1481 
 
 The Orifice of the Urethra or the Meatus 
 
 Urinarius 1481 
 
 The Hymen 1481 
 
 Glands of Bartholin 1482 
 
 The Clitoris 1479 '' The Vaginal Bulb or Bulb of the Vestibule 1483 
 
CONTENTS 
 
 XXV 
 
 PAQE 
 
 Internal Organs. 
 The Vagina. 
 
 Relations 1484 
 
 Structure 1484 
 
 The Wo7nh or Uterus. 
 
 The Fundus 1487 
 
 The Body of the Uterus 1487 
 
 The Neck or Cervix Uteri 1488 
 
 Folds and Ligaments 1489 
 
 The Cavity of the Uterus 1491 
 
 The Cavity of the Cervix or Cervical Canal 1491 
 
 Surgical Anatomy 1496 
 
 The Adnexa or Appendages of Uterus. 
 
 The Fallopian Tube. 
 
 Structure of the Fallopian Tube . . 7 1498 
 
 The Epo-ophoron, Parovarium or Organ of 
 
 Rosenmiiller 1499 
 
 The Paro-ophoron 1499 
 
 The Ovary. 
 
 Supports and Connections of the Ovary . 1500 
 
 Descent of the Ovary 150I 
 
 The Ovary at Different Ages . . . 1501 
 
 Structure 1501 
 
 Surgical Anatomy of the Appendages . . 1503 
 
 The Mammary Gland. 
 
 Description of a Well-developed Breast . 1503 
 
 The Nipple 1504 
 
 Prolongation of Mammary Tissue . . . 1505 
 
 Structure of Mammary Gland and Nipple . 1505 
 
 Surgical Anatomy 1508 
 
 The Male Breast . . 1509 
 
 Surgical Anatomy 1509 
 
 THE SURGICAr. ANATOMY OF INGUINAL AND FEMORAL 
 
 HERNIA. 
 
 Dissection 1511 
 
 Inguinal Hernia. 
 
 Obli<iue Inguinal Hernia 1520 
 
 Congenital Hernia 1523 
 
 Infantile and Encysted Hernia . . 1523 
 
 Hernia into Funicular Process 
 Direct Inguinal Hernia . 
 
 Femoral Hernia. 
 Varieties of Femoral Hernia 
 
 1523 
 1523 
 
 1534 
 
 SURGICAL ANATOMY OF THE PERINiEUM. 
 
 Dissection ." 7 . 1535 
 
 Ischio-reclal Region. 
 Dissection 1536 
 
 The PcrincBum, Proper in the Male. 
 Position of the Viscera at the Outlet of the 
 
 Pelvis 1540 
 
 Surgical Anatomy 1541 
 
 The Female PerincBum,. 
 
 The Pelvic Fascia 1544 
 
 The Obturator Fascia 154G 
 
 The Recto-vesical Fascia or the Visceral 
 
 Layer of the Pelvic Fascia .... 1546 
 
 Chronological T,\ble of the Development of the Fcetus ....... 7 . 1547 
 
 Index I549 
 
DESCRIPTIVE AND SURaiOAL 
 
 AI^ATOMY. 
 
 OSTEOLOGY -THE SKELETON. 
 
 T 
 
 HE entire skeleton in the adult consists of 200 distinct bones. These are: 
 
 The spine or vertebral column (sacrum and coccyx included) .... 26 
 
 Cranium 8 
 
 Face 14 
 
 Hyoid bone, sternum, and ribs 26 
 
 Upper extremities 64 
 
 Lower extremities 62 
 
 200 
 
 In this enumeration the patellae are included as separate bones, but the smaller 
 sesamoid bones and the ossicula auditus are not reckoned. The teeth belong to 
 the tegumentary system. Different anatomists make different computations as 
 to the number of bones in the skeleton. Some describe the skeleton as containing 
 206 distinct bones, adding the ossicles of the ear to the previously stated number. 
 By adding the epipteric bones, the sphenoidal turbinal bones, the sesamoid bones, 
 and others, the number may be greatly augmented. 
 
 Bones are divisible, according to their shape, into four classes: long, short, flat, 
 and irregular. 
 
 Long Bones. — The long bones are found in the limbs, where they form a 
 system of levers, which sustain the weight of the trunk and confer the power 
 of locomotion. A long bone consists of a shaft and two extremities. The shaft 
 is a hollow cylinder, contracted and narrowed to afford greater space for the 
 bellies of the muscles; the walls consist of dense, compact tissue of great thick- 
 ness in the middle, but becoming thinner toward the extremities; the spongy 
 tissue is scanty, and the bone is hollowed out in its interior to form the medullary 
 canal. The extremities are generally somewhat expanded for greater convenience 
 of mutual connection, for the purpose of articulation, and to afford a broad 
 surface for muscular attachment. Here the bone is made up of spongy tissue 
 with only a thin coating of compact substance. The long bones are not straight, 
 but curved, the curve generally taking place in two directions, thus affording 
 greater strength to the bone. The bones belonging to this class are the clavicle, 
 humerus, radius, ulna, femur, tibia, fibula, metacarpal and metatarsal bones, and 
 the phalanges. 
 
 Short Bones. — Where a part of the skeleton is intended for strength and com- 
 pactness, and its motion is at the same time slight and limited, it is divided into 
 a number of small pieces united together by ligaments, and the separate bones 
 are short and compressed, such as the bones of the carpus and tarsus. These 
 bones, in their structure, are spongy throughout, excepting at their surface, where 
 
 .s ( 33 ) 
 
34 THE SKELETON 
 
 there is a thin crust of compact substance. The patellae also, together with the 
 other sesamoid bones, are by some regarded as short bones. 
 
 Flat Bones. — Where the principal requirement is either extensive protection 
 or the provision of broad surfaces for muscular attachment, we find the osseous 
 structure expanded into broad, flat plates, as is seen in the bones of the skull 
 and the shoulder-blades. Flat bones are composed of two thin layers of com- 
 pact tissue enclosing between them a variable quantity of cancellous tissue. In 
 the cranial bones these layers of compact tissue are familiarly known as the tables 
 of the skull; the outer table is thick and tough; the inner table is thinner, denser, 
 and more brittle, and hence is termed the vitreous table. The intervening can- 
 cellous tissue is called the diploe. The flat bones are: the occipital, parietal, frontal, 
 nasal, lachrymal, vomer, scapula, os innominatum, sternum, ribs, and patella. 
 
 Irregular Bones. — -The irregular or mixed bones are such as, from their pecu- 
 liar form, cannot be grouped under either of the preceding heads. Their structure 
 is similar to that of other bones, consisting of a layer of compact tissue externally 
 and of spongy, cancellous tissue within. The irregular bones are: the vertebrae, 
 sacrum, coccyx, temporal, sphenoid, ethmoid, malar, superior maxilla, inferior maxilla, 
 palate, inferior turbinated, and hyoid. 
 
 Surfaces of Bones. — If the surface of any bone is examined, certain eminences 
 and depressions are seen, to which descriptive anatomists have given the following 
 names. 
 
 These eminences and depressions are of two kinds: articular and non-articular. 
 Well-marked examples of articular eminences are found in the heads of the 
 humerus and femur and of articular depressions in the glenoid cavity of the 
 scapula and the acetabulum. Non-articular eminences are designated according 
 to their form. Thus a broad, rough, uneven elevation is called a tuberosity; a 
 small, rough prominence, a tubercle; a sharp, slender, pointed eminence, a spine; 
 a narrow, rough elevation, running some way along the surface, a ridge, line, or 
 crest. 
 
 The non-articular depressions are also of very variable form, and are described 
 as fossae, grooves, furrows, fissures, notches, sulci, etc. These non-articular emi- 
 nences and depressions may receive blood-vessels, nerves, tendons, ligaments, or 
 portions of organs, or may serve to increase the extent of surface for the attach- 
 ment of ligaments and muscles. They are usually well marked in proportion to 
 the muscular development of the subject. 
 
 A prominent process projecting from the surface of a bone which it has never 
 been separate from or movable upon is termed an apophysis (from d-6</'tj(Ti^, an 
 excrescence) ; but if such process is developed as a separate piece from the rest of 
 the bone, to which it is afterward joined, it is termed an epiphysis (from iTiiifom^, 
 an accretion). The main part of the bone, or shaft, which is formed from the 
 primary centre of ossification, is termed the diaphysis, and is separated, during 
 growth, from the epiphysis by a layer of cartilage, at which growth in length of 
 the bone takes place. Some bones are hollow and contain sinuses, which are 
 spaces for air. Canals or foramina are channels or openings in bone through 
 which nerves or vessels pass. 
 
 Structure of Bone. — Bone is a highly specialized form of connective tissue. 
 In reality, it is white fibrous tissue, calcified and structurally modified until it 
 becomes osseous tissue. Bone is not simply a crude mass resulting from the 
 calcification of cartilage or fibrous tissue; it is a distinct tissue, of a definite struc- 
 ture, the constituent parts of which are arranged symmetrically, Its structure 
 varies somewhat in different vertebrates.^ 
 
 1 Arquitectura del Aparato de Sustentacion en los Vertebrados. Por el Dr. Saturnine Garcia Hurtado. Our 
 description applies to human bone. 
 
STRUCTURE OF BONE 
 
 35 
 
 There are two varieties of bone: dense or compact bone {substantia compacta), 
 and cancellous, loose, or spongy bone {substantia spongiosa). 
 
 Compact Bone is dense, like ivory, and is always placed upon the exterior of 
 bones. Even this apparently compact tissue is porous; it differs from cancellous 
 bone in the greater density of its tissue and in the arrangement of its osseous 
 plates into Haversian systems. Compact bone is surrounded by periosteum. 
 
 OSTEOQENETIO 
 
 CELLS 
 
 LAMELL/E 
 
 LACUN/E 
 
 CANALICUL 
 
 HAVERSIAN 
 
 CANAL 
 
 COMPLETE 
 HAVERSIAN 
 SYSTEM 
 
 Fig. 1. — Diagram of the structure of osseous tissue. A small part of a transverse section of the shaft of a long 
 JDone is shown. At the uppermost part is the periosteum covering the outside of the bone ; at the lowermost part 
 is the endosteum lining the marrow-cavity. Between these is the compact tissue, consisting largely of a series of 
 Haversian systems, each being circular in outline and perforated by a central canal. In the first one is shown 
 only the area occupied by a system", in the second is seen the concentric arrangement of the lamelte; and in the 
 others, respectively, canaliculi; lacunae; lacuna" and canaliculi; the contents of the canal, artery, vein, lymphatic 
 and areolar tissue; lamella?, lacunae, and canaliculi; and, finall.y, all of the structures composing a complete sys- 
 tem. Between the systems are circumferential and intermediate lamella>, only a few of which are represented as 
 lodging lacuna>, though it is to be understood that the lacuna; are in all parts. The periosteum is seen to be 
 made up of a fibrous layer and a vascular layer, and to have upon its attached surface a stratum of cells. From 
 the fibrous layer project inward the rivet-like fibres of Sharpey. (F. H. Gerrish.) 
 
 The outer portion of the wall of a long bone, the cortex of the head of a bone, 
 and the outer and inner layers of a flat bone are composed of compact osseous 
 tissue, which is the hardest substance in the body with the exception of dentine 
 and enamel; it is tough and elastic, and much force is required to break it. 
 
 Cancellous Bone is found in the interior of bones. The name, which means 
 lattice-work, indicates the structure, which consists of slender fibres and lamellse 
 joined to form a reticulum, the small meshes of which are marrow-spaces. The 
 
36 THE SKELETON 
 
 spicules of cancellous bone contain lacunae and canaliculi, but no Haversian 
 systems. In some regions the inner portion of the wall of a long bone, about the 
 marrow-cavity, is composed of cancellous bone. Toward each extremity of the 
 shaft the amount of cancellous tissue increases, the marrow-cavity diminishes in 
 size, and the cancellous tissue is arranged in lines that approach each other toward 
 the extremity, like the sides of an arch, and form a support for the epiphysis 
 (Fig. 131). In the epiphysis the bone-plates are, as a rule, at right angles to 
 the plane of the articular surface (the lines of greatest pressure) ; and they are 
 bound together or strengthened by other bone-fibres, which are usually in corre- 
 spondence with the planes of the articulation (the lines of greatest tension) (Fig. 
 163). The nearer the bone-spicules are to the medullary cavity the stronger they 
 are (Hurtado). 
 
 In the flat and the irregular bones, the cancellous tissue is between the layers 
 of compact bone, and is called the diploe. 
 
 A Short Bone is composed chiefly of cancellous tissue, which is encased in a 
 thin coat of compact substance [substantia corticalis). 
 
 A Long Bone consists of a shaft, or diaphysis, and two extremities, or epiphyses. 
 The shaft is an osseous tube, the outer layer of which is compact, and the inner 
 layer of which is cancellous. It surrounds the medullary cavity (cavum medullar e), 
 which, in the recent condition, contains the medulla, or marrow [medulla ossium), 
 which substance enters into the nearest Haversian canals. ' This cavity is widest 
 at the centre of the shaft, and narrows toward the ends, where it is encroached 
 upon by the cancellous layer which lies within the compact layer. 
 
 There are two varieties of marrow: Yellow marrow [medulla ossium flava) is 
 found in the medullary cavities of the shafts of the long bones. It is composed 
 of a network of fibrous tissue carrying many blood-vessels, fat-cells, and a few 
 large nucleated masses of protoplasm — the true marrow-cells, or myelocytes. 
 The yellow color of the marrow is due to fat. Yellow marrow is derived from 
 red marrow by an increase in fat and diminution in marrow elements; it plays 
 no part in blood-formation. At the periphery of the marrow cavity the fibrous 
 tissue of the network forms a firm, fibrous membrane lining the eavity. This 
 represents an inner periosteum, and is called the endosteum. 
 
 Red marrow (medulla ossium rubra) is found in the diploe of the cranial bones, in 
 the cancellous tissue of the vertebrae, ribs, and sternum, and in the articular ends 
 of the long bones. Red marrow contains much less fat and is less solid than yellow 
 marrow. It consists of a delicate network of connective tissue, supporting a 
 dense capillary plexus ; some fat; and numerous cellular elements. The delicate 
 fibrous membrane surrounding red marrow is called the endosteum. The 
 cellular elements of red marrow (Fig. 2) comprise, first, marrow-cells, or myelocytes, 
 which are protoplasmic masses, capable of amceboid movements, and containing 
 large nuclei. They are not found in normal blood, but are abundant in leukaemia; 
 second, small, nucleated, reddish cells called erythroblasts, resembhngthe nucleated 
 red cells of the blood of the embryo, and eventually by the loss of their nuclei 
 becoming red blood-corpuscles; third, non-nucleated red blood-corpuscles; fourth, 
 giant-cells containing one or more nuclei. They are varieties of leukocytes. The 
 leukocyte group also contains the osteoclasts, eosinophiles, and mast-cells. 
 
 Gelatinous or mucoid marrow is formed by the absorption of the fat and the 
 cellular elements of yellow marrow, and by the serous infiltration of the inter- 
 cellular substance. It is produced by starvation, old age, and certain pathological 
 conditions. 
 
 Each extremity of a long bone is separated from the shaft by a layer of car- 
 tilage known as the cambium layer, the epiphysial cartilage, or the epiphysial 
 disk (Fig. 8). Growth from the cartilages causes an increase in the length of 
 the bone. The cartilages ossify during development, and effect a bony union 
 
STRUCTURE OF BONE 
 
 37 
 
 between the shaft and the head of the bone. Certain bony processes are 
 separated from the bone by cartilage, which later ossifies. 
 
 A Flat Bone is composed of two layers of compact bone with a layer of can- 
 cellous bone (the diploe) interposed. There is no general marrow-cavity; but 
 the spaces between the bone-spicules intercomm.unicate and contain marrow. 
 
 9 ^ 
 
 f® o c«) % Q * I SDiXI ® 
 
 i y- /fe i. m. n, ^ p q r ^ ^ 
 
 Fig. 2. — Cells of red marrow of the guinea-iiiK- a-'''- Myelo-plaques. c-i. Marrow-cells proper, j-i. Erythro- 
 blasts — some in process of division. (Schiifer.) 
 
 The Periosteum is a fibrous membrane adhering to the surface of the bone in 
 nearly every part except at the cartilage-covered extremities. When strong ten- 
 dons or ligaments are attached to the bone, the periosteum is incorporated with 
 them. By means of the periosteum many vessels reach and enter the hard bone 
 through Volkmann's canals. This is shown by stripping the periosteum- from the 
 surface of Hving bone, when small bleeding points are seen, each of which 
 marks the entrance of a vessel from the periosteum. It thus becomes obvious 
 that the loosening of the periosteum, by depriving a portion of the bone of its 
 nourishment, may produce necrosis. The membrane is firmly attached to the 
 bone by trabecular of fibrous tissue, which pene- 
 trate the bone at right angles to its surface, and 
 carry blood-vessels. These trabeculse are called 
 the fibres of Sharpey (Fig. 3). They do not di- 
 rectly enter the Haversian systems, but only the 
 circumferential and intermediate lamellae — parts 
 that are formed by periosteal action. Prolonga- 
 tions from some of these vessels reach the Haver- 
 sian canals, and even the bone-marrow. In the 
 extremities of a long bone, vessels from the peri- 
 osteum penetrate the layer of compact bone and 
 reach the cancellous tissue. In the newborn and 
 in the young the periosteum is composed of three 
 layers: an outer or fibrous layer, containing some 
 blood-vessels, and composed of bundles of white 
 fibrous tissue; a middle or fibro-elastic layer, con- 
 taining some blood-vessels, fibrous tissue, and 
 much elastic tissue; and an inner or osteogenetic layer, which is very vascular and 
 contains numerous cells, which are converted into osteoblasts. These are the 
 cells that form osseous tissue. 
 
 
 Fig. 3. — Fibres of Sharpey from the 
 parietal bone (adult man) isolated by 
 dissociation. (After Kolliker.) 
 
38 THE SKELETON 
 
 Transverse Section of Compact Bone (Figs. 1,4, and 6). — As previously stated, 
 dense bone differs from cancellous bone in the fact that the bone-plates of the 
 former are arranged in Haversian systems, so named from the anatomist 
 Havers. A Haversian system consists of a central canal, running in a more or 
 less longitudinal or slightly curved or spiral direction and called the Haversian 
 canal; from five to ten bone-plates, or lamellae, arranged concentrically around the 
 canal; gaps, called lacunae, between the lamellae, which spaces contain bone-cor- 
 puscles; minute channels, or canaliculi, radiating from the lacunae and passing 
 through the lamellae — some reaching other lacunae, some reaching the Haver- 
 sian canal, and others passing to adjacent Haversian systems. The canaliculi 
 contain processes from the bone-corpuscle. From a study of transverse sections 
 it would be thought that the lamellae always run longitudinally in straight lines 
 or in curves determined by pressure and tension; but Prof. Dixon proved that 
 in the human femur many of the bone-plates are arranged spirally, and thus 
 increased strength is obtained. The same is probably true of other bones. 
 
 Fig. 4. — Transverse section of compact tissue of bone. Magnified about 150 diameters. (Sharpey.) 
 
 There are four varieties of lamellae: (1) the periosteal, peripheral, superficial, 
 or external; (2) the Haversian, or concentric; (3) the interstitial, ground, or inter- 
 mediate; and (4) the perimeduUary, or internal. The periosteal lamellae are some- 
 times called primary, as they are the first to appear, and are formed by the direct 
 transformation of the inner layer of the periosteum into bone. In the shaft of 
 a long bone there are several layers of periosteal lamellae, but no one layer is 
 extensive enough to surround the bone completely. 
 
 In the outer surface of the layer of periosteal lamellae depressions exist that 
 are known as Howship's foveolse, or lacunae. These depressions are made by 
 large cells, called osteoclasts, which destroy bone. There are no Haversian 
 canals in this outer layer, but there are some large channels that convey blood- 
 vessels into the bone, and are known as Volkmann's canals. Many small arteries 
 from the periosteum enter the periphery of the shaft, and also of the epiphyses. 
 A large trunk enters the shaft by the nutrient foramen (foramen nutricius), pass 
 along the nutrient canal [canalis nutricius), and reaches the medullary canal. 
 This vessel is called the nutrient artery. 
 
 The Haversian or concentric lamellae are circular layers arranged around a 
 central space, or canal, known as the Haversian canal. There is no fixed num- 
 ber of these layers, there being usually from five to ten. The layers of each system 
 are parallel to one another, but the layers of different systems cross at various 
 
BLOOD-VESSELS OF BONE 
 
 39 
 
 angles. Between these layers are small, irregular spaces, called lacunse; and 
 extending radially out from the lacunte and piercing the various lamellae are 
 delicate canals, known as canaliculi, which connect the lacunse. The lacuna 
 nearest to the Haversian canal communicates with it by means of canalicuH; 
 and canaliculi also communicate with other Haversian systems. The Haversian 
 canal contains blood-vessels — an artery or a vein, or both an artery and a vein — 
 and a nerve. The vessel in the canal is covered with endothelial cells, and the 
 canal itself is lined with them. The space thus formed is a lymph-space, and 
 into these lymph-spaces the canaliculi empty. Beneath the periosteum and at 
 the periphery of the medullary cavity there are lymph-spaces that are in direct 
 communication with the canaliculi of the Haversian systems. In each lacuna is 
 a bone-cell — a corpuscle that almost fills the space, and sends arms, or processes, 
 out into the canaliculi (Fig. 5j. This bone-cell is an osteoblast. 
 
 The interstitial or intermediate lamellse occupy the spaces between the 
 Haversian systems. They represent the remains of peripheral lamellae. They 
 are usually short and very 
 irregular, but possess lacunse 
 and canaliculi, which are ar- 
 ranged as in the Haversian 
 systems. The perimedullary 
 lamellae are irregular and few 
 in number. 
 
 Fig. 5. — Nucleated bone-cells and their 
 processes, contained in the bone-lacuna and 
 their canaliculi, respectively. From a section 
 through the vertebra of an adult mouse. 
 (Klein and Noble Smith.) 
 
 Fig. 6. — Combined transverse and longitudinal section of 
 compact bone. CH. Longitudinal Haversian canal and 
 anastomosing canals, o. Communicating with medullary 
 cavity. <S'j. Intermediate systems. Spe. Circumferential 
 lamella;. Spi. Perimedullary lamellae. os. Osteoblasts, 
 (Poirier and Charpy.) 
 
 The osteoblasts are irregular, flattened, stellate masses of protoplasm, pos- 
 sessing a number of processes. The protoplasm is granular, and each cell con- 
 tains a large and distinct nucleus. Osteoblasts are met with in the deeper layer 
 of the periosteum, in the endosteum, and in the lacunae. 
 
 Longitudinal Section of Compact Bone (Figs. 6 and 7). — We do not see con- 
 centric rings, as in a transverse section, but rows of lacunae parallel to the course 
 of the Haversian canals — and these canals appear like half-tubes instead of 
 circular spaces. The tubes are seen to branch and communicate, so that each 
 separate Haversian canal runs only a short distance. In other respects the 
 structure closely resembles that of a transverse section. 
 
 Lamellae of Cancellous Bone. — There are no Haversian canals, and canaliculi 
 open into the medullary spaces, which act as do the Haversian canals in com- 
 pact bone. 
 
 Blood-vessels of Bone. — Small arteries derived from the periosteum enter 
 the minute orifices of the compact bone (Volkmann's canals) and reach the 
 
40 THE SKELETON 
 
 Haversian canals of the bony substance. Prolongations from these vessels 
 reach the marrow and communicate with branches from the nutrient artery. 
 The cancellous tissue is supplied by fewer but larger vessels, which are derived 
 from the periosteum, and which often penetrate the cortex of compact bone 
 and ramify in the cavities of the spongy tissue. 
 
 Fig. 7. — From a groiind longitudinal sri'iion t !iroiicrh the dianlivsis of tlie human vilna. All canals are filled 
 with pigment, which is here black. Ihuersian canals are cut longitudinally. X 90. (Szymonowicz.) 
 
 The medullary canal of a long bone is supplied by a large artery (sometimes 
 more than one) called the nutrient artery. It enters the bone by the nutrient 
 foramen, which is usually near the centre of the shaft, runs in an oblique canal 
 through the compact structure, giving off branches to this structure, and enters 
 the medullary cavity, and sends branches upward and downward. These branches 
 communicate with branches from the periosteal vessels and subdivide into capil- 
 laries, which pass into comparatively large vessels. The walls of the vessels are 
 very thin, and in some places deficient; the venous blood enters the spaces of 
 the red marrow, and the current becomes extremely slow. Small veins collect 
 the venous blood and emerge from the bone. 
 
 In the humerus the nutrient canal is directed toward the elbow-joint; in the 
 radius and the ulna the nutrient canals are directed toward the elbow-joint; in 
 the femur, the canal is directed toward the hip-joint; and in the tibia and the 
 fibula, the canals are directed toward the ankle-joint. As Professor Cunningham 
 states it: "In the upper limb the vessels flow toward the elbow; while in the 
 
CHEMICAL COMPOSITION OF BONE 41 
 
 lower limb they pass from the knee." The red marrow of the extremities and 
 the medulla of the entire shaft, and the bone of the shaft, except the circum- 
 ferential lamellae, are supplied by the nutrient artery. The circumferential 
 lamellae, wholly, and the cancellous tissue of the extremities, in part, and the 
 medulla of the shaft to a very small extent are supplied by vessels from the 
 periosteum. The extremities of a bone also receive articular arteries. In most 
 of the flat bones, and in some of the short bones, one or more large apertures exist 
 for the passage of blood-vessels to the central parts of the bone. 
 
 Veins emerge from the long bones in three places: 1. One or two large veins 
 accompany the nutrient artery. 2. Numerous veins emerge at the articular 
 extremities. 3. Many small veins arise in and emerge from compact substance. 
 The latter two classes do not accompany arteries. The veins in the marrow 
 and in the bone are devoid of valves; but immediately after emerging from the 
 bone they have numerous valves. 
 
 In the flat cranial bones the veins are numerous and large; as seen in diploic 
 canals, the walls of which are composed of osseous tissue, perforated, here and 
 there, for branches from adjacent cancelli. In all cancellous tissue the venous 
 channels are similarly arranged, and the veins have very thin coats and are 
 without valves. When the bone is divided, the vessels remain open; they do 
 not retract into their bony canals, and readily absorb any septic matter that 
 may be present. 
 
 The lymphatics are chiefly periosteal ; but some enter, the bone, along with the 
 vessels. Cruikshank has traced them into the substance of the bone and Klein 
 has described them as running in the Haversian canals. The perivascular spaces 
 of the Haversian canals are lymph-spaces. 
 
 Nerves are partly medullated and partly non-medullated, are distributed freely 
 to the periosteum, and some of the fibres terminate in this structure as Pacinian 
 corpuscles. Nerves accompany the nutrient arteries into the interior of the 
 bone, and also reach the marrow from the periosteum by way of Volkmann's 
 canals and the Haversian canals. They certainly supply the arterial coats. 
 It is not, as yet, determined whether nerves do or do not terminate in bone-tissue. 
 Stroh maintains that occasionally they terminate in bone-corpuscles. According 
 to Kolliker nerves are most numerous in the articular extremities of the long 
 bones, in the vertebnie, and the large flat bones. 
 
 Chemical Composition of Bone. — Bone consists of an animal and an earthy 
 part intimately combined. 
 
 The animal part may be obtained by immersing the bone for a considerable 
 time in dilute mineral acid, after which process the bone comes out exactly the 
 same shape as before, but perfectly flexible, so that a long bone (one of the ribs, 
 for example) can easily be tied into a knot. If now a transverse section is made, 
 the same general arrangement of the Haversian canals, lamellae, lacunae, and 
 canaliculi is seen, though not so plainly, as in the ordinary section. 
 
 The earthy part may be obtained separate by calcination, by which the animal 
 matter is completely burned out. The bone will still retain its original form, but 
 it will be white and brittle, will have lost about one-third of its original weight, 
 and will crumble with the slightest force. The earthy matter confers on bone 
 its hardness and rigidity, and the animal matter its tenacity. 
 
 The mineral matter consists of phosphate, carbonate, and fluoride of calcium, 
 chloride of sodium, and phosphate of magnesium. 
 
 The animal basis is largely composed of ossein, or fat collagen. When boiled 
 with water, especially under pressure, fat collagen is almost entirely resolved 
 into gelatin. 
 
 The organic matter of bone forms about one-third; the inorganic matter, 
 two-thirds. The exact composition, according to Professor Cunningham, is, of 
 
42 THE SKELETON 
 
 organic matter, 31.04 parts; of inorganic matter, 68.97 parts. Of the earthy 
 matter, five-sixths is calcium phosphate. Even after the removal of all the 
 marrow a small percentage of fat is still found in bone. 
 
 Some of the diseases to which bones are liable mainly depend on the dispro- 
 portion between the two constituents of bone. Thus in the disease called rickets, 
 so connnon in the children of the poor, the bones become bent and curved, either 
 from the superincumbent weight of the body or under the action of certain mus- 
 cles. This depends upon some defect of nutrition by which bone becomes deprived 
 of its normal proportion of earthy matter, while the animal matter is of unhealthy 
 quality. In the vertebrae of a rickety subject Bostock found in 100 parts 79.75 
 animal and 20.25 earthy matter. Osteomalacia is a disease of adults charac- 
 terized by the decalcification of existing bone and by the failure in calcification 
 of new osteoid material. In this disease the bone shows a diminution in 
 inorganic and an increase in organic material. Senile atrophy renders bones 
 porous and brittle, and portions of bone may actually be absorbed, as is seen in 
 the disappearance of the alveolae in old age. In senile atrophy of the calvaria 
 the outer table becomes very thin, porous, and brittle, and the inner table often 
 becomes rough and thicker from the formation of new bone. In senile atrophy 
 of a long bone there is absorption of bone from the surface by osteoclasts in 
 Howship's lacunae, and absorption of the inner surface. The bone becomes 
 porous and the medulla becomes more fatty. This change is not, as was so 
 
 long taught, a decrease in organic matter 
 and an increase in mineral matter, but is an 
 actual alteration in the structure of the bone. 
 Ossification and Growth of Bone. — For 
 the early development of the skeleton the 
 reader is referred to text-books on embry- 
 ology. Embryonic connective-tissue cells of 
 the mesoblast develop membrane. Membrane 
 may become bone directly or cartilage may be 
 deposited, which cartilage by the process of 
 ossification is formed into bone. The tissue 
 which is eventually to become bone contains 
 cellular elements which evolve into osteoblasts, 
 ^^^tf ^^^ffffl or bone-forming cells. Osteoblasts exist in the 
 
 I B X ^ I ' « I I connective tissues which become bone by in- 
 
 " * tramembranous ossification, and in the deeper 
 
 Fig. 8.— Schematic diagram showing epi- lavers of the tissuc Called perichondrium which 
 
 physis and diaphysis and line of ossification. . •' i i • i i i 
 
 Ep. Epiphysis of endochondral bone. zpt. mvests Cartilage and whicli bccomcs the osteo- 
 
 Zone of proliferation, zc. Zone of calcifica- . , » i • , t • e 
 
 tion. ca. Cartilage. (Poirier and Charpy.) gCnctlC layer OI the pcriOStCUm. lU VlCW OI 
 
 the fact that in the foetal skeleton some bones 
 are preceded by membrane (parietal bones, frontal bone, upper part of tabular 
 surface of occipital bone, most of bones of the face), and others are preceded by 
 rods of cartilage (the long bones), two kinds of ossification are described — viz., 
 the intramembranous and the intracartilaginous. Professor Cunningham says all 
 true bone may be correctly regarded as of membranous origin, though its appear- 
 ance is preceded in some instances by the deposition of cartilage ; in this case 
 calcification of the cartilage is an essential stage in the process of bone forma- 
 tion, but the ultimate conversion into true bone, with characteristic Haversian 
 systems, leads to the absorption and disappearance of this primitive calcified 
 cartilage. Intramembranous ossification forms membrane bones, that is, forms 
 bone directly from fibrous tissue, there being no intermediate cartilaginous 
 stage. 
 
 Intracartilaginous ossification consists in the ossification of cartilage. 
 
OSSIFICATION AND GROWTH OF BONE 
 
 43 
 
 Intramembranous Ossification. — In the case of bones which are developed in 
 membrane no cartilaginous mould precedes the appearance of the bone-tissue. 
 The membrane, which occupies the place of the future bone, is of the nature of 
 connective tissue, and ultimately forms the periosteum. At this stage it is seen 
 to be composed of fibres and granular cells in a matrix. The outer portion is 
 more fibrous, while internally the cells or osteoblasts predominate; the whole 
 tissue is richly supplied with blood-vessels. At the outset of the process of bone- 
 formation a little network of bony spiculse is first noticed radiating from the point 
 or centre of ossification. When these rays of growing bone are examined with a 
 microscope, they are found to consist at their growing point of a network of fine, 
 clear fibres and granular corpuscles, with an intervening ground substance 
 (Fig. 9). The fibres are termed osteogenetic fibres, and are made up of fine fibrils 
 
 Union of— 
 
 adjacent 
 
 spicules. 
 
 Osteoblasts. <-:^ 
 
 Osteogenetic 
 
 fibres. 
 
 Calcific deposit 
 
 between the 
 fibres. 
 
 Bony 
 spicules. 
 
 Fig. 9. — Part of the growing edge of the developing parietal bone of a fcetal cat. (After J. Lawrence.) 
 
 differing little from those of white fibrous tissue. Like 'them, they are probably 
 deposited in the matrix through the influence of the cells — in this case the osteo- 
 blasts. The osteogenetic fibres soon assume a dark and granular appearance from 
 the deposition of calcareous granules in the fibres and in the intervening matrix, 
 and as they calcify they are found to enclose some of the granular corpuscles or 
 osteoblasts. By the fusion of the calcareous granules the bony tissue again assumes 
 a more transparent appearance, but the fibres are no longer so distinctly seen. 
 The involved osteoblasts form the corpuscles of the future bone, the spaces in 
 which they are enclosed constituting the lacunae. As the osteogenetic fibres grow 
 out to the periphery they continue to calcify, and give rise to fresh bone-spicules. 
 Thus a network of bone is formed, the meshes of which contain the blood-vessels 
 and a delicate connective tissue crowded with osteoblasts. The bony trabecular 
 thicken by the addition of fresh layers of bone formed by the osteoblasts on their 
 surface, and the meshes are correspondingly encroached upon. Subsequently 
 successive layers of bony tissue are deposited under the periosteum and around 
 the larger vascular channels, which become the Haversian canals, so that the bone 
 increases much in thickness. 
 
 Intracartilaginous Ossification. — Just before ossification begins the bone is 
 entirely cartilaginous, and in the long bone, which may be taken as an example, the 
 process commences in the centre and proceeds toward the extremities, which for 
 some time remain cartilaginous. Subsequently a similar process commences in one 
 
44 
 
 THE SKELETON 
 
 or more places in those extremities and gradually extends through them. The 
 extremities do not, however, become joined to the shaft by bony tissue until growth 
 has ceased, but are attached to it by a layer of cartilaginous tissue termed the 
 epiphysial cartilage (Fig. 8). 
 
 The first step in the ossification of the cartilage is that the cartilage-cells, at 
 the point where ossification is commencing and which is termed a centre of ossifica- 
 tion, enlarge and arrange themselves in rows (Fig. 10). The matrix in which they 
 are embedded increases in quantity, so that the cells become further separated 
 from each other. A deposit of calcareous material now takes place in this matrix, 
 
 Fig. 10. — Section of fcetal bone of cat. ir. Irruption 
 of the subperiosteal tissue, p. Fibrous layer of the peri- 
 osteum, o. Layer of osteoblasts. im,. Subperiosteal 
 bony deposit. (From Quain's Anatomy, E. A. Schafer.) 
 
 Fig. 11. — Part of a longitudinal section of 
 the developing femur of a rabbit, o. Flat- 
 tened cartilage-cells, h. Enlarged cartilage- 
 cells, c, d. Newly formed bone. e. Osteo- 
 blasts. /. Giant-cells or osteoclasts. .0, h. 
 Shrunken cartilage-cells. (From Atlas of His- 
 tology, Klein and Noble Smith.) 
 
 between the rows of cells, so that they become separated from each other by longi- 
 tudinal columns of calcified matrix, presenting a granular and opaque appearance. 
 Here and there the matrix between two cells of the same row also becomes calci- 
 fied, and transverse bars of calcified substance stretch across from one calcareous 
 column to another. Thus there are longitudinal groups of the cartilage-cells 
 enclosed in oblong cavities, the walls of which are formed of calcified matrix, 
 which cuts off all nutrition from the cells, and they, in consequence, waste, leav- 
 ing spaces called the primary areolae (Sharpey). 
 
 At the same time that this process is going on in the centre of the solid bar of 
 cartilage of which the foetal bone consists, certain changes are taking place on 
 
OSSIFICATION AND GROWTH OF BONE 
 
 45 
 
 its surface. This is covered by a very vascular membrane, the perichondrium, 
 entirely similar to the embryonic connective tissue already described as constituting 
 the basis of membrane-bone, on the inner surface of which, that is to say, on the 
 surface in contact with the cartilage, are gathered the formative cells, the osteo- 
 blasts. By the agency of these cells a thin layer of bony tissue is being formed 
 between the perichondrium and the cartilage, by the intramemhranous mode of 
 ossification just described. There are, then, in this first stage of ossification, two 
 processes going on simultaneously: in the centre of the cartilage the formation 
 of a number of oblong spaces, formed of calcified matrix and containing the 
 withered cartilage-cells, and on the surface of the cartilage the formation of a 
 layer of true membrane-bone. The second stage consists in the prolongation 
 into the cartilage of processes of the 
 deeper or osteogenetic layer of the 
 perichondrium, which has now be- 
 come periosteum (Fig. 10, ir). The 
 processes consist of blood-vessels and 
 cells — osteoblasts, or bone -formers, and 
 osteoclasts, or bone -destroyers. The 
 latter are similar to the giant-cells 
 (myelo-plaques) found in marrow, 
 and they excavate passages through 
 
 Fig. 12. — Transverse section from the femur of a 
 human embryo about eleven weeks old. a. A med- 
 ullary sinus cut transversely, and ft, another, longi- 
 tudinally. C. Osteoblasts, d. Newly formed os.seous 
 substance of a lighter color, e. That of greater age. 
 /. Lacunip with their cells, g. A cell still united to 
 an osteoblast. 
 
 Fig. 13. — Vertical section from the edge of the 
 ossifying portion of the diaphysis of a metatar- 
 sal bone from a fojtal calf. a. Ground-mass of 
 the cartilage, b. Of the bone. C. Newly formed 
 bone-cells in profile, more or less embedded in in- 
 tercellular substance, d. Medullary canal in pro- 
 cess of formation, with vessels and medullary 
 cells. «,/. Bone-cells on their broad aspect, g. 
 Cartilage-capsules arranged in rows, and partly 
 with shrunken cell-bodies. (After Miiiler.) 
 
 the new-formed bony layer by absorption, and pass through it into the cal- 
 cified matrix (Fig. 10). Wherever these processes come in contact with the 
 calcified walls of the primary areolae they absorb it, and thus cause a fusion 
 of the original cavities and the formation of larger spaces, which are termed 
 the secondary areolae (Sharpey), or medullary spaces (Miiiler). In these second- 
 ary spaces the original cartilage-cells, having disappeared, become filled 
 with embryonic marrow, consisting of osteoblasts and vessels, and derived in 
 
46 
 
 THE SKELETON 
 
 the manner described above, from the osteogenetic layer of the periosteum 
 (Fig. 11). 
 
 Thus far there has been traced the formation of enlarged spaces (secondary 
 areolae), the perforated walls of which are still formed by calcified cartilage- 
 matrix, containing an embryonic marrow, derived from the processes sent in 
 from the osteogenetic layer of the periosteum, and consisting of blood-vessels 
 and round-cells, osteoblasts (Fig, 11), The walls of these secondary areolae are 
 at this time of only inconsiderable thickness, but they become thickened by 
 the deposition of layers of new bone on their interior. This process takes place 
 in the following manner: Some of the osteoblasts of the embryonic marrow, 
 after undergoing rapid division, arrange themselves as an epithelioid layer on 
 the surface of the wall of the space (Fig. 12), This layer of osteoblasts form a 
 bony stratum, and thus the wall of the space becomes gradually covered with a 
 layer of true osseous substance. On this a second layer of osteoblasts arrange 
 themselves, and in their turn form an osseous layer. By the repetition of this 
 process the original cavity becomes very much reduced in size, and at last only 
 remains as a small circular hole in the centre, containing the remains of the 
 embryonic marrow — that is, a blood-vessel and a few osteoblasts. This small 
 cavity constitutes the Haversian canal of the perfectly ossified bone. The successive 
 layers of osseous matter which have been laid down and which encircle this central 
 
 canal constitute the lamellae of 
 which, as we have seen, each 
 Haversian system is made up. 
 As the successive layers of os- 
 teoblasts form osseous tissue, 
 certain of the osteoblastic cells 
 remain included between the 
 various bony layers. These 
 persist as the corpuscles of the 
 future bone, the spaces enclos- 
 ing them forming the lacimae 
 (Figs. 12 and 14). The canal- 
 iculi, at first extremely short, are 
 supposed to be extended by ab- 
 sorption, so as to meet those of 
 neighboring lacunae. 
 
 Such are the changes which 
 may be observed at one partic- 
 ular point, the centre of ossifi- 
 cation. While they have been going on here a similar process has been set up 
 in the surrounding parts and has been gradually proceeding toward the end of 
 the shaft, so that in the ossifying bone all the changes described above may be 
 seen in different parts, from the true bone in the centre of the shaft to the hyaline 
 cartilage at the extremities. The bone thus formed differs from the bone of the 
 adult in being more spongy and less regularly lamellated. 
 
 Thus far, then, we have followed the steps of a process by which a solid bony 
 mass is produced, having vessels running into it from the periosteum, Haversian 
 canals in which those vessels run, medullary spaces filled with foetal marrow, 
 lacunae with their contained bone-cells, and canaliculi growing out of these 
 lacunae. 
 
 This process of ossification, however, is not the origin of the whole of the 
 skeleton, for even in those bones in which the ossification proceeds in a great 
 measure from a single centre, situated in the cartilaginous shaft of a long bone, a 
 considerable part of the original bone is formed by intramembranous ossification 
 
 Fig. 14. — Osteoblasts from the parietal bone of a human embryo 
 thirteen weeks old. a. Bony septa with the cells of the lacunse. 
 0. Layers of osteoblasts, c. The latter in transition to bone- 
 corpuscles. (After Gegenbauer.) 
 
OSSIFICATION AND GROWTH OF BONE 47 
 
 beneath the perichondrium or periosteum ; so that the girth of the bone is increased 
 by bony deposit from the deeper layer of this membrane. The shaft of the bone 
 is at first sohd, but a tube is hollowed out in it by absorption around the vessels 
 passing into it, which becomes the medullary canal. This absorption is supposed 
 to be brought about by large "giant-cells," the so-called osteoclasts of KoUiker 
 (Fig. 11). They vary in shape and size, and are known by containing a large 
 number of clear nuclei, sometimes as many as twenty. The occurrence of 
 similar cells in some tumors of bones has led to such tumors being denominated 
 "myeloid." 
 
 As more and more bone is removed by this process of absorption from the 
 interior of the bone to form the medullary canal, so more and more bone is 
 deposited on the exterior from the periosteum, until at length the bone has attained 
 the shape and size which it is destined to retain during adult life. As the ossifi- 
 cation of the cartilaginous shaft extends toward the articular ends it carries with 
 it, as it were, a layer of cartilage, or the cartilage grows as it ossifies, and thus the 
 bone is increased in length. During this period of growth the articular end, or 
 epiphysis, remains for some time entirely cartilaginous ; then a bony centre appears 
 in it, and it commences the same process of intracartilaginous ossification; but 
 this process never extends to any great distance. The epiphyses remain separated 
 from the shaft by a narrow cartilaginous layer for a definite time (Fig. 8). 
 This layer ultimately ossifies, the distinction between shaft and epiphysis is 
 obliterated, and the bone assumes its completed form and shape. The same 
 remarks also apply to the processes of bone which are separately ossified, such as 
 the trochanters of the femur. The bones, having been formed, -continue to 
 grow until the body has acquired its full stature. They increase in length by 
 ossification continuing to extend in the epiphysial cartilage, which goes on grow- 
 ing in advance of the ossifying process. They increase in circumference by 
 deposition of new bone, from the deeper layer of the periosteum, on their external 
 surface, and at the same time an absorption takes place within, by which the 
 medullary cavity is increased. 
 
 The medullary spaces which characterize the cancellous tissue are produced by 
 the absorption of the original foetal bone in the same way as the original medul- 
 lary canal is formed. The distinction between the cancellous and compact tissue 
 appears to depend essentially upon the extent to which this process of absorption 
 has been carried ; and we may perhaps remind the reader that in morbid states of 
 the bone inflammatory absorption produces exactly the same change, and con- 
 verts portions of bone naturally compact into cancellous tissue. 
 
 The number of ossific centres is different in different bones. In most of the 
 short bones ossification commences by a single point in the centre, and proceeds 
 toward the circumference. In the long bones there is a central point of ossifica- 
 tion for the shaft or diaphysis; and one or more for each extremity, the epiphysis. 
 That for the shaft is the first to appear. The union of the epiphyses with the 
 shaft takes place in the reverse order to that in which their ossification began, with 
 the exception of the fibula, and appears to be regulated by direction of the nutrient 
 artery of the bone. Thus the nutrient arteries of the bones of the arm and fore- 
 arm are directed toward the elbow, and the epiphyses of the bones forming this 
 joint become united to the shaft before those at the shoulder and wrist. In the 
 lower limb, on the other hand, the nutrient arteries pass in a direction from the 
 knee; that is, upward in the femur, downward in the tibia and fibula; and in 
 them it is observed that the upper epiphysis of the femur and the lower epiphysis 
 of the tibia and fibula become first united to the shaft. 
 
 Where there is only one epiphysis, the medullary artery is directed toward 
 that end of the bone where there is no additional centre, as toward the acromial 
 end of the clavicle, toward the distal end of the metacarpal bone of the thumb 
 
48 THE SKELETON 
 
 and great toe, and toward the proximal end of the other metacarpal and meta- 
 tarsal bones. 
 
 Besides these epiphyses for the articular ends, there are others for projecting 
 parts or processes, which are formed separately from the bulk of the bone. For 
 an account of these the reader is referred to the description of the individual 
 bones in the sequel. 
 
 A knowledge of the exact periods when the epiphyses become joined to the 
 shaft is often of great importance in medico-legal inquiries. It also aids the sur- 
 geon in the diagnosis of many of the injuries to which the joints are liable; for it 
 not infrequently happens that on the application of severe force to a joint the 
 epiphysis becomes separated from the shaft, and such an injury may be 
 mistaken for a fracture or dislocation. 
 
 THE VERTEBRAL OR SPINAL COLUMN (THE SPINE) 
 (COLUMNA VERTEBRALIS). 
 
 The spine is a flexuous and flexible column formed of a series of bones called 
 vertebrae (from vertere, to turn). 
 
 The vertebrae are thirty-three in number, and have received the names cervical, 
 dorsal or thoradc, lumbar, sacral, and coccygeal, according to the position which 
 they occupy; seven being found in the cervical region, twelve in the dorsal, five 
 in the lumbar, five in the sacral, and four in the coccygeal. 
 
 This number is sometinies increased by an additional vertebra in one region, or 
 the number may be diminished in one region, the deficiency being supplied by 
 an additional vertebra in another. These observations do not apply to the cervical 
 portion of the spine, the number of bones forming which is seldom increased or 
 diminished. 
 
 The vertebrae in the upper three regions of the spine remain separate through- 
 out life, and are known as true or movable vertebrae; but those found in the 
 sacral and coccygeal regions are in the adult firmly united, so as to form two 
 bones — five entering into the formation of the upper bone or sacrum, and four into 
 the terminal bone of the spine or coccyx. The fused vertebrae are known as 
 false or immovable vertebrae. 
 
 GENERAL CHARACTERS OF A VERTEBRA. 
 
 Each vertebra consists of two essential parts — an anterior solid segment, the 
 body, or centrum, and a posterior segment, the arch (arcus vertebra;), or the neural 
 arch. The neural arch is formed of two pedicles and two laminae, supporting 
 seven processes — viz., four articular, two transverse, and one spinous. 
 
 The bodies of the vertebrae are piled one upon the other, forming a strong 
 pillar for the support of the cranium and trunk; the arches forming a hollow 
 cylinder behind the bodies for the protection of the spinal cord (spinal canal or 
 neural canal). The different vertebrae are connected too:ether bv means of the 
 articular processes and the intervertebral fibrocartilages; while the transverse 
 and spinous processes serve as levers for the attachment of muscles which 
 move the different parts of the spine. Lastly, between each pair of vertebrae 
 apertures exist through which the spinal nerves pass from the cord. Each of 
 these constituent parts must now be separately examined. 
 
 Body, or Centrum (corpus vertebra'). — The body is the largest part of a vertebra. 
 Above and below it is flattened; its upper and lower surfaces are rough for the 
 attachment of the intervertebral fibro-cartilages, and each presents a rim around 
 its circumference. In front it is convex from side to side, concave from above 
 downward. Behind it is flat from above downward and slightly concave from 
 
THE CERVICAL VERTEBRA 49 
 
 side to side. Its anterior surface is perforated by a few small apertures, for 
 the passage of nutrient vessels; while on the posterior surface is a single large, 
 irregular aperture, or occasionally more than one, for the exit of veins from the 
 body of the vertebra — the venae basis vertebrae. 
 
 Pedicles. — The pedicles are two short, thick pieces of bone, which project 
 backward, one on each side, from the upper part of the body of the vertebra, at 
 the line of junction of its posterior and lateral surfaces. Each pedicle {radix 
 arcus i^ertebra') is a root of the vertebral arch. The concavities above and below 
 the pedicles are the superior and inferior intervertebral notches or grooves (incisura 
 vertehralis superior et inferior) ; they are four in number, two on each side, the 
 inferior ones being generally the deeper. When the vertebrae are articulated the 
 notches of each contiguous pair of bones form the intervertebral foramina {jora- 
 mina intervertebralia) , which communicate with the spinal canal and transmit 
 the spinal nerves and bloodvessels. 
 
 Laminse. — The lamin* are two broad plates of bone which complete the neural 
 arch by fusing together in the middle line behind. They enclose a foramen, the 
 spinal or vertebral foramen (foramen vertebrale), which serves for the protection of 
 the spinal cord. When the vertebrte are joined they form, with their ligaments, 
 the vertebral canal {spinal or neural canal, canalis vertehralis). The laminse are 
 connected to the body by means of the pedicles. Their upper and lower borders 
 are rough, for the attachment of the ligamenta subflava. 
 
 Processes. Spinous Process {processus spinosus). — The spinous process projects 
 backward from the junction of the two laminse, and serves for the attachment of 
 muscles and ligaments. 
 
 Articular Processes. — The articular processes {zygapophyses), four in number, 
 two on each side, spring from the junction of the pedicles with the laminse. Each 
 superior process (processus articularis superior) projects upward, its articular 
 surface (fades articularis superior) being directed more or less backward; each 
 inferior process (processus articularis inferior) projects downward, its articular 
 surface (fades articularis inferior) looking more or less forward.^ 
 
 Transverse Processes (processus transversi). — The transverse processes, two in 
 number, project one at each side from the point where the lamina joins the 
 pedicle, between the superior and inferior articular processes. They also serve 
 for the attachment of muscles and ligaments. 
 
 The Cervical Vertebrae (Vertebrae Cervicales) (Fig. 15). 
 
 The cervical vertebrae are smaller than those in any other region of the spine, 
 and may be readily distinguished by the foramen in the transverse process, which 
 does not exist in the transverse process of either a dorsal or lumbar vertebra. 
 
 Body. — The body (centrum) is small, comparatively dense, and broader from 
 side to side than from before backward. The anterior and posterior surfaces 
 are flattened and of equal depth; the former is placed on a lower level than the 
 latter, and its inferior border is prolonged downward, so as to overlap the upper 
 and fore part of the vertebra below. Its upper surface is concave transversely, 
 and presents a projecting lip on each side; its lower surface is convex from side 
 to side, concave from before backward, and presents laterally a shallow concavity 
 which receives the corresponding projecting lip of the adjacent vertebra. 
 
 Pedicles. — The pedicles are directed outward and backward, and are 
 attached to the body midway between the upper and lower borders, so that 
 the superior intervertebral notch is as deep as the inferior, but it is, at the same 
 time, narrower. 
 
 ' It may, perhaps, be as well to remind the reader that the direction of a surface is determined by that of a 
 line drawn at right angles to it. 
 
 4 
 
50 
 
 THE SKELETON 
 
 Laminae. — The laminae are narrow, long, thinner above than below, and 
 overlap each other, enclosing the spinal foramen, which is very large, and of a 
 triangular form. 
 
 Processes. Spinous Process. — The spinous process is short, and bifid at the 
 extremity, to afford greater extent of surface for the attachment of muscles, the 
 two divisions being often of unequal size. They increase in length from the fourth 
 to the seventh vertebra. 
 
 Anterior tubercle of trans- 
 verse process, 
 
 Costo-transverse foramen for 
 
 vertebral artery and vein and 
 
 sympathetic plexus.^ 
 
 Posterior tubercle of 
 transverse process. 
 
 Costal cartilage. 
 
 Transverse process. 
 
 ^-Superior articular 
 process. 
 Inferior articular process. 
 
 Fig. 15. — Cervical vertebra. 
 
 Articular Processes. — The articular processes are flat, oblique, and of an oval 
 form : the superior are directed backward and upward ; the inferior forward and 
 downward. 
 
 Transverse Processes. — The transverse processes are short, directed down- 
 ward, outward, and forward, bifid at their extremity, and marked by a 
 groove along their upper surface, which runs dowmward and outward from the 
 superior intervertebral notch and serves for the transmission of one of the cer- 
 vical nerves. They are situated in front of the articular processes and on the 
 outer side of the pedicles. The transverse processes are pierced at their base by 
 a foramen, for the transmission of the vertebral artery, vein, and a plexus of 
 sympathetic nerves. This foramen is known as the transverse foramen, the costo- 
 transverse foramen, and the vertebrarterial foramen (foramen transversarium) . 
 Each process is formed by two roots: the anterior root, sometimes called the 
 costal process, arising from the side of the body, and is the homologue of the rib 
 in the dorsal region of the spine; the posterior root springs from the junction of 
 the pedicle with the lamina, and corresponds with the transverse process in the 
 dorsal region. It is by the junction of the two that the foramen for the vertebral 
 vessels is formed. The extremity of each of the anterior roots forms the anterior 
 tubercle {tubercidum anterius) and the extremity of each of the posterior roots the 
 posterior tubercle {tuhercvlum 'posterius) of the transverse processes.^ 
 
 The peculiar vertebrae in the cervical regions are the first, or atlas; the second, 
 or axis; and the seventh, or vertebra prominens. The great modifications in the 
 form of the atlas and axis are designed to admit of the nodding and rotatory 
 movements of the head. 
 
 Atlas. — The atlas (Fig. 16) is so named from supporting the globe of the head. 
 The chief peculiarities of this bone are that it has neither body nor spinous process. 
 The body is detached from the rest of the bone, and forms the odontoid process of 
 
 _ ' The anterior tubercle of the transverse process of the sixth cervical vertebra is of large size, and is some- 
 ^vmeii known as " Chassaignac's " or the "carotid tubercle" (tubercidum caroticum). It is in close relation 
 with the carotid artery, which lies in front and a little external to it; so that, as was first pointed out by 
 Lhassaignac, the vessel can with ease be compressed against it. 
 
THE CERVICAL VERTEBRA 
 
 51 
 
 the second vertebra; while the parts corresponding to the pedicles join in front to 
 form the anterior arch. The atlas is ring-like, and consists of an anterior arch, a 
 posterior arch, and two lateral masses. The anterior arch (arcus anterior) forms about 
 one-fifth of the ring; its anterior surface is convex, and presents about its centre a 
 tubercle (tuberculum anterius), for the attachment of the Longus colli muscle; pos- 
 teriorly it is concave, and marked by a smooth, oval facet, called the circular facet 
 (fovea c^cn^t^), covered with cartilage, for articulation with the odontoid process of the 
 
 Tubercle. 
 
 Diagram of section of odontoid 
 process. 
 
 Diagram of section of 
 transverse ligament. 
 
 Foramen for 
 vertebral artery. 
 
 Groove for vertebral artery 
 and 1st cervical nerve. 
 
 Budimentary spinous process. , 
 
 Fig. 16. — F'irst cervical vertebra, or atlas. 
 
 axis. The upper and lower borders give attachment to the anterior occipito-atlantal 
 and the anterior atlanto-axial ligaments, which connect it with the occipital bone 
 above and the axis below. The posterior arch [arcus 'posterior) forms about two- 
 fifths of the circumference of the bone; it terminates behind in a tubercle {tuber- 
 culum posterius), which is the rudiment of a spinous process, and gives origin to 
 the Rectus capitis posticus minor. The diminutive size of this process prevents 
 any interference in the movements between the atlas and the cranium. The pos- 
 terior part of the arch presents above and behind a rounded edge for the attach- 
 ment of the posterior occipito-atlantal ligament, while in front, immediately 
 behind each superior articular process, is a groove (sulcus arterice vertehralis), 
 sometimes converted into a foramen by a delicate bony spiculum, which arches 
 backward from the posterior extremity of the superior articular process. These 
 grooves represent the superior intervertebral notches, and are peculiar from being 
 situated behind the articular processes, instead of in front of them, as in the 
 other vertebrse. They serve for the transmission of the vertebral artery, which, 
 ascending through the foramen in the transverse process, winds round the lateral 
 mass in a direction backward and inward. They also transmit the suboccipital 
 (first spinal) nerve. On the under surface of the posterior arch, in the same 
 situation, are two other grooves, placed behind the lateral masses, and repre- 
 senting the inferior intervertebral notches of other vertebrae. They are much 
 less marked than the superior. The lower border also gives attachment to the 
 posterior atlanto-axial ligament, which connects it with the axis.. The lateral 
 masses (massoe. laterales) are the most bulky and solid parts of the atlas, in order 
 to support the weight of the head; they present two articulating surfaces above, 
 and two below. Each superior process (fovea articularis superior) is of large size, 
 oval, concave, and approaches its companion in front, but diverges from it 
 behind; it is directed upward, inward, and a little backward, forming a kind of 
 cup for the corresponding condyle of the occipital bone. The two processes are 
 admirably adapted to the nodding movements of the head. Not infrequently 
 they are partially subdivided by a more or less deep indentation, which encroaches 
 upon each lateral margin. Each inferior articular process (fades articularis inferior) 
 
52 
 
 THE SKELETON 
 
 is circular in form, flattened or slightly concave, and directed downward and 
 inward, articulating with the axis. The inferior processes permit the rotatory 
 movements. Just below the inner margin of each superior articular surface is 
 a small tubercle, for the attachment of the transverse ligament, which, stretching 
 across the ring of the atlas, divides it into two unequal parts or arches; the anterior 
 or smaller segment receiving the odontoid process of the axis, the posterior allow- 
 ing the transmission of the spinal cord and its membranes. This part of the 
 spinal canal is of considerable size, to afford space for the spinal cord r and hence 
 lateral displacement of the atlas may occur without compression of this structure. 
 The transverse processes are of large size, project directly outward and down- 
 ward from the lateral masses, and serve for the attachment of special muscles 
 which assist in rotating the head. They are long, not bifid, and perforated at 
 their base by a canal for the vertebral artery, which is directed from below, 
 upward, and backward. 
 
 Odontoid process. 
 
 Bough surface for check ligaments. 
 Articviar surface for transverse ligament. 
 
 Articular surface for 
 atlas. 
 
 Spinous process: 
 
 Inferior artictdar process. 
 Fig. 17. — Second cervical vertebra, or axis. 
 
 Axis. — The axis (epistropheus) (Fig. 17) is the pivot upon which the first 
 vertebra, carrying the head, rotates, hence the name, axis. The most distinctive 
 character of this bone is the strong, prominent process, tooth-like in form (hence 
 the name odontoid process, or dens), which rises perpendicularly from the upper 
 surface of the body. The body is deeper in front than behind, and prolonged 
 downward anteriorly so as to overlap the upper and fore part of the next 
 vertebra. It presents in front a median longitudinal ridge, separating two 
 lateral depressions, for the attachment of the Longus colli muscle of either side. 
 The odontoid process presents two articulating surfaces covered with cartilage : 
 one in front, of an oval form, for articulation with the atlas (fades articularis 
 anterior); another behind (fades articularis posterior), for the transverse ligament 
 — the latter frequently encroaching on the sides of the process. The apex is 
 pointed, and gives attachment to the middle odontoid ligament (ligamentum 
 apids dentis). Below the apex the process is somewhat enlarged, and presents 
 on either side a rough impression for the attachment of the lateral fasciculi of 
 the odontoid or check ligaments, which connect it to the occipital bone; the base 
 of the process, where it is attached to the body, is constricted, so as to prevent 
 displacement from the transverse ligament, which binds it in this situation to the 
 anterior arch of the atlas. Sometimes, however, this process does become di.s- 
 placed, especially in children, in whom the ligaments are more relaxed: instant 
 death is the result of this accident. The internal structure of the odontoid process 
 is more compact than that of the body. The pedicles are broad and strong, espe- 
 cially their anterior extremities, which coalesce with the sides of the body and the 
 
THE THORACIC OB DORSAL VERTEBRA 
 
 53 
 
 Body. 
 
 root of the odontoid process. The laminae are thick and strong, and the spinal 
 foramen large, but smaller than that of the atlas. The transverse processes are very 
 small, not bifid, and each is perforated by the foramen for the vertebral artery, 
 which is directed obli(|uely upward and outward. The superior articular surfaces 
 {fades articulares swperiores) are round, slightly convex, directed upward and 
 outward, and are peculiar in being supported on the body, pedicles, and trans- 
 verse processes. The inferior 
 articular surfaces (fades articu- 
 lares inferiores) have the same 
 direction as those of the other 
 cervical vertebra\ The superior 
 intervertebral notches are very 
 shallow, and lie behind the artic- 
 ular processes ; the inferior in 
 front of them, as in the other 
 cervical vertebriie. The spinous 
 process is of large size, very 
 strong, deeply channelled on its 
 under surface, and presents a 
 bifid, tubercular extremity for 
 the attachment of muscles which 
 serve to rotate the head upon 
 the spine. 
 
 Seventh Cervical (Fig. 18).— 
 The most distinctive character 
 of this vertebra is the existence 
 of a very long and prominent 
 spinous process; hence the name vertebra prominens. This process is thick, nearly 
 horizontal in direction, not bifurcated, and has attached to it the lower end of the 
 ligamentum nuchse. The transverse process is usually of large size, its posterior 
 tubercles are large and prominent, while the anterior are small and faintly marked; 
 its upper surface has usually a hollow groove, and it seldom presents more than a 
 trace of bifurcation at its extremity. The foramen in the transverse process is 
 sometimes as large as in the other cervical vertebme, but is usually smaller on one 
 or both sides, and is sometimes wanting. On the left side it occasionally gives 
 passage to the vertebral artery; more frequently the vertebral vein traverses it on 
 both sides; but the usual arrangement is for both artery and vein to pass in front 
 of the transverse process, and not through the foramen. Occasionally the anterior 
 root of the transverse process exists as a separate bone, and attains a large size. 
 It is then known as a cervical rib. 
 
 Spinous process. 
 Fig. 18. — Seventh cervical vertebra, or vertebra prominens. 
 
 The Thoracic or Dorsal Vertebrae (Vertebrae Thoracales). 
 
 The dorsal vertebrae are intermediate in size between those in the cervical and 
 those in the lumbar region, and increase in size from above downward, the upper 
 vertebrre in this segment of the spine being much smaller than those in the 
 lower part of the region. The dorsal vertebrre may be at once recognized by the 
 presence on the sides of the body of one or more facets or half-facets for the heads 
 of the ribs. 
 
 Bodies. — The bodies of the dorsal vertebrae resemble those in the cervical and 
 lumbar regions at the respective ends of this portion of the spine; but in the middle 
 of the dorsal region their form is very characteristic, being heart-shaped, and as 
 broad in the anteroposterior as in the lateral direction. They are thicker behind 
 than in front, flat above and below, convex and prominent in front, deeply con- 
 
54 THE SKELETON 
 
 cave behind, slightly constricted in front and at the sides, and marked on each 
 side, near the root of the pedicle, by two demi-facets, one above, the other below 
 {fovea costalis superior et inferior). These are covered with cartilage in the recent 
 state, and, when articulated with the adjoining vertebrae, form, with the inter- 
 vening fibro-cartilage, oval surfaces for the reception of the heads of the corre- 
 sponding ribs. The tenth, eleventh, and twelfth dorsal vertebrse each possesses 
 one complete facet for the head of the rib, instead of two demi-facets. 
 
 Superior articular process.- ._^_-»™v r^ • /. 
 
 ' "^"^^ Demi-facet for head of no. 
 
 Facet for tubercle of rib 
 
 Demi-facet for head of Hb. 
 Inferior articular process. 
 
 Fig. 19.— a dorsal vertebra. 
 
 Pedicles. — The pedicles are directed backward, and the inferior intervertebral 
 notches are of large size, and deeper than in any other region of the spine. 
 
 Laminae. — ^The laminae are broad, thick, and imbricated — that is to say, over- 
 lapping one another like tiles on a roof. The spinal foramen is small, and of a 
 circular form. 
 
 Processes. Spinous Processes. — Each spinous process is long, triangular on 
 transverse section, directed obliquely downward, and terminates in a tubercular 
 extremity. They overlap one another from the fifth to the eighth vertebra, but 
 are less oblique in direction above and below. 
 
 Articular Processes. — The articular processes are flat, nearly vertical in 
 direction, and project from the upper and lower part of the pedicles; the 
 superior being directed backward and slightly outward and upward, the inferior 
 forward and a little inward and downward. 
 
 Transverse Processes. — The transverse processes arise from the same parts 
 of the arch as the posterior roots of the transverse processes in the neck, and 
 are situated behind the articular processes and pedicles; they are thick, strong, 
 and of great length, directed obliquely backward and outward, presenting a 
 clubbed extremity, which is tipped on its anterior part by a small concave surface, 
 for articulation with the tubercle of a rib {fovea costalis transversalis) . The 
 twelfth, the eleventh, and sometimes the tenth dorsal vertebra has no facet on 
 the transverse process. Besides the articular facet for the rib, three indistinct 
 tubercles may be seen arising from the transverse processes: one at the upper 
 border, one at the lower border, and one externally. In man they are compara- 
 tively of small size, and serve only for the attachment of muscles. But in some 
 animals they attain considerable magnitude, either for the purpose of more closely 
 
THE THORACIC OB DORSAL VERTEBRA 
 
 55 
 
 connecting the segments of this portion of the spine or for muscular and liga- 
 mentous attachment. 
 
 The peculiar dorsal vertebrje are the first, ninth, tenth, eleventh, and twelfth 
 (Fig. 20). 
 
 f An entire facet above; 
 \ a demi-facet below. 
 
 '—A demi-facet above. 
 
 — One entire facet. 
 
 2/1 ( An entire facet. 
 
 II I No facet on transverse 
 process, which is ru- 
 dimentary. 
 
 An entire facet. 
 
 Ko facet on trans- 
 verse process. 
 I Inferior articular 
 process, convex 
 and turned out- 
 ward. 
 
 Fig. 20. — Peculiar dorsal vertebrae. 
 
 First Dorsal Vertebra. — The first dorsal vertebra presents, on each side of 
 the body, a single entire articular facet for the head of the first rib and a half 
 facet for the upper half of the second. The body is like that of a cervical vertebra, 
 being broad transversely its upper surface is concave, and lipped on each side. 
 The articular surfaces are oblique, and the spinous process thick, long, and almost 
 horizontal. 
 
 Ninth Dorsal Vertebra.— The ninth dorsal has no demi-facet below. In some 
 subjects, however, the ninth has two demi-facets on each side; when this occurs 
 the tenth has only a demi-facet at the upper part. 
 
56 THE SKELETON 
 
 Tenth Dorsal Vertebra. — The tenth dorsal has (except in the cases just men- 
 tioned) an entire articular facet on each side, above, which is partly placed on 
 the outer surface of the pedicle. It has no demi-facet below. 
 
 Eleventh Dorsal Vertebra. — In the eleventh dorsal the body approaches in its 
 form and size to the lumbar. The articular facets for the heads of the ribs, one 
 on each side, are of large size, and placed chiefly on the pedicles, which are 
 thicker and stronger in this and the next vertebra than in any other part of the 
 dorsal region. The spinous process is short, and nearly horizontal in direction. 
 The transverse processes are very short, tubercular at their extremities, and have 
 no articular facets for the tubercles of the ribs. 
 
 Twelfth Dorsal Vertebra. — The twelfth dorsal has the same general characters 
 as the eleventh, but may be distinguished from it by the inferior articular processes, 
 being convex and turned outward, like those of the lumbar vertebrae; by the 
 general form of the body, laminae, and spinous process, approaching to that of 
 the lumbar vertebrae; and by the transverse processes being shorter, and marked 
 by three elevations, the superior, inferior, and external tubercles, which corre- 
 spond to the mammillary, accessory, and transverse processes of the lumbar ver- 
 tebrae. Traces of similar elevations are usually to be found upon the other dorsal 
 vertebrae {vide ut supra). 
 
 The Lumbar Vertebrae (Vertebrae Lumbales). 
 
 The lumbar vertebrae (Fig. 21) are the largest segments of the vertebral 
 column, and can at once be distinguished by the absence of the foramen in 
 the transverse process, the characteristic point of the cervical vertebrae, and by 
 the absence of any articulating facet on the side of the body, the distinguishing 
 mark of the dorsal vertebrae. 
 
 Superior articular process. 
 
 Fig. 21. — Lumbar vertebra. 
 
 Body. — The body is large, and has a greater diameter from side to side than 
 from before backward, slightly thicker in front than behind, flattened or slightly 
 concave above and below, concave behind, and deeply constricted in front and at 
 the sides, presenting prominent margins, which afford a broad basis for the sup- 
 port of the superincumbent weight. 
 
 Pedicles. — The pedicles are very strong, directed backward from the upper 
 part of the bodies; consequently, the inferior intervertebral notches are of con- 
 siderable depth. 
 
 Laminae. — The laminae are broad, short, and strong, and the spinal fora- 
 men triangular, larger than in the dorsal, smaller than in the cervical, region. 
 
THE LUMBAR VERTEBRA 
 
 57 
 
 Processes. Spinous Processes. — The spinous processes are thick and broad, 
 somewhat quadrilateral, horizontal in direction, thicker below than above, and 
 terminating by a rough, uneven border. 
 
 Articular Processes. — The superior articular processes are concave, and look 
 backward and inward; the inferior are convex, and look forward and outward; 
 the former are separated by a much wider interval than the latter, embracing 
 the lower articulating processes of the vertebra above. 
 
 Transverse Processes. — The transverse processes are long, slender, directed 
 transversely outward in the upper three lumbar vertebrae, slanting a little upward 
 in the lower two. They are situated in front of the articular processes, instead 
 of behind them, as in the dorsal vertebme, and are homologous with the ribs. Of 
 the three tubercles noticed in connection with the transverse processes of the 
 twelfth dorsal vertebra, the superior one on each side becomes connected in this 
 region with the back part of the superior articular process, and has received the 
 
 Inf. articular process. 
 
 Mammillary process. 
 Accessory process. 
 
 Sup. articular process. 
 
 Fig. 22. — Lumbar vertebra. 
 
 name of mammillary process {jyrocessus mammillaris) ; the inferior is represented 
 by a small process pointing downward, situated at the back part of the base of 
 the transverse process, and called the accessory process {processus accessorius): 
 these are the true transverse processes, v/hich are rudimental in this region of 
 the spine. The external one is the so-called transverse process, the homologue 
 of the rib, and hence sometimes called the costal process {processus costarius) 
 (Fig. 22). Although in man the costal processes are comparatively small, in some 
 animals they attain considerable size, and serve to lock the vertebrae more 
 closely together. 
 
 Fifth Lumbar Vertebra. — The fifth lumbar vertebra is characterized by having 
 the body much thicker in front than behind, which accords with the prominence 
 of the sacro-vertebral articulation; by the smaller size of its spinous process; by 
 the wide interval between the inferior articulating processes; and by the greater 
 size and thickness of its transverse processes, which spring from the body as well 
 as from the pedicles. 
 
58 
 
 THE SKELETON 
 
 Structure of the Vertebrae. — The body is composed of light, spongy, cancel- 
 lous tissue, having a thin coating of compact tissue on its external surface per- 
 forated by numerous orifices, some of large size, for the passage of vessels; its 
 interior is traversed by one or two large canals, for the reception of veins, which 
 converge toward a single large, irregular aperture or several small apertures at the 
 posterior part of the body of each bone. The arch and processes projecting from 
 it have, on the contrary, an exceedingly thick covering of compact tissue (Fig. 23). 
 
 Fig 23. — Bony structure of a lumbar vertebra. (Poirier and Charpy.) 
 
 Development. — Each vertebra is formed of four primary centres of ossification 
 (Fig. 24), one for each lamina and its processes, and two for the body.^ Ossifica- 
 tion commences in the laminae about the sixth week of foetal life, in the situation 
 where the transverse processes afterward project, the ossific granules shooting 
 backward to the spine, forward into the pedicles, and outward into the transverse 
 and articular processes. Ossification in the body commences in the middle of 
 the cartilage about the eighth week by two closely approximated centres, which 
 
 By Jf primary centres. 
 
 ^^ [Sfor body (8th week). 
 
 By 4 secondary centres. 
 
 Ifor each lamina (6th week). 
 Fig. 24. — Development of a vertebra. 
 
 By 2 additional plates. 
 
 T^Igt b -1 for upper surface 
 aw of body, 
 
 ^1 for under surface 
 
 of body. 
 Fig. 25. 
 
 • f i years. 
 
 1 for each trans- 
 verse process, 
 16 years. 
 
 [sometimes 1) for spinous process (16 years). 
 Fig. 26. 
 
 speedily coalesce to form one central ossific point. According to some authors, 
 ossification commences in the laminae only in the upper vertebrae — i. e., in the 
 cervical and upper dorsal. The first ossific points in the lower vertebrae are those 
 which are to form the body, the osseous centres for the laminte appearing at a 
 subsequent period. At birth these three pieces are perfectly separate. During 
 the first year the laminae become united behind, the union taking place first in 
 the lumbar region and then extending upward through the dorsal and lower cer- 
 vical regions. About the third year the body is joined to the arch on each side in 
 such a manner that the body is formed from the three original centres of ossifica- 
 
 1 By many observers it is asserted that the bodies of the vertebra are developed from a single centre which 
 speedily becomes bilobed, so as to give the appearance of two nuclei; but that there are two centres, at all 
 events sometimes, is evidenced by the fact that the two halves of the body of the vertebra may remain distinct 
 throughout life and be separated by a fissure through which a protrusion of the spinal menibrane may take 
 place, constituting an anterior spina bifida. 
 
THE LUMBAR VERTEBRjE 
 
 59 
 
 By S centres. 
 
 tion, the amount contributed by the pedicles increasing in extent from below 
 upward. Thus the bodies of the sacral vertebrse are formed almost entirely from 
 the central nuclei; the bodies of the lumbar are formed laterally and behind by the 
 pedicles; in the dorsal region the pedicles advance as far forward as the articular 
 depressions for the head of the ribs, forming these cavities of reception; and in 
 the neck the lateral portions of the bodies are formed entirely by the advance of 
 the pedicles. The line along which union takes place between the body and the 
 neural arch is named neuro -central suture. Before puberty no other changes occur, 
 excepting a gradual increase in the growth of these primary centres; the upper 
 and under surfaces of the bodies and the ends of the transverse and spinous pro- 
 cesses being tipped with cartilage, in which ossific granules are not as yet deposited. 
 At sixteen years (Fig. 26) three secondary centres appear, one for the tip of 
 each transverse process, and one for the extremity of the spinous process. In 
 some of the lumbar vertebra, especially the first, second, and third, a second 
 ossifying centre appears at the base of the spinous process. At twenty-one years 
 (Fig. 25) a thin, circular, epiphysial plate of bone is formed in the layer of cartilage 
 situated on the upper and under surfaces of the body, the former being the thicker 
 of the two. All these become joined, and the bone is completely formed between 
 the twenty-fifth and thirtieth year of life. 
 
 Exceptions to this mode of development occur in the first, second, and seventh 
 cervical, and in the vertebra? of the lumbar region. 
 
 Atlas (Fig. 27). — The number of centres of ossification of the atlas is very vari- 
 able. It may be developed from two, three, four, or five centres. The most 
 frequent arrangement is by three 
 centres. Two of these are destined 
 for the two lateral or neural masses, 
 the ossification of which commences 
 about the seventh week near the 
 articular processes, and extend 
 backward; these portions of bone 
 are separated from one another be- 
 hind, at birth, by a narrow interval 
 filled in with cartilage. Between 
 the third and fourth years they unite 
 either directly or through the me- 
 dium of a separate centre developed 
 in the cartilage in the middle line. 
 The anterior arch, at birth, is al- 
 together cartilaginous, and in this 
 a separate nucleus appears about 
 the end of the first year after birth, 
 and, extending laterally, joins the 
 neural processes in front of the pedi- 
 cles. Sometimes there are two nu- 
 clei developed in the cartilage, one 
 on either side of the median line, 
 which join to form a single mass. 
 And occasionally there is no sepa- 
 rate centre, but the anterior arch is formed by the gradual extension forward 
 and ultimate junction of the two neural processes. 
 
 Axis. — The axis (Fig. 28) is developed by seven centres. The body and arch 
 of this bone are formed in the same manner as the corresponding parts in the other 
 vertebrje: one centre (or two, which speedily coalesce) for the lower part of the 
 body, and one for each lamina. The centres for the laminae appear about the 
 
 anterior arch {1st year), 
 
 not constant. 
 1 for each 
 lateral mass 
 
 I befori 
 
 e birth. 
 
 Fig. 27.— Atlas. 
 
 By 7 centres. 
 
 2d year. 
 
 6th month. 
 
 1 for each lateral mass. 
 
 1 for body (4th month). 
 1 for under surface of 
 body. 
 
 Pig. 28.— Axis. 
 S additional centres. 
 
 for tubercles on superior artictdar process. 
 Fig. 29. — Lumbar vertebra. 
 
60 THE SKELETON 
 
 seventh or eighth week, that for the body about the fourth month. The odontoid 
 process consists originally of an extension upward of the cartilaginous mass in 
 which the lower part of the body is formed. At about the sixth month of foetal 
 life two osseous nuclei make their appearance in the base of this process; they 
 are placed laterally, and join before birth to form a conical bilobed mass deeply 
 cleft above; the interval between the cleft and the summit of the process is formed 
 by a wedge-shaped piece of cartilage, the base of the process being separated 
 from the body by a cartilaginous interval, which gradually becomes ossified at 
 its circumference, but remains cartilaginous in its centre until advanced age.^ 
 Finally, as Humphry has demonstrated, the apex of the odontoid process has 
 a separate nucleus, which appears in the second year and joins about the twelfth 
 year. . In addition to these there is a secondary centre for a thin epiphysial plate 
 on the under surface of the body of the bone. J. Bland Sutton and others main- 
 tain that the odontoid process is the "dissociated body of the atlas."^ 
 
 Seventh Cervical. — The anterior or costal part of the transverse process of the 
 seventh cervical is developed from a separate osseous centre at about the sixth 
 month of foetal life, and joins the body and posterior division of the transverse 
 process between the fifth and sixth years. Sometimes this process continues as 
 a separate piece, and, becoming lengthened outward, constitutes what is known 
 as a cervical rib. This separate ossific centre for the costal process has also been 
 found in the fourth, fifth, and sixth cervical vertebrae. 
 
 Lumbal Vertebrae. — The lumbar vertebrae (Fig. 29) have two additional centres 
 (besides those peculiar to the vertebrae generally) for the mammillary tubercles, 
 which project from the back part of the superior articular processes. The trans- 
 verse process of the first lumbar is sometimes developed as a separate piece, which 
 may remain permanently unconnected with the remaining portion of the bone, 
 thus forming a lumbar rib — a peculiarity that is rarely met with. 
 
 Progress of Ossification in the Spine Generally. — Ossification of the laminae of 
 the vertebrae commences in the cervical region of the spine, and proceeds gradually 
 downward. Ossification of the bodies, on the other hand, commences a little 
 below the centre of the spinal column (about the ninth or tenth dorsal vertebra), 
 and extends both upward and downward. Although the ossific nuclei make their 
 first appearance in the lower dorsal vertebrae, the lumbar and first sacral ver- 
 tebrae are those in which these nuclei are largest at birth. 
 
 Attachment of Muscles. — To the Atlas are attached nine pairs: the Longus 
 colli, Rectus capitis anticus minor. Rectus lateralis, Obliquus capitis superior and 
 inferior, Splenius colli, Ivcvator anguli scapuUe, First Intertransverse, and Rectus 
 capitis posticus minor. 
 
 To the Axis are attached eleven pairs: the Longus colli, I>evator anguli scapulae, 
 Splenius colli. Scalenus medius, Transversalis colli, Intertransversales, Obliquus 
 capitis inferior. Rectus capitis posticus major, Semispinalis colli, Multifidus spinae, 
 Interspinales. 
 
 To the remaining vertebrae, generally, are attached thirty-five pairs and a 
 single muscle: anteriorly, the Rectus capitis anticus major, Longus colli. Scalenus 
 anticus medius and posticus, Psoas magnus and parvus, Quadratus lumborum. 
 Diaphragm, Obliquus abdominis internus, and Transversalis abdominis; pos- 
 teriorly, the Trapezius, Latissimus dorsi. Levator anguli scapulae, Rhomboideus 
 major and minor, Serratus posticus superior and inferior, Splenius, Erector spinae, 
 Ilio-costalis, I>,ongissimus dorsi. Spinalis dorsi, Cervicalis ascendens, Transversalis 
 colli, Trachelo-mastoid, Complexus, Biventer cervicis, Semispinalis dorsi and colli, 
 Multifidus spinae, Rotatores spinae, Interspinales, Supraspinales, Intertransversales, 
 Levatores costarum. 
 
 ^ See Cunningham, Jour. Anat., vol. xx. p. 238. ^ Ligaments: their Nature and Morphology. 
 
THE SACRAL AND COCCYGEAL VERTEBBjE 
 
 61 
 
 The Sacral and Coccygeal Vertebrae (False or Immovable Vertebrae). 
 
 The sacral and coccygeal vertebrae consist, at an early period of life, of nine 
 separate pieces, which are united in the adult so as to form two bones, five enter- 
 ing into the formation of the sacrum, four into that of the coccyx. Occasionally, 
 the coccyx consists of five bones.^ 
 
 Sacrum {os sacrum). — The os sacrum (sacer, sacred), the sacred bone. 
 So called, according to some, because it was the part selected in sacrifices. 
 Another view is that the name is derived from an opinion of the Jewish rabbis, 
 that this part of the skeleton strongly resists decay and becomes the germ from 
 which the new body will be raised. The sacrum is a large, triangular bone (Fig. 
 30), situated at the lower part of the vertebral column, and at the upper and 
 back part of the pelvic cavity, where it is inserted like a wedge between the two 
 innominate bones; its upper part or base articulating with the last lumbar ver- 
 tebra, its apex with the coccyx. It is composed of five segments of bone (sacral 
 vertebrae, or vertebrw sacrales). The sacrum is curved upon itself, and placed 
 very obliquely, its upper extremity projecting forward, and forming, with the 
 last lumbar vertebra, a very prominent angle, called the promontory (promontorium) , 
 or sacro -vertebral angle; while its central part is directed backward, so as to give 
 increased capacity to the pelvic cavity. It presents for examination an anterior and 
 posterior surface, two lateral surfaces, a base, an apex, and a central canal. 
 
 Fig. 30. — Sacrum, anterior surface. 
 
 Surfaces. Anterior or Pelvic Surface (fades pelvina). — The anterior surface 
 is concave from above downward, and slightly so from side to side. In the 
 middle are seen four transverse ridges (linear transversoB) , indicating the original 
 division of the bone into five separate pieces. The portions of bone intervening 
 
 ' Sir George Humphry describes this as the usual composition of the coccyx. On the Skeleton, p. 456. 
 
62 
 
 THE SKELETON 
 
 between the ridges correspond to the bodies of the vertebrae. The body of the first 
 segment is of large size, and in forra resembles that of a lumbar vertebra; the suc- 
 ceeding ones diminish in size from above downward, are flattened from before 
 backward, and curved so as to accommodate themselves to the form of the sacrum, 
 being concave in front, convex behind. At each end of the ridges above men- 
 tioned are seen the anterior sacral foramina (foramina sacralia anteriora) , analogous 
 to the intervertebral foramina, four in number on each side, somewhat rounded 
 in form, diminishing in size from above downward, and directed outward and 
 forward; they transmit the anterior branches of the sacral nerves and the lateral 
 sacral arteries. External to these foramina is the lateral mass {'pars lateralis), 
 consisting at an early period of life of separate segments; these become blended, 
 
 in the adult, with the bodies, with each 
 other, and with the posterior transverse 
 processes. Each lateral mass is traversed 
 by four broad, shallow grooves, which 
 lodge the anterior sacral nerves as they 
 pass outward, the grooves being sepa- 
 rated by prominent ridges of bone, which 
 give attachment to the slips of the 
 Pyriformis muscle. 
 
 If a vertical section is made through 
 the centre of the sacrum (Fig. 31), the 
 bodies are seen to be united at their cir- 
 cumference by bone, a wide interval being 
 left centrally, which, in the recent state, 
 is filled by intervertebral substance. In 
 some bones this union is more complete 
 between the lower segments than between 
 the upper ones. 
 
 Posterior or Dorsal Sm:face {fades dor- 
 salis) . — The posterior surface (Fig. 32) is 
 convex and much narrower than the ante- 
 rior. In the middle line are three or four 
 tubercles, which represent the rudimen- 
 tary spinous processes of the sacral verte- 
 brae. Of these tubercles, the first is 
 usually prominent, and perfectly distinct 
 from the rest; the second and third are 
 either separate or united into a tubercular 
 ridge {crista sacralis media), which dimin- 
 ishes in size from above downward; the 
 fourth usually, and the fifth always, 
 remaining undeveloped. The gap which results from failure of the lamina? to 
 meet in the mid-line is called the hiatus sacralis. External to the spinous pro- 
 cesses on each side are the laminae, broad and well marked in the first three 
 pieces; sometimes the fourth, and generally the fifth, are only partially developed 
 and fail to meet in the middle line. These partially developed laminae are prolonged 
 downward as rounded processes, the sacral comua (cornua sacralia) , and are con- 
 nected to the cornua of the coccyx. Between them the bony wall of the lower end 
 of the sacral canal is imperfect. External to the laminae is a linear series of 
 indistinct tubercles representing the articular processes {cristoe sacrales articulares) ; 
 the upper pair are large, well developed, and correspond in shape and direction 
 to the superior articulating processes of a lumbar vertebra; the second and third 
 are small; the fourth and fifth (usually blended together) are situated on each 
 
 Fig. 31. — Vertical section of the sacrum. 
 
THE SACRAL AND COCCYGEAL VERTEBRA 
 
 63 
 
 side of the sacral canal and assist in forming the sacral cornua. External to the 
 articular processes are the four posterior sacral foramina {foramina sacralia pos- 
 ter iora); they are smaller in size and less regular in form than the anterior, 
 and transmit the posterior branches of the sacral nerves. On the outer side of 
 
 Erector spinae. 
 
 Latissimus dorai. 
 
 Erector spinse. 
 
 Upper half of fifth 
 erior sacral foramen. 
 
 Fig. 32. — Sacrum, posterior surface. 
 
 the posterior sacral foramina is a series of tubercles, the rudimentary transverse 
 processes of the sacral vertebrae (cristcB sacrales laterales) . The first pair of trans- 
 verse tubercles are large, very distinct, and correspond with each superior angle of 
 the bone; they together with the second pair, which are of small size, give attach- 
 ment to the horizontal part of the sacro-iliac ligament ; the third gives attachment 
 to the oblique fasciculi of the posterior sacro-iliac ligaments ; and the fourth 
 and fifth to the great sacro-sciatic ligaments. The interspace between the spinous 
 and transverse processes on the back of the sacrum presents a wide, shallow 
 concavity, called the sacral groove: it is continuous above with the vertebral 
 groove, and lodges the origin of the Multifidus spinjie. 
 
 Lateral Surface. — The lateral surface, broad above, becomes narrowed into a 
 thin edge below. Its upper half presents in front a broad, ear-shaped surface for 
 articulation with the ilium. This is called the auricular surface (fades auricularis) , 
 and in the fresh state is coated with fibro-cartilage. It is bounded posteriorly by 
 deep and uneven impressions, for the attachment of the posterior sacro-iliac liga- 
 ments. The chief prominence is called the tuberosity (tuberositas sacralis). The 
 lower half is thin and sharp, and terminates in a projection called the inferior lateral 
 angle; below this angle is a notch, which is converted into a foramen by articula- 
 tion with the transverse process of the upper piece of the coccyx, and transmits 
 the anterior division of the fifth sacral nerve. This lower, sharp border gives 
 attachment to the greater and lesser sacro-sciatic ligaments, and to some fibres 
 of the Gluteus maximus posteriorly, and to the Coccygeus in front. 
 
 y 
 
64 THE SKELETON 
 
 Base (basis oss. sacri) . — The base of the sacrum, which is broad and expanded, is 
 directed upward and forward. In the middle is seen a large oval articular surface, 
 which is connected with the under surface of the body of the last lumbar vertebra 
 by a fibro-cartilaginous disk. It is bounded behind by the large, triangular orifice 
 of the sacral canal. The orifice is formed behind by the lamina? and spinous process 
 of the first sacral vertebra: the superior articular processes project from it on each 
 side; they are oval, concave, directed backward and inward, like the superior 
 articular processes of a lumbar vertebra; and in front of each articular process is 
 an intervertebral notch, which forms the lower part of the foramen between the 
 last lumbar and first sacral vertebra. Lastly, on each side of the large oval articular 
 plate is a broad and flat triangular surface of bone, which extends outward, 
 supports the Psoas magnus muscle and lumbo-sacral cord, and is continuous 
 on each side with the iliac fossa. This is called the ala of the sacrum (ala 
 sacralis) , and gives attachment to a few of the fibres of the Iliacus muscle. The 
 posterior part of the ala represents the transverse process of the first sacral 
 segment. 
 
 Apex {a'pex OSS. sacri). — The apex, directed downward and slightly forward, 
 presents a small, oval, concave surface for articulation with the coccyx. 
 
 Spinal Canal. — The spinal canal in this region is called the sacral canal (canalis 
 sacralis). It runs throughout the greater part of the bone; it is large and tri- 
 angular in form above, small and flattened, from before backward, below. In 
 this situation its posterior wall is incomplete, from the non-development of the 
 lamince and spinous processes (hiatus sacralis). It lodges the sacral nerves, 
 and is perforated by the anterior and posterior sacral foramina, through which 
 these pass out. 
 
 Structure. — It consists of much loose, spongy tissue within, invested externally 
 by a thin layer of compact tissue. 
 
 Differences in the Sacrum of the Male and Female. — The sacrum in the 
 female is shorter and wider than in the male; the lower half forms a greater 
 angle with the upper, the upper half of the bone being nearly straight, the lower 
 half presenting the greatest amount of curvature. The bone is also directed more 
 obliquely backward, which increases the size of the pelvic cavity; but the sacro- 
 vertebral angle projects less. In the male the curvature is more evenly dis- 
 tributed over the whole length of the bone, and is altogether greater than in 
 the female. 
 
 Peculiarities of the Sacrum. — This bone, in some cases, consists of six pieces; 
 occasionally, the number is reduced to four. Sometimes the bodies of the first 
 and second segments are not joined or the laminae and spinous processes have not 
 coalesced. Occasionally, the upper pair of transverse tubercles are not joined to 
 the rest of the bone on one or both sides ; and, lastly, the sacral canal may be open 
 for nearly the lower half of the bone, in consequence of the imperfect development 
 of the laminte and spinous processes. The sacrum, also, varies considerably with 
 respect to its degree of curvature. From the examination of a large number of 
 skeletons it would appear that in one set of cases the anterior surface of this bone 
 was nearly straight, the curvature, which was very slight, affecting only its lower 
 end. In another set of cases the bone was curved throughout its whole length, 
 but especially toward its middle. In a third set the degree of curvature was less 
 marked, and affected especially the lower third of the bone. 
 
 Development (Fig. 33). — The sacrum, formed by the union of five vertebrae, 
 has thirty-five centres of ossification. 
 
 The bodies of the sacral vertebrae have each three ossific centres: one for the 
 central part, and one for the epiphysial plates on its upper and under surface. 
 Occasionally the primary centres for the bodies of the first and second piece of the 
 sacrum are double. 
 
SACBAL AND COCCYGEAL VERTEBRA 
 
 65 
 
 The arch of each sacral vertebra is developed by two centres, one for each 
 lamina. These unite with each other behind, and subsequently join the body. 
 
 The lateral masses have six additional centres, two for each of the first three 
 vertebrse. These centres make their appearance above and to the outer side of 
 the anterior sacral foramina (Fig. 33), and are developed into separate segments 
 (Fig. 34); they are subsequently blended with each other, and with the bodies 
 and transverse processes to form the lateral mass. 
 
 Lastly, each lateral surface of the sacrum is developed by two epiphysial plates 
 (Fig. 35): one for the auricular surface, and one for the remaining part of the 
 thin lateral edge of the bone. 
 
 Additional centres 
 for the first three pieces. 
 
 At birth. 
 
 At4i 
 
 Two epiphysial laminx 
 for each lateral surface.'^ 
 
 At 
 S5th year. 
 
 Fig. 33. — Development of the sacrum. 
 
 Fig. 34. 
 
 Fig. 35. 
 
 Period of Development. — At about the eighth or ninth week of foetal life ossifi- 
 cation of the central part of the bodies of the first three vertebrae commences, 
 and at a somewhat later period that of the last two. Between the sixth and 
 eighth months ossification of the laminae takes place; and at about the same 
 period the centres for the lateral masses for the first three sacral vertebrae make 
 their appearance. The period at which the arch becomes completed by the junc- 
 tion of the laminae with the bodies in front and with each other behind varies in 
 different segments. The junction between the laminae and the bodies takes place 
 first in the lower vertebrae as early as the second year, but is not affected in the 
 uppermost until the fifth or sixth year. About the sixteenth year the epiphyses 
 for the upper and under surfaces of the bodies are formed, and between the eigh- 
 teenth and twentieth years those for each lateral surface of the sacrum make their 
 appearance. The bodies of the sacral vertebrae are, during early life, separated 
 from each other by intervertebral disks. But about the eighteenth year the two 
 lowest segments become joined together by ossification extending through the 
 disk. This process gradually extends upward until all the segments become 
 united, and the bone is completely formed from the twenty-fifth to the thirtieth 
 year of life. 
 
 Articulations. — With four bones: the last lumbar vertebra, coccyx, and the 
 two innominate bones. 
 
 Attachment of Muscles. — To eight pairs: in front, the Pyriformis and Coc- 
 cygeus, and a portion of the Iliacus to the base of the bone; behind, the Gluteus 
 maximus, Latissimus dorsi, Multifidus spinae, and Erector spinae, and sometimes 
 the Extensor coccygis. 
 
 Coccyx (os coccygis). — The coccyx [xoxxuq, cuckoo), so called from having 
 been compared to a cuckoo's beak (Fig. 36), is usually formed of four small 
 segments of bone, the most rudimentary parts of the vertebral column (vertebrae 
 coccygeae or caudate vertebrae). In each of the first three segments may be traced 
 a rudimentary body, articular and transverse processes; the last piece (some- 
 
 5 
 
66 
 
 THE SKELETON 
 
 times the third) is a mere nodule of bone, without distinct processes. All the 
 segments are destitute of pedicles, laminte, and spinous processes, and, conse- 
 quently, of intervertebral foramina and spinal canal. The first segment is the 
 largest; it resembles the lowermost sacral vertebra, and often exists as a separate 
 
 Cornua. 
 
 Anterior surface. 
 
 '*ct'eR 
 
 Posterior surface. 
 
 Pig. 36. — Coccyx. 
 
 piece; the last three, diminishing in size from above downward, are usually 
 blended together so as to form a single bone. The gradual diminution in the size 
 of the pieces gives this bone a triangular form, the base of the triangle joining 
 the end of the sacrum. It presents for examination an anterior and posterior sur- 
 face, two borders, a base, and an apex. 
 
 Surfaces. Anterior Surface. — The anterior surface is slightly concave, and 
 marked with three transverse grooves, indicating the points of junction of the 
 different pieces. It has attached to it the anterior sacro-coccygeal ligament and 
 Levator ani muscle, and supports the lower end of the rectum. 
 
 Posterior Surface. — The posterior surface is convex, marked by transverse grooves 
 similar to those on the anterior surface; and presents on each side a lineal row 
 of tubercles, the rudimentary articular processes of the coccygeal vertebrae. Of 
 these, the superior pair are large, and are called the cornua of the coccyx (cornua 
 coccygea) ; they project upward, and articulate with the cornua of the sacrum, the 
 junction between these two bones completing the fifth posterior sacral foramen for 
 the transmission of the posterior division of the fifth sacral nerve. 
 
 Borders. — The lateral borders are thin, and present a series of small eminences, 
 which represent the transverse processes of the coccygeal vertebr*. Of these, 
 the first on each side is the largest, flattened from before backward, and often 
 ascends to join the lower part of the thin lateral edge of the sacrum, thus com- 
 pleting the fifth anterior sacral foramen for the transmission of the anterior 
 division of the fifth sacral nerve; the others diminish in size from above down- 
 ward, and are often wanting. The borders of the coccyx are narrow, and give 
 attachment on each side to the sacro-sciatic ligaments, to the Coccygeus muscles 
 in front of the ligaments, and to the Gluteus maximus behind them. 
 
 Base. — The base presents an oval surface for articulation with the sacrum. 
 This articulation is known as the sacro-coccygeal symphysis (symphysis sacro- 
 coccygea) . 
 
 Apex. — The apex is rounded, and has attached to it the tendon of the external 
 Sphincter muscle. It is occasionally bifid, and sometimes deflected to one or 
 other side. 
 
 Development. — The coccyx is developed by four centres, one for each piece. 
 Occasionally one of the first three pieces of this bone is developed by two centres, 
 placed side by side. The ossific nuclei make their appearance in the following 
 order: in the first segment, shortly after birth; in the second piece, at from five 
 
THE VERTEBRAL COLUMN 
 
 67 
 
 to ten years; in the third, from ten to fifteen 
 years; in the fourth, from fifteen to twenty 
 years. As age advances these various seg- 
 ments become united with each other from 
 below upward, the union between the first 
 and second segments being frequently delayed 
 until after the age of twenty-five or thirty. 
 At a late period of life, especially in females, 
 the coccyx often becomes joined to the end 
 of the sacrum. 
 
 Articulation. — AYith the sacrum. 
 
 Attachment of Muscles. — To four pairs 
 and one single muscle : on either side, the 
 Coccygeus ; behind, the Gluteus maximus 
 and Extensor coccygis, when present ; at the 
 apex, the Sphincter ani ; and in front, the 
 Levator ani. 
 
 The Vertebral Colunm or Spine in General. 
 
 "^llie spinal column (columna vertehralis) , 
 formed by the junction of the vertebrae, is 
 situated in the median line, at the posterior 
 part of the trunk; its average length is about 
 two feet two or three inches, measuring along 
 the curved anterior surface of the column. 
 Of this length the cervical part measures 
 about five, the dorsal about eleven, the lum- 
 bar about seven inches, and the sacrum and 
 coccyx the remainder. The female spine is 
 about one inch less than that of the male. 
 
 Viewed in front, the ventral surface presents 
 two pyramids joined together at their bases, 
 the upper one being formed by all the verte- 
 bra from the second cervical to the last lum- 
 bar, the lower one by the sacrum and coccyx. 
 AVhen examined more closely, the upper 
 pyramid is seen to be formed of three smaller 
 pyramids. The uppermost of these consists 
 of the six lower cervical vertebrae, its apex 
 being formed by the axis or second cervical, 
 its base by the first dorsal. The second 
 pyramid, which is inverted, is formed by the 
 four upper dorsal vertebrae, the base being at 
 the first dorsal, the smaller end at the fourth. 
 The third pyramid commences at the fourth 
 dorsal, and gradually increases in size to the 
 fifth lumbar. 
 
 Viewed laterally (Fig. 37), the spinal column 
 presents several curves which correspond to 
 the different regions of the column, and are 
 called cervical, dorsal, lumbar, and pelvic. 
 The cervical curve commences at the apex of 
 the odontoid process, and terminates at the 
 
 1st cervical 
 or Atlas. 
 
 1st lumbar 
 
 Coccyx. 
 Fig. 37. — Lateral view of the spine. 
 
68 THE SKELETON 
 
 middle of the second dorsal vertebra ; it is convex in front, and is the least 
 marked of all the curves. The dorsal curve, which is concave forward, com- 
 mences at the middle of the second, and terminates at the middle of the twelfth 
 dorsal vertebra. Its most prominent point behind corresponds to the spine 
 of the seventh dorsal vertebra. The lumbar curve commences at the middle 
 of the last dorsal vertebra, and terminates at the sacro-vertebral angle. It is 
 convex anteriorly; the convexity of the lower three vertebrae being much greater 
 than that of the upper two. The pelvic curve commences at the sacro-verte- 
 bral articulation and terminates at the point of the coccyx. It is concave 
 anteriorly. The dorsal and pelvic curves are the primary qurves, and begin to 
 be formed at an early period of foetal life, and are due to the shape of the bodies 
 of the vertebrae. The cervical and lumbar curves are compensatory or secondary, 
 and are developed after birth in order to maintain the erect position. They are 
 due mainly to the shape of the intervertebral disks. 
 
 Some writers teach that the spine has a normal deviation to the right side. 
 Quain, Hyrtl, and others maintain this view. The curve is said to be in the 
 dorsal region. Bichat assigned muscular action as the chief cause of the curve. 
 Most persons use the right arm in preference to the left, especially in making 
 long-continued efforts, when the body is curved to the right side. In support 
 of this explanation is the observation made by Beclard that in some individuals 
 who were left-handed the lateral curvature was directed to the left side. Sappey 
 and others deny the existence of this curve. 
 
 The movable part of the spinal column presents for examination an anterior, 
 a posterior, and two lateral surfaces; a base, a summit, and the spinal canal. 
 
 Surfaces. Anterior Surface. — The anterior or ventral surface presents the bodies 
 of the vertebrae separated in the recent state by the intervertebral disks. The bodies 
 are broad in the cervical region, narrow in the upper part of the dorsal, and 
 broadest in the lumbar region. The whole of this surface is convex transversely, 
 concave from above downward in the dorsal region, and convex in the same 
 direction in the cervical and lumbar regions. 
 
 Posterior Surface. — The posterior or dorsal surface presents in the median line 
 the spinous processes. These are short, horizontal, with bifid extremities, in the 
 cervical region. In the dorsal region they are directed obliquely above, assume 
 almost a vertical direction in the middle, and are horizontal below, as are also 
 the spines of the lumbar vertebrae. They are separated by considerable intervals 
 in the loins, by narrower intervals in the neck, and are closely approximated in 
 the middle of the dorsal region. Occasionally one of these processes deviates a 
 little from the median line — a fact to be remembered in practice, as irregularities 
 of this sort are attendant also on fractures or displacements of the spine. On 
 either side of the spinous processes, extending the whole length of the column, 
 is the vertebral groove formed by the laminae in the cervical and lumbar regions, 
 where it is shallow, and by the laminae and transverse processes in the dorsal 
 region, where it is deep and broad. In the recent state these grooves lodge the 
 deep muscles of the back. External to each vertebral groove are the articular 
 processes, and still more externally is the transverse process. In the dorsal region 
 the latter processes stand backward, on a plane considerably posterior to the 
 same processes in the cervical and lumbar regions. In the cervical region the 
 transverse processes are placed in front of the articular processes, and on the 
 outer side of the pedicles, between the intervertebral foramina. In the dorsal 
 region they are posterior to the pedicles, intervertebral foramina, and articular 
 processes. In the lumbar region they are placed also in front of the articular 
 processes, but behind the intervertebral foramina. 
 
 Lateral Surfaces. — The lateral surfaces are separated from the posterior surface 
 by the articular processes in the cervical and lumbar regions, and by the trans- 
 
THE VERTEBRAL COLUMN 69 
 
 verse processes in the dorsal region. These surfaces present in front the sides of 
 the bodies of the vertebrie, marked in the dorsal region by the facets for articula- 
 tion with the heads of the ribs. I\Iore posteriorly are the intervertebral foramina, 
 formed by the juxtaposition of the intervertebral notches, oval in shape, smallest 
 in the cervical and upper part of the dorsal regions, and gradually increasing in 
 size to the last lumbar vertebra. They are situated between the transverse pro- 
 cesses in the neck, anfl in front of them in the back and loins, and transmit the 
 spinal nerves. 
 
 Base. — The base of that portion of the vertebral column formed by the twenty- 
 four movable vertebne is formed by the under surface of the body of the fifth 
 lumbar vertebra; and the summit by the upper surface of the atlas. 
 
 Spinal Canal {canalis vertehralis) . — The vertebral or spinal canal follows the 
 different curves of the spine; it is largest in those regions in which the. spine 
 enjoys the greatest freedom of movement, as in the neck and loins, where it is 
 wide and triangular; and is narrow and rounded in the back, where motion is 
 more limited. The centre of gravity of the spine is in the upper lumbar region, 
 slightly to the right of the median plane (Struthers). 
 
 Sm"face Form. — The only parts of the vertebral column which lie closely under the skin, and 
 so directly influence surface form, are the apices of the spinous processes. These are always distin- 
 guishable at the bottom of a median furrow, which, more or less evident, runs down the mesial 
 line of the back from the external occipital protuberance above to the middle of the sacrum below. 
 In the cervical region the furrow is between the Trapezii muscles ; in the back and loins it is between 
 the Erector spinae muscles. In the neck the furrow is broad, and terminates in a conspicuous 
 projection, which is caused by the spinous process of the seventh cervical vertebra (vertebra 
 prominens). Above this the spinous process of the sixth cervical vertebra may sometimes be 
 seen to form a projection; the other cervical spines are sunken, and are not visible, though the 
 spine of the axis can be felt, and generally also the spines of the third, fourth, and fifth cervical 
 vertebne. In the dorsal region the furrow is shallow, and during stooping disappears, and then 
 the spinous processes become more or less visible. The markings produced by these spines are 
 small and close together. In the lumbar region the furrow is deep, and the situation of the lumbar 
 spines is frequently indicated by Httle pits or depressions, especially if the muscles in the loins 
 are well developed and the spine incurved. They are much larger and farther apart than in the 
 dorsal region. In the sacral region the furrow is shallower, presenting a flattened area which 
 terminates below at the most prominent part of the posterior surface of the sacrum, formed by 
 the spinous process of the third sacral vertebra. At the bottom of the furrow may be felt the 
 irregular posterior surface of the bone. Below this, in the deep groove leading to the anus, the 
 coccyx may be felt. The only other portions of the vertebral column which can be felt from the 
 surface are the transverse processes of three of the cervical vertebrae — viz., the first, the sixth, 
 and the seventh. The transverse process of the atlas can be felt as a rounded nodule of bone 
 just below and in front of the apex of the mastoid process, along the anterior border of the sterno- 
 mastoid. The transverse process of the sixth cervical vertebra is of surgical importance. If 
 deep pressure be made in the neck in the course of the carotid artery, opposite the cricoid carti- 
 lage, the prominent anterior tubercle of the transverse process of the sixth cervical vertebra can 
 be felt. This has been named Chassaignac's tubercle, and against it the carotid artery may be 
 most conveniently compressed by the finger. The transverse process of the seventh cervical 
 vertebra can also often be felt. Occasionally the anterior root, or costal process, is large and 
 .segmented ofi', forming a cervical rib. 
 
 Surgical Anatomy. — It is frequently necessary to locate certain vertebrae. Several of them 
 can be easily found and identified. The seventh cervical spine is conspicuously prominent, and 
 when the skin above it has been marked with a blue pencil the spine of the sixth cervical above 
 and of the first dorsal below may be located. The spine of the third dorsal vertebra is on a level 
 with the root of the spine of the scapula. The spine of the fourth lumbar vertebra is on a level 
 with the highest point of the iliac crest. When one or two vertebrae have been definitely recog- 
 nized the other ones can be found by counting the spines from a fixed point or from fixed points. 
 Over the fifth lumbar spine there is no prominence, but a depression. The third sacral spine 
 is on a level with the posterior superior spines of the ilium. The level at which the spinal cord 
 terminates should be known to the surgeon if he proposes to tap the dural sac {lumbar pmicture), 
 for diagnostic or therapeutic purposes or as a preliminary to the injection of cocaine oreucaine 
 (spinal anaesthesia). In an adult the cord terminates at the lower border of the first lumbar 
 vertebra, and the dural sac terminates opposite the body of the third sacral vertebra. In a child 
 the cprd terminates opposite the body of the third lumbar vertebra, and the dural sac ends at 
 
70 THE SKELETON 
 
 about the same level as in an adult. Hence, in either a child or an adult, a puncture below the 
 level of the fourth lumbar vertebra will inflict no injury upon the cord. In children the puncture 
 is made just beneath the vertebral spine, and in adults about one-half an inch to either side of 
 the vertebral spine, although, even in adults, the needle is made to enter the dura in the middle 
 line. In either case the needle is directed upward and forward. As previously pointed out, the 
 surgical anatomy of an infant's spine is not identical with the surgical anatomy of an adult's 
 spine. An infant's spine is larger comparatively than an adult's spine, because the lower limbs 
 are less developed in the former (A. H. Tubby). The umbilicus of an infant is opposite the body 
 of the fourth lumbar vertebra; in an adult it is opposite the spine of the third lumbar vertebra. 
 In an infant the base of the sternum is on a level with the top of the seventh cervical spine, and 
 in an adult of the second dorsal spine (A. H. Tubby). 
 
 Occasionally the coalescence of the laminae is not completed, and consequently a cleft is left 
 in the arches of the vertebrae, through which a protrusion of the spinal membranes (dura mater 
 and arachnoid), and sometimes of the spinal cord itself, takes place, constituting a malformation 
 known as s-pina bifida or hydrorrhachitis. This disease is most common in the lumbosacral 
 region; but it may occur in the dorsal or cervical region, or the arches throughout the whole 
 length of the canal may remain unapproximated. In some rare cases, in consequence of the 
 non-coalescence of the two primary centres from which the body is formed, a similar condition 
 may occur in front of the canal, the bodies of the vertebrae being found cleft and the tumor pro- 
 jecting into the thorax, abdomen, or pelvis, between the lateral halves of the bodies affected. 
 
 The construction of the spinal column of a number of pieces, securely connected together 
 and enjoying only a slight degree of movement between any two individual pieces, though per- 
 mitting of a very considerable range of movement as a whole, allows a sufficient degree of 
 mobility without any material diminution of strength. The main joints of which the spine is 
 composed, together with the very varied movements to which it is subjected, render it liable to 
 strains, which may complicate other injuries or may exist alone; but so closely are the individual 
 vertebrae articulated that these sprains are seldom severe, and an amount of violence sufficiently 
 great to produce tearing of the ligaments would tend to cause a dislocation or fracture. The 
 further safety of the column and its less liability to injury is provided for by its disposition 
 in curves instead of in one straight line. For it is an elastic column, and must first bend before 
 it breaks: under these circumstances, being made up of three curves, it represents three columns, 
 and greater force is required to produce bending of a short column than of a longer one that is 
 equal to it in breadth and material. Again, the safety of the column is provided for by the inter- 
 position of the intervertebral disks between the bodies of the vertebrae, which act as admirable 
 buffers in counteracting the effects of violent jars or shocks. Fracture dislocation of the spine 
 may be caused by direct or indirect violence, or by a combination of the two, as when a person, 
 falling from a height, strikes against some prominence and is doubled over it. The fractures 
 from indirect violence are the more common, and here the bodies of the vertebrae are compressed, 
 whilst the arches are torn asunder; whilst in fractures from direct violence the arches are com- 
 pressed and the bodies of the vertebrae separated from each other. It will therefore be seen that 
 in both classes of injury the spinal marrow is the part least likely to be injured, and may escape 
 damage even where there has been considerable lesion of the bony framework. For, as Mr. 
 Jacobson states, "being lodged in the centre of the column, it occupies neutral ground in respect 
 to forces which might cause fracture. For it is a law in mechanics that when a beam, as of timber, 
 is exposed to breakage and the force does not exceed the limits of the strength of the material, 
 one division resists compression, another laceration of the particles, while the third, between 
 the two, is in a negative condition."^ Applying this principle to the spine it will be seen that, 
 v^hether the fracture dislocation be produced by direct violence or by indirect force, one segment, 
 either the anterior or posterior, will be exposed to compression, the other to laceration, and the 
 intermediate part, where the cord is situated, will be in a neutral state. When a fracture dis- 
 location is produced by indirect violence the displacement is almost always the same, the upper 
 segment being driven for\vard on the lower, so that the cord is compressed between the body of 
 the vertebra below and the arch of the vertebra above. 
 
 The parts of the spine most liable to be injured are (1) the dorso-lumbar region, for this part 
 is near the middle of the column, and there is therefore a greater amount of leverage, and more- 
 over the portion above is comparatively fixed, and the vertebrae which form it, though much 
 smaller, have nevertheless to bear almost as great a weight as those below; (2) the cervico-dorsal 
 region, because here the flexible cervical portion of the spine joins the more fixed dorsal region; 
 and (3) the atlanto-axial region, because it enjoys an extensive range of movement, and, being 
 near the skull, is influenced by violence applied to the head. In fracture dislocation spinous 
 processes and portions of the laminae may be removed {laminectomy) in order to free the cord 
 from pressure, and to permit the surgeon to explore, to arrest hemorrhage, to remove bone 
 fragments, or to apply sutures. Laminectomy is also resorted to in some cases of paraplegia due 
 to Pott's disease of the spine. 
 
 1 Holmes's System of Surgery, vol. i. p. 529, 1883. 
 
THE OCCIPITAL BONE 
 
 71 
 
 THE SKULL. 
 
 The skeleton of the head is called the skull. The cranium is the skull without 
 the mandible. The calvaria or cerebral cranium is the skull without the bones of 
 the face. The skull is supported on the summit of the vertebral column, and is 
 of an oval shape, wider behind than in front. It is composed of a series of flat- 
 tened or irregularly shaped bones which, with one exception (the lower jaw), are 
 immovably joined together. It is divided into two parts, the cerebral cranium or 
 calvaria an^l the visceral cranium or face, the former of which constitutes a case 
 for the accommodation and protection of the brain, while opening on the face 
 are the orifices of the nose and mouth; between the cerebral cranium above and 
 the face below the orbital cavities are situated. The cerebral cranium (xpduo^, a 
 helmet) is composed of eight bones — viz., the occipital, two parietal, frontal, two 
 temporal, sphenoid, and ethmoid. The face is composed of fourteen bones — 
 viz., the two nasal, two superior maxillary, two lachrymal, two malar, two palate, 
 two inferior turbinated, vomer, and inferior maxillary or mandible. The ossiculi 
 auditus, the teeth, and Wormian bones are not included in this enumeration. 
 
 Occipital. 
 Two Parietal. 
 
 ''Cranium, 8 bones . i m m i 
 
 iwo lemporal. 
 
 I Sphenoid. 
 
 L Ethmoid. 
 
 Two Nasal. 
 
 Two Superior Maxillary. 
 
 Two Lachrymal. 
 
 Two Malar. 
 } Two Palate. 
 
 Two Inferior Turbinated. 
 
 Vomer. 
 L Inferior Maxillary or Mandible. 
 
 The Hyoid Bone, situated at the root of the tongue and attached to the base 
 of the skull by ligaments, has also to be considered in this section. 
 
 Skull, 22 bones' 
 
 Face, 14 bones 
 
 THE CEREBRAL CRANIUM (CRANIUM CEREBRALE) (THE CALVARIA). 
 
 The Occipital Bone (Os Occipitale). 
 
 The occipital bone (ob, caput, against the head) is situated at the back part 
 and base of the cranium, is trapezoid in shape and is much curved on itself (Fig. 
 38). It presents at its front and lower part a large oval aperture, the foramen 
 magnum (foramen occipitale magnum) , by which the cranial cavity communicates 
 with the spinal canal. The portion of bone behind this opening is flat and 
 expanded and forms the tabula, tabular portion, or squamous part {squama 
 occipitalis) ; the portion in front is a thick, el ngated mass of bone, the basilar 
 process (pars basilaris) ; while on each side of the foramen is situated a lateral 
 or condylic portion {pars lateralis), bearing the condyle, by which the bone articu- 
 lates with the atlas. The bone presents for examination two surfaces, four borders, 
 and four angles. 
 
 Surfaces. External Surface. — The external surface is convex. Midway between 
 the summit of the bone and the posterior margin of the foramen magnum is a 
 prominent tubercle, the inion or external occipital protuberance {protuberantia 
 
72 
 
 THE SKELETON 
 
 occipitalis externa, and, descending from it as far as the foramen, a vertical 
 rido-e, the external occipital crest {crista occipitalis externa). This protuberance 
 and crest give attachment to the hgamentum nuchre, and vary in prominence 
 in different skulls. Passing outward from the occipital protuberance is a semi- 
 circular ridge on each side, the superior curved or superior nuchal line (linea 
 nuchas superior). Above this line there is often a second less distinctly 
 marked ridge, called the highest curved line (linea nuchce suprema) ; to it the epi- 
 cranial aponeurosis is attached. The bone between these two lines is smoother 
 and denser than the rest of the surface. Running parallel with these from the 
 middle of the crest is another semicircular ridge on each side, the inferior curved 
 or inferior nuchal line (linea nuchce inferior). The surface of the bone above the 
 linea suprema is rough and porous, and in the recent state is covered by the 
 
 lAnea 
 suprema 
 
 SUPERIOR 
 CONSTRICTOR 
 
 of Pharynx. 
 
 IfusvlctT Jrrcic. 
 Fig. 38. — Occipital bone. Outer surface. 
 
 Occipito-frontalis muscle. It is called the occipital portion or the planum 
 occipitale. The superior and inferior curved lines, together with the surfaces of 
 bone between and below them, serve for the attachment of several muscles. 
 The superior curved line gives attachment internally to the Trapezius, externally 
 to the muscular origin of the Occipito-frontalis, and to the Sterno-cleido-mastoid 
 to the extent shown in Fig. 38; the depressions between the curved lines to the 
 Complexus internally, the Splenius capitis and Obliquus capitis superior exter- 
 nally. The inferior curved line and the depressions below it afford insertion to 
 the Rectus capitis posticus, major and minor. The portion of the tabula below 
 the superior curved line is called the nuchal plane (planum nuchale) , and it gives 
 attachment to certain of the neck muscles. 
 
 The foramen magnum (foramen occipitale magnum) is a large, oval aperture, its 
 long diameter extending from before backward. It transmits the lower portion 
 
THE OCCIPITAL BONE 73 
 
 of the medulla oblongata and its membranes, the spinal accessory nerves, the 
 vertebral arteries, the anterior and posterior spinal arteries, and the occipito- 
 axial ligaments. Its back part is wide for the transmission of the medulla, and 
 the corresponding margin rough for the attachment of the dura mater enclosing 
 it; the fore part is narrower, being encroached upon by the condyles; it has pro- 
 jecting toward it, from below, the odontoid process, and its margins are smooth 
 and bevelled internally to support the medulla oblongata. The middle of the 
 anterior wall of the foramen magnum is called by Broca the basion. The lateral 
 or condylic portions {partes laterales) are on either side of the foramen magnum 
 and bear the condyles for articulation with the atlas. Each condyle (condylus 
 occipitalis) is convex, oval, or reniform in shape, and directed downward and 
 outward. The condyles converge in front, and encroach slightly upon the anterior 
 segment of the foramen. On the inner border of each condyle is a rough tubercle 
 for the attachment of the ligaments (check) which connect this bone with the 
 odontoid process of the axis; while external to them is a rough tubercular promi- 
 nence, the transverse or jugular process (processus jugularis), channelled in front 
 by a deep notch (incisura jugularis), which forms part of the jugular foramen 
 or foramen laceruin posterius. The under surface of this process presents an 
 eminence (processus intrajugularis) which represents the paramastoid process of 
 some mammals. The eminence is occasionally large, and extends as low as the 
 transverse process of the atlas. This surface affords attachment to the Rectus 
 capitis lateralis muscle and to the lateral occipito-atlantal ligament; its upper or 
 cerebral surface presents a deep groove which lodges part of the lateral sinus, 
 while its external surface is marked by a quadrilateral rough facet, covered with 
 cartilage in the fresh state, and articulating with a similar surface on the petrous 
 portion of the temporal bone. On the outer side of each condyle, near its fore 
 part, is a foramen, the anterior condyloid foramen (canalis hypoglossi or the hypo- 
 glossal canal) ; it is directed downward, outward, and forward, and transmits the 
 hypoglossal nerve, and occasionally a meningeal branch of the ascending pharyn- 
 geal artery. This foramen is sometimes double. Behind each condyle is a 
 fossa^ (fossa condyloideus) , sometimes perforated at the bottom by a foramen, 
 the posterior condyloid foramen (canalis condyloideus), for the transmission of a 
 vein to the lateral sinus. The basilar process (pars hasilaris) is a strong quadri- 
 lateral plate of bone, which is wider behind than in front, and is situated in front 
 of the foramen magnum. Its under surface, which is rough, presents in the 
 median line a tubercular ridge, the pharjmgeal spine or tubercle (tuherculum 
 pharyngeum) , for the attachment of the tendinous raph^ and Superior con- 
 strictor of the pharynx; and on each side of it rough depressions for the attach- 
 ment of the Rectus capitis anticus, major and minor. 
 
 Internal Surface. — The internal or cerebral surface (Fig. 39) is deeply concave. 
 The posterior or tabular part is divided by a crucial ridge into four fossa?. The 
 two superior fossse receive the occipital lobes of the cerebrum, and present slight 
 eminences and depressions corresponding to their convolutions. The two inferior, 
 which receive the hemispheres of the cerebellum, are larger than the former, and 
 comparatively smooth; l)oth are marked by slight grooves for the lodgement of 
 arteries. At the point of meeting of the four divisions of the crucial ridge is an 
 eminence, the internal occipital protuberance (protuherantia occipitalis interna). It 
 nearly corresponds to that on the outer surface, though it is often on a slightly 
 higher level, and is perforated by one or more large vascular foramina. From 
 this eminence the superior division of the crucial ridge runs upward to the supe- 
 rior angle of the bone; it presents a deep groove, the sagittal sulcus (sulcus sagii- 
 
 * This fossa presents many variations in size. It is usually shallow, and the foramen small; occasionally 
 wanting on one or both sides. Sometimes both fossa and foramen are large, but confined to one side only; 
 more rarely, the fossa and foramen are very large on both sides. 
 
74 
 
 THE SKELETON 
 
 talis), for the superior longitudinal sinus. The margins of the groove give attach- 
 ment to the falx cerebri. The inferior division, the internal occipital crest {crista 
 occipitalis interna), runs to the posterior margin of the foramen magnum, on the 
 edge of which it becomes gradually lost; this ridge, which is bifurcated below, serves 
 
 Superior angle. 
 
 Inferior angle. 
 Fig. 39. — Occipital bone. Inner surface. 
 
 for the attachment of the falx cerebelli. It is usually marked by a single groove, 
 which commences at the back part of the foramen magnum and lodges the occip- 
 ital sinus. Occasionally the groove is double where two sinuses exist. A 
 transverse groove (sulcus transversus) passes outward on each side to the lateral 
 angle. The grooves are deep channels for the lodgement of the lateral sinuses, their 
 prominent margins affording attachment to the tentorium cerebelli.^ At the point 
 of meeting of these grooves is a depression, the torcular Herophili,^ placed a little 
 to one or the other side of the internal occipital protuberance. ]More anteriorly 
 is the foramen magnum, and on each side of it, but nearer its anterior than its 
 posterior part, the internal openings of the anterior condyloid foramen. On the 
 superior aspect of the lateral portion of the bone the jugular tubercle (tuherculum 
 jugulare) is seen. This corresponds to the portion of bone which roofs in the 
 anterior condyloid foramen. The internal openings of the posterior condyloid 
 
 1 Usually one of the transverse grooves is deeper and broader than the other; occasionally, both grooves are 
 of equal depth and breadth, or both equally indistinct. The broader of the two transverse grooves is nearly 
 always continuous with the vertical groove for the superior longitudinal sinus. 
 
 - The columns of blood coming in different directions were supposed to be pressed together at this point 
 (torcular, a wine-press). 
 
THE OCCIPITAL BONE 75 
 
 foramina are a little external alid posterior to the openings of the anterior con- 
 dyloid foramina, protected by a small arch of bone. At this part of the internal 
 surface there is a very deep groove in which the posterior condyloid foramen, 
 when it exists, has its termination. This groove is continuous, in the complete 
 skull, with the transverse groove on the posterior part of the bone, and lodges 
 the end of the same sinus, the lateral. In front of the foramen magnum is the 
 basilar process, presenting a shallow depression, the basilar groove (clivus), which 
 slopes from behind, upward and forward, and supports the medulla oblongata 
 and part of the pons Varolii, and on each side of the basilar process is a narrow 
 channel, which, when united with a similar channel on the petrous portion of 
 the temporal bone, forms a groove (sulcus petrosus inferior) which lodges the 
 inferior petrosal sinus. 
 
 Borders. Superior Border. — The superior border, lambdoidal margin (mar go 
 lambdoideus) , extends on each side from the superior to the lateral angle, is 
 deeply serrated for articulation with the parietal bone, and forms, by this union, 
 the lambdoid suture. 
 
 Inferior Border. — The inferior border extends from the lateral to the inferior 
 angle; its upper half, mastoid margin (margo mastoideus) , is rough, and articu- 
 lates with the mastoid portion of the temporal, forming the masto -occipital suture ; 
 the inferior half articulates with the petrous portion of the temporal, forming 
 the petro-occipital suture; these two portions are separated from one another by 
 the jugular process. In front of this process is a deep notch, which, with a 
 similar one on the petrous portion of the temporal, forms the jugular foramen 
 (foramen lacerum posterius). This notch is occasionally subdivided into two 
 parts by a small process of bone (processus intrajugularis) , and it generally 
 presents an aperture at its upper part, the internal opening of the posterior 
 condyloid* foramen. 
 
 Angles. Superior Angle .^ — The superior angle is received into the interval 
 between the posterior superior angles of the two parietal bones; it corresponds 
 with that part of the skull in the foetus which is called the posterior fontanelle 
 (lambda). 
 
 Inferior Angle. — The inferior angle is represented by the square-shaped surface 
 of the basilar process. At an early period of life a layer of cartilage separates this 
 part of the bone from the sphenoid, 
 but in the adult the union between 
 them is osseous. 
 
 Lateral Angles. — The lateral an- 
 gles correspond to the outer ends of ^^^-l* ^^^B^/or ocdpitai 
 the transverse grooves, and are re- ^^^^%'7 ""^"^^^ portion. 
 ceived into the interval between the 
 posterior inferior angles of the pari- 
 etal and the mastoid portion of the ^^^'^^^JJ^^ 0^ ^m^^i for each condyloid . -^ 
 temporal. The junction of the oc- separate. \q\ )■ ^J portion. 
 cipital, parietal, and temporal bones 
 was named the asterion by Broca. ""g^ — —1 for basilar portimi. j 
 
 Structure. The occipital bone Fig. 40.— Development of occipital bone. By seven centres. 
 
 consists of two compact laminae, 
 
 called the outer and inner tables, having between them the diploic tissue; this bone 
 is especially thick at the ridges, protuberances, condyles, and anterior part of the 
 basilar process; while at the bottom of the fossae, especially the inferior, it is thin, 
 semitransparent, and destitute of diploe. 
 
 Development (Fig. 40). — At birth the bone consists of four distinct parts: a 
 tabular squamous or expanded pcrtion, which lies behind the foramen magnum ; two 
 condylic parts, which form the sides of the foramen; and a basilar part, which lies 
 
76 THE SKELETON 
 
 in front of the foramen. The number of nuclei for the tabular part vary. As 
 a rule, there are four, but there may be only one (Blandin) or as many as eight 
 (Meckel). They appear about the eighth week of foetal life, and soon unite to 
 form a single piece, which is, however, fissured in the direction indicated in 
 Fig. 40. The basilar and two condyloid portions are each developed from a single 
 nucleus, which appears a little later. The upper portion of the tabular surface 
 — that is to say, the portion above the transverse fissure — is developed from mem- 
 brane, and may remain separated from the rest of the bone throughout life, when 
 it constitutes the interparietal bone, which is called the os incae, because of its fre- 
 quent occurrence in Peruvian skulls. The rest of the bone is developed from 
 cartilage. At about the fourth year the tabular and the two condyloid pieces 
 join, and about the sixtii year the bone consists of a single piece. At a later period, 
 between the eighteenth and twenty-fifth years, the occipital and sphenoid become 
 united, forming a single bone. 
 
 Articulations. — With six bones: two parietal, two temporal, sphenoid, and atlas. 
 
 Attachment of Muscles. — To twelve pairs: to the superior curved line are 
 attached the Occipito-frontalis, Trapezius, and Sterno-cleido-mastoid. To the 
 space between the curved lines, the Complexus,^ Splenius capitis, and Obliquus 
 capitis superior; to the inferior curved line, and the space between it and the 
 foramen magnum, the Rectus capitis posticus, major and minor; to the transverse 
 process, the Rectus capitis lateralis; and to the basilar process, the Rectus capitis 
 anticus, major and minor, and Superior constrictor of the pharynx. 
 
 The Parietal Bone (Os Parietale). 
 
 The parietal bones (paries, a wall) are paired bones and form, by their union, the 
 sides and roof of the cerebral cranium. Each bone is of an irregular quadrilateral 
 form, and presents for examination two surfaces, four borders, and four angles. 
 
 Surfaces. External Surface (fades parietalis). — The external surface (Fig. 41) 
 is convex, smooth, and marked about its centre by an eminence called the 
 parietal eminence (tuber parietale), which indicates the point where ossification 
 commenced. Crossing the middle of the bone in an arched direction are two 
 well-marked curved lines or ridges, the upper and lower temporal lines or ridges 
 (linea temporalis superior et inferior); the former gives attachment to the tem- 
 poral fascia, while the latter indicates the upper limit of the origin of the 
 Temporal muscle. These lines form the temporal crest. Above these ridges 
 the surface of the bone is rough and porous, and covered by the aponeurosis 
 . of the Occipito-frontalis ; between them the bone is smoother and more polished 
 than the rest; below them the bone forms part of the temporal fossa. This 
 portion of bone is called the planum temporale, and affords attachment to the 
 Temporal muscle. The superior stephanion is the intersection of the upper 
 temporal ridge with the coronal suture. The inferior stephanion is the intersec- 
 tion of the lower temporal ridge with the coronal suture. At the back part of 
 the superior border, close to the sagittal suture, is a small foramen, the parietal 
 foramen (foramen parietale), which transmits the emissary vein of Santorini from 
 the scalp to the superior longitudinal sinus. It sometimes also transmits a 
 small branch of the occipital artery. Its existence is not constant, and its 
 size varies considerably. The point on the sagittal suture, between the parietal 
 foramina, is the obelion. 
 
 Internal or Cerebral Surface (fades cerebralis) . — The internal surface (Fig. 42) is 
 concave, presents depressions for lodging the convolutions of the cerebrum and 
 numerous furrows, for the ramifications of the middle meningeal artery; the 
 
 1 To these the Biventer cervicis should be added, if it is regarded as a separate muscle. 
 
THE PARIETAL BONE 
 
 77 
 
 Articulates 
 
 Posterior 
 
 superior 
 
 angle. 
 
 ';/;'l':'''i"'",.. ^Anterior 
 .,, ..■,... -,..., ■■'■' J sriperior 
 
 Posterior 
 
 inferior 
 
 angle. 
 
 FiQ. 42. — Left parietal bone. Internal surface. 
 
 i 
 
 -/ Anterior 
 inferior 
 angle. 
 
78 THE SKELETON 
 
 latter runs upward and backward from the anterior inferior angle and from the 
 central and posterior part of the lower border of the bone. The depression for 
 the middle meningeal artery at the anterior and inferior portions of the cerebral 
 surface of the bone is called the sulcus arteriosus. Sometimes a distinct canal 
 exists for the artery, but it never remains a canal for a long distance. Along 
 the upper margin of the bone is part of a shallow groove, which, when joined 
 to the opposite parietal, forms a channel for the superior longitudinal sinus (the 
 sulcus sagittalis). The elevated edges of the groove afford attachment to the 
 falx cerebri. Near the groove are seen several depressions, Pacchionian depressions 
 (foveoloe granulares [Pacchioni]). They are most frequently found in the skulls 
 of old persons, and lodge the Pacchionian bodies. The internal opening of the 
 parietal foramen is also seen when that aperture exists. On the inner surface of 
 the posterior inferior portion of the bone is a portion of the groove for the lodge- 
 ment of the lateral sinus (sulcus transversus). 
 
 Borders. Superior Border. — The superior border, sagittal margin (margo sagit- 
 talis), the longest and thickest, is dentated to articulate with its fellow of the 
 opposite side, forming the sagittal suture. 
 
 Inferior Border. — The inferior border, squamous margin (margo squamosus), is 
 divided into three parts: of these, the anterior is thin and pointed, bevelled at 
 the expense of the outer surface, and overlapped by the tip of the great wing 
 of the sphenoid; the middle portion is arched, bevelled at the expense of the 
 outer surface, and overlapped by the squamous portion of the temporal; the 
 posterior portion is thick and serrated for articulation with the mastoid portion 
 of the temporal. 
 
 Anterior Border. — The anterior border, frontal margin (margo frontalis), deeply 
 serrated, is bevelled at the expense of the outer surface above and of the inner 
 below; it articulates with the frontal bone, forming the coronal suture. 
 
 Posterior Border. — The posterior border, occipital margin (margo occipitalis), 
 deeply denticulated, articulates with the occipital, forming the lambdoid suture. 
 
 Angles. Anterior Superior Angle (angulus frontalis). — The anterior superior 
 or frontal angle, thin and pointed, corresponds with that portion of the skull 
 which in the foetus is membranous, and is called the anterior fontanelle (bregma). 
 
 Anterior Inferior Angle (angulus sphenoidalis) . — The anterior inferior or 
 sphenoidal angle is thin and lengthened, being received in the interval between 
 the great wing of the sphenoid and the frontal. Its inner surface is marked by a 
 deep groove, sometimes a canal, for the anterior branch of the middle meningeal 
 artery. At the anterior inferior angle the parietal, temporal, and frontal bones 
 and the greater wing of the sphenoid bone meet. This spot is called the 
 pterion. 
 
 Posterior Superior Angle (angulus occipitalis) . — The posterior superior or occip- 
 ital angle corresponds with the jimction of the sagittal and lambdoid sutures. In 
 the foetus this part of the skull is membranous, and is called the posterior fonta- 
 nelle (lambda). 
 
 Posterior Inferior Angle (angulus mastoideus. — The posterior inferior or mas- 
 toid angle articulates with the mastoid portion of the temporal bone, and 
 generally presents on its inner surface a broad, shallow groove for lodging part 
 of the lateral sinus. 
 
 Development. — The parietal bone is formed in membrane, being developed 
 by one centre, which corresponds with the parietal eminence, and makes its first 
 appearance about the seventh or eighth week of foetal life. Ossification gradually 
 extends from the centre to the circumference of the bone: the angles are conse- 
 quently the parts last formed, and it is in their situation that the fontanelles exist 
 previous to the completion of the growth of the bone. Occasionally the parietal 
 bone is divided into two parts, upper and lower, by an antero-posterior suture. 
 
THE FRONTAL BONE 
 
 79 
 
 Articulations. — ^Yith five bones: the opposite parietal, the occipital, frontal, 
 temporal, and sphenoid. 
 Attachment of Muscles. — One only, the Temporal. 
 
 The Frontal Bone (Os Frontale). 
 
 The frontal bone (frons, the forehead) resembles a cockle-shell in form, and 
 consists of two portions — a vertical or frontal portion, situated at the anterior 
 part of the cranium, forming the forehead; and a horizontal or orbital portion, 
 which enters into the formation of the roof of the orbits and nasal fossae. 
 
 Vertical Portion of the Frontal Bone (Pars Frontalis). 
 
 Surfaces. External Surface (fades frontalis) (Fig. 43). — In the median line, 
 traversing the bone from the upper to the lower part, is occasionally seen a 
 slightly elevated ridge, and in young subjects a suture, the frontal (metopic) 
 suture, which represents the line of union of the two lateral halves of which the 
 
 , ,„ - , External 
 
 m angtdar process. angular process. 
 
 Nasal i spine. 
 
 Fig. 43. — Frontal bone. Outer surface. 
 
 bone consists at an early period of life; in the adult this suture is usually oblit- 
 erated and the bone forms one piece; traces of the obliterated suture are, how- 
 ever, generally perceptible at the lower part. On either side of this ridge, a little 
 below the centre of the bone, is a rounded eminence, the frontal eminence (tuber 
 frontale). These eminences vary in size in different individuals, and are occa- 
 sionally unsymmetrical in the same subject. They are especially prominent in 
 cases of well-marked cerebral development. The whole surface of the bone 
 above this part is smooth, and covered by the aponeurosis of the Occipito- 
 frontalis muscle. Below the frontal eminence and separated from it by a slight 
 
go THE SKELETON 
 
 groove is the superciliary ridge (arcus swperciliaris) , broad internally, where it 
 is continuous with the nasal eminence, but less distinct as it arches outward. 
 These ridges are caused by the projection outward of the frontal air sinuses,^ 
 and give attachment to the Orbicularis palpebrarum and Corrugator supercilii. 
 Between the two superciliary ridges is a smooth, flat surface, the glabella. 
 Nearly corresponding with the glabella is the ophryon, a point in the mid-line 
 on a level with the upper border of the eyebrows, which is the centre of the 
 narrowest transverse diameter of the forehead. Beneath the superciliary ridge 
 is the orbital margin or supraorbital arch (margo supraorbitalis) , a curved and 
 prominent margin, which forms the upper boundary of the orbit and separates 
 the vertical from the horizontal portion of the bone. The outer part of the 
 arch is sharp and prominent, affording to the eye, in that situation, considerable 
 protection from injury; the inner part is less prominent. At the junction of the 
 internal and middle third of this arch is a notch, sometimes converted into a 
 foramen, and called the supraorbital notch or foramen (incisura supraorbitalis or 
 foramen supraorbitale) . It transmits the supraorbital artery, vein, and nerve. A 
 small aperture is seen in the upper part of the notch, which transmits a vein 
 from the diploe to join the supraorbital vein. To the median side of the 
 supraorbital notch there is often a notch (incisura frontalis) for the passage 
 of the frontal artery and frontal nerve. The supraorbital arch terminates 
 externally in the external angular process (processus zygomaticus) and internally 
 in the internal angular process. The external angular process is strong, prominent, 
 and articulates with the malar bone; running upward and backward from it are 
 two well-marked lines, which, commencing together from the external angular 
 process as the temporal ridge, crest or line (linea temporalis), soon diverge from 
 each other and run in a curved direction across the bone. These are the 
 upper and lower temporal ridges; the upper gives attachment to the temporal 
 fascia, the lower to the Temporal muscle. Beneath them is a slight concavity 
 that forms the anterior part of the temporal fossa and gives origin to the 
 Temporal muscle. The internal angular processes are less marked than the 
 external, and articulate with the lachrymal bones. Between the internal angular 
 processes is a rough, uneven interval, the nasal notch, which articulates in the 
 middle line with the nasal bone, and on either side with the nasal process of the 
 superior maxillary bone. From the concavity of this notch projects a process, 
 the nasal process, which extends beneath the nasal bones and nasal processes of 
 the superior maxillary bones and supports the bridge of the nose. On the under 
 surface of this is a long, pointed process, the nasal or frontal spine (spina nasalis 
 or frontalis), and on either side a small grooved surface enters into the formation 
 of the roof of the nasal fossa. The nasal spine forms part of the septum of the 
 nose, articulating in front with the nasal bones and behind with the perpen- 
 dicular plate of the ethmoid. The junction of the nasal and frontal bones is 
 called the nasion. 
 
 Internal Surface (cerebral surface, fades cerebralis) (Fig. 44). — Along the middle 
 line is a vertical groove, the sulcus sagittalis, the edges of which unite below to 
 form a ridge, the frontal crest (crista frontalis) ; the groove lodges the superior 
 longitudinal sinus, whilst its margins afford attachment to the falx cerebri. The 
 crest terminates below at a small notch which is converted into a foramen by 
 articulation with the ethmoid. It is called the foramen caecum, and varies in 
 size in different subjects: it is sometimes partially or completely impervious, 
 
 1 Some confusion is occasioned to students commencing the study of anatomy by the name " sinuses " having 
 been given to two perfectly different kinds of spaces connected with the skull. It may be as well, therefore, to 
 state here at the outset, that the " sinuses " in the interior of the cranium which produce the grooves on the 
 mner surface of the bones are venous channels along which the blood runs in its passage back from the brain, 
 wbile the "sinuses " external to the cranial cavity (the frontal sphenoidal, ethmoidal, and maxillary) are hollow 
 spaces m the bones themselves which communicate with the nostrils, and contain air. 
 
THE FRONTAL BONE 
 
 81 
 
 lodges a process of the falx cerebri, and when open transmits a vein from the 
 Hning membrane of the nose to the superior longitudinal sinus. On either 
 side of the groove the bone is deeply concave, presenting depressions for the 
 convolutions of the brain, and numerous small furrows for lodging the rami- 
 
 With superior maxillary! 
 
 With na^al' 
 
 I 
 With perpendicular plate of ethmoid. 
 
 Fig. 44. — Frontal bone. 
 
 Frontal sinus. 
 
 Under surface of nasal process, 
 forming part of roof of nose. 
 Inner surface. 
 
 fications of the anterior branches of the middle meningeal arteries. Several 
 small irregular fossie are seen also on either side of the groove, for the reception 
 of the Pacchionian bodies. 
 
 Border. — The border of the vertical portion is thick, strongly serrated, bevelled 
 at the expense of the internal table above, where it rests upon the parietal bones, 
 and at the expense of the external table at each side, where it receives the lateral 
 pressure of those bones; this border is continued below into a triangular rough 
 surface which articulates with the great wing of the sphenoid. 
 
 Structure. — The vertical portion and external angular processes are very thick, 
 consisting of diploic tissue contained between two compact laminae. 
 
 Horizontal or Orbital Portion of the Frontal Bone (Pars Orbitalis). 
 
 This portion of the bone consists of two thin plates, the orbital plates, which 
 form the vault of the orbit, separated from one another by a median gap, the 
 ethmoidal notch. 
 
 Surfaces. External Surface. — The inferior or external surface of each orbital 
 plate (fades orbitalis) consists of a smooth, concave, triangular lamina of bone, 
 marked at its anterior and external part (immediately beneath the external 
 angular process) by a shallow depression, the lachrymal fossa (fossa glandular 
 lacrimalis) for lodging the lachrymal gland; and at its anterior and internal part 
 
 6 
 
82 
 
 THE SKELETON 
 
 by a depression (sometimes a small tubercle), the trochlear fossa (fovea trochlearis) , 
 for the attachment of the cartilaginous pulley of the Superior oblique muscle of 
 the eye. The ethmoidal notch (incisura ethmoidalis) separates the two orbital 
 plates; it is quadrilateral, and filled up, when the bones are united, by the cribri- 
 form plate of the ethmoid. The margins of this notch present several half-cells, 
 which, when united with corresponding half-cells on the upper surface of the eth- 
 moid, complete the ethmoidal cells ; two grooves are also seen crossing these edges 
 transversely; they are converted into canals by articulation with the ethmoid, and 
 are called the anterior and posterior ethmoidal foramina or canals {foramen ethmoi- 
 dale anterius and foramen ethmoidale posterius) : they open on the inner wall of the 
 orbit. The anterior one transmits the nasal nerve and anterior ethmoidal vessels, 
 the posterior one the posterior ethmoidal vessels. In front of the ethmoidal 
 notch, on each side of the nasal spine, is the opening of the frontal air sinus (sinus 
 frontalis). These are two irregular cavities, which extend upward and outward, a 
 variable distance, between the two tables of the skull, and are separated from one 
 another by a thin, bony septum (septum sinuum frontalium) , which is often dis- 
 placed to one side. Within the sinuses imperfect trabeculffi of bone often exist. The 
 sinuses are beneath and give rise to the prominences above the supraorbital arches 
 called the superciliary ridges (arcus superciliares) . The frontal air sinuses are absent 
 at birth, become apparent about the seventh year of life, and from this period until 
 the age of twenty increase gradually in size. Sometimes, however, the sinuses 
 remain very small or never develop at all — or one side may be large and the other 
 small — or one may exist on one side and be absent on the other.^ The right sinus 
 is usually the larger. These cavities are larger in men than in women. The floor 
 of each sinus is very thin and is over the orbit and the upper border of the lateral 
 mass of the ethmoid. The thinnest portion of the floor is at the upper and 
 inner angle of the orbit, and at this point pus is apt to point in cases of 
 empyema of the sinus. The frontal sinuses are lined by mucous membrane 
 and each sinus communicates with the middle meatus of the nose by the infun- 
 dibulum and part of the semilunar hiatus. In some cases the sinuses commu- 
 nicate with each other by means of an aperture in the septum and occasionally 
 join the sinus in the crista galli of the ethmoid.^ 
 
 Internal Surface (cerebral surface, fades cerebralis). — The internal surface of 
 the horizontal portion presents the convex upper surfaces of the orbital plates, 
 
 separated from each other in the mid- 
 dle line by the ethmoidal notch, and 
 marked by eminences and depressions for 
 the convolutions of the frontal lobes of 
 the brain. 
 
 Border. — The border of the horizontal 
 portion is thin, serrated, and articulates 
 with the lesser wing of the sphenoid. 
 
 Structure. — The horizontal portion is 
 thin, translucent, and composed entirely 
 of compact tissue; hence the facility with 
 which instruments can penetrate the 
 cranium through this part of the orbit. 
 
 Development (Fig. 45).— The frontal 
 
 bone is formed in membrane, being 
 
 developed by two centres, one for each lateral half, which make their appearance 
 
 about the seventh or eighth week, above the orbital arches. From this point 
 
 ossification extends, in a radiating manner, upward into the forehead and back- 
 
 FiG. 45. — Frontal bone at birth. Developed by 
 two lateral halves. 
 
 ' Dr. D. Kerfoot Shute. Article on the Skull, in Reference Handbook of the Medical Sciences. 
 
 Ibid. 
 
THE TEMPORAL BONE 
 
 83 
 
 ward over the orbit. At birth the bone consists of two pieces, which afterward 
 become united, along the middle line, by a suture which runs from the vertex 
 to the root of the nose. This suture usually becomes obliterated within a few 
 years after birth; but it occasionally remains throughout life, constituting the 
 metopic suture. Secondary centres of ossification appear for the nasal spine — 
 one on either side of the internal angular process where it articulates with the 
 lachrymal bone; and sometimes there is one on either side at the lower end of 
 the coronal suture. This latter centre sometimes remains ununited, and is 
 known as the pterion ossicle, or it may join with the parietal, sphenoid, or tem- 
 poral bone. 
 
 Articulations. — With twelve bones: two parietal, the sphenoid, the ethmoid, 
 two nasal, two superior maxillary, two lachrymal, and two malar. 
 
 Attachment of Muscles. — To three pairs: the Corrugator supercilii, Orbicu- 
 laris palpebrarum, and Temporal, on each side. 
 
 The Temporal Bone (Os Temporale). 
 
 The temporal ones (tempus, time) are paired liones, situated at the sides and 
 base of the skull. Each presents for examination a squamous, mastoid, and petrous 
 portion. 
 
 Squamous Portion of the Temporal Bone (Squama Temporalis) . 
 
 The squamous portion (squama, a scale), the anterior and upper part of the 
 bone, is scale-like in form, and thin and translucent in texture (Fig. 46). 
 
 SQUAMOUS SUTURE 
 
 SULCUS ron middle 
 
 TEMPORAL ARTERY 
 
 REMAINS OF 
 SQUAMOSO- 
 MASTOID 
 
 X OF PETROUS 
 PORTION 
 
 MASTOID 
 FORAMEN 
 
 MASTOID 
 PORTION 
 
 EXTERNAL AUDITORY MEATUS TYMPANIC PORTION 
 
 Fig. 46. — Right temporal bone, from without. (Spaltebolz.) 
 
 Surfaces. Outer Surface (fades temporalis) . — Its outer surface is smooth, convex, 
 and grooved at its back part for the middle or deep temporal artery {sulcus a. 
 temporalis media'); it affords attachment to the Temporal muscle and forms part 
 of the temporal fossa. At its back part may be seen a curved ridge — part of the 
 temporal ridge or line; it serves for the attachment of the temporal fascia and 
 
84 THE SKELETON 
 
 limits the origin of the Temporal muscle. The boundary between the squamous 
 and mastoid portions of the bone, as indicated by traces of the original suture, 
 lies fully half an inch below this ridge. Projecting from the lower part of the 
 squamous portion is a long, arched process of bone, the zygoma or zygomatic 
 process (processus zygomaticus). This process is at first directed outward, its 
 two surfaces looking upward and downward; it then appears as if twisted 
 upon itself, and runs forward, its surfaces now looking inward and outward. 
 The superior border of the process is long, thin, and sharp, and serves for the 
 attachment of the temporal fascia. The inferior, short, thick, and arched, has 
 attached to it some fibres of the Masseter muscle. Its outer surface is convex 
 and subcutaneous; its inner is concave, and also affords attachment to the 
 Masseter. The extremity, broad and deeply serrated, articulates with the malar 
 bone. The zygomatic process is connected to the temporal bone by three divi- 
 sions, called its roots — an anterior, middle, and posterior. The anterior, which 
 is short, but broad and strong, is directed inward, to terminate in a rounded 
 eminence, the eminentia articularis or articular eminence (tuberculum articulare) 
 (Fig. 46). This eminence forms the front boundary of the glenoid or mandibular 
 fossa (fossa Tnandihularis), and in the recent state is covered with cartilage. 
 The middle root is known as the post-glenoid process or tubercle, and is very 
 prominent in young bones. It separates the mandibular portion of the glenoid 
 fossa from the external auditory meatus, and terminates at the commencement 
 of a well-marked fissure, the Glaserian (petro-tympanic) fissure (fissura petro- 
 tympanica [Glaseri]). The posterior root, which is strongly marked, runs from 
 the upper border of the zygoma backward over the external auditory meatus. 
 It is termed the supramastoid or temporal crest, and forms part of the lower 
 temporal ridge. At the junction of the anterior root with the zygoma is a 
 projection, called the tubercle, for the attachment of the external lateral liga- 
 ment of the lower jaw; and between the anterior and middle roots is an oval 
 depression, forming part of the glenoid (Tnandihular) fossa (ylrjvri, a socket), for 
 the reception of the condyle of the lower jaw. This fossa is bounded, in front, 
 by the eminentia articularis; behind, by the tympanic plate, which separates it 
 from the external auditory meatus; it is divided into two parts by a narrow slit, 
 the Glaserian or petro -tympanic fissure. The anterior or mandibular part, formed 
 by the squamous portion of the bone, is smooth, covered in the recent state with 
 cartilage, and articulates with the condyle of the lower jaw. This part of the 
 glenoid fossa presents posteriorly a small conical eminence, the post-glenoid 
 process, already referred to. This process is the representative of a prominent 
 tubercle which, in some of the mammalia, descends behind the condyle of the 
 jaw, and prevents it being displaced backward during mastication (Humphry). 
 The posterior part of the glenoid fossa, which lodges a portion of the parotid 
 gland, is formed chiefly by the tympanic plate, which constitutes the anterior 
 wall of the tympanum and external auditory meatus. The plate of bone termi- 
 nates above in the Glaserian fissure, and below forms a sharp edge, the vaginal 
 process of the styloid (vagina processus styloidei), which gives origin to some of 
 the fibres of the Tensor palati muscle. The Glaserian fissure, which leads into 
 the tympanum, lodges the processus gracilis of the malleus, and transmits the 
 tympanic branch of the internal maxillary artery. The chorda tympani nerve 
 passes through a separate canal, parallel to the Glaserian fissure, the canal of 
 Huguier (canaliculus chorda^ tympani), on the outer side of the Eustachian 
 tube, in the retiring angle between the squamous and petrous portions of the 
 temporal bone.^ Between the posterior bony wall of the external auditory meatus 
 
 ^ This small fissure must not be confounded with the large canal which lies above the Eustachian tube and 
 transmits the Tensor tympani muscle. 
 
THE TEMPORAL BONE 
 
 85 
 
 and the posterior root of the zygoma is the area called the suprameatal triangle of 
 Prof. Macewen. Through this space the surgeon pushes the gauge in order to 
 carry it into the antrum of the mastoid process. 
 
 Internal Surface (cerebral surface, fades cerebralis). — The internal surface of 
 the squamous portion (Fig. 47) is concave, presents numerous eminences and 
 depressions for the convolutions of the cerebrum, and two well-marked grooves 
 for the branches of the middle meningeal artery. 
 
 parietal 
 
 Aqiixductus vestibuli. 
 
 Depression for dura mater 
 
 Meatus auditorius internus. 
 
 Eminence for superior semicircular canal. 
 Hiatus Fallopii. 
 
 Opening for smaller petrosal nerve. 
 Depression for Gasserian Ganglion. 
 Bristle passed through carotid canal. 
 
 Fig. 47. — Left temporal bone. Inner surface. , 
 
 Borders. Superior Border. — The superior border, parietal margin (margo 
 parietalis), is thin, bevelled at the expense of the internal surface, so as to 
 overlap the lower border of the parietal bone, forming the squamous suture. 
 
 Anterior Inferior Border. — The anterior inferior border, sphenoidal margin (margo 
 sphenoidal is), is thick, serrated, and bevelled, alternately at the expense of the 
 inner and outer surfaces, for articulation with the great wing of the sphenoid. 
 
 Posterior Inferior Border. — The posterior inferior border, occipital margin 
 (margo occipitalis), is serrated and articulates with the occipital bone. 
 
 The Mastoid Portion of the Temporal Bone (Pars Mastoidea) . 
 
 The mastoid portion (/mazo^, a nipple or teat) is situated at the posterior part 
 of the bone (Figs. 46, 48, and 49). 
 
 Surfaces. Outer Surface. — The outer surface of the mastoid is rough, and 
 gives attachment to the Occipito-frontalis and Retrahens aurem muscles. It 
 is perforated by numerous foramina; one of these, of large size, situated at the 
 posterior border of the bone, is termed the mastoid foramen (foramen mastoideum) ; 
 it transmits a vein to the lateral sinus and a small artery from the occipital to 
 supply the dura mater. The position and size of this foramen are very variable. 
 It is not always present; sometimes it is situated in the occipital bone or in the 
 suture between the temporal and the occipital. The mastoid portion is con- 
 
86 
 
 THE SKELETON 
 
 tinned below into a conical projection, the mastoid process (processus mastoideus) , 
 the size and form of which vary somewhat. Tlie mastoitl process begins to 
 develop during the second year and does not attain full size until after puberty. 
 This process serves for the attachment of the Sterno-mastoid, Splenius capitis, 
 and Trachelo-mastoid muscles. On the inner side of the mastoid process is a 
 deep groove, the digastric fossa (incisura mastoidea), for the attachment of the 
 Digastric muscle; and, running parallel with it, but more internal, the occipital 
 groove (sidcus a. occipitalis), which lodges the occipital artery. The suprameatal 
 triangle of Prof. Macewen is bounded by the posterior root of the zygoma, the 
 posterior bony wall of the external auditory meatus, and an imaginary line join- 
 ing these two. Through this triangle the surgeon enters his instrument in order 
 to reach the mastoid antrum. Behind the suprameatal spine is a depression 
 known as the mastoid fossa [fossa mastoidea), which contains numerous small 
 openings for bloodvessels. 
 
 Tensor tympani. 
 Proc. cochleariformis. 
 
 Eustachian tube, 
 'arotid canal. 
 
 Carotid canw 
 Fenestra rotunda. 
 
 Pyramid, 
 
 Aqueductus Fallopii. 
 Marrow cells. 
 
 Fig. 48.- 
 
 -Section through the petrous and mastoid portions of the temporal bone, showing the communication 
 • of the cavity of the tympanum with the mastoid antrum. 
 
 Internal Surface. — The internal surface of the mastoid portion presents a deep, 
 curved groove, the sigmoid fossa or sulcus (sulcus sigmoideus) , which lodges part 
 of the lateral sinus; and into it may be seen opening the mastoid foramen, 
 which transmits an emissary vein from the lateral sinus to the posterior auricular 
 or occipital vein and a small artery, the mastoid branch of the occipital artery 
 (ramus mastoideus) . The groove for the lateral sinus is separated from the inner- 
 most of the mastoid air-cells by only a thin lamina of bone, and even this may be 
 partly deficient. A section of the mastoid process (Figs. 48 and 49) shows it to be 
 hollowed out into a number of cellular spaces, communicating with each other, 
 called the mastoid cells (cellules mastoidece), which exhibit the greatest possible 
 variety as to their size and number, and which do not exist at birth, but develop 
 with the growth of the mastoid process. At the upper and front part of the 
 bone these cells are large and irregular, and contain air. They diminish in size 
 toward the lower part of the bone, those situated at the apex of the mastoid 
 process being quite small and usually containing marrow. These pneumatic 
 cells extend far beyond the mastoid. Some may reach the floor of the Eustachian 
 
THE TEMPORAL BONE 
 
 87 
 
 canal; others the jugular portion of the occipital bone; others the roof of the 
 external auditory canal, and some pass up toward the squamous portion.^ Occa- 
 sionally they are entirely absent, and the mastoid is solid throughout. In addi- 
 tion to these pneumatic cells may be seen a large, irregular cavity (Figs. 48 and 
 49), situated at the upper and front part of the section. It is called the mastoid or 
 tympanic antrum (antrum tympanicum) , and must be distinguished from the mas- 
 toid cells, though it communicates with them. The mastoid cells are not developed 
 until after puberty, but the mastoid antrum is almost as large at birth as it is in 
 the adult. 
 
 It is filled with air, and is lined with a prolongation of the mucous membrane 
 of the tympanum, which extends into it through an opening, by which it com- 
 municates with the cavity of the tympanum. The mastoid antrum is bounded 
 above by a thin plate of bone, the tegmen tympani, which separates it from the 
 middle fossa of the base of the skull on the anterior surface of the petrous portion 
 
 PROMINENCE OVER 
 SEMICIRCULAR CANAL 
 
 FENESTRA OVALIS 
 OR VCSTIBULI 
 
 PROCESSUS 
 COCHLEARIFORMIS 
 
 AQUEDUCT of/ 
 
 FALLOPIUS 
 
 SEPTUM OF 
 EUSTACHIAN TUBE 
 
 PROBE IN 
 TYMPANIC 
 CANAL 
 
 Fig. 49. — Right temporal bone cut open. Lateral view of medial half of bone. X 2. (Spalteholz.) 
 
 of the temporal bone; below by the mastoid process; externally by the squamous 
 portion of the bone just below the supramastoid crest; and internally by the 
 external semicircular canal of the internal ear, which projects into its cavity. 
 The opening by which it communicates with the tympanum is situated at the 
 superior internal angle of the posterior wall of that cavity; it is a triangular 
 opening into that portion of the tympanic cavity which is known as the tympanic 
 attic or epitympanic recess or space (aditus ad antrum) — that is to say, that 
 portion of the tympanum which is above the level of the membrana tympani. 
 
 In consequence of the communication which exists between the tympanum and mastoid cells, 
 mflammation of the lining membrane of the former cavity may easily travel backward to that 
 of the antrum, leading to caries and necrosis of their walls and the risk of transference of the 
 inflammation to the lateral sinus or encephalon. 
 
 ' Dr. D. Kerfoot Shute, in Reference Handbook of the Medical Sciences.- 
 
88 THE SKELETON 
 
 Borders. Superior Border. — The superior border of the mastoid portion is 
 broad and rough, its serrated edge sloping outward, for articulation with the 
 posterior inferior angle of the parietal bone. 
 
 Posterior Border. — The posterior border, also, uneven and serrated, articu- 
 lates with the inferior border of the occipital bone between its lateral angle and 
 jugular process. 
 
 The Petrous Portion of the Temporal Bone (Pars Petrosa [Pyramis]) (Fig. 47). 
 
 The petrous portion (Trsrpo^, a stone), so named from its extreme density and 
 hardness, is a pyramidal process of bone wedged in at the base of the skull 
 between the sphenoid and occipital bones. Its direction from without is inward, 
 forward, and a little downward. It presents for examination a base, an apex, 
 three surfaces, and three borders, and contains, in its interior, the essential parts 
 of the organ of hearing. 
 
 Base. — The base is applied against the internal surface of the squamous and 
 mastoid portions, its upper half being concealed; but its lower half is exposed 
 by the divergence of those two portions of the bone, which brings into view the 
 oval, expanded orifice of a canal leading into the tympanum, the meatus audi- 
 torius externus {meatus acusticu^ externus). The curved tympanic plate or part 
 {fars tympanica) forms the anterior wall, the floor, and a part of the posterior 
 wall of this meatus, while the squamous portion of the temporal completes it 
 above and behind. The entrance to the meatus is bounded throughout the 
 greater part of its circumference by the auditory process, which is the name 
 applied to the free rough margin of the tympanic plate, and which gives attach- 
 ment to the cartilaginous portion of the meatus. Superiorly tlie entrance to 
 the meatus is limited by the posterior root of the zygoma. At the upper and 
 posterior portion of the bony meatus is a spine of bone known as the suprameatal 
 spine or spine of Henle (spina suprameatum) , which is a valuable surgical land- 
 mark. In most skulls it is distinctly marked. 
 
 Apex {apex pyramidis). — The apex of the petrous portion, rough and uneven, 
 is received into the angular interval between the posterior border of the greater 
 wing of the sphenoid and the basilar process of the occipital; it presents the anterior 
 or internal orifice of the carotid canal (foramen caroticum internum) , and forms 
 the posterior and external boundary of the foramen lacerum medium. 
 
 Surfaces. Anterior Surface (fades anterior pyramidis). — The anterior surface 
 of the petrous portion (Fig. 47) forms the posterior part of the middle fossa of 
 the skull. This surface is continuous with the squamous portion, to which it is 
 united by a suture, the petro-squamous suture, the remains of which are distinct even 
 at a late period of life. It presents six points for examination: (1) An eminence 
 {eminentia arcuata) near the centre, which indicates the situation of the 
 superior semicircular canal. (2) In front and a little to the outer side of this 
 eminence a depression indicating the position of the tympanum ; here the layer 
 of bone which separates the tympanum from the cranial cavity is extremely thin, 
 and is known as the tegmen tympani. (.3) A shallow groove, sometimes double, 
 leading outward and backward to an oblique opening, the hiatus Fallopii (hiatus 
 canalis facialis) , for the passage of the greater petrosal nerve and the petrosal 
 branch of the middle meningeal artery. (4) A smaller opening (apertura superior 
 canalicidi tympanici) , occasionally seen external to the latter, for the passage of 
 the smaller petrosal nerve. (5) Xear the apex of the bone, the termination of the 
 carotid canal, the internal carotid foramen (foramen caroticum internum), the wall 
 of which in this situation is deficient in front. (6) Above the canal a shallow 
 depression, the trigeminal depression (impressio trigeminy), for the reception of the 
 Gasserian ganglion. 
 
THE TEMPORAL BONE 
 
 89 
 
 Posterior Surface (fades posterior pyramidis). — The posterior surface forms the 
 front part of the posterior fossa of the skull, and is continuous with the inner 
 surface of the mastoid portion of the bone. It presents three points for exami- 
 nation: 1. About its centre, a large orifice, the meatus auditorius internus (meatus 
 acusticus internus), whose size varies considerably; its margins are smooth and 
 rounded, and it leads into a short canal, about four lines in length, which runs 
 directly outward and is closed by a vertical plate, the lamina cribrosa, which is 
 divided by a horizontal crest, the falciform crest (crista falciformis) , into two unequal 
 portions ( Fig. 50) . Each portion is subdivided by a little vertical crest into two parts, 
 named, respectively, anterior and posterior. The lower portion presents three sets 
 of foramina: one group just below the poste- 
 rior part of the crest, the area cribro«a media, 
 consisting of a number of small openings 
 for the nerves to the saccule; below and 
 posterior to this, the foramen singulare, or 
 opening for the nerve to the posterior semi- 
 circular canal; in front and below the first, 
 the tractus spiralis foraminosus, consisting 
 of a numlier of small, spirally arranged 
 openings which terminate in the canalis 
 centralis cochleae and transmit the nerve to 
 the cochlea; the upper portion, that above 
 the crista, presents behind a series of small 
 openings the area cribrosa superior, for the 
 passage of filaments to the utricle and supe- 
 rior and external semicircular canal, and, in 
 front, one large opening, the commence- 
 ment of the aquaeductus Fallopii (canalis 
 facialis), for the passage of the facial nerve. 
 
 2. Behind the meatus auditorius, a small 
 slit (apertura externa aqiioeducfus vestihidi), 
 almost hidden by a thin plate of bone, lead- 
 ing to a canal, the aquaeductus vestibuli, 
 which transmits the ductus endolymphaticus 
 together with a small artery and vein. In 
 
 the interval between these two openings, but above them, is an angular depression 
 (fossa subarcuata) which lodges a process of the dura mater, and transmits a 
 small vein into the cancellous tissue of the bone. In the child this depression 
 is representefl by a large fossa, the floccular fossa, which extends backward as a 
 blind tunnel under the superior semicircular canal. 
 
 Inferior Surface (fades inferior pyramidis) . — The inferior or basilar surface (Fig. 
 51) is rough and irregular, and forms part of the base of the skull. Passing from 
 the apex to the base, this surface presents eleven points for examination: 1. A 
 rough surface, quadrilateral in* form, which serves partly for the attachment of 
 the Levator palati and Tensor tympani muscles. 2. The large, circular aperture 
 of the carotid canal, the external carotid foramen (foramen caroticum externum) ; the 
 canal ascends at first vertically, and then, making a bend, runs horizontally for- 
 ward and inward; it transmits the internal carotid artery and the carotid plexus. 
 Within the carotid canal are several openings (canaliculi carotico tympanici) which 
 transmit tympanic branches of the internal carotid artery and of the carotid plexus. 
 
 3. The opening of the aquaeductus cochleae (apertura externa canaliculi cochleoe), a 
 small triangular opening, lying on the inner side of the latter, close to the posterior 
 border of the petrous portion; it transmits a vein from the cochlea, which joins 
 the internal jugular. 4. Behind these openings a deep depression, the jugular fossa 
 
 Fig. 50. — Diagrammatic view of the fundus 
 of the internal auditory meatus: 1. Falciform 
 crest. 2. Anterior superior cribriform area. 2'. 
 Internal opening of the aquaeductus Fallopii. 
 3. Vertical crest which separates the anterior 
 and po-sterior superior cribriform areas. 4. Pos- 
 terior superior cribriform area, with (4') open- 
 ings for nerve-filaments. 5. Anterior inferior 
 cribriform area. 5'. Spirally arranged, sieve-like 
 openings for the nerves to the cochlea. 5". Open- 
 ing of the central canal of the cochlea. 6. Crest 
 which separates the anterior and posterior infe- 
 rior cribriform areas. 7. Posterior inferior crib- 
 riform area. 7'. Orifices for the branches of the 
 nerve to the saccule. 8. Foramen singulare of 
 Morgagni, with the anterior portion of the canal 
 which gives passage to the nerve to the posterior 
 semicircular canal. (Testut) 
 
90 
 
 THE SKELETON 
 
 (fossa jugularis), which varies in depth and size in different skulls; it lodges the 
 lateral sinus, and, with a similar depression on the margin of the jugular process of 
 the occipital bone, forms the foramen lacerum posterius or jugular foramen. 5. A 
 foramen which is the opening of a small canal (canaliculus tympanicus) , for the 
 
 Canals for Eustachian tube and 
 
 TENSOR TYMPANI MUSCLE 
 LEVATOR PALATI 
 
 Rough quadrilateral surface. 
 
 Opening of carotid canal. 
 
 Canal for Jacohson's nerve. 
 
 Aquseductus cochlese. 
 
 Canal for Arnold's nerve. 
 
 Jugular fossa. 
 
 Vaginal process. 
 
 Styloid process. 
 Stylo-mastoid foramen: 
 Jugular surface. 
 Auricular fissure. 
 
 STYL0-PHARVNGEU8. 
 
 Fig. 51. — Petrous portion. Inferior surface. 
 
 passage of Jacobson's nerve (the tympanic branch of the glosso-pharyngeal) ; 
 this foramen is seen in front of the bony ridge dividing the carotid canal from 
 the jugular fossa. 6. A small foramen on the wall of the jugular fossa, for the 
 entrance of the auricular branch of the pneumogastric (Arnold's) nerve. 7. Behind 
 the jugular fossa a smooth, square-shaped facet, the jugular surface; it is covered 
 with cartilage in the recent state, and articulates with the jugular process of 
 the occipital bone. 8. The vaginal process (vagina processus sUjloidea), a very 
 broad, sheath-like plate of bone, which extends backward from the carotid canal 
 and gives attachment to part of the Tensor palati muscle; this plate divides 
 behind into two laminae, the outer of which is continuous with the tympanic 
 plate, the inner with the jugular process. 9. Between these laminae is the ninth 
 point for examination, the styloid process (processus styloideus), a sharp spine, 
 about an inch in length; it is directed downward, forward, and inward, varies 
 in size and shape, and sometimes consists of several pieces united by cartilage; it 
 affords attachment to three muscles, the Stylo-pharyngeus, Stylo-hyoideus, and 
 Stylo-glossus, and two ligaments, the stylo-hyoid and stylo-maxillary. 10. The 
 stylo-mastoid foramen (foramen stylomastoideum) , a rather large orifice, placed 
 between the styloid and mastoid processes; it is the termination of the aquaeductus 
 Fallopii, and transmits the facial nerve and stylo-mastoid artery. 11. The auricular 
 fissure (fissura tympanomastoidea) , situated between the tympanic plate and 
 mastoid processes, for the exit of the auricular branch of the pneumogastric nerve 
 
THE TEMPORAL BONE 
 
 91 
 
 (Arnold's nerve). This fissure is the external opening of the canaliculus mas- 
 toideus, which passes to the aqueduct of Fallopius. 
 
 Borders. Superior Border {angulus superior pyramidis) . — The superior, the 
 longest, is grooved for the superior petrosal sinus, and has attached to it the ten- 
 torium cere})elli ; at its inner extremity is a semilunar notch, upon which the fifth 
 nerve lies. 
 
 Posterior Border {angulus posterior pyramidis). — The posterior border is inter- 
 mediate in length between the superior and the anterior. Its inner half is marked 
 by a groove, which, when completed by its articulation with the occipital, forms 
 the channel for the inferior petrosal sinus. Its outer half presents a deep excava- 
 tion, the jugular fossa Qossa jugidaris), which, with a similar notch on the occipital, 
 forms the foramen lacerum posterius. A projecting eminence of bone occasionally 
 stands out from the centre of the notch, and divides the foramen into two parts. 
 
 Anterior Border (angulus anterior pyramidis) . — The anterior border is divided 
 into two parts — an outer, joined to the squamous portion by a suture, the remains 
 of which are distinct; an inner, free, articulating with the spinous process of the 
 sphenoid. At the angle of junction of the petrous and squamous portions is 
 seen the opening of the canalis musculotubarius. This canal is completely or 
 partially divided into two canals, separated from one another by a thin plate of 
 bone, the processus cochleariformis (septum canalis musculotubarii) ; they both lead 
 into the tympanum, the upper one (semicanalis m. tensoris tympani) transmitting 
 the Tensor tympani muscle, the lower 
 one (semicanalis tubes auditivce) form- 
 ing the bony part of the Eustachian 
 tube or canal. 
 
 Structure. — The squamous portion 
 is like that of the other cranial bones: 
 the mastoid portion, cellular; and the 
 petrous portion, dense and hard. 
 
 Development (Fig. 52). — The tem- 
 poral bone is developed by ten centres, 
 exclusive of those for the internal ear 
 and the ossicula — viz., one of the 
 squamous portion including the zygo- 
 ma, one for the tympanic plate, six for 
 the petrous and mastoid parts, and two 
 for the styloid process. Just before the 
 close of foetal life the temporal bone 
 consists of four parts : 1 . The squamo- 
 zygomatic part, ossified in membrane 
 from a single nucleus, which appears 
 at its lower part about the second 
 month. 2. The tympanic plate, an imperfect ring, in the concavity of which is 
 a groove, the sulcus tympanicus, for the attachment of the circumference of the 
 tympanic membrane. This is also ossified from a single centre, which appears 
 about the third month. 3. The petro-mastoid part is developed from six cen- 
 tres, which appear about the fifth or sixth month. Four of these are for the 
 petrous portion, and are placed around the labyrinth, and two for the mastoid 
 (Vrolik). According to Huxley, the centres are more numerous, and are dis- 
 posed so as to form three portions: (1) including most of the labyrinth, with a 
 part of the petrous and mastoid, he has named prootic; (2) the rest of the petrous, 
 the opisthotic; and (3) the remainder of the mastoid, the epiotic. The petro- 
 mastoid is ossified in cartilage. 4. The styloid process is also ossified in cartilage 
 from two centres: one for the base, which appears before birth, and is termed the 
 
 1 for 
 squamous 
 portion, 
 including 
 zygoma : 
 2d month. 
 
 1 for tympanic 
 plate. 
 
 6 for petrous 
 
 and mastoid 
 
 portions. 
 
 2 for styloid process. 
 
 Fig. 52. — Development of the temporal bone, 
 ten centres. 
 
 By 
 
92 THE SKELETON 
 
 t3nQDipanohyal; the other, comprising the rest of the process, is named the stylohyal, 
 and does not appear until after birth. Shortly before birth the tympanic plate joins 
 with the squamous. The petrous and mastoid join with the squamous during 
 the first year, and the tympanohyal portion of the styloid process about the same 
 time. The stylohyal does not join the rest of the bone until after puberty, and 
 in some skulls never becomes united. The subsequent changes in this bone are, 
 that the tympanic plate extends outward and backward, so as to form the meatus 
 auditorius. The extension of the tympanic plate, however, does not take place at 
 an equal rate all around the circumference of the ring, but occurs most rapidly 
 on its anterior and posterior portions, and these outgrowths meet and blend, and 
 thus, for a time, there exists in the floor of the meatus a foramen, the foramen of 
 Buschke; this foramen may persist throughout life. The glenoid cavity is at first 
 extremely shallow, and looks outward as well as downward; it becomes deeper 
 and is ultimately directed downward. Its change in direction is accounted for 
 as follows : the part of the squamous temporal which supports it lies at first helow 
 the level of the zygoma. As, however, the base of the skull increases in width, 
 this lower part of the squama is directed horizontally inward to contribute to 
 the middle fossa of the skull, and its surfaces therefore come to look upward and 
 downward. The mastoid portion is at first quite flat, and the stylo-mastoid fora- 
 men and rudimentary styloid process lie immediately behind the entrance to the 
 auditory meatus. With the development of the air-cells the outer part of the 
 mastoid portion grows downward and forward to form the mastoid process, and 
 the styloid process and stylo-mastoid foramen now come to lie on the under sur- 
 face. The descent of the foramen is necessarily accompanied by a corresponding 
 lengthening of the aqueduct of Fallopius. 
 
 The downward and forward growth of the mastoid process also pushes forward 
 the tympanic plate, so that the portion of it which formed the original floor of 
 the meatus and containing the foramen of Huschke is ultimately found in the 
 anterior wall. With the gradual increase in size of the petrous portion the floc- 
 cular fossa or tunnel under the superior semicircular canal becomes filled up 
 and almost obliterated. 
 
 Articulations. — With five bones — occipital, parietal, sphenoid, inferior maxil- 
 lary, and malar. 
 
 Attachment of Muscles. — To fifteen : to the squamous portion, the Tem- 
 poral; to the zygoma, the Masseter; to the mastoid portion, the Occipito- 
 frontalis, Sterno-mastoid, Splenius capitis, Trachelo-mastoid, Digastricus, and 
 Retrahens aurem; to the styloid process, the Stylo-pharyngeus, Stylo-hyoideus, 
 and Stylo-glossus ; and to the petrous portion, the Levator palati, Tensor 
 tympani. Tensor palati, and Stapedius. 
 
 The Sphenoid Bone (Os Sphenoidale). 
 
 The sphenoid bone {oipr^v, a wedge) is situated at the anterior part of the base 
 of the skull, articulating with all the other cranial bones, which it binds firmly 
 and solidly together. In its form it somewhat resembles a bat with its wings 
 extended; and is divided into a central portion or body, two greater and two lesser 
 wings extending outward on each side of the body, and two processes — the ptery- 
 goid processes — which project from it below. 
 
 The Body of the Sphenoid Bone. 
 
 The body (eorpiis) is of large size and hollowed out in its interior so as to form a 
 mere shell of bone. It presents for examination jour surfaces — a superior, an 
 inferior, an anterior, and a posterior. 
 
THE SPHENOID BONE 
 
 93 
 
 Surfaces. Superior Surface (fades cerehralis) (Fig. 53). — In front is seen a promi- 
 nent spine, the ethmoidal spine, for articulation with the cribriform plate of the eth- 
 moid ; behind this a smooth surface presenting, in the median line, a slight longi- 
 tudinal eminence, with a depression on each side for lodging the olfactory lobes. 
 This surface is bounded behind by a ridge, which forms the anterior border of a 
 narrow, transverse groove, the optic groove {sulcus chiasmatis), behind which lies the 
 optic chiasm ; the groove is continuous on each side with the optic foramen (foramen 
 opticum) , for the passage of the optic nerve and ophthalmic artery. Behind the 
 
 Middle chnoid process. 
 _Posterior clinoid process 
 
 \ 
 
 Ethmoidal 
 
 Foramen opticum... 
 
 Foramen laceriim ante- 
 
 rius or Sphenoidal 
 
 fissure. 
 
 Foramen rotundum. 
 
 Foramen Vesalii. 
 
 Foramen ovale.' 
 
 Foramen spinosum. 
 
 Fig. 53. — Sphenoid bone. Superior surface. 
 
 optic groove is a small eminence, olive-like in shape, the olivary process or eminence 
 {tuberculum sellce) ; and still more posteriorly, a deep depression, the pituitary fossa, 
 or sella turcica (fossa hypophyseos) , which lodges the circular sinus and the pituitary 
 body (hypophysis). This fossa is perforated by numerous foramina, for the trans- 
 mission of nutrient vessels into the substance of the bone. It is bounded in front 
 by the olivary eminence, and also by two small eminences, one on either side, called 
 the middle clinoid processes (processus clinoidei medii) (x/cvrj, a bed), which are 
 sometimes connected by a spiculum of bone to the anterior clinoid processes. It 
 is bounded behind by a square-shaped plate of bone, the dorsum ephippii or dorsum 
 sellse, terminating at each superior angle in a tubercle, the posterior clinoid process 
 (processus clinoideu^ posterior). The size and form of these processes vary con- 
 siderably in different individuals. They deepen the pituitary fossa, and serve for 
 the attachment of prolongations from the tentoriimi cerebelli. The sides of the 
 dorsum ephippii are notched for the passage of the sixth pair of nerves, and 
 below present a sharp process, the petrosal process, which is joined to the apex 
 of the petrous portion of the temporal bone, forming the inner boundary of the 
 middle lacerated foramen. Behind this plate the bone presents a shallow depres- 
 sion, which slopes obliquely backward, and is continuous with the basilar groove 
 of the occipital bone; it is called the clivus, and supports the upper part of the 
 pons Varolii. On either side of the body is a broad groove, curved something like 
 the italic letter /; it lodges the internal carotid artery and the cavernous sinus, 
 and is called the carotid or cavernous groove (sul&iis caroticus). Along the outer 
 margin of this groove, at its posterior part, is a ridge of bone in the angle 
 between the body and greater wing, called the lingula (lingula sphenoidalis) . 
 
 Posterior Surface. — The posterior surface, quadrilateral in form, is joined to the 
 basilar process of the occipital bone. During childhood these bones are separated 
 
94 
 
 THE SKELETON 
 
 by a layer of cartilage; but in after-life (between the eighteenth and twenty-fifth 
 years) this becomes ossified, ossification commencing above and extending down- 
 ward; and the two bones then form one piece. 
 
 Anterior Surface. — The anterior surface (Fig. 54) presents, in the middle line, a 
 vertical ridge of bone, the ethmoidal or sphenoidal crest (crista sphenoidalis) , which 
 articulates in front with the perpendicular plate of the ethmoid, forming part of 
 the septum of the nose. On either side of it are irregular openings leading into 
 the sphenoidal cells or sinuses (sinus sphenoidales). These are two large, irregular 
 cavities hollowed out of the interior of the body of the sphenoid bone, often 
 
 Pterygoid ridge, 
 
 Internal pterygoid plate-Si- 
 HamuLar process.-^ 
 
 Fig. 54. — Sphenoid bone. Anterior surface.^ 
 
 extending into the pterygoid processes and base of the greater wings of the bone, 
 and separated from one another by a more or less complete perpendicular bony 
 septum (septum sinuum sphenoidalium). Occasionally they extend into the basilar 
 process of the occipital nearly as far as the foramen magnum. Their form and 
 size vary considerably; they are seldom symmetrical, and are often partially sub- 
 divided by irregular, osseous laminte. One sinus or both sinuses may be absent. 
 The septum is seldom quite vertical, being commonly bent to one or the other 
 side. These sinuses do not exist in very young children, but appear, according 
 to lyaurent, in the seventh year, and, according to Tillaux, not until the twen- 
 tieth year. After once appearing they increase in size as age advances. They 
 are partially closed, in front and below, by two thin, curved plates of bone, 
 the sphenoidal, spongy, or turbinated bones (conchce sphenoidales). At the upper 
 part of each is a round opening (apertura sinus sphenoidalis) by which the sinus 
 communicates with the upper and back part of the nose, and occasionally with 
 the posterior ethmoidal cells or sinuses. The lateral margins of this surface 
 present a serrated edge, which articulates with the os planum of the ethmoid, 
 completing the posterior ethmoidal cells; the lower margin, also rough and ser- 
 rated, articulates with the orbital process of the palate bone, and the upper 
 margin with the orbital plate of the frontal bone. 
 
 Inferior Surface. — The inferior surface presents, in the middle line, a triangular 
 spine, the rostrum (rostrum sphenoidalis), which is continuous with the sphenoidal 
 crest on the anterior surface, and is received into a deep fissure between the alse 
 
 1 ^'V^'?!? figure, both the anterior and inferior surfaces of the body of the sphenoid bone are shown, the bone 
 being held with the pterygoid processes almost horizontal. 
 
THE SPHENOID BONE 95 
 
 of the vomer. On each side may be seen a projecting lamina of bone, which runs 
 horizontally inward from near the base of the pterygoid process: these plates, termed 
 the vaginal processes, articulate with the edges of the vomer. Close to the root of 
 the pterygoid process is a groove (sulcus pterygopalatinus) , formed into a complete 
 canal when articulated with the sphenoidal process of the palate bone; it is called 
 the pterygo-palatine canal, and transmits the pterygo-palatine vessels and pharyngeal 
 nerve. 
 
 The Greater or Temporal Wings of the Sphenoid Bone (Alae Magnse). 
 
 The greater wings are two strong processes of bone which arise from the sides 
 of the body, and are curved in a direction upward, outward, and backward, each 
 being prolonged behind into a sharp-pointed extremity, the alar or sphenoidal 
 spine (spina angularis) . Each wing presents three surfaces and a circumference. 
 
 Surfaces. Superior Surface (fades cerebralis) . — The superior or cerebral surface 
 (Fig. 53) forms part of the middle fossa of the skull; it is deeply concave, and pre- 
 sents eminences and depressions for the convolutions of the brain. At its anterior 
 and internal part is seen a circular aperture, the foramen rotundum, for the transmis- 
 sion of the second division of the fifth nerve. Behind and external to this is a large, 
 oval foramen, the foramen ovale, for the transmission of the third division of the 
 fifth nerve, the small meningeal artery, and sometimes the small petrosal nerve.^ 
 At the inner side of the foramen ovale a small aperture may occasionally be seen 
 opposite the root of the pterygoid process; it is the foramen Vesalii, transmitting 
 a small vein. Lastly, in the posterior angle, near to the spine of the sphenoid, is 
 a short canal, sometimes double, the foramen spinosum; it transmits the middle 
 meningeal artery. 
 
 External Surface. — The external surface (Fig. 54) is convex and divided by a 
 transverse ridge, the pterygoid ridge or infratemporal crest (crista infratemporalis) , 
 into two portions. The superior or larger, convex from above downward, concave 
 from before backward, enters into the formation of the temporal fossa, and gives 
 attachment to part of the Temporal muscle. The inferior portion, smaller in size 
 and concave, enters into the formation of the zygomatic fossa, and affords attach- 
 ment to the External pterygoid muscle. It presents, at its posterior part, a sharp- 
 pointed eminence of bone, the spine, to which are connected the internal lateral 
 ligament of the lower jaw and the Tensor palati muscle. The pterygoid ridge, 
 dividing the temporal and zygomatic portions, gives attachment to part of the 
 External pterygoid muscle. At its inner and anterior extremity is a triangular 
 spine of bone, which serves to increase the extent of origin of this muscle. 
 
 Anterior Surface (fades orbitalis) . — The anterior or orbital surface, smooth and 
 quadrilateral in form, assists in forming the outer wall of the orbit. It is bounded 
 above by a serrated edge, for articulation with the frontal bone; below, by a rounded 
 border which enters into the formation of the spheno-maxillary fissure. Internally, it 
 presents a sharp border, which forms the lower boundary of the sphenoidal fissure, 
 and has projecting from about its centre a little tubercle of bone, which gives 
 origin to one head of the External rectus muscle of the eye; and at its upper part 
 is a notch for the transmission of a recurrent branch of the lachrymal artery; 
 externally it presents a serrated margin for articulation with the malar bone. One 
 or two small foramina may occasionally be seen for the passage of branches of 
 the deep temporal arteries; they are called the external orbital foramina. 
 
 Circumference (Fig. 53). — Commencing from behind, that portion of the cir- 
 cumference from the body of the sphenoid to the spine is serrated and articulates 
 by its outer half with the petrous portion of the temporal bone, while the inner 
 half forms the anterior boundary of the foramen lacerum mediiun, and presents 
 
 ^ The small petrosal nerve sometimes passes through a special foramen between the foramen ovale and 
 foramen spinosum. 
 
96 THE SKELETON 
 
 the posterior aperture of the Vidian canal (canalis ptenjgoideus) for the passage of the 
 Vidian nerve and artery. In front of the spine the circumference of the great wing 
 presents a serrated edge, bevelled at the expense of the inner table below and of the 
 external above, which articulates with the squamous portion of the temporal bone. 
 At the tip of the great wing a triangular portion is seen, bevelled at the expense of 
 the internal surface, for articulation with the anterior inferior angle of the parietal 
 bone. Internal to this is a triangular, serrated surface, for articulation with the 
 frontal bone; this surface is continuous internally with the sharp inner edge of 
 the orbital plate, which assists in the formation of the sphenoidal fissure, and 
 externally with the serrated margin for articulation with the malar bone. 
 
 The Lesser or Orbital Wings of the Sphenoid Bone (Alae Parvae). 
 
 The lesser wings (processes of Ingrassias) are two thin, triangular plates of 
 bone which arise from the upper and lateral parts of the body of the sphenoid, 
 and, projecting transversely outward, terminate in a sharp point (Fig. 53). The 
 superior surface of each is smooth, flat, broader internally than externally, and 
 supports part of the frontal lobe of the brain. The inferior surface forms the 
 back part of the roof of the orbit and the upper boundary of the orbital or sphe- 
 noidal fissure or foramen lacenim anterius (fissura orhitalis superior) . This fissure is 
 of a triangular form, and leads from the cavity of the cranium into the orbit; it is 
 bounded internally by the body of the sphenoid — above, by the lesser wing; 
 below, by the internal margin of the orbital surface of the great wing — and is 
 converted into a foramen by the articulation of this bone with the frontal. It 
 transmits the third, the fourth, the three branches of the ophthalmic division 
 of the fifth, the sixth nerve, some filaments from the cavernous plexus of the 
 sympathetic, the orbital branch of the middle meningeal artery, a recurrent 
 branch from the lachrymal artery to the dura mater and the ophthalmic vein. 
 The anterior border of the lesser wing is serrated for articulation with the 
 frontal bone; the posterior border, smooth and rounded, is received into the fissure of 
 Sylvius of the brain. Each inner extremity of this border forms an anterior clinoid 
 process (processus clinoideus anterior). The lesser wing is connected to the side 
 of the body by two roots, the upper thin and flat, the lower thicker, obliquely 
 directed, and presenting on its outer side, near its junction with the body, a small 
 tubercle, for the attachment of the common tendon of origin of three of the muscles 
 of the eye. Between the two roots is the optic foramen (foramen opticum), for 
 the transmission of the optic nerve and ophthalmic artery. 
 
 The Pterygoid Processes of the Sphenoid Bone (Processus Pterygoidei) . 
 
 The pterygoid processes (Tzripu^, a wing; slda:, likeness), one on each side, 
 descend perpendicularly from the point where the body and greater wing unite 
 (Fig. 55). Each process consists of an external and an internal lamina or plate, 
 which are joined together by their anterior borders above, but are separated below, 
 leaving an angular cleft, the pterygoid notch or fissure (fissura pterygoidea) , in which 
 the pterygoid process or tuberosity of the palate bone is received. The two plates 
 diverge from each other from their line of connection in front, so as to form a V- 
 shaped fossa, the pterygoid fossa (fossa pterygoidea) . The external pterygoid plate 
 (lamina lateralis processus pterygoidei) is broad and thin, turned a little outward, 
 and, by its outer surface, forms part of the inner wall of the zygomatic fossa, giving 
 attachment to the External pterygoid; its inner surface forms part of the pterygoid 
 fossa, and gives attachment to the Internal pterygoid. The internal pterygoid plate 
 (lamina medialis processus pterygoidei) is much narrower and longer, curving 
 outward, at its extremity, into a hook-like process of bone, the hamular process 
 
THE SPHENOID BONE 97 
 
 (hamulus pterygoideus) , around which turns the tendon of the Tensor palati 
 muscle. The outer surface of this plate forms part of the pterygoid fossa, the 
 inner surface forming the outer boundary of the posterior aperture of the nares. 
 On the posterior surface of the base of the process, above the pterygoid fossa, is a 
 small, oval, shallow depression, the scaphoid fossa (fossa scaphoidea), from which 
 arises the Tensor palati, and above which is seen the posterior orifice of the Vidian 
 canal {canalis pterygoideus [Vidii]). Below and to the inner side of the Vidian 
 
 Fig. 55. — Sphenoid bone. Posterior surface. 
 
 canal, on the posterior surface of the base of the internal plate, is a little promi- 
 nence, which is known by the name of the pterygoid tubercle. The Superior 
 constrictor of the pharynx is attached to the posterior edge of the internal plate. 
 The anterior surface of the pterygoid process is very broad at its base, and forms 
 the posterior wall of the spheno-maxillary fossa. It supports Meckel's ganglion. 
 It presents, above, the anterior orifice of the Vidian canal ; and below, a rough 
 margin, which articulates with the perpendicular plate of the palate bone. 
 
 The Sphenoidal Spongy Bone. 
 
 The sphenoidal spongy, turbinal or turbinated bones (the hones of Bertin, conchcB 
 sphenoidales) are two thin, curved plates of bones, which exist as separate pieces 
 until puberty, and occasionally are not joined to the sphenoid in the adult. They 
 are situated at the anterior and inferior part of the body of the sphenoid, an 
 aperture (apertura sinus sphenoidalis) of variable size being left in the anterior wall 
 of each, through which the sphenoidal sinuses open into the nasal fossae. They are 
 irregular in form and taper to a point behind, being broader and thinner in front. 
 Their upper surface, which looks toward the cavity of the sinus, is concave ; their 
 under surface convex. Each bone articulates in front with the ethmoid, exter- 
 nally with the palate; its pointed posterior extremity is placed above the vomer, 
 and is received between the root of the pterygoid process on the outer side and 
 the rostrum of the sphenoid on the inner. ^ 
 
 Development. — Up to about the eighth month of fcetal life the sphenoid bone 
 consists of two distinct parts: a posterior or post-sphenoid part, which comprises 
 the pituitary fossa, the greater wings, anfl the pterygoid processes; and an anterior 
 or pre-sphenoid part, to which the anterior part of the body and lesser wings 
 belong. It is developed by fourteen centres: eight for the posterior sphenoid 
 division, and six for the anterior sphenoid. The eight centres for the posterior 
 
 1 A small portion of the .sphenoidal turbinated bone sometimes enters into the formation of the inner wall of 
 the orbit, between the os planum of the ethmoid in front, the orbital plate of the palate below, and the frontal 
 above. — Cleland, Roy. Soe. Trans.. 1862. 
 
98 THE SKELETON 
 
 sphenoid are: one for each greater wing and external pterygoid plate, one for 
 each internal pterygoid plate, two for the posterior part of the body, and one on 
 each side for the lingula. The six for the anterior sphenoid are: one for each 
 lesser wing, two for the anterior part of the body, and one for each sphenoidal 
 turbinated bone. 
 
 Post-sphenoid Division. — The first nuclei to appear are those for the greater 
 wings (ali-sphenoids). They make their appearance between the foramen rotun- 
 
 dum and foramen ovale about the eighth 
 one for each two for anterior week, and from them the external pterygoid 
 
 lesser wing, ^art of body. pktes are also formed. Soon after, the 
 
 nuclei for the posterior part of the body 
 appear, one on either side of the sella turcica, 
 and become blended together about the 
 \ r\w/(*7<-T-3i ;<scn:« • middle of foetal life. About the fourth 
 
 ' yv/f^ T^^^V^V \ month the remaining four centres appear, 
 
 one for each i£rnai,Ai"" ' \ *^^.^^ ^^\ *^^^ internal pterygoid plates being 
 
 pterygoid plate. '-' \ ossified in membrane and becoming joined 
 
 me for for^ each lingula. \ to the external pterygoid plate about the 
 
 each great wing and external ptery- sixth month. The centres for the linguhe 
 onefor each Sphenoidal turbinated bme^^^'''"' speedily beCOme joined tO the rest of the 
 Fig. 66. — Plan of development of the sphenoid. _ ' , .,_.... rr\, n i • 
 
 By fourteen centres. Pie-sphenoid Division. — 1 lie hrst nuclci 
 
 to appear are those for the lesser wings 
 (orbito-sphenoids). They make their appearance about the ninth week, at the 
 outer borders of the optic foramina. A second pair of nuclei appear on the inner 
 side of the foramina shortly after, and, becoming united, form the front part of 
 the body of the bone. The remaining two centres for the sphenoidal turbinated 
 bones make their appearance about the fifth month. At birth they consist of small 
 triangular laminae, and it is not till the third year that they become hollowed out 
 and cone-shaped. About the fourth year they become fused with the lateral 
 masses of the ethmoid, and hence, from an embryological point of view, may be 
 regarded as belonging to the ethmoid. 
 
 The pre-sphenoid is united to the body of the post-sphenoid about the eighth 
 month, so that at birth the bone consists of three pieces — viz., the body in the 
 centre, and on each side the great wings with the pterygoid processes. The lesser 
 wings become joined to the body at about the time of birth. At the first year 
 after birth the greater wings and body are united. From the tenth to the twelfth 
 year the spongy bones are partially united to the sphenoid, their junction being 
 complete by the twentieth year. Lastly, the sphenoid joins the occipital from the 
 eighteenth to the twenty-fifth year. 
 
 Articulations. — The sphenoid articulates with all the bones of the cranium, 
 and five of the face — the two malar, the two palate, and vomer; the exact extent 
 of articulation with each bone is shown in the accompanying figures.^ 
 
 Attachment of Muscles. — To eleven pairs: the Temporal, External pterygoid, 
 Internal pterygoid, Superior constrictor. Tensor palati, Levator palpebrae, Ob- 
 liquus oculi superior, Superior rectus. Internal rectus, Inferior rectus. External 
 rectus. 
 
 The Ethmoid Bone (Os Ethmoidale). 
 
 The ethmoid (/jd/jto^, a sieve) is an exceedingly light, spongy bone, of a cubical 
 form, situated at the anterior part of the base of the cranium, between the two 
 orbits at the root of the nose, and contributing to form each of these cavities. 
 
 ' It also sometimes articulates with the tuberosity of the superior maxilla. 
 
THE ETHMOID BONE 
 
 99 
 
 It consists of three parts: a horizontal plate, which forms part of the base of the 
 cranium; a perpendicular plate, which forms part of the septum nasi; and two 
 lateral masses of cells. 
 
 The Horizontal Lamina or Cribriform Plate {lamina crihrosa) (Fig. 57) forms 
 part of the anterior fossa of the base of the skull, and is received into the ethmoid 
 notch of the frontal bone be- 
 tween the two orbital plates. 
 Projecting upward from the 
 middle line of this plate is a 
 thick, smooth, triangular pro- 
 cess of bone, the crista galli, so 
 called from its fancied resem- 
 blance to a cock's comb. Its 
 base joins the cribriform plate. 
 Its posterior border, long, thin, 
 and slightly curved, serves for 
 the attachment of the falx cere- 
 bri. Its anterior border, short 
 and thick, articulates with the 
 frontal bone, and presents two 
 small projecting alae (processus 
 alares), which are received in- 
 to corresponding depressions 
 in the frontal, completing the 
 foramen caecum behind. Its sides are smooth and sometimes bulging; in which 
 case it is found to enclose a small sinus.* On each side of the crista galli the cribri- 
 form plate is narrow and deeply grooved, to support the bulb of the olfactory tract, 
 and is perforated by foramina for the passage of the olfactory nerves. These fora- 
 
 FiG. 57.- 
 
 With inferior turbinated bone. 
 
 -Ethmoid bone. Outer surface of right lateral mass 
 (enlarged). 
 
 LAMINA CRIBROSA 
 
 CRISTA GALLI 
 
 ALAR PROCESS 
 
 MINA CRIBROSA 
 
 UNCIFORM 
 PROCESS 
 
 ETHMOIDAL 
 LABYRINTH 
 
 Fig. .58. — Ethmoid bone from behind, somewhat 
 schematic. (Spalteholz.) 
 
 PERPENDICU- 
 LAR LAMINA 
 
 POSTERIOR 
 ETHMOIDAL 
 FORAMEN 
 
 ANTERIOR 
 
 ETHMOIDAL 
 
 FORAMEN 
 
 RISTA GALLI 
 
 ALAR PROCESS 
 
 Fig. 59. — Ethmoid bone from above. (Spalteholz.) 
 
 mina are arranged in three rows: the innermost, which are the largest and least 
 numerous, are lost in grooves on the upper part of the septum; the foramina of the 
 outer row are continued on to the surface of the upper spongy bone. The fora- 
 mina of the middle row are the smallest; they perforate the bone and transmit 
 nerves to the roof of the nose. At the front part of the cribriform plate, on each 
 
 ' Sir George Humphry states that the crista galli is commonly inclined to one side, usually the opposite to 
 that toward which the lower part of the perpendicular plate is bent. — The Human Skeleton, 1858, p. 277. 
 
100 
 
 THE SKELETON 
 
 wAl, Ethmoidal 
 
 Fig 
 
 side of the crista galli, is a small fissure, which transmits the nasal branch of the 
 ophthalmic nerve; and at its posterior part a triangular notch, which receives the 
 ethmoidal spine of the sphenoid. 
 
 The Vertical or Perpendicular Lamina or Plate (lamina perpendicularis or 
 mesethmoid) (Fig. 60) is a thin, flattened lamella of bone, which descends from the 
 under surface of the cribriform plate, and assists in forming the septum of the nose. 
 It is much thinner in the middle than at the circumference, and is generally deflected 
 a little to one side. Its anterior border articulates with the nasal spine of the frontal 
 bone and crest of the nasal bones. Its posterior border, divided into two parts, 
 
 articulates by its upper 
 half with the sphenoidal 
 crest of the sphenoid, by 
 its lower half with the 
 vomer. The inferior bor- 
 der serves for the attach- 
 ment of the triangular car- 
 tilage of the nose. On 
 each side of the perpen- 
 dicular plate numerous 
 grooves and canals are 
 seen, leading from the for- 
 amina on the cribriform 
 plate; they lodge filaments 
 of the olfactory nerves. 
 
 The Lateral Mass or 
 Labyrinth (labyrinthus 
 ethmoidalis) of the ethmoid 
 consists of a number of 
 thin-walled cellular cavities, the ethmoidal cells (cellulw etkmoidales) interposed be- 
 tween two vertical plates of bone, the outer one of which forms part of the orbit, 
 and the inner one part of the nasal fossa of the corresponding side. There are two 
 lateral masses, one on each side. The ethmoidal cells are not present at birth, 
 but appear during the fifth year. In the disarticulated bone many of these cells 
 appear to be broken; but when the bones are articulated they are closed in at 
 every part, except where they open into the nasal fossi«. The wpper surface of 
 each lateral mass presents a number of apparently half-broken cellular spaces; 
 these are closed in, when articulated, by the edges of the ethmoidal notch of the 
 frontal bone. Crossing this surface are two grooves on each side, converted into 
 canals by articulation with the frontal ; they are the anterior and posterior ethmoidal 
 canals {canalis ethmoidale anterius and posterius), and open on the inner wall of 
 the orbit. The posterior surface also presents large, irregular cellular cavities, 
 which are closed in by articulation with the sphenoidal turbinated bones and 
 the orbital process of the palate. The cells at the anterior surface are completed 
 by the lachrymal bone and nasal process of the superior maxillary, and those 
 below also by the superior maxillary. The older surface of each lateral mass is 
 formed of a thin, smooth, oblong plate of bone, called the os planum [lamina 
 papyracea) ; it forms part of the inner wall of the orbit, and articulates, above, 
 with the orbital plate of the frontal ; below, with the superior maxillary; in 
 front, with the lachrymal; and behind, with the sphenoid and orbital process of 
 the palate. 
 
 From the inferior part of each lateral mass, immediately beneath the os planum, 
 there projects downward and backward an irregular lamina of bone, called the 
 unciform process (processus uncinatus) , from its hook-like form ; it serves to close 
 in the upper part of the orifice of the antrum, and articulates with the ethmoidal 
 
 60. — Perpendicular plate of ethmoid (enlarged), shown by 
 removing the right lateral mass. 
 
THE ETHMOID BONE 101 
 
 process of the inferior turbinated bone. It is often broken in disarticulating the 
 bones. 
 
 The inner surface of each lateral mass forms part of the outer wall of the nasal 
 fossa of the corresponding side. It is formed of a thin lamella of bone, which 
 descends from the under surface of the cribriform plate, and terminates below in 
 a free, convoluted margin, the middle turbinated or the inferior ethmoidal turbinate 
 bone (concha nasalis media). The middle turbinated bone may contain a cell or 
 cells, which are really ethmoidal cells. Howard A. Lothrop^ studied 1000 speci- 
 mens, and found cells in 9 per cent, 
 of them. He never found cells in 
 children. As a rule, a turbinate cell 
 communicates with a posterior eth- 
 moidal cell, but may join an anterior 
 ethmoidal cell. The cells may open 
 into the superior meatus or into the 
 middle meatus. The whole of this 
 surface is rough and marked above 
 by numerous grooves, which run nearly 
 vertically downward from the cribri- 
 form plate; they lodge branches of the 
 
 IP, 1*1, j'i*Vj.J Fig. 61. — Ethmoid bone. Inner surface of right lateral 
 
 olfactory nerve, which are distributed mass (enlarged). 
 
 on the mucous membrane covering the 
 
 bone. The back part of this surface is subdivided by a narrow oblique fissure, the 
 superior meatus of the nose (meatus nasi superior) , bounded above by a thin, curved 
 plate of bone, the superior turbinated bone (concha nasalis superior). By means of an 
 orifice at the upper part of this fissure the posterior ethmoitlal cells open into the 
 nose. Below, and in front of the superior meatus, is seen the convex surface of 
 the middle turbinated bone. It extends along the whole length of the inner sur- 
 face of each lateral mass; its lower margin is free and thick, and its concavity, 
 directed outward, assists in forming the middle meatus. It is by a large orifice 
 at the upper and front part of the middle meatus that the anterior ethmoidal cells, 
 and through them the frontal sinuses, communicate with the nose by means of a 
 funnel-shaped canal, the infundibulum (infundibulum ethmoidale). The cellular 
 cavities of each lateral mass, thus walled in by the os planum on the outer side and 
 by the other bones already mentioned, are divided by a thin transverse bony parti- 
 tion into two sets, which do not communicate with each other; they are termed 
 the anterior and posterior ethmoidal cells or sinuses. The former, more numerous, 
 communicate with the frontal sinuses above and the middle meatus below by 
 means of a long, flexuous canal, the infundibulum; the posterior, less numerous, 
 open into the superior meatus and communicate (occasionally) with the sphe- 
 noidal sinuses. In some cases the ethmoidal sinuses communicate with the maxil- 
 lary sinus. In some cases the os planum never develops, and the ethmoidal 
 sinuses are separated from the orbit inerely by membrane. 
 
 Development. — By three centres: one for the perpendicular lamella, and one 
 for each lateral mass. The lateral masses are first developed, ossific granules 
 making their appearance in the os planum between the fourth and fifth months 
 of foetal life, and extending into the spongy bones. At birth the bone consists of 
 the two lateral masses, which are small and ill-developed. During the first year 
 after birth the perpendicular plate and crista galli begin to ossify, from a single 
 nucleus, and become joined to the lateral masses about the beginning of the second 
 year. The cribriform plate is ossified partly from the perpendicular plate and 
 partly from the lateral masses. The formation of the ethmoidal cells, which com- 
 pletes the bone, does not commence until the end of the fourth year. 
 
 ' Annals of Surgery, May, 1903. 
 
102 THE SKELETON 
 
 Articulations. — With fifteen bones: the sphenoid, two sphenoidal turbinated, 
 the frontal, and eleven of the face — the two nasal, two superior maxillary, two 
 lachrymal, two palate, two inferior turbinated, and the vomer. No muscles are 
 attached to this bone. 
 
 DEVELOPMENT OF THE CRANIUM. 
 
 The cerebral vesicles became enclosed by an envelope of membrane derived from the em- 
 bryonic connective tissue about the head end of the chorda. This sac from the mesoderm 
 is converted into fibrous tissue, and is known as the membranous cranium. In adult Hfe 
 the dura mater represents the membranous cranium. 
 
 In mammals the base and part of the sides of the membranous cranium become cartilaginous, 
 but the roof and the remaining part of the sides remain membi'anous. Ossification com- 
 mences in the roof and begins at a later period in the base. Although ossification begins in 
 the membrane bones before it does in the cartilage bones, and the bones of the roof appear 
 before the bones of the base and make considerable progress in their growth, at birth ossification 
 is more advanced in the base, this portion of the skull forming a solid, immovable groundwork. 
 
 The Skull at Different Ages. — The skull at birth is relatively of large size as compared 
 with the body. The cerebral cranium is large and the face is small. The fontanelles are 
 open (see below). There are no sutures, but the margins of adjacent bones are widely sepa- 
 rated by fibrous tissue which runs from the periosteum to the dura mater. The bones of the 
 vault have no diploe and digital impressions are absent on the cranial surfaces. The parietal 
 eminences and the frontal eminences are very distinct.' 
 
 The orbits and parietal bones are large. If the base is examined it is noted that the 
 mastoid processes are absent, that the lower border of the symphysis of the jaw is on a level 
 with the condyles of the occipital bone, and that the pterygoid plates form " a large angle with 
 the skull base, whereas in the adult the angle is almost a right one." ' The lower jaw at birth 
 is shown in Fig. 91 . 
 
 The development of individual bones is considered under the appropriate headings. At 
 puberty various pneumatic cells develop in bone and alter the form of the head and face. 
 
 After the eruption of the first set of teeth the age can be determined with reasonable cer- 
 tainty, and the degree of obliteration of the sutures will also give valuable information. In 
 the vast majority of individuals the metopic suture becomes a mere trace during the fifth or 
 sixth years. Ossification at the junction of the coronal and sagittal sutures and osseous union 
 of the sphenoid and basilar portion of the occipital occur during maturity. The lower jaw of 
 an adult is shown in Fig. 93. 
 
 In old age much of the diploe disappears and the bones become thinner and more porous. 
 The alveolar surfaces of the jaws are absorbed if the teeth are lost, and the lower jaw alters 
 its form (Fig. 94). 
 
 Sexual Differences. — It is not always possible to tell with certainty a woman's skull from 
 a man's, but certain features are of value in reaching a conclusion. Virchow maintained that 
 in non-European races it is very difficult to determine the sex from the skull, though among 
 some savage races the differences may be great.^ It is always to be borne in mind that a 
 woman's skull may he of the masculine type and a man's skull mmj he of the feminine type. 
 There is no constant characteristic significant of the male or female skull. As a general rule, 
 the female skull is smaller than the male; it is lighter, the muscular ridges and processes are 
 less distinct, the mastoid processes are of less size, the orbital margins are thin and sharp 
 (Cunningham), the forehead is more vertical and the vertex is more flattened (Cunningham), 
 and the edge of the tympanic plate is " rounder and more tuberculous " (Cunningham). The 
 frontal air sinuses are smaller in women than in men, one reason why the glabella is more 
 prominent in men. The flattening of the vertex in women, previously referred to, causes 
 the top of the head to be at a more marked angle with the forehead than in men (Ecker). 
 This characteristic was recognized by the Greek sculptors (Havelock Ellis). The cephalic 
 index, which shows the relation of skull breadth to skull length, is of doubtful value in 
 determining sex. 
 
 The Fontanelles (Fonticuli). 
 
 Before birth the bones at the vertex and side of the skull are separated from each other by 
 membranous intervals in which bone is deficient. These intervals are principally found at the 
 four angles of the parietal bones. Hence there are six fontanelles. Their formation is due to 
 the wave of ossification being circular and the bones quadrilateral ; the ossific matter first meets 
 at the margins of the bones, at the points nearest to their centres of ossification, and vacuities 
 
 1 J. Bland Sutton in Henry Morris' Human Anatomy. ^ Ibid. 
 
 * Man and Woman, by Havelock Ellis. 
 
8UPEBNUMEBABY, WORMIAN OB SUTUBAL BONES 
 
 103 
 
 or spaces are left at the angles, which are called fontanelles, so named from the pulsations of 
 the brain, which are perceptible at the anterior fontanelle, were likened to the rising of water 
 in a fountain. The anterior or bregmatic fontanelle {fonticulus frontalis) is the largest; it is 
 lozenge-shaped, and corresponds to the junction of the sagittal and coronal sutures; the pos- 
 terior fontanelle {fonticulus occipitalis), of smaller size, is triangular, and is situated at the 
 junction of the sagittal and lambdoid sutures; the remaining ones, the antero-lateral and the 
 postero-lateral fontanelles {fonticulus sphenoidalis et fonticulus mastoideus), are situated at the 
 inferior angles of each parietal bone. The latter are closed soon after birth; the two at the two 
 superior angles remain open longer; the posterior being closed in a few months after birth; the 
 anterior remaining open until the first or second year. These spaces are gradually filled in by an 
 extension of the ossifying process or by the development of. a Wormian bone. Sometimes the ante- 
 rior fontanelle remains open beyond two years, and is occasionally persistent throughout life. 
 
 Supernumerary, Wormian,^ Sutural or Epactal Bones (Ossa Triquetra). 
 
 In addition to the constant centres of ossification of the skull, additional ones are occasion- 
 ally found in the course of the sutures. These form irregular, isolated bones, interposed between 
 the cranial bones, and have been termed Wormian bones or OSSa triquetra. They are most 
 
 Fig. 62. — Skull at birth, showing the anterior and 
 posterior fontanelles. 
 
 Fig. 63. — The lateral fontanelles. 
 
 frequently found in the course of the lambdoid suture, but occasionally also occupy the situation 
 of the fontanelles, especially the posterior and, more rarely, the anterior. Frequently one is 
 found between the anterior inferior angle of the parietal bone and the greater wing of the 
 
 Fig. 64. — Wormian bones. 
 
 Fig. 65. 
 
 Fig. 66. 
 
 sphenoid, the epicteric bone or the pterion ossicle (Fig. 63). They have a great tendency to be 
 symmetrical on the two sides of the .skull, and they vary much in size, being in some cases not 
 larger than a pin's head, and confined to the outer table; in other cases so large that one pair of 
 these bones may form the whole of the occipital bone above the superior curved lines, as described 
 
 * Wormius, a physician of Copenhagen, is said to have given the first detailed description of these bones. 
 
104 
 
 THE SKELETON 
 
 by B^clard and Ward. Their number is generally limited to two or three, but more than a 
 hundred have been found in the skull of an adult hydrocephalic skeleton. In their development, 
 structure, and mode of articulation they resemble the other cranial bones. 
 
 Congenital Fissures and Gaps. 
 
 An arrest in the ossifying process may give rise to deficiencies or gaps; or to fissures, which 
 are of importance in a medico-legal point of view, as they are liable to be mistaken for fractures. 
 The fissures generally extend from the margins toward the centre of the bone, but the gaps 
 may be found in the middle as well as at the edges. In course of time they may become covered 
 with a thin lamina of bone. 
 
 BONES OF THE FACE (OSSA FACIEI). 
 
 The Facial Bones are fourteen in number — viz., the 
 Two Nasal. Two Palate. 
 
 Two Superior Maxillae. Two Inferior Turbinated. 
 
 Two Lachrymal. Vomer. 
 
 Two Malar. Inferior Maxilla or Mandible. 
 
 "Of these, the upper and lower jaws are the fundamental bones for mastication^ 
 and the others are accessories; for the chief function of the facial bones is to 
 provide an apparatus for mastication, while subsidiary functions are to provide for 
 the sense organs (eye, nose, tongue) and a vestibule to the respiratory and vocal 
 organs. Hence the variations in the shape of the face in man and the lower 
 animals depend chiefly on the question of the character of their food and their 
 mode of obtaining it."^ 
 
 The Nasal Bones (Ossa Nasalia). 
 
 The nasal {nasus, the nose) are two small oblong bones, varying in size and 
 form in different individuals; they are placed side by side at the middle and upper 
 
 Nasal bone. 
 
 Nasal proc ^ 
 
 / 
 
 Lachrymal hone. 
 
 Orbital surface. 
 Infra-orbital 
 groove. 
 
 Infra-orbital 
 foramen 
 
 Ant. nasal spine.- 
 
 ■Artie, with malar. 
 
 Maxillary 
 tuberosity. 
 
 Fig. 67. — Nasal and lachrymal bones in situ. 
 
 part of the face, forming, by their junction, "the bridge" of the nose (Fig. 67). 
 Each bone presents for examination two surfaces and four borders. 
 
 1 W. W. Keen, American edition, 1887, p. 185. 
 
THE SUPEBIOB MAXILLARY BONES 
 
 105 
 
 Surfaces. Outer Surface. — The outer surface is concave from above downward, 
 convex from side to side; it is covered by the Pyramidalis and Compressor nasi 
 muscles, and gives attachment at its upper part to a few fibres of the Occipito- 
 frontahs muscle (Theile). It is marked by numerous small arterial furrows, and 
 perforated about its centre by a foramen {foramen nasale), sometimes double, 
 for the transmission of a small vein. 
 
 Inner Surface. — The inner surface is concave from side to side, convex from 
 above downward; in which direction it is traversed by a longitudinal groove 
 (sometimes a canal), for the 
 
 With frontal bone. 
 
 With 
 
 With 
 'opposite bone. 
 
 Outer Surface. 
 
 Fig. 68. — Right nasal bone. 
 
 frontal spine. 
 
 Crest. 
 
 With 
 perpendicular 
 plate of 
 ethmoid. 
 
 Groove for nasal nerve. 
 
 Inner Surface. 
 
 Fig. 69. — Left nasal bone. 
 
 passage of a branch of the nasal 
 nerve. 
 
 Borders. Superior Border. — 
 The superior border is narrow, 
 thick, and serrated, for articula- 
 tion with the nasal notch of the 
 frontal bone. 
 
 Inferior Border. — The inferior 
 border is broad, thin, sharp, in- 
 clined obliquely downward, out- 
 ward, and backward, and serves 
 for the attachment of the lateral 
 cartilage of the nose. This bor- 
 der presents, about its middle, a notch, through which passes the branch of the 
 nasal nerve above referred to, and is prolonged at its inner extremity into a sharp 
 spine, which, when articulated with the opposite bone, forms the nasal angle. 
 
 External Border. — The external border is serrated, bevelled at the expense of 
 the internal surface above and of the external below, to articulate with the nasal 
 process of the superior maxillary. 
 
 Internal Border. — The internal border, thicker above than below, articulates 
 with its fellow of the opposite side, and is prolonged behind into a vertical crest, 
 which forms part of the septum of the nose; this crest articulates above down- 
 ward with the nasal spine of the frontal above, and the perpendicular plate of 
 the ethmoid, and the triangular septal cartilage of the nose. 
 
 Development.— By one centre for each bone, which appears about the eighth week. 
 
 Articulations. — With four bones: two of the cranium, the frontal and ethmoid, 
 and two of the face, the opposite nasal and the superior maxillary. 
 
 Attachment of Muscles. — A few fibres of the Occipito-frontalis muscle. 
 
 The Superior Maxillary Bones (Upper Jaw Bones or Maxillae). 
 
 The superior maxillje (maxilla, the jaw bone) are the most important bones 
 of the face from a surgical point of view, on account of the number of diseases to 
 which some of their parts are liable. Their careful examination becomes, there- 
 fore, a matter of considerable interest. They are the largest bones of the face, 
 excepting the lower jaw, and form, by their union, the whole of the upper jaw. 
 Each maxilla assists in the formation of three cavities, the roof of the mouth, the 
 floor and outer wall of the nasal fossse, and t!ie floor of the orbit, and also enters 
 into the formation of two fossae, the zygomatic and spheno-maxillary, and two 
 fissures, the spheno-maxillary and pterygo-maxillary. The bone presents for exam- 
 ination a body and four processes — malar, nasal, alveolar, and palate. 
 
 The Body of the Superior Maxilla (Corpus Maxlllas). 
 
 The body is somewhat cuboid and is hollowed out in its interior to form a 
 large cavity, the antrum of Highmore (sinus maxillaris) . Its surfaces are four — 
 
106 
 
 THE SKELETON 
 
 an external or facial, a posterior or zygomatic, a superior or orbital, and an 
 internal or nasal. 
 
 Surfaces. External Surface (fades anterior) . — The external anterior or facial 
 surface (Fig. 70) is directed forward and outward. It presents at its lower part a 
 series of eminences corresponding to the position of the anterior five alveoli (juga 
 alveolaria) . Just above those for the incisor teeth is a depression, the incisive or 
 m3niiiform fossa, which gives origin to the Depressor alie nasi ; and below it to the 
 alveolar border is attached a slip of the Orbicularis oris. Above and a little exter- 
 nal to it the Compressor nasi arises. More external is another depression, the 
 canine fossa (fossa canina) , larger and deeper than the incisive fossa, from which it 
 is separated by a vertical ridge, the canine eminence, corresponding to the socket of 
 the canine tooth. The canine fossa gives origin to the Levator anguli oris. Above 
 the canine fossa is the infraorbital foramen {foramen infraorhitale) , the termination 
 
 Outer Surface. 
 
 TENDO OCULI 
 
 Incisive fossa.- 
 
 Posterior dental 
 canals. 
 
 Maxillary tuberosity. 
 
 '»»««. Bicuspids. 
 Fig. 70. — Left superior maxilla. Outer surface. 
 
 of the infraorbital canal; it transmits the infraorbital vessels and nerve. Some- 
 times the infraorbital canal opens by two, very rarely by three, orifices on the 
 face. Above the infraorbital foramen is the margin of the orbit (margo infraor- 
 bitalis), which affords partial attachment to the Levator labii superioris proprius. 
 To the sharp margin of bone which bounds this surface in front and separates 
 it from the internal surface is attached the Dilator naris posterior. 
 
 Posterior Surface (fades infratemporalis) . — The posterior or zygomatic or infra- 
 temporal surface is convex, directed backward and outward, and forms part of the 
 zygomatic fossa. It is separated from the facial surface by a strong ridge of bone, 
 the malar process, which extends upward from the socket of the second molar 
 tooth. It presents about its centre several apertures leading to canals in the 
 substance of the bone; they are termed the posterior dental canals (foramina alveo- 
 laria), and transmit the posterior dental vessels and nerves. At the lower part of 
 this surface is a rounded eminence, the maxillary tuberosity (tuber maxillare), 
 especially prominent after the growth of the wisdom-tooth, rough on its inner 
 
THE SUPERIOR MAXILLARY BONES 107 
 
 side for articulation with the tuberosity of the palate bone, and sometimes with 
 the external pterygoid plate. It gives attachment to a few fibres of origin of 
 the Internal pterygoid muscle. Immediately above this is a smooth surface, 
 which forms the anterior boundary of the spheno-maxillary fossa; it presents a 
 groove which, running obliquely downward, is converted into a canal by articu- 
 lation with the palate bone, forming the posterior palatine or palato-maxillary canal 
 for the descending palatine artery and great palatine nerve. 
 
 Superior Surface (fades orhitalis). — The superior or orbital surface is thin, 
 smooth, triangular, and forms part of the floor of the orbit. It is bounded in- 
 ternally by an irregular margin which in front presents a notch, the lachrymal notch 
 {incisura lacrimalis) , which receives the lachrymal bone; in the middle articulates 
 with the OS planum of the ethmoid, and behind with the orbital process of the 
 palate bone; bounded externally by a smooth, rounded edge which enters into the 
 formation of the spheno-maxillary fissure, and which sometimes articulates at its 
 anterior extremity with the orbital plate of the sphenoid; bounded in front by part 
 of the circumference of the orbit, which is continuous on the inner side with the 
 nasal, on the outer side with the malar process. Along the middle hne of the orbital 
 surface is a deep groove, the infraorbital groove {sulcus infraorbitalis) , for the pas- 
 sage of the infraorbital vessels and nerve. The groove commences at the middle 
 of the outer border of this surface, and, passing forward, terminates in a canal, 
 which subdivides into two branches. One of the canals, the infraorbital canal 
 (canalis infraorbitalis), opens just below the margin of the orbit; the other, which 
 is smaller, runs downward in the substance of the anterior wall of the antrum; 
 it is called the anterior dental canal, and transmits the anterior dental vessels 
 and nerve to the front teeth of the upper jaw. From the back part of the 
 infraorbital canal a second small canal is sometimes given off, which runs down- 
 w^ard in the outer wall of the antrum, and conveys the middle dental nerve to 
 the bicuspid teeth. Occasionally this canal is derived from the anterior dental. 
 At the inner and fore part of the orbital surface, just external to the lachrymal 
 groove for the nasal duct, is a depression which gives origin to the Inferior oblique 
 muscle of the eye. 
 
 Internal Surface (fades nasalis). — The internal or nasal surface (Fig. 71) is 
 unequally divided into two parts by a horizontal projection of bone, the palate 
 process (processus palatinus) : the portion above the palate process forms part of 
 the outer wall of the nasal fossa? ; that below it forms part of the cavity of the 
 mouth. The superior division of this surface presents a large, irregular opening, 
 the maxillary hiatus (hiatus maxillaris) , leading into the antrum of Highmore. 
 At the upper border of this aperture are numerous broken cellular cavities, which 
 in the articulated skull are closed in by the ethmoid and lachrymal bones. Below 
 the aperture is a smooth concavity which forms part of the inferior meatus of the 
 nasal fossae, and behind it is a rough surface which articulates with the perpendic- 
 ular plate of the palate bone, traversed by a groove which, commencing near the 
 middle of the posterior border, runs obliquely downward and forward, and forms, 
 when completed by its articulation with the palate bone, the posterior palatine or 
 palato-maxillary canal. In front of the opening of the antrum is a deep groove, 
 converted into a canal (canalis nasolacrimalis) by the lachrymal and inferior 
 turbinated bones. The groove is called the lachrymal groove (sulcus lacrimalis), 
 and lodges the nasal duct. More anteriorly is a well-marked rough ridge, the 
 inferior turbinated crest (crista conchalis), for articulation with the inferior turbin- 
 ated bone. The shallow concavity above this ridge forms part of the middle 
 meatus of the nose, while that below it forms part of the inferior meatus. The 
 portion of this surface below the palate process is concave, rough, and uneven, 
 and perforated by numerous small foramina for the passage of nutrient vessels. 
 It enters into the formation of the roof of the mouth. 
 
108 
 
 THE ^SKELETON 
 
 The Antrum of Highmore, Maxillary Antrum, or Maxillary Sinus {sinus maxil- 
 laris), is a pyramidal cavity hollowed out of the body of the maxillary bone. 
 It varies much in size. It is in most cases a large cavity, but in some is very 
 small. The apex of the antrum, directed outward, is formed by the malar process; 
 
 Bones partially dosing orifice of antrum 
 marked in outline. 
 
 Ethmoid. 
 
 Inferior turbinated. 
 
 Palate. 
 
 ^u!la,. 
 
 Anterior nasal spine. 
 
 Bristle passed 
 through anterior 
 palatine canal. 
 
 Fig. 71. — Left superior maxilla. Internal surface. 
 
 its base by the outer wall of the nose. Its walls are everywhere exceedingly thin, 
 and correspond to the orbital, facial, and zygomatic surfaces of the body of the 
 bone. The antral floor is, in most persons, on a level with the floor of the nasal 
 fossa, but in some individuals it is on a lower level. Not unusually the inner 
 wall of the antrum will be found to contain depressions or pockets. In rare 
 instances an antral cavity is made into two by a bony septum. Its inner wall or 
 base presents, in the disarticulated bone, a large, irregular aperture {hiatus 
 maxillaris), which communicates with the nasal fossa. The margins of this 
 aperture are thin and ragged, and the aperture itself is much contracted by its 
 articulation with the ethmoid above, the inferior turbinated below, and the 
 palate bone behind.^ In the articulated skull this cavity communicates with 
 the middle meatus of the nasal cavity, generally by two small apertures left 
 between the above-mentioned bones. In the recent state usually only one small 
 opening exists, near the upper part of the cavity, sufficiently large to admit the 
 end of a probe, the other being closed by the lining membrane of the sinus. That 
 the opening into the nasal fossa does not afford the best drainage is demon- 
 strated, when we note that it is at the highest and not at the lowest point of the 
 antrum. "In rare instances the antrum communicates with the anterior eth- 
 moidal cells, or the orbital and posterior ethmoidal cells and sphenoidal sinuses."^ 
 At birth the antrum exists, though in a rudimentary state. It attains its full 
 size from the twelfth to the fourteenth year. 
 
 Crossing the cavity of the antrum are often seen several projecting laminae of 
 bone, similar to those seen in the sinuses of the cranium ; and on its posterior wall 
 
 1 In some cases, at any rate, the lachrymal bone encroaches slightly on the anterior superior portion of the 
 opening, and assists in forming the inner wall of the antrum. 
 
 - D. Kerfoot Shute, in the Reference Handbook of the Medical Sciences. 
 
THE SUPERIOR MAXILLARY BONES 109 
 
 are the posterior dental canals, transmitting the posterior dental vessels and nerves 
 to the teeth. Projecting into the floor are several conical processes, corresponding 
 to the roots of the first and second molar teeth;' in some cases the floor is per- 
 forated by the teeth in this situation. 
 
 It is from the extreme thinness of the walls of this cavity that we are enabled to explain how 
 a tumor growing from the antrum encroaches upon the adjacent parts, pushing up the floor of 
 the orbit, and displacing the eyeball, projecting inward into the nose, protruding forward on 
 to the cheek, and making its way backward into the zygomatic fossa and downward into the 
 mouth. 
 
 The Processes of the Superior Maxillae. 
 
 Malar Process (processus zygomaticus). — The malar process is a rough, trian- 
 gular eminence, situated at the angle of separation of the facial from the zygo- 
 matic surface. In front it is concave, forming part of the facial surface; behind 
 it is also concave, and forms part of the zygomatic fossa; above it is rough and 
 serrated for articulation with the malar bone; whilst below a prominent ridge 
 marks the division between the facial and zygomatic surfaces. A small part of 
 the Masseter muscle arises from this process. 
 
 Nasal Process (processus frontalis). — The nasal process is a strong, triangular 
 plate of bone, which projects upward, inward, and backward by the side of the 
 nose, forming part of its lateral boundary. Its external surface is concave, smooth, 
 perforated by numerous foramina, and gives attachment to the Levator labii 
 superioris aheque nasi, the Orbicularis palpebrarum, and Tendo oculi. Its 
 internal surface forms part of the outer wall of the nasal fossse; at its upper 
 part it presents a rough, uneven surface, which articulates with the ethmoid 
 bone, closing in the anterior ethmoidal cells; below this is a transverse ridge, the 
 superior turbinated crest (crista ethmoidalis), for articulation with the middle tur- 
 binated bone of the ethmoid, bounded below by a shallow, smooth concavity 
 which forms part of the middle meatus; below this again is the inferior turbinated 
 crest (already described), where the process joins the body of the bone. Its upper 
 border articulates with the frontal bone. The anterior border of the nasal process 
 is thin, directed obliquely downward and forward, and presents a serrated edge for 
 articulation with the nasal bone; its posterior border is thick, and hollowed into 
 a groove, the lachrjrmal groove (sulcus lacrimalis) , for the naso-lachrymal duct: of 
 the two margins of this groove, the inner one articulates with the lachrymal bone; 
 the outer one forms part of the circumference of the orbit. Just where the latter 
 joins the orbital surface is a srnall tubercle, the lachrymal tubercle; this serves as 
 a guide to the position of the lachrymal sac in the operation for fistula laclirymalis. 
 The lachrymal groove in the articulated skull is converted into a canal (canalis 
 lacrimalis) by the lachrymal bone and lachrymal process of the inferior turbin- 
 ated; it is directed downward, and a little backward and outward, is about the 
 diameter of a goose-quill, slightly narrower in the middle than at either extremity, 
 and terminates below in the inferior meatus. 'It lodges the nasal duct. 
 
 Alveolar Process (processus alveolaris). — The alveolar process is the thickest 
 and most spongy part of the bone, broader behind than in front, and excavated 
 into deep cavities for the reception of the teeth (alveoli dentales). These cavities 
 are eight in number, and vary in size and depth according to the teeth they con- 
 tain. That for the canine tooth is the deepest; those for the molars are the 
 widest, and subdivided into minor cavities by septa; those for the incisors are 
 single, but deep and narrow. The limbus alveolaris is the broad inferior margin 
 of the alveolar process. On the anterior surface are five projections correspond- 
 
 ' The number of teeth whose fangs are in relation to the floor of the antrum is variable. The antrum " may 
 extend so as to be in relation to all the teeth of the true maxilla, from the canine to the dens sapientise." (See 
 Mr. Salter on Abscess of the Antrum, in a System of Surgery, edited by T. Holmes, 2d ed., vol. iv. p. 356). 
 
110 
 
 THE SKELETON 
 
 Foramen of Stenson. 
 
 Foramen of Scarpa. 
 
 Palate process of 
 maxillary bone. 
 
 Horizontal plate 
 of palate bone 
 
 rior palatine canal. 
 
 ing to the five anterior alveoli. They are called juga alveolaria. The cavities 
 for the teeth are separated by septa inter alveolar la. "^Fhe Buccinator muscle arises 
 from the outer surface of this process as far forward as the first molar tooth. 
 
 Palate Process {processus palatinus). — The palate process, thick and strong, 
 projects horizontally inward from the inner surface of the bone. It is much thicker 
 
 in front than behind, and 
 Anterior palatine canal. forms a considerable part 
 
 of the floor of the nostril 
 and the roof of the mouth. 
 Its inferior surface (Fig. 
 72) is concave, rough and 
 uneven, contains numer- 
 ous little cavities for the 
 glands of the mucous 
 membrane, and forms 
 part of the roof of the 
 mouth. This surface is 
 perforated by niunerous 
 foramina for the passage 
 of the nutrient vessels, 
 chaimelled at the back 
 part of its alveolar bor- 
 der by a longitudinal 
 groove, sometimes a canal, 
 for the transmission of 
 the posterior palatine 
 vessels, and the great pos- 
 terior palatine nerve from 
 Meckel's ganglion, and 
 presents little depressions 
 for the lodgement of the palatine glands. When the two superior maxillae 
 bones are articulated together, a large orifice may be seen in the middle 
 line, immediately behind the incisor teeth. This is the anterior palatine fossa 
 {foramen incisivum). On examining the bottom of this fossa four canals are 
 seen : two branch off laterally to the right and left nasal fossfe, and two, one in 
 front and one behind, lie in the middle line. The former pair of these openings 
 are named the incisor foramina or foramina of Stenson; they are the openings of 
 the forking incisor canal {canalis incisiviis), through which pass the anterior or 
 terminal branches of the descending or posterior palatine arteries, which ascend 
 from the mouth to the nasal fossae, and they contain the remains of Jacobson's 
 organ. The canals in the middle line are termed the foramina of Scarpa, and 
 transmit the naso-palatine nerves, the left passing through the anterior, and the 
 right through the posterior, canal. Occasionally in adults' skulls, often in chil- 
 dren's skulls, on the palatal surface of the process a delicate linear suture may 
 sometimes be seen extending from the anterior palatine fossa to the interval 
 between the lateral incisor and the canine tooth. This marks out the inter- 
 maxillary or pre-maxillary bones or the incisive bone {os incisivum) on each side. 
 It is the portion of the upper jaw which is in front of the anterior palatine 
 foramen, and which in some animals exists permanently as a separate piece. 
 It includes the whole thickness of the alveolus, the corresponding part of the floor 
 of the nose, and the anterior nasal spine, and contains the sockets of the incisor 
 teeth. The pre-maxillary bone has a separate centre of ossification and develops 
 in association with the vertical plate of the ethmoid and the vomer. The incisive 
 bones, which are always present in the foetus, usually join the rest of the bone 
 
 1 
 
 Accessory palatine foramen. 
 Fig. 72. — The palate and alveolar arch. 
 
THE SUPERIOR MAXILLARY BONES 
 
 111 
 
 early in development, more or less well-marked sutures (sutura incisiva) indi- 
 cating the lines of union. In double hare-lip the incisive bones covered by the 
 median part of the lip are frequently not joined to the palate processes of the 
 superior maxillary bones, but are fixed to the nasal septum. Albrecht maintains 
 that instead of two intermaxillary seg- 
 ments or incisive bones, each carrying 
 two incisor teeth, there are originally 
 four, each carrying the rudiment of 
 one tooth and each of a triangular 
 
 CNDOGNATHION 
 
 SUTURE I CNOO-MESOGNATHION 
 
 SUTURE 
 MESOGNATHION 
 
 ENOOGNATHION 
 
 EXOGNATHION 
 
 CNOO-EXOGNATHION 
 SUTURE 
 
 MESO- EXOGNATHION 
 SUTURE 
 
 Fig. 73. — The pre-maxilla and its sutures. (Albrecht.) 
 
 shape, the apices approaching at the 
 anterior palatine canal. The seg- 
 ments are separated by five sutures. 
 The maxilla is called the exo-gnathion, 
 each mesial segment is called an endo- 
 gnathion, and each lateral segment 
 a meso-gnathion. In hare-lip the cleft 
 
 may l^e {)urely in the soft parts, but may pass into the nostril, the alveolar portion 
 of the maxilla, or through the palate bone (cleft palate). In hare-lip with cleft 
 palate (alveolar hare-lip) Kolliker believes that the cleft is between the maxilla and 
 the intermaxillary bone; that is, between the exo-gnathion and the meso-gnathion. 
 Albrecht is of the opinion that the cleft is between the endo-gnathion and the meso- 
 gnathion. In some cases of double hare-lip the pre-maxillary segment contains the 
 germs of four incisors, and in such a case the cleft must be between the exo- 
 gnathion and the meso-gnathion. In other cases it contains but two, and in such 
 a case the cleft must be as indicated by Albrecht, as Fergusson's explanation is 
 not in accordance with our knowledge of development. Fergusson believed that 
 if the germs of four incisors are not present the missing ones were lost in the gap. 
 The upper surface of the palate process is concave from side to side, smooth, and 
 forms part of the floor of the nose. It presents the upper orifices of the foramina of 
 
 Fig. 74. — KoUiker's theory of alveolar hare-lip. 
 (Poirier and Charpy.) 
 
 Fig. 75. — Alveolar hare-lip according to the theory of 
 Albrecht. (Poirier and Charpy.) 
 
 Stenson and Scarpa, the former being on each side of the middle line, the latter 
 being situated in the intermaxillary suture, and therefore not visible unless the two 
 bones are placed in apposition. The outer border of the palate process is incorpor- 
 ated with the rest of the bone. The inner border is thicker in front than behind, and 
 is raised above into a ridge, the nasal crest (crista nasalis), which, with the corre- 
 sponding ridge in the opposite bone, forms a groove for the reception of the vomer. 
 In front this crest rises to a considerable height, and this portion is named the incisor 
 crest. The anterior margin is bounded by the thin, concave border of the opening 
 of the nose, prolonged forward internally into a sharp process, forming, with a 
 similar process of the opposite bone, the anterior nasal spine (spina nasalis anterior). 
 The posterior border is serrated for articulation with the horizontal plate of the 
 palate bone. 
 
112 
 
 THE SKELETON 
 
 Anterior Surface. 
 
 Development. — This bone commences to ossify at a very early period, and 
 ossification proceeds in it with great rapidity, so that it is difficult to ascertain with 
 certainty its precise number of centres. It appears, however, probable that it is 
 ossified from four centres, which are deposited in membrane. 1. One which forms 
 that portion of the body of the bone which lies internal 
 to the infraorbital canal, including the floor of the orbit, 
 the outer wall of the nasal fossa, and the nasal process, 
 2. A second which gives origin to that portion of the 
 bone which lies external to the infraorbital canal and the 
 malar process. 3. A third from which is developed the 
 palatine process posterior to Stenson's canal and the ad- 
 joining part of the nasal wall. 4. And a fourth for the 
 front part of the alveolus which carries the incisor teeth 
 and corresponds to the pre-maxillary bone of the lower 
 animals. These centres appear about the eighth week, 
 and by the tenth week the three first-named centres 
 have become fused together and the bone consists of two 
 portions, one the maxilla proper, and the other the pre- 
 maxillary portion. The suture between these two por- 
 tions on the palate persists till middle life, but is not to 
 be seen on the facial surface. This is believed by Cal- 
 lender to be due to the fact that the front wall of the 
 sockets of the incisive teeth is not formed by the pre- 
 FiG. 76. — Development of maxillary bouc, but by an outgrowth from the facial part 
 
 superior maxillary bone. At „ ^, '' . .,, r^\^ i i i 
 
 birth. oi the superior maxilla. 1 he antrum appears as a shal- 
 
 low groove on the inner surface of the bone at an ear\ier 
 period than any of the other nasal sinuses, its development commencing about 
 the fourth month of f«etal life. The sockets for the teeth are formed by the 
 growing downward of two plates from the dental groove, which subsequently 
 becomes divided by partitions jutting across from the one to the other. If the 
 two palate processes fail to unite partially or completely, a partial or complete 
 cleft palate results. 
 
 Articulations. — With nine bones: two of the cranium, the frontal and ethmoid, 
 and seven of the face — viz., the nasal, malar, lachrymal, inferior turbinated, palate, 
 vomer, and its fellow of the opposite side. Sometimes it articulates with the orbital 
 plate of the sphenoid, and sometimes with its external pterygoid plate. 
 
 Attachment of Muscles. — To twelve: the Orbicularis palpebrarum, Obliquus 
 oculi inferior. Levator labii superioris aljeque nasi, I>evator labii superioris pro- 
 prius. Levator anguli oris. Compressor nasi, Depressor ahe nasi. Dilatator naris 
 posterior, Masseter, Buccinator, Internal pterygoid, and Orbicularis oris. 
 
 Inferior Surface. 
 
 CHANGES PRODUCED IN THE UPPER JAW BY AGE. 
 
 At birth and during infancy the diameter of the bone is greater in an antero-posterior than 
 in a vertical direction. Its nasal process is long, its orbital surface large, and its tuberosity 
 well marked. In the adult the vertical diameter is the greater, owing to the development of 
 the alveolar process and the increase in size of the antrum. In old age the bone approaches 
 again in character to the infantile condition: its height is diminished, and after the loss of the 
 teeth the alveolar process is absorbed, and the lower part of the bone contracted and diminished 
 in thickness. 
 
 The Lachrymal Bone (Os Lacrimale). 
 
 The lachrymal {lachryma, a tear) is the smallest and most fragile bone of 
 the face. There are two lachrymal bones. They are situated at the front part 
 of the inner wall of the orbit (Fig. 67), and resemble somewhat in form, thinness, 
 
THE MALAR BONE 113 
 
 and size a finger-nail; hence they are termed theossa unguis. Each bone presents 
 for examination two surfaces and four borders. 
 
 Surfaces. External Surface. — The external or orbital surface (Fig. 77) is divided 
 bv a vertical ridge, the lachrymal crest (crista lacrimalis posterior), into two parts. 
 The portion of bone in front of this ridge, the lachr3mial sulcus (sulcus lacrimalis), 
 presents a smooth, concave, longitudinal groove, the free margin of which unites 
 with the nasal process of the superior maxillary bone, completing the lachrymal 
 groove. The upper part of this groove (fossa sacci lacrimalis) 
 lodges the lachrymal sac; the lower part (sulcus lacrimalis) wuhfronmi. 
 
 lodges the nasal duct. The portion of bone behind the ridge 
 is smooth, slightly concave, and forms part of the inner wall 
 of the orbit. The ridge, with a part of the orbital surface 
 inmiediately behind it, affords attachment to the Tensor tarsi 
 muscle: it terminates below in a small, hook-like projection, 
 the hamular process (hamulus lacrimalis), which articulates 
 with the lachrymal tubercle of the superior maxillary bone, 
 and completes the upper orifice of the lachrymal groove. 
 It sometimes exists as a separate piece, which is then called ^^ fl^^^v, 
 the lesser lachrymal bone. in/*''"^'"" 
 
 Internal Surface. — The internal or nasal surface presents Fig. 77. — Left lachry- 
 
 , , „ !• J ,1 • 1 -i J mal bone. External sur- 
 
 a depressed furrow, correspondmg to the ridge on its outer face. (Siightiy enlarged.) 
 surface. The surface of bone in front of this forms part of 
 the middle meatus, and that behind it articulates with the ethmoid bone, fill- 
 ing in the anterior ethmoidal cells. 
 
 Borders. — Of the four borders, the anterior is the longest, and articulates with 
 the nasal process of the superior maxillary bone. The posterior, thin and uneven, 
 articulates with the os planum of the ethmoid. The superior, the shortest and 
 thickest, articulates with the internal angular process of the frontal bone. The 
 inferior is divided by the lower edge of the vertical crest into two parts; the poste- 
 rior part articulates with the orbital plate of the superior maxillary bone; the 
 anterior portion is prolonged downward into a pointed process, which articulates 
 with the lachrymal process of the inferior turbinated bone and assists in the forma- 
 tion of the lachrymal groove. 
 
 Development. — By a single centre, which makes its appearance soon after ossifi- 
 cation of the vertebrfe has commenced. 
 
 Articulations. — With four bones: two of the cranium, the frontal and ethmoid, 
 and two of the face, the superior maxillary and the inferior turbinated. 
 
 Attachment of Muscles. — To one muscle, the Tensor tarsi. 
 
 The Malar Bone (Os Zygomaticum). 
 
 The name malar is derived from mala, the cheek. The malar or yoke bone is 
 also called the cheek bone. There are two malar bones. Plach is a small, quad- 
 rangular bone, situated at the upper and outer part of the face. They form 
 the prominence of the cheek, part of the outer wall and floor of the orbit, and 
 part of the temporal and zygomatic fossa? (Fig. 78). Each bone presents for 
 examination an external and an internal surface; four processes, the frontal, 
 orbital, maxillary, anfl zygomatic processes; and four borders. 
 
 Surfaces. External or Malar Surface (fades malaris). — The external surface 
 (Fig. 79) is smooth, convex, perforated near its centre by a small aperture, the 
 malar foramen (foramen zygomaticofaciale), for the passage of nerves and vessels 
 from the orbit. The malar surface is covered by the Orbicularis palpebrarum 
 muscle, and affords attachment to the Zygomaticus major and minor muscles. 
 
 8 
 
114 
 
 THE SKELETON 
 
 Internal or Temporal Surface (fades temporalis). — The internal surface (Fig. 80), 
 directed backward and inward, is concave, presenting internally a rough, 
 triangular surface, for articulation with the superior maxillary bone; and exter- 
 nally, a smooth concave surface, which above forms the anterior boundary of 
 
 Zygoma- 
 tic proc. 
 
 Fig. 78. — Malar bone in situ. 
 
 the temporal fossa, and below, where it is wider, forms part of the zygomatic 
 fossa. This surface presents, a little above its centre, the aperture of a malar 
 canal (foramen zygomaticotemporale) , and affords attachment to a portion of the 
 Masseter muscle at its lower part. 
 
 Bristles passed 
 
 through temporo- 
 
 malar canals. 
 
 yfiih frontal. 
 
 Fig. 79. — Left malar bone. Outer surface. 
 
 Fig. 80. — Left malar bone. Inner surface. 
 
 Processes. Frontal Process (processus frontosphenoidalis).—Oi the four 
 processes, the frontal is thick and serrated, and articulates with the external 
 angular process of the frontal bone. To its orbital margin is attached the 
 
 external tarsal ligament. 
 
 Orbital Process. — The orbital process is a thick and strong plate, which projects 
 backward from the orbital margin of the bone. Its supero-internal surface (fades 
 
 1 
 
THE PALATE BONE 115 
 
 orbitalis), smooth and concave, forms, by its junction with the orbital surface of the 
 superior maxillary bone and with the great wing of the sphenoid, part of the floor 
 and outer wall of the orbit. Its infero-external surface, smooth and convex, forms part 
 of the zygomatic and temporal fossa?. Its anterior marcjin is smooth and rounded, 
 forming part of the circumference of the orbit. Its superior margin, rough and 
 directed horizontally, articulates with the frontal bone behind the external angular 
 process. Its posterior margin is rough and serrated for articulation with the 
 sphenoid; internally it is also serrated for articulation with the orbital surface of 
 the superior maxillary. At the angle of junction of the sphenoidal and maxillary- 
 portions a short, rounded, non-articular margin is generally seen; this forms the 
 anterior boundary of the spheno-maxillary fissure: occasionally no such non- 
 articular margin exists, the fissure being completed by the direct junction of the 
 maxillary and sphenoid bones or by the interposition of a small Wormian bone in 
 the angular interval between them. On the upper surface of the orbital process 
 are seen a single or double temporo -malar foramen {foramen zygoTnaticoorhitale), 
 the entrance of the temporo-malar canal. This canal may be bifurcated, or 
 there may be two canals from the beginning; one of these usually opens on the 
 posterior surface, the other (occasionally two) on the facial surface: they transmit 
 filaments (temporo-malar) of the orbital branch of the superior maxillary nerve. 
 
 Maxillary Process. — The maxillary process is a rough, triangular surface which 
 articulates with the malar process of the superior maxillary bone. 
 
 Zygomatic Process (processus temporalis). — The zygomatic process, long, narrow, 
 and serrated, articulates with the zygomatic process of the temporal bone. 
 
 Borders. — Of the four borders, the antero- superior or orbital border is smooth, 
 arched, and forms a considerable part of the circumference of the orbit. The 
 antero-inferior or maxillary border is rough, and bevelled at the expense of its 
 inner ta})le, to articulate with the superior maxillary bone; affording attachment 
 by its margin to the Levator labii superioris proprius, just at its point of junction 
 with the superior maxillary. The postero-superior or temporal border, curved like 
 an italic letter /, is continuous above with the commencement of the temporal 
 ridge ; below, with the upper border of the zygomatic arch : it affords attachment 
 to the temporal fascia. The poster o-inferior or zygomatic border is continuous 
 with the lower border of the zygomatic arch, affording attachment by its rough 
 edge to the Masseter muscle. 
 
 Development. — The malar bone ossifies generally from three centres, which 
 appear about the eighth week — one for the zygomatic and two for the orbital 
 portion — and fuse about the fifth month of fcetal life. The bone is sometimes, 
 after birth, seen to be divided by a horizontal suture into an upper and larger 
 and a lower and smaller division. In some quadrumana the malar bone consists 
 of two parts, an orbital and a malar, which are ossified by separate centres. 
 
 Articulations. — With four bones: three of the cranium, frontal, sphenoid, and 
 temporal; and one of the face, the superior maxillary. 
 
 Attachment of Muscles. — To four: the Levator labii superioris proprius, 
 Zygomaticus major and minor, and Masseter. 
 
 The Palate Bone (Os Palatinum). 
 
 The palate bones {palatum, the palate) are situated at the back part of the 
 nasal fossse: they are wedged in between the superior maxillary bones and the 
 pterygoid processes of the sphenoid (Fig. 81). Each bone assists in the formation 
 of three cavities: the floor and outer wall of the nose, the roof of the mouth, and 
 the floor of the orbit, and enters into the formation of two fossje, the spheno- 
 maxillary {fossa pterygopalatina) and pterygoid fossae {fossa pterygoidea) ; and one 
 fissure, the spheno-maxillary fissure {fissura orbitalis inferior). In form the palate 
 
116 
 
 THE SKELETON 
 
 bone somewhat resembles the letter L, and may be divided into an inferior or 
 horizontal plate and a superior or vertical plate. 
 
 Orbital process. 
 
 Spheno-palatine for. 
 
 Sphenoidal process 
 
 Sup. turbinated crest 
 
 Inf. turbi7iated crest. 
 
 Nasal process. 
 
 Sup. turbinated crest. 
 
 Inf. turbinated crest. 
 
 — 'Ant. nasal spine. 
 
 Fig. 81. — Palate bone in silu. 
 
 The Horizontal Plate of the Palate Bone (Pars Horizcntalis) (Fig. 83). 
 
 The horizontal plate is of a quadrilateral form, and presents two surfaces and 
 four borders. 
 
 Surfaces. Superior Surface (fades nasalis). — The superior or nasal surface, 
 concave from side to side, forms the back part of the floor of the nasal cavity. 
 
 Inferior Surface [jades palatina). — The inferior or palatine surface, slightly 
 concave and rough, forms the back part of the hard palate. At its posterior part 
 may be seen a transverse ridge, more or less marked, for the attachment of part 
 of the aponeurosis of the Tensor palati muscle. At the outer extremity of this 
 ridge is a deep groove, the pterygopalatine groove (sulcus pterygopalatinus), 
 converted into a canal by its articulation with the tuberosity of the superior 
 maxillary bone, and forming the lower end of the posterior palatine canal (canalis 
 pterygopalatinus) , the opening of which is called the great palatine foramen (fora- 
 men palatinum majus). Near this groove the orifices (foramiria palatina minora) 
 of one or two small canals, accessory posterior palatine canals (canales palatini) 
 may be seen. Through the posterior palatine canal emerge the descending 
 palatine artery and the great posterior palatine nerve. 
 
 Borders. — The anterior border is serrated, bevelled at the expense of its inferior 
 surface, and articulates with the palate process of the superior maxillary bone. 
 The posterior border is concave, free, and serves for ,the attachment of the soft 
 palate. Its inner extremity is sharp and pointed, and, when united with the 
 opposite bone, forms a projecting process, the posterior nasal or palatine spine 
 (spina nasalis posterior), for the attachment of the Azygos uvulfe muscle. The 
 external border is united with the lower part of the perpendicular plate almost 
 at right angles. The internal border, the thickest, is serrated for articulation with 
 its fellow of the opposite side; its superior edge is raised into a ridge, which, united 
 with the opposite bone, forms a crest (crista nasalis) into which the vomer is 
 received. 
 
THE PALATE BONE 
 
 117 
 
 Orbital process. 
 
 Orhiud surface. 
 
 Maxillary surface. 
 
 Superior meatus. 
 Spheno-palatine foramen.-^ 
 
 ■^ Maxillary 
 process. 
 
 The Vertical or Perpendicular Plate of the Palate Bone (Pars Perpendicularis). 
 
 The vertical or perpendicular plate (Figs. 82 and 83) is thin, of an oblong 
 form, and directed upward and a little inward. It presents two surfaces, an 
 external and an internal, and four borders. 
 
 Surfaces. Internal, Medial, or Nasal Surface (fades nasalis). — The internal sur- 
 face presents at its lower part a broad, shallow depression, which forms part of 
 the inferior meatus of the nose. 
 Immediately above this is a 
 well-marked horizontal ridge, 
 the inferior turbinated crest 
 (crista conchalis), for articula- 
 tion with the inferior turbin- 
 ated bone; above this, a second 
 broad, shallow depression, 
 which forms part of the mid- 
 dle meatus, surmounted above 
 by a horizontal ridge less 
 prominent than the inferior, 
 the superior turbinated crest 
 (crista ethmoidalis) , for articu- 
 lation with the middle turbin- 
 ated bone. Above the superior 
 turbinated crest is a narrow, 
 horizontal groove, which forms 
 part of the superior meatus. 
 
 External, Lateral, or Maxillary 
 Surface (fades maxillaris) . — 
 The external surface is rough and irregular throughout the greater part of its extent, 
 for articulation with the inner surface of the superior maxillary bone, its upper 
 
 and back part being smooth where it enters 
 into the formation of the spheno-maxillary 
 fossa; it is also smooth in front, where it 
 covers the orifice of the antrum. Toward 
 the back part of this surface is a deep 
 groove, the pterygo -palatine groove, converted 
 into a canal, the posterior palatine canal, by 
 its articulation with the superior maxillary 
 bone. It transmits the posterior or descend- 
 ing palatine vessels and the great posterior 
 palatine nerve from Meckel's ganglion. 
 
 Borders. Anterior Border (Fig. 82).— The 
 anterior border is thin, irregular, and pre- 
 sents opposite the inferior turbinated crest 
 a pointed, projecting lamina, the maxillary 
 process (processus maxillaris), which is di- 
 rected forward, and closes in the lower and 
 back part of the opening of the antrum. 
 
 Posterior Border. — The posterior border 
 
 (Fig. S3) presents a deep groove, the edges 
 
 of which are serrated for articulation with 
 
 the pterygoid process of the sphenoid. At the lower part of this border is seen a 
 
 pyramidal process of bone, the pterygoid process or tuberosity of the palate (processus 
 
 pyramidalis) , which is received into the angular interval between the two pterygoid 
 
 Horizontal Plate. 
 
 Fig. 82. — Left palate bone. Internal view. (Enlarged.) 
 
 Orbital process, 
 , surface. 
 
 ^Sphenoidal palatine 
 foramen. 
 
 js. ^ Sphenoidal process. 
 / Y~ 'Artic^llar portion, 
 ii on-articular portion. 
 
 ""ill/. 
 
 Fig. 83.— Left palate bone. 
 (Enlarged.) 
 
 External Surface. 
 
 Posterior 
 . nasal spine. 
 
 Horizontal 
 
 Plate. 
 
 Posterior view. 
 
118 THE SKELETON 
 
 plates of the sphenoid at their inferior extremity. This process presents at its back 
 part a median groove and two lateral surfaces. The groove is smooth, and forms 
 part of the pterygoid fossa, affording attachment to the Internal pterygoid muscle; 
 whilst the lateral surfaces are rough and uneven, for articulation with the anterior 
 border of each pterygoid plate, A few fibres of the Superior constrictor arise from 
 the tuberosity of the palate bone. The base of this process, continuous with the 
 horizontal portion of the bone, presents the aperture of the accessory descending 
 palatine canals, through which pass the two smaller descending branches of 
 Meckel's ganglion ; whilst its outer surface is rough for articulation with the 
 inner surface of the body of the superior maxillary bone. 
 
 Superior Border. — The superior border of the vertical plate presents two well- 
 marked processes separated by an intervening notch or foramen. The anterior, 
 or larger, is called the orbital process; the posterior, the sphenoidal process. 
 
 Processes. Orbital Process {processus orbitalis). — The orbital process, directed 
 upward and outward, is placed on a higher level than the sphenoidal. It presents 
 five surfaces, which enclose a hollow cellular cavity, and is connected with the per- 
 pendicular plate by a narrow, constricted neck. Of these five surfaces, three are 
 articular, two non-articular or free surfaces. The three articular are the anterior or 
 maxillary surface, which is directed forward, outward, and downward, is of an 
 oblong form, and rough for articulation with the superior maxillary bone. The pos- 
 terior or sphenoidal surface is directed backward, upward, and inward. It ordinarily 
 presents a small, open cell, the orbital sinus {sinus orbitalis) , which communicates 
 with the sphenoidal cells, and the margins of which are serrated for articulation with 
 the vertical part of the sphenoidal turbinated bone. " The orbital may connnunicate 
 not only with the sphenoidal sinus and the ethmoidal cells, but, in rare instances, 
 with the maxillary antrum."^ The internal or ethmoidal surface is directed inward, 
 upward, and forward, and articulates with the lateral mass of the ethmoid bone. 
 In some cases the cellular cavity opens on the internal surface of the bone; it then 
 communicates with the posterior ethmoidal cells. More rarely it opens on both 
 surfaces, and then communicates v/ith both the posterior ethmoidal and the 
 sphenoidal cells. The non-articular or free surfaces are the superior or orbital 
 surface, directed upward and outward, of triangular form, concave, smooth, and 
 forming the back part of the floor of the orbit ; and the external or zygomatic surface, 
 directed outward, backward, and downward, of an oblong form, smooth, lying in 
 the spheno-maxillary fossa, and looking into the zygomatic fossa. The latter 
 surface is separated from the orbital by a smooth, rounded border, which enters 
 into the formation of the spheno-maxillary fissure. 
 
 Sphenoidal Process {processus sphenoidalis) . — The sphenoidal process of the 
 palate bone is a thin, compressed plate, much smaller than the orbital, and 
 directed upward and inward. It presents three surfaces and two borders. The 
 superior surface, the smallest of the three, articulates with the under surface of 
 the sphenoidal turbinated bone; it presents a groove, which contributes to the 
 formation of the pterygo-palatine canal. The internal surface is concave, and 
 forms part of the outer wall of the nasal fossa. The external surface is divided 
 into an articular and a non-articular portion: the former is rough, for articulation 
 with the inner surface of the internal pterygoid plate of the sphenoid; the latter is 
 smooth, and forms part of the spheno-maxillary fossa. The anterior border forms 
 the posterior boundary of the spheno-palatine notch. The posterior border, 
 serrated at the expense of the outer table, articulates with the inner surface of 
 the internal pterygoid plate. 
 
 The orbital and sphenoidal processes are separated from one another by a deep 
 notch, the spheno-palatine notch {incisura sphenopalatinum) , which is converted 
 
 1 Dr. D. Kerfoot Shute, in the Reference Handbook of the Medical Sciences. 
 
THE INFERIOR TURBINATED BONE 
 
 119 
 
 into a foramen, the spheno-palatine foramen {foramen sphenopalatinwn) , by articu- 
 lation with the under surface of the body of the sphenoid bone. Sometimes the 
 two processes are united above, and form between them a complete foramen (Figs. 
 82 and 83) , or the notch is crossed by one or more spicuUe of bone, so as to form 
 two or more foramina. In the articulated skull this foramen is seen to pass from 
 the spheno-maxillary fossa into the back part of the superior meatus. It trans- 
 mits the spheno-palatine vessels and the superior nasal and naso-palatine nerves. 
 
 Development. — From a single centre, which makes its appearance about the 
 second month at the angle of junction of the two plates of the bone. From this 
 point ossification spreads inward to the horizontal plate, downward into the 
 tuberosity, and upward into the vertical plate. In the foetus the horizontal plate 
 is much larger than the vertical, and even after it is fully ossified the whole bone 
 is at first remarkable for its shortness. 
 
 Articulations. — With six bones: the sphenoid, ethmoid, superior maxillary, 
 inferior turbinated, vomer, and opposite palate. 
 
 Attachment of Muscles.- -To four: the Tensor palati, Azygos uvulae, Internal 
 pterygoid, and Superior constrictor of the pharynx. 
 
 The Inferior Turbinated Bone (Concha Nasalis Inferior). 
 
 The inferior turbinal or turbinated bones (turbo, a whirl) are situated one on 
 each side of the outer wall of the nasal fossae. Each inferior turbinated bone 
 (concha nasalis inferior) consists of a layer of thin, spongy bone, curled upon 
 
 NASO-PHARYNGEAU 
 MEATUS 
 
 Fig. 84. — Nasal cavity, right lateral wall, from the left. (Spalteholz.) 
 
 itself like a scroll — hence its name "turbinated" — and extends horizontally 
 along the outer wall of the nasal fossa, immediately below the orifice of the 
 antrum (Fig. 84). Each bone presents two surfaces, two borders, and two 
 extremities. 
 
120 
 
 THE SKELETON 
 
 Surfaces. — The internasal surface (Fig. 85) is convex, perforated by numerous 
 apertures, and traversed by longitudinal grooves and canals for the lodgement 
 of arteries and veins. In the recent state it is covered by the lining membrane of 
 the nose. The external surface is concave (Fig. 86), and forms part of the inferior 
 meatus. 
 
 Fig. 85. — Right inferior turbinated bone, 
 surface. 
 
 Internal 
 
 Fig. 86. 
 
 -Right inferior turbinated bone. 
 External surface. 
 
 Borders. — Its upper border is thin, irregular, and connected to various bones 
 along the outer wall of the nose. It may be divided into three portions : of these, 
 the anterior articulates with the inferior turbinated crest of the superior maxillary 
 bone; the posterior with the inferior turbinated crest of the palate bone; the middle 
 portion of the superior border presents three well-marked processes, which vary 
 much in their size and form. Of these, the anterior and smallest is situated at 
 the junction of the anterior fourth with the posterior three-fourths of the bone: 
 it is small and pointed, and is called the lachrymal process (processus lacrimalis) ; 
 it articulates by its apex with the anterior inferior angle of the lachrymal bone, 
 and by its margins with the groove on the back of the nasal process of the supe- 
 rior maxillary, and thus assists in forming the canal for the nasal duct. At the 
 junction of the two middle fourths of the bone, but encroaching on its posterior 
 fourth, a broad, thin plate, the ethmoidal process (processus ethmoidalis) , ascends 
 to join the unciform process of the ethmoid; from the lower border of this pro- 
 cess a thin lamina of bone curves downward and outward, hooking over the 
 lower edge of the orifice of the antrum, which it narrows below: it is called the 
 maxillary process (processus maxillaris), and fixes the bone firmly to the outer wall 
 of the nasal fossa. The inferior border is free and thick, more especially in the 
 middle of the bone. Bone extremities are more or less narrow and pointed, the 
 posterior being the more tapering. If the bone is held so that its outer concave 
 surface is directed backward (i. e., toward the holder), and its superior border, from 
 which the lachrymal and ethmoidal processes project, upward, the lachrymal pro- 
 cess will be directed to the side to which the bone belongs.^ In a study of 1000 speci- 
 mens, Howard A. Lothrop^ did not discover cells in the inferior turbinated bone. 
 
 Development. — By a single centre, which makes its appearance about the 
 middle of foetal life. 
 
 Articulations.^ With four bones: one of the cranium, the ethmoid, and three 
 of the face, the superior maxillary, lachrymal, and palate. 
 
 No muscles are attached to this bone. 
 
 The Vomer (Ploughshare Bone). 
 
 The vomer (vomer, a ploughshare) is a single bone, situated vertically at the 
 back part of the nasal fossae, forming part of the septum of the nose (Fig. 87). 
 It is thin, somewhat like a ploughshare in form; but it varies in different indi- 
 viduals, being frequently bent to one or the other side; it presents for examination 
 two surfaces and four borders. 
 
 If the lachrymal process is broken off, as is often the case, the side to which the bone belongs may be known 
 by recollecting that the maxillary process is nearer the back than the front of the bone. 
 - Annals of Surgery, May, 1903. 
 
THE VOMER 
 
 121 
 
 Surfaces. — The lateral surfaces are smooth, marked by small furrows for the 
 lodgement of blood-vessels, and })y a groove on each side, sometimes a canal, the 
 naso-palatine groove or canal, which runs obliquely downward and forward to the 
 intermaxillary suture; it transmits the naso-palatine nerve. 
 
 Frontal sinuses. 
 
 Sphenoidal sinuses. 
 
 Perpendicnlar 
 plute of eth- 
 moid. 
 
 Space for triangular 
 cartilage of septum, 
 
 Vomer. 
 
 Rostrum of sphenoid. 
 Palate process. 
 Int. pterygoid plate. 
 
 Fig. 87. — Vomer in situ. 
 
 Borders. — The superior border, the thickest, presents a deep groove, bounded 
 on each side by a horizontal projecting leaf of bone; these leaves are the alae 
 (alcB vomeris). The groove formed by the a\se receives the rostrum of the 
 sphenoid, while the alse are overlapped and retained by the vaginal processes, which 
 project from the under surface of the body of the sphenoid at the base of the 
 pterygoid processes. At the front 
 of the groove a fissure is left for 
 the transmission of blood-vessels 
 to the substance of the bone. The 
 inferior border, the longest, is 
 broad and imeven in front, where 
 it articulates with the two supe- 
 rior maxillary bones ; thin and 
 sharp behind, where it joins with 
 the palate bones. The upper \s; 
 half of the anterior border usually ^^ ^ 
 
 With sup. maxill. hones and palate. 
 
 Fig. 88. — The vomer. 
 
 consists of two laminae of bone, 
 
 in the groove between which is 
 
 received the perpendicular plate 
 
 of the ethmoid; the lower half, 
 
 also separated into two lamellae, receives between them the lower margin of the 
 
 septal cartilage of the nose. The posterior border is free, concave, and separates 
 
 the nasal fossae behind. It is thick and bifid above, thin below. 
 
 The surfaces of the vomer are covered by mucous membrane, which is inti- 
 mately connected with the periosteum, with the intervention of very little, if any, 
 
122 
 
 THE SKELETON 
 
 submucous connective tissue. Hence polypi are rarely found growing from this 
 surface, though they frequently grow from the outer wall of the nasal fossae, 
 where the submucous tissue is abundant. 
 
 Development. — The vomer at an early period consists of two laminae, separated 
 by a very considerable interval, and enclosing between them a plate of cartilage, 
 the vomerine cartilage, which is prolonged forward to form the remainder of the 
 septum. Ossification commences in the membrane at the postero-inferior part of 
 this cartilage by two centres, one on each side of the middle line, which extend 
 to form the two laminje. They begin to coalesce at the lower part, but their 
 union is not complete until after puberty. 
 
 Articulations.- -With 5ix bones: two of the cranium, the sphenoid and ethmoid; 
 and four of the face, the superior maxillary and the two palate bones; and with 
 the cartilage of the septum. 
 
 The vomer has no muscles attached to it. 
 
 The Maxillary Bone, Inferior Maxilla, Mandible or Lower Jaw (Mandibula) . 
 
 The mandible, the largest and strongest bone of the face, serves for the 
 reception of the lower teeth. It consists of a curved, horizontal portion, the 
 body, and two perpendicular portions, the rami, which join the back part of 
 the body nearly at right angles. 
 
 The Horizontal Portion or Body of the Mandible (Corpus Mandibulse). 
 
 The horizontal portion or body (Fig. 89) is convex in its general outline, and 
 curved somewhat like a horseshoe. It presents for examination two surfaces and 
 two borders. 
 
 Coronoid process. Condyle. 
 
 Mental, 
 process 
 
 Groove for facial artery. 
 Fig. 89. — The mandible. Outer surface. Side view. 
 
 Surfaces. External Surface. — The external surface is convex from side to side, 
 concave from above downward. In the median line is a vertical ridge, the symphy- 
 sis, which extends from the upper to the lower border of the bone, and indicates 
 the point of junction of the two pieces of which the bone is composed at an early 
 period of life. The lower part of the ridge terminates in a prominent triangular 
 eminence, the mental process or protuberance (protuberantia mentalis) . This emi- 
 nence is rounded below, and often presents a median depression separating two 
 processes, the mental tubercles (tubera meritalia). It forms the chin, a feature 
 peculiar to the human skull. On either side of the symphysis, just below the 
 
THE 3£AXILLAIiY BONE 
 
 123 
 
 cavities for the incisor teeth, is a depression, the incisive or incisor fossa, for the 
 attachment of the Levator menti (or Levator labii inferioris) ; more externally is 
 attached a portion of the Orbicularis oris (accessorii orbicularis inferioris), and, 
 still more externally, a foramen, the mental foramen (foramen mentale), for the 
 passage of the mental vessels and nerve. This foramen is placed just below the 
 interval between the two bicuspid teeth. Running outward from the base of the 
 mental process on each side is a ridge, the external oblique line (linea obliqua). 
 The ridge is at first nearly horizontal, but afterward inclines upw^ard and back- 
 ward, and is continuous with the anterior border of the ramus : it affords attach- 
 ment to the Depressor labii inferioris and Depressor anguli oris; below it the 
 Platysma myoides is attached. 
 
 Internal Surface.- — The internal surface (Fig. 90) is concave from side to side, 
 convex from above downward. In the middle line is an indistinct linear depres- 
 
 QENIO-HYO-QLOSS 
 
 QENIO-HYOIOEUS. 
 
 Mylo-hyoid ridge. 
 
 Body. 
 
 Fig. 90. — The mandible. Inner surface. Side view. 
 
 sion, corresponding to the symphysis externally; on either side of this depression, 
 just below its centre, are four prominent tubercles, placed in pairs, two above and 
 two below; they are called the genial tubercles or mental spines (spinoB mentales) , and 
 afford attachment, the upper pair to the Genio-hyo-glossi, the lower pair to the 
 Genio-hyoidei, muscles. Sometimes the tubercles on each side are blended into 
 one; at others they all unite into an irregular eminence; or, again, nothing but an 
 irregularity may be seen on the surface of the bone at this part. On either side of 
 the genial tubercles is an oval depression, the sublingual fossa {fovea sublingualis) , 
 for lodging the sublingual gland; and beneath the fossa a rough depression on 
 each side which gives attachment to the anterior belly of the Digastric muscle, 
 the digastric fossa (fossa digastrica) . At the back part of the sublingual fossa the 
 internal oblique line or mylo-hyoid ridge (linea mylohyoidea) commences; it is at 
 first faintly marked, but becomes more distinct as it passes upward and outward, 
 and is especially prominent opposite the last two molar teeth; it affords attach- 
 ment throughout its whole extent to the Mylohyoid muscle; the Superior con- 
 strictor of the pharynx with the pterygo-m axillary ligament being attached above 
 its posterior extremity, near the alveolar margin. The portion of the bone above 
 this ridge is smooth and covered by the mucous membrane of the mouth; the 
 portion below presents an oblong depression, the submaxillary fossa (fovea sub- 
 maxillaris) , wider behind than in front, for the lodgement of the submaxillary 
 
124 THE SKELETON 
 
 gland. The external oblique line and the internal or mylo-hyoidean line divide 
 the body of the bone into a superior or alveolar and an inferior or basilar portion. 
 Borders. — The superior or alveolar 'portion of the body {jpars alveolaris] has 
 above a narrow border which is wider and the margins of which are thicker 
 behind than in front. Its narrow margin is called the limbus alveolaris. It is 
 hollowed into numerous cavities {alveoli dentales) , for the reception of the teeth ; 
 these cavities are sixteen in number, and vary in depth and size according to the 
 teeth which they contain. The cavities are separated from one another by septa 
 interalveolaria. The juga alveolaria are prominences on the outer surface over the 
 three front alveoli. To the outer side of the alveolar border the Buccinator muscle 
 is attached upon the buccinator crest (crista huccinatoria) as far forward as the 
 first molar tooth. The inferior or basilar portion (basis mandibulcB) is rounded, 
 longer than the superior, and thicker in front than behind; it presents a shallow 
 groove, just where the body joins the ramus, over which the facial artery turns. 
 
 The Perpendicular Portions or Rami of the Mandible (Rami Mandibulae). 
 
 The perpendicular portions or rami are of a quadrilateral form. Each presents 
 for examination two surfaces, four borders, and two processes. 
 
 Surfaces. External Surface. — The external surface is flat, marked with ridges, 
 and gives attachment throughout nearly the whole of its extent to the Masseter 
 muscle. 
 
 Internal Surface. — The internal surface presents about its centre an oblique 
 foramen (foramen mandibulare) of the inferior dental canal (canalis mandibuloe) , for 
 the passage of the inferior dental vessels and nerve. The margin of this opening 
 is irregular; it presents in front a prominent ridge, surmounted by a sharp spine, 
 the lingula (lingula mandibuloe), which gives attachment to the internal lateral 
 ligament of the lower jaw, and at its lower and back part a notch leading to 
 a groove, the mylo-hyoidean groove (sulcus mylohyoideus) , which runs obliquely 
 downward to the back part of the submaxillary fossa, and lodges the mylo-hyoid 
 vessels and nerve. Behind the groove is a rough surface, for the insertion of the 
 Internal pterygoid muscle. The inferior dental canal runs obliquely downward 
 and forward in the substance of the ramus, and then horizontally forward in the 
 body; it is here placed under the alveoli, with which it communicates by small 
 openings. On arriving at the incisor teeth, it turns back to communicate with 
 the mental foramen, giving off two small canals, which run forward, to be lost in 
 the cancellous tissue of the bone beneath the incisor teeth. This canal, in the 
 posterior two-thirds of the bone, is situated nearer the internal surface of the 
 jaw; and in the anterior third, nearer its external surface. Its walls are com- 
 posed of compact tissue at either extremity, and of cancellous in the centre. It 
 contains the inferior dental vessels and nerve, from which branches are distributed 
 to the teeth through small apertures at the bases of the alveoli. 
 
 Borders. — The lower border of the ramus is thick, straight, and continuous 
 with the body of the bone. At its junction with the posterior border is the angle 
 of the jaw (angulus inandibulce). The outer portion of the angle is called the 
 gonion. The angle is either inverted or everted, and marked by rough, oblique 
 ridges on each side, for the attachment of the Masseter externally, and the 
 Internal pterygoid internally; the stylo-maxillary ligament is attached to the angle 
 between these muscles. The anterior border is thin above, thicker below, and 
 continuous with the external oblique line. The posterior border is thick, 
 smooth, rounded, and covered by the parotid gland. The upper border of the 
 ramus is thin, and presents two processes, separated by a deep concavity, the 
 sigmoid notch (incisura mandibuloe). Of these processes, the anterior is the 
 coronoid, the posterior the condyloid. 
 
THE MAXILLARY BONE 125 
 
 Coronoid Process (processus coronoideus) . — The coronoid process is a thin, flat- 
 tened, triangular eminence of bone, which varies in shape and size in different 
 subjects, and serves chiefly for the attachment of the Temporal muscle. Its external 
 surface is smooth, and aftbrds attachment to the Temporal and Masseter muscles. 
 Its internal surface gives attachment to the Temporal muscle and presents the 
 commencement of a longitudinal ridge, which is continued to the posterior part 
 of the alveolar process. On the outer side of this ridge is a deep groove, con- 
 tinued below on the outer side of the alveolar process; this ridge and part of the 
 groove afford attachment, above, to the Temporal; below, to the Buccinator 
 muscle. 
 
 Condyloid Process (processus condyloideus) . — The condyloid process, shorter but 
 thicker than the coronoid, consists of two portions: the condyle (capitulum man- 
 dibulcB), and the constricted portion which supports the condyle, the neck (collum 
 mandihulw). The condyle is of an oblong form, its long axis being transverse, and 
 set obliquely on the neck in such a manner that its outer end is a little more 
 forward and a little higher than its inner. It is convex from before backward 
 and from side to side, the articular surface extending farther on the posterior 
 than on the anterior aspect. At its outer extremity is a small tubercle for the 
 attachment of the external lateral ligament of the temporo-mandibular joint. 
 The neck of the condyle is flattened from before backward, and strengthened 
 by ridges which descend from the fore part and sides of the condyle. Its lateral 
 margins are narrow, the external one giving attachment to part of the external 
 lateral ligament. Its posterior surface is convex; its anterior is hollowed out on 
 its inner side by a depression, the pterygoid depression (fovea pterygoidea) , for the 
 attachment of the External pterygoid muscle. 
 
 The Sigmoid Notch (incisura mandibidoe) , separating the two processes, is a 
 deep semilunar depression, crossed by the masseteric vessels and nerve. 
 
 Development. — The lower jaw is developed principally from membrane, but 
 partly from cartilage. The process of ossification commences early — earlier than 
 in any other bone except the clavicle. The greater part of the bone is formed from 
 a centre of ossification (dentary), which appears between the fifth and sixth week 
 in the membrane on the outer surface of Meckel's cartilage. A second centre 
 (splenial) appears in the membrane on the inner surface of the cartilage, and 
 from this centre the inner wall of the sockets of the teeth is formed; this termi- 
 nates above in the lingula. The anterior extremity of INleckel's cartilage becomes 
 ossified, forming the body of the bone on each side of the symphysis. Two supple- 
 mental patches of cartilage appear at the condyle and at the angle, in each of 
 which a centre of ossification for these parts appears; the coronoid process is also 
 ossified from a separate centre. At birth the bone consists of two halves, united 
 by a fibrous symphysis, in which ossification takes place during the first year. 
 
 Articulation. — With the glenoid fossae of the two temporal bones. 
 
 Attachment of Muscles. ^ — To fifteen pairs: to its external surface, commencing 
 at the symphysis, and proceeding backward : Levator menti, Depressor labii infe- 
 rioris, Depressor anguli oris, Platysma myoides. Buccinator, Masseter; a portion 
 of the Orbicularis oris fAccessorii orbicularis inferioris) is also attached to this 
 surface. To its internal surface, commencingat the same point : Genio-hyo-glossus, 
 Genio-hyoideus, Mylo-hyoideus, Digastric, Superior constrictor. Temporal, Inter- 
 nal pterygoid. External pterygoid. 
 
 CHANGES PRODUCED IN THE LOWER JAW BY AGE. 
 
 The changes which the lower jaw undergoes after birth relate (1) to the alterations effected 
 in the body of the bone by the first and second dentitions, the loss of the teeth in the aged, and 
 the subsequent absorption of the alveoli; (2) to the size and situation of the dental canal; and 
 (3) to the angle at which the ramus joins with the^ody. 
 
126 
 
 THE SKELETON 
 
 Side View of the Lower Jaw at Different Periods of Life. 
 
 At birth (Fig. 91 ) the bone consists of lateral halves, united by fibrous tissue. The body is 
 a mere shell of bone, containing the sockets of the two incisor, the canine, and the two tem- 
 porary molar teeth, imperfectly partitioned from one another. The dental canal is of large size, 
 and runs near the lower border of the bone, the mental foramen opening beneath the socket of 
 the first molar. The angle is obtuse (175 degrees), and the condyloid portion nearly in the 
 same horizontal line with the body; the neck of the condyle is short, and bent backward. The 
 coronoid process is of comparatively large size, and situated at right angles with the rest of 
 the bone. 
 
 Fig. 91. — Lower jaw bone in newborn. (Spalteholz.) 
 
 Fig. 92.- 
 
 -In child six to seven years of age. 
 (Spalteiiolz.) 
 
 After birth (Fig. 92) the two segments of the bone become joined at the symphysis, from 
 below upward, in the first year; but a trace of separation may be visible in the beginning of the 
 second year near the alveolar margin. The body becomes elongated in its whole length, but 
 more especially behind the mental foramen, to provide space for the three additional teeth 
 developed in this part. The depth of the body becomes greater, owing to increased growth of 
 the alveolar part, to afford room for the fangs of the teeth, and by thickening of the subdental 
 portion, which enables the jaw to withstand the powerful action of the masticatory muscles; but 
 the alveolar portion is the deeper of the two, and, consequently, the chief part of the body lies 
 above the oblique line. The dental canal after the second dentition is situated just above the 
 level of the mylo-hyoid ridge, and the mental foramen occupies the position usual to it in the 
 adult. The angle becomes less obtuse, owing to the separation of the jaws by the teeth. (About 
 the fourth year it is 140 degrees.) 
 
 Fig. 93.— In the adult. (Spalteholz.) 
 
 In the adult (Fig. 93) the alveolar and basilar portions of the body are usually of equ^l 
 depth. The mental foramen opens midway between the upper and lower border of the bone, 
 
THE SUTURES 127 
 
 and the dental canal runs nearly parallel with the mylo-hyoid line. The ramus is almost vertical 
 in direction, and joins the body nearly at right angles. 
 
 In old age (Fig. 94) the bone becomes greatly reduced in size; for with the loss of the teeth 
 the alveolar process is absorbed, and the basilar part of the bone alone remains, consequently, 
 
 Fig. 94. — In old age. (Spalteholz.) 
 
 the chief part of the bone is heloio the oblique line. The dental canal, with the mental foramen 
 opening from it, is close to the alveolar border. The rami are oblique in direction, the angle 
 obtuse, and the neck of the condyle more or less bent backward. 
 
 The Sutures. 
 
 The bones of the cranium and face are connected to each other by means of 
 sutures. That is, the articulating surfaces or edges of the bones are more or less 
 roughened or uneven, and are closely adapted to each other, a small amount of 
 intervening fibrous tissue, the sutural ligament, fastening them together. The 
 cranial sutures may be divided into three sets: 1. Those at the vertex of the 
 skull. 2. Those at the side of the skull. 3. Those at the base. 
 
 The sutures at the vertex of the skull are four: the metopic, the sagittal, the 
 coronal, and the lambdoid. 
 
 The Metopic or Frontal Suture {sutura frontalis) is usually noted in adults as a 
 trivial fissure, just above the glabella. At birth the two halves of the frontal 
 bone are separated by the suture. This suture is, as a rule, almost completely 
 or completely closed during the fifth or sixth year, but occasionally it remains 
 intact (in about 8 per cent, of Europeans according to Prof. Cunningham). 
 
 The Interparietal or Sagittal Suture (sutura sagittalis) is formed by the junction 
 of the two parietal bones, and extends from the middle of the frontal bone back- 
 ward to the superior angle of the occipital. This suture is sometimes perforated, 
 near its posterior extremity, by the parietal foramen ; and in front, where it joins 
 the coronal suture, a space is occasionally left which encloses a large Wormian 
 bone. 
 
 The Fronto -parietal or Coronal Suture {sutura coronalis) extends transversely 
 across the vertex of the skull, and connects the frontal with the parietal bones. 
 It commences at the extremity of the greater wing of the sphenoid on one side, 
 and terminates at the same point on the opposite side. The dentations of the 
 suture are more marked at the sides than at the summit, and are so constructed 
 that the frontal rests on the parietal above, whilst laterally the frontal supports 
 the parietal. 
 
128 THE SKELETON 
 
 The Occipito -parietal or Lambdoid Suture (sutura lamhdoidea) , so called from 
 its resemblance to the Greek letter A, connects the occipital with the parietal 
 bones. It commences on each side at the mastoid portion of the temporal bone, 
 and inclines upward to the end of the sagittal suture. The dentations of this 
 suUire are very deep and distinct, and are often interrupted by several small 
 Wormian bones. 
 
 The sutures at the side of the skull extend from the external angular process of 
 the frontal bone to the lower end of the lambdoid suture behind. Theanterior 'portion 
 is formed between the lateral part of the frontal bone above and the malar and great 
 wing of the sphenoid below, forming the fronto-malar suture {sutura zijgomatico- 
 frontalis) and fronto-sphenoidal suture (sutura spheno frontalis). These sutures 
 can also be seen in the orbit, and form part of the so-called transverse facial 
 suture. The posterior portion is formed between the parietal bone above and 
 the great wing of the sphenoid, the squamous and mastoid portions of the temporal 
 bone below, forming the spheno -parietal, squamo-parietal, and masto-parietal sutures. 
 
 The spheno-parietal {sutura sphenoparietalis) is very short; it is formed by the 
 tip of the great wing of the sphenoid, which overlaps the anterior inferior angle 
 of the parietal bone. 
 
 The squamo-parietal or squamous suture (sutura squamosa) is arched. It is 
 formed by the squamous portion of the temporal bone overlapping the middle 
 division of the lower border of the parietal. 
 
 The masto-parietal (sutura parietomastoidea) is a short suture, deeply dentated, 
 formed by the posterior inferior angle of the parietal and the superior border of 
 the mastoid portion of the temporal. 
 
 The sutures at the base of the skull are the basilar in the centre, and on each 
 side the petro-occipital, the masto-occipital, the petro-sphenoidal, and the squamo- 
 sphenoidal. 
 
 The Basilar Suture (fissura sphenooccipitalis) is formed by the junction of the 
 basilar surface of the occipital bone with the posterior surface of the body of 
 the sphenoid. At an early period of life a thin plate of cartilage exists between 
 these bones, but in the adult they become fused into one (synchondrosis spheno- 
 occipitalis) . Between the outer extremity of the basilar suture and the termina- 
 tion of the lambdoid an irregular suture exists, which is subdivided into two por- 
 tions. The inner portion, formed by the union of the petrous part of the temporal 
 with the occipital bone, is termed the petro-occipital fissure (fissura petrooccipitalis) . 
 The outer portion, formed by the junction of the mastoid part of the temporal 
 with the occipital, is called the masto-occipital suture (sutura occipitomastoidea) . 
 Between the bones forming the petro-occipital suture a thin plate of cartilage 
 exists; in the masto-occipital is occasionally found the opening of the mastoid 
 foramen. Between the outer extremity of the basilar suture and the spheno- 
 parietal an irregular suture may be seen, formed by the union of the sphenoid 
 with the temporal bone. The inner and smaller portion of this suture is termed 
 the petro-sphenoidal fissure (fissura spheno petrosa) ; it is formed between the 
 petrous portion of the temporal and the great wing of the sphenoid; the outer 
 portion, of greater length and arched, is formed between the squamous portion 
 of the temporal and the great wing of the sphenoid ; it is called the squamo- 
 sphenoidal suture (sutura spheno squamosa) . 
 
 The cranial bones are connected with those of the face, and the facial bones 
 with each other, by numerous sutures, which, though distinctly marked, have 
 received no special names. The only remaining suture deserving especial con- 
 sideration is the transverse suture. This extends across the upper part of the face, 
 and is formed by the junction of the frontal with the facial bones: it extends from 
 the external angular process of one side to the same point on the opposite side, 
 and connects the frontal with the malar, the sphenoid, the ethmoid, the lachrymal, 
 
THE VERTEX OF THE SKULL 129 
 
 the superior maxillary, and the nasal bones on each side (sutura zygomatico- 
 frontalis; the orbital portion of the sutura sphenofrontalis, sutura fronto- 
 cthmoidalis , sutura frontolacrimalis, sutura frontomaxillaris, sutura nasofrontalis) . 
 Tlie sutures remain separate for a considerable period after the complete for- 
 mation of the skull. It is probable that they serve the purpose of permitting the 
 growth of the bones at their margins, while their peculiar formation, together 
 with the interposition of the sutural ligament between the bones forming them, 
 prevents the dispersion of blows or jars received upon the skull. Humphry 
 remarks, "that, as a general rule, the sutures are first obliterated at the parts in 
 which the ossification of the skull was last completed — viz., in the neighborhood 
 of the fontanelles; and the cranial bones seem in this respect to observe a similar 
 law to that which regulates the union of the epiphyses to the shafts of the long 
 bones." The same author remarks that the time of their disappearance is ex- 
 tremely variable: they are sometimes found well marked in skulls edentulous 
 with age, while in others which have only just reached maturity they can hardly 
 be traced. The obliteration of the sutures takes place sooner on the inner than 
 on the outer surface of the skull. The sagittal and coronal sutures are as a rule 
 the first to become ossified — the process starting near the posterior extremity of 
 the former and the lower ends of the latter. 
 
 THE SKULL AS A WHOLE. 
 
 The skull, formed by the union of the several cranial and facial bones already 
 described, when considered as a whole is divisible into five regions: a superior 
 region or vertex, an inferior region or base, two lateral regions, and an anterior 
 region, the face. 
 
 The Vertex of the Skull. 
 
 The superior region, or vertex, presents two surfaces, an external and an 
 internal. 
 
 Surfaces. External Surface. (This surface as seen from above is called the 
 norma verticalis.) — The external surface is bounded, in front, by the glabella 
 and supraorbital ridges; behind, by the occipital protuberance and superior 
 curved lines of the occipital bone; laterally, by an imaginary line extending from 
 the outer end of the superior curved line, along the temporal ridge, to the exter- 
 nal angular process of the frontal bone. This surface includes the greater pai't of 
 the vertical portion of the frontal, the greater part of the parietal, and the superior 
 third of the occipital bone; it is smooth, convex, of an elongated oval form, crossed 
 transversely by the coronal suture, and from before backward by the sagittal, 
 which terminates behind in the lambdoid. The point of junction of the coronal 
 and sagittal sutures is named the bregma, and is represented by a line drawn verti- 
 cally upward from the external auditory meatus, the head being in its normal posi- 
 tion. The point of junction of the sagittal and lambdoid sutures is called the 
 lambda, and is about 2f inches above the external occipital protuberance. From 
 before backward may be seen the frontal eminences and remains of the suture 
 connecting the two lateral halves of the frontal bone; on each side of the sagittal 
 siiture are the parietal foramen and parietal eminence, and still more posteriorly 
 the convex surface of the occipital bone. In the neighborhood of the parietal 
 foramen the skull is often flattened, and the name of obelion is sometimes given 
 to that point of the sagittal suture which lies exactly opposite to the parietal 
 foramen. 
 
 Internal or Cerebral Surface. — The internal surface is concave, presents depres- 
 sions for the convolutions of the cerebrum, and numerous furrows for the lodge- 
 ment of branches of the meningeal arteries. Along the middle line of this 
 
130 THE SKELETON 
 
 surface is a longitudinal groove, narrow in front, where it commences at the 
 frontal crest, but broader behind, where it lodges the superior longitudinal 
 sinus, and by its margin affords attachment to the falx cerebri. On either side 
 of it are several depressions for the Pacchionian bodies, and at its back part 
 the internal openings of the parietal foramina. This surface is crossed, in front, 
 by the coronal suture; from before backward by the sagittal; behind, by the 
 lambdoid. 
 
 The Base of the Skull (the Skull being without the Mandible). 
 
 The inferior region, or base of the skull, presents two surfaces — an internal 
 or cerebral, and an external or basilar. 
 
 Surfaces. Internal Upper or Cerebral Surface. — The internal or cerebral surface 
 (Fig. 95) presents three fossaj, called the anterior, middle, and posterior fossse of the 
 cranium. 
 
 Anterior Fossa (fossa cranii anterior). — The anterior fossa is formed by the 
 orbital plates of the frontal, the cribriform plate of the ethmoid, the anterior 
 third of the superior surface of the body, and the upper surface of the lesser wings 
 of the sphenoid bone. It is the most elevated of the three fosste, convex exter- 
 nally where it corresponds to the roof of the orbit, concave in the median line in 
 the situation of the criliriform plate of the ethmoid. It is traversed by three sutures, 
 the ethmo-frontal, ethmo-sphenoidal, and fronto-sphenoidal, and lodges the frontal 
 lobe of the cerebrum. It presents, in the median hne, from before backward, the 
 commencement of the groove for the superior longitudinal sinus and the frontal 
 crest for the attachment of the falx cerebri; the foramen caecum, an aperture formed 
 between the frontal bone and the crista galli of the ethmoid, which, if pervious, 
 transmits a small vein from the nose to the superior longitudinal sinus; behind the 
 foramen cjecum, the crista galli, the posterior margin of which affords attachment 
 to the falx cerebri; on either side of the crista galli, the cribriform plate, which sup- 
 ports the olfactory bulb, and presents three rows of foramina for the transmission 
 of its nervous filaments, and in front a slit-like opening for the nasal branch of 
 the ophthalmic division of the fifth nerve. On the outer side of each olfactory 
 groove are the internal openings of the anterior and posterior ethmoidal foramina; 
 the former, situated about the middle of the outer margin of the olfactory 
 groove, transmits the anterior ethmoidal vessels and the nasal nerve, which latter 
 runs in a depression along the surface of the ethmoid to the slit-like opening abov^e 
 mentioned; while the posterior ethmoidal foramen opens at the back part of this 
 margin under cover of the projecting lamina of the sphenoid, and transmits the 
 posterior ethmoidal vessels. Farther back in the middle line is the ethmoidal spine, 
 bounded behind by a slight elevation, separating two shallow longitudinal grooves 
 which support the olfactory lobes. Behind this is a transverse sharp ridge, run- 
 ning outward on either side to the anterior margin of the optic foramen, and sepa- 
 rating the anterior from the middle fossa of the l)ase of the skull. The anterior 
 fossa presents, laterally, depressions for the convolutions of the brain and grooves 
 for the lodgement of the anterior meningeal arteries. 
 
 Middle Fossa (fossa cranii media). — The middle fossa, deeper than the pre- 
 ceding, is narrow in the middle line, but becomes wider at the side of the skull. It 
 is bounded in front by the posterior margin of the lesser wing of the sphenoid, the 
 anterior clinoid process, and the ridge forming the anterior margin of the optic 
 groove; behind, by the superior border of the petrous portion of the temporal and 
 the dorsum ephippii; externally by the squamous portion of the temporal anterior 
 inferior angle of the parietal bone, and greater wing of the sphenoid. It is trav- 
 ersed by four sutures, the squamo-parietal, spheno-parietal, squamo-sphenoidal, 
 and petro-sphenoidal. In the middle line, from before backward, is the optic 
 
 I 
 
THE BASE OF THE SKULL 
 
 131 
 
 groove, behind which Hes the optic commissure; the groove terminates on each side 
 in the optic foramen, for the passage of the optic nerve and ophthalmic artery; 
 
 Groove for superior longitudinal sinus. 
 
 Grooves for anterior meningeal artery. 
 
 Foramen cseeum. 
 
 Crista galli. 
 
 Slit for nasal nerve. 
 
 Groove for 7iasal nerve. 
 
 Anterior ethinoidal foramen. 
 
 Orifices for olfactory nerves. 
 
 Postei'ior ethmoidal foramen. 
 
 Ethmoidal spine. 
 
 Olfactory grooves. 
 
 Optic foramen. 
 
 Optic groove. f 
 
 Olivary process.- G^^' 
 
 Anterior clinoid process. 
 Middle clinoid process. 
 
 Postei-ior clinoid process. 
 
 Groove for 6th nerve. 
 
 Foramen lacerum medium. 
 
 Orifice of carotid canal. 
 
 Depression for Gasserian ganglion. 
 
 Meatus auditorius internus. 
 
 Slit for dura mater. 
 
 Superior petrosal groove. 
 
 Foramen lacerum posterius. 
 
 Anterior condyloid foramen. 
 
 Aquxductus vestibuli. 
 
 Posterior condyloid foramen. 
 
 Mastoid foramen. 
 Posterior meningeal grooves. 
 
 Fig. 95. — Base of the .skull. Inner or cerebral surface. 
 
 behind the optic groove is the olivaxy process and laterally the anterior clinoid pro- 
 cesses, to which are attached processes of the tentorium cerebelH. Farther back is 
 the sella tm-cica, a deep depression which lodges the pituitary gland, bounded in 
 
132 THE SKELETON 
 
 front by a small eminence on either side, the middle clinoid process, and behind by 
 a broad, square plate of bone, the dorsum ephippii, surmounted at each superior 
 angle by a tubercle, the posterior clinoid process; beneath the latter process is 
 a notch, for the sixth nerve. On each side of the sella turcica is the cavernous 
 groove: it is broad, shallow, and curved somewhat like the italic letter /; it com- 
 mences behind at the foramen lacerum medium, and terminates on the inner 
 side of the anterior clinoid process, and presents along its outer margin a ridge 
 of bone. This groove lodges the cavernous sinus, the internal carotid artery, 
 and the nerves of the orbit. The sides of the middle fossa are of considerable 
 depth; they present depressions for the convolutions of the brain and grooves 
 for the branches of the middle meningeal artery; the latter commence on the 
 outer side of the foramen spinosum, and consist of two large branches, an anterior 
 and a posterior; the former passing upward and forward to the anterior inferior 
 angle of the parietal bone, the latter passing upward and backward. The fol- 
 lowing foramina may also be seen from before backward: Most anteriorly is the 
 foramen lacerum anterius, or sphenoidal fissure (fissura orhitaLis superior), formed 
 above by the lesser wing of the sphenoid; below, by the greater wi ig; internally, by 
 the body of the sphenoid ; and sometimes completed externally by the orbital plate 
 of the frontal bone. It transmits the third, the fourth, the three branches of the 
 ophthalmic division of the fifth, the sixth nerve, some filaments from the cavernous 
 plexus of the sympathetic, the orbital branch of the middle meningeal artery, a 
 recurrent branch from the lachrymal artery to the dura mater, and the ophthalmic 
 vein. Behind the inner extremity of the sphenoidal fissure is the foramen rotundum, 
 for the passage of the second division of the fifth or the superior maxillary nerve; 
 still more posteriorly is seen a small orifice, the foramen Vesalii.an opening situated 
 between the foramen rotundum and ovale, a little internal to both: it varies in size 
 in different individuals, and is often absent; when present it transmits a small vein. 
 It opens below into the pterygoid fossa, just at the outer side of the scaphoid 
 depression. Behind and external to the latter opening is the foramen ovale, which 
 transmits the third division of the fifth or the inferior maxillary nerve, the small 
 meningeal artery, and the small petrosal nerve.^ On the outer side of the foramen 
 ovale is the foramen spinosum, for the passage of the middle meningeal artery; and 
 on the inner side of the foramen ovale is the foramen lacerum medium. The lower 
 part of this aperture is filled with cartilage in the recent state. The Vidian nerve 
 and a meningeal branch from the ascending pharyngeal artery pierce this car- 
 tilage. On the anterior surface of the petrous portion of the temporal bone is 
 seen, from without inward, the eminence caused by the projection of the superior 
 semicircular canal; in front of and a little outside this is a depression corresponding 
 to the roof of the tympanum; the groove leading to the hiatus Fallopii, for the 
 transmission of the petrosal branch of the Vidian nerve and the petrosal branch 
 of the middle meningeal artery; beneath it, the smaller groove, for the passage 
 of the lesser petrosal nerve; and, near the apex of the bone, the depression for 
 the Gasserian ganglion; and the internal orifice of the carotid canal {foramen 
 caroticum internum), for the passage of the internal carotid artery and carotid 
 plexus of nerves. 
 
 Posterior Fossa (fossa cranii posterior). — The posterior fossa, deeply concave, 
 is the largest of the three, and situated on a lower level than either of the preceding. 
 It is formed by the posterior third of the superior surface of the bodv of the sphe- 
 noid, by the occipital, the petrous and mastoid portions of the temporal, and the 
 posterior inferior angle of the parietal bone; it is crossed by four sutures, the petro- 
 occipital, the masto-occipital, the masto-parietal, and the basilar; and lodges the 
 cerebellum, pons Varolii, and medulla oblongata. It is separated from the middle 
 
 * See footnote, p. 95. 
 
THE BASE OF THE SKULL 133 
 
 fossa in the median line by the dorsum ephippii, and on each side by the superior 
 border of the petrous portion of the temporal bone. This border serves for the 
 attachment of the tentorium cerebelli, is grooved for the superior petrosal sinus, 
 and at its inner extremity presents a notch, upon which rests the fifth nerve. The 
 circumference of the fossa is bounded posteriorly by the grooves for the lateral 
 sinuses. In the centre of this fossa is the foramen magnum, bounded on either 
 side by a rough tubercle, which gives attachment to the odontoid" or check liga- 
 ments; and a little above these are seen the internal openings of the anterior 
 condyloid foramina, through which pass the hypoglossal nerves and meningeal 
 branches from the ascending pharyngeal arteries. In front of the foramen mag- 
 num is a grooved surface, formed by the basilar process of the occipital bone and 
 by the posterior third of the superior surface of the body of the sphenoid, which 
 supports the medulla oblongata and pons Varolii, and articulates on each side 
 with the petrous portion of the temporal bone, forming the petro-occipital suture, 
 the anterior half of which is grooved for the inferior petrosal sinus, the posterior 
 half being encroached upon by the foramen lacerum posterius or jugular foramen 
 (foramen jugulare). This foramen presents three compartments : through the ante- 
 rior passes the inferior petrosal sinus ; through the posterior, the lateral sinus and 
 some meningeal branches from the occipital and ascending pharyngeal arteries; 
 and through the middle, the glosso-pharyngeal, pneumogastric, and spinal acces- 
 sory nerves. Above the jugular foramen is the internal auditory meatus, for the 
 facial and auditory nerves and auditory artery; behind and external to this is the 
 slit-like opening leading into the aquaeductus vestibuli, which lodges the ductus 
 endolymphaticus; while between the two latter, and near the superior border of 
 the petrous portion, is a small, triangular depression, the remains of the floccular 
 fossa, which lodges a process of the dura mater and occasionally transmits a small 
 vein into the substance of the bone. Behind the foramen magnum are the inferior 
 occipital fossae, which lodge the hemispheres of the cerebellum, separated from 
 one another by the internal occipital crest, which serves for the attachment of the 
 falx cerebelli and lodges the occipital sinus. The posterior fossae are surmounted 
 above by the deep transverse grooves for the lodgement of the lateral sinuses. 
 These channels, in their passage outward, groove the occipital bone, the posterior 
 inferior angle of the parietal, the mastoid portion of the temporal, and the jugular 
 process of the occipital, and terminate at the back part of the jugular foramen. 
 Where this sinus grooves the mastoid portion of the temporal bone the orifice of 
 the mastoid foramen may be seen. Just previous to the termination of the groove 
 the posterior condyloid foramen opens into it. Neither foramen is constant. 
 
 External Under or Basilar Surface (the view from below is called the norma 
 basalis). — The external surface of the base of the skull (Fig. 96) is extremely 
 irregular. It is bounded in front by the incisor teeth in the upper jaw; behind 
 by the superior curved lines of the occipital bone; and laterally by the alve- 
 olar arch, the lower border of the malar bone, the zygoma, and an imaginary line 
 extending from the zygoma to the mastoid process and extremity of the superior 
 curved line of the occiput. It is formed by the palate processes of the superior 
 maxillary and palate bones, the vomer, the pterygoid processes, under surface 
 of the great wing, spinous processes and part of the body of the sphenoid, the 
 under surface of the squamous, mastoid, and petrous portions of the temporal, 
 and the under surface of the occipital bone. The anterior part of the base of the 
 skull is raised above the level of the rest of this surface (when the skull is turned 
 over for the purpose of examination), surrouhded by the alveolar process, which is 
 thicker behind than in front, and excavated by sixteen depressions for lodging the 
 teeth of the upper jaw, the cavities varying in depth and size according to the teeth 
 they contain. Immefliately behind the incisor teeth is the anterior palatine fossa 
 (foramen incisivum) . At the bottom of this fossa may usually be seen four apertures : 
 
134 
 
 THE SKELETON 
 
 two placed laterally, the foramina of Stenson, which open above, one in the floor of 
 each nostril, and transmit the anterior branch of the posterior palatine vessels, and 
 
 ,c<'- 
 
 Anterior palatine fossa. 
 
 Transmits left naso-palatine nerve. 
 Transmits anterior palatine vessel. 
 Transmits right naso-palatine nerve. 
 
 Accessory palatine foramina. 
 Posterior nasal spine. 
 
 AZYQOS UVUL>E. 
 
 Hamular process. 
 
 Sphenoid process of palate. 
 Ptery go-palatine canal. 
 
 -TENSOR TYMPANI. 
 
 ■Pharyngeal spine for 
 
 SUPERIOR CONSTRICTOR. 
 
 Situation of Eustachian tube and 
 canal for tensor tvmpani. 
 
 TENSOR PALATI. 
 
 Canal for Jacobson's nerve. 
 Aquxductus cochlem. 
 Foramen lacerum posterius. 
 Canal for Arnold's nerve. 
 ~ Auricular fissure. 
 
 Fig. 96. — Base of the skull. External surface. 
 
THE BASE OF THE SKULL I35 
 
 two in the median line in the intermaxillary suture, the foramina of Scarpa, one 
 in front of the other, the anterior transmitting the left, and the posterior (the 
 larger) the right, naso-palatine nerve. These two lateral canals are sometimes 
 wanting, or they may join to form a single one, or one of them may open into one 
 of the lateral canals above referred to. The palatine vault is concave, uneven, 
 perforated by numerous foramina, marked by depressions for the palatine glands, 
 anfl crossed by a crucial suture, formed by the junction of the four bones of which 
 it is composed. At the front part of this surface a delicate hnear suture may 
 frequently be seen, passing outward and forward from the anterior palatine fossa 
 to the interval between the lateral incisor and canine teeth, and marking off the 
 pre -maxillary portion of the bone. At each posterior angle of the hard palate is 
 the posterior palatine foramen, for the transmission of the posterior palatine vessels 
 and great descending palatine nerve; and running forward and inward from it a 
 groove, for the same vessels and nerve. Behind the posterior palatine foramen 
 is the tuberosity of the palate bone, perforated by one or more accessory posterior 
 palatine canals, and marked by the commencement of a ridge which runs trans- 
 versely inward, and serves for the attachment of the tendinous expansion of the 
 Tensor palati muscle. Projecting backward from the centre of the posterior 
 border of the hard palate is the posterior nasal spine, for the attachment of the 
 Azygos uvulffi nmscle. Behind and above the hard palate is the posterior aper- 
 ture of the nares, divided into two parts by the vomer, bounded above by the 
 body of the sphenoid, below by the horizontal plate of the palate bone, and lat- 
 erally by the internal pterygoid plate of the sphenoid. Each aperture measures 
 about an inch in the vertical and about half an inch in the transverse direction. 
 At the base of the vomer may be seen the expanded alte of this bone, receiving 
 between them, on each side, the rostrum of the sphenoid. Near the lateral margins 
 of the vomer, at the root of the pterygoid processes, are the pterygo-palatine canals. 
 The pterygoid process, which bounds the posterior nares on each side, presents 
 near its base the pterygoid or Vidian canal (canalis pterygoideus) ,ior the Vidian nerve 
 and artery. Each process consists of two plates, which bifurcate at the extremity to 
 receive the tuberosity of the palate bone, and are separated behind by the ptery- 
 goid fossa, which lodges the Internal pterygoid muscle. The internal plate is 
 long and narrow, presenting on the outer side of its base the scaphoid fossa, for 
 the origin of the Tensor palati muscle, and at its extremity the hamular process, 
 around which the tendon of this muscle turns. The external pterygoid plate is 
 broad, forms the inner boundary of the zygomatic fossa, and affords attachment 
 by its outer surface to the External pterygoid muscle. 
 
 Behind the nasal fossae in the middle line is the basilar surface of the occipital 
 bone, presenting in its centre the pharsmgeal spine, for the attachment of the 
 Superior constrictor muscle of the pharynx, with depressions on each side for 
 the insertion of the Rectus capitis anticiis major and minor. At the base of the 
 exteriial pterygoid plate is the foramen ovale, for the transmission of the third 
 division of the fifth nerve, the small meningeal artery, and sometimes the small 
 petrosal nerve; behind this, the foramen spinosum, w^hich transmits the middle 
 meningeal artery, and the prominent spinous process of the sphenoid, which gives 
 attachment to the internal lateral ligament of the lower jaw' and the Tensor palati 
 muscle. External to the spinous process is tlie glenoid fossa, divided into two parts 
 by the Glaserian fissure (page 84), the anterior portion concave, smooth, bounded 
 in front by the eminentia articularis, and serving for the articulation of the condyle 
 of the lower jaw; the posterior portion rough, bounded behind by the tympanic 
 plate, and serving for the reception of part of the parotid gland. Emerging from 
 between the laminae of the vaginal process of the tympanic plate is the styloid 
 process, and at the base of this process is the stylo-mastoid foramen, for the exit of 
 the facial nerve and entrance of the stylo-mastoid artery. External to the stylo- 
 
136 THE SKELETON 
 
 mastoid foramen is the auricular fissure, for the auricular branch of the pneumo- 
 gastric, bounded behind by the mastoid process. Upon the inner side of the mas- 
 toid process is a deep groove, the digastric fossa; and a little more internally the 
 occipital groove, for the occipital artery. At the base of the internal pterygoid plate 
 is a large and somewhat triangular aperture, the foramen lacerum medium, bounded 
 in front by the great wing of the sphenoid, behind by the apex of the petrous por- 
 tion of the temporal bone, and internally by the body of the sphenoid and basilar 
 process of the occipital bone : it presents in front the posterior orifice of the Vidian 
 canal; behind, the aperture of the carotid canal. The basilar surface of this open- 
 ing is filled in the recent state by fibro-cartilaginous substance; across its upper 
 or cerebral aspect passes the internal carotid artery. External to this aperture the 
 petro-sphenoidal sutiure is observed, at the outer termination of which is seen the 
 orifice of the canal for the Eustachian tube and that for the Tensor tympani 
 muscle. Behind this suture is seen the under surface of the petrous portion of the 
 temporal bone, presenting, from within outward, the quadrilateral, rough surface, 
 part of which affords attachment to the Levator palati and Tensor tympani mus- 
 cles; external to this surface the orifices of the carotid canal (foramen caroticum 
 externum) and the aquaeductus cochleae, the former transmitting the internal 
 carotid artery anrl the ascending branches of the superior cervical ganglion 
 of the sympathetic, the latter serving for the passage of a small artery and vein 
 to the cochlea. Behind the carotid canal is a large aperture, the jugular foramen, 
 formed in front by the petrous portion of the temporal, and behind by the 
 occipital; it is generally larger on the right than on the left side, and is divided 
 into three compartments by processes of dura mater. The anterior is for the 
 passage of the inferior petrosal sinus; the posterior, for the lateral sinus and 
 some meningeal branches from the occipital and ascending pharyngeal arteries; 
 the central one, for the glosso-pharyngeal, pneumogastric, and spinal accessory 
 nerves. On the ridge of bone dividing the carotid canal from the jugular fora- 
 men is the small foramen for the transmission of Jacobson's nerve; and on the 
 wall of the jugular foramen, near the root of the styloid process, is the small 
 aperture for the transmission of Arnold's nerve. Behind the basilar surface of 
 the occipital bone is the foramen magnum, bounded on each side by the con- 
 dyles, rough internally for the attachment of the check or odontoid ligaments, and 
 presenting externally a rough surface, the jugular process, which serves for the 
 attachment of the Rectus capitis lateralis muscle and the lateral occipito-atlantal 
 ligament. On either side of each condyle anteriorly is the anterior condyloid fossa, 
 perforated by the anterior condyloid foramen, for the passage of the hypoglossal 
 nerve and often a meningeal branch of the ascending pharyngeal artery. Behind 
 each condyle is the posterior condyloid fossa, perforated by the posterior condyloid 
 foramen, for the transmission of a vein to the lateral sinus. Behind the foramen 
 magnum is the external occipital crest, terminating above at the external occipital 
 protuberance, whilst on each side are seen the superior and inferior curved lines; 
 these, as well as the surfaces of bone between them, are rough for the attachment 
 of the muscles, which are enumerated on page 76. 
 
 The Lateral Region of the Skull. 
 
 The view of the lateral region of the skull from the side is known as the norma 
 lateralis. The lateral region is of a somewhat triangular form, the base of the tri- 
 angle being formed by a line extending from the external angular process of the 
 frontal bone along the temporal ridge backward to the outer extremity of the supe- 
 rior curved line of the occiput; and the sides by two lines, the one drawn down- 
 ward and backward from the external angular process of the frontal bone to the 
 angle of the lower jaw, the other from the angle of the jaw upward and back- 
 
THE LATERAL REGION OF THE SKULL 
 
 137 
 
 ward to the outer extremity of the superior curved line. This region is divisible into 
 three portions — temporal fossa, mastoid portion, and zygomatic or infratemporal fossa. 
 The Temporal Fossa {fossa temporalis). — The temporal fossa is bounded above 
 and behind by the temporal ridges, which extend from the external angular process 
 of the frontal upward and backward across the frontal and parietal bones, curving 
 downward behind to terminate in the posterior root of the zygomatic process, supra- 
 
 |'<:^//('V/''V>/ 
 
 
 Y 
 
 5 :A}^'^ 
 
 M^f 
 
 ^m%- * 
 
 r 
 
 / / 
 
 Oc< 
 
 ■,f 
 
 ■l^-/ 
 
 y 
 
 
 Fig. 97. — Side view of the skull. (Cryer.) 
 
 mastoid crest. In front it is bounded by the frontal, malar, and great wing of the 
 sphenoid; externally by the zygomatic arch formed conjointly by the malar and 
 temporal bones; below, it is separated from the zygomatic fossa by the pterygoid 
 ridge, seen on the outer surface of the great wing of the sphenoid. This fossa is 
 formed by five bones, part of the frontal, great wing of the sphenoid, parietal, squa- 
 mous portion of the temporal and malar bones, and is traversed by six sutures, part of 
 the transverse facial, spheno-malar, coronal, spheno-parietal, squamo-parietal, and 
 squamo-sphenoidal. The point where the coronal suture crosses the superior tem- 
 poral ridge is sometimes named the stephanion ; and the region where the four bones, 
 the parietal, the frontal, the squamous, and the greater wing of the sphenoid, meet, 
 at the anterior inferior angle of the parietal bone, is named the pterion. This point 
 is about on a level with the external angular process of the frontal bone and about 
 one and a half inches behind it. This fossa is deeply concave in front, convex 
 behind, traversed by grooves which lodge branches of the deep temporal arteries, 
 and filled by the Temporal muscles. 
 
138 
 
 THE SKELETON 
 
 The Mastoid Portion. — The mastoid portion of the side of the skull is bounded 
 in front by the tubercle of the zygoma; above, by a line which runs from the pos- 
 terior root of the zygoma to the end of the mastoid-parietal suture; behind and 
 below by the masto-occipital suture. It is formed by the mastoid and part of the 
 squamous and petrous portions of the temporal bone; its surface is convex and 
 rough for the attachment of muscles, and presents, from behind forward, the 
 mastoid foramen, the mastoid process, the external auditory meatus surrounded by 
 the tympanic plate, and, most anteriorly, the temporo-maxillary articulation. The 
 point where the posterior inferior angle of the parietal meets the occipital bone 
 and mastoid portion of the temporal is named the asterion. 
 
 The Zygomatic or Infratemporal Fossa {jossa infratemporalis) . — The zygo- 
 matic fossa is an irregularly shaped cavity, situated below and on the inner side 
 of the zygoma; bounded in front by the zygomatic surface of the superior maxil- 
 lary bone and the ridge which descends from its malar process; behind, by the 
 posterior border of the external pterygoid plate and the eminentia articularis; 
 above, by the pterygoid ridge on the outer surface of the great wing of the 
 sphenoid and the under part of the squamous portion of the temporal; below, 
 by the alveolar border of the superior maxilla; internally, by the external pterygoid 
 plate; and externally, by the zygomatic arch and ramus of the lower jaw (Fig. 98). 
 
 Ext. auditory y^ 
 
 Spheno- ^^U 
 
 maxillary ^^H 
 
 fissure. ^H 
 
 meatus. Styloid 
 
 /^ 
 
 process. 
 
 Ext. 
 
 
 pterygoid 
 plate. 
 
 Fig. 98. — Zygomatic fossa. 
 
 It contains the lower part of the Temporal, the External and Internal pterygoid 
 muscles, the internal maxillary artery and vein, and inferior maxillary nerve and 
 their branches. At its upper and inner part may be observed two fissures, the 
 spheno-maxillary and pterygo-maxillary fissures. 
 
 The Spheno-maxillary Fissure {fissura orhitalis inferior), horizontal in direction, 
 opens into the outer and back jmrt of the orbit. It is formed above by the lower 
 border of the orbital surface of the great wing of the sphenoid ; below, by the exter- 
 nal border of the orbital surface of the superior maxilla and a small part of the 
 palate bone; externally, by a small part of the malar bone:* internally, it joins at 
 
 1 Occasionally the superior maxillary bone and the sphenoid articulate with each other at the anterior 
 extremity of this fissure ; the malar is then excluded from entering into its formation. 
 
THE ANTERIOR REGION OF THE SKULL 139 
 
 right angles with the pterygo-maxillary fissure. This fissure opens a communication 
 from the orbit into three fossae — the temporal, zygomatic, and spheno -maxillary fossa ; 
 it transmits the superior maxillary nerve and its orbital branch, the infraorbital 
 vessels, and ascending branches from the spheno-palatine or Meckel's ganglion. 
 
 The Pterygo-maxillary Fissm^e is vertical, and descends at right angles from the 
 inner extremity of the preceding; it is a V-shaped interval, formed by the diver- 
 gence of the superior maxillary bone from the pterygoid process of the sphenoid. 
 It serves to connect the spheno-maxillary fossa with the zygomatic fossa, and 
 transmits the internal maxillary artery. 
 
 The Spheno-maxillary or Pterygo-palatine Fossa {fossa pterygopalatina). — 
 The spheno-maxillary fossa is a small, triangular space situated at the angle 
 of junction of the spheno-maxillary and pterygo-maxillary fissures, and placed 
 beneath the apex of the orbit. It is formed above by the under surface of the 
 body of the sphenoid and by the orbital process of the palate bone; in front, 
 by the superior maxillary bone; behind, by the anterior surface of the base of 
 the pterygoid process and lower part of the anterior surface of the great wing of 
 the sphenoid; internally, by the vertical plate of the palate. This fossa has 
 three fissures terminating in it — the sphenoidal, spheno-maxillary,- and pterygo- 
 maxillary; it communicates with the orbit by the spheno-maxillary fissure ; with the 
 nasal fossae by the spheno-palatine foramen, and with the zygomatic fossa by the 
 pterygo-maxillary fissure. It also communicates with the cavity of the cranium, 
 and has opening into it five foramina. Of these, there are three on the posterior 
 wall : the foramen rotmidum above ; below and internal to this, the Vidian canal ; and 
 still more inferiorly and internally, the pterygo-palatine canal. On the inner wall 
 is the spheno-palatine foramen, by which the spheno-maxillary communicates with 
 the nasal fossa; and below is the superior orifice of the posterior palatine canal, 
 besides occasionally the orifices of the accessory posterior palatine canals. The 
 fossa contains the superior maxillary nerve and Meckel's ganglion, and the termi- 
 nation of the internal maxillary artery. 
 
 The Anterior Region of the Skull. 
 
 The view of the anterior region of the skull from the front is known as the 
 norma frontalis. It forms the face, is of an oval form, presents an irregular 
 surface, and is excavated for the reception of two of the organs of sense, the 
 eye and the nose. It is bounded above by the glabella and margins of the 
 orbit; below, by the prominence of the chin; on each side by the malar bone 
 and anterior margin of the ramus of the jaw. In the median line are seen from 
 above downward the glabella, and diverging from it are the superciUary ridges, 
 which indicate the situation of the frontal sinuses and supports the eyebrow. 
 Beneath the glabella is the fronto-nasal suture, the mid-point of which is termed 
 the nasion, and below this is the arch of the nose, formed by the nasal bones, and 
 the nasal processes of the superior maxillary. The nasal arch is convex from side 
 to side, concave from above downward, presenting in the median line the inter- 
 nasal suture {sutura inter nasalis) , formed between the nasal bones, laterally the 
 naso-maxillary suture {sutura nasomaxillaris) , formed between the nasal bone and 
 the nasal process of the superior maxillary bone. Below the nose is seen the 
 opening of the anterior nares, which is heart-shaped, with the narrow end 
 upward, and presents laterally the thin, sharp margins serving for the attach- 
 ment of the lateral cartilages of the nose, and in the middle line below a 
 prominent process, the anterior nasal spine, bounded by two deep notches. 
 Below this is the intermaxillary suture {sutura intermaxillaris) , and on each side 
 of it the iricisive fossa. Beneath this fossa are the alveolar processes of the 
 upper and lower jaws, containing the incisor teeth, and at the lower part of the 
 
140 
 
 THE SKELETON 
 
 median line the symphysis of the chin, the mental process, with its two mental 
 tubercles, separated by a median groove, and the incisive fossa of the lower jaw. 
 
 On each side, proceeding from above downward, is the supraorbital ridge, 
 terminating externally in the external angular process at its junction with the 
 malar, and internally in the internal angular process; toward the inner third of 
 this ridge is the supraorbital notch or foramen, for the passage of the supraorbital 
 vessels and nerve. Beneath the supraorbital ridge is the opening of the orbit, 
 bounded externally by the orbital ridge of the malar bone; below, by the orbital 
 ridge formed by the malar and superior maxillary bones; internally, by the nasal 
 process of the superior maxillary and the internal angular process of the frontal 
 bone. On the outer side of the orbit is the quadrilateral anterior surface of the 
 malar bone, perforated by one or two small malar foramina. Below the inferior 
 margin of the orbit is the infraorbital foramen, the termination of the infraorbital 
 canal, and beneath this the canine fossa, which gives attachment to the Levator 
 anguli oris; still lower are the alveolar processes, containing the teeth of the upper 
 and lower jaws. Beneath the alveolar arch of the lower jaw is the mental foramen, 
 for the passage of the mental vessels and nerve, the external oblique line, and at 
 the lower border of the bone, at the point of junction of the body with the ramus, 
 a shallow groove for the passage of the facial artery. 
 
 Orbits, Orbital Cavities, or Orbital Fossae. — The orbits (from orhis, a circle) 
 (Fig. 99) are two quadrilateral pyramidal cavities, situated at the upper and anterior 
 
 TENDO OCULI 
 
 \<Tiooiefor 
 facial artery 
 
 [ueiice 
 
 Fig. 99. — Antero-lateral region of the skull. (Cryer.) 
 
THE ANTERIOR REGION OF THE SKULL 141 
 
 part of the face, their bases being directed forward and outward, and their apices 
 backward and inward, so that the axes of the two, if continued backward, would 
 meet over the body of the sphenoid bone. The wide orbital opening or mouth is 
 called the aditus orbitce. The orbit is lined with periosteum, the periorbita. Each 
 orbit (orbita) is formed of seveji bones, the frontal, sphenoid, ethmoid, superior 
 maxillary, malar, lachrymal, and palate; but three of these, the frontal, ethmoid, 
 and sphenoid, enter into the formation of both orbits, so that the two cavities are 
 formed of eleven bones only. Each cavity presents for examination a roof, a floor, 
 an inner and an outer wall, four angles, a circumference or base, and an apex. 
 
 The Roof (paries superior). — The roof is concave, directed downward and 
 slightly forward, and formed in front by the orbital plate of the frontal; behind, 
 by the lesser wing of the sphenoid. This surface presents internally the depres- 
 sion for the cartilaginous pidley of the Superior oblique muscle; externally, the 
 depression for the lachrymal gland; and posteriorly, the suture connecting the 
 frontal and lesser wing of the sphenoid. 
 
 The Floor (paries inferior). — The floor is directed upward and outward, and 
 is of less extent than the roof; it is formed chiefly by the orbital process of 
 the superior maxillary; in front, to a small extent, by the orbital process of the 
 malar, and behind, by the superior surface of the orbital process of the palate. 
 This surface presents at its anterior and internal part, just external to the lachrymal 
 groove, a depression for the attachment of the Inferior oblique muscle; externally, 
 the sutu re between the malar and superior maxillary bones ; near its middle, the infra- 
 orbital groove ; and posteriorly, the suture between the maxillary and palate bones. 
 
 Inner or Medial Wall (paries medialis). — The inner wall is flattened, nearly 
 vertical, and formed from before backward by the nasal process of the superior 
 maxillary, the lachrymal, os planum of the ethmoid, and a small part of the body of 
 the sphenoid. This surface presents the lachrymal groovie and crests of the lachrymal 
 bone, and the sutures connecting the lachrymal with the superior maxillary, the 
 ethmoid with the lachrymal in front, and the ethmoid with the sphenoi<l behind. 
 
 Outer or Lateral Wall (paries lateralis). — The outer wall is directed forward 
 and inward, and is formed in front by the orbital process of the malar bone; 
 behind, by the orbital surface of the greater wing of the sphenoid. On it are 
 seen the orifices of one or two malar canals, and the suture connecting the sphenoid 
 and malar bones. 
 
 Angles. — The superior external angle is formed by the junction of the upper 
 and outer walls; it presents from before backward, the suture connecting the 
 frontal with the malar in front and with the great wing of the sphenoid behind; 
 quite posteriorly is the foramen lacerum anterius, or sphenoidal fissure, which 
 transmits the third, the fourth, the three branches of the ophthalmic division of 
 the fifth, the sixth nerve, some filaments from the cavernous plexus of the sym- 
 pathetic, the orbital branch of the middle meningeal artery, a recurrent branch 
 from the lachrymal artery to the dura mater, and the ophthalmic vein. The 
 superior internal angle is formed by the junction of the upper and inner wall, and 
 presents the suture connecting the frontal bone with the lachrymal in front and 
 with the ethmoid behind. The point of junction of the anterior border of the 
 lachrymal with the frontal has been named the dacryon. This angle presents two 
 foramina, the anterior and posterior ethmoidal foramina, the former transmitting the 
 anterior ethmoidal vessels and nasal nerve, the latter the posterior ethmoidal vessels. 
 The inferior external angle, formed by the junction of the outer wall and floor, pre- 
 sents the spheno-maxillary fissure, which transmits the superior maxillary nerve and 
 its orliital branches, the infraorbital vessels, and the ascending branches from the 
 spheno-palatine or jNIeckel's ganglion. The inferior internal angle is formed by 
 the union of the lachrymal bone and the os planum of the ethmoid with the 
 superior maxillary and palate bones. 
 
142 
 
 THE SKELETON 
 
 Circumference. — The circumference or base of the orbit, quadrilateral in form, 
 is bounded above (margo swpraorhitalis) by the supraorbital ridge; below (margo 
 infraorb (talis) , by the anterior border of the orbital plate of the malar and supe- 
 rior maxillary bones; externally, by the external angular process of the frontal 
 and malar bones; internally, by the internal angular process of the frontal and the 
 nasal process of the superior maxillary. The circumference is marked by three 
 sutures, the fronto-maxillary internally, the fronto-malar externally, and the malo- 
 maxillary below; it contributes to the formation of the lachrymal groove, and 
 presents, above, the supraorbital notch (or foramen), for the passage of the supra- 
 orbital vessels and nerve. 
 
 Apex. — The apex, situated at the back of the orbit, corresponds to the optic 
 foramen,^ a short circular canal which transmits the optic nerve and ophthalmic 
 artery. It will thus be seen that there are nine openings communicating with each 
 orbit — viz., the optic foramen, sphenoidal fissure, spheno-maxillary fissure, supra- 
 orbital foramen, infraorbital canal, anterior and posterior ethmoidal foramina, 
 malar foramina, and the canal for the nasal duct. 
 
 >E FROM FRONTAL 
 
 SINUS IN THE 
 
 INFUNDIBULUM 
 
 LACHRYMAL CANAL PALATE BONE 
 
 Fig. 100. — Nasal cavity, right lateral wall, from the left. (Spalteholz.) 
 
 The Nasal Cavity (cavum nasi). — The nasal cavities or nasal fossae CFigs. 
 84 and 100) are two l^arge, irregular cavities situated on either sidfe of th& middle 
 line of the face, extending from the base of the craniiim to the roof of the 
 mouth, and separated from each other by a thin vertical g^ptuffi; the Bepfcuni; of 
 the nose (septum nasi osseum), formed by the perpendicular plate of the ethmoid 
 and by the vomer. Each cavity communicates by a large aperture, the anterior 
 nasal aperture (apertura pyriformis) ^ with the front of the face, and by the two 
 posterior nares {choanae) with the naso-pharynx behind. These fossse are much 
 
 1 Quain, Testut, and others give the apex of the orbit as oorresponding with the inner end of the sphenoidal 
 fissure. It seentis better, however, to adopt the statement in the text, since the muscles of the eyeball take 
 origin around the optic foramen, and diverge from it to the globe of the eye. 
 
 2 In the skull freed of soft parts, the anterior nasal cavities open in front by the apertura pyriformis. In the 
 skull with the soft parts in place they open by the antenoi nares 
 
THE ANTERIOR REGION OF THE SKULL 143 
 
 narrower above than below, and in the middle than at the anterior or posterior 
 openings; their depth, which is considerable, is much greater in the middle than at 
 either extremity. "The nasal fossae are surrounded by four other fossae — above is 
 the cranial fossa; laterally, the orbital fossae; and below, the cavity of the mouth."^ 
 Each nasal fossa communicates with four sinuses, the frontal above, the sphenoidal 
 behind, and the maxillary and ethmoidal on the outer wall. Each fossa also com- 
 municates with four cavities: with the orbit by the lachrymal groove, with the 
 mouth by the anterior palatine canal, with the cranium by the olfactory foramina, 
 and with the spheno-maxillary fossa by the spheno-palatine foramen ; and they occa- 
 sionally communicate with each other by an aperture in the septum. The bones 
 entering into their formation are fourteen in number: three of the cranium, the 
 frontal, sphenoid, and ethmoid, and all the bones of the face, excepting the malar 
 and lower jaw. Each cavity is bounded by a roof, a floor, an inner and an outer wall. 
 
 Upper Wall. — The upper wall, or roof (Fig. 101), is long, narrow, and horizontal 
 in its centre, but slopes downward at its anterior and posterior extremities; it is 
 formed in front by the nasal bones and nasal spine of the frontal, which are 
 directed downward and forward; in the middle, by the cribriform plate of the 
 ethmoid, which is horizontal; and behind, by the under surface of the body of the 
 sphenoid and sphenoidal turbinated bones, the ala of the vomer and the sphenoidal 
 process of the palate bone, which are directed downward and backward. This 
 surface presents, from before backward, the internal aspect of the nasal bones; 
 on their outer side, the suture formed between the nasal bone and the nasal process 
 of the superior maxillary; on their inner side, the elevated crest which receives the 
 nasal spine of the frontal and the perpendicular plate of the ethmoid, and articu- 
 lates with its fellow of the opposite side; whilst the surface of the bones is perforated 
 by a few small vascular apertures, and presents the longitudinal groove for the 
 nasal nerve; farther back is the transverse suture, connecting the frontal with the 
 nasal in front, and the ethmoid behind, the olfactory foramina and nasal slit on 
 the under surface of the cribriform plate, and the suture between it and the sphe- 
 noid behind; quite posteriorly are seen the sphenoidal turbinated bones, the ori- 
 fices of the sphenoidal sinuses, and the articulation of the alse of the vomer with 
 the under surface of the body of the sphenoid. 
 
 Floor (Figs. 84, 100, and 101) . — The floor is flattened from before backward, 
 concave from side to side, and wider in the middle than at either extremity. It 
 is formed in front by the palate process of the superior maxillary; behind, by the 
 I palate process of the palate bone. This surface presents, from before backward, 
 the anterior nasal spine ; behind this, the upper orifices of the anterior palatine canal ; 
 [internally, the elevated crest which articulates with the vomer; and behind, the 
 suture between the palate and superior maxillary bones, and the posterior nasal spine. 
 
 Inner or Medial Wall. — The inner wall, or septum (Figs. 101 and 103), is a thin 
 vertical partition which separates the nasal fossae from each other; it is occasionally 
 .perforated, so that the fossje communicate, and it is frequently deflected consid- 
 erably to one side.^ It is formed, in front, by the crest of the nasal bones and 
 [nasal spine of the frontal; in the middle, by the perpendicular plate of the ethmoid; 
 [behind, by the vomer and rostrum of the sphenoid; below, by the crests of the 
 superior maxillary and palate bones. It presents, in front, a large, triangular 
 [notch, which receives the septal cartilage of the nose; and behind, the grooved 
 [edge of the vomer. Its surface is marked by numerous vascular and nervous 
 [canals and the groove for the naso-palatine nerve, and is traversed by sutures 
 [connecting the bones of which it is formed. 
 
 Outer or Lateral Wall. — The outer wall (Figs. 84 and 101) is formed, in front, 
 [by the nasal process of the superior maxillary and lachrymal bones; in the middle, 
 
 1 Howard A. Lothrop, in Annals of Surgery, May, 1903. '^ See footnote, p. 99. 
 
144 
 
 THE SKELETON 
 
 by the ethmoid and inner surface of the body of the superior maxillary and inferior 
 turbinated bones; behind, by the vertical plate of the palate bone and the internal 
 pterygoid plate of the sphenoid. Upon this outer wall are two marked projections 
 
 UNCIFORM 
 
 PROCESS OF 
 
 ETHMOID 
 
 INFERIOR 
 TURBINATED 
 
 THIRD MOLAR 
 TOOTH 
 
 MIDDLE 
 TURBINATED 
 
 Fig. 101. — Coronal section of the face, passing through the third molar tooth. (Poirier and Charpy.) 
 
 of bone (Figs. 84 and 101). One is known as the inferior turbinated bone and the 
 other as the middle turbinated bone. The superior turbinated bones or bodies appear 
 
 ANTRUM O 
 HIGHMOR 
 
 STLE PASSED THROUGH 
 FUNDIBULUM FROM 
 ONTAL SINUS TO 
 DOLE MEATUS 
 
 PROBE PASSED 
 THROUGH LACH- 
 RYMAL CANAL 
 
 RONTAL CANAL 
 
 f— NASAL CANAL 
 
 Fig. 102. — Cranial section through the frontal sinus and nasal fossa. (Poirier and Charpy.) 
 
 as less distinct bony projections. This surface presents three irregular longitudinal 
 passages, or meatuses, termed the superior, middle, and inferior meatuses of the 
 nose (Figs. 84, 101, and 102). The superior meatus {meatus nasi superior), the 
 
THE ANTERIOR REGION OF THE SKULL 
 
 145 
 
 smallest of the three, is situated at the upper and back part of each nasal fossa, occu- 
 pying the posterior third of the outer wall. It is situated between the superior 
 turbinated bone, and has opening into it two foramina, the spheno-palatine foramina 
 at the back of its outer wall, and the posterior ethmoidal cells at the front part of 
 the outer wall. The sphenoidal sinus opens into a recess, the spheno -ethmoidal 
 recess {recessus sphenoethmoidalis) , which is situated above and behind the 
 superior turbinated bone. The middle meatus (meatus nasi medius) is situated 
 external to the middle turbinated bone, and above the inferior turbinated bone, 
 and extends from the anterior end of the inferior turbinated bone to the spheno- 
 palatine foramen of the outer wall of the nasal fossa. Anteriorly it terminates in 
 a depression, the atrium of the nasal meatus. The bulla ethmoidalis, an elevated 
 area disclosed by removing the middle turbinated bone. Below and in front of the 
 bulla is a groove, the semilunar hiatus (hiatus semilunaris) , into which open the 
 antrum and the anterior ethmoidal cells. The middle meatus presents in front 
 the orifice of the infundibulum (infundibulum ethmoidale) , by which the middle 
 meatus communicates with the anterior ethmoidal cells, and through these with 
 
 Crest of nasal bone 
 
 Nasal spine of 
 frontal bone. 
 
 Space for triangular^ 
 cartilage of septum^ 
 
 Crest of palate bone. 
 I Crest of superior maxilla. 
 
 Fig. 103. — Inner wall of nasal fossse, or septum of nose. 
 
 the frontal sinuses. The middle ethmoidal cells also open into this meatus, while 
 at the centre of the outer wall is the orifice of the maxillary antrum (hiatus maxil- 
 laris), which varies somewhat as to its exact position in different skulls. The 
 inferior meatus (meatus nasi inferior), the largest of the three, is the space between 
 the inferior turbinated bone and the floor of the nasal fossa. It extends along 
 the entire length of the outer wall of the nose, is broader in front than behind, 
 and presents anteriorly the lower orifice of the canal for the nasal duct (canalis 
 nasolacrimalis). The anterior nares present a heart-shaped or pyriform opening 
 (apertura piriformis) whose long axis is vertical and narrow extremity upward. 
 This opening in the recent state is much contracted by the cartilages of the nose. 
 It is bounded above by the inferior border of the nasal bone; laterally by the thin, 
 sharp margin which separates the facial from the nasal surface of the superior 
 
 10 
 
146 
 
 THE SKELETON 
 
 maxillary bone; and below by the same border, where it slopes inward to join its 
 fellow of the opposite side at the anterior nasal spine. The posterior naxes, or 
 choance, are the two posterior oval openings of the nasal fossae, by which they 
 communicate with the upper part of the naso-pharynx. They are situated imme- 
 diately in front of the basilar process, and are bounded above by the under 
 surface of the body of the sphenoid and alse of the vomer; below, by the posterior 
 border of the horizontal plate of the palate bone; externally, by the inner surface 
 of the internal pterygoid plate; and internally, in the middle line, they are 
 separated from each other by the posterior border of the vomer. 
 
 Difference in Size and Form of the Cranium. — These differences are thus 
 set forth by Mr. Arthur Thomson in Professor D. J. Cunningham's Text-book 
 of Anatomy: 
 
 Microcephalic skulls have a capacity of less than 1350 c.c. Mesocephalic skulls 
 have a capacity of from 1350 c.c. to 1450 c.c. Megacephalic skulls have a capacity 
 over 1450 c.c. 
 
 What is known as the cephalic index is the proportion borne by the greatest 
 
 breadth of the skull to the greatest length, assuming that the latter is equal to 100. 
 
 Thomson gives the following formula: 
 
 Maximum length X 100 i i- • i 
 
 . , j-j = cephalic mdex. 
 
 maximum breadth 
 
 The cephalic index is used to determine the form of the skull : Dolichocephalic 
 (long antero-posterior diameter) (Figs. 105 and 107), having a cephalic index 
 
 Fig. 104. — Brachycephalic cranium. 
 (Poirier and Charpy.) 
 
 Fig. 105. — Dolichocephalic cranium. 
 (Poirier and Charpy.) 
 
 Fig. 106. — Brachycephalic cranium. 
 (Poirier and Charpy.) 
 
 Fig. 107. — Dolichocephalic cranium. 
 Poirier and Charpy.) 
 
THE ANTERIOR REGION OF THE SKULL 147 
 
 below 75. Mesaticephalic (median head), having a cephahc index from 75 to 80. 
 Brachycephahc (short antero-posterior diameter) (Figs. 104 and 106), having a 
 cephalic index over 80. 
 
 Surface Form. — The various bony prominences or landmarks which are to be easily felt and 
 recognized in the head and face, and which afford the means of mapping out the important 
 structures comprised in this region, are as follows: 
 
 1. Supraorbital arch. 8. Parietal eminences. 
 
 2. Internal angular process. 9. Temporal ridge. 
 
 3. External angular process. 10. Frontal eminences. 
 
 4. Zygomatic arch. 11. Superciliary ridges. 
 
 5. Mastoid process. 12. Nasal bones. 
 
 6. External occipital protuberance. 13. Lower margin of orbit. 
 
 7. Superior curved line of occipital bone. 14. Lower jaw. 
 
 1 . The supraorbital arches are to be felt throughout their entire extent, covered by the eye- 
 brows. They form the upper boundary of the circumference or base of the orbit, and separate 
 the face from the forehead. They are strong and arched, and terminate internally on each side 
 of the root of the nose in the internal angular process, which articulates with the lachrymal 
 bone. Externally they terminate in the external angular process, which articulates with the 
 malar bone. This arched ridge is sharper and more defined in its outer than in its inner half, 
 and forms an overhanging process which protects and shields the lachrymal gland. It thus pro- 
 tects the eye in its most exposed situation and in the direction from which blows are most likely 
 to descend. The supraorbital arch varies in prominence in different individuals. It is more 
 marked in the male than in the female, and in some races of mankind than others. In the less 
 civilized races, as the forehead recedes backward, the supraorbital arch becomes more prominent, 
 and approaches more to the characters of the monkey tribe, in which the supraorbital arches are 
 very largely developed, and acquire additional prominence from the oblique direction of the 
 frontal bone. 2. The internal angular process is scarcely to be felt. Its position is indicated 
 by the angle formed by the supraorbital arch with the nasal process of the superior maxillary 
 bone and the lachrymal bone at the inner side of the orbit. Between the internal angular pro- 
 cesses of the two sides is a broad surface which assists in forming the root of the nose, and 
 immediately above this a broad, smooth, somewhat triangular surface, the glabella, situated 
 between the superciliary ridges. 3. The external angular process is much more strongly marked 
 than the internal, and is plainly to be felt. It is formed by the junction or confluence of the supra- 
 orbital and temj)oral ridges, and, articulating with the malar bone, it serves to a very consider- 
 able extent to support the bones of the face. In carnivorous animals the external angular pro- 
 cess does not articulate with the malar, and therefore this lateral support to the bones of the face 
 is not present. 4. The zygomatic arch is plainly to be felt throughout its entire length, being 
 situated almost immediately under the skin. It is formed by the malar bone and the zygomatic 
 process of the temporal bone. At its anterior extremity, where it is formed by the malar bone, 
 it is broad and forms the prominence of the cheek; the posterior part is narrower, and termi- 
 nates just in front and a little above the tragus of the external ear. The lower border is 
 more plainly to be felt than the upper, in consequence of the dense temporal fascia being 
 attached to the latter, which somewhat obscures its outline. Its shape differs very much in indi- 
 viduals and in different races of mankind. In the most degraded type of skull — as, for instance, 
 in the skull of the negro of the Guinea Coast — the malar bones project forward and not outward, 
 and the zygoma at its posterior extremity extends farther outward before it is twisted on itself to 
 be prolonged forward. This makes the zygomatic arch stand out in bold relief, and affords 
 greater space for the Temporal muscle. In skulls which have a more pyramidal shape, as in the 
 Esquimaux or Greenlander, the malar bones do not project forward and downward under the 
 eyes, as in the preceding form, but take a direction outward, forming with the zygoma a large, 
 rounded sweep or segment of a circle. Thus it happens that if two lines are drawn from the 
 zygomatic arches, touching the temporal ridges, they meet above the top of the head, instead of 
 being parallel, or nearly so, as in the European skull, in which the zygomatic arches are not 
 nearly so prominent. This gives to the face a more or less oval type. 5. Behind the ear is the 
 mastoid portion of the temporal bone, plainly to be felt, and terminating below in a nipple- 
 shaped process. Its anterior border can be traced immediately behind the concha, and its apex 
 is on about a level with the lobule of the ear. It is rudimentary in infancy, but gradually 
 develops in childhood, and is more marked in the negro than in the European. 6. The external 
 occipital protuberance is always plainly to be felt just at the level where the skin of the neck 
 joins that of the head. At this point the skull is thick for the purposes of safety, while radiating 
 from it are numerous curved arches or buttresses of bone which give to this portion of the 
 skull further security. 7. Running outward on either side from the external occipital protu- 
 berance is an arched ridge of bone, which can be more or less plainly perceived. This is the 
 superior curved line of the occipital bone, and gives attachment to some of the muscles which 
 
148 THE SKELETON 
 
 keep the head erect on the spine; accordingly, we find it more developed in the negro tribes, in 
 whom the jaws are much more massive, and therefore require stronger muscles to prevent their 
 extra weight carrying the head forward. Below this line the surface of hone at the back of the 
 head is obscured by the overlying muscles. Above it, the vault of the cranium is thinly covered 
 with soft structures, so that the form of this part of the head is almost exactly that of the upper 
 partion of the occipital, the parietal, and the frontal bones themselves; and in bald persons, 
 even the lines of junction of the bones, especially the junction of the occipital and parietal at 
 the lambdoid suture, may be defined as a slight depression, caused by the thickening of the 
 borders of the bones in this situation. 8. In the line of the greatest transverse diameter of the 
 head, on each side of the middle line, are generally to be found the parietal eminences, one on 
 each side of the middle line, though sometimes these eminences are not situated at the point of 
 the greatest transverse diameter, which is at some other prominent part of the parietal region. 
 They denote the point where ossification of the parietal bone began. They are much more 
 prominent and well-marked in early life, in consequence of the sharper curve of the bone at 
 this period, so that it describes the segment of a smaller circle. Later in life, as the bone grows, 
 the curve spreads out and forms the segment of a larger circle, so that the eminence becomes 
 less distinguishable. In consequence of this sharp curve of the bone in early life, the whole of 
 the vault of the skull has a squarer shape than it has in later life, and this appearance may per- 
 sist in some rickety skulls. The eminence is more apparent in the negro's skull than in that of 
 the European. This is due to greater flattening of the temporal fossa in the former skull to 
 accommodate the larger Temporal muscle which exists in these races. The parietal eminence 
 is particularly exposed to injury from blows or falls on the head, but fracture is to a certain 
 extent prevented by the shape of the bone, which forms an arch, so that the force of the blow 
 is diffused over the bone in every direction. 9. At the side of the head may be felt the temporal 
 ridge. Commencing at the external angular process, it may be felt as a curved ridge, passing 
 upward and then curving backward, on the frontal bone, separating the forehead from the 
 temporal fossa. It may then be traced passing backward in a curved direction, over the parietal 
 bone, and, though less marked, still generally to be recognized. Finally, the ridge curves down- 
 ward, and terminates in the posterior root of the zygoma, which separates the squamous from 
 the subcutaneous mastoid portion of the temporal bone. Sir Victor Horsley has recently shown 
 in an article on the "Topography of the Cerebral Cortex," that the second temporal ridge (see 
 page 76) can be made out on the living body. 10. The frontal eminences vary a good deal in 
 different individuals, being considerably more prominent in some than in others, and they are 
 often not symmetrical on the two sides of the body, the one being much more pronounced than 
 the other. This is often especially noticeable in the skull of the young child or infant, and 
 becomes less marked as age advances. The prominence of the frontal eminences depends 
 more upon the general shape of the whole bone than upon the size of the protuberances them- 
 selves. As the skull is more highly developed in consequence of increased intellectual capacity, 
 so the frontal bone becomes more upright and the frontal eminences stand out in bolder relief. 
 Thus they may be considered as affording, to a certain extent, an indication of the development 
 of the hemispheres of the brain beneath, and of the mental powers of the individual. They 
 are not so much exposed to injury as the parietal eminences. In falls forward the upper extrem- 
 ities are involuntarily thrown out, and break the force of the fall, and thus shield the frontal 
 bone from injury. 11. Below the frontal eminences on the forehead are the superciliary ridges, 
 which denote the position of the frontal sinuses, and vary according to the size of the sinuses 
 in difTerent individuals, being, as a rule, small in the female, absent in children, and some- 
 times unusually prominent in the male, when the frontal sinuses are largely develo])ed. They 
 commence on either side of the glabella, and at first present a rounded form, which gradually 
 fades away at their outer ends. 12. The nasal bones form the prominence of the nose. They 
 vary much in size and shape, and to them is due the varieties in the contour of this organ and 
 much of the character of the face. Thus, in the Mongolian or Ethiopian they are flat, broad, 
 and thick at their base, giving to these races the flattened nose by which they are characterized, 
 and differing very decidedly from the Caucasian, in whom the nose, owing to the shape of the ■ 
 nasal bones, is narrow, elevated at the bridge, and elongated downward. Below, the nasal 
 bones are thin and connected with the cartilages of the nose, and the angle or arch formed by ' 
 their union serves to throve out the bridge of the nose, and is much more marked in some indi- 
 viduals than others. 13. The lower margin of the orbit, formed by the superior maxillary bone 
 and the malar bone, is plainly to be felt throughout its entire length. It is continuous inter- i 
 nally with the nasal process of the superior maxillary bone, which forms the inner boundary 
 of the orbit. At the point of junction of the lower margin of the orbit with the nasal process 
 is to be felt a little tubercle of bone, which can be plainly perceived by running the finger along 
 the bone in this situation. This tubercle serves as a guide to the position of the lachrymal sac, 
 which is situated above and behind it. 14. The outline of the lower jaw is to be felt throughout 
 its entire length. Just in front of the tragus of the external ear, and below the zygomatic arch, 
 the condyle can be made out. When the mouth is opened this prominence of bone can be per- 
 ceived advancing out of the glenoid fossa on to the eminentia articularis, and receding again 
 
THE ANTERIOR REGION OF THE SKULL 149 
 
 when the mouth is closed. From the condyle the posterior border of the ramus can be felt 
 extending down to the angle. A line drawn from the condyle to the angle would indicate the 
 exact position of this border. From the angle to the symphysis of the chin the lower, rounded 
 border of the body of the bone is plainly to be felt. At the point of junction of the two halves 
 of the bone is a well-marked triangular eminence, the mental process, which forms the promi- 
 nence of the chin. 
 
 Fixed Points for Measurement. — In order to determine the location of regions of surgical 
 importance within the skull (bony spaces, vessels, fissures, centres, and convolutions of the 
 i)rain) and in order to estimate cranial capacity, measurements are made and these measure- 
 ments are taken from fixed points. The following are the chief fixed points: 
 
 The Nasion. The middle of the naso-frontal suture. 
 
 The Glabella. Midway between the two superciliary ridges. 
 
 The Obelion. A point in the sagittal suture between the parietal foramina. 
 
 The IxiON. The external occipital protuberance. 
 
 The Basion. The middle of the anterior edge of the foramen magnum. 
 
 The Opisthion. The middle of the posterior edge of the foramen magnum. 
 
 The Lambda. The point of junction of the sagittal and lambdoid sutures. 
 
 The Pterion. The site of the antero-lateral fontanelle, where the frontal, parietal, squa- 
 mous portion of the temporal and greater wing of the sphenoid are in relation. 
 
 The AsTERiON. The region of the postero-lateral fontanelle, at the posterior inferior margin 
 of the parietal bone. 
 
 The Bregma. The site of the anterior fontanelle, where the sagittal and coronal sutures 
 meet. 
 
 The Superior Stephanion. The point where the superior temporal ridge meets the coronal 
 suture. 
 
 The Inferior Stephanion. The point where the inferior temporal ridge meets the coronal 
 suture. 
 
 The GoNiON. The outer surface of the angle of the mandible. 
 
 The Ophryon. The middle of the narrowest transverse diameter of the forehead. 
 
 The Vertex. The highest point of the vault of the skull. 
 
 Besides these points we use the mastoid process, the nasal spine, the zygomatic arch, the 
 frontal eminences, the parietal eminences, the supraorbital ridges, the superciliary ridges, the 
 mental process, suprameatal spine, the external and internal angular processes, and the canine 
 fossa. 
 
 Surgical Anatomy. — The thickness of the skull varies greatly in different regions of the same 
 skull and in different individuals. The average thickness of the skull-cap is about one-fifth 
 of an inch. The thickest portions are the occipital protuberance, the inferior portion of the 
 frontal bone, and the mastoid process. The thinnest portions are the occipital fossae, the squa- 
 mous portion of the temporal bone, and over certain sinuses and arteries. An arrest in the 
 ossifying process may give rise to deficiencies or gaps, or to fissures, which are of importance 
 in a medico-legal point of view, as they are liable to be mistaken for fractures. The fissures 
 generally extend from the margin toward the centre of the bone, but gaps may be found in the 
 middle as well as at the edges. In course of time they may become covered with a thin lamina 
 of bone. 
 
 Occasionally a protrusion of the brain or its membranes may take place through one of these 
 gaps in an imperfectly developed skull. When the protrusion consists of membranes only, and 
 is filled with cerebro-spinal fluid, it is called a meningocele ; when the protrusion consists of brain 
 as well as membranes, it is termed an enCGphalocele and when the protruded brain is a prolonga- 
 tion from one of the ventricles, and is distended by a collection of fluid from an accumulation in 
 the ventricle, it is termed an hydrencephalocele. This latter condition is sometimes found at the 
 root of the nose, where a protrusion of the anterior horn of the lateral ventricle takes place 
 through a deficiency of the fronto-nasal suture. These malformations are usually found in the 
 middle line, and most frequently at the back of the head, the protrusion taking place through 
 the fissures which separate the four centres of ossification from w-hich the tabular portion of the 
 occipital bone is originally developed (see page 75). They most frequently occur through the 
 upper part of the vertical fissure, which is the last to ossify, but not uncommonly through the 
 lower part, when the foramen magnum may be incomplete. More rarely these protrusions 
 have been met with in other situations than those above mentioned, both through normal 
 fissures, as the sagittal, lambdoid, and other sutures, and also through abnormal gaps and 
 deficiencies at the sides, and even at the base of the skull. Force may be responsible in a young 
 person for separating a suture. This accident, seldom met with even in the young, is only occa- 
 sionally encountered in older persons. 
 
 Fractures of the skull may be divided into those of the vault and those of the base. Frac- 
 tures of the vault are usually produced by direct violence. This portion of the skull varies in 
 thickness and strength in different individuals, but, as a rule, is sufficiently strong to resist a very 
 considerable amount of violence without being fractured. This is due to several causes: the 
 
150 THE SKELETON 
 
 rounded shape of the head and its construction of a number of secondary elastic arches, each 
 made up of a single bone; the fact that it consists of a number of bones, united, at all events in 
 early life, by a sutural ligament, which acts as a sort of buffer and interrupts the continuity of 
 any violence applied to the skull ; the presence of arches or ridges, both on the inside and outside 
 of the skull, which materially strengthen it; and the mobility of the head upon the spine, which 
 further enables it to withstand violence. The elasticity of the bones of the head is especially 
 marked in the skull of the child, and this fact, together with the wide separation of the indi- 
 vidual bones from each other, and the interposition between them of other and softer structures 
 render fracture of the bones of the head a very uncommon event in infants and quite young 
 children; as age advances and the bones become joined, fracture is more common, though still 
 less liable to occur than in the adult. Fractures of the vault may, and generally do, involve the 
 whole thickness of the bone; but sometimes one table may be fractured without any correspond- 
 ing injury to the other. Thus, the outer table of the skull may be splintered and driven into the 
 diploe, or in the frontal or mastoid regions into the frontal or mastoid cells, without any injury 
 to the internal table. And on the other hand, the internal table has been fractured, and por- 
 tions of it depressed and driven inward, without any fracture of the outer table. As a rule, in 
 fractures of the skull the inner table is more splintered and comminuted than the outer, and 
 this is due to several causes. It is thinner and more brittle; the force of the violence as it passes 
 inward becomes broken up, and is more diffused by the time it reaches the inner table; the 
 bone, being in the form of an arch, bends as a whole and spreads out, and thus presses the 
 particles together on the convex surface of the arch — i. e., the outer table — and forces them 
 asunder on the concave surface or inner table; and, lastly, there is nothing firm under the inner 
 table to support it and oppose the force. Fractures of the vault may be simple fissures or starred 
 and comminuted fractures, and these may be depressed or elevated. These latter cases of 
 fracture with elevation of the fractured portion are uncommon, and can only be produced by 
 direct wound. In comminuted fracture a portion of the skull is broken into several pieces, 
 the lines of fracture radiating from a centre where the chief impact of the blow was felt; if 
 depressed, a fissure circumscribes the radiating line, enclosing a portion of skull. If this area 
 is circular, it is termed a pond fracture, and would in all probability have been caused by 
 a round instrument, as a life-preserver or hammer; if elliptical in shape, it is termed a gutter 
 fracture, and would owe its shape to the instrument which had produced it, as a poker. A 
 fracture may take place along the line of an ossified or partly ossified suture. When a surgeon 
 explores the vault of the skull through a wouftd he must not mistake a Wormian bone for a frag- 
 ment produced by a fracture. A Wormian bone which may lead to mistake is encountered at 
 the anterior inferior angle of the parietal bone. Wormian bones are most frequently found 
 along the lambdoid suture. 
 
 Fractures of the base are most frequently produced by the extension of a fissure from the 
 vault, as in falls on the head, where the fissure starts from the part of the vault which first 
 struck the ground. Sometimes, however, they are caused by direct violence, when foreign 
 bodies have been forced through the thin roof of the orbit, through the cribriform plate of the 
 ethmoid from being thrust up the nose, or through the roof of the pharynx. Other cases of 
 fracture of the base occur from indirect violence, as in fracture of the occipital bone from impac- 
 tion of the spinal column against its condyles in falls on the buttocks, knees, or feet, or in cases 
 where the glenoid cavity has been fractured by the violent impact of the condyle of the lower jaw 
 against it from blows on the chin. 
 
 The most common place for fracture of the base to occur is through the middle fossa, and 
 here the fissure usually takes a fairly definite course. Starting from the point struck, which is 
 generally somewhere in the neighborhood of the parietal eminence, it runs downward through the 
 parietal bone and the squamous portion of the temporal bone and across the petrous portion of this 
 bone, frequently traversing and implicating the internal auditory meatus, to the middle lacerated 
 foramen. From this it may pass across the body of the sphenoid, through the pituitary fossa to 
 the middle lacerated foramen of the other side, and may indeed travel round the whole cranium, 
 so as to completely separate the anterior from the posterior part. The course of the fracture 
 should be borne in mind, as it explains the symptoms to which fracture in this region may give 
 rise; thus, if the fissure pass across the internal auditory meatus, injury to the facial and auditory 
 nerves may result, with consequent facial paralysis and deafness; or the tubular prolongation 
 of the arachnoid around these nerves in the meatus may be torn, and thus permit of the escape 
 of the cerebro-spinal fluid should there be a communication between the internal ear and the 
 tympanum and the membrana tympani be ruptured, as is frequently the case; again, if the 
 fissure passes across the pituitary fossa and the muco-periosteum covering the under surface 
 of the body of the sphenoid is torn, blood will find its way into the pharynx and be swallowed, 
 and after a time vomiting of blood will result. Fractures of the anterior fossa, involving the 
 bones forming the roof of the orbit and nasal fossa, are generally the results of blows on the fore- 
 head; but fracture of the cribriform plate of the ethmoid may be a complication of fracture of 
 the nasal bone. When the fracture implicates the roof of the orbit, the blood finds its way 
 into this cavity, and, travelling forward, appears as a subconjunctival ecchymosis. Subcon- 
 
THE ANTERIOR REGION OF THE SKULL 
 
 151 
 
 junctival ecchyraosis can also be caused by fracture of the malar bone. If the roof of the nasal 
 fossa be fractured, the blood escapes from the nose. In rare cases there may be also escape of 
 cerebro-spinal fluid from the nose where the dura mater and arachnoid have been torn. In 
 fractures of the posterior fossa extravasation of blood takes place beneath the deep fascia and 
 discoloration of the skin is soon observed in the course of the posterior auricular artery, the dis- 
 coloration first appearing in the skin over the tip of the mastoid process of the temporal bone 
 (Battle's sign). Some of the blood which was extra vasated beneath the deep fascia approaches 
 the surface through the openings in the deep fascia for the passage of vessels and nerves. 
 
 The bones of the skull are frequently the seat of nodes, and not uncommonly necrosis results 
 from this cause, also from injury. Necrosis may involve the entire thickness of the skull, but 
 is usually confined to the external table. Necrosis of the internal table alone is rarely met with. 
 The bones of the skull are also sometimes the seat of sarcomatous tumor. 
 
 The skull in rickets is peculiar: the forehead is high, square, and projecting, and the antero- 
 posterior diameter of the skull is long in relation to the transverse diameter. The bones of the 
 face are small and ill-developed, and this gives the appearance of a larger head than actually 
 exists. The bones of the head are often thick, especially in the neighborhood of the sutures, 
 and the anterior fontanelle is late in closing, sometimes remaining unclosed till the fourth year. 
 The condition of craniotabes has by some been also believed to be the result of rickets, by others 
 is believed to be due to inherited syphilis. In all probability it is due to both. In these cases 
 the bone undergoes atrophic changes in patches, so that it becomes greatly thinned in places, 
 generally where there is pressure, as from the pillow or nurse's arm. It is, therefore, usually 
 met with in the parietal bone and vertical plate of the occipital bone. 
 
 In congenital syphilis deposits of porous bone are often found at the angles of the parietal 
 bones and two halves of the frontal bone which bound the anterior fontanelle. These deposits 
 are separated by the coronal and sagittal sutures, and give to the skull an appearance like a hot 
 cross bun. They are known as Parrot's nodes, and such a skull has received the name of nati- 
 form, from its fancied resemblance to the buttocks. When the surgeon wishes to effect an entrance 
 into the interior of the mastoid antrum (Fig. 108) he applies his bur or gouge in the swprameatal 
 triangle 1 cm. posterior to the suprameatal spine, being careful to keep below the posterior root of 
 the zygoma and the level of the superior wall of the bony meatus. If the instrument is entered 
 at a higher level it will open the cerebral cavity; the instrument should be carried inward, for- 
 ward, and a little upward, that is, in the direction of the auditory canal. The antrum is usually 
 reached after the penetration of from 1 to 1^ cm. of bone. The depth at which the antrum is sit- 
 uated is not constant. "It is safe to say that if the instrument penetrates deeper than 1^ cm. and 
 be directed too far forward or downward, the horizontal semicircular canal or the aqujeduetus 
 Fallopii will be encountered. If the 
 former were opened in a purulent otitis 
 media the pus would travel along it to 
 the vestibule and from there into the 
 internal auditory meatus, producing a 
 pachymeningitis or extradural (epidural) 
 abscess of the posterior fossa of the skull ; 
 or from the vestibule through the perpen- 
 dicular semicircular canal, which if ac- 
 companied by erosion of its bony cover- 
 ing would lead to involvement of the 
 meninges of the middle fossa; the same 
 would hold good for the posterior semi- 
 circular canal, affecting the posterior 
 fossa. If the latter (the aquseductus Fal- 
 lopii) were opened an inflammation of 
 the facial nerve which is contained there- 
 in would result, producing paralysis of 
 that side of the face. The inflammatory 
 process might also find its way through 
 the entire canal to the internal auditory 
 meatus, causing a pachymeningitis or 
 extradural abscess as mentioned above; 
 or, travelling along the nerve to its cere- 
 bral attachment, would produce a men- 
 ingitis or subdural (intradural) abscess. 
 The direction of the penetrating instru- 
 ment must also V)e forward, in order to avoid injuring the lateral dnus" ("Anatomy and Sur- 
 gerv of the Temporal Bone," bv A. E. Schmitt, M.D., American Journal of the Medical Sciences, 
 April, 1903). In the operation for infective thrombosis of the lateral sinus the sinus is deliber- 
 ately exposed and opened (Fig. 108). 
 
 Fig. 108. — Division of the mastoid process into four equal 
 parts. An opening in the upper anterior quadrant reaches the 
 mastoid antrum ; into the upper posterior quadrant reaches 
 the lateral sinus ; the lower anterior quadrant into mastoid 
 cells ; a superficial opening into the lower posterior quadrant 
 reaches mastoid cells ; a deep opening reaches the descending 
 limb of the lateral sinus. (A. E. Schmitt.) 
 
152 THE SKELETON 
 
 Hartley divides the mastoid process into four parts as follows: The upper margin is the 
 posterior root of the zygoma. The anterior margin is the anterior border of the mastoid. The 
 posterior margin is a vertical line dropped from the masto-occipital junction. The lower mar- 
 gin is an imaginary line backward from the mastoid tip. This space is divided into four equal 
 parts. Points upon it may be designated as on a map. Take the left side for demonstration. 
 An opening in the N. W. quadrant enters the antrum, one into the N. E. quadrant exposes the 
 lateral sinus, one into the S. W. quadrant enters mastoid cells, and a superficial one into the 
 S. E. quadrant enters mastoid cells, but a deep one exposes the descending portion of the lateral 
 sinus. 
 
 When pus breaks through the mastoid process it may enter the sheath of the digastric or sterno- 
 cleido-mastoid muscle and point a considerable distance away from the bone, Bezold's abscesS; 
 
 In connection with the bones of the face a common malformation is cleft palate, owing to 
 the non-union of the palatal processes of the maxillary or pre-oral arch. This cleft may involve 
 the whole or only a portion of the hard palate, and usually involves the soft palate also. The 
 cleft is in the middle line, except it involves the alveolus in front, when it follows the suture 
 between the main portion of the bone and the pre-maxillary bone. Sometimes the cleft runs 
 on either side of the pre-maxillary bone, so that this bone is quite isolated from the maxillary 
 bones and hangs from the end of the vomer. In such a case the pre-maxillary bone usually 
 contains the germs of the central incisors only. In some cases there is no pre-maxillary bone 
 and the great gap in the lip is in the median line. Cleft palate (Fig. 92) is usually associated 
 with hare-lip, which, when single, is almost always on one side, corresponding to the position 
 of the suture between the lateral incisor and canine tooth. Some few cases of median hare- 
 lip have been described. In double hare-lip there is a cleft on each side of the middle line (see 
 page 111). 
 
 The outlines and the height of the arch of the palate vary greatly in different persons. A 
 narrow palate with a high arch is common in idiots and certain degenerates. 
 
 The bones of the face are sometimes fractured as the result of direct violence. The two 
 most commonly broken are the nasal bone and the mandible, and of these the latter is by 
 far the most frequently fractured of all the bones of the face. Fracture of the nasal bone is 
 for the most part transverse, and takes place about half an inch from the free margin. The 
 broken portion may be displaced backward or more generally to one side by the force which 
 produced the lesion, as there are no muscles here which can cause displacement. The malar 
 bone is probably never broken alone; that is to say, unconnected with a fracture of the other 
 bones of the face. The zygomatic arch is occasionally fractured, and when this occurs from 
 direct violence, as is usually the case, the fragments may be displaced inward. This lesion is 
 often attended with great difficulty or even inability to open and shut the mouth, and this has 
 been stated to be due to the depressed fragments perforating the temporal muscle, but would 
 appear rather to be caused by the injury done to the bony origin of the Masseter muscle. 
 Fractures of the superior maxilla may vary much in degree, from the chipping off of a portion 
 of the alveolar arch, a frequent accident when the "old key" instrument was used for the 
 extraction of teeth, to an extensive comminution of the whole bone from severe violence, as 
 the kick of a horse. The most common situation for a fracture of the mandible bone is in the 
 neighborhoad of the canine tooth, as at this spot the jaw is weakened by the deep socket for 
 the fang of this tooth; it is next most frequently fractured at the angle; then at the symphysis, 
 and finally the neck of the condyle or the coronoid process may be broken. Occasionally a 
 double fracture may occur, one in either half of the bone. The fractures are usually compound, 
 from laceration of the mucous membrane covering the gums. The displacement is mainly the 
 result of the same violence as producsd the injury, but may be further increased by the action 
 of the muscles passing from the neighborhood of the symphysis to the hyoid bone. 
 
 The superior and inferior maxillary bones are both of them frequently the seat of necrosis, 
 though the disease affects the lower much more frequently than the upper jaw. It may be the 
 result of periostitis, from tooth irritation, injury, or the action of some specific poison, as syphilis, 
 or from salivation by mercury; it not infrequently occurs in children after attacks of the exan- 
 thematous fevers, and a special form occurs from the action of the fumes of phosphorus in 
 persons engaged in the manufacture of matches. 
 
 Tumors attack the jaw bones not infrequently, and these may be either innocent or malig- 
 nant: in the upper jaw cysts may occur in the antrum, constituting the so-called dropsy of the 
 antrum; or, again, cysts may form in either jaw in connection with the teeth: either cysts con- 
 nected with the roots of fully developed teeth, the "dental cyst;" or cysts connected with im- 
 perfectly developed teeth, the "dentigerous cyst." Solid innocent tumors include the fibroma, 
 the chondroma, and the osteoma. Of malignant tumors there are the endotheliomata, the 
 sarcomata, and the epitheliomata. The sarcomata are of various kinds, the spindle-celled, 
 the round-celled, which are of a very malignant character, and the myeloid sarcomata, prin- 
 cipally affecting the alveolar margin of the bone. Of the epitheliomata we find the squamous 
 variety spreading to the bone from the palate or gum, and the cylindrical epithelioma origin- 
 ating in the antrum or nasal fossae. 
 
THE HYOID OB LINGUAL BONE 153 
 
 Both superior and inferior maxillary bones occasionally require excision for tumors and in 
 some other conditions. The upper jaw is removed by an incision from the inner canthus of the 
 eye, along the side of the nose, round the ala, and down the middle line of the upper lip. A 
 second incision is carried outward from the inner canthus of the line along the lower margin of 
 the orbit as far as the prominence of the malar bone. The flap thus formed is reflected outward 
 and the surface of the bone exposed, and the central incisor of the diseased side is removed. 
 The connections of the bone to the other bones of the face are then divided with a narrow saw and 
 bone-cutting forceps. They are (1) the junction with the malar bone, passing into the spheno- 
 maxillary fissure; (2) the nasal process; a small portion of its upper extremity, connected with the 
 nasal bone in front, the lachrymal bone behind, and the frontal bone above, being left; (3) the 
 connection with the bone on the opposite side and the palate in the roof of the mouth. The 
 bone is now firmly grasped with lion-jaw forceps, and by means of a rocking movement upward 
 and downward the remaining attachments of the orbital plate with the ethmoid and the 
 back of the bone with the palate, broken through. The soft palate is first separated from 
 the hard with a scalpel, and is not removed. Occasionally in removing the upper jaw it 
 will be found that the orbital plate can be spared, and this should always be done if possible. 
 A horizontal saw-cut is to be made just below the infraorbital foramen and the bone cut through 
 with a chisel and mallet. Lockwood has pointed out that in removing the upper jaw the sur- 
 geon must be careful in dividing the nasal process of the superior maxilla to preserve the inter- 
 nal orbital or palpebral ligament (Tendo oculi), because this ligament arises from the palpebral 
 fascia, and if it is interfered with the eye will inevitably drop downward. Removal of one-half 
 of the lower jaw is sometimes required. If possible, the section of the bone should be made 
 to one side of the symphysis, so as to save the genial tubercles and the origin of the genio-hyo- 
 glossus muscle, as otherwise the tongue tends to fall backward and may produce suffocation. 
 Having extracted the central or preferably the lateral incisor tooth, a vertical incision is made 
 down to the bone, commencing at the free margin of the lip, and carried to the lower border 
 of the bone; it is then carried along its lower border to the angle and up the posterior margin 
 of the ramus to a level with the lobule of the ear. The flap thus formed is raised by separating 
 all the structures attached to the outer surface of the bone. The jaw is now sawn through 
 at the point where the tooth has been extracted, and the knife passed along the inner side of 
 the jaw, separating the structures attached to this surface. The jaw is then grasped by the 
 surgeon and strongly depressed, so as to bring down the coronoid process and enable the operator 
 to sever the tendon of the Temporal muscle. The jaw can be now further depressed, care being 
 taken not to evert it nor rotate it outward, which would endanger the internal maxillary artery, 
 and the External pterygoid muscle is torn through or divided. The capsular ligament is now 
 opened in front and the lateral ligaments divided, and the jaw removed with a few final touches 
 of the knife. 
 
 The antrum of Highmore occasionally requires tapping for suppuration. This may be done 
 through the socket of a tooth, preferably the first molar, the fangs of which are most intimately 
 connected with the antrum, or through the facial aspect of the bone above the alveolar process. 
 This latter method does not perhaps afford such efficient drainage, but there is less chance of 
 food finding its way into the cavity. The operation may be performed by incising the mucous 
 membrane above the second molar tooth, and driving a trocar or any sharp-pointed instrument 
 into the cavity. 
 
 THE HYOID OR LINGUAL BONE (OS HYOIDEUM). 
 
 The hyoid bone (Fig. 109) is named from its resemblance to the Greek upsilon; 
 it is also called the lingual hone, because it supports the tongue and gives attach- 
 ment to its numerous muscles. It is a bony arch, shaped like a horseshoe, and 
 consisting of five segments: a body, two greater comua, and two lesser comua. It 
 is suspended from the tip of the styloid processes of the temporal bone by liga- 
 mentous bands, the stylo-hyoid ligaments. 
 
 Body {corpus ossei Jnjoidei).- — The body, or basi-hyal, forms the central part 
 of the bone, and is of a quadrilateral form. 
 
 Surfaces. — Its anterior surface (Fig. 109), convex, directed forward and upward, 
 is divided into two parts by a vertical ridge which descends along the median 
 line and is crossed at right angles by a horizontal ridge, so that this surface is 
 divided into four spaces or depressions. At the point of meeting of these two lines 
 is a prominent elevation, the tubercle. The portion above the horizontal ridge is 
 directed upward, and is sometimes described as the superior border. The anterior 
 surface gives attachment to the Genio-hyoid in the greater part of its extent; above, 
 
154 
 
 THE SKELETON 
 
 THYRO-HVOIO 
 
 STYLO-HYOID. 
 
 OMO-HYOID. 
 
 GENIO-HYOID. STERNO-HYOID. MYLO-HYOIO. 
 
 Fig. 109. — Hyoid bone. Anterior surface. (Enlarged.) 
 
 to the Genio-hyo-glossus ; below, to the Mylo-hyoid, Stylo-hyoid, and aponeurosis of 
 the. Digastric (suprahyoid aponeurosis); and between these to part of the Hyo- 
 glossus. The posterior surface is smooth, concave, directed backward and down- 
 ward, and separated from the epiglottis by the thyro-hyoid membrane and by a 
 quantity of loose areolar tissue. The lateral surfaces after middle life are joined 
 to the greater cornua. In early life they are connected to the cornua by carti- 
 laginous surfaces, and held together by ligaments, and occasionally a synovial 
 membrane is found between them. 
 
 Borders. — The superior border is rounded, and gives attachment to the thyro- 
 hyoid membrane, part of the Genio-hyo-glossi and Chondro-glossi muscles. The 
 inferior border gives attachment, in front, to the Sterno-hyoid ; behind, to the Omo- 
 hyoid and to the part of the Thyro- 
 hyoid at its junction with the great 
 cornu. It also gives attachment to 
 the Levatore glandule thyroidese 
 when this muscle is present. 
 
 Greater Cornua (cornua majora) . 
 — The greater cornua or tiyro-hyals 
 project backward from the lateral 
 surfaces of the body; they are flat- 
 tened from above downward, di- 
 minish in size from before back- 
 ward, and terminate posteriorly in 
 a tubercle for the attachment of 
 the lateral thyro-hyoid ligament. 
 The outer surface gives attachment 
 to the Hyo-glossus, their upper border to the Middle constrictor of the pharynx, 
 their lower border to part of the Thyro-hyoid muscle. 
 
 Lesser Cornua (cornua minora). — The lesser cornua, or cerato-hyals, are two 
 small, conical-shaped eminences attached by their bases to the angles of junc- 
 tion between the body and greater cornua, and giving attachment by their apices 
 to the stylo-hyoid ligaments.^ The smaller cornua are connected to the body of 
 the bone by a distinct diarthrodial joint, which usually persists throughout life, 
 but occasionally becomes ankylosed. 
 
 Development. — By five centres: one for the body, and one for each cornu. 
 Ossification commences in the body about the eighth month, and in the greater 
 cornua toward the end of foetal life. Ossification of the lesser cornua commences 
 some years after birth. Sometimes there are two centres for the body. 
 
 Attachment of Muscles. — Sterno-hyoid, Thyro-hyoid, Omo-hyoid, aponeurosis 
 of the Digastric, Stylo-hyoid, Mylo-hyoid, Genio-hyoid, Genio-hyo-glossus, Chon- 
 dro-glossus, Hyo-glossus, Middle constrictor of the pharynx, and occasionally a 
 few fibres of the Inferior lingualis. It also gives attachment to the thyro-hyoidean 
 membrane and the stylo-hyoid, thyro-hyoid, and hyo-epiglottic ligaments. 
 
 Surface Form. — The hyoid bone can be felt in the receding angle below the chin, and the 
 finger can be carried along the whole length of the bone to the greater cornu, which is situated 
 just below the angle of the jaw. This process of bone is best perceived by making pressure on 
 one cornu, and so pushing the bone over to the opposite side, when the cornu of this side will 
 be distinctly felt immediately beneath the skin. This process of bone is an important landmark 
 in ligature of the lingual artery. 
 
 Surgical Anatomy.— The hyoid bone is occasionally fractured, generally from direct vio- 
 lence, as in the act of garroting or throttling. It is frequently found broken in those who have 
 been hung. The great cornu is the part of the bone most frequently broken, but sometimes 
 the fracture takes place through the body of the bone. In consequence of the muscles of the 
 
 1 These ligaments in many animals are distinct bones, and in man are occasionally ossified to a certain extent. 
 
THE STERNUM I55 
 
 tongue having important connections with this bone, there is great pain upon any attempt being 
 made to move the tongue, as in speaking or swallowing. 
 
 THE THORAX. 
 
 The thorax, or chest, is an osseo-cartilaginous cage the cavity of which (cavum 
 thoracis) contains and protects the principal organs of respiration and circula- 
 tion. It is conical in shape, being narrow above and broad below, flattened 
 from before backward, and longer behind than in front. It is somewhat 
 renifonn on transverse section. 
 
 Boundaries. — The posterior surface is formed by the twelve dorsal vertebrae and 
 the posterior part of the ribs. It is concave from above downward, and presents 
 on each side of the middle line a deep groove, the vertebral groove, in conse- 
 quence of the direction backward and outward which the ribs take from their 
 vertebral extremities to their angles. The anterior surface is flattened or slightly 
 convex, and inclined forward from above downward. It is formed by the sternum 
 and costal cartilages. The lateral surfaces are convex; they are formed by the 
 ribs, separated from each other by spaces. Each space is called an intercostal 
 space (spatium intercostale) . These are eleven in number, and are occupied by 
 the intercostal muscles. 
 
 The superior or upper opening or aperture of the thorax, the inlet (apertura 
 thoracis superior), is reniform in shape, being broader from side to side than 
 from before backward. It is formed by the first dorsal vertebra behind, the 
 upper margin of the sternum in front, and the first rib on each side. It slopes 
 downward and forward, so that the anterior part of the ring is on a lower level 
 than the posterior. The antero-posterior diameter is about two inches, and the 
 transverse al)out four. The inferior or lower opening (apertura thoracis inferior) 
 is formed by the twelfth dorsal vertebra behind, by the twelfth rib at the sides, 
 and in front by the cartilages of the eleventh, tenth, ninth, eighth, and seventh 
 ribs, which ascend on either side and form an angle, the subcostal angle {anguine 
 infrasternalis) , from the apex of which the ensiform cartilage projects. It is 
 wider transversely than from before backward. It slopes obliquely downward 
 and backward, so that the cavity of the thorax is much deeper behind than in 
 front. The Diaphragm closes in the opening forming the floor of the thorax. 
 
 In the female the thorax differs as follows from the male: 1. Its general capa- 
 city is less. 2. The sternum is shorter. 3. The upper margin of the sternum 
 is on a level with the lower part of the body of the third dorsal vertebra, whereas 
 in the male it is on a level with the lower part of the body of the second dorsal 
 vertebra. 4. The upper ribs are more movable, and so allow a greater enlarge- 
 ment of the upper part of the thorax than in the male. 
 
 The Sternum or Breast Bone. 
 
 The sternum (azipvov, the chest), or breast bone (Figs. 110, 111), is a flat, 
 narrow bone, situated in the median line of the front of the chest, and con- 
 sisting, in the adult, of three portions. It has been likened to an ancient 
 sword; the upper piece, representing the handle, is termed the manubrium 
 stemi (presternum); the middle and largest piece, which represents the chief 
 part of the blade, is termed the gladiolus (mesosternum or corpus stemi); and 
 the inferior piece, which is likened to the point of the sword, is termed the 
 ensiform or xiphoid process or appendix (processus xiphoideus or metasternum) . 
 In early youth the sternum is composed of six pieces or stemebrse. In adult life 
 the upper piece remains as the manubrium; the inferior piece remains as the 
 xiphoid; and the other four pieces fuse together to form the gladiolus. In its 
 
156 
 
 THE SKELETON 
 
 STERNO-OLEIDOMASTOID. % 
 SUBCLAVIUS. 
 
 Fig. 110. — Sternum and costal cartilages. 
 
 Fig. 111. — Posterior surface of sternum. 
 
THE STERNUM I57 
 
 natural position its inclination is oblique from above downward and forward. It 
 is slightly convex in front, concave behind, broad above, becoming narrowed at 
 the point where the first and second pieces are connected, after which it again 
 widens a little, and is pointed at its extremity. Its average length in the adult is 
 about seven inches, being rather longer in the male than in the female. At the 
 junction of the manubrium and gladiolus is a distinct angle, the angulus stemi 
 {angle of Ludovic or angle of 'Louis), the maimbrium looking forward, the 
 gladiolus also looking forward, but to a less degree. This angle is on a level 
 with the second rib, and is produced by retraction of the upper portion of the 
 thorax. 
 
 WilSt Piece. — The first piece of the sternum, or the manubrium sterni (pre- 
 sternum), is of a somewhat triangular form, broad and thick above, narrow 
 below at its junction with the middle piece. 
 
 Surfaces. — Its anterior surface, convex from side to side, concave from above 
 downward, is smooth, and affords attachment on each side to the Pectoralis 
 major aud sternal origin of the Sterno-cleido-mastoid muscle. In well-marked 
 bones the ridges limiting the attachment of these muscles are very distinct. Its 
 posterior surface, concave and smooth, affords attachment on each side to the 
 Sterno-hyoid and Sterno-thyroid muscles. 
 
 Borders. — The superior border, the thickest, presents at its centre the pre-stemal 
 notch (incisura jugularis), and on each side an oval articular surface, the 
 clavicular facet (incisura clavicularis) , directed upward, backward, and outward, 
 for articulation with the sternal end of the clavicle. The inferior border presents 
 an oval, rough surface, covered in the recent state with a thin layer of cartilage, 
 for articulation with the second portion of the bone (synchondrosis sternalis). 
 The junction of the manubrium with the gladiolus is marked by a transverse 
 ridge, which corresponds to the attachment on each side of the cartilage of 
 the second rib. The lateral borders are marked above by a depression (incisura 
 costalis I) for the first costal cartilage, and below by a small facet, which, with a 
 similar facet on the upper angle of the middle portion of the bone, forms a 
 notch (incisura costalis II) for the reception of the costal cartilage of the second 
 rib. These articular surfaces are separated by a narrow, curved edge, which 
 slopes from above downward and inward. 
 
 Second Piece. — The second piece of the sternum, the corpus sterni or gladiolus 
 (mesosternum) , considerably longer, narrower, and thinner than the first piece, is 
 broader below than above. 
 
 Surfaces. — Its anterior surface (planum sternale) is nearly flat, directed upward 
 and forward, and marked by three transverse lines which cross the bone opposite 
 the third, fourth, and fifth articular depressions. These lines are produced by the 
 union of the four separate pieces of which this part of the bone consists at an early 
 period of life. iVt the junction of the third and fourth pieces is occasionally seen 
 an orifice, the sternal foramen; it varies in size and form in different individuals, 
 and pierces the bone from before backward. This surface affords attachment 
 on each side to the sternal origin of the Pectoralis major. The posterior surface, 
 slightly concave, is also marked by three transverse lines, but they are less dis- 
 tinct than those in front: this surface affords attachment below, on each side, 
 to the Triangularis sterni muscle, and occasionally presents the posterior opening 
 of the sternal foramen. 
 
 Borders. — The superior border presents an oval surface for articulation with the 
 manubrium. The inferior border is narrow, and articulates with the ensiform 
 appendix. Each lateral border presents, at each superior angle, a small facet, 
 whicii, with a similar facet on the manubrium, forms a cavity for the cartilage of 
 the second rib; the four succeeding angular depressions receive the cartilages of 
 the third, fourth, fifth, and sixth ribs; whilst each inferior angle presents a small 
 
158 
 
 THE SKELETON 
 
 facet, which, with a corresponding one on the ensiform appendix, forms a notch 
 for the cartilage of the seventh rib. These articular depressions are known as 
 incisurcB costales. They are separated by a series of curved interarticular inter- 
 vals, which diminish in length from above downward, and correspond to the 
 intercostal spaces. Most of the cartilages belonging to the true ribs, as will be 
 seen from the foregoing description, articulate with the sternum at the line of 
 junction of two of its primitive component segments. This is well seen in many 
 of the lower animals, where the separate parts of the bone remain ununited 
 longer than in man. In this respect a striking analogy exists between the mode 
 of connection of the ribs with the vertebral column and the connection of the 
 costal cartilages with the sternum. 
 
 Third Piece. — The third piece of the sternum, the ensiform or xiphoid appendix 
 {'processus xiphoideus or metasternuTn), is the smallest of the three; it is thin and 
 elongated in form, cartilaginous in structure in youth, but more or less ossified 
 at its upper part in the adult. 
 
 Surfaces. — Its anterior surface affords attachment to the chondro-xiphoid 
 ligament; its posterior surface, to some of the fibres of the Diaphragm and 
 Triangularis sterni muscles; its lateral borders, to the aponeurosis of the abdom- 
 inal muscles. Above it articulates with the lower end of the gladiolus, and at each 
 superior angle presents a facet (incisura costalis VII), for the lower half of the 
 cartilage of the seventh rib; below, by its pointed extremity, it gives attachment 
 to the linea alba. This portion of the sternum is very various in appearance, 
 being sometimes pointed, broad, and thin, sometimes bifid or perforated by a 
 round hole, occasionally curved or deflected considerably to one or the other side. 
 
 Structure. — The bone is composed of delicate cancellous structure, covered by 
 a thin layer of compact tissue, which is thickest in the manubrium between the 
 articular facets for the clavicles. 
 
 Development. — The cartilaginous sternum originally consists of two bars, situ- 
 ated one on either side of the mesial plane and connected with the rib cartilages of 
 its own side. These two bars fuse with each other along the middle line, and 
 the bone, including the ensiform appendix, is developed by six centres : one for the 
 first piece or manubrium, four for the second piece or gladiolus, and one for the 
 ensiform appendix. Up to the middle of foetal life the sternum is entirely car- 
 
 for first piece, two or more centres. 
 
 for second piece, usually one. 
 
 for third ] 
 I 
 for fourth \ 2, placed laterally. 
 
 for fifth J 
 
 Fig. 112. — Development of the sternum by six 
 centres. Time of appearance. 
 
 Arrest of development 
 of lateral pieces, producing 
 
 -Sternal fissure, and 
 .Sternal foramen. 
 
 Fig. 113. — Time of union of sternum. 
 
 tilaginous, and when ossification takes place the ossific granules are deposited in 
 the mitldle of the intervals between the articular depressions for the costal car- 
 tilages, in the following order (Fig. 112): In the first piece, between the fifth and 
 sixth months; in the second and third, between the sixth and seventh months; in 
 the fourth piece, at the ninth month; in the fifth, within the first year or between 
 the first and second years after birth; and in the ensiform appendix, between the 
 
THE BIBS 
 
 ]59 
 
 second and the seventeenth or eighteenth years, by a single centre which makes 
 its appearance at the upper part and proceeds gradually downward. To these 
 may be added the occasional existence, as described by Breschet, of two small 
 episternal centres, which make their appearance one on each side of the pre-sternal 
 notch. They are probably vestiges of the episternal bone of the monotremata 
 and lizards. It occasionally happens that some of the segments are formed from 
 more than one centre, the number and position of which vary (Fig. 114). Thus, 
 the first piece may have two, three, or even six centres. When two are present, 
 they are general y situated one above the other, the upper one being the larger;^ 
 the second piece has seldom more than one; the third, fourth, and fifth pieces 
 are often formed from two centres placed laterally, the irregular union of which 
 will serve to explain the occasional occurrence of the sternal foramen (Fig. 113), 
 
 1 for M piece \ ^^^^^ month foetal, 
 or manubrium J •' 
 
 4 for 2nd piece 
 or gladiolus 
 
 6-7th month. 
 
 Jf 9ih month. 
 
 5 1st year after 
 birth. 
 
 Iforensifo^-m ] ^nd to 18th year 
 cartilage J " 
 
 Fig. 114. — Peculiarities in number of centres of 
 sternum. 
 
 Rarely unite, 
 except in old age. 
 
 Between puberty 
 j and the 25th year. 
 
 Soon after puberty. 
 
 Partly cartilaginous to 
 advanced life. 
 
 Fig. 115. — Peculiarities in mode of union 
 of sternum. 
 
 or of the vertical fissure which occasionally intersects this part of the bone (Fig. 113), 
 and which is further explained by the manner in which the cartilaginous matrix, 
 in which ossification takes place, is formed. Union of the various centres of the 
 gladiolus commences about puberty, from below, and proceeds upward, so that by 
 the age of twenty-five they are all united, and this portion of bone consists of one 
 piece. The ensiform cartilage becomes joined to the gladiolus about forty. The 
 manubrium is occasionally but seldom joined to the gladiolus in advanced life 
 by bone. When this union takes place, however, it is generally only superficial, a 
 portion of the centre of the sutural cartilage remaining unossified. 
 
 Articulations. — With the clavicles and seven costal cartilages on each side. 
 
 Attachment of Muscles. — To nine pairs and one single muscle: the Pectoralis 
 major, Sterno-cleido-mastoid, Sterno-hyoid, Ster no- thyroid. Triangularis sterni, 
 aponeuroses of the Obliquus externus, Obliquus internus, Transversalis, Rectus 
 muscles, and Diaphragm. 
 
 The Ribs (Costse). 
 
 The ribs are elastic arches of hone, which form the chief part of the thoracic 
 walls. They are twelve in number on each side; but this number may be increased 
 by the development of a cervical or lumbar rib, or may be diminished to eleven. 
 The first seven are connected behind with the spine and in front with the sternum, 
 through the intervention of the costal cartilages; they are called true, sternal, or 
 vertebro-stemal ribs (cosioB veroe).^ The remaining five are false ribs {costw 
 
 ' Sir George Humphry states that this is "probably the more complete condition." 
 
 ^ Sometimes the eighth rib cartilage articiilates with the sternum; this condition occurs more frequently on 
 the right than on the left side. 
 
160 
 
 THE SKELETON 
 
 spurice) ; of these, the first three have their cartilages attached to the cartilage of 
 the rib above, and are called the vertebro-chondral ribs; the last two are free at their 
 
 ^Tuberosity, 
 
 Articular part of tuberosity: 
 
 iNeck. 
 
 -Subcostal groove 
 
 Head.' 
 
 anterior extremities; they are termed floating or 
 vertebral ribs. The ribs vary in their direction, 
 the upper ones being less oblique than the lower. 
 The extent of obliquity reaches its maximum at 
 the ninth rib, and gradually decreases from that 
 rib to the twelfth. The ribs are situated one be- 
 low the other in such a manner that spaces are 
 left between them. Each space is called an inter- 
 costal space (spatium intercostale). The length of 
 these spaces corresponds to the length of the ribs 
 and their cartilages; their breadth is greater in 
 front than behind, and between the upper than 
 between the lower ribs. The ribs increase in 
 length from the first to the seventh, when they 
 again diminish to the twelfth. In breadth they 
 decrease from above downward ; in the upper ten 
 the greatest breadth is at the sternal extremity. 
 
 ^Body 
 or shaft. 
 
 Common Characters of the Ribs. 
 
 A rib from the middle of the series should be 
 taken in order to studv the common characters of 
 the ribs (Figs. 116, "ll 7, and 118). Each rib 
 presents two extremities, a posterior or vertebral, 
 an anterior or sternal, and an intervening portion 
 — the body or shaft. 
 
 Posterior Extremity. — The posterior or ver- 
 tebral extremity presents for examination a head, 
 neck, and tuberosity. 
 
 The Head {capitulum costcB). — The head (Fig. 
 118) is marked by a kidney shaped articular 
 surface, divided by a horizontal ridge {crista 
 capituli) into two facets for articulation with the 
 costal cavity formed by the junction of the bodies 
 of two contiguous dorsal vertebrae; the upper 
 facet is small, the inferior one of larger size; 
 the ridge separating them serves for the attach- 
 ment of the interarticular ligament. 
 
 The Neck (collum costoe), — The neck is that flattened portion of the rib which 
 extends outward from the head; it is about an inch long, and is placed in front 
 
 Fig. 116. — A central rib of right side. 
 
COMMON CHARACTERS OF THE RIBS 
 
 161 
 
 of the transverse process of the lower of the two vertebrae with which the head 
 articulates. Its anterior surface is flat and smooth, its posterior surface is rough 
 for the attachment of the middle costo-transverse ligament, and is perforated by 
 numerous foramina, the direction of which is less constant than those found on 
 the inner surface of the shaft. Of its two borders the 
 superior border presents a rough crest {crista colli costce) 
 for the attachment of the anterior costo-transverse liga- 
 ment; its inferior border is rounded. On the posterior 
 surface of the neck, just where it joins the shaft, and 
 nearer the lower than the upper border, is an eminence 
 — the tuberosity, or tubercle. 
 
 Tuberosity (tuberculum costce). — The tuberosity, or 
 tubercle, consists of an articular and a non-articular por- 
 tion. The axticular portion (fades articularis tuber culi 
 costce), the more internal and inferior of the two, pre- 
 sents a small, oval surface for articulation with the ex- 
 tremity of the transverse process of the lower of the two 
 vertebrfe to which the head is connected. The non- 
 articulax portion is a rough elevation, which affords at- 
 tachment to the posterior costo-transverse ligament. 
 The tubercle is much more prominent in the upper than 
 in the lower ribs. 
 
 Anterior Extremity. — ^The anterior or sternal extremity is flattened, and pre- 
 sents a porous, oval, concave depression, into which the costal cartilage is received. 
 
 The Shaft {corpus costae). — The shaft is thin and flat, so as to present two sur- 
 faces, an external and an internal, and two borders, a superior and an inferior. 
 
 Fig. 117. — Ribs and ar- 
 ticulations of the vertebrsB. 
 (Sappey.) 
 
 ■Facet for body of upper dorsal vertebra. 
 ■Ridge for interarticular ligament. 
 ■Facet for body of lower dorsal vertebra. 
 
 Articular part of tuberosity. 
 
 Non-articular part of tuberosity. 
 Fig. 118. — Vertebral extremity of a rib. External surface. 
 
 Surfaces. — The external surface is convex, smooth and marked at its back part, a 
 little in front of the tuberosity, by a prominent line, directed obliquely from above 
 downward and outward; this gives attachment to a tendon of the Ilio-costalis 
 muscle or of one of its accessory portions, and is called the angle {angulus costae) . 
 At this point the rib is bent in two directions. If the rib is laid upon its lower 
 border, it will be seen that the portion of the shaft in front of the angle rests upon 
 this border, while the portion of the shaft behind the angle is bent inward and at 
 the same time tilted upward. The interval between the angle and the tuberosity 
 increases gradually from the second to the tenth rib. The portion of bone between 
 these two parts is rounded, rough, and irregular, and serves for the attachment of 
 the Longissimiis dorsi muscle. The portion of bone between the tubercle and 
 sternal extremity is also slightly twisted upon its own axis, the external surface 
 looking downward behind the angle, a little upward in front of it. This surface 
 presents, toward its sternal extremity, an oblique line, the anterior angle. The 
 internal surface is concave, smooth, directed a little upward behind the angle, a 
 little downward in front of it. This surface is marked by a ridge which com- 
 
 11 
 
162 THE SKELETON 
 
 mences at the lower extremity of the head; it is strongly marked as far as the 
 inner side of the angle, and gradually becomes lost at the junction of the anterior 
 with the middle third of the bone. '^J^'he interval between it and the inferior border 
 presents a groove, subcostal groove {sulcus costce), for the intercostal vessels and 
 nerve. At the back part of the bone this groove belongs to the inferior border, 
 but just in front of the angle, where it is deepest and broadest, it corresponds to 
 the internal surface. The superior edge of the groove is rounded; it serves for 
 the attachment of the Internal intercostal muscle. The inferior edge corresponds 
 to the lower margin of the rib and gives attachment to the External intercostal 
 muscle. Within the groove are seen the orifices of numerous small foramina 
 which traverse the wall of the shaft obliquely from before backward. 
 
 Borders.— The superior border, thick and rounded, is marked by an external 
 and an internal lip, more distinct behind than in front; they serve for the attach- 
 ment of the External and Internal intercostal muscles. The inferior border, thin, 
 and sharp, has attached to it the External intercostal muscle. 
 
 Peculiar Ribs, 
 
 The ribs which require especial consideration are five in number — viz., the 
 first, second, tenth, eleventh, and twelfth. 
 
 First Rib. — The first rib (Fig. 119) is the shortest and the most curved of 
 all the ribs; it is broad and flat, its surface looking upward and downward, and 
 its borders inward and outward. The head is of small size, rounded, and presents 
 only a single articular facet for articulation with the body of the first dorsal ver- 
 tebra. The neck is narrow and rounded. The tuberosity, thick and prominent, 
 rests on the outer border. There is no angle, but in this situation the rib is slightly 
 bent, with the convexity of the bend upward, so that the head of the bone is 
 directed downward. The upper surface of the shaft is marked by two shallow 
 depressions, separated by a small rough surface (tuberculum scaleni) for the 
 attachment of the Scalenus anticus muscle — the shallow groove in front of it 
 transmitting the subclavian vein, the deeper groove behind it (sulcus subclaviae) 
 the subclavian artery. Between the groove for the subclavian artery and 
 the tuberosity is a rough surface, for the attachment of the Scalenus medius 
 muscle. The under surface is smooth, and destitute of the groove observed on the 
 other ribs. The outer border is convex, thick, and rounded, and at its posterior 
 part gives attachment to the first serration of the Serratus magnus; the inner is 
 concave, thin, and sharp, and marked about its centre by the commencement of 
 the rough surface for the Scalenus anticus. The anterior extremity is larger and 
 thicker than any of the other ribs. 
 
 Second Rib. — The second rib (Fig. 120) is much longer than the first, but bears 
 a very considerable resemblance to it in the direction of its curvature. The non- 
 articular portion of the tuberosity is occasionally only slightly marked. The angle 
 is slight and situated close to the tuberosity, and the shaft is not twisted, so that 
 both ends touch any plane surface upon which it may be laid; but there is a similar 
 though slighter bend, with its convexity upward, to that found in the first rib. The 
 shaft is not horizontal, like that of the first rib, its outer surface, which is convex, 
 looking upward and a little outward. It presents, near the middle, a rough emi- 
 nence, tuberositas costse II, for the attachment of the second and third digitations 
 of the Serratus magnus; behind and above which is attached the Scalenus 
 posticus. The inner surface, smooth and concave, is directed dowmward and a 
 little inward; it presents a short groove toward its posterior part. 
 
 Tenth Rib. — The tenth rib (Fig. 121) has only a single articular facet on its head. 
 
 Eleventh and Twelfth Ribs.— The eleventh and twelfth ribs (Figs. 122 and 
 123) have each a single articular facet on the head, which is of rather large size; 
 
PECULIAR JRIBS 
 
 163 
 
 they have no neck or tuberosity, and are pointed at the extremity. The eleventh 
 has a slight angle and a shallow groove on the lower border. The twelfth has 
 neither, and is much shorter than the eleventh, and the head has a slight inclina- 
 tion downward. Sometimes the twelfth rib is even shorter than the first. 
 
 .\,Avgi« <s>-, 
 
 Angle 
 
 slightly marked 
 
 and close to 
 
 tuberosity. 
 
 Single articular facet 
 
 Single articular facet. 
 
 Figs. 119-123.— Peculiar ribs. 
 
 Structure. — The ribs consist of cancellous tissue enclosed in a thin, compact 
 layer. 
 
 Development. — Each rib, with the exception of the last two, is developed by 
 three centres: one for the shaft, one for the head, and one for the tubercle. The 
 last two have only two centres, that for the tubercle being wanting. Ossification 
 commences in the shaft of the ribs at a very early period, before its appearance in 
 the vertebrae. The epiphysis of the head, which is of slightly angular shape, and 
 that for the tubercle, of a lenticular form, make their appearance between the six- 
 teenth and twentieth years, and are not united to the rest of the bone until about 
 the twenty-fifth year. 
 
164 THE SKELETON 
 
 Attachment of Muscles. — To nineteen: The Internal and External intercostals, 
 Scalenus anticus, Scalenus medius, Scalenus posticus, Pectoralis minor, Serratus 
 magnus, Obliquus externus, Quadratus lumborum, Diaphragm, Latissimus dorsi, 
 Serratus posticus superior, Serratus posticus inferior, Ilio-costalis, Musculus acces- 
 sorius ad ilio-costalem, Longissimus dorsi, Cervicalis ascendens, Levatores costa- 
 rum, and Infracostales. 
 
 The Costal Cartilages. 
 
 The costal cartilage (cartilago costalis) (Fig. 110) is white, hyaline cartilage. The 
 cartilages serve to prolong the ribs forward to the front of the chest, and they 
 contribute very materially to the elasticity of its walls. The first seven are con- 
 nected with the sternum, the next three with the lower border of the cartilage of 
 the preceding rib. The cartilages of the last two ribs have pointed extremities, 
 which terminate in free ends in the walls of the abdomen. Like the ribs, the 
 costal cartilages vary in their length, breadth, and direction. They increase in 
 length from the first to the seventh, then gradually diminish to the last. They 
 diminish in breadth, as well as the intervals between them, from the first to the 
 last. They are broad at their attachment to the ribs, and taper toward their sternal 
 extremities, excepting the first two, which are of the same breadth throughout, 
 and the sixth, seventh, and eighth, which are enlarged where their margins are 
 in contact. In direction they also vary: the first descends a little, the second is 
 horizontal, the third ascends slightly, while all the rest follow the course of the 
 ribs for a short extent, and then ascend to the sternum or preceding cartilage. 
 Each costal cartilage presents two surfaces, two borders, and two extremities. 
 
 Surfaces. — The anterior surface is convex, and looks forward and upward: that 
 of the first gives attachment to the costo-clavicular ligament and the Subclavius 
 muscle; that of the second, third, fourth, fifth, and sixth, at their sternal ends, 
 to the Pectoralis major.^ The others are covered by, and give partial attachment 
 to, some of the great flat muscles of the abdomen. The ^posterior surface is con- 
 cave, and directed backward and downward, the first giving attachment to the 
 Sterno-thyroid, the third to the sixth inclusive to the Triangularis sterni, and 
 the six or seven inferior ones to the Trans versalis muscle and the Diaphragm. 
 
 Borders. — Of the two borders, the superior border is concave, the inferior con- 
 vex; they afford attachment to the internal Intercostal muscles, the upper border 
 of the sixth giving attachment to the Pectoralis major muscle. The contiguous 
 borders of the sixth, seventh, and eighth, and sometimes the ninth and tenth, 
 costal cartilages present small, smooth, oblong-shaped facets at the points where 
 they articulate. 
 
 Extremities. — Of the two extremities, the outer extremity is continuous with the 
 osseous tissue of the rib to which it belongs. The inner extremity of the first is 
 continuous with the sternum; the six succeeding ones have rounded extremities, 
 which are received into shallow concavities on the lateral margins of the sternum. 
 The inner extremities of the eighth, ninth, and tenth costal cartilages are pointed, 
 and are connected with the cartilage above. Those of the eleventh and twelfth 
 are free and pointed. 
 
 The costal cartilages are most elastic in youth, those of the false ribs being 
 more so than the true. In old age they become of a deep yellow color, and are 
 prone to calcify. 
 
 Attachment of Muscles. — To nine: the Subclavius, Sterno-thyroid, Pectoralis 
 major, Internal oblique, Transversalis, Rectus, Diaphragm, Triangularis sterni, 
 and Internal intercostals. 
 
 1 The first and seventh also, occasionally, give origin to the same muscle. 
 
THE COSTAL CARTILAGES 165 
 
 Surface Form. — The bones of the chest are to a very considerable extent covered by mus- 
 cles, so that in the strongly developed muscular subject they are for the most part concealed. 
 In the emaciated subject, on the other hand, the ribs, especially in the lower and lateral region, 
 stand out as prominent ridges with the sunken, intercostal spaces between them. 
 
 In the middle line, in front, the superficial surface of the sternum is to be felt throughout 
 its entire length, at the bottom of a deep median furrow situated between the two great pectoral 
 muscles and called the Sternal fuiTOW. These muscles overlap the anterior surface somewhat, so 
 that the whole of the sternum in its entire width is not subcutaneous; and this overlapping is 
 greater opposite the centre of the bone than above and below, so that the furrow is wider at its 
 upper and lower parts, but narrower in the middle. The centre of the upper border of the ster- 
 num is visible, constituting the pre-stemal notch, but the lateral parts of this border are obscured 
 by the tendinous origins of the Sterno-mastoid muscles, which present themselves as oblique 
 tendinous cords, which narrow and deepen the notch. Lower down on the subcutaneous surface 
 a well-defined transverse ridge, the angle of Ludovic, is always to be felt. This denotes the line 
 of junction of the manubrium and body of the bone, and is a useful guide to the second costal 
 cartilage, and thus to the identity of any given rib. The second rib being found through its 
 costal cartilage, it is easy to count downward and find any other. From the middle of the 
 sternum the furrow spreads out, and, exposing more of the surface of the body of the bone, 
 terminates below in a sudden depression, the infrastemal depression or pit of the stomach 
 {scrobiculus cordis), which corresponds to the ensiform cartilage. This depression lies between 
 the cartilages of the seventh ribs, and in it the ensiform cartilage may be felt. The sternum in 
 its vertical diameter presents a general convexity forward, the most prominent point of which 
 is at the joint between the manubrium and gladiolus. 
 
 On each side of the sternum the costal cartilages and ribs on the front of the chest are par- 
 tially obscured by the great pectoral muscles; through which, however, they are to be felt as 
 ridges, with yielding intervals between them, corresponding to the intercostal spaces. Of these 
 spaces, the one between the second and third ribs is the widest, the next two somewhat nar- 
 rower, and the remainder, with the exception of the last two, comparatively narrow. 
 
 The lower border of the Pectoralis major muscle corresponds to the fifth rib, and below 
 this, on the front of the chest, the broad, flat outline of the ribs, as they begin to ascend, and 
 the more rounded outline of the costal cartilages, are often visible. The lower boundary of 
 the front of the thorax, the abdomino-thoracic arch, which is most plainly seen by arching the 
 body backward, is formed by the ensiform cartilage and the cartilages of the seventh, eighth, 
 ninth, and tenth ribs, and the extremities of the eleventh and twelfth ribs or their cartilages. 
 
 On each side of the chest, from the axilla downward, the flattened external surfaces of the 
 ribs may be defined in the form of oblique ridges, separated by depressions corresponding to the 
 intercostal spaces. They are, however, covered by muscles, which obscure their outline to a 
 certain extent in the strongly developed. Nevertheless, the ribs, with the exception of the first, 
 can generally be followed over the front and sides of the chest without difficulty. The first rib, 
 being almost completely covered by the clavicle and scapula, can only be distinguished in a 
 small portion of its extent. At the back the angles of the ribs form a slightly-marked oblique 
 line on each side of and some distance from the vertebral spines. This line diverges some- 
 what as it descends, and external to it is a broad, convex surface caused by the projection of 
 the ribs beyond their angles. Over this surface, except where covered by the scapula, the 
 individual ribs can be distinguished. 
 
 Surgical Anatomy. — Malformations of the sternum present nothing of surgical importance 
 beyond the fact that abscesses of the mediastinum may sometimes escape through the sternal 
 foramen. Frax'tures of the sternum are by no means common, owing, no doubt, to the elasticity 
 of the ribs and their cartilages, which support it like so many springs. When broken it is fre- 
 quently associated with fracture of the spine, and may be caused by forcibly bending the body 
 either backward or forw^ard until the chin becomes impacted against the top of the sternum. It 
 may also be fractured by direct violence or by muscular action. The fracture usually occurs in 
 the upper half of the body of the bone. Dislocation of the gladiolus from the manubrium also 
 takes place, and is sometimes described as a fracture. 
 
 The bone, cancellous in structure and being subcutaneous, is frequently the seat of gummatous 
 tumors, and not uncommonly is affected with caries. Occasionally the bone, and especially 
 its ensiform appendix, becomes altered in shape and driven inward by the pressure, in work- 
 men, of tools against the chest. 
 
 The ribs are frequently broken, though from their connections and shape they are able to 
 withstand great force, yielding under the injury and recovering themselves like a spring. The 
 middle of the series are the ones most liable to fracture. The first, and to a less extent the 
 second, being protected by the clavicle, are rarely fractured; and the eleventh and twelfth, on 
 account of their loose and floating condition, enjoy a like immunity. The fracture generally 
 occurs from indirect violence, from forcible compression of the chest-wall, and the bone then 
 gives way at its weakest part — i. e., just in front of the angle. But the ribs may also be broken 
 by direct violence, when the bone gives away and is driven inward at the point struck, or they 
 
166 THE SKELETON 
 
 may be broken by muscular action. It seems probable, however, that in the latter case the 
 bone has undergone some atrophic changes. Fracture of the ribs is frequently complicated with 
 some injury to the viscera contained within the thorax or upper part of the abdominal cavity, 
 and this is most likely to occur in fractures from direct violence. 
 
 Fracture of the costal cartilages may also take place, though it is a comparatively rare injury. 
 
 The thorax is frequently found to be altered in shape in certain diseases. 
 
 The shape of the rickety thorax is produced chiefly by atmospheric pressure. The balance 
 between the air on the inside of the chest and the outside during some stage of respiration is not 
 equal, the preponderance being in favor of the air outside; and this, acting on the softened ribs, 
 causes them to be forced in at the junction of the cartilages with the bones, which is the weakest 
 part. In consequence of this the sternum projects forward, with a deep depression on either side 
 caused by the sinking in of the softened ribs. The depression is less on the left side, on account 
 of the ribs being supported by the heart. The condition is known as pigeon-breast. The 
 lower ribs, however, are not involved in this deformity, as they are prevented from falling in by 
 the presence of the stomach, liver, and spleen. And when the liver and spleen are enlarged, 
 as they sometimes are in rickets, the lower ribs may be pushed outward: this causes a trans- 
 verse constriction just above the costal arch. The anterior extremities of the ribs are usually 
 enlarged in rickets, giving rise to what has been termed the rickety rosary. The phthisical 
 chest is often long and narrow, flattened from before backward, and with great obliquity of the 
 ribs and projection of the scapulae. In pulmonary emphysema the chest is enlarged in all its 
 diameters, and presents on section an almost circular outline. It has received the name of the 
 barrel-shaped chest. In severe cases of lateral curvature of the spine the thorax becomes 
 much distorted. In consequence of the rotation of the bodies of the vertebrae which takes 
 place in this disease the ribs opposite the convexity of the dorsal curve become extremely con- 
 vex behind, being thrown out and bulging, and at the same time flattened in front, so that the 
 two ends of the same rib are almost parallel. Coincident with this, the ribs on the opposite 
 side, on the concavity of the curve, are sunk and depressed behind and bulging and convex in 
 front. In addition to this the ribs become occasionally welded together by bony material. 
 
 The ribs are frequently the seat of caries leading to abscesses and sinuses, which may 
 burrow to a considerable extent over the wall of the chest. The only special anatomical point 
 in connection with abscesses and sinuses is that care must be taken in dealing with them that 
 the intercostal space is not punctured and the pleural cavity opened or the intercostal vessels 
 wounded, as the necrosed portion of bone is generally situated on the internal surface of the rib. 
 
 In cases of empyema the chest requires opening ft evacuate the pus. There is consider- 
 able difference of opinion as to the best position to do this. Probably the best place for inter- 
 costal drainage is between the fifth and sixth ribs, in or a little in front of the mid-axillary line. 
 This is the last part of the cavity to be closed by the expansion of the lung; it is not thickly 
 covered by soft parts; the space between the two ribs is sufficiently great to allow of the intro- 
 duction of a fair-sized drainage-tube, and when the patient is confined to bed he does not lie 
 upon the drainage-tube as he does when the opening is posterior. Better than intercostal drain- 
 age in the vast majority of cases is rib resection and drainage. A portion of the fifth or sixth 
 rib should be removed in the mid-axillary line. In chronic empyema the lung becomes shrunken 
 and adherent and simple drainage will not bring about a cure. It is necessary in such cases 
 to do an operation that will permit of collapse of the chest wall. Esilander's operation consists 
 in resecting a portion of every rib which overlies the cavity of the empyema. Schede's opera- 
 tion consists in removing ribs from the second rib down over the empyema cavity. The ribs 
 are removed from cartilages to angles, and intercostal muscles and the parietal layer of the 
 pleura are also taken away. Fowler and de Lorme not only practice extensive rib resection 
 and remove the parietal layer of the pleura, but also remove the pulmonary pleura {total pleu- 
 rectomy or pulmonary decortication). 
 
 THE EXTREMITIES. 
 
 The extremities, or limbs, are those long, jointed appendages of the body 
 which are connected with the trunk by one end and free in the rest of their extent. 
 They are four in number: an upper or thoracic pair, connected with the thorax 
 through the intervention of the shoulder, and subservient mainly to prehension; 
 and a lower pair, connected with the pelvis, intended for support and locomotion. 
 Both pairs of limbs are constructed after one common type, so that they present 
 numerous analogies, while at the same time certain differences are observed 
 between the upper and lower pair, dependent on the peculiar offices they have 
 to perform. 
 
THE CLAVICLE 167 
 
 The bones by which the upper and lower limbs are attached to the trunk are 
 named respectively the shoulder and pelvic girdles, and they are constructed on the 
 same general type, though presenting certain modifications relating to the different 
 uses to which the upper and lower limbs are respectively applied. The shoulder 
 girdle is formed by the scapulae and clavicles, and is imperfect in front and behind. 
 In front, however, the girdle is completed by the upper end of the sternum, with 
 which the inner extremities of the clavicle articulate. Behind, the girdle is widely 
 imperfect and the scapula is connected to the trunk by muscles only. The pelvic 
 girdle is formed by the innominate bones, and is completed in front through the 
 symphysis pubis, at which the two innominate bones articulate with each other. 
 It is imperfect behind, but the intervening gap is filled in by the upper part of 
 the sacrum. The pelvic girdle, therefore, presents, with the sacrum, a complete 
 ring, comparatively fixed, and presenting an arched form which confers upon it a 
 solidity manifestly intended for the support of the trunk, and in marked contrast 
 to the lightness and mobility of the shoulder girdle. 
 
 With regard to the morphology of these girdles, the blade of the scapula is 
 generally believed to correspond to the ilium; but with regard to the clavicles 
 there is some difference of opinion: formerly it was believed that they corre- 
 sponded to the ossa pubis, meeting at the symphysis, but it is now generally 
 taught that the clavicle has no homologue in the pelvic girdle, and that the os 
 pubis and ischium are represented by the small coracoid process in man and 
 most mammals. 
 
 i 
 
 THE UPPER EXTREMITY. 
 
 The bones of the upper extremity consist of those of the shoulder girdle, of the 
 arm, the forearm, and the hand. 
 
 THE SHOULDER GIRDLE. 
 
 The shoulder girdle consists of the clavicle and the scapula. 
 
 The Clavicle or Collar Bone (Clavicula). 
 
 The clavicle or key bone (clavis, a key) obtains it name from its supposed 
 resemblance to the key used by the Romans. It forms the anterior portion of the 
 shoulder girdle. It is a long bone, curved somewhat like the italic letter /, and 
 placed nearly horizontally at the upper and anterior part of the thorax, imme- 
 diately above the first rib. It articulates by its inner extremity with the upper 
 border of the sternum, and by its outer extremity with the acromion process of the 
 scapula, serving to sustain the upper extremity in the various positions which it 
 assumes, whilst at the same time it allows of great latitude of motion in the arm.' 
 It presents a double curvature when looked at in front, the convexity being for- 
 ward at the sternal end and the concavity at the scapular end. Its outer third is 
 flattened from above downward, and extends, in the natural position of the bone, 
 from a point opposite the coracoid process to the acromion. Its inner two-thirds 
 are of a prismatic form, and extend from the sternum to a point opposite the cora- 
 coid process of the scapula. 
 
 Outer, External, or Flattened Portion. — ^The outer third is flattened from above 
 downward, so as to present two surfaces, an upper and a lower; and two borders, 
 an anterior and a posterior. 
 
 ' The clavicle acts especially as a fulcrum to enable the muscles to give lateral motion to the arm. It is 
 accordingly absent in those animals whose fore limbs are used only for progression, but is present for the most 
 part in those animals whose anterior extremities are clawed and used for prehension, though in some of them — 
 as, for instance, in a large number of the carnivora — it is merely a rudimentary bone suspended among the 
 muscles, and not articulating with the scapula or sternum. 
 
168 THE SKELETON 
 
 Surfaces. — The upper surface is flattened, rough, marked by impressions for the 
 attachment of the Deltoid in front and the Trapezius behind; between these two 
 impressions, externally, a small portion of the bone is subcutaneous. The under 
 surface is flattened. At its posterior border, a little external to the point where the 
 prismatic joins with the flattened portion, is a rough eminence, the conoid tubercle 
 (tuberositas coracoidea) ; this, in the natural position of the bone, surmounts the 
 coracoid process of the scapula and gives attachments to the conoid ligament. 
 From this tubercle an oblique line, occasionally a depression, passes forward 
 and outward to near the outer end of the anterior border; it is called the oblique 
 line or trapezoid ridge, and affords attachment to the trapezoid ligament. 
 
 Borders. — The anterior border is concave, thin, and rough, and gives attachment 
 to the Deltoid; it occasionally presents, at its inner end, at the commencement of 
 the deltoid impression, a tubercle, the deltoid tubercle, which is sometimes to be 
 felt in the living subject. The posterior border is convex, rough, broader than the 
 anterior, and gives attachment to the Trapezius. 
 
 Inner, Internal, or Prismatic Portion. — The prismatic portion forms the inner 
 two-thirds of the bone. It is curved so as to be convex in front, concave behind, 
 and is marked by three borders, separating three surfaces. 
 
 Borders. — The anterior border is continuous with the anterior margin of the flat 
 portion. At its commencement it is smooth, and corresponds to the interval 
 between the attachment of the Pectoralis major and Deltoid muscles; at the inner 
 half of the clavicle it forms the lower boundary of an elliptical space for the 
 attachment of the clavicular portion of the Pectoralis major, and approaches the 
 posterior border of the bone. The superior border is continuous with the posterior 
 margin of the flat portion, and separates the anterior from the posterior surface. 
 At its commencement it is smooth and rounded, becomes rough toward the inner 
 third for the attachment of the Sterno-mastoid muscle, and terminates at the 
 upper angle of the sternal extremity. The posterior or subclavian border separates 
 the posterior from the inferior surface, and extends from the conoid tubercle to 
 the rhomboid impression. It forms the posterior boundary of the groove for the 
 Subclavius muscle, and gives attachment to a layer of cervical fascia covering 
 the Omo-hyoid muscle. 
 
 Surfaces. — The anterior surface is included between the superior and anterior 
 borders. It is directed forward and a little upward at the sternal end, outward 
 and still more upward at the acromial extremity, where it becomes continuous 
 with the upper surface of the flat portion. Externally, it is smooth, convex, 
 nearly subcutaneous, being covered only by the Platysma; but, corresponding 
 to the inner half of the bone, it is divided by a more or less prominent line into 
 two parts: a lower portion, elliptical in form, rough, and slightly convex, for the 
 attachment of the Pectoralis major; and an upper part, which is rough, for the 
 attachment of the Sterno-cleido-mastoid. Between the two muscular impressions 
 is a small subcutaneous interval. The posterior or cervical surface is smooth, 
 flat, and looks backward toward the root of the neck. It is limited, above, by the 
 superior border; below, by the subclavian border; internally, by the margin of the 
 sternal extremity; externally, it is continuous with the posterior border of the flat 
 portion. It is concave from within outward, and is in relation, by its lower part, 
 with the suprascapular vessels. This surface, at about the junction of the inner 
 and outer curves, is also in close relation with the brachial plexus and subclavian 
 vessels. It gives attachment, near the sternal extremity, to part of the Sterno-hyoid 
 muscle; and presents, at or near the middle, a foramen, nutrient foramen (foramen 
 nutricium). It opens into a canal, nutrient canal (canalis nutricius), which is 
 directed obliquely outward and transmits the chief nutrient artery of the bone. 
 Sometimes there are two foramina on the posterior surface, or one on the 
 posterior, and one on the inferior surface. The inferior or subclavian surface 
 
THE CLAVICLE 
 
 169 
 
 is bounded, in front, by the anterior border; behind, by the subclavian border. 
 It is narrow internally, but gradually increases in width externally, and is 
 continuous with the under surface of the flat portion. Commencing at the 
 sternal extremity may be seen a small facet, the costal facet, for articulation 
 
 This is continuous with the articular surface 
 
 with the cartilage of the first rib 
 
 Acromial extremity. 
 
 Sternal exti-emity. 
 
 Fig. 124. — Left clavicle. Superior surface. 
 
 at the sternal end of the bone. External to this is a broad, rough surface, the 
 rhomboid impression (tuberositas costalis), rather more than an inch in length, for 
 the attachment of the costo-clavicular (rhomboid) ligament. The remaining part 
 of this surface is occupied by a longitudinal groove, the subclavian groove, broad 
 and smooth externally, narrow and more uneven internally; it gives attachment to 
 the Subclavius muscle, and by its margins to the costo-coracoid membrane, 
 which splits to enclose the muscle. Not infrequently this groove is subdivided 
 into two parts by a longitudinal line, which gives attachment to the intermuscular 
 septum of the Subclavius muscle. 
 
 Fig. 125. — Left clavicle. Inferior surface. 
 
 Internal or Sternal Extremity (extremitas sternalis). — The internal or sternal 
 extremity of the clavicle is triangular in form, dii'ected inward and a little down- 
 ward and forward; and presents an articular facet {fades articularis sternalis), 
 concave from before backward, convex from above downward, which articulates 
 with the sternum through the intervention of an interarticular fibro-cartilage; 
 the circumference of the articular surface is rough, for the attachment of 
 numerous ligaments. The posterior border of this surface is prolonged back- 
 warfl, so as to increase the size of the articular facet; the upper border gives 
 attachment to the interarticular fibro-cartilage, and the lower border is con- 
 tinuous with the costal facet on the inner end of the inferior or subclavian sur- 
 face, which articulates with the cartilage of the first rib. 
 
 Outer or Acromial Extremity (extremitas acromialis) . — The outer or acromial 
 extremity, directed outward and forward, presents a small, flattened, oval facet. 
 
170 
 
 THE SKELETON 
 
 acromial surface (facies articularis acromialis) , which looks obliquely downward, 
 for articulation with the acromion process of the scapula. The circumference 
 of the articular facet is rough, especially above, for the attachment of the 
 acromio-clavicular ligaments. 
 
 Peculiarities of the Bone in the Sexes and in Individuals. — In the female the. 
 clavicle is generally shorter, thinner, less curved, and smoother than in the male.] 
 In those persons who perform considerable manual labor, which brings into con- 
 stant action the muscles connected with this bone, it becomes thicker and more 
 curved, its ridges for muscular attachment become prominently marked. The 
 right clavicle is generally longer, thicker, and rougher than the left. 
 
 Structure. — The shaft, as well as the extremities, consists of cancellous tissue,; 
 invested in a compact layer much thicker in the middle than at either end. The 
 clavicle is highly elastic, by reason of its curves. From the experiments of Mr.j 
 Ward it has been shown that it possesses sufficient longitudinal elastic force tc 
 project its own weight nearly two feet on a level surface when a smart blow is 
 struck on it; and sufficient transverse elastic force, opposite the centre of it 
 anterior convexity, to throw its own weight about a foot. This extent of elastic 
 power must serve to moderate very considerably the effect of concussions receivec 
 upon the point of the shoulder. 
 
 Development.^-By two centres: one for the shaft and outer extremity anc 
 one for the sternal extremity. The centre for the shaft appears very early, 
 before any other bone — according to Beclard, as early as the thirtieth day.l 
 The centre for the sternal end makes its appearance about the eighteenth oi 
 twentieth year, and unites with the rest of the bone about the twenty-fifth year.l 
 
 Articulations. — With the sternum, scapula, and cartilage of the first rib. 
 
 Attachment of Muscles. — To six : the Sterno-cleido-mastoid, Trapezius, 
 Pectoralis major. Deltoid, SubclaviuSj and Sterno-hyoid. 
 
 Surface Form. — The clavicle can be felt throughout its entire length, even in persons who 
 are very fat. Commencing at the inner end, the enlarged sternal extremity, where the bone 
 projects above the upper margin of the sternum, can be felt, forming with the sternum and the 
 rounded tendon of the Sterno-mastoid a V-shaped notch, the pre-stemal notch. Passing out-^ 
 ward, the shaft of the bone can be felt immediately under the skin, with its convexity forwarc 
 in the inner two-thirds, the surface partially obscured above and below by the attachments of 
 the Sterno-mastoid and Pectoralis major muscles. In the outer third it forms a gentle curve 
 backward, and terminates at the outer end in a somewhat enlarged extremity which articulates 
 with the acromial process of the scapula. The direction of the clavicle is almost, if not quite, 
 horizontal when the arm is lying quietly by the side, though in well-developed subjects it may 
 incline a little upward at its outer end. Its direction is, however, very changeable, altering 
 with the varying movements of the shoulder-joint. 
 
 Surgical Anatomy. — The clavicle is the most frequently fractured of any single bone in the 
 body. This is due to the fact that it is much exposed to violence, and is the only bony connec- 
 tion between the upper limb and the trunk. The bone, moreover, is slender, and is very super- 
 ficial. The bone may be broken by direct or indirect violence or by muscular action. The most 
 common cause is, however, from indirect violence, and the bone then gives way at the junction 
 of the fixed outer one-third with the movable inner two-thirds of the bone. This is the weakest 
 and most slender part of the bone. The fracture is generally oblique, and the displacement 
 of the outer fragments is inward, away from the surface of the body; hence compound 
 fracture of the clavicle is of rare occurrence. The iimer fragment as a rule is little displaced 
 (page 503). Beneath the bone the main vessels of the upper limb and the great nerve-cords of 
 the brachial plexus lie on the first rib, and are liable to be wounded in fracture, especially in 
 fracture from direct violence, when the force of the blow drives the broken ends inward. For- 
 tunately, the Subclavius muscle is interposed between these structures and the clavicle, and 
 this often protects them from injury. 
 
 The clavicle is not uncommonly the seat of sarcomatous tumors, rendering the operation 
 of excision of the entire bone necessary. This operation is best performed by exposing the 
 bone freely, disarticulating at the acromial end, and turning it inward. The removal of 
 the outer part is comparatively easy, but resection of the inner part is fraught with difficulty, the 
 main danger being the risk of wounding the great veins which are in relation with its under 
 surface. 
 
THE SCAPULA 
 
 The Scapula or Shoulder Blade. 
 
 173 
 
 The scapula {axaTzdvrj, a spade), or blade bone, forms the back part of 
 the shoulder girdle. It is a large, flat bone, triangular in shape, situated at 
 the posterior aspect and side of the thorax, between the second and seventh, or 
 sometimes the eighth, ribs, its internal border or base being about an inch from 
 and nearly but not quite parallel with the spinous processes of the vertebrae, so 
 that it is rather closer to them above than below. It presents for examination 
 two surfaces, three borders, and three angles. 
 
 Fig. 126. — Left scapula. Anterior surface or venter. 
 
 Surfaces. Anterior or Costal Surface, Ventral Aspect or Venter (facies costalis) . — 
 The anterior surface (Fig. 126) presents a broad concavity, the subscapular 
 fossa ijossa subscapularis) . It is marked, in the inner two-thirds, by several 
 oblique ridges (linece musculares) , which pass from behind outward and upward; 
 the outer third is smooth. The oblique ridges give attachment to the tendinous 
 mtersections, and the surfaces between them to the fleshv fibres, of the Sub- 
 
172 THE SKELETON 
 
 scapularis muscle. The anterior third of the fossa, which is smooth, is covered 
 by, but does not afford attachment to, the fibres of this muscle. The venter is 
 separated from the internal border by a smooth, triangular margin at the supe- 
 rior and inferior angles, and in the interval between these by a narrow edge which 
 is often deficient. This marginal surface affords attachment throughout its entire 
 extent to the vSerratus magnus muscle. The subscapular fossa presents a trans- 
 verse depression at its upper part, where the bone appears to be bent on itself, 
 forming a considerable angle, called the subscapulax angle (angulus subscapularis) , 
 thus giving greater strength to the body of the bone from its arched form, whilst 
 the summit of the arch serves to support the spine and acromion process. It is in 
 this situation that the fossa is deepest, so that the thickest part of the Subscapu- 
 laris muscle lies in a line perpendicular to the plane of the glenoid cavity, and 
 must consequently operate most effectively on the head of the humerus, which 
 is contained in that cavity. The portion of bone between the suprascapular 
 notch and the infraglenoid tubercle is sometimes called the surgical neck. 
 
 Posterior or Dorsal Surface or Dorsum (facies dorsalis) . — The posterior or dorsal 
 surface (Fig. 127) is arched from above downward, alternately concave and 
 convex from side to side. It is subdivided unequally into two parts by the 
 spine ; the portion above the spine is called the supraspinous fossa, and that below 
 it the infraspinous fossa. 
 
 The supraspinous fossa {fossa supraspinata) , the smaller of the two, is concave, 
 smooth, and broader at the vertebral than at the humeral extremity. It affords 
 attachment by its inner two-thirds to the Supraspinatus muscle. 
 
 The infraspinous fossa (fossa infraspinata) is much larger than the preceding; 
 toward its vertebral margin a shallow concavity is seen at its upper part; its centre 
 presents a prominent convexity, whilst toward the axillary border is a deep groove 
 which runs from the upper toward the lower part. The inner two-thirds of this 
 surface affords attachment to the Infraspinatus muscle; the outer third is only cov- 
 ered by it, without giving origin to its fibres. This surface is separated from the 
 axillary border by an elevated ridge, which runs from the lower margin of the glenoid 
 cavity downward and backward to the posterior border, about an inch above the in- 
 ferior angle. The ridge serves for the attachment of a strong aponeurosis which 
 separates the Infraspinatus from the two Teres muscles. The surface of bone between 
 this line and the axillary border is narrow in the upper two-thirds of its extent, 
 and traversed near its centre by a groove for the passage of the dorsalis scapulae 
 vessels; it affords attachment to the Teres minor muscle. Its lower third presents a 
 broader, somewhat triangular surface, which gives origin to the Teres major, and 
 over which the Latissimus dorsi glides; sometimes the latter muscle takes origin 
 by a few fibres from this part. The broad and narrow portions of bone above 
 alluded to are separated by an oblique line which runs from the axillary border, 
 downward and backward, to meet the elevated ridge: to it is attached the 
 aponeurosis separating the two Teres muscles from each other. 
 
 The spine {spina scapuloe) is a prominent plate of bone which crosses obliquely 
 the inner four-fifths of the dorsum of the scapula at its upper part, and separates the 
 supra- from the infraspinous fossa : it commences at the vertebral border by a smooth, 
 triangular surface, over which the Trapezius glides, separated from the bone by a 
 bursa, and, gradually becoming more elevated as it passes outward, terminates in 
 the acromion process, which overhangs the shoulder-joint. The spine is triangular 
 and flattened from above downward, its apex corresponding to the vertebral 
 border, its base (which is directed outward) to the neck of the scapula. It pre- 
 sents two surfaces and three borders. Its superior surface is concave, assists 
 in forming the supraspinous fossa, and affords attachment to part of the Supra- 
 spinatus muscle. Its inferior surface forms part of the infraspinous fossa, gives 
 origin to part of the Infraspinatus muscle, and presents near its centre the orifice 
 
THE SCAPULA 
 
 173 
 
 of a nutrient canal. Of the three borders, the anterior is attached to the dorsum 
 of the bone; the posterior, or crest of the spine, is broad, and presents two hps 
 and an intervening rough interval. To the superior hp is attached the Trapezius 
 to the extent shown in the figure. A rough tubercle is generally seen occupying 
 that portion of the spine which receives the insertion of the middle and inferior 
 fibres of this muscle. To the inferior lip, throughout its whole length, is attached 
 
 Coracoi(f 
 
 Vor ^ 
 
 Groove for Dorsalis 
 Scapulx Artery. 
 
 inferior 
 Fig. 127. — Left scapula. Posterior surface or dorsum. 
 
 the Deltoid. The intervals between the lips is also partly covered by the tendinous 
 fibres of these muscles. The external border, or base, the shortest of the three, is 
 slightly concave, its edge thick and round, continuous above with the under sur- 
 face of the acromion process, below with the neck of the scapula. The narrow 
 portion of bone external to this border, and separating it from the glenoid cavity, 
 is called the great scapular notch, and serves to connect the supra- and infraspinous 
 fossae. 
 
174 THE SKELETON 
 
 The acromion process (acromion), so called from forming the summit of the 
 shoulder (dxpou, a summit; (h/io^, the shoulder), is a large and somewhat triangular 
 or oblong process, flattened from behind forward, directed at first a little outward, 
 and then curving forward and upward, so as to overhang the glenoid cavity. Its 
 upper surface, directed upward, backward, and outward, is convex, rough, and 
 gives attachment to some fibres of the Deltoid, and in the rest of its extent it is 
 subcutaneous. Its under surface is smooth and concave. Its outer border is thick 
 and irregular, and presents three or four tubercles for the tendinous origins of the 
 Deltoid muscle. Its inner margin, shorter than the outer, is concave, gives attach- 
 ment to a portion of the Trapezius muscle, and presents about its centre a small 
 oval surface for articulation with the acromial end of the clavicle. Its apex, which 
 corresponds to the point of meeting of these two borders in front, is thin, and 
 has attached to it the coraco-acromial ligament. 
 
 Margins or Borders of the Scapula. Superior Border (margo superior) . — Of the 
 three borders of the scapula, the superior is the shortest and thinnest; it is concave 
 and extends from the superior angle to the coracoid process. At its outer part is a 
 deep, semicircular notch, the suprascapular notch {incisura scapulae) , formed partly 
 by the base of the coracoid process. This notch is converted into a foramen by the 
 transverse ligament, and serves for the passage of the suprascapular nerve. Some- 
 times this foramen is entirely surrounded by bone. The adjacent margin of the 
 superior border affords attachment to the Omo-hyoid muscle. 
 
 External or Axillary Border {margo axillaris) .—The external or axillary border 
 is the thickest of the three. It commences above at the lower margin of the 
 glenoid cavity, and inclines obliquely downward and backward to the inferior 
 angle. Immediately below the glenoid cavity is a rough impression, the infra- 
 glenoid tubercle {tuberositas infraglenoidalis) , about an inch in length, which 
 affords attachment to the long head of the Triceps muscle; in front of this is 
 a longitudinal groove, which extends as far as the lower third of the axillary 
 border and affords origin to part of the Subscapularis muscle. The inferior 
 third of this border, which is thin and sharp, serves for the attachment of a few 
 fibres of the Teres major behind and the Subscapularis in front. 
 
 Internal or Vertebral Border {margo vertebralis) . — The internal or vertebral bor- 
 der, also named the base, is the longest of the three, and extends from the superior to 
 the inferior angle of the bone. It is arched, is intermediate in thickness between the 
 superior and the external borders, and the portion of it above the spine is bent con- 
 siderably outward, so as to forai an obtuse angle with the lower part. The vertebral 
 border presents an anterior lip, a posterior lip, and an intermediate space. The ante- 
 rior lip affords attachment to the Serratus magnus ; the posterior lip, to the Supra- 
 spinatus above the spine, the Infraspinatus below; the interval between the two lips, 
 to the Levator anguli scapulae above the triangular surface at the commencement 
 of the spine, the Rhomboideus minor to the edge of that surface; the Rhomboideus 
 major being attached by means of a fibrous arch connected above to the lower 
 part of the triangular surface at the base of the spine, and below to the lower part 
 of the posterior border. 
 
 Angles. Superior or Mesial Angle {angulus medialis) . — Of the three angles, the 
 superior, formed by the junction of the superior and internal borders, is thin, 
 smooth, rounded, somewhat inclined outward, and gives attachment to a few 
 fibres of the Levator anguli scapulae muscle. 
 
 Inferior Angle (angulus inferior). — The inferior angle, thick and rough, is 
 formed by the union of the vertebral and axillary borders, its outer surface 
 affording attachment to the Teres major and frequently to a few fibres of the 
 Latissimus dorsi. 
 
 Anterior or Lateral Angle {angidus lateralis) . — The anterior angle is the thickest 
 part of the bone, and forms what is called the head of the scapula. The head 
 
THE SCAPULA 
 
 175 
 
 presents a shallow, pyriforra, articular surface, the glenoid surface or cavity {cav- 
 itas glenoidalis , from y/rjvT^, a socket), whose longest diameter is from above 
 downward, and its direction outward and forward. It is broader below than 
 above. Just above it is a rough surface, the supraglenoid tubercle or tuberosity 
 (tuberositas supraglenoidalis) , to which is attached the long tendon of the Biceps 
 muscle. The glenoid cavity is covered with cartilage in the recent state; and 
 its margins are slightly raised and give attachment to a fibro-cartilaginous struc- 
 ture, the glenoid ligament, by which its cavity is deepened. The anatomical neck 
 of the scapula (collum scajmlae) is the slightly depressed surface which surrounds 
 the head ; it is more distinct on the posterior than on the anterior surface, and 
 below than above. In the latter situation it has arising from it a thick prominence, 
 the coracoid process. 
 
 The coracoid process (processus coracoideus) , so called from its fancied resemblance 
 to a crow's beak (x6(>a^, a crow), is a thick, curved process of bone which arises by 
 a broad base from the upper part of the neck of the scapula; it is directed at first 
 upward and inward, then, becoming smaller, it changes its direction and passes for- 
 ward and outward. The ascending portion, flattened from before backward, pre- 
 sents in front a smooth, concave 
 
 surface over which passes the ^/J^ ^foi- ^ 
 
 Subscapularis muscle. The '^^ " " ^^ 
 
 horizontal portion is flattened 
 from above downward, its upper 
 surface is convex and irregular, 
 and gives attachment to the 
 Pectoralis minor; its under sur- 
 face is smooth ; its inner border 
 is rough, and gives attachment 
 to the Pectoralis minor; its outer 
 border is also rough for the 
 coraco-acromial ligament, while 
 the apex is embraced by the 
 conjoined tendon of origin of 
 the short head of the Biceps 
 and of the Coraco-brachialis 
 and gives attachment to the 
 costo-coracoid ligament. At the 
 inner side of the root of the 
 coracoid process is a rough im- 
 pression for the attachment of 
 the conoid ligament; and run- 
 ning from it obliquely forward 
 and outward on the upper sur- 
 face of the horizontal portion, 
 an elevated ridge for the attach- 
 ment of the trapezoid ligament. 
 
 Structure.— In the head, pro- 
 cesses, and all the thickened 
 parts of the bone the scapula is composed of cancellous tissue, while in the rest of 
 its extent it is composed of a thin layer of dense, compact tissue. " The centre part 
 of the supraspinous fossa and the upper part of the infraspinous fossa, but especially 
 the former, are usually so thin as to be semitransparent ; occasionally the bone is 
 found wanting in this situation, and the adjacent muscles come into contact. 
 
 Development (Fig. 128). — By seven or more centres: one for the body, two for 
 the coracoid process, two for the acromion, one for the vertebral border, and one 
 
 fifenot 
 
 Fig. 128. — Plan of the development of the scapula. By seven 
 centres. The epiphyses (except one for the coracoid process) 
 appear from fifteen to seventeen years, and unite between twenty- 
 two and twenty-five years of age. 
 
176 THE SKELETON 
 
 For the inferior angle. Ossification of the body of the scapula commences about 
 the second month of f(»*tal life by tiie fonn.ition of an invfj^nhir (|na(lrihiteral 
 plate of bone ininiediately behind the j^lenoid cavity. This plate extends itself so 
 as to form the chief part of the bone, the spine growing up from its posterior, 
 surface about the third month. At birth a large j)art of the scapula is osseous, 
 but the glenoid cavity, coracoid and acromion processes, the |)osterior border, and 
 inferior angle are cartilaginous. From the fifteenth to the eighteenth month after 
 birth ossification takes place in the middle of the coracoid process, which usually 
 becomes joined with the rest of the bone at the time when the other centres make 
 their aj)pearance. Between the fourteenth and twentieth years ossification of the 
 remaining centres takes place in (juick succession, and in the following onler: 
 first, in the root of the coracoid process, in the form of a broad scale; secondly, 
 near the base of the acromion process; thirdly, in the inferior angle and contigu- 
 ous part of the posterior border; fourthly, near the extremity of the acromion; 
 fifthly, in the posterior border. The acromion process, besides !)eing formed of 
 two se{)arate nuclei, has its base formed by an extension into it of tlie centre of 
 ossification which belongs to the spine, the extent of which varies in different 
 cases. The two separate nuclei unite, and then join with the extension from the 
 spine. These various epiphyses become joined to the bone between the ages of 
 twenty-two and twenty-five years. Sometimes failure of union between the 
 acromion process and spine occurs, the junction being effected by fibrous tissue 
 or by an imperfect articulation; in some cases of supposed fracture of the acromion 
 with ligamentous union it is probable that the detached segment was never united 
 to the rest of the bone. The upper third of the glenoid cavity is usually ossified 
 from a separate centre (subcoracoid) which makes its appearance between the 
 tenth and eleventh years. Very often, in addition, an epiphysis appears for the 
 lower part of the glenoid cavity. 
 
 Articulations. With the humerus and clavicle. 
 
 Attachment of Muscles. — To seventeen: to the anterior surface, the Subscapu- 
 laris; posterior surface, Supraspinatus, Infraspinatus; spine. Trapezius, Deltoid; 
 superior border, Omo-hyoid; vertebral border, Serratus magnus, Levator anguli 
 scapida\ Hhomboideus minor and major; axillary border. Triceps, Teres minor, 
 Teres major; apex of glenoid cavity, long head of the Biceps; coracoid process, 
 short head of the Hice{)s, Coraco-brachialis, Pectoralis minor; and to the inferior 
 angle occasionally a few fibres of the Latissimus dorsi. 
 
 Surface Form.— The only parts of the scapula which are truly subcutaneous are the spine 
 and acromion process, but, in addition to those, the coracoid process, the internal or vcrteoral 
 l)order and inferior anjjfe, and, to a less extent, the axillary border, may be defined. TIic acro- 
 mion process and s}>ine of the scapula are easily felt throuji;hout their entiiv leno;th, forming, 
 with tile clavicle, the ar<'li of the shoulder. The acromion can be ascertained to be connected 
 to the clavicle at the acromio-clavicular joint by runninji the finjier alonjj; it, its position being 
 often indicated bv an irrcfjularity or bony outjjrowth from the clavicle close to the joint. The 
 acronuon can be tclt forming the point of the shoulder, and from this can be traced backward to 
 join the spine of the scapula. The plai'c of junction is usually denoted by a prominence, which is 
 sumctimes called the acromial angle. From here the spine of the scapula can be felt as a promi- 
 nent ridge of bone, marked on the surface as an oblicjuc depression, which becomes less and less 
 distinct, and terminates a little external to the spinous processes of the vertebra'. Its termination is 
 usually indicated by a slight chniple in the skin on a level with the interval between the third and 
 fourth dorsal spines, below this point the vertebral border of the scapula may be trai-etl, running 
 downward and outward, and thus diverging from the vertebral spines, to the inferior angle of 
 the bone, which can be recognized, although covered by the Latissimus dorsi muscle. From 
 this angle the axillary border can usually be traced through this thick nuiscular covering, form- 
 ing, with the nniscles, the posterior fold of the axilla. The coracoid nroccss may be felt about 
 an inch below the junction of the middle and outer thirds of the clavicle. Here it is covered by 
 the anterior bonier of the deltoid and lies a little to the outer side of a slight depression which 
 corresponds to the interval l)etwecn the IVctoralis major and Deltoid nniscles. When the arms 
 are hanging by the side, the upper angle of the scapula corresponds to the upper bonier of tlie 
 
THE HUMERUS 177 
 
 second rih or (lie iiilcrval between the first and second dorsal spines, the inferior anple to the 
 upper lionlcr of i\w. eiffhth rih or the interval between tlu^ seventh and eifjhth dorsal spines. 
 
 Surgical Anatomy. Fnuiurr.i of the body of the scapula are ran;, owinj^ to the mobility of the 
 bone, the thick layer of muscles by which it is encased on both surfaces, and the elasticity of the 
 ribs on which it rests. Fracture of the neck of the bone is also uncommon. 'I'hc; most fre(juent 
 course of a line; of fracture of the neck is from the su|)rascapular notch to the infraglenoid 
 tubercle {nurt/ictil neck), and it derives its princi|)al interest from its simulation to a subj^lenoid 
 dislocation of the humerus. The diagnosis can be made by noting the alteration in the position 
 of the coracoid process. A fracture of the neck external to, and not including, the coracoid 
 process {analoiiiiad nrric) is said to occur, but it is exceedingly doubtful whether such an 
 accident ever tak(!s place. The acromion process is more frc(juently broken than any other 
 part of the bone, and there is sometimes, in young subjects, a separation of the epiphysis. It 
 IS believed that many of the cases of supposed fracture of the acromion, with fibrous union, 
 which have been found on post-mortem examination are really cases of imperfectly united 
 e])iphysis. !^ir Astley C.ooper believed that most fractures of this bone united by fibrous 
 tissue, and the cause of this mode of um'on was the difficulty there was in keeping the frac- 
 tured ends in constant ap|)osition. TIk; <'oraeoi(l proces.s is occasionally broken off, either from 
 direct violence or perhaps, rarely, from mus<"ular action. 
 
 Tumor.i of various kinds grow from the scapula. Of the innocent form of tumors probably 
 the osteomata are th(! most coirnnon. When an osteoma grows from the venter of the sca|)ida, as it 
 sometimes <loes, it is of the compact variety, such as usually grows from membrane-formed bones, 
 as the bones of the skull. This wouhl app(!ar to afford evidence that this i)ortion of the bone 
 is foruKnl from membrane, and not, like; the rest of the bone, from cartilage. Sarcomatous 
 tumors somctiiiK's grow from the scapula, and may necessitate removal of the bone, with or 
 witlDUt amputation of the up|)er limb. Removal of the upper limb with th<; scapula and the 
 outer two-thirds of the clavicle is known as the intrrncajmlo-tlioracic, arnputntinn. The 
 scapula may be partially res(!cted or completely excised. There are several methods of com- 
 plete ex<'ision. 'I'lie bone may be excised by a T-sha{)ed incision, and, the flaps being reflected, 
 the removal is commenced from the oosterior or vertebral border, so that the subscapular 
 vessels which lie along the axillary boraer are among the last structures divided, and can be 
 at once secured. 
 
 THE ARM. 
 
 The arm is tluit portion of the upj)er extremity which i.s situated between the 
 .shoulder and the elhow. Its skeleton consists of a single bone, the humerus. 
 
 The Humerus or Upper Arm Bone (Figs. 129, 130). 
 
 The hmnerus (from humerus, or more correctly umerus, the .shoulder) is the 
 longest and largest bone of the upper extremity; it presents for examination a 
 shaft and two extremities. 
 
 Upper Extremity. — The upper extremity presents a large, rounded head, 
 joined to the shaft by a constricted portion, called the neck, and two other emi- 
 nences, the greater and lesser tuberosities. 
 
 The Head (caput humeri). — The head, nearly hemispherical in form,* is directed 
 upward, inward, and slightly backward, and articulates with the glenoid cavity 
 of the scapula; its surface is smooth and coated with cartilage in the recent .state. 
 The circumference of its articular surface is slightly constricted, and is termed 
 the anatomical neck, in contradistinction to th(^ constriction which exists below the 
 tiibcrosilics. The latter is called the surgical neck (collum chirurgicum) ,hom its 
 often being the seat of fracture. It should be remembered, however, that frac- 
 ture of the anatomical neck does sometimes, though rarely, occur. 
 
 A.N'ATO.MiCAL Nkck (collurri anatomicum). — The anatomical neck is oblicjuely 
 directed, forming an obtuse angle with the shaft. It is more distinctly marked in 
 the lower half of its circiunference than in the upper half, where it presents a nar- 
 row groove, .separating the head from the tuberosities. Its circumference affords 
 
 ' ThouKh the head is nearly heminpherical in form, its marfcin, an Sir ('•. Humphry haw xhown, is by no meanH 
 a true circle. U-s greatest measurement is from the top of the l)icipital groove in a (jirection downward, inward, 
 and backward. Hence it follows that the greatest elevation of the arm can be obtained by rolling the articular 
 surface in this direction- that is to say, obliquely upward, outward, and forward. 
 
 12 
 
178 
 
 THE SKELETON 
 
 Surgical nech.- 
 
 >SUPINATOR RADII LONQUS. 
 
 ^■m 
 
 ^EXTENSOR CARPI RADIALI8 
 LONQIOR. 
 
 Common origin of- 
 
 FLEXOR CARPI RADIALIS. 
 PALMARIS LONQUS. 
 FLEXOR SUBLIMIS DIQITORUM. 
 FLEXOR CARPI ULNARIS. 
 
 'i'^.. 
 
 Common origin of 
 
 i EXTENSOR CARPI RADIALIS BREVISt 
 (• ■■ COMMUNIS DIOITORUM. 
 
 " MINIMI DIQITI. 
 ' CARPI ULNARIS. 
 SUPINATOR BREVIS. 
 
 Fig. 129. — Left humerus. Anterior view. 
 
THE HUMERUS 179 
 
 attachment to the capsular hgament and is perforated by numerous vascular 
 foramina. 
 
 Greater Tuberosity (tuberculum ma jus). — The greater tuberosity is situated on 
 the outer side of the head and lesser tuberosity. Its upper surface is rounded and 
 marked by three flat facets, separated by two slight ridges: the highest facet gives 
 attachment to the tendon of the Supraspinatus; the middle one, to the Infra- 
 spinatus; the inferior facet and the shaft of the bone below it, to the Teres minor. 
 The outer surface of the great tuberosity is convex, rough, and continuous with 
 the outer side of the shaft. 
 
 Lesser Tuberosity (tuberculum minus). — The lesser tuberosity is more promi- 
 nent, although smaller than the greater: it is situated in front of the head, and 
 is directed inward and forward. Its summit presents a prominent facet for the 
 insertion of the tendon of the Subscapularis muscle. The tuberosities are sepa- 
 rated from one another by a deep groove, the bicipital groove (sulcus intertuber- 
 cularis). This groove lodges the long tendon of the Biceps muscle, with which 
 runs a branch of the anterior circumflex artery. It commences above between 
 the two tuberosities, passes obliquely downward and a little inward, and ter- 
 minates at the junction of the upper with the middle third of the bone. It is 
 deep and narrow at the commencement, and becomes shallow and a little broader 
 as it descends. Its borders are called, respectively, the external or posterior bicipital 
 ridge {crista tuberculi majoris) and the internal or anterior bicipital ridge (crista 
 tuherculi minoris), and form the upper part of the anterior and internal borders 
 of the shaft of the bone. In the recent state it is covered with a thin layer of 
 cartilage, lined by a prolongation of the synovial membrane of the shoulder- 
 joint, and receives the tendon of insertion of the I-atissimus dorsi muscle. 
 
 The Shaft (corpus humeri) . — The shaft of the humerus is almost cylindrical in 
 the upper half of its extent, prismatic and flattened below, and presents three 
 borders an<l three surfaces for examination. 
 
 Anterior Border. — The anterior border runs from the front of the great tuber- 
 osity above to the coronoid depression below, separating the internal from the 
 external surface. Its upper part is very prominent and rough, and forms the 
 outer lip of the bicipital groove. It is sometimes called the posterior bicipital, 
 external bicipital, or pectoral ridge (crista tuberculi majoris), and serves for the 
 attachment of the tendon of the Pectoralis major. About its centre it forms the 
 anterior boundary of the rough deltoid eminence or impression (tuberositas deltoidea) ; 
 below, it is smooth and rounded, affording attachment to the Brachialis anticus 
 muscle. 
 
 External Border (margo lateralis). — The external border runs from the back 
 part of the greater tuberosity to the external condyle, and separates the external 
 from the posterior surface. It is rounded and indistinctly marked in its upper 
 half, serving for the attachment of the lower part of the insertion of the Teres 
 minor muscle, and below this of the external head of the Triceps muscle ; its centre is 
 traversed by a broad but shallow, oblique depression, the musculo-spiral groove 
 (sulcus nervi radialis) ; its lower part is marked by a prominent, rough margin, 
 a little curved from behind forward, the external supracondylar or epicondylic ridge 
 (marr/o lateralis), which presents an anterior lip for the attachment of the Supin- 
 ator longus above and Extensor carpi radialis longior below, a posterior lip for 
 the Triceps, and an intermediate space for the attachment of the external inter- 
 muscular septum. 
 
 Internal Border (margo medialis). — The internal border extends from the lesser 
 tuberosity to the internal condyle. Its upper third is marked by a prominent 
 ridge, forming the posterior lip of the bicipital groove, and gives attachment to 
 the tendon of the Teres major. About its centre is an impression for the attach- 
 ment of the Coracobrachialis, and just below this is seen the entrance of the 
 
180 
 
 THE SKELETON 
 
 
 '«^. 
 
 Fig. 130. — Left humerus. Posterior surface. 
 
 nutrient canal, directed downward. Sometimes 
 there is a second canal situated at the com- 
 mencement of the musculo-spiral groove, for a 
 nutrient artery derived from the superior pro- 
 funda branch of the brachial artery. The in- 
 ferior third of this border is raised into a slig-ht 
 ridge, the internal supracondylar or epicondylic 
 ridge (margo medialis), which becomes very 
 prominent below; it presents an anterior lip 
 for the attachment of the Brachialis anticus 
 muscle, a posterior lip for the internal head of 
 the Triceps muscle, and an intermediate space 
 for the attachment of the internal intermuscular 
 septum. 
 
 External Surface (facies anterior lateralis). — 
 The external surface is directed outward above, 
 where it is smooth, rounded, and covered by the 
 Deltoid muscle ; forward and outward below, 
 where it is slightly concave from above down- 
 ward, and gives origin to part of the Brachi- 
 alis anticus muscle. About the middle of this 
 surface is seen a rough, triangular impression 
 for the insertion of the Deltoid muscle, deltoid 
 impression (tuberositas deltoidea) ; and below it 
 the musculo-spiral groove, directed obliquely 
 from behind, forward and downward, and trans- 
 mitting the musculo-spiral nerve and superior 
 profunda artery. 
 
 Internal Surface (facies anterior medialis). — 
 The internal surface, less extensive than the ex- 
 ternal, is directed inward above, forward and 
 inward below; at its upper part it is narrow and 
 forms the floor of the bicipital groove: to it is 
 attached the Latissimus dorsi. The middle part 
 of this surface is slightly rough for the attach- 
 ment of some of the fibres of the tendon of 
 insertion of the Coraco-brachialis ; its loweM 
 part is smooth, concave from above downward^ 
 and gives attachment to the Brachialis anticus 
 muscle.^ A little below the middle of the shafl 
 is the nutrient foramen (foramen nutriciwmn 
 
 ' A small, hook-shaped process of bone, the supracondylar prt^ 
 cess, varying from '/lo to ^/4 of an inch in length, is not infrequentl 
 found projecting from the inner surface of the shaft of the humeru 
 two inches above the internal condyle. It is curved downward 
 forward, and inward, and its pointed extremity is connected t 
 the internal border, just above the inner condyle, by a ligamel 
 or fibrous band, which gives origin to a portion of the Pronato 
 radii teres; through the arch completed by this fibrous band tb 
 median nerve and brachial artery pass when these structun 
 deviate from their usual course. Sometimes the nerve alone i 
 transmitted through it, or the nerve may be accompanied by tfc 
 ulnar artery in cases of high division of the brachial. A well-marke 
 groove is usually found behind the process in which the nerve and 
 artery are lodged. This space is analogous to the .supracondyloi^ 
 foramen in many animals, and probably serves in them to protei 
 the nerve and artery from compression during the contractio 
 of the muscles in this region. A detailed account jf this procea 
 is given by Dr. Struthers, in his Anatomical and Physiologiea 
 Observations, p. 202. An acces.sory portion of the Coraco-bra 
 chialis muscle is frequently connected with this process, accordint 
 to Mr. J. Wood (Journal of Anat. and Phys., No. 1, November 
 1866. p. 47). 
 
THE HUMERUS 181 
 
 This leads into a nutrient canal (canalis nutricius), which is directed toward the 
 elbow-joint (distally) . 
 
 Posterior Surface (fades posterior), — The posterior surface (Fig. 130) appears 
 somewhat twisted, so that its upper part is directed a little inward, its lower part 
 backward and a little outward. Nearly the whole of this surface is covered by 
 the external and internal heads of the Triceps, the former of which is attached 
 to its upper and outer part, the latter to its inner and back part, the two being 
 separated by the musculo-spiral groove. 
 
 Lower Extremity. — The lower extremity is flattened from before back- 
 ward, and curved slightly forward; it terminates below in a broad, articular 
 surface which is divided into two parts by a slight ridge. Projecting on 
 either side are the external and internal condyles (epicondyliis lateralis and 
 epicondylus medialis). By some anatomists the external condyle is called the 
 external epicondyle and the internal condyle is called the internal epicondyle. 
 Others call the internal condyle the epitrochlea. The articular surface extends a 
 little lower than the condyles, and is curved slightly forward, so as to occupy the 
 more anterior part of the bone; its greatest breadth is in the transverse diameter, 
 and it is obliquely directed, so that its inner extremity occupies a lower level than 
 the outer. The outer portion of the articular surface presents a smooth, rounded 
 eminence, which has received the name of the capitellum, or radial head of the 
 humerus {capitulum humeri); it articulates with the cup-shaped depression on 
 the head of the radius, and is limited to the front and lower part of the bone, 
 not extending as far back as the other portion of the articular surface. On the 
 inner side of this eminence is a shallow, groove, in which is received the inner 
 margin of the head of the radius. Above the front part of the capitellum is a 
 slight depression, the radial fossa (fossa radialis), which receives the anterior 
 bonier of the head of the radius when the forearm is flexed. The inner por- 
 tion of the articular surface, the trochlea (trochlea humeri), presents a deep 
 depression between two well-marked borders. This surface is convex from 
 before backward, concave from side to side, and occupies the anterior, lower, 
 and posterior parts of the bone. The external border, less prominent than the 
 internal, corresponds to the interval between the radius and the ulna. The 
 internal border is thicker, more prominent, and consequently of greater length, 
 than the external. The grooved portion of the articular surface fits accurately 
 within the greater sigmoid cavity of the ulna: it is broader and deeper on the pos- 
 terior than on the anterior aspect of the bone, and is inclined obliquely from 
 behind forward and from without inward. Above the front part of the trochlear 
 surface is seen a smaller depression, the coronoid fossa (fossa coronoidea), which 
 receives the coronoid process of the ulna during flexion of the forearm. Above 
 the back part of the trochlear surface is a deep, triangular depression, the 
 olecranon fossa (fossa olecrani), in which is received the summit of the olecranon 
 process in extension of the forearm. These fossae are separated from one another by 
 a thin, transparent lamina of bone, which is sometimes perforated by a foramen, 
 the supratrochlear foramen; their upper margins afford attachment to the anterior 
 and posterior ligaments of the elbow-joint, and they are lined, in the recent state, 
 by the synovial membrane of this articulation. The articular surfaces, in the 
 recent state, are covered with a thin layer of cartilage. The external epicon- 
 dyle (epicondylus lateralis) is a small, tubercular eminence, less prominent 
 than the internal, curved a little forward, and giving attachment to the external 
 lateral ligament of the elbow-joint, and to a tendon common to the origin of some 
 of the extensor and supinator muscles. The internal epicondyle (epitrochlea or 
 epicondylus medialis), larger and more prominent, and therefore more liable to 
 fracture, than the external, is directed a little backward: it gives attachment to 
 the internal lateral ligament, to the Pronator radii teres, and to a tendon common 
 
182 
 
 THE SKELETON 
 
 to the origin of some of the flexor muscles of the forearm. The ulnar nerve runs 
 in a groove, the ulnar groove (sulcus nervi ulnaris), at the back of the internal 
 condyle, or between it and the olecranon process. These condyles are directly 
 continuous above with the external and internal supracondylar ridges. 
 
 Structure. — The extremities consist of cancellous tissue, covered with a thin 
 compact layer; the shaft is composed of a cylinder of compact tissue, thicker at 
 the centre than at the extremities, and hollowed out by a large medullary canal, 
 which extends along its whole length. In the head of the humerus the plates 
 of the cancellous tissue are arranged in 
 curves (Fig. 131) known as pressure curves. 
 Most of the bone-plates are at right angles 
 to the plane of the articular surface (the 
 lines of greatest pressure), and they are 
 bound together by other bone-fibres, which 
 usually correspond to the plane of the 
 
 Epiphyses of head and 1 ^^ 
 tuberosities Mend at %-/^ 
 5th year, and unite \ ' 
 with shaft at 2(Hh 
 
 year. 
 
 Fig. 131. — Diagram showing the architecture of the supe- 
 rior extremity of the humerus. (Poirier and Charpy.) 
 
 Unites with shaft ] c5 
 at 18th year. J 
 
 Sha/t at 
 
 Fig. 132.^Plan of the development of the 
 humerus by seven centres. 
 
 articulation (the lines of greatest tension) . This arch-like arrangement strength- 
 ens the head of the bone, and it is further strengthened by the binding fibres. 
 
 Development. — By seven, or occasionally eight, centres (Fig. 132) : one for the 
 shaft, one for the head, one for the tuberosities, one for the radial head, one for 
 the trochlear portion of the articular surface, and one for each condyle. The 
 nucleus for the shaft appears near the centre of the bone in the eighth week, and 
 soon extends toward the extremities. At birth the humerus is ossified nearly in 
 its whole length, the extremities remaining cartilaginous. During the first year, 
 sometimes even before birth, ossification commences in the head of the bone, and 
 during the third year the centre for the tuberosities makes its appearance, usually 
 by a single ossific point, but sometimes, according to Beclard, by one for each 
 tuberosity, that for the lesser being small and not appearing until the fifth year. 
 By the sixth year the centres for the head and tuberosities have increased in size 
 and become joined, so as to form a single large epiphysis. 
 
 The lower end of the humerus is developed in the following manner: At the 
 end of the second year ossification commences in the capitellum, and from this 
 point extends inward, so as to form the chief part of the articular end of the bone, 
 
THE HUMERUS 183 
 
 the centre for the inner part of the trochlea not appearing until about the age of 
 twelve. Ossification commences in the internal condyle about the fifth year, and 
 in the external one not until about the thirteenth or fourteenth year. About six- 
 teen or seventeen years the outer condyle and both portions of the articulating 
 surface (which have already joined) unite with the shaft; at eighteen years the inner 
 condyle becomes joined; while the upper epiphysis, although the first formed, is 
 not united until about the twentieth year. 
 
 Articulations. — With the glenoid cavity of the scapula and with the ulna and 
 radius. 
 
 Attachment of the Muscles. — To twenty-four: to the greater tuberosity, the 
 Supraspinatus, Infraspinatus, and Teres minor; to the lesser tuberosity, the 
 Subscapularis ; to the anterior bicipital ridge, the Pectoralis major; to the posterior 
 bicipital ridge, the Teres major; to the bicipital groove, the Latissimus dorsi; to 
 the shaft, the Deltoid, Coraco-brachialis, Brachialis anticus, external and internal 
 heads of the Triceps; to the internal condyle, the Pronator radii teres, and common 
 tendon of the Flexor carpi radialis, Palmaris longus, Flexor sublimis digitorum, 
 and Flexor carpi ulnaris; to the external condyloid ridge, the Supinator longus 
 and Extensor carpi radialis longior; to the external condyle, the common tendon 
 of the Extensor carpi radialis brevior. Extensor communis digitorum, Extensor 
 minimi digiti, Extensor carpi ulnaris, and Supinator brevis; to the back of the 
 external condyle, the Anconeus, 
 
 Surface Form. — The humerus is almost entirely clothed by the muscles which surround it, 
 and the only ])arts of this bone which are strictly subcutaneous are small portions of the 
 internal and external condyles. In addition to these, the tuberosities and a part of the head 
 of the bone can be felt under the skin and muscles by which they, are covered. Of these the 
 greater tuberosity forms the most prominent bony point of the shoulder, extending beyond the 
 acromion process and covered by the Deltoid muscle. It influences materially the surface form 
 of the shoulder. It is best felt while the arm is lying loosely by the side; if the arm be raised, 
 it recedes from under the finger. The lesser tuberosity, directed forward and inward, is to be 
 felt to the inner side of the greater tuberosity, just below the acromio-clavicular joint. Between 
 the two tuberosities lies the bicipital groove. This can be defined by placing the finger and 
 making firm pressure just internal to the greater tuberosity; then, by rotating the humerus, the 
 groove will be felt to pass under the finger as the bone is rotated. With the arm abducted from 
 the side, by pressing deeply in the axilla the lower part of the head of the bone is to be felt. 
 On each side of the elbow-joint, and just above it, the internal and external condyles of the 
 bone are to be felt. Of these the internal is the more prominent, but the ridge passing upward 
 from it, the internal condyloid ridge, is much less marked than the external, and, as a rule, is 
 not to be felt. Occasionally, however, we find along this border the hook-shaped process men- 
 tioned above. The external condyle is most plainly to be seen during semiflexion of the fore- 
 arm, and its position is indicated by a depression between the attachment of the adjacent mus- 
 cles. From it is to be felt a strong bony ridge running up the outer border of the shaft of the 
 bone. This is the external supracondylar ridge; it is concave forward, and corresponds with 
 the curved direction of the lower extremity of the humerus. 
 
 Surgical Anatomy. — There are several points of surgical interest connected with the 
 humerus. First, as regards its development. The upper end, though the first to ossify, is the 
 last to join the shaft, and the length of the bone is mainly due to growth from this upper 
 epiphysis. Hence, in cases of amputation of the arm in young subjects the humerus continues 
 to grow considerably, and the end of the bone, which immediately after the operation was cov- 
 ered with a thick cushion of soft tissue, begins to project, thinning the soft parts and rendering 
 the stump conical. This may necessitate another operation, which consists in the removal of a 
 couple of inches or so of the bone, and even after this operation a recurrence of the conical stump 
 may take place. 
 
 There are several points of surgical interest in connection with fractures. First, as regard 
 their causation: the bone may be broken by direct or indirect violence like the other long bones, 
 but, in addition to this, it is probably more frequently fractured by muscular action than any 
 other of this class of bone in the body. It is usually the shaft, just below the insertion of the 
 Deltoid, which is thus broken. Mr. Pick has seen the accident happen from throwing a stone, and 
 in an apparently healthy adult from cutting a piece of hard "cake tobacco" on a table. In this 
 latter case there was no disease of the bone that could be discovered. Fractures of the upper 
 end may take place through the anatomical neck, through the surgical neck, or separation of the 
 
184 "J" HE SKELETON 
 
 greater tuberosity may occur. Fracture of the anatomical neck is a very rare accident ; in fact, 
 it is doubted by some whether it ever occurs. These fractures are usually considered to be 
 intracapsular, but they are probably partly within and partly without the capsule, as the lower 
 part of the capsule is inserted some little distance below the anatomical neck, while the upper 
 part is attached to it. They may be impacted or non-impacted. In most cases there is little or 
 no displacement on account of the capsule, in whole or in part, remaining attached to the lower 
 fragment. But occasionally a very remarkable alteration in position takes place; the upper 
 fragment turns on its own axis, so that the cartilaginous surface of the head rests against the 
 upper end of the lower fragment. When the fractured end is entirely separated from all its 
 surroundings, its vascular supply must be entirely cut off, and one would expect it, theoretically, 
 to necrose. But this must be exceedingly rare, for Gurlt was unable to find a single authenti- 
 cated case recorded. Separation of the upper epiphysis of the humerus sometimes occurs in the 
 young subject, and is marked by a characteristic deformity by which the lesion may be at once 
 recognized. This consists in the presence of an abrupt projection at the front of the joint some 
 short distance below the coracoid process, caused by the upper end of the lower fragment. In 
 fractures of the shaft of the humerus the lesion may take place at any point, but appears to be 
 more common in the lower than in the upper part of the bone. The points of interest in con- 
 nection with these fractures are: (1) That the musculo-spiral nerve may be injured as it lies in the 
 groove on the bone, or may become involved in the calluL which is subsequently thrown out; 
 and (2) the frequency of non-union. This is believed to be more common in the humerus than 
 in any other bone, and various causes have been assigned for it. It would seem most probably 
 to be due to the difficulty that there is in fixing the shoulder-joint and the upper fragment, and 
 possibly the elbow-joint and lower fragment also. Other causes which have been assigned 
 for the non-union are: (1) That in attempting passive motion of the elbow-joint to overcome 
 any rigidity which may exist, the movement does not take place at the articulation, but at the 
 seat of fracture; or that the patient, in consequence of the rigidity of the elbow, in attempting 
 to flex or extend the forearm moves the fragment and not the joint. (2) The presence of small 
 portions of muscular tissue between the broken ends. (3) Want of support to the elbow, so 
 that the weight of the arm tends to drag the lower fragment away from the upper. An impor- 
 tant distinction to make in fractures of the lower end of the humerus is between those that 
 involve the elbow-joint and those which do not; the former are always serious, as they may lead 
 to stiffness of the joint and impairment of the utility of the limb. They include the T-shaped 
 fracture and oblique fractures which involve the articular surface. The fractures which do not 
 involve the joint are the transverse above the condyles and the so-called epitrochlear fracture, 
 in which the tip of the internal condyle is broken off, generally by direct violence. 
 
 Under the head of separation of the lower epiphysis two separate injuries have been described: 
 One where the whole oi the four ossific centres which form the lower extremity of the bone are 
 separated from the shaft; and secondly, where the articular portion is alone separated, the two 
 condyles remaining attached to the shaft of the bone. The epiphysial line between the shaft 
 and lower end runs across the bone just above the tips of the condyles, a point to be borne in 
 mind in performing the operation of excision. 
 
 Tumors originating from the humerus are of frequent occurrence. A not uncommon place 
 for a chondroma tc grow from is the shaft of the bone somewhere in the neighborhood of the 
 insertion of the deltoid. Sarcomata frequently grow from this bone. 
 
 THE FOREARM. 
 
 The forearm is that portion of the upper extremity which is situated between 
 the elbow and the wrist. Its skeleton is composed of two bones, the ulna and 
 radius. 
 
 The Ulna or Elbow Bone. 
 
 The ulna (Figs. 133 and 134), so called from its forming the elbow {coXivrj), is a 
 long bone, prismatic in form, placed at the inner side of the forearm, parallel with 
 the radius. It is the larger and longer of the two bones. Its upper extremity, of 
 great thickness and strength, forms a large part of the articulation of the elbow- 
 joint; it diminishes in size from above downward, its lower extremity being very 
 small, and excluded from the wrist-joint by the interposition of an interarticular 
 fibro-cartilage. It is divisible into a shaft and two extremities. 
 . Upper Extremity. — The upper extremity, the strongest part of the bone, 
 presents for examination two large, curved processes, the olecranon process and 
 
THE ULNA 
 
 185 
 
 Ulna 
 
 FLEXOR DIQITORUM 
 SUBLIMIS. 
 
 PRONATOR 
 RADII TERES 
 
 Radius. 
 
 i^^lr^^^-^ii&. 
 
 Occasional origin of 
 
 FLEXOR LONQUS POLLICIS. 
 
 Radial orifjin o/flexob 
 
 DIQITORUM SUBLIMIS. 
 
 SUPINATOR LONQUS. 
 
 Groove for ext. ossis 
 
 METACARPI POLLICIS 
 and EXT, BREV. POLL. 
 
 Styloid process. 
 Fig. 133. — Bones of the left forearm. Anterior surface. 
 
186 'J'HE SKELETON 
 
 the coronoid process; and two concave, articular cavities, the greater and lesser 
 sigmoid cavities. 
 
 Olecranon Process {olecranon). — The olecranon process {ioXivrj, elbow; xpaucuv, 
 head) is a large, thick, curved eminence situated at the upper and back part of 
 the ulna. It is curved forward at the summit so as to present a prominent tip 
 which is received into the olecranon fossa of the humerus in extension of the fore- 
 arm ; its base being contracted where it joins the shaft. This is the narrowest part 
 of the upper end of the ulna, and, consequently, the most usual seat of fracture. 
 The posterior surface of the olecranon, directed backward, is triangular, smooth, 
 subcutaneous, and covered by a bursa. Its upper surface is of a quadrilateral 
 form, marked behind by a rough impression for the attachment of the Triceps 
 muscle; and in front, near the margin, by a slight transverse groove for the 
 attachment of part of the posterior ligament of the elbow-joint. Its interior sur- 
 face is smooth, concave, covered with cartilage in the recent state, and forms the 
 upper and back part of the great sigmoid cavity. The lateral borders present 
 a continuation of the same groove that was seen on the margin of the superior 
 surface; they serve for the attachment of ligaments — viz., the back part of the 
 internal lateral ligament internally, the posterior ligament externally. To the 
 inner border is also attached a part of the Flexor carpi ulnaris, while to the outer 
 border is attached the Anconeus muscle. 
 
 Coronoid Process {processus coronoideus) . — ^The coronoid process {xopcovfj, any- 
 thing hooked like a crow's beak) is a triangular eminence of bone which projects 
 horizontally forward from the upper and front part of the ulna. Its base is con- 
 tinuous with the shaft, and of considerable strength; so much so that fracture of 
 it is an accident of rare occurrence. Its apex is pointed, slightly curved upward, 
 and is received into the coronoid depression of the humerus in flexion of the forearm. 
 Its upper surface is smooth, concave, and forms the lower part of the greater sig- 
 moid cavity. The under surface is concave. At the junction of this surface with 
 the shaft is a rough eminence, the tubercle of the ulna {tuberositas ulnae), for the 
 attachment of the oblique ligament of the superior radio-ulnar articulation and the 
 Brachialis anticus muscle. Its outer surface presents a narrow, oblong, articular 
 depression, the lesser sigmoid cavity. The inner surface, by its prominent, free 
 margin, serves for the attachment of part of the internal lateral ligament. At 
 the front part of this surface is a small, rounded eminence for the attachment of 
 one head of the Flexor sublimis digitorum ; behind the eminence, a depression for 
 part of the origin of the Flexor profundus digitorum; and, descending from the 
 eminence, a ridge which gives attachment to one head of the Pronator radii teres. 
 Generally, the Flexor longus pollicis has an origin from the lower part of the 
 coronoid process by a rounded bundle of muscular fibres. 
 
 Greater Sigmoid Cavity {incisura semilunaris). — ^The greater sigmoid cavity, so 
 called from its resemblance to the old shape of the Greek letter 2', is a semi- 
 lunar depression of large size, formed by the olecranon and coronoid processes, 
 and serving for articulation with the trochlear surface of the humerus. About 
 the middle of either lateral border of this cavity is a notch which contracts it 
 somewhat, and serves to indicate the junction of the two processes of which it is 
 formed. The cavity is concave from above downward, and divided into two 
 lateral parts by a smooth, elevated ridge which runs from the summit of the 
 olecranon to the tip of the coronoid process. Of these two portions, the internal 
 is the larger, and is slightly concave transversely; the external portion is convex 
 above, slightly concave below. The articular surface, in the recent state, is 
 covered with a thin layer of cartilage. 
 
 Lesser Sigmoid Cavity {incisura radialis). — The lesser sigmoid cavity is a narrow,, 
 oblong, articular depression, placed on the outer side of the coronoid process, and 
 receives the lateral articular surface of the head of the radius. It is concave from 
 
THE ULKA 
 Ulna. 
 
 187 
 
 For EXT. CARPI RAD. LON' 
 
 extensor carpi radialis brevl'or. 
 
 extensor lonqus pollici 
 Fig. 134. 
 
 FLEXOR SUBLIMIS DIOITORUM. 
 
 For EXTENSOR CARPI ULNAHI8. 
 For EXTENSOR MINIMI D;OITI. 
 
 J!br| 
 Bones of the left forearm 
 
 EXTENSOR INDICIS. 
 
 EXTENSOR COMMUNIS DIQITORUM. 
 
 Posterior surface. 
 
188 THE SKELETON 
 
 before backward, and its extremities, which are prominent, serve for the attach- 
 ment of the orbicular Hgament. In the recent state it is covered with a thin layer 
 of cartilage. 
 
 The Shaft {corpus ulnos). — The shaft, at its upper part, is prismatic in form, and 
 curved from behind forward and from without inward, so as to be convex behind 
 and externally; its central part is quite straight; its lower part rounded, smooth, 
 and bent a little outward; it tapers gradually from above downward, and presents 
 for examination three borders and three surfaces. 
 
 Anterior or Palmar Border (margo volaris). — The anterior border commences 
 above at the prominent inner angle of the coronoid process, and terminates below 
 in front of the styloid process. It is well marked above, smooth and rounded in 
 the middle of its extent, and affords attachment to the Flexor profundus digitorum : 
 its lower fourth, marked off from the rest of the border by the commencement of 
 an oblique ridge on the anterior surface, serves for the attachment of the Pronator 
 quadratus. It separates the anterior from the internal surface. 
 
 Posterior or Dorsal Border {margo dor sails) . — The posterior border commences 
 above at the apex of the triangular subcutaneous surface at the back part of the 
 olecranon, and terminates below at the back part of the styloid process; it is well 
 marked in the upper three-fourths, and gives attachment to the aponeurosis com- 
 mon to the Flexor carpi ulnaris, the Extensor carpi ulnaris, and the Flexor pro- 
 fundus digitorum muscles; its lower fourth is smooth and rounded. This border 
 separates the internal from the posterior surface. 
 
 External or Interosseous Border (crista interossea). — The external or interosseous 
 border commences above by the union of two lines, which converge one from each 
 extremity of the lesser sigmoid cavity, enclosing between them a triangular space 
 for the attachment of part of the Supinator brevis. The external line is the 
 crista m. supinatoris. The interosseous border of the ulna terminates below at 
 the middle of the head of the ulna. Its two middle fourths are very prominent; 
 its lower fourth is smooth and rounded. This border gives attachment to the 
 interosseous membrane, and separates the anterior from the posterior surface. 
 
 Anterior or Palmar Surface (fades volaris) . — The anterior surface, much broader 
 above than below, is concave in the upper three-fourths of its extent, and affords 
 attachment to the Flexor profundus digitorum; its lower fourth, also concave, is 
 covered by the Pronator quadratus. The lower fourth is separated from the 
 remaining portion of the bone by a prominent ridge, directed obliquely from 
 above downward and inward; this ridge, the oblique or pronator ridge, marks the 
 extent of attachment of the Pronator quadratus. At the junction of the upper 
 with the middle third of the bone is the nutrient foramen (foramen nutricium). 
 It opens into the nutrient canal (canalis nutricius), which is directed obliquely 
 upward and inward (proximally) . 
 
 Posterior or Dorsal Surface (facies dorsalis) . — The posterior surface, directed back- 
 ward and outward, is broad and concave above, somewhat narrower and convex in 
 the middle of its course, narrow, smooth, and rounded below. It presents, above, an 
 oblique ridge, which runs from the posterior extremity of the lesser sigmoid cavity, 
 downward to the posterior border; the triangular surface above this ridge receives 
 the insertion of the Anconeus muscle, whilst the upper part of the ridge itself affords 
 attachment to the Supinator brevis. The surface of bone below this is subdivided 
 by a longitudinal ridge, sometimes called the perpendicular line, into two parts; 
 the internal part is smooth, and covered by the Extensor carpi ulnaris; the exter- 
 nal portion, wider and rougher, gives attachment from above downward to part 
 of the Supinator brevis, the Extensor ossis metacarpi pollicis, the Extensor longus 
 pollicis, and the Extensor indicis muscles. 
 
 Internal Surface (facies medialis). — The internal surface is broad and concave 
 above, narrow and convex below. It gives attachment by its upper three-fourths 
 
THE ULNA 
 
 189 
 
 to the Flexor profundus digitorura muscle: its lower fourth is subcutaneous. 
 The anterior and the inner surfaces constitute the flexor surface. 
 
 Lower Extremity. — The lower extremity of the ulna is of small size, and 
 excluded from the articulation of the wrist-joint. It presents for examination two 
 eminences, the outer and larger of which is a rounded, articular eminence, termed 
 the head of the ulna (capitulum ulnae), the inner, narrower and more projecting, 
 is a non-articular eminence, the styloid process (processiis styloideus) . The head- 
 presents an articular facet, part of which, of an oval or semilunar form, is 
 directed downward, and articulates with the upper surface of the interarticular 
 fibro-cartilage which separates it from the wrist-joint; the remaining portion, 
 directed outward, is narrow, convex, and received into the sigmoid cavity of the 
 radius. The peripheral margin of the portion of the head which articulates with 
 the ulna is called the articular circumference (circumferentia ariicularis). The 
 styloid process projects from the inner and back part of the bone, and descends 
 a little lower than the head, terminating in a rounded summit, which affords 
 attachment to the internal lateral ligament of the wrist. The head is separated 
 from the styloid process by a depression for the attachment of the triangular 
 interarticular fibro-cartilage; and behind, by a shallow groove for the passage of 
 the tendon of the Extensor carpi ulnaris. 
 
 Structure. — Similar to that of the other long bones. 
 
 Development. — By three centres : one for the shaft, one for the inferior extrem- 
 ity, and one for the olecranon (Fig. 135). Ossification commences near the 
 middle of the shaft about the eighth week, and 
 soon extends through the greater part of the bone. 
 At birth the ends are cartilaginous. About the 
 fourth year a separate osseous nucleus appears in 
 the middle of the head, which soon extends into the 
 styloid process. About the tenth year ossific matter 
 appears in the olecranon near its extremity, the chief 
 part of this process being formed from an extension 
 of the shaft of the bone into it. At about the six- 
 teenth year the upper epiphysis becomes joined, and 
 at about the twentieth year the lower one. 
 
 Articulations. — With the humerus and radius. 
 
 Attachment of Muscles. — To sixteen : to the ole- 
 cranon, the Triceps, Anconeus, and one head of the 
 Flexor carpi ulnaris. To the coronoid process, the 
 Brachialis anticus. Pronator radii teres, Flexor sub- 
 limis digitorum, and Flexor profundus digitorum; 
 generally also the Flexor longus pollicis. To the 
 shaft, the Flexor profundus digitorum, Pronator 
 quadratus. Flexor carpi ulnaris. Extensor carpi 
 ulnaris. Anconeus, Supinator brevis, Extensor ossis 
 metacarpi pollicis. Extensor longus pollicis, and 
 Extensor indicis. 
 
 Olecranon. 
 Appears aCr^s£^^-Jom.s shaft at 
 
 10th year. 
 
 16th year. 
 
 Appears at f 
 4th year. 
 
 Joins shaft at 
 20th year. 
 
 Inferior extremity. 
 Fig. 135. — Plan of the development 
 Surface Form.— The most prominent part of the ulna on "^ ^^^ ^l"**- ^^ ^^'^^ ''^''^'^^■ 
 the surface of the body is the olecranon process, which can 
 
 ahvays be felt at the back of the elbow-joint. When the forearm is flexed, the upper quadri- 
 lateral surface can be feU, directed backward; during extension it recedes into the olecranon 
 fossa, and the contracting fibres of the triceps prevent its being perceived. At the back of 
 the olecranon is the smooth, triangular, subcutaneous surface, which below is continuous 
 with the posterior border of the shaft of the bone, and felt in every position of the forearm. 
 During extension the upper border of the olecranon is slightly above the level of the internal 
 condyle, and the process itself is nearer to this condyle than the outer one. Running down 
 the back of the forearm, from the apex of the triangular surface which forms the posterior 
 
190 THE SKELETON 
 
 surface of the olecranon, is a prominent ridge of bone, the posterior border of the ulna. 
 This is to be felt throughout the entire length of the shaft of the bone, from the olecranon 
 above to the styloid process below. As it passes down the forearm it pursues a sinuous course 
 and inclines to the inner side, so that, though it is situated in the middle of the back of 
 the limb above, it is on the inner side of the wrist at its termination. It becomes rounded off 
 in its lower third, and may be traced below to the small, subcutaneous surface of the styloid 
 process. Internal to this border the lower fourth of the inner surface is to be felt. The styloid 
 process is to be felt as a prominent tubercle of bone, continuous above with the posterior sub- 
 cutaneous border of the ulna, and terminating below in a blunt apex, which lies a little internal 
 and behind, but on a level with, the wrist-joint. The styloid process is best felt when the hand 
 is in the same line as the bones of the forearm, and in a position midway between supination 
 and pronation. If the forearm is pronated while the finger is placed on the process, it will be 
 felt to recede, and another prominence of bone will appear just behind and above it. This 
 is the head of the ulna, which articulates with the lower end of the radius and the triangular 
 interarticular fibro-cartilage, and now projects between the tendons of the Extensor carpi ulnaris 
 and the Extensor minimi digiti muscles. 
 
 The Radius. 
 
 The radius {radius, a ray, or spoke of a wheel) is so called because it is the 
 rotary bone of the forearm. It is situated on the outer side of the forearm, lying 
 side by side with the ulna, which exceeds it in length and size (Figs. 133 and 
 134). Its upper end is small, and forms only a small part of the elbow-joint; 
 but its lower end is large, and forms the chief part of the wrist. It is one of the 
 long bones, prismatic in form, slightly curved longitudinally, and, like other 
 long bones, has a shaft and two extremities. 
 
 Upper Extremity. — ^The upper extremity presents a head, neck, and tuberosity. 
 
 The Head. — The head (capitulum radii) is of a cylindrical form, depressed on 
 its upper surface into a shallow cup (fovea capitidi radii), which articulates with 
 the capitellum or radial head of the humerus. In the recent state it is covered 
 with a layer of cartilage which is thinnest at its centre. Around the circumference 
 of the head is a smooth, articular surface (circumferentia articularis) , broad inter- 
 nally where it articulates with the lesser sigmoid cavity of the ulna; narrow in 
 the rest of its circumference, where it rotates within the orbicular ligament. It 
 is coated with cartilage in the recent state. The head is supported on a round, 
 smooth, and constricted portion of bone, called the neck (collum radii), which 
 presents, behind, a slight ridge, for the attachment of part of the Supinator brevis. 
 Beneath the neck, at the inner and front aspect of the bone, is a rough eminence, 
 the bicipital tuberosity (tuberositas radii). Its surface is divided into two parts by 
 a vertical line — a posterior, rough portion, for the insertion of the tendon of the 
 Biceps muscle; and an anterior, smooth portion, on which a bursa is interposed 
 between the tendon and the bone. • 
 
 The Shaft (corpus radii). — The shaft of the bone is prismoid in form, narrower 
 above than below, and slightly curved, so as to be convex outward. It presents 
 three surfaces, separated by three borders. 
 
 Anterior or Palmar Border (margo volaris) . — ^The anterior border extends from 
 the lower part of the tuberosity above to the anterior part of the base of the styloid 
 process below. It separates the anterior from the external surface. Its upper 
 third is very prominent; and from its oblique direction, downward and outward, 
 has received the name of the oblique line of the radius. It gives attachment exter- 
 nally to the Supinator brevis, internally to the Flexor longus pollicis, and between 
 these to the Flexor sublimis digitorum. The middle third of the anterior border 
 is indistinct and rounded. Its lower fourth is sharp, prominent, affords attach- 
 ment to the Pronator quadratus and to the posterior annular ligament of the wrist, 
 and terminates in a small tubercle at the base of the styloid process, into which 
 is inserted the tendon of the Supinator longus. 
 
THE RADIUS 191 
 
 Posterior or Dorsal Border (margo dorsalis). — The posterior border commences 
 above at the back part of the neck of the radius, and terminates below at the 
 posterior part of the base of the styloid process; it separates the posterior from 
 the external surface. It is indistinct above and below, but well marked in the 
 middle third of the bone. 
 
 Internal or Interosseous Border (crista interossea). — The internal or interosseous 
 border commences above at the back part of the tuberosity, where it is rounded 
 anti indistinct, becomes sharp and prominent as it descends, and at its lower part 
 divides into two ridges, which descend to the anterior and posterior margins of 
 the sigmoid cavity. This border separates the anterior from the posterior sur- 
 face, and has the interosseous membrane attached to it throughout the greater 
 part of its extent. 
 
 Anterior or Palmar or Flexor Surface (fades volaris). — ^The anterior surface is 
 concave for its upper three-fourths, and gives attachment to the Flexor longus 
 pollicis muscle; it is broad and flat for its lower fourth, and gives attachment to 
 the Pronator quadratus. A prominent ridge limits the attachment of the Pro- 
 nator quadratus below, and between this and the inferior border is a triangular 
 rough surface for the attachment of the anterior ligament of the wrist-joint. At 
 the junction of the upper and middle third of this surface is the nutrient foramen 
 (foramen nidricium) , the opening of the nutrient canal (canalis nutricius), which 
 is directed obliquely upward (proximally) . 
 
 Posterior or Dorsal or Extensor Surface (facies dorsalis). — ^The posterior surface 
 is rounded, convex, and smooth in the upper third of its extent, and covered by 
 the Supinator brevis muscle. Its middle third is broad, slightly concave, and gives 
 attachment to the Extensor ossis metacarpi pollicis above, the Extensor brevis pol- 
 licis below. Its lower third is broad, convex, and covered by the tendons of the 
 muscles, which subsequently run in the grooves on the lower end of the bone. 
 
 External Surface (facies lateralis) . — The external surface is rounded and convex 
 throughout its entire extent. Its upper third gives attachment to the Supinator 
 brevis muscle. About its centre is seen a rough ridge, for the insertion of the Pro- 
 nator radii teres muscle. Its lower part is narrow, and covered by the tendons 
 of the Extensor ossis metacarpi pollicis and Extensor brevis pollicis muscles. 
 
 Lower Extremity. — The lower extremity of the radius is large, of quadri- 
 lateral form, and provided with two articular surfaces — one at the extremity, for 
 articulation with the carpus, and one at the inner side of the bone, for articulation 
 with the ulna. The carpal articular surface (facies articularis carpea) is of tri- 
 angular form, concave, smooth, and divided by a slight antero-posterior ridge 
 into two parts. Of these, the external is of a triangular form, and articulates with 
 the scaphoid bone; the inner is quadrilateral and articulates with the semilunar 
 bone. The articular surface for the head of the ulna is called the sigmoid cavity 
 of the radius (incisura ulnaris); it is narrow, concave, smooth, and articulates 
 with the head of the ulna. The circumference of this end of the bone presents 
 three surfaces — an anterior, external, and posterior. The anterior surface, rough 
 and irregular, affords attachment to the anterior ligament of the wrist-joint. The 
 external surface is prolonged obliquely downward into a strong, conical projec- 
 tion, the styloid process (processus styloideus), which gives attachment by its base 
 to the tendon of the Supinator longus, and by its apex to the external lateral liga- 
 ment of the wrist-joint. The outer surface of this process is marked by a flat 
 groove, which runs obliquely downward and forward, and gives passage to the 
 tendons of the Extensor ossis metacarpi pollicis and the Extensor brevis pollicis. 
 The posterior surface is convex, affords attachment to the posterior ligament of 
 the wrist, and is marked by three grooves. Proceeding from without inward, the 
 first groove is broad but shallow, and subdivided into two by a slightly elevated 
 ridge: the outer of these two transmits the tendon of the Extensor carpi radialis 
 
192 
 
 THE SKELETON 
 
 Appears atj 
 5th year. 
 
 Unites with shaft 
 about puberty. 
 
 longior, the inner the tendon of the Extensor carpi radialis brevior. The second^ 
 which is near the centre of the bone, is a deep but narrow groove, bounded on its 
 outer side by a sharply-defined ridge; it is directed obHquely from above, down- 
 ward and outward, and transmits the tendon of the Extensor longus polHcis- 
 The third, lying most internally, is a broad groove, for the passage of the tendons 
 of the Extensor indicis and Extensor communis digitorum. 
 Structure. — Similar to that of the other long bones. 
 
 Development (Fig. 136). — By three centres: one for the shaft and one for each 
 extremity. That for the shaft makes its appearance near the centre of the bone, 
 
 about the eighth week of foetal life. About 
 Head. the end of the second year ossification com- 
 
 mences in the lower epiphysis, and about the 
 fifth year in the upper end At the age of 
 seventeen or eighteen the upper epiphysis be- 
 comes joined to the shaft, the lower epiphysis 
 becoming united about the twentieth year. 
 
 Articulation. — With four bones: the humerus, 
 ulna, scaphoid, and semilunar. 
 
 Attachment of Muscles. — To nine: to the 
 tuberosity, the Biceps, to the oblique ridge, the 
 Supinator brevis, Flexor subhmis digitorum, 
 and Flexor longus pollicis; to the shaft (its 
 anterior surface), the Flexor longus pollicis^ 
 and Pronator quadratus ; (its posterior surface) , 
 the Extensor ossis metacarpi pollicis and Exten- 
 sor brevis pollicis; (its outer surface), the Pro- 
 nator radii teres; and to the styloid process, 
 the Supinator longus. 
 
 Appears at^ 
 2d year. 
 
 Unites with shaft 
 ' about 20th year. 
 
 Lower extremity. 
 
 Fig. 136. — Plan of the development of the 
 radius. By three centres. 
 
 Surface Form.— Just below and a little in front of 
 the posterior surface of the external condyle a part of 
 the head of the radius may be felt, covered by the 
 orbicular and external lateral ligaments. There is in 
 this situation a little dimple in the skin, which is most 
 visible when the arm is extended; and which marks the 
 position of the head of the bone. If the finger is placed on this dimple and the forearm pro- 
 nated and supinated, the head of the bone will be distinctly perceived rotating in the lesser 
 sigmoid cavity. The upper half of the shaft of the radius cannot be felt, as it is surrounded by 
 the fleshy bellies of the muscles arising from the external condyle. The lower half of the shaft 
 can be readily examined, though covered by tendons and muscles and not strictly subcutaneous- 
 If traced downward, the shaft will be felt to terminate in a lozenge-shaped, convex surface 
 on the outer side of the base of the styloid process. This is the only subcutaneous part of the 
 bone, and from its lower extremity the apex of the styloid process will be felt bending inward 
 toward the wrist. About the middle of the posterior aspect of the lower extremity of the bone 
 is a well-marked ridge, best perceived when the hand is slightly flexed on the wrist. It forms 
 the outer boundary of the oblique groove on the posterior surface of the bone, through which 
 the tendon of the Extensor longus pollicis runs, and serves to keep that tendon in place. 
 
 Surgical Anatomy of the Radius and Ulna. — The two bones of the forearm are more often 
 broken together than is either the radius or ulna separately. It is therefore convenient to consider 
 fractures of both bones in the first instance, and subsequently to mention the principal fractures 
 which take place in each bone individually. These fractures may be produced by either direct 
 or indirect violence, though more commonly by direct violence. When indirect force is applied 
 to the forearm the radius generally alone gives way, though both bones may suffer. The 
 fracture from indirect force generally takes place somewhere about the middle of the bones; 
 fracture from direct violence may occur at any part, more often, however, in the lower half of 
 the bone. The fracture is usually transverse, but may be more or less oblique. A point of 
 interest in connection with these fractures is the tendency that there is for the two bones to unite 
 across the interosseous membrane; the limb should therefore be put up in a position midway 
 between supination and pronation, which is not only the most comfortable position, but also sep- 
 arates the bones most widely from each other, and therefore diminishes the risk of the bones 
 
THE CARPUS 193 
 
 becoming united across the interosseous membrane. The splints, anterior and posterior, which 
 are apphed in these cases should be rather wider than the limb, so as to prevent any lateral 
 pressure on the bones. In these cases there is a greater liability to gangrene from the pressure 
 of the splints than in other parts of the body. This is no doubt due principally to two causes: 
 (1) the flexion of the forearm compressing to a certain extent the brachial artery and retarding 
 the flow of blood to the limb; and (2) the superficial position of the two main arteries of the 
 forearm in a part of their course, and their liability to be compressed by the splints. The special 
 fractures of the ulna are — (1) Fracture of the olecranon. This may be caused by direct violence, 
 falls on the elbow, with the forearm flexed, or by muscular action by the sudden contraction of 
 the triceps, The most common place for the fracture to occur is at the constricted portion 
 where the olecranon joins the shaft of the bone, and the fracture may be either transverse or 
 oblique; but any part may be broken, even a thin shell may be torn off. Fractures from direct 
 violence are occasionally comminuted. The displacement is sometimes very slight, owing to the 
 fibrous structures around the process not being torn. (2) Fracture of the coronoid process some- 
 times occurs as a complication of dislocation backward of the bones of the forearm, but it is 
 doubtful if it ever occurs as an uncomplicated injury. (3) Fractures of the shaft of the ulna 
 may occur at any part, but usually takes place at the middle of the bone or a little below it. 
 They are almost always the result of direct violence. (4) The styloid process may be knocked 
 off by direct violence. Fractures of the radius consist of — (1) Fracture of the head of the bone; 
 this generally occurs in conjunction with some other lesion, but may occur as an uncomplicated 
 injury. (2) Fracture of the neck may also take place, but is generally complicated with other 
 injury (3) Fractures of the shaft of the radius are very common, and may take place at any 
 part of the bone. They may take place from either direct or indirect violence. In fractures of the 
 upper third of the shaft of the bone, that is to say, above the insertion of the Pronator radii teres, 
 the displacement is very great. The upper fragment is strongly supinated by the Biceps and Supi- 
 nator brevis, and flexed by the Biceps, while the lower fragment is pronated and drawn toward 
 the ulna by the two pronators. If such a fracture is put up in the ordinary position, midway 
 between supination and pronation, the fracture will unite with the upper fragment in a position 
 of supination, and the lower one in the mid-position, and thus considerable impairment of the 
 movements of the hand will result. The limb should be put up with the forearm supinated. (4) 
 The most important fracture of the radius is that of the lower end {Colles's fracture). The 
 fracture is transverse, and generally takes place about an inch from the lower extremity. It is 
 caused by falls on the palm of the hand, and is an injury of advanced life, occurring more fre- 
 (|uently in the female than the male. In consequence of the manner in which the fracture is 
 caused, the upper fragment becomes driven into the lower, and impaction is the result; or else 
 the lower fragment becomes split up into two or more pieces, so that no fixation occurs. Sepa- 
 ration of the lower epiphysis of the radius may take place in the young. This injury and Colles's 
 fracture may be distinguished from other injuries in this neighborhood — especially dislocation, 
 with which it is liable to be confounded — by observing the relative positions of the styloid 
 processes of the ulna and radius. In the natural condition of parts, with the arm hanging by the 
 side, the styloid process of the radius is on a lower level than that of the ulna; that is to say, 
 nearer the ground. After fracture or separation of the epiphysis this process is on the same or 
 a higher level than that of the ulna, whereas it would be unaltered in position in dislocation. 
 
 THE HAND. 
 
 The skeleton of the hand is subdivided into three segments — the carpus or wrist 
 ones ; the metacarpus or bones of the palm ; and the phalanges or bones of the digits . 
 
 The Carpus (Ossa Carpi) (Figs. 137, 138). 
 
 The bones of the carpus {xapiioQ, the wrist), eight in number, are arranged 
 in two rows. Those of the upper row, enumerated from the radial to the ulnar 
 side, are the scaphoid, semilunar, cuneiform, and pisiform; those of the lower 
 row, enumerated in the same order, are the trapezium, trapezoid, os magnum, 
 and unciform. 
 
 Common Characters of the Carpal Bones. — Each bone (excepting the pisiform) 
 presents six surfaces. Of these the anterior, 'palmar, or volar, and the posterior or 
 dorsal are rough for ligamentous attachment, the dorsal surface being the broader, 
 except in the scaphoicl and semilunar. The superior or proximal and inferior or 
 distal are articular, the superior generally convex, the inferior concave; and the 
 
 13 
 
194 
 
 THE SKELETON 
 
 internal and external are also articular when in contact with contiguous bones, 
 otherwise rough and tubercular. The structure in all is similar, consisting of 
 
 ^i^^^^&i^\ 
 
 I 
 
 EXTKNSOR CARPI 
 FACIALIS LONQIOR. 
 
 EXTENSOR CARPI 
 RAOIALIS BREVIOR. 
 
 Metacarpus, \ 
 
 EXTENSOR BREVIS 
 POLtlCIS 
 
 EXTENSOR LONQUS 
 POLLICIS 
 
 EXTENSOR D1QITORUM 
 
 COMMUNIS and 
 
 EXTENSOR INDICIS 
 
 Fig. 137. — Bones of the left hand. Dorsal surface. 
 
 cancellous tissue enclosed in a layer of compact bone. Each bone is also develope( 
 from a single centre of ossification. 
 
THE CARPUS 
 
 195 
 
 Bones of the Upper Row. 
 
 Scaphoid or Navicular Bone {os naviculare manus, the boat-like hone) (Fig, 
 139). — The scaphoid ((Txd<fT^, a boat, £cdo(;, like) is the largest bone of the first 
 
 FLEXOR CARPI ULNARIS. 
 
 FLEXOR BREVIS MINIMI DIQITI. 
 
 FLEXOR 0SS1S METACARPI. 
 MINIMI DIQITI. 
 
 Groove for tendon of 
 
 FLEXOR CARPI RADIALIS. 
 
 FLEXOR OSSIS 
 METACARPI POLLICIS. 
 FLEXOR BREVIS POLL. 
 
 EXTEN. OS. METACARP. POLL. 
 
 EXTENSOR OSSIS 
 METACARPI POLLICIS. 
 
 Metacarpus. 
 
 FLEX. BREVIS 
 
 and 
 
 ABDUCTOR 
 MINIMI DIQTI. 
 
 FLEXOR 
 
 IQITORUM 
 PROFUNDUS. 
 
 Fig. 138. — Bones of the left hand. Palmar .surface. 
 
 row. It has received its name from its fancied resemblance to a boat, being 
 broad at one end and narrowed like a prow at the opposite. It is situated at 
 
196 
 
 THE SKELETON 
 
 the upper and outer part of the carpus, its long axis being from above down- 
 ward, outward, and forward. 
 
 Surfaces. — The superior surface is convex, smooth, of triangular shape, and 
 articulates with the lower end of the radius. The inferior surface, directed 
 
 For radius. 
 
 Tuberosity 
 
 For trapezium. 
 
 For semilunar. 
 
 For OS magntim. 
 For trapezoid. 
 
 Fig. 139. — The left scaphoid. 
 
 downward, outward, and backward, is smooth, convex, also triangular, and' 
 divided by a slight ridge into two parts, the external of which articulates with 
 the trapezium, the inner with the trapezoid. The posterior or dorsal surface 
 presents a narrow, rough groove which runs the entire length of the bone andj 
 serves for the attachment of ligaments. The anterior or palmar surface is concave 
 above, and elevated at its lower and outer part into a prominent rounded tuber- 
 osity {tuberculum ossis navicularis) , which projects forward from the front of the] 
 carpus and gives attachment to the anterior annular ligament of the wrist and 
 sometimes a few fibres of the Abductor pollicis. The external surface is rough 
 and narrow, and gives attachment to the external lateral ligament of the wrist. 
 The internal surface presents two articular facets: of these, the superior or smaller] 
 one is flattened, of semilunar form, and articulates with the semilunar; the inferior 
 or larger is concave, forming, with the semilunar bone, a concavity for the head i 
 of the OS magnum. 
 
 To ascertain to which side the bone belongs, hold it with the superior or radial 
 convex, articular surface upward, and the posterior surface — i. e., the narrow,: 
 non-articular, grooved surface — toward you. The tubercle on the outer surface] 
 points to the side to which the bone belongs.^ 
 
 Articulations. — With five bones: the radius above, trapezium and trapezoid] 
 below, OS magnum and semilunar internally. 
 
 Attachment of Muscles. — Occasionally a few fibres of the Abductor pollicis. 
 
 Semilunar (os lunatum) (Fig. 140). — The semilunar {semi, half; luna, moon) 
 bone may be distinguished by its deep concavity and crescentic outline. It isl 
 
 For cuneiform. 
 
 For radius. 
 
 For unciform. 
 
 For OS magnum 
 Fig. 140. — The left semilunar, 
 
 For 
 scaphoid. 
 
 situated in the centre of the upper row of the carpus, between the scaphoid and 
 cuneiform. 
 
 Surfaces. — The superior surface, convex, smooth, and bounded by four edges, 
 articulates with the radius. The inferior surface is deeply concave, and of greater I 
 
 ' In these directions each bone is supposed to be placed in its natural position — that is, such a position as it 
 would occupy when the arm is hanging by the side, the forearm in a position of supination, the thumb being 
 directed outward,' and the palm of the hand looking forward. 
 
THE CABPUS 197 
 
 extent from before backward than transversely : it articulates with the head of the 
 OS magnum and by a long, narrow facet (separated by a ridge from the general 
 surface) with the unciform bone. The anterior or palmar and 'posterior or dorsal 
 surfaces are rough, for the attachment of iigaments, the former being the broader 
 and of a somewhat rounded form. The external surface presents a narrow, flat- 
 tened, semilunar facet for articulation with the scaphoid. The internal surface 
 is marked by a smooth, quadrilateral facet, for articulation with the cuneiform. 
 
 Hold it with the convex articular surface for the radius upward, and the nar- 
 rowest non-articular surface toward you. The semilunar facet for the scaphoid 
 will be on the side to which the bone belongs. 
 
 Articulations, — With five bones: the radius above, os magnum and unciform 
 below, scaphoid and cuneiform on either side. 
 
 Cuneiform (as triquetrum, the wedge-shaped bone) (Fig. 141). — ^The cuneiform 
 (cuneus, a wedge; forma, likeness) may be distinguished by its pyramidal 
 shape, and by its having an oval, isolated facet for articu- 
 lation with the pisiform bone. It is situated at the upper For semilunar. 
 and inner side of the carpus. ForpisiM 
 
 Surfaces. — The superior surface presents an internal, rough, 
 non-articular portion, and an external or articular portion, 
 which is convex, smooth, and articulates with the triangular 
 interarticular fibro-cartilage of the wrist. The inferior sur- -^*"" v,nciform. 
 
 face, directed outward, is concave, sinuously curved, and ^'g- i^i— T^kftcunei- 
 smooth for articulation with the unciform. The posterior 
 or dorsal surface is rough, for the attachment of ligaments. The anterior or 
 palmar surface presents, at its inner side, an oval facet, for articulation with 
 the pisiform; and is rough externally, for ligamentous attachment. The exter- 
 nal surface, the base of the pyramid, is marked by a flat, quadrilateral, smooth 
 facet, for articulation with the semilunar. The internal surface, the summit of 
 the pyramid, is pointed and roughened, for the attachment of the internal lateral 
 ligament of the wrist. 
 
 Hold the bone with the surface supporting the pisiform facet away from you, 
 and the concavo-convex surface for the unciform downward. The base of the 
 wedge (i. e., the broad end of the bone) will be on the side to which it belongs. 
 
 Articulations. — With three bones: the semilunar externally, the pisiform in 
 front, the unciform below; and with the triangular, interarticular fibro-cartilage 
 which separates it from the lower end of the ulna. 
 
 Pisiform (os pisiforme) (Fig. 142). — The pisiform (pisum, a pea; forma, like- 
 ness) may be known by its small size and by its presenting a single articular 
 facet. It is situated on a plane anterior to the other bones of 
 
 For . . . . 
 
 cuneiform. the carpus; it is spheroidal in form, with its long diameter 
 
 # directed vertically. 
 
 Surfaces. — Its posterior surface is a smooth, oval facet, for 
 articulation with the cuneiform. This facet approaches the 
 superior, but not the inferior border of the bone. The anterior 
 '° pisifOTm.^ ^* or palmar surface is rounded and rough, and gives attachment 
 to the anterior annular ligament and to the Flexor carpi 
 ulnaris and Abductor minimi digiti muscles. The outer and inner surfaces are 
 also rough, the former being concave, the latter usually convex. 
 
 Hold the bone with the posterior surface — that which presents the articular 
 facet — toward you, in such a manner that the faceted portion of the surface is 
 uppermost. The outer, concave surface will point to the side to which it belongs. 
 Articulations. — With one bone, the cuneiform. 
 
 Attachment of Muscles. — To two: the Flexor carpi ulnaris and Abductor 
 minimi digiti; and to the anterior annular ligament. 
 
198 
 
 THE SKELETON 
 
 Bones of the Lower Row. 
 
 Trapezium {os multangulmn majus) (Fig. 143). — The trapezium (zf)dz£^a, a 
 table) is of very irregular form. It may be distinguished by a deep groove, for 
 
 Groove. 
 
 For scaphoid. 
 
 For Sd 
 metacarpal. 
 
 Ridge. 
 
 For 1st metacarpal. 
 
 Fig. 143. — The left trapezium. 
 
 For trapezoid. 
 
 For 2d metacarpal. 
 
 the tendon of the Flexor carpi radiahs muscle. It is situated at the external and 
 inferior part of the carpus between the scaphoid and first metacarpal bone. 
 
 Surfaces. — The superior surface, concave and smooth, is directed upward and 
 inward, and articulates with the scaphoid. The inferior surface, directed down- 
 ward and inward, is oval, concave from side to side, convex from before backward, 
 so as to form a saddle-shaped surface, for articulation with the base of the first 
 metacarpal bone. The anterior or palmar surface is narrow and rough. At its 
 upper part is a deep groove running from above obliquely downward and inward ; 
 it transmits the tendon of the Flexor carpi radialis, and is bounded externally 
 by a prominent ridge, the oblique ridge of the trapezium (tuherculum ossis mul- 
 tanguli majoris). This surface gives attachment to the Abductor pollicis. Flexor 
 ossis metacarpi pollicis, and Flexor brevis pollicis muscles, and the anterior 
 annular ligament. The posterior or dorsal surface is rough. The external sur- 
 face is also broad and rough, for the attachment of ligaments. The internal 
 surface presents two articular facets: the upper one, large and concave, articu- 
 lates with the trapezoid; the lower one, small and oval, with the base of the 
 second metacarpal bone. 
 
 Hold the bone with the saddle-shaped surface downward and- the grooved 
 surface away from you. The prominent, rough, non-articular surface points to 
 the side to which the bone belongs. 
 
 Articulations. — With four bones: the scaphoid above, the trapezoid and second 
 metacarpal bones internally, the first metacarpal below. 
 
 Attachment of Muscles. — Abductor pollicis, Flexor ossis metacarpi pollicis, and 
 part of the Flexor brevis pollicis. 
 
 Trapezoid (os multangulum minus) (Fig. 144). — The trapezoid is the smallest 
 bone in the second row. It may be known by its wedge-shaped form, the broad 
 
 For scaphoid. 
 
 Anterior surface. 
 
 For trapezium. 
 
 Post, surface 
 
 Fig. 144. 
 
 OS magnum. 
 
 For 2d metacarpal. 
 The left trapezoid. 
 
 end of the wedge forming the dorsal, the narrow end the palmar, surface, and by 
 its having four articular surfaces touching each other and separated by sharp 
 edges. 
 
 Surfaces.^The superior surface, quadrilateral in form, smooth, and slightly con- 
 cave, articulates with the scaphoid. The inferior surface articulates with the upper 
 
THE CARPUS 
 
 199 
 
 end of the second metacarpal bone ; it is convex from side to side, concave from before 
 backward, and subdivided by an elevated ridge into two unequal lateral facets. 
 The posterior or dorsal and anterior or palmar surfaces are rough, for the attach- 
 ment of ligaments, the former being the larger of the two. The external surface, 
 convex and smooth, articulates with the trapezium. The internal surface is con- 
 cave and smooth in front, for articulation with the os magnum; rough behind, 
 for the attachment of an interosseous ligament. 
 
 Hold the bone with the larger, non-articular surface toward you, and the 
 smooth, quadrilateral articular surface upward. The convex articular surface 
 will point to the side to which the bone belongs.^ 
 
 Articulations. — ^With four bones: the scaphoid above, second metacarpal bone 
 below, trapezium externally, os magnum internally. 
 
 Os Magnum (os capitatum) (Fig. 145). — The os magnum is the largest bone 
 of the carpus, and occupies the centre of the wrist. It presents, above, a rounded 
 
 For semilunar. 
 
 For scaphoid. 
 
 For 
 trapezoid. 
 
 For 2d 
 metacarpal. 
 
 For semUunar. 
 
 For unciform. 
 
 For 4th 
 metacarpal. 
 
 For 3d For 4th metacarpal, 
 metacarpal. 
 
 Fig. 145. — The left os magnum 
 
 Ant. surface. 
 
 portion or head, which is received into the concavity formed by the scaphoid and 
 semilunar bones; a constricted portion or neck; and, below, the body. 
 
 Surfaces. — The superior surface is rounded, smooth, and articulates with the semi- 
 lunar. The inferior surface is divided by two ridges into three facets for articulation 
 with the second, third, and fourth metacarpal bones, that for the third (the middle 
 facet) being the largest of the three. The posterior or dorsal surface is broad and 
 rough; the anterior or palmar, narrow, rounded, and also rough, for the attachment 
 of ligaments and a part of the Adductor obliquus pollicis. The external surface 
 articulates with the trapezoid by a small facet at its anterior inferior angle, behind 
 which is a rough depression for the attachment of an interosseous ligament. 
 Above this is a deep and rough groove, which forms part of the neck and serves , 
 for the attachment of ligaments, bounded superiorly by a smooth, convex surface, 
 for articulation with the scaphoid. The internal surface articulates with the unci- 
 form by a smooth, concave, oblong facet which occupies its posterior and superior 
 parts, and is rough in front, for the attachment of an interosseous ligament. 
 
 Hold the bone with the broader, non-articular surface toward you, and the 
 head upward. The small, articular facet at the anterior inferior angle of the 
 external surface will point to the side to which the bone belongs. 
 
 Articulations. — With seven bones: the scaphoid and semilunar above; the 
 second, third, and fourth metacarpal below; the trapezoid on the radial side; and 
 the unciform on the ulnar side. 
 
 Attachment of Muscles. — Part of the Adductor obliquus pollicis. 
 
 Unciform (os hamatum) (Fig. 146). — ^The unciform or hook bone (uncus, a hook; 
 forma, likeness) may be readily distinguished by its wedge-shaped form and the 
 hook-like process that projects from its palmar surface. It is situated at the inner 
 
 ' Occa.'iionally in a badly marked bone there is some difficulty in ascertaining to which side the bone belongs; 
 the following method will sometimes be found useful : Hold the bone with its broader, non-articular surface 
 upward, so that its sloping border is directed toward you. The border will slope to the side to which, the bone 
 belongs. 
 
200 
 
 THE SKELETON 
 
 and lower angle of the carpus, with its base downward, resting on the two inner 
 metacarpal bones, and its apex directed upward and outward. 
 
 Surfaces. — The superior surface, the apex of the wedge, is narrow, convex, 
 smooth, and articulates with the semilunar. The inferior surface articulates with 
 
 For semilunar. 
 
 For cuneiform. 
 
 For OS magnum. 
 
 For fourth meta 
 tarsal. 
 
 Unciform process. 
 
 fifth 
 metatarsal. 
 
 Fig. 146. — The left unciform. 
 
 the fourth and fifth metacarpal bones, the concave surface for each being sepa- 
 rated by a ridge which runs from before backward. The posterior or dorsal\ 
 surface is triangular and rough, for ligamentous attachment. The anterior orj 
 palmar surface presents, at its lower and inner side, a curved, hook-like pro- 
 cess of bone, the unciform process (hamulus ossis hamati), directed from the] 
 palmar surface forward and outward. It gives attachment by its apex to thej 
 annular ligament and Flexor carpi ulnaris; by its inner surface to the Flexor brevis 
 minimi digiti and the Opponens minimi digiti; and is grooved on its outer] 
 side, for the passage of the Flexor tendons into the palm of the hand. This isj 
 one of the four eminences on the front of the carpus to which the anterior 
 annular ligament is attached, the others being the pisiform internally, the oblique} 
 ridge of the trapezium and the tuberosity of the scaphoid externally. The internall 
 surface articulates with the cuneiform by an oblong facet cut obliquely from above,} 
 downward and inward. The external surface articulates with the os magnum byj 
 its upper and posterior part, the remaining portion being rough, for the attach- 
 ment of ligaments. 
 
 Hold the bone with the hooked process away from you, and the articular sur- 
 face, divided into two parts, for the metacarpal bones, downward The concavity! 
 of the process will be on the side to which the bone belongs. 
 
 Articulations. — -With five bones: the semilunar above, the fourth and fiftl 
 metacarpal below, the cuneiform internally, the os magnvim externally. 
 
 Attachment of Muscles. — To three: the Flexor brevis minimi digiti, the Opponens 
 minimi digiti, the Flexor carpi ulnaris. 
 
 The Metacarpus (Ossa Metacarpalia) (Figs. 137, 138). 
 
 The metacarpal bones are five in number, and they are numbered from 1 to-l 
 5 inclusive, the first being the metacarpal bone of the thumb, the fifth the 
 metacarpal bone of the index finger. They are long, cylindrical bones, pre- 
 senting for examination a shaft and two extremities. 
 
 Common Characters of the Metacarpal Bones. The Shaft (corpus) .—The\ 
 shaft is prismoid in form and curved longitudinally, so as to be convex in the] 
 longitudinal direction behind, concave in front. It presents three surfaces; 
 two lateral and one posterior. The two lateral surfaces constitute the palmar or) 
 volar surface. The lateral surfaces are concave, for the attachment of the Inter-j 
 ossei muscles, and separated from one another by a prominent anterior ridge. [ 
 The posterior or dorsal surface presents in its distal half a smooth, triangular, flat-j 
 tened area which is covered, in the recent state, by the tendons of the Extensor 
 muscles. This triangular surface is bounded by two lines, which commence inj 
 
THE METACABPUS 
 
 201 
 
 small tubercles situated on the dorsal aspect on either side of the digital extremity, 
 and, running backward, converge to meet together a little behind the centre of 
 the bone and form a ridge which runs along the rest of the dorsal surface to the 
 carpal extremity. This ridge separates two lateral, sloping surfaces for the 
 attachment of the Dorsal interossei muscles/ To the tubercles on the digital 
 extremities are attached the lateral ligaments of the metacarpo-phalangeal joints. 
 On the palmar surface of each metacarpal bone is a nutrient foramen (foramen 
 nidricium) , which opens into a nutrient canal {canalis nutricius). In the thumb 
 metacarpal the direction of this foramen is toward the periphery (distally). In 
 each of the other metacarpals it is from the periphery (proximally). 
 
 Carpal or Proximal Extremity or Base (basis) . — The carpal extremity, or base, 
 is of a cuboidal form, and broader behind than in front; it articulates above 
 with the carpus, and on each side with the adjoining metacarpal bones ; its dorsal 
 and palmar surfaces are rough, for the attachment of tendons and ligaments. 
 
 Digital or Distal Extremity or Head (capitulum). — The digital extremity, or head, 
 presents an oblong surface, markedly convex from before backward, less so from 
 side to side, and flattened laterally; it articulates with the proximal phalanx; it is 
 broader and extends farther forward on the palmar than on the dorsal aspect. It 
 is longer in the antero-posterior than in the transverse diameter. On either side of 
 the head is a tubercle for the attachment of the lateral ligament of the metacarpo- 
 phalangeal joint. The posterior surface, broad and flat, supports the Extensor 
 tendons; the anterior surface is grooved in the middle line for the passage of the 
 Flexor tendons, and marked on each side by an articular eminence continuous with 
 the terminal articular surface. The metacarpal spaces (spatia interossea metacarpi) 
 are the intervals between the metacarpal bones. They are occupied by the 
 Interossei muscles. The broadest space is between the metacarpal bones of the 
 thumb and index finger. 
 
 Peculiar Characters of the Metacarpal Bones. — The Metacarpal Bone of the 
 Thumb (os metacarpale I) (Fig. 147) is shorter and wider than the rest, diverges to a 
 greater degree from the carpus, and its palmar sur- 
 face is directed inward toward the palm. The shaft 
 is flattened and broad on its dorsal aspect, and 
 does not present the ridge which is found on the 
 other metacarpal bones ; it is concave from above 
 downward, on its palmar surface. The carpal 
 extremity, or base, presents a concavo-convex sur- 
 face, for articulation with the trapezium; it has 
 no lateral facets, but presents externally a tubercle 
 for the insertion of the Extensor ossis metacarpi 
 pollicis. The digital extremity is less convex than 
 that of the other metacarpal bones, broader from 
 side to side than from before backward. It pre- 
 sents on its palmar aspect two distinct articular 
 eminences for the two sesamoid bones in the ten- 
 dons of the Flexor brevis pollicis, the outer one 
 being the larger of the two. 
 
 The side to which this bone belongs may be known by holding it in the position 
 it occupies in the hand, with the carpal extremity upward and the dorsal surface 
 backward; the tubercle for the Extensor ossis metacarpi pollicis will point to the 
 side to which it belongs. 
 
 Attachment of Muscles. — To four: the Flexor ossis metacarpi pollicis, the Extensor 
 ossis metacarpi pollicis, the Flexor brevis pollicis, and the First dorsal interosseous. 
 
 Tubercle. 
 For trapezium 
 
 For trnpezium. 
 
 Fig. 147. — The fir.st metacarpal. (Left.) 
 
 ' By these .sloping surfaces the metacarpal bones of the hand may be at once differentiated from the meta- 
 tarsal bone of the foot. 
 
202 
 
 THE SKELETON 
 
 The Metacarpal Bone of the Index Finger {os metacarpale II) (Fig. 148) is the 
 longest and its base the largest of the other four. Its carpal extremity is prolonged 
 upward and inward, forming a prominent ridge. The dorsal and palmar surfaces 
 of this extremity are rough, for the attachment of tendons and ligaments. It pre- 
 sents four articular facets : three on the upper aspect of the base : the middle one of 
 the three is the largest, concave from side to side, convex from before backward, for 
 articulation with the trapezoid; the external one is a small, flat, oval facet, for 
 articulation with the trapezium ; the internal one on the summit of the ridge is long 
 and narrow, for articulation with the os magnum. The fourth facet is on the inner 
 or ulnar side of the extremity of the bone, and is for articulation with the third 
 metacarpal bone. 
 
 The side to which this bone belongs is indicated by the absence of the lateral 
 facet on the outer (radial) side of its base, so that if the bone is placed with the 
 base toward the student and the palmar surface upward, the side on which there 
 is no lateral facet will be that to which it belongs. 
 
 ■t^For trapezium. 
 For trapezoid. 
 
 1 For third metacarpal. 
 For OS magnum. 
 
 Fig. 148. — The second metacarpal. (Left.) 
 
 Styloid For second \ For fourth 
 
 process, metacarpal. \ metacarpal. 
 
 For OS magnum. 
 
 Fig. 149. — The third metacarpal. (Left.) 
 
 Attachment of Muscles. — To six: Flexor carpi radialis, Extensor carpi radialis 
 longior, Adductor obliquus pollicis. First and Second dorsal interosseous, and 
 First palmar interosseous. 
 
 The Metacarpal Bone of the Middle Finger (os metacarpale III) (Fig. 149) is a 
 little smaller than the preceding: it presents a pyramidal eminence, the styloid 
 process (processus styloideus) , on the radial side of its base (dorsal aspect), which 
 extends upward behind the os magnum; immediately below this, on the dorsal 
 aspect, is a rough surface for the attachment of the Extensor carpi radialis brevior. 
 The carpal, articular facet is concave behind, flat in front, and articulates with the 
 OS magnum. On the radial side is a smooth, concave facet, for articulation with 
 the second metacarpal bone, and on the ulnar side two small, oval facets, for articu- 
 lation with the fourth metacarpal. 
 
 The side to which this bone belongs is easily recognized by the styloid process 
 on the radial side of its base. With the palmar surface uppermost and the base 
 toward the student, this process points toward the side to which the bone belongs. 
 
THE METACARPUS 
 
 203 
 
 Attachment of Muscles. — To six: Extensor carpi radialis brevior, Flexor carpi 
 radialis, Adductor transversus pollicis, Adductor obliquus pollicis, and Second and 
 Third dorsal interosseous. 
 
 The Metacarpal Bone of the Ring Finger {os metacarpale IV) (Fig. 150) is shorter 
 and smaller than the preceding, and its base small and quadrilateral; the carpal 
 surface of the base presenting two facets, a large one externally, for articulation 
 with the unciform, and a small one internally, for the os magnum. On the radial 
 side are two oval facets, for articulation with the third metacarpal bone; and on 
 the ulnar side a single concave facet, for the fifth metacarpal. 
 
 If this bone is placed with the base toward the student and the palmar surface 
 upward, the radial side of the base, which has two facets for articulation with the 
 third metacarpal bone, will be on the side to which it belongs. If, as sometimes 
 happens in badly marked bones, one of these facets is indistinguishable, the side 
 may be known by selecting the surface on which the larger articular facet is present. 
 This facet is for the fifth metacarpal bone, and would therefore be situated on the 
 ulnar side — that is, the one to which the bone does not belong. 
 
 Fig. 150. 
 
 For fift h metor 
 For OS I carpal 
 
 magnum. For unciform. 
 
 — The fourth metacarpal. (Left.) 
 
 For cuneiform. 
 
 For fourth 
 metacarpal. 
 Fig. 151. — The fifth metacarpal. 
 
 (Left.) 
 
 Attachment of Muscles. — ^To three: the Third and Fourth dorsal and Second 
 pahnar intercsseous. 
 
 The Metacarpal Bone of the Little Finger (os metacarpale V) (Fig. 151) presents on 
 its base one facet, which is concavo-convex, and which articulates with the unciform 
 bone, and one lateral, articular facet, which articulates with the fourth metacarpal 
 bone. On its ulnar side is a prominent tubercle, for the insertion of the tendon of 
 the Extensor carpi ulnaris. The dorsal surface of the shaft is marked by an oblique 
 ridge which extends from near the uhiar side of the upper extremity to the radial 
 side of the lower. The outer division of this surface serves for the attachment of 
 the Fourth dorsal interosseous muscle; the inner division is smooth and covered 
 by the Extensor tendons of the little finger. 
 
 If this bone is placed with its base toward the student and its palmar surface 
 upward, the side of the head which has a lateral facet will be that to which the 
 bone belongs. 
 
 Attachment of Muscles. — To five: the Extensor carpi ulnaris. Flexor carpi 
 ulnaris, Flexor ossis metacarpi minimi digiti, Fourth dorsal, and Third palmar 
 interosseous. 
 
204 THE SKELETON 
 
 Articulations. — Besides the phalangeal articulations, the first metacarpal bone 
 articulates with the trapezium; the second with the trapezium, trapezoid, os 
 magnum, and third metacarpal bones; the third with the os magnum and second 
 and fourth metacarpal bones; the fourth with the os magnum, unciform, and 
 third and fifth metacarpal bones; and the fifth with the unciform and fourthj 
 metacarpal. 
 
 The first has no lateral facets on its carpal extremity; the second has no lateral] 
 facet on its radial side, but one on its ulnar side; the third has one on its radial! 
 and two on its ulnar side; the fourth has two on its radial and one on its ulnarj 
 side; and the fifth has only one on its radial side. 
 
 The Phalanges of the Hand (Phalanges Digitorum Manus). 
 
 The phalanges (internodia) are the bones of the fingers; they are fourteen ir 
 number, three for each finger, and two for the thumb. In numbering them the 
 proximal bone is designated as the first phalanx (phalanx I) . They are long bones J 
 and present for examination a shaft and two extremities. The shaft (corpus 
 phalangis) tapers from above downward, is convex posteriorly, concave in front 
 from above downward, flat from side to side, and marked laterally by rougl 
 ridges, which give attachment to the fibrous sheaths of the Flexor tendons, 
 nutrient foramen on the palmar surface leads into a nutrient canal which runs 
 toward the periphery (distalward) . The metacarpal extremity or base (hasiA 
 phalangis) of each phalanx in the first row presents an oval, concave, articular 
 surface, broader from side to side than from before backward; and the samt 
 extremity in the other two rows, a double concavity, separated l)y a longitudinal] 
 median ridge, extending from before backward. The distal extremity of the first 
 phalanx of the thumb and of the first and second phalanx of each of the fingers is 
 smaller than the base, and terminates in two small, lateral condyles, separatee 
 by a slight groove (trochlea phalangis) ; the articular surface being prolonged far- 
 ther forward on the palmar than on the dorsal surface, especially in the first row.] 
 
 The Ungual Phalanges (distal) are convex on their dorsal, flat on their palmar^ 
 surfaces; they are recognized by their small size and by a roughened, elevatec 
 surface of a horseshoe form on the palmar aspect of their ungual extremity 
 (tuberositas unguicularis) , which serves to support the sensitive pulp of the finger.] 
 
 Articulations. — The first row, with the metacarpal bones and the second row of 
 phalanges; the second row, with the first and third; the third, with the second row.] 
 
 Attachment of Muscles. — To the base of the first phalanx of the thumb, five 
 muscles: the Extensor brevis polHcis, Flexor brevis pollicis. Abductor polHcis,] 
 Adductor transversus and Obliquus pollicis. To the second phalanx, two : the 
 Flexor longus pollicis and the Extensor longus pollicis. To the base of the first 
 phalanx of the index finger, the First dorsal and the First palmar interosseous; tc 
 that of the middle finger, the Second and Third dorsal interosseous; to that of 
 the ring finger, the Fourth dorsal and the Second palmar interosseous ; and to that 
 of the little finger, the Third palmar interosseous, the Flexor brevis minimi digiti,] 
 and Abductor minimi digiti. To the second phalanges, the Extensor sublimis digi- 
 torum. Extensor communis digitorum, and, in addition, the Extensor indicis tc 
 the index finger, the Extensor minimi digiti to the little finger. To the third] 
 phalanges, the Flexor profundus digitorum and Extensor communis digitorum. 
 
 Surface Form. — On the front of the wrist are two subcutaneous eminences, one on the 
 radial side, the larger and flatter, due to the tuberosity of the scaphoid and the ridge on the 
 trapezium; the other, on the ulnar side, caused by the pisiform bone. The tubercle of the 
 scaphoid is to be felt just below and in front of the apex of the styloid process of the radius. It 
 is best perceived by extending the hand on the forearm. Immediately below is to be felt 
 another prominence, better marked than the tubercle; this is the ridge on the trapezium whichj 
 gives attachment to some of the short muscles of the thumb. On the inner side of the front of 
 
DEVELOPMENT OF THE BONES OF THE HAND 205 
 
 the wrist the pisiform bone is to be felt, forming a small but prominent projection in this situa- 
 tion. It is some distance below the styloid process of the ulna, and may be said to be just below 
 the level of the styloid process of the radius. The rest of the front of the carpus is covered by 
 tendons and the annular ligament, and entirely concealed, with the exception of the hooked 
 process of the unciform, which can only be made out with difficulty. The back of the carpus is 
 convex and covered by the Extensor tendons, so that none of the posterior surfaces of the bones 
 are to be felt, with the exception of the cuneiform on the inner side. Below the carpus the 
 dorsal surfaces of the metacarpal bones, except the fifth, are covered by tendons, and are scarcely 
 visible except in very thin hands. The dorsal surface of the fifth is, however, subcutaneous 
 throughout almost its whole length, and is plainly to be perceived and felt. In addition to this, 
 slightly external to the middle line of the hand, is a prominence, frequently well marked, but 
 occasionally indistinct, formed by the base of the metacarpal of the middle finger. The heads of 
 the metacarpal bones are plainly to be felt and seen, rounded in contour and standing out in bold 
 relief under the skin, when the fist is clenched. It should be borne in mind that when the fin- 
 gers are flexed on the hand, the articular surfaces of the first phalanges glide off the heads of the 
 metacarpal bones on to their anterior surfaces, so that the head of these bones form the prom- 
 inence of the knuckles and receive the force of any blow which may be given. The head of the 
 third metacarpal bone is the most prominent, and receives the greater part of the shock of the 
 blow. This bone articulates with the os magnum, so that the concussion is carried through this 
 bone to the scaphoid and semilunar, with which the head of the os magnum articulates, and by 
 these bones is transferred to the radius, along which it may be carried to the capitellum of the 
 humerus. The enlarged extremities of the phalanges are to be ])lainly felt: they form the 
 joints of the fingers. When the digits are bent the proximal phalanges of the joints form 
 prominences, which in the joint between the first and second phalanges is slightly hollowed, in 
 accordance with the grooved shape of their articular surfaces, whilst at the last row the prom- 
 inence is flattened and square-shaped. In the palm of the hand the four inner metacarpal bones 
 are covered by muscles, tendons, and the palmar fascia, and no part of them but their heads 
 is to be distinguished. With regard to the thumb, on the dorsal aspect the base of the meta- 
 carpal bone forms a prominence below the styloid process of the radius; the shaft is to be felt, 
 covered by tendons, terminating at its head in a flattened prominence, in front of which can be 
 felt the sesamoid bones. 
 
 Surgical Anatomy. — The carpal bones are not very liable to fracture, except from extreme 
 violence, when the parts may be so comminuted as to necessitate amputation. Occasionally they 
 . are the seat of tuberculous disease. The metacarpal bones and the phalanges are not unfrequently 
 broken by direct violence. The first metacarpal bone is the one most commonly fractured; 
 then the second, the fourth, and the fifth, the third being the one least frequently broken. There 
 are two diseases of the metacarpal bones and phalanges which require special mention on 
 account of the frequency of their occurrence. One is tuberculous dactylitis, consisting in a 
 deposit of tuberculous material in the medullary canal, expanding the bone, with subsequent 
 caseation and resulting necrosis. The other is chondroma, which is perhaps more frequently 
 found in connection with the metacarpal bones and phalanges than with any other bones. When 
 chondromatous growth takes place there are usually multiple tumors, and they may spring 
 either from the medullary canal or from the periosteum. 
 
 • 
 
 Development of the Bones of the Hand. 
 
 The Carpal Bones are each developed by a single centre. At birth they are 
 all cartilaginous. Ossification proceeds in the following order (Fig. 152): In the 
 OS magnum and unciform an ossific point appears during the first year, the former 
 preceding the latter; in the cuneiform, at the third year; in the trapezium and 
 semilunar, at the fifth year, the former preceding the latter; in the scaphoid, at 
 the sixth year; in the trapezoid, during the eighth year; and in the pisiform, about 
 the twelfth year. 
 
 Occasionally an additional bone, the os cenirale, is found in the carpus, lying 
 between the scaphoid, trapezoid, and os magnum. During the second month of 
 foetal life it is represented by a small cartilaginous nodule, which, however, 
 fuses with the cartilaginous scaphoid about the third month. Sometimes the 
 styloid process of the third metacarpal is detached and forms an additional 
 ossicle. 
 
 The Metacarpal Bones are each developed by two centres: one for the shaft 
 and one for the digital extremity for the four inner metacarpal bones; one for the 
 shaft and one for the base for the metacarpal bone of the thumb, which in this 
 
206 
 
 THE SKELETON 
 
 respect resembles the phalanges/ Ossification commences in the centre of the 
 shaft about the eighth or ninth week, and gradually proceeds to either end of the 
 bone: about the third year the digital extremities of the four inner metacarpal 
 bones and the base of the first metacarpal begin to ossify, and they unite about 
 the twentieth year. 
 
 Carpus. 
 
 One centre for each hone. ^^ 
 All cartilaginous at birth. ^/ 
 
 Metacarpus. 
 
 Two centres for each hone : 
 One for shaft, 
 One for digital extremity, 
 except first. 
 
 Phalanges. 
 
 Two centres for each hone 
 One for shaft, 
 One for metacarpal 
 extremity. 
 
 Appears Srd year. 
 
 Vs^^S. f/mfe 20th year. 
 
 "^ Appears 8th week. 
 
 ^-Appears Uth-Sth year. 
 I Unite ISth-SOlh year. 
 Appears 8th week. 
 
 Appears Uh-Sth year. 
 \ Unite mh-30 year. 
 '—Appears 8th week. 
 
 Fig. 152. — Plan of the development of the hand. 
 
 The Phalanges are each developed by two centres ; one for the shaft and one 
 for the base. Ossification commences in the shaft, in all three rows, at about the 
 eighth week, and gradually involves the whole of the bone excepting the upper 
 extremity. Ossification of the base commences in the first row between the third 
 and fourth years, and a year later in those of the second and third rows. The two 
 centres become united, in each row, between the eighteenth and twentieth years. 
 
 In the ungual phalanges the centre for the shaft appears at the distal extremity 
 of the phalanx, instead of at the middle of the shaft, as is the case with the other 
 phalanges. 
 
 THE LOWER EXTREMITY. 
 
 The bones of the lower extremity consist of those of the pelvic girdle, of the 
 thigh, of the leg, and of the foot. 
 
 ' Allan Thomson has demonstrated the fact that the first metacarpal bone is often developed from three 
 centres; that is to say, there is a separate nucleus for the di.stal end, forming a distinct epiphysis, visible at the 
 age of seven or eight years. He also states that there are traces of a proximal epiphysis in the second meta- 
 carpal bone. — Journal of Anatomy, 1869. 
 
THE OS INNOMINATUM 207 
 
 THE PELVIC GIRDLE. 
 
 The pelvic girdle consists of a single bone, the os innominatum, by which the 
 thigh is connected to the trunk. 
 
 The Os Innominatum, called also Os Coxae, Hip Bone, Haunch Bone, 
 the Nameless Bone (Figs. 153, 154). 
 
 The OS innominatum {in, not; nomino, I name) is so called from bearing no 
 resemblance to any known object. It is a large, irregularly shaped, flat bone, con- 
 stricted in the centre and expanded above and below. With its fellow of the 
 opposite side it forms the sides and anterior wall of the pelvic cavity. In young 
 subjects it consists of three separate parts, which meet and form the large, cup- 
 like cavity, the acetabulum, situated near the middle of the outer surface of the 
 bone; and, although in the adult these have become united, it is usual to describe 
 the bone as divisible into three portions — the ilium, the ischium, and the pubis. 
 
 The iUum, so called from its supporting the flank (ilium or ileuin, the flank), 
 is the superior, broad, and expanded portion which runs upward from the 
 acetabulum and forms the prominence of the hip. 
 
 The ischium {iayj.ov, the hip) is the inferior and strongest portion of the bone ; 
 it proceeds downward from the acetabulum, expands into a large tuberosity, and 
 then, curving forward, forms, with the descending ramus of the os pubis, a large 
 aperture, the obturator foramen. 
 
 The OS pubis is that portion which extends inward and downward from the 
 acetabulum to articulate in the middle line with the l)one of the opposite side: it 
 forms the front of the pelvis, supports the external organs of generation, and has 
 received its name from the skin over it being covered with hair (pubes). 
 
 The Ilium {os ilium). — The lower or constricted part of the ilium is thick, 
 though narrower than the expanded portion. It aids in the formation of the 
 acetabulum and is called the body {corpus ossis ilium). The broad expanded 
 portion of the ilium is thin in many places. It is called the ala {ala ossis ilium). 
 The ilium presents for examination two surfaces, an external and an internal; a 
 crest, and two borders, an anterior and a posterior. 
 
 External Surface or Dorsum of the Ilium (Fig. 153). — The posterior part of this 
 surface is directed backward and outward; its front part, downward and outward. 
 It is smooth, convex in front, deeply concave behind; bounded above by the crest, 
 below by the upper border of the acetabulum ; in front and behind by the anterior 
 and posterior borders. This surface is crossed in an arched direction by three 
 semicircular lines — the superior, middle, and inferior curved lines. The superior 
 curved line, or the posterior gluteal line {linea glutaea 'posterior), the shortest of the 
 three, commences at the crest, about two inches in front of its posterior extremity; 
 it is at first distinctly marked, but as it passes downward and backward to the 
 upper part of the great sacro-sciatic notch, where it terminates, it becomes less 
 marked, and is often altogether lost. Behind this line is a narrow semilunar 
 surface, the upper part of which is rough and affords attachment to part of 
 the Gluteus maximus; the lower part is smooth and has no muscular fibres 
 attached to it. The middle curved line, or the anterior gluteal line {linea glutaea 
 anterior), the longest, of the three, commences at the crest, about an inch 
 behind its anterior extremity, and, taking a curved direction downward and 
 backward, terminates at the upper part of the great sacro-sciatic notch. The 
 space between the superior and middle curved lines and the crest is concave, 
 and affords attachment to the Gluteus medius muscle. Near the central part 
 of this line may often be observed the orifice of a nutrient foramen. The inferior 
 
208 
 
 THE SKELETON 
 
 curved or inferior gluteal line (linea glutaea inferior), the least distinct of the three, 
 commences in front at the notch on the anterior border, and, taking a curved 
 direction backward and downward, terminates at the middle of the great sacro- 
 sciatic notch. The surface of bone included between the middle and inferior 
 
 nierior superior 
 spine. 
 
 OEMELLUS SUPERIOR. 
 
 Bpine of ischium. 
 
 OEMKLLUS INFERIOR. 
 
 PYRAMIOALIS. 
 DDUCTOR LOi 
 
 Fig. 153. — Right os innominatum. External surface. 
 
 curved lines is concave from above downward, convex from before backward, andj 
 affords attachment to the Gluteus minimus muscle. Beneath the inferior curvec 
 line, and corresponding to the upper part of the acetabulum, is a roughened sur-1 
 face (sometimes a depression), to which is attached the reflected tendon of the] 
 Rectus femoris muscle. 
 
 Internal Surface. — The internal surface (Fig. 154) of the ilium is bounded abovej 
 by the crest; below it is continuous with the pelvic surface of the os pubis andj 
 ischium, a faint line only indicating the place of union; and before and behind itj 
 
THE OS INNOMINATUM 
 
 209 
 
 is bounded by the anterior and posterior borders. It presents a large, smooth, 
 concave surface, called the iliac fossa, or venter ilii (fossa iliaca) , which lodges the 
 Iliacus muscle, and presents at its lower part the orifice of a nutrient canal (fora- 
 men nutricium) ; and below this a smooth, rounded border, the ilio-pectineal line 
 
 COMPRESSOR URETHR/E. 
 
 TRANSVERSUS PERINEI. 
 
 Crus penis.' erector penis. 
 
 Fig. 154. — Right os innominatum. Internal surface. 
 
 or the linea ilio-pectinea (linea arcuata) , which separates the iliac fossa from that 
 portion of the internal surface which enters into the formation of the true pelvis, 
 and which gives attachment to part of the Obturator internus muscle. Behind 
 the iliac fossa is a rough surface divided into two portions, an anterior and 
 a posterior. The anterior or auricular surface (fades auricularis) , so called from 
 its resemblance in shape to the ear, is coated with cartilage in the recent state, 
 and articulates with a surface of similar shape on the side of the sacrum. The 
 posterior portion (tuberositas iliaca) is rough, for the attachment of the posterior 
 sacro-iliac ligaments and |or a part of the origin of the Erector and Multifidus 
 
 14 
 
210 THE SKELETON 
 
 spinse. In many bones a furrow exists in front, under and behind the auricular 
 surface. This furrow is the paraglenoid sulcus (sulcus paraglenoidalis) , and it 
 affords attachment to the sacro-sciatic ligaments. 
 
 The Crest of the Ilium (crista iliaca). — The crest of the ilium is convex in its 
 general outline and sinuously curved, being concave inward in front, concave 
 outward behind. It is longer in the female than in the male, very thick behind, 
 and thinner at the centre than at the extremities. It terminates at either end inj 
 a prominent eminence, the anterior superior and posterior superior spinous processj 
 (spina iliaca anterior superior et spina iliaca posterior superior) . The surface of j 
 the crest is broad, and divided into an external lip (labium externum) , an inter- 
 nal lip (labium internum), and an intermediate space (linea intermedia). About 
 two inches behind the anterior superior spinous process there is a prominent 
 tubercle on the outer lip. To the external lip is attached the Tensor fascif 
 femoris, Obliquus externus abdominis, and Latissimus dorsi, and along its! 
 whole length, the fascia lata; to the space between the lips, the Internal oblique;! 
 to the internal lip, the Transversalis, Quadratus lumborum, and Erector spinse,] 
 the Iliacus, and the fascia iliaca. 
 
 Anterior Border. — The anterior border of the ilium is concave. It presents twol 
 projections, separated by a notch. Of these, the uppermost, situated at the junc-j 
 tion of the crest and anterior border, is called the anterior superior spinous processj 
 of the ilium (spina iliaca anterior superior), the outer border of which gives 
 attachment to the fascia lata and the origin of the Tensor fasciae femoris (teri5or| 
 vagincB femoris) ; its inner border, to the Iliacus; while its extremity affords attach- 
 ment to Poupart's ligament and the origin of the Sartorius. Beneath this emi- 
 nence is a notch which gives attachment to the Sartorius muscle, and across 
 which passes the external cutaneous nerve. Below the notch is the anterior 
 inferior spinous process (spina iliaca anterior inferior), which terminates in thel 
 upper lip of the acetabulum; it gives attachment to the straight tendon of] 
 the Rectus femoris muscle and the ilio-femoral ligament. On the inner side of thej 
 anterior inferior spinous process is a broad, shallow groove, over which passes 
 the Ilio-psoas muscle. This groove is bounded internally by an eminence, thel 
 ilio-pectineal eminence (eminentia iliopectinea) , which marks the point of union] 
 of the ilium and os pubis. 
 
 Posterior Border. — -The posterior border of the ilium, shorter than the anterior,! 
 also presents two projections separated by a notch, the posterior superior spinous! 
 process (spina iliaca posterior superior) and the posterior inferior spinous process! 
 (spina iliaca posterior inferior). The former corresponds with that portion ofj 
 the inner surface of the ilium which serves for the attachment of the oblique! 
 portion of the sacro-iliac ligaments and the Multifidus spinae muscle; the latter,! 
 to the auricular portion which articulates with the sacrum. Below the pos- 
 terior inferior spinous process is a deep notch, the great sciatic, ilio-sciatic, orl 
 the great sacro-sciatic notch (incisura isckiadica major). 
 
 The Ischium (os ischii). — The ischium forms the lower and back part of thej 
 OS innominatum. It is divisible into a thick and solid portion — the body; a large,] 
 rough eminence, on which the trunk rests in sitting — the tuberosity; and a thin! 
 part which passes forward and slightly upward — the ramus. 
 
 The Body (corpus ossis ischii). — The body, somewhat triangular in form, pre- 
 sents three surfaces, external, internal, and posterior; and three borders, external, 
 internal, and posterior. The external surface corresponds to that portion of the 
 acetabulum formed by the ischium; it is smooth and concave, and forms ai 
 little more than two-fifths of the acetabular cavity; its outer margin is bounded] 
 by a prominent rim or lip, the external border, to which the cotyloid fibro- 
 cartilage is attached. Below the acetabulum, between it and the tuberosity, is] 
 a deep groove, along which the tendon of the Obturator externus muscle runs 
 
THE OS INNOMINATUM 211 
 
 as it passes outward to be inserted into the digital fossa of the femur. The 
 internal surface is smooth, concave, and enters into the formation of the lateral 
 boundary of the true pelvic cavity. This surface is perforated by two or three 
 large, vascular foramina, and affords attachment to part of the Obturator inter- 
 nus muscle. The 'posterior surface is quadrilateral in form, broad and smooth. 
 Below, where it joins the tuberosity, it presents a groove, the obturator groove 
 (sulcus obturatorius) , continuous with that on the external surface, for the tendon 
 of the Obturator externus muscle. The lower edge of this groove is formed by 
 the tuberosity of the ischium, and affords attachment to the Gemellus inferior 
 muscle. This surface is limited, externally, by the margin of the acetabulum; 
 behind, by the posterior border; it supports the Pyriformis, the two Gemelli, and 
 the Obturator internus muscles in their passage outward to the great trochanter. 
 The external border forms the prominent rim of the acetabulum, and separates 
 the posterior from the external surface. To it is attached the cotyloid fibro- 
 cartilage. The internal border is thin, and forms the outer circumference of the 
 obturator foramen. The posterior border of the body of the ischium presents, a 
 little below the centre, a thin and pointed, triangular eminence, the spine of the 
 ischium (spina ischiadica) , more or less elongated in different subjects; its exter- 
 nal surface gives attachment to the Gemellus superior, its internal surface to 
 the Coccygeus and Levator ani; whilst to the pointed extremity is connected the 
 lesser sacro-sciatic ligament. Above the spine is a notch of large size, the great 
 sacro-sciatic notch (incisura ischiadica major), converted into a foramen, the great 
 sacro-sciatic foramen (foramen ischiadicum majus), by the lesser sacro-sciatic liga- 
 ment; it transmits the Pyriformis muscle, the gluteal vessels, and superior and 
 inferior gluteal nerves; the sciatic vessels, the greater and lesser sciatic nerves, 
 the internal pudic vessels and nerve, and the nerves to the Obturator internus and 
 Quadratus femoris. Of these, the gluteal vessels and superior gluteal nerve pass 
 out above the Pyriformis muscle, the other structures, below it. Below the spine 
 is a smaller notch, the lesser sacro-sciatic notch (incisura ischiadica minor) ; it is 
 smooth, coated in the recent state with cartilage, the surface of which presents 
 two or three ridges corresponding to the subdivisions of the tendon of the Obtu- 
 rator internus, which winds over it. It is converted into a foramen, the lesser 
 sacro-sciatic foramen (foramen ischiadicum minus), by the sacro-sciatic ligaments, 
 and transmits the tendon of the Obturator internus, the nerve which supplies 
 that muscle, and the internal pudic vessels and nerve. 
 
 The Tuberosity of the Ischium (tuber ischiadicum). — The tuberosity of the 
 ischium is the portion of bone between the body and the ascending ramus. 
 Some anatomists name this portion of bone the descending or superior ramus 
 (ramus superior ossis ischii), and restrict the term tuberosity to the surface of 
 the bone which is rough, and is directed backward and outward. The tuber- 
 osity presents for examination three surfaces: external, internal, and posterior. 
 The external surface is quadrilateral in shape, and rough for the attachment of 
 muscles. It is bounded above by the groove for the tendon of the Obturator 
 externus; in front it is limited by the posterior margin of the obturator foramen, 
 and below it is continuous with the ramus of the bone; behind, it is bounded by 
 a prominent margin which separates it from the posterior surface. In front of 
 this margin the surface gives attachment to the Quadratus femoris, and anterior 
 to this to some of the fibres of origin of the Obturator externus. The lower part 
 of the surface gives origin to part of the Adductor magnus. The internal sur- 
 face forms part of the bony wall of the true pelvis. In front it is limited by the 
 posterior margin of the obturator foramen. Behind, it is bounded by a sharp 
 ndge, for the attachment of a falciform prolongation of the great sacro-sciatic 
 ligament; it sometimes presents a groove on the inner side of this ridge for the 
 lodgement of the internal pudic vessels and nerve; and, more anteriorly, has 
 
212 THE SKELETON 
 
 attached the Transversus perinaei and Erector penis muscles. The 'posterior 
 surface is divided into two portions — a lower rough, somewhat triangular part, 
 and an upper smooth, quadrilateral portion. The anterior portion is subdivided 
 by a prominent vertical ridge, passing from base to apex, into two parts; the 
 outer one gives attachment to the Adductor magnus; the inner to the great sacro- 
 sciatic ligament. The upper portion is subdivided into two facets by an oblique 
 ridge which runs downward and outward; from the upper and outer facet arises 
 the Semimembranosus; from the lower and inner, the Biceps and Semitendinosus. 
 
 The Ramus or Inferior Ramus or Ascending Ramus of the Ischium {ramus inferior 
 ossis ischii) . — The ramus is the thin, flattened part of the ischium which ascends 
 from the tuberosity upward and inward, and joins the descending ramus of the 
 OS pubis, their point of junction being indicated in the adult by a rough line. 
 The outer surface of the ramus is rough, for the attachment of the Obturator 
 externus muscle, and also some fibres of the Adductor magnus; its inner sur- 
 face forms part of the anterior wall of the pelvis. Its inner border is thick, 
 rough, slightly everted, forms part of the outlet of the pelvis, and presents two 
 ridges and an intervening space. The ridges are continuous with similar ones 
 on the descending ramus of the os pubis: to the outer one is attached the deep 
 layer of the superficial perineal fascia, and to the inner, the superficial layer of 
 the triangular ligament of the urethra. If these two ridges are traced downward, 
 they will be found to join with each other just behind the point of origin of the 
 Transversus perinsei muscle; here the two layers of fascia are continuous behind 
 the posterior border of the muscle. To the intervening space, just in front of the 
 point of junction of the ridges, is attached the Transversus perinsei muscle, and 
 in front of this a portion of the crus penis vel clitoridis and the Erector penis vel 
 clitoridis muscle. Its outer border is thin and sharp, and forms part of the inner 
 margin of the obturator foramen. 
 
 The Pubis {os pubis). — The OS pubis forms the anterior part of the os innomi- 
 natum, and, with the bone of the opposite side, forms the front boundary of the 
 true pelvic cavity. It is divisible into a body, an ascending and a descending ramus. 
 
 The Body {corpus ossis pubis) . — The body is the broad portion of bone formed 
 by the junction of the two rami. It is somewhat quadrilateral in shape, and 
 presents for examination two surfaces and three borders. The anterior surface 
 is rough, directed downward and outward, and serves for the attachment of 
 various muscles. To the upper and inner angle, immediately below the crest, 
 is attached the Adductor longus; lower down, from without inward, are attached 
 the Obturator externus, the Adductor brevis, and the upper part of the Gracilis. 
 The posterior surface, convex from above downward, concave from side to side, 
 is smooth, and forms part of the anterior wall of the pelvis. It gives attach- 
 ment to the Levator ani. Obturator internus, a few muscular fibres prolonged 
 from the bladder, and the pubo-prostatic ligaments. The upper border presents 
 fer examination a prominent tubercle, which projects forward and is called the 
 spine {tuberculum pubicum) ; to it are attached the outer pillar of the external 
 abdominal ring and Poupart's ligament. Passing upward and outward from 
 this is a prominent ridge, forming part of the ilio-pectineal line {linea arcuMta), 
 and called the pecten ossis pubis. It marks the brim of the true pelvis: to it are 
 attached a portion of the conjoined tendon of the Internal oblique and Trans- 
 versalis muscles, Gimbernat's ligament, and the triangular fascia of the abdomen. 
 Internal to the spine of the os pubis is the crest, which extends from this process 
 to the iimer extremity of the bone. It affords attachment, anteriorly, to the con- 
 joined tendon of the Internal obhque and Transversalis ; and posteriorly, to the 
 Rectus and Pyramidalis muscles. The point of junction of the crest with the 
 inner border of the bone (symphysis) is called the angle ; to it, as well as to the 
 symphysis, is attached the internal pillar of the external abdominal ring. The 
 
THE OS INNOMINATUM 213 
 
 internal border is articular; it is oval, covered by eight or nine transverse ridges, 
 or a series of nipple-like processes arranged in rows, separated by grooves; they 
 serve for the attachment of a thin layer of cartilage, placed between it and the 
 central fibro-cartilage. The outer border presents a sharp margin, which forms 
 part of the circumference of the obturator foramen and affords attachment to 
 the obturator membrane. 
 
 The Ascending or Superior Ramus of the Pubis {ramus superior ossis pubis). — 
 The ascending or superior ramus extends from the body to the point of junction 
 of the OS pubis with the ilium, and forms the upper part of the circumference of 
 the obturator foramen. It presents for examination a superior, inferior, and 
 posterior surface, and an outer extremity, The superior surface presents a con- 
 tinuation of the ilio-pectineal line, already mentioned as commencing at the 
 pubic spine. In front of this ridge the surface of bone is triangular in form, 
 wider externally than internally, smooth, and is covered by the Pectineus muscle. 
 The surface is bounded externally by a rough eminence, the ilio-pectineal emi- 
 nence (eminentia iliopectinea) , which serves to indicate the point of junction of 
 the ilium and os pubis, and gives attachment to the Psoas parvus, when this 
 muscle is present. The triangular surface is bounded below by a prominent 
 ridge, the obturator crest (crista obturatoria) , which extends from the cotyloid 
 notch to the spine of the os pubis. The inferior surface forms the upper bound- 
 ary of the obturator foramen, and presents externally a broad and deep oblique 
 groove, the obturator groove (sulcus obturatorius) , for the passage of the obturator 
 vessels and nerve; and internally a sharp margin which forms part of the cir- 
 cumference of the obturator foramen, and to which the obturator membrane is 
 attached. The posterior surface forms part of the anterior boundary of the true 
 pelvis. It is smooth, convex from above downward, and affords attachment to 
 .some fibres of the Obturator internus. The outer extremity, the thickest part of 
 the ramus, forms one-fifth of the cavity of the acetabulum. 
 
 The Descending or Inferior Ramus of the Pubis (ramus inferior ossis pubis) . — 
 The descending or inferior ramus of the os pubis is thin and flattened. It passes 
 outward and downward, becoming narrower as it descends, and joins with the 
 ramus of the ischium. Its anterior surface is rough, for the attachment of muscles 
 — the Gracilis along its inner border; a portion of the Obturator externus where it 
 enters into the formation of the foramen of that name; and between these two 
 muscles the Adductores brevis and magnus from within outward. The posterior 
 surface is smooth, and gives attachment to the Obturator internus, and, close to 
 the inner margin, to the Compressor urethrae. The inner border is thick, rough, 
 and everted, especially in females. It presents two ridges, separated by an inter- 
 vening space. The ridges extend downward, and are continuous with similar 
 ridges on the ascending ramus of the ischium; to the external one is attached 
 the deep layer of the superficial perineal fascia, and to the internal one the super- 
 ficial layer of the triangular ligament of the urethra. The outer border is thin 
 and sharp, forms part of the circumference of the obturator foramen, and gives 
 attachment to the obturator membrane. 
 
 The Cotyloid Cavity or Acetabulum. — The cotyloid cavity, or acetabulum, is 
 a deep, cup-shaped, hemispherical depression, directed downward, outward, and 
 forward; formed internally by the os pubis, above by the ilium, behind and below 
 by the ischium, a little less than two-fifths being formed by the ilium, a little more 
 than two-fifths by the ischium, and the remaining fifth by the pubic bone. It is 
 bounded by a prominent, uneven rim, which is thick and strong above, and serves 
 for the attachment of the cotyloid ligament, which contracts its orifice and deepens 
 the surface for articulation. It presents below a deep notch, the cotyloid notch 
 (mcisura acetabuli), which is continuous with a circular depression, the fossa of 
 the acetabulum (fossa acetabuli), at the bottom of the cavity: this depression is 
 
214 
 
 THE SKELETON 
 
 perforated by numerous apertures, lodges a mass of fat, and its margins, as well 
 as those of the notch, serve for the attachment of the ligamentum teres. In fronts 
 above and behind the fossa acetabuli, is a concave rim of bone (fades lunata) . The 
 cotyloid notch is converted, in the natural state, into a foramen by a dense liga- 
 mentous band which passes across it. Through this foramen the nutrient vessels 
 and nerves enter the joint. 
 
 The Obturator or Thyroid Foramen (foramen ohturatum) . — The obturator or 
 thyroid foramen is a large aperture situated between the ischium and os pubis. 
 In the male it is large, of an oval form, its longest diameter being obliquely from 
 before backward; in the female it is smaller and more triangular. It is bounded 
 by a thin, uneven margin, to which a strong membrane is attached, and presents, 
 anteriorly, a deep groove, the obturator groove (sulcus ohturatorius) , which runs 
 from the pelvis obliquely inward and downward. This groove is converted into 
 a foramen by the obturator membrane, and transmits the obturator vessels and 
 nerve. 
 
 Structure. — This bone consists of much cancellous tissue, especially where itl 
 is thick, enclosed between two layers of dense, compact tissue. In the thinnerj 
 parts of the bone, as at the bottom of the acetabulum and centre of the iliac 
 fossa, it is usually semitransparent, and composed entirely of compact tissue. 
 
 Development (Fig. 155). — ^y eight centres: three primary — one for the ilium J 
 one for the ischium, and one for the os pubis; and five secondary — one for the) 
 
 By eight centres \ l^"""^ primary {Ilium, Ischium, and Os Pubis). 
 " " ( Five secondary. 
 
 8. Symphysis pubis. 
 
 The three primary centres unite through a \-shaped piece about puberty. 
 Epiphyses appear about puberty, and unite about the twenty-fifth year. 
 
 Fig. 155. — Plan of the development of the os innominatum. 
 
 crest of the ilium, one for the anterior inferior spinous process (said to occur more: 
 frequently in the male than in the female), one for the tuberosity of the ischium, 
 one for the symphysis pubis (more frequent in the female than the male), and one 
 or more for the Y-shaped piece at the bottom of the acetabulum. These various 
 centres appear in the following order: First, in the ilium, at the lower part of 
 
THE PELVIS 215 
 
 the bone, immediately above the sciatic notch, at about the eighth or ninth week; 
 secondly, in the body of the ischium, at about the third month of foetal hfe; 
 thirdly, in the body of the os pubis, between the fourth and fifth months. At 
 birth the three primary centres are quite separate, the crest, the bottom of the 
 acetabulum, the ischial tuberosity, and the rami of the ischium and pubes being 
 still cartilaginous. At about the seventh or eighth year the rami of the os pubis 
 and ischium are almost completely united by bone. About the thirteenth or 
 fourteenth year the three divisions of the bone have extended their growth into 
 the bottom of the acetabulum, being separated from each other by a Y-shaped 
 portion of cartilage, which now presents traces of ossification, often by two or 
 more centres. One of these, the os acetabuli, appears about the age of twelve, 
 between the ilium and os pubis, and fuses with them about the age of eighteen. 
 It forms the pubic part of the acetabulum. The ilium and ischium then become 
 joined, and lastly the os pubis to the ischium, through the intervention of this 
 Y-shaped portion. At about the age of puberty ossification takes place in each 
 of the remaining portions, and they become joined to the rest of the bone 
 between the twentieth and twenty-fifth years. Separate centres are frequently 
 found for the pubic and ischial spines 
 
 Articulations. — With its fellow of the opposite side, the sacrum, and femur. 
 
 Attachment of Muscles. — To the ilium, sixteen. To the outer lip of the crest, 
 the Tensor vaginje femoris, Obliquus externus abdominis, and Latissimus dorsi; 
 to the internal lip, the Iliacus, Transversalis, Quadratus lumborum, and Erector 
 spintie; to the interspace between the lips, the Obliquus internus. To the outer 
 surface of the ilium, the Gluteus maximus, Gluteus medius. Gluteus minimus, 
 reflected tendon of the Rectus; to the upper part of the great sacro-sciatic notch, a 
 portion of the Pyriformis; to the internal surface, the Iliacus; to that portion of 
 the internal surface below the linea ilio-pectinea, the Obturator internus to the 
 internal surface of the posterior superior spine, and the Multifidus spinse; to the 
 anterior border, the Sartorius and straight tendon of the Rectus. To the ischium, 
 thirteen. To the outer surface of the ramus, the Obturator externus and Adductor 
 magnus; to the internal surface, the Obturator internus and Erector penis. To the 
 spine, the Gemellus superior. Levator ani, and Coccygeus. To the tuberosity, the 
 Biceps, Semitendinosus, Semimembranosus, Quadratus femoris. Adductor mag- 
 nus, Gemellus inferior, Transversus periniei, Erector penis. To the pubis, 
 sixteen: Obliquus externus, Obliquus internus, Transversalis, Rectus, Pyramid- 
 alis, Psoas parvus, Pectineus, Adductor magnus, Adductor longus, Adductor 
 brevis. Gracilis, Obturator externus and internus, Levator ani, Compressor 
 urethrie, and occasionally a few fibres of the Accelerator urinae. 
 
 The Pelvis (Figs. 156, 157). 
 
 The pelvis, so c^led from its resemblance to a basin (L. pelvis), is stronger 
 and more massively constructed than either the cranial or thoracic cavity; it is a 
 bony ring, interposed between the lower end of the spine, which it supports, and 
 the lower extremities, upon which its rests. It is composed of four bones: the two 
 ossa innominata, which bound it on either side and in front, and the sacrum and 
 coccyx, which complete it behind. The pelvis is divided by an oblique plane 
 passing through the prominence of the sacrum, the linea ilio-pectinea, and the 
 upper margin of the symphysis pubis into the false and true pelvis. 
 
 The False Pelvis (pelvis major) .—The false pelvis is the expanded portion of 
 the pelvic cavity which is situated above this plane. It is bounded on each side 
 by the ossa ilii; in front it is incomplete, presenting a wide interval between the 
 spinous processes of the ilia on either side, which is filled up in the recent state by 
 the parietes of the abdomen; behind, in the middle line, is a deep notch., This 
 
216 
 
 THE SKELETON 
 
 broad, shallow cavity is fitted to support the intestines and to transmit part of 
 their weight to the anterior wall of the abdomen, and is, in fact, really a portion 
 of the abdominal cavity. The term false pelvis is incorrect, and this space ought 
 
 Fig. 156. — Male pelvis (adult). 
 
 more properly to be regarded as part of the hypogastric and iliac regions of the 
 abdomen. 
 
 The True Pelvis (pelvis minor) . — The true pelvis is that part of the pelvic 
 cavity which is situated beneath the plane. It is smaller than the false pelvis, 
 
 Fig. 157. — Female pelvis (adult). 
 
 but its walls are more perfect. For convenience of description it is divided 
 into a superior circumference or inlet, an inferior circumference or outlet, and a 
 cavity. 
 
THE PELVIS 217 
 
 The Superior Circumference or Inlet (apertura pelvis superior) . — The superior cir- 
 cumference forms the brim of the pelvis, the included space being called the inlet. 
 It is formed by the linea ilio-pectinea, completed in front by the crests of the 
 pubic bones, and behind by the anterior margin of the base of the sacrum and 
 sacro-vertebral angle. The brim of the pelvis is the name often given to the 
 marofin of the inlet. The inlet of the pelvis is somewhat heart-shaped, obtusely 
 pointed in front, diverging on either side, and encroached upon behind by the 
 projection forward of the promontory of the sacrum. It has three principal 
 diameters: antero-posterior (sacro-pubic), transverse, and oblique. The antero- 
 posterior or conjugate diameter (conjugata) extends from the sacro-vertebral angle 
 to the symphysis pubis. The anatomical conjugate (conjugata anatomica) is the 
 distance between the sacro-vertebral angle and the top of the symphysis pubis. 
 Its average measurement is four inches in the male and four and three-fifths inches 
 in the female. The true, available, or obstetric conjugate {conjugata gyncecologica) 
 is the distance between the sacro-vertebral angle and the nearest point upon the 
 symphysis. This point is a little behind and below the upper margin (Webster). 
 The average distance in women is four and three-eighths inches. The diagonal 
 conjugate (diagonalconjugata) is measured from the sacro-vertebral angle to the 
 subpubic ligament. The distance exceeds the true conjugate by one-half or two- 
 thirds of an inch. The transverse diameter (diameter transversa) extends across 
 the greatest width of the inlet, from the middle of the brim on one side to the 
 same point on the opposite; its average measurement is five inches in the male, 
 five and one-fourth inches in the female. The oblique diameter (diameter ohliqua) 
 extends from the margin of the pelvis, corresponding to the ilio-pectineal eminence 
 on one side, to the sacro-iliac articulation on the opposite side; its average 
 measurement is four and a quarter inches in the male and five in the female. The 
 oblique diameters are named right or left oblique, according to the sacro-iliac 
 joint from which the measurement is taken. 
 
 The Cavity.— The cavity of the true pelvis is bounded in front by the symphysis 
 pubis; behind, by the concavity of the sacrum and coccyx, which, curving forward 
 above and below, contracts the inlet arid outlet of the canal; and laterally it is 
 bounded by a broad, smooth, quadrangular surface of bone, corresponding to the 
 inner surface of the body of the ischium and that part of the ilium which is below 
 the ilio-pectineal line. The cavity is shallow in front, measuring at the symphy- 
 sis an inch and a half in depth, three inches and a half in the middle, and four 
 inches and a half posteriorly. From this description it will be seen that the cavity 
 of the pelvis is a short, curved canal, considerably deeper on its posterior than 
 on its anterior wall. This cavity contains, in the recent subject, the rectum, 
 bladder, and part of the organs of generation. The rectum is placed at the back 
 of the pelvis, and corresponds to the curve of the sacro-coccygeal column; the 
 bladder in front, behind the symphysis pubis. In the female the uterus and 
 vagina occupy the interval between these viscera. 
 
 The Lower Circumference or Outlet (apertura pelvis inferior). — The lower cir- 
 cumference of the pelvis is very irregular, and forms what is called the outlet. 
 It is bounded by three prominent eminences : one posterior, formed by the point 
 of the coccyx; and one on each side, the tuberosities of the ischia. These emi- 
 nences are separated by three notches ; one in front, the pubic arch (arcus pubis) , 
 formed by the convergence of the rami of the ischia and pubic bones on each 
 side. The other notches, one on each side, are formed by the sacrum and coccyx 
 behind, the ischium in front, and the ilium above; they are called the sacro-sciatic 
 notches; in the natural state they are converted into foramina by the lesser and 
 greater sacro-sciatic ligaments. In the recent state, when the ligaments are in 
 situ, the outlet of the pelvis is lozenge-shaped, bounded in front by the subpubic 
 ligament and the rami of the os pubis and ischium; on each side by the tuber- 
 
218 
 
 THE SKELETON 
 
 osities of the ischia; and behind by the great sacro-sciatic Hgaments and the tip 
 of the coccyx. 
 
 The diameters of the outlet of the pelvis are two, antero-posterior and trans- 
 verse. The antero-posterior (conjugate) diameter (diameter recta of the outlet) 
 extends from the tip of the coccyx to the lower part of the symphysis pubis ; its 
 average measurement is three and three-quarter inches in the male and four and 
 one-half inches in the female. The antero-posterior diameter varies with the 
 length of the coccyx, and is capable of increase or diminution on account of the 
 mobility of that bone. During labor the coccyx may be bent back so that the 
 conjugate is increased one inch, or even one and one-fourth inches. The trails- 
 verse diameter extends from the posterior part of one ischiatic tuberosity to the 
 same point on the opposite side: the average measurement is three and a half 
 inches in the male and four and three-fourths in the female.^ 
 
 Oblique diameters are not employed, as there are no fixed points from which 
 to measure them. 
 
 Position of the Pelvis. — In the erect posture the pelvis is placed obliquely with 
 regard to the trunk of the body: the bony ring, which forms the brim of the true 
 pelvis, is placed so as to form an angle of about 60 to 65 degrees with the ground 
 on which we stand (inclinatio pelvis). The pelvic surface of the symphysis pubis 
 looks upward and backward, the concavity of the sacrum and coccyx downward 
 and forward, the base of the sacrum in well-formed female bodies being nearly 
 four inches above the upper border of the symphysis pubis, and the apex of the 
 
 coccyx a little more than half an inch above its 
 lower border. In consequence of the obliquity 
 of the pelvis the line of gravity of the head, 
 which passes through the middle of the odontoid 
 process of the axis and through the points of 
 junction of the curves of the vertebral column to 
 the sacro-vertebral angle, descends toward the 
 front of the cavity; so that it bisects a line 
 drawn transversely through the middle of the 
 heads of the thigh bones. And thus the centre 
 of gravity of the head is placed immediately 
 over the heads of the thigh bones on which the 
 trunk is supported. 
 
 Axes of the Pelvis (Fig. 158).— The plane of 
 the inlet of the true pelvis will be represented by 
 a line drawn from the base of the sacrum to the 
 upper margin of the symphysis pubis. A line 
 carried at right angles with this at its middle 
 would correspond at one extremity with the 
 umbilicus, and at the other with the middle of 
 the coccyx: the axis of the inlet is therefore directed downward and backward. 
 The axis of the outlet, produced upward, would touch the base of the sacrum, 
 and is therefore directed downward and forward. The axis of the cavity is curved 
 like the cavity itself: this curve corresponds to the concavity of the sacrum 
 and coccyx, the extremities being indicated by the central points of the inlet and 
 
 pi^W "'^*'«*- 
 
 Fig. 158. — ;- Vertical section of the pelvis 
 with lines indicating the axis of the pelvis. 
 
 _ ^ The measurements of the pelvis given above are. I believe, fairly accurate, but different measurements are 
 given by various authors, no doubt due in a great measure to differences in the physique and stature of the 
 population from whom the measurements have been taken. The accompanying chart has been formulated to 
 show the measurements of the pelvis which are adopted by many obstetricians. — ]']d. 
 
 Diameters of the True Pelvis in Woman. 
 
 
 Antero-posterior. 
 
 Oblique. 
 
 Transverse. 
 
 Of inlet 
 
 . 4'''/5 inches (118 mm.) 
 
 5 inches (127 mm.) 
 
 S% inches (135 mm.) 
 
 Of outlet . 
 
 . 4% inches (115 mm. ) 
 
 
 4% inches (120 mm.) 
 
THE PELVIS 
 
 219 
 
 outlet. A knowledge of the direction of these axes serves to explain the course 
 of tlie foetus in the passage through the pelvis during parturition. It is also 
 important to the surgeon, as indicating the direction of the force required in the 
 removal of calculi from the bladder by the sub-pubic operation, and as deter- 
 mining the direction in which instruments should be used in operations upon the 
 pelvic viscera. 
 
 Differences between the Male and the Female Pelvis. — The female pelvis, 
 looked at as a whole, is distinguished from the male by the bones being more 
 delicate, by its width being greater and its depth smaller. The whole pelvis is 
 less massive, and its bones are lighter and more slender, and its muscular impres- 
 sions are slightly marked. The iliac fossjT? are shallow, and the anterior iliac spines 
 widely separated; hence the greater prominence of the hips. The inlet in the 
 female is larger than in the male ; it is more nearly circular, and the sacro-vertebral 
 angle projects less forward. The cavity is shallower and wider; the sacrum is 
 shorter, wider, and less curved; the obturator foramina are triangular, and smaller 
 in size than in the male. The outlet is larger and the coccyx more movable. The 
 spines of the ischia project less inward. The tuberosities of the ischia and the 
 acetabula are wider apart. The pubic arch is wider and more rounded than in the 
 male, where it is an angle rather than an arch. In consequence of this the width of 
 the fore part of the pelvic outlet is much increased and the passage of the foetal 
 head facilitated. 
 
 The size of the pelvis varies, not only in the two sexes, but also in different 
 members of the same sex. This does not appear to be influenced in any way by 
 
 Fig. 159. — Diameters of the pelvic inlet. 
 
 the height of the individual. Women of short stature, as a rule, have broad pelves. 
 Occasionally the pelvis is equally contracted in all its dimensions, so much so that 
 all its diameters measure an inch less than the average, and this even in women 
 of average height and otherwise well formed. The principal divergences, however, 
 are found at the inlet, and affect the relation of the antero-posterior to the trans- 
 verse diameter. Thus we may have a pelvis the inlet of which is elliptical either 
 in a transverse or antero-posterior direction; the transverse diameter in the former 
 and the antero-posterior in the latter greatly exceeding the other diameters. Again, 
 the inlet of the pelvis in some instances is seen to be almost circular. The same 
 differences are found in various races. European women are said to have the 
 
220 
 
 THE SKELETON 
 
 most roomy pelves. That of the negress is smaller, circular in shape, and with a 
 narrow pubic arch. The Hottentots and Bushwomen possess the smallest pelves. 
 In the foetus and for several years after birth the pelvis is small in proportion 
 to that of the adult. The cavity is deep, and the projection of the sacro-vertebral 
 angle less marked. The generally accepted opinion that the female pelvis does 
 not acquire its sexual characters until after puberty has been shown by recent 
 
 Fig. 160. — Diameters of the pelvic outlet. 
 
 observations^ to be erroneous, the characteristic differences between the male and 
 female pelvis being distinctly indicated as early as the fourth month of foetal life. 
 At birth these differences are distinct (Romiti), the female pelvis possessing less 
 straight ilia, a broader subpubic arch, and less height than the male. 
 
 Surface Form. — The pelvic bones are so thickly covered with muscles that it is only at 
 certain points that they approach the surface and can be felt through the skin. In front, 
 the anterior superior spinous process is easily recognized; a portion of it is subcutaneous, 
 and in thin subjects may be seen to stand out as a prominence at the outer extremity of the fold 
 of the groin. In fat subjects its position is marked by an oblique depression amongst the sur- 
 rounding fat, at the bottom of which the bony process may be felt. Proceeding upward and 
 outward from this process, the crest of the ilium may be traced throughout its whole length, 
 sinuously curved. It is represented, in muscular subjects, on the surface, by a groove or fur- 
 row, the iliac furrow, caused by the projection of fleshy fibres of the External oblique muscles 
 of the abdomen ; the iliac furrow lies slightly below the level of the crest. It terminates behind 
 in the posterior superior spinous process, the position of which is indicated by a slight depression 
 on a level with the spinous process of the second sacral vertebra. Between the two posterior 
 superior spinous processes, but at a lower level, is to be felt the spinous process of the third - 
 sacral vertebra (see page 69). Another part of the bony pelvis easily accessible to touch is the 
 tuberosity of the ischium, situated beneath the gluteal fold, and, when the hip is flexed, it is 
 easily felt, as it is then to a great extent uncovered by muscle. Finally, the spine of the os 
 pubis can always be readily felt, and constitutes an important surgical guide, especially in con- 
 nection with the subject of hernia. It is nearly in the same horizontal line with the upper edge 
 of the great trochanter. In thin subjects it is very apparent, but in the obese it is obscured by 
 the pubic fat. It can, however, be detected by following up the tendon of origin of the 
 Adductor longus muscle. 
 
 Surgical Anatomy. — There is arrest of development in the bones of the pelvis in cases 
 of extroversion of the bladder ; the anterior part of the pelvic girdle being deficient, the bodies 
 of the pubic bones imperfectly developed, and the symphysis absent. The pubic bones are 
 separated to the extent of from two to four inches, the superior rami shortened and directed 
 forward, and the obturator foramen diminished in size, narrowed, and turned outward. The 
 
 ' Fehling, Zeitschr. fiir Geburt. u. Gynaek., Bd. ix. und x.; and Arthur Thomson, Journal of Anatomy and 
 Physiology, vol. xxxiii. 
 
THE FEMUR, OB THIGH BONE 221 
 
 iliac bones are straightened out more than normal. The sacrum is very peculiar. The lateral 
 curve, instead of being concave, is flattened out or even convex, with the ilio-sacral facets turned 
 more outward than normal, while the vertical curve is straightened.' 
 
 Fractures of the pelvis are divided into fractures of the false pelvis and of the true pelvis. 
 Fractures of the false pelvis vary in extent: a small portion of the iliac crest may be broken or 
 one of the spinous processes may be torn off, and this may be the result of muscular action; or 
 the bone may be extensively comminuted. This latter accident is the result of some crushing 
 violence, and may be complicated with fracture of the true pelvis. These cases may be accom- 
 panied by injury to the intestine as it lies in the hollow of the bone, or to the iliac vessels as 
 they course along the margin of the true pelvis. Fractures of the true pelvis generally occur 
 through the ascending ramus of the os pubis and the ramus of the ischium, as this is the weakest 
 part of the bony ring, and may be caused either by crushing violence applied in an antero- 
 posterior direction, when the fracture occurs from direct force, or by compression laterally, 
 when the acetabula are pressed together, and the bone gives way in the same place from indirect 
 violence. Occasionally the injury may be double, a break occurring on both sides of the body. 
 In fracture of the true pelvis the contained viscera are liable to be damaged: the small intestines, 
 the urethra, the bladder, the rectum, the vagina, and even the uterus, in the female, have all 
 been lacerated by a displaced fragment. Fractures of the acetabulum are occasionally met with: 
 either a portion of the rim may be broken off, or a fracture may take place through the bottom 
 of the cavity, and the head of the femur may be driven inward and project into the pelvic cavity. 
 Separation of the Y-shaped cartilage at the bottom of the acetabulum may also occur in the 
 young subject, dispersing the bone into its three anatomical portions. 
 
 The sacrum is seldom broken. The cause is direct violence — i. e., blows, kicks, or falls 
 on the part. The lesion may be complicated with injury to the nerves of the sacral plexus, 
 leading to paralysis and loss of sensation in the lower extremity or to incontinence of fseces from 
 paralysis of the Sphincter ani. 
 
 The pelvic bones often undergo important deformity in rickets, the effect of which in the 
 adult woman may interfere seriously with childbearing. The deformity *is due mainly to the 
 weight of the spine and trunk, which presses on the sacro-vertebral angle and greatly increases 
 it, so that the antero-posterior diameter of the pelvis is diminished. But, in addition to this, 
 the weight of the viscera on the venter ilii causes those bones to expand and the tuberosities of 
 the ischia to incurve. In osteomalacia also great deformity may occur. The weight of the 
 trunk causes an increase in the sacro-vertebral angle and a lessening of the antero-posterior 
 diameter of the inlet, and at the same time the pressure of the acetabula on the heads of the 
 thigh-bones causes these cavities, with the adjacent bone, to be pushed upward and backward, 
 so that the oblique diameters of the pelvis are also diminished, and the cavity of the pelvis 
 assumes a triradiate shape, with the symphysis pubis pushed forward. 
 
 THE THIGH. 
 
 The thigh is that portion of the lower extremity which is situated between the 
 pelvis and the knee. It consists in the skeleton of a single bone, the femur. 
 
 The Femur, or Thigh Bone (Figs. 161, 162). 
 
 The femur (femur, the thigh) is the longest,^ largest, and strongest bone in the 
 skeleton, and almost perfectly cylindrical throughout the greater part of its extent. 
 In the erect posture it is not vertical, being separated from its fellow above by 
 a considerable interval, which corresponds to the entire breadth of the pelvis, but 
 inclining gradually downward and inward, so as to approach its fellow toward 
 its lower part, for the purpose of bringing the knee-joint near the line of gravity 
 of the body. The degree of this inclination varies in different persons, and 
 is greater in the female than the male, on account of the greater breadth of 
 the pelvis. The femur, like other long bones, is divisible into a shaft and two 
 extremities. 
 
 Upper Extremity. — The upper extremity presents for examination a head, 
 a neck, and a great and lesser trochanters. 
 
 Head of the Femur {caput femoris) .—The head, which is globular, and 
 forms rather more than a hemisphere, i^ directed upward, inward, and a little 
 
 ' Wood. Heath's Dictionary of Practical Surgery, i., 426. 
 
 2 In a man six feet high it measures eighteen inches — one-fourth of the whole body. 
 
222 
 
 THE SKELETON 
 
 OBTURATOR INTERNUS 
 and QEMELLI. 
 PVRIFORMIS. 
 
 ' Depression for 
 
 LIQAMENTUM TERES. 
 
 Fig. 161.— Right femur. 
 
 Anterior surface. 
 
 forward, the greater part of its 
 convexity being above and in front. 
 Its surface is smooth, coated with 
 cartilage in the recent state, ex- 
 cept at a Httle behind and below its centre, 
 where is an ovoid depression (fovea capitis 
 jemoris), for the attachment for the Ligamen- 
 tiim teres. 
 
 The Neck of the Femur (collum jemoris). — The 
 neck is a flattened pyramidal process of bone 
 which connects the head with the shaft. It 
 varies in length and obliquity at various periods 
 in life and under different circumstances. The 
 angle is widest in infancy, and becomes lessened 
 during growth, so that at puberty it forms a 
 gentle curve from the axis of the shaft. In the 
 adult it forms an angle of about 130 degrees 
 with the shaft, but varies in inverse proportion 
 to the development of the pelvis and the stature. 
 In consequence of the prominence of the hips 
 and widening of the pelvis in the female, the 
 neck of the thigh bone forms more nearly a right 
 angle with the shaft than it does in man. It has 
 been stated that the angle diminishes in old age 
 and the direction of the neck becomes hori- 
 zontal, but this statement is founded on insuffi- 
 cient evidence. Sir George Humphry states 
 that the angle decreases during the period of 
 growth, but after full growth has been attained 
 it does not usually undergo any change, even 
 in old age. He further states that the angle 
 varies considerably in different persons of the 
 same age. It is smaller in short than in long 
 bones, and when the pelvis is wide.^ The neck 
 is flattened from before backward, contracted in 
 the middle, and broader at its outer extremity, 
 where it is connected with the shaft, than at 
 its summit, where it is attached to the head. 
 The vertical diameter of the outer half is in- 
 creased by the thickening of the lower edge, 
 which slopes downward to join the shaft at the 
 lesser trochanter, so that the outer half of the 
 neck is flattened from before backward, and its 
 vertical diameter measures one-third more than 
 the antero-posterior. The inner half is smaller 
 and of a more circular shape. The anterior 
 surface of the neck is perforated by numerous 
 vascular foramina. The posterior surface is 
 smooth, and is broader and more concave than 
 the anterior; it gives attachment to the posterior 
 part of the capsular ligament of the hip-joint, 
 about half an inch above the posterior intertro- 
 chanteric line. The superior border is short and 
 
 ' Journal of Anatomy and Physiology. 
 
THE FEMUB, OB THIGH BONE 223 
 
 thick, and terminates externally at the great trochanter; its surface is perforated 
 by large foramina. The inferior border, long and narrow, curves a little back- 
 ward, to terminate at the lesser trochanter. 
 
 The Trochanters. — The trochanters (Tf)uydco, to run or roll) are prominent pro- 
 cesses of bone which afford leverage to the muscles which rotate the thigh on its 
 axis. They are two in number, the greater and the lesser. 
 
 The great trochanter (trochanter major) is a large, irregular, quadrilateral eminence, 
 situated at the outer side of the neck, at its junction with the upper part of the shaft. 
 It is directed a little outward and backward, and in the adult is about three-quarters 
 of an inch lower than the head. It presents for examination two surfaces and four 
 borders. The external surface, quadrilateral in form, is broad, rough, convex, and 
 marked by a prominent diagonal impression, which extends from the posterior 
 superior to the anterior inferior angle, and serves for the attachment of the tendon 
 of the Gluteus medius. Above the impression is a triangular surface, sometimes 
 rough for part of the tendon of the same muscle, sometimes smooth for the inter- 
 position of a bursa between that tendon and the bone. Below and behind the 
 diagonal line is a smooth, triangular surface, over which the tendon of the Gluteus 
 maximus muscle plays, a bursa being interposed. The internal surface is of much 
 less extent than the external, and presents at its base a deep depression, the digital 
 or trochanteric fossa (fossa trochanter ica) , for the attachment of the tendon of the 
 Obturator externus muscle: above and in front of this an impression for the attach- 
 ment of the Obturator internus and Gemelli. The superior border is free; it is thick 
 and irregular, and marked near the centre by an impression for the attachment of 
 the Pyriformis. The inferior border corresponds to the point of junction of the base 
 of the trochanter with the outer surface of the shaft; it is marked by a rough, promi- 
 nent, slightly curved ridge, which gives attachment to the upper part of the Vastus 
 externus muscle. The anterior border is prominent, somewhat irregular, as well 
 as the surface of bone immediately below it; it affords attachment at its outer 
 part to the Gluteus minimus. The posterior border is very prominent, and appears 
 as a free, rounded edge, which forms the back part of the digital fossa. 
 
 The lesser trochanter (trochanter minor) is a conical eminence which varies in size 
 in different subjects ; it projects from the lower and back parts of the base of the neck. 
 Its base is triangular, and connected with the adjacent parts of the bone by three 
 well-marked borders: two of these are above — the internal border, continuous with 
 the lower border of the neck, the external border with the posterior intertrochan- 
 teric line — while the inferior border is continuous with the middle division of the 
 linea aspera. Its summit, which is directed inward and backward, is rough, and 
 gives insertion to the tendon of the Ilio-psoas. The Iliacus is also inserted into 
 the shaft below the lesser trochanter between the Vastus internus in front and the 
 Pectineus behind. 
 
 A well-marked prominence of variable size, which projects from the upper and 
 front part of the neck at its junction with the great trochanter, is called the tuber- 
 cle of the femur; it is the point of meeting of five muscles: the Gluteus minimus 
 externally, the Vastus externus below, and the tendon of the Obturator internus 
 and Gemelli above. Running obliquely downward and inward from the tubercle 
 is the spiral line of the femur, or anterior intertrochanteric line (linea intertrochan- 
 terica); it winds round the inner side of the shaft, below the lesser trochanter, and 
 terminates in the linea aspera, about two inches below thi^ eminence. Its upper 
 half is rough, and affords attachment to the ilio-femoral ligament of the hip-joint; 
 its lower half is less prominent, and gives attachment to the upper part of the 
 Vastus internus. Running obliquely downward and inward from the summit of 
 the great trochanter on the posterior surface of the neck is a very prominent, 
 well-marked ridge, the posterior intertrochanteric line (crista intertrochanterica). 
 Its upper half forms the posterior border of the great trochanter, and its lower 
 
224 
 
 THE SKELETON 
 
 OBTURATOR EXTERNUS. 
 
 Groove for tendon of 
 
 POPLITEUS. 
 
 Fig. 162. — Right femur. Posterior surface. 
 
 half runs downward and inward 
 to the upper and back part of 
 the lesser trochanter, A slight 
 ridge sometimes commences about 
 the middle of the posterior inter- 
 trochanteric line, and passes ver- 
 tically downward for about two 
 inches along the back part of the 
 shaft: it is called the linea quadrati, 
 and gives attachment to the 
 Quadratus femoris and a few 
 fibres of the Adductor magnus. 
 muscles/ 
 
 The Shaft of the Femur {corpus 
 femoris) . — The shaft, almost cylin 
 drical in form, is a little broader 
 above than in the centre, and 
 somewhat flattened below, from 
 before backward. It is slightly 
 arched, so as to be convex in front 
 and concave behind, where it is. 
 strengthened by a prominent lon- 
 gitudinal ridge, the linea aspera 
 It presents for examination three 
 borders, separating three surfaces 
 Of the three borders, one, the linea 
 aspera, is posterior; the other two 
 are placed laterally. 
 
 The Linea Aspera. — The linea 
 aspera (Fig. 162) is a prominent 
 longitudinal ridge or crest, on the 
 middle third of the bone, present 
 ing an external lip (labium laterale) ,. 
 an internal lip {labium mediale), 
 and a rough intermediate space. 
 Above, this crest is prolonged by 
 three ridges. The most external 
 ridge is very rough, and is con 
 tinned almost vertically upward to- 
 the base of the great trochanter, 
 It is sometimes termed the gluteal 
 ridge {tuberositas glutoea) , and gives 
 attachment to part of the Gluteus 
 maximus muscle; its upper part is 
 sometimes elongated into a rough- 
 ened crest, on which is a more or 
 less well-marked, rounded tuber- 
 cle, a rudimental third trochanter 
 {trochanter tertius). The middle 
 ridge (linea pectinea) , the least dis- 
 
 1 Generally there is merely a slight thickening- 
 about the centre of the intertrochanteric line, 
 marking the point of attachment of the Quad- 
 ratus femoris. This is termed by some anato- 
 mists the tubercle of Uie Quadratus. 
 
 I 
 
THE FEMUR, OB THIGH BONE 225 
 
 tinct, is continued to the base of the trochanter minor, and the Internal ridge is 
 lost above in the spiral line of the femur. Below, the linea aspera is prolonged 
 by two ridges, which pass to the condyles and enclose between them a triangular 
 space, the popliteal surface (planum popliteum), upon which rests the popliteal 
 artery. Of these two ridges, the outer one is the more prominent, and descends 
 to the summit of the outer condyle. The inner one is less marked, especially at 
 its upper part, where it is crossed by the femoral artery. It terminates, below, 
 at the summit of the internal condyle, in a small tubercle, the adductor tubercle, 
 which affords attachment to the tendon of the Adductor magnus. To the inner 
 lip of the linea aspera and its inner prolongation above and below is attached 
 the Vastus internus, and to the outer lip and its outer prolongation above is 
 attached the Vastus externus. The Adductor magnus is attached to the linea 
 aspera, to its outer prolongation above and its inner prolongation below. Be- 
 tween the Vastus externus and the Adductor magnus are attached two muscles 
 — viz., the Gluteus maximus above, and the short head of the Biceps below. 
 Between the Adductor magnus and the Vastus internus four muscles are attached : 
 the Iliacus and Pectineus above, the Adductor brevis and Adductor longus below. 
 A little below the centre of the linea aspera is the nutrient foramen (foramen 
 nutricium), the orifice of the nutrient canal (canalis nutricius), which is directed 
 obHquely upward (proximally) . 
 
 Lateral Borders. — The two lateral borders of the femur are only slightly marked, 
 the outer one extending from the anterior inferior angle of the great trochanter 
 to the anterior extremity of the external condyle; the inner one from the spiral line 
 at a point opposite the trochanter minor, to the anterior extremity of the internal 
 condyle. The internal border marks the limit of attachment of the Crureus muscle 
 internally. 
 
 Anterior Surface. — The anterior surface includes that portion of the shaft which 
 is situated between the two lateral borders. It is smooth, convex, broader above 
 and below than in the centre, slightly twisted, so that its upper part is directed 
 forward and a little outward, its lower part forward and a little inward. To the 
 upper three-fourths of this surface the Crureus is attached; the lower fourth is 
 separated from the muscle by the intervention of the synovial membrane of the 
 knee-joint and a bursa, and affords attachment to the Subcrureus to a small extent. 
 
 External Surface. — The external surface includes the portion of bone between 
 the external border and the outer lip of the linea aspera : it is continuous above 
 with the outer surface of the great trochanter, below with the outer surface of 
 the external condyle ; to its upper three-fourths is attached the outer portion of 
 the Crureus muscle. 
 
 Internal Surface. — The internal surface includes the portion of bone between 
 the internal border and the inner hp of the linea aspera; it is continuous above 
 with the lower border of the neck, below with the inner side of the internal con- 
 dyle: it is covered by the Vastus internus muscle. 
 
 Lower Extremity. — The lower extremity, larger than the upper, is of a cuboid 
 form, flattened from before backward, and divided into two large eminences, 
 the condyles (condyli, from ;f6vrJu/oc, a knuckle), by an interval which presents a 
 smooth depression in front called the trochlea (fades patellaris) , and a notch of con- 
 siderable size behind — the intercondyloid notch (fossa intercondyloidea) . The exter- 
 nal condyle (condylus lateralis) is the more prominent anteriorly, and is the broader 
 both in the antero-posterior and transverse diameters. The internal condyle (con- 
 dylus medialis) is the narrower, longer, and more prominent inferiorly. This 
 difference in the length of the two condyles is only observed when the bone is 
 perpendicular and depends upon the obliquity of the thigh bones, in consequence 
 of their separation above at the articulation with the pelvis. If the femur is 
 held obliquely, the surfaces of the two condyles will be seen to be nearly hori- 
 
 15. 
 
226 
 
 THE SKELETON 
 
 zontal. The two condyles are directly continuous in front, and form a smooth, 
 trochlear surface, the trochlea, which articulates with the patella. It presents 
 a median groove, which extends downward and backward to the intercondyloid 
 notch; and two lateral convexities, of which the external is the broader, more 
 prominent, and prolonged farther upward upon the front of the outer condyle. 
 The external border of this articular surface is also more prominent, and ascends 
 higher than the internal one. The intercondyloid notch lodges the crucial liga- 
 ments ; it is bounded laterally by the opposed surfaces of the two condyles, and 
 in front by the lower end of the shaft. Between the popliteal surface and the I 
 floor of the intercondyloid notch is an elevation {linea intercondyloidea) , which i 
 affords attachment to the posterior ligament of the knee-joint. 
 
 Outer or External Condyle {condylus lateralis). — The outer surface of the external i 
 condyle presents, a little behind its centre, an eminence, the outer tuberosity {e'pi- 
 condylus lateralis) ; it is less prominent than the inner tuberosity, and gives attach- 
 ment to the external lateral ligaments of the knee. Immediately beneath it is a] 
 groove, the popliteal groove (sulcus popliieus), which commences at a depression a 
 little behind the centre of the lower border of this surface : the front part of this 
 depression gives origin to the Popliteus muscle, the tendon of which is lodged! 
 in the groove during flexion of the knee. The groove is smooth, covered with] 
 cartilage in the recent state, and runs upward and backward to the posterior 
 extremity of the condyle. The inner surface of the outer condyle forms one of 
 the lateral boundaries of the intercondyloid notch, and gives attachment, by its' 
 posterior part, to the anterior crucial ligament. The inferior surface is convex, 
 smooth, and broader than that of the internal condyle. The posterior extremity) 
 is convex and smooth: just above and to the outer side of the articular surface] 
 is a depression for the tendon of the outer head of the Gastrocnemius, above 
 which is the origin of the Plantaris. 
 
 Inner or Internal Condyle {condylus medialis) . — The inner surface of the inner | 
 condyle presents a convex eminence, the inner tuberosity (epicondylu^ medialis), 
 rough for the attachment of the internal lateral ligament. The outer side of the; 
 
 inner condyle forms one of the lateral bound- 
 aries of the intercondyloid notch, and gives 
 attachment, by its anterior part, to the posterior 1 
 crucial ligament. Its inferior or articular sur- 
 face is convex, and presents a less extensive 
 surface than the external condyle. Just above ' 
 the articular surface of the condyle, behind, 
 is a depression for the tendon of origin of the 
 inner head of the Gastrocnemius. 
 
 Structure. — The shaft of the femur is a 
 cylinder of compact tissue, hollowed by a 
 large medullary canal. The cylinder is of great 
 thickness and density in the middle third of 
 the shaft, where the bone is narrowest and the 
 medullary canal well formed; but above and 
 below this the cylinder gradually becomes 
 thinner, owing to a separation of the layers of 
 the bone into cancelli, which project into the 
 medullary canal and finally obliterate it, so 
 that the upper and lower ends of the shaft, and 
 the articular extremities more especially, consist of cancellated tissue invested 
 by a thin, compact layer. 
 
 The arrangement of the cancelli in the ends of the femur is remarkable. In 
 the upper end they are arranged in two sets. One, starting from the top of the 
 
 Tension Pressure 
 planes. planes 
 
 Fig. 163. — Diagram showing the arrangement 
 of the bone-fibres of the neck of the femur. 
 
THE FEMUB^ OB THIGH BONE 227 
 
 head, the upper surface of the n( < Is, and the great trochanter, converge to the inner 
 circumference of the shaft (Figs. 163 and 164); these are placed in the direction of 
 greatest pressure, and serve to support the vertical weight of the body. The second 
 set are planes of lamellfe intersecting the former nearly at right angles, and are 
 
 Fig. 164. — Right femur, upper extremity, ground frontal section, from in front. (Spalteholz.) 
 
 situated in the line of the greatest tension — that is to say, along the lines in which 
 the muscles and ligaments exert their traction. In the head of the bone these 
 planes are arranged in a curv^ed form, in order to strengthen the bone when exposed 
 to pressure in all directions. In the midst of the cancellous tissue of the neck is 
 a vertical plane of compact bone, the femoral spur {calcar femorale), which com- 
 
228 
 
 THE SKELETON 
 
 mences at the point where the neck joins the shaft midway between the lesser 
 trochanter and the internal border of the shaft of the bone, and extends in the 
 direction of the digital fossa (Fig. 165). This materially strengthens this portion 
 of the bone. Another point in connection with the structure of the neck of the 
 femur requires mention, especially on account of its influence on the productionjij 
 of fracture in this situation. It will be noticed that a considerable portion of the «l 
 great trochanter lies behind the level of the posterior surface of the neck; and if a 
 section be made through the trochanter at this level, it will be seen that the pos- 
 terior wall of the neck is prolonged into the trochanter. This prolongation is 
 termed by Bigelow the true neck,^ and forms a thin, dense plate of bone, which 
 passes beneath the posterior intertrochanteric ridge toward the outer surface of 
 the bone. In the lower end the cancelli spring on all sides from the inner surface 
 of the cyUnder, and descend in a perpendicular direction to the articular surface, 
 
 Great trochanter. 
 
 _ Digital fossa. 
 
 Appears at ^th 
 year; joins shaft ■^ 
 about 18th year. 
 
 Appears at 
 9th month 
 (fatal). 
 
 Appears at end 
 of 1st year ; 
 
 joins shaft about 
 18th year. 
 
 £ Appears ISth-lJ^th year ; 
 5- joins shaft about 18th 
 
 Joins shaft at 20th 
 year. 
 
 Fig. 165. — Calcar femorale. 
 
 Lower extremity. 
 
 Fig. 166. — Plan of the development of the femur, 
 five centres. 
 
 the cancelli being strongest and having a more accurately perpendicular course 
 above the condyles. In addition to this, however, horizontal planes of cancellous 
 tissue are to be seen, so that the spongy tissue in this situation presents an appear*] 
 ance of being mapped out into a series of rectangular areas. 
 
 Articulations. — With three bones: the os innominatum, tibia, and patella. 
 
 Development (Fig. 166). — The femur is developed by five centres: one for th| 
 shaft, one for each extremity, and one for each trochanter. Of all the long bonesi 
 except the clavicle, it is the first to show traces of ossification : this commences ii 
 the shaft, at about the seventh week of foetal life, the centres of ossification in th^ 
 epiphyses appearing in the following order: First, in the lower end of the bonej 
 at the ninth month of foetal life^ (from this the condyles and tuberosities ai 
 
 1 Bigelow on the Hip, p. 121. 
 
 * This is said to be the only epiphysis in which cssification begins before birth; though according to som^ 
 observers, the centre for the upper epiphysis of the tibia also appears before birth. 
 
THE FEMUB, OB THIGH BONE 229 
 
 formed); in the head at the end of the first year after birth; in the great tro- 
 chanter, during the fourth year; and in the lesser trochanter, between the thir- 
 teenth and fourteenth. The order in which the epiphyses are joined to the shaft 
 is the reverse of that of their appearance: their junction does not commence until 
 after puberty, the lesser trochanter being first joined, then the great, then the 
 head, and, lastly, the inferior extremity (the first in Avhich ossification commenced), 
 which is not united until the twentieth year. 
 
 Attachment of Muscles. — To twenty-three. To the great trochanter: the Glu- 
 teus medius. Gluteus minimus, Pyriformis, Obturator internus. Obturator externus, 
 Gemellus superior. Gemellus inferior, and Quadratus femoris. To the lesser 
 trochanter: the Psoas magnus and the Iliacus below it. To the shaft: the Vastus 
 externus. Gluteus maximus, short head of the Biceps, Vastus internus, Adductor 
 magnus, Pectineus, Adductor brevis. Adductor longus, Crureus, and Subcrureus. 
 To the condyles: the Gastrocnemius, Plantaris, and Popliteus. 
 
 Surface Form. — The femur is covered with muscles, so that in fairly muscular subjects the 
 shaft is not to be detected through its fleshy covering, and the only parts accessible to the touch 
 are the outer surface of the great trochanter and the lower expanded end of the bone. The 
 external surface of the great trochanter is to be felt, especially in certain positions of the limb. Its 
 position is generally indicated by a depression, owing to the thickness of the Gluteus medius and 
 minimus, which project above it. When, however, the thigh is flexed, and especially if crossed 
 over the opposite one, the trochanter produces a blunt eminence on the surface. The upper 
 border is about on a line with the spine of the os pubis, and its exact level is indicated by a 
 line drawn from the anterior superior spinous process of the ilium, over the outer side of the 
 hip, to the most prominent point of the tuberosity of the ischium. This is known as Nelaton's 
 line. The outer and inner condyles of the lower extremity are easily to be felt. The outer one 
 is more subcutaneous than the inner one and readily felt. The tuberosity on it is comparatively 
 little developed, but can be more or less easily recognized. The inner condyle is more thickly 
 covered, and this gives a general convex outline to this part, especially when the knee is flexed. 
 The tuberosity on it is easily felt, and at the upper part of the condyle the sharp tubercle for the 
 insertion of the tendon of the Adductor magnus can be recognized without difficulty. When 
 the knee is flexed, and the patella situated in the interval between the condyles and the upper 
 end of the tibia, a part of the trochlear surface of the femur can be made out above the patella. 
 
 Surgical Anatomy. — There are one or two points about the ossification of the femur bear- 
 ing on practice to which allusion must be made. It has been stated above that the lower end 
 of the femur is the only epiphysis in which ossification has commenced at the time of birth. 
 The presence of the ossific centre in newly born children found dead is, therefore, a proof 
 that the child has arrived at the full period of utero-gestation, and is always relied upon in 
 medico-legal investigations. The position of the epiphysial line should be carefully noted. It 
 is on a level with the adductor tubercle, and the epiphysis does not, therefore, form the whole 
 of the cartilage-clad portion of the lower end of the bone. It is essential to bear this point in 
 mind in performing excision of the knee, since growth in length of the femur takes place chiefly 
 from the lower epiphysis, and any interference with the epiphysial cartilage in a young child 
 would involve such ultimate shortening of the limb, from want of growth, as to render it almost 
 useless. Separation of the lower epiphysis may take place up to the age of twenty, at which 
 time it becomes completely joined to the shaft of the bone; but, as a matter of fact, few cases 
 occur after the age of sixteen or seventeen. The epiphysis of the head of the femur is of interest 
 principally on account of its being the seat of origin of a large number of cases of tuberculous 
 disease of the hip-joint. The disease commences in the majority of cases in the highly vascular 
 and growing tissue in the neighborhood of the epiphysis, and from here extends into the joint. 
 In the condition known as coxa vara the head of the femur falls to a lower level than normal. 
 The angle between the neck and shaft is greatly diminished and may become a right angle or 
 the head may actually descend to a lower level than that of the trochanter. The neck is also 
 bent with a convexity forward; coxa vara is due to rickets. 
 
 Fractures of the femur are divided, like those of the other long bones, into fractures of the 
 upper end; of the shaft; and of the lower end. The fractures of the upper end may be classi- 
 fied into (1) fracture of the neck; (2) fracture at the junction of the neck with the great trochanter; 
 (3) fracture of the great trochanter; and (4) separation of the epiphysis, either of the head or 
 of the great trochanter. The first of these, fracture of the neck, is usually termed intracapsular 
 fracture, but this is scarcely a correct designation, as owing to the attachment of the capsular 
 ligament, the fracture may be partly within and partly without the capsule, when the fracture 
 occurs at the lower part of the neck. It generally occurs in old people, principally women, and 
 usually from a very slight degree of indirect violence. Probably the main cause of the fracture 
 
230 THE SKELETON 
 
 taking place in old people is in consequence of the degenerative changes which the bone has 
 undergone. Merkel believes that it is mainly due to the absorption of the calcar femorale. 
 These fractures are occasionally impacted. As a rule they unite by fibrous tissue, and frequently 
 no union takes place, and the surfaces of the fracture become smooth and eburnated. The 
 lack of reparative power in intracapsular fracture is due to lack of apposition of the fragments and 
 diminution in the amount of blood sent to the smaller fragment. The head of the bone receives 
 blood from the neck through the reflected portions of the capsule and through the Ligamentum 
 teres. A fracture cuts off the supply by the neck and by the reflected portions of the capsule. 
 
 Fractures at the junction of the neck with the great trochanter are usually termed extra- 
 capsular, but this designation is also incorrect; as the fracture is partly within the capsule, 
 owing to its attachment in front to the anterior intertrochanteric line, which is situated below 
 the line of fracture. These fractures are produced by direct violence to the great trochanter, as 
 from a blow or fall laterally on the hip. From the manner in which the accident is caused, the 
 neck of the bone is driven into the trochanter, where it may remain impacted or the trochanter 
 may be split up into two or more fragments, and thus no fixation takes place. 
 
 Fractures of the great trochanter may be either "oblique fracture through the trochanter 
 major, without implicating the neck of the bone" (Astley Cooper), or seyjaration of the great 
 trochanter. Most of the recorded cases of this latter injury occurred in young persons, and 
 were probably cases of separation of the epiphysis of the great trochanter. Separation of the 
 epiphysis of the head of the femur has been said to occur, but has probably never been verifii 
 by post-mortem examination. 
 
 Fractures of the shaft may occur at any part, but the most usual situation is at or near th( 
 centre of the bone. They may be caused by direct or indirect violence or by muscular action. 
 Fractures of the upper third of the shaft are almost always the result of indirect violence, whilst 
 those of the lower third are the result, for the most part, of direct violence. In the middle third 
 fractures occur from both forms of injury in about equal proportions. Fractures of the shaft 
 are generally oblique, but they may be transverse, longitudinal, or spiral. The transverse 
 fracture occurs most frequently in children. The fractures of the lower end of the femur include 
 transverse fracture above the condyles, the most common; and this may be complicated by a 
 vertical fracture between the condyles, constituting the T-shaped fracture. In these cases the 
 popliteal artery is in danger of being wounded. Oblique fracture, separating either the internal 
 or external condyle, and a longitudinal incomplete fracture between the condyles, may also tak 
 place. 
 
 The femur and also the bones of the leg are frequently the seat of acute osteomyelitis in younj^ 
 children. This is no doubt due to their greater exposure to injury, which is often the exciting 
 cause of this disease. Tumors not unfrequently are found growing from the femur: the most 
 common forms being sarcoma, which may grow either from the periosteum or from the medullary 
 tissue within the interior of the bone; and exostosis, which is commonly found originating in 
 the neighborhood of the epiphysial cartilage of the lower end. 
 
 Genu varum is a form of bow-leg in which the tibia and femur are curved outward, the knee: 
 being widely separated. Both extremities are usually affected. In early life the disease is due 
 to rickets. In elderly people it may be due to arthritis deformans. Genu valgum (knock-knee) 
 is a condition in which the knees are close together, the feet are wide apart, and the internal 
 lateral ligament of the knee-joint is stretched. It is due to excessive growth of the inner con- 
 dyle of the femur, the shaft of the femur curving inward. It may be due to rickets, attitude o: 
 an occupation, or flat-foot, and one or both knees may be affected. 
 
 THE LEG. 
 
 The skeleton of the leg consists of three bones: the patella, a large sesamoic 
 bone, placed in front of the knee; the tibia; and the fibula. 
 
 The Patella, or Knee-cap (Figs. 167, 168). 
 
 The patella (patella, a small pan), the knee-cap or knee-pan, is a flat, triangularl 
 bone, situated at the anterior part of the knee-joint. It is usually regarded as a| 
 sesamoid bone, developed in the tendon of the Quadriceps extensor. It resembles] 
 these bones (1) in its being developed in a tendon; (2) in its centre of ossification 
 presenting a knotty or tuberculated outline; (3) in its structure being composed; 
 mainly of dense cancellous tissue, as in the other sesamoid bones. It serves to I 
 protect the front of the joint, and increases the leverage of the Quadriceps extensor 
 by making it act at a greater angle. It presents an anterior and a posterior sur-J 
 face, three borders, and an apex. 
 
 I 
 
 I 
 
 it 
 
 I 
 
THE PATELLA, OB KNEE-CAP 
 
 231 
 
 Fig. 167.— Right patella. 
 Anterior surface. 
 
 Fig. 168.— Right patella. 
 Posterior surface. 
 
 Surfaces. Anterior Surface. — The anterior surface is convex, perforated by 
 small apertures, for the passage of nutrient vessels, and marked by numerous 
 rough, longitudinal striie. This surface is covered, in the recent state, by an 
 e.xpansion from the tendon of 
 the Quadriceps extensor, which 
 is continuous below with the 
 superficial fibres of the liga- 
 mentum patellae. It is sepa- 
 rated from the integument Ly 
 a bursa. 
 
 Posterior Surface. — The pos- 
 terior surface presents a 
 smooth, oval-shaped, articular 
 surface {fades articularis) , cov- 
 ered with cartilage in the re- 
 cent state, and divided into two facets by a vertical ridge, which descends from 
 the superior border toward the inferior angle of the bone. The ridge corresponds 
 to the groove on the trochlear surface of the femur, and the two facets to the 
 articular surfaces of the two condyles ; the outer facet, for articulation with the 
 outer condyle, being the broader and deeper. This character serves to indicate 
 the side to which the bone belongs. Below the articular surface is a rough, convex, 
 non-articular depression, the lower half of which gives attachment to the liga- 
 mentum patellae, the upper half being separated from the head of the tibia by 
 adipose tissue. 
 
 Borders. Superior Border. — The superior border (basis patelloB) is thick, and 
 sloped from behind, downward and forward: it gives attachment to that portion 
 of the Quadriceps extensor which is derived from the Rectus and Crureus muscles. 
 
 Lateral Borders. — The lateral borders are thinner, converging below. They 
 give attachment to that portion of the Quadriceps extensor derived from the 
 external and internal Vasti muscles. 
 
 The Apex (apex patellce). — The apex is pointed, and gives attachment to the 
 ligamentum patellae. 
 
 Structure. — It consists of a nearly uniform, dense cancellous tissue covered 
 by a thin compact lamina. The cancelli immediately beneath the anterior surface 
 are arranged parallel with it. In the rest of the bone they radiate from the pos- 
 terior articular surface toward the other parts of the bone. 
 
 Development. — By a single centre, which makes its appearance, according to 
 B^clard, about the third year. In two instances Mr. Pick haS seen this bone car- 
 tilaginous throughout, at a much later period (six years). More rarely, the bone is 
 developed by two centres, placed side by side. Ossification is completed about 
 the age of puberty. ;. 
 
 Articulations. — With the two condyles of the femur. 
 
 Attachment of Muscles. — To four: the Rectus, Crureus, Vastus internus, and 
 Vastus externus. These muscles, joined at their insertion, constitute the Quadri- 
 ceps extensor cruris. 
 
 Surface Form. — The external surface of the patella can be seen and felt Jn front of the 
 knee. In the extended position of the limb the internal border is a little more prominent than 
 the outer, and if the Quadriceps extensor is relaxed the bone can be moved from side to side and 
 appears to be loosely fixed. If the joint is flexed, the patella recedes into the hoUox^ between the 
 condyles of the femur and the upper end of the tibia, and becomes firmly fixed against the femur. 
 
 Surgical Anatomy. — The main surgical interest about the patella is in connection with 
 fractures, which are of common occurrence. They may be produced by muscular action; that 
 IS to say, by violent contraction of the Quadriceps extensor while the limb is in a position of 
 semi-flexion, so that the bone is snapped across the condyles; or by direct violence, such as 
 
232 
 
 THE SKELETON 
 
 Head. 
 
 Styloid process. 
 
 Tibia. 
 
 ^rticulrt^"". 
 
 Internal malleolus. 
 External malleolus. 
 
 Fig. 169. — Bones of the right leg. Anterior surface. 
 
 Styloid proces. 
 
 Fibula. 
 
 Fig. 170. — Bones of the right leg. Posterior surface. 
 
THE TIBIA, OR SHIN BONE 233 
 
 falls on the knee. Most fractures are due to muscular action ; in fact, the patella is more often 
 broken by muscular action than is any other bone. In fractures by muscular action the line of 
 fracture is transverse. In fractures by direct force the line of fractuure may be oblique, longi- 
 tudinal, stellate, or the bone variously comminuted. The principal interest in these cases 
 attaches to their treatmennt. Owing to the wide separation of the fragments, and the diffi- 
 culty there is in maintaining them in apposition, union takes place by fibrous tissue, and this 
 may subsequently stretch, producing wide separation of the fragments and permanent lame- 
 ness. Various plans, including opening the joint and suturing the fragments, have been advo- 
 cated for overcoming this difficulty. In many cases a portion of fascia or capsule gets between 
 the fragments. In such a condition operation is necessary. 
 
 In the larger number of cases of fracture of the patella the knee-joint is involved, the car- 
 tilage which covers its posterior surface being torn, the synovial membrane lacerated, the lateral 
 fibrous expansions ruptured, and the patellar bursa torn open. In cases of fracture from 
 direct violence, however, this need not necessarily happen, the lesion may involve only the 
 superficial part of the bone; and, as Morris has pointed out, it is an anatomical possibility, in 
 complete fracture, if the lesion involve only the lower and non-articular part of the bone, for 
 it to take place without injury to the synovial membrane. 
 
 The Tibia, or Shin Bone (Figs. 169, 170). 
 
 The tibia {tibia, a flute or pipe) is situated at the front and inner side of the 
 leg, and, excepting the femur, is the longest and largest bone in the skeleton. It 
 is prismoid in form, expanded above, where it enters into the knee-joint, more 
 slightly enlarged below. In the male its direction is vertical and parallel with 
 the bone of the opposite side; but in the female it has a slightly oblique direction 
 downward and outward, to compensate for the oblique direction of the femur 
 inward. It presents for examination a shaft and two extremities. 
 
 Upper Extremity. — The upper extremity, or head, is large, and expanded 
 on each side into two lateral eminences, the internal and external tuberosities 
 (condylus medialis and condylus lateralis). Superiorly, each tuberosity presents 
 a smooth, concave surface (fades articularis superior), which articulates with 
 
 ATTACHMENT OF POSTERIOR __,_,„ „_ po-TroinB ATTACHMENT OF POSTERIOR 
 
 EXTREMITY OF EXTERNAL i^ ^T^ " EXTR EM ITY OF I NTERN AL 
 
 SEMILUNAR CARTILAGE ,.-,,- 'V ,""^Z^, SEMI LUNAR CARTI LAGC 
 
 ATTACHMENT OF ANTERIOR^ ooiPiM nr .mtc- ^ATTACHMENT OF ANTERIOR 
 
 EXTREMITY OF EXTERNAL „,„''„ °^*Jo\j., EXTREM ITY OF INTERN AL 
 
 SEMILUNAR CARTILAGE """," EATERIMAL SEMILUNAR CARTILAGE 
 
 Fig. 171. — Upper articular surface of the tibia, showing the attachments of the ligaments. 
 
 (Poirier and Charpy.) 
 
 a condyle of the femur. The internal, articular surface is longer, deeper, and 
 narrower than the external, oval from before backward, to articulate with the in- 
 ternal condyle; the external one is broader and more circular, concave from side 
 to side, but slightly convex from before backward^especially at its posterior part, 
 where it is prolonged on to the posterior surface for a short distance, to articulate 
 with the external condyle. Between the two articular surfaces, and nearer the pos- 
 terior than the anterior aspect of the bone, is an eminence, the spinous process 
 of the tibia (eminentia intercondyloidea) ; surmounted by a prominent tubercle on 
 each side (the tuberculum intercondyloideum mediale and the tuherculum inter- 
 condyloideum laterale), on to the lateral aspect of which the facets just described 
 are prolonged; in front and behind the spinous process is a rough depression 
 
234 'J^HE SKELETON 
 
 (fossa intercondyloidea anterior and the fossa inter condyloidea ^posterior) for the 
 attachment of the anterior and posterior crucial Ugaments and the semilunar 
 fibro-cartilages (Fig. 171). 
 
 The anterior surfaces of the tuberosities are continuous with one another, form- 
 ing a single large surface, which is somewhat flattened: it is triangular, broad 
 above, and perforated by large vascular foramina; narrow below, where it ter- 
 minates in a prominent oblong elevation of large size, the tubercle of the tibia , 
 {tuberositas tibce); the lower half of this tubercle is rough, for the attachment of ■! 
 the ligamentum patellae; the upper half presents a smooth facet supporting, in the 
 recent state, a bursa which separates the ligament from the bone. Posteriorly the 
 tuberosities are separated from each other by a shallow depression, the popliteal 
 notch (incisura poplitea), which gives attachment to part of the posterior crucial 
 ligament and part of the posterior ligament of the knee-joint. The inner tuberosity 
 presents posteriorly a deep transverse groove, for the insertion of one of the fas- 
 ciculi of the tendon of the Semi-membranosus. Its lateral surface is convex, 
 rough, and prominent, and gives attachment to the internal lateral ligament. The 
 outer tuberosity presents posteriorly a flat articular facet (fades articular is fibularis), 
 nearly circular in form, directed downward, backward, and outward, for articu- 
 lation with the fibula. Its lateral surface is convex and rough, more prominent 
 in front than the internal, and presents a prominent rough eminence, situated on 
 a level with the upper border of the tubercle of the tibia at the junction of its 
 anterior and outer surfaces, for the attachment of the ilio-tibial band. Just below 
 this the Extensor longus digitorum and a slip from the Biceps are attached. The 
 infraglenoid margin (margo infraglenoidalis) is at the outer edge of the superior 
 articular surface. From this point the bone rapidly narrows distally. 
 
 Shaft of the Tibia (corpus tibice). — The shaft of the tibia is of a triangular 
 prismoid form, broad above, gradually decreasing in size to its most slender part, 
 at the commencement of its lower fourth, where fracture most frequently occurs; 
 it then enlarges again toward its lower extremity. It presents for examination 
 three borders and three surfaces. 
 
 Anterior Border. — ^The anterior border, the most prominent of the three, is 
 called the crest of the tibia (crista anterior), or, in popular language, the shin; it 
 commences above at the tubercle, and terminates below at the anterior margin 
 of the inner malleolus. This border is very prominent in the upper two-thirds of 
 its extent, smooth and rounded below. It presents a very flexuous course, being 
 usually curved outward above and inward below; it gives attachment to the 
 deep fascia of the leg. 
 
 Internal Border (margo medialis) . — ^The internal border is smooth and rounded 
 above and below, but more prominent in the centre; it commences at the back 
 part of the inner tuberosity, and terminates at the posterior border of the inter- 
 nal malleolus; its upper part gives attachment to the internal lateral ligament of 
 the knee to the extent of about two inches, and to some fibres of the Fopliteus 
 muscle, and its middle third to some fibres of the Soleus and Flexor longus 
 digitorum muscles. 
 
 External Border (crista interossea). — The external border, or interosseous ridge, 
 is thin and prominent, especially its central part, and gives attachment to the 
 interosseous membrane; it commences above in front of the fibular articular facet, 
 and bifurcates below, to form the boundaries of a triangular rough surface, for 
 the attachment of the interosseous ligament connecting the tibia and fibula. 
 
 Internal Surface (fades medialis). — The internal surface is smooth, convex^ 
 and broader above than below; its upper third, directed forward and inward, is 
 covered by the aponeurosis derived from the tendon of the Sartorius, and by the 
 tendons of the Gracilis and Semitendinosus, all of which are inserted nearly as 
 far forward as the anterior border; in the rest of its extent it is subcutaneous. 
 
THE TIBIA, OB SHIN BONE 235 
 
 External Surface (fades lateralis). — The external surface is narrower than the 
 internal; its upper two-thirds presents a shallow groove for the attachment of 
 the Tibialis anticus muscle; its lower third is smooth, convex, curves gradually 
 forward to the anterior aspect of the bone, and is covered from within outward by 
 the tendons of the following muscles: Tibialis anticus. Extensor proprius hallucis, 
 Extensor longus digitorum. 
 
 Posterior Surface (fades posterior). — The posterior surface (Fig. 170) presents, 
 at its upper part, a prominent ridge, the popliteal line or the oblique line of the 
 tibia (linea poplitea), which extends from the back part of the articular facet 
 for the fibula obliquely downward, to the internal border, at the junction of 
 its upper and middle thirds. It marks the lower limit for the insertion of the 
 Popliteus muscle, and serves for the attachment of the popliteal fascia and part 
 of the Soleus, Flexor longus digitorum, and Tibialis posticus muscles; the tri- 
 angular concave surface, above and to the inner side of this line, gives attach- 
 ment to the Popliteus muscle. The middle third of the posterior surface is 
 divided by a vertical ridge into tAvo lateral halves: the ridge is well marked at 
 its commencement at the oblique Hne, but becomes gradually indistinct below; 
 the inner and broader half gives attachment to the Flexor longus digitorum, the 
 outer and narrower to part of the Tibialis posticus. The remaining part of the 
 bone presents a smooth surface covered by the Tibialis posticus, Flexor longus 
 digitorum, and Flexor longus hallucis muscles. Immediately below the oblique 
 line is the nutritive foramen (foramen nutridum), which is large and directed 
 obliquely downward. It is the opening of the nutrient canal, which is directed 
 toward the periphery. 
 
 Lower Extremity. — The lower extremity, much smaller than the upper, 
 presents five surfaces; it is prolonged downward, on its inner side, to a strong 
 process, the internal malleolus (malleolus medialis) . 
 
 Inferior Surface (fades articularis inferior). — The inferior surface of the bone 
 is quadrilateral, and smooth for articulation with the astragalus. This surface 
 is concave from before backward, and broader in front than behind. It is trav- 
 ersed from before backward by a slight elevation, separating two lateral depres- 
 sions. It is narrow internally, where the articular surface becomes continuous 
 with that on the inner malleolus (fades articularis malleolaris) . 
 
 Anterior Surface. — The anterior surface of the lower extremity is smooth and 
 rounded above, and covered by the tendons of the Extensor muscles of the toes; 
 its lower margin presents a rough transverse depression, for the attachment of 
 the anterior ligament of the ankle-joint. 
 
 Posterior Surface. — The posterior surface presents a superficial groove directed 
 obliquely downward and inward, continuous with a similar groove on the posterior 
 surface of the astragalus, and serving for the passage of the tendon of the Flexor 
 longus hallucis. 
 
 External Surface. — The external surface presents a triangular rough depression 
 for the attachment of the interior interosseous ligament, connecting it with the 
 fibula; the lower part of this depression, the fibular notch (incisura fibularis), is 
 smooth, covered with cartilage in the recent state, and articulates with the fibula. 
 This surface is bounded by two prominent borders, continuous above with the 
 interosseous ridge; they afford attachment to the anterior inferior and posterior 
 inferior tibio-fibular ligaments. 
 
 Internal Smrface. — The internal surface of the lower extremity is prolonged 
 downward to form a strong pyramidal process, flattened from without inward — 
 the internal malleolus (malleolus medialis). The inner surface of this process is 
 convex and subcutaneous; its outer surface is smooth and slightly concave, and 
 articulates with the astragalus; its anterior border is rough, for the attachment of 
 the anterior fibres of the internal lateral or Deltoid ligament; its posterior border 
 
236 
 
 THE SKELETON 
 
 Upper extremity. 
 
 Appears at. 
 birth. 
 
 ,Johis shaft about 
 20th year. 
 
 presents a broad and deep groove (sulcus malleolaris) , directed obliquely down- 
 ward and inward, which is occasionally double: this groove transmits the tendons 
 of the Tibialis posticus and Flexor longus digitorum muscles. The summit of the 
 internal malleolus is marked by a rough depression behind, for the attachment of 
 the internal lateral ligament of the ankle-joint. 
 
 Structure. — Like that of the other long bones. At the junction of the middle 
 
 and lower third, where the bone is smallest, the wall of the shaft is thicker than 
 
 in other parts, in order to compensate for the smallness of the calibre of the bone. 
 
 Development. — By three centres (Fig. 172): one for the shaft and one for 
 
 each extremity. Ossification commences in the centre of the shaft about the 
 
 seventh week, and gradually extends to- 
 ward either extremity. The centre for 
 the upper epiphysis appears before or 
 shortly after birth; it is flattened in form, 
 and has a thin, tongue-shaped process in 
 front which forms the tubercle. That 
 for the lower epiphysis appears in the 
 second year. The lower epiphysis joins 
 the shaft at about the eighteenth, and 
 the upper one about the twentieth year. 
 Two additional centres occasionally exist 
 — one for the tongue-shaped process of 
 the upper epiphysis, which forms the 
 tubercle, and one for the inner malleolus. 
 Articulations. — With three bones : the 
 femur, fibula, and astragalus. 
 
 Attachment of Muscles. — To twelve: 
 to the inner tuberosity, the Semimem- 
 branosus; to the outer tuberosity, the 
 Tibialis anticus and Extensor longus digi- 
 torum and Biceps; to the shaft, its in- 
 ternal surface, the Sartorius, Gracilis, and 
 Semitendinosus; to its external surface, 
 the Tibialis anticus; to its posterior sur- 
 face, the Pppliteus, Soleus, Flexor longus 
 digitorum, and Tibiahs posticus; to the 
 tubercle, the ligamentum patellae, by which the Quadriceps extensor muscle is 
 inserted into the tibia. In addition to these muscles, the Tensor fasciae femoris is 
 inserted indirectly into the tibia, through the ilio-tibial band, and the Peroneus 
 longus occasionally derives a few fibres of origin from the outer tuberosity. 
 
 Surface Form. — A considerable portion of the tibia is subcutaneous and easily to be felt. 
 At the upper extremity the tuberosities are to be recognized just below the knee. The internal 
 one is broad and smooth, and merges into the subcutaneous surface of the shaft below. The 
 external one is narrower and more prominent, and on it, about midway between the apex of the 
 patella and the head of the fibula, may be felt a prominent tubercle for the insertion of the illo- 
 tibial band. In front of the upper erid of the bone, between the tuberosities, is the tubercle of 
 the tibia, forming an oval eminence which is continuous below with the anterior border or crest 
 of the bone. This border can be felt, forming the prominence of the shin, in the upper two- 
 thirds of its extent as a sharp and flexuous ridge, curved outward above and inward below. In 
 the lower third of the leg the border disappears, and the bone is concealed by the tendons of 
 the muscles on the front of the leg. Internal to the anterior border is to be felt the broad 
 internal surface of the tibia, slightly encroached upon by the muscles in front and behind. It 
 commences above at the wide expanded inner tuberosity, and terminates below at the internal 
 malleolus. The internal malleolus is a broad prominence situated on a higher level and some- 
 what farther forward than the external malleolus. It overhangs the inner border of the arch 
 of the foot. Its anterior border is nearly straight; its posterior border presents a sharp edge 
 which forms the inner margin of the groove for the tendon of the Tibialis posticus muscle. 
 
 Appears at 2nd^ 
 year. 
 
 Joins shaft about 
 18th year. 
 
 Lower extremity. 
 
 Fig. 172.- 
 
 -Plan of the development of the tibia. 
 By tiiree centres. 
 
THE FIBULA, OR CALF BONE 237 
 
 The Fibula, or Calf Bone (Figs. 169, 170). 
 
 The fibula (fibula, a clasp) is situated at the outer side of the leg. It is the 
 smaller of the two bones, and, in proportion to its length, the most slender of all 
 the long bones; it is placed on the outer side of the tibia, with which it is con- 
 nected above and below. Its upper extremity is small, placed toward the back of 
 the head of the tibia and below the level of the knee-joint, and excluded from its 
 formation; the lower extremity inclines a little forward, so as to be on a plane 
 anterior to that of the upper end, projects below the tibia, and forms the outer 
 ankle. It presents for examination a shaft and two extremities. 
 
 Upper Extremity. — The upper extremity, or head (capitulum fibulce), is of 
 an irregular quadrate form, presenting above a flattened articular facet, directed 
 upward, forward, and inward, for articulation with a corresponding facet on the 
 external tuberosity of the tibia. On the outer side is a thick and rough promi- 
 nence, continued behind into a pointed eminence, the styloid process of the fibula. 
 (apex capituli fibulce), which projects upward from the posterior part of the 
 head. The prominence gives attachment to the tendon of the Biceps muscle 
 and to the long external lateral ligament of the knee, the ligament dividing the 
 tendon into two parts. The summit of the styloid process gives attachment to 
 the short external lateral ligament. The remaining part of the circumference of the 
 head is rough, for the attachment of muscles and ligaments. It presents in front 
 a tubercle for the origin of the upper and anterior part of the Peroneus longus, and 
 the adjacent surface gives attachment to the anterior superior tibio-fibular liga- 
 ment; and behind, another tubercle for the attachment of the posterior superior 
 tibio-fibular ligament and the upper fibres of the Soleus muscle. 
 
 Shaft of the Fibula (corpus fibulce). — The shaft presents four borders — 
 the antero-external, the antero-internal, the postero-external, and the postero- 
 internal; and four surfaces — anterior, posterior, internal, and external. 
 
 Antero-external Border (crista anterior). — The antero-external border commences 
 above in front of the head, runs vertically downward to a little below the middle of 
 the bone, and then, curving somewhat outward, bifurcates so as to embrace the 
 triangular subcutaneous surface immediately above the outer surface of the exter- 
 nal malleolus. This border gives attachment to an intermuscular septum, which 
 separates the extensor muscles on the anterior surface of the leg from the Peroneua 
 longus and brevis muscles on the outer surface. 
 
 Antero-intemal Border (crista interossea) . — The antero-internal border, or inter- 
 osseous ridge, is situated close to the inner side of the preceding, and runs nearly 
 parallel with it in the upper third of its extent, but diverges from it so as to 
 include a broader space in the lower two-thirds. It commences above, just 
 beneath the head of the bone (sometimes it is quite indistinct for about an 
 inch below the head), and terminates below at the apex of a rough triangular 
 surface inmiediately above the articular facet of the external malleolus. It serves 
 for the attachment of the interosseous membrane, which separates the extensor 
 muscles in front from the flexor muscles behind. 
 
 Postero-external Border (crista lateralis) . — The postero-external border is promi- 
 nent; it commences above at the base of the styloid process, and terminates below 
 in the posterior border of the outer malleolus. It is directed outward above, back- 
 ward in the middle of its course, backward and a little inward below, and gives 
 attachment to an aponeurosis which separates the Peronei muscles on the outer 
 surface of the shaft from the flexor muscles on its posterior surface. 
 
 Postero-intemal Border (crista medialis). — The postero-internal border, some- 
 times called the oblique line, commences above at the inner side of the head, 
 and terminates by becoming continuous with the antero-internal border or inter- 
 
238 THE SKELETON 
 
 osseous ridge at the lower fourth of the bone. It is well marked and promi- 
 nent at the upper and middle parts of the bone. It gives attachment to an 
 aponeurosis which separates the Tibialis posticus from the Soleus above and the 
 Flexor longus hallucis below. 
 
 Anterior Surface (fades anterior) ,-^The anterior surface is the interval between 
 the antero-external and antero-internal borders. It is extremely narrow and flat 
 in the upper third of its extent; broader and grooved longitudinally in its lower 
 third; it serves for the attachment of three muscles, the Extensor longus digitorum, 
 Peroneus tertius, and Extensor proprius hallucis. 
 
 External Surface (facies lateralis). — The external surface is the space between 
 the antero-external and postero-external borders. It is much broader than the 
 preceding, and often deeply grooved, is directed outward in the upper two-thirds 
 of its course, backward in the lower third, where it is continuous with the poste- 
 rior border of the external malleolus. This surface is completely occupied by 
 the Peroneus longus and brevis muscles. 
 
 Internal Surface (facies medialis). — The internal surface is the interval included 
 between the antero-internal and the postero-internal borders. It is directed 
 inward, and is grooved for the attachment of the Tibialis posticus muscle. 
 
 Posterior Surface (facies posterior). — ^The posterior surface is the space included 
 between the postero-external and the postero-internal borders, it is continuous 
 below with the rough triangular surface above the articular facet of the outer 
 malleolus; it is directed backward above, backward and inward at its middle, 
 directly inward below. Its upper third is rough, for the attachment of the Soleus 
 muscle; its lower part presents a triangular rough surface, connected to the tibia 
 by a strong interosseous ligament, and between these two points the entire surface 
 is covered by the fibres of origin of the Flexor longus hallucis muscle. At about 
 the middle of this surface is the nutrient foramen (foramen nutricium) . It opens 
 into the nutrient canal (canalis nutricius) , which is directed downward. 
 
 Lower Extremity. — The lower extremity, or external malleolus (malleolus 
 lateralis), is of a pyramidal form, somewhat flattened from without inward, and 
 is longer, and descends lower than the internal malleolus. Its external surface is 
 convex, subcutaneous, and continuous with the triangular (also subcutaneous) 
 surface on the outer side of the shaft. The internal surface presents in front a 
 smooth triangular facet (facies articularis malleoli) . broader above than below, and 
 convex from above downward, which articulates with a corresponding surface on 
 the outer side of the astragalus. Behind and beneath the articular surface is a 
 rough depression which gives attachment to the posterior fasciculus of the external 
 lateral ligament of the ankle. The anterior border is thick and rough, and marked 
 below by a depression for the attachment of the anterior fasciculus of the external 
 lateral ligament. The posterior border is broad and niarked by a shallow groove 
 (sulcus malleolaris) , for the passage of the tendons of the Peroneus longus and 
 brevis muscles. The summit is rounded, and gives attachment to the middle 
 fasciculus of the external lateral ligament. 
 
 In order to distinguish the side to which the bone belongs, hold it with the 
 lower extremity downward and the broad groove for the Peronei tendons back- 
 ward — i.e., toward the holder; the triangular subcutaneous surface will then be 
 directed to the side to which the bone belongs. 
 
 Articulations. — With two bones: the tibia and astragalus. 
 
 Development. — By three centres (Fig. 173): one for the shaft, and one for 
 each extremity. Ossification commences in the shaft about the eighth week of 
 foetal life, a little later than in the tibia, and extends gradually toward the extrem- 
 ities. At birth both ends are cartilaginous. Ossification commences in the lower 
 end in the second year, and in the upper one about the fourth year. The lower 
 ■epiphysis, the first in which ossification commences, becomes united to the shaft 
 
THE FOOT 
 
 239 
 
 Upper extremity. 
 
 Appears about /-^^VUnite^ about 
 y,h year. ^ ^Sm ^^^^ V^^- 
 
 about the twentieth year; the upper epiphysis joins about the twenty-fifth year. 
 Ossification appearing first in the lower epiphysis is contrary to the rule which 
 prevails with regard to the commencement of ossification in epiphyses — viz., 
 that epiphysis toward which the nutrient artery is 
 directed commences to ossify last; but it follows the 
 rule which prevails with regard to the union of epi- 
 physes, by uniting first. 
 
 Attachment of Muscles. — ^To nine: to the head, 
 the Biceps, Soleus, and Peroneus longus; to the shaft, 
 its anterior surface, the Extensor longus digitorum, 
 Peroneus tertius, and Extensor proprius hallucis; to 
 the internal surface, the Tibialis posticus; to the 
 posterior surface, the Soleus and Flexor longus 
 hallucis; to the external surface, the Peroneus longus 
 and brevis. 
 
 Surface Form. — The only parts of the fibula which are to 
 be felt are the head and the lower part of the external surface 
 of the shaft and the external malleolus. The head is to be 
 seen and felt behind and to the outer side of the outer tuber- 
 osity of the tibia. It presents a small, prominent triangular 
 eminence slightly above the level of the tubercle of the tibia. 
 The external malleolus presents a narrow elongated promi- 
 nence, situated on a plane posterior to the internal malleolus 
 and reaching to a lower level. From it may be traced the 
 
 lower third or half of the external surface of the shaft of the Appears o<__fliP Pni<cs about 
 bone in ihe interval between the Peroneus tertius in front and ^"'^ 2/«o»'- \ w / ^^''^ J'^"'"- 
 
 the other two Peronei tendons behind. 
 
 Surgical Anatomy. — In fractures of the bones of the leg both 
 bones are usually fractured, but either bone may be broken 
 separately, the fibula more frequently than the tibia. Fracture 
 of both bones may be caused either by direct or indirect violence. When it occurs from indirect 
 force, the fracture in the tibia is usually at the junction of the middle and lower third of the bone. 
 Many causes conduce to render this the weakest part of the bone. The fracture of the fibula 
 is usually at rather a higher level. These fractures present great variety, both as regards 
 their direction and condition. They may be oblique, transverse, longitudinal, or spiral. When 
 oblique, they are usually the result of indirect violence, and the direction of the fracture is from 
 behind, downward, forward, and inward in many cases, but may be downward and outward 
 or downward and backward. When transverse, the fracture is often at the upper part of the 
 bone, and is the result of direct violence. The spiral fracture usually commences as a vertical 
 fissure, involving the ankle-joint, and is associated with fracture of the fibula higher up. It is 
 the result of torsion, from twisting of the body whilst the foot is fixed. 
 
 Fractures of the tibia alone are almost always the result of direct violence, except where the 
 malleolus is broken of? by twists of the foot. Fractures of the fibula alone may arise from indi- 
 rect or direct force, those of the lower end being usually the result of the former, and those 
 higher up being caused by a direct blow on the part. 
 
 The tibia and fibula, like the femur, are frequently the seat of acute osteomyelitis. Tuberculous 
 <ibscess is more frequently met with in the cancellous tissue of the head and lower end of the 
 tibia than in any other bone of the body. The abscess is of small sizC; very chronic, and prob- 
 ably the result of tuberculous osteitis in the highly vascular growing tissue at the end of the shaft 
 near the epiphysial cartilage in the young subject. Such an abscess in bone is called Brodie's 
 abscess. 
 
 The tibia is the bone which is most frequently and most extensively distorted in rickets. It 
 gives way at the junction of the middle and lower third, its weakest part, and presents a curve 
 forward and outward. Bow-leg is due to outward curvature of the femur, tibia, and fibula, 
 the bend being about the junction of the shafts and lower extremities. 
 
 Lower extremity. 
 
 Fig. 173. — Plan of the development 
 of the fibula. By three centres. 
 
 THE FOOT (Figs. 174, 175). 
 
 The skeleton of the foot consists of three divisions: the tarsus, metatarsus, and 
 phalanges. 
 
240 
 
 THE SKELETON 
 
 Groove Jor peroncus lonqus. 
 Groove for peroneus brevis, 
 
 PERONEUS TERTIUS 
 PERONEUS BREVIS 
 
 Groove for tendon of 
 
 FLEXOR LONQUS HALLUCIS. 
 
 Tarsus. 
 
 Metatarsus. 
 
 Innermost tendon of 
 
 EXTENSOR BREVIS DIQITORUM. 
 
 i'^Shaftj Phalanges. 
 
 y 
 
 i!A.—.;5rT~ EXTENSOR LONQUS HALLUCIS. 
 
 Fig. 174.— Bones of the right foot. Dorsal surface. 
 
THE FOOT 
 
 241 
 
 A9DUCT0R HALLUCIS 
 
 OUTER HEAD Or ACCESSORIUS, 
 
 rtCXOR BREVIS HALLU0I8. 
 
 FLEXOR BREVia 
 , „.... ABDUCTOR 
 ( MINIMI DIQITI. 
 
 FLEXOR BREVIS OIQlTORUM. 
 
 FLEXOR LONQUS DIQITORUM. 
 
 Fig. 175. — Bones of the right foot. Plantar surface. 
 
 16 
 
242 
 
 THE SKELETON 
 The Tarsus (Ossa Tarsi). 
 
 The bones of the tarsus are seven in number — viz., the calcaneus or os calcis, 
 astragalus, cuboid, scaphoid, internal, middle, and external cuneiform. 
 
 The Calcaneus, or Heel Bone (Fig. 176).— It is also called the os calcis. The 
 name is derived from calx, the heel. The heel bone is the largest and strongest of 
 the tarsal bones. It is irregularly cuboidal in form, having its long axis directed for- 
 
 A 
 
 Peroneal tubercle 
 Groove for 
 Peroneus brevis 
 
 Groove for 
 Peroneus longus. Tubercle for ext. lat. lig. 
 
 For astragalus. 
 
 For cuboid, 
 tali. 
 
 Groove for Flex, 
 long, hallucis. 
 
 Fig. 176. — The left os calcis. A. Postero-external view. B. Antero-internal view. 
 
 ward and outv^^ard. It is situated at the lov^^er and back bart of the foot, serving to 
 transmit the weight of the body to the ground, and forming a strong lever for the 
 muscles of the calf. It is composed of a body (corpus calcanei) , an anterior extremity 
 or greater process, and a posterior extremity or tuberosity (tuber calcanei). It pre- 
 sents for examination six surfaces: superior, inferior, external, internal, anterior, 
 and posterior. 
 
 Superior Surface. — The superior surface is formed behind by the upper aspect 
 of that part of the os calcis which projects backward to form the heel. It varies 
 in length in different individuals ; is convex from side to side, concave from before 
 backward, and corresponds above to a mass of adipose substance placed in 
 front of the tendo Achillis. In the middle of the superior surface are two (some- 
 times three) articular facets, separated by a broad shallow groove (sulcus cal- 
 canei), which is directed obliquely forward and outward, and is rough for the 
 attachment of the interosseous ligament connecting the astragalus and os calcis. 
 When the calcaneus is in contact with the astragalus this groove is converted into 
 a canal (sinus tarsi) . Of the articular surfaces, the external or posterior articular 
 surface (fades articularis calcanea posterior) is the larger, and is situated on the body 
 
THE TARSUS 243 
 
 of the bone: it is of an oblong form, wider behind than in front, and convex from 
 before backward. The internal or anterior articular surface is usually divided into 
 two facets. The anterior facet is the ]acies articularis calcanea anterior, and it 
 supports the head of the astragalus. The more posteriorly situated facet is the 
 fades articularis calcanea media. It articulates with the middle facet on the 
 under surface of the astragalus. The internal articular surface is supported on 
 a projecting process of bone, called the lesser process of the calcaneus (susten- 
 taculum tali) ; it is also oblong, concave longitudinally, and sometimes subdivided 
 into two parts, which differ in size and shape. More anteriorly is seen the upper 
 surface of the greater process of the calcaneus, marked by a rough depression 
 for the attachment of numerous ligaments, and a tubercle for the origin of the 
 Extensor brevis digitorum muscle. 
 
 Inferior Surface. — The inferior surface is narrow, rough, uneven, wider behind 
 than in front and convex from side to side, it is bounded posteriorly by two tuber- 
 cles separated by a rough depression ; the external tubercle (processus lateralis tuheris 
 calcanei), small, prominent, and rounded, gives attachment to part of the Abductor 
 minimi digiti : the internal tubercle (processus medialis tuheris calcanei) , broader 
 and larger, for the support of the heel, gives attachment, by its prominent inner 
 margin, to the Abductor hallucis, and in front to the Flexor brevis digitorum 
 muscles and plantar fascia; the depression between the tubercles gives attach- 
 ment to the Abductor minimi digiti. The rough surface in front of the tubercles 
 gives attachment to the long plantar ligament and to the outer head of the Flexor 
 accessorius muscle; while to a prominent tubercle nearer the anterior part of 
 this surface, as well as to a transverse groove in front of it, is attached the 
 short plantar ligament. 
 
 External Surface. — The external surface is broad, flat, and almost subcutaneous; 
 it presents near its centre a tubercle, for the attachment of the middle fasciculus 
 of the external lateral ligament. At its upper and anterior part this surface 
 gives attachment to the external calcaneo-astragaloid ligament; and in front of 
 the tubercle it presents a narrow surface marked by two oblique grooves, sepa- 
 rated by an elevated ridge which varies much in size in different bones; it is 
 named the peroneal spine or tubercle (processus trochlearis) , and gives attachment 
 to a fibrous process from the external annular ligament. The superior groove 
 transmits the tendon of the Peroneus brevis; the inferior groove the tendon of 
 the Peroneus longus. 
 
 Internal Surface. — The internal surface is deeply concave; it is directed obliquely 
 downward and forward, and serves for the transmission of the plantar vessels 
 nd nerves into the sole of the foot; it affords attachment to part of the Flexor 
 
 cessorius muscle. At its upper and fore part it presents an eminence of bone, 
 
 e lesser process of the calcaneum (sustentaculum tali), which projects horizon- 
 tally inward, and to it a slip of the tendon of the Tibialis posticus is attached. 
 This process is concave above, and supports the anterior articular surface of 
 the astragalus; below, it is grooved for the tendon of the Flexor longus hallucis. 
 Its free margin is rough, for the attachment of part of the internal lateral liga- 
 ment of the ankle-joint. 
 
 Anterior Surface (fades articularis cuboidea). — The anterior surface, of a some- 
 what triangular form, articulates with the cuboid. It is concave from above 
 downward and outward, and convex in the opposite direction. Its inner border 
 gives attachment to the inferior calcaneo-scaphoid ligament. 
 
 Posterior Surface. — The posterior surface is rough, prominent, convex, and 
 wider below than above. The posterior extremity is the projection of the heel. 
 It is called the tuberosity (tuber calcanei). Its lower part is rough, for the attach- 
 ment of the tendo Achillis and the tendon of the Plantaris muscle; its upper part 
 is smooth, and is covered by a bursa which separates the tendons from the bone. 
 
 ^ 
 
 '^^. 
 
244 
 
 THE SKELETON 
 
 Articulations. — With two bones: the astragalus and cuboid. 
 
 Attachment of Muscles. — To eight : part of the Tibiahs posticus, the tendo 
 AchilHs, Plantaris, Abductor hallucis, Abductor minimi digiti, Flexor brevis digi- 
 torum, Flexor accessorius, and Extensor brevis digitorum. 
 
 The Astragalus, or Ankle Bone (talus) (Fig. 177). — The astragalus (daTfjayah}::, 
 a die) is the largest of the tarsal bones, next to the os calcis. It occupies thei 
 middle and upper part of the tarsus, supporting the tibia above, articulating 
 with the malleoli on either side, resting below upon the os calcis, and joined inj 
 front to the scaphoid. This bone may easily be recognized by its large roundec 
 head, by the broad articular facet on its upper convex surface, and by the tw( 
 articular facets separated by a deep groove on its under concave surface. II 
 
 For 
 navicular. Neck. 
 
 Sup. surface 
 for tibia. 
 
 ■ / 
 
 For inner 
 malleolus. 
 
 For navicular. 
 
 For ext. 
 malleolus 
 
 ^For inferior 
 calc. navic. lig. 
 
 Groove for ^_^^^' 
 
 Flex. long. hall. «« ^'"'«*«- 
 
 Fig. 177. — The left astragalus. A. Superior and external view. B. Inferior and internal view, 
 
 is divided into a body (corpus tali), which supports the trochlear surface; the 
 head (caput tali), which is in front of the body; and the neck (collum tali), the 
 constricted part between the head and body. The astragalus presents si? 
 surfaces for examination. 
 
 Superior Surface. — The superior surface presents, behind, a broad smootl 
 trochlear surface (trochlea tali) for articulation with the tibia. The trochlea is| 
 broader in front than behind, convex from before backward, slightly concave 
 from side to side; in front of it is the upper surface of the neck of the 
 astragalus, rough for the attachment of ligaments. 
 
 Inferior Surface. — The inferior surface presents two articular facets separatee 
 by a deep groove (sulcus tali). The groove runs obliquely forward and outward, 
 becoming gradually broader and deeper in front: it corresponds with a similar 
 groove upon the upper surface of the calcaneus, and forms, when articulated wit! 
 that bone, a canal (sinus tarsi) , filled up in the recent state by the interosseous 
 calcaneo-astragaloid ligament. Of the two articular facets, the posterior articula 
 facet (fades articularis calcanea posterior) is the larger, of an oblong form an( 
 deeply concave from side to side; the anterior articular facet is shorter and nar- 
 rower, of an elongated oval form, convex longitudinally, and often subdivided intq 
 two by an elevated ridge; of these, the posterior (fades articularis calcanea media) 
 articulates with the lesser process of the os calcis ; the anterior (fades articulari 
 calcanea anterior) , with the upper surface of the inferior calcaneo-scaphoid ligamentj 
 
 Internal Surface. — The internal surface presents at its upper part a pear-shapec 
 articular facet (fades malleolaris medialis) for the inner malleolus, continuous 
 above with the trochlear surface; below the articular surface is a rougl 
 depression, for the attachment of the deep portion of the internal lateral ligament^ 
 
 External Surface. — The external surface presents a large triangular facet (faciei 
 malleolaris lateralis) , covered with cartilage and concave from above downwai 
 
THE TARSUS 
 
 245 
 
 for articulation with the external malleolus; it is called the external process {'pro- 
 cessus lateralis tali), and passes outward and downward from the triangular facet. 
 The triangular facet is continuous above with the trochlear surface; and in front 
 of it is a rough depression for the attachment of the anterior fasciculus of the 
 external lateral ligament of the ankle-joint. 
 
 Anterior Surface {jades articularis navicularis) . — The anterior surface of the 
 h?ad of the astragalus is convex and rounded, smooth, of an oval form, and 
 directed obliquely inward and downward; it articulates with the scaphoid. On 
 its under and inner surface is a small facet, continuous in front with the articular 
 surface of the head, and behind with the smaller facet for the os calcis. This 
 rests on the inferior calcaneo-scaphoid ligament, being separated from it by the 
 synovial membrane, which is prolonged from the anterior calcaneo-astragaloid 
 joint to the astragalo-scaphoid joint. The head is surrounded by a constricted 
 portion, the neck of the astragalus {collum tali). 
 
 Posterior Surface. — The posterior surface is narrow, and traversed by a groove 
 {sulcus m. flexor is hallucis longi), which runs obliquely downward and inward, 
 and transmits the tendon of the Flexor longus hallucis, external to which is 
 the prominent external tubercle {processus posterior tali), to which the posterior 
 fasciculus of the external lateral ligament is attached. This tubercle is some- 
 times separated from the rest of the astragalus, and is then known as the os 
 trigonum. To the inner side of the groove is the less marked internal tubercle. 
 
 To ascertain to which foot the bone belongs, hold it with the broad articular 
 surface upward, and the rounded head forward; the lateral triangular articular 
 surface foi' the external malleolus will then point to the side to which the bone 
 belongs. 
 
 Articulations. — With four bones: tibia, fibula, os calcis, and scaphoid. 
 
 The Cuboid {os cuhoideaim) (Fig. 178). — The cuboid, from zt>/9oc, a cube; 
 eidoQ, like, is placed on the outer side of the foot, in front of the os calcis, and 
 
 isionnl facet. 
 • navicular. 
 
 For ext. 
 cuneiform. 
 
 For fourth 
 metatarml. 
 
 Groove for 
 Peroneus longus. For os calcis. 
 For fifth metatarsal. 
 Fig. 178. — The left cuboid. A. Antero-internal view. B. Postero-external view. 
 
 )ehind the fourth and fifth metatarsal bones. It is of a pyramidal shape, its 
 base being directed inward, its apex outward. It may be distinguished from 
 the other tarsal bones by the existence of a deep groove on its under surface, 
 for the tendon of the Peroneus longus muscle. It presents for examination six 
 surfaces: three articular and three non-articular. 
 
 Non-articular Surfaces. — The non-articular surfaces are the superior, inferior, and 
 external. The superior or dorsal surface, directed upward and outward, is rough, 
 for the attachment of numerous ligaments. The inferior or plantar surface presents 
 in front a deep groove, the peroneal groove {sulcus m. peronoei longi), which 
 runs obliquely from without, forward and inward; it lodges the tendpn of the 
 Peroneus longus, and is bounded behind by a prominent ridge, to which is 
 attached the long calcaneo-cuboid ligament. The ridge terminates externally 
 in an eminence, the tuberosity of the cuboid {tuberositas ossis cuboidei), the sur- 
 face of which presents a convex facet, for articulation with the sesamoid bone 
 
246 
 
 THE SKELETON 
 
 of the tendon contained in the groove. The surface of bone behind the groove 
 is rough, for the attachment of the short plantar ligament, a few fibres of the 
 Flexor brevis hallucis, and a fasciculus from the tendon of the Tibialis posticus. 
 The external surface, the smallest and narrowest of the three, presents a deep 
 notch formed by the commencement of the peroneal groove. 
 
 Articular Surfaces. — The articular surfaces are the posterior, anterior, and] 
 internal. The 'posterior surface is smooth, triangular, and concavo-convex, foi 
 articulation with the anterior surface of the os calcis. The anterior surface, o{ 
 smaller size, but also irregularly triangular, is divided by a vertical ridge intc 
 two facets; the inner one, quadrilateral in form, articulates with the fourtl: 
 metatarsal bone; the outer one, larger and more triangular, articulates witl 
 the fifth metatarsal. The internal surface is broad, rough, irregularly quadrin 
 lateral, presenting at its middle and upper part a smooth oval facet, for articula-i 
 tion with the external cuneiform bone; and behind this (occasionally) a smallei 
 facet, for articulation with the navicular; it is rough in the rest of its extent, for 
 the attachment of strong interosseous ligaments. 
 
 To ascertain to which foot the bone belongs, hold it so that its under surface] 
 marked by the peroneal groove, looks downward, and the large concavo-convex! 
 articular surface backward toward the holder: the narrow non-articular surface,! 
 marked by the commencement of the peroneal groove, will point to the side toj 
 which the bone belongs. 
 
 Articulations. — With four bones: the os calcis, external cuneiform, and the 
 fourth and fifth metatarsal bones; occasionally with the scaphoid. 
 
 Attachment of Muscles. — Part of the Flexor brevis hallucis and a slip from] 
 the tendon of the Tibialis posticus. 
 
 Scaphoid or Navicular Bone {os naviculare pedis) (Fig. 179). — The scaphoid) 
 is situated at the inner side of the tarsus, between the astragalus behind and] 
 
 J^ur mid. cuneiform. 
 
 For int. 
 cuneiform, 
 
 For ext. 
 cuneiform. 
 
 For cuboid 
 (occasional). For astragalus. 
 
 Fig. 179. — The left scaphoid. A. Antero-external view. B. Postero-internal view. 
 
 the three cuneiform bones in front. It may be distinguished by its form, bein^ 
 concave behind, convex and subdivided into three facets in front. 
 
 Surfaces. — The anterior surface, of an oblong form, is convex from side to side,| 
 and subflivided by two ridges into three facets, for articulation with the three 
 cuneiform bones. The posterior surface is oval, concave, broader externally! 
 than internally, and articulates with the rounded head of the astragalus. Tbej 
 superior surface is convex from side to side, and rough for the attachment oi 
 ligaments. The inferior is irregular, and also rough for the attachment of liga- 
 ments. The internal surface presents a rounded tubercular eminence, thej 
 tuberosity (tuberositas ossis navicularis) , the lower part of which projects, andl 
 gives attachment to part of the tendon of the Tibialis posticus. The external] 
 surface is rough and irregular, for the attachment of ligamentous fibres, andf 
 occasionally presents a small facet for articulation with the cuboid bone. 
 
THE TARSUS 247 
 
 To ascertain to which foot the bone belongs, hold it with the concave articular 
 surface backward, and the convex dorsal surface upward; the external surface — 
 i. e., the surface opposite the tubercle — will point to the side to which the bone 
 belongs. 
 
 Articulations. — With four bones: astragalus and three cuneiform; occasionally 
 also with the cuboid. 
 
 Attachment of Muscles. — Part of the Tibialis posticus. 
 
 Cuneiform or Wedge Bones. — The cuneiform bones have received their 
 name from their wedge-like shape {cuneus, a wedge; forma, likeness). They 
 form, with the cuboi(l, the anterior row of the tarsus, being placed between 
 the scaphoid behind, the three innermost metatarsal bones in front, and the 
 cuboid externally. They are called the first, second, and third, counting from 
 the inner to the outer side of the foot, and, from their position, internal, middle, 
 and external. 
 
 Internal or First Cuneiform (os cuneiforme primum) (Fig. 180). — The inter- 
 nal cuneiform is the largest of the three. It is situated at the inner side of 
 the foot, between the scaphoid behind and the base of the first metatarsal in 
 front. It may be distinguished from ^^^.^^^^ ^^^^^^^^^^ For middle 
 
 the other two by its large size, and metatarsal. metatarsal. cuneiform. 
 
 by its not presenting such a distinct 
 wedse-like form. Without the others 
 ■ it may be known by the large, kidney- 
 shaped anterior articulating surface 
 and by the prominence on the in- 
 'erior or plantar surface for the at- 
 tachment of the Tibialis posticus. It 
 presents for examination six surfaces. 
 Surfaces. — The internal surface is 
 
 subcutaneous, and forms part of the ■f"'" tendon of Tibialis ant. For navicular. 
 
 ;^.,^v. Vx^,.J,,« ^t *^V..r. f^r^+. ;+ Ic. U^^o^l Fig. 180. — The left internal cuneiform. A. Antero- 
 
 inner border Ot the toot; it is broad, internal view. B. Postero-extemal view. 
 
 cjuadrilateral, and presents at its an- 
 terior inferior angle a smooth oval facet, into which the tendon of the Tibialis 
 anticus is partially inserted; in the rest of its extent it is rough, for the attachment 
 of ligaments. The external surface is concave, presenting, along its superior and 
 posterior borders, a narrow, reversed, L-shaped surface, for articulation with the 
 middle cuneiform behind and second metatarsal bone in front; in the rest of its 
 extent it is rough, for the attachment of ligaments and part of the tendon of the 
 eroneus longus. The anterior surface, kidney-shaped, much larger than the poste- 
 or, articulates with the metatarsal bone of the great toe. The posterior surface 
 is triangular, concave, and articulates with the innermost and largest of the three 
 facets on the anterior surface of the scaphoid. The inferior or plantar surface 
 is rough, and presents a prominent tuberosity at its back part for the attachment 
 of part of the tendon of the Tibialis posticus. It also gives attaphment in front 
 to part of the tendon of the Tibialis anticus. The superior surface is the narrow- 
 pointed end of the wedge, which is directed upward and outward; it is rough 
 for the attachment of ligaments. 
 
 To ascertain to which side the bone belongs, hold it so that its superior narrow 
 edge looks upward, and the long, kidney-shaped, articular surface forward; the 
 external surface, marked by its vertical and horizontal articular facets, will 
 point to the side to which it belongs. 
 
 Articulations. — With four bones: scaphoid, middle cuneiform, first and second 
 metatarsal bones. 
 
 Attachment of Muscles. — To three : the Tibialis anticus and posticus, and 
 Peroneus longus. 
 
 m 
 
248 
 
 THE SKELETON 
 
 Middle or Second Cuneiform {os cuneiforme secundum) (Fig. 181). — The 
 middle cuneiform, the smallest of the three, is of very regular wedge-like form, 
 the broad extremity being placed upward, the narrow end downward. It is 
 situated between the other two bones of the same name, and articulates with the 
 scaphoid behind and the second metatarsal in front. It is smaller than the external 
 cuneiform bone, from which it may be further distinguished by the L-shaped 
 articular facet, which runs round the upper and back part of its inner surface. 
 
 Surfaces. — The anterior surface, triangular in form and narrower than the poste- 
 rior, articulates with the base of the second metatarsal bone. The posterior sur- 
 face, also triangular, articulates with the scaphoid. The internal surface presents] 
 a reversed L-shaped articular facet, running along the superior and posteriori 
 borders, for articulation with the internal cuneiform, and is rough in the rest] 
 of its extent, for the attachment of ligaments. The external surface presents 
 posteriorly a smooth facet for articulation with the external cuneiform bone. 
 The superior surface forms the base of the wedge; it is quadrilateral, broader: 
 behind than in front, and rough for the attachment of ligaments. The inferior' 
 surface, pointed and tubercular, is also rough for ligamentous attachment and 
 for the insertion of a slip from the tendon of the Tibialis posticus. 
 
 For int. cuneiform. 
 
 For navicular. 
 
 For navicular. 
 
 For mid. cuneiform. 
 
 For ext. cuneiform. 
 
 Fig. 181. — The left middle cuneiform. A. Antero- 
 internal view. B. Posteroexternal view. 
 
 For fourth For cuboid, 
 metatarsal. I 
 
 Fig. 182. 
 
 For For third 
 
 second metatarsal, metatarsal. 
 
 -The left external cuneiform. A. Postero-internal 
 view. B. Antero-external view. 
 
 To ascertain to which foot the bone belongs, hold its superior or dorsal surface ' 
 upward, the broadest edge being toward the holder: the smooth facet (limited 
 to the posterior border) will then point to the side to which it belongs. 
 
 Articulations. — With four bones: scaphoid, internal and external cuneiform, 
 and second matatarsal bone. 
 
 Attachment of Muscles. — A slip from the tendon of the Tibialis posticu-s is I 
 attached to this bone. 
 
 External or Third Cuneiform (os cuneiforme tertium) (Fig. 182). — The exter- 
 nal cuneiform, intermediate in size between the two preceding, is of a very! 
 regular wedge-like form, the broad extremity being placed upward, the narrow < 
 end downward. It occupies the centre of the front row of the tarsus, between 
 the middle cuneiform internally, the cuboid externally, the scaphoid behind, and 
 the third metatarsal in front. It is distinguished from the internal cuneiform i 
 bone by its more regular wedge-like shape and by the absence of the kidney- j 
 shaped articular surface: from the middle cuneiform, by the absence of thei 
 reversed L-shaped facet, and by the two articular facets which are present onj 
 both its inner and outer surfaces. It has six surfaces for examination. 
 
 Surfaces. — The anterior surface, triangular in form, articulates with the thirdj 
 metatarsal bone. The posterior surface articulates with the most external facet 
 of the scaphoid, and is rough below for the attachment of ligamentous fibres.. 
 The internal surface presents two articular facets, separated by a rough depres-l 
 sion; the anterior one, sometimes divided into two, articulates with the outer side J 
 of the base of the second metatarsal bone; the posterior one skirts the posteriori 
 border and articulates with the middle cuneiform; the rough depression between! 
 
THE 3IETATABSAL BONES 249 
 
 the two gives attachment to an interosseous Hgament. The external surface also 
 presents two articular facets, separated by a rough non-articular surface; the 
 anterior facet, situated at the superior angle of the bone, is small, and articulates 
 with the inner side of the base of the fourth metatarsal; the posterior and larger 
 one articulates with the cuboid; the rough, non-articular surface serves for the 
 attachment of an interosseous ligament. The three facets for articulation with 
 the three metatarsal bones are continuous with one another, and covered by a 
 prolongation of the same cartilage; the facets for articulation with the middle 
 cuneiform and scaphoid are also continuous, but that for articulation with he 
 cuboid is usually separate. The superior or dorsal surface is of an oblong square 
 form, its posterior external angle being prolonged backward. The inferior or 
 plantar surface is an obtuse rounded margin, and serves for the attachment of 
 part of the tendon of the Tibialis posticus, part of the Flexor brevis hallucis, 
 and ligaments. 
 
 To ascertain to which side the bone belongs, hold it with the broad dorsal 
 surface upward, the prolonged edge backward; the separate articular facet for 
 the cuboid will point to the proper side. 
 
 Articulations. — With six bones: the scaphoid, middle cuneiform, cuboid, and 
 second, third, and fourth metatarsal bones. 
 
 Attachment of Muscles. — To two: part of the Tibialis posticus, and Flexor 
 brevis hallucis. 
 
 The number of tarsal bones may be reduced owing to congenital ankylosis 
 which may occur between the os calcis and cuboid, the os calcis and scaphoid, 
 
 e OS calcis and astragalus, or the astragalus and scaphoid. 
 
 tf 
 
 The Metatarsal Bones (Ossa Metatarsalia). 
 
 The metatarsal bones are five in number, and are numbered one to five, in 
 accordance with their position from within outward; they are long bones, and 
 ])resent for examination a shaft and two extremities. 
 
 Common Characters. — The shaft (corpus) is prismoid in form, tapers gradually 
 from the tarsal to the phalangeal extremity, and is slightly curved longitudinally, 
 so as to be concave below, slightly convex above. On the plantar surface of the 
 shaft of each bone is a nutrient foramen corresponding to the nutrient foramen 
 in each metacarpal bone. The posterior or proximal extremity, or base (basis), 
 is wedge-shaped, articulating by its terminal surface with the tarsal bones, and 
 by its lateral surfaces with the contiguous metatarsal bones, its dorsal and plantar 
 surfaces being rough for the attachment of ligaments. The anterior or distal 
 extremity, or head (capitulum) , presents a terminal rounded articular surface, 
 oblong from above downward, and extending farther backward below than 
 above. Its sides are flattened and present a depression, surmounted by a 
 tubercle, for ligamentous attachment. Its under surface is grooved in the 
 middle line for the passage of the Flexor tendon, and marked on each side by 
 an articular eminence continuous with the terminal articular surface. 
 
 Peculiar Characters. First Metatarsal Bone or the Metatarsal Bone of the Great 
 Toe {as metatarsale I). — The first (Fig. 183) is remarkable for its great thickness, 
 but is the shortest of all the metatarsal bones. The shaft is strong and of well- 
 marked prismoid form. The posterior extremity presents, as a rule, no lateral 
 articular facet, but occasionally on the outer side there is an oval facet by which 
 it articulates with the second metatarsal bones. Its terminal articular surface is of 
 large size and kidney-shaped; its circumference is grooved, for the tarso-metatarsal 
 ligaments, and internally gives attachment to part of the tendon of the Tibialis 
 anticus muscle; its inferior angle presents a rough oval prominence, the tuberosity 
 (tuberositas ossis metatarsalis I) , for the insertion of the tendon of the Peroneus 
 
250 
 
 THE SKELETON 
 
 longus. The head is of large size; on its plantar surface are two grooved facets, 
 over which glide sesamoid bones ; the facets are separated by a smooth elevated 
 ridge. 
 
 This bone is known by the single kidney-shaped articular surface on its base, 
 the deeply grooved appearance of the plantar surface of its head, and its great 
 
 thickness relatively to its length. . 
 When it is placed in its natural^! 
 position, the concave border of 
 the kidney-shaped articular sur- 
 face on its base points to the^f 
 side to which the bone belongs. ^" 
 
 Attachment of Muscles. — To 
 three: part of the Tibialis anti-- 
 cus, the Peroneus longus, and] 
 the First dorsal interosseous. 
 
 Second Metatarsal {os metatarA 
 sale II) .—The second (Fig. 184)] 
 is the longest and largest of the 
 remaining metatarsal bones, be-J 
 ing prolonged backward into the 
 recess formed between the three! 
 cuneiform bones. Its tarsal ex- 
 tremity is broad above, narrow! 
 and rough belovv^. It presents! 
 four articular surfaces: one be-j 
 hind, of a triangular form, for articulation with the middle cuneiform ; one at thej 
 upper part of its internal lateral surface, for articulation with the internal cunei-j 
 
 For internal cuneiform. 
 
 J'iG. 183. — The first metatarsal 
 
 Occasional facet fui 
 second metatarsal. 
 
 (Left.) 
 
 Occasional 
 facet for first 
 ! metatarsal. 
 
 For middle cuneiform. 
 
 Fig. 184. — The second metatarsal. 
 
 For external 
 cuneiform. 
 
 (Left.) 
 
 / For second melahirsal. 
 For middle cuneiform. 
 
 For foiirfh 
 metatarsal. 
 
 Fig. 185. — The third metatarsal. (Left.) 
 
 form ; and two on its external lateral surface — an upper and a lower, separated by 
 a rough non-articular interval. Each of these articular surfaces is divided by a] 
 vertical ridge into two facets, thus making four facets; the two anterior of thesel 
 
THE METATARSAL BONES 
 
 251 
 
 articulate with the third metatarsal ; the two posterior (sometimes continuous) with 
 the external cuneiform. In addition to these articular surfaces there is occasion- 
 ally a fifth when this bone articulates with the first metatarsal bone. It is oval in 
 shape, and is situated on the inner side of the shaft near the base. 
 
 The facets on the tarsal extremity of the second metatarsal bone serve at once 
 to distinguish it from the rest, and to indicate the foot to which it belongs; there 
 being one facet at the upper angle of the internal surface, and two facets, each 
 subdivided into two parts, on the external surface, pointing to the side to which 
 the bone belongs. The fact that the two posterior subdivisions of these external 
 facets sometimes run into one should not be forgotten. 
 
 Attachment of Muscles. — To ]our : the Adductor obliquus halhicis, First and 
 Second dorsal interosseous, and a slip from the tendon of the Tibialis posticus; 
 occasionally also a slip from the Peroneus longus. 
 
 Third Metatarsal {os metaiarsale HI) . — The third metatarsal (Fig. 185) articu- 
 lates behind, by means of a triangular smooth surface, with the external cunei- 
 form; on its inner side, by two facets, with the second metatarsal; and on its 
 outer side, by a single facet, with the fourth metatarsal. The latter facet is of 
 circular form and situated at the upper angle of the base. 
 
 The third metatarsal is known by its having at its tarsal end two undivided 
 facets on the inner side, and a single facet on the outer. This distinguishes it 
 from the second metatarsal, in which the two facets, found on one side of its 
 tarsal end, are each subdivided into two. The single facet (when the bone is put 
 in its natural position) is on the side to which the bone belongs. 
 
 Attachment of Muscles. — To five : Adductor obliquus hallucis. Second and 
 Third dorsal, and First plantar interosseous, and a slip from the tendon of the 
 Ti])ialis posticus. 
 
 Fourth Metatarsal {os metaiarsale IV). — The fourth metatarsal (Fig. 186) is 
 smaller in size than the preceding; its tarsal extremity presents a terminal quad- 
 
 For cuboid. 
 For ext. cuneiform. 
 
 For fifth 
 metatarsal. 
 
 Fig. 186.— The fourth metatarsal. (Left.) 
 
 For fourth \ 
 
 metatarsal. \ ^ »"<='"--»• 
 
 Fnr ciiboid. 
 Fig. 187.— The fifth metatarsal. (Left.) 
 
 rilateral surface, for articulation with the cuboid; a smooth facet on the inner 
 side, divided by a ridge into an anterior portion for articulation with the third 
 
252 "THE SKELETON 
 
 metatarsal, and a posterior portion for artic'iilatioi> with the external cuneiform; 
 on the outer side a sinjijle facet, for articulation with the fifth metatarsal. 
 
 The fourth metatarsal is known by its haviufj^ a sino;le facet on either side of 
 the tarsal extremity, that on the inner side heinjjj divided into two })arts. If this 
 subdivision be not recognizable, the fact that its tarsal end is bent somewhatf^ 
 outward will indicate the side to which it belonj^s. 
 
 Attachment of Muscles. — To five: Adductor obliquus hallucis, Third anc 
 Fourth dorsal, and Second plantar interosseous, and a slip from the tendon of the 
 Tibialis posticus. 
 
 Fifth Metatarsal Bone, or the Metatarsal Bone of the Little Toe {os met afar sale V)\ 
 — The fifth metatarsal (Fii;;. 1S7) is rec()ti;ni/ed by the tubercl'* (fnheroslfas ossis' 
 mefatarsalis V) on the outer side of its base. It articulates behind, by a tri- 
 an<2^ular surface cut oblicpiely from without inward, with the cuboid, and int.T-" 
 nally with the fourth metatarsal. 
 
 The projection on the outer side of this bone at its tarsal end at once distinJ 
 guishes it from the others, and points to the side to which it belongs. 
 
 Attachment of Muscles. — To six : the Peroneus brevis, Peroneus tertius 
 Flexor brevis minimi digiti, Adductor transversus hallucis, Fourth dorsal, am 
 Third plantar interossei. 
 
 Articulations. — Each bone articulates with the tarsal bones by one extremity 
 and by the other with the first row of phalanges. The number of tarsal boneij 
 with which each metatarsal articulates is t)ne for the first, three for the secon(" 
 one for the third, two for the fourth, and one for the fifth. 
 
 The Phalanges of the Foot (Phalanges Digitoram Pedis). 
 
 The phalanges of the foot, both in number and general arrangement, resembU 
 those in the hand; there being two in the great toe and three in each of th^ 
 other toes. The nutritive foramina correspond to those in the phalanges of th^ 
 hand. 
 
 The first or proximal phalanx (phalanx prima) resembles closely the correspond^ 
 ing bone of the hand. The shaft also is compressed from side to side, convex 
 above, concave below. The posterior extremity is concave; and the anteric 
 extremitif presents a trochlear surface, for articulation with the second phalanx. 
 
 The second phalanx (phalanx secunda) is remarkably small and short, \n\\ 
 rather broader than the first ])halanx. 
 
 The ungual or distal phalanx (phalanx tcriia) in form resembles the bone of th* 
 corresponding finger, l)ut is smaller, flattened from above downward, presenting 
 broad base for articulation with tlie second phalanx, and an expanded extremity 
 for the sup))ort of the nail and end of the toe. 
 
 Articulation.^The first row, with the metatarsal bones behind and secon( 
 phalanges in front; the second row of the four outer toes, with the first and thirc 
 phalanges; of the great toe, with the first phalanx; the third row of the four outei 
 toes, with the second phalanges. 
 
 Attachment of Muscles. — To the first phalanges. Great toe, five muscles^ 
 innermost tendon of Extensor brevis digitorum, Abductor hallucis. Adductor 
 obliquus hallucis, Flexor brevis hallucis. Adductor transversus hallucis. Second 
 toe, three muscles: First and Second dorsal interosseous and First lumbrical. 
 Third toe, three muscles: Third dorsal and First plantar interosseous and Second 
 lumbrical. Fourth toe, three muscles: Fourth dorsal and Second plantar inter- 
 osseous and Third lumbrical. Fifth toe, four muscles: Flexor brevis minimi 
 digiti. Abductor minimi digiti, and Third plantar interosseous, and Fourth! 
 lumbrical. — Second phalanges. (Ireat toe; Extensor longus hallucis. Flexor! 
 longus hallucis. Other toes; Flexor brevis digitorum, one slip of the commor 
 
DEVELOrMKI^T OF TUi: FOOT 
 
 253 
 
 Icndoii of (lie FiXtcnsor loii^us uiid hirvis di^iloniin.'- — Tliinl pliulaii^c.s: (wo sli|),s 
 from the coiiimoii tendon of the KxliMi.sor loii^u.s and Extensor hrevis digitoruni, 
 and the Flexor lon<fiis dif^itornni. 
 
 Development of the Foot {V\\^. I.S8). 
 
 The Tarsal Bones are each developed hy a Hincflc centre, excepting the os calcis 
 
 I which hiis an ej)iphy.sis for its posterior extn-niity. The centres nMd\e their appear- 
 ', ance in Ih*- following order: os caU'is, at the sixth month of fo'tai life; astragalus, 
 
 y H i 8. 
 
 "^ ^a^HMEEk, Appenm VHh year ; 
 
 . *^i'//'/ •'"**'" \ uniivs after puberty. 
 
 Tarmis. Walei.//. 
 
 One centre for eneh bone, nJ^^''""§\ 
 
 exccnt OS cald». \ yWrinKiL 
 
 MdatnrHioi. 
 
 Tu'o mil rm for rach bone 
 Out' for HhafI, 
 One for difiilnl extremity 
 except lat. 
 
 Appear$ 7th week. 
 
 Unite 18th-20th year. 
 Appi'drn lird year, 
 
 Appearn ^Ih year..—,^^ 
 
 Unite 17-lHth year. 
 
 Phalanges. Appears 2nd-/tlh monlh.- 
 
 Tuio centres for each bone : 
 
 One for shnfl, 
 
 Oneformelalarsal Appears mh -7th year. ^ ^ 
 
 extremity. f/„//,, 77//, igih year. .[ ' *^ £ 
 
 ' V'kl 
 
 Appears '£n<l-4lh month. t»-''»i 
 
 Appears (llh year.^^ si 
 
 Unite 17th- IKIh year.-r^. - 
 
 Appears 7th week.^ij)'^^ 
 
 f^-J^ Appears /5th year, 
 WHS^ I Unite mh~20 year. 
 
 \~ Appears 7th week. 
 
 
 Fio, 188. — Plan of the (iovelopment of the foot, 
 
 al)out the seventh month; enhoid, at the ninth month; external cuneiform, dur- 
 ing the first y^'iir; internal cuneiform in the third year; middle cuneiform and 
 sca[)hoid in the fourth year. The ej)ij)hysis for the posterior tnlx'rosity of the 
 OS calcis ap|)ears at the tenth year, and unites with the rest of the hone soon 
 after |)ul)erty. 
 
 The Metatarsal Bones are each developed hy two centres: one for the shaft 
 and one for tlx' digital extremity in the ff)ur outer metatarsal; one for the shaft 
 and one for the base in the metatarsal hone of the great toe,'' Ossification com- 
 
 ' Except the ttecond phalanx of the fifth toe, which receive* no »iHp from the Kxtennor brevln diBltoriirn. 
 » Ah waH nijtcil in the firHt inctaciiroiil bono, no in th<i firMt niPtatiirHal, there i« often to be oljwrved a ten<lency 
 to the formation of n xecond epiphynlH in tiic (iiMliil extremity. 
 
254 
 
 THE SKELETON 
 
 mences in the centre of the shaft about the ninth week, and extends toward 
 either extremity. The centre in the proximal end of the first metatarsal bone 
 appears about the third year, the centre in the distal end of the other bones 
 between the fifth and eighth years; they become joined between the eighteenth 
 and twentieth years. 
 
 The Phalanges are developed by two centres for each bone: one for the shaft 
 and one for the metatarsal extremity. The centre for the shaft appears about the 
 tenth week, that for the epiphysis between the fourth and tenth years; they join 
 the shaft about the eighteenth year. 
 
 Construction of the Foot as a Whole (Figs. 189, 190). 
 
 The foot is constructed on the same principles as the hand, but modified to form 
 a firm basis of support for the rest of the body when in the erect position. It 
 is more solidly constructed, and its component parts are less movable on each 
 other than in the hand. This is especially the case with the great toe, which has 
 
 Fig. 189. — Skeleton of the foot, internal border. (Poirier and Charpy.) 
 
 to assist in supporting the body, and is therefore constructed with greater solidity; 
 it lies parallel with the other toes, and has a very limited degree of mobility, 
 whereas the thumb, which is occupied in numerous and varied movements, is 
 constructed in such a manner as to permit of great mobility. Its metacarpal bone 
 
 SECOND CUNEIFORM 
 
 SECOND METATARSAL 
 
 Fig. 190. — Skeleton of the foot, external border. (Poirier and Charpy.) 
 
 is directed away from the others, so as to form an acute angle with the second, 
 and it enjoys a considerable range of motion at its articulation with the carpus. 
 The foot is placed at right angles to the leg — a position which is almost peculiar 
 to man, and has relation to the erect position which he maintains. In order to 
 allow of its supporting the weight of the whole body in this position with the 
 least expenditure of material, it is constructed in the form of an arch. This 
 antero-posterior or longitudinal arch is made up of two unequal limbs. The 
 
CONSTRUCTION OF THE FOOT AS A WHOLE 255 
 
 hinder one, which is made up of the os calcis and the posterior part of the 
 astragahis, is about half the length of the anterior limb, and measures about 
 three inches. The anterior limb consists of the rest of the tarsal and the meta- 
 tarsal bones, and measures about seven inches. It may be said to consist of two 
 parts, an inner segment made up of the head of the astragalus, the scaphoid, 
 the three cuneiform, and the three inner metatarsal bones; and an outer segment 
 composed of the os calcis, the cuboid, and the two outer metatarsal bones. The 
 summit of the arch is at the superior articular surface of the astragalus; and its 
 tw^o extremities — that is to say, the two piers on which the arch rests in standing 
 — are the tubercles on the under surface of the os calcis posteriorly, and the heads 
 of the metatarsal bones anteriorly. The weakest part of the arch is the joint 
 between the astragalus and scaphoid, and here it is more liable to yield in those 
 who are overweighted, and in those in whom the ligaments which complete and 
 preserve the arch are relaxed. This weak point in the arch is braced on its con- 
 cave surface by the inferior calcaneo-scaphoid ligament, which is more elastic 
 than most other ligaments, and thus allows the arch to yield from jars or shocks 
 applied to the anterior portion of the foot and quickly restores it to its pristine 
 condition. This ligament is supported internally by blending with the Deltoid 
 ligament, and inferiorly by the tendon of the Tibialis posticus muscle, which is 
 spread out into a fan-shaped insertion, and prevents undue tension of the ligament 
 or such an amount of stretching as would permanently elongate it. 
 
 In addition to this longitudinal arch the foot presents a transverse axch, at the 
 anterior part of the tarsus and hinder part of the metatarsus. This, however, can 
 scarcely be described as a true arch, but presents more the character of a half- 
 dome. The inner border of the central portion of the longitudinal arch is elevated 
 from the ground, and from this point the bones arch over to the outer border, 
 w^hich is in contact with the ground, and, assisted by the longitudinal arch, pro- 
 duce a sort of rounded niche on the inner side of the foot, which gives the appear- 
 ance of a transverse as well as a longitudinal arch. 
 
 The line of the foot, from the point of the heel to the toes, is not quite straight, 
 but is directed a little outward, so that the inner border is a little convex and the 
 outer border concave. This disposition of the bones becomes more marked when 
 the longitudinal arch of the foot is lost, as in the disease known under the name 
 of "flat-foot." 
 
 Surface Form.— On the dorsum of the foot the individual bones are not to be distinguished 
 with the exception of the head of the astragalus, which forms a rounded projection in front of 
 the ankle-joint when the foot is forcibly extended. The whole surface forms a smooth convex 
 outline, the summit of which is the ridge formed by the head of the astragalus, the scaphoid, 
 the middle cuneiform, and the second metatarsal bones; from this it gradually inclines outward 
 and more rapidly inward. On the inner side of the foot, the internal tuberosity of the OS Calcis 
 and the ridge separating the inner from the posterior surface of the bone may be felt most poste- 
 riorly. In front of this, and below the internal malleolus, may be felt the projection of the 
 sustentaculum tali. Passing forward is the well-marked tuberosity of the scaphoid bone, situ- 
 ated about an inch or an inch and a quarter in front of the internal malleolus. Further toward 
 the front, the ridge formed by the base of the first metatarsal bone can be obscurely felt, and 
 from this the shaft of the bone can be traced to the expanded head articulating with the base 
 of the first phalanx of the great toe. Immediately beneath the base of this phalanx, the internal 
 sesamoid bone is to be felt. Lastly, the expanded ends of the bones forming the last joint of 
 the great toe are to be felt. On the outer side of the foot the most posterior bony point is the 
 outer tuberosity of the os calcis, with the ridge separating the posterior from the outer surface 
 of the bone. In front of this the greater part of the external surface of the os calcis is subcu- 
 taneous; on it, below and in front of the extern^,! malleolus, may be felt the peroneal ridge, when 
 this process is present. Farther forward, the base of the fifth metatarsal bone forms a prom- 
 inent and well-defined landmark, and in front of this the shaft of the bone, with its expanded 
 head, and the base of the first phalanx may be defined. The sole of the foot is almost entirely 
 covered by soft parts, so that but few bony parts are to be made out, and these somewhat 
 obscurely. The hinder part of the under surface of the os calcis and the heads of the metatarsal 
 
256 THE SKELETON 
 
 bones, with the exception of the first, which is concealed by the sesamoid bones, may be recog- 
 nized. 
 
 Surgical Anatomy. — Considering the injuries to which the foot is subjected, it is surpris- 
 ing how seldom the tarsal bones are fractured. This is no doubt due to the fact that the tarsus 
 is composed of a number of bones, articulated by a considerable extent of surface and joined 
 together by very strong ligaments, which serve to mitigate the intensity of violence applied to this 
 part of the body. When fracture does occur, these bones, being composed for the most part 
 of a soft cancellous structure, covered only by a thin shell of compact tissue, are often extensively 
 comminuted, especially as most of the fractures are produced by direct violence. As the bones 
 have only a very scanty amount of soft parts over them, fractures are very often compound, and 
 amputation is frequently necessary. 
 
 When fracture occurs in the anterior group of tarsal bones, it is almost invariably the result 
 of direct violence; but fractures of the posterior group, that is, of the calcaneum and astrag- 
 alus, are most frequently produced by falls from a height on to the feet; though fracture of the 
 OS calcis may be caused by direct violence or by muscular action. The posterior part of the 
 bone, that is, the part behind the articular surfaces, is almost always the seat of the fracture, 
 though some few cases of fracture of the sustentaculum tali and of vertical fracture between 
 the two articulating facets have been recorded. The neck of the astragalus, being the weakest 
 part of the bone, is most frequently fractured, though fractures may occur in any part and 
 almost in any direction, either associated or not with fracture of other bones. 
 
 In cases of club-foot, especially in congenital cases, the bones of the tarsus become altered 
 in shape and size, and displaced from their proper positions. This is especially the case in con- 
 genital equino-varus, in which the astragalus, particularly about the head, becomes twisted and 
 atrophied, and a similar condition may be present in the other bones, more especially the sca- 
 phoid. The tarsal bones are peculiarly liable to become the seat of tuberculous caries, and this 
 condition may arise after comparatively trivial injuries. There are several reasons to account 
 for this. They are composed of a delicate cancellated structure, surrounded by intricate synovial 
 membranes. They are situated at the farthest point from the central organ' of the circulation 
 and exposed to vicissitudes of temperature; and, moreover, on their dorsal surface are thinly 
 clad with soft parts which have but a scanty blood-supply. And finally, after slight injuries, 
 they are not maintained in a condition of rest to the same extent as structures suffering from 
 similar injuries in some other parts of the body. Caries of the calcaneus or astragalus 
 may remain limited to the one bone for a long period, but when one of the other bones is 
 affected, the remainder frequently become involved, in consequence of the disease spreading 
 through the large and complicated synovial membrane which is more or less common to these 
 bones. 
 
 Amputation of the whole or a part of the foot is frequently required either for injury or 
 disease. The principal amputations are as follows: (1) Syme's : amputation at the ankle-joint 
 by a heel-flap, with removal of the malleoli and a thin slice from the lower end of the tibia. 
 (2) Roux's : amputation at the ankle-joint by a large internal flap. (3) Pirogoff's amputa- 
 tion .• removal of the whole of the tarsal bones, except the posterior part of the os calcis.. A thin 
 slice is sawn from the tibia and fibula, including the two malleoli. The sawn surface of the os 
 calcis is then turned up and united to the similar surface of the tibia. (4) Subastragaloid 
 amputation : removal of the foot below the astragalus through the joint between it and the os 
 calcis. This operation has been modified by Hancock, who leaves the posterior third of the os 
 calcis and turns it up against the denuded surface of the astragalus. This latter operation is of 
 doubtful utility and is rarely performed. (.5) ChopaH's or medio-tarsal : removal of the ante- 
 rior part of the foot with all the tarsal bones except the os calcis and astragalus; disarticula- 
 tion being effected through the astragalo-scaphoid and calcaneo-cuboid joints. (6) Lisfrancs : 
 amputation of the anterior part of the foot through the tarso-metatarsal joints. This was 
 modified by Hey, who disarticulated through the joints of the four outer metatarsal bones with 
 the tarsus, and sawed off the projecting internal cuneiform; and by Skey, who sawed off the base 
 of the second metatarsal bone and disarticulated the others. 
 
 The bones of the tarsus occasionally require removal individually. This is especially the 
 case with the astragalus and os calcis for disease limited to the one bone, or again the astragalus 
 may require excision in cases of subastragaloid dislocation, or, as recommended by M.r Lund, 
 m cases of inveterate talipes. The cuboid has been removed for the same reason by Mr. Solly, 
 cut the latter two operations have fallen into disuse, and have been superseded bv resection 
 ot a wedge-shaped piece of bone from the outer side of the tarsus. Finally, Mickulicz and 
 Watson have devised operations for the removal of more extensive portions of the tarsus. 
 Mickuhcz s operation consists in the removal of the os calcis and astragalus, along with the 
 articular surfaces of the tibia and fibula, and also of the scaphoid and cuboid. The remain- 
 ing portion of the tarsus is then brought into contact with the sawn surfaces of the tibia and 
 fabula, and fixed there. The result is a position of the shortened foot resembling talipes 
 equinus. Watsons operation is adapted to those cases where the disease is confined to the 
 anterior tarsal bones. By two lateral incisions he saws through the bases of the metatarsal 
 
SESAMOID BONES 
 
 257 
 
 bones in front and opens up the joints between the scaphoid and astragalus, and the cuboid and 
 OS calcis, and removes the intervening bones. 
 
 Fractures of the metatarsal bones and phalanges are nearly always due to direct violence, and 
 in many cases the injury is the result of severe crushing accidents, necessitating amputation. 
 The metatarsal bones, and especially the metatarsal bone of the great toe, are frequently dis- 
 eased, either in tuberculous subjects or in perforating ulcer of the foot. 
 
 Sesamoid Bones (Ossa Sesamoidea) (Figs. 191, 192). 
 
 These are small rounded masses, cartilaginous in early life, osseous in the adult, 
 which are developed in those tendons which exert a great amount of pressure upon 
 the parts over which they glide. It is said that they are more commonly found in 
 the male than in the female, and in persons of an active muscular habit than in 
 those who are weak and debilitated. They are invested throughout their whole 
 surface by the fibrous tissue of the tendon in which they are found, excepting upon 
 that side which lies in contact with the part over which they play, where they 
 present a free articular facet. They may be divided into two kinds: those which 
 glide over the articular surfaces of the joints, and those which play over the cartilag- 
 inous facets found on the surfaces of certain bones. 
 
 Fig. 191. — Sesamoid bones of the hand. (Poirier 
 and Charpy.) 
 
 Fig. 192. — Sesamoid bones of the 
 foot. (Poirier and Charpy.) 
 
 The sesamoid bones of the joints in the upper extremity are two on the palmar 
 surface of the metacarpo-phalangeal joint in the thumb, developed in the tendons 
 of the Flexor brevis poUicis; one on the palmar surface of the interphalangeal 
 joint of the thumb; occasionally one or two opposite the metacarpo-phalangeal 
 articulations of the fore and little fingers; and, still more rarely, one opposite 
 the same joints of the third and fourth fingers. In the lower extremity, the 
 patella, which is developed in the tendon of the Quadriceps extensor; two 
 small sesamoid bones, found in the tendons of the flexor brevis hallucis, opposite 
 the metatarso-phalangeal joint of the great toe; one sometimes over the inter- 
 phalangeal joint of the great toe; and occasionally one in the metatarso-phalan- 
 geal joint of the second toe, the little toe, and, still more rarely, the third and 
 fourth toes. 
 
 17 
 
258 THE SKELETON 
 
 Those found in the tendons which glide over certain bones occupy the following 
 situations: one sometimes found in the tendon of the Biceps cubiti, opposite the 
 tuberosity of the radius: one in the tendon of the Peroneus longus, where it glides 
 through the groove in the cuboid bone; one appears late in life in the tendon of the 
 Tibialis anticus, opposite the smooth facet of the internal cuneiform bone; one is 
 found in the tendon of the Tibialis posticus, opposite the inner side of the head 
 of the astragalus; one in the outer head of the Gastrocnemius, behind the outer 
 condyle of the femur; and one in the conjoined tendon of the Psoas and Iliacus, 
 where it glides over the Os pubis. Sesamoid bones are found occasionally in the 
 tendon of the Gluteus maximus, as it passes over the great trochanter, and in 
 the tendons which wind round the inner and outer malleoli. 
 
THE AKTIOULATIONS OR JOINTS. 
 
 THE various bones of which the Skeleton consists are connected together at 
 different parts of their surfaces, and such a connection is designated by the 
 name of joint or articulation. Arthrology is the branch of anatomy which treats of 
 the joints. If the joint is immovable, as between the cranial and most of the 
 facial bones, the adjacent margins of the bones are applied in almost close con- 
 tact, a thin layer of fibrous membrane, the sutural ligament, and, at the base of 
 the skull, in certain situations, a thin layer of cartilage, being interposed. Where 
 slight movement is required, combined with great strength, the osseous surfaces 
 are united by tough and elastic fibro -cartilages, as in the joints between the 
 vertebral bodies and interpubic articulations; but in the movable joints the bones 
 forming the articulation are generally expanded for greater convenience of mutual 
 connection, covered by cartilage, held together by strong bands or capsules of 
 fibrous tissue called ligaments, and partially lined by a membrane, the synovial 
 membrane, which secretes a fluid to lubricate the various parts of which the joint 
 is formed; so that the structures which enter into the formation of a joint are 
 bone, cartilage, fibro-cartilage, ligament, and sjmovial membrane. 
 
 Bone. — Bone constitutes the fundamental element of all the joints. In the 
 long bones the extremities are the parts which form the articulations; they are 
 generally somewhat enlarged, consisting of spongy cancellous tissue, with a thin 
 coating of compact substance. In the flat bones the articulations usually take 
 place at the edges, and, in the short bones, at various parts of their surface. The 
 layer of compact bone which forms the articular surface, and to which the car- 
 tilage is attached, is called the articular lamella. It is of a white color, extremely 
 dense, and varies in thickness. Its structure differs from ordinary bone-tissue 
 in this respect, that it contains no Haversian canals, and its lacunar are much 
 larger than in ordinary bone and have no canaliculi. The vessels of the can- 
 cellous tissue, as they approach the articular lamella, turn back in loops, and 
 do not perforate it; this layer is consequently more dense and firmer than ordinary 
 bone, and is evidently designed to form a firm and unyielding support for the 
 articular cartilage. 
 
 Cartilage. — Cartilage is material which is a transition stage of connective tissue 
 into bone. When boiled it yields chondrin. Cartilage is not vascular and is found 
 in various parts of the body; in adult life chiefly in the joints, in the parietes of 
 the thorax, and in various tubes, which are to be kept permanently open, such as 
 the air passages, nostrils, and ears. In the foetus in an early period the greater part 
 of the skeleton is cartilaginous. As this cartilage is replaced by bone, it is called 
 temporary in contradistinction to that which remains unossified during life, and 
 which is called permanent. Cartilage is divided into: 
 
 1. Hyaline cartilage. 
 
 2. Elastic cartilage. 
 
 3. Fibro-cartilage. 
 
 Hyaline Cartilage. — This structure is found in the nose, larynx, trachea, bronchi, 
 and in symphyses and synchondroses; costal cartilage and epiphyseal cartilage 
 are composed of it, and as articular cartilage (cartilago articularis) it covers joint 
 
 (259) 
 
2G0 ^^^' ARTICULATIONS OB JOINTS 
 
 surfaces. It is a bluish or pearly hued substance, in reality a modified connective 
 tissue, but mych harder than most connective tissues. The investing membrane, 
 the perichondrium, is composed of two layers: an outer fibrous layer which carries 
 blood-vessels and an inner or chondrogenetic layer, which contains cartilage- 
 forming cells (chondroblasts). 
 
 Cartilage does not contain blood-vessels except in regions of very active growth 
 or of ossification. In such regions vessels may be formed. Hyaline cartilage is 
 composed of round or oval cells and intercellular substance. Each cell contains 
 granular protoplasm and a nucleus, and the nucleus contains one or two nucleoli. 
 The cells are placed in the so-called cartilage spaces of the ground substance, and the 
 ground substance immediately surrounding a space is called a cartilage capsule. 
 The cells are placed in groups and near the surface are arranged in rows, and in 
 some regions are flattened by pressure. The intercellular or ground substance 
 (matrix) is an apparently homogeneous and structureless material between the 
 cartilage spaces. By certain methods, however, fibres can be demonstrated in it. 
 These fibrils in general are parallel. In some of the lower animals canals have 
 been demonstrated. In man it has not been proved that canals exist, and it has 
 been suggested that the fibrils act as paths of conduction for nutritive fluid. 
 
 Articular cartilage forms a thin incrustation upon the joint-surfaces of the 
 bones, and its elasticity enables it to break the force of any concussion, while its 
 smoothness affords ease and freedom of movement. It varies in thickness accord- 
 ing to the shape of the articular surface on which it lies; where this is convex the 
 cartilage is thickest at the centre, where the greatest pressure is received; and the 
 reverse is the case on the concave articular surfaces. Articular cartilage appears 
 to derive its nutriment partly from the vessels of the neighboring synovial mem- 
 brane, partly from those of the bone upon which it is implanted. Toynbee has 
 shown that the minute vessel of the cancellous tissue as they approach the articular 
 lamella dilate and form arches, and then return into the substance of the bone. 
 
 The hyaline cartilages, especially in adult and advanced life, are prone to 
 calcify — that is to say, to have their matrix permeated by the salts of lime without 
 any appearance of true bone. The process of calcification occurs also, and still 
 more frequently, according to Rollett, in such cartilages as those of the trachea 
 and in the costal cartilages, which are prone afterward to conversion into true 
 bone. 
 
 Elastic Cartilage. — In this structure there are elastic fibres in the matrix, which 
 fibres at the periphery of the cartilage enter into the perichondrium. Such carti- 
 lage is not blue-white in color, but is a very light yellow, and is not to be regarded 
 as identical with elastic fibrous tissue. Elastic cartilage is found in the epiglottis 
 and the cartilages of the larynx. 
 
 Fibro-cartilage is composed of wliite fibrous tissue and cartilage in varying pro- 
 portions; it is to the first of these two constituents that its flexibility and toughness are 
 chiefly owing, and to the latter its elasticity; the cells are fewer in number, but are 
 possessed of more definite capsules than are those of hyaline cartilage, and they 
 are usually arranged in groups surrounded by small islands of hyaline matrix, 
 which may be concentrically striated. The hyaline islands are separated from 
 one another by bundles of white fibrous tissue that pursue a markedly wavy 
 course. 
 
 Fibro-cartilage is found at the point of insertion of the ligamentum teres into 
 the head of the femur, in the intervertebral disks, in the pubic symphysis, and in 
 the interarticular cartilages. 
 
 The fibro-cartilages admit of arrangement into four groups: interarticular, con- 
 necting, circumferential, and stratiform. 
 
 1. The interarticular fibro-cartilages {menisci') are flattened, fibro-cartilaginous 
 plates, of a round, oval, triangular, or sickle-like form, interposed between the 
 
LIGAMENTS 261 
 
 articular cartilages of certain joints. They are free on both surfaces, thinner 
 toward their centre than at their circumference, and held in position by the attach- 
 ment of their margins and extremities to the surrounding ligaments. The synovial 
 membrane of the joint is prolonged over them a short distance from their attached 
 margins. They are fouiid in the temporo-mandibular, sterno-clavicular, acromio- 
 clavicular, wrist- and knee-joints. These cartilages are usually found in those 
 joints which are most exposed to violent concussion and subject to frequent move- 
 ment. Their use is to maintain the apposition of the opposed surfaces in their 
 various motions; to increase the depth of the articular surfaces and give ease to 
 the gliding movement; to moderate the effects of great pressure and deaden the 
 intensity of the shocks to which the parts may be subjected. Humphry has pointed 
 out that these interarticular fibro-cartilages serve an important purpose in increasing 
 the variety of movements in a joint. Thus, in the knee-joint there are two kinds 
 of motion — viz., angular movement and rotation — although it ijs a hinge joint, in 
 which, as a rule, only one variety of motion is permitted ; the foimer movement takes 
 place between the condyles of the femur and the interarticular cartilage, the latter 
 between the cartilage and the head of the tibia. So, also, in the temporo-man- 
 dibular joint, the upward and downward movement of opening and shutting the 
 mouth takes place between the fibro-cartilage and the jaw-lwne, the grinding 
 movement between the glenoid cavity and the fibro-cartilage, the latter moving 
 with the jaw-bone. 
 
 Interarticular cartilages may divide the joint into two distinct cavities, as in the 
 temporo-maxillary articulation. The periphery of an articular cartilage is attached 
 particularly to the capsule and may also be attached to the non-articular portion 
 of the bone. The semilunar cartilages of the knee resemble tendon more than 
 they do cartilage. The fibres are arranged in dense, more or less parallel bundles, 
 separated by small, scattered hyaline cells, and the disks are attached to the bone 
 by thin layers of hyaline cartilage. 
 
 2. The connecting fibro-cartilages are interposed between the bony surfaces of 
 those joints which admit of only slight mobility, as between the bodies of the 
 vertebrae and between the pubic bones. They form disks which adhere closely to 
 both of the opposed surfaces, antl are composed of concentric rings of fibrous 
 tissue, with cartilaginous laminae interposed, the former tissue predominating 
 toward the circumference, the latter toward the centre. 
 
 3. The circumferential fibro-cartilages consist of a rim of fibro-cartilage, which 
 surrounds the margin of some of the articular cavities, as the cotyloid cavity of 
 the hip and the glenoid cavity of the shoulder; they serve to deepen the articular 
 surface, and to protect its edges. 
 
 4. The stratiform fibro-cartilages are those which form a thin coating to osseous 
 grooves through which the tendons of certain muscles glide. Small masses of 
 fibro-cartilages are developed also in the tendons of some muscles, where they 
 glide over bones, as in tendons of the Peroneus longus and the Tibialis posticus. 
 
 Ligaments. — Ligaments consist of bands of various forms, serving to connect 
 together the articular extremities of l)ones, and are composed mainly of coarse 
 bundles of very dense white fibrous tissue placed parallel with, or closely inter- 
 laced with, one another, and presenting a white, shining, silvery aspect. These 
 bundles are called fasciculi. They are held together by a cement substance 
 containing cells which resemble those of tendon. A ligament is pUant and 
 flexible, so as to allow of the most perfect freedom of movement, but it is 
 strong, tough, and inextensile, so as not readily to yield under the most 
 severely applied force; it is consequently well adapted to serve as the connecting- 
 medium between the bones. Some ligaments consist entirely of yellow elastic 
 tissue {elastic fibrous tissue), the elastic fibres branching considerably, but main- 
 taining in general a parallel course. The fibres are in bundles, between which 
 
202 THE ARTICULATIONS OR JOINTS 
 
 areolar connective tissue lies. The ligamenta subflava, which connect together 
 the adjacent arches of the vertebrae in man and the ligamentum nuchae in the 
 lower animals are composed of yellow elastic tissue. In these cases it will be 
 observed that the elasticity of the ligament is intended to act as a substitute for 
 muscular power. 
 
 Synovial Membranes. — These membranes are serous in character. A synovial 
 membrane consists of loose connecting tissue (subendothelial tissue), containing fat, 
 vessels, and nerves, its inner surface being lined with a single layer of flat endothelial 
 cells. The endothelial cells are polyhedral, and each cell possesses a flattened oval 
 nucleus. The cells are held together by intercellular cement. It is believed by some 
 that little openings occur at intervals in the intercellular cement, but it is held by 
 many that the supposed openings are artifacts. Synovial cavities contain a little 
 fluid. A non-articular synovial membrane does not actually secrete fluid, but it is 
 moistened by lymph which passes through the membrane and into the cavity by 
 osmosis. 
 
 Joint cavities and bursa? communicating with joints contain a characteristic 
 fluid which is a secretion of the membrane. It is yellowish-white or slightly red- 
 dish, somewhat cloudy, viscid like the white of an egg, having a strongly alkaline 
 reaction and a slightly saline taste. It consists of fats, salts, albumins, extract- 
 ives from lymph, a mucinous body known as S3moviii,^ and another mucin-like 
 body, which is rich in phosphorus (Simon). The nature of synovin is uncertain, 
 but it is neither a nucleo-albumin nor a mucin (Simon). The second mucin-like 
 body is probably a nucleo-albumin (Simon). The quantitative composition of 
 synovial fluid varies with motion and rest (Frerichs, Simon). During exercise the 
 mucin-like bodies, the albumins, and the extractives increase, and the salts and 
 water diminish.^ The synovial membranes found in the body admit of sub- 
 division into three kinds — articular, bursal, and vaginal. 
 
 Articular Synovial Membrane. — Articular synovial membrane is found in every 
 freely movable joint. It lines the capsule of the joint and is reflected upon the 
 non-articular intracapsular portion of the bones which enter into the formation 
 of the joint. In the fcetus this membrane is said, by Toynbee, to be continued 
 over the surface of the cartilages; but in the adult it merely encroaches for a 
 short distance upon the margins of the cartilages, to which it is firmly attached; 
 it then invests the inner surface of the capsular or other ligaments enclosing the 
 joint, and is reflected over the surface of any tendons passing through its cavity, as 
 the tendon of the Popliteus in the knee and the tendon of the Biceps in the 
 shoulder. Hence the articular synovial membrane may be regarded as a short 
 wide tube, attached by its open ends to the margins of the articular cartilages, and 
 covering the inner surface of the various ligaments which connect the articular 
 surfaces, so that along with the cartilages it completely encloses the joint-cavity. 
 In some of the joints the synovial membrane is thrown into folds, which pass 
 across the cavity. They are called synovial ligaments, and are especially distinct in 
 the knee. In some joints there are flattened folds, subdivided at their margins into 
 fringe-like processes (synovial villi) , the vessels of which have a convoluted arrange- 
 ment. These latter generally project from the synovial membrane near the margin 
 of the cartilage and lie flat upon its surface. They consist of connective tissue cov- 
 ered with endothelium, and contain fat-cells in variable quantities, and, more rarely, 
 isolated cartilage-cells. The larger folds often contain considerable quantities of 
 fat. They were described by Clopton Havers as mucilaginous glands, and as the 
 source of the synovial secretion. Under certain diseased conditions similar pro- 
 cesses are found covering the entire surface of the synovial membrane, forming a 
 
 ' Simon's Physiological Chemistry. 
 
 ' Frerichs' analysis, in Simon's Physiological Chemistry. 
 
SYNOVIAL MEMBRANES 
 
 263 
 
 mass of pedunculated fibro-fatty growths which project into the joint. Similar 
 structures are also found in some of the bursal and vaginal synovial membranes. 
 
 Bursal Synovial Membrane. — The bursal synovial membranes are sacs inter- 
 posed between surfaces which move upon each other, producing friction, as in the 
 gliding of a tendon or of the integument over projecting bony surfaces. There are 
 two groups of synovial bursae designated according to situation : 1. Those situated 
 between the integument and a prominent process of bone. Such a bursa is called 
 a subcutaneous synovial bursa {bursa mucosa subcutanea) (Fig. 246). Subcuta- 
 neous bursa' are found between the integument and the front of the patella, 
 over the olecranon, the malleoli, and other prominent parts. 2. Those situated 
 between tendons or muscles and the bony or cartilaginous surfaces over which 
 the tendons or nmscles glide (Figs. 193 and 194). Such a bursa is called a 
 
 Fig. 193. 
 
 -Scheme of a serous bursa. 
 and Charpy.) 
 
 (Poirier 
 
 Fig. 194. 
 
 C SUBTENDINOUS J 
 BURSA J 
 
 -Scheme of a serous bursa. (Poirier 
 and Charpy.) 
 
 subtendinous synovial bursa {bursa mucosa subtendinea) . For example, a bursa 
 is placed between the Glutei muscles and the surface of the great trochanter. 
 Subtendinous bursae are found often about joints and not unusually communicate 
 directly with the cavity of the joint by means of an opening in the joint capsule, 
 the synovial membrane of the joint being continuous with the synovial mem- 
 brane of the bursa. For instance, the bursa between the tendon of the Psoas 
 and Iliacus muscles and the capsular ligament of the hip communicates with 
 the hip-joint; and the bursa between the under surface of the Subscapularis 
 muscle and the neck of the scapula communicates with the shoulder-joint. 
 Bursae consist of a thin wall of connective tissue, partially covered by patches 
 of cells, and contain a viscid fluid. 
 
 Vaginal Synovial Membrane (Fig. 326). — A vaginal synovial membrane (52/rioi;iaZ 
 sheath, thecal synovial bursa, vagina mucosa tendinis) serves to facilitate the gliding 
 of a tendon in the osseo-fibrous canal through which it passes. The membrane 
 is here arranged in the form of a sheath, one laver of which adheres to the wall 
 of the canal, and the other is reflected upon the surface of the contained tendon, 
 the space between the two free surfaces of the membrane containing synovia. 
 These sheaths are chiefly found surrounding the tendons of the Flexor and Ex- 
 tensor muscles of the fingers and toes as they pass through the osseo-fibrous 
 canals in the hand or foot. A vaginal sheath covers the long head of the biceps 
 muscle from its origin to the surgical neck of the humerus (Fig. 222). 
 
 Pads of adipose tissue {synovial fat pads) are found in certain joints between 
 the synovial membrane and the surface beneath it. These pads fill up certain 
 joint intervals, and by adapting themselves to changes of position maintain the 
 form of the joint during movement. 
 
 The articulations are divided into three classes: synarthrosis, or immovable; 
 amphiarthrosis, or mixed; and diarthrosis, or movable joints. 
 
264 'THE ARTICULATIONS OB JOINTS 
 
 Synarthrosis (Immovable Articulation). 
 
 Synarthrosis includes all those articulations in which the surfaces of the bones 
 are in almost direct contact, being fastened together by an intervening mass of 
 connective tissue, and in which there is no joint cavity and no appreciable motion. 
 Examples of synarthrosis are the joints between the bones of the cranium and 
 of the face, excepting those of the lower jaw. The varieties of synarthrosis are 
 four in number: sutura, schindylesis, gomphosis, and synchondrosis. 
 
 Sutura. — Sutura (a seam) is that form of articulation met with only in the 
 skull, where the contiguous margins of flat bones are apparently but not really 
 in immediate contact, a thin layer of fibrous tissue, sutural membrane, being 
 interposed. This membrane is continuous externally with the pericranium and 
 internally with the dura mater. In some of the sutures the sutural membrane 
 gradually disappears as age advances and the two bones form an osseous fusion. 
 Where the articulating surfaces are connected by a series of processes and inden- 
 tations interlocked together, it is termed a tme suture or sutura vera, of which there 
 are three varieties: sutura dentata, serrata, and limbosa. The sutura dentata {dens, 
 a tooth) is so called from the tooth-like form of the projecting articular processes, 
 as in the suture between the parietal bones. In the sutura serrata (serra, a saw) 
 the edges of the two bones forming the articulation are serrated like the teeth 
 of a fine saw, as between the two portions of the frontal bone. In the sutura 
 limbosa (limbus, a selvage), besides the dentated processes, there is a certain 
 d agree of bevelling of the articular surfaces, so that the bones overlap one another, 
 as in the suture between the parietal and frontal bones. When the articulation 
 is formed by roughened surfaces placed in apposition with one another, it is 
 termed the false suture (sutura notha), of which there are two kinds: the sutura 
 squamosa {squama, a scale), formed by the overlapping of two contiguous bones 
 by broad bevelled margins, as in the squamo-parietal (squamous) suture; and 
 the sutura harmonia {kpixovla, a joining together), where there is simple apposition 
 of two contiguous, rough, bony surfaces, as in the articulation between the two 
 superior maxillary bones or of the horizontal plates of the palate bones. 
 
 Schindylesis. — Schindylesis {ayivdbhjotz, a fissure) is that form of articulation 
 in which a thin plate of bone is received into a cleft or fissure formed })y the sep- 
 aration of two laminae in another bone, as in the articulation of the rostrum of the 
 sphenoid and perpendicular plate of the ethmoid with the vomer, or in the recep- 
 tion of the latter in the fissure between the superior maxillary and palate bones. 
 
 Gomphosis. — Gomphosis {yofupo!^, a nail) is an articulation formed by the 
 insertion of a conical process into a socket, as a nail is driven into a board; this 
 is not illustrated by any articulation between bones, properly so called, but is 
 seen in the articulation of the teeth with the alveoli of the maxillary bones. 
 
 Synchondrosis. — Where the connecting medium is cartilage the joint is termed 
 a synchondrosis. This is a temporary form of joint, because the hyaline cartilage 
 becomes converted into bone before adult life. wSuch a joint is found between 
 the epiphyses and shafts of long bones. Another example of a synchondrosis is 
 the occipito-sphenoid articulation. 
 
 Amphiarthrosis (Mixed Articulation). 
 
 In this form of articulation the contiguous osseous surfaces may be connected 
 together by broad flattened disks of fibro-cartilage, of a more or less complex 
 structure, which adhere to the end of each bone, as in the articulation between 
 the bodies of the vertebrae and the pubic symphyses. This is termed symphysis. 
 In a symphysis there is a partial joint cavity which may exhibit an incomplete 
 synovial membrane. Each constituent bone is coated with hyaline cartilage and 
 
DIARTHBOSIS 265 
 
 the bones are held together by Hgaments and intervening fibro-cartilage. The 
 bony surfaces of an amphiarthrodial joint may be united by an interosseous hga- 
 ment, as in the inferior tibio-fibular articulation. To such an articulation the 
 term syndesmosis is applied. A mixed articulation permits limited motion. 
 
 Diarthrosis (Movable Articulation). 
 
 This form of articulation includes the greater number of the joints in the body, 
 mobility being their distinguishing character. They are formed by the approxi- 
 mation of two contiguous bony surfaces covered with cartilage, connected by 
 ligaments and lined by synovial membrane. The varieties of joints in this class 
 have been determined by the kind of motion permitted in each. There are two 
 varieties in which the movement is uniaxial; that is to say, all movements take 
 place around one axis. In one form, the ginglymus or hinge-joint, this axis is, 
 practically speaking, transverse; in the other, the trochoid or pivot-joint, it is 
 longitudinal. There are two varieties where the movement is biaxial or around 
 two horizontal axes at right angles to each other or at any intervening axis 
 between the two. These are the condyloid-joint and the saddle-joint. There is 
 one form of joint where the movement is polyaxial, the enarthrosis or ball-and- 
 socket joint. And finally there are the arthrodia or gliding joints. In a diarthrosis 
 there is always a joint cavity lined with synovial membrane — the articular sur- 
 faces of the bones are covered with hyaline cartilage and the bones are held in 
 contact by ligaments. 
 
 Ginglymus or Hinge-joint {yiyfAoiioz, a hinge). — In this form of joint the 
 articular surfaces are moulded to each other in such a manner as to permit motion 
 only in one plane, forward and backward ; the extent of motion at the same time 
 being considerable. The direction which the distal bone takes in this motion is 
 never in the same plane as that of the axis of the proximal bone, and there is 
 always a certain amount of alteration from the straight line during flexion. The 
 articular surfaces are connected together by strong lateral ligaments, which form 
 their chief bond of union. The most perfect forms of ginglymus are the inter- 
 phalangeal joints and the joint between the humerus and ulna; the knee and 
 ankle are less perfect, as they allow a slight degree of rotation or lateral move- 
 ment in certain positions of the limb. 
 
 Trochoid or Pivot-joint or Rotary-joint. — Where the movement is limited to 
 rotation, the joint is formed by a pivot-like process turning within a ring, or the 
 ring on the pivot, the ring being formed partly of bone, partly of ligament. In 
 the superior radio-ulnar articulation the ring is formed partly by the lesser sig- 
 moid cavity of the ulna; in the rest of its extent, by the orbicular ligament; here 
 the head of the radius rotates within the ring. In the articulation of the odontoid 
 process of the axis with the atlas the ring is formed in front by the anterior arch 
 of the atlas; behind, by the transverse ligament; here the ring rotates round the 
 odontoid process. 
 
 Condyloid or Biaxial Articulation. — In this form of joint an ovoid articular 
 head, or condyle, is received into an elliptical cavity in such a manner as to per- 
 mit of flexion and extension, adduction and abduction and circumduction, but 
 no axial rotation. The articular surfaces are connected together by anterior, 
 posterior, and lateral ligaments. An example of this form of joint is found in 
 the wrist. 
 
 Articulation by Reciprocal Reception or Saddle-joint. — In this variety the 
 articular surfaces are concavo-convex; that is to say, they are inversely convex in 
 one direction and concave in the other. The movements are the same as in the 
 preceding form; that is to say, there is flexion, extension, adduction, abduction, 
 and circumduction, but no axial rotation. The articular surfaces are connected 
 
266 
 
 THE ARTICULATIONS OR JOINTS 
 
 by a capsular ligament. The best example of this form of joint is the carpo- 
 metacarpal joint of the thumb. 
 
 Enarthrosis, or Ball-and-socket-joint, is that form of joint in which the distal 
 bone is capable of motion around an indefinite number of axes which have one 
 common centre. It is formed by the reception of a globular head into a deep 
 cup-like cavity (hence the name "ball-and-socket"), the parts being kept in 
 apposition by a capsular ligament strengthened by accessory ligamentous bands. 
 Examples of this form of articulation are found in the hip and shoulder. 
 
 Arthrodia. — Arthrodia is that form of joint which admits of a gliding move- 
 ment; it is formed by the approximation of plane surfaces or one slightly concave, 
 the other slightly convex, the amount of motion between them being limited by 
 the ligaments, or osseous processes, surrounding the articulation; as in the articu- 
 lar processes of the vertebrae, the carpal joints, except that of the os magnum 
 with the scaphoid and semilunar bones, and the tarsal joints with the exception 
 of the joint between the astragalus and the scaphoid. 
 
 Below, in tabular form, are the names, distinctive characters, and examples 
 of the different kinds of articulations. 
 
 The Kinds of Movement Admitted in Joints. 
 
 The movements admissible in joints may be divided into four kinds: gliding, 
 angular movement, circumduction, and rotation. These movements are often, 
 however, more or less combined in the various joints, so as to produce an infinite 
 variety, and it is seldom that we find only one kind of motion in any particular joint. 
 
 D entata, having 
 tooth-like processes. 
 
 As in interparietal 
 suture. 
 
 Serrata, havinsf ser- 
 rated edges like the 
 teeth of a saw. 
 
 As in interfrontal 
 suture. 
 
 L imbosa, having 
 bevelled margins and 
 dentated processes. 
 
 As in fronto-parie- 
 tal suture. 
 
 Squamosa, formed 
 by thin bevelled mar- 
 gins, overlapping each 
 other. 
 
 As in squamo-parie- 
 
 Synarthrosis, or 
 Immovable Joint. 
 Surfaces separated 
 by fibrous mem- 
 brane or by line 
 of cartilage, with- 
 out any interven- 
 ing synovial 
 cavity, and im- 
 movably con- 
 nected with each 
 other. 
 
 As in joints of 
 cranium and face 
 (except lower 
 jaw). 
 
 Sutura. Ar- 
 ticulation by 
 processes and 
 indentations 
 i nterlocked 
 together. 
 
 Sutura vera 
 (true), articulate 
 by indented bor- 
 ders. 
 
 Sutur a notha 
 (false), articulate^ tal suture 
 by rough surfaces. //armo/n'a, formed by 
 the apposition of con- 
 tiguous rough surfaces. 
 As in intermaxillary 
 ^ suture. 
 
 Schindylesis. — Articulation formed by the reception of a 
 thin plate of one bone into a fissure of another. 
 
 As in articulation of rostrum of sphenoid with vomer. 
 Gomphosis. — Articulation formed by the insertion of a 
 conical process into a socket: the teeth. 
 
THE KIND:^ of 3I0VEMENT ADMITTED IN JOINTS 267 
 
 f Symphysis. — Surfaces connected by fibro-cartilage. There 
 J i-.r • I is a partial joint cavity and may be an incomplete synovial 
 ^ membrane. Mas limited motion. As in joints between 
 
 bodies of vertebrae. 
 
 Syndesmosis. — Surfaces united by an interosseous liga- 
 
 Mixed Articula 
 tion 
 
 < 
 
 Diarthro'sis, 
 Movable Joint. 
 
 Lment. As in the inferior tibio-fibular articulation. 
 
 Ginglymus. — Hinge-joint; motion limited to two directions, 
 forwaid and backward. Articular surfaces fitted together 
 so as to permit of movement in one plane. As in the inter- 
 phalangeal joints and the joint between the humerus and the 
 ulna. 
 
 Trochoides, or Pivot-joint. — Articulation by a pivot process 
 turning within a ring or ring around a pivot. As in superior 
 radio-ulnar articulation and atlanto-axial joint. 
 
 Condyloid.— Ow Old head received into elliptical cavity. 
 Movements in every direction except axial rotation. As the 
 wrist-joint. 
 
 Reciprocal Reception (saddle-joint). — Articular surfaces 
 inversely convex in one direction and concave in the other. 
 Movement in every direction except axial rotation. As in 
 the carpo-metacarpal joint of the thumb. 
 
 Enarthrosis. — Ball-and-socket joint; capable of motion in 
 all directions. Articulations by a globular head received 
 into a cup-like cavity. As in hip- and shoulder-joints. 
 
 Arthrodia. — Gliding joint; articulations by plane surfaces, 
 which glide upon each other. As in carpal and tarsal articu- 
 ^ lations. 
 
 Gliding movement is the most simple kind of motion that can take place in a 
 joint, one surface gliding or moving over another without any angular or rotatory 
 movement. It is common to all movable joints, but in some, as in the articu- 
 lations of the carpus and tarsus, it is the only motion permitted. This movement 
 is not confined to plane surfaces, but may exist between any two contiguous 
 surfaces, of whatever form, limited by the ligaments which enclose the articu- 
 lation. Gliding over a wide range, as is seen in the sliding of the patella over 
 the femur, is called coaptation. 
 
 Angular movement occurs only between the long bones, and by it the angle 
 between the two bones is increased or diminished. It may take place in four 
 directions: forward and backward, constituting flexion or bending and extension 
 or straightening, or inward toward and outward from the mesial line of the body, 
 constituting adduction and abduction. Abduction of a limb is movement away from 
 the mesial fine of the body. Adduction of a limb is movement toward the mesial 
 line of the body. In the fingers and toes the significance of the terms are different; 
 abduction means movement of the fingers away from the middle finger or of the 
 toes away from the second toe; adduction means movement of fingers toward 
 the middle finger or of the toes toward the second toe. The strictly ginglymoid 
 or hinge-joints admit of flexion and extension only. Abduction and adduction, 
 combined with flexion and extension, are met with in the more movable joints; 
 as in the hip-, shoulder-, and metacarpal-joint of the thumb, and partially in 
 the wrist. When two anterior surfaces are brought nearer together, as by 
 bending the elbow or wrist, we speak of the movement as ventral, anterior, or 
 palmar flexion. If two posterior surfaces are brought nearer together, as by 
 bending the knee or wrist, we speak of the movement as posterior or dorsalt 
 flexion. 
 
268 '-^'HE ARTICULATIONS OB JOINTS 
 
 At the wrist-joint the bending of the uhiar margin of the hand toward the 
 ulnar side of the forearm is ulnar flexion; the bending of the radial margin of 
 the hand toward the radial side of the forearm is radial flexion. 
 
 Circumduction is that limited degree of motion which takes place between the 
 head of the bone and its articular cavity, whilst the extremity and sides of the limb 
 are made to circumscribe a conical space, the base of which corresponds with the 
 inferior extremity of the limb, the apex with the articular cavity; this kind of 
 motion is best seen in the shoulder- and hip-joints. 
 
 Rotation is the movement of a bone upon an axis, which is the axis of the pivot 
 on which the bone turns, as in the articulation between the atlas and axis, when 
 the odontoid process serves as a pivot around which the atlas turns; or else is the 
 axis of a pivot-like process which turns within a ring, as in the rotation of the 
 radius upon the humerus. 
 
 Ligamentous Action of Muscles. — The movements of the different joints of 
 a limb are combined by means of the long muscles which pass over more than one 
 joint, and which, when relaxed and stretched to their greatest .extent, act as 
 elastic ligaments in restraining certain movements of one joint, except when 
 combined with corresponding movements of the other, these latter movements 
 being usually in the opposite direction. Thus the shortness of the hamstring 
 muscles prevents complete flexion of the hip, unless the knee-joint is also flexed, 
 so as to bring their attachments nearer together. The uses of this arrangement 
 are threefold: 1. It co-ordinates the kinds of movement which are the most 
 habitual and necessary, and enables them to be performed with the least expendi- 
 ture of power. "Thus in the usual gesture of the arms, whether in grasping or 
 rejecting, the shoulder and the elbow are flexed simultaneously, and simultane- 
 ously extended," in consequence of the passage of the Biceps and Triceps cubiti 
 over both joints. 2. It enables the short muscles which pass over only one joint 
 to act upon more than one. "Thus, if the Rectus femoris remain tonically of 
 such length that, when stretched over the extended hip, it compels extension of 
 the knee, then the Gluteus maximus becomes not only an extensor of the hip, but 
 an extensor of the knee as well." 3. It provides the joints with ligaments which, 
 while they are of very great power in resisting movements to an extent incom- 
 patible with the mechanism of the joint, at the same time spontaneously yield 
 when necessary. "Taxed beyond its strength, a ligament will be ruptured, 
 whereas a contracted muscle is easily relaxed; also, if neighboring joints be 
 united by ligaments, the amount of flexion or extension of each must remain in 
 constant proportion to that of the other; while, if the union be by muscles, the 
 separation of the points of attachment of those muscles may vary considerably 
 in different varieties of movement, the muscles adapting themselves tonically 
 to the length required." The quotations are from a very interesting paper by 
 Dr. Cleland in the Journal of Anatomy and Physiology, No. 1, 1866, p. 85; by 
 whom I believe this important fact in the mechanism of joints was first clearly 
 pointed out, though it has been independently observed afterward by other 
 anatomists. Dr. W. W. Keen points out how important it is "that the surgeon 
 should remember this ligamentous action of muscles in making passive motion — 
 for instance, at the wrist after Colles's fracture. If the fingers be extended, the 
 wrist can be flexed to a right angle. If, however, they be first flexed, as in 'mak- 
 ing a fist,' flexion at the wrist is quickly limited to from 40 to 50 degrees in 
 different persons, and is very painful beyond that point. Hence passive motion 
 here should be made with the fingers extended. In the leg, when flexing the hip, 
 the knee should be flexed." Dr. Keen further points out that "a beautiful illus- 
 tration of this is seen in the perching of birds, whose toes are forced to clasp the 
 perch by just such a passive ligamentous action so soon as they stoop. Hence 
 they can go to sleep and not fall ofi^ the perch." 
 
ARTICULATIONS OF THE VERTEBRAL COLUMN 269 
 
 The articulations may be arranged into those of the trunk, those of the upper 
 extremity, and those of the lower extremity. 
 
 ARTICULATIONS OF THE TRUNK. 
 
 These may be divided into the following groups, viz. : 
 
 I. Of the vertebral column. 
 II. Of the atlas Vv-^ith the axis. 
 III. Of the atlas with the occipital 
 
 l^one. 
 V\ . Of the axis with the occipital bone. 
 V. Of the lower jaw. 
 VI. Of the ribs with the vertebrae. 
 
 VII. Of the cartilages of the ribs with 
 the sternum and with each other. 
 VIII. Of the sternum. 
 IX. Of the vertebral column with the 
 
 pelvis. 
 X. Of the pelvis. 
 
 I. Articulations of the Vertebral Column. 
 
 The different segments of the spine are connected together by spinal ligaments 
 (Ugamenta columnoB vertebraLs) , which may be divided into five sets: 1. Those 
 connecting the bodies of the vertebrae. 2, Those connecting the laminae. 
 3. Those connecting the articular processes. 4. Those connecting the spinous 
 processes. 5. Those of the transverse processes. 
 
 The articulations of the bodies of the vertebras with each other form a series of 
 amphiarthrodial joints; those between the articular processes form a series of 
 arthrodial joints. 
 
 1. The Ligaments of the Vehtebral Bodies or Centra (Intercentral 
 
 Ligaments). 
 
 Anterior Common Ligament (anterior longitudinal ligament). 
 Posterior Common Ligament (posterior longitudinal ligament). 
 Intervertebral Substance (intervertebral disk, fibro-cartilage). 
 
 The Anterior Common or Anterior Longitudinal Ligament (ligamentum longitu- 
 dinale anterius) (Figs. 197, 199, and 203) is a broad and strong band of longi- 
 tudinal fibres which extends along the anterior (ventral) surface of the bodies of 
 the vertebra? from the axis to the sacrum. It is broader below than above, thicker 
 in the dorsal than in the cervical or lumbar regions, and somewhat thicker 
 opposite the front of the body of each vertebra than opposite the intervertebral 
 substance. It is attached, above, to the body of the axis by a pointed process, 
 where it is continuous with the anterior atlanto-axial ligament, is connected 
 with the tendon of insertion of the Longus colli muscle, and extends down as far 
 as the upper bone of the sacrum. It consists of dense longitudinal fibres, which 
 are intimately adherent to the intervertebral substance and the prominent margins 
 of the vertebrae, but less closely to the middle of the bodies. In the latter 
 situation the fibres are exceedingly thick, and serve to fill up the concavities 
 on their front surface and to make the anterior surface of the spine more even. 
 This ligament is composed of several layers of fibres, which vary in length, but 
 are closely interlaced with each other. The most superficial or longest fibres 
 extend between four or five vertebrae. A second subjacent set extends between 
 two or three vertebrae, whilst a third set, the shortest and deepest, extends from 
 one vertebra to the next. At the side of the bodies the ligament consists of a 
 few short fibres, which pass from one vertebra to the next, separated from the 
 median portion by large oval apertures for the passage of vessels. 
 
270 
 
 THE ARTICULATIONS OB JOINTS 
 
 The Posterior Common or Posterior Longitudinal Ligament (ligamentum longi- 
 tudinale posterius) (Figs. 195, 197, 202, and 203) is situated within the spinal 
 canal, and extends along the posterior (dorsal) surface of the bodies of the ver- 
 tebrae from the body of the axis above, where it is continuous with the posterior 
 
 INTERVERTE- 
 BFIAL FIBRO- 
 CARTILAGE 
 
 ROOT OF 
 VERTEBRAL 
 
 Fig. 196. — Intervertebral disk, with the adjacent 
 vertebral bodies, from in front. (Spalteholz.) 
 
 POSTERIOR COMMON 
 LIGAMENT 
 
 Fig. 195. — Vertebral bodies with ligaments, from 
 behind. (Spalteholz.) 
 
 occipito-axial ligament, to the sacrum 
 below. It can be separated from the 
 posterior occipito-axial ligament, as is 
 shown in Fig. 203, and may be regarded 
 as really arising from the clivus. It is 
 broader above than below, and thicker in 
 the dorsal than in the cervical or lumbar 
 regions. In the situation of the intervertebral substance and contiguous margins 
 of the vertebrie, where the ligament is more intimately adherent, it is broad, and 
 presents a series of dentations with intervening concave margins; but it is narrow 
 and thick over the centre of the bodies, from which it is separated by the vense 
 basis vertebrae. This ligament is composed of smooth, shining, longitudinal 
 fibres, denser and more compact than those of the anterior ligament, and formed 
 of a superficial layer occupying the interval between three or four vertebrae, and 
 of a deeper layer which extends between one vertebra and the next adjacent 
 to it. It is separated from the dura mater of the spinal cord by some loose 
 connective tissue, which is very liable to serous infiltration. 
 
 The Intervertebral Fibro-cartilages, Disks, or Substances (fibrocartilagines inter- 
 vertebrales) (Figs. 196 and 197).— Each fibrocartilaginous disk is of lenticular 
 form and of composite structure. The disks are interposed between the adjacent 
 surfaces of the bodies of the vertebrae from the axis to the sacrum, and form 
 the chief bonds of connection between those bones. In young children inter- 
 vertebral substance exists in the coccyx. These disks vary in shape, size, and 
 thickness in different parts of the spine. In shape they accurately correspond 
 with the surfaces of the bodies between which they are placed, being oval in the 
 cervical and lumbar regions, and circular in the dorsal. Their size is greatest 
 in the lumbar region. In thickness they vary not only in the different regions 
 of the spine, but in different parts of the same disk: thus, they are thicker in 
 front than behind in the cervical and lumbar regions, while they are uniformly 
 thick in the dorsal region. The intervertebral disks form about one-fourth of 
 the spinal column, exclusive of the first two vertebrae; they are not equally dis- 
 tributed, however, between the various bones; the dorsal portion of the spine 
 
ARTICULATIONS OF THE VERTEBBAL COLUMN 
 
 271 
 
 having, in proportion to its length, a much smaller quantity than in the cervical 
 and lumbar regions, which necessarily gives to the latter parts greater pliancy 
 and freedom of movement. The intervertebral disks are adherent, by their sur- 
 faces, to a thin layer of hyaline cartilage which covers the upper and under sur- 
 faces of the bodies of the vertebme, and in which, in early life, the epiphysial 
 plate develops, and by their circinnference are closely connected in front to the 
 anterior, and behind to the posterior common ligament; whilst in the dorsal 
 region they are connected laterally, by means of the interarticular ligament, to 
 the heads of those ribs which articulate with two vertebrae; they, consequently, 
 form part of the articular cavities in which the heads of these bones are received. 
 
 POSTERIOR COMMON 
 LIGAMENT 
 
 Fig. 197.- 
 
 - Median section of a piece of the lumbar spinal column, right half of sections viewed from the 
 left. (Spalteholz.) 
 
 Structure of the Intervertebral Substance. — The outer portion of the intervertebral 
 substance is composed of many layers of fibrous connective tissue. This envel- 
 oping portion is called the annulus fibrosus. The central portion of the disk is 
 composed of soft, pulpy, highly elastic fibro-cartilage, containing some bantls of 
 connective tissue. It is called the nucleus pulposus, is of a yellowish color, and 
 rises up considerably above the surrounding level when the disk is divided hori- 
 zontally. This pulpy substance, which is especially well developed in the lumbar 
 region, is the remains of the chorda dorsalis, and, according to Luschka, contains a 
 small synovial cavity in its centre. The outer layers of the disk are arranged con- 
 centrically one within the other, the outermost consisting of ordinary fibrous tissue, 
 but the others and more numerous consisting of white fibro-cartilage. These 
 plates are not quite vertical in their direction, those near the circumference being 
 curved outward and closely approximated; whilst those nearest the centre curve 
 in the opposite direction, and are somewhat more widely separated. The fibres of 
 which each plate is composed are directed, for the most part, obliquely from above 
 downward, the fibres of adjacent plates passing in opposite directions and varying 
 in every layer; so that the fibres of one layer are directed across those of another, 
 like the limbs of the letter X. This laminar arrangement belongs to about the 
 outer half of each disk. The pulpy substance presents no concentric arrangement, 
 and consists of a fine fibrous matrix, containing angular cells, united to form a 
 
272 
 
 THE ARTICULATIONS OR JOINTS 
 
 reticular structure. J. Bland Sutton^ calls attention to the fact that in the human 
 foetus a transverse ligamentous band crosses the dorsal aspect of the intervertebral 
 disk and is continuous with the interosseous ligaments of the heads of the ribs; 
 and also that a foetal ligamentous band exists in the ventral surface of the inter- 
 vertebral disk which, after development, becomes the middle fasciculus of the 
 stellate ligament. These bands are named by Sutton the posterior conjugal 
 ligaments and the anterior conjugal ligaments. 
 
 Interneural Articulations include the ligaments of the laminae; articular 
 processes, spinous processes, and transverse processes. 
 
 2. Ligaments connecting the Lamina. 
 Ligamenta Subflava. 
 
 The Ligamenta Subflava {ligamenta flava, ligamenta intercruralia) (Figs. 197 
 and 198) are interposed between the laminae of the vertebrae, from the axis to 
 the sacrum. They are most distinct when seen from the interior of the spinal 
 canal; when viewed from the outer surface they appear short, being over- 
 lapped by the laminae. Each ligamentum subflavmn consists of two lateral 
 portions, which commence on each side at the root of either articular process, 
 and pass backward to the point where the laminae converge to form the spi- 
 nous process, where their margins are in contact and to a certain extent united; 
 slight intervals being left for the passage of small vessels. These ligaments 
 
 consist of yellow elastic tissue, the 
 fibres of which, almost perpendic- 
 ular in direction, are attached to 
 the anterior surface of the laminae 
 above, some distance from its in- 
 ferior margin, and to the posterior 
 surface, as well as to the margin 
 ,of the lamina below. In the cer- 
 vical region they are thin in tex- 
 ture, but very broad and long; 
 they become thicker in the dorsal 
 region, and in the lumbar acquire 
 very considerable thickness. Their 
 highly elastic property serves to 
 preserve the upright posture and 
 to assist in resuming it after the 
 spine has been flexed. These liga- 
 ments do not exist between the 
 occiput and atlas or between . the 
 atlas and axis. 
 
 3. Ligaments connecting the 
 Articular Processes. 
 
 Capsular Ligaments. 
 
 The Capsular Ligaments (capsidce 
 articidares) (Fig. 198) are thin and 
 loose ligamentous sacs, attached 
 to the contiguous margins of the articulating processes of each vertebra through 
 the greater part of their circumference, and completed internally by the ligamenta 
 
 Fig. 198. 
 
 -Vertebral arches with ligamenta flava. 
 (Spalteholz.) 
 
 1 J. Bland Sutton. Ligaments: Their Nature and Morphology. 
 
ARTICULATIONS OF THE VERTEBRAL COLVMN 273 
 
 subflava. They are longer and looser in the cervical than in the dorsal or lumbar 
 regions. The capsular ligaments are lined on their inner surface by synovial 
 membrane. 
 
 4. Ligaments connecting the Spinous Processes. 
 
 Supraspinous Ligament. Interspinous Ligaments. 
 
 The Supraspinous Ligament {Ugainentum supraspinale) (Fig. 197) is a strong 
 fibrous cord, which connects together the apices of the spinous processes from the 
 seventh cervical to the spinous processes of the sacrum. It is thicker and broader 
 in the lumbar than in the dorsal region, and intimately blended, in both situa- 
 tions, with the neighboring aponeurosis. The most superficial fibres of this 
 ligament connects three or four vertebrae; those deeper-seated pass between two 
 or three vertebra; whilst the deepest connect the contiguous extremities of 
 neighboring vertebrte. It is continued upward to the external occipital protu- 
 berance as the ligamentum nuchse, which, in the human subject, is thin and 
 forms merely an intermuscular septum. 
 
 The Interspinous Ligaments (ligamenta interspinalia) (Fig. 197), thin and 
 membranous, are interposed between the spinous processes. Each ligament 
 extends from the root to the summit of each spinous process and connects together 
 their adjacent margins. They meet the ligamenta subflava in front and the 
 supraspinous ligament behind. They are narrow and elongated in the dorsal 
 region; broader, cjuadrilateral in form, and thicker in the lumbar region; and 
 only slightly developed in the neck. 
 
 5. Liga:ments connecting the Transverse Processes. 
 Intertransverse Ligaments. 
 
 The Intertransverse Ligaments (ligamenta intertransversaria) (Fig. 210) consist 
 of bundles of fibres interposed between the transverse processes. In the cervical 
 region they consist of a few irregular, scattered fibres; in the dorsal, they are 
 rounded cords intimately connected with the deep muscles of the back; in the 
 lumbar region they are thin and membranous. 
 
 Actions. — The movements permitted in the spinal column are, flexion, exten- 
 sion, lateral movement, circwmduction, and rotation. 
 
 In flexion {forward flexion), or movement of the spine forward, the anterior 
 common ligament is relaxed, and the intervertebral substances are compressed 
 in front, while the posterior common ligament, the ligamenta subflava, and the 
 inter- and supra-spinous ligaments are stretched, as well as the posterior fibres 
 of the intervertebral disks. The interspaces between the laminae are widened, 
 and the inferior articular processes of the vertebrae above glide upward upon 
 the articular processes of the vertebrae below. Flexion is the most extensive of 
 all the movements of the spine. 
 
 In extension (backward flexion), or movement of the spine backward, an exactly 
 opposite disposition of the parts takes place. This movement is not extensive, 
 being limited by the anterior common ligament and by the approximation of the 
 spinous processes. 
 
 Flexion and extension are free in the lower part of the lumbar region between 
 the third and fourth and fourth and fifth lumbar vertebne; above the third 
 they are much diminished, and reach their minimum in the middle and upper 
 part of the back. They increase again in the neck, the capability of motion 
 backward from the upright position being in this region greater than that of the 
 motion forward, whereas in the lumbar region the reverse is the case. 
 
 In lateral flexion, the sides of the intervertebral disks are compressed, the 
 extent of motion being limited by the resistance offered by the surrounding liga- 
 
 18 
 
274 '^HE ARTICULATIONS OB JOINTS 
 
 ments and by the approximation of the transverse processes. This movement 
 may take place in any part of the spine, but is most free in the neck and loins. 
 
 Circumduction is very limited, and is produced merely by a succession of the 
 preceding movements. 
 
 Rotation is produced by the twisting of the intervertebral substances; this, 
 although only slight between any two vertebrae, produces a considerable extent of 
 movement when it takes place in the whole length of the spine, the front of the 
 upper part of the column being turned to one or the other side. This movement 
 takes place only to a slight extent in the neck, but is freer in the upper part ot 
 the dorsal region, and is altogether absent in the lumbar region. 
 
 It is thus seen that the cervical region enjoys the greatest extent of each variety 
 of movement, flexion and extension especially being very free. In the dorsal 
 region the three movements of flexion, extension, and circumduction are per- 
 mitted only to a slight extent, while rotation is very free in the upper part and 
 ceases below. In the lumbar region there is free flexion, extension, and lateral 
 movement, but no rotation. 
 
 As Sir George Humphry has pointed out, the movements permitted are mainly 
 due to the shape and position of the articulating processes. In the loins the infe- 
 rior articulating processes are turned outward and are embraced by the superior; 
 this renders rotation in this region of the spine impossible, while there is nothing 
 to prevent a sliding upward and downward of the surfaces on each other, so as to 
 allow of flexion and extension. In the dorsal region, on the other hand, the 
 articulating processes, by their direction and mutual adaptation, especially at the 
 upper part of the series, permit of rotation, but prevent extension and flexion, 
 while in the cervical region the greater obliquity and lateral slant of the articular 
 processes allow not only flexion and extension, but also rotation. 
 
 The principal muscles which produce flexion are the Sterno-mastoid, Rectus 
 capitis anticus major, and Longus coUi; the Scaleni; the abdominal muscles and 
 the Psoas magnus. Extension is produced by the fourth layer of the muscles 
 of the back, assisted in the neck by the Splenius, Semispinalis dorsi et colli, and 
 the Multifidus spinae. Lateral motion is produced by the fourth layer of the 
 muscles of the back, by the Splenius and the Scaleni, the muscles of one side only 
 acting; and rotation by the action of the following muscles of one side only — viz. 
 the Sterno-mastoid, the Rectus capitis anticus major, the Scaleni, the Multifidus 
 spinse, the Complexus, and the abdominal muscles. 
 
 II. Articulation of the Atlas with the Axis (Articulatio Atlantoepistrophica). 
 
 The articulation of the atlas with the axis is of a complicated nature, compris- 
 ing no fewer than four distinct joints. There is a pivot articulation between the 
 odontoid process of the axis and the ring formed between the anterior arch of the 
 atlas and the transverse ligament (see Fig. 201). Here there are two joints: one in 
 front between the posterior surface of the anterior arch of the atlas and the front 
 of the odontoid process, the atlanto-odontoid joint of Cruveilhier; the other between 
 the anterior surface of the transverse ligament and the back of the process, the 
 syndesmo-odontoid joint. Between the articular processes of the two bones there 
 is a double arthrodia or gliding joint. The ligaments which connect these bones 
 are the 
 
 Anterior Atlanto-axial. Transverse. 
 
 Posterior Atlanto-axial. Two Capsular. 
 
 The Anterior Atlanto-axial or the Anterior Atlo-axoid Ligament (Figs. 199 and 203) 
 is a strong, membranous layer, attached, above, to the lower border of the anterior, 
 arch of the atlas; below, to the base of the odontoid process and to the front of 
 
ARTICULATION OF THE ATLAS WITH THE AXIS 
 
 275 
 
 the body of the axis. It is strengthened in the middle Kne by a rounded cord, which 
 is attached, above, to the tubercle on the anterior arch of the atlas, and below to 
 the body of the axis, being a continuation upward of the anterior common liga- 
 ment of the spine. Some anatomists regard this ligament as being a part of the 
 anterior common ligament. The ligament is in relation, in front, with the Recti 
 antici majores. 
 
 The Posterior Atlanto-axial or the Posterior Atlo-axoid Ligament (Figs. 200 and 
 203) is a broad and thin membranous layer, attached, above, to the lower border 
 of the posterior arch of the atlas; below, to the upper edge of the laminae of 
 the axis. This ligament supplies the place of the ligamenta subflava, and is 
 in relation, behind, with the Inferior oblique muscles. 
 
 The Transverse Ligament of the Atlas^ (ligamentum transversum atlantis) (Figs. 
 201, 202, and 203) is a thick, strong band, which arches across the ring of the 
 atlas, and serves to retain the odontoid process in firm connection with its anterior 
 arch. This ligament is flattened from before backward, broader and thicker in 
 the middle than at either extremity, and firmly attached on each side to a small 
 tubercle on the inner surface of the lateral mass of the atlas. As it crosses the 
 odontoid process, a small fasciculus is derived from its upper, and another from 
 its lower, border; the former passing upward, to be inserted into the anterior sur- 
 
 PHARYNGEAL 
 TUBERCLE 
 
 BASILAR PORTION OF 
 CIPITAL BONE 
 
 ANTERIOR OCCIPITO- 
 ATLANTAL LIGAMENT 
 
 ANTERIOR CONDYLOID 
 ORAMEN 
 
 CIPITO-ATLANTAL 
 ICULATION 
 
 TRANSVERSE 
 PROCESS OF 
 ATLAS 
 
 ANTERIOR ATLANTO- 
 AXIAL LIGAMENT 
 
 JOINT BETWEEN 
 
 BODY CF VERTEBRA 
 
 AND INTERVER-. 
 
 TEBRAL FIBRO- 
 
 CARTILAGE 
 
 TRANSVERSE 
 PROCESS OF 
 AXIS 
 
 TRANSVERSE PROCESS 
 OF THIRD CERVICAL 
 VERTEBRA 
 
 INTERVERTEBRAL 
 FIBROCARTILAGE 
 
 ANTERIOR COMMON 
 LIGAMENT 
 
 Fig. 199. — Occipital bone and first three cervical vertebrae with ligaments, from in front. (Spalteholz.) 
 
 face of the foramen magnum of the occipital bone; the latter, downward, to be 
 attached to the posterior surface of the body of the axis; hence, the whole ligament 
 has received the name of cruciform ligament (ligamentum cruciatum atlantis). 
 A synovial surface is interposed between the odontoid process and the trans- 
 verse ligament, and one is placed between the anterior surface of the odontoid 
 process and the anterior arch of the atlas. The transverse ligament divides the 
 
 ' It hasi been found necessary to describe the transverse ligament with those of the atlas and axis; but the 
 student mu.«t remember that it is really a portion of the mechanism by which the movements of the head on the 
 spine are regulated; so that the connections between the atlas and axis ought always to be studied together with 
 those between the latter bones and the skull. 
 
276 THE ARTICULATIONS OB JOINTS 
 
 ring of the atlas into two unequal parts : of these, the posterior and larger serves 
 for the transmission of the cord and its membranes and the spinal accessory 
 nerves ; the anterior and smaller contains the odontoid process. Since the space 
 between the anterior arch of the atlas and the transverse ligament is smaller at 
 the lower part than the upper (because the transverse ligament embraces tightly 
 the narrow neck of the odontoid process), this process is retained in firm connec- 
 tion with the atlas after all the other ligaments have been divided. 
 
 The Capsular Ligaments (capsuloB articulares) (Figs. 199, 200, and 202) are two 
 thin and loose capsules, connecting the lateral masses of the atlas with the superior 
 articular surfaces of the axis, the fibres being strengthened at the posterior and 
 inner part of each articulation by an accessory ligament, which is attached below 
 to the body of the axis near the base of the odontoid process. 
 
 Synovial Membranes (Fig. 201). — There are jour synovial membranes in this 
 articulation: one lining the inner surface of each of the capsular ligaments; one 
 between the anterior surface of the odontoid process and the anterior arch of 
 the atlas, the atlanto-odontoid joint; and one between the posterior surface of 
 the odontoid process and the transverse ligament, the syndesmo-odontoid joint. 
 The latter often communicates with those between the condyles of the occipital 
 bone and the articular surfaces of the atlas. 
 
 Actions. — This joint allows the rotation of the atlas (and, with it, of the cra- 
 nium) upon the axis, the extent of rotation being limited by the odontoid ligaments. 
 
 The principal muscles by which this action is produced are the Sterno-mastoid 
 and Complexus of one side, acting with the Rectus capitis anticus major, Sple- 
 nius, Trachelo-mastoid, Rectus capitis posticus major, and Inferior oblique of the 
 other side. 
 
 ARTICULATIONS OF THE SPINE WITH THE CRANIUM. 
 
 The ligaments connecting the spine with the cranium may be divided into two 
 sets — those connecting the occipital bone with the atlas, and those connecting the 
 occipital bone with the axis. 
 
 III. Articulation of the Atlas with the Occipital Bone (Articulatio 
 
 Atlantooccipitalis) . 
 
 This articulation is a double condyloid joint. Its ligaments are the 
 
 Anterior Occipito-atlantal. Posterior Occipito-atlantal. 
 
 Two Capsular. 
 
 The Anterior Occipito-atlantal Ligament or Membrane (memhrana atlantooccipitalis 
 anterior, anterior occipito-atloid ligament) (Figs. 199 and 203) is a broad membra- 
 nous layer, composed of densely woven fibres, which passes between the anterior 
 margin of the foramen magnum above, and the whole length of the upper border 
 of the anterior arch of the atlas below. Laterally, it is continuous with the cap- 
 sular ligaments. In the middle line in front it is strengthened by a strong, narrow, 
 rounded cord, which is attached, above, to the basilar process of the occiput, and, 
 below, to the tubercle on the anterior arch of the atlas, and which is a continua- 
 tion of the anterior common ligament. This ligament is in relation, in front, 
 with the Recti antici minores; behind, with the odontoid ligaments. 
 
 The Posterior Occipito-atlantal Ligament or Membrane (memhrana atlantooccipitalis 
 posterior, posterior occipito-atloid ligament) (Figs. 200 and 203) is a very broad but 
 thin membranous lamina intimately blended with the dura mater. It is connected, 
 above, to the posterior margin of the foramen magnum ; below, to the upper border 
 
ARTICULATION OF THE ATLAS WITH THE OCCIPITAL BONE 277 
 
 of the posterior arch of the atlas. This hgament is incomplete at each side, and 
 forms, with the superior intervertebral notch, an opening for the passage of the 
 vertebral artery and suboccipital nerve. The fibrous band which arches over the 
 artery and nerve sometimes becomes ossified. The ligaments are in relation, 
 behind, with the Recti postici minores and Obliqui superiores; in front, with the 
 dura mater of the spinal canal, to which they are intimately adherent. 
 
 POSTERIOR OC 
 
 CIPITO-ATLANTA 
 
 LIGAMEN 
 
 POSTERIOR 
 CIPITO-ATLAN 
 LIGAME 
 
 TRANSVERSE 
 PROCESS OF 
 ATLAS 
 
 POSTE 
 AT LAN TO 
 
 Fig. 200. — Occipital bone, first and second cervical vertebra? with ligaments from behind. (Spalteholz.) 
 
 The Capsular Ligaments {capsvloB articvlares) (Fig. 202) surround the condyles 
 of the occipital bone, and connect them with the articular processes of the atlas; 
 they consist of thin and loose capsules, which enclose the synovial membranes 
 of the articulations. 
 
 S3movial Membranes. — There are two synovial membranes in this articulation, 
 one lining the inner surface of each of the capsular ligaments. These occasionally 
 communicate with that between the posterior surface of the odontoid process and 
 the transverse lisament. 
 
 Fig. 201. — Articulation between odontoid process and atlas. 
 
 Actions. — The movements permitted in this joint are flexion and extension, 
 which give rise to the ordinary forward and backward nodding of the head. Slight 
 lateral motion to one or the other side may also take place. When either of these 
 actions is carried beyond a slight extent, the whole of the cervical portion of the spine 
 assists in its production. Flexion is mainly produced by the action of the Rectus 
 capitis anticus major et minor and the Sterno-mastoid muscles; extension by the 
 
278 
 
 THE ARTICULATIONS OR JOINTS 
 
 Rectus capitis posticus major et minor, the Superior oblique, the Complexus, Sple- 
 nius, and upper fibres of the Trapezius. The Recti laterales are concerned in the 
 lateral movement, assisted by the Trapezius, Splenius, Complexus, and the Sterno- 
 mastoid of the same side, all acting together. According to Cruveilhier, there is 
 a slight motion of rotation in this joint. 
 
 rV. Articulation of the Axis with the Occipital Bone. 
 The ligaments of this articulation are the 
 
 Occipito-axial. Three Odontoid. 
 
 To expose these ligaments the spinal canal should be laid open by removing 
 the posterior arch of the atlas, the laminae and spinal process of the axis, and the 
 portion of the occipital bone behind the foramen magnum, as seen in Fig. 192. 
 
 The Posterior Occipito-axial Ligament (posterior occipito-axoid ligament , membrana 
 tedoria, apparatus ligamentosus colli) (Figs. 202 and 203) is situated within the spinal 
 canal. It is a broad, strong band, w^hich covers the odontoid process and its liga- 
 ments, and appears to be a prolongation upward of or a membrane due to fusion 
 with the posterior common ligament of the spine. It is attached, below, to the 
 posterior surface of the body of the axis, and, becoming expanded as it ascends, 
 is inserted into the basilar groove of the occipital bone, in front of the foramen 
 magnum, where it becomes blended with the dura mater of the skull. 
 
 Tfie vertical portion of 
 
 ODONTOID LIQAWENTS. 
 
 CAPSULAR LIGAMENT 
 
 and synovial 
 membrane. 
 
 fCAPSULAR LIGAMENT 
 
 (. membrane. 
 
 Fig. 202. — Occipito-axial and atlanto-axial ligaments. Posterior view, obtained by removing the arches of 
 the vertebrce and the posterior part of the skull. 
 
 Relations. — By its anterior surface with the transverse ligament; by its posterior 
 surface with the posterior common ligament. 
 
 The Lateral Odontoid or Check Ligaments (ligamenta alaria) (Figs. 202 and 203) 
 are strong, rounded, fibrous cords, which arise one on either side of the upper 
 part of the odontoid process, and, passing obliquely upward and outward, are 
 inserted into the rough depressions on the inner side of the condyles of the 
 
ARTICULATION OF THE AXIS WITH THE OCCIPITAL BONE 279 
 
 occipital bone. In the triangular interval left between these ligaments another 
 strong fibrous cord, ligamentum suspensorium, or middle odontoid ligament {liga- 
 mentum apicis dentis), may be seen, which passes almost perpendicularly from 
 the apex of the odontoid process to the anterior margin of the foramen mag- 
 num, being intimately blended with the deep portion of the anterior occipito- 
 atlantal ligament and upper fasciculus of the transverse ligament of the atlas. 
 
 Actions. — The odontoid ligaments serve to limit the extent to which rotation 
 of the cranium may be carried; hence, they have received the name of check 
 ligaments. 
 
 In addition to these ligaments, which connect the atlas and axis to the skull, 
 the ligamentum nuchse must be regarded as one of the ligaments by which the 
 spine is connected with the cranium. It is described on page 273. 
 
 Surgical Anatomy. — The ligaments which unite the component parts of the vertebrae 
 together are so strong, and these bones are so interlocked by the arrangement of their articu- 
 lating processes, that dislocation is very uncommon, and, indeed, unless accompanied by fracture, 
 seldom occurs, except in the upper part of the neck. Dislocation of the occiput from the atlas 
 
 THIN LAYER OF POSTERIOR COMMON 
 LIGAMENT SEPARATED FROM THE 
 POSTERIOR OCCIPITO-AXIAL LIGAMENT 
 
 HYPOGLOSSAL 
 NERVE 
 
 ANTERIOR OCCIPITO- 
 ATLOID LIGAMENT 
 
 POSTERIOR OCCIPITO- 
 AXIAL LIGAMENT 
 CRUCIFORM 
 
 LIGAMENT i j 
 MIDDLE ODONTOID 
 LIGAMENT 
 
 ANTERIOR ARCH 
 OF ATLAS 
 ODONTOID PROC- 
 ESS OF AXIS 
 ARTICULAR 
 CAVITY 
 TRANSVERSE LIGA 
 MENT OF ATLAS 
 
 ANTERIOR ATLO- 
 AXOID LIGAMENT 
 
 intervertebral 
 fibro-cartilage" 
 
 ANTERIOR COMMON 
 LIGAMENT' 
 
 . B Q O^l^' 
 
 POSTERIOR COMMON 
 LIGAMENT 
 
 Fig. 203. — Median section through the occipital bone and first three cervical vertebrae with ligaments. 
 
 (Spalteholz.) 
 
 has only been recorded in one or two cases ; but dislocation of the atlas from the axis, with rup- 
 ture of the transverse ligament, is much more common: it is the mode in which death is produced 
 in many cases of execution by hanging. Occipito-atloid dislocation is certainly fatal. Recoveries 
 are on record after atlo-axoid dislocation. Immediate death occurs if the transverse ligament 
 is torn or the odontoid process is broken. In the lower part of the neck — that is, below the 
 third cervical vertebra — dislocation unattended by fracture occasionally takes place. 
 
280 
 
 THE ARTICULATIONS OB JOINTS 
 
 V. Articulation of the Lower Jaw, or the Temporo-mandibular Articulation 
 
 (Articulatio Mandibularis). 
 
 This is a ginglymo-arthrodial joint: the parts entering into its formation on 
 each side are, above, the anterior part of the glenoid cavity of the temporal bone 
 and the eminentia articularis; and, below, the condyle of the lower jaw. The 
 ligaments are the following: 
 
 External liateral. Stylo-mandibular. 
 
 Internal Lateral. Capsular. 
 
 Interarticular Fibro-cartilage. 
 
 The External Lateral Ligament {ligamentum temporomandibulare) (Fig. 204) is a 
 short, thin, and narrow fasciculus, attached, above, to the outer surface of the zygoma 
 and to the tubercle on its lower border; below, to the outer surface and posterior 
 border of the neck of the lower jaw. It is broader above than below; its fibres are 
 
 Fig. 204. — Temporo-mandibular articulation. 
 
 placed parallel with one another, and directed obliquely downward and backward. 
 Externally, it is covered by the parotid gland and by the integument. Internally 
 it is in relation with the capsular ligament, of which it is an accessory band, and 
 from which it is not separable. 
 
 The Internal Lateral Ligament (ligamentum sphenomandibulare) (Fig. 205) is a 
 flat, thin band which is attached above to the spinous process of the sphenoid 
 bone, and, becoming broader as it descends, is inserted into the margin of the 
 mandibular or dental fofamen and the portion of bone, the lingula, which over- 
 hangs the foramen in front. Its outer surface is in relation, above, Avith the 
 External pterygoid muscle; lower down it is separated from the neck of the 
 condyle by the internal maxillary artery; and still more inferiorly, the inferior 
 dental vessels and nerve separate it from the ramus of the jaw. The inner surface 
 is in relation with the Internal pterygoid. It is really the fibrous covering of a 
 part of Meckel's cartilage. 
 
ARTICULATION OF THE LOWER JAW 
 
 281 
 
 Fig. 205. — Temporo-mandibular articulation. Internal view 
 
 The Stylo-mandibulax or Stylo -maxillary Ligament {ligamentum stylomandihulare) 
 (Fig. 205) is a specialized band of the cervical fascia, which extends from near the 
 apex of the styloid process of the temporal bone to the angle and posterior border 
 of the ramus of the lower jaw, between the Masseter and Internal pterygoid mus- 
 cles. This ligament separates the parotid from the submaxillary gland, and has 
 attached to its inner side part of 
 the fibres of origin of the Stylo- 
 glossus muscle. Although usually 
 classed among the ligaments of the 
 jaw, it can be considered only as 
 an accessory to the articulation. 
 
 The Capsular Ligament (capsida 
 articularis) (Figs. 204 and 205) 
 forms a thin and loose capsule, 
 passing from the circumference of 
 the glenoid cavity and the articular 
 surface immediately in front to the 
 upper margin of the articular disk, 
 and from the lower margin of the 
 articular disk to the neck of the 
 condyle of the lower jaw. It con- 
 sists of very thin fibres, and is com- 
 plete. It forms two joint cavities, 
 distinct from each other, and sepa- 
 rated by the articular disk. So 
 thin is it that it is hardly to be 
 considered as a distinct ligament; it is thickest at the back part, and thinnest 
 on the inner side of the articulation.* 
 
 The Interarticular Fibro-cartilage or Meniscus (discus articularis) (Fig. 206) is a 
 thin plate of an oval form, placed horizontally between the condyle of the jaw and 
 
 the glenoid cavity. Its upper surface 
 is concavo-convex from before back- 
 ward, and a little convex transversely, 
 to accommodate itself to the form of 
 the glenoid cavity. Its under surface, 
 where it is in contact with the con- 
 dyle, is concave. Its circumference is 
 connected to the capsular ligament, 
 and in front to the tendon of the Ex- 
 ternal pterygoid muscle. It is thicker 
 at its circumference, especially be- 
 hind, than at its centre. The fibres 
 of which it is composed have a con- 
 centric arrangement, more apparent 
 at the circumference than at the 
 centre. Its surfaces are smooth. It divides the joint into two cavities, each 
 of which is furnished with a separate synovial membrane from the capsular 
 ligament. 
 
 Synovial Membranes (Fig. 206) . — The synovial membranes, two in number, are 
 placed, one above, and the other below, the fibro-cartilage. The upper one, the 
 larger and looser of the two, is continued from the margin of the cartilage covering 
 
 Fig. 206. — Vertical section of temporo-mandibular 
 articulation. 
 
 ' Sir G. Humphry describes the internal portion of the capsular lijjament .separately as the short internal lateral 
 ligament: and it certainly seems as deserving of a separate description as is the external lateral ligament. 
 
282 THE ARTICULATIONS OB JOINTS 
 
 the glenoid cavity and eminentia articularis on to the upper surface of the fibro- 
 cartilage. The lower one passes from the under surface of the fibro-cartilage to 
 the neck of the condyle of the jaw, being prolonged downward a little farther 
 behind than in front. The interarticular cartilage is sometimes perforated in its 
 centre; the two synovial sacs then communicate with each other. 
 
 The nerves of this joint are derived from the auriculo-temporal and masseteric 
 branches of the inferior maxillary. The arteries are derived from the temporal 
 branch of the external carotid. 
 
 Actions. — The movements possible in this articulation are very extensive. Thus, 
 the jaw may be depressed or elevated, or it may be carried forward or backward. 
 It must be borne in mind that there are two distinct joints in this articula- 
 tion — that is to say, one between the condyle of the jaw and the interarticular 
 fibro-cartilage, and another between the fibro-cartilage and the glenoid fossa; 
 when the jaw is depressed, as in opening the mouth, the movements which take 
 place in these two joints are not the same. In the lower compartment, that between 
 the condyle and the fibro-cartilage, the movement is of a ginglymoid or hinge-like 
 character, the condyle rotating on a transverse axis on the fibro-cartilage; while in 
 the upper compartment the movement is of a gliding character, the fibro-cartilage, 
 together with the condyle, gliding forward on to the eminentia articularis. These 
 two movements take place simultaneously — the condyle and fibro-cartilage move 
 forward on the eminence, and at the same time the condyle revolves on the fibro- 
 cartilage. In the opposite movement of shutting the mouth the reverse action takes 
 place; the fibro-cartilage glides back, carrying the condyle with it, and this at the 
 same time revolves back to its former position. When the jaw is carried horizon- 
 tally forward, as in protruding the lower incisors in front of the upper, the move- 
 ment takes place principally in the upper compartment of the joint: the fibro- 
 cartilage, carrying with it the condyle, glides forward on the glenoid fossa. This 
 is because this movement is mainly effected by the External pterygoid muscles, 
 which are inserted into both condyle and interarticular fibro-cartilage. The grind- 
 ing or chewing movement is produced by the alternate movement of one condyle, 
 with its fibro-cartilage, forward and backward, while the other condyle moves 
 simultaneously in the opposite direction; at the same time the condyle undergoes a 
 vertical rotation on its own axis on the fibro-cartilage in the lower compartment. 
 One condyle advances and rotates, the other condyle recedes and rotates, in alter- 
 nate succession. 
 
 The lower jaw is depressed by its own weight, assisted by the Platysma, the 
 Digastric, the Mylo-hyoid, and the Genio-hyoid muscles. It is elevated by the 
 anterior part of the Temporal, Masseter, and Internal pterygoid. It is drawn for- 
 ward by the simultaneous action of the External pterygoid and the superficial fibres 
 of the Masseter; and it is drawn backward by the deep fibres of the Masseter and 
 the posterior fibres of the Temporal muscle. The grinding movement is caused by 
 the alternate action of the two External pterygoids. 
 
 Surface Form. — The temporo-mandibular articulation is quite superficial, situated below the 
 base of the zygoma, in front of the tragus and external auditory meatus, and behind the poste- 
 rior border of the upper part of the Masseter muscle. Its exact position can be at once ascer- 
 tained by feehng for the condyle of the jaw, the working of which can be distinctly felt in the 
 movements of the lower jaw in opening and shutting the mouth. When the mouth is opened 
 wide, the condyle advances out of the glenoid fossa on to the eminentia articularis, and a depres- 
 sion is felt in the situation of the joint. 
 
 Surgical Anatomy.— Genuine dislocation of the lower jaw is always forward. Croker, 
 Kmg, and Theim, however, have reported posterior displacement. Dislocation is caused by 
 violence or muscular action. When the mouth is open, the condyle is situated on the eminentia 
 articularis, and any sudden violence, or even a sudden muscular spasm, as during a convulsive 
 yawn, may displace the condyle forward into the zygomatic fossa. The displacement may be 
 unilateral or bilateral, according as one or both of' the condyles are displaced. The latter of 
 
ARTICULATIONS OF THE BIBS WITH THE VERTEBRA 283 
 
 the two is the more common. The interarticular fibro-cartilage adheres to the condyle till it 
 passes over the eminentia articularis, but at this point remains behind. 
 
 Sir Astley Cooper described a condition which he termed "subluxation." It occurs princi- 
 pally in delicate women, and is believed by some to be due to the relaxation of the ligaments, 
 permitting too free movement of the bone. Others believe it is due to displacement of the inter- 
 articular fibro-cartilage. Still others attribute the symptoms to gouty or rheumatic changes in 
 the joint. In close relation to the condyle of the jaw is the external auditory meatus and the 
 tympanum; any force, therefore, applied to the bone is liable to be attended with damage to 
 these parts, or inflammation in the joint may extend to the ear, or on the other hand inflam- 
 mation of the middle ear may involve the articulation and cause its destruction, thus leading 
 to ankylosis of the joint. In children, arthritis of this joint may follow the exanthemata, and 
 in adults it occurs as the result of some constitutional conditions, as rheumatism or gout. The 
 temporo-mandibular joint is also occasionally the seat of osteo-arthritis, leading to great suffer- 
 ing during efforts of mastication. A peculiar affection sometimes attacks the neck and condyle 
 of the lower jaw, consisting in hypertrophy and elongation of these parts and consequent protru- 
 sion of the chin to the opposite side. 
 
 VI. Articulations of the Ribs with the Vertebrse or the Costo-vertebral 
 Articulations (Articulationes Costovertebrales). 
 
 The articulations of the ribs with the vertebral column may be divided into 
 two sets: 1. Those which connect the heads of the ribs with the bodies of the 
 vertebrae; costo-central. 2. Those which connect the necks and tubercles of the 
 ribs with the transverse processes; costo-transverse. 
 
 1. Articulations between the Heads of the Ribs and the Bodies of 
 THE Vertebra or the Costo-central Articulations (Articu- 
 lationes Capitulorum) (Figs. 207 and 208). 
 
 These constitute a series of arthrodial joints, formed by the articulation of the 
 heads of the ribs with the cavities on the contijiuous margins of the bodies of the 
 
 FOVEA COSTALIS 
 TRANSVERSALIS 
 
 rNTCRVERTEBRAL 
 FIBROCARTILAGC 
 
 Fig. 207. — Spinal column with ligament, from in front. (Spalteholz.) 
 
284 
 
 THE ARTICULATIONS OB JOINTS 
 
 INTEBARTICULAR LIGA- 
 MENT OF HEAD OF RIB 
 
 dorsal vertebrae and the intervertebral substance between them, except in the case 
 of the first, tenth, eleventh, and twelfth ribs, where the cavity is formed by a single 
 vertebra. The bones are connected by the following ligaments: 
 
 Anterior Costo-vertebral or Stellate. 
 Capsular. Interarticular. 
 
 The Anterior Costo-vertebral or Stellate Ligament {ligamentum capitvli costcB radi- 
 atum) (Figs. 207 and 210) connects the anterior part of the head of each rib with the 
 sides of the bodies of two vertebrae and the intervertebral disk between them. It 
 consists of three flat bundles of ligamentous fibres, which are attached to the ante- 
 rior part of the head of the rib, just beyond the articular surface. The superior 
 
 fibres pass upward to be con- 
 nected with the body of the 
 vertebra above; the inferior 
 one descends to the body of 
 the vertebra below; and the 
 middle one, the smallest and 
 least distinct, passes horizon- 
 tally inward, to be attached 
 to the intervertebral sub- 
 stance. 
 
 Relations. — In front, with 
 the thoracic ganglia of the 
 sympathetic, the pleura, and, 
 on the right side, with the vena 
 azygos major; behind, with 
 the interarticular ligament 
 and synovial membranes. 
 
 On the first rib, which 
 articulates with a single ver- 
 tebra, this ligament does not 
 present a distinct division 
 into three fasciculi ; its fibres, 
 however, radiate, and are at- 
 tached to the body of the last cervical vertebra, as well as to the body of the 
 vertebra with which the rib articulates. In the tenth, eleventh, and twelfth ribs 
 also, which likewise articulate with a single vertebra, the division does not exist; 
 but the fibres of the ligament in each case radiate and are connected with the 
 vertebra above, as well as that with which the ribs articulate. 
 
 The Capsular Ligament (capsula articularis) is a thin and loose ligamentous bag, 
 which surrounds the joint between the head of the rib and the articular cavity 
 formed by the intervertebral disk and the adjacent vertebra. It is very thin, 
 firmly connected with the anterior ligament, and most distinct at the upper and 
 lower parts of the articulation. Behind, some of its fibres pass through the inter- 
 vertebral foramen to the back of the intervertebral disk. This is the analogue of 
 the ligamentum conjugale of some mammals, which unites the heads of opposite 
 ribs across the back of the intervertebral disk. 
 
 The Interarticular Ligament {ligamentum capituli costce interarticulare) (Figs. 208 
 and 209) is situated in the interior of the joint. It consists of a short band of 
 fibres, flattened from above downward, attached by one extremity to the sharp 
 crest which separates the two articular facets on the head of the rib, and by the 
 other to the intervertebral disk. It divides the joint into two cavities, which 
 have no communication with each other. In the first, tenth, eleventh, and 
 
 Fig. 208.— Ribs and corresponding vertebral bodies with their 
 ligaments, viewed from the right. (Spalteholz.) 
 
ARTICULATIONS OF THE BIBS WITH THE VEBTEBBjE 285 
 
 twelfth ribs the interarticular ligament does not exist; consequently there is but 
 one synovial membrane. 
 
 Synovial Membranes (Figs. 208 and 209). — There are hoo synovial membranes 
 in each of the articulations in which there is an interarticular hgament, one on 
 each side of this structure. 
 
 2. Articulations of the Necks and Tubercles of the Ribs with the 
 
 Transverse Processes or the Costo-transverse Articulations 
 
 (Articulationes Costotransversari^) (Fig. 209). 
 
 The articular portion of the tubercle of the rib and adjacent transverse process 
 form an arthrodial joint. 
 
 In the eleventh and twelfth ribs this articulation is wanting. 
 The ligaments connecting these parts are the 
 
 Anterior Superior Costo-transverse. 
 Middle Costo-transverse (Interosseous). 
 
 Posterior Costo-transverse 
 Capsular. 
 
 The Anterior Superior or Long Costo-traiisverse Ligament (ligamentum costo- 
 transversarium anterius) (Figs. 207,208,209, and 210) consists of two sets of fibres: 
 the one (anterior) is attached below to the sharp crest on the upper border 
 
 Fig. 209. — Costo-transverse articulation. Seen from above. 
 
 of the neck of each rib, and passes obliquely upward and outward to the lower 
 border of the transverse process immediately above; the other (posterior) is 
 attached below to the neck of the rib, and passes upward and inward to the base 
 of the transverse process and outer border of the lower articular process of the 
 vertebra above. This ligament is in relation, in front, with the intercostal vessels 
 and nerves; behind, with the Longissimus dorsi muscle. Its internal border is 
 thickened and free, and bounds an aperture through which pass the posterior 
 branches of the intercostal vessels and nerves. Its external border is continuous 
 with a thin aponeurosis which covers the External intercostal muscle. 
 
 The first rib has no anterior costo-transverse ligament. In the twelfth rib the 
 ligament is absent or is a mere vestige. 
 
286 
 
 THE ARTICULATIONS OB JOINTS 
 
 ARTICULAR SURFACE 
 
 FOR TUBCRCLE W 
 OF RIB 
 
 ANTERIOR 
 COSTO-TRANS- 
 VERSE LIGAMENT 
 INTERTRANS- 
 VERSE LIGAMENT 
 
 5 SUPERIOR ARTICULAR 
 .n SURFACE FOR HEAD 
 
 INTERVERTE- 
 BRAL FIBRO- 
 CARTILAGE 
 
 The Middle Costo-transverse or Interosseous Ligament (ligamentum colli costoe) 
 (Fig. 209) consists of short but strong fibres which pass between the rough sur- 
 face on the posterior part of the neck of each rib and the anterior surface of the 
 adjacent transverse process. In order fully to expose this ligament, a horizontal 
 section should be made across the transverse process and corresponding part of 
 the rib; or the rib may be forcibly separated from the transverse process and the 
 fibres of the ligament put on the stretch. 
 
 In the eleventh and twelfth ribs this ligament is quite rudimentary or wanting. 
 
 The Posterior Costo-transverse Ligament (ligamentumcostotransversarium posterius) 
 
 (Fig. 209) is a short but thick and strong fasciculus which passes obliquely from the 
 
 summit of the transverse 
 *'^^'^' process to the rough non- 
 
 articular portion of the 
 tubercle of the rib. This 
 ligament is shorter and 
 more oblique in the upper 
 than in the lower ribs. 
 Those corresponding to 
 the superior ribs ascend, 
 while those of the inferior 
 ribs descend slightly. 
 
 In the eleventh and 
 twelfth ribs this ligament 
 is wanting. 
 
 The Capsular Ligament 
 (capsula articularis) is a 
 thin, membranous sac at- 
 tached to the circumfer- 
 ence of the articulari sur- 
 faces, and enclosing a 
 small synovial membrane. 
 In the eleventh and 
 twelfth ribs this ligament 
 is absent. 
 
 Actions. — The heads of 
 the ribs are so closely 
 connected to the bodies 
 of the vertebrae by the 
 stellate and interarticular 
 ligaments, and the necks 
 and tubercles of the ribs to the transverse processes, that only a slight sliding 
 movement of the articular surfaces on each other can take place in these articula- 
 tions. The result of this gliding movement with respect to the six upper ribs con- 
 sists in an elevation of the front and middle portion of the rib, the hinder part 
 being prevented from performing any upward movement by its close connection 
 with the spine. In this gliding movement the rib rotates on an axis corresponding 
 with a line drawn through the two articulations, costo-central and costo-transverse, 
 which the rib forms with the spine. With respect to the seventh, eighth, ninth, and 
 tenth ribs, each one, besides rotating in a similar manner to the upper six, also 
 rotates on an axis corresponding with a line drawn from the head of the rib to the 
 sternum. By the first movement — that of rotation of the rib on an axis correspond- 
 ing with a line drawn through the two articulations which this bone forms with 
 the spine — an elevation of the anterior part of the rib takes place, and a consequent 
 enlargement of the antero-posterior diameter of the chest. None of the ribs lie in 
 
 Fig. 
 
 INFERIOR ARTICULAR 
 SURFACE FOR HEAD 
 OF RIB 
 INFERIOR ARTIC- 
 ULAR PROCESS 
 
 210. — Ribs and corresponding vertebrae with ligaments, viewed 
 from the right. (Spalteholz.) 
 
ARTICULATION OF CARTILAGES OF BIBS WITH STEBNUM 287 
 
 a truly horizontal plane; they are all directed more or less obliquely, so that their 
 anterior extremities lie on a lower level than their posterior, and this obliquity 
 increases from the first to the seventh, and then again decreases. If we examine 
 any one rib — say, that in which there is the greatest obliquity— we shall see that 
 it is obvious that as its sternal extremity is carried upward, it must also be thrown 
 forward ; so that the rib may be 
 regarded as a radius moving on 
 the vertebral joint as a centre, and 
 causing the sternal attachment to 
 describe an arc of a circle in the 
 vertical plane of the body. Since 
 all the ribs are oblique and con- 
 nected in front to the sternum by 
 the elastic costal cartilages, they 
 must have a tendency to thrust 
 the sternum forward, and so in- 
 crease the antero-posterior diam- 
 eter of the chest. By the second 
 movement — that of the rotation 
 of the rib on an axis correspond- 
 ing with a line drawn from the 
 head of the rib to the sternum — 
 an elevation of the middle portion 
 of the rib takes place, and conse- 
 quently an increase in the trans- 
 verse diameter of the chest. For 
 the ribs not only slant downward 
 and forward from their vertebral 
 attachment, but they are also ob- 
 lique in relation to their transverse 
 plane — that is to say, their middle 
 is on a lower level than either 
 their vertebral or sternal extremi- 
 ties. It results from this that when 
 the ribs are raised, the centre por- 
 tion is thrust outward, somewhat 
 after the fashion in which the 
 handle of a bucket is thrust away 
 from the side when raised to a 
 horizontal position, and the lateral 
 diameter of the chest is increased 
 (see Fig. 21 1). The mobility of the different ribs varies very much. The first rib 
 is more fixed than the others, on account of the weight of the upper extremity and 
 the strain of the ribs beneath ; but on the freshly dissected thorax it moves as freely 
 as the others. From the same causes the movement of the second rib is also not 
 very extensive. In the other ribs this mobility increases successively down to the 
 last two, which are very movable. The ribs are generally more movable in the 
 female than in the male. 
 
 VII. Articulation of the Cartilages of the Ribs with the Sternum, etc., or 
 
 the Costo-stemal Articulations (Articulationes 
 
 Stemocostales) (Fig. 212). 
 
 The articulations of the cartilages of the true ribs with the sternum are arthro- 
 dial joints, with the exception of the first, in which the cartilage is almost always 
 
 Fig. 211. — Diagrams showing the axis of rotation of the 
 ribs in the movements of respiration. The one axis of rota- 
 tion corresponds with the line drawn through the two articu- 
 lations which the rib forms with the spine (a, b), and the other 
 with a line drawn from the head of the rib to the sternum 
 {A, B). (From Kirke's Handbook of Physiology.) 
 
288 THE ARTICULATIONS OR JOINTS 
 
 directly united with the sternum, and which must therefore be regarded as a 
 synarthrodia! articulation. The ligaments connecting them are the 
 
 Anterior Chondro-sternal. Capsular. 
 
 Posterior Chondro-sternal. Interarticular Chondro-sternal. 
 
 Chondro-xiphoid. 
 
 The Anterior Chondro-sternal or Stemo-costal Ligament (ligamentum sternocostale 
 radiatum) (Fig. 212) is a broad and thin membranous band that radiates from 
 the front of the inner extremity of the cartilages of the true ribs to the anterior 
 surface of the sternum. It is composed of fasciculi which pass in different direc- 
 tions. The superior fasciculi ascend obliquely, the inferior fasciculi pass obliquely 
 downward, and the middle fasciculi pass horizontally. The superficial fibres of this 
 ligament are the longest: they intermingle with the fibres of the ligaments above 
 and below them, with those of the opposite side, and with the tendinous fibres of 
 origin of the Pectoralis major, forming a thick fibrous membrane which covers 
 the surface of the sternum {memhrana sterni). This is more distinct at the lower 
 than at the upper part. According to the modern nomenclature, this ligament 
 and the posterior chondro-sternal ligament are called ligamenta stemocostalia 
 radiata. The two chondro-sternal ligaments form a sheath for the sternum 
 anteriorly and posteriorly, the membrana sterni. 
 
 The Posterior Chondro-sternal or Stemo-costal Ligament {ligamentum sterno- 
 costale radiatum), less thick and distinct than the anterior, is composed of fibres 
 which radiate from the posterior surface of the sternal end of the cartilages of 
 the true ribs to the posterior surface of the sternum, becoming blended with the 
 periosteum. 
 
 The Capsular Ligament (capsida articidaris) surrounds the joint formed between 
 the cartilage of a true rib and the sternum. It is very thin, intimately blended 
 with the anterior and posterior Hgaments, and strengthened at the upper and lower 
 part of the articulation by a few fibres which pass from the cartilage to the side 
 of the sternum. These ligaments protect the synovial membranes. 
 
 The Interarticular Chondro-sternal or Sterno-costal Ligament {ligamentum sterno- 
 costale interarticuLare) (Fig, 212). — This is found between the second costal car- 
 tilage and the sternum. The cartilage of the second rib is connected with the 
 sternum by means of an interarticular ligament attached by one extremity to the 
 cartilage of the second rib, and by the other extremity to the cartilage which unites 
 the first and second pieces of the sternum. This articulation is provided with tioo 
 synovial membranes. The cartilage of the third rib is also connected with the ster- 
 num by means of an interarticular ligament which is attached by one extremity to 
 the cartilage of the third rib, and by the other extremity to the point of junction 
 of the second and third pieces of the sternum. This articulation may be provided 
 with two synovial membranes. In the other joints interarticular ligaments may 
 exist, but they rarely completely divide the joint into two cavities. 
 
 The Anterior Chondro-xiphoid or Costo-xiphoid Ligament {ligamentum costo- 
 xiphoidea) (Fig. 212). — This is a band of ligamentous fibres which connects 
 the anterior surface of the seventh costal cartilage, and occasionally also that 
 of the sixth, to the anterior surface of the ensiform appendix. It varies in 
 length and breadth in different subjects. A similar band of fibres on the inter- 
 nal or posterior surface, though less thick and distinct, may be demonstrated. 
 It is spoken of as the posterior chondro-xiphoid or costo-xiphoid ligament. 
 
 Synovial Membranes (Fig. 212). — There is no synovial membrane between the 
 first costal cartilage and the sternum, as this cartilage is directly continuous with 
 the sternum. There are two synovial membranes, both in the articulation of the 
 second and third costal cartilages to the sternum. There is generally one syno- 
 vial membrane in each of the joints between the fourth, fifth, sixth, and seventh 
 
ARTICULATION OF CARTILAGES OF RIBS WITH STERNUM 289 
 
 costal cartilages to the sternum; but it is sometimes absent in the sixth and 
 seventh chondro-sternal joints. Thus there are usually eight synovial cavities on 
 each side in the articulations between the costal cartilages of the true ribs and 
 the sternum. After middle life the articular surfaces lose their polish, become 
 
 Fig. 212. — Sternum and ribs with ligaments, from in front. In the left half of the figure the most anterior 
 layer has been removed and the joint sUts have been opened ; the parts are separated somewhat from one 
 another on the left side. (Spalteholz.) 
 
 roughened, and the synovial membranes appear to be wanting. In old age the 
 articulations do not exist, the cartilages of most of the ribs becoming continuous 
 with the sternum. 
 
 Actions. — The movements which are permitted in the chondro-sternal articu- 
 lations are limited to elevation and depression, and these only to a slight extent. 
 
 Articulations of the Cartilages of the Ribs with Each Other or the Inter- 
 chondral Articulations (articidationes interchondrales) (Fig. 212). — The con- 
 
 19 
 
290 THE ARTICULATIONS OB JOINTS 
 
 tiguous borders of the sixth, seventh, and eighth, and sometimes the ninth and 
 tenth, costal cartilages articulate with each other by small, smooth, oblong-shaped 
 facets. Each articulation is enclosed in a thin capsular ligament lined by syno- 
 vial membrane, and strengthened externally and internally by ligamentous fibres, 
 external and internal interchondral ligaments {ligamenta intercostalia externa et 
 interna), which pass from one cartilage to the other. Sometimes the fifth costal 
 cartilao-e, more rarely that of the ninth, articulates, by its lower border, with the 
 adjoining cartilage by a small oval facet; more frequently they are connected 
 too-ether by a few ligamentous fibres. Occasionally the articular surfaces above 
 mentioned are wanting. 
 
 Articulations of the Ribs with their Cartilages or the Costo-chondral 
 Articulations (Fig. 212). — The outer extremity of each costal cartilage is re- 
 ceived into a depression in the sternal ends of the ribs, and the two are held 
 together by the periosteum. There is no real joint. Occasionally a synovial 
 membrane exists between the first rib and the corresponding cartilage. 
 
 VIII. Articulations of the Sternum (Fig. 212). 
 
 The first piece of the sternum is united to the second either by an amphi- 
 arthrodial joint — a single piece of true fibro-cartilage uniting the segments — or 
 by a diarthrodial joint, in which each bone is clothed with a distinct lamina of 
 cartilage, adherent on one side, free and lined with synovial membrane on the 
 other. In the latter case the cartilage covering the gladiolus is continued without 
 interruption on to the cartilages of the second ribs. Mr. Rivington has found the 
 diarthrodial form of joint in about one-third of the specimens examined by him; 
 Mr. Maisonneuve more frequently. It appears to be rare in childhood, and is 
 formed, in Mr. Rivington's opinion, from the amphiarthrodial form by absorption. 
 The diarthrodial joint seems to have no tendency to ossify at any age, while the 
 amphiarthrodial is more liable to do so, and has been found ossified as early as 
 thirty-four years of age. Professor Cunningham^ says : "It is not usual to find the 
 manubri-gladiolar joint obliterated by the ossification of the two bony segments. 
 Even in advanced life it remains open, and the joint partakes of the nature of 
 an amphiarthrosis, although a joint cavity is not found under any circumstances 
 in the plate of fibro-cartilage which intervenes between the manubrium and the 
 gladiolus." The two segments are further connected by an 
 
 Anterior Intersternal Ligament. Posterior Intersternal Ligament. 
 
 The Anterior Intersternal Ligament consists of a layer of fibres, having a longi- 
 .tudinal direction; it blends with the fibres of the anterior chondro-sternal liga- 
 ments on both sides (membrani sterni), and with the tendinous fibres of origin 
 of the Pectoralis major muscle. This ligament is rough, irregular, and much 
 thicker below than above. 
 
 The Posterior Intersternal Ligament is disposed in a somewhat similar manner 
 on the posterior surface of the articulation. 
 
 IX. Articulation of the Vertebral Column with the Pelvis. 
 
 The ligaments connecting the last lumbar vertebra with the sacrum are similar 
 to those which connect the segments of the spine with each other — viz.: 1. The 
 continuation downward of the anterior and posterior common ligaments. 2. The 
 intervertebral substance connecting the flattened oval surfaces of the two bones 
 
 1 Text-book of Anatomy, p. 264. 
 
ARTICULATION OF VERTEBRAL COLUMN WITH PELVIS 291 
 
 and forming an amphiarthrodial joint. 3. Ligamenta subflava, connecting the 
 arch of the last lumbar vertebra with the posterior border of the sacral canal. 
 4. Capsular ligaments connecting the articulating processes and forming a double 
 arthrodia. 5. Inter- and supraspinous ligaments. 
 
 The two proper ligaments connecting the pelvis with the spine are the lumbo- 
 sacral and ilio-lumbar. 
 
 The Lumbo-sacral Ligament (Fig. 213) is a short, thick, triangular fascic- 
 ulus, which is connected above to the lower and front part of the trans- 
 verse process of the last lumbar vertebra, passes obliquely outward, and is 
 attached below to the lateral surface of the base of the sacrum. It is closely 
 blended with the anterior sacro-iliac ligament and with the ilio-lumbar 
 ligament, and is to be regarded as a portion of the ilio-lumbar ligament. 
 This ligament is in relation, in front, with the Psoas muscle. The in- 
 ternal border of the lumbo-sacral ligament margins the foramen of the last 
 lumbar nerve. 
 
 The Ilio-liimbar Ligament (I ig amentum iliolumhale) (Fig. 213) passes horizon- 
 tally outward from the apex of the transverse process of the last lumbar vertebra 
 
 Aperture of communication 
 vnth 
 PSOAS and iliacus. 
 
 Fig. 213. — Articulations of the pelvis and hip. Anterior view. 
 
 to the crest of the ilium immediately in front of the sacro-iliac articulation. It 
 is of a triangular form, thick and narrow internally, broad and thinner exter- 
 nally. It is in relation, in front, with the Psoas muscle ; behind, with the 
 muscles occupying the vertebral groove; above, with the Quadratus lum- 
 borum. It blends in places with the lumbo-sacral ligament, and its cres- 
 centic inner margin marks the limit of the foramen for the fourth lumbar nerve. 
 These ligaments are thick prolongations from the anterior layer of the lumbar 
 fascia. 
 
292 THE ARTICULATIONS OB JOINTS 
 
 X. Articulations of the Pelvis. 
 
 The ligaments connecting the bones of the pelvis with each other may be 
 divided into four groups: 1. Those connecting the sacrum and ilium. 2. Those 
 passing between the sacrum and ischiimi. 3. Those connecting the sacrum and 
 coccyx. 4. Those between the two pubic bones. 
 
 1. Articulation 0¥ the Sacrum and Ilium (Articulatio Sacroiliaca.) 
 
 The sacro-iliac articulation is an amphiarthrodial joint, formed between the 
 lateral surfaces of the sacrum and ilium. Tlie anterior or auricular portion of each 
 articular surface is covered with a thin plate of cartilage, thicker on the sacrum 
 than on the ilium. These are in close contact with each other, and to a certain 
 extent united together by irregular patches of softer fibro-cartilage, and at their 
 upper and posterior part by fine fibres of interosseous fibrous tissue. Throughout 
 a considerable part of their extent, especially in advanced life, they are not 
 connected together, but are separated by a space containing a synovial-like fluid, 
 and hence the joint presents the characters of a diarthrosis. 
 
 The ligaments connecting these surfaces are the 
 
 Anterior Sacro-iliac. Posterior Sacro-iliac. 
 
 Interosseous. 
 
 The Anterior Sacro-iliac Ligaments (ligamenta sacroiliaca anteriora) (Fig. 213) 
 consists of numerous thin bands which connect the anterior surfaces of the sacrum 
 and ilium. 
 
 The Posterior Sacro-iliac Ligament {lig amentum sacroiliacum posterius) (Fig. 214) 
 is a strong interosseous ligament, situated in a deep depression between the sacrum 
 and ilium behind, and forming the chief bond of connection between those bones. 
 It consists of numerous strong fasciculi which pass between the bones in various 
 directions. Three of these are of large size: the two superior fasciculi constitute 
 the short sacro-iliac ligament {ligamentum sacroiHacum posterius breve) . They are 
 nearly horizontal in direction, arise from the first and second transverse tuber- 
 cles on the posterior surface of the sacrum, and are inserted into the rough, 
 uneven surface at the posterior part of the inner surface of the iHum. The 
 third fasciculus, oblique in direction, is attached by one extremity to the third 
 transverse tubercle on the posterior surface of the sacrum, and by the other to 
 the posterior superior spine of the ilium; it is sometimes called the long or oblique 
 sacro-iliac ligament (ligamentum sacroiliacum posterius longum). 
 
 The Interosseous Ligaments {ligamenta sacroiliaca inter ossea) are completely 
 covered by the posterior sacro-iliac ligament, and are not visible when the joint 
 is unopened. The fibres are short and run obliquely and completely fill the 
 hollow which exists posterior to the joint. 
 
 The position of the sacro-ihac joint is indicated by the posterior superior spine of the iHum. 
 This process is immediately behind the centre of the articulation. 
 
 2. Ligaments passing between the Sacrum and Ischium (Fig. 214). 
 
 The Great Sacro-sciatic (Posterior). 
 The Lesser Sacro-sciatic (Anterior). 
 
 The Great or Posterior Sacro-sciatic Ligament {ligamentum sacrotuherosum) (Figs. 
 214 and 215) is situated at the lower and back part of the pelvis. It is flat, and 
 triangular in form; narrower in the middle than at the extremities; attached by its 
 broad base to the posterior inferior spine of the ilium, to the fourth and fifth trans- 
 
ARTICULATIONS OF THE PELVIS 
 
 293 
 
 verse tubercles of the sacrum, and to the lower part of the lateral margin of that bone 
 and the coccyx. Passing obliquely downward, outward, and forward, it becomes 
 narrow and thick, and at its insertion into the inner margin of the tuberosity of 
 the ischium it increases in breadth, and is prolonged forward along the inner 
 margin of the ramus, forming what is known as the falciform process of the 
 great sacro-sciatic ligament or the falciform ligament (processus falciformis) . The 
 free concave edge of this prolongation has attached to it the obturator fascia, 
 with which it forms a kind of groove, protecting the internal pudic vessels and 
 nerve. One of its surfaces is turned toward the perinoeum, the other toward 
 the Obturator internus muscle. 
 
 Fig. 214. — Articulations of pelvis and hip. Posterior view. 
 
 The posterior surface of this ligament gives origin, by its whole extent, to fibres 
 of the Gluteus maximus muscle. Its anterior surface is united to the lesser sacro- 
 sciatic ligament. Its external border forms, above, the posterior boundary of the 
 great sacro-sciatic foramen, and, below, the posterior boundary of the lesser sacro- 
 sciatic foramen. Its lower border forms part oi the boundary of the perinseum. It 
 is pierced by the coccygeal branch of the sciatic artery and the coccygeal nerve. 
 
 The Lesser or Anterior Sacro-sciatic Ligament (ligamentum sacrospinosum) (Figs. 
 214 and 215), much shorter and smaller than the preceding, is thin, triangular in 
 form, attached by its apex to the spine of the ischium, and internally, by its broad 
 base, to the lateral margin of the sacrum and coccyx, anterior to the attachment 
 of the great sacro-sciatic ligament, with which its fibres are intermingled. 
 
 It is in relation, anteriorly, with the Coccygeus muscle; posteriorly, it is covered 
 by the great sacro-sciatic ligament and crossed by the internal pudic vessels and 
 nerve. Its superior border forms the lower boundary of the great sacro-sciatic 
 foramen; its inferior border, part of the lesser sacro-sciatic foramen. 
 
294 THE ARTICULATIONS Oli JOINTS 
 
 These two ligaments convert the sacro-sciatic notches into foraminao The 
 superior or great sacro-sciatic foramen (foramen ischiadicum majus) (Figs. 214 and 
 215) is bounded, in front and above, by the posterior border of the os innominatum; 
 behind, by the great sacro-sciatic ligament; and below, by the lesser sacro-sciatic 
 ligament. It is partially filled up, in the recent state, by the Pyriformis muscle, 
 which passes through it. Above this muscle the gluteal vessels and superior gluteal 
 nerve emerge from the pelvis, and, below it, the sciatic vessels and nerves, the inter- 
 nal pudic vessels and nerve, the inferior gluteal nerve, and the nerves to the obtu- 
 rator internus and quadratus femoris. The inferior or lesser sacro-sciatic foramen 
 (foramen ischiadicum minus) (Figs. 214 and 215) is bounded, in front, by the 
 
 POUPAHTS 
 LIGAMENT 
 
 ANT. SACRO-ILlAa 
 LIGAMENT. 
 
 GREAT SACRO- 
 SCIATIC LIGA- 
 MENT. 
 
 LESSER SACRO- 
 SCIATIC LIGA- 
 MENT. 
 
 GREAT SACRO- 
 SCIATIC LIGA- 
 MENT. 
 
 Obturator 
 membrane 
 
 Fig. 215. — Side view of pelvis, showing the greater and lesser sacro-sciatic ligaments. 
 
 tuber ischii; above, by the spine and lesser sacro-sciatic ligament; behind, by the- 
 greater sacro-sciatic ligament. It transmits the tendon of the Obturator internus 
 muscle, its nerve, and the internal pudic vessels and nerve. 
 
 3. Articulation of the Sacrum and Coccyx (Symphysis Sacrococcygea) . 
 
 This articulation is an amphiarthrodial joint, formed between the oval surface 
 at the apex of the sacrum and the base of the coccyx. It is analogous to the 
 joints between the bodies of the vertebrte. The ligaments are the 
 
 Anterior Sacro-coccygeal. Lateral Sacro-coccygeal. 
 
 Posterior Sacro-coccygeal. Interposed Fibro-cartilage. 
 
 The Anterior Sacro-coccygeal Ligament (ligamenium sacrococcygeum anterius) 
 consists of a few irregular fibres which descend from the anterior surface of the 
 sacrum to the front of the coccyx, becoming blended with the periosteum. It is 
 a continuation of the anterior common ligament. 
 
 The Posterior Sacro-coccygeal Ligament (ligamentum sacrococcygeum posterius) 
 (Fig. 216) is divided into two portions, the deep and the superficial. The deep' 
 
ARTICULATIONS OF THE PELVIS 
 
 295 
 
 portion of the posterior sacro -coccygeal ligament {ligamentum sacrococcygeum posterius 
 profundum) , which is a continuation of the posterior common ligament, is a flat 
 band of a pearly tint, which arises from the margin of the lower orifice of the sacral 
 canal, and descends to be inserted into the posterior surface of the coccyx. This 
 ligament completes the lower and back part of the sacral canal. Its superficial 
 fibres are much longer than the more deeply seated. This ligament is in rela- 
 tion, behind, with the Gluteus maximus. 
 
 The superficial portion of the posterior sacro-coccygeal ligament (ligamentum 
 sacrococcygeum posterius superficiale) is composed of longitudinal fibrous bands 
 which extend from the lower portion of the middle sacral ridge to the posterior 
 surface of the coccyx and closes partly the hiatus sacralis; and of fibrous bands 
 which extend from the sacral cornua to the coccygeal cornua. A portion of this 
 ligament corresponds to the ligamenta subflava and the balance to the capsular 
 ligament. 
 
 A Lateral Sacro-coccygeal or Intertransverse Ligament (ligamentum sacrococcygeum 
 later ale) (Fig. 216) connects the transverse process of the coccyx to the lower 
 lateral angle of the sacrum on each side. 
 
 APEX OF SACRUM 
 LATERAL SACRO- 
 COCCYGEAL LIGAMENT 
 SUPERFICIAL PORTION OF POST 
 SACRO-COCCYGEAL LIGAMENT 
 DEEP PORTION OF POSTERIOR 
 SACRO-COCCYGEAL LIGAMENT 
 
 Fig. 216. — Ligaments between the sacrum and the coccyx. (Spalteholz.) 
 
 A Fibro-cartilage is interposed between the contiguous surfaces of the sacrum 
 and coccyx; it differs from that interposed between the bodies of the vertebrae in 
 being thinner, and its central part firmer in texture. It is somewhat thicker in 
 front and behind than at the sides. Occasionally, a synovial membrane is found 
 and the coccyx is freely movable. This is especially the case during pregnancy. 
 
 The different segments of the coccyx are connected together by an extension 
 downward of the anterior and posterior sacro-coccygeal ligaments, a thin annular 
 disk of fibro-cartilage being interposed between each of the bones. In the adult 
 male all the pieces become ossified, but in the female this does not commonly 
 occur until a later period of life. The separate segments of the coccyx are first 
 united, and at a niore advanced age the joint between the sacrum and coccyx is 
 obliterated. 
 
 Actions.— The movements which take place between the sacrum and coccyx, 
 and between the different pieces of the latter bone, are forward and backward^ 
 and are very limited. Their extent increases during pregnancy. 
 
296 
 
 THE ARTICULATIONS OB JOINTS 
 
 4. Articulation of the Ossa Pubis (Symphysis Ossium Pubis) (Figs. 213, 217). 
 
 The articulation between the pubic bones is an amphiarthrodial joint, formed 
 by the junction of the two oval articular surfaces of the ossa pubis. The liga- 
 ments of this articulation are the 
 
 Anterior Pubic. 
 Posterior Pubic. 
 
 Superior Pubic. 
 Inferior Pubic. 
 
 Hyaline cartilage covering bone. 
 
 Intermediate fibro-cartilaqe. 
 Cavity at upper 
 and hack part 
 
 Interpubic Disk. 
 
 The Anterior Pubic Ligament (ligamentum pubicum anterius) (Fig. 213) consists 
 of several superimposed layers which pass across the front of the articulation. The 
 superficial fibres pass obliciuely from one bone to the other, decussating and form- 
 ing an interlacement with the fibres of the aponeurosis of the External oblique and 
 the tendon of the Rectus muscles. The deep fibres pass transversely across the 
 symphysis, and are blended with the fibro-cartilage. 
 
 The Posterior Pubic Ligament {ligamentum pubicum posterius) consists of a 
 few thin, scattered fibres which unite the two pubic bones posteriorly. 
 
 The Superior Pubic Ligament {liga- 
 mentum pubicum super ius) (Fig. 213) 
 is a band of fibres which connects to- 
 gether the two pubic bones superiorly. 
 The Inferior Pubic or Subpubic 
 Ligament {ligamentum arcuatum 
 pubis) (Fig. 213) is a thick, tri- 
 angular arch of ligamentous fibres, 
 connecting together the two pubic 
 bones below and forming the upper 
 boundary of the pubic arch. Above, 
 it is blended with the interarticular 
 fibro-cartilage; laterally it is united 
 with the descending rami of the 
 pubis. Its fibres are closely con- 
 nected and have an arched direction. 
 Its lower margin is separated from 
 the triangular ligament of the per- 
 inffium by a gap, through w^hich runs 
 the dorsal vein of the penis. 
 The Interpubic Disk {lamina fibrocartilaginea interpubica) (Fig. 217) consists of a 
 disk of cartilage and fibro-cartilage connecting the surfaces of the pubic bones in 
 front. Each of the two surfaces is covered by a thin layer of hyaline cartilage which 
 is firmly connected to the bone by a series of nipple-like processes which accu- 
 rately fit within corresponding depressions on the osseous surfaces. These opposed 
 cartilaginous surfaces are connected together by an intermediate stratum of fibrous 
 tissue and fibro-cartilage which varies in thickness in different subjects. It often 
 contains a cavity {cavum articulare) in its centre, probably formed by the soften- 
 ing and absorption of the fibro-cartilage, since it rarely appears before the tenth' 
 year of life, and is not lined by synovial membrane. It is larger in the female 
 than in the male, but it is very questionable whether it enlarges, as was formerly 
 supposed, during pregnancy. It is most frequently limited to the upper and back 
 part of the joint, but it occasionally reaches to the front, and may extend the 
 entire length of the cartilage. This cavity may be easily demonstrated by making 
 a vertical section of the symphysis pubis near its posterior surface (Fig. 217). 
 
 The Obturator Ligament is more properly regarded as analogous to the muscular 
 fasciae, with which it will be described. 
 
 Fig. 217. — Vertical section of the symphysis pubis. 
 Made near its posterior surface. 
 
^TERNO CLAVICULAR ARTICULATION 
 
 297 
 
 ARTICULATIONS OF THE UPPER EXTREMITY. 
 
 The articulations of the upper extremity may be arranged in the following 
 groups : 
 
 I. Sterno-clavicular Articulation. VII, 
 
 II. Acromio-clavicular Articulation. VIII. 
 
 III. Ligaments of the Scapula. IX. 
 
 IV. Shoulder-joint. X. 
 V. Elbow-joint. 
 
 VI. Radio-ulnar Articulations. XI. 
 
 Wrist-joint. 
 
 Articulations of the Carpal Bones. 
 Carpo-metacarpal Articulations. 
 Metacarpo-phalangeal Articula- 
 tions. 
 Articulations of the Phalanges. 
 
 I. Stemo-clavicular Articulation (Articulatio Steraoclavicularis) (Fig. 218). 
 
 The sterno-clavicular is regarded by most anatomists as an arthrodial joint, 
 but Cruveilhier considers it to be an articulation by reciprocal reception. Probably 
 
 Fig. 218. — Sterno-clavicular articulation. Anterior view. 
 
 the former opinion is the correct one, the varied movement which the joint enjoys 
 being due to the interposition of an interarticular fibro-cartilage between the 
 joint surfaces. The parts entering into its formation are the sternal end of the 
 clavicle, the upper and lateral part of the first piece of the sternum, and the 
 cartilage of the first rib. The articular surface of the sternum is covered with 
 cartilage. The articular surface of the clavicle is much larger than that of the 
 sternum, and invested with a layer of cartilage^ which is considerably thicker than 
 that on the latter bone. The ligaments of this joint are the 
 
 Capsular. Interclavicular. 
 
 Anterior Sterno-clavicular. Costo-clavicular. 
 
 Posterior Sterno-clavicular. Interarticular Fibro-cartilage. 
 
 The Capsular Ligament (capsula articularis) completely surrounds the articula- 
 tion, consisting of fibres of varying degrees of thickness and strength. Those in 
 front and behind are of considerable thickness, and form the anterior and posterior 
 sterno-clavicular ligaments; but those above and below, especially in the latter 
 situation, are thin and scanty, and partake more of the character of connective 
 tissue than true fibrous tissue. 
 
 1 According to Bruch, the sternal end of the clavicle is covered by a tissue which is rather fibrous than 
 cartilaginous in structure. 
 
298 THE ARTICULATIONS OB JOINTS 
 
 The Anterior Sterao-clavicular Ligament (ligamentum sternoclaviculare) (Fig. 218) 
 is a part of the capsule. It is a broad band of fibres which covers the anterior sur- 
 face of the articulation, being attached, above, to the upper and front part of the 
 inner extremity of the clavicle, and, passing obliquely downward and inward, 
 is attached, below, to the upper and front part of the first piece of the sternum. 
 This ligament is covered, in front, by the sternal portion of the Sterno-cleido- 
 mastoid and the integument; behind, it is in relation with the interarticular 
 fibro-cartilage and the two synovial membranes. 
 
 The Posterior Stemo -clavicular Ligament, also a part of the capsule, is a band of 
 fibres which covers the posterior surface of the articulation, being attached, above, 
 to the upper and back part of the inner extremity of the clavicle, and, passing 
 obliquely downward and inward, is attached, below, to the upper and back part 
 of the first piece of the sternum. It is in relation, in front, with the interartic- 
 ular fibro-cartilage and synovial membranes; behind, with the Sterno-hyoid and 
 Sterno-thyroid muscles. 
 
 The Interclavicular Ligament {ligamentum interciaviculare) (Fig. 218j is a flat- 
 tened band which varies considerably in form and size in different individuals; it 
 passes in a curved direction from the upper part of the inner extremity of one 
 clavicle to the other, and is also attached to the upper margin of the sternum. It 
 is in relation, in front, with the integument; behind, with the Sterno-thyroid 
 muscles. 
 
 The Costo-clavicular or Rhomboid Ligament '{ligamentum costoclavicular e) 
 (Fig. 218) is short, flat, and strong; it is of a rhomboid form, attached, below, to 
 the upper and inner part of the cartilage of the first rib : it ascends obliquely back- 
 ward and outward, and is attached, above, to the rhomboid depression on the 
 under surface of the clavicle. It is in relation, in front, with the tendon of 
 origin of the Subclavius; behind, with the subclavian vein. 
 
 The Literarticular Fibro-cartilage {discus articularis) (Fig. 218) is a flat and nearly 
 circular meniscus, interposed between the articulating surfaces of the sternum and 
 clavicle. It is attached, above, to the upper and posterior border of the articular 
 surface of the clavicle; below, to the cartilage of the first rib, at its junction with the 
 sternum ; and by its circumference, to the anterior and posterior sterno-clavicular 
 and the interclavicular ligaments. It is thicker at the circumference, especially 
 its upper and back part, than at its centre or below. It divides the joint into two 
 cavities, each of which is furnished with a separate synovial membrane. 
 
 Synovial Membrane. — Of the two synovial membranes found in this articulation, 
 one is reflected from the sternal end of the clavicle over the adjacent surface of the 
 fibro-cartilage and cartilage of the first rib; the other is placed between the articular 
 surface of the sternum and adjacent surface of the fibro-cartilage; the latter is the 
 larger of the two. 
 
 Actions. — This articulation is the centre of the movements of the shoulder, and 
 admits of a limited amount of motion in nearly every direction — upward, down- 
 ward, backward, forward — as well as circumduction. When these movements take 
 place in the joint, the clavicle in its motion carries the scapula with it, this bone 
 gliding on the outer surface of the chest. This joint therefore forms the centre 
 from which all movements of the supporting arch of the shoulder originate, and 
 is the only point of articulation of this part of the skeleton with the trunk. "The 
 movements attendant on elevation and depression of the shoulder take place 
 between the clavicle and the interarticular fibro-cartilage, the bone rotating upon 
 the ligament on an axis drawn from before backward through its own articular 
 facet. When the shoulder is moved forward and backward, the clavicle, with 
 the interarticular fibro-cartilage, rolls to and fro on the articular surface of the 
 sternum, revolving, with a sliding movement, round an axis drawn nearly vertically 
 through the sternum. In the circumduction of the shoulder, which is compounded 
 
ACBOMIO-CLAVICULAR ARTICULATION 299 
 
 of these two movements, the clavicle revolves upon the interarticular fibro-carti- 
 lage, and the latter, with the clavicle, rolls upon the sternum."^ Elevation of the 
 clavicle is principally hmited by the costo-clavicular ligament; depression bv the 
 interclavicular. The muscles which raise the clavicle, as in shrugging the shoulder, 
 are the upper fibres of the Trapezius, the Levator anguli scapulae, the clavicular 
 head of the Sterno-mastoid, assisted to a certain extent by the two Rhomboids, 
 which pull the vertebral border of the Scapula backward and upward, and so 
 raise the clavicle. The degression of the clavicle is principally effected by gravity, 
 assisted by the Subclavius, Pectoralis minor, and lower fibres of the Trapezius. 
 It is drawn backward by the Rhomboids and the middle and lower fibres of the 
 Trapezius; and forward by the Serratus magnus and Pectoralis minor. 
 
 Surface Form. — The position of the sterno-clavicular joint may be easily ascertained by feel- 
 ing the enlarged sternal end of the collar-bone just external to the long, cord-like, sternal origin 
 of the Sterno-mastoid muscle. If this muscle is relaxed by bending the head forward, a depres- 
 sion just internal to the end of the clavicle, and between it and the sternum, can be felt, indi- 
 cating the exact position of the joint, which is subcutaneous. When the arm hangs by the side, 
 the cavity of the joint is V-shaped. If the arm is raised, the bones become more closely approx- 
 imated, and the cavity becomes a mere slit. 
 
 Surgical Anatomy. — The strength of this joint mainly depends upon its ligaments, and 
 it is because of the ligaments and because the force of a blow is generally transmitted along the 
 long axis of the clavicle, that dislocation so rarely occurs, and that the bone is generally broken 
 rather than displaced. When dislocation does occur, the course which the displaced bone takes 
 depends more upon the direction in which the violence was applied than upon the anatomical 
 construction of the joint; it may be either forward, backward, or upward. A complete upward 
 dislocation is also inward. A complete forward or backward dislocation is also inward and 
 downward. The chief point worthy of note, as regards the construction of the joint, in regard 
 to dislocations, is the fact that, owing to the shape of the articular surfaces being so little 
 adapted to each other, and that the strength of the joint mainly depends upon the ligaments, 
 the displacement when reduced is very liable to recur, and hence it is extremely difficult to 
 keep the end of the bone in its proper place, and it may be necessary to incise the soft parts 
 and wire the bone in place. 
 
 II. Acromio-clavicular Articulation or Scapulo-clavicular Articulation 
 (Articulatio Acromioclavicularis) (Fig. 219). 
 
 The acromio-clavicular is an arthrodial joint formed between the outer extrem- 
 ity of the clavicle and the inner margin of the acromion process of the scapula. 
 The ligaments which surround the joint form a capsule. The ligaments of this 
 articulation are the 
 
 Superior Acromio-clavicular. (Trapezoid. 
 
 Inferior Acromio-clavicular. Coraco-clavicular < and 
 
 Interarticular Fibro-cartilage. I Conoid. 
 
 The Superior Acromio-clavicular Ligament (ligamentum acromioclavicidare) (Figs. 
 219 and 220) is a portion of the joint capsule. It is a quadrilateral band which 
 covers the superior part of the articulation, extending between the upper part of 
 the outer end of the clavicle and the adjoining part of the upper surface of the 
 acromion. It is composed of parallel fibres wliich interlace with the aponeurosis 
 of the Trapezius and Deltoid muscles; below, it is in contact with the inter- 
 articular fibro-cartilage (when it exists) and the synovial membranes. 
 
 The Inferior Acromio-clavicular Ligament, somewhat thinner than the pre- 
 ceding, and like it a portion of the capsule, covers the under part of the articula- 
 tion, and is attached to the adjoining surfaces of the two bones. It is in relation, 
 above, with the synovial membranes, and in rare cases with the interarticular 
 fibro-cartilage; below, with the tendon of the Supraspinatus. These two liga- 
 
 • Humphry. On the Human Skeleton, p. 402. 
 
300 'J'HE ARTICULATIONS OR JOINTS 
 
 ments are continuous with each other in front and behind, and form a complete 
 capsule round the joint. 
 
 The Interarticular Fibro-cartilage (discus articularis) is frequently absent in this 
 articulation. When the meniscus exists it is generally incomplete and only par- 
 tially separates the articular surfaces, and occupies the upper part of the articu- 
 lation. More rarely it completely separates the joint into two cavities. 
 
 Fig. 219. — The left shoulder-joint, scapulo-clavicular articulations, and proper ligaments of scapula. 
 
 The Sjmovial Membrane. — There is usually only one synovial membrane in 
 this articulation, but when a complete interarticular fibro-cartilage exists there are 
 two synovial membranes. 
 
 The Coraco-clavicular Ligament (ligamentum coracoclaviculare) (Figs. 219 and 
 220) serves to connect the clavicle with the coracoid process of the scapula. It does 
 not properly belong to this articulation, but as it forms a most efficient means in 
 retaining the clavicle in contact with the acromial process, it is usually described 
 with it. It consists of two fasciculi, called the trapezoid and conoid ligaments. 
 
 The trapezoid ligament (ligamentum trapezoideum) , the anterior and external 
 fasciculus, is broad, thin, and quadrilateral; it is placed obliquely between the 
 coracoid process and the clavicle. It is attached, below, to the upper surface 
 of the coracoid process; above, to the obHque line on the under surface of the 
 clavicle. Its anterior border is free ; its posterior border is joined with the conoid 
 ligament, the two forming by their junction a projecting angle. 
 
 The conoid ligament (ligamentum conoideum) , the posterior and internal fas- 
 ciculus, is a dense band of fibres, conical in form, the base being directed upward, 
 the summit downward. It is attached by its apex to a rough impression at the 
 base of the coracoid process, internal to the preceding; above, by its expanded 
 
PROPER LIGAMENTS OF THE SCAPULA 301 
 
 base, to the conoid tubercle on the under surface of the clavicle, and to a line 
 proceeding internally from it for half an inch. These ligaments are in relation, 
 in front, with the Subclavius and Deltoid; behind, with the Trapezius. They 
 serve to limit rotation of the scapula, the Trapezoid limiting rotation forward, 
 and the Conoid backward. 
 
 Actions. — The movements of this articulation are of two kinds: 1. A gliding 
 motion of the articular end of the clavicle on the acromion. 2. Rotation of the 
 scapula forward and backward upon the clavicle, the extent of this rotation being 
 limited by the two portions of the coraco-clavicular ligament. 
 
 The acromio-clavicular joint has important functions in the movements of the 
 upper extremity. It has been well pointed out by Sir George Humphry that if 
 there had been no joint between the clavicle and scapula the circular movement of 
 the scapula on the ribs (as in throwing both shoulders backward or forward) would 
 have been attended with a greater alteration in the direction of the shoulder than is 
 consistent with the free use of the arm in such position, and it would have been 
 impossible to give a blow straight forward with the full force of the arm ; that is to 
 say, with the combined force of the scapula, arm, and forearm. "This joint," as 
 he happily says, "is so adjusted as to enable either bone to turn in a hinge-like 
 manner upon a vertical axis drawn through the other, and it permits the surfaces 
 of the scapula, like the baskets in a roundabout swing, to look the same way in 
 every position or nearly so." Again, when the whole arch formed by the clavicle 
 and scapula rises and falls (in elevation or depression of the shoulders), the joint 
 between these two bones enables the scapula still to maintain its lower part in 
 contact with the ribs. 
 
 Surface Form. — The position of the acromio-clavicular joint can generally be ascertained by 
 the slightly enlarged extremity of the outer end of the clavicle, which causes it to project above 
 the level of the acromion process of the scapula. Sometimes this enlargement is so considerable 
 as to form a rounded eminence, which is easily to be felt. The joint lies in the plane of a ver- 
 tical line passing uj) the middle of the front of the arm. 
 
 Surgical Anatomy. — Owing to the slanting shape of the articular surfaces of this joint, 
 the commonest dislocation is the passing of the acromion process of the scapula under the 
 outer end of the clavicle; but dislocations in the opposite direction have been described. The 
 first form of dislocation is produced by violent force applied to the scapula so as to drive the 
 shoulder forward. The displacement in acromio-clavicular dislocation is often incomplete, on 
 account of the strong coraco-clavicular ligaments which remain untorn. The same difficulty 
 exists, as in the sterno-clavicular dislocation, in maintaining the ends of the bone in apposition after 
 reduction, and it may become necessary to wire them in place after incision of the soft parts. 
 
 III. Proper Ligaments of the Scapula (Figs. 219, 220). 
 
 The proper ligaments of the scapula pass between portions of that bone, but 
 are not parts of an articulation. They are the 
 
 Coraco-acromial. Superior Transverse. 
 
 Inferior Transverse. 
 
 The Coraco-acromial Ligament (ligamentum coracoccromicle) is a strong trian- 
 gular band, extending between the coracoid and acromial processes. It is attached, 
 by its apex, to the summit of the acromion just in front of the articular surface 
 for the clavicle, and by its broad base to the whole length of the outer border of 
 the coracoid process. Its posterior fibres are directed inward, its anterior fibres 
 forward and inward. This ligament completes the vault formed by the coracoid and 
 acromion processes for the protection of the head of the humerus. It is in relation, 
 above, with the clavicle and under surface of the Deltoid muscle; below, with the 
 tendon of the Supraspinatus muscle, a bursa being interposed. Its outer border is 
 continuous with a dense lamina that passes beneath the Deltoid upon the tendons 
 
302 
 
 THE ARTICULATIONS OR JOINTS 
 
 of the Supra- and Infraspinatus muscles. This Hgament is sometimes described as 
 consisting of two marginal bands and a thinner intervening portion, the two bands 
 being attached respectively to the apex and base of the coracoid process, and join- 
 ing together at their attachment into the acromion process. When the Pectoralis 
 minor is inserted, as sometimes is the case, into the capsule of the shoulder-joint 
 instead of into the coracoid process, it passes between these two bands, and the 
 intervening portion is then deficient. 
 
 The Superior Transverse, Coracoid or Suprascapular Ligament (lig amentum trans- 
 versum scapuloe super ius) (Figs. 219, 220, and 222J converts the suprascapular 
 
 SUPERIOR 
 
 ACROMIOCLAVICULAR 
 
 LIGAMENT 
 
 GLENOID 
 
 LIGAMENT 
 
 Fig. 220.- 
 
 -Right clavicle and shoulder-blade with ligament, from without and somewhat from in front. 
 
 (Spaltenolz.) 
 
 notch into a foramen. It is a thin and flat fasciculus, narrower at the middle 
 than at the extremities, attached by one end to the base of the coracoid process, 
 and by the other to the inner extremity of the scapular notch. The suprascapular 
 nerve passes through the foramen; the suprascapular vessels pass over the liga- 
 ment. 
 
 An additional ligament, the Inferior Transverse or Spino-glenoid Ligament (liga- 
 menium transversum scapuloe inferius), is sometimes found on the scapula, stretch- 
 ing from the outer border of the spine to the margin of the glenoid cavity. When 
 present, it forms an arch under which the suprascapular vessels and nerve pass as 
 they enter the infraspinous fossa. 
 
 Movements of Scapula. — The scapula is capable of being moved upward and 
 downward, forward and backward, or, by a combination of these movements, cir- 
 cumducted on the wall of the chest. The muscles which raise the scapula are the 
 upper fibres of the Trapezius, the Levator anguli scapulre, and the two Rhom- 
 boids; those which depress it are the lower fibres of the Trapezius, the Pectoralis 
 minor, and, through the clavicle, the Subclavius. The scapula is drawn hackioard 
 by the Rhomboids and the middle and lower fibres of the Trapezius, and forward 
 
THE SHOULDER- JOINT 
 
 303 
 
 by the Serratus magnus and Pectoralis minor, assisted, when the arm is fixed, by 
 the PectoraHs major. The mobihty of the scapula is very considerable, and 
 greatly assists the movements of the arm at the shoulder-joint. Thus, in raising 
 the arm from the side the Deltoid and Supraspinatus can only lift it to a right 
 
 DELTOID. SUPRA-SPINATUS. 
 
 TERES MAJOR 
 
 SUl 
 
 TERES MAJOR. Circumjiex vessels. Circumflex vessels. scapularis. 
 
 Fig. 221. — Vertical sections through the shoulder-joint, the arm being vertical and horizontal. (After Henle.) 
 
 angle with the trunk, the further elevation of the limb being effected by the 
 Trapezius and Serratus magnus moving the scapula on the wall of the chest. 
 This mobility is of special importance in ankylosis of the shoulder-joint, the 
 movement of this bone compensating to a very great extent for the immobility 
 of the joint. 
 
 IV. The Shoulder-joint (Articulatio Humeri) (Figs. 219, 220, 221, 222). 
 
 The shoulder is an enarthrodial or ball-and-socket joint. The bones entering 
 into its formation are the large globular head of the humerus, which is received 
 into the shallow glenoid cavity of the scapula — an arrangement which permits of 
 very considerable movement, whilst the joint itself is protected against displace- 
 ment by the tendons which surround it and by atmospheric pressure. The liga- 
 ments do not maintain the joint surfaces in apposition, because when they alone 
 remain the humerus can be separated to a considerable extent from the glenoid 
 cavity ; their use, therefore, is to limit the amount of movement. Above, the joint 
 is protected by an arched vault, formed by the under surfaces of the ccracoid and 
 acromion processes, and the coraco-acromial ligament. The articular surfaces 
 are covered by a layer of cartilage: that on the head of the humerus is thicker at 
 the centre than at the circumference, the reverse being the case in the glenoid 
 cavity. The ligaments of the shoulder are the 
 
 Capsular. Transverse humeral. 
 
 Coraco-huraeral. Glenoid.^ 
 
 The Capsular Ligament (capsula articularis) (Figs. 219, 220, and 222) completely 
 encircles the articulation, being attached, above, to the circumference of the glenoid 
 cavity beyond the glenoid ligament, below, to the anatomical neck of the humerus, 
 approaching nearer to the articular cartilage above than in the rest of its extent. 
 It is thicker above and below than elsewhere, and is remarkably loose and lax, and 
 
 1 The long tendon of origin of the Biceps muscle also acts as one of the liganients of this joint, 
 observations on p. 268 on the function of the muscles passing over more than one joint. 
 
 See the 
 
304 
 
 THE ARTICULATIONS OB JOINTS 
 
 much larger and longer than is necessary to keep the bones in contact, allowing 
 them to be separated from each other more than an inch — an evident provision 
 for that extreme freedom of movement which is peculiar to this articulation. Its 
 superficial surface is strengthened, above, by the Supraspinatus; below, by the 
 long head of the Triceps; behind, by the tendons of the Infraspinatus and Teres 
 minor; and in front, by the tendon of the Subscapularis. The capsular ligament 
 usually presents three openings: One anteriorly, below the coracoid process, 
 establishes a communication between the synovial membrane of the joint and a 
 
 ARTICULAR 
 CAPSULE 
 
 LONG HEAD OF 
 BICEPS MUSCLE 
 
 SPINE OF SCAPULA 
 
 (sawed off at its origin) 
 
 Fig. 222. — Right shoulder-joint, frontal section, from behind. (Spalteholz.) 
 
 bursa beneath the tendon of the Subscapularis muscle. The second, which is 
 not constant, is at the posterior part, where a communication sometimes exists 
 between the joint and a bursal sac belonging to the Infraspinatus muscle. The 
 third is seen between the two tuberosities, for the passage of the long tendon 
 of the Biceps muscle. It transmits a sac-like prolongation of the synovial 
 membrane, which ends as a blind pouch opposite the surgical neck of the bone. 
 This synovial sac is called the vagina mucosa intertubercularis. 
 
 The Coraco-humeral Ligament {lig amentum coracohumerale) (Fig. 219) is a broad 
 band which strengthens the upper part of the capsular ligament. It arises from 
 the outer border of the coracoid process, and passes obliquely downward and out- 
 ward to the front of the great tuberosity of the humerus, being blended with the 
 tendon of the Supraspinatus muscle. This ligament is intimately united to the 
 capsular ligament throughout the greater part of its extent. 
 
 Supplemental Bands of the Capsular Ligament. — In addition to the coraco- 
 humeral ligament, the capsular ligament is strengthened by supplemental bands in 
 the interior of the joint. One of these bands is situated on the inner side of the 
 joint, and passes from the inner edge of the glenoid cavity to the lower part of the 
 lesser tuberosity of the humerus. This is sometimes known as Flood's ligament> 
 
THE SHOULDER- JOINT 305 
 
 and is supposed to correspond with the Hgamentum teres of the hip-joint. A 
 second of these bands is situated at the lower part of the joint, and passes from the 
 under edge of the glenoid cavity to the under part of the neck of the humerus, and 
 is known as Schlemm's ligament. A third, called the gleno-humeral ligament, is 
 situated at the upper part of the joint, and projects into its interior, so that it can 
 be seen only when the capsule is opened. It is attached above to the apex of the 
 glenoid cavity, close to the root of the coracoid process, and, passing downward 
 along the inner edge of the tendon of the Biceps, is attached below to the lesser 
 tuberosity of the humerus, where it forms the inner boundary of the upper part of 
 the bicipital groove. It is a thin, ribbon-like band, occasionally quite free from 
 the capsule. 
 
 The Transverse Humeral Ligament is a prolongation of the capsular ligament. 
 It is a broad band of fibrous tissue passing from the lesser to the greater tuber- 
 osity of the humerus, and always limited to that portion of the bone which lies 
 above the epiphysial line. It converts the bicipital groove into an osseo-aponeu- 
 rotic canal, and is the analogue of the strong process of bone which connects the 
 summits of the two tuberosities in the musk ox. 
 
 The Glenoid Ligament (lahrum glenoidale) (Figs. 220 and 222) is a fibro- 
 cartilaginous rim, attached round the margin of the glenoid cavity. It is trian- 
 gular on section, the thickest portion being fixed to the circumference of the cavity, 
 the free edge being thin and sharp. It is continuous above with the long tendon 
 of the Biceps muscle, which bifurcates at the upper part of the cavity into two 
 fasciculi, and becomes continuous with the fibrous tissue of the glenoid ligament. 
 This ligament deepens the cavity for articulation, and protects the edges of the 
 bone. It is lined by the synovial membrane. 
 
 Synovial Membrane (Fig. 222). — The synovial membrane is reflected from the 
 margin of the glenoid cavity over the fibro-cartilaginous rim surrounding it: it is 
 then reflected over the internal surface of the capsular ligament, covers the lower 
 part and sides of the anatomical neck of the humerus as far as the cartilage cover- 
 ing the head of the bone. The long tendon of the Biceps muscle which passes 
 through the capsular ligament is enclosed in a tubular sheath of synovial membrane 
 {vagina mucosa intertvbercularis) , which is reflected upon it at the point where it 
 perforates the capsule, and is continued around it as far as the level of the surgical 
 neck of the humerus. The tendon of the Biceps is thus enabled to traverse the 
 articulation, but it is not contained in the interior of the synovial cavity. 
 
 Bm'sse. — A large bursa exists between the joint capsule and the tendon of the 
 Subscapularis muscle. It is called the subscapular bursa. This sac communicates 
 with the shoulder-joint by means of an opening at the inner side of the capsular 
 ligament. The subscapular bursa is constant. Occasionally another and smaller 
 bursa exists jjeneath the tendon of the infraspinatus. It is called the infraspinatus 
 bursa, and communicates with the shoulder-joint by means of an opening in the outer 
 surface of the capsule. The subdeltoid or subacromial bursa is placed between the 
 under surface of the Deltoid muscle and the outer surface of the capsule. It does 
 not communicate with the joint. The subcutaneous acromial bursa is between the 
 surface and the summit of the acromion process. There is a bursa beneath 
 the Coraco-brachialis muscle — one beneath the teres major — and one beneath 
 the tendinous portion of the latissimus dorsi. There is also a bursa between the 
 tendon of insertion of the Pectoralis major muscle and the long head of the 
 biceps. 
 
 The Muscles in relation with the joint are, above, the Supraspinatus ; below, the 
 long head of the Triceps; in front, the Subscapularis; behind, the Infraspinatus 
 and Teres minor; within, the long tendon of the Biceps. The Deltoid is placed 
 most externally, and covers the articulation on its outer side, as well as in front 
 and behind. 
 
 20 
 
306 THE ARTICULATIONS OB JOINTS 
 
 The Arteries supplying the joint are articular branches of the anterior and 
 posterior circumflex, and the suprascapular. 
 
 The Nerves are derived from the circumflex and suprascapular. 
 
 Actions. — The shoulder-joint is capable of movement in every direction, forward, 
 backward, abduction, adduction, circumduction, and rotation. The humerus is 
 drawn forward by the Pectoralis major, anterior fibres of the Deltoid, Coraco- 
 brachialis, and by the Biceps when the forearm is flexed ; backward, by the Latis- 
 simus dorsi, Teres major, posterior fibres of the Deltoid, and by the Triceps when 
 the forearm is extended; it is abducted (elevated) by the Deltoid and Supraspinatus; 
 it is adducted (depressed) by the Subscapularis, Pectoralis major, liatissimus dorsi, 
 and Teres major; it is rotated outward by the Infraspinatus and Teres minor; 
 and it is rotated inward by the Subscapularis, Latissimus dorsi. Teres major, and 
 •Pectoralis major. 
 
 The most striking peculiarities in this joint are: 1. The large size of the head 
 of the humerus in comparison with the depth of the glenoid cavity, even when 
 supplemented by the glenoid ligament. 2. The looseness of the capsule of the 
 joint. 3. The intimate connection of the capsule with the muscles attached to the 
 head of the humerus. 4. The peculiar relation of the biceps tendon to the joint. 
 
 It is in consequence of the relative size of the two articular surfaces that the 
 joint enjoys such free movement in every possible direction. When these move- 
 ments of the arm are arrested in the shoulder-joint by the contact of the bony sur- 
 faces and by the tension of the corresponding fibres of the capsule, together with 
 that of the muscles acting as accessory ligaments, they can be carried considerably 
 farther by the movements of the scapula, involving, of course, motion at the 
 acromio- and sterno-clavicular joints. These joints are therefore to be regarded 
 as accessory structures to the shoulder-joint.^ The extent of these movements of 
 the scapula is very considerable, especially in extreme elevation of the arm, which 
 movement is best accomplished when the arm is thrown somewhat forward and 
 outward, because the margin of the head of the humerus is by no means a true 
 circle; its greatest diameter is from the bicipital groove downward, inward, and 
 backward, and the greatest elevation of the arm can be obtained by rolling its 
 articular surface in the direction of the measurement. The great width of the 
 central portion of the humeral head also allows of very free horizontal movement 
 when the arm is raised to a right angle, in which movement the arch formed by the 
 acromion, the coracoid process, and the coraco-acromial ligament constitutes a 
 sort of supplemental articular cavity for the head of the bone. 
 
 The looseness of the capsule is so great that the arm will fall about an inch 
 from the scapula when the muscles are dissected from the capsular ligament and 
 an opening made in it to remove the atmospheric pressure. The movements of 
 the joint, therefore, are not regulated by the capsule so much as by the surrounding 
 muscles and by the pressure of the atmosphere — an arrangement which "renders 
 the movements of the joint much more easy than they would otherwise have been, 
 and permits a swinging, pendulum-like vibration of the limb when the muscles 
 are at rest" (Humphry). The fact, also, that in all ordinary positions of the joint 
 the capsule is not put on the stretch enables the arm to move freely in all direc- 
 tions. Extreme movements are checked by the tension of appropriate portions of 
 the capsule, as well as by the interlocking of the bones. Thus it is said that 
 " abduction is checked by the contact of the great tuberosity with the upper edge of 
 the glenoid cavity, adduction by the tension of the coraco-humeral ligament" 
 (Beaunis et Bouchard). Cleland^ maintains that the limitations of movement at 
 the shoulder-joint are due to the structure of the joint itself, the glenoid ligament 
 fitting, in different positions of the elevated arm, into the anatomical neck of the 
 humerus. 
 
 1 See p. 301. * Journal of Anatomy and Physiology, 1884, vol. xviii. 
 
THE SHOULDER- JOINT 307 
 
 Cathcart^ has pointed out that in abducting the arm and raising it above the 
 liead, the scapula rotates throughout the whole movement with the exception of 
 a short space at the beginning and at the end; that the humerus moves on the 
 scapula not only from the hanging to the horizontal position, but also in passing 
 upward as it approaches the vertical above; that the clavicle moves not only 
 during the second half of the movement but in the first as well, though to a less 
 extent — i. e., the scapula and clavicle are concerned in the first stage as well as in 
 the second; and that the humerus is partly involved in the second as well as 
 chiefly in the first. 
 
 The intimate union of the tendons of the four short muscles with the capsule 
 converts these muscles into elastic and spontaneously acting ligaments of the joint, 
 and it is regarded as being also intended to prevent the folds into which all portions 
 of the capsule would alternately fall in the varying positions of the joint from being 
 driven between the bones by the pressure of the atmosphere. 
 
 The peculiar relations of the Biceps tendon to the shoulder-joint appear to sub- 
 serve various purposes. In the first place, by its connection with both the shoulder 
 and elbow the muscle harmonizes the action of the two joints, and acts as an 
 elastic ligament in all positions, in the manner previously adverted to.^ Next, it 
 strengthens the upper part of the articular cavity, and prevents the head of the 
 humerus from being pressed up against the acromion process, when the Deltoid 
 contracts, instead of forming the centre of motion in the glenoid cavity. By its 
 passage along the bicipital groove it assists in rendering the head of the humerus 
 steady in the various movements of the arm. When the arm is raised from the 
 side it assists the Supra- and Infraspinatus in rotating the head of the humerus in 
 the glenoid cavity. It also holds the head of the bone firmly in contact with the 
 glenoid cavity, and prevents its slipping over its lower edge, or being displaced by 
 the action of the Latissimus dorsi and Pectoralis major, as in climbing and many 
 other movements. 
 
 Surface Form. — The direction and position of the shoulder-joint may be indicated by a line 
 drawn from the middle of the coraco-acromial ligament, in a curved direction, with its con- 
 vexity inward, to the innermost part of that portion of the head of the humerus which can be 
 felt in the axilla when the arm is forcibly abducted from the side. When the arm hangs by the 
 side, not more than one-third of the head of the bone is in contact with the glenoid cavity, and 
 three-fjuarters of its circumference is in front of a vertical line drawn from the anterior border 
 of the acromion process. 
 
 Surgical Anatomy. — Owing to the construction of the shoulder-joint and the freedom of 
 movement which it enjoys, as well as in consequence of its exposed situation, it is more frequently 
 dislocated than any other joint in the body. Dislocations of the shoulder contribute about forty 
 per cent, of the cases in tables of dislocations. Dislocation occurs when the arm is thrown into 
 <?xtreme abduction, and when, therefore, the head of the humerus presses against the lower and 
 froiit part of the capsule, which is the thinnest and least supported part of the ligament. The 
 rent in the capsule almost invariably takes place in this situation, between the tendon of the Sub- 
 scapularis and the Triceps, and through it the head of the bone escapes, so that the dislocation 
 in most instances is primarily subglenoid. The head of the bone does not usually remain in this 
 situation, but generally assumes some other position, which varies according to the direction and 
 amount of force producing the dislocation and the relative strength of the muscles in front and 
 behind the joint. In consequence of the muscles at the back being weaker than those in front, 
 and especially on account of the long head of the Triceps preventing the bone passing backward, 
 dislocation forward is much more common than backward. The most frequent position which 
 the head of the humerus ultimately assumes is on the front of the neck of the scapula, beneath 
 the coracoid process, and hence named subcoracoid dislocation. Occasionally, in consequence 
 probably of a greater amount of force being brought to bear on the limb, the head is driven 
 farther inward, and rests on the upper part of the front of the chest, beneath the clavicle (sub- 
 clavicular). If the head of the bone passes under the Subscapularis muscle and also under 
 the Teres major or the lower border of the Pectoralis major, the arm remains abducted, or even 
 with the elbow raised above the head {luxatio erecta). Sometimes the humerus remains in the 
 position in which it was primarily displaced, resting on the axillary border of the scapula (sub- 
 
 ' Journal of Anatomy and Physiology, 1884, vol. xviii. * See p. 26Sr 
 
308 'I'HE ARTICULATIONS OB JOINTS 
 
 glenoid), and rarely it passes backward and remains in the infraspinatous fossa beneath the 
 spine (subspinous). If dislocation frequently recurs the condition may be amended in some 
 cases by exposing the capsule and putting tucks in it by means of sutures. 
 
 An old unreduced dislocation is sometimes treated by incising the soft parts and returning 
 the head of the humerus into the glenoid cavity. In other cases the head of the humerus is 
 excised. Dislocation of the long tendon of the Biceps muscle from the bicipital groove is a rare 
 accident. When it occurs the arm is rigid in abduction, but the head of the humerus is found 
 to be in the glenoid cavity. It is reduced by flexion of the elbow and rotation of the arm. 
 Rupture of the long tendon of the biceps is more common than dislocation of the tendon. 
 
 After this injury the belly of the muscle is relaxed and is nearer than normal to the elbow; 
 flexion of the forearm is much weakened, and is weaker in supination than it is in pronation. 
 The head of the humerus passes forward and inward, and the condition is often mistaken for 
 dislocation of the bone. 
 
 If we desire to aspirate the shoulder- joint, place the arm against the side, flex the forearm at 
 a right angle to the arm, carry the forearm across the front of the chest, and enter the trocar 
 below the acromion (De Vos). 
 
 The shoulder-joint is sometimes the seat of all those inflammatory affections, both acute and 
 chronic, which attack joints, though perhaps it suffers less frequently than some other joints of 
 equal size and importance. Acute synovitis may result from injury, rheumatism, or pysemia, or 
 may follow secondarily on the so-called acute epiphysitis of infants. It is attended with effusion 
 into the joint, and when this occurs the capsule is evenly distended and the contour of the joint 
 rounded. Special projections may occur at the site of the openings in the capsular ligament. 
 Thus a swelling may appear just in front of the joint, internal to the lesser tuberosity, from effu- 
 sion into the bursa beneath the Subscapularis muscle; or, again, a swelling which is sometimes 
 bilobed may be seen in the interval between the Deltoid and Pectoralis major muscles, from effu- 
 sion into the diverticulum, which runs down the bicipital groove with the tendon of the biceps. 
 The effusion into the synovial membrane can be best ascertained by examination from the axilla, 
 where a soft, elastic, fluctuating swelling can usually be felt. The bursa beneath the deltoid is 
 sometimes ruptured by violence, and sometimes inflames, suppurates, or becomes tuberculous. 
 
 Tuberculous arthritis not unfrequently attacks the shoulder-joint, and may lead to total 
 destruction of the articulation, when ankylosis may result or long-protracted suppuration may 
 necessitate excision. This joint is also one of those which is most liable to be the seat of osteo- 
 arthritis, and may also be affected in gout and rheumatism; or in locomotor ataxia, when it 
 occasionally becomes the seat of Charcot's disease. 
 
 Excision of the shoulder-joint may be required in cases of arthritis (especially the tuber- 
 culous form) which have gone on to destruction of the articulation; in compound dislocations and 
 fractures, particularly those arising from gunshot injuries, in which there has been extensive 
 injury to the head of the bone; in some cases of old unreduced dislocation, where there is much 
 pain; and possibly in some few cases of growth connected with the upper end of the bone. The 
 operation is best performed by making an incision from the middle of the coraco-acromial liga- 
 ment down the arm for about three inches: this will expose the bicipital groove and the tendon 
 of the Biceps, which may be either divided or hooked out of the way, according as to whether it 
 is implicated in the disease or not. The capsule is then freely opened, and the muscles attached 
 to the greater and lesser tuberosities of the humerus divided. The head of the bone can then 
 be thrust out of the wound and sawn off, or divided with a narrow saw in sitn and subsequently 
 removed. The section should be made, if possible, just below the articular surface, so as to 
 leave the bone as long as possible. The glenoid cavity must then be examined, and gouged 
 if carious. 
 
 V. The Elbow- joint (Articulatio Cubiti) (Figs. 223, 224, 225, 226). 
 
 The elbow is a ginglymus or hinge-joint. The bones entering into its forma- 
 tion are the trochlea of the humerus, which is received into the greater sigmoid 
 cavity of the ulna {articulatio humeroulnaris ) , and admits of the movements 
 peculiar to this joint — viz., flexion and extension; whilst the capitellum or radial 
 head of the humerus articulates with the cup-shaped depression on the head of 
 the radius (articulatio Jiumeroradialis) ; the circumference of the head of the 
 radius articulates with the lesser sigmoid cavity of the ulna {articulatio radio- 
 ulnaris proximalis) , allowing of the movement of rotation of the radius on the 
 ulna, the chief action of the superior radio-ulnar articulation. The articular 
 surfaces are covered with a thin layer of cartilage, and connected together by a 
 capsular ligament {capsula articularis) (Fig. 225) of unequal thickness, being 
 especially thickened on its two sides and, to a less extent, in front and behind. 
 
THE ELBOW- JOINT 
 
 309 
 
 These thickened portions are usually described as distinct ligaments under the 
 
 following names: 
 
 Anterior. Internal Lateral 
 
 Posterior. External Lateral. 
 
 The orbicular ligament of the upper radio-ulnar articulation must also be 
 reckoned among the ligaments of the elbow. 
 
 The Anterior Ligament (Fig. 223) is a broad and thin fibrous layer which covers 
 the anterior surface of the joint. It is attached to the front of the internal condyle 
 and to the front of the humerus immediately above the coronoid and radial fossae; 
 below, to the anterior surface of the coronoid process of the ulna and to the 
 orbicular ligament, being continuous on each side with the lateral ligaments. Its 
 
 Fig. 223. — Left elbow-joint, showing anterior 
 and internal ligaments. 
 
 Fig. 224. — Left elbow-joint, showing posterior 
 and external ligaments. 
 
 superficial fibres pass obliquely from the inner condyle of the humerus outward to 
 the orbicular ligament. The middle fibres, vertical in direction, pass from the 
 upper part of the coronoid depression and become partly blended with the pre- 
 ceding, but are mainly inserted into the anterior surface of the coronoid process. 
 The deep or transverse set intersects these at right angles. This ligament is in 
 relation, in front, with the Brachialis anticus muscle, except at its outermost 
 part; behind, it is in relation with the synovial membrane. 
 
 The Posterior Ligament (Fig. 224) is a tliin and loose membranous fold, attached, 
 above, to the lower end of the humerus, above and at the sides of the olecranon 
 
310 
 
 THE ARTICULATIONS OB JOINTS 
 
 CORONOID 
 PROCESS 
 
 OLECRANON 
 FOSSA 
 
 ARTICULAR 
 CAPSULE 
 
 fossa; below, to the groove on the upper and outer surfaces of the olecranon. The 
 superficial or transverse fibres pass between the adjacent margins of the olecranon 
 fossa. The deeper portion consists of vertical fibres, some of which, thin and 
 weak, pass from the upper part of the olecranon fossa to the margin of the olec- 
 ranon; others, thicker and stronger, pass from the back of the capitellum of the 
 humerus to the posterior border of the lesser sigmoid cavity of the ulna. This 
 ligament is in relation, behintl, with the tendon of the Triceps muscle and the 
 Anconeus muscle; in front, with the synovial membrane. 
 
 The Internal Lateral Ligament (ligamentum collaterale ulnare) (Fig. 223) is a 
 thick triangular band consisting of two portions, an anterior and posterior, united 
 by a thinner intermediate portion. The anterior portion, directed obhquely forward, 
 
 is attached, above, by its apex, 
 to the front part of the in- 
 ternal condyle of the humerus ; 
 and, below, by its broad base, 
 to the inner margin of the 
 coronoid process. The poste- 
 rior portion, also of triangular 
 form, is attached, above, by 
 its apex, to the lower and back 
 part of the internal condyle; 
 below, to the inner margin of 
 the olecranon. Between these 
 two bands a few intermediate 
 fibres descend from the inter- 
 nal condyle to blend with a 
 transverse band of ligament- 
 ous tissue which bridges 
 across the notch between the 
 olecranon and coronoid pro- 
 cesses. This ligament is in 
 relation, internally, with the 
 Triceps and Flexor carpi 
 ulnaris muscles and the ulnar 
 nerve, and gives origin to part 
 of the Flexor sublimis digi- 
 torum muscle. 
 
 The External Lateral Liga- 
 ment (ligamentum collaterale 
 radiale) (Fig. 224) is a short 
 and narrow fibrous band less 
 distinct than the internal, at- 
 tached, above, to a depression 
 below the external condyle of 
 the humerus; below, to the 
 orbicular ligament, some of its 
 most posterior fibres passing over that ligament, to be inserted into the outer 
 margin of the ulna. This ligament is intimately blended with the tendon of 
 origin of the Supinator brevis muscle. 
 
 Synovial Membrane (Fig. 225). — The synovial membrane is very extensive. It 
 covers the margin of the articular surface of the humerus, and lines the coronoid 
 and olecranon fossa on that bone; from these points it is reflected over the anterior, 
 posterior, and lateral ligaments, and forms a pouch (recessus sacciformis) between 
 the lesser sigmoid cavity, the internal surface of the orbicular ligament, and the 
 
 EPIPHYSrAL 
 JUNCTION 
 
 EPIPHYSEAL 
 JUNCTION 
 
 Fig. 225. — Right elbow-joint, cut through at right angles to the 
 axis of the trochlea humeri, from the ulnar side. (Spalteholz.) 
 
THE ELBOW- JOINT 
 
 311 
 
 circumference of the head of the radius. Projecting into the cavity is a crescentic 
 fold of synovial membrane, between the radius and ulna, suggesting the division of 
 the joint into two : one the humero-radial, the other the humero-ulnar. 
 
 Between the capsular ligament and the synovial membrane are three masses 
 of fat: one, the largest, above the olecranon fossa, which is pressed into the fossa by 
 the Triceps during flexion; a second, over the coronoid fossa; and a third, over 
 the radial fossa. The two last-named pads are pressed into their respective fossae 
 during extension. 
 
 The muscles (Fig. 226) in relation with the joint are, in front, the Brachialis 
 anticus; behind, the Triceps and Anconeus; externallij, the Supinator brevis and 
 the common tendon of origin of the Ex- 
 tensor muscles ; internally, the common 
 tendon of origin of the Flexor muscles, and 
 the Flexor carpi ulnaris, with the ulnar 
 nerve. 
 
 The arteries supplying the joint are de- 
 rived from the anastomosis between the 
 superior profunda, inferior profunda, and 
 anastomotica magna, bi inches of the 
 brachial, with the anterior, posterior, and 
 interosseous recurrent branches of the 
 ulnar and the recurrent branch of the 
 radial. These vessels form a complete 
 chain of inosculation around the joint. 
 
 The nerves are derived from the ulnar 
 as it passes between the internal condyle 
 and the olecranon ; a filament from the 
 musculo-cutaneous (Riidinger), and two 
 filaments from the median (Macalister). 
 
 Bursse. — The olecranon bursa (bursa sub- 
 cutaneous olecrani) is placed between the 
 olecranon process and the cutaneous sur- 
 face. A bursa exists between the tendon 
 of the Biceps and the tubercle of the 
 radius {bursa bicipitoradialis) — another 
 between the Triceps tendon and the olec- 
 ranon process (bursa subtendinea olecrani) 
 — another between the cutaneous surface 
 
 and the external condyle (bursa subcutanea epicondyli humeri lateralis) — another 
 between the cutaneous surfr.ce and the internal condyle (bursa subcutanea 
 epicondyli humeri medialis — another within the Triceps tendon at its insertion on 
 the olecranon (bursa intratendinea olecrani). 
 
 Actions. — The elbow-joint comprises three different portions — viz., the joint 
 between the ulna and humerus, that between the head of the radius and the 
 humerus, and the superior radio-ulnar articulation, described below. All these 
 articular surfaces are invested by a common synovial membrane, and the move- 
 ments of the whole joint should be studied together. The combination of the 
 movements of flexion and extension of the forearm with those of pronation and 
 supination of the hand, which is ensured by the two being performed at the 
 same joint, is essential to the accuracy of the various minute movements of the 
 hand. 
 
 The portion of the joint between the ulna and humerus is a simple hinge- 
 joint, and allows of movements of flexion and extension only. Owing to the 
 obliquity of the trochlear surface of the humerus, this movement does not take 
 
 Fig. 226. — Sagittal section of the right elbow- 
 joint, taken somewhat obliquely and seen from the 
 radial aspect. (After Braune.) 
 
312 THE ARTICULATIONS OR JOINTS 
 
 place in a straight line; so that when the forearm is extended and supinated 
 the axis of the arm and forearm is not in the same line, but the one portion of the 
 limb forms an angle with the others, and the hand, with the forearm, is directed 
 outward. During flexion, on the other hand, the forearm and the hand tend to 
 approach the middle line of the body, and thus enable the hand to be easily 
 carried to the face. The shape of the articular surface of the humerus, with its 
 prominences and depressions accurately adapted to the opposing surfaces of 
 the olecranon, prevents any lateral movement. Flexion is produced by the 
 action of the Biceps and Brachialis anticus, assisted by the muscles arising from 
 the internal condyle of the humerus and the Supinator longus; extension, by the 
 Triceps and Anconeus, assisted by the extensors of the wrist and by the Extensor 
 communis digitorum and Extensor minimi digiti. 
 
 The joint between the head of the radius and the capitellum or radial head of 
 the humerus is an arthrodial joint. The bony surfaces would of themselves con- 
 stitute an enarthrosis, and allow of movement in all directions were it not for the 
 orbicular ligament by which the head of the radius is bound down firmly to the 
 sigmoid cavity of the ulna, and which prevents any separation of the two bones 
 laterally. It is to the same ligament that the head of the radius owes its security 
 from dislocation, which would otherwise constantly occur as a consequence of the 
 shallowness of the cup-like surface on the head of the radius. In fact, but for 
 this ligament the tendon of the biceps would be liable to pull the head of the 
 radius out of the joint. ^ In complete extension the head of the radius glides so 
 far back on the outer condyle that its edge is plainly felt at the back of the articu- 
 lation. Flexion and extension of the elbow-joint are limited by the tension of 
 the structures on the front and back of the joint, the limitation of flexion being 
 also aided by the soft structures of the arm and forearm coming in contact. 
 
 In combination with any position of flexion or extension the head of the radius 
 can be rotated in the upper radio-ulnar joint, carrying the hand with it. The 
 hand is directly articulated to the lower surface of the radius only, and the concave 
 or sigmoid surface on the lower end of the radius travels round the lower end of 
 the ulna. The latter bone is excluded from the wrist-joint (as will be seen in 
 the sequel) by the interarticular fibro-cartilage. Thus, rotation of the head of the 
 radius round an axis which passes through the centre of the radial head of the 
 humerus imparts circular movement to the hand through a very considerable 
 arc. 
 
 Surface Form. — If the forearm be slightly flexed on the arm, a curved crease or fold with 
 its convexity downward may be seen running across the front of the elbow, extending from one 
 condyle to the other. The centre of this fold is some slight distance above the line of the joint. 
 The position of the radio-humeral portion of the joint can be at once ascertained by feehng for a 
 slight groove or depression between the head of the radius and the capitellum of the humerus at 
 the back of the articulation. 
 
 Surgical Anatomy.^From the great breadth of the joint, and the manner in which the 
 articular surfaces are interlocked, and also on account of the strong lateral ligaments and 
 the support which the joint derives from the mass of muscles attached to each condyle of the 
 humerus, lateral displacement of the bones is very uncommon, whereas antero-posterior disloca- 
 tion, on account of the shortness of the antero-posterior diameter, the weakness of the anterior 
 and posterior ligaments, and the want of support of muscles, much more frequently takes place, 
 dislocation backward taking place when the forearm is in a position of extension, and forward 
 when in a position of flexion. For, in the former position, that of extension, the coronoid process 
 is not interlocked into the coronoid fossa, and loses its grip to a certain extent, whereas th(: 
 olecranon process is in the olecranon fossa, and entirely prevents displacement forward. On 
 the other hand, during flexion, the coronoid process is in the coronoid fossa, and prevents dis- 
 location backward, while the olecranon loses its grip and is not so efficient, as during extension, 
 in preventing a forward displacement. When lateral dislocation does take place, it is generally 
 incomplete. 
 
 1 Humphry, op cit., p. 419. 
 
RADIO- ULNAR ARTICULATION 313 
 
 Dislocation of the elbow-joint is of common occurrence in children, far more common than 
 dislocation of any other articulation, for, as a rule, fracture of a bone more frequently takes 
 place, under the application of any severe violence, in young persons than dislocation. In 
 lesions of this joint there is often very great difficulty in ascertaining the exact nature of the 
 injury. Sprain of the elbow is a very common injury in childhood. Injury to the radio- 
 humeral joint is frequently produced by lifting a child by the hand, as in swinging it over a 
 gutter. The supinator brevis, which under normal circumstances would retain the head of the 
 radius against the capitellum of the humerus, is unable to do so, the radio-humeral articulation 
 receives the force and the orbicular ligament undergoes upward displacement, is caught 
 between the head of the radius and the capitellum and jams the joint. ^ This injury is often 
 called subluxation of the head of the radius. 
 
 The elbow-joint is occasionally the seat of acute synovitis. The synovial membrane then 
 becomes distended with fluid, the bulging showing itself principally around the olecranon process ; 
 that is to say, on its inner and outer sides and above, in consequence of the laxness of the poste- 
 rior ligament. Occasionally a well-marked, triangular projection may be seen on the outer 
 side of the olecranon, from bulging of the synovial membrane beneath the Anconeus muscle. 
 Again, there is often some swelling just above the head of the radius, in the line of the radio- 
 humeral joint. There is generally not much swelling at the front of the joint, though sometimes 
 deep-seated fulness beneath the Brachialis anticus may be noted. When suppuration occurs the 
 abscess usually points at one or other border of the Triceps muscle; occasionally the pus dis- 
 charges itself in front, near the insertion of the Brachialis anticus muscle. Chronic synovitis, 
 usually of tuberculous origin, is of common occurrence in the elbow-joint: under these circum- 
 stances the forearm tends to assume the position of semi-flexion, which is that of greatest ease 
 and relaxation of ligaments. It should be borne in mind that should ankylosis occur in this or 
 the extended position, the limb will not be nearly so useful as if it becomes ankylosed in a position 
 of rather less than a right angle. Loose cartilages are sometimes met with in the elbow-joint, not 
 so commonly, however, as in the knee; nor do they, as a rule, give rise to such urgent symptoms. 
 They rarely require operative interference. The elbow-joint is also sometimes affected with 
 osteo-arthritis , but this affection is less common in this articulation than in some other of the 
 larger joints. Bursitis about the elbow is not uncommon. Enlargement of the subcutaneous 
 bursa over the olecranon is known as miners' elbow. Enlargement of any one of the bursse 
 may occur. 
 
 Excision of the elbow is principally required for one of three conditions — viz., tuberculous 
 arthritis, injury and its results, and ankylosis in a position which greatly impairs the. useful- 
 ness of the limb; but may be necessary for some other rarer conditions, such as disorganizing 
 arthritis after pyaemia, unreduced dislocation, and osteo-arthritis. The results of the opera- 
 tion are, as a rule, more favorable than those of excision of any other joint, and it is one, 
 therefore, that the surgeon should never hesitate to perform, especially in the first three of 
 the conditions mentioned above. The operation is best performed by a single vertical incision 
 down the back of the joint, a transverse incision, over the outer condyle, being added if the 
 p:irts are much thickened and fixed. A straight incision is made about four inches long, the 
 mid-point of which is on a level with and a little to the inner side of the tip of the olecra- 
 non. This incision is made down to the bone, through the substance of the Triceps muscle. 
 The operator with the point of his knife, and guarding the soft parts with his thumb-nail, 
 separates them from the bone. In doing this there are two structures which he should 
 carefully avoid: the ulnar nerve, which lies parallel to his incision, but a little internal, as it 
 courses down between the internal condyle and the olecranon process, and the prolongation of 
 the Triceps into the deep fascia of the forearm over the Anconeus muscle. Having cleared the 
 bones and divided the lateral and posterior ligaments, the forearm is strongly flexed and the 
 ends of the bone turned out and sawn off. The section of the humerus should be through 
 the base of the condyles, that of the ulna and radius should be just below the level of the lesser 
 sigmoid cavity of the ulna and the neck of the radius. In this operation the object is to obtain 
 such fibrous union as shall allow free motion of the bones of the forearm; and, therefore, passive 
 motion must be commenced early, that is to say, about the tenth day. 
 
 VI. Radio-ulnar Articulation (Articulatio Radioulnaris). 
 
 The articulation of the radius with the ulna is effected by ligaments which 
 connect together both extremities as well as the shafts of these bones. It may, 
 consequently, be subdivided into three articulations : (1) the superior radio-ulnar, 
 which is a portion of the elbow-joint; (2) the middle radio-ulnar; and (3) the infe- 
 rior radio-ulnar articulations. 
 
 ^ Mr. Jonathan Hutchinson, Jr., in Annals of Surgery, August, 1885. 
 
314 THE ARTICULATIONS OB JOINTS 
 
 1. Superior or Proximal Radio-ulnar Articulation (Articulatio 
 Radioulnaris Proximalis). 
 
 This articulation is a trochoid or pivot-joint. The bones entering into its forma- 
 tion are the inner side of the circumference of the head of the radius rotating within 
 the lesser sigmoid cavity of the ulna. Its only ligament is the annular or orbicular. 
 
 The Orbicular or Annular Ligament {ligamentum annulare radii) (Figs. 223, 224, 
 and 227) is a strong, flat band of ligamentous fibres which surrounds the head of 
 the radius and retains it in firm connection with the lesser sigmoid cavity of the 
 ulna. It forms about four-fifths of an osseo-fibrous ring, attached by each end to 
 the extremities of the lesser sigmoid cavity, and is smaller at the lower part of its 
 circumference than above, by which means the head of the radius is more securely 
 held in its position. Its outer surface is strengthened by the external lateral 
 ligament of the elbow, and affords origin to part of the Supinator brevis muscle. 
 Its inner surface is smooth, and lined by synovial membrane. The synovial 
 membrane is continuous with that which lines the elbow-joint. 
 
 Actions. — ^The movement which takes place in this articulation is limited to 
 rotation of the head of the radius within the orbicular ligament, and upon the 
 lesser sigmoid cavity of the ulna, rotation forward being called pronation; rotation 
 backward, supination. Supination is performed by the Biceps and Supinator 
 brevis, assisted to a slight extent by the Extensor muscles of the thumb and, 
 in certain positions, by the Supinator longus. Pronation is performed by the 
 Pronator radii teres and the Pronator quadratus, assisted, in some positions, by 
 the Supinator longus. 
 
 Surface Form. — The position of the superior radio-ulnar joint is marked on the surface of 
 the body by the little dimple on the back of the elbow which indicates the position of the head 
 of the radius. 
 
 Surgical Anatomy. — Dislocation of the head of the radius alone is not an uncommon acci- 
 dent, and occurs most frequently in young persons from falls on the hand when the forearm is 
 extended and supinated, the head of the bone being displaced forward. It is attended by rup- 
 ture of the orbicular ligament. Occasionally a peculiar injury, which is supposed to be a sub- 
 luxation, occurs in young children in lifting them from the ground by the hand or forearm. It 
 is believed that the head of the radius is displaced downward or the orbicular ligament upward, 
 and the upper border of the ligament becomes folded over the head of the radius, between it and 
 the capitellum of the humerus. 
 
 2. Middle Radio-ulnar Ligaments. 
 
 The interval between the shafts of the radius and ulna is occupied by two 
 ligaments. 
 
 Oblique. Interosseous. 
 
 The Oblique or Round Ligament (chorda obliqua) (Figs. 223 and 225) is a small^ 
 flattened fibrous band which extends obliquely downward and outward from the 
 tubercle of the ulna at the base of the coronoid process to the radius a little below 
 the bicipital tuberosity. Its fibres run in the opposite direction to those of the 
 interosseous ligament, and it appears to be placed as a substitute for it in the 
 upper part of the interosseous interval. This ligament is sometimes wanting. 
 
 The Interosseous Membrane (membrana interossea antibrachii) (Fig. 227) is a 
 broad and thin plane of fibrous tissue descending obliquely downward and inward, 
 from the interosseous ridge on the radius to that on the ulna. It is deficient above, 
 commencing about an inch beneath the tubercle of the radius; is broader in the 
 middle than at either extremity; and presents an oval aperture just above its 
 lower margin for the passage of the anterior interosseous vessels to the back of 
 the forearm. This ligament serves to connect the bones and to increase the 
 extent of surface for the attachment of the deep muscles. Between its upper 
 
BADIO- ULNAR ARTICULATION 
 
 315 
 
 ANNULAR LIGAMENT 
 OF RADI 
 
 TENDON OF 
 BICEPS MUSCL 
 
 (cut through) 
 
 OBLIQUE 
 LICAMENT 
 
 INTEROSSEOUS 
 MEMBRANE 
 
 border and the oblique ligament an interval exists through which the posterior 
 interosseous vessels pass to the dorsum of the forearm. Two or three 
 fibrous bands are occasionally found 
 on the posterior surface of this mem- 
 brane which descend obliquely from 
 the ulna toward the radius, and which 
 have consequently a direction contrary 
 to that of the other fibres. It is in 
 relation, in front, by its upper three- 
 fourths with the Flexor longus pollicis 
 on the outer side, and with the Flexor 
 profundus digitorum on the inner, lying 
 upon the interval between which are 
 the anterior interosseous vessels and 
 nerve ; by its lower fourth, with the 
 Pronator quadratus; behind, with the 
 Supinator brevis. Extensor ossis meta- 
 carpi pollicis, Extensor brevis pollicis, 
 Extensor longus pollicis, Extensor in- 
 dicis; and, near the wrist, with the 
 anterior interosseous artery and poste- 
 rior interosseous nerve. 
 
 3. Inferior or Distal Radio-ulnar 
 Articulation (Articulatio Ra- 
 
 DIOULNARIS DiSTALIS). 
 
 ■ This is a pivot-joint, formed by the 
 sigmoid cavity at the inner side of the 
 lower end of the radius receiving the 
 head of the ulna. The articular sur- 
 faces are covered by a thin layer of 
 cartilage, and connected together by a 
 capsule (capsula articularis) , portions 
 of which are usually described as dis- 
 tinct ligaments. The ligaments of the 
 articulation are: 
 
 Anterior Radio-ulnar. 
 Posterior Radio-ulnar. 
 Triangular Interarticular Fibro- 
 cartilage. 
 
 The Anterior Radio-ulnax Ligament 
 (Fig. 228) is a narrow band of fibres 
 extending from the anterior margin of 
 the sigmoid cavity of the radius to the 
 anterior surface of the head of the ulna. 
 
 The Posterior Radio-ulnar Ligament 
 (Fig, 229) extends between similar 
 points on the posterior surface of the 
 articulation. 
 
 The Triangular Interarticular Fibro-cartilage (discus articularis) (Figs. 227 and 231) 
 is triangular in shape, and is placed transversely beneath the head of the ulna, 
 binding the lower end of this bone and the radius firmly together. Its periphery 
 
 Fig. 227. — Bones of the right forearm, with ligaments 
 from the volar .surface. (Spalteholz.) 
 
31G 
 
 THE ARTICULATIONS OB JOINTS 
 
 is thicker than its centre, which is thin and occasionally perforated. It is attached 
 by its apex to a depression which separates the styloid process of the ulna from 
 the head of that bone; and by its base, which is thin, to the prominent edge of 
 
 Inferior radio-ulnar 
 articulation. 
 
 ■joint. 
 
 ticulations. 
 
 metacarpal 
 •ulations. 
 
 Fig. 228. — Ligament.s of wrist and hand. Anterior view. 
 
 the radius, which separates the sigmoid cavity from the carpal articulating sur- 
 face. Its margins are united to the ligaments of the wrist-joint. Its iipper sur- 
 face, smooth and concave, articulates with the head of the ulna, forming an 
 
 Inferior radio-iUnar 
 
 articulation 
 
 Wrist-joint 
 Carpal articulations. 
 
 Carpo-metacarpal 
 
 articulations, 
 
 Fig. 229. — Ligaments of wrist and hand. Posterior view. 
 
 arthrodial joint; its under surface, also concave and smooth, forms part of the 
 wrist-joint and articulates with the cuneiform and inner part of the semilunar 
 bone. Both surfaces are lined by a synovial membrane — the upper surface, by 
 
RADIO -CARPAL OR WRIST -JOINT 
 
 317 
 
 one peculiar to the radio-ulnar articulation; the under surface, by the synovial 
 membrane of the wrist. 
 
 Synovial Membrane. — The synovial membrane (Fig. 231) of this articulation 
 has been called, from its- extreme looseness, the membrana sacciformis. It projects 
 horizontally inward between the head of the ulna and the interarticular fibro- 
 cartilage, and upward between the radius and the ulna, forming a very loose 
 cul-de-sac {recessus sacciformis). The quantity 
 of synovia which it contains is usually consider- 
 able. The inferior radio-ulnar joint does not 
 communicate with the wrist-joint. 
 
 Actions.— The movement in the inferior radio- 
 ulnar articulation is just the reverse of that in 
 the superior radio-ulnar joint. It consists of a 
 movement of rotation of the lower end of the 
 radius round an axis which corresponds to the 
 centre of the head of the ulna. When the radius 
 rotates forward, pronation of the forearm and 
 hand is the result; and when backward, supina- 
 tion. It will thus be seen that in pronation and 
 supination of the forearm and hand the radius 
 describes a segment of a cone, the axis of which 
 extends from the centre of the head of the radius 
 to the middle of the head of the ulna. In this 
 movement, however, the ulna is not quite sta- 
 tionary, but rotates a little in the opposite direc- 
 tion. So that it also describes the segment of a 
 cone, though of smaller size than that described 
 by the radius. The movement which causes this 
 alteration in the position of the head of the ulna 
 takes place principally at the shoulder-joint by a 
 rotation of the humerus, but possibly also to a 
 slight extent at the elbow-joint.^ 
 
 Surface Form. — The position of the inferior radio- 
 ulnar joint may be ascertained by feeling for a slight 
 groove at the back of the wrist, between the prominent 
 head of the ulna and the lower end of the radius, when 
 the forearm is in a state of almost complete pronation. 
 
 VII. Radio-carpal or Wrist-joint (Articulatio 
 Radiocarpea) (Figs. 228, 229, 231). 
 
 The wrist is a condyloid articulation. The 
 parts entering into its formation are the lower 
 end of the radius and under surface of the 
 interarticular fibro-cartilage, which form together 
 the receiving cavity, and the scaphoid, semilunar, 
 and the cuneiform bones, which form the condyle. The articular surface of the 
 radius and the under surface of the interarticular fibro-cartilage are the receiving 
 cavity, forming together a transversely elliptical concave surface. The articular 
 surfaces of the scaphoid, semilunar, and cuneiform bones form together a smooth, 
 convex surface, the condyle, which is received into the concavity above men- 
 tioned. All the bony surfaces of the articulation are covered with cartilage, and 
 
 Fig. 230. — Longitudinal section of the 
 
 right forearm, hand, and third finger, 
 
 viewed from the ulnar aspect. (Afier 
 Braune.) 
 
 1 See Journal of Anatomy and Physiology, vol. xix., parts ii., iii., and iv. 
 
318 THE ARTICULATIONS OB JOINTS 
 
 connected together by a loose capsule (capsula articularis) , which is divided into 
 the following ligaments : 
 
 External Lateral. Anterior. 
 
 Internal Lateral. Posterior. 
 
 • 
 
 The External Lateral Ligament ( ligamentum collaterale carpi radiate) (Fig. 228) 
 extends from the summit of the styloid process of the radius to the outer side of 
 the scaphoid, some of its fibres being prolonged to the trapezium and annular 
 ligament. 
 
 The Internal Lateral Ligament {ligamentum collaterale carpi ulnare) (Fig. 228) 
 is a rounded cord, attached, above, to the extremity of the styloid process of the 
 ulna, and dividing below into two fasciculi, which are attached, one to the inner 
 side of the cuneiform bone, the other to the pisiform bone and annular ligament. 
 
 The Anterior or Volar Ligament {ligamentum radiocarpeum volare) (Fig. 228j 
 is a broad, membranous band, attached, above, to the anterior margin of the 
 lower end of the radius, its styloid process, and the ulna : its fibres pass downward 
 and inward to be inserted i^to the palmar surface of the scaphoid, semilunar, 
 and cuneiform bones, some of the fibres being continued to the os magnum. In 
 addition to this broad membrane there is a distinct rounded fasciculus, superficial 
 to the rest, which passes from the base of the styloid process of the ulna to 
 the semilunar and cuneiform bones. This ligament is perforated by numerous 
 apertures for the passage of vessels, and is in relation, in front, with the tendons 
 of the Flexor profundus digitorum and Flexor longus pollicis; behind, with the 
 synovial membrane of the wrist-joint. 
 
 The Posterior or Dorsal Ligament (ligamentum radiocarpeum dorsale) (Fig. 229), 
 less thick and strong than the anterior, is attached, above, to the posterior border 
 of the lower end of the radius; its fibres pass obliquely downward and inward, to 
 be attached to the dorsal surface of the scaphoid, semilunar, and cuneiform bones, 
 being continuous with those of the dorsal carpal ligaments. This ligament is in 
 relation, behind, with the extensor tendons of the fingers; in front, with the syno- 
 vial membrane of the wrist. 
 
 S3movial Membrane. — The synovial membrane (Fig. 231) lines the inner sur- 
 face of the ligaments above described, extending from the lower end of the radius 
 and interarticular fibro-cartilage above to the articular surfaces of the carpal bones 
 below. It is loose and lax, and presents numerous folds, especially behind. 
 
 Relations. — The wrist-joint is covered in front by the flexor and behind by the 
 extensor tendons (Fig; 230); it is also in relation with the radial and ulnar 
 arteries. 
 
 The arteries supplying the joint are the anterior and posterior carpal branches 
 of the radial and ulnar, the anterior and posterior interosseous, and some ascend- 
 ing branches from the deep palmar arch. 
 
 The nerves are derived from the ulnar and posterior interosseous. 
 
 Actions. — The movements permitted in this joint are flexion, extension, abduc- 
 tion, adduction, and circumduction. Its actions will be further studied with those 
 of the carpus, with which they are combined. 
 
 Surface Form. — The line of the radio-carpal joint is on a level with the apex of the styloid 
 process of the ulna. 
 
 Surgical Anatomy. — The wrist-joint is rarely dislocated, its strength depending mainly 
 upon the numerous strong tendons which surround the articulation. Its security is further pro- 
 vided for by the number of small bones of which the carpus is made up, and which are united 
 by very strong ligaments. The slight movement which takes place between the several bones 
 serves to break the jars that result from falls or blows on the hand. Dislocation backward, 
 which is the more common dislocation, simulates to a considerable extent Colles's fracture of the 
 radius, and is liable to be mistaken for it. The diagnosis can be easily made out by observing 
 the relative position of the styloid processes of the radius and the ulna. " In the natural condition 
 
ARTICULATIONS OF THE CARPUS 319 
 
 the styloid process of the radius is on a lower level — i. e., nearer the ground — when the arm hangs 
 by the side, than that of the ulna, and the same would be the case in dislocation. In Colles's 
 fracture, on the other hand, the styloid process of the radius is on the same or even a higher 
 level than that of the ulna. 
 
 The wrist-joint is occasionally the seat of (wute synovitis, the result of traumatism or arising 
 in the rheumatic or pya?mic state. When the synovial sac is distended with fluid, the swelling 
 is greatest on the dorsal aspect of the wrist, showing a general fulness, with some bulging between 
 the tendons. The inflammation is prone to extend to the intercarpal joints and to attack also 
 the sheaths of the tendons in the neighborhood. Chronic inflammation of the wrist is generally 
 tuberculous, and often leads to similar disease in the synovial sheaths of adjacent tendons and of 
 the intercarpal joints. The disease, therefore, when progressive, often leads to necrosis of the 
 car{>al bones, and the result is often unsatisfactory. 
 
 VIII. Articulations of the Carpus (Articulatio Intercarpea) 
 
 (Figs. 228, 229, 231). 
 
 These articulations may be subdivided into three sets: 
 
 1. The Articulations of the First Row of Carpal Bones. 
 
 2. The Articulations of the Second Row of Carpal Bones. 
 
 3. The Articulations of the Two Rows with each other. 
 
 1. Articulations of the First Row of Carpal Bones. 
 
 These are arthrodial joints. The ligaments connecting the scaphoid, semi- 
 lunar, and cuneiform bones are — 
 
 Dorsal. Palmar. 
 
 Two Interosseous 
 
 The Dorsal Ligaments (ligamenta intercarpea dorsalia) are placed transversely 
 behind the bones of the first row; they connect the scaphoid and semilunar and 
 the semilunar and cuneiform. 
 
 The Palmar or Volar Ligaments {ligamenta intercarpea volaria) connect the 
 scaphoid and semilunar and the semilunar and cuneiform bones; they are less 
 strong than the dorsal, and placed very deeply below the anterior ligament of 
 the wrist. 
 
 The Interosseous Ligaments {ligamenta intercarpea interossea) (Fig. 231) are two 
 narrow bundles of fibrous tissue connecting the semilunar bone on one side with 
 the scaphoid, and on the other with the cuneiform. They are on a level with 
 the superior surfaces of these bones, and close the upper part of the spaces 
 between them. Their upper surfaces are smooth, and form with the bones the 
 convex articular surfaces of the wrist-joint. 
 
 The ligaments connecting the pisiform bone are — 
 
 Capsular. Two Palmar Ligaments. 
 
 The Capsular Ligament {capsula articularis) is a thin membrane which con- 
 nects the pisiform bone to the cuneiform. It is lined with a separate synovial 
 membrane. 
 
 The Two Palmar Ligaments are two strong fibrous bands which connect the 
 pisiform to the unciform, the piso-uncinate ligament (ligamentum pisohamatum) , 
 and to the base of the fifth metacarpal bone, the piso-metacarpal ligament {liga- 
 mentum pisometacarpeum) . 
 
 2. Articulations of the Second Row of Carpal Bones. 
 
 These are also arthrodial joints. The articular surfaces are covered with 
 cartilage, and connected by the following ligaments: 
 
 Dorsal. Palmar. 
 
 Three Interosseous. 
 
320 THE ARTICULATIONS OB JOINTS 
 
 The Dorsal Ligaments (ligamenta intercarpea dorsalia) extend transversely from 
 one bone to another on the dorsal surface, connecting the trapezium with the trape- 
 zoid, the trapezoid with the os magnum, and the os magnum with the unciform. 
 
 The Palmar or Volar Ligaments (ligamenta intercarpea volaria) have a similar 
 arrangement on the palmar surface. 
 
 The Three Interosseous Ligaments (ligamenta intercarpea interossea) (Fig. 231) 
 much thicker than those of the first row, are placed one between the os magnum 
 and the unciform, a second between the os magnum and the trapezoid, and a 
 third between the trapezium and trapezoid. The first of these is much the 
 strongest, and the third is sometimes wanting. 
 
 3. Articulations of the Two Rows of Carpal Bones with Each Other 
 
 (Figs. 228,229, 231). 
 
 The joint between fhe scaphoid, semilunar, and cuneiform, and the second row 
 of the carpus, or the mid-carpal joint, is made up of three distinct portions; in the 
 centre the head of the os magnum and the superior surface of the unciform 
 articulate with the deep, cup-shaped cavity formed by the scaphoid and semi- 
 lunar bones, and constitute a sort of ball-and-socket joint. On the outer side 
 the trapezium and trapezoid articulate with the scaphoid, and on the inner side 
 the unciform articulates with the cuneiform, forming gliding joints. 
 
 The ligaments are : 
 
 Anterior. External Lateral. 
 
 Posterior. Internal Lateral. 
 
 The Anterior, Palmar, or Volar Ligaments {ligamenta intercarpea volaria) consist 
 of short fibres, which pass, for the most part, from the palmar surface of the bones 
 of the first row to the front of the os magnum. 
 
 The Posterior or Dorsal Ligaments (ligamenta intercarpea dorsalia) consist of 
 short, irregular bundles of fibres passing between the bones of the first and second 
 row on the dorsal surface of the carpus. 
 
 The Lateral Ligaments are very short: they are placed, one on the radial, the 
 other on the ulnar side of the carpus; the former, the stronger and more distinct, 
 connecting the scaphoid and trapezium bones, the latter the cuneiform and unci- 
 form; they are continuous with the lateral ligaments of the wrist-joint. In addi- 
 tion to these ligaments, a slender interosseous band sometimes connects the os 
 magnum and the scaphoid. 
 
 Synovial Membrane (Fig. 231). — The synovial membrane of the carpus is very 
 extensive: it passes from the under surface of the scaphoid, semilunar, and cunei- 
 form bones to the upper surface of the bones of the second row, sending upward 
 two prolongations — between the scaphoid and semilunar and the semilunar and 
 cuneiform ; sending downward three prolongations between the four bones of the 
 second row, which are further continued onward into the carpo-metacarpal 
 joints of the four inner metacarpal bones, and also for a short distance between 
 the metacarpal bones. There is a separate synovial membrane between the 
 pisiform and cuneiform bones. 
 
 Actions. — The articulation of the hand and wrist, considered as a whole, is 
 divided into three parts: (1) the radius and the i ntef articular fibro-cartilage ; 
 (2) the meniscus, formed by the scaphoid, semilunar, and cuneiform, the pisiform 
 bone having no essential part in the movements of the hand; (3) the hand proper, 
 the metacarpal bones with the four carpal bones on which they are supported — viz., 
 the trapezium, trapezoid, os magnum, and imciform. These three elements form 
 two joints: (1) the superior, wrist-joint proper, between the meniscus and bones 
 of the forearm; (2) the inferior, between the hand and meniscus, transverse or 
 mid-carpal joint. 
 
CARPO- METACARPAL ARTICULATIONS 321 
 
 (1) The articulation between the forearm and carpus is a true condyloid artic- 
 ulation, and therefore all movements but rotation are permitted. Flexion and 
 extension are the most free, and of these a greater amount of extension than 
 flexion is permitted on account of the articulating surfaces extending farther on 
 the dorsal than on the palmar aspect of the carpal bones. In this movement the 
 carpal bones rotate on a transverse axis drawn between the tips of the styloid 
 processes of the radius and ulna. A certain amount of adduction (or ulnar 
 flexion) and abduction (or radial flexion) is also permitted. Of these the former 
 is considerably greater in extent than the latter. In this movement the carpus 
 revolves upon an antero-posterior axis drawn through the centre of the wrist. 
 Finally, circumduction is permitted by the consecutive movements of adduction, 
 extension, abduction, and flexion, with intermediate movements between them. 
 There is no rotation, but this is provided for by the supination and pronation 
 of the radius on the ulna. The movement of flexion is performed by the Flexor 
 carpi radialis, the Flexor carpi ulnaris, and the Palmaris longus; extension, 
 by the Extensor carpi radialis longior et brevior and the Extensor carpi 
 ulnaris; adduction (ulnar flexion), by the Flexor carpi ulnaris and the Ex- 
 tensor carpi ulnaris; and abduction (radial flexion), by the Extensors of the 
 thumb and the Extensor carpi radialis longior et brevior and the Flexor carpi 
 radialis. 
 
 (2) The chief movements permitted in the transverse or mid-carpal joint are 
 flexion and extension and a slight amount of rotation. In flexion and extension, 
 which is the movement most freely enjoyed, the trapezium and trapezoid on the 
 radial side and the unciform on the ulnar side glide forward and backward on the 
 scaphoid and cuneiform respectively, while the head of the os magnum and the 
 superior surface of the unciform rotate in the cup-shaped cavity of the scaphoid 
 anfl semilunar. Flexion at this joint is freer than extension. A very trifling 
 amount of rotation is also permitted, the head of the os magnum rotating round a 
 vertical axis drawn through its own centre, while at the same time a slight gliding 
 movement takes place in the lateral portions of the joint. 
 
 IX. Carpo-metacarpal Articulations (Articulationes Carpometacarpese) 
 
 (Figs. 228, 229, 231). 
 
 1. Articulation of the Metacarpal Bone of the Thumb with the 
 Trapezium (Articulatio Carpometacarpea Pollicis). 
 
 This is a joint of reciprocal reception, and enjoys great freedom of movement, 
 on account of the configuration of its articular surfaces, which are saddle-shaped, 
 so that, on section, each bone appears to be received into a cavity in the other, 
 according to the direction in which they are cut. The joint is surrounded by a 
 capsular ligament. 
 
 The Capsular Ligament (capsula articularis) is thick and fibrous, but loose, 
 and passes from the circumference of the upper extremity of the meta- 
 carpal bone to the rough edge bounding the articular surface of the trape- 
 zium; it is thickest externally and behind, and lined by a separate synovial 
 membrane. 
 
 Movements. — In the articulation of the metacarpal bone of the thumb w^ith the 
 trapezium the movements permitted are flexion, extension, adduction, abduction, 
 and circumduction. When the joint is flexed the metacarpal bone is brought in 
 front of the palm and the thumb is gradually turned to the fingers. It is by this 
 peculiar movement that the tip of the thumb is opposed to the other digits; for 
 by slightly flexing the fingers the palmar surface of the thumb can be brought in 
 contact with their palmar surfaces one after another. 
 
 21 
 
322 
 
 THE ARTICULATIONS OB JOINTS 
 
 2. Articulations of the Metacarpal Bones of the Four Inner Fingers 
 WITH THE Carpus (Articulationes Carpometacarpe.^). 
 
 The joints formed between the carpus and four inner metacarpal bones are 
 arthrodial joints. The Hgaments are — 
 
 Dorsal. 
 
 Palmar. 
 
 Interosseous. 
 
 The Dorsal Ligaments (Hgamenta carpometacarpea dorsalia), the strongest and 
 most distinct, connect the carpal and metacarpal bones on their dorsal surface. 
 
 EPIPHYSEAL 
 JUNCTION 
 
 MEMBRANA SACCI- 
 
 FORMIS OF INFERIOR 
 
 RADIO-ULNAR 
 
 ARTICULATION 
 
 TRIANGULAR 
 FIBRO-CARTILAGE 
 
 STYLOID PROCESS 
 OF ULNA 
 
 EPIPHYSEAL 
 JUNCTION 
 
 RADIO-CARPAL 
 ARTICULATION 
 
 INTEROSSEOUS 
 LIGAMENT 
 
 INTEROSSEOUS 
 LIGAMENT 
 
 INTERMETACARPAL 
 ARTICULATION 
 
 INTERCARPAL 
 ATION 
 
 RTICULATION OF 
 RAPEZIUM AND 
 
 ETACARPAL BONE 
 
 F THUMB 
 
 A RPO- METACARPAL 
 RTICULATION 
 
 METACARPAL BONES 
 
 Fig. 231. — Joints of the right hand, from the back of the hand. (Spalteholz.) 
 
 The second metacarpal bone receives two fasciculi — one from the trapezium, 
 the other from the trapezoid; the third metacarpal receives two — one from 
 the trapezoid and one from the os magnum; the fourth two — one from the os 
 magnum and one from the unciform; the fifth receives a single fasciculus from 
 the unciform bone, which is continuous with a similar ligament on the palmar 
 surface, forming an incomplete capsule. 
 
 The Palmar or Volar Ligaments (liqamenta carpometacarpea volaria) have a 
 somewhat similar arrangement on the palmar surface, with the exception of 
 the third metacarpal, which has three ligaments — an external one from the 
 
CABPO - METACARPAL ARTICULATIONS 
 
 323 
 
 trapezium, situated above the sheath of the tendon of the Flexor carpi radialis; 
 a middle one, from the os magnum; and an internal one, from the unciform. 
 
 The Interosseous Ligaments consist of short, thick fibres, which are limited to 
 one part of the carpo-metacarpal articulation ; they connect the contiguous inferior 
 angles of the os magnum and unciform with the adjacent surfaces of the third 
 and fourth metacarpal bones. 
 
 Synovial Membrane. — The synovial membrane is a continuation of that between 
 the two rows of carpal bones. Occasionally, the articulation of the unciform 
 with the fourth and fifth metacarpal bones has a separate synovial membrane. 
 
 The synovial membranes of the wrist and carpus (Fig. 231) are thus seen to 
 be five in number. The first, the membrana sacciformis or the recessus sacciformis 
 of the inferior radio-ulnar articulation, passes from the lower end of the ulna to 
 
 TENDON OF FLEXOR 
 8UBLIMIS OIGITORUM 
 
 TENDON OF FLEXOR 
 PROFUNDUS OIGITORUM 
 
 ANTERIOR 
 
 OR VAGINAL 
 
 LIGAMENT 
 
 TRANSVERSE 
 
 METACARPAL 
 
 LIGAMENT 
 
 LATERAL 
 LIGAMENT 
 
 SECOND LUM- 
 BRICAL MUSCLE 
 
 ANTERIOR OR SECOND 
 
 VAGINAL LIGAMENT PALMAR 
 
 INTEROSSEOUS 
 MUSCLE 
 
 ANTERIOR OR 
 VAGINAL LIGAMENT 
 
 Fig. 232. — Metacarpal bones and first phalanges of the second to the fifth finger of the right hand, with 
 ligaments, from the volar surface. (Spalteholz.) 
 
 the sigmoid cavity of the radius, and lines the upper surface of the interarticular 
 fibro-cartilage. The second passes from the lower end of the radius and inter- 
 articular fibro-cartilage above to the bones of the first row below, The third, 
 the most extensive, passes between the contiguous margins of the two rows of 
 carpal l)ones— between the bones of the second row to the carpal extremities of 
 the four inner metacarpal bones. The fourth,^ from the margin of the trapezium 
 to the metacarpal bone of the thumb. The fifth, between the adjacent margins 
 of the cuneiform and pisiform bones. 
 
 Actions. — The movement permitted in the carpo-metacarpal articulations of the 
 four inner fingers is limited to a slight gliding of the articular surfaces upon each 
 other, the extent of which varies in the difi'erent joints. Thus the articulation of the 
 metacarpal bone of the little finger is most movable, then that of the ring finger. 
 The metacarpal bones of the index and middle fingers are almost immovable. 
 
324 
 
 THE ARTICULATIONS OB JOINTS 
 
 »nO ^ft^ 
 
 3. Articulations of the Metacarpal Bones with Each Other (Articu- 
 LATiONES Intermetacarpe^ (Figs. 228, 229, 231). 
 
 The carpal extremities of the four inner metacarpal bones articulate with 
 one another at each side by small surfaces covered with cartilages, and connected 
 together by dorsal, palmar, and interosseous ligaments. 
 
 The Dorsal Ligaments {ligamenta hasium oss. 7netacarp. dorsalia) and Palmar 
 Ligaments (ligamenta hasium oss. metacarp. volaria) pass transversely from one 
 
 bone to another on the dorsal and palmar sur- 
 faces. 
 
 The Interosseous Ligaments (ligamenta hasium 
 oss. metacarp. interossea) pass between their con- 
 tiguous surfaces, just beneath their lateral artic- 
 ular facets. 
 
 Synovial Membrane (Fig. 231). — The synovial 
 membrane between the lateral facets is a reflec- 
 tion from that between the two rows of carpal 
 bones. 
 
 The Transverse Metacarpal Ligament {Uga- 
 nentum capitulorum oss. metacarpalium trans- 
 versum) (Fig. 232) is a narrow, fibrous band 
 which passes transversely across the anterior sur- 
 faces of the digital extremities of the four inner 
 ^\\"^^3I metacarpal bones, connecting them together. It 
 
 is blended anteriorly with the palmar ligaments 
 of the metacarpo-phalangeal articulations. To 
 its posterior border is connected the fascia which 
 covers the Interossei muscles. Its anterior sur- 
 face is concave where the flexor tendons pass 
 over it. Behind it the tendons of the Interossei 
 muscles pass to their insertion. 
 
 X. Metacarpo-phalangeal Articulations f Artic- 
 
 ulationes Metacarpo-phalangeae; 
 
 (Figs. 232, 233). 
 
 These articulations are of the condyloid kind, 
 formed by the reception of the rounded head of 
 the metacarpal bone into a shallow cavity in the 
 extremity of the first phalanx. The expansion 
 of the extensor tendon acts as a dorsal ligament. 
 There is a capsular ligament which at certain 
 points has strengthening ligaments. The liga- 
 ments are — 
 
 ARTICULAR 
 CAPSULC 
 
 LATERAL 
 
 'ligament 
 
 ARTICULAR. 
 CAPSULE 
 
 LATERAL 
 
 'ligament 
 
 
 articular 
 capsule' 
 
 LATERAL 
 'LIGAMEM 
 
 Anterior. 
 
 Two Lateral. 
 
 The Anterior, Palmar, or Vaginal Ligament 
 
 (glenoid ligament of Cruveilhier, ligamentum 
 _ vaginale) is a thick, dense, fibrous structure, 
 
 phai'aAges ofThefSfing^r"ofthe'lfght placed on the palmar surface of the joint in the 
 (sArhoS^'"""*''''""'^"''"^'"'"^"- interval between the lateral ligaments, to which 
 
 it is connected ; it is loosely united to the meta- 
 carpal bone, but very firmly to the base of the first phalanx. Its palmar surface 
 is intimately blended with the transverse metacarpal ligament, and presents a 
 
THE HIP -JOINT 
 
 325 
 
 groove for the passage of the flexor tendons, the sheath surrounding which is 
 connected to each side of the groove. By its deep surface it forms part of the 
 articular surface for the head of the metacarpal bone, and is lined by a synovial 
 membrane. 
 
 The Lateral or Collateral Ligaments (ligamenta collateralia) are strong, rounded 
 cords placed one on each side of the joint, each being attached by one extremity 
 to the posterior tubercle on the side of the head of the metacarpal bone, and by 
 the other to the contiguous extremity of the phalanx. 
 
 Actions. — The movements which occur in these joints are flexion, extension, 
 adduction, abduction, and circumduction ; the lateral movements are very limited. 
 
 Surface Form. — The prominences of the knuckles do not correspond to the position of the 
 joints either of the metacarpo-phalangeal or interphalangeal articulations. These prominences 
 are invariably formed by the distal ends of the proximal bone of each joint, and the line indi- 
 cating the position of the joint must be sought considerably in front of the middle of the knuckle. 
 The usual rule for finding these joints is to flex the distal phalanx on the proximal one to a right 
 angle; the position of the joint is then indicated by an imaginary line drawn along the middle of 
 the lateral aspect of the proximal phalanx. 
 
 XI. Articulations of the Phalanges (Articulationes Digitorum Manus) 
 
 (Fig. 233). 
 
 These are ginglymus joints. Each joint has a capsule, and certain accentuated 
 portions are regarded as definite ligaments. These ligaments are — 
 
 Anterior or Palmar. 
 
 Two Lateral (ligamenta collateralia). 
 
 The arrangement of these ligaments is similar to those in the metacarpo- 
 phalangeal articulations; the extensor tendon supplies the place of a dorsal 
 ligament. 
 
 Actions. — The only movements permitted in the phalangeal joints are flexion 
 and extension; these movements are more extensive between the first and second 
 phalanges than between the second and third. The movement of flexion is very 
 considerable, but extension is limited by the anterior and lateral ligaments. 
 
 ARTICULATIONS OF THE LOWER EXTREMITY. 
 
 The articulations of the Lower Extremity comprise the following groups: 
 
 L The Hip-joint. 
 IL The Knee-joint. 
 in. The Articulations between the 
 
 Tibia and Fibula. 
 IV. The Ankle-joint. 
 V. The Articidations of the Tarsus. 
 
 VI. TheTarso-metatarsal Articulations. 
 VII. Articulations of the Metatarsal 
 
 Bones with each other. 
 VIII. The Metatarso-phalangeal Artic- 
 ulations. 
 IX. The Articulations of the Phalanges. 
 
 I. The Hip-joint (Articulatio Coxae) (Figs. 234, 235, 236, 237, 238, 239). 
 
 This articulation is an enarthrodial or ball-and-socket joint, formed by the 
 reception of the head of the femur into the cup-shaped cavity of the acetabulum. 
 The articulating surfaces are covered with cartilage, that on the head of the femur 
 being thicker at the centre than at the circumference, and covering the entire 
 surface, with the exception of a depression just below its centre for the ligamen- 
 tum teres; that covering the acetabulum is much thinner at the centre than at 
 the circumference. It forms an incomplete cartilaginous ring of a horseshoe 
 shape, being deficient below, where there is a circular depression, which is occu- 
 
326 
 
 THE ARTICULATIONS OB JOINTS 
 
 pied in the recent state by a mass of fat covered by synovial membrane. The 
 ligaments of the joints are the 
 
 Capsular. 
 Ilio-femoral. 
 
 Transverse. 
 
 Teres. 
 Cotyloid. 
 
 The Capsular Ligament {capsula articularis) (Figs. 234, 235, 237, and 239) is a 
 strong, dense, ligamentous capsule, embracing the margin of the acetabulum 
 above and surrounding the neck of the femur below. Its upper circumference 
 
 ANTERIOR INFERIOR 1 
 
 SPINE OF ILIUM 
 
 rElMO R A« 
 
 
 AiviEN-y^^y/^V^y;^ 
 
 LESSER 
 TROCHANTER 
 
 Fig. 234. — Right hip-joint, from in front. (Spalteholz.) 
 
 is attached to the acetabulum, above and behind, two or three lines external 
 to the cotyloid ligament; but in front it is attached to the outer margin of 
 this ligament, and opposite to the notch, where the margin of this cavity is 
 deficient, it is connected to the transverse ligament, and by a few fibres to 
 the edge of the obturator foramen. Its lower circumference surrounds the neck 
 of the femur, being attached, in front, to the spiral or anterior intertrochanteric 
 line; above, to the base of the neck; behind, to the neck of the bone, about half 
 
THE HIP- JOINT 
 
 327 
 
 an inch above tl;ie posterior intertrochanteric Hne. From this insertion the fibres 
 are reflected upward over the neck of the femur, forming a sort of tubular sheath, 
 the cervical reflection, which blends with the periosteum and can be traced as far 
 as the articular cartilage. On the surface of the neck of the femur some of these 
 reflected fibres are raised into longitudinal folds, termed retinacula. It is much 
 thicker at the upper and forepart of the joint, where the greatest amount of 
 
 •■?#// 
 
 I i_ I U M 
 
 Fig. 235. — Right hip-joint, from behind. (The joint capsule, except for the strengthening ligaments, has 
 
 been removed.) (Spalteholz.) 
 
 resistance is required, than below and internally, where it is thin, loose, and 
 longer than in any other part. It consists of two sets of fibres, circular and lon- 
 gitudinal. The circular fibres, zona orbicularis (Fig. 237) , are most abundant at the 
 lower and back part of the capsule, and form a sling or collar around the neck of 
 the femur. Anteriorly they blend with the deep surface of the ilio-femoral liga- 
 ment, and through its medium reach the anterior inferior spine of the ilium. The 
 longitudinal fibres are greatest in amount at the upper and front part of the cap- 
 sule, where they form distinct Imnds or accessory ligaments, of which the most 
 important is the ilio-femoral. Other accessory bands are known as the pubo- 
 
328 
 
 THE ARTICULATIONS OB JOINTS 
 
 femoral or pubo-capsular ligament (ligamentum pubocapsulare) , passing from the 
 outer portion of the horizontal pubic ramus, the iho-pectineal eminence, the 
 obturator crest and the obturator membrane, to the front of the capsule; and 
 ischio-capsular ligament or ligament of Bertin (ligamentum ischiocapsulare) , 
 passing from the ischium, just below the acetabulum, to blend with the circular 
 fibres at the lower part of the joint. The external surface is rough, covered by 
 numerous muscles, and separated in front from the Psoas and Iliacus muscles by 
 a synovial bursa, which not infrequently communicates, by a circular aperture, 
 with the cavity of the joint. It differs from the capsular ligament of the shoulder 
 in being much less loose and lax, and in not being perforated for the passage of 
 a tendon. 
 
 ANTERIOR 
 
 INFERIOR 
 
 SPINE OF ILIUM 
 
 ,'«..ii,lj,|(i.,.,, 
 
 SPINE OF 
 ISCHIUM 
 
 TRANSVERSE 
 LIGAMENT OF 
 ACETABULUM 
 
 TUBEROSITY 
 OF ISCHIUM 
 
 Fig. 236.- 
 
 -Right hip-joint from the medial side. (The bottom of the acetabulum has been chiselled away 
 suflBciently to make the head of the femur visible.) (Spalteholz.) 
 
 The Ilio-femoral or Y-ligament or Ligament of Bigelow (ligamentum ilio- 
 femorale) (Figs. 234, 235, 237, and 238) is an accessory band of fibres extending 
 obliquely across the front of the joint; it is intimately connected with the cap- 
 sular ligament, and serves to strengthen it in this situation. It is attached, 
 above, to the lower part of the anterior inferior spine of the ilium and the 
 adjacent rim of the acetabulum; and, diverging below, forms two bands, of 
 which one passes downward to be inserted into the lower part of the anterior 
 intertrochanteric line; the other passes downward and outward to be inserted 
 into the upper part of the same line and the adjacent part of the neck of the 
 femur. Between the two bands is a thinner part of the capsule. Sometimes 
 there is no division, but the ligament spreads out into a flat, triangular band, 
 which is attached below into the whole length of the anterior intertrochanteric 
 line. This ligament is frequently called the Y-shaped ligament of Bigelow; and 
 
THE HIP -JOINT 
 
 329 
 
 the outer or upper of the two bands is sometimes described as a separate liga- 
 ment, under the name of the ilio -trochanteric ligament. 
 
 The Ligamentum Teres, or the Interarticular Ligament (ligamentum teres femoris) 
 (Figs. 236, 237, and 239) is a triangular band implanted by its apex into the 
 depression a little behind and below the centre of the head of the femur, and by 
 its broad base into the margins of the cotyloid notch, becoming blended with the 
 transverse ligament. It is formed of connective tissue, surrounded by a tubular 
 sheath of synovial membrane. Sometimes only the synovial fold exists. Very 
 rarely it is absent. The ligament is made tense when the hip is semiflexed, 
 
 ILIOLUMBAR LIGAMENT 
 
 ANTERIOR SACRO- 
 ILIAC LIGAMENT 
 
 CAPSULAR LIGAMENT, 
 
 FIBROUS PORTION 
 
 CAPSULAR LIGAMENT, 
 
 SYNOVIAL PORTION 
 
 ILIOFEMORAL 
 LIGAMENT 
 
 ZONA 
 ORBICULARIS 
 GREAT 
 TROCHANTER 
 
 /COOPER'S LIGAMtNT 
 / SPINE OF PUBIS 
 
 PUBOFEMORAL 
 LIGAMENT 
 
 OBTURATOR LIGAMENT 
 ZONA ORBICULARIS 
 SMALL SYNOVIAL MEMBRANE COVERING 
 
 TROCHANTER NECK OF FEMUR 
 
 Fig. 237. — The right hip-joint, seen from before. (Toldt.) 
 
 and the limb adducted and rotated outward; it is, on the other hand, relaxed 
 when the limb is abducted. It has, however, but little influence as a ligament, 
 though it may to a certain extent limit movement, and would appear to be 
 merely a "vestigial and practically useless ligament."^ It is probably a modifi- 
 cation of the folds which in other joints fringe the margins of reflection of synovial 
 membranes. 
 
 The Cotyloid Ligament (lahrum glenoidale) (Fig. 239) is a fibro-cartilaginous rim 
 attached to the margin of the acetabulum, the cavity of which it deepens; at the 
 
 * J. Bland Sutton. Ligaments: Their Nature and Morphology. 
 
330 
 
 THE ABTICULATIOS OB JOINTS 
 
 same time it protects the edges of the bone and fills up the inequalities on its sur- 
 face. It bridges over the notch as the transverse ligament of the acetabulum, and 
 
 thus forms a complete circle, which closely sur- 
 rounds the head of the femur, and assists in 
 holding it in its place, acting as a sort of valve. 
 It is prismoid on section, its base being attached 
 to the margin of the acetabulum and its op- 
 posite edge being free and sharp; whilst its 
 two surfaces are invested by synovial mem- 
 brane, the external one being in contact with 
 the capsular ligament, the internal one being 
 inclined inward, so as to narrow the acetab- 
 ulum and embrace the cartilaginous surface 
 of the head of the femur. It is much thicker 
 above and behind than below and in front, 
 and consists of close, compact fibres, which 
 arise from different points of the circumference 
 of the acetabulum and interlace with each other 
 at very acute angles. 
 
 The transverse ligament of the acetabulum 
 (ligamentum transversum acetabuli) (Figs. 230 
 and 239) is in reality a portion of the cotyloid 
 ligament, though differing from it in having 
 no cartilage-cells amongst its fibres. It con- 
 sists of strong, flattened fibres, which cross the 
 notch at the lower part of the acetabulum and 
 convert it into a foramen. Thus an interval 
 is left beneath the ligament for the passage of 
 nutrient vessels to the joint. 
 Synovial Membrane (Figs. 237 and 239). — The synovial membrane is very 
 extensive. Commencing at the margin of the cartilaginous surface of the head 
 of the femur, it covers all that portion of the neck which is contained within the 
 joint; from the neck it is reflected on the internal surface of the capsular liga- 
 ment, covers both surfaces of the cotyloid ligament and the mass of fat contained 
 in the depression at the bottom of the acetabulum, and is prolonged in the form 
 of a tubular sheath around the ligamentum teres, as far as the head of the femur. 
 It sometimes communicates through a hole in the capsular ligament between 
 the inner band of the Y-shaped ligament and the pubo-femoral ligament with 
 a bursa situated on the under surface of the Ilio-psoas muscle. 
 
 The muscles in relation with the joint (Fig. 240) are, in front, the Psoas and 
 Iliacus, separated from the capsular ligament by a synovial bursa; above, the 
 reflected head of the Rectus and Gluteus minimus, the latter being closely adherent 
 to the capsule; internally, the Obturator externus and Fectineus; behind, the Pyri- 
 formis, Gemellus superior. Obturator internus, Gemellus inferior. Obturator exter- 
 nus, and Quadratus femoris. 
 
 The arteries supplying the joint are derived from the obturator, sciatic, internal 
 circumflex, and gluteal. 
 
 The nerves are articular branches from the sacral plexus, great sciatic, obtu- 
 rator, accessory obturator, and a filament from the branch of the anterior crural 
 supplying the rectus. 
 
 Bursse. — Numerous bursse exist in the neighborhood of the hip-joint. Some 
 anatomists have counted twenty-one (Synnestredt). The chief ones are : 1. The 
 ilio-pectineal bursa (bursa iliopectinea) (Fig. 240), between the ilio-psoas tendon 
 and the capsule of the joint. It often communicates with the hip-joint. 2. The 
 
 Fig. 238. — Hip-joint, showing the ilio-femoral 
 
 ligament. (After Bigelow.) 
 
THE HIP -JOINT 
 
 331 
 
 subtendinous iliac bursa (bursa iliaca subtendinea) , between the tendon of the psoas 
 and iUacus and the lesser trochanter. 3. The ischio -gluteal bursa (bursa ischiadica 
 m. glutei maximi) , between the Gluteus maximus muscle and the tuberosity of the 
 ischium (not constant). 4. The bursa of the great trochanter (bursa trochanterica m. 
 glutoei maximi), between the great trochanter and the Gluteus maximus muscle 
 near the muscular insertion. 5. Two or three gluteo-femcral bursae (bursa; 
 glutaojemorales) below. 6. The obturator bursa (bursa m. obturatorii interni), 
 between the margin of the great sacro-sciatic notch and the tendon of the 
 Obturator internus muscle. 7. The subcutaneous trochanteric bursa (bursa tro- 
 
 GREAT. 
 
 TROCHANTER / 
 
 EPIPHVSEAL 
 JUNCTION 
 
 EPIPHYSEAL 
 JUNCTION 
 
 LIGAMENTUM 
 TERES 
 
 TRANSVERSE 
 LIGAMENT OF 
 ACETABULUM 
 
 
 Fig. 239. — Right hip-joint. Frontal section. Posterior half, viewed from in front. (The joint surfaces 
 have been .somewhat pulled apart.) (Spalteholz.) 
 
 chanterica subcufanea), between the cutaneous surface and the great trochanter. 
 Besides these there is a bursa between the great trochanter and the anterior part 
 of the Gluteus medius — between the great trochanter and the posterior part of 
 the Gluteus medius — between the great trochanter and the Gluteus minimus — 
 beneath the Pyriformis muscle — between the small trochanter and the Quad- 
 ratus femoris muscle, and there are bursae beneath the Biceps femoris muscle. 
 
 Actions. — The movements of the hip are very extensive, and consist of flexion, 
 extension, adduction, abduction, circumduction, and rotation. 
 
332 
 
 THE ARTICULATIONS OB JOINTS 
 
 The hip-joint presents a very striking contrast to the shoulder-joint in the 
 much more complete mechanical arrangements for its security and for the limita- 
 tion of its movements. In the shoulder, as we have seen, the head of the humerus 
 is not adapted at all in size to the glenoid cavity, and is hardly restrained in any 
 of its ordinary movements by the capsular ligament. In the hip-joint, on the 
 contrary, the head of the femur is closely fitted to the acetabulum for a distance 
 extending over nearly half a sphere, and at the margin of the bony cup it is still 
 more closely embraced by the cotyloid ligament, so that the head of the femur 
 is held in its place by that ligament even when the fibres of the capsule have been 
 quite divided (Humphry). The anterior portion of the capsule, described as the 
 ilio-femoral ligament, is the strongest of all the ligaments in the body, and is put 
 on the stretch by any attempt to extend the femur beyond a straight line with the 
 trunk. That is to say, this ligament is the chief agent in maintaining the erect 
 position without muscular fatigue; for a vertical line passing through the centre 
 of gravity of the trunk falls behind the centres of rotation in the hip-joints, and 
 
 Isch. capn 
 ligament 
 
 RECT. FEM. 
 
 Ileo-fem. ligament 
 
 Pub. fern, ligament 
 
 Fig. 240. — Relation of muscles to hip-joint. (Henle.) 
 
 therefore the pelvis tends to fall backward, but is prevented by the tension of 
 the ilio-femoral and capsular ligaments. The security of the joint may be also 
 provided for by the two bones being directly united through the ligamentum 
 teres; but it is doubtful whether this so-called ligament can have much influence 
 upon the mechanism of the joint. Flexion of the hip-joint is arrested by the soft 
 parts of the thigh and abdomen being brought into contact when the leg is flexed 
 on the thigh ; and by the action of the hamstring muscles when the leg is extended ;* 
 extension, by the tension of the ilio-femoral ligament and front of the capsule; 
 adduction, by the thighs coming into contact; adduction, with flexion by the 
 outer band of the ilio-femoral ligament, the outer part of the capsular ligament; 
 
 ' The hip-joint cannot be completely flexed, in most persons, without at the same time flexing the knee, on 
 account of the shortness of the hamstring muscles. — Cleland, Jour, of Anat. and Phys., No. 1, Old Series, p. 87. 
 
THE HIP -JOINT . 333 
 
 abduction, by the inner band of the iho-femoral Hgament and the pubo-femoral 
 band; rotation outward, by the outer band of the iUo-femoral Hgament; and 
 rotation inward, by the ischio-capsular Hgament and the hinder part of the cap- 
 sule. The muscles which f.ex the femur on the pelvis are the Psoas, Iliacus, 
 Rectus, Sartorius, Pectineus, Adductor longus and brevis, and the anterior fibres 
 of the Gluteus medius and minimus. Extension is mainly performed by the 
 Gluteus maximus, assisted by the hamstring muscles. The thigh is adducted by 
 the Adductor magnus, longus, and brevis, the Pectineus, the Gracilis, and lower 
 part of the Gluteus maximus, and abducted by the Gluteus medius and minimus 
 and upper part of the Gluteus maximus. The muscles which rotate the thigh 
 inward are the anterior fibres of the Gluteus medius, the Gluteus minimus, and the 
 Tensor fasciae f emoris ; while those which rotate it outward are the posterior fibres 
 of the Gluteus medius, the Pyriformis, Obturator externus and internus, Gemellus 
 superior and inferior, Quadratus femoris, Iliacus, Gluteus maximus, the three 
 Adductors, the Pectineus, and the Sartorius. 
 
 Surface Form, — A line drawn from the anterior superior spinous process of the ilium to 
 the most prominent part of the tuberosity of the ischium (Nelaton's line) runs through the 
 centre of the acetabulum, and would, therefore, indicate the level of the hip-joint; or, in other 
 words, the upper border of the great trochanter, which lies on Nelaton's line, is on a level with 
 the centre of the hip-joint. 
 
 Surgical Anatomy. — Inflammation of bursw about the hip-joint gives rise to confusing 
 symptoms. Inflammation of one of the bursse over the great trochanter is not uncommon. 
 Great pain is produced if any movement of the gluteal muscles is permitted. 
 
 Enlargement of the bursa over the ischial tuberosity was long called weaver's button. Enlarge- 
 ment of the bursa beneath the ilio-psoas may produce a large swelling. Bursal inflammation is 
 not unusually mistaken for hip-joint disease 
 
 In dislocation of the hip "the head of the thigh bone may rest at any point around its socket" 
 (Bryant); but whatever position the head ultimately assumes, the primary displacement is 
 generally downward and inward, the capsule giving way at its weakest — that is, its lower and 
 inner — part. The situation that the head of the bone subsequently assumes is determined 
 by the degree of flexion or extension, and of outward or inward rotation of the thigh at the 
 moment of luxation, influenced, no doubt, by the ilio-femoral ligament, which is not easily 
 ruptured. When, for instance, the head is forced backward, this ligament forms a fixed axis, 
 round which the head of the bone rotates, and the head is thus driven on to the dorsum of the ilium. 
 The ilio-femoral ligament also influences the position of the thigh in the various dislocations: 
 in the dislocations backward it is tense, and produces inversion of the limb; in the dislocation 
 on to the pubes it is relaxed, and therefore allows the external rotators to evert the thigh; while 
 in the thyroid dislocation it is tense and produces flexion. The muscles inserted into the upper 
 part of the femur, with the exception of the Obturator internus, have very little direct influence 
 in determining the position of the bone. But Bigelow has endeavored to show that the Obtu- 
 rator internus is the principal agent in determining whether in the backward dislocations the 
 head of the bone shall be ultimately lodged on the dorsum of the ilium or in or near the sciatic 
 notch. In both dislocations the head passes, in the first instance, in the same direction; but, 
 as Bigelow asserts, in the displacement on to the dorsum, the head of the bone travels up behind 
 the acetabulum, in front of the muscle; while in the dislocation into the sciatic notch, the head 
 passes behind the muscle, and is therefore prevented from reaching the dorsum, in consequence 
 of the tendon of the muscle arching over the neck of the bone, and so remains in the neighbor- 
 hood of the sciatic notch. Bigelow, therefore, distinguishes these two forms of dislocation by 
 describing them as dislocations backward, "above and below," the Obturator internus. 
 
 The ilio-femoral ligament is rarely torn in dislocations of the hip, and this fact is taken 
 advantage of by the surgeon in reducing these dislocations by manipulation. It is made to act 
 as a fulcrum to a lever, of which the long arm is the shaft of the femur, and the short arm the 
 neck of the bone. 
 
 The hip-joint is rarely the seat of acute synovitis from injury, on account of its deep position 
 and its thick covering of soft parts. Acute inflammation may, and does, frequently occur as 
 the result of constitutional conditions, as rheumatism, pytemia, etc. When, in these cases, 
 effusion takes place, and the joint becomes distended with fluid, the swelling is not very easy 
 to detect on account of the thickness of the capsule and the depth of the articulation. It is 
 principally to be found on the front of the joint, just internal to the ilio-femoral ligament; or 
 behind, at the lower and back part. In these two places the capsule is thinner than elsewhere. 
 Disease of the hip-joint is much more frequently of a chronic character and is usually of tuber- 
 culous origin. It begins either in the bones or in the synovial membrane, more frequently in the 
 
334 • '^HE ARTICULATIONS OR JOINTS 
 
 former, and probably, in most cases, in the growing, highly vascular tissue in the neighborhood 
 of the epiphysial cartilage. In this respect it differs very materially from tuberculous arthritis 
 of the knee, where the disease often commences in the synovial membrane. The reasons why 
 hip-disease so frequently begins near the epiphysial cartilage are twofold: first, this part being 
 the centre of rapid growth, its nutrition is unstable and inflammation is easily awakened; 
 and, secondly, great strain is thrown upon it, from the frequency of falls and blows upon the hip, 
 which causes crushing of the epiphysial cartilage or the cancellous tissue in its neighborhood, 
 with the results likely to follow such an injury. In addition to these, the depth of the joint 
 protects it from the causes of synovitis. 
 
 In chronic hip-disease the affected limb assumes an altered position, the cause of which it 
 is important to understand. In the early stage of a typical case the limb is flexed, abducted, 
 and rotated outward. In this position all the ligaments of the joint are relaxed: the front of 
 the capsule by flexion; the outer band of the ilio-femoral ligament by abduction; and the inner 
 band of this ligament and the back of the capsule by rotation outward. It is, therefore, the 
 position of the greatest ease. The condition is not quite obvious at first upon examining a 
 patient. If the patient is laid in the supine position, the affected limb will be found to be 
 extended and parallel with the other. But it will be found that the pelvis is tilted downward 
 on the diseased side and the limb apparently longer than its fellow, and that the lumbar spine 
 is arched forward (lordosis). If now the thigh is abducted and flexed, the tilting down- 
 ward and the arching forward of the pelvis disappears. The condition is thus explained. A 
 limb which is flexed and abducted is obviously useless for progression, and, to overcome the 
 difficulty, the patient depresses the affected side of his pelvis in order to produce parallelism 
 of his limbs, arid at the same time rotates his pelvis on its transverse horizontal axis, so as to 
 direct the limb downward instead of forward. In the latter stages of the disease the limb 
 becomes flexed, adducted, and inverted. The position probably depends upon muscular 
 action, at all events as regards the adduction. The Adductor muscles are supplied by the 
 obturator nerve, which also largely supplies the joint. These muscles are therefore thrown into 
 reflex action by the irritation of the peripheral terminations of this nerve in the inflamed artic- 
 ulation. Osteo-arthritis is not uncommon in the hip-joint, and it is said to be more common in 
 the male than in the female, in whom the knee-joint is more frequently affected. It is a disease 
 of middle age or more advanced period of life. 
 
 Congenital dislocation is more commonly met with in the hip-joint than in any other articula- 
 tion. The displacement usually takes place on to the dorsum ilii. It gives rise to extreme 
 lordosis, and a waddling gait is noticed as soon as the child commences to walk. 
 
 Excision of the hip may be required for disease or for injury, especially for gunshot wound. 
 It may be performed either by an anterior or an external incision. The former one entails 
 less interference with important structures, especially muscles, than the posterior one, but permits 
 of less efficient drainage. In these days, however, when the surgeon aims at securing healing 
 of his wound without suppuration, this second advantage is not of so much importance. In 
 the operation in front the surgeon makes an incision three or four inches in length, starting 
 immediately below and external to the anterior superior spinous process of the ilium, down- 
 ward and inward between the Sartorius and Tensor fascite femoris, to the neck of the bone, 
 dividing the capsule at its upper part. A narrow-bladed saw now divides the neck of the femur, 
 and the head of the bone is extracted with sequestrum forceps. All diseased tissue is carefully 
 removed with a sharp spoon or scissors, and the cavity thoroughly flushed with a hot aseptic 
 fluid. 
 
 The external method consists in making an incision three or four inches long, commencing 
 midway between the top of the great trochanter and the anterior superior spine, and ending 
 over the shaft, just below the trochanter. The muscles are detached from the great trochanter, 
 and the capsule opened freely. The head and neck are freed from the soft parts and the bone 
 sawn through just below the top of the trochanter with a narrow saw. The head of the bone is 
 then levered out of the acetabulum. In both operations, if the acetabulum is eroded, it must be 
 freely gouged. 
 
 II. The Knee-joint (Articulatio Genu). 
 
 The knee-joint was formerly described as a ginglymus or hinge-joint, but is 
 really of a much more complicated character. It must be regarded as consist- 
 ing of three articulations in one : one between each condyle of the femur and the 
 corresponding tuberosity of the tibia, which are condyloid joints, and one between 
 the patella and the femur, which is partly arthrodial, but not completely so, since 
 the articular surfaces are not mutually adapted to each other, so that the movement 
 is not a simple gliding one. This view of the construction of the knee-joint receives 
 confirmation from the study of the articulation in some of the lower mammals, 
 
THE KNEE-JOINT 
 
 335 
 
 where three synovial membranes are sometimes found, corresponding to these 
 three subdivisions, either entirely distinct or only connected together by small 
 communications. This view is further rendered probable by the existence 
 of the two crucial ligaments within the joint, which must be regarded as the 
 external and internal lateral ligaments of the inner and outer joints respectively. 
 The existence of the ligamentum mucosum would further indicate a. tendency 
 to separation of the synovial cavity into two minor sacs, one corresponding to 
 each joint. 
 
 The bones entering into the formation of the knee-joint are the condyles of the 
 femur above, the head of the tibia below, and the patella in front. The bones are 
 connected together by ligaments, some of which are placed on the exterior of the 
 joint, while others occupy its interior. 
 
 External Ligaments. 
 
 Anterior, or Ligamentum Patellae. 
 
 Posterior. 
 
 Internal Lateral. 
 
 Two External Lateral. (The long 
 external ligament is constant. The 
 short external ligament is not always 
 present.) 
 
 Capsular. 
 
 Interior Ligaments. 
 
 Anterior, or External Crucial. 
 
 Posterior, or Internal Crucial. 
 
 Two Semilunar Fibro-cartilages. 
 
 Transverse. 
 
 Coronary. 
 
 T . , f Processes of 
 
 Ligamentum mucosum. o • i 
 T .^ . 1 • ^ fevnovial 
 
 Ligamenta alaria. tvt u 
 
 '^ Membrane. 
 
 The Anterior Ligament, or Ligamentum Patellae (Figs. 241, 245, and 246), is the 
 central portion of the common tendon of the Extensor muscles of the thigh, which 
 is continued from the patella to the tubercle of the tibia, supplying the place of an 
 anterior ligament. It is a strong, flat, ligamentous band about three inches in 
 length, attached, above, to the apex of the patella and the rough depression on its 
 posterior surface ; below, to the lower part of the tubercle of the tibia, its superficial 
 fibres being continuous over the front of the patella with those of the tendon of the 
 Quadriceps extensor. The lateral portions of the tendon of the Extensor muscles 
 pass down on either side of the patella, and are attached to the borders of this bone. 
 The deep fascia and the quadriceps extensor muscle are inserted into the patella. 
 Prolongations from the fascia and from the fibrous expansion of the muscle pass 
 from the edges of the patella and from the ligament of the patella to the upper 
 extremity of the tibia on each side of the tubercle ; externally, and to the head of 
 the fibula. They are termed lateral patellar ligaments (retinaculum patelloB mediate 
 and retinaculum, 'patelloe laterale), and merge into the capsule. The posterior 
 surface of the ligamentum patellae is separated from the front of the capsular 
 ligament by a mass of fat. 
 
 The Posterior Ligament (ligamentum popliteum ohliquum) (Fig. 241) is a broad, 
 flat, fibrous band, formed of fasciculi separated from one another by apertures 
 for the passage of vessels and nerves. It is attached, above, to the upper margin 
 of the intercondyloid notch of the femur, and, below, to the posterior margin of 
 the head of the tibia. Superficial to the main part of the ligament and forming 
 a portion of it is a strong fasciculus derived from the tendon of the Semi- 
 membranosus, and passing from the back part of the inner tuberosity of the tibia 
 obliquely upward and outward to the back part of the outer condyle of the femur. 
 This expansion from the tendon of the Semimembranosus muscle is called the 
 posterior ligament of Winslow (ligamentum posticum Winslowii), and it merges 
 with the posterior ligament. The posterior ligament forms part of the floor of 
 the popliteal space, and the popliteal artery rests upon it. 
 
 The Internal Lateral Ligament (ligamentum collaterale tihiale) (Figs. 241 and 242) 
 is a broad, flat, membranous band, thicker behind than in front, and situated 
 
336 
 
 THE ARTICULATIONS OB JOINTS 
 
 nearer to the back than the front of the joint. It is attached, above, to the inner 
 tuberosity of the femur; below, to the inner tuberosity and inner surface of the 
 shaft of the tibia to the extent of about two inches. It is crossed, at its lower 
 part, by the tendons of the Sartorius, GraciUs, and Semitendinosus muscles, a 
 synovial bursa being interposed. Its deep surface covers the anterior portion of 
 the tendon of the Semimembranosus, with which it is connected by a few fibres, 
 the synovial membrane of the joint, and the inferior internal articular vessels and 
 nerve; it is intimately adherent to the internal semilunar fibro-cartilage. 
 
 Fig. 241. — Right knee-joint. Anterior view. 
 
 Fig. 242. — Right knee-joint. Posterior view. 
 
 The External Lateral or Long External Lateral Ligament ( Ugamentum collaterale 
 fbulare) (Figs. 242 and 246) is a strong, rounded, fibrous cord situated nearer 
 to the back than the front of the joint. It is attached, above, to the back part 
 of the outer tuberosity of the femur; below, to the outer part of the head of the 
 fibula. Its outer surface is covered by the tendon of the Biceps, which divides at 
 its insertion into two parts, separated by the ligament. The ligament has, pass- 
 ing beneath it, the tendon of the Popliteus muscle and the inferior external 
 articular vessels and nerve. 
 
 The Short External Lateral Ligament {Ugamentum laterale externum breve sen 
 posticum) (Fig. 242) is not a constant structure. It is an accessory bundle of 
 fibres placed behind and parallel with the preceding, attached, above, to the 
 lower and back part of the outer tuberosity of the femur; below, to the summit 
 of the styloid process of the fibula. This ligament is intimately connected with 
 the capsular ligament, and has, passing beneath it, the tendon of the Popliteus 
 muscle and the inferior external articular vessels and nerve. 
 
THE KNEE-JOINT 
 
 337 
 
 Femur 
 
 The Capsular Ligament (capsula articularis) (Fig. 241) consists of an exceedingly 
 thin but strong, fibrous membrane which fills in the intervals left between the 
 stronger bands above described, and is inseparably connected with them. In front 
 it blends with and forms part of the lateral 
 patellar ligaments and fills in the interval 
 between the anterior and lateral ligaments of 
 the joints, with which latter structures it is 
 closely connected. It is deficient above the 
 joint and beneath the tendon of the quadri- 
 ceps extensor. Behind, it is formed chiefly 
 of vertical fibres, which arise above from 
 the condyles and intercondyloid notch of 
 the femur, and is connected below with the 
 back part of the head of the tibia, being 
 closely united with the origins of the Gas- 
 trocnemius, Plantaris, and Popliteus muscles. 
 It passes in front of, but is inseparably con- 
 nected with, the posterior ligament. 
 
 The Crucial Ligaments (ligamenta cruciata 
 genu) (Figs. 171, 243, and 244) are two inter- 
 osseous ligaments of considerable strength 
 situated in the interior of the joint, nearer its 
 posterior than its anterior part. They are 
 called crucial because they cross each other 
 somewhat like the lines of the letter X; and 
 have received the names anterior crucial and 
 posterior crucial, from the position of their at- 
 tachment to the tibia. 
 
 The anterior or external crucial ligament 
 {ligamentum cruciatum anterius) (Fig. 243) is 
 attached to the depression in front of the 
 spine of the tibia, being blended with the anterior extremity of the external 
 semilunar fibro-cartilage, and, passing obliquely upward, backward, and out- 
 ward, is inserted into the iimer and back part of the outer condyle of the femur. 
 The posterior or internal crucial ligament (ligamentum cruciatum posterius) 
 is stronger, but shorter and less oblique in its direction than the anterior. It 
 
 is attached to the back part 
 of the depression behind the 
 spine of the tibia, to the pop' 
 liteal notch, and to the poste- 
 rior extremity of the external 
 semilunar fibro-cartilage; and 
 passes upward, forward, and 
 inward, to be inserted into 
 the outer and forepart of the 
 inner condyle of the femur. 
 It is in relation, in front, with 
 the anterior crucial ligament; 
 behind, with the capsular liga- 
 ment. 
 
 The Semilunar Fibro-cartil- 
 a,ges(menisic) (Figs. 171,243, 
 244, 245, and 246) are two crescentic lamellae which serve to deepen the surface 
 of the head of the tibia, for articulation with the condyles of the femur. The 
 
 22 
 
 Fig. 243.- 
 
 Right knee-joint. Showing internal 
 ligaments. 
 
 Fig. 244. 
 
 -Head of tibia, with semilunar cartilages, etc. 
 from above. Right side. 
 
 Seen 
 
338 
 
 THE ARTICULATIONS OB JOINTS 
 
 circumference of each cartilage is thick, convex, and attached to the inside of the 
 capsule of the knee ; the inner border is thin, concave, and free. Their uy^er 
 surfaces are concave, and in relation with the condyles of the femur; their lower 
 surfaces are flat, and rest upon the head of the tibia. Each cartilage covers 
 nearly the outer two-thirds of the corresponding articular surface of the tibia, 
 leaving the inner third uncovered ; both surfaces are smooth and invested by 
 svnovial membrane. 
 
 ARTICULAR 
 CAVITY 
 
 LIGAMENTA 
 ALARIA 
 
 SE 
 FIBRO-CA 
 
 LIGAMENTUM 
 PATELL/E 
 
 DEEP INFRA- 
 PATELLAR BURSA 
 
 EPIPHYSEAL 
 JUNCTION 
 
 Fig. 245. — Right knee-joint. Sagittal section through the external condyle of the femur. Medial half of 
 section, from the lateral side. (The knee is slightly flexed; the joint surfaces have been pulled a little aparv.) 
 (Spalteholz.) 
 
 The internal semilunar fibro-caxtilage {meniscus medialis) is nearly semicircular 
 in form, a little elongated from before backward, and broader behind than in front; 
 its anterior extremity, thin and pointed, is attached to a depression on the anterior 
 margin of the head of the tibia, in front of the anterior crucial ligament; its 
 'posterior extremity is attached to the depression behind the spine, between the 
 attachments of the external semilunar fibro-cartilage and the posterior crucial 
 ligaments. 
 
THE KNEE-JOINT 
 
 339 
 
 The external semilunar fibro-cartilage {meniscus lateralis) forms nearly an 
 entire circle, covering a larger portion of the articular surface than the internal 
 one. It is grooved on its outer side for the tendon of the Popliteus muscle. Its 
 extremities, at their insertion, are interposed between the two extremities of the 
 internal semilunar fibro-cartilage ; the anterior extremity being attached in front 
 of the spine of the tibia to the outer side of, and behind, the anterior crucial 
 
 TENDON OF QUAD- 
 RICEPS EXTENSOR 
 FEMORIS 
 
 SUPRAPATELLAR 
 BURSA 
 
 ARTICULAR 
 CAVITY 
 
 LONG EXTERNAL 
 
 LATERAL 
 
 LIGAMENT 
 
 TENDON OF 
 
 POPLITEUS 
 
 MUSCLE 
 
 popliteal 
 bursa' 
 
 HEAD OF li 
 FIBULA 
 
 PREPATELLAR 
 BURSA 
 
 EXTERNAL SEMI- 
 LUNAR FIBRO- 
 CARTILAGE 
 
 LIGAMENTUM 
 PATELUE 
 
 DEEP INFRAPATEL- 
 LAR BURSA 
 
 TUBEROSITIES 
 OF TIBIA 
 
 Fig. 246. 
 
 -Right knee-joint, from the lateral surface. (The joint cavity and several bursse have been injecteu 
 
 with a stiffening medium and then dissected out.) (Spalteholz.) 
 
 ligament, with which it blends; the posterior extremity being attached behind the 
 spine of the tibia, in front of the posterior extremity of the internal semilunar 
 fibro-cartilage. Just before its insertion posteriorly it gives off a strong fasciculus, 
 the ligament of Wrisberg, which passes obliquely upward and outward, to be 
 inserted into the inner condyle of the femur, close to the attachment of the poste- 
 rior crucial ligament. Occasionally a small fasciculus is given off which passes 
 forward to be inserted into the back part of the anterior crucial ligament. The 
 
340 THE ARTICULATIONS OR JOINTS 
 
 external semilunar fibro-cartilage gives off from its anterior convex margin a 
 fasciculus which forms the transverse ligament. 
 
 The Transverse Ligament (ligamentum transversum genu) (Fig. 244) is a band of 
 fibres which passes transversely from the anterior convex margin of the external 
 semilunar fibro-cartilage to the anterior convex margin of the internal semilunar 
 fibro-cartilage; its thickness varies considerably in different subjects, and it is 
 sometimes absent altogether. 
 
 The Coronary Ligaments (ligamenfa coronaria) are merely portions of the cap- 
 sular ligament, which connect the circumference of each of the semilunar fibro- 
 cartilages with the margin of the head of the tibia. 
 
 Synovial Membrane (Figs. 245 and 246) . — The synovial membrane encloses the 
 articular cavity (cavum articulare) of the knee-joint. It is the largest and most 
 extensive synovial membrane in the body. Commencing above the upper border 
 of the patella, it forms a short cul-de-sac beneath the Quadriceps extensor tendon of 
 the thigh, on the lower part of the front of the shaft of the femur; this connnuni- 
 cates, by an orifice of variable size, with a synovial bursa interposed between the 
 tendon "and the front of the femur (bursa suprapaiellaris) . On each side of the 
 patella the synovial membrane extends beneath the aponeurosis of the Vasti 
 muscles, and more especially beneath that of the Vastus internus. Below the 
 patella it is separated from the anterior ligament by the anterior part of the 
 capsule and a considerable quantity of adipose tissue, known as the infrapatellar 
 pad (Fig. 245) . In this situation the synovial membrane sends off a triangular 
 prolongation, containing a few ligamentous fibres, which extends from the ante- 
 rior part of the joint below the patella to the front of the intercondyloid notch. 
 This fold has been termed the ligamentum mucosum (plica synovialis patellar is). 
 It also sends off two fringe-like folds, called the ligamenta alaria (plicre alares) 
 (Fig. 245), which extend from the sides of the ligamentum mucosum, upward 
 and laterally between the patella and femur. On either side of the joint it passes 
 downward from the femur, lining the capsule to its point of attachment to the 
 semilunar cartilages ; it may then be traced over the upper surfaces of these car- 
 tilages to their free borders, and from thence along their under surfaces to the 
 tibia. At the back part of the external one it forms a cul-de-sac between the 
 groove on its surface and the tendon of the Popliteus; it surrounds the crucial 
 ligaments and lines the inner surface of the ligaments which enclose the joint. 
 The pouch of synovial membrane between the Extensor tendon and front of the 
 femur is supported, during the movements of the knee, by a small muscle, the 
 Subcrureus, which is inserted into the upper part of the capsular ligament. 
 
 The folds of synovial membrane and the fatty processes contained in them act, 
 as it seems, mainly in padding to fill up interspaces and obviate concussions. 
 Sometimes the bursa beneath the Quadriceps extensor is completely shut off from 
 the rest of the synovial cavity, thus forming a closed sac between the Quadriceps 
 and the lower part of the front of the femur; sometimes it communicates with the 
 synovial cavity by a minute aperture; usually the two cavities are incompletely 
 separated by a synovial fold. 
 
 Bursae.^-The bursa? about the knee-joint are the following: In front there 
 are jour bursse: one is interposed between the patella and the skin. It is 
 known as the prepatellar bursa (bursa prcepatellaris suhcutanea) ; another, of 
 small size, between the upper part of the tuberosity of the tibia and the 
 ligamentum patellae is called the deep infrapatellar bursa (bursa injrapateUaris 
 profunda); and a third between the lower part of the tuberosity of the tibia 
 and the skin, the subcutaneous tibial bursa (bursa subcutanea tuberositaUs tibiw). 
 A fourth bursa exists in front, the suprapatellar bursa (bursa suprapateUaris) . 
 It lies between the anterior surface of the lower end of the femur and the 
 posterior surface of the quadriceps feraoris. Spalteholz says that the supra- 
 
THE KNEE-JOINT 34I 
 
 patellar bursa is closely connected with the quadriceps tendon and is usually 
 incompletely shut off from the cavity of the joint.^ Occasionally there is a 
 bursa between the expansion of the fascia lata and the Quadriceps and the 
 patella (bursa prcepatellaris subfascialis) , and sometimes one between the tendon 
 of the quadriceps and the anterior surface of the patella (bursa prcBpatellaris 
 siibtendinea) . On the outer side there are Jour bursse: (1) one beneath the outer 
 head of the Gastrocnemius (which sometimes communicates with the joint); 
 (2) one above the external lateral ligament between it and the tendon of the 
 Biceps; (3) one beneath the external lateral ligament between it and the tendon 
 of the Popliteus (this is sometimes only an expansion from the next bursa); 
 
 (4) one beneath the tendon of the Popliteus (bursa musculi poplitei) between it 
 and the condyle of the femur, which is almost always an extension from the syno- 
 vial membrane of the joint. On the inner side there are fivehursee: (1) one 
 beneath the inner head of the Gastrocnemius, which sends a prolongation between 
 the tendons of the Gastrocnemius and Semimembranosus : this bursa often com- 
 municates with the joint; (2) one above the internal lateral ligament between it 
 and the tendons of the Sartorius, Gracilis, and Semitendinosus; (3) one beneath 
 the internal lateral ligament between it and the tendon of the Semimembra- 
 nosus: this is sometimes only an expansion from the next bursa; (4) one beneath 
 the tendon of the Semimembranosus, between it and the head of the tibia; 
 
 (5) sometimes there is a bursa between the tendons of the Semimembranosus 
 and of the Semitendinosus. 
 
 Structures around the Joint. — In front and at the sides, the Quadriceps extensor; 
 on the outer side, the tendons of the Biceps and the Popliteus and the external 
 popliteal nerve; on the inner side, the Sartorius, Gracilis, Semitendinosus, and 
 Semimembranosus; behind, an expansion from the tendon of the Semimembra- 
 nosus, the popliteal vessels, and the internal popliteal nerve, the Popliteus, the 
 Plantaris, and the inner and outer heads of the Gastrocnemius, some lymphatic 
 glands, and fat. 
 
 The arteries supplying the joint are derived from the anastomotica magna 
 branch of the femoral, articular branches of the popliteal, anterior and posterior 
 recurrent branches of the anterior tibial, and a descending branch from the 
 external circumflex of the Profunda. 
 
 The nerves are derived from the obturator, anterior crural, and external and 
 internal popliteal. 
 
 Actions. — The knee-joint permits of movements of flexion and extension, and, 
 in certain positions, of slight rotation inward and outward. The movement of 
 flexion and extension does not, however, take place in a simple, finger-like man- 
 ner, as in other joints, but is a complicated movement, consisting of a certain 
 amount of gliding and rotation; so that the same part of one articular surface is 
 not always applied to the same part of the other articular surface, and the axis 
 of motion is not a fixed one. If the joint is examined while in a condition of 
 extreme flexion, the posterior part of the articular surfaces of the tibia will be 
 found to be in contact with the posterior rounded extremities of the condyles of 
 the femur; and if a simple hinge-like movement were to take place, the axis, 
 round which the revolving movement of the tibia occurs, would be in the back 
 part of the condyle. If the leg is now brought forward into a position of semi- 
 flexion, the upper surface of the tibia will be seen to glide over the condyles of 
 the femur, so that the middle part of the articular facets are in contact, and the 
 axis of rotation must therefore have shifted forward to nearer the centre of the 
 condyles. If the leg is now brought into the extended position, a still further 
 gliding takes place and a further shifting forward of the axis of rotation. This 
 
 1 Spalteholz's Hand Atlas of Human Anatomy. Translated by Lewellys F. Barker. 
 
342 THE ARTICULATIONS OR JOINTS 
 
 is not, however, a simple movement, but is accompanied by a certain amount of 
 rotation outward round a vertical axis drawn through the centre of the head of 
 the tibia. This rotation is due to the greater length of the internal condyle, and 
 to the fact that the anterior portion of its articular surface is inclined obliquely 
 outward. In consequence of this it will be seen that toward the close of the 
 movement of extension — that is to say, just before complete extension is effected 
 — the tibia glides obliquely upward and outward over this oblique surface on the 
 inner condyle, and the leg is therefore necessarily rotated outward. In flexion 
 of the joint the converse of these movements takes place: the tibia glides backward 
 round the end of the femur, and at the commencement of the movement the tibia 
 is directed downward and inward along the oblique curve of the inner condyle, 
 thus causing an inward rotation to the leg. 
 
 During flexion and extension the patella moves on the lower end of the femur, 
 but this movement is not a simple gliding one; for if the articular surface of this 
 bone is examined, it will be found to present on each side of the central vertical 
 ridge two less marked transverse ridges, which divide the surface, except a small 
 portion along the inner border, which is cut off by a slight vertical ridge into 
 six facets (see Fig. 247), and therefore does not present a uniform curved surface 
 
 as would be the case if a simple gliding movement took 
 place. These six facets — three on each side of the 
 median vertical ridge — correspond to and denote the 
 parts of the bone respectively in contact with the con- 
 dyles of the femur during flexion, semiflexion, and exten- 
 sion. In flexion only the upper facets on the patella are 
 in contact with the condyles of the femur; the lower 
 two-thirds of the bone rests upon the mass of fat which 
 occupies the space between the femur and tibia. In the 
 semiflexed position of the joint the middle facets on the 
 Fig 247 —View of the pos- Patella rcst upon the most prominent portion of the con- 
 terior surface of the patella, dvlcs, and thus afford greater leverage to the Quadriceps 
 
 showing diagrammatically the ,"'. . .,. "^^ ^ ». i 
 
 areas of contact with the femur by mcrcasiug its distaucc irom the Centre oi motion. In 
 
 in different positions of the , . , . ,, j ii • i ,i , i 
 
 knee. Complete extension the patella is drawn up, so that only 
 
 the lower facets are in contact with the articular sur- 
 faces of the condyles. The narrow strip along the inner border is in contact 
 with the outer aspect of the internal condyle when the leg is fully flexed at 
 the knee-joint. As in the elbow, so it is in the knee — the axis of rotation in 
 flexion and extension is not precisely at right angles to the axis of the bone, but 
 during flexion there is a certain amount of alteration of plane; so that, whereas in 
 flexion the femur and tibia are in the same plane, in extension the one bone forms 
 an angle of about 10 degrees with the other. There is, however, this difference 
 between the two extremities: that in the upper, during extension, the humeri are 
 parallel and the bones of the forearm diverge; in the lower, the femora converge 
 below and the tibia are parallel. 
 
 In addition to the slight rotation during flexion and extension, the tibia enjoys 
 an independent rotation on the condyles of the femur in certain positions of the 
 joint. This movement takes place between the interarticular fibro-cartilages and 
 the tibia, whereas the movement of flexion and extension takes place between the 
 interarticular fibro-cartilages and the femur. So that the knee may be said to 
 consist of two joints, separated by the fibro-cartilages: an upper, menisco-femoral, 
 in which flexion and extension take place; and a lower, menisco-tibial, allowing 
 of a certain amount of rotation. This latter movement can only take place in the 
 semiflexed position of the limb, when all the ligaments are relaxed. • 
 
 During flexion the ligamentum patellae is put upon the stretch, as is also the 
 posterior crucial ligament in extreme flexion. The other ligaments are all relaxed 
 
THE KNEE JOINT 343 
 
 by flexion of the joint, though the relaxation of the anterior crucial ligament is 
 very trifling. During life flexion is checked by the contact of the leg with the 
 thigh. In the act of extending the leg upon the thigh the ligamentuin patellse is 
 tightened by the Quadriceps extensor; but when the leg is fully extended, as in the 
 erect posture, the ligament becomes relaxed, so as to allow free lateral movement to 
 the patella, which then rests on the front of the lower end of the femur. The other 
 ligaments, with the exception of the posterior crucial, which is partly relaxed, are all 
 on the stretch. When the limb has been brought into a straight line, extension is 
 checked mainly by the tension of all the ligaments except the posterior crucial and 
 ligamentum patellae. The movements of rotation of which the knee is capable are 
 permitted in the semiflexed condition by the partial relaxation of both crucial liga- 
 ments, as well as of the lateral ligaments. Rotation inward appears to be limited 
 by the tension of the anterior crucial ligament, and by the interlocking of the two 
 ligaments; but rotation outward does not appear to be checked by either crucial 
 ligament, since they uncross during the execution of this movement, but it is 
 checked by the lateral ligaments, especially the internal. The main function of 
 the crucial ligaments is to act as a direct bond of union between the tibia and 
 femur, preventing the former bone from being carried too far backward or 
 forward. Thus the anterior crucial ligament prevents the tibia being carried 
 too far forward by the extensor tendons, and the posterior crucial checks too 
 great movement backward by the flexors. They also assist the lateral ligaments 
 in resisting any lateral bending of the joint. The interarticular cartilages are 
 intended, as it seems, to adapt the surface of the tibia to the shape of the femur 
 to a certain extent, so as to fill up the intervals which would otherwise be felt 
 in the varying positions of the joint, and to interrupt the jars which would be 
 so frequently transmitted up the limb in jumping or falls on the feet; also to 
 permit of the two varieties of motion, flexion and extension, and rotation, as 
 explained above. The patella is a great defence to the knee-joint from any 
 injury inflicted in front, and it distributes upon a large and tolerably even sur- 
 face during kneeling the pressure which would otherwise fall upon the prominent 
 ridges of the condyles ; it also affords leverage to the Quadriceps extensor muscle 
 when it acts upon the tibia; and Mr. Ward has pointed out^ how this leverage 
 varies in the various positions of the joint, so that the action of the muscles pro- 
 duces velocity at the expense of force in the commencement of extension, and, on 
 the contrary, at the close of extension tends to diminish velocity, and therefore 
 the shock to the ligaments at the moment tension of the structures takes place. 
 Extension of the leg on the thigh is performed by the Quadriceps extensor; 
 flexion by the hamstring muscles, assisted by the Gracilis and Sartorius, and, 
 indirectly, by the Gastrocnemius, Popliteus, and Plantaris; rotation outward, by 
 the Biceps; and rotation inward by the Popliteus, Semitendinosus, and, to a slight 
 extent, the Semimembranosus, the Sartorius, and the Gracilis. 
 
 Surface Form. — The interval between the two bones entering into the formation of the knee- 
 joint can always easily be felt. If the limb is extended, it is situated on a slightly higher level 
 than the apex of the patella; but if the limb is slightly flexed, a knife carried horizontally back- 
 ward immediately below the apex of the patella would pass directly into the joint. When the 
 knee-joint is distended with fluid, the outline of the synovial membrane at the front of the knee 
 may be fairly well mapped out. 
 
 Surgical Anatomy. — The bursa; about the knee are frequently the seat of inflammation. 
 Enlargement of the prepatellar bursa constitutes housemaid' s knee. The bursa beneath the 
 Semimembranosus may enlarge greatly. It communicates with the knee-joint and can frequently 
 be made to disappear bv pressure when the knee is flexed. Treves points out that enlargement 
 of the bursa between the biceps tendon and the external lateral ligament causes great pain 
 because the peroneal nerve crosses the sac.^ 
 
 From a consideration of the construction of the knee-joint it would at first sight appear to be 
 
 1 Human Osteology, p. 405. ^ Applied Anatomy. 
 
344 THE ARTICULATIONS OB JOINTS 
 
 one of the least secure of any of the joints in the body. It is formed between the two longest 
 bones, and therefore the amount of leverage which can be brought to bear upon it is very con- 
 siderable; the articular surfaces are but ill adapted to each other, and the range and variety of 
 motion which it enjoys is great. All these circumstances tend to render the articulation very 
 insecure; but, nevertheless, on account of the very powerful ligaments which bind the bones 
 together, the joint is one of the strongest in the body, and dislocation from traumatism is of 
 very rare occurrence. When, on the other hand, the ligaments have been softened or destroyed 
 by disease, partial displacement is very liable to occur, and is frequently brought about by the 
 mere action of the muscles displacing the articular surfaces from each other. The tibia may 
 be dislocated in any direction from the femur — forward, backward, inward, or outward; or a 
 combination of two of these dislocations may occur — that is, the tibia may be dislocated for- 
 ward and laterally, or backward and laterally, and any of these dislocations may be complete 
 or incomplete. As a rule, however, the antero-posterior dislocations are complete, the lateral 
 ones incomplete. 
 
 One or other of the semilunar cartilages may become displaced and nipped between the 
 femur and tibia. The accident is produced by a twist of the leg when the knee is flexed, and is 
 accompanied by a sudden pain and fixation of the knee in a flexed position. The cartilage may 
 be displaced either inward or outward: that is to say, either inward toward the tibial spine, so 
 that the cartilage becomes lodged in the intercondyloid notch; or outward, so that the car- 
 tilage projects beyond the margin of the articular surface. Acute synovitis, the result of trau- 
 matism or exposure to cold, is very common in the knee, on account of its superficial position. 
 When distended with fluid, the swelling shows itself above and at the sides of the patella, reach- 
 ing about an inch or more above the trochlear surface of the femur, and extending a little higher 
 under the Vastus internus than the Vastus externus. Occasionally the swelling may extend 
 two inches or more. At the sides of the patella the swelling extends lower at the inner side 
 than it does on the outer side. The lower level of the synovial membrane is just above the 
 level of the upper part of the head of the fibula. In the middle line it covers the upper third 
 of the ligamentum patellae, being separated from it, however, by the capsule and a pad of fat. 
 Chronic synovitis principally shows itself in the form of pulpy degeneration of the synovial mem- 
 brane, the result of tuberculous arthritis. The reasons why tuberculous disease of the knee 
 so often commences in the synovial membrane appear to be the complex and extensive nature of 
 this sac; the extensive vascular supply to it; and the fact that injuries are generally diffused 
 and applied to the front of the joint rather than to the ends of the bones. Syphilitic disease 
 not unfrequently attacks the knee-joint. In the hereditary form of the disease it is usually 
 symmetrical, attacking both joints, which become filled with synovial effusion, and is very intract- 
 able and difficult to cure. In the tertiary stage of acquired syphilis gummatous infiltration of 
 the synovial membrane may take place. The knee is one of the joints most commonly affected with 
 osteo-arthritis, and is said to be more frequently the seat of this disease in women than in men. 
 The occurrence of the so-called loose cartilage is almost confined to the knee, though loose cartilages 
 are occasionally met with in the elbow, and, rarely, in some other joints. Many of them occur in 
 cases of osteo-arthritis, in which calcareous or cartilaginous material is formed in one of the synovial 
 fringes and constitutes the foreign body, and may or may not become detached, in the former 
 case only meriting the usual term, " loose " cartilage. In other cases they have their origin in the 
 exudation of inflammatory lymph, and possibly, in some rare instances, a portion of the articular 
 cartilage or one of the semilunar cartilages becomes detached and constitutes the foreign body. 
 
 Genu valgum, or knock-knee, is a common deformity of childhood, in which, owing to 
 changes in and about the joint, the angle between the outer border of the tibia and femur is 
 diminished, so that as the patient stands the two internal condyles of the femora are in contact, 
 but the two internal malleoli of the tibise are more or less widely separated from each other. 
 When, however, the knees are flexed to a right angle, the two legs are practically parallel with 
 each other. At the commencement of the disease there is a yielding of the internal lateral liga- 
 ment and other fibrous structures on the inner side of the joint; as a result of this there is a 
 constant undue pressure of the outer tuberosity of the tibia against the outer condyle of the 
 femur. This extra pressure causes arrest of growth and, possibly, wasting of the outer con- 
 dyle, and a consequent tendency for the tibia to become separated from the internal condyle. 
 To prevent this the internal condyle becomes depressed; probably, as was first pointed out by 
 Mikulicz, by an increased growth of the lower end of the diaphysis on its inner side, so that the 
 line of the epiphysis becomes oblique instead of transverse to the axis of the bone, with a direc- 
 tion downward and inward. It is often said that the deformity is produced by undue length 
 of the inner condyle, but in reality the condyle grows as the deformity progresses. 
 
 Excision of the knee-joint is most frequently required for tuberculous disease of this articula- 
 tion, but is also practised in cases of disorganization of the knee after rheumatic fever, pyaemia, 
 etc., in osteo-arthritis, and in ankylo^s. It is also occasionally called for in cases of injury, gun- 
 shot or otherwise. The operation is best performed either by a horseshoe incision, starting from 
 one condyle, descending as low as the tubercle of the tibia, where it crosses the leg, and is then 
 earned upward to the other condyle; or by a transverse incision across the patella. In this 
 
TIBIO- FIBULAR ARTICULATION 
 
 345 
 
 TUBEROSITY 
 OF TIBIA 
 
 latter incision the patella is either removed or sawn across, and the halves subsequently sutured 
 together. The bones having been cleared, and in those cases where the operation is performed 
 for tuberculous disease all pulpy tissue having been carefully removed, the section of the femur 
 is first made. This should never include, in children, more than, at the most, two-thirds of 
 the articular surface, otherwise the epiphysial cartilage will be involved, with disastrous results 
 as regards the growth of the limb. Afterward a thin slice should be removed from the upper 
 end of the tibia, not more than half an inch. If any diseased tissue still appears to be left in the 
 bones, it should be removed with the gouge rather than by making a further section of the bones. 
 
 III. Tibio-fibular Articulation 
 (Articulatio Tibiofibularis) . 
 
 The articulations between the tibia 
 and fibula are effected by ligaments 
 which connect both extremities, as 
 well as the shafts of the bones. It 
 may, consequently, be subdivided 
 into three articulations: 1. The 
 superior tibio-fibulax articulation. 2. 
 The middle tibio-fibular ligament or 
 interosseous membrane. 3. The 
 inferior tibio-fibular articulation. 
 
 1. Superior Tibio-fibular Artic- 
 ulation (Articulatio 
 Tibiofibularis) . 
 
 This articulation is an arthrodial 
 joint. The contiguous surfaces of 
 the bones present two flat, oval 
 facets covered with cartilage, and 
 connected together by the following 
 ligaments : 
 
 Capsular. 
 
 Anterior Superior Tibio-fibular. ' 
 
 Posterior Superior Tibio-fibular. 
 
 The Capsular Ligament (capsula 
 articularis) consists of a membra- 
 nous bag which surrounds the artic- 
 ulation, being attached around the 
 margins of the articular facets on 
 the tibia and fibula, and is much 
 thicker in front than behind. 
 
 The new nomenclature considers 
 the anterior and posterior ligaments 
 as one ligament {ligamentum capitidi 
 fibulce). 
 
 The Anterior Superior Ligament 
 (Fig. 248) consists of two or three 
 broad and flat bands which pass 
 obliquely upward and inward from 
 the front of the head of the fibula 
 to the front of the outer tuberosity 
 of the tibia. 
 
 The Posterior Superior Ligament 
 (Fig. 241) is a single thick and 
 
 INNER 
 MALLEOLUS 
 
 OUTER 
 MALLEOLUS 
 
 TERIOR LIGAMENT 
 OF LATERAL 
 MALLEOLUS 
 
 Fig. 248. — Ligaments of the right leg, from in front. 
 (Spalteholz.) 
 
346 THE ARTICULATIONS OR JOINTS 
 
 broad band which passes upward and inward from the back part of the head of 
 the fibula to the back part of the outer tuberosity of the tibia. It is covered by 
 the tendon of the Pophteus muscle. 
 
 Synovial Membrane. — A synovial membrane lines this articulation, which at its 
 upper and back part is occasionally continuous with that of the knee-joint. 
 
 2. Middle Tibio-fibular Ligament or Interosseous Membrane 
 (Membrana Interossea Cruris) (Fig. 248). 
 
 An interosseous membrane extends between the contiguous margins of the 
 tibia, and fibula and separates the muscles on the front from those on the back 
 of the leg. It consists of a thin, aponeurotic lamina composed of oblique fibres 
 which for the most part pass downward and outward between the interosseous 
 ridges on the two bones; some few fibres, however, pass in the opposite direction, 
 downward and inward. It is broader above than below. Its upper margin does 
 not quite reach the superior tibio-fibular joint, but presents a free concave bprder, 
 above which is a large, oval aperture for the passage of the anterior tibial vessels 
 forward to the anterior aspect of the leg. At its lower part is an opening for the 
 passage of the anterior peroneal vessels. It is continuous below with the inferior 
 interosseous ligament, and is perforated in numerous places for the passage of small 
 vessels. It is in relation, in front, with the Tibialis anticus. Extensor longus digi- 
 torum. Extensor proprius hallucis, Peroneus tertius, and the anterior tibial vessels 
 and nerve ; behind, with the Tibialis posticus and Flexor longus hallucis. 
 
 3. Inferior Tibio-fibular Articulation (Syndesmosis Tibiofibularis) 
 
 (Figs. 250, 251, 252). 
 
 This articulation is formed by the rough, convex surface of the inner side of 
 the lower end of the fibula, connected with a concave rough surface on the outer 
 side of the tibia. Below, to the extent of about two lines, these surfaces are smooth, 
 and covered with cartilage, which is continuous with that of the ankle-joint. The 
 ligaments of this joint are- 
 Anterior Inferior Tibio-fibular. . Transverse or Inferior. 
 Posterior Inferior Tibio-fibular. Inferior Interosseous. 
 
 The Anterior Inferior Ligament (ligamentum malleoli lateralis anterius) (Figs. 248 
 and 252) is a flat, triangular band of fibres, broader belowthan above, which extends 
 obliquely downward and outward, between the adjacent margins of the tibia and 
 fibula, on the front aspect of the articulation. It is in relation, in jront, with the 
 Peroneus tertius, the aponeurosis of the leg, and the integument; behind, with 
 the inferior interosseous ligament; and lies in contact with the cartilage covering 
 the astragalus. 
 
 The Posterior Inferior Ligament {ligamentum malleoli lateralis posterius) (Fig. 
 252), smaller than the preceding, is disposed in a similar manner on the posterior 
 surface of the articulation. 
 
 The Transverse Ligament or Inferior Ligament lies under cover of the posterior 
 ligament, and is a strong, thick band of yellowish fibres which passes transversely 
 across the back of the joint, from the external malleolus to the posterior border of 
 the articular surface of the tibia, almost as far as its malleolar process. This liga- 
 ment projects below the margin of the bones, and forms part of the articulating 
 surface for the astragalus. 
 
 The Inferior Interosseous Ligament (Fig. 250) consists of numerous short, strong, 
 fibrous bands which pass between the contiguous rough surfaces of the tibia and 
 fibula, and constitute the chief bond of union between the bones. This ligament 
 is continuous above with the interosseous membrane. 
 
THE TIBIO- TARSAL ARTICULATION 
 
 347 
 
 Synovial Membrane. — The synovial membrane lining the articular surface is 
 derived from that of the ankle-joint (Fig. 250). 
 
 Actions. — The movement permitted in these articulations is limited to a very 
 slight gliding of the articular surfaces one upon another. 
 
 IV. The Tibio-tarsal Articulation or Ankle-joint (Articulatio Talocruralis) 
 
 (Figs. 249, 250, 251, 252). 
 
 The ankle is a ginglymus or hinge-joint. The bones entering into its formation 
 are the lower extremity of the tibia and its malleolus and the external malleolus 
 
 Tarso-metatar 
 articulations 
 
 Tarsal articulations. 
 
 Fig. 249. — Ankle-joint: tarsal and tarso-metatarsal articulations. Internal view. Right side. 
 
 of the fibula, which forms a mortise (Fig. 248) to receive the upper convex surface 
 of the astragalus and its two lateral facets. The bony surfaces are covered with car- 
 tilage and connected together by a capsule (capsula articularis) , which in places 
 forms thickened bands constituting the following ligaments: 
 
 Anterior. Internal Lateral. 
 
 Posterior. External Lateral. 
 
 The Anterior Tibio-tarsal Ligament {ligamentum talotihiale anterius) is a broad, 
 thin, membranous layer, attached, above, to the anterior margin of the lower 
 extremity of the tibia; below, to the margin of the astragalus, in front of its artic- 
 ular surface. It is in relation, in front, with the Extensor tendons of the toes, with 
 the tendons of the TibiaHs anticus and Peroneus tertius, and the anterior tibial 
 vessels and nerve; behind, it lies in contact with the synovial membrane. 
 
 The Posterior Tibio-tarsal Ligament {ligamentum talotihiale posterius) is very 
 thin, and consists principally of transverse fibres. It is attached, above, to the 
 margin of the articular surface of the tibia, blending with the transverse tibio- 
 fibular ligament; below, to the astragalus, behind its superior articular facet. 
 Externally, where a somewhat thickened band of transverse fibres is attached to 
 the hollow on the inner surface of the external malleolus, it is thicker than inter- 
 nally. 
 
348 
 
 THE ARTICULATIONS OB JOINTS 
 
 The Internal Lateral or Deltoid Ligament (ligamentum calcaneotib iale or ligamentum 
 deltoideum) (Figs. 249, 250, and 251) is a strong, flat, triangular band, attached, 
 above, to the apex and anterior and posterior borders of the inner malleolus. 
 The most anterior fibres pass forward to be inserted into the scaphoid bone and 
 the inferior calcaneo-scaphoid ligament; the middle descend almost perpendicu- 
 larly to be inserted into the sustentaculum tali of the os calcis; and the posterior 
 fibres pass backward and outward to be attached to the inner side of the astragalus. 
 This ligament is covered by the tendons of the Tibialis posticus and Flexor longus 
 digitorum muscles. 
 
 The External Lateral Ligament {ligamenta talofibularia et calcaneofibulare) (Figs. 
 251 and 252) consists of three distinctly specialized* fasciculi of the capsule, 
 taking different directions and separated by distinct intervals; for which reason 
 it is described by some anatomists as three distinct ligaments.^ 
 
 The anterior fasciculus (ligamentum talofibulare anterius), the shortest of the 
 three, passes from the anterior margin of the external malleolus forward and 
 inward to the astragalus, in front of its external articular facet. 
 
 INTEROSSEOUS. 
 LIGAME 
 
 SYNOVIAL 
 ADIPOSE PAD 
 
 PERONE 
 IREVIS MUSC 
 
 PERONEU 
 LONGUS MUSCL 
 
 NTERNAL LATERAL 
 LIGAMENT 
 TIBIALIS POSTICUS 
 
 NTEROSSEOUS CAL- 
 NEO ASTRAGALOID 
 GAMENT 
 
 EXOR LONGUS 
 
 GITORUM 
 
 EXOR LONGUS 
 HALLUCIS 
 POSTERIOR 
 TIBIAL VESSELS 
 
 Fig. 250. — Frontal section through the ankle-joint and the calcaneo-astragaloid articulation. 
 (Poirier and Charpy). 
 
 The posterior fasciculus {ligamentum talofibulare posterius), the most deeply seated, 
 passes inward from the depression at the inner and back part of the external mal- 
 leolus to a prominent tubercle on the posterior surface of the astragalus. Its fibres 
 are almost horizontal in direction. 
 
 The middle fasciculus (ligamentum calcaneofibulare) (Figs. 251 and 252), the 
 longest of the three, is a narrow, rounded cord passing from the apex of the 
 external malleolus downward and slightly backward to a tubercle on the outer 
 surface of the os calcis. It is covered by the tendons of the Peroneus longus and 
 brevis. 
 
 Sjmovial Membrane. — The synovial membrane (^Fig. 250) invests the inner 
 surface of the ligaments, and sends a duplicature upward between the lower 
 extremities of the tibia and fibula for a short distance. 
 
 ^ Humphry. On the Skeleton, p. 559. 
 
THE TIBIO- TARSAL ARTICULATION 
 
 349 
 
 Relations. — The tendons, vessels, and nerves in connection with the joint are, 
 in jront, from within outward, the TibiaHs anticus, Extensor proprius hallucis, 
 anterior tibial vessels, anterior tibial nerve, Extensor longus digitorum, and Pero- 
 neus tertius; behind, from within outward, the Tibialis posticus, Flexor longus 
 
 INTERNAL 
 
 INTEROSSEOUS 
 
 LIGAMENT 
 
 TARSO- 
 METATARSAL 
 ARTICULATIONS 
 
 INTEROSSEOUS 
 LIGAMENT 
 
 ASTRAGALO- 
 
 SCAPHOID 
 
 ARTICULATION 
 
 TENDON OF POS 
 TERIOR TIBIAL 
 MUSCLE 
 
 INTEROSSEOUS 
 LIGAMENTS 
 
 INTERMETATARSAL 
 ARTICULATIONS 
 
 INTEROSSEOUS 
 LIGAMENT 
 
 CALCANEO-SCAPHOID 
 LIGAMENT 
 
 CALCANEO-CUBOID 
 ARTICULATION 
 
 INTEROSSEOUS 
 LIGAMENT 
 
 ASTRAGALO-CALCANEAL 
 RTICULATION 
 
 ANKLE-JOINT 
 
 MIDDLE FASCICULUS 
 OF THE EXTERNAL 
 LATERAL LIGAMENT 
 
 INFERIOR TIBIO- 
 FIBULAR ARTICULATION 
 
 Fig. 251. — Joints of the right foot, from the back of the foot. (Spalteholz.) 
 
 digitorum, posterior tibial vessels, posterior tibial nerve, Flexor longus hallucis; 
 and in the groove behind the external malleolus, the tendons of the Peroneus 
 longus and brevis. 
 
 The arteries supplying the joint are derived from the malleolar branches of 
 the anterior tibial and the peroneal. 
 
350 
 
 THE ARTICULATIONS OH JOINTS 
 
 The nerves are derived from the anterior and posterior tibial. 
 
 Actions. — The movements of the joint are those of flexion and extension. 
 Flexion consists in the approximation of the dorsum of the foot to the front of the 
 leg, while in extension the heel is drawn up and the toes pointed downward. The 
 malleoli tightly embrace the astragalus in all positions of the joint, so that any 
 slight degree of lateral movement which may exist is simply due to stretching 
 of the inferior tibio-fibular ligaments and slight bending of the shaft of the fibula. 
 Of the ligaments, the internal, or deltoid, is of very great power — so much so 
 that it usually resists a force which fractures the process of bone to which it is 
 attached. Its middle portion, together with the middle fasciculus of the external 
 lateral ligament, binds the bones of the leg firmly to the foot and resists displace- 
 ment in every direction. Its anterior and posterior fibres limit extension and 
 flexion of the foot respectively, and the anterior fibres also limit abduction. The 
 posterior portion of the external lateral ligament assists the middle portion in 
 resisting the displacement of the foot backward, and deepens the cavity for the 
 
 Inferior tibio-fibidar articulation. 
 
 Tarsal articulations. 
 
 Tarso-metatar.sal 
 
 articulations. 
 
 Fig. 252. — Ankle-joint: tarsal and tarso-metatarsal articulations. External view. Right side. 
 
 reception of the astragalus. The anterior fasciculus is a security against the dis- 
 placement of the foot forward, and limits extension of the joint. The movements 
 of inversion and eversion of the foot, together with the minute changes in form by 
 which it is applied to the ground or takes hold of an object in climbing, etc., are 
 mainly effected in the tarsal joints, the one which enjoys the greatest amount of 
 motion being that between the astragalus and os calcis behind and the scaphoid 
 and cuboid in front. This is often called the transverse or medio-taxsal joint, and 
 it can, with the subordinate joints of the tarsus, replace the ankle-joint in a great 
 measure when the latter has become ankylosed. 
 
 Extension of the tarsal bones upon the tibia and fibula is produced by the 
 Gastrocnemius, Soleus, Plantaris, Tibialis posticus, Peroneus longus and brevis, 
 Flexor longus digitorum, and Flexor longus hallucis; flexion, by the Tibialis anti- 
 cus, Peroneus tertius, Extensor longus digitorum, and Extensor proprius hallucis* 
 
 ' The student must bear in mind that the Extensor longus digitorum and Extensor proprius hallucis are 
 extensors of the toes, but/ea:oj-s of the ankle, and that the Flexor longus digitorum and Flexor longus hallucis are 
 flexors of the toes, but extensors of the ankle. 
 
THE TIBIO- TARSAL ARTICULATION 
 
 351 
 
 (Fig. 251) ; imsrsion, in the extended position, is produced by the Tibialis anticus 
 and posticus; and eversion by the Peronei, 
 
 Fig. 
 
 263. — Section of the right foot near its inner border, dividing the tibia, astragalus, scaphoid, internal 
 
 cuneiform, and first metatarsal bone, and the first phalanx of the great toe. (After Braune.) 
 
 Surface Form. — The line of the ankle-joint may be indicated by a transverse line drawn 
 across the front of the lower part of the leg, about half an inch above the level of the tip of the 
 internal malleolus. 
 
 Surgical Anatomy. — Displacement of the trochlear surface of the astragalus from the tibio- 
 fibular mortise is not of common occurrence, as the ankle-joint is a very strong and powerful 
 articulation, and great force is required to produce dislocation. Nevertheless, dislocation does 
 occasionally occur, both in an antero-posterior and a lateral direction. In the latter, which is the 
 most common, fracture is a necessary accompaniment of the injury. The dislocation in these cases 
 is somewhat peculiar, and is not a displacement in a horizontally lateral direction, such as usually 
 occurs in lateral dislocations of ginglymoid joints, but the astragalus undergoes a partial rotation 
 round an antero-posterior axis drawn through its own centre, so that the superior surface, instead 
 of being directed upward, is inclined more or less inward or outward according to the variety of 
 the displacement. 
 
 The ankle-joint is more frequently sprained than any joint in the body, and this may lead 
 to acute synovitis. In these cases, when the synovial sac is distended with fluid, the bulging 
 appears principally in the front of the joint, beneath the anterior tendons, and on either side, 
 between the tibialis anticus and the internal lateral ligament on the inner side, and between the 
 Peroneus tertius and the external lateral ligament on the outer side. In addition to this, bulging 
 frequently occurs posteriorly, and a fluctuating swelling may be detected on either side of the 
 tendo Achillis. 
 
 Chronic synovitis may result from frequent sprains, and when once this joint has been 
 sprained it is more liable to a recurrence of the injury than it was before; chronic synovitis 
 may be tuberculous in its origin, the disease usually commencing in the astragalus and extending 
 to the joint, though it may commence as a synovitis the result probably of some slight strain in 
 a tuberculous subject. 
 
 Excision of the ankle-joint is not often performed for two reasons. In the first place, disease 
 of the articulation for which this operation is indicated is frequently associated with disease of 
 the tarsal bones, which prevents its performance; and, secondly, the foot after excision is fre- 
 quently of very little use; far less, in fact, than after a Syme's amputation, which is often, there- 
 fore, a preferable operation in these cases. Excision may, however, be attempted in a case of 
 tuberculous arthritis in a young and otherwise healthy subject, where the disease is limited to 
 the bones forming the joint. It may also be required after injury where the vessels and nerves 
 have not been damaged and the patient is young and free from visceral disease. The excision is 
 best performed through two lateral incisions. One commencing two and a half inches above the 
 external malleolus, carried down the posterior border of the fibula, round the end of the bone, 
 and then forward and downward as far as the calcaneo-cuboid joint, midway between the tip 
 of the external malleolus and the tuberosity on the fifth metatarsal bone. Through this incision 
 
352 THE ARTICULATIONS OR JOINTS 
 
 the fibula is cleared, the external lateral ligament is divided, and the bone sawn through about 
 half an inch above the level of the ankle-joint and removed. A similar curved incision is now 
 made on the inner side of the foot, commmencing two and a half inches above the lower end of 
 the tibia, carried down the posterior border of the bone, round the internal malleolus, and for- 
 ward and downward to the tuberosity of the scaphoid bone. Through this incision the tibia is 
 cleared in front and behind, the internal lateral, the anterior and posterior ligaments divided, 
 and the end of the tibia protruded through the wound by displacing the foot outward, and sawn 
 off sufficiently high to secure a healthy section of bone. The articular surface of the astragalus 
 is now to be sawn off or the whole bone removed. In cases where the operation is performed 
 for tuberculous arthritis the latter course is probably preferable, as the injury done by the saw is 
 frequently the starting point of fresh caries; and after removal of the whole bone the shortening 
 is not appreciably increased, and the result as regards union appears to be as good as when two 
 sawn surfaces of bone are brought into apposition. 
 
 V. Articulations of the Tarsus (Articulationes Intertarsese) (Figs. 249, 
 
 251, 252, 254, 255). 
 
 1. Articulation of the Os Calcis and Astragalus or the Calcaneo- 
 
 ASTRAGALOID ARTICULATION (ArTICULATIO TaLOCALCANEA) (Fig. 251). 
 
 The articulations between the os calcis and astragalus are two in number — 
 anterior and posterior. They are arthrodial joints. The bones are connected 
 together by a capsule (capsula articularis) , which is at certain points accentuated 
 into definite ligaments. There are five ligaments in this articulation: 
 
 External Calcaneo-astragaloid, Anterior Calcaneo-astragaloid. 
 
 Internal Calcaneo-astragaloid. Posterior Calcaneo-astragaloid. 
 
 Interosseous. 
 
 The External Calcaneo-astragaloid Ligament (ligainentum talocalcaneum laterale) 
 (Fig. 252) is a short, strong, fasciculus passing from the outer surface of the 
 astragalus, immediately beneath its external malleolar facet, to the outer surface 
 of the OS calcis. It is placed in front of the middle fasciculus of the external 
 lateral ligament of the ankle-joint, with the fibres of which it is parallel. 
 
 The Internal Calcaneo-astragaloid Ligament {ligainentum talocalcaneum mediale) 
 is a band of fibres connectino- the internal tubercle of the back of the astragalus 
 with the back of the sustentaculum tali. Its fibres blend with those of the inferior 
 calcaneo-scaphoid ligament. 
 
 The Anterior Calcaneo-astragaloid Ligament (ligamentum talocalcaneum anterius) 
 passes from the front and outer surface of the neck of the astragalus to the supe- 
 rior surface of the os calcis. 
 
 The Posterior Calcaneo-astragaloid Ligament (ligamentum talocalcaneum posterius) 
 connects the external tubercle of the astragalus with the upper and inner part 
 of the OS calcis ; it is a short band, the fibres of which radiate from their narrow 
 attachment to the astragalus. 
 
 The Interosseous Ligament {ligamentum talocalcaneum interosseum) (Figs. 250, 
 251, and 255) forms the chief bond of union between the bones. It consists of 
 numerous vertical and oblique fibres attached by one extremity to the groove 
 between the articulating facets on the under surface of the astragalus; by the 
 other to a corresponding depression on the upper surface of the os calcis. It 
 is very thick and strong, being at least an inch in breadth from side to side, 
 and serves to unite the os calcis and astragalus solidly together. 
 
 SjTiovial Membrane. — The synovial membranes (Fig. 255) are two in num- 
 ber: one for the posterior calcaneo-astragaloid articulation; a second for the 
 anterior calcaneo-astragaloid joint. The latter synovial membrane is con- 
 tinued forward between the contiguous surfaces of the astragalus and scaphoid 
 bones. 
 
ARTICULATIONS OF THE TARSUS 353 
 
 Actions. — The movements permitted between the astragalus and os calcis are 
 limited to a ghding of the one bone on the other in a direction from before back- 
 ward, and from side to side. 
 
 2. Articulation of the Os Calcis with the Cuboid or the Calcaneo- 
 cuboid Articulation (Articulatio Calcaneocuboidea) (Fig. 251). 
 
 In this joint the articular capsule {capsula articularis) is strengthened at 
 certain points by definite ligaments. 
 
 The ligaments connecting the os calcis with the cuboid are four in number: 
 
 Dorsal or Superior Calcaneo-cuboid. T PI t ^ Long Calcaneo-cuboid. 
 The Internal Calcaneo-cuboid. \ Short Calcaneo-cuboid. 
 
 The Superior Calcaneo-cuboid Ligament {ligamentum calcaneocuhoideum dorsale) 
 (Fig. 252) is a broad portion of the capsule which passes between the contiguous 
 surfaces of the os calcis and cuboid on the dorsal surface of the joint. 
 
 The Internal Calcaneo-cuboid or the Interosseous Ligament {'pars calcaneo- 
 cuboidea ligamenti bifurcati) is a short but thick and strong band of fibres 
 arising from the cfs calcis, in the deep hollow which intervenes between it and 
 the astragalus, and closely blended, at its origin, with the superior calcaneo- 
 scaphoid ligament. These two ligaments are often regarded as a single bifur- 
 cated ligament (ligamentum bijurcatum). The internal calcaneo-cuboid liga- 
 ment is inserted into the inner side of the cuboid bone. This ligament forms 
 one of the chief bonds of union between the first and second rows of the tarsus. 
 
 The Long Calcaneo-cuboid or Long Plantar or Superficial Long Plantar Ligament 
 (ligamentum plantar e longum) (Fig. 254), the more superficial of the two plantar 
 ligaments, is the longest of all the ligaments of the tarsus : it is attached to 
 the under surface of the os calcis, from near the tuberosities, as far forward as 
 the anterior tubercle; its fibres pass forward to be attached to the ridge on the 
 under surface of the cuboid bone, the more superficial fibres being continued 
 onward to the bases of the second, third, and fourth metatarsal bones. This 
 ligament crosses the groove on the under surface of the cuboid bone, converting 
 it into a canal for the passage of the tendon of the Peroneus longus. 
 
 The Short Calcaneo-cuboid or Short Plantar Ligament {ligamentum calcaneo- 
 cuhoideum plantare) (Fig. 254) lies nearer the bones than the preceding, from 
 which it is separated by a little areolar tissue. It is exceedingly broad, about 
 an inch in length, and extends from the tubercle and the depression in front of 
 it, on the forepart of the under surface of the os calcis, to the inferior surface of 
 the cuboid bone behind the peroneal groove. 
 
 Synovial Membrane (Fig. 255). — The synovial membrane in this joint is distinct. 
 It lines the inner surface of the ligaments. 
 
 Actions. — The movements permitted between the os calcis and cuboid are 
 limited to a slight gliding upon each other. 
 
 3. The Ligaments Connecting the Os Calcis and Scaphoid or the 
 Calcaneo-scaphoid Articulation Ijgaments. 
 
 Though these two bones do not directly articulate, they are connected together 
 by two ligaments: 
 
 Superior or External Calcaneo-scaphoid. 
 Inferior or Internal Calcaneo-scaphoid. 
 
 The Superior or External Calcaneo-scaphoid or Calcaneo -navicular {pars cal- 
 caneonavicular is ligamenti bifurcati) arises, as already mentioned, with the 
 internal calcaneo-cuboid in the deep hollow between the astragalus and os calcis, 
 
 23 
 
354 
 
 THE ARTICULATIONS OR JOINTS 
 
 constituting a part of the ligamentum bifurcatum ; it passes forward from the 
 upper surface of the anterior extremity of the os calcis to the outer side of the 
 scaphoid bone. These two hgaments resemble the letter Y, being blended together 
 behind, but separated in front. 
 
 The Inferior or Internal Oalcaneo-scaphoid or Galcaneo-navicular (ligamentum 
 calcaneonavicular e plantarc) (Fig. 254) is by far the larger and stronger of the two 
 ligaments between these bones; it is a broad and thick band of fibres, which 
 
 passes forward and inward from the anterior 
 margin of the sustentaculum tali of the os 
 calcis to the under surface of the scaphoid 
 bone. This ligament not only serves to 
 connect the os calcis and scaphoid, but sup- 
 ports the head of the astragalus, forming 
 part of the articular cavity in which it is 
 received. The upper surface presents a 
 fibro-cartilaginous facet, lined by the syn- 
 ovial membrane continued from the ante- 
 rior calcaneo-astragaloid articulation, upon 
 which a portion of the head of the astragalus 
 rests. Its under surface is in contact with 
 the tendon of the Tibialis posticus muscle;^ 
 its inner border is blended with the forepart 
 of the Deltoid ligament, thus completing 
 the socket for the head of the astragalus. 
 
 Surgical Anatomy. — The inferior calcaneo- 
 scaphoid ligament, by supporting the head of the 
 astragalus, is principally concerned in maintaining 
 the arch of the foot, and when it yields the head of 
 the astragalus is pressed downward, inward, and 
 forward by the weight of the body, and the foot 
 becomes flattened, expanded, and turned outward, 
 constituting the disease known as flat-foot. This 
 ligament contains a considerable amount of elastic 
 fibre, so as to give elasticity to the arch and spring to 
 the foot; hence it is sometimes called the "spring" 
 ligament. It is supported, on its under surface, by 
 the tendon of the Tibialis posticus, which spreads 
 out at its insertion into a number of fasciculi which 
 are attached to most of the tarsal and metatarsal 
 bones; this prevents undue stretching of the ligament 
 and is a protection against the occurrence of fiat-foot. 
 
 Fig. 254. 
 
 -Ligaments of the plantar surface 
 of the foot. 
 
 4. Articulation of the Astragalus with the Scaphoid Bone or the 
 
 ASTRAGALO-SCAPHOID ARTICULATION (ArTICULATIO TaLONAVICULARIS) 
 
 (Fig. 251). 
 The articulation between the astragalus and scaphoid is an arthrodial joint: 
 the rounded head of the astragalus being received into the concavity formed by 
 the posterior surface of the scaphoid, the anterior articulating surface of the 
 calcaneum, and the upper surface of the inferior calcaneo-scaphoid ligament, 
 which fills up the triangular interval between these bones. The only ligament of 
 this joint is the superior astragalo-scaphoid (Fig. 249). It is a broad band, 
 which passes obliquely forward from the neck of the astragalus to the superior 
 surface of the scaphoid bone. It is thin, and weak in texture, and covered by the 
 Extensor tendons. The inferior calcaneo-scaphoid ligament supplies the place of 
 an inferior astragalo-scaphoid ligament. 
 
 1 Mr. Hancock describes an extension of this ligament upward on the inner side of the foot, which completes 
 the socket of the joint in that direction (Lancet, 1866, vol. i. p. 618). 
 
ARTICULATIONS OF THE TARSUS 355 
 
 Synovial Membrane (Fig. 255) . — The synovial membrane which lines the joint 
 is continued forward from the anterior calcaneo-astragaloid articulation. 
 
 Actions. — This articulation permits of considerable mobility, but its feebleness 
 is such as to allow occasionally of dislocation of the other bones of the tarsus 
 from the astragalus. 
 
 The transverse tarsal or medio-tarsal joint [articulatio tarsi transversa [Choparti]) 
 (Figs. 251 and 256) is formed by the articulation of the os calcis with the cuboid, 
 and by the articulation of the astragalus with the scaphoid. The movement which 
 takes place in this joint is more extensive than that in the other tarsal joints, and 
 consists of a sort of rotation by means of which the sole of the foot may be 
 slightly flexed and extended or carried inward (inverted) and outward (everted). 
 
 5. The Articulation of the Scaphoid with the Cuneiform Bones 
 (Articulatio Cuneonavicularis) (Fig. 251). 
 
 The scaphoid is connected to the three cuneiform bones by 
 Dorsal and Plantar ligaments. 
 
 The Dorsal Ligaments {ligamenta navicular icuneiformia dorsalia) (Figs. 249 and 
 251) are s^nall, longitudinal bands of fibrous tissue arranged as three bundles, one 
 to each of the cuneiform bones. That bundle of fibres which connects the scaphoid 
 with the internal cuneiform is continued round the inner side of the articulation to 
 be continuous with the plantar ligament which connects these two bones. 
 
 The Plantar Ligaments (ligamenta navicularicuneiforrnia plantaria) (Fig. 254) 
 have a similar arrangement to those on the dorsum. They are strengthened by 
 processes given off from the tendon of the Tibialis posticus. 
 
 Synovial Membrane (Fig. 255). — The synovial membrane of these joints is 
 part of the great tarsal synovial membrane. 
 
 Actions. — The movements permitted between the scaphoid and cuneiform 
 bones are limited to a slight gliding upon each other. 
 
 6. The Articulation of the Scaphoid with the Cuboid (Articulatio 
 
 Cubonavicularis) . 
 
 The scaphoid bone is connected with the cuboid by 
 
 Dorsal, Plantar, and Interosseous ligaments. 
 
 The Dorsal Ligament (ligamentum cuboideonaviculare dorsale) (Fig. 252) con- 
 sists of a band of fibrous tissue which passes obliquely forward and outward 
 from the scaphoid to the cuboid bone. 
 
 The Plantar Ligament (ligamentum cuboideonaviculare. plantare) consists of a 
 band of fibrous tissue which passes nearly transversely between these two bones. 
 
 The Interosseous Ligament (Figs. 251 and 255) consists of strong transverse 
 fibres which pass between the rough non-articular portions of the lateral sur- 
 faces of these two bones. 
 
 Synovial Membrane (Fig. 255). — The synovial membrane of this joint is part 
 of the great tarsal synovial membrane. 
 
 Actions. — The movements permitted between the scaphoid and cuboid bones 
 are limited to a slight gliding upon each other. 
 
 7. The Articulations of the Cuneiform Bones with Each Other or 
 THE Intercuneiform Articulations (Fig. 251). 
 
 These bones are connected together by 
 
 Dorsal, Plantar, and Interosseous ligaments. 
 
356 
 
 THE ARTICULATIONS OB JOINTS 
 
 The Dorsal Ligaments (ligamenta inter cuneiformia dorsalia) consist of two bands 
 of fibrous tissue which pass transversely, one connecting the internal with the 
 middle cuneiform, and the other connecting the middle with the external cunei- 
 form. 
 
 The Plantar Ligaments (ligamenta intercuneijormia 'plantaria) have a similar 
 arrangement to those oh the dorsum. They are strengthened by the processes 
 given off from the tendon of the TibiaUs posticus. 
 
 The Interosseous Ligaments {ligamenta intercuneijormia interossea) consist of 
 strong transverse fibres which pass between the rough non-articular portions of 
 the lateral surfaces of the first and second and the second and third cuneiform 
 bones. The outer portion of the third cuneiform is attached to the cuboid by 
 the ligamentum cuneocuboideum interosseum. 
 
 Synovial Membrane (Fig. 255). — ^The synovial membrane of these joints is part 
 of the great tarsal synovial membrane. 
 
 Actions. — The movements permitted between the cuneiform bones are limited 
 to a slight gliding upon each other. 
 
 8. The Articulation of the External Cuneiform Bone with the 
 
 Cuboid (Fig. 251). 
 
 These bones are connected together by 
 
 Dorsal, Plantar, and Interosseous ligaments. 
 
 The Dorsal Ligament {ligamentum cuneocuboideum dorsale) (Fig. 252) consists 
 of a band of fibrous tissue which passes transversely between these two bones. 
 
 The Plantar Ligament (ligamentum cuneocuboideum plantare) has a similar 
 arrangement. It is strengthened by a process given off from the tendon of the 
 Tibialis posticus. 
 
 The Interosseous Ligament (ligamentum cuneocuboideum interosseum) (Fig. 251) 
 consists of strong transverse fibres which pass between the rough non-articular 
 portions of the lateral surfaces of the adjacent sides of these two bones. 
 
 Sjmovial Membrane (Fig. 255). — The synovial membrane of this joint is part 
 of the great tarsal synovial membrane. 
 
 Actions. — The movements permitted between the external cuneiform and 
 cuboid are limited to a slight gliding upon each other. 
 
 Nerve-supply. — All the joints of the tarsus are supplied by the anterior tibial 
 nerve. 
 
 Surgical Anatomy. — In spite of the great strength of the ligaments which connect the tarsal 
 bones together, dislocation at some of the tarsal joints does occasionally occur; though, on 
 account of the spongy character of the bones, they are more frequently broken than dislocated, 
 as the result of violence. When dislocation does occur, it is most commonly in connection with 
 the astragalus; for not only may this bone be dislocated from the tibia and fibula at the ankle- 
 joint, but the other bones may be dislocated from it, the trochlear surface of the bone remaining 
 in situ in the tibio-fibular mortise. This constitutes what is known as the subastragaloid dis- 
 location. Or, again, the astragalus may be dislocated from all its connections — from the tibia 
 and fibula above, the os calcis below, and the scaphoid in front — and may even undergo a 
 rotation, either on a vertical or horizontal axis. In the former case the long axis of the bone 
 becoming directed across the joint, so that the head faces the articular surface on one or other 
 malleolus; or, in the latter, the lateral surfaces becoming directed upward and downward, so 
 that the trochlear surface faces to one or the other side. Finally, dislocation may occur at 
 the medio-tarsal joint, the anterior tarsal bones being luxated from the astragalus and cal- 
 caneum. The other tarsal bones are also, occasionally, t)iough rarely, dislocated from their 
 connections. 
 
 Pes planus, flat-foot, or splay-foot is a condition in which there is abduction, eversion, and 
 loss of both the longitudinal and the transverse arch. The head of the astragalus passes down- 
 ward and inward ; the anterior portion of the foot is turned outward and the inner side of the 
 foot is lengthened and broadened. Deformity is increased when standing. In severe cases 
 
TABSO - METATARSAL ARTICULATIONS 357 
 
 the patient walks on the inner side of the foot. The condition is due to yielding of the tarsal 
 ligaments. Abduction is permitted by yielding of the internal lateral and calcaneo-astragaloid 
 ligaments. Yielding of the calcaneo-scaphoid ligament permits the head of the astragalus to pass 
 downward and forward, and the entire arch falls. Further deformity is induced by the yielding 
 of the ligaments. 
 
 VI. Tarso-metatarsal Articulations (Articulationes Tarsometatarseae 
 
 [Lisfranci]) (Figs. 249, 251, 252, 254, 257). 
 
 These are arthrodial joints. The bones entering into their formation are four 
 tarsal bones — viz., the internal, middle, and external cuneiform and the cuboid — 
 which articulate with the metatarsal bones of the five toes. The metatarsal bone 
 of the great toe articulates with the internal cuneiform; that of the second is 
 deeply wedged in between the internal and external cuneiform, resting against the 
 middle cuneiform, and being the most strongly articulated of all the metatarsal 
 bones; the third metatarsal articulates with the extremity of the external cunei- 
 form; the fourth, with the cuboid and external cuneiform; and the fifth, with 
 the cuboid. The articular surfaces are covered with cartilage, lined by 
 synovial membrane, and connected together by capsules and by the following 
 ligaments : 
 
 Dorsal. Plantar. Interosseous. 
 
 The Dorsal Ligaments {ligamenta tarsometatarsea dorsalia) consist of strong, 
 flat, fibrous bands, which connect the tarsal with the metatarsal bones. The 
 first metatarsal is connected to the internal cuneiform by a single broad, thin, 
 fibrous band; the second has three dorsal ligaments, one from each cuneiform 
 bone; the third has one from the external cuneiform; the fourth has two, one 
 from the external cuneiform and one from the cuboid; and the fifth, one from 
 the cuboid. 
 
 The Plantar Ligaments {ligamenta tarsometatarsea plantaria) consist of longi- 
 tudinal and oblique fibrous bands connecting the tarsal and metatarsal bones, 
 but disposed with less regularity than on the dorsal surface. Those for the first 
 and second metatarsal are the most strongly marked ; the second and third meta- 
 tarsal receive strong fibrous bands which pass obliquely across from the internal 
 cuneiform; the plantar ligaments of the fourth and fifth metatarsal consist of a 
 few scanty fibres derived from the cuboid. 
 
 The Interosseous Ligaments (ligamenta cuneomeiatarsea interossea) are three in 
 number— internal, middle, and external. The internal one is the strongest of the 
 three, and passes from the outer extremity of the internal cuneiform to the 
 adjacent angle of the second metatarsal. The middle one, less strong than the 
 preceding, connects the external cuneiform with the adjacent angle of the second 
 metatarsal. The external interosseous ligament connects the outer angle of the 
 external cuneiform with the adjacent side of the third metatarsal. 
 
 Synovial Membrane (Fig. 255). — ^The synovial membrane between the internal 
 cuneiform bone and the first metatarsal bone is a distinct sac. The synovial 
 membrane between the middle and external cuneiform behind, and the second 
 and third metatarsal bones in front, is part of the great tarsal synovial membrane. 
 Two prolongations are sent forward from it — one between the adjacent sides of 
 the second and third metatarsal bones, and one between the third and fourth 
 metatarsal bones. The synovial membrane between the cuboid and the fourth 
 and fifth metatarsal bones is a distinct sac. From it a prolongation is sent for- 
 ward between the fourth and fifth metatarsal bones. 
 
 Actions. — The movements permitted between the tarsal and metatarsal bones 
 are limited to a slight gliding upon each other. 
 
358 
 
 THE ARTICULATIONS OB JOINTS 
 
 VII. Articulations of the Metatarsal Bones with Each Other 
 (Articulationes Intermetatarseae) (Figs. 251, 252, 254). 
 
 The base of the first metatarsal bone is not connected with the second meta- 
 tarsal bone by any ligaments; in this respect it resembles the thumb. 
 
 The bases of the four outer metatarsal bones are connected together by dorsal, 
 plantar, and interosseous ligaments. 
 
 The Dorsal Ligaments (ligamenta hasium \oss. metatarsi] dorsalia) consist of 
 bands of fibrous tissue which pass transversely between the adjacent metatarsal 
 bones. 
 
 The Plantar Ligaments {ligamenta hasium \oss. metatars.] plantaria) have a 
 similar arrangement to those on the dorsum. 
 
 The Interosseous Ligaments (ligamenta basium [oss. metatars.] interossea) con- 
 sist of strong transverse fibres which pass between the rough non-articular portions 
 of the lateral surfaces. 
 
 Synovial Membrane. — The synovial membrane between the second and third 
 and the third and fourth metatarsal bones is part of the great tarsal synovial mem- 
 brane. The synovial membrane between the fourth and fifth metatarsal bones is 
 a prolongation of the synovial membrane of the cubo-metatarsal joint (Fig. 255). 
 
 Actions. — The movement permitted in the tarsal ends of the metatarsal bones 
 is limited to a slight gliding of the articular surfaces upon one another. 
 
 The Synovial Membranes in the Tarsal and Metatarsal Joints. 
 
 The synovial membranes (Fig. 255) found in the articulations of the tarsus 
 and metatarsus are six in number; one for the posterior calcaneo-astragaloid 
 
 Fig. 255. — Oblique section of the articulations of the tarsus and metatarsus. Showing the six synovial 
 
 membranes. 
 
 articulation; a second for the anterior calcaneo-astragaloid and astragalo- 
 scaphoid articulations; a third for the calcaneo-cuboid articulation; and a fourth 
 for the articulations of the scaphoid with the three cuneiform, the three cunei- 
 form with each other, the external cuneiform with the cuboid, and the middle and 
 external cuneiform with the bases of the second and third metatarsal bones, and 
 the lateral surfaces of the second, third, and fourth metatarsal bones with each 
 other; a fifth for the internal cuneiform with the metatarsal bone of the great toe; 
 and a sixth for the articulation of the cuboid with the fourth and fifth metatarsal 
 bones. A small synovial membrane is sometimes found between the contiguous 
 surfaces of the scaphoid and cuboid bones. 
 
ARTICULATIONS OF THE PHALANGES 359 
 
 Nerve-supply. — The nerves supplying the tarso-metatarsal joints are derived 
 from the anterior tibial. 
 
 The digital extremities of all the metatarsal bones are connected together by 
 the transverse metatarsal ligament. 
 
 The Transverse Metatarsal Ligament is a narrow fibrous band which passes 
 transversely across the anterior extremities of all the metatarsal bones, connecting 
 them together. It is blended anteriorly with the plantar {glenoid) ligament of 
 each metatarso-phalangeal articulation. To its posterior border is connected the 
 fascia covering the Interossei muscles. Its inferior surface is concave where the 
 Flexor tendons pass over it. Above it the tendons of the Interossei muscles pass 
 to their insertion. It differs from the transverse metacarpal ligament in that it 
 connects the metatarsal bone of the great toe with the rest of the metatarsal bones. 
 
 VIII. Metatarso-phalangeal Articulations (Articulationes Metatarso- 
 
 phalangeae). 
 
 The metatarso-phalangeal articulations are of the condyloid kind, formed by 
 the reception of the rounded head of the metatarsal bone into a superficial cavity 
 in the extremity of the first phalanx. Each joint has a capsule and certain 
 other ligaments. 
 
 These ligaments are — 
 
 Plantar. Two I^ateral. 
 
 The Plantar Ligaments or the Glenoid Ligaments of Cruveilhier (ligamenta 
 accessoria plaTitaria) are thick, dense, fibrous structures. Each is placed on 
 the plantar surface of the joint in the interval between the lateral ligaments, 
 to which it is connected. The plantar ligaments are loosely united to the meta- 
 tarsal bones, but very firmly to the bases of the first phalanges. The plantar 
 surface of each is intimately blended with the transverse metatarsal ligament, 
 and, except in the great toe, presents a groove for the passage of the Flexor 
 tendons, the sheath surrounding which is connected to each side of the groove. 
 The plantar ligament of the great toe contains two large sesamoid bones. By 
 their deep surface they form part of the articular surface for the head of the 
 metatarsal bone, and are lined by synovial membrane. 
 
 The Lateral Ligaments (ligamenta collaieralia) are strong, rounded cords, placed 
 one on each side of the joint, each being attached, by one extremity, to the poste- 
 rior tubercle on the side of the head of the metatarsal bone; and, by the other, to 
 the contiguous extremity of the phalanx. 
 
 The place of a Posterior Ligament is supplied by the extensor tendon over the 
 back of the joint. 
 
 Actions. — The movements permitted in the metatarso-phalangeal articulations 
 are flexion, extension, abduction, and adduction. 
 
 IX. Articulations of the Phalanges (Articulationes Digitorum Pedis). 
 
 The articulations of the phalanges are ginglymoid joints. Besides the cap- 
 sular the ligaments are — 
 
 Plantar. Two Lateral (ligamenta collateralia) . 
 
 The arrangement of these ligaments is similar to those in the metatarso-phalan- 
 geal articulations; the extensor tendon supplies the place of a posterior ligament. 
 
 Actions. — The only movements permitted in the phalangeal joints are flexion 
 and extension; these movements are more extensive between the first and second 
 phalanges than between the second and third. The movement of flexion is very 
 considerable, but extension is limited by the plantar and lateral ligaments. 
 
3G0 THE ARTICULATIONS OB JOINTS 
 
 Surface Form. — The principal joints which it is necessary to distinguish, with regard to 
 the surgery of the foot, are the medio-tarsal and the tarso-metatarsal. The joint between the 
 astragalus and the scaphoid is best found by means of the tubercle of the scaphoid, for 
 the line of the joint is immediately behind this process. If the foot is grasped and forcibly 
 extended, a rounded prominence, the head of the astragalus, will appear on the inner side of 
 the dorsum in front of the ankle-joint, and if a knife is carried downward, just in front of this 
 prominence and behind the line of the scaphoid tubercle, it will enter the astragalo-scaphoid 
 joint. The calcaneo-cuboid joint is situated midway between the external malleolus and the 
 prominent end of the fifth metatarsal bone. The plane of the joint is in the same line as that 
 of the astragalo-scaphoid. The position of the joint between the fifth metatarsal bone and the 
 cuboid is easily found by the projection of the fifth metatarsal bone, which is the guide to it. 
 The direction of the line of the joint is very oblique, so that, if continued onward, it would 
 pass through the head of the first metatarsal bone. The joint between the fourth metatarsal 
 bone and the cuboid and external cuneiform is the direct continuation inward of the previous 
 joint, but its plane is less oblique; it would be represented by a line drawn from the outer side 
 of the articulation to the middle of the first metatarsal bone. The plane of the joint between 
 the third metatarsal bone and the external cuneiform is almost transverse. It would be repre- 
 
 FIFTH 
 
 OS CALCIS-f- \ iK METATARSAL i ft^j^ I / / CUNEIFORM 
 
 EXTERNAL 
 
 FIRST 
 METATARSAL 
 
 Fig. 256. — Line of Chopart's amputation. Fig. 257. — Line of Lisfranc's amputation. 
 
 (Poirier.) (Poirier.) 
 
 sented by a line drawn from the outer side of the joint to the base of the first metatarsal bone. 
 The tarso-metatarsal articulation of the great toe corresponds to a groove which can be felt by 
 making firm pressure on the inner side of the foot one inch in front of the tubercle on the 
 scaphoid bone; and the joint between the second metatarsal bone and the middle cuneiform is 
 to be found on the dorsum of the foot, half an inch behind the level of the tarso-metatarsal joint 
 of the great toe. The line of the joints between the metatarsal bones and the first phalanges 
 is about an inch behind the webs of the corresponding toes. 
 
 Surgical Anatomy. — Chopart's amputation passes through the middle tarsal joint (astragalo- 
 scaphoid and calcaneo-cuboid articulation). Fig. 256 shows the line of Chopart. Lisfranc 
 amputated at the tarso-metatarsal articulation. Fig. 257 shows the line of Lisfranc. In Hey's 
 amputation the fifth, fourth, third, and second metatarsal bones are disarticulated from the 
 tarsus and the internal cuneiform is sawn through. In the operation of Forbes, of Toledo, the 
 cuneiform bones are disarticulated from the scaphoid, the cuboid is sawn through on a line 
 with the surface exposed by the disarticulation. 
 
THE MUSCLES AND FASCU). 
 
 MYOLOGY is the branch of anatomy which treats of the muscles. The 
 muscles are formed of bundles of reddish fibres, endowed with the property 
 of contractility. The two principal kinds of muscular tissue found in the 
 body are voluntary and involiintaxy. The former of these, from the character- 
 istic appearances which its fibres exhibit under the microscope, is known as 
 striated or striped muscle, and from the fact that it is capable of being put into 
 action and controlled by the will, as voluntary muscle. The fibres of the latter 
 do not present any cross-striped appearance, and for the most part are not 
 under the control of the will; hence they are known as unstriated, unstriped, or 
 involuntary muscle. The muscular fibres of the heart differ in certain partic- 
 ulars from both these groups, and they are therefore separately described as 
 cardiac muscular fibres. 
 
 Thus it will be seen that there are three varieties of muscular fibres: (1) 
 Transversely striated muscular fibres, which are for the most part voluntary and 
 under the control of the will, but some of which are not so, such as the muscles 
 of the pharynx and upper part of the oesophagus. This variety of muscle is 
 sometimes called skeletal. (2) Transversely striated muscular fibres, which are 
 not under the control of the will — i. e., the cardiac muscles. (3) Plain or unstriped 
 muscular fibres, which are involuntary and controlled by a different part of the 
 nervous system from that which controls the activity of the voluntary muscles. 
 Such are the muscular walls of the stomach and intestine, of the uterus and bladder, 
 of the blood-vessels, etc. 
 
 In this section we treat of the skeletal or voluntary muscles only. A muscle is 
 composed of numerous long, narrow muscle cells which shorten when stimulated. 
 The wall of a muscle cell is called the sarcolemma. Muscle cells end either by 
 blending with tendon or aponeurosis or else by rounded or tapering extremities, 
 which are connected to neighboring cells by means of the sarcolemma. Each 
 muscle is composed of bundles or fasciculi of cells or fibres. These bundles are 
 connected together by a connective tissue which is known as the epimysium or 
 external perimysium (perimysium externum), and which is continuous with the 
 sheath of the muscle. Each bundle of muscle fibres is surrounded by the internal 
 perimysium (perimysium internum). The internal perimysium joins the external 
 perimysium externally and the sarcolemma, or tubular sheath, of each fibre 
 internally. 
 
 Each muscle cell (fibre) contains numerous nuclei and also fibrillated striated 
 protoplasm. A muscle cell may be 10 cm. in length, and may even extend the 
 entire length of a small muscle (Szymonowicz). The diameter of a cell is from 
 40// to 60//. The striated portion of a cell is differentiated protoplasm, each cell is 
 a portion of unchanged protoplasm (sarcoplasm). In man most muscles are of 
 
 * The Muscles and Fascise are described conjointly, in order that the student may consider the arrangement 
 of the latter in his dissection of the former. It is rare for the student of anatomy in this country to have 
 the opportunity of dissecting the fascia; separately; and it is for this reason, as well as from the close con- 
 nection that exists between the muscles and their investing sheaths, that they are considered together. Some 
 general observations are first made on the histology and anatomy of the muscles and fasciae, the special 
 description being given in connection with the different regions. 
 
 ( 361 ) 
 
362 THE MUSCLES AND FASCIA 
 
 the red type, but some (mixed muscles) contain red and white fibres. A red 
 muscle fibre contains a considerable quantity of sarcoplasm, and the nuclei are 
 toward the centre of the cell; in a white muscle fibre there is less sarcoplasm, the 
 nuclei are toward the periphery, and striation is very distinct/ Striation is due 
 to alteration in the parts of the fibre, so that the altered material has a different 
 refractive index and stains differently from the unaltered portions of the cell. 
 
 The Arteries of voluntary muscles pierce the external perimysium and form 
 superficial and deep plexuses that anastomose with each other. These vessels 
 follow the trabeculse between the bundles. Branches enter the bundles and 
 form capillary plexuses, which here and there possess dilatations for the relief 
 of tension during muscular action. 
 
 Veins accompany the arteries, and even the smaller ones possess valves 
 (Spalteholz). 
 
 The Nerve Endings in voluntary muscle comprise both motor and sensory ter- 
 minations. A motor nerve pierces the external perimysium and breaks up into 
 numerous branches to form an interfascicular plexus in the internal perimysium. 
 From this plexus nerve fibrils arise and usually one nerve fibril passes to each 
 muscle fibre. The nerve fibril pierces the sarcolemma, the neurilemma and 
 medullary sheath disappearing before the nerve fibril reaches the muscle fibre, 
 and probably being lost by fusing with the sarcolemma. The naked axis-cylinder 
 beneath the sarcolemma of a fibre continues to the surface of the muscle fibre and 
 undergoes arborization to form an end organ. Around the end organ is a quantity 
 of granular sarcoplasm, which, with the nerve end organ, constitutes a sole-plate. 
 A sensory nerve takes origin from a muscle spindle, which consists of a bundle 
 of encapsuled muscle fibre about sensory nerve twigs. From a muscle spindle 
 arise from two to eight large medullated nerve fibres. 
 
 The muscles are connected with the bones, cartilages, ligaments, and skin, 
 either directly or through the intervention of fibrous structures called tendons 
 or aponeuroses. Where a muscle is attached to bone or cartilage, the fibres ter- 
 minate in blunt extremities upon the periosteum or perichondrium, and do not 
 come into direct relation with the osseous or cartilaginous tissue. Where muscles 
 are connected with the skin, they either lie as a flattened layer beneath it, or are 
 connected with its areolar tissue by larger or smaller bundles of fibres, as in the 
 muscles of the face. The direct continuation of the tendon of a muscle is known 
 as the belly or venter. The origin of a muscle is its head (caput). 
 
 The muscles vary extremely in their form. In the limbs they are of consid- 
 erable length, especially the more superficial ones, the deep ones being generally 
 broad; they surround the bones and form an important protection to the various 
 joints. In the trunk they are broad, flattened, and expanded, forming the parietes 
 of the cavities which they enclose; hence the reason of the terms long, broad, 
 short, etc., used in the description of a muscle. 
 
 There is a considerable variation in the arrangement of the fibres of certain 
 muscles with reference to the tendons to which they are attached. In some, the 
 fibres are parallel and run directly from their origin to their insertion; these are 
 quadrilateral muscles, such as the Thyro-hyoid. A modification of these is found in 
 the fusiform muscles {m. fusiformis), in which the fibres are not quite parallel, but 
 slightly curved, so that the muscle tapers at each end; in their action, however, they 
 resemble the quadrilateral muscles. Secondly, in other muscles the fibres are con- 
 vergent; arising by a broad origin, they converge to a narrow or pointed insertion. 
 This arrangement of fibres is found in the triangular muscles — e. g., the Temporal. 
 In some muscles, which otherwise would belong to the quadrilateral or triangular 
 type, the origin and insertion are not in the same plane, but the plane of the line 
 
 ^ A Text-book of Histology. By Dr. Ladislaus Szymonowicz. Translated and edited by Dr. John Bruce 
 MacCallum. 
 
APONEUROSES 363 
 
 of origin intersects that of their insertion; such is the case in the Pectineus muscle. 
 Thirdly, in some muscles the fibres are oblique and converge, like the plumes 
 of a pen, to one side of a tendon, which runs the entire length of the muscle. 
 Such a muscle is rhomboidal or penniform im. unipennatus) , as the Peronei. A 
 modification of these rhomboidal muscles is found in those cases where oblique 
 fibres converge to both sides of a central tendon which runs down the middle of 
 the muscle; these are called bipenniform (m. bipennatus) , and an example is afforded 
 in the Rectus femoris. Finally, we have muscles in which the fibres are arranged 
 in curved bimdles in one or more planes, as in an orbicular muscle (m. orbicularis) 
 and in that variety of orbicular muscle called a sphincter muscle (m. sphincter). 
 The arrangement of the muscular fibres is of considerable importance in respect 
 to their relative strength and range of movement. Those muscles where the 
 fibres are long and few in number have great range, but diminished strength; 
 where, on the other hand, the fibres are short and more numerous, there is 
 great power, but lessened range. 
 
 Muscles differ much in size: the Gastrocnemius forms the chief bulk of the 
 back of the leg, and the fibres of the Sartorius are nearly two feet in length, whilst 
 the Stapedius, a small muscle of the internal ear, weighs about a grain, and its 
 fibres are not more than two lines in length. 
 
 The names applied to the various muscles have been derived — 1, from their 
 situation, as the Tibialis, Radialis, Ulnaris, Peroneus; 2, from their direction, as 
 the Rectus abdominis, Obliquus capitis, Transversalis; 3, from their uses, as Flexors, 
 Extensors, Abductors, etc. ; 4, from their shape, as the Deltoid, Trapezius, Rhom- 
 boideus; 5, from the number of their divisions, as the Biceps, the Triceps; 6, 
 from their points of attachment, as the Sterno-cleido-mastoid, Sterno-hyoid, 
 Sterno-thyroid. 
 
 In the description of a muscle the term origin is meant to imply its more fixed 
 or central attachment, and the term insertion, the movable point to which the 
 force of the muscle is directed; but the origin is absolutely fixed in only a very 
 small number of muscles, such as those of the face, which are attached by one 
 extremity to the bone and by the other to the movable integument; the greater 
 number of muscles can be made to act from either extremity. 
 
 In the dissection of the muscles the student should pay especial attention to 
 the exact origin, insertion, and actions of each, and its more important relations 
 with surrounding parts. An accurate knowledge of the points of attachment of 
 the muscles is of great importance in the determination of their action. By a 
 knowledge of the action of the muscles the surgeon is able to explain the causes 
 of displacement in various forms of fracture and the causes which produce dis- 
 tortion in various deformities, and, consequently, to adopt appropriate treatment 
 in each case. The relations, also, of some of the muscles, especially those in 
 immediate apposition with the larger blood-vessels, and the surface-markings they 
 produce, should be especially remembered, as they form useful guides to the 
 surgeon who operates to expose and ligate them. 
 
 Tendons. — Tendons are white, glistening, fibrous cords, varying in length and 
 thickness, sometimes round, sometimes flattened, of considerable strength, and 
 devoid of elasticity. They consist almost entirely of white fibrous tissue, the fibrils 
 of which have an undulating course parallel with each other and are firmly united 
 together. They are very sparingly supplied with blood-vessels, the smaller ten- 
 dons presenting in their interior not a trace of them. Nerves also are not present 
 in the smaller tendons, but the larger ones, as the tendo Achillis, receive nerves 
 which accompany nutrient vessels. The tendons consist principally of a sub- 
 stance w'hich yields gelatin. 
 
 Aponeuroses. — Aponeuroses are flattened or ribbon-shaped tendons, of a 
 pearly-white color, iridescent, glistening, and similar in structure to the tendons. 
 
364 
 
 THE MUSCLES AND FASCIJE 
 
 They are destitute of nerves, and the thicker ones are only sparingly supplied 
 with blood-vessels. 
 
 The tendons and aponeuroses are connected, on the one hand, with the mus- 
 cles, and, on the other hand, with movable structures, as the bones, cartilages, 
 ligaments, fibrous membranes (for instance, the sclerotic). Where the muscular 
 fibres are in a direct line with those of the tendon or aponeurosis, the two are 
 directly continuous, the muscular fibre being distinguishable from that of the 
 tendon only by its striation. But where the muscular fibres join the tendon or 
 aponeurosis at an oblique angle the former terminate, according to Kolliker, in 
 rounded extremities, which are received into corresponding depressions on the 
 surface of the latter, the connective tissue between the fibres being continuous 
 with that of the tendon. The latter mode of attachment occurs in all the penni- 
 form and bipenniform muscles, and in those muscles the tendons of which com- 
 mence in a membranous form, as the Gastrocnemius and Soleus. 
 
 Fasciae. — The fasciae {fascia, a bandage) are fibro-areolar or aponeurotic 
 laminae of variable thickness and strength, found in all regions of the body, 
 investing the softer and more delicate organs. The fasciae have been sub- 
 divided, from the situation in which they are found, into two groups, superficial 
 and deep. 
 
 Superficial Fascia (panniculus adiposus). — The superficial fascia is found imme- 
 diately beneath the integument over almost the entire surface of the body. It 
 connects the skin with the deep or aponeurotic fascia, and consists of fibro-areolar 
 tissue, containing in its meshes pellicles of fat in varying quantity. In the eyelids 
 and scrotum, where adipose tissue is rarely deposited, this tissue is very liable -to 
 serous infiltration. The superficial fascia varies in thickness in different parts 
 of the body: in the groin it is so thick as to be capable of being subdivided in 
 several laminae. Beneath the fatty layer of the superficial fascia, which is imme- 
 diately subcutaneous, there is generally another layer of the same structure, com- 
 paratively devoid of adipose tissue, in which the trunks of the subcutaneous vessels 
 and nerves are found, as the superficial epigastric vessels in the abdominal region, 
 the radial and ulnar veins in the forearm, the saphenous veins in the leg and 
 thigh, and the superficial lymphatic glands; certain cutaneous muscles also are 
 situated in the superficial fascia, as the Platysma myoides in the neck, and the 
 Orbicularis palpebrarum around the eyelids. This fascia is most distinct at the 
 lower part of the abdomen, the scrotum, perinaeum, and extremities; is very thin 
 in those regions where muscular fibres are inserted into the integument, as on 
 the side of the neck, the face, and around the margin of the anus. It is very 
 dense in the scalp, in the palms of the hands and soles of the feet, forming a fibro- 
 fatty layer which binds the integument firmly to the subjacent structure. The 
 superficial fascia connects the skin to the subjacent parts, facilitates the move- 
 ment of the skin, serves as a soft medium for the passage of vessels and nerves 
 to the integument, and retains the warmth of the body, since the fat contained in 
 its areolae is a bad conductor of heat. 
 
 Deep Fascia. — The deep or aponeurotic fascia is a dense, inelastic, unyielding 
 fibrous membrane, forming sheaths for the muscles and affording them broad 
 surfaces for attachment. It consists of shining tendinous fibres, placed parallel 
 with one another, and connected together by other fibres disposed in a rectilinear 
 manner. It is usually exposed on the removal of the superficial fascia, forming a 
 strong investment, which not only binds down collectively the muscles in each 
 region, but gives a separate sheath to each, as well as to the vessels and nerves. 
 The fasciae are thick in unprotected situations, as on the outer side of a limb, and 
 thinner on the inner side. The deep fasciae assist the muscles in their action by 
 the degree of tension and pressure they make upon their surface; and in certain 
 situations this is increased and regulated by muscular action; as, for instance, by 
 
MUSCLES AND FASCIJS OF THE CRANIUM AND FACE 365 
 
 the Tensor fasciae femoris and Gluteus maximus in the thigh, by the Biceps in 
 the upper and lower extremities, and Palmaris longus in the hand. In the limbs 
 the fasciae not only invest the entire limb, but give off septa which separate the 
 various muscles, and are attached beneath to the periosteum : these prolongations 
 of fasciae are usually spoken of as intermuscular septa. 
 
 The Muscles and Fasciae may be arranged, according to the general division 
 of the body, into those of the cranium, face, and neck; those of the trunk; those of 
 the upper extremity; and those of the lower extremity. 
 
 MUSCLES AND FASCI-ffi OF THE CRANIUM AND FACE. 
 
 The muscles of the cranium and face consist of ten groups, arranged according 
 to the region in which they are situated: 
 
 1. Cranial Region. 
 
 2. Auricular Region. 
 
 3. Palpebral Region. 
 
 4. Orbital Region. 
 
 5. Nasal Region 
 
 6. Maxillary Region. 
 
 7. Mandibular Region. 
 
 8. Intermaxillary Region. 
 
 9. Temporo-mandibular Region. 
 10. Pterygo-mandibular Region. 
 
 The muscles contained in each of these groups are the following: 
 
 1. Cranial Region. 
 Occipito-frontalis. 
 
 2. Auricular Region. 
 
 Attrahens auriculam. 
 AttoUens auriculam. 
 Retrahens auriculam. 
 
 3. Palpebral Region. 
 
 Orbicularis palpebrarum. 
 Corrugator supercilii. 
 Tensor tarsi. 
 
 4. Orbital Region. 
 
 Levator palpebrae. 
 Rectus superior. 
 Rectus inferior. 
 Rectus internus. 
 Rectus externus. 
 Obliquus superior. 
 Obliquus inferior. 
 
 5. Nasal Region. 
 
 Pyramidalis nasi. 
 
 Levator labii superioris alseque 
 
 nasi. 
 Dilatator naris posterior. 
 Dilatator naris anterior. 
 Compressor nasi. 
 Compressor narium minor. 
 Depressor alae nasi. 
 
 6. Maxillary Region. 
 
 Levator labii superioris. 
 Levator anguli oris. 
 Zygomaticus major. 
 Zygomaticus minor. 
 
 7. Mandibular Region. 
 
 I^evator labii inferioris. 
 Depressor labii inferioris. 
 Depressor anguli oris. 
 
 8. Intermaxillary Region. 
 
 Buccinator. 
 Risorius. 
 Orbicularis oris. 
 
 9. Temporo-mandibular Region. 
 
 Masseter. 
 Temporal. 
 
 10. Pterygo-mandibular Region. 
 
 Pterygoideus externus. 
 Pterygoideus internus. 
 
366 
 
 THE MUSCLES AND FASCIuE 
 
 1. The Cranial Region. 
 
 Occipito-frontalis. 
 
 Dissection (Fig. 258). — The head being shaved, and a block placed beneath the back of 
 the neck, make a vertical incision through the skin from before backward, commencing at 
 
 1. Dissection of scalp. 
 
 2, S, of auricular region. 
 4, 5, 6, of face. 
 
 7, 8, of neck. 
 
 Fig. 258. — Dissection of the head, face, and neck. 
 
 the root of the nose in front, and terminating behind at the occipital protuberance; make a 
 second incision in a horizontal direction along the forehead and round the side of the head, 
 from the anterior to the posterior extremity of the preceding. Raise the skin in front, from 
 the subjacent muscle, from below upward; this must be done with extreme care, removing 
 the integument from the outer surface of the vessels and the nerves which lie immediately 
 beneath the skin. 
 
 The Skin of the Scalp. — This is thicker than in any other part of tlie body. It 
 is intimately adherent to the superficial fascia, which attaches it firmly to the 
 underlying aponeurosis and muscle. Movements of the muscle move the skin. 
 The hair-follicles are very closely set together, and extend throughout the whole 
 thickness of the skin. It also contains a number of sebaceous glands. 
 
 SUBCUTANEOUS ADI- 
 POSE TISSUE 
 
 APONEUROSIS OF 
 CC I PITO- FRONTALIS 
 
 MUSCLE 
 
 OCCIPITO-FRONTALIS 
 MUSCLE 
 
 BAPONEUROTIC 
 SUE 
 
 PERIOSTEUM 
 
 OCCIPITO-FRONTALIS 
 MUSCLE 
 
 Fig. 259. — Epicranial aponeurosis. Antero-posterior section. (Schematic.) (Poirier and Charpy.) 
 
 Superficial Fascia. — The superficial fascia in the cranial region is a firm, 
 dense, fibro-fatty layer, intimately adherent to the integument, and to the occipito- 
 frontalis and its tendinous aponeurosis; it is continuous, behind, with the super- 
 
THE CRANIAL REGION 
 
 367 
 
 ficial fascia at the back part of the neck; and, laterally, is continued over the 
 temporal fascia. It contains between its layers the superficial vessels and nerves 
 and much granular fat. 
 
 Surgical Anatomy. — The subcutaneous tissue is composed of bands of fibrous tissue enclos- 
 ing spaces filled with fat. The fibrous character of this tissue greatly limits discoloration and 
 swelling when inflammation occurs. The edges of a wound which does not involve the apon- 
 eurosis or muscle do not retract, hence the wound does not gap. The blood-vessels run practi- 
 cally in the skin, and as they lie in very dense tissue and are adherent to it, wounds bleed 
 profusely, the arteries being unable to freely contract and retract. It is very difficult or 
 impossible to pick up with forceps a vessel in the skin of the .scalp, and bleeding must be 
 arrested by suture ligatures or by the stitches which close the wound. Sebaceous glands in 
 the skin of the scalp may develop into sebaceous cysts (wens). 
 
 The Occipito-frontalis {m. epicranms) (Fig. 260).— The Occipito-frontalis 
 is a broad musculo-fibrous laver, which covers the whole of one side of the 
 
 CORRUQATOR SUPERCILM 
 
 DILATATOR NAHIS ANTERIOR 
 
 DILATATOR MARIS POSTERIOR 
 
 COMPRESSOR NARIUM MINOR 
 
 DEPRESSOR AL/C NASI. 
 
 LEVATOR MENTI 
 
 Fio. 260. — Muscles of the head, face, and neck. 
 
368 THE MUSCLES AND FASCIA 
 
 vertex of the skull, from the occiput to the eyebrow. It consists of two mus- 
 cular shps, separated by an intervening tendinous aponeurosis. The occipital 
 portion, the occipitalis muscle {m. occipitalis), is thin, quadrilateral in form, and 
 about an inch and a half in length; it arises from the outer two-thirds of the 
 superior curved line of the occipital bone, and from the mastoid portion of the 
 temporal bone. Its fibres of origin are tendinous, but they soon become muscular, 
 and ascend in a parallel direction to terminate in a tendinous aponeurosis. The 
 frontal portion, the frontalis muscle {m. frontalis), is thin, of a quadrilateral 
 form, and intimately adherent to the superficial fascia. It is broader, its fibres 
 are longer, and their structure paler than the occipital portion. Its internal 
 fibres are continuous with those of the PyramidaHs nasi. Some anatomists con- 
 sider the Pyramidalis muscle as simply the lower fibres of the frontalis, and 
 give these bundles of muscle fibre the name of musculus procerus. Its middle 
 fibres become blended with the Corrugator supercilii and Orbicularis palpebra- 
 rum; and the outer fibres are also blended with the latter muscle over the external 
 angular process. According to Theile, the innermost fibres are attached to the 
 nasal bones, the outer to the external angular process of the frontal bone. From 
 these attachments the fibres are directed upward, and join the aponeurosis below 
 the coronal suture. The inner margins of the frontal portions of the two muscles 
 are joined together for some distance above the root of the nose; but between the 
 occipital portions there is a considerable, though variable, interval, which is occu- 
 pied by the aponeurosis. 
 
 The middle portion of the Occipito-frontalis muscle or the aponeurosis (epi- 
 cranial aponeurosis, Galea aponeurotica) covers the upper part of .the vertex 
 of the skull, being continuous across the middle line with the aponeurosis of the 
 opposite muscle. Behind, it is attached, in the interval between the occipital 
 origins, to the occipital protuberance and highest curved lines of the occipital 
 bone; in front, it forms a short and narrow prolongation between the frontal por- 
 tions; and on each side it has connected with it the Attollens and Attrahens 
 auriculam muscles. This aponeurosis is closely connected to the integument by 
 the firm, dense, fibro-fatty layer which forms the superficial fascia; it is connected 
 with the pericranium by loose cellular tissue, which allows of a considerable 
 degree of movement of the integument. It is continuous with the temporal 
 fascia below the temporal ridge, and it is in reality the representative of the 
 deep fascia. 
 
 Nerves. — The frontal portion of the Occipito-frontalis is supplied by the facial 
 nerve; its occipital portion by the posterior auricular branch of the facial. 
 
 Actions. — The frontal portion of the muscle raises the eyebrows and the skin 
 over the root of the nose, and at the same time draws the scalp forward, throwing 
 the integument of the forehead into transverse wrinkles. The posterior portion 
 draws the scalp backward. By bringing alternately into action the frontal and 
 occipital portions the entire scalp may be moved forward and backward. In the 
 ordinary action of the muscles, the eyebrows are elevated, and at the same time 
 the aponeurosis is fixed by the posterior portion, thus giving to the face the 
 expression of surprise: if the action is more exaggerated, the eyebrows are still 
 further raised, and the skin of the forehead thrown into transverse wrinkles, as in 
 the expression of fright or horror. 
 
 Surgical Anatomy.— The skull is covered by the scalp (Fig. 259). This consists of five layers: 
 (1) the pericranium; (2) a layer of connective tissue beneath the Occipito-frontalis aponeurosis 
 (subaponeurotic tissue) ; (3) the Occipito-frontalis muscle and aponeurosis; (4) subcutaneous fat; 
 (5) skin. If a wound involves the muscle or aponeurosis, it gaps widely, the greatest amount 
 of gaping being observed in transverse wounds. The space between the aponeurosis and the 
 pericranium is called by Treves the dangerous area of the scalp. It contains a layer of con- 
 nective tissue and suppuration in this tissue spreads widely. An abscess in the dangerous area 
 
THE AURICULAR REGION 369 
 
 should be opened above the superior curved line of the occipital bone, above the eyebrow 
 or above the zygoma. In a wound or contusion above the aponeurosis but little blood can be, 
 effused in the tissue because the fibrous structure prevents it, and abscesses do not tend to 
 spread widely. Between the aponeurosis and the pericranium a great amount of blood can be 
 effused. An effusion of blood beneath the pericranium is called a cephalhcematoma. Such 
 a condition may occur from pressure during birth. An extravasation beneath the pericranium 
 is limited to the surface of one bone. The pericranium is tightly attached to the sutures, but 
 adheres lightly to the surface of the bone, and abscess beneath the pericranium is restricted 
 to the surface of one bone. 
 
 2. The Auricular Region (Fig. 260). 
 
 Attrahens auriculam. AttoUens auriculam. 
 
 Retrahens auriculam. 
 
 These three small muscles are placed immediately beneath the skin around the 
 external ear. In man, in whom the external ear is almost immovable, they are 
 rudimentary. They are the analogues of large and important muscles in some 
 of the mammalia. 
 
 Dissection. — This requires considerable care, and should be performed in the following 
 manner: To expose the Attollens auriculam, draw the pinna, or broad part of the ear, downward, 
 when a tense band will be felt beneath the skin, passing from the side of the head to the upper 
 part of the concha; by dividing the skin over this band in a direction from below upward, 
 and then reflecting it on each side, the muscle is exposed. To bring into view the Attrahens 
 auriculam, draw the helix backward by means of a hook, when the muscle will be made 
 tense, and may be exposed in a similar manner to the preceding. To expose the Retrahens 
 auriculam, draw the pinna forward, when the muscle, being made tense, may be felt beneath 
 the skin at its insertion into the back part of the concha, and may be exposed in the same 
 manner as the other muscles. 
 
 The Attrahens Auriculam or Aurem (m. auricularis anterior), the smallest of the 
 three, is thin, fan-shaped, and its fibres pale and indistinct; they arise from the 
 lateral edge of the aponeurosis of the Occipito-frontalis, and converge to be inserted 
 into a projection on the front of the helix. 
 
 Relations. — Superficially, with the skin; deeply, with the areolar tissue derived 
 from the aponeurosis of the Occipito-frontalis, beneath which are the temporal 
 artery and vein and the temporal fascia. 
 
 The AttoUens Auriculam or Aurem (m. auricularis superior), the largest of the 
 three, is thin and fan-shaped : its fibres arise from the aponeurosis of the Occipito- 
 frontalis and converge to be inserted by a thin, flattened tendon into the upper 
 part of the cranial surface of the pinna. 
 
 Relations. — Superficially, with the integument; deeply, with the areolar tissue 
 derived from the aponeurosis of the Occipito-frontalis, beneath which is the tem- 
 poral fascia. 
 
 The Retrahens Auriculam or Aurem (m. auricularis posterior) consists of two or 
 three fleshy fasciculi, which arise from the mastoid portion of the temporal bone 
 by short aponeurotic fibres. They are inserted into the lower part of the cranial 
 surface of the concha. 
 
 Relations. — Superficially, with the integument; deeply, with the mastoid portion 
 of the temporal bone and the posterior auricular artery and nerve. 
 
 Nerves. — The Attrahens and Attollens auriculam are supplied by the temporal 
 branch of the facial ; the Retrahens auriculam is supplied by the posterior auricu- 
 lar branch of the same nerve. 
 
 Actions. — In man, these muscles possess very little action: the Attrahens auric- 
 ulam draws the ear forward and upward; the Attollens auriculam slightly raises 
 it; and the Retrahens auriculam draws it backward. 
 
 24 
 
370 THE MUSCLES AND FASCIjE 
 
 3. The Palpebral Region (Fig. 260). 
 
 Orbicularis palpebrarum. Levator palpebrse. 
 
 Corrugator supercilii. Tensor tarsi. 
 
 Dissection (Fig. 257). — In order to expose the muscles of the face, continue the longi- 
 tudinal incision made in the dissection of the Occipito-frontalis down the median line of the 
 face to the tip of the nose, and from this point onward to the upper lip; and carry another 
 incision along the margin of the lip to the angle of the mouth, and transversely across the face 
 to the angle of the jaw. Then make an incision in front of the external ear, from the angle of 
 the jaw upward, to join the transverse incision made in exposing the Occipito-frontalis. These 
 incisions include a square-shaped flap, which should be removed in the direction marked in 
 the figure, with care, as the muscles at some points are intimately adherent to the integument. 
 
 The Orbicularis Palpebrarum (m. orbicularis oculi) is a sphincter muscle, which 
 surrounds the circumference of the orbit and eyehds. It arises from the internal 
 angular process of the frontal bone, from the nasal process of the superior maxil- 
 lary bone in front of the lachrymal groove for the nasal duct, and from the anterior 
 surface and borders of a short tendon, the tendo oculi, or internal taxsal ligament, 
 placed at the inner angle of the orbit. From this origin the fibres are directed 
 outward, forming a broad, thin, and flat layer, which covers the eyelids, surrounds 
 the circumference of the orbit, and spreads out over the temple and downward on 
 the cheek. The internal or palpebral portion {pars palpebralis) of the Orbicularis is 
 thin and pale; it arises from the bifurcation of the tendo palpebrarum, and forms 
 a series of concentric curves, which are on the outer side of the eyelids inserted into 
 the external tarsal ligament. The external or orbital portion (pars orbitalis) is 
 thicker and of a reddish color: its fibres are well developed, and form complete 
 ellipses. The upper fibres of this portion blend with the Occipito-frontalis and 
 Corrugator supercilii. 
 
 Relations. — By its superficial surface, with the integument. By its deep surface, 
 above, with the Occipito-frontalis and Corrugator supercilii, with which it is inti- 
 mately blended, and with the supraorbital vessels and nerve ; below, it covers the 
 lachrymal sac, and the origin of the Levator labii superioris alreque nasi, the 
 I-,evator labii superioris, and the Zygomaticus minor muscles. Internally, it is 
 occasionally blended with the Pyramidalis nasi. Externally , it lies on the temporal 
 fascia. On the eyelids it is separated from the conjunctiva by the Levator palpe- 
 brse, the tarsal ligaments, the tarsal plates, and the Meibomian glands. 
 
 The tendo oculi or internal tarsal ligament (ligamentum palpebrale mediale) is a 
 short tendon, about two lines in length and one in breadth, attached to the nasal 
 process of the superior maxillary bone in front of the lachrymal groove. Crossing 
 the lachrymal sac, it divides into two parts, each division being attached to the 
 inner extremity of the corresponding tarsal plate. As the tendon crosses the lach- 
 rymal sac, a strong aponeurotic lamina is given off from the posterior surface, 
 which expands over the sac, and is attached to the ridge on the lachrymal bone. 
 This is the reflected aponeurosis of the tendo oculi. 
 
 The external tarsal ligament (raphe palpebralis lateralis) is a much weaker struc- 
 ture than the tendo oculi. It is attached to the margin of the frontal process of 
 the malar bone, and passes inward to the outer commissure of the eyelids; it 
 coimects together the outer extremities of the two tarsal cartilages. 
 
 Use of Tendo Oculi. — Besides giving attachment to part of the Orbicularis 
 palpebrarum and to the tarsal plates, it serves to suck the tears into the lachrymal 
 sac, by its attachment to the sac. Thus, each time the eyelids are closed, the tendo 
 oculi becomes tightened, through the action of the Orbicularis, and draws the wall 
 of the lachrymal sac outward and forward, so that a vacuum is made in the sac, 
 and the tears are sucked along the lachrymal canals into it. 
 
THE PALPEBRAL REGION 
 
 371 
 
 The Comigatcr Supercilii (Figs. 259 and 260) is a small narrow, pyramidal 
 muscle, placed at the inner extremity of the eyebrow, beneath the Occipito- 
 frontalis and Orbicularis palpebrarum muscles. It arises from the inner extrem- 
 ity of the superciliary ridge, from whence its fibres pass upward and outward, 
 and are inserted into the deep surface of the skin, opposite the middle of the 
 orbital arch. 
 
 Relations. — By its anterior surface with the Occipito-frontalis and Orbicularis 
 palpebrarum muscles; by its posterior surface, with the frontal bone and supra- 
 trochlear nerve. 
 
 The Levator Palpebrae will be described with the muscles of the orbital region. 
 
 The Tensor Tarsi or Homer's Muscle (pars lacrimalis of the orbicularis pal- 
 pebrarum) (Fig. 261) is a small thin muscle about three lines in breadth and six 
 in length, situated at the inner side of the orbit, behind the tendo oculi. It is 
 usually considered to be composed of fibres derived from the Orbicularis palpe- 
 brarum. It arises from the crest and adjacent part of the orbital surface of the 
 
 FRONTAL SINUS 
 
 CORRUGATOR 
 SUPERCIUI 
 
 PALPEBRAL PORTION 
 
 OF ORBICULARIS 
 
 PALPEBRARUM 
 
 PUNCTA 
 LACHRYMALIA 
 
 ' ~77f LACHRYMAL 
 
 '£ GROOVE 
 
 ORBITAL PORTION OF 
 ORBICULARIS PALPEBRARUM 
 
 ANTRUM OF 
 HIGHMORE 
 
 Fig. 261. — The three portions of the Orbicularis palpebrarum muscle, and the relation of this muscle to the 
 Corrugator supercilii muscle, seen from behind. (Left side.) (Toldt.) 
 
 lachrymal bone, and, passing across the lachrymal sac, divides into two slips, 
 which cover the lachrymal canals and are inserted into the tarsal plates internal 
 to the puncta lachrymalia. Its fibres appear to be continuous with those of the 
 palpebral portion of the Orbicularis palpebrarum; it is occasionally very indistinct. 
 
 Nerves. — The Orbicularis palpebrarum, Corrugator supercilii, and Tensor tarsi 
 are supplied by the facial nerve. Recent investigations tend to show that the 
 Orbicularis palpebrarum, Corrugator supercilii, and frontal part of the Occipito- 
 frontalis are in reality supplied by fibres of the third nerve, which descend through 
 the pons varolii to join the facial nerve. 
 
 Actions. — The Orbicularis palpebrarum is the sphincter muscle of the eyelids. 
 The palpebral portion acts involuntarily, closing the lids gently, as in sleep or in 
 blinking; the orbicular portion is subject to the will. When the entire muscle is 
 brought into action, the skin of the forehead, temple, and cheek is drawn inward 
 toward the inner angle of the orbit, and the eyelids are firmly closed as in photo- 
 
372 
 
 THE MUSCLES AND FASCIA 
 
 phobia. When the skin of the forehead, temple, and cheek is thus drawn inward 
 by the action of the muscle it is thrown into folds, especially radiating from the 
 outer angle of the eyelids, which give rise in old age to the so-called "crow's feet." 
 The Levator palpebrse is the direct antagonist of this muscle; it raises the upper 
 eyelid and exposes the globe. The Corrugator supercilii draws the eyebrow 
 downward and inward, producing the vertical wrinkles of the forehead. It is the 
 " frowning" muscle, and may be regarded as the principal agent in the expression 
 of suffering. The Tensor tarsi draws the eyelids inward and compresses the eye- 
 lids and the extremities of the lachrymal canals against the surface of the globe 
 of the eye; thu& placing the canals in the most favorable situation for receiving 
 the tears. It serves, also, to compress the lachrymal sac. 
 
 4. The Orbital Region (Fig. 262). 
 
 Levator palpebrse superioris. Rectus internus. 
 
 Rectus superior. Rectus externus. 
 
 Rectus inferior. Obliquus oculi superior. 
 
 Obliquus oculi inferior. 
 
 Dissection. — To open the cavity of the orbit, remove the skull-cap and brain; then saw 
 through the frontal bone at the inner extremity of the supraorbital ridge, and externally at its 
 junction with the malar. Break in pieces the thin roof of the orbit by a few slight blows of 
 the hammer, and take it away; drive forward the superciliary portion of the frontal bone 
 
 Fig. 262. — Muscles of the right orbit. 
 
 by a smart stroke, but do not remove it, as that would destroy the pulley of the Obliquus 
 superior. When the fragments are cleared away, the periosteum of the orbit will be exposed; 
 this being removed, together with the fat which fills the cavity of the orbit, the several muscles 
 of this region can be examined. The dissection will be facilitated by distending the globe 
 of the eye. In order to effect this, puncture the optic nerve near the eyeball with a curved 
 needle, and push the needle onward into the globe; insert the point of a blowpipe through 
 this aperture, and force a little air into the cavity of the eyeball; then apply a ligature round 
 the nerve so as to prevent the air escaping. The globe being now drawn forward, the muscles 
 will be put upon the stretch. 
 
 The Levator Palpebrae Superioris is thin, flat, and triangular in shape. It 
 arises from the under surface of the lesser wing of the sphenoid, above and in 
 front of the optic foramen, from which it is separated by the origin of the Superior 
 rectus (Fig. 263). At its origin it is narrow and tendinous, but soon becomes 
 broad and fleshy, and finally terminates in a wide aponeurosis, which is inserted 
 into the upper margin of the superior tarsal plate. From this aponeurosis a thin 
 expansion is continued onward, passing between the fibres of the Orbicularis 
 
THE ORBITAL REGION 373 
 
 to be inserted into the skin of the Hd, and some deeper fibres blend with an 
 expansion from the sheath of the Superior rectus muscle, and are with it pro- 
 longed into the conjunctiva. 
 
 Relations. — By its upper surface, with the frontal nerve and supraorbital 
 artery, the periosteum of the orbit and lachrymal gland; and, in the lid, with the 
 inner surface of the tarsal ligament ; by its under surface, with the Superior rectus, 
 and, in the lid, with the conjunctiva. A small branch of the third nerve enters 
 its under surface. 
 
 The Superior Rectus (m. rectus superior) , the thinnest and narrowest of the 
 four Recti, arises from the upper margin of the optic foramen (Fig. 263) beneath 
 the Levator palpebrse, and from the fibrous sheath of the optic nerve; and is 
 inserted by a tendinous expansion into the sclerotic coat, about three or four 
 lines from the margin of the cornea. 
 
 Relations. — By its upper surface, with the Levator palpebrse; by its under sur- 
 face, with the optic nerve, the ophthalmic artery, the nasal nerve, and the branch 
 of the third nerve which supplies it ; and, in front, with the tendon of the Superior 
 oblique and the globe of the eye. 
 
 The Inferior Rectus (m. rectus inferior) and the Internal Rectus (m. rectus 
 medialis) arise by a common tendon, the ligament of Zinn^ (annulus tendineus 
 communis), which is attached round the circumference of the optic foramen, 
 except at its upper and outer part (Fig. 263). 
 
 The External Rectus (m. rectus lateralis) has two heads : the upper one arises 
 from the outer margin of the optic foramen immediately beneath the Superior 
 rectus; the lower head, partly from the ligament of Zinn and partly from a small 
 pointed process of bone on the lower margin 
 of the sphenoidal fissure (Fig. 263). Each Rectus stiperior 
 
 muscle passes forward in the position implied by paipebZ^'lupenor. 
 its name, to be inserted by a tendinous expan- owquus superior} 
 sion, the tunica albuginea, into the sclerotic coat, 
 about three or four lines from the margin of 
 the cornea. Between the two heads of the Ex- 
 ternal rectus is a narrow interval, through 
 which passes the third, the nasal branch of 
 the ophthalmic division of the fifth and sixth 
 nerves, and the ophthalmic vein. Although sectus inferior. 
 
 nearly all of these muscles present a common ^^^..e'nt'oTtle mSi^rortile le^^ 
 origin and are inserted in a similar manner 
 
 into the sclerotic coat, there are certain differences to be observed in them as 
 regards their length and breadth. The Liternal rectus is the broadest, the 
 External is the longest, and the Superior is the thinnest and narrowest. 
 
 The Superior Oblique (w. ohliquus superior) is a fusiform muscle placed at the 
 upper and inner side of the orbit, internal to the Levator palpebrse. It arises 
 about a line above the inner margin of the optic foramen (Fig. 263) , and, pass- 
 ing forward to the inner angle of the orbit, terminates in a rounded tendon, 
 which plays in a ring or pulley, the trochlea {trochlea m. ohliqui superioris), 
 formed by a cartilaginous tissue attached to a depression beneath the internal 
 angular process of the frontal bone, the contiguous surfaces of the tendon and 
 ring being lined by a delicate synovial membrane and enclosed in a thin fibrous 
 investment. The tendon is reflected backward, outward, and downward beneath 
 the Superior rectus to the outer part of the globe of the eye, and is inserted into 
 
 ' The ligament of Zinn ought, perhaps more appropriately, to be termed the aponeurosis or tendon of Zinn, 
 Mr. C. B. Lockwood has described a somewhat similar structure on the under surface of the Superior rectus 
 muscle, which is attached to the lesser wing of the sphenoid, forming the upper and outer margin of the optic 
 foramen. This superior tendon give.s origin to the Rectus superior, the superior head of the External rectus, 
 and the upper part of the Internal rectus. — Journal of Anatomy and Physiology, vol. xx. part i. p. 1. 
 
374 THE MUSCLES AND FASCIA 
 
 the sclerotic coat, behind the equator of the eyeball, the insertion of the muscle 
 lying between the Superior and External recti. 
 
 Relations. — By its upper surface, with the periosteum covering the roof of the 
 orbit and the fourth nerve: the tendon, where it lies on the globe of the eye, 
 is covered by the Superior rectus; by its under surface, with the nasal nerve, 
 ethmoidal arteries, and the upper border of the internal rectus. 
 
 The Inferior Oblique (m. obliquus inferior) is a thin, narrow muscle placed near 
 the anterior margin of the orbit. It arises from a depression on the orbital plate 
 of the superior maxillary bone, external to the lachrymal groove (Fig. 262). 
 Passing outward, backward, and upward between the Inferior rectus and the 
 floor of the orbit, and then between the eyeball and the External rectus, it is 
 inserted into the outer part of the sclerotic coat between the Superior and External 
 recti, near to, but somewhat behind, the tendon of insertion of the Superior oblique. 
 
 Relations. — By its ocular surface, with the globe of the eye and with the Inferior 
 rectus; by its orbital surface, with the periosteum covering the floor of the orbit, 
 and with the External rectus. Its borders look forward and backward ; the poste- 
 rior one receives a branch of the third nerve. 
 
 The orbital muscle or Miiller's muscle {musculus orbitalis), which spans the 
 spheno-maxillary fissure and infraorbital groove, is composed of non-striated 
 fibres, and is a rudimentary structure continuous with the periosteum of the orbit.^ 
 
 Nerves. — The Levator palpebree. Inferior oblique, and all the Recti excepting 
 the External, are supplied by the third nerve; the Superior oblique, by the fourth; 
 the External rectus, by the sixth. 
 
 Actions. — The Levator palpebrse raises the upper eyelid, and is the direct 
 antagonist of the Orbicularis palpebrarum. The four Recti muscles are attached 
 in such a manner to the globe of the eye that, acting singly, they will turn it either 
 upward, downward, inward, or outward, as expressed by their names. The 
 movement produced by the Superior or Inferior rectus is not quite a simple one, 
 for, inasmuch as they pass obliquely outward and forward to the eyeball, the 
 elevation or depression of the cornea must be accompanied by a certain deviation 
 inward, with a slight amount of rotation, which, however, is corrected by the 
 Oblique muscles, the Inferior oblique correcting the deviation inward of the 
 Superior rectus, and the Superior oblique that of the Inferior rectus. The con- 
 traction of the External and Internal recti, on the other hand, produces a purely 
 horizontal movement. If any two contiguous recti of one eye act together, they 
 carry the globe of the eye in the diagonal of these directions — viz., upward and 
 inward, upward and outward, downward and inward, or downward and outward. 
 The movement of circumduction, as in looking round a room, is performed by 
 the alternate action of the four Recti. The Oblique muscles rotate the eyeball 
 on its antero-posterior axis, this kind of movement being required for the correct 
 viewing of an object when the head is moved laterally, as from shoulder to shoulder, 
 in order that the picture may fall in all respects on the same part of the retina of 
 each eye.^ It should be noted that sometimes the corresponding Recti and some- 
 times the opposite ones of the two eyes act together; for instance, the two superior 
 and inferior Recti carry both eyeballs upward and downward, respectively. In 
 looking toward the right the right External and left Internal recti act together, 
 the reverse being the case in looking toward the left. In turning both eyes toward 
 the middle line, as in directing our vision toward an object less than twenty feet 
 distant, the two internal recti act together. 
 
 Fasciae of the Orbit. — The connective tissue of the orbit is in various places 
 condensed into thin membranous layers, which may be conveniently described as 
 
 1 See F. Groyer, in the Vienna Sitzungsberichte der Kaiserlichen Akademie derWissenschaften, 1903, Band cxii. 
 _ ^ On the Oblique Muscles of the Eye in Man and Vertebrate Animals, by John Struthers, M.D., in Anatom- 
 ical and Physiological Observations. For a fuller account of the various co-ordinate actions of the muscles of 
 a smgle eye and of both eyes than our space allows see Dr. M. Foster's Text-book of Physiology. 
 
THE NASAL REGION 375 
 
 (1) the orbital fascia; (2) the sheaths of the muscles; and (3) the covering of the 
 eyeball. 
 
 (1) The Orbital Fascia. — This forms the periosteum of the orbit. It is loosely 
 connected to the bones, from which it can be readily separated. Behind, it is 
 connected with the dura mater by processes which pass through the optic foramen 
 and sphenoidal fissure, and with the sheath of the optic nerve. In front it is 
 connected with the periosteum at the margin of the orbit, and sends off a process 
 which assists in forming the palpebral fascia. From its internal surface two 
 processes are given off — one to enclose the lachrymal gland, the other to hold the 
 pulley of the Superior oblique muscle in position. 
 
 (2) The Sheaths of the Muscles. — The sheaths of the muscles give off expansions 
 to the margins of the orbit which limit the action of the muscles. 
 
 (3) The Covering of the Eyeball — Tenon's capsule — surrounds the posterior 
 two-thirds of the eyeball ; it will be described in the sequel. 
 
 Surgical Anatomy. — The position and exact point of insertion of the tendons of the 
 Internal and External recti muscles into the globe should be carefully examined from the front 
 of the eyeball, as the surgeon is often required to divide the one or the other muscle for the cure 
 of strabismus (squint). In convergent strabismus, which is the more common form of the disease, 
 the eye is turned inward, requiring the division of the Internal rectus. In the divergent form, 
 which is more rare, the eye is turned outward, the External rectus being especially implicated. 
 The deformity produced in either case is to be remedied by division of one or the other muscle. 
 The operation is thus performed: The lids are to be well separated; the eyeball being rotated 
 outward or inward, the conjunctiva should be raised by a pair of forceps and divided immediately 
 beneath the lower border of the tendon of the muscle to be divided, a little behind its insertion 
 into the sclerotic; the submucous areolar tissue is then divided, and into the small aperture 
 thus made a blunt hook is passed upward between the muscle and the globe, and the tendon of 
 the muscle and conjunctiva covering it divided by a pair of blunt-pointed scissors. Or the 
 tendon may be divided by a subconjunctival incision, one blade of the scissors being passed 
 upward between the tendon and the conjunctiva, and the other between the tendon and the 
 sclerotic. The student, when dissecting these muscles, should remove on one side of the subject 
 the conjunctiva from the front of the eye, in order to see more accurately the position of the 
 tendons, while on the opposite side the operation may be performed. Inflammation of the 
 synovial membrane lining the trochlea of the Superior oblique may lead to the formation of 
 a cyst of considerable size. 
 
 In performing enucleation of the eyeball the conjunctiva is clipped with scissors near the 
 cornea and the capsule of T^non is divided with it. One rectus muscle after another is caught 
 up on a blunt hook and divided. The scissors are now pushed well in along the outer orbital 
 wall and the optic nerve is divided. Finally the oblique muscles, the ciliary vessels and nerves, 
 and fragments of tissue helping to retain the globe are cut and the eyeball is enucleated. 
 
 An orbital abscess is evacuated by making an incision close to the border of the orbit, above 
 or below the eyeball. 
 
 5. The Nasal Region (Fig. 260). 
 
 Pyramidalis nasi. Dilatator naris anterior, 
 
 lycvator labii superioris alseque nasi. Compressor nasi. 
 
 Dilatator naris posterior. Compressor narium minor. 
 
 Depressor ate nasi. 
 
 The Pyramidalis Nasi is a small pyramidal slip placed over the nasal bone. 
 Its origin is by tendinous fibres from the fascia covering the lower part of the nasal 
 bone and upper part of the cartilage, where it blends with the Compressor nasi, 
 and it is inserted into the skin over the lower part of the forehead between the 
 two eyebrows, its fibres decussating with those of the Occipito-frontalis (see 
 page 368). 
 
 Relations. — By its upper surface, with the skin; by its under surface, with the 
 frontal and nasal bones. 
 
 The Levator Labii Superioris Alaeque Nasi is a thin triangular muscle placed 
 by the side of the nose, and extending between the inner margin of the orbit and 
 
376 THE MUSCLES AND FASCIA 
 
 upper lip. It arises by a pointed extremity from the upper part of the nasal 
 process of the superior maxillary bone, and, passing obliquely downward and 
 outward, divides into two slips, one of which is inserted into the cartilage of the 
 ala of the nose and the under surface of the skin over the ala; the other is pro- 
 longed into the upper lip, becoming attached to the urider surface of the skin 
 and blended with the Orbicularis oris and Levator labii superioris proprius. 
 
 Relations. — In ]ront, with the integument, and with a small part of the Orbicu- 
 laris palpebrarum above. 
 
 The Dilatator Naris Posterior is a small muscle which is placed partly beneath 
 the elevator of the nose and lip. It arises from the margin of the nasal notch of 
 the superior maxilla and from the sesamoid cartilages, and is inserted into the 
 skin near the margin of the nostril. 
 
 The Dilatator Naris Anterior is a thin delicate fasciculus passing from the 
 cartilage of the ala of the nose to the integument near its margin. This muscle is 
 situated in front of the preceding. 
 
 The Compressor Nasi is a small, thin, triangular muscle arising by its apex 
 from the superior maxillary bone, above and a little external to the incisive fossa; 
 its fibres proceed upward and inward, expanding into a thin aponeurosis which 
 is attached to the fibro-cartilage of the nose and is continuous on the bridge of 
 the nose with that of the muscle of the opposite side and with the aponeurosis of 
 the Pyraraidalis nasi. His uses the term musculus nasalis to include the Com- 
 pressor nasi (transverse portion of the nasal muscle), and the Dilatator naris 
 posterior and the Dilatator naris anterior (alar portion of the nasal muscle). 
 
 The Compressor Narium Minor is a small muscle attached by one end to the 
 alar cartilage, and by the other to the integument at the end of the nose. 
 
 The Depressor Alae Nasi (depressor septi) is a short radiated muscle arising 
 from the incisive fossa of the superior maxilla; its fibres ascend to be inserted into 
 the septum and back part of the ala of the nose. This muscle Hes between the 
 mucous membrane and muscular structure of the hp. 
 
 Nerves. — All of the muscles of this group are supplied by the facial nerve. 
 
 Actions. — The Pyramidalis nasi draws down the inner angle of the eyebrows 
 and produces transverse wrinkles over the bridge of the nose. The Levator labii 
 superioris alseque nasi draws upward the upper lip and ala of the nose ; its most 
 important action is upon the nose, which it dilates to a considerable extent. The 
 action of this muscle produces a marked influence over the countenance, and it is 
 the principal agent in the expression of contempt and disdain. The two Dilatatores 
 nasi enlarge the aperture of the nose. Their action in ordinary breathing is to 
 resist the tendency of the nostrils to close from atmospheric pressure, but in 
 difficult breathing they may be noticed to be in violent action, as well as in some 
 emotions, as anger. The Depressor aUe nasi is a direct antagonist of the other 
 muscles of the nose, drawing the ala of the nose downward, and thereby constrict- 
 ing the aperture of the nares. The Compressor nasi depresses the cartilaginous 
 part of the nose and compresses the alse together. 
 
 6. The Superior Maxillary Region (Fig. 260). 
 
 Levator labii superioris. Zygomaticus major. 
 
 Ivcvator anguli oris. Zygomaticus minor. 
 
 By the term musculus quadratus labii superioris, His includes three muscles. 
 The caput angulare is called in this book the Levator labii superioris alaeque nasi. 
 The caput infraorbitale is called the Levator labii superioris. The caput zygomati- 
 cum is called the Zygomaticus minor. 
 
 The Levator Labii Superioris (proprius) is a thin muscle of a quadrilateral 
 form. It arises from the lower margin of the orbit immediately above the infra- 
 
THE MANDIBULAR REGION 377 
 
 orbital foramen, some of its fibres being attached to the superior maxilla, others 
 to the malar bone; its fibres converge to be inserted into the muscular substance 
 of the upper lip. 
 
 Relations. — By its swperjicial surface above, with the lower segment of the 
 Orbicularis palpebrarum; below, it is subcutaneous. By its deep surface it con- 
 ceals the origin of the Compressor nasi and Ijcvator anguli oris muscles, and the 
 infraorbital vessels and nerve, as they escape from the infraorbital foramen. 
 
 The Levator Anguli Oris (r/i. caninus) arises from the canine fossa immediately 
 below the infraorbital foramen ; its fibres incline downward and a little outward, to 
 be inserted into the deep surface of the skin and into the subcutaneous tissue 
 near the angle of the mouth and intermingles with the fibres of the Zygomaticus 
 major, the Depressor anguli oris, and the Orbicularis. 
 
 Relations. — By its superficial surface, with the Levator labii superioris and 
 the infraorbital vessels and nerves; by its deep surface, with the superior maxilla, 
 the Buccinator, and the mucous membrane. 
 
 The Zygomaticus Major (m. zygomaticus) is a slender fasciculus which 
 arises from the malar bone, in front of the zygomatic suture, and, descending 
 obliquely downward and inward, is inserted into the deep surface of the skin 
 and subcutaneous tissue at the outer portion of the upper lip and into the angle 
 of the mouth, where it blends with the fibres of the Levator anguli oris, the 
 Orbicularis oris, and the Depressor anguli oris. 
 
 Relations. — By its superficial surface, with the subcutaneous adipose tissue; 
 by its deep surface, with the Masseter and Buccinator muscles and the facial artery 
 and vein. 
 
 The Zygomaticus Minor, which is often absent, arises from the malar bone 
 immediately behind the maxillary suture, and, passing downward and inward, is 
 inserted into the deep surface of the skin and the adjacent muscles at the upper 
 margin of the exposed vermilion surface of the lip midway between the middle 
 line of the lip and the angle of the mouth. It is continuous with the Orbicularis 
 oris at the outer margin of the I^evator labii superioris. It lies in front of the 
 preceding. 
 
 Relations. — By its superficial surface, with the integument and the Orbicularis 
 palpebrarum above; by its deep surface, with the Masseter, Buccinator, and 
 Levator anguli oris, and the facial artery and vein. 
 
 Nerves. — This group of muscles is supplied by the facial nerve. 
 
 Actions. — The Levator labii superioris is the proper elevator of the upper lip, 
 carrying it at the same time a little forward. It assists in forming the naso-labial 
 ridge, which passes from the side of the nose to the upper lip and gives to the 
 face an expression of sadness. The Levator anguli oris raises the angle of the 
 mouth and draws it inward, and assists the Levator labii superioris in producing 
 the naso-labial ridge. The Zygomaticus major draws the angle of the mouth 
 backward and upward, as in laughing; whilst the Zygomaticus minor, being 
 inserted into the outer part of the upper lip and not into the angle of the 
 mouth, draws it backward, upward, and outward, and thus gives to the face 
 an expression of sadness, 
 
 7. The Mandibular Region (Fig. 260). 
 
 Levator labii inferioris. Depressor labii inferioris. 
 
 Depressor anguli oris. 
 
 Dissection. — The muscles in this region may be dissected by making a vertical incision 
 through the integument from the margin of the lower lip to the chin; a second incision should 
 then be carried along the margin of the lower jaw as far as the angle, and the integument care- 
 fully removed in the direction shown in Fig. 258. 
 
378 THE MUSCLES AND FASCIA 
 
 The Levator Labii Inferioris or Levator Menti (m. mentalis) is to be dissected 
 by everting the lower Hp and raising the mucous membrane. It is a small conical 
 fasciculus placed on the side of the frsenum of the lower lip. It arises from the 
 incisive fossa, external to the symphysis of the lower jaw; its fibres descend to 
 be inserted into the integument of the chin. 
 
 Relation. — On its inner surface, with the mucous membrane; in the median 
 line, it is blended with the muscle of the opposite side; and on its outer side, with 
 the Depressor labii inferioris. 
 
 The Depressor Labii Inferioris or Quadratus Menti (m. quadratus labii 
 inferioris) (Fig. 264) is a small quadrilateral muscle. It arises from the external 
 oblique line of the lower jaw, between the symphysis and mental foramen, and 
 passes obliquely upward and inward, to be inserted into the integument of the 
 lower lip, its fibres blending with the Orbicularis oris and with those of its fellow 
 of the opposite side. It is continuous with the fibres of the Platysma at its origin. 
 This muscle contains much yellow fat intermingled with its fibres. 
 
 Relations. — By its superficial surface, with part of the Depressor anguli oris 
 and with the integument, to which it is closely connected; by its deep surface, 
 with the mental vessels and nerves, the mucous membrane of the lower lip, the 
 labial glands, and the Levator menti, with which it is intimately united. 
 
 The Depressor Anguli Oris or Triangularis Menti (m. triangularis) (Fig. 260) 
 is triangular in shape, arising, by its broad base, from the external oblique line of 
 the lower jaw, from whence its fibres pass upward, to be inserted, by a narrow 
 fasciculus, into the angle of the mouth. It is continuous with the Platysma at 
 its origin and with the Orbicularis oris and Risorius at its insertion, and some of 
 its fibres are directly continuous with those of the Levator anguli oris. Muscular 
 fibres connecting the two muscles below the chin are occasionally met with; they 
 constitute the Musculus transversus menti of His and Waldeyer. 
 
 Relations. — By its superficial surface, with the integument; by its deep surface, 
 with the Depressor labii inferioris and Buccinator. 
 
 Nerves. — This group of muscles is supplied by the facial nerve. 
 
 Actions. — The Levator labii inferioris raises the lower lip and protrudes it 
 forward, and at the same time wrinkles the integument of the chin, expressing 
 doubt or disdain. The Depressor labii inferioris draws the lower lip directly 
 downward and a little outward, as in the expression of irony. The Depressor 
 anguli oris depresses the angle of the mouth, being the antagonist to the Levator 
 anguli oris and Zygomaticus major; acting with these muscles, it will draw the 
 angle of the mouth directly backward. 
 
 8. The Intermaxillary Region. 
 Orbicularis oris. Buccinator. Risorius. 
 
 Dissection. — The dissection of these muscles may be considerably facilitated by filling the 
 cavity of the mouth with tow, so as to distend the cheeks and lips; the mouth should then be 
 closed by a few stitches and the integument carefully removed from the surface. 
 
 The Orbicularis oris (Figs. 260 and 264) is not a sphincter muscle, like the Orbic- 
 ularis palpebrarum, but consists of numerous strata of muscular fibres, having dif- 
 ferent directions, which surround the orifice of the mouth. These fibres are par- 
 tially derived from the other facial muscles which are inserted into the lips, and are 
 partly fibres proper to the lips themselves. Of the former, a considerable number 
 are derived from the Buccinator and form the deeper stratum of the Orbicularis. 
 Some of them — namely, those near the middle of the muscle — decussate at the 
 angle of the mouth, those arising from the upper jaw passing to the lower lip, and 
 those from the lower jaw to the upper lip. Other fibres of the muscle, situated at 
 
THE INTERMAXILLARY REGION 
 
 379 
 
 its upper and lower part, pass across the lips from side to side without decussation. 
 Superficial to this stratum is a second, formed by the Levator and Depressor 
 anguli oris, which cross each other at the angle of the mouth, those from the 
 Depressor passing to the upper lip, and those from the Levator to the lower lip, 
 along which they run to be inserted into the skin near the median line. In addi- 
 
 Fio. 264. — Temporal and deep muscles about the mouth. (Testut.) 
 
 tion to these there are fibres from the other muscles inserted into the lips — the 
 Levator labii superioris, the Levator labii superioris alseque nasi, the Zygomatici, 
 and the Depressor labii inferioris; these intermingle with the transverse fibres 
 above described, and have principally an oblique direction. The proper fibres of 
 the lips are oblique, and pass from the under surface of the skin to the mucous 
 membrane through the thickness of the lip. And in addition to these are fibres 
 
380 THE MUSCLES AND FASCIA 
 
 by which the muscle is connected directly with the maxillary bones and the 
 septum of the nose. These consist, in the upper lip, of four bands, two of 
 which {m. incisivus superior) arise from the alveolar border of the superior 
 maxilla, opposite the lateral incisor tooth, and, arching outward on each side, 
 are continuous at the angles of the mouth with the other muscles inserted into 
 this part. The two remaining muscular slips, called the Nasolabialis, connect 
 the upper lip to the back of the septum of th& nose: as they descend from the 
 septum an interval is left between them. It is this interval which forms the depres- 
 sion seen on the surface of the skin beneath the septum of the nose, which is 
 called the philtnim. The additional fibres for the lower segment {m. incisivus 
 inferior) arise from the inferior maxilla, externally to the Levator labii inferioris, 
 and arch outward to the angles of the mouth, to join the Buccinator and the other 
 muscles attached to this part. 
 
 Relations. — By its superficial surface, with the integument, to which it is closely 
 connected; by its deep surface, with the buccal mucous membrane, the labial 
 glands, and coronary vessels; by its outer circumference it is blended with the 
 numerous muscles which converge to the mouth from various parts of the face. 
 Its inner circumference is free, and covered by the mucous membrane. 
 
 The Buccinator (Fig. 264) is a broad, thin muscle, quadrilateral in form, 
 which occupies the interval between the jaws at the side of the face. It arises 
 from the outer surface of the alveolar processes of the upper and lower jaws, 
 corresponding to the three molar teeth, and, behind, from the anterior border of 
 the ptery go-maxillary ligament. The fibres converge toward the angle of the 
 mouth, where the central fibres intersect each other, those from below being 
 continuous with the upper segment of the Orbicularis oris, and those from above 
 with the inferior segment ; the highest and lowest fibres continue forward uninter- 
 ruptedly into the corresponding segment of the lip, without decussation. 
 
 Relations. — By its superficial surface, behind, with a large mass of fat, the sucking 
 or suctorial pad (corpus adiposum huccx), which separates it from the ramus of the 
 lower jaw, the Masseter, and a small portion of the Temporal muscle. The suck- 
 ing pad is much more developed relatively in children than in adults. It assists 
 sucking by aiding the cheek to resist atmospheric pressure. The buccinator 
 muscle is in relation, anteriorly, with the Zygomatici, Risorius, Levator anguli 
 oris. Depressor anguli oris, and Stenson's duct, which pierces it opposite the 
 second molar tooth of the upper jaw; the facial artery and vein cross it from below 
 upward; it is also crossed by the branches of the facial and buccal nerves; by 
 its internal surface, with the buccal glands and mucous membrane of the mouth. 
 
 The Pterygo-maxillary or Pterygo-mandibular Ligament {raphe pterygomandih- 
 ularis) separates the Buccinator muscle from the Superior constrictor of the 
 pharynx. It is a tendinous thickening of the bucco-pharyngeal fascia, attached by 
 one extremity to the apex of the internal pterygoid plate, and by the other to the 
 posterior extremity of the internal oblique line of the lower jaw. Its inner surface 
 corresponds to the cavity of the mouth, and is lined by mucous membrane. Its 
 outer surface is separated from the ramus of the jaw by a quantity of adipose 
 tissue. Its posterior border gives attachment to the Superior constrictor of the 
 pharynx; its anterior border, to the fibres of the Buccinator. 
 
 The Bucco-pharyngeal fascia (fascia hiccophari/ngea) is a thin fascia covering 
 the external surface of the Buccinator muscle. lit is gradually lost in front of the 
 angle of the mouth. Posteriorly it is continued over the external surface of the 
 throat muscles. Its thickened cord-like portion is the stylo-mandibular ligament. 
 
 The Risorius or Santorini's Muscle (m. risorius) (Fig. 260) consists of a 
 narrow bundle of fibres which arises in the fascia over the Masseter muscle, 
 and, passing horizontally forward, is inserted with the Depressor anguli oris into 
 the subcutaneous and muscular tissue at the angle of the mouth. It is placed 
 
THE TEMPORO - MANDIBULAR REGION 381 
 
 superficial to the Platysraa, and is broadest at its outer extremity. This muscle 
 varies much in its size and form. 
 
 Nerves. — The muscles in this group are all supplied by the facial nerve. The 
 buccal branch of the inferior maxillary nerve pierces the Buccinator muscle, and 
 by some anatomists is regarded as partly supplying this muscle. Probably it 
 merely pierces it on its way to the mucous membrane of the cheek. 
 
 Actions. — The Orbicularis oris in its ordinary action produces the direct closure 
 of the lips; by its deep fibres, assisted by the oblique ones, it closely applies the 
 lips to the alveolar arch. The superficial part, consisting principally of the decus- 
 sating fibres, brings the lips together and also protrudes them forward. The Buc- 
 cinators contract and compress the cheeks, so that, during the process of mastica- 
 tion, the food is kept under the immediate pressure of the teeth. When the cheeks 
 have been previously distended with air, the Buccinator muscles expel it from 
 between the lips, as in blowing a trumpet. Hence the name (buccina, a trumpet). 
 The Risorius retracts' the angles of the mouth, and produces the unpleasant 
 expression which is sometimes seen in tetanus, and is known as risus sardonicus, the 
 sardonic laugh. 
 
 9. The Temporo-mandibular Region. 
 
 Masseter. Temporal. 
 
 The Masseteric Fascia (fascia parotideomasseterica) covers the outer and inner 
 surfaces of the parotid gland as a thick membrane, called the parotid fascia. It 
 passes forward, and becomes thinner to cover the Masseter muscle, to which it 
 is firmly connected. It is derived from the deep cervical fascia. Above, this 
 fascia is attached to the lower border of the zygoma. It is lost in front below 
 the Risorius and Platysma. 
 
 The Masseter Muscle is exposed by the removal of this fascia (Fig. 260) ; it is a 
 short, thick muscle, somewhat quadrilateral in form, consisting of two portions, 
 superficial and deep. The superficial portion, the larger, arises by a thick, tendinous 
 aponeurosis from the malar process of the superior maxilla, and from the anterior 
 two-thirds of the lower border of the zygomatic arch: its fibres pass downward 
 and backward, to be inserted into the angle and lower half of the outer surface 
 of the ramus of the jaw. The deep portion is much smaller and more muscular 
 in texture; it arises from the posterior third of the lower border and the whole of 
 the inner surface of the zygomatic arch; its fibres pass downward and forward, 
 to be inserted into the upper half of the ramus and outer surface of the coronoid 
 process of the jaw. The deep portion of the muscle is partly concealed, in front 
 by the superficial portion; behind, it is covered by the parotid gland. The fibres 
 of the two portions are united at their insertion. 
 
 Relations. — By its superficial surface, with the Zygomatici, the parotid gland 
 and Socia parotidis, and Stenson's duct; the branches of the facial nerve and 
 the transverse facial vessels, which cross it; the masseteric fascia; the Risorius, 
 Platysma myoides, and the integument; by its deep surface, with the Temporal 
 muscle at its insertion, the ramus of the jaw, the Buccinator and the long 
 buccal nerve, from which it is separated by a mass of fat (suctorial or sucking pad). 
 The masseteric nerve and artery enter in on its under surface. Its posterior margin 
 is overlapped by the parotid gland. Its anterior margin projects over the Bucci- 
 nator muscle, and the facial vein lies on it below. 
 
 Temporal Fascia (fascia temporalis). — The temporal fascia is seen, at this stage 
 of a dissection, covering in the Temporal muscle. It is a strong, fibrous invest- 
 ment, covered, on its outer surface, by the Attrahens and Attollens auriculam mus- 
 cles, the aponeurosis of the Occipito-frontalis, and by part of the Orbicularis palpe- 
 brarum. The temporal vessels and the auriculo-temporal nerve cross it from below 
 upward. Above, it is a single layer, attached to the entire extent of the upper tem- 
 
382 
 
 THE MUSCLES AND FASCIA 
 
 poral ridge; but below, where it is attached to the zygoma, it consists of two layers, 
 one of which is inserted into the outer, and the other into the inner, border of the 
 zygomatic arch. A small quantity of fat, the orbital branch of the temporal artery, 
 and a filament from the orbital, or temporo-malar, branch of the superior maxillary 
 nerve are contained between these two layers. It affords attachment by its inner 
 surface to the superficial fibres of the Temporal muscle. 
 
 Dissection. — In order to expose the Temporal muscle, remove the temporal fascia, which 
 may be effected by separating it at its attachment along the upper border of the zygoma, and 
 dissecting it upward from the surface of the muscle. The zygomatic arch should then 
 be divided in front at its junction with the malar bone, and behind near the external auditory 
 meatus, and drawn downward with the Masseter, which should be detached from its inser- 
 tion into the ramus and angle of the jaw. The whole extent of the Temporal muscle is then 
 exposed. 
 
 Fig. 265. — The Temporal muscle, the zygoma and Masseter having been removed. 
 
 The Temporal Muscle (m. temporalis) (Figs. 264 and 265) is a broad, radiating 
 muscle situated at the side of the head and occupying the entire extent of the tem- 
 poral fossa. It arises from the whole of the temporal fossa except that portion of it 
 that is formed by the malar bone. Its attachment extends from the external angular 
 process of the frontal in front to the mastoid portion of the temporal behind, and 
 from the curved line on the frontal and parietal bones above to the pterygoid ridge 
 on the great wing of the sphenoid below. It is also attached to the inner surface of 
 the temporal fascia. Its fibres converge as they descend, and terminate in an apon- 
 eurosis, the fibres of which, radiated at its commencement, converge into a thick 
 and flat tendon, which is inserted into the inner surface, apex, and anterior border 
 of the coronoid process of the jaw, nearly as far forward as the last molar tooth. 
 
 Relations. — By its superficial surface, with the integument, the Attrahens and 
 Attollens auriculam muscles, the temporal vessels and nerves, the aponeurosis of 
 the Occipito-frontalis, the temporal fascia, the zygoma, and Masseter; by its 
 deep surface, with the temporal fossa, the External pterygoid and part of the 
 Buccinator muscles, the internal maxillary artery and its deep temporal branches, 
 and the deep temporal nerves. Behind the tendon are the masseteric vessels and 
 nerve, and in front of it the buccal vessels and nerve. Its anterior border is sepa- 
 rated from the malar bone by a mass of fat. 
 
 Nerves. — Both muscles are supplied by the inferior maxillary nerve. 
 
THE PTEBYGO- MANDIBULAR REGION 383 
 
 10. The Pterygo-mandibular Region (Figs. 266, 267). 
 External pterygoid. Internal pterygoid. 
 
 Dissection. — The Temporal muscle having been examined, saw through the base of the 
 coronoid process, and draw it upward, together with the Temporal muscle, which should be 
 detached from the surface of the temporal fossa. Divide the ramus of the jaw just below the 
 condyle, and also, by a transverse incision extending across the middle, just above the dental 
 foramen; remove the fragment, and the Pterygoid muscles will be exposed. 
 
 The External Pterygoid Muscle (m. pterygoideus. extemus) is a short, thick 
 muscle, somewhat conical in form, which extends ahiiost horizontally between the 
 zygomatic fossa and the condyle of the jaw. It arises by two heads, separated 
 by a slight interval : the upper head arises from the inferior surface of the greater 
 wing of the sphenoid and from the pterygoid ridge, which separates the zygo- 
 matic from the temporal fossa ; the lower head from the outer surface of the external 
 pterygoid plate. Its fibres pass horizontally backward and outward, to be inserted 
 into a depression in front of the neck of the condyle of the lower jaw and into the 
 corresponding part of the interarticular fibro-cartilage. 
 
 Fig. 266. — The Pterygoid muscles, the zygomatic arch, and a portion of the ramus of the jaw having 
 
 been removed. 
 
 Relations. — By its external surface, with the ramus of the lower jaw, the internal 
 maxillary artery, which crosses it,^ the tendon of the Temporal muscle, and the 
 Masseter; by its internal surface it rests against the upper part of the Internal 
 pterygoid muscle, the internal lateral ligament, the middle meningeal artery, and 
 inferior maxillary nerve; by its upper border it is in relation with the temporal and 
 masseteric branches of the inferior maxillary nerve; by its lower border it is in 
 relation with the inferior dental and gustatory nerves. Through the interval 
 between the two portions of the muscle, the buccal nerve emerges and the internal 
 maxillary artery passes, when the trunk of this vessel lies on the muscle. 
 
 The Internal Pterygoid Muscle (m. pterygoideu^ internus) is a thick, quadri- 
 lateral muscle, and resembles the Masseter in form. It arises from the pterygoid 
 fossa, being attached to the inner surface of the external pterygoid plate and to 
 
 1 This is the usual relation, but in many cases the artery will be found below the muscle. 
 
384 
 
 THE 3IUSCLE8 AND FASCIA 
 
 the D-rooved surface of the tuberosity of the palate bone, and by a second sHp from 
 the outer surface of the tuberosities of the palate and superior maxillary bones; 
 its fibres pass downward, outward, and backward, to be inserted, by a strong, ten- 
 dinous lamina, into the lower and back part of the inner side of the ramus and 
 angle of the lower jaw, as high as the dental foramen. 
 
 Relations. — By its external surface, with the ramus of the lower jaw, from 
 which it is separated, at its upper part, by the External pterygoid muscle, the 
 internal lateral ligament, the internal maxillary artery, the dental vessels and 
 nerves, and the lingual nerve, and a process of the parotid gland. By its internal 
 surface, with the Tensor palati, being separated from the Superior constrictor of 
 the pharynx by a cellular interval. 
 
 Fig. 267. 
 
 -Pterygoid muscles, viewed from behind, the back portion of the skull having been removed. 
 
 (Testut.) 
 
 Nerves. — ^These muscles are supplied by the inferior maxillary nerve. 
 
 Actions.— The Temporal and Masseter and Internal pterygoid raise the lower 
 jaw against the upper with great force. The superficial portion of the Masseter 
 assists the External pterygoid in drawing the lower jaw forward upon the upper, 
 the jaw being drawn back again by the deep fibres of the Masseter and posterior 
 fibres of the Temporal. The External pterygoid muscles are the direct agents in 
 the trituration of the food, drawing the lower jaw directly forward, so as to make 
 the lower teeth project beyond the upper. If the muscle of one side acts, the 
 corresponding side of the jaw is drawn forward, and, the other condyle remaining 
 fixed, the symphysis deviates to the opposite side. The alternation of these move- 
 ments on the two sides produces trituration. 
 
3TUSCLES AND FASCIA OF THE NECK 335 
 
 Surface Form. — The outline of the muscles of the head and face cannot be traced on the 
 surface of the body, except in the case of two of the masticatory muscles. Those of the head 
 are thin, so that the outline of the bone is perceptible beneath them. Those in the face are 
 small, covered by soft skin, and often by a considerable layer of fat, so that their outline is con- 
 cealed, but they serve to round off and smooth prominent borders and to fill up what would be 
 otherwise . unsightly angular depressions. Thus, the Orbicularis palpebrarum rounds off the 
 prominent margin of the orbit, and the Pyramidalis nasi fills in the sharp depression beneath 
 the glabella, and thus softens and tones down the abrupt depression which is seen on the 
 unclothed bone. In like manner, the labial muscles, converging to the lips and assisted by the 
 superimposed fat, fill in the sunken hollow of the lower part of the face. Although the muscles 
 of the face are usually described as arising from the bones and inserted into the nose, lips, and 
 corners of the mouth, they have fibres inserted into the skin of the face along their whole 
 extent, so that almost every point of the skin of the face has its muscular fibre to move it; 
 hence it is that when in action the facial muscles produce alterations in the skin-surface, 
 giving rise to the formation of various folds or wrinkles, or otherwise altering the relative 
 position of the parts, so as to produce the varied expressions with which the face is endowed; 
 hence these muscles are termed the muscles of expression. The only two muscles in this 
 region which greatly influence surface form are the Masseter and the Temporal. The Masseter 
 is a quadrilateral muscle, which imparts fulness to the hinder part of the cheek. When the 
 muscle is firmly contracted, as when the teeth are clenched, its outline is plainly visible; 
 the anterior border forms a prominent vertical ridge, behind which is a considerable fulness, 
 especially marked at the lower part of the muscle; this fulness is entirely lost when the 
 mouth is opened and the muscle no longer in a state of contraction. The Temporal muscle 
 is fan-shaped, and fills the Temporal fossa, substituting for it a somewhat convex form, the 
 anterior part of which, on account of the absence of hair over the temple, is more marked than 
 the posterior, and stands out in strong relief when the muscle is in a state of contraction, 
 
 MUSCLES AND FASCIA OF THE NECK. 
 
 The muscles of the neck may be arranged into groups corresponding with the 
 region in which they are situated. 
 These groups are nine in number: 
 
 1. Superficial Cervical Region. 5. Muscles of the Pharynx. 
 
 2. Depressors of the Os Hyoideum 6. Muscles of the Soft Palate. 
 
 and Larynx. 7. Muscles of the Anterior Ver- 
 
 3. Elevators of the Os Hyoideum tebral Region. 
 
 and I..arynx. 8. Muscles of the Lateral Ver- 
 
 4. Muscles of the Tongue. tebral Region. 
 
 9. Muscles of the Larynx. 
 
 The muscles contained in each of these groups are the following: 
 
 \. Superficial Region. Lingual Region. 
 
 Platysma myoides. 
 Sterno-cleido-mastoid. 4. Muscles of the Tongue. 
 
 Infra-hyoid Region. Genio-hyo-glossus. 
 
 2. Depressors of Os hyoideum and Hyo-glossus. 
 
 Larynx. Chondro-glossus. 
 
 Sterno-hyoid. Stylo-glossus. 
 
 Sterno-thyroid. Palato-glossus. 
 
 Thyro-hyoid. 
 Omo-hyoid. 
 
 Supra-hyoid Region. 
 
 3. Elevators of Os hyoideum and Larynx. Inferior constrictor. 
 
 Digastric. Middle constrictor. 
 
 Stylo-hyoid. Superior constrictor. 
 
 Mylo-hyoid. Stylo-pharyngeus. 
 
 Genio-hyoid. Palato-pharyngeus. 
 
 25 
 
 5. Muscles of the Pharynx, 
 
386 THE MUSCLES AND FASCIA 
 
 6. Muscles of the Soft Palate. 8. Muscles of the Lateral Vertebral 
 Levator palati. Region. 
 
 Tensor palati. 
 
 Azygos uvulae. Scalenus anticus. 
 
 Palato-glossus. Scalenus medius. 
 
 Palato-pharyngeus. Scalenus posticus. 
 
 Salpingo-pliaryngeus. 
 
 7. Muscles of the A nteriorV ertehral Region. 
 
 Rectus capitis anticus major. ^ Muscles of the Larynx. 
 
 Rectus capitis anticus minor. 
 
 Rectus capitis lateralis. Included in description of the 
 
 Longus colli. Larynx. 
 
 1. The Superficial Cervical Region. 
 
 Platysma myoides. Sterno-cleido-mastoid. 
 
 Dissection. — A block having been placed at the back of the neck, and the face turned to 
 the side opposite that to be dissected, so as to place the parts upon the stretch, make two trans- 
 verse incisions: one from the chin, along the margin of the lower jaw, to the mastoid jjrocess, 
 and the other along the upper border of the clavicle. Connect these by an oblique incision 
 made in the course of the Sterno-mastoid muscle, from the mastoid process, to the sternum ; the 
 two flaps of integument having been removed in the direction shown in Fig. 257, the superficial 
 fascia will be exposed. 
 
 Superficial Cervical Fascia. — The superficial cervical fascia is a thin, apon- 
 eurotic lamina which is hardly demonstrable as a separate membrane. Beneath 
 it is found the Platysma myoides muscle. 
 
 The Platysma Myoides (m. 'platysma) (Fig. 260) is a broad, thin plane of mus- 
 cular fibres placed immediately beneath the superficial fascia on each side of the 
 neck. It arises by thin, fibrous bands from the fascia covering the upper part of the 
 Pectoral and Deltoid muscles ; its fibres pass over the clavicle and proceed obliquely 
 upward and inward along the side of the neck. The anterior fibres interlace, 
 below and behind the symphysis menti, with the fibres of the muscle of the oppo- 
 site side; the posterior fibres pass over the lower jaw, some of them being attached 
 to the bone below the external oblique line, others passing on to be inserted into 
 the skin and subcutaneous tissue of the lower part of the face, many of these fibres 
 blending with the muscles about the angle and lower part of the mouth. Some- 
 times fibres can be traced to the Zygomatic muscles or to the margin of the 
 Orbicularis oris. Beneath the Platysma the external jugular vein may be seen 
 descending in a line from the angle of the jaw to the middle of the clavicle. 
 
 Relations. — By its external surface, with the integument, to which it is united 
 moi'e closely below than above; by its internal surface, with the Pectoralis major 
 and Deltoid, and with the clavicle. In the neck, with the external and anterior 
 jugular veins, the deep cervical fascia, the superficial branches of the cervical 
 plexus, the Sterno-mastoid, Sterno-hyoid, Omo-hyoid, and Digastric muscles; 
 behind the Sterno-mastoid muscle it covers in the posterior triangle of the neck. 
 On the face it is in relation with the parotid gland, the facial artery and vein, 
 and the Masseter and Buccinator muscles. 
 
 Nerves. — ^The lower division of the facial nerve chiefly innervates this muscle, 
 and superficial branches from the cervical plexus also reach it. 
 
 Action. — The Platysma myoides produces a slight wrinkling of the surface of 
 the skin of the neck, in an oblique direction, when the entire muscle is brought 
 into action. Its anterior portion, the thickest part of the muscle, depresses the 
 lower jaw; it also serves to draw down the lower lip and angle of the mouth on 
 each side, being one of the chief agents in the expression of melancholy. In the 
 pressure upon the blood-vessels of the neck induced by strong inspiratory effort, 
 
THE SUPERFICIAL CERVICAL REGION 
 
 387 
 
 this muscle draws away the skin and fascia, and by so doing, greatly diminishes 
 the pressure on the veins. 
 
 Deep Cervical Fascia {jascia colli) (Fig. 268).— The deep cervical fascia 
 lies under cover of the Platysma myoides muscle and constitutes a complete 
 investment for the neck. It also forms a sheath for the carotid vessels, and, in 
 addition, is prolonged deeply in the shape of certain processes or lamellae, which 
 come into close relation with the structures situated in front of the vertebral column. 
 
 SPACE BETWEEN THE 
 TWO LAYERS OF FASCIA 
 
 STERNOTHYROID 
 
 DEEP FASCIA OF NECK 
 lOHYOID 
 
 OESOPHAGUS 
 
 PREVERTEBRAL 
 FASCIA 
 
 MOHYOID 
 
 COMMON CAROTID 
 ERV 
 
 DESCENDENS HYPO- 
 GLOSSI NERVE 
 
 PNEUMOGASTRIC 
 NERVE 
 
 LYMPHATIC 
 GLANDS 
 
 SYMPATHETIC 
 NERVE 
 PHRENIC 
 NERVE 
 INTERNAL 
 JUGULAR 
 VEIN 
 
 BRACHIAL 
 PLEXUS 
 
 SUPERFICIAL 
 FASCIA OF 
 NECK 
 
 Fig. 268. — Transverse section through the neck at the level of the seventh cervical vertebra. (Spalteholz.) 
 
 The investing portion of the fascia is attached, behind, to the ligamentum 
 nuchae and to the spine of the seventh cervical vertebra. Along this line it splits 
 to enclose the Trapezius muscle, at the anterior border of which the two enclosing 
 lamellie unite and form a strong membrane, which extends forward so as to roof 
 in the posterior triangle of the neck. Along the hinder edge of the Sterno-mastoid 
 the membrane divides to enclose this muscle, at the anterior edge of which it once 
 more forms a single lamellae, which roofs in the anterior triangle of the neck, 
 and, reaching forward to the middle line, is continuous with the corresponding 
 part from the opposite side of the neck. In the middle line of the neck it is attached 
 to the symphysis menti and to the body of the liyoid bone. 
 
388 THE MUSCLES AND FASCIA 
 
 AboDe, the fascia is attached to the superior curved Hne of the occiput, to the 
 mastoid process of the temporal, and to the whole length of the body of the jaw. 
 Opposite the angle of the jaw the fascia is very strong, and binds the anterior 
 edge of the Sterno-mastoid firmly to that bone. Between the jaw and the mastoid 
 process it ensheaths the parotid gland — the layer which covers the gland extending 
 upward under the name of the parotid fascia to be fixed to the zygomatic arch. 
 Thg parotid fascia is prolonged forward to cover the masseter muscle, the masse- 
 teric fascia. From the layer which passes under the parotid a strong band, 
 the stylo-mandibular ligament, reaches from the styloid process to the angle of 
 the jaw. The parotid and masseteric fascite constitute the fascia parotideo- 
 masseterica. 
 
 Below, the cervical fascia is attached to the acromion process, the clavicle, and 
 to the manubrium sterni. Some little distance above the last-named point, how- 
 ever, it splits into two layers, superficial and deep. The former is attached to 
 the anterior border of the manubrium, the latter to its posterior border and to 
 the interclavicular ligament. Between these two layers is a slit-like interval, the 
 suprasternal space or space of Bums (spatium swpr aster nale). It contains a small 
 quantity of areolar tissue, and sometimes a lymphatic gland; the lower portions 
 of the anterior jugular veins and their transverse connecting branch; and also 
 the sternal heads of the Sterno-mastoid muscles. 
 
 The fascia which lines the deep aspect of the Sterno-mastoid gives off certain 
 important processes, viz. : (1) A process to envelop the tendon of the Omo-hyoid, 
 and bind it down to the sternum and first costal cartilage. (2) A strong sheath, 
 the carotid sheath, for the large vessels of the neck, enclosed within which are the 
 carotid artery, internal jugular vein, the vagus, and descendens hypoglossi nerves. 
 (3) The prevertebral fascia {fascia prcevertebralis) , which extends inward behind 
 the carotid vessels, where it assists in forming their sheath, and passes in front 
 of the prevertebral muscles. It thus forms the posterior limit of a fibrous com- 
 partment which contains the larynx and trachea, the thyroid gland, and the 
 pharynx and oesophagus. The prevertebral fascia is fixed above to the base of 
 the skull, while below it is continued into the thorax in front of the Longus colli 
 muscles. Parallel to the carotid vessels and along their inner aspect it gives off 
 a thin lamina, the bucco-pharyngeal fascia (fascia buccopharyngea) , which closely 
 invests the constrictor muscles of the pharynx, and is continued forward from 
 the Superior constrictor on to the Buccinator. It is attached to the prever- 
 tebral layer by loose connective tissue only, and thus an easily distended space, 
 the retro-pharyngeal space (spatium retropharyjigea) , is found between them. This 
 space is limited above by the base of the skull, while below it extends behind the 
 oesophagus into the thorax, where it is continued into the posterior mediastinum. 
 The prevertebral fascia is prolonged downward and outward behind the carotid 
 vessels and in front of the Scaleni muscles, and forms a sheath for the brachial 
 plexus of nerves and for the subclavian vessels in the posterior triangle of the neck, 
 and, continuing under the clavicle as the axillary sheath, is attached to the deep 
 surface of the costo-coracoid membrane. Immediately above the clavicle an 
 areolar space exists between the investing layer and the sheath of the subclavian 
 vessels, and in it are found the lower part of the external jugular vein, the descend- 
 ing clavicular nerves, the suprascapular and transversalis colli vessels, and the 
 posterior belly of the Omo-hyoid muscle. This space extends downward behind 
 the clavicle, and is limited below by the fusion of the costo-coracoid membrane 
 with the anterior wall of the axillary sheath. (4) The pre-tracheal fascia, which 
 extends inward in front of the carotid vessels, and assists in forming the carotid 
 sheath. It is further continued behind the Depressor muscles of the hyoid bone, 
 and, after enveloping the thyroid body, is prolonged in front of the trachea to 
 meet the corresponding layer of the opposite side. Above, it is fixed to the hyoid 
 
THE INFRAHYOID REGION 39I 
 
 Actions. — When only one Sterno-mastoid muscle acts, it draws the head toward 
 the shoulder of the same side, assisted by the Splenius and the Obliquus capitis 
 inferior of the opposite side. At the same time it rotates the head so as to carry 
 the face toward the opposite side. When the two muscles act together they 
 flex the head upon the neck. If the head is fixed, the two muscles assist in 
 elevating the thorax in forced inspiration. 
 
 Surface Form. — The anterior edge of the muscle forms a very prominent ridge beneath the 
 skin, which it is important to notice, as it forms a guide to the surgeon in making the necessary 
 incisions for Hgature of the common carotid artery and for oesophagotomy. 
 
 Surgical Anatomy. — The relations of the sternal and clavicular parts of the Sterno-mastoid 
 should be carefully examined, as the surgeon is sometimes required to divide one or both portions 
 of the muscle in wry-neck (torticollis). One variety of this distortion is produced by spasmodic 
 contraction or rigidity of the Sterno-mastoid ; the head being carried down toward the shoulder 
 of the same side, and the face turned to the opposite side and fixed in that position. When there 
 is permanent shortening, subcutaneous division of the muscle is resorted to by some surgeons. 
 This is performed by introducing a tenotomy knife beneath it, close to its origin, and dividing 
 it from behind forward whilst the muscle is put well upon the stretch. There is seldom any 
 difficulty in dividing the sternal portion by making a puncture on the inner side of the tendon, 
 and then pushing a blunt tenotome behind it, and cutting forward. In dividing the clavicular 
 portion care must be taken to avoid wounding the external jugular vein, which runs parallel 
 with the posterior border of the muscle in this situation, or the anterior jugular vein, which 
 crosses beneath it. If the external jugular vein lies near the muscle, it is safer to make the 
 first puncture at the outer side of the tendon, and introduce a blunt tenotome from without 
 inward. Many surgeons prefer dividing the muscle by open incision, because by this method 
 all of the contracted fibres, muscular and facial, can be certainly and safely divided. An incision 
 is made over the origin of the muscle, the origin is exposed, a director is passed underneath it, 
 and it is then divided. With care and attention to asepsis this plan of treatment is devoid of 
 risk, and in this way the accidental division of vessels can be avoided. Some of the fibres of 
 the Sterno-mastoid muscle are occasionally torn during birth, especially in breech presenta- 
 tions; this is accompanied by hemorrhage and formation of a swelling within the substance of 
 the muscle. This by some is believed to be one of the causes of wry-neck, the scar tissue 
 which is formed contracting and shortening the muscle. 
 
 2. The Infra-hyoid Region (Figs. 269, 270). 
 Depressors of the Os Hyoideum and Larynx. 
 
 Sterno-hyoid. Thyro-hyoid. 
 
 Sterno-thyroid. Omo-hyoid. 
 
 Dissection. — The muscles in this region may be exposed by removing the deep fascia from the 
 front of the neck. In order to see the entire extent of the Omo-hyoid it is necessary to divide 
 the sterno-mastoid at its centre, and turn its ends aside, and to detach the Trapezius from the 
 clavicle and scapula. This, however, should not be done until the Trapezius has been dissected. 
 
 The Stemo-hyoid (m. sternohyoideus) is a thin, narrow, ribbon-like muscle, 
 which arises from the inner extremity of the clavicle, the posterior sterno- 
 clavicular ligament, and the upper and posterior part of the first piece of the 
 sternum ; passing upward and inward, it is inserted, by short, tendinous fibres, 
 into the lower border of the body of the hyoid bone. This muscle is separated, 
 below, from its fellow by a considerable interval; but the two muscles come into 
 contact with one another in the middle of their course, and from this upward 
 lie side by side. It sometimes presents, immediately above its origin, a trans- 
 verse tendinous intersection, like those in the Rectus abdominis. As a rule, 
 two bursse, the stemo-hyoid bursae (hursce sternohyoidii) , lie between the crico- 
 thyroid membrane, on one hand, and the Stemo-hyoid muscle and the cervical 
 fascia, on the other. Sometimes there is one large median bursa instead of two 
 lateral bursae. Not unusually there is no bursa at all. 
 
 Relations. — By its superficial surface, below, with the sternum, the sternal end 
 of the clavicle, and the Sterno-mastoid ; and above, with the Platysma and deep 
 cervical fascia; by its deep surface, with the Sterno-thyroid, Crico-thyroid, and 
 
392 
 
 THE MUSCLES AND FASCIA 
 
 Thyro-hyoid muscles, the thyroid gland, the superior thyroid vessels, the thyroid 
 cartilage, the crico-thyroid and thyro-hyoid membranes. 
 
 The Stemo-thyroid {m. sternoihyreoideus) is situated beneath the preceding 
 muscle, but is shorter and wider than it. It arises from the posterior surface of 
 the first piece of the sternum, below the origin of the Sterno-hyoid, and from the 
 edge of the cartilage of the first rib, occasionally of the second rib also, and is 
 inserted into the oblique line on the side of the ala of the thyroid cartilage. 
 This muscle is in close contact with its fellow at the lower part of the neck, and 
 is occasionally traversed by a transverse or oblique tendinous intersection, like 
 those in the Rectus abdominis. 
 
 Symphysis 
 of jaw. 
 
 Fig. 270. — Muscles of the neck. Anterior view. 
 
 Relations. — By its anterior surface, with the Sterno-hyoid, Omo-hyoid, and 
 Sterno-mastoid ; by its 'posterior surface, from below upward, with the trachea, 
 vena innominata, common carotid (and on the right side the arteria innominata), 
 the thyroid gland and its vessels, and the lower part of the larynx and pharynx. 
 The inferior thyroid vein lies along its inner border, a relation which it is impor- 
 tant to remember in the operation of tracheotomy. On the left side the deep 
 surface of the muscle is in relation to the oesophagus. 
 
 The Thyro-hyoid (m. thyreohyoideus) is a small, quadrilateral muscle appear- 
 ing like a continuation of the Stemo-thyroid. It arises from the oblique line on 
 the side of the thyroid cartilage, and passes vertically upward to be inserted into 
 the lower border of the body and greater cornu of the hyoid bone. The thyro- 
 hyoid bursse {hursce thyreohyoidii) lie inferior to the greater cornua of the hyoid 
 bone and upon the thyro-hyoid membrane. There is one bursa on each side 
 beneath the corresponding Thyro-hyoid muscle. 
 
 Relations. — By its external surface, with the Sterno-hyoid and Omo-hyoid 
 muscles; by its internal surface, with the thyroid cartilage, the thyro-hyoid mem- 
 brane, and the superior laryngeal vessels and nerve. 
 
THE SUPRA- HYOID REGION 393 
 
 The Omo-hyoid (m. omohyoideus) passes across the side of the neck, from 
 the scapula to the hyoid bone. It consists of two fleshy bellies, united by a 
 central tendon. It arises from the upper border of the scapula, and occasionally 
 from the transverse ligament which crosses the suprascapular notch, its extent of 
 attachment to the scapula varying from a few lines to an inch. From this origin 
 the posterior belly (venter inferior) forms a flat, narrow fasciculus, which inclines 
 forward and slightly upward across the lower part of the neck, behind the Sterno- 
 mastoid muscle, where it becomes tendinous; it then changes its direction, forming 
 an obtuse angle, and terminates in the anterior belly (venter superior), which 
 passes almost vertically upward, close to the outer border of the Sterno-hyoid, 
 to be inserted into the lower border of the body of the hyoid bone, just external to 
 the insertion of the Sterno-hyoid. The central tendon of this muscle, which varies 
 much in length and form, is held in position by a process of the deep cervical 
 fascia, which includes it in a sheath. This process is prolonged down, to be 
 attached to the clavicle and first rib. It is by this means that the angular form of 
 the muscle is maintained. 
 
 This muscle subdivides each of the two large triangles at the side of the neck 
 into two smaller triangles; the two posterior ones being the posterior superior or 
 occipital triangle, and the posterior inferior or subclavian triangle; the two anterior, 
 the anterior superior or superior carotid triangle, and the anterior inferior or inferior 
 carotid triangle. 
 
 Relations. — By its superficial surface, with the Trapezius, the Sterno-mastoid, 
 deep cervical fascia, Platysma, and integument; by its deep surface, with the 
 Scaleni muscles, phrenic nerve, lower cervical nerves, which go to form the brachial* 
 plexus, the suprascapular vessels and nerve, sheath of the common carotid artery 
 and internal jugular vein, the Sterno-thyroid and Thyro-hyoid muscles. 
 
 Nerves. — The Thyro-hyoid is supplied by the hypoglossal; the other muscles 
 of this group by branches from the loop of communication between the descendens 
 and communicans hypoglossi. 
 
 Actions. — ^These muscles depress the larynx and hyoid bone, after they have 
 been drawn up with the pharynx in the act of deglutition. The Omo-hyoid 
 muscles not only depress the hyoid bone, but carry it backward and to one side. 
 It is concerned especially in prolonged inspiratory efforts; for by tensing the 
 lower part of the cervical fascia it lessens the inward suction of the soft parts, 
 which would otherwise compress the great vessels and the apices of the lungs. 
 This action is synergistic with that of the Platysma. The Thyro-hyoid may act 
 as an elevator of the thyroid cartilage when the hyoid bone ascends, drawing 
 upward the thyroid cartilage, behind the hyoid bone. The Sterno-thyroid acts as 
 a depressor of the thyroid cartilage. 
 
 3. The Supra-hyoid Region (Figs. 269, 270). 
 
 Elevators of the Os Hyoideum — Depressors of the Lower Jaw. 
 
 Digastric. Mylo-hyoid. 
 
 Stylo-hyoid. Genio-hyoid. 
 
 Dissection. — To dissect these muscles a block should be placed beneath the back of the 
 neck, and the head drawn backward and retained in that position. On the removal of the deep 
 fascia the muscles are at once exposed. 
 
 The Digastric (m. digastricus) consists of two fleshy bellies united by an inter- 
 mediate, rounded tendon. It is a small muscle, situated below the side of the 
 body of the lower jaw, and extending, in a curved form, from the side of the 
 head to the symphysis of the jaw. The posterior belly (venter posterior) , longer 
 than the anterior, arises from the digastric groove on the inner side of the mas- 
 toid process of the temporal bone, and passes downward, forward, and inward. 
 
394 THE MUSCLES AND FASCIA 
 
 The anterior belly {venter anterior) arises from a depression on the inner side 
 of the lower border of the jaw, close to the symphysis, and passes downward 
 and backward. The two bellies terminate in the central tendon which per- 
 forates the Stylo-hyoid, and is held in connection with the side of the body 
 and the greater cornu of the hyoid bone by a fibrous loop, lined by a synovial 
 membrane. A broad aponeurotic layer is given off from the tendon of the 
 Digastric on each side, which is attached to the body and great cornu of the 
 hyoid bone: this is termed the supra-hyoid aponeurosis. It forms a strong layer 
 of fascia between the anterior portion of the two muscles, and a firm investment 
 for the other muscles of the supra-hyoid region which lie deeper. 
 
 The Digastric muscle divides the anterior superior triangle of the neck into 
 two smaller triangles; the upper, or submaxillary triangle, being bounded, above, by 
 the lower border of the body of the jaw, and a line drawn from its angle to the 
 mastoid process; below, by the posterior belly of the Digastric and the Stylo- 
 hyoid muscles ; in front, by the middle line of the neck and the anterior belly of the 
 Digastric, the lower or superior carotid triangle being bounded above by the poste- 
 rior belly of the Digastric, behind by the Sterno-mastoid, below by the anterior 
 belly of the Omo-hyoid, 
 
 Relations. — By its superficial surface, with the mastoid process, the Platysma,. 
 Sterno-mastoid, part of the Splenius, Trachelo-mastoid, and Stylo-hyoid muscles, 
 and the parotid gland. By its deep surface, the anterior belly lies on the Mylo- 
 hyoid; the posterior belly on the Stylo-glossus, Stylo-pharyngeus, and Hyo-glossus 
 muscles, the external carotid artery and its occipital, lingual, facial, and ascending 
 pharyngeal branches, the internal carotid artery, internal jugular vein, and hypo- 
 glossal nerve. 
 
 The Stylo-hyoid (m. stylohyoideus) is a small, slender muscle, lying in front 
 of, and above, the posterior belly of the Digastric. It arises from the back and 
 outer surface of the styloid process of the temporal bone, near the base; andy 
 passing downward and forward, is inserted into the body of the hyoid bone,^ 
 just at its junction with the greater cornu, and immediately above the Omo- 
 hyoid, This muscle is perforated, near its insertion, by the tendon of the 
 Digastric, 
 
 Relations. — By its superficial surface above with the parotid gland and deep 
 cervical fascia; below it is superficial, being situated immediately beneath the deep 
 cervical fascia. By its deep surface, with the posterior belly of the Digastric, the 
 external carotid artery, with its lingual and facial branches, the Hyo-glossus 
 muscle, and the hypoglossal nerve. 
 
 The Stylo-hyoid Ligament {ligamentum stylohyoideus) . — In connection with the 
 Stylo-hyoid muscle may be described a ligamentous band, the stylo-hyoid ligament. 
 It is a fibrous cord, often containing a little cartilage in its centre, which continues 
 the styloid process down to the hyoid bone, being attached to the tip of the former 
 and the small cornu of the latter. It is often more or less ossified, and in many 
 animals forms a distinct bone, the epihyal. 
 
 The anterior belly of the Digastric should be removed, in order to expose the next muscle. 
 
 The Mylo-hyoid (m. mylohyoideus) (Fig. 271) is a flat, triangular muscle^ 
 situated immediately beneath the anterior belly of the Digastric, and forming, 
 with its fellow of the opposite side, a muscular floor for the cavity of the mouth- 
 It arises from the whole length of the mylo-hyoid ridge of the lower jaw, extend- 
 ing from the symphysis in front to the last molar tooth behind. The posterior 
 fibres pass inward and slightly downward, to be inserted into the body of the 
 hyoid bone. The middle and anterior fibres are inserted into a median fibrous 
 raphe, extending from the symphysis of the lower jaw to the hyoid bone, where 
 they join at an angle with the fibres of the opposite muscle. The median raph^ 
 
THE SUPRA- HYOID REGION 
 
 395 
 
 is sometimes wanting; the muscular fibres of the two sides are then directly 
 continuous with one another. 
 
 Relations. — By its cutaneous or under surface, with the Platysma, the anterior 
 belly of the Digastric, the supra-hyoid aponeurosis, the submaxillary gland, sub- 
 mental vessels, and mylo-hyoid vessels and nerve; by its deep or superior surface, 
 with the Genio-hyoid, part of the Hyo-glossus and Stylo-glossus muscles, the hypo- 
 glossal and lingual nerves, the submaxillary ganglion, the sublingual gland, the 
 deep portion of the submaxillary gland, and Wharton's duct; the sublingual and 
 ranine vessels, and the buccal mucous membrane. 
 
 Dissection. — The Mylo-hvoid should now be removed, in order to expose the muscles which 
 lie beneath; this is effected by reflecting it from its attachments to the hyoid bone and jaw, and 
 separating it by a vertical incision from its fellow of the opposite side. 
 
 Fig. 271. — Mylo-hyoid muscle. (Poirier and Charpy.) 
 
 The Genio-hyoid (m. geniohijoideus) (Fig. 272) is a narrow, slender muscle, 
 situated immediately beneath^ the inner border of the preceding. It arises from 
 the inferior genial tubercle on the inner side of the symphysis of the jaw, and 
 passes downward and backward, to be inserted into the anterior surface of the 
 body of the hyoid bone. This muscle lies in close contact with its fellow of the 
 opposite side, and increases slightly in breadth as it descends. 
 
 Relations. — It is covered by the Mylo-hyoid and lies along the lower border 
 of the Genio-hyo-glossus. 
 
 Nerves. — The anterior belly of the Digastric is supplied by the mylo-hyoid 
 branch of the inferior dental; its posterior belly, by the facial; the Stylo-hyoid 
 is supplied by the facial; the Mylo-hyoid, by the mylo-hyoid branch of the 
 inferior dental; the Genio-hyoid, by the hypoglossal. 
 
 Actions. — This group of muscles performs two very important actions. They 
 raise the hyoid bone, and with it the base of the tongue, during the act of degluti- 
 tion; or, when the hyoid bone is fixed by its depressors and those of the larynx, 
 they depress the lower jaw. During the first act of deglutition, when the mass 
 is being driven from the mouth into the pharynx, the hyoid bone, and with it the 
 tongue, is carried upward and forward by the anterior belly of the Digastric, the 
 Mylo-hyoid, and Genio-hyoid muscles. In the second act, when the mass is pass- 
 
 1 This refers to the depth of the muscles from the skin in the order of dissection. In the erect position of 
 the body the Genio-hyoid is above the Mylo-hyoid. 
 
396 
 
 THE MUSCLES AND FASCIjE 
 
 ing through the pharynx, the direct elevation of the hyoid bone takes place by the 
 combined action of all the muscles; and after the food has passed, the hyoid bone 
 is carried upward and backward by the posterior belly of the Digastric and Stylo- 
 hyoid muscles, which assist in preventing the return of the morsel into the mouth. 
 
 4. The Lingual Region (Figs. 272, 273, 274). 
 
 Genio-hyo-glossus. Stylo-glossus. 
 
 Hyo-glossus. Palato-glossus. 
 
 Chondro-glossus. 
 
 Dissection. — After completing the dissection of the preceding muscles, saw through the 
 lower jaw just external to the symphysis. Then draw the tongue forward, and attach it, by a 
 stitch, to the nose; when its muscles, which are thus put on the stretch, may be examined. 
 
 Fig. 272. — Muscles of the tongue. Left side. 
 
 The Gsnio-hyo-glossus (m. genioglossus) has received its name from its triple 
 attachment to the jaw, hyoid bone, and tongue, but it is better to name it the 
 Genio-glossus, since its attachment to the hyoid bone is very slight or altogether 
 absent. It is a flat, triangular muscle, placed vertically on either side of the 
 middle line, its apex corresponding with its point of attachment to the lower jaw, its 
 base with its insertion into the tongue and hyoid bone. It arises by a short tendon 
 from the superior genial tubercle on the inner side of the symphysis of the jaw, im- 
 mediately above the Genio-hyoid ; from this point the muscle spreads out in a fan- 
 like form, a few of the inferior fibres passing downward, to be attached by a thin 
 aponeurosis into the upper part of the body of the hyoid bone, a few fibres passing 
 between the Hyo-glossus and Chondro-glossus to blend with the Constrictor mus- 
 cles of the pharynx; the middle fibres passing backward, and the superior ones 
 upward and forward, to enter the whole length of the under surface of the tongue, 
 from the base to the apex. The two muscles lie on either side of the median plane; 
 
THE LING UAL REGION 
 
 397 
 
 behind (Fig. 273), they are quite distinct from each other, and are separated at 
 their insertion into the under surface of the tongue by a tendinous raph^, which 
 extends through the middle of the organ; in front, the two muscles are more or 
 less blended: distinct fasciculi are to be seen passing off from one muscle, 
 crossing the middle line, and intersecting with bundles of fibres derived from 
 the muscle on the other side. 
 
 Relations. — By its internal surface it is in contact with its fellow of the opposite 
 side; by its external surface, with the Inferior lingualis, the Hyo-glossus, the lin- 
 gual artery and hypoglossal nerve, the lingual 
 nerve, and sublingual gland; by its upper bor- 
 der, with the mucous membrane of the floor of 
 the mouth (frtenum linguae) ; by its lower border 
 with the Genio-hyoid. 
 
 The Hyo-glossus (m. hyoglossv^) is a thin, 
 flat, quadrilateral muscle which arises from the 
 side of the body and whole length of the greater 
 cornu of the hyoid bone, and passes almost ver- 
 tically upward to enter the side of the tongue, 
 between the Stylo-glossus and Lingualis. Those 
 fibres of this muscle which arise from the body 
 are directed upward and backward, overlajv 
 ping those arising from the greater cornu, which 
 are directed upward and forward. 
 
 Relations. — By its external surface, with the 
 Digastric, the Stylo-hyoid, Stylo-glossus, and 
 Mylo-hyoid muscles, the submaxillary ganglion, 
 the lingual and hypo-glossal nerves, Wharton's 
 duct, the ranine vein, the sublingual gland, and 
 the deep portion of the submaxillary gland. By 
 its deep surface, with the Stylo-hyoid ligament, 
 the Genio-hyo-glossus, Lingualis, and Middle 
 constrictor, the lingual vessels, and the glosso- 
 pharyngeal nerve. 
 
 The Chondro-glossus (to. chondroglossus) is 
 a distinct muscular slip, though it is sometimes 
 described as a part of the Hyo-glossus, from 
 which, however, it is separated by the fibres of 
 the Genio-hyo-glossus, which pass to the side of 
 
 the pharynx. It is about three-quarters to an inch in length, and arises from the 
 inner side and base of the lesser cornu and contiguous portion of the body of the 
 hyoid bone, and passes directly upward to blend with the intrinsic muscular 
 fibres of the tongue, between the Hyo-glossus and Genio-hyo-glossus. A small 
 slip of muscular fibre is occasionally found, arising from the cartilago triticia 
 in the thyro-hyoid ligament, and passing upward and forward to enter the 
 tongue with the hindermost fibres of the Hyo-glossus. 
 
 The Stylo-glossus (to. styloglossus), the shortest and smallest of the three styloid 
 muscles, arises from the anterior and outer side of the styloid process, near its apex, 
 and from the stylo-mandibular ligament, to which its fibres, in most cases, are 
 attached by a thin aponeurosis. Passing downward and forward between the inter- 
 nal and external carotid arteries, and becoming nearly horizontal in its direction, 
 it divides upon the side of the tongue into two portions: one longitudinal, which 
 enters the side of the tongue near its dorsal surface, blending with the fibres of the 
 Lingualis in front of the Hyo-glossus; the other oblique, which overlaps the 
 Hyoglossus muscle and decussates with its fibres. 
 
 CHONDRO-GLOSSUS. 
 
 Fig. 273. — Muscles of the tongue from be~ 
 low. (From a preparation in the Museum of 
 the Royai College of Surgeons of England.) 
 
THE MUSCLES AND FASCIA 
 
 Relations. — By its external surface, from above downward, with the parotid 
 gland, the Internal pterygoid muscle, the lingual nerve, and the mucous membrane 
 of the mouth; by its internal surface, with the tonsil, the Superior constrictor, and 
 the Hyo-glossus muscle. 
 
 The Palato-glossus or Constrictor Isthmi Faucium (m. glossopalatinus) , 
 although it is one of the muscles of the tongue, serving to draw its base upward 
 during the act of deglutition, is more nearly associated with the soft palate, both 
 in its situation and function ; it will consequently be described with that group of 
 muscles. 
 
 Nerves. — The Palato-glossus is probably innervated by the spinal accessory 
 nerve, through the pharyngeal plexus; the remaining muscles of this group, by the 
 hypo-glossal. 
 
 Muscular Substance of the Tongue (Figs. 273, 274, and 275).— The muscular 
 fibres of the tongue run in various directions. These fibres are divided into two 
 sets — Extrinsic and Intrinsic. The extrinsic muscles of the tongue are those 
 which have their origin external, and only their terminal fibres contained in the 
 substance of the organ. They are: the Stylo-glossus, the Hyo-glossus, the Palato- 
 glossus, the Genio-hyo-glossus, and part of the 
 Superior constrictor of the pharynx (Pharyngeo- 
 glossus). The intrinsic muscles are those which 
 are contained entirely within the tongue, and 
 form the greater part of its muscular struc- 
 ture. 
 
 / 9 
 
 CUT EDGE OF SUPERIOR LINGUALIS. 
 
 Fig. 274. — Muscles on the dorsum of the 
 tongue. 
 
 ■'""'iiJ/Zllli 
 
 Fig. 275. — ;Coronal section of tongue. Showing intrinsic 
 muscles, a. lingual artery; b. Inferior lingualis, cut through; 
 C, fibres of Hyo-glossus; d. oblique fibres of Stylo-glo.ssus; e, in- 
 sertion of Transverse lingualis; /, Superior lingualis; fir, papillae 
 to tongue; h, vertical fibres of Genio-hyo-glossus intersecting 
 Transverse lingualis; i, septum. (Altered from Krause.) 
 
 The tongue consists of symmetrical halves separated from each other in the 
 middle line by a fibrous septum (septum linguoe). Each half is composed of 
 muscular fibres arranged in various directions, containing much interposed fat, 
 and supplied by vessels and nerves. 
 
 To demonstrate the various fibres of the tongue, the organ should be subjected to 
 prolonged boiling, in order to soften the connective tissue; the dissection may then 
 be commenced from the dorsum (Figs. 274 and 275). Immediately beneath the 
 mucous membrane is a submucous, fibrous layer, into which the muscular fibres 
 which terminate on the surface of the tongue are inserted. Upon removing this, 
 
THE LINGUAL REGION 399 
 
 with the mucous membrane, the first stratum of muscular fibres is exposed. 
 This belongs to the group of intrinsic muscles, and has been named the Superior 
 lingualis {m. longitudinalis superior). It consists of a thin layer of oblique and 
 longitudinal fibres which arise from the submucous fibrous layer, close to the 
 Epiglottis, and from the fibrous septum, and pass forward and outward to the 
 edges of the tongue. Between its fibres pass some vertical fibres derived from 
 the Genio-hyo-glossus and from the vertical intrinsic muscle, which will be de- 
 scribed later on. Beneath this layer is the second stratum of muscular fibres, 
 derived principally from the extrinsic muscles. In front it is formed by the fibres 
 derived from the Stylo-glossus, running along the side of the tongue, and sending 
 one set of fibres over the dorsum which run obliquely forward and inward to the 
 middle line, and another set of fibres seen at a later period of the dissection, on to 
 the under surface of the sides of the anterior part of the tongue, which run forward 
 and inward, between the fibres of the Hyo-glossus, to the middle line. Behind this 
 layer of fibres, derived from the Stylo-glossus, are fibres derived from the Hyo- 
 glossus, assisted by some few fibres of the Palato-glossus. The Hyo-glossus, enter- 
 ing the side of the under surface of the tongue, between the Stylo-glossus and 
 Inferior lingualis, passes round its margin and spreads out into a layer on the dor- 
 sum, which occupies the middle third of the organ, and runs almost transversely 
 inward to the septum. It is reinforced by some fibres from the Palato-glossus; 
 other fibres of this muscle pass more deeply and intermingle with the next layer. 
 The posterior part of the second layer of the muscular fibres of the tongue is 
 derived from those fibres of the Hyo-glossus which arise from the lesser cornu of 
 thehyoid bone, and are here described as a separate muscle — theChondro-glossus. 
 The fibres of this muscle are arranged in a fan-shaped manner, and spread out over 
 the posterior third of the tongue. Beneath this layer is the great mass of the intrin- 
 sic muscles of the tongue, intersected at right angles by the terminal fibres of one of 
 the extrinsic muscles — the Genio-hyo-glossus. This portion of the tongue is paler 
 in color and softer in texture than that already described, and is sometimes 
 designated the medullary portion in contradistinction to the firmer superficial part, 
 which is termed the cortical portion. It consists largely of transverse fibres, the 
 Transverse lingualis (m. iransversus lingua;), and of vertical fibres, the Vertical 
 lingualis (m. veriicdis lingua'). The Transverse lingualis forms the.largest portion 
 of the third layer of muscular fibres of the tongue. The fibres arise from the 
 median septum, and pass outward to be inserted into the submucous fibrous layer 
 at the sides of the tongue. Intermingled with these transverse intrinsic fibres are 
 transverse extrinsic fibres derived from the Palato-glossus and the Superior con- 
 strictor of the pharynx. These transverse extrinsic fibres, however, run in the 
 opposite direction, passing inward toward the septum. Intersecting the transverse 
 fibres are a large number of vertical fibres derived partly from the Genio-hyo- 
 glossus and partly from intrinsic fibres, the Vertical lingualis. The fibres derived 
 from the Genio-hyo-glossus enter the under surface of the tongue on each side of 
 the median septum from base to apex. They ascend in a radiating manner to the 
 dorsum, being inserted into the submucous fibrous layer covering the tongue on 
 each side of the middle line. The Vertical lingualis is found only at the borders 
 of the forepart of the tongue, external to the fibres of the Genio-hyo-glossus. 
 Its fibres extend from the upper to the under surface of the organ, decussating 
 with the fibres of the other muscles, and especially with the Transverse lingualis. 
 The fourth layer of muscular fibres of the tongue consists partly of extrinsic fibres 
 derived from the Stylo-glossus, and partly of intrinsic fibres, the Inferior lingualis 
 (m. longitudinalis inferior). At the sides of the under surface of the organ are 
 some fibres derived from the Stylo-glossus, which, as it runs forward at the side of 
 the tongue, gives off fibres which, passing forward and inward between the fibres 
 of the Hyo-glossus, form an inferior oblique stratum which joins in front with the 
 
400 THE MUSCLES AND FASCIA 
 
 anterior fibres of the Inferior lingualis. The Inferior Ungualis is a longitudinal 
 band, situated on the under surface of the tongue, and extending from the base to 
 the apex of the organ. Behind, some of its fibres are connected with the body of 
 the hyoid bone. It Hes between the Hyo-glossus and the Genio-hyo-glossus, and 
 in front of the Hyo-glossus it enters into relation with the Stylo-glossus, with the 
 fibres of which it blends. It is in relation by its under surface with the ranine 
 artery. 
 
 Surgical Anatomy. — The fibrous septum which exists between the two halves of the tongue 
 is very complete, so that the anastomosis between the two lingual arteries is not very free, 
 a fact often illustrated by injecting one-half of the tongue with colored size, while the other 
 half is left uninjected or is injected with size of a different color. 
 
 This is a point of considerable importance in connection with removal of one-half of the 
 tongue for cancer, an operation which is now frequently resorted to when the disease is strictly 
 confined to one side of the anterior portion of the tongue. If the mucous membrane is divided 
 longitudinally exactly in the middle line, the tongue can be split into halves along the median 
 raphe without any appreciable hemorrhage, and the diseased half can then be removed. 
 
 Actions. — The movements of the tongue, although numerous and complicated,^ 
 may be understood by carefully considering the direction of the fibres of its 
 muscles. The Genio-hyo-glossi muscles, by means of their posterior fibres, draw 
 the base of the tongue forward, so as to protrude the apex from the mouth. The 
 anterior fibres draw the tongue back into the mouth. The whole length of these 
 two muscles, acting along the middle line of the tongue, draw it downward, so as to 
 make it concave from side to side, forming a channel along which fluids may pass 
 toward the pharynx, as in sucking. The Hyo-glossi muscles depress the tongue 
 and draw down its sides, so as to render it convex from side to side. The Stylo- 
 glossi muscles draw the tongue upward and backward. The Palato-glossi muscles 
 draw the base of the tongue upward. With regard to the intrinsic muscles, both 
 the Superior and Inferior linguales tend to shorten the tongue, but the former, in 
 addition, turn the tip and sides upward so as to render the dorsum concave, while 
 the latter pull the tip downward and cause the dorsum to become convex. The 
 Transverse lingualis narrows and elongates the tongue, and the Vertical lingualis 
 flattens and broadens it. The complex arrangement of the muscular fibres of 
 the tongue, and the various directions in which they run, give to this organ the 
 power of assuining the various forms necessary for the enunciation of the different 
 consonantal sounds; and Dr. Macalister states that "there is reason to believe 
 that the musculature of the tongue varies in different races owing to the hereditary 
 practice and habitual use of certain motions required for enunciating the several 
 vernacular languages." 
 
 5. The Pharyngeal Region (Figs. 276, 277, 278). 
 
 Inferior constrictor. Superior constrictor. 
 
 Middle constrictor. Stylo-pharyngeus. 
 
 Palato-pharyngeus. 1 .^ , x- \ 
 
 c^ ^ • ■> r (See next section.) 
 
 Salpmgo-pharyngeus. J ^ 
 
 Dissection (Fig. 276). — In order to examine the muscles of the pharynx, cut through the 
 trachea and oesophagus just above the sternum, and draw them upward by dividing the loose 
 areolar tissue connecting the pharynx with the front of the vertebral column. The parts being 
 drawn well forward, apply the edge of the saw immediately behind the styloid processes, and 
 saw the base of the skull through from below upward. The pharynx and mouth should then 
 be stuffed with tow, in order to distend its cavity and render the muscles tense and easier of 
 dissection. 
 
 The Inferior Constrictor (w. constrictor pharipigis inferior), the most superficial 
 and thickest of the three constrictors, arises from the sides of the cricoid and 
 thyroid cartilages. To the cricoid cartilage it is attached in the interval between 
 
THE PHARYNGEAL REGION 
 
 401 
 
 the Crico-thyroid muscle in front and the articular facet for the thyroid cartilage 
 behind. To the thyroid cartilage it is attached to the oblique line on the side of 
 the great ala, the cartilaginous surface behind it, nearly as far as its posterior border, 
 and to the inferior cornu. From these attachments the fibres spread backward and 
 inward, to be inserted into the fibrous raphd in the posterior median line of the 
 pharynx. The inferior fibres are horizontal, and continuous with the fibres of the 
 oesophagus : the rest ascend, increasing in obliquity, and overlap the Middle con^ 
 stricter. 
 
 Relations. — It is covered by a thin membrane which surrounds the entire 
 pharynx, bucco-pharyngeal fascia (fascia buccopharyngea) . Behind, it is in 
 relation with the vertebral column 
 and the prevertebral fascia and mus- 
 cles; laterally, with the thyroid gland, 
 the common carotid artery, and the 
 Sterno-thyroid muscle; by its internal 
 surface, with the Middle constrictor, 
 the Stylo-pharyngeus, Palato-pharyn- 
 geus, the fibrous coat and mucous 
 membrane of the pharynx. The in- 
 ternal laryngeal nerve and the laryn- 
 geal branch of the Superior Thyroid 
 artery pass near the upper border, and 
 the inferior, or recurrent laryngeal 
 nerve, and the laryngeal branch of the 
 Inferior Thyroid artery, beneath the 
 lower border of this muscle, previous to 
 their entering the larynx. 
 
 The Middle Constrictor (m. constric- 
 tor jyharyngis medius) is a flattened, 
 fan-shaped muscle, smaller than the 
 preceding. It arises from the whole 
 length of the . upper border of the 
 greater cornu of the hyoid bone, from 
 the lesser cornu, and from the stylo- 
 hyoid ligament. The fibres diverge 
 from their origin, the lower ones de- 
 scending beneath the Inferior con- 
 stricter, the middle fibres passing 
 transversely, and the upper fibres ascending and overlapping the Superior con- 
 strictor. The muscle is inserted into the posterior median fibrous raphe, blending 
 in the middle line with the one of the opposite side. 
 
 Relations. — Between this muscle and the Superior constrictor are the glosso- 
 pharyngeal nerve, the Stylo-pharyngeus muscle and the stylo-hyoid ligament; 
 and between it and the Inferior constrictor is the superior laryngeal nerve. 
 Behind, it lies on the vertebral column, the Longus colli, and the Rectus capitis 
 anticus major. On each side it is in relation with the carotid vessels, the pharyn- 
 geal plexus, and some lymphatic glands. Near its origin it is covered by the 
 Hyo-glossus, the lingual vessels being placed between the two muscles. It lies 
 upon the Superior constrictor, the Stylo-pharyngeus, the Palato-pharyngeus, the 
 fibrous coat, and the mucous membrane of the larynx. 
 
 The Superior Constrictor (to. constrictor pharyngis superior) is a quadrilateral 
 muscle, thinner and paler than the other constrictors, and situated at the upper 
 part of the pharynx. It arises from the lower third of the posterior margin of the 
 internal pterygoid plate and its hamular process, from the contiguous portion of the 
 
 26 
 
 Fig. 276. — Muscles of the pharynx. External view. 
 
402 
 
 THE 3fUSCLES AND FASCIA 
 
 palate bone and the reflected tendon of the Tensor palati muscle, from the pterygo- 
 maxillary ligament, from the alveolar process above the posterior extremity of the 
 mylo-hyoid ridge, and by a few fibres from the side of the tongue. From these 
 points the fibres curve backward, to be inserted into the median raphe, being also 
 prolonged by means of a fibrous aponeurosis to the pharyngeal spine on the basilar 
 process of the occipital bone. The superior fibres arch beneath the I^evator palati 
 and the Eustachian tube, the interval between the upper border of the muscle and 
 the basilar process being deficient in muscular fibres and closed by a portion 
 of the pharyngeal aponeurosis [fascia pharyngobasilaris) . This interval is known as 
 the sinus of Morgagni. 
 
 ACCESSORY BUN 
 FROM PETROSA 
 TION OF TEMPOI 
 
 STYLOID PROC 
 
 EXPANSION OF 
 STYLO-PHARYNGEUS 
 
 g EXPANSION OF 
 
 PALATO-PHARYNGEUS 
 
 Fig. 277. — The muscles of the pharynx. On the right side most of the inferior constrictor has been removed, 
 on the left side the Digastric and Stylo-hyoid have been removed. (Spalteholz.) 
 
 Relations. — By its outer surface, with the prevertebral fascia and muscles, 
 the vertebral column, the internal carotid and ascending pharyngeal arteries, the 
 internal jugular vein and pharyngeal venous plexus, the glosso-pharyngeal, pneu- 
 mogastric, spinal accessory, hypoglossal, lingual, and sympathetic nerves, the 
 Middle constrictor and Internal pterygoid muscles, the Styloid process, the Stylo- 
 
THE PALATAL REGION 403 
 
 hyoid ligament, and the Stylo-pharyngeus. By its internal surface, with the 
 Palato-pharyngeus, the tonsil, the fibrous coat and mucous membrane of the 
 pharynx. 
 
 The Stylo-pharyngeus (m. stylopharyngeus) is a long, slender muscle, round 
 above, broad and thin below. It arises from the inner side of the base of the 
 styloid process of the temporal bone, passes downward along the side of the 
 pharynx between the Superior and Middle constrictors, and spreads out beneath 
 the mucous membrane, where some of its fibres are lost in the Constrictor muscles; 
 and others, joining with the Palato-pharyngeus, are inserted into the posterior 
 border of the thyroid cartilage. The glosso-pharyngeal nerve runs on the outer 
 side of this muscle, and crosses over it in passing forward to the tongue. 
 
 Relations. — Externally, with the Stylo-glossus muscle, the parotid gland, the 
 external carotid artery, and the ^Middle constrictor; internally, with the internal 
 carotid, the internal jugular vein, the Superior constrictor, Palato-pharyngeus, 
 and mucous membrane. 
 
 Nerves.— The Constrictors are supplied by branches from the pharyngeal 
 plexus. The Inferior constrictor also receives an additional branch from the 
 external laryngeal nerve and one frcm the recurrent laryngeal. The Stylo- 
 pharyngeus is supplied by the glosso-pharyngeal nerve. 
 
 Actions. — When deglutition is about to be performed, the pharynx is drawn 
 upward and dilated in different directions, to receive the morsel propelled into it 
 from the mouth. The Stylo-pharyngei, which are much farther removed from 
 one another at their origin than at their insertion, draw the sides of the pharynx 
 upward and outward, and so increase its transverse diameter, its breadth in the 
 antero-posterior direction being increased by the larynx and tongue being carried 
 forward in their ascent. As soon as the morsel is received in the pharynx, the 
 Elevator muscles relax, the bag descends, and the Constrictors contract upon 
 the morsel, and convey it gradually downward into the oesophagus. Besides its 
 action in deglutition, the pharynx also exerts an important influence in the modu- 
 lation of the voice, especially in the production of the higher tones. 
 
 6. The Palatal Region (Fig. 278.) 
 
 Levator palati. Palato-glossus. 
 
 Tensor palati. Palato-pharyngeus. 
 
 Azygos uvulae. Salpingo-pharyngeus. 
 
 Dissection (Fig. 278). — Lay open the pharynx from behind by a vertical incision extending 
 from its upper to its lower part, and partially divide the occipital attachment by a transverse 
 incision on each side of the vertical one; the posterior surface of the soft palate is then exposed. 
 Having fixed the uvula so as to make it tense, the mucous membrane and glands should be 
 carefully removed from the posterior surface of the soft palate, and the muscles of this part 
 are at once exposed. 
 
 The Levator Palati (m. levator veil palatini) is a long, thick, rounded muscle, 
 placed on the outer side of the posterior nares. It arises from the under surface of 
 the apex of the petrous portion of the temporal bone, and from the inner surface 
 of the cartilaginous portion of the Eustachian tube; after passing into the pharynx, 
 above the upper concave margin of the Superior constrictor, it passes obliquely 
 downward and inward, its fibres spreading out in the soft palate as far as the 
 middle line, where they blend with those of the opposite side. 
 
 Relations. — Externally, with the Tensor palati and Superior constrictor and 
 Eustachian tube; internally, with the mucous membrane of the pharynx; pos- 
 teriorly, with the posterior fasciculus of the Palato-pharyngeus, the Azygos uvulae, 
 and the mucous lining of the soft palate. 
 
404 
 
 THE 3rU^CLES AND FASCIA 
 
 The Gircumfiexus or Tensor Palati {m. tensor veli palatini) is a broad, thin, 
 ribbon-Uke muscle, placed on the outer side of the Levator palati, and consisting of 
 a vertical and a horizontal portion. The vertical portion arises by a flat lamella 
 from the scaphoid fossa at the base of the internal pterygoid plate; from the spine 
 of the sphenoid and the outer side of the cartilaginous portion of the Eustachian 
 tube: descending vertically between the internal pterygoid plate and the inner sur- 
 face of the Internal pterygoid muscle, it terminates in a tendon, which winds round 
 the hamular process, being retained in this situation by some of the fibres of origin 
 of the Internal pterygoid muscle. Between the hamular process and the tendon is 
 a small bursa (bursa m. tensoris veli palati). The tendon or horizontal portion then 
 
 <> p h a 
 Fig. 278. — Muscles of the soft palate, the pharynx being laid open from behind. 
 
 passes horizontally inward, and is inserted into a broad aponeurosis, the palatini 
 aponeurosis, and into the transverse ridge on the horizontal portion of the palate 
 bone. 
 
 Relations. — Externally, with the Internal pterygoid; internally, with the Levator 
 palati, from which it is separated by the Eustachian tube and Superior constrictor 
 and with the internal pterygoid plate. In the soft palate its tendon and the pala- 
 tine aponeurosis are anterior to those of the I^evator palati, being covered by the 
 Palato-glossus and the mucous membrane. 
 
 Palatine Aponeurosis. — Attached to the posterior border of the hard palate is 
 a thin, firm, fibrous lamella which supports the muscles and gives strength to the 
 soft palate. It is thicker above than below, where it becomes very thin and 
 difficult to define. Laterally, it is continuous with the pharyngeal aponeurosis. 
 
THE PALATAL REGION 405 
 
 The Azygos Uvulae {m. uvuhc) is not a single muscle, as would be inferred from 
 its name, but a pair of narrow cylindrical fleshy fasciculi placed on either side of the 
 median line of the soft palate. Each muscle arises from the posterior nasal spine 
 of the palate bone and from the contiguous tendinous aponeurosis of the soft palate, 
 and descends to be inserted into the uvula. 
 
 Relations. — Anteriorly, with the tendinous expansion of the Levatores palati; 
 behind, with the posterior fasciculus of the Palato-pharyngeus and the mucous 
 membrane. 
 
 The next two muscles are exposed by removing the mucous membrane from the pillars of 
 the fauces throughout nearly their whole extent. 
 
 The Palato-glossus or the Constrictor Isthmi Faucium (to. glossopalatinns) 
 is a small fleshy fasciculus, narrower in the middle than at either extremity, 
 forming, with the mucous membrane covering its surface, the anterior pillar of 
 the soft palate. It arises from the anterior surface of the soft palate on each 
 side of the uvula, and, passing downward, forward, and outward in front of the 
 tonsil, is inserted into the side of the tongue, some of its fibres spreading over 
 the dorsum, and others passing deeply into the substance of the organ to inter- 
 mingle with the Transverse lingualis. In the soft palate the fibres of this muscle 
 are continuous with those of the muscle of the opposite side. 
 
 The Palato-pharyngeus (to. pharyngopalatinus) is a long, fleshy fasciculus, 
 narrower in the middle than at either extremity, forming, with the mucous 
 membrane covering its surface, the posterior pillar of the soft palate. It is sepa- 
 rated from the Palato-glossus by an angular interval, in which the tonsil is 
 lodged. It arises from the soft palate by an expanded fasciculus, which is 
 divided into two parts by the Levator palati and Azygos uvulae. The posterior 
 fasciculus lies in contact with the mucous membrane, and also joins with the 
 corresponding muscle in the middle line; the anterior fasciculus, the thicker, lies 
 in the soft palate between the Levator and Tensor, and joins in the middle line 
 the corresponding part of the opposite muscle. Passing outward and downward 
 behind the tonsil, the Palato-pharyngeus joins the Stylo-pharyngeus, and is 
 inserted with that muscle into the posterior border of the thyroid cartilage, some 
 of its fibres being lost on the side of the pharynx, and others passing across the 
 middle line posteriorly to decussate with the muscle of the opposite side. 
 
 Relations. — In the soft palate its posterior svrface is covered by mucous mem- 
 brane, from which it is separated by a layer of palatine glands. By its anterior 
 surface it is in relation with the Tensor palati. Where it forms the posterior pillar 
 of the fauces it is covered by mucous membrane, excepting on its outer surface. In 
 the pharynx it lies between the mucous membrane and the Constrictor muscles. 
 
 The Salpingo-pharyngeus arises from the inferior part of the Eustachian tube 
 near its orifice ; it passes downward and blends with the posterior fasciculus of 
 the Palato-pharyngeus. 
 
 In a dissection of the soft palate from its posterior or nasal surface to its ante- 
 rior or oral surface, the muscles Avould be exposed in the following order — viz., the 
 posterior fasciculus of the Palato-pharyngeus, covered over by the mucous mem- 
 brane reflected from the floor of the nasal fossa?; the Azygos uvulae; the Levator 
 palati; the anterior fasciculus of the Palato-pharyngeus; the aponeurosis of the 
 Tensor palati, and the Palato-glossus, covered over by a reflection from the oral 
 mucous membrane. 
 
 Nerves. — The Tensor palati is supplied by a branch from the otic ganglion; 
 the remaining muscles of this group are in all probability supplied by the internal 
 branch of the spinal accessory, whose fibres are distributed along with certain 
 branches of the pneumogastric through the pharyngeal plexus.^ It is possible, 
 
 1 Journal of Anatomy anrt Physiology, vol. xxiii. p. 523. 
 
406 
 
 THE MUSCLES AND FASCIA 
 
 however, that the Levator palati may be suppHed by the facial through the Petrosal 
 branch of the Vidian. 
 
 Actions. — During the first stage of deglutition the morsel of food is driven 
 back into the fauces by the pressure of the tongue against the hard palate, the 
 base of the tongue being, at the same time, retracted, and the larynx raised with 
 the pharynx, and carried forward under it. During the second stage the entrance 
 to the larynx is closed, not, as was formerly supposed, by the folding backward 
 of the epiglottis over it, but, as Anderson Stuart has shown, by the drawing 
 forward of the arytenoid cartilages toward the cushion of the epiglottis — a move- 
 ment produced by the contraction of the External thyro-arytenoid, the Arytenoid, 
 and Aryteno-epiglottidean muscles. 
 
 The morsel of food after leaving the tongue passes on to the posterior or laryn- 
 geal surface of the epiglottis, and glides along this for a certain distance;^ then 
 the Palato-glossi muscles, the constrictors of the fauces, contract behind the food; 
 the soft palate is slightly raised by the Levator palati, and made tense by the 
 Tensor palati; and the Palato-pharyngei, by their contraction, pull the pharynx 
 upward over the morsel of food, and at the same time come nearly together, the 
 uvula filling up the slight interval between them. By these means the food is 
 prevented passing into the upper part of the larynx or the posterior nares; at 
 the same time the latter muscles form an inclined plane, directed obliquely down- 
 ward and backward, along the under surface of which the morsel descends into 
 the lower part of the pharynx. The Salpingo-pharyngeus raises the upper and 
 lateral part of the pharynx — i. e., that part which is above the point where the 
 Stylo-pharyngeus is attached to the pharynx. 
 
 Surgical Anatomy. — The muscles of the soft palate should be carefully dissected, the rela- 
 tions they bear to the surrounding parts especially examined, and their action attentively studied 
 upon the dead subject, as the surgeon is required to divide one or more of these muscles in the 
 operation of staphylorraphy. Sir W. Fergusson was the first to show that in the congenital 
 deficiency called clep, palate the edges of the fissure are forcibly separated by the action of the 
 Levatores palati and Palato-pharyngei muscles, producing very considerable impediment to the 
 healing process after the performance of the operation for uniting their margins by adhesion ; he 
 consequently recommended the division of these muscles as one of the most important steps in 
 the operation. This he effected by an incision made with a curved knife introduced behind the 
 soft palate. The incision is to be half-way between the hamular process and Eustachian tube 
 and perpendicular to a line drawn between them. This incision perfectly accomplishes the 
 division of the Levator palati. The Palato-pharyngeus may be divided by cutting across the 
 posterior pillar of the soft palate, just below the tonsil, with a pair of blunt-pointed curved 
 scissors; and the anterior pillar may be divided also. To divide the Levator palati the plan 
 recommended by Mr. Pollock is to be greatly preferred. The soft palate being put upon the 
 stretch, a double-edged knife is passed through it just on the inner side of the hamular process 
 and above the line of the Levator palati. The handle being now alternately raised and depressed, 
 a sweeping cut is made along the posterior surface of the soft palate, and the knife withdrawn, 
 leaving only a small opening in the mucous membrane on the anterior surface. If this operation 
 is performed on the dead body and the parts afterward dissected, the Levator palati will be 
 found completely divided. In the present day, however, this division of the muscles, as part 
 of the operation of staphylorraphy, is not so much insisted upon. All tension is prevented by 
 making longitudinal incisions on either side, parallel to the cleft and just internal to the hamular 
 process, in such a position as to avoid the posterior palatine artery. 
 
 7. The Anterior Vertebral Region (Fig. 279). 
 
 Rectus capitis anticus major. Rectus capitis lateralis. 
 
 Rectus capitis anticus minor. Longus colli. 
 
 The Rectus Capitis Anticus Major or the Longus Capitis, broad and 
 thick above, narrow below, appears hke a continuation upward of the Sca- 
 
 ^ We now know that normal deglutition can be carried out when the epiglottis is so small that it cannot coyer 
 the opening into the larynx, or when it has been removed surgically. In such cases the sphincter muscles which 
 surround the laryngeal aperture contract during swallowing and prevent the entrance of foreign bodies mto the 
 larynx. — Ed. 
 
THE ANTERIOR VERTEBRAL REGION 
 
 407 
 
 leniis anticus. It arises by four tendinous slips from the anterior tubercles of 
 the transverse processes of the third, fourth, fifth, and sixth cervical vertebrae, and 
 ascends, converging toward its fellow of the opposite side, to be inserted into the 
 basilar process of the occipital bone. 
 
 Relations. — By its anterior surface, with the pharynx, the sympathetic nerve, 
 and the sheath enclosing the internal and common carotid artery, internal jugular 
 vein, and pneumogastric nerve; by its ^posterior surface, with the Longus colli, the 
 Rectus capitis anticus minor, and the upper cervical vertebrae. 
 
 Fig. 279. — The prevertebral muscles. 
 
 The Rectus Capitis Anticus Minor is a short, flat muscle, situated imme- 
 diately behind the upper part of the preceding. It arises from the anterior 
 surface of the lateral mass of the atlas and from the root of its transverse process, 
 and, passing obliquely upward and inward, is inserted into the basilar process 
 immediately behind the preceding muscle. 
 
 Relations. — By its anterior surface, with the Rectus capitis anticus major; by 
 its posterior surface, with the front of the occipito-atlantal articulation. 
 
 The Rectus Capitis Lateralis is a short, flat muscle, which arises from the 
 upper surface of the transverse process 9f the atlas, and is inserted into the under 
 surface of the jugular process of the occipital bone. 
 
 Relations. — By its anterior surface, with the internal jugular vein; by its 'pos- 
 terior surface, with the vertebral artery. On its outer side lies the occipital artery; 
 on its inner side, the suboccipital nerve. 
 
 The Longus Colli is a long, flat muscle, situated on the anterior surface of the 
 spine, between the atlas and the third dorsal vertebra. It is broad in the middle, 
 
408 
 
 THE MUSCLES AND FASCIA 
 
 narrow and pointed at each extremity, and consists of three portions: a superior 
 obhque, an inferior obUque, and a vertical portion. The superior oblique portion 
 arises from the anterior tubercles of the transverse processes of the third, fourth, 
 and fifth cervical vertebrae, and, ascending obliquely inward, is inserted by a nar- 
 row tendon into the tubercle on the anterior arch of the atlas. The inferior oblique 
 portion, the smallest part of the muscle, arises from the front of the bodies of the 
 first two or three dorsal vertebrae, and, ascending oblicjuely outward, is inserted 
 into the anterior tubercles of the transverse processes of the fifth and sixth cervi- 
 cal vertebrae. The vertical portion lies directly on the front of the spine; it arises, 
 below, from the front of the bodies of the upper three dorsal and lower three cer- 
 vical vertebrae, and is inserted above into the front of the bodies of the second, 
 third, and fourth cervical vertebrae. 
 
 Relations. — By its anterior surface, with the prevertebral fascia, the pharynx, 
 the oesophagus, sympathetic nerve, the sheath of the great vessels of the neck, 
 the inferior thyroid artery, and recurrent laryngeal nerve; by its ^posterior surface, 
 with the cervical and dorsal portions of the spine. Its inner border is separated 
 from the opposite muscle by a considerable interval below, but they approach 
 each other above. 
 
 8. The Lateral Vertebral Region (Figs. 279, 280). 
 
 Scalenus anticus. 
 
 Scalenus medius. 
 
 Scalenus posticus. 
 
 The Scalenus Anticus (w. scalenus anterior) is a conical-shaped muscle, 
 situated deeply at the side of the neck, behind the Sterno-mastoid. It 
 
 arises from the anterior tubercles of 
 the transverse processes of the third, 
 fourth, fifth, and sixth cervical verte- 
 brae, and, descending almost vertically, 
 is inserted by a narrow, flat tendon 
 into the Scalene tubercle on the inner 
 border and upper surface of the first 
 rib. The lower part of this muscle sep- 
 arates the subclavian artery and vein, 
 the latter being in front, and the former, 
 with the brachial plexus, behind. 
 
 Relations. — In front, with the clav- 
 icle, the Subclavius, Sterno-mastoid, 
 and Omo-hyoid muscles, the Trans- 
 versalis colli, the suprascapular and 
 ascending cervical arteries, the subcla- 
 vian vein, and the phrenic nerve; by 
 its 'posterior surface, with the Scalenus 
 medius, pleura, subclavian artery, and 
 brachial plexus of nerves. It is sep- 
 arated from the Longus colli, on the 
 inner side, by the vertebral artery. 
 On the anterior tubercles of the trans- 
 verse processes of the cervical vertebrae, 
 between the attachments of the Scale- 
 nus anticus and Longus colli, lies the 
 ascending cervical branch of the infe- 
 rior thyroid artery. 
 
 The Scalenus Medius, the largest and longest of the three Scaleni, arises from 
 the posterior tubercles of the transverse processes of the lower six cervical vertebrae, 
 
 Fig. 280. — Scaleni muscles. (Poirier and Charpy.) 
 
THE LATERAL VERTEBRAL REGION 409 
 
 and, descending along the side of the vertebral column, is inserted by a broad 
 attachment into the upper surface of the first rib, behind the groove for the sub- 
 clavian artery, as far back as the tubercle. It is separated from the Scalenus 
 anticus by the subclavian artery below and the cervical nerves above. The pos- 
 terior thoracic, or nerve of Bell, is formed in the substance of the Scalenus medius 
 and emerges from it. The nerve to the Rhomboids also pierces it. 
 
 Relations. — By its anterior surface, with the Sterno-mastoid; it is crossed by 
 the clavicle, the Omo-hyoid muscle, subclavian artery, and cervical nerves. To 
 its outer side is the Levator anguli scapulae and the Scalenus posticus muscle. 
 
 The Scalenus Posticus (m. scalenus posterior), the smallest of the three Scaleni, 
 arises, by two or three separate tendons, from the posterior tubercles of the trans- 
 verse processes of the lower two or three cervical vertebrae, and, diminishing as it 
 descends, is inserted by a thin tendon into the outer surface of the second rib, 
 behind the attachment of the Serratus magnus. This is the most deeply placed of 
 the three Scaleni, and is occasionally blended with the Scalenus medius. 
 
 Nerves.— The Rectus capitis anticus major and minor and the Rectus lateralis 
 are supplied by the first cervical nerve, and from the loop formed between it and 
 the second; the I>ongus colli and Scaleni, by branches from the anterior divisions 
 of the lower cervical nerves (fifth, sixth, seventh, and eighth) before they form the 
 brachial plexus. The Scalenus medius also receives a filament from the deep 
 external branches of the cervical plexus. 
 
 Actions. — The Rectus anticus major and minor are the direct antagonists of the 
 muscles at the back of the neck, serving to restore the head to its natural position 
 after it has been drawn backward. These muscles also serve to flex the head, and, 
 from their obliquity, rotate it, so as to turn the face to one or the other side. The 
 Longus colli flexes and slightly rotates the cervical portion of the spine. The 
 Scaleni muscles, when they take their fixed point from above, elevate the first and 
 second ribs, and are, therefore, inspiratory muscles. When they take their fixed 
 point from below, they bend the spinal column to one or the other side. If the 
 muscles of both sides act, lateral movement is prevented, but the spine is slightly 
 flexed. The Rectus lateralis, acting on one side, bends the head laterally. 
 
 Surface Form. — The muscles in the neck, with the exception of the Platysma myoides, are 
 invested by the deep cervical fascia, which softens down their form, and is of considerable 
 importance in connection with deep cervical abscesses and tumors, modifying the direction of 
 the growth of tumors and of the enlargement of abscesses, and causing them to extend 
 laterally instead of toward the surface. The Platysma myoides does not influence surface 
 form except when in action, when it produces wrinkling of the skin of the neck, which is 
 thrown into oblique ridges parallel with the fasciculi of the muscle. Sometimes this con- 
 traction takes place suddenly and repeatedly as a sort of spasmodic twitching, the result of 
 a nervous habit. The Sterno-cleido-mastoid is the most important muscle of the neck as 
 regards its surface form. If the muscle is put into action by drawing the chin downward and 
 to the opposite shoulder, its surface form will be plainly outlined. The sternal origin will 
 stand out as a sharply-defined ridge, while the clavicular origin will present a flatter and not so 
 prominent an outline. The fleshy middle portion will appear as an oblique roll or elevation, 
 Avith a thick rounded anterior border gradually becoming less marked above. On the opposite 
 side — i. e., on the side to which the head is turned — the outline is lost, its place being occupied 
 by an oblique groove in the integument. When the muscle is at rest its anterior border is still 
 visible, forming an oblique rounded ridge, terminating below in the sharp outline of the sternal 
 head. The posterior border of the muscle does not show above the clavicular head. The 
 anterior border is defined by drawing a line from the tip of the mastoid process to the sterno- 
 clavicular joint. It is an important surface-marking in the operation of ligature of the common 
 carotid artery and in some other operations. Between the sternal and clavicular heads is a slight 
 depression, most marked when the muscle is in action. This is bounded below by the prominent 
 sternal extremity of the clavicle. Between the sternal origins of the two muscles is a V-shaped 
 space, the suprasternal notch, more pronounced below, and becoming toned down above, where 
 the vSterno-hyoid and Sterno-thyroid muscles, lying upon the trachea, become more prominent. 
 Above the hyoid bone, in the middle line, the anterior belly of the Digastric to a certain extent 
 influences surface form. It corresponds to a line drawn from the symphysis of the lower jaw to 
 
410 
 
 THE MUSCLES AND FASCl^ 
 
 the side of the body of the hyoid bone, and renders this part of the hyo-mental region convex. 
 In the posterior triangle of the neck, the posterior belly of the Omo-hyoid, when in action, forms 
 a conspicuous object, especially in thin necks, presenting a cord-like form running across this 
 region, almost parallel with, and a little above, the clavicle. 
 
 MUSCLES AND FASCIA OF THE TRUNK. 
 
 The muscles of the Trunk may be arranged in four groups, corresponding 
 with the region in which they are situated. 
 
 I. The Back. III. The Abdomen. 
 
 II. The Thorax. 
 
 IV. The Perinseum. 
 
 I. MUSCLES OF THE BACK. 
 
 The muscles of the Back are very numerous, and may be subdivided into five 
 layers : 
 
 First Layer. 
 
 Trapezius. 
 Latissimus dorsi. 
 
 Second Layer. 
 
 Levator anguli scapulae. 
 Rhomboideus minor. 
 Rhomboideus major. 
 
 Third Layer. 
 
 Serratus posticus superior. 
 Serratus posticus inferior. 
 Splenius capitis. 
 Splenius colli. 
 
 Fourth Layer. 
 Sacral and Lumbar Regions. 
 Erector spinse. 
 
 Dorsal Region. 
 
 Ilio-costalis. 
 
 Musculus accessorius ad ilio-costalem. 
 
 Longissimus dorsi. 
 Spinalis dorsi. 
 
 Cervical Region. 
 
 Cervicalis ascendens. 
 Transversalis cervicis. 
 Trachelo-mastoid. 
 Complexus. 
 Biventer cervicis. 
 Spinalis colli. 
 
 Fifth Layer. 
 
 Semispinalis dorsi. 
 Semispinalis colli. 
 Multifidus spinse. 
 Rotatores spinee. 
 Supraspinales. 
 Interspinales. 
 Extensor coccygis. 
 Intertransversalis. 
 Rectus capitis posticus major. 
 Rectus capitis posticus minor. 
 Obliquus capitis inferior. 
 Obliquus capitis superior. 
 
 The First Layer (Fig. 282). 
 Trapezius. I>atissimus dorsi. 
 
 Dissection (Fig. 281). — Place the body in a prone position, with the arms extended over 
 the sides of the table, and the chest and abdomen supported by several blocks, so as to render 
 the muscles tense. Then make an incision along the middle line of the back from the occipital 
 protuberance to the coccyx. Make a transverse incision from the upper end of this to the mas- 
 toid process, and a third incision from its lower end, along the crest of the ilium to about its 
 middle. This large intervening space should, for convenience of dissection, be subdivided by 
 a fourth incision, extending obliquely from the spinous process of the last dorsal vertebra, upward 
 and outward, to the acromion process. This incision corresponds with the lower border of the 
 Trapezius muscle. The flaps of integument are then to be removed in the direction shown in 
 the figure. 
 
OF THE BACK 
 
 411 
 
 Superficial Fascia. — The superficial fascia is exposed upon removing the skin 
 from the back. It forms a layer of considerable thickness and strength, in which 
 a quantity of granular pinkish fat is contained. It is continuous with the super- 
 ficial fascia in other parts of the body. 
 
 Deep Fascia. — The deep fascia is a dense fibrous layer attached to the 
 occipital bone, the spines of the vertebrse, the crest of the ilium, and the spine 
 of the scapula. It covers over the superficial 
 muscles, forming sheaths for them, and in the 
 neck forms the posterior part of the deep cer- 
 vical fascia; in the thorax it is continuous with 
 the deep fascia of the axilla and chest, and in 
 the abdomen with that covering the abdominal 
 muscles. In the back of the thoracic region 
 the deep fascia is called the vertebral aponeurosis 
 or the aponeurosis of the latissimus dorsi muscle. 
 It covers the erector spinte muscles, and is the 
 posterior layer of the lumbar fascia. 
 
 The Trapezius is a broad, flat, triangular 
 muscle, placed immediately beneath the skin 
 and fascia, and covering the upper and back 
 part of the neck and shoulders. It arises from 
 the external occipital protuberance and the 
 inner third of the superior curved line of the 
 occipital bone; from the ligamentum nuchae, the 
 spinous process of the seventh cervical, and the 
 spinous processes of all the dorsal vertebrae; and 
 from the corresponding portion of the supra- 
 spinous ligament. From this origin the supe- 
 rior fibres proceed downward and outward, 
 the inferior ones upward and outward, and 
 the middle fibres horizontally, and are in- 
 serted, the superior ones into the outer third of 
 the posterior border of the clavicle ; the middle 
 fibres into the inner margin of the acromion 
 
 process, and into the superior lip of the posterior border or crest of the spine 
 of the scapula; the inferior fibres converge near the scapula, and terminate in a 
 triangular aponeurosis, which glides over a smooth surface at the inner extremity 
 of the spine, to be inserted into a tubercle at the outer part of this smooth surface. 
 The Trapezius is fleshy in the greater part of its extent, but tendinous at its origin 
 and insertion. At its occipital origin it is connected to the bone by a thin fibrous 
 lamina, firmly adherent to the skin, and wanting the lustrous, shining appearance 
 of aponeuroses. At its origin from the spines of the vertebrae it is connected to 
 the bones by means of a broad semi-elliptical aponeurosis, which occupies the 
 space between the sixth cervical and the third dorsal vertebrae, and forms, with 
 the aponeurosis of the opposite nmscle, a tendinous ellipse. The rest of the 
 muscle arises by numerous short tendinous fibres. If the Trapezius is dissected 
 on both sides, the two muscles resemble a trapezium or diamond-shaped quad- 
 rangle ; two angles corresponding to the shoulders ; a third to the occipital pro- 
 tuberance; and the fourth to the spinous process of the last dorsal vertebra. The 
 clavicular insertion of this muscle varies as to the extent of its attachment; it 
 sometimes advances as faV as the middle of the clavicle, and may even become 
 blended with the posterior edge of the Sterno-mastoid or overlap it. This should 
 be borne in mind in the operation for tying the third part of the subclavian 
 artery. ♦ 
 
 Fig. 281. — Dissection of the muscles of 
 the back. 
 
412 
 
 THE 31USCLES AND FASCIA 
 
 Fig. 282. — Muscles of the back. On the left side is exposed the first layer; on the right side, the second layer 
 
 and part of the third. 
 
OF THE BACK 413 
 
 Relations. — By its superficial surface, with the integument; by its deep sur- 
 face, in the neck, with the Complexus, Splenius, Levator anguH scapulae, and 
 Rhomboideus minor; in the back, with the Rhomboideus major, Supraspinatus, 
 Infraspinatus, and Vertebral aponeurosis (which separates it from the prolonga- 
 tions of the Erector spinae), and the Latissimus dorsi. The spinal accessory nerve 
 and the superficial cervical artery and branches from the third and fourth cervical 
 nerves pass beneath the anterior border of this muscle. The anterior margin of its 
 cervical portion forms the posterior boundary of the posterior triangle of the neck, 
 the other boundaries being the Sterno-mastoid in front and the clavicle below. 
 
 The Ligamentum nuchse (Fig. 282) is a fibrous membrane, which, in the neck, 
 represents the supraspinous and interspinous ligaments of the lower vertebrae. 
 It extends from the external occipital protuberance to the spinous process of the 
 seventh cervical vertebra. From its anterior border a fibrous lamina (fascia 
 nuAihoe) is given off, which is attached to the external occipital crest, the posterior 
 tubercle of the atlas, and the spinous process of each of the cervical vertebrae, so 
 as to form a septum between the muscles on each side of the neck. In man it is 
 merely the rudiment of an important elastic ligament, which, in some of the lower 
 animals, serves to sustain the weight of the head. 
 
 The Latissimus Dorsi is a broad flat muscle, which covers the lumbar and the 
 lower half of the dorsal regions, and is gradually contracted into a narrow fascic- 
 ulus at its insertion into the humerus. It arises by tendinous fibres from the 
 spinous processes of the six inferior dorsal vertebrae and from the posterior layer 
 of the lumbar fascia (see page 416), by which it is attached to the spines of the 
 lumbar and sacral vertebnB and to the supraspinous ligament. It also arises 
 from the external lip of the crest of the ilium, behind the origin of the External 
 oblique, and by fleshy digitations from the three or four lower ribs, which are 
 interposed between similar processes of the External oblique muscle (Fig. 289, 
 page 434). From this extensive origin the fibres pass in different directions, the 
 upper ones horizontally, the middle obliquely upward, and the lower vertically 
 upward, so as to converge and form a thick fasciculus, which crosses the inferior 
 angle of the scapula, and occasionally receives a few fibres of origin from it. The 
 muscle then curves around the lower border of the Teres major, and is twisted 
 upon itself so that the superior fibres become at first posterior and then inferior, 
 and the vertical fibres at first anterior and then superior. It then terminates in a 
 short quadrilateral tendon, about three inches in length, which, passing in front of 
 the tendon of the Teres major, is inserted into the bottom of the bicipital groove 
 of the humerus, its insertion extending higher on the humerus than that of the 
 tendon of the Pectoralis major. The lower border of the tendon of this muscle is 
 united with that of the Teres major, the surfaces of the two being separated by a 
 bursa; another bursa is sometimes interposed between the muscle and the inferior 
 angle of the scapula. This muscle at its insertion gives off an expansion to the 
 deep fascia of the arm. 
 
 A muscular slip, the axillary arch, varying from 3 to 4 inches in length, and from J to f of an 
 inch in breadth, occasionally arises from the upper edge of the Latissimus dorsi about the mid- 
 dle of the posterior fold of the axilla, and crosses the axilla in front of the axillary vessels and 
 nerves, to join the under surface of the tendon of the Pectoralis major, the Coraco-brachialis, 
 or the fascia over the Biceps. The position of this abnormal slip is a point of interest in its 
 relation to the axillary artery, as it crosses the vessel just above the spot usually selected for the 
 application of a ligature, and may mislead the surgeon during the operation. It may be easily 
 recognized by the transverse direction of its fibres. Dr. Struther found it, in 8 out of 105 sub- 
 jects, occurring seven times on both sides. In most subjects there is a fibrous axillary arch, 
 in only a few is the arch muscular. 
 
 There is usually a fibrous slip which passes from the lower border of the tendon of the Latis- 
 simus dorsi, nearits insertion, to the long head of the Triceps. This is occasionally muscular, 
 and is the representative of the Dorso-epitrochlearis muscle of apes. 
 
414 THE 3IU8CLES ANB FASCIA 
 
 Relations. — Its superficial surface is subcutaneous, excepting at its upper part, 
 where it is covered by the Trapezius, and at its insertion, where its tendon is 
 crossed by the axillary vessels and the brachial plexus of nerves. By its deep 
 surface it is in relation with the lumbar fascia, the Serratus posticus inferior, 
 the lower External intercostal muscles and ribs, inferior angle of the scapula, 
 Rhomboideus major. Infraspinatus, and Teres major. Its outer margin is sepa- 
 rated below from the External oblique by a small triangular interval, the triangle 
 of Petit (trigonum lumbale [Petiti]) ; and another triangular interval exists between 
 its upper border and the margin of the Trapezius, in which the Rhomboideus 
 major muscle is exposed. 
 
 Nerves. — The Trapezius is supplied by the spinal accessory, and by branches 
 from the anterior divisions of the third and fourth cervical nerves : the Latissimus 
 dorsi, by the middle or long subscapular nerve. 
 
 The Second Layer (Fig. 282). 
 
 Levator anguli scapulae. Rhomboideus minor. 
 
 Rhomboideus major. 
 
 Dissection.— The Trapezius must be removed, in order to expose the next layer; to effect 
 this, detach the muscle from its attachment to the clavicle and spine of the scapula, and turn 
 it back toward the spine. 
 
 The Levator Ang^uli Scapulae (m. levator scapulae) is situated at the back part 
 and side of the neck. It arises by tendinous slips from the transverse process of 
 the atlas, and from the posterior tubercles of the transverse processes of the second, 
 third, and fourth cervical vertebrae; these, becoming fleshy, are united so as to 
 form a flat muscle, which, passing downward and backward, is inserted into the 
 posterior border of the scapula, between the superior angle and the triangular 
 smooth surface at the root of the spine. 
 
 Relations. — By its superficial surface, with the integument. Trapezius, and 
 Sterno-mastoid; by its deep surface, with the Splenius colli, Transversalis cervicis, 
 Cervicalis ascendens, and Serratus posticus superior muscles, and with the pos- 
 terior scapular artery and the nerve to the Rhomboids. 
 
 The Rhomboideus Minor arises from the ligamentum nuchse and spinous 
 processes of the seventh cervical and first dorsal vertebrae. Passing downward 
 and outward, it is inserted into the margin of the triangular smooth surface at the 
 root of the spine of the scapula. This small muscle is usually separated from the 
 Rhomboideus major by a slight cellular interval. 
 
 Relations. — By its superficial (posterior) surface, with the Trapezius; by its deep 
 {anterior) surface, with the same structures as the Rhomboideus major. 
 
 The Rhomboideus Major is situated immediately below the preceding, the 
 adjacent margins of the two being occasionally united. It arises by tendinous 
 fibres from the spinous processes of the four or five upper dorsal vertebrae and the 
 supraspinous ligament, and is inserted into a narrow tendinous arch attached 
 above to the lower part of the triangular surface at the root of the spine; below, 
 to the inferior angle, the arch being connected to the border of the scapula by a 
 thin membrane. When the arch extends, as it occasionally does, but a short 
 distance, the muscular fibres are inserted into the scapula itself. 
 
 Relations. — By its superficial (posterior) surface, with the Trapezius and Latis- 
 simus dorsi; by its deep (anterior) surface, with the Serratus posticus superior, 
 posterior scapular artery, the vertebral aponeurosis which separates it from the 
 prolongations from the Erector spinae, the Intercostal muscles, and ribs. 
 
 Nerves. — The Rhomboid muscles are supplied by branches from the anterior 
 division of the fifth cervical nerve; the Levator anguli scapulae, by the anterior 
 
OF THE BACK 4I5 
 
 divisions of the third and fourth cervical nerves, and frequently by a branch from 
 the nerve to the Rhomboids. 
 
 Actions. — The movements effected by the preceding muscles are numerous, as 
 may be conceived from their extensive attachment. The whole of the Trapezius 
 when in action retracts the scapula and braces back the shoulder; if the head is 
 fixed, the upper part of the Trapezius will elevate the point of the shoulder, as in 
 supporting weights; when the lower fibres are brought into action, they assist 
 in depressing the bone. The middle and lower fibres of the muscle rotate the 
 scapula, causing elevation of the acromion process. If the shoulders are fixed, both 
 Trapezii, acting together, will draw the head directly backward; or if only one 
 acts the head is drawn to the corresponding side. The Latissimus dorsi, when it 
 acts upon the humerus, depresses it, draws it backward, adducts, and at the same 
 time rotates it inward. It is the muscle which is principally employed in giving a 
 downward blow, as in felling a tree or in sabre practice. If the arm is fixed, the 
 muscle may act in various ways upon the trunk; thus, it may raise the lower ribs 
 and assist in forcible inspiration; or, if both arms are fixed, the two muscles may 
 assist the Abdominal and great Pectoral muscles in suspending and drawing the 
 whole trunk forward, as in climbing or walking on crutches. The Levator anguli 
 scapula? raises the superior angle of the scapula, and by so doing depresses the 
 point of the shoulder. It assists the Trapezius in bearing weights and in shrugging 
 the shoulders. If the shoulder be fixed, the Levator anguli scapulte inclines the 
 neck to the corresponding side and rotates it in the same direction. The Rhom- 
 boid muscles carry the inferior angle backward and upward, thus producing a 
 slight rotation of the scapula upon the side of the chest, the Rhomboideus major 
 acting especially on the lower angle of the scapula through the tendinous arch by 
 which it is inserted. The Rhomboid muscles, acting together with the middle and 
 inferior fibres of the Trapezius, will draw the scapula directly backward toward 
 the spine. 
 
 The Third Layer. 
 
 Serratus posticus superior. Serratus posticus inferior. 
 
 ^ , . f Splenius capitis. 
 Splenms | g^j^^j^^ J^^ 
 
 Dissection. — To bring into view the third layer of muscles, remove the whole of the second, 
 together with the Latissimus dorsi, by cutting through the Levator anguli scapulae and Rhom- 
 boid muscles near their origin, and reflecting them downward, and by dividing the Latissimus 
 dorsi in the middle by a vertical incision carried from its upper to its lower part, and reflecting 
 the two halves of the muscle. 
 
 The Serratus Posticus Superior {m. serratus 'posterior superior) is a thin, flat, 
 quadrilateral muscle situated at the upper and back part of the thorax. It arises 
 by a thin and broad aponeurosis from the ligamentum nuchae, and from the spinous 
 processes of the last cervical and two or three upper dorsal vertebrae and from the 
 supraspinous ligament. Inclining downward and outward, it becomes muscular, 
 and is inserted, by four fleshy digitations into the upper borders of the second, 
 third, fourth, and fifth ribs, a little beyond their a gles. 
 
 Relations. — By its superficial surface, with the Trapezius, Rhomboidei, and 
 Levator anguli scapulae; by its deep surface, with the Splenius and the vertebral 
 aponeurosis, which separates it from the prolongations of the Erector spinae, and 
 with the Intercostal muscles and ribs. 
 
 The Serratus Posticus Inferior (m. serratus posterior inferior) (Fig. 282) is 
 situated at the junction of the dorsal and lumbar regions ; it is of an irregularly 
 quadrilateral form, broader than the preceding, and separated from it by a consid- 
 erable interval. It arises by a thin aponeurosis from the spinous processes of the 
 last two dorsal and two or three upper lumbar vertebrae, and from the supra- 
 
41G THE MUSCLES AND FASCIA 
 
 spinous ligaments. Passing obliquely upward and outward, it becomes fleshy, 
 and divides into four flat digitations, which are inserted into the lower borders of 
 the four lower ribs, a little beyond their angles. The thin aponeurosis of origin 
 is intimately blended with the lumbar fascia. 
 
 Relations. — By its superficial surface, with the Latissimus dorsi. By its deep 
 surface, with the Erector spinae, ribs, and Intercostal muscles. Its upper margin 
 is continuous with the vertebral aponeurosis. 
 
 The vertebral aponeurosis is a thin, fibrous lamina, extending along the whole 
 length of the back part of the thoracic region, serving to bind down the long 
 Extensor muscles of the back which support the spine and head, and separate them 
 from those muscles which connect the spine to the upper extremity. It consists of 
 longitudinal and transverse fibres blended together, forming a thin lamella, which 
 is attached in the median line to the spinous processes of the dorsal vertebrae; 
 externally, to the angles of the ribs ; and below, to the upper border of the Serratus 
 posticus inferior and a portion of the lumbar fascia, which gives origin to the Latis- 
 simus dorsi ; above, it passes beneath the Serratus posticus superior and the Splenius, 
 and blends with the deep fascia of the neck. 
 
 The lumbar fascia or aponeurosis (Fig^. 282 and 295), which may be regarded 
 as the posterior aponeurosis of the Transversalis abdominis muscle, consists 
 of three laminae, which are attached as follows: the posterior layer, to the 
 spines of the lumbar and sacral vertebrae and their supraspinous ligaments; the 
 middle layer, to the tips of the transverse processes of the lumbar vertebne and 
 their intertransverse ligaments; the anterior layer, to the roots of the lumbar 
 transverse processes. The posterior layer is continued above as the vertebral 
 aponeurosis, while inferiorly it is fixed to the outer lip of the iliac crest. With this 
 layer are blended the aponeurotic origin of the Serratus posticus inferior and part 
 of that of the Latissimus dorsi. The middle layer is attached above to the last 
 rib, and below to the iliac crest; the anterior layer is fixed below to the ilio-lumbar 
 ligament and iliac crest ; while above it is thickened to form the external arcuate 
 ligament of the Diaphragm, and stretches from the tip of the last rib to the trans- 
 verse process of the first or second lumbar vertebra. These three layers, together 
 with the vertebral column, enclose two spaces, the posterior of which is occupied 
 by the Erector spinae muscle, and the anterior by the Quadratus lumborum. 
 
 Now detach the Serratus posticus superior from its origin, and turn it outward, when the 
 Splenius muscle will be brought into view. 
 
 The Splenius (Fig. 282) is situated at the back of the neck and upper part 
 of the dorsal region. At its origin it is a single muscle, which soon after its 
 origin becomes broad, and divides into two portions, which have separate inser- 
 tions. It arises, by tendinous fibres, from the lower half of the ligamentum 
 nuchae, from the spinous processes of the last cervical and of the six upper 
 dorsal vertebrae, and from the supraspinous ligament. From this origin the fleshy 
 fibres proceed obliquely upward and outward, forming a broad flat muscle, which 
 divides as it ascends into two portions, the Splenius capitis and Splenius colli. 
 
 The Splenius capitis (m. splenius capitis) is inserted into the mastoid process of 
 the temporal bone, and into the rough surface on the occipital bone just beneath 
 the superior curved line. 
 
 The Splenius colli (m. splenius cervicis) is inserted, by tendinous fasciculi, into the 
 posterior tubercles of the transverse processes of the two or three upper cervical 
 vertebrae. 
 
 The Splenius is separated from its fellow of the opposite side by a triangular 
 interval, in which is seen the Complexus. 
 
 Relations. — By its superficial surface, with the Trapezius, from which it is sepa- 
 rated below by the RhomJboidei and the Serratus posticus superior. It is covered 
 
OF THE BACK 41 7 
 
 at its insertion by the Sterno-mastoid, and at the lower and back part of the neck 
 by the Levator anguH scapulae ; by its deep surface, with the Spinalis dorsi, Longis- 
 simus dorsi, Semispinalis colli, Complexus, Trachelo-mastoid, and Transversalis 
 cervicis. 
 
 Nerves. — The Splenius is supplied from the external branches of the posterior 
 divisions of the cervical nerves; the Serratus posticus superior is supplied by the 
 external branches of the posterior divisions of the upper dorsal nerves; the Ser- 
 ratus posticus inferior by the external branches of the posterior divisions of the 
 lower dorsal nerves. 
 
 Actions. — The Serrati are respiratory muscles. The Serratus posticus supe- 
 rior elevates the ribs; it is therefore an inspiratory muscle; while the Serratus 
 inferior draws the lower ribs downward and backward, and thus elongates the 
 thorax. It also fixes the lower ribs, thus aiding the downward action of the 
 diaphragm and resisting the tendency which it has to draw the lower ribs upward 
 and forward. It must therefore be regarded as a muscle of inspiration. This 
 muscle is also probably a tensor of the vertebral aponeurosis. The Splenii muscles 
 of the two sides, acting together, draw the head directly backward, assisting the 
 Trapezius and Complexus; acting separately, they draw the head to one or the 
 other side, and slightly rotate it, turning the face to the same side. They also 
 assist in supporting the head in the erect position. 
 
 The Fourth Layer (Fig. 283). 
 
 I. Erector spinse. 
 a. Outer Column. h. Middle Column. 
 
 Ilio-costalis. Longissimus dorsi. 
 
 Musculus accessorius. Transversalis cervicis. 
 
 Cervicalis ascendens. Trachelo-mastoid. 
 
 c. Inner Column. 
 Spinalis dorsi. Spinalis colli. 
 
 II. Complexus. 
 
 Dissection. — To expose the muscles of the fourth layer, remove entirely the Serrati and the 
 vertebral and lumbar fasciae. Then detach the Splenius by separating its attachment to the 
 spinous processes and reflecting it outward. 
 
 The Erector Spinse {m. sacrospinalis) and its prolongations in the dorsal 
 and cervical regions fill up the vertebral groove on each side of the spine. It 
 is covered in the lumbar region by the lumbar fascia; in the dorsal region, by 
 the Serrati muscles and the vertebral aponeurosis; and in the cervical region, by 
 a layer of cervical fascia continued beneath the Trapezius and the Splenius. This 
 large muscular and tendinous mass varies in size and structure at different parts 
 of the spine. In the sacral region the Erector spina? is narrow and pointed, and 
 its origin chiefly tendinous in structure. In the lumbar region the muscle becomes 
 enlarged, and forms a large fleshy mass. In the dorsal region it subdivioes into 
 two parts, which gradually diminish in size as they ascend to be inserted into the 
 vertebrae and ribs. 
 
 The Erector spinae arises from the anterior surface of a very broad and thick 
 tendon, which is attached, internally, to the spines of the sacrum, to the spinous 
 processes of the lumbar and the eleventh and twelfth dorsal vertebrae, and the 
 supraspinous ligament; externally, to the back part of the inner lip of the crest of 
 the ilium, and to the series of eminences on the posterior part of the sacrum, which 
 represents the transverse processes, where it blends with the great sacro-sciatic and 
 posterior sacro-iliac ligaments. Some of its fibres are continuous with the fibres 
 
 27 
 
■418 
 
 THE MUSCLES AND FASCIA 
 
 MULTIFIDUS SPINiE 
 
 First dorsal vertebra.- — 
 
 First lumbar vertebra. 
 
 First sacral vertebra 
 
 Fig. 283. — Muscles of the back. Deep layers. 
 
OF THE BACK 41 9 
 
 of origin of the Gluteus maximus. The muscular fibres form a single large fleshy 
 mass, bounded in front by the transverse processes of the lumbar vertebrae and by 
 the middle lamella of the lumbar fascia. Opposite the last rib it divides into two 
 parts, the Ilio-costalis and the Longissimus dorsi; the Spinalis dorsi is given off 
 from the latter in the upper dorsal region. 
 
 The Ilio-costalis or Sacro-lumbalis (w. iliocostalis lumhorum), the external por- 
 tion of the Erector spinse, is inserted, generally, by six or seven flattened tendons into 
 the inferior borders of the angles of the six or seven lower ribs. The number of the 
 tendons of this muscle is, however, very variable, and therefore the number of ribs 
 into which it is inserted vary. Frequently it is found to possess nine or ten 
 tendons, and sometimes as many tendons as there are ribs, and is then inserted 
 into the angles of all the ribs. If this muscle is reflected outward, it will be 
 seen to be reinforced by a series of muscular sHps which arise from the angles 
 of the ribs ; by means of these the IHo-costalis is continued upward to the upper 
 ribs and cervical portion of the spine. The accessory portions form two additional 
 muscles, the Musculus accessorius and the Cervicalis ascendens. 
 
 The Musculus accessorius ad ilio-costalem {m. iliocostalis dorsi) arises, by separate 
 flattened tendons, from the upper borders of the angles of the six lower ribs: these 
 become muscular, and are finally inserted, by separate tendons, into the upper 
 borders of the angles of the six upper ribs and into the back of the transverse 
 processes of the seventh cervical vertebra. 
 
 The Cervicalis ascendens* (w. iliocostalis cervicis) is the continuation of the Acces- 
 sorius upward into the neck; it is situated on the inner side of the tendons of the 
 Accessorius, arising from the angles of the four or five upper ribs, and is inserted 
 by a series of slender tendons into the posterior tubercles of the transverse processes 
 of the fourth, fifth, and sixth cervical vertebrae. 
 
 The Longissimus dorsi is the middle and largest portion of the Erector spinse. 
 In the lumbar region, where it is as yet blended with the Ilio-costalis, some of the 
 fibres are attached to the whole length of the posterior surface of the transverse 
 processes and the accessory processes of the lumbar vertebrae, and to the middle 
 layer of the lumbar fascia. In the dorsal region, the Longissimus dorsi is inserted, 
 by long thin tendons, into the tips of the transverse processes of all the dorsal ver- 
 tebrae, and into from seven to eleven of the lower ribs between their tubercles and 
 angles. This muscle is continued upward to the cranium and cervical portion of 
 the spine by means of two additional muscles, the Transversalis cervicis and 
 Trachelo-mastoid. 
 
 The Transversalis cervicis or Transversalis colli {m. longissimus cervicis), placed 
 on the inner side of the Longissimus dorsi, arises by long thin tendons from the 
 summits of the transverse processes of the six upper dorsal vertebrae, and is 
 inserted by similar tendons into the posterior tubercles of the transverse pro- 
 cesses of the cervical vertebrae, from the second to the sixth inclusive. 
 
 The Trachelo-mastoid (m. longissimus capitis) lies on the inner side of the preced- 
 ing, V)etween it and the Complexus muscle. It arises, by tendons, from the trans- 
 verse processes of the five or six upper dorsal vertebrae, and the articular processes 
 of the three or four lower cervical. The fibres form a small muscle, which ascends 
 to be inserted into the posterior margin of the mastoid process, beneath the Splenius 
 and vSterno-mastoid muscles. This small muscle is almost always crossed by a 
 tendinous intersection near its insertion into the mastoid process.^ 
 
 The Spinalis dorsi connects the spinous processes of the upper lumbar and the 
 dorsal vertebrae together by a series of muscular and tendinous slips which are 
 
 ' This muscle is sometimes called "Cervicalis deseendens." The student should remember that these long 
 muecles take their fixed point from above or from below, according to circumstances. 
 
 ^ These two muscles (Transversalis cervicis and Trachelo-mastoid) are sometirnes described as one, having 
 a common origin, but dividing above at their insertion. The Trachelo-mastoid is then termed the Transver- 
 salis capitis. 
 
420 THE MUSCLES AND FASCIA 
 
 intimately blended with the Longissimus dorsi. It is situated at the inner side 
 of the Longissimus dorsi, arising, by three or four tendons, from the spinous 
 processes of the first two lumbar and the last two dorsal vertebrae: these, 
 uniting, form a small muscle, which is inserted, by separate tendons, into spinous 
 processes of the dorsal vertebrae, the number varying from four to eight. It is 
 intimately united with the Semispinalis dorsi, which lies beneath it. 
 
 The Spinalis colli (m. spinalis cervicis) is a small muscle, connecting together the 
 spinous processes of the cervical vertebrae, and analogous to the Spirialis dorsi in 
 the dorsal region. It varies considerably in its size and in its extent of attachment 
 to the vertebrae, not only in different bodies, but on the two sides of the same body. 
 It usually arises by fleshy or tendinous slips, varying from two to four in number, 
 from the spinous processes of the fifth, sixth, and seventh cervical vertebrae, and 
 occasionally from the first and second dorsal, and is inserted into the spinous 
 process of the axis, and occasionally into the spinous processes of the two vertebrae 
 below it. This muscle was found absent in five cases out of twenty-four. 
 
 Relations. — The Erector spinae and its prolongations are bound down to the 
 vertebrae and ribs in the lumbar and dorsal regions by the lumbar fascia and 
 the vertebral aponeurosis. The inner part of these muscles covers the muscles 
 of the fifth layer. In the neck they are in relation, by their superficial surface, with 
 the Trapezius and Splenius; by their deep surface, with the Semispinalis dorsi et 
 colli and the Recti and Obliqui. 
 
 The Gomplexus (m. semispinalis capitis) is a broad thick muscle, situated at the 
 upper and back part of the neck, beneath the Splenius, and internal to the Trans- 
 versalis cervicis and Trachelo-mastoid. It arises, by a series of tendons, from 
 the tips of the transverse processes of the upper six or seven dorsal and the last 
 cervical vertebrae, and from the articular processes of the three cervical above 
 this. The tendons, uniting, form a broad muscle, which passes obliquely upward 
 and inward, and is inserted into the innermost depression between the two curved 
 lines of the occipital bone. This muscle, about its middle, is traversed by a trans- 
 verse tendinous intersection. The biventer cervicis is a small fasciculus, situated 
 on the inner side of the preceding, and in the majority of cases blended with it; 
 it has received its name from having a tendon intervening between two fleshy 
 bellies. It is sometimes described as a part of the Complexus. It arises by from 
 two to four tendinous slips, from the transverse processes of as many of the upper 
 dorsal vertebrae, and is inserted, on the inner side of the Complexus, into the supe- 
 rior curved line of the occipital bone. 
 
 Relations. — The Complexus is covered by the Splenius and the Trapezius. It 
 lies on the Rectus capitis posticus major and minor, the Obliquus capitis superior 
 and inferior, and on the Semispinalis colli, from which it is separated by the pro- 
 funda cervicis artery, the princeps cervicis artery, and branches of the posterior 
 primary divisions of the cervical nerves. The Biventer cervicis is separated from 
 its fellow of the opposite side by the ligamentum nuchae. 
 
 The Fifth Layer (Fig. 283). 
 
 Semispinalis dorsi. Extensor coccygis. 
 
 Semispinalis colli. Intertransversales. 
 
 Multifidus spinae. Rectus capitis posticus major. 
 
 Rotatores spinae. Rectus capitis posticus minor. 
 
 Supraspinales. Obliquus capitis inferior. 
 
 Interspinales. Obliquus capitis superior. 
 
 Dissection. — Remove the muscles of the preceding layer by dividing and turning aside the 
 Complexus; then detach the Spinalis and Longissimus dorsi from their attachments, divide the 
 Erector spinae at its connection below to the sacral and lumbar spines and turn it outward. The 
 muscles filling up the interval between the spinous and transverse processes are then exposed. 
 
OF THE BACK 42i 
 
 The Semispinalis Dorsi consists of thin, narrow, fleshy fasciculi interposed 
 between tendons of considerable length. It arises by a series of small tendons 
 from the transverse processes of the lower dorsal vertebrae, from the tenth or 
 eleventh to the fifth or sixth; and is inserted, by five or six tendons, into the 
 spinous processes of the upper four dorsal and lower two cervical vertebrae. 
 
 The Semispinalis Colli [in. semispinalis cervicis), thicker than the preceding, 
 arises by a series of tendinous and fleshy fibres from the transverse processes of 
 the upper five or six dorsal vertebrae, and is inserted into the spinous processes of 
 four cervical vertebrae, from the axis to the fifth cervical. The fasciculus con- 
 nected with the axis is the largest, and chiefly muscular in structure. 
 
 Relations.— By their superficial surface, from below upward, with the Spinalis 
 dorsi, Longissimus dorsi, Splenius, Complexus, the profunda cervicis artery, the 
 princeps cervicis artery, and the internal branches of the posterior divisions of 
 the first, second, and third cervical nerves; by their deep surface, with the Mul- 
 tifidus spinse. 
 
 The Multifidus Spinse (m. multifidus) consists of a number of fleshy and ten- 
 dinous fasciculi which fill up the groove on either side of the spinous processes of the 
 vertebrae, from the sacrum to the axis. In the sacral region these fasciculi arise from 
 the back of the sacrum, as low as the fourth sacral foramen, and from the aponeu- 
 rosis of origin of the Erector spinae; from the inner surface of the posterior superior 
 spine of the ilium and posterior sacro-iliac ligaments; in the lumbar regions, from 
 the articular processes; in the dorsal region, from the transverse processes; and in 
 the cervical region, from the articular processes of the three or four lower vertebrae. 
 Each fasciculus, passing obliquely upward and inward, is inserted into the whole 
 length of the spinous process of one of the vertebrae above. These fasciculi vary 
 in length: the most superficial, the longest, pass from one vertebra to the third or 
 fourth above; those next in order pass from one vertebra to the second or third 
 above; whilst the deepest connect two contiguous vertebrae. 
 
 Relations. — By its superficial surface, with the Longissimus dorsi. Spinalis dorsi, 
 Semispinalis dorsi, and Semispinalis colli; by its deep surface, with the laminae 
 and spinous processes of the vertebrae, and with the Rotatores spinae in the dorsal 
 region. 
 
 The Rotatores Spinse (mm. rotatores) are found only in the dorsal region of the 
 spine, beneath the Multifidus spinae; they are eleven in number on each side. Each 
 muscle is small and somewhat quadrilateral in form; it arises from the upper and 
 back part of the transverse process, and is inserted into the lower border and outer 
 surface of the lamina of the vertebra above, the fibres extending as far inward as 
 the root of the spinous process. The first is found between the first and second 
 dorsal ; the last, between the eleventh and twelfth. Sometimes the number of these 
 muscles is diminished by the absence of one or more from the upper or lower end. 
 
 The Supraspinales consist of a series of fleshy bands which lie on the spinous 
 processes in the cervical region of the spine. 
 
 The Interspinales are short muscular fasciculi, placed in pairs between the 
 spinous processes of the contiguous vertebrae, one on each side of the interspinous 
 ligament. In the cervical region they are most distinct, and consist of six pairs, 
 the first being situated between the axis and third vertebra, and the last between 
 the last cervical and the first dorsal. They are small narrow bundles, attached, 
 above and below, to the apices of the spinous processes. In the dorsal region 
 they are found between the first and second vertebrae, and occasionally between 
 the second and third; and below, between the eleventh and twelfth. In the 
 lumbar region there are four pairs of these muscles in the intervals between the 
 five lumbar vertebrae. There is also occasionally one in the interspinous space, 
 between the last dorsal and first lumbar, and between the fifth lumbar and the 
 sacrum. 
 
422 THE MUSCLES AND FASCIA 
 
 The Extensor Coccygis is a slender muscular fasciculus, occasionally present, 
 which extends over the lower part of the posterior surface of the sacrum and 
 coccyx. It arises by tendinous fibres from the last bone of the sacrum or first 
 piece of the coccyx, and passes downward to be inserted into the lower part of 
 the coccyx. It is a rudiment of the Extensor muscle of the caudal vertebrae of 
 the lower animals. 
 
 The Intertransversales {mm. intertransversarii) are small muscles placed 
 between the transverse processes of the vertebrae. In the cervical region they are 
 most developed, consisting of rounded muscular and tendinous fasciculi, which are 
 placed in pairs, passing between the anterior and the posterior tubercles of the 
 transverse processes of two contiguous vertebrae, separated from one another by 
 the anterior division of the cervical nerve, which lies in the groove between them. 
 In this region there are seven pairs of these nmscles, the first pair being between 
 the atlas and axis, and the last pair between the seventh cervical and first dorsal 
 vertebrae. In the dorsal region they are least developed, consisting chiefly of 
 rounded tendinous cords in the intertransverse spaces of the upper dorsal vertebrae; 
 but between the transverse processes of the lower three dorsal vertebrae, and 
 between the transverse processes of the last dorsal and the first lumbar, they are 
 muscular in structure. In the lumbar region they are arranged in pairs, on either 
 side of the spine, one set occupying the entire interspace between the transverse 
 processes of the lumbar vertebrae, the intertransversales laterales {mm. intertrans- 
 versarii laterales) ; the other set, intertransversales mediales {mm. intertransversarii 
 mediates) , passing from the accessory process of one vertebra to the mammillary 
 process of the next. 
 
 The Rectus Capitis Posticus Major {m. rectus capitis posterior major) arises by 
 a pointed tendinous origin from the spinous process of the axis, and, becoming 
 broader as it ascends, is inserted into the inferior curved line of the occipital bone 
 and the surface of bone immediately below it. As the muscles of the two sides pass 
 upward and outward, they leave between them a triangular space, in which are 
 seen the Recti capitis postici minores muscles. 
 
 Relations. — By its superficial surface, with the Complexus, and, at its insertion, 
 with the Superior oblique; by its deep surface, with part of the Rectus capitis 
 posticus minor, the posterior arch of the atlas, the posterior occipito-atlantal liga- 
 ment, and part of the occipital bone. 
 
 The Rectus Capitis Posticus Minor (w. rectus capitis posterior minor), the small- 
 est of the four muscles in this region, is of a triangular shape; it arises by a narrow 
 pointed tendon from the tubercle on the posterior arch of the atlas, and, becom- 
 ing broader as it ascends, is inserted into the rough surface beneath the inferior 
 curved line, nearly as far as the foramen magnum, nearer to the middle line than 
 the preceding. 
 
 Relations. — By its superficial surface, with the Complexus and the Rectus capitis 
 posticus major; by its deep surface, with the posterior occipito-atlantal ligament. 
 
 The Obliquus Capitis Inferior, the larger of the two Oblique muscles, arises 
 from the apex of the spinous process of the axis, and passes outward and slightly 
 upward, to be inserted into the lower and back part of the transverse process of 
 the atlas. 
 
 Relations. — By its superficial surface, with the Complexus and with the pos- 
 terior division of the second cervical nerve, which crosses it; by its deep surface, 
 with the vertebral artery and posterior atlanto-axial ligament. 
 
 The Obliquus Capitis Superior, narrow below, wide and expanded above, 
 arises by tendinous fibres from the upper surface of the transverse process of the 
 atlas, joining with the insertion of the preceding, and, passing obliquely upward 
 and inward, is inserted into the occipital bone, between the two curved lines, 
 external to the Complexus. 
 
OF THE BACK 423 
 
 Relations. — By its superficial surface, with the Complexus and Trachelo-mastoid 
 and occipital artery. By its deep surf ace, with the posterior occipito-atlantal Hgament. 
 
 Between the two obhque muscles and the Rectus capitis posticus major a trian- 
 gular interval exists, the suboccipital triangle. This triangle is bounded, above 
 and internally, by the Rectus capitis posticus major; above and externally, by the 
 Obliquus capitis superior; below and externally, by the Obliquus capitis inferior. 
 It is covered in by a layer of dense fibro-fatty tissue, situated beneath the Com- 
 plexus muscle. The floor is formed by the posterior occipito-atlantal ligament 
 and the posterior arch of the atlas. It contains the vertebral artery, as it runs in 
 a deep groove on the upper surface of the posterior arch of the atlas, and the pos- 
 terior division of the suboccipital nerve. 
 
 Nerves.— The third, fourth, and fifth layers of the muscles of the back are 
 supplied by the posterior primary divisions of the spinal nerves. 
 
 Actions. — When both the Spinales dorsi contract, they extend the dorsal region 
 of the spine; when only one muscle contracts, it helps to bend the dorsal por- 
 tion of the spine to one side. The Erector spinse, comprising the Ilio-costalis and 
 the Ivongissimus dorsi with their accessory muscles, serves, as its name implies, 
 to maintain the spine in the erect posture; it also serves to bend the trunk back- 
 ward when it is required to counterbalance the influence of any weight at the 
 front of the body, as, for instance, when a heavy weight is suspended from the 
 neck, or when there is any great abdominal distention, as in pregnancy or dropsy; 
 the peculiar gait under such circumstances depends upon the spine being drawn 
 backward by the counterbalancing action of the Erector spinse muscles. The 
 muscles which form the continuation of the Erector spinse upward steady the 
 head and neck, and fix them in the upright position. If the Ilio-costalis and 
 Longissimus dorsi of one side act, they serve to draw down the chest and spine to 
 the corresponding side. The Cervicales ascendens, taking their fixed points from 
 the cervical vertebrae, elevate those ribs to which they are attached; taking their 
 fixed points from the ribs, both muscles help to extend the neck; while one muscle 
 bends the neck to its own side. The Trans versalis cervicis, when both muscles act, 
 taking their fixed point from below, bend the neck backward. The Trachelo- 
 mastoid, when both muscles act, taking their fixed point from below, bend the head 
 backward; while, if only one muscle acts, the face is turned to the side on which 
 the muscle is acting, and then the head is bent to the shoulder. The two Recti 
 muscles draw the head backward. The Rectus capitis posticus major, owing to 
 its obliquity, rotates the cranium, with the atlas, round the odontoid process, 
 turning the face to the same side. The Multifidus spinte acts successively upon the 
 different parts of the spine; thus, the sacrum furnishes a fixed point from which 
 the fasciculi of this muscle act upon the lumbar region; these then become the 
 fixed points for the fasciculi moving the dorsal region, and so on throughout the 
 entire length of the spine; it is by the successive contraction and relaxation of 
 the separate fasciculi of this and other muscles that the spine preserves the erect 
 posture without the fatigue that would necessarily have been produced had this 
 position been maintained by the action of a single muscle. The Multifidus spinae, 
 besides preserving the erect position of the spine, serves to rotate it, so that the 
 front of the trunk is turned to the side opposite to that from which the muscle 
 acts, this muscle being assisted in its action by the Obliquus externus abdominis. 
 The Complexi draw the head directly backward: if one muscle acts, it draws 
 the head to one side, and rotates it so that the face is turned to the opposite 
 side. The Superior oblique draws the head backward, and, from the obliquity 
 in the direction of its fibres, will slightly rotate the cranium, turning the face to 
 the opposite side. The Obliquus capitis inferior rotates the atlas, and with it the 
 cranium, round the odontoid process, turning the face to the same side. The 
 Semispinales, when the muscles of the two sides act together, help to extend thq 
 
424 THE MUSCLES AND FASCIA 
 
 spine; when the muscles of one side only act, they rotate the dorsal and cervical 
 parts of the spine, turning the body to the opposite side. The Supraspinales and 
 Interspinales by approximating the spinous processes help to extend the spine. 
 The Intertransversales approximate the transverse processes, and help to bend the 
 spine to one side. The Rotatores spinie assist the Multifidus spinse to rotate the 
 spine, so that the front of the trunk is turned to the side opposite to that from 
 which the muscle acts. 
 
 Surface Forms. — The surface forms produced by the muscles of the back are numerous and 
 difficult to analyze unless they are considered in systematic order. The most superficial layer, 
 consisting of large strata of muscular substance, influences to a certain extent the surface form, 
 and at the same time reveals the forms of the layers beneath. The Trapezius at the upper part 
 of the back, and in the neck, covers over and softens down the outline of the underlying muscles. 
 Its anterior border forms the posterior boundary of the posterior triangle of the neck. It forms 
 a slight undulating ridge which passes downward and forward from the occiput to the junction 
 of the middle and outer third of the clavicle. The tendinous ellipse formed by a part of the 
 origin of the two muscles at the back of the neck is always to be seen as an oval depression, 
 more marked when the muscle is in action. A slight dimple on the skin opposite the interval 
 between the spinous processes of the third and fourth dorsal vertebrae marks the triangular 
 aponeurosis by which the inferior fibres are inserted into the root of the spine of the scapula. 
 From this point the inferior border of the muscle may be traced as an undulating ridge to the 
 spinous process of the twelfth dorsal vertebra. In like manner the Latissimus dorsi softens 
 down and modulates the underlying structures at the lower part of the back and lower part of 
 the side of the chest. In this way it modulates the outline of the Erector spinae; of the Serratus 
 posticus inferior, which is sometimes to be discerned through it, and is sometimes entirely 
 obscured by it; of part of the Serratus magnus and Superior oblique, which it covers; and of 
 the convex oblique ridges formed by the ribs with the intervening intercostal spaces. The 
 anterior border of the muscle is the only part which gives a distinct surface form. This border 
 may be traced, when the muscle is in action, as a rounded edge, starting from the crest of the 
 ilium, and passing obliquely forward and upward to the posterior border of the axilla, where it 
 combines with the Teres major in forming a thick rounded fold, the posterior boundary of the 
 axillary space. The muscles in the second layer influence to a very considerable extent the sur- 
 face form of the back of the neck and upper part of the trunk. The Levator anguli scapulae 
 reveals itself as a prominent divergent line, running downward and outward, from the trans- 
 verse processes of the upper cervical vertebrae to the angle of the scapula, covered over and 
 toned down by the overlying Trapezius. The Rhomboidei produce, when in action, a vertical 
 eminence between the vertebral border of the scapula and the spinal furrow, varying in intensity 
 according to the condition of contractioij or relaxation of the Trapezius muscle, by which they 
 are for the most part covered. The lowermost part of the Rhomboideus major is uncovered 
 by the Trapezius, and forms on the surface an oblique ridge running upward and inward from 
 the inferior angle of the scapula. Of the muscles of the third layer of the back, the Serratus 
 posticus superior does not in any way influence surface form. The Serratus posticus inferior, 
 when in strong action, may occasionally be revealed as an elevation beneath the Latissimus 
 dorsi. The Splenii by their divergence serve to broaden out the upper part of the back of the 
 neck and produce a local fulness in this situation, but do not otherwise influence surface form. 
 Beneath all these muscles those of the fourth layer — the Erector spince and its continuations — 
 influence the surface form in a decided manner. In the loins, the Erector spinse, bound down 
 by the lumbar fascia, forms a rounded vertical eminence, which determines the depth of the 
 spinal furrow, and which below tapers to a point on the posterior surface of the sacrum and 
 becomes lost there. In the back it forms a flattened plane which gradually becomes lost. In 
 the neck the only part of this group of muscles which influences surface form is the Trachelo- 
 mastoid, which produces a short convergent line across the upper part of the posterior triangle 
 of the neck, appearing from under cover of the posterior border of the Sterno-mastoid and 
 being lost below beneath the Trapezius. 
 
 II. MUSCLES AND FASCIiE OF THE THORAX. 
 
 The muscles belonging exclusively to this region are few in number. They are the 
 
 Intercostales externi. Triangularis sterni. 
 
 Intercostales interni. I^evatores costarum. 
 
 Infracostales. Diaphragm. 
 
 Intercostal Fascia. — A thin but firm layer of fascia covers the outer surface of 
 the External intercostal and the inner surface of the Internal intercostal muscles; 
 
OF THE THORAX 425 
 
 and a third layer, more delicate, is interposed between the two planes of muscular 
 fibres. These are the intercostal fasciae, external, viiddle, and internal; they are best 
 marked in those situations where the muscular fibres are deficient, as between the 
 External intercostal muscles and sternum, in front, and between the Internal 
 intercostals and spine, behind. 
 
 The Intercostal Muscles (Figs. 291 and 315) are two thin planes of muscular 
 and tendinous fibres, placed one over the other, filling up the intercostal spaces, 
 and being directed obliquely between the margins of the adjacent ribs. They 
 have received the name external and internal from the position they bear to one 
 another. The tendinous fibres are longer and more numerous than the muscular; 
 hence the walls of the intercostal spaces possess very considerable strength, to 
 which the crossing of the muscular fibres materially contributes. 
 
 The External Intercostals (mm. intercostales externi) are eleven in number on 
 each side. They extend from the tubercles of the ribs, behind, to the commence- 
 ment of the cartilages of the ribs, in front, where they terminate in a thin mem- 
 brane, the anterior intercostal membrane, which is continued forward to the sternum. 
 They arise from the lower border of the rib above, and are inserted into the upper 
 border of the rib below. In the two lowest spaces they extend to the ends of the 
 cartilages, and in the upper two or three spaces they do not quite extend to the ends 
 of the ribs. Their fibres are directed obliquely downward and forward, in a 
 similar direction with those of the External oblique muscle of the abdomen. 
 They are thicker than the Internal intercostals. 
 
 Relations. — By their oider surface, with the muscles which immediately invest 
 the chest — viz., the Pectoralis major and minor, Serratus magnus, and Rhom- 
 boideus major, Serratus posticus superior and inferior. Scalenus posticus, Ilio- 
 costalis, Longissimus dorsi, Cervicalis ascendens, Transversalis cervicis, I>eva- 
 tores costarum, Obliquus externus abdominis, and the Latissimus dorsi; by their 
 internal surface, with the middle intercostal fascia, which separates them from the 
 intercostal vessels and nerve and the Internal intercostal muscles, and, behind, 
 from the pleura. 
 
 The Internal Intercostals (mw. intercostales interni) are also eleven in number on 
 each side. They commence anteriorly at the sternum in the interspaces between 
 the cartilages of the true ribs, and from the anterior extremities of the cartilages 
 of the false ribs, and extend backward as far as the angles of the ribs, whence they 
 are continued to the vertebral column by a thin aponeurosis, the 'posterior inter- 
 costal membrane. They arise from the ridge on the inner surface of the rib above, 
 as well as from the corresponding costal cartilage, and are inserted into the upper 
 border of the rib below. Their fibres are directed obliquely downward and back- 
 ward, passing in the opposite direction to the fibres of the External intercostal 
 muscle. 
 
 Relations. — By their external surface, with the intercostal vessels and nerves 
 and the External intercostal muscles; near the sternum, with the anterior inter- 
 costal membrane and the Pectoralis major. By their internal surface, with the 
 pleura costalis. Triangularis sterni, and Diaphragm. 
 
 The Infracostales (mm. subcostales) consist of muscular and aponeurotic fas- 
 ciculi, which vary in number and length; they are placed on the inner surface of the 
 ribs, where the Internal intercostal muscles cease; they arise from the inner sur- 
 face of one rib, and are inserted into the inner surface of the first, second, or third 
 rib below. Their direction is most usually oblique, like the Internal intercostals. 
 They are most frequent between the lower ribs. 
 
 The Triangularis Sterni (m. transversus thoracis) (Fig. 284) is a thin plane of 
 muscular and tendinous fibres, situated upon the inner wall of the front of the chest. 
 It arises from the lower third of the posterior surface of the sternum, from the 
 posterior surface of the ensiform cartilage, and from the sternal ends of the costal 
 
426 
 
 THE MUSCLES AND FASCIAE 
 
 cartilages of the three or four lower true ribs. Its fibres diverge upward and out- 
 ward, to be inserted by digitations into the lower borders and inner surfaces of the 
 costal cartilages of the second, third, fourth, fifth, and sixth ribs. The lowest 
 fibres of this muscle are horizontal in their direction, and are continuous with 
 those of the Transversalis ; those which succeed are oblique, whilst the superior 
 fibres are almost vertical. This muscle varies much in its attachment, not only in 
 different bodies, but on opposite sides of the same body. 
 
 Relations. — In front, with the sternum, ensiform cartilage, costal cartilages, 
 Internal intercostal muscles, and internal mammary vessels; behind, with the 
 pleura, pericardium, and anterior mediastinum. 
 
 STERNO-MASTOID 
 
 SUBCLAVIUS 
 
 SUBCLAVIUS. 
 
 Internal mam,' 
 mary artery. 
 
 TRIANGULARIS 
 STERN I. 
 
 TRANSVERSALIS ABDOMINIS. 
 
 Fig. 284. — Posterior surface of sternum and costal cartilages, showing Triangularis sterni muscle (From a 
 preparation in the Museum of the Royal College of Surgeons of England.) 
 
 The Levatores Costarum (Fig. 283), twelve in number on each side, are small 
 tendinous and fleshy bundles which arise from the extremities of the transverse 
 processes of the seventh cervical and eleven upper dorsal vertebrae, and, passing 
 obliquely downward and outward, are inserted into the upper border of the rib 
 below them, between the tubercle and the angle. The Inferior levatores divide 
 into two fasciculi, one of which is inserted as above described; the other fasciculus 
 passes down to the second rib below its origin ; thus, each of the lower ribs receives 
 fibres from the transverse processes of two vertebrfe. 
 
 Nerves. — The muscles of this group are supplied by the intercostal nerves. 
 
OF THE THORAX 
 
 427 
 
 The Diaphragm (diaphragma, from d:d(foayna, a partition wall) (Figs. 285, 286, 
 and 287) is a thin, musculo-fibrous septum, consisting of muscular fibres externally, 
 which arise from the circumference of the thoracic cavity and pass upward and 
 inward to converge to a central tendon. It is placed obliquely at the junction of 
 the upper with the middle third of the trunk, and separates the thorax from the 
 abdomen, forming the floor of the former cavity and the roof of the latter. It is 
 elliptical, its longest diameter being from side to side; is somewhat fan-shaped, the 
 broad elliptical portion being horizontal, the narrow part, the crura, which repre- 
 sents the handle of the fan, vertical, and joined at right angles to the former. It 
 is from this circumstance that some anatomists describe it as consisting of two 
 portions, the upper or great muscle of the Diaphragm, and the lower or lesser 
 muscle. It arises from the whole of the internal circumference of the thorax, 
 being attached, in front, by fleshy fibres to the ensiform cartilage, sternal portion 
 of the Diaphragm (pars sternalis); on either side, to the inner surface of the 
 cartilages and bony portions of the six or seven inferior ribs, costal portion (pars 
 costalis), interdigitating with the Transversalis; and behind, to two aponeurotic 
 arches, named the ligamentum arcuatum externum and the ligamentum arcuatum 
 internum, and by the crura, to the lumbar vertebrae, lumbar portion (pars lumhalis). 
 The fibres from these sources vary in length: those arising from the ensiform 
 appendix are very short and occasionally aponeurotic; those from the ligamenta 
 arcuata, and more especially those from the cartilages of the ribs at the side 
 of the chest, are longer, describe well-marked curves as they ascend, and finally 
 converge to be inserted into the circumference of the central tendon. Between 
 the sides of the muscular slip from the ensiform appendix and the cartilages of 
 the adjoining ribs the fibres of the Diaphragm are deficient, the interval being 
 filled by areolar tissue, covered on the thoracic side by the pleurae; on the abdom- 
 inal, by the peritoneum. This is, consequently, a weak point, and a portion of 
 the contents of the abdomen may protrude through it into the chest, forming a 
 phrenic or diaphragmatic hernia, or a collection of pus in the mediastinum may 
 descend through it, so as to point at the epigastrium. A triangular gap is some- 
 times seen between the fibres springing from the internal and those arising from 
 the external arcuate ligament. When it exists, the kidney is separated from the 
 pleura only by fatty and areolar tissue. 
 
 A congenital deficiency in the Diaphragm may produce diaphragmatic hernia; 
 in deficiency of the central tendon the hernia passes into the pericardial sac; in 
 deficiency of one of the lateral portions the hernia passes into the pleural sac. 
 
 There are five arcuate ligaments, two internal, two external, and one middle. 
 
 The Ligamentum Arcuatum Internum (arcus lumbocostalis medialis) is a tendinous 
 arch, thrown across the upper part of the Psoas magnus muscle, on each side of 
 the spine. It is connected, by one end, to the outer side of the body of the first or 
 second lumbar vertebra, being continuous with the outer side of the tendon of 
 the corresponding crus ; and, by the other end, to the front of the transverse process 
 of the first, and sometimes also to that of the second, lumbar vertebra. 
 
 The Ligamentum Arcuatimi Externum (arcus lumbocostalis lateralis) is the thick- 
 ened upper margin of the anterior lamella of the lumbar fascia; it arches across 
 the upper part of the Quadratus lumborum, being attached, by one extremity, to 
 the front of the transverse process of the first lumbar vertebra, and, by the other, 
 to the apex and lower margin of the last rib. 
 
 The arch of fibrous tissue which connects the crura of the diaphragm in front 
 of the aorta is sometimes called the middle arcuate ligament. The Diaphragm is 
 connected to the spine by two crura or pillars, which are situated on the bodies of 
 lumbar vertebrae, on each side of the aorta. The crura, at their origin, are ten- 
 dinous in structure; the right crus, larger and longer than the left, arising from 
 the anterior common ligament and intervertebral substances of the three or four 
 
428 
 
 THE MUSCLES AND FASCIAE 
 
 upper lumbar vertebrse; the left, from the two upper lumbar vertebrae. These 
 tendinous portions of the crura pass forward and inward, and gradually con- 
 
 CESOPHAGUS 
 
 FORAMEN QUADRATUM 
 FOR VENA CAVA 
 
 CENTRAL TENDON, 
 LEFT SIDE 
 
 AORTA CENTRAL TENDON, 
 
 RIGHT SIDE 
 
 Fig. 285. — The Diaphragm, seen from above. (Poirier and Charpy.) 
 
 Fig. 286.— The Diaphragm, Meised from in front. (Testut.) 
 
 verge to meet in the middle line, forming an arch, beneath which passes the 
 aorta, vena azygos major, and thoracic duct. From this tendinous arch muscular 
 fibres arise, which diverge, the outermost portion being directed upward and 
 
OF THE THORAX 
 
 429 
 
 outward to the central tendon; the innermost decussating in front of the aorta 
 and then diverging, so as to surround the oesophagus before ending in the central 
 tendon. The fibres derived from the right crus are the most numerous and pass 
 in front of those derived from the left. His and Spalteholz teach that three crura 
 exist on each side — viz., the crus mediale, arising from the third and fourth lumbar 
 vertebrae; the crus intermedium, from the second and third lumbar vertebrte; and 
 the crus laterale, from the second or first lumbar vertebrae, and from the band of 
 fascia which is stretched between the lateral part of the body of the first lumbar 
 vertebra and the transverse process of the second lumbar vertebra in front of the 
 Psoas muscle. 
 
 The Central or Cordiform Tendon of the Diaphragm {centrum tendineum) is a thin 
 but strong tenflinous aponeurosis, situated at the centre of the vault formed by 
 the muscle, immediately below the pericardium, with which it is partly blended. 
 It is shaped somewhat like a trefoil leaf, consisting of three divisions, or leaflets. 
 
 Fig. 287. — The Diaphragm, viewed from below. (Testut.) 
 
 separated from one another by slight indentations. The right leaflet is the largest; 
 the middle one, directed toward the ensiform cartilage, the next in size; and the 
 left, the smallest. In structure, the tendon is composed of several planes of fibres 
 which intersect one another at various angles, and unite into straight or curved 
 bundles — an arrangement which affords it additional strength. 
 
 The Openings. — The openings connected with the Diaphragm are three large 
 and several smaller apertures. The former are the aortic, the oesophageal, and the 
 opening for the vena cava. 
 
 The Aortic Opening (hiatus aorticus) is the lowest and the most posterior of the 
 three large apertures connected with this muscle, being at the level of the first 
 lumbar vertebra. It is situated slightly to the left of the middle line, immediately 
 in front of the bodies of the vertebrsTp; and is, therefore, behind the Diaphragm, not 
 in it. It is an osseo-aponeurotic aperture, formed by a tendinous arch thrown 
 across the front of the bodies of the vertebrae, from the crus on one side to that 
 on the other, and transmits the aorta, vena azygos major, and thoracic duct. 
 Sometimes the vena azygos major is transmitted upward through the right crus. 
 
430 THE MUSCLES AND FASCIA 
 
 Occasionally some tendinous fibres are prolonged across the bodies of the ver- 
 tebrae from the inner part of the lower end of the crura, passing behind the aorta, 
 and thus converting the opening into a fibrous ring. 
 
 The OEsophageal Opening {hiatus cesophageus) is situated at the level of the tenth 
 dorsal vertebrae; it is elliptical in form, oblique in direction, muscular in structure, 
 and, formed by the decussating fibres of the two crura, is placed above, and, at 
 the same time, anterior, and a little to the left of the preceding. It transmits the 
 oesophagus and pneumogastric nerves and some small oesophageal arteries. The 
 anterior margin of this aperture is occasionally tendinous, being formed by the 
 margin of the central tendon. The posterior and lateral margins are thick and 
 the gullet is in contact with them for about half an inch. The right margin of 
 the oesophageal opening is particularly prominent and lies in the oesophageal 
 groove on the posterior surface of the left lobe of the liver. 
 
 The Opening for the Vena Cava or the Foramen Quadratum (foramen vence cavoe) 
 is the highest opening, being about on the level of the disk between the eighth 
 and ninth dorsal vertebrae; it is quadrilateral in form, tendinous in structure, and 
 placed at the junction of the right and middle leaflets of the central tendon, 
 its margins being adherent to the wall of the inferior vena cava. 
 
 The right cms transmits the greater and lesser splanchnic nerves of the right 
 side; the left crus transmits the greater and lesser splanchnic nerves of the left 
 side, and the vena azygos minor. The gangliated cords of the sympathetic 
 usually enter the abdominal cavity by passing behind the internal arcuate liga- 
 ments. 
 
 Serous Membranes. — The serous membranes in relation with the Diaphragm are 
 four in number: three lining its upper or thoracic surface; one, its abdominal. The 
 three serous membranes on its upper surface are the pleura on either side and the 
 pericardium, which covers the middle portion of the tendinous centre. The 
 serous membrane covering the under surface of the Diaphragm is a portion of 
 the general peritoneal membrane of the abdominal cavity. 
 
 The Diaphragm is arched, being convex toward the chest and concave toward the 
 abdomen. The right portion forms a complete arch from before backward, being 
 accurately moulded over the convex surface of the liver, and having resting upon 
 it the concave base of the right lung. The left portion is arched from before back- 
 ward in a similar manner; but the arch is narrower in front, being encroached upon 
 by the pericardium, and lower than the right, at its summit, by about three-quarters 
 of an inch. It supports the base of the left lung, and covers the great end of the 
 stomach, the spleen, and left kidney. At its circumference the Diaphragm is 
 higher in the mesial line of the body than at either side; but in the middle of the 
 thorax the central portion, which supports the heart, is on a lower level than the 
 two lateral portions. 
 
 Nerves. — The Diaphragm is supplied by the phrenic nerves, the lower inter- 
 costal nerves and the phrenic plexus of the sympathetic. 
 
 Actions. — The Intercostals are the chief agents in the movement of the ribs 
 in ordinary respiration. When the first rib is elevated and fixed by the Scaleni, the 
 External intercostals raise the other ribs, especially their forepart, and so increase 
 the capacity of the chest from before backward ; at the same time they evert their 
 lower borders, and so enlarge the thoracic cavity transversely. The Internal 
 intercostals, at the side of the thorax, depress the ribs and invert their lower 
 borders, and so diminish the thoracic cavity; but at the forepart of the chest these 
 muscles assist the External intercostals in raising the cartilages.* The Levatores 
 
 ^ The view of the action of the Intercostal muscles given in the text is that which is taught by Hutchinson 
 (Cycl. of Anat. and Phys., art. Thorax), and is usually adopted in our schools. It is, however, much dis- 
 puted. Hamberger believed that the External intercostals act as elevators of the ribs, or muscles of inspira- 
 tion, while the internal act in expiration. Haller taught that both sets of muscles act in common — viz., as muscles 
 of inspiration — and this view is adopted by many of the best anatomists of the Continent, and appears sup- 
 
OF THE THORAX 43 1 
 
 costarum assist the External intercostals in raising the ribs. The Triangularis 
 sterni draws flown the costal cartilages; it is therefore an expiratory muscle. 
 
 The Diaphragm is the principal muscle of inspiration. When in a condition 
 of rest the muscle presents a domed surface, concave toward the abdomen; and 
 consists of a circumferential muscular and a central tendinous part. When 
 the muscular fibres contract, they become less arched, or nearly straight, and 
 thus cause the central tendon to descend, and in consequence the level of the 
 chest-wall is lowered, the vertical diameter of the chest being proportionally 
 increased. In this descent the different parts of the tendon move unequally. 
 The left leaflet descends to the greatest extent; the right to a less extent, on 
 account of the liver; and the central leaflet the least, because of its connection to 
 the pericardium. In descending the Diaphragm presses on the abdominal viscera, 
 and so to a certain extent causes a projection of the abdominal wall; but in conse- 
 quence of these viscera not yielding completely, the central tendon becomes a fixed 
 point, and enables the circumferential muscular fibres to act from it, and so elevate 
 the lower ribs and expand the lower part of the thoracic cavity; and Duchenne 
 has shown that the Diaphragm has the power of elevating the ribs, to which it 
 is attached, by its contraction, if the abdominal viscera are in situ, but that if these 
 organs are removed, this power is lost. When at the end of inspiration the Dia- 
 phragm relaxes, the thoracic walls return to their natural position in consequence 
 of their elastic reaction and of the elasticity and weight of the displaced viscera.^ 
 
 In all expulsive acts the Diaphragm is called into action, to give additional 
 power to each expulsive effort. Thus, before sneezing, coughing, laughing, and 
 crying, before vomiting, previous to the expulsion of the urine and faeces, or of 
 the foetus from the womb, a deep inspiration takes place. 
 
 The height of the Diaphragm is constantly varying during respiration, the 
 muscle being carried upward or downward from the average level; its height also 
 varies according to the degree of distention of the stomach and intestines, and the 
 size of the liver. After a forced expiration, the right arch is on a level, in front, 
 with the fourth costal cartilage; at the side, with the fifth, sixth, and seventh 
 ribs; and behind, with the eighth rib, the left arch being usually from one to two 
 ribs' breadth below the level of the right one. In a forced inspiration, it descends 
 from one to two inches; its slope would then be represented by a fine drawn 
 from the ensiform cartilage toward the tenth rib. Prof. Wm. S. Forbes^ is of the 
 opinion that the Diaphragm is an appendage of the circulatory apparatus rather 
 than the chief agent in respiration. He maintains that the opening in the 
 vena cava is stationary and holds a constant relation to the ninth dorsal verte- 
 bra. He emphasizes the fact that the base of the pericardium is attached to the 
 central tendon of the Diaphragm, and on the anterior and left side. The muscular 
 fibres of the Diaphragm ascend upon and are attached to the pericardium. Pro- 
 longations of the fibrous pericardium pass upward as the pericardial ligaments. 
 These ligaments form fibrous planes reaching from each side of the central 
 tendon of the Diaphragm to the " bony apex of the thoracic line " and to the 
 fascia stretched across the thoracic apex, and they may be called the " superior 
 tendinous crura." It is thus evident that the deep cervical fascia is connected 
 to the lateral and superior parts of the pericardium. At birth the muscular 
 
 ported by many observations made on the human subject under various conditions of disease, and on living 
 animals after the muscles have been exposed under chloroform. The reader may consult an interestmg paper 
 bv Dr. Cleland in the Journal of Anat. and Phys., No. II., May, 1867, p. 209, On the Hutchmsonian Theory 
 of the Action of the Intercostal Muscles, who refers also to Henle, Luschka, Budge, and Baumler, Observa- 
 tions on the Action of the Intercostal Muscles, Eriangen, 1860. (In New Syd. Soc. s Year-book for 1861, p. 69.) 
 Dr. W. W. Keen has come to the conclusion, from experiments made upon a crimmal executed by hangmg, 
 that the External intercostals are muscles of expiration, as they pulled the ribs down, while the Internal inter- 
 costals pulled the ribs up and are muscles of inspiration (Trans. Coll. Phys., Philadelphia, Third beries, vol. i., 
 
 > For a detailed description of the general relations of the Diaphragm, and its action, refer to Dr. Sibson's 
 Medical Anatomy. 
 
 * American Journal of the Medical Sciences, July, 1880. 
 
432 THE MUSCLES AND FASCIAE 
 
 fibres of the Diaphragm contract at the first inspiration. The ductus arteriosus 
 is lodged in an elhptical opening of a tendinous scaflolding. The contractions 
 of the Diaphragm cause the tendinous scafi^olding to. compress the ductus arteri- 
 osus " and eventually close it." The chief agents in the compression are the 
 muscular fibres which pass from the Diaphragm to the pericardium. When the 
 lateral wings of the Diaphragm descend they tend to form a vacuum in the thorax 
 and thus assist the venous circulation. 
 
 " The descent of the Diaphragm is not necessary to respiration," but it " is 
 necessary in order to protect the heart from the movement of surrounding 
 viscera, and in order to promote the free circulation of the blood through the 
 vessels forming the cardiac roots." 
 
 Muscles of Inspiration and Expiration. — The muscles which assist the action 
 of the Diaphragm in ordinary tranquil inspiration are the Intercostals and the 
 Levatores costarum, as above stated, and the Scaleni. When the need for more 
 forcible action exists, the shoulders and the base of the scapula are fixed, and then 
 the powerful muscles of forced inspiration come into play; the chief of these are 
 the Trapezius, the Pectoralis minor, the Serratus posticus superior and inferior, 
 and the Rhomboidei. The lower fibres of the Serratus magnus may possibly assist 
 slightly in dilating the chest by raising and everting the ribs. The Sterno-mastoid 
 also, when the head is fixed, assists in forced inspiration by drawing up the sternum 
 and by fixing the clavicle, and thus affording a fixed point for the action of the 
 muscles of the chest. The Ilio-costalis and Quadratus lumborum assist in forced 
 inspiration by fixing the last rib. 
 
 The ordinary action of expiration is hardly effected by muscular force, but 
 results from a return of the walls of the thorax to a condition of rest, owing to 
 their own elasticity and to that of the lungs. Forced expiratory actions are per- 
 formed mainly by the flat muscles (Obliqui and Transversalis) of the abdomen^ 
 assisted by the Rectus. Other muscles of forced expiration are the Internal 
 intercostals and Triangularis sterni (as above mentioned).^ 
 
 III. MUSCLES OF THE ABDOMEN. 
 
 The muscles of the abdomen may be divided into two groups: 1. The super- 
 ficial muscles of the abdomen. 2. The deep muscles of the abdomen. 
 
 1. The Superficial Muscles of the Abdomen. 
 
 The Muscles in this region are, the 
 
 External Oblique. Transversalis. 
 
 Internal Obhque. Rectus. 
 
 Pyramidalis. 
 
 Dissection (Fig. 288). — To dissect the abdominal muscles, make a vertical incision from the 
 ensiform cartilage to the symphysis pubis; a second incision from the umbilicus obliquely upward 
 and outward to the outer surface of the chest, as high as the lower border of the fifth or sixth 
 rib; and a third, commencing midway between the umbilicus and pubes, transversely outward 
 to the anterior superior iliac spine, and along the crest of the ilium as far as its posterior third. 
 Then reflect the three flaps included between these incisions from within outward, in the lines 
 of direction of the muscular fibres. If necessary, the abdominal muscles may be made tense 
 by inflating the peritoneal cavity through the umbilicus. 
 
 > A. M. Patterson (article on Myology, in D. J. Cunningham's Text-book of Anatomy) states that the move- 
 ment of expiration is performed by the elasticity of the lungs, the weight of the chest-wall, the elevation of 
 the Diaphragm, the action of the Triangularis sterni and muscles of the abdominal wall, possiblv aided by the 
 interosseous fibres of the Internal intercostal muscles. The same author states that the movement of inspira- 
 tion IS performed ordinarily by the descent of the Diaphragm and the action of this muscle in elevating the 
 ribs, the action of the External intercostals and Levatores costarum, probably the action of the whole of each 
 Iriternal intercostal, of the Scaleni, and of the Serrati postici. The accessory muscles of respiration are employed 
 when voluntary respiratory effort is necessary. Patterson names them as follows: The Quadratus lumborum, 
 Pectorales, Serratus magnus, Sterno-mastoid, Latissimus dorsi, Infra-hyoid muscles, Extensors of the spine. 
 
OF THE ABDOMEN 
 
 433 
 
 Superficial Fascia. — The superficial fascia of the abdomen consists, over the 
 greater part of the abdominal wall, of a single layer of fascia, which contains a 
 variable amount of fat; but as this layer approaches the groin it is easily divisible 
 into two layers, between which are found the superficial vessels and nerves and 
 the superficial inguinal lymphatic glands. The superficial layer of the superficial 
 fascia, or the fascia of Camper, is thick, areolar in texture, containing adipose tissue 
 in its meshes, the quantity of which varies in different subjects. Below it passes 
 over Poupart's ligament, and is continuous with the outer layer of the superficial 
 fascia of the thigh. In the male this fascia is continued over the penis and outer sur- 
 face of the cord to the scrotum, where it helps to 
 form the dartos. As it passes to the scrotum it 
 changes its character, becoming thin, destitute of 
 adipose tissue, and of a pale hue, it has a reddish 
 color, and in the scrotum it acquires some invol- 
 untary muscular fibres. From the scrotum it may 
 be traced backward to be continuous with the 
 superficial fascia of the perinseum. In the female 
 this fascia is continued into the labia majora. 
 The deep layer of the superficial fascia or the fascia 
 of Scarpa, is thinner and more membranous in 
 character than the superficial layer. In the mid- 
 dle line it is intimately adherent to the linea alba g Dig. 
 and to the symphysis pubis, and is prolonged on section of 
 to the dorsum of the penis, forming the suspen- ^hernia. 
 sory ligament of the penis; above, it joins the 
 superficial layer and is continuous with the 
 superficial fascia over the rest of the trunk; 
 below, it blends with the fascia lata of the 
 thigh a little below Poupart's ligament; and 
 below and internally it is continued over the 
 penis and spermatic cord to the scrotum, where 
 it helps to form the dartos. From the scrotum 
 it may be traced backward to be continuous with the deep layer of the super- 
 ficial fascia of the perinseum. In the female it is continued into the labia 
 majora. 
 
 Deep Fascia. — The deep fascia invests the external oblique muscle, but is so 
 thin over the aponeurosis of the muscle as to be scarcely recognizable. 
 
 The External or Descending Oblique Muscle (m. obliquus extemus abdominis) 
 (Fig. 289) is situated on the side and forepart of the abdomen; being the largest 
 and the most superficial of the three flat muscles in this region. It is broad, thin, 
 and irregularly quadrilateral, its muscular portion occupying the side, its aponeu- 
 rosis the anterior wall, of the abdomen. It arises, by eight fleshy digitations, 
 from the external surface and lower borders of the eight inferior ribs; these 
 digitations are arranged in an oblique line running downward and backward; 
 the upper ones being attached close to the cartilages of the corresponding ribs; 
 the lowest, to the apex of the cartilage of the last rib; the intermediate ones, to 
 the ribs at some distance from their cartilages. The five superior serrations 
 increase in size from above downward, and are received between corresponding 
 processes of the Serratus magnus; the three lower ones diminish in size from 
 above downward, receiving between them corresponding processes from the Latis- 
 simus dorsi. From these attachments, the fleshy fibres proceed in various direc- 
 tions. Those from the lowest ribs pass nearly vertically downward, to be inserted 
 into the anterior half of the outer lip of the crest of the ilium ; the middle and 
 upper fibres, directed downward and forward, terminate in an aponeurosis, oppo- 
 
 28 
 
 Fig. 288. — Dissection of abdomen. 
 
434 
 
 THE MUSCLES AND FASCIAE 
 
 site a line drawn from the prominence of the ninth costal cartilage to the anterior 
 superior spinous process of the ilium. 
 
 Aponeurosis of External Oblique. — The aponeurosis of the external oblique is a 
 thin, but strong membranous aponeurosis, the fibres of which are directed 
 obliquely downward and inward. It is joined with that of the opposite muscle 
 along the median line, covers the whole of the front of the abdomen; above, it is 
 connected with the lower border of the Pectoralis major; below, its fibres are closely 
 
 External abdo- 
 minal ring. 
 GimbernaVs 
 ligament. 
 
 \Pubes. 
 Fig. 289. — The External oblique muscle. 
 
 aggregated together, and extend obliquely across from the anterior superior spine 
 of the ilium to the spine of the os pubis and the linea ilio-pectinea. In the median 
 line it interlaces with the aponeurosis of the opposite muscle, forming the linea 
 alba, which extends from the ensiform cartilage to the symphysis pubis. 
 
 That portion of the aponeurosis which extends between the anterior superior 
 spine of the ilium and the spine of the os pubis is a broad band, folded inward, 
 and continuous below with the fascia lata; it is called Poupart's ligament or the 
 
OF THE ABDOMEN 
 
 435 
 
 ligament of Fallopius. The portion which is reflected from Poupart's ligament 
 at the spine of the os pubis along the pectineal line is called Gimbemat's ligament. 
 From the point of attachment of the latter to the pectineal line, a few fibres 
 pass upward and inward, behind the inner pillar of the ring, to the linea alba. 
 They diverge as they ascend, and form a thin, triangular, fibrous layer, which is 
 called the triangular fascia of the abdomen or Oolles's ligament {ligamentum 
 inguinale reflexum). The point of the triangle is at the origin of Colles's ligament; 
 the base is at the linea alba. Colles's ligament is in front of the conjoined tendon, 
 the Rectus muscle, and the Pyramidalis muscle. 
 
 In the aponeurosis of the External oblique, immediately above the crest of the 
 OS pubis, is a triangular opening, the external abdominal ring, formed by a separa- 
 tion of the fibres of the aponeurosis in this situation. 
 
 POUPART'S 
 LIGAMENT 
 
 INTERCOLUMNAR 
 FIBRES 
 
 GIMBERNAT'S 
 LIGAMENT 
 
 SAPHENOUS 
 OPENING 
 
 LONG 
 
 SAPHENOUS 
 
 VEIN 
 
 EXTERNAL 
 ■ABDOMINAL 
 RING 
 
 CRU3 
 SUPERIOR 
 
 Fig. 290.— Right external abdominal ring and saphenous opening in the male. (Spalteholz.) 
 
 Relations.— By its external surface, with the superficial fascia, superficial epi- 
 gastric and circumflex iliac vessels, and some cutaneous nerves; by its internal 
 surface, with the Internal oblique, the lower part of the eight inferior ribs, and 
 Intercostal muscles, the Cremaster, the spermatic cord in the male, and round liga- 
 ment in the female. Its posterior border, extending from the last rib to the crest 
 of the ilium, is fleshy throughout and free; it is occasionally overlapped by the 
 Latissimus dorsi, though generally a triangular interval exists between the two 
 muscles near the crest of the ilium, in which is seen a portion of the internal 
 oblique. This triangle, Petit's triangle (trigonum lumhale), is therefore bounded 
 in front by the External oblique, behind by the Latissimus dorsi, below by the 
 crest of the ilium, while its floor is formed by the Internal oblique (Fig. 289). 
 
 The following parts of the aponeurosis of the External oblique muscle require 
 to be further described — viz., the external abdominal ring, the intercolumnar fibres 
 and fascia, Poupart's ligament, Gimbemat's ligament, and the triangular fascia of 
 the abdomen. 
 
436 THE MUSCLES AND FASCIA 
 
 The External Abdominal Ring {annulus inguinalis subcutaneous) (Fig. 290). — 
 Just above and to the outer side of the crest of the os pubis an interval is seen in the 
 aponeurosis of the External oblique, called the external abdominal ring. The aper- 
 ture is oblique in direction, somewhat triangular in form, and corresponds with 
 the course of the fibres of the aponeurosis. It usually measures from base to apex 
 about an inch, and transversely about half an inch. It is bounded below by the 
 crest of the os pubis; above, by a series of curved fibres, the external spermatic, or 
 the intercolumnar fibres (fibrce intercrurales) , which pass across the upper angle of 
 the ring, so as to increase its strength; and on each side, by the margins of the 
 opening in the aponeurosis, which are called the columns or pillars of the ring. 
 
 The External Pillar or inferior cms (crus inferius) is inferior from the obliquity 
 of its direction. It is stronger than the internal pillar; it is formed by that 
 portion of Poupart's ligament which is inserted into the spine of the os pubis; it is 
 curved so as to form a kind of groove, upon which the spermatic cord rests. 
 
 The Internal Pillar or superior crus (crus swperius) is a broad, thin, flat band, 
 which is attached to the front of the symphysis pubis, interlacing with its fellow 
 of the opposite side. 
 
 The external abdominal ring gives passage to the spermatic cord in the male 
 {funiculus spermaticus) and round ligament in the female (ligamentum teres uteri) : 
 it is much larger in men than in women, on account of the large size of the sper- 
 matic cord, and hence the greater frequency of inguinal hernia in men. 
 
 Intercolumnar Fibres {jihrcs intercrurales) (Fig. 290). — The intercolumnar fibres 
 are a series of curved tendinous fibres, which arch across the lower part of 
 the aponeurosis of the External oblique. They have received their name from 
 stretching across between the two pillars of the external ring, describing a curve 
 with the convexity downward. They are much thicker and stronger at the outer 
 margin of the external ring, where they are connected to the outer third of Pou- 
 part's ligament, than internally, where they are inserted into the linea alba. They 
 are more strongly developed in the male than in the female. The inter- 
 columnar fibres increase the strength of the lower part of the aponeurosis, 
 and prevent the divergence of the pillars from one another. 
 
 These intercolumnar fibres as they pass across the external abdominal ring 
 are themselves connected together by delicate fibrous tissue, thus forming a fascia, 
 which as it is attached to the pillars of the ring covers it in, and is called the 
 intercolumnar fascia or the external spermatic fascia. This intercolumnar fascia 
 is continued down as a tubular prolongation around the outer surface of the 
 cord and testis or of the round ligament, and encloses them in a distinct sheath. 
 
 The sac of an inguinal hernia, in passing through the external abdominal ring, receives an 
 investment from the intercolumnar fascia. 
 
 If the finger is introduced a short distance into the external abdominal ring 
 and the limb is then extended and rotated outward, the aponeurosis of the External 
 oblique, together with the iliac portion of the fascia lata, will be felt to become 
 tense, and the external ring much contracted; if the limb is, on the contrary, flexed 
 upon the pelvis and rotated inward, this aponeurosis will become lax and the 
 external abdominal ring sufficiently enlarged to admit the finger with compara- 
 tive ease; hence the patient should always be put in the latter position when the 
 taxis is applied for the reduction of an inguinal hernia in order that the abdominal 
 walls may be relaxed as much as possible. 
 
 Poupart's Ligament (ligamentum inguinale). — The portion of Poupart's ligament 
 in front of the crural ring is called the superficial crural arch. Poupart's ligament 
 is the lower border of the aponeurosis of the External oblique muscle, and extends 
 from the anterior superior spine of the ilium to the pubic spine. From this 
 latter point it is reflected outward to be attached to the pectineal line for about 
 
OF THE ABDOMEN 437 
 
 half an inch, forming Gimbemat's ligament. Its general direction is curved down- 
 ward toward the thigh, where it is continuous with the fascia lata. Its outer half 
 is rounded and oblique in direction. Its inner half gradually widens at its attach- 
 ment to the OS pubis, is more horizontal in direction, and lies beneath the spermatic 
 cord. Nearly the whole of the space included between the crural arch and the 
 innominate bone is filled in by the parts which descend from the abdomen into 
 the thigh (Fig. 298). These will be referred to again on a subsequent page. 
 
 Gimbemat's Ligament (ligamentum lacunare) (Figs. 290 and 298). — Gimbernat's 
 ligament is that part of the aponeurosis of the External oblique muscle which is 
 reflected upward and outward from the spine of the os pubis to be inserted into the 
 pectineal line. It is about half an inch in length, larger in the male than in the 
 female, almost horizontal in direction in the erect posture, and of a triangular form 
 with the base directed outward. Its base, or outer margin, is concave, thin, and 
 sharp, and lies in contact with the crural sheath, forming the inner boundary of 
 the femoral or crural ring (antiulus femoralis) . Its apex corresponds to the spine 
 of the OS pubis. Its posterior margin is attached to the pectineal line, and is con- 
 tinuous with the pubic portion of the fascia lata. Its anterior margin is continuous 
 with Poupart's ligament. Its surfaces are directed upward and downward. 
 
 Triangular Fascia or CoUes's Ligament (ligamentum inguinal reflexum). — The 
 triangular fascia of the abdomen is a layer of tendinous fibres of a triangular 
 shape, which is attached by its apex to the pectineal line, where it is continuous 
 with Gimbernat's ligament. It passes inward beneath the spermatic cord, and 
 expands into a somewhat fan-shaped fascia, lying behind the inner pillar of the 
 external abdominal ring, and in front of the conjoined tendon, and interlaces with 
 the ligament of the other side at the linea alba. 
 
 Ligament of Cooper (Fig. 298). — This is a strong ligamentous band, which was 
 first described by Sir Astley Cooper. It extends upward and backward from the 
 base of Gimbernat's ligament along the ilio-pectineal line, to which it is attached. 
 It is strengthened by the fascia transversalis, by the pectineal aponeurosis, and 
 by a lateral expansion from the lower attachment of the linea alba (adminicidum 
 lineoe alhoe). 
 
 Suspensory Ligament of the Penis {ligamentum fundiforme penis). — The suspen- 
 sory ligament of the penis arises from the linea alba, the anterior portion of 
 the sheath of the Rectus muscle, and the superficial fascia. It splits into two 
 portions, blends with the inserting fascia of the penis, and passes into the scrotum. 
 
 Suspensory Ligament of the Clitoris (ligamentum fundiforme clitoridis). — The 
 suspensory ligament of the clitoris corresponds in the female to the suspen- 
 sory ligament of the penis in the male. 
 
 Dissection — Detach the External oblique by dividing it across, just in front of its attach- 
 ment to the ribs, as far as its posterior border, and separate it below from the crest of the ihum 
 as far as the anterior superior spine; then separate the muscle carefully from the Internal oblique, 
 which lies beneath, and turn it toward the opposite side. 
 
 The Internal or Ascending Oblique Muscle (m. obliquus intemus abdominis) 
 (Fig. 291), thinner and smaller than the preceding, beneath which it lies, is of 
 an irregularly quadrilateral form, and is situated at the side and forepart of the 
 abdomen. It arises, by fleshy fibres, from the outer half of Poupart's ligament, 
 being attached to the groove on its upper surface; from the anterior two-thirds 
 of the middle lip of the crest of the ilium, and from the posterior lamella of the 
 lumbar fascia (Fig. 295). From this origin the fibres diverge: those from Poupart's 
 ligament, few in number and paler in color than the rest, arch downward and 
 inward across the spermatic cord in the male and the round ligament in the 
 female, and, becoming tendinous, are inserted, conjointly with those of the Trans- 
 versalis, into the crest of the os pubis and pectineal line, to the extent of half an inch 
 or more, forming what is known as the conjoined tendon of the Internal oblique and 
 
438 
 
 THE MUSCLES AND FASCIA 
 
 Transversalis ; those from the anterior tliird of the ihac origin are horizontal in 
 their direction, and, becoming tendinous along the lower fourth of the linea 
 semilunaris, pass in front of the Rectus muscle to be inserted into the linea alba; 
 those which arise from the middle third of the origin from the crest of the 
 ilium pass obliquely upward and inward, and terminate in an aponeurosis wdiich 
 divides at the outer border of the Rectus muscle into two lamellae (Fig. 296), 
 which are continued forward, in front and behind this muscle, to the linea alba, 
 the posterior lamella being also connected to the cartilages of the seventh, eighth, 
 and ninth ribs; the most posterior fibres pass almost vertically upward, to be 
 inserted into the lower borders of the cartilages of the three lower ribs, being con- 
 tinuous with the Internal intercostal muscles. 
 
 Conjoined tendon.-jj 
 
 CREMASTER 
 
 Puhes. 
 
 Fig. 291. — The Internal oblique muscle. 
 
 The conjoined tendon of the Inte.nal obhque and Transversalis is inserted into 
 the crest of the os pubis and pectineal line, immediately behind the external 
 abdominal ring, serving to protect what would otherwise be a weak point in the 
 abdominal wall. Sometimes this tendon is insufficient to resist the pressure from 
 within, and is carried forward in front of a protrusion through the external ring, 
 forming one of the coverings of direct inguinal hernia ; or the hernia forces its way 
 through the fibres of the conjoined tendon. The conjoined tendon is sometimes 
 divided into an outer and an inner portion — the former being termed the liga- 
 ment of Hesselbach {ligamentum interjoveolare) ; the latter, the ligament of Henle 
 (Fig. 292). 
 
OF THE ABDOMEN 
 
 439 
 
 Aponeurosis of Internal Oblique. — The aponeurosis of the Internal oblique is 
 continued forward to the middle line of the abdomen, where it joins with the 
 aponeurosis of the opposite muscle at the linea alba, and extends from the margin 
 of the thorax to the os pubis. At the outer margin of the Rectus muscle this 
 aponeurosis, for the upper three-fourths of its extent, divides into two lamellae, 
 which pass, one in front and the other behind the muscle, enclosing it in a kind of 
 sheath, and reuniting on its inner border of the linea alba; the anterior layer is 
 blended with the aponeurosis of the External obli(}ue muscle; the posterior layer 
 with that of the Transversalis. Along the lower fourth the aponeurosis passes 
 altogether in front of the Rectus without any separation. Where the aponeurosis 
 
 SEMILUNAR FOLD 
 OF DOUGLAS 
 
 TRANSVERSALIS 
 
 RECTUS 
 ABDOMINIS 
 
 DEEP EPI- 
 GASTRIC ARTERY 
 AND VEIN 
 
 INTERNAL 
 OBL4QUe 
 
 iiGAMENT OF HENLE LIGAMENT OF HESSELBACH 
 
 Fig. 292. — The deep epigastric artery and veins, ligament of Henle and ligament of Hesselbach, seen 
 from in front. (Modified from Braune.) 
 
 ceases to split, and passes altogether in front of the Rectus muscle, a deficiency is 
 left in the sheath of the muscle behind; this is marked above by a sharp lunated 
 margin having its concavity downward. This is known as the semilunar fold of 
 Douglaft (linea semicircularis) (Fig. 293). 
 
 Relations. — By its external surface, with the External oblique, Latissimus dorsi, 
 spermatic cord, and external ring; by its internal surface, with the Transversalis 
 muscle, the lower intercostal vessels and nerves, the ilio-hypogastric and the ilio- 
 inguinal nerves. Near Poupart's ligament it lies on the fascia transversalis, 
 internal ring, and spermatic cord. Its lower border forms the upper boundary 
 of the inguinal canal. 
 
 The Cremaster muscle (Fig. 291) is a thin, muscular layer, composed of a num- 
 ber of fasciculi which arise from the inner part of Poupart's ligament, where its 
 fibres are continuous with those of the Internal oblique and also occasionally with 
 the Transversalis. It passes along the outer side of the spermatic cord, descends 
 with it through the external abdominal ring upon the front and sides of the cord, 
 and forms a series of loops which differ in thickness and length in different sub- 
 jects. Those at the upper part of the cord are exceedingly short, but they become 
 in succession longer and longer, the longest reaching down as low as the testicle, 
 where a few are inserted into the tunica vaginalis. These loops are united together 
 by areolar tissue, and form a thin covering over the cord and testis, the middle 
 
440 
 
 THE MUSCLES AND FASCIyE 
 
 spermatic fascia (fascia cremasterica). The fibres ascend along the inner side of 
 the cord, and are inserted by a small pointed tendon into the crest of the os 
 pubis and front of the sheath of the Rectus muscle. 
 
 '5 POSTERIOR LEAF 
 
 ^ OF SHEATH OF 
 
 ■' RECTUS ABDOMINIS 
 
 LINEA SEMILUNARIS 
 
 TRANSVERSALI8 
 
 SEMILUNAR FOLD 
 OF DOUGLAS 
 
 RECTUS ABDOMINIS 
 
 (cut through) 
 
 ANTERIOR LEAF 
 
 F SHEATH OF 
 RECTUS ABDOMINIS 
 
 Fig. 293. — The muscles of the abdomen, showing the semilunar fold of Douglas. Viewed from in front. 
 
 (Spalteholz.) 
 
 It will be observed that the origin and insertion of the Cremaster is precisely 
 similar to that of the lower fibres oif the Internal oblique. This fact affords an easy 
 explanation of the manner in which the testicle and cord are invested by this 
 muscle. At an early period of fretal life the testis is placed at the lower and back 
 part of the abdominal cavity, but during its descent toward the scrotum, which 
 takes place before birth, it passes beneath the arched fibres of the Internal oblique. 
 In its passage beneath this muscle some fibres are derived from its lower part 
 which accompany the testicle and cord into the scrotum. It occasionally happens 
 
OF THE ABDOMEN 
 
 441 
 
 that the loops of the Cremaster surround the cord, some lying behind as well as in 
 front. It is probable that under these circumstances the testis, in its descent, 
 passed through instead of beneath the fibres of the Internal oblique. 
 
 In the descent of an ol)lique inguinal hernia, which takes the same course as 
 the spermatic cord, the Cremaster muscle forms one of its coverings. This muscle 
 becomes largely developed in cases of hydrocele and large old scrotal hernia. The 
 Cremaster muscle is found only in the male, but almost constantly in the female 
 
 JAnea alba. 
 
 Fig. 294. — The Transversalis, Rectus, and Pyramidalis muscles. 
 
 a few muscular fibres may be seen on the surface of the round ligament, which 
 correspond to this muscle, and in cases of oblique inguinal hernia in the female a 
 considerable amount of muscular fibre may be found covering the sac. 
 
 Dissection. — Detach the Internal oblique in order to expose the Transversalis beneath. This 
 may be effected by dividing the muscle, above, at its attachment to the ribs; below, at its con- 
 nection with Poupart's ligament and the crest of the ilium; and behind, by a vertical incision 
 
442 THE MUSCLES AND FASCIA 
 
 extending from the last rib to the crest of the ihum. The muscle should previously be made 
 tense by drawing upon it with the fingers of the left hand, and if its division is carefully effected, 
 the cellular interval between it and the Transversalis, as well as the direction of the fibres of the 
 latter muscle, will aft'ord a clear guide to their separation; along the crest of the ilium the cir- 
 cumflex iliac vessels are interposed between them, and form an important guide in separating 
 them. The muscle should then be thrown inward toward the linea alba. 
 
 The Transversalis Muscle {m. transversus abdominis) (Fig. 294), so called 
 from the direction of its fibres, is the most internal flat muscle of the abdomen, 
 being placed immediately beneath the Internal oblique. It arises by fleshy fibres 
 from the outer third of Poupart's ligament; from the inner lip of the crest of the 
 ilium for its anterior three-fourths ; from the inner surface of the cartilages of the 
 six lower ribs, interdigitating with the Diaphragm; and from the lumbar fascia 
 (Fig. 295), which may be regarded as the posterior aponeurosis of the muscle. 
 The muscle terminates in front in a broad aponeurosis, the lower fibres of 
 which curve downward and inward, and are inserted, together with those of the 
 Internal oblique, into the lower part of the linea alba, the crest of the os pubis 
 and pectineal line forming what is known as the conjoined tendon of the Internal 
 oblique and Transversalis. The lowermost fibres help to form the posterior wall 
 of the inguinal canal. Throughout the rest of its extent the aponeurosis passes 
 horizontally inward, and is inserted into the linea alba, its upper three-fourths 
 passing behind the Rectus muscle, blending with the posterior lamella of the 
 Internal oblique; its lower fourth passing in front of the Rectus. The external 
 portion of the lower fibres of the conjoined tendon is known as the ligament of 
 Hesselbach; the internal portion as the ligament of Henle. 
 
 Relations. — By its external surface, with the Internal oblique, the lower inter- 
 costal nerves, and the inner surface of the cartilages of the lower ribs; by its 
 internal surface, with the fascia transversalis, which separates it from the periton- 
 eum. Its lower border forms the upper boundary of the inguinal canal. 
 
 Dissection. — To expose the Rectus muscle, open its sheath by a vertical incision extending 
 from the margin of the thorax to the os pubis, and then reflect the two portions from the surface 
 of the muscle, which is easily done, excepting at the linefe transversse, where so close an adhesion 
 exists that the greatest care is requisite in separating them. Now raise the outer edge of the 
 muscle, in order to examine the posterior layer of the sheath. By dividing the muscle in the 
 centre, and turning its lower part downward, the point where the posterior wall of the sheath 
 terminates in a thin curved margin will be seen. 
 
 The Rectus Abdominis (Figs. 292, 294 and 296) is a long flat muscle, which 
 extends along the whole length of the front of the abdomen, being separated from 
 its fellow of the opposite side by the linea alba. It is much broader, but thinner, 
 above than below, and arises by two tendons, the external or larger being attached 
 to the crest of the os pubis, the internal, smaller portion interlacing with its fellow of 
 the opposite side, and being connected with the ligaments covering the front of the 
 symphysis pubis. The fibres ascend, and the muscle is inserted by three portions of 
 unequal size into the cartilages of the fifth, sixth, and seventh ribs. The upper por- 
 tion, attached principally to the cartilage of the fifth rib, usually has some fibres of 
 insertion into the anterior extremity of the rib itself. Some fibres are occasionally 
 connected with the costo-xiphoid ligaments and side of the ensiform cartilage. 
 
 The Rectus muscle is traversed by tendinous intersections, three in number, 
 which have received the name of lineae transversae. One of these is usually 
 situated opposite the umbilicus, and two above that point; of the latter, one 
 corresponds to the extremity of the ensiform cartilage, and the other to the inter- 
 val between the ensiform cartilage and the umbilicus. These intersections pass 
 transversely or obliquely across the muscle in a zigzag course; they rarely extend 
 completely through its substance, sometimes they pass only half-way across it, and 
 are intimately adherent in front to the sheath in which the muscle is enclosed. 
 
OF THE ABDOMEN 
 
 443 
 
 Sometimes one or two additional lines may be seen, one usually below the 
 umbilicus; the position of the other, when it exists, is variable. These addi- 
 tional lines are for the most part incomplete. 
 
 Fig. 295. — A transverse section of the abdomen in the lumbar region. 
 
 The Rectus is enclosed in a sheath, the rectus sheath {vagina m. recti abdominis) 
 (Figs. 295 and 296), formed by the aponeurosis of the Oblique and Trans versalis 
 
 SHEATH OF 
 RECTUS ABDOMINIS 
 
 (anterior leaf) 
 
 Posterior leaf Anterior leaf 
 
 SHEATH OF RECTUS ABDOMINIS 
 
 Fig. 296. — Transition of the tendon of the right internal oblique into the sheath of the rectus. (Spalteholz.) 
 
 muscles, which are arranged in the following manner. When the aponeurosis of the 
 Internal oblique arrives at the outer margin of the Rectus it divides into two lamellae. 
 
444 THE MUSCLES AND FASCIA 
 
 one of which passes in front of the Rectus, blending with the aponeurosis of the 
 External oblique; the other, behind it, blending with the aponeurosis of the Trans- 
 versalis; and these, joining again at its inner border, are inserted into the linea alba. 
 This arrangement of the aponeuroses exists along the upper three-fourths of the 
 muscle: at the commencement of the lower fourth, the posterior wall of the sheath 
 terminates in a thin curved margin, the semilunar fold of Douglas {linea semicir- 
 cularis) (Fig. 293), the concavity of which looks downward toward the pubes; the 
 aponeuroses of all three muscles passing in front of the Rectus without any sepa- 
 ration. A very thin aponeurotic layer does pass behind the- lower one-fourth of 
 the muscle, but it is trivial as compared with the thickness of the layer behind the 
 upper three-fourths of the muscle. This sudden thinning causes the semilunar 
 fold of Douglas. The extremities of the fold of Douglas descend as pillars to the 
 OS pubis. The inner pillar is attached to the symphysis pubis; the outer pillar 
 passes downward as a distinct band on the inner side of the internal abdominal 
 ring to join with the outer fibres of the conjoined tendon, and assist to form 
 the ligament of Hesselbach. There its fibres divide into two sets, internal 
 and external; the internal fibres are attached to the ascending ramus of the os 
 pubis and the pectineal fascia; the external ones pass to the Psoas fascia, to 
 the deep surface of Poupart's ligament, and to the tendon of the Transversalis on 
 the outer side of the ring. The Rectus muscle, in the situation where its sheath 
 is deficient, is separated from the peritoneum by the transversalis fascia. The 
 convex outer border of the Rectus muscle corresponds to the linea semilunaris. 
 
 The P3n:amidalis is a small muscle, triangular in shape, placed at the lower 
 part of the abdomen, in front of the Rectus, and contained in the same sheath 
 with that muscle. It arises by tendinous fibres from the front of the os pubis 
 and the anterior pubic ligament; the fleshy portion of the muscle passes upward, 
 diminishing in size as it ascends, and terminates by a pointed extremity, which is 
 inserted into the linea alba, midway between the umbilicus and the os pubis. This 
 muscle is sometimes found wanting on one or both sides; the lower end of the 
 Rectus then becomes proportionately increased in size. Occasionally it has been 
 found double on one side, or the muscles of the two sides are of unequal size. 
 Sometimes its length exceeds what is stated above. 
 
 Besides the Rectus and Pyramidalis muscles, the sheath of the Rectus contains 
 the superior and deep epigastric arteries, the terminations of the lumbar arteries 
 and of the lower intercostal arteries and nerves. 
 
 Nerves. — The abdominal muscles are supplied by the lower intercostal nerves. 
 The Transversalis and Internal oblique also receive filaments from the hypogastric 
 branch of the ilio-hypogastric and sometimes from the ilio-inguinal. The Cremas- 
 ter is supplied by the genital branch of the Genito-crural. 
 
 In the description of the abdominal muscles mention has frequently been made 
 of the linea alba, lineae semilunares, and linese transversae; when the dissection of 
 the muscles is completed these structures should be examined. 
 
 The Linea Alba (Figs. 293 and 296). — The linea alba is a tendinous raph^ seen 
 along the middle line of the abdomen, extending from the ensiform cartilage to the 
 symphysis pubis, to which it is attached. It is placed between the inner borders of 
 the Recti muscles, and is formed by the blending of the aponeuroses of the Obliqui 
 and Transversales muscles. It is narrow below, corresponding to the narrow inter- 
 val existing betwee^ the Recti ; but broader above, as these muscles diverge from one 
 another in their ascent, becoming of considerable breadth when there is great dis- 
 tention of the abdomen from pregnancy or ascites. It presents numerous apertures 
 for the passage of vessels and nerves : the largest of these is the umbilicus (Fig. 297). 
 The umbilicus is a fibrous ring formed by the fibres of the aponeurosis of the linea 
 alba, is filled with scar tissue; in the foetus transmits the umbilical vein, the two 
 hypogastric arteries, the allantoic duct, and the vitello-intestinal duct; but in the 
 
OF THE ABDOMEN 
 
 445 
 
 UMBILICAL 
 VEIN 
 
 LINEA ALBA 
 
 INTERVASCULAR 
 
 HYPOGASTRIC 
 ARTERY 
 
 Fig. 297.— The umbilicus of the fcetus 
 seen from within the abdomen. (Poirier 
 and Charpy.) 
 
 adult is obliterated, the cicatrix being stronger than the neighboring parts; hence 
 umbilical hernia occurs in the adult near the umbilicus, whilst in the foetus it occurs 
 at the umbilicus. The remains of the foetal structures are cord-like in character, 
 and they diverge from the umbilicus within the 
 abdomen. The remains of the umbilical vein con- 
 stitute the round ligament of the liver, and this 
 cord passes upward (Pig. 297). The remains of 
 the hypogastric arteries pass downward (Pig. 297). 
 The remains of the allantois become the urachus, 
 which passes to the summit of the bladder (Fig. 
 297). The depression of the umbilicus was 
 created by the urachus. The linea alba is in re- 
 lation, in ^ront, with the integument, to which it 
 is adherent, especially at the umbilicus; behind, 
 it is separated from the peritoneum by the trans- 
 versalis fascia; and below, by the urachus, and 
 the bladder when that organ is distended. 
 
 The Lineae Semilunares (Fig. 289). — The linese 
 semilunares are two curved tendinous lines placed 
 one on each side of the linea alba. Each corre- 
 sponds with the outer border of the Rectus mus- 
 cle, extends from the cartilage of the ninth rib 
 to the pubic spine, and is formed by the aponeu- 
 rosis of the Internal oblique at its point of division to enclose the Rectus, where 
 it is reinforced in front by the External oblique and behind by the Transversalis. 
 
 The Lineae Transversse (inscriptiones tendinew) (Fig. 289). — The line.T trans- 
 versje are narrow transverse lines which intersect the Recti muscles, as already 
 mentioned; they connect the lineae semilunares with the linea alba. 
 
 Actions. — The abdominal muscles perform a threefold action: 
 
 When the pelvis and thorax are fixed, they compress the abdominal, viscera, by 
 constricting the cavity of the abdomen, in which action they are materially assisted 
 by the descent of the Diaphragm. By these means the foetus is expelled from the 
 uterus, the faeces from the rectum, the urine from the bladder, and the contents of 
 the stomach in vomiting. 
 
 If the pelvis and spine are fixed, these muscles compress the lower part of the 
 thorax, materially assisting expiration. If the pelvis alone is fixed, the thorax is 
 bent directly forward when the muscles of both sides act, or to either side when 
 those of the two sides act alternately, rotation of the trunk at the same time taking 
 place to the opposite side. 
 
 If the thorax is fixed, these muscles, acting together, draw the pelvis upward, 
 as in climbing; or, acting singly, they draw the pelvis upward, and bend the 
 vertebral column to one side or the other. The Recti muscles, acting from below, 
 depress the thorax, and consequently flex the vertebral column; when acting from 
 above, they flex the pelvis upon the vertebral column. The Pyramidalis are 
 tensors of the linea alba. 
 
 The Transversalis Fascia (fascia transversalis). — The fascia transversalis is a 
 thin aponeurotic membrane which lies between the inner surface of the Transversalis 
 muscle and the extra-peritoneal fat. It forms part of the general layer of fascia 
 which lines the interior of the abdominal and pelvis cavities, and is directly continu- 
 ous with the iliac and pelvic fasciae. In the inguinal region the transversalis fascia is 
 thick and dense in structure, and joined by fibres from the aponeurosis of the Trans- 
 versalis muscle, but it becomes thin and cellular as it ascends to the Diaphragm, 
 and blends with the fascia covering this muscle. In front, it unites across the 
 middle line with the fascia on the opposite side of the body, and behind it becomes 
 
446 
 
 THE MUSCLES AND FASCIA 
 
 lost in the fat which covers the posterior surfaces of the kidneys. Below, it has 
 the folloAving attachments: posteriorly, it is connected to the whole length of the 
 crest of the ilium, between the attachments of the Transversalis and Iliacus 
 muscles; between the anterior superior spine of the ilium and the femoral vessels 
 it is connected to the posterior margin of Poupart's ligament, and is there con- 
 tinuous with the iliac fascia. Internal to the femoral vessels it is thin and attached 
 to the OS pubis and pectineal line, behind the conjoined tendon, with which it is 
 united; and, corresponding to the point where the femoral vessels pass into the 
 thigh, this fascia descends in front of them, forming the anterior wall of the crural 
 sheath. Beneath Poupart's ligament it is strengthened by a band of fibrous tissue, 
 which is only loosely connected to Poupart's ligament, and is specialized as the 
 deep crural arch. The spermatic cord in the male and the round ligament in the 
 female pass through this fascia; the point where they pass through is called the 
 internal abdominal ring. This opening is not visible externally, owing to a pro- 
 longation of the transversalis fascia on these structures, forming the infundibuliform 
 fascia. 
 
 The internal or deep abdominal ring {annulus inguinalis abdominis) (Figs. 292 
 and 298) is situated in the transversalis fascia, midway between the anterior 
 
 TRANSVERSALIS 
 FASCIA 
 
 INTERNAL 
 
 ABDOMINAL 
 
 RING 
 
 CRURAL NERVE 
 
 FEMORAL ARTERY. 
 
 ILIAC FASCIA 
 
 GIMBERNAT'S 
 LIGAMENT 
 
 COOPER'S 
 LIGAMENT 
 
 Fig. 298.— The relation of the femoral and internal abdominal rings, seen from within the abdomen after 
 removal of the peritoneum. (Poirier and Charpy.) 
 
 superior spine of the ilium and the symphysis pubis, and about half an inch above 
 Poupart's ligament. It is of an oval form, the extremities of the oval directed 
 upward and downward, varies in size in different subjects, and is much larger in 
 the male than in the female. Its lower border is strengthened by the collection of 
 fibres called Hesselbach's ligament, lying directly in front of the deep epigastric 
 artery. It is the outer portion of the conjoined tendon fused with the outer 
 pillar of the semilunar fold of Douglas. The internal ring is bounded, above 
 and externally, by the arched fibres of the Transversalis; below and internally, 
 by the deep epigastric vessels. It transmits the spermatic cord in the male 
 and the round ligament in the female. From its circumference a thin funnel- 
 shaped membrane, the infmidibuliform or internal spermatic fascia, is continued 
 round the cord and testis, enclosing them in a distinct pouch. 
 
OF THE ABDOMEN 
 
 447 
 
 , EXTERNAL OBLIQUE 
 
 (reflected downward) 
 
 EXTERNAL.OBLIQUE 
 
 (reflected inward; 
 
 POSTERIOR WALL OF 
 
 INGUINAL CANAL 
 
 INTERNAL ORIGIN 
 OF CRENASTER 
 
 Fig. 299. — The right inguinal canal in the male, second layer, viewed from in front. (The first layer 
 is shown in Fig. 290.) (Spalteholz.) 
 
 INTERNAL OBLIQUE 
 
 (reflected inward) 
 
 INTERNAL 
 OBLIQUE 
 
 EXTERNAL OBLIQUE 
 
 (reflected inward) 
 
 Fio. 300. — The right inguinal canal in the male, third layer, viewed from in front. (Spalteholz.) 
 
448 THE 3IUSCLES AND FASCIA 
 
 When the sac of an oblique inguinal hernia passes through the internal or deep abdominal 
 ring, the infundibuliform process of the transversalis fascia forms one of its coverings. 
 
 The Inguinal or Spermatic Canal (canalis ingumaUs) (Figs. 299 and 300). — The 
 ino-uinal or spermatic canal contains the spermatic cord {funiculus spermaticus) in 
 the male and the round ligament {ligamentum teres uteri) in the female. It is an 
 oblique canal about an inch and a half in length, directed downward and inward, 
 and placed parallel to and a little above Poupart's ligament. It commences above 
 at the internal or deep abdominal ring, which is the point where the cord enters 
 the spermatic canal, and terminates below at the external ring. It is bounded 
 in front by the integument and superficial fascia, by the aponeurosis of the 
 External oblique throughout its whole length, and by the Internal oblique for 
 its outer third; behind, by the triangular fascia, the conjoined tendon of the 
 Internal obHque and Transversalis, transversalis fascia, and the subperitoneal 
 fat and peritoneum ; above, by the arched fibres of the Internal oblique and Trans- 
 versalis; below, by Gimbernat's ligament, and by the union of the fascia trans- 
 versalis with Poupart's ligament. The median aspect of the floor of the canal is 
 strengthened by dense fibres which are attached to the pubis and to the Rectus 
 muscle. These fibres constitute the falx inguinalis. The deep epigastric artery 
 passes upward and inward behind the canal lying close to the inner side of the 
 internal abdominal ring (Fig. 292). The interval between this artery and the 
 outer edge of the Rectus is named Hesselbach's triangle, the base of which is 
 formed by Poupart's ligament. 
 
 That form of protrusion in which the intestine follows the course of the spermatic cord along 
 ihe spermatic canal is called oblique inguinal hernia. 
 
 The Deep Crural Arch. — Curving over the vessels, just at the point where they 
 become femoral, on the abdominal side of Poupart's ligament and loosely con- 
 nected with it, is a thickened band of fibres called the deep crural arch. It is 
 apparently a thickening of the fascia transversalis, joining externally to the centre 
 of Poupart's ligament, and arching across the front of the crural sheath to be 
 inserted by a broad attachment into the spine of the os pubis and ilio-pectineal 
 line, behind the conjoined tendon. In some subjects this structure is not very 
 prominently marked, and not infrequently it is altogether wanting. 
 
 Cooper's Ligament or the Reflected Tendon of Cooper (Fig. 298) is a small reflection 
 from the tendon of the Transversalis which passes downward and outward behind 
 Gimbernat's ligament. 
 
 Surface Form. — The only two muscles of this group which have any considerable influ- 
 ence on surface form are the External oblique and Rectus muscles of the abdomen. With 
 regard to the External oblique, the upper digitations of its origin from the ribs are well marked, 
 intermingled with the serrations of the Serratus magnus; the lower digitations are not visible, 
 being covered by the thick border of the Latissimus dorsi. Its attachment to the crest of the 
 ilium, in conjunction with the Internal oblique, forms a thick oblique roll, which determines the 
 iliac furrow. Sometimes on the front of the lateral region of the abdomen an undulating out- 
 line marks the spot where the muscular fibres terminate and the aponeurosis commences. The 
 outer border of the Rectus is defined by the tinea sryailunaris, which may be exactly defined by 
 putting the muscle into action. It corresponds with a curved line, with its convexity outward, 
 drawn from the end of the cartilage of the ninth rib to the spine of the os pubis, so that the 
 centre of the line, at or near the umbilicus, is three inches from the median line. The inner 
 border of the Rectus corresponds to the tinea alba, marked on the surface of the body by a 
 groove, the abdominal furrow, which extends from the infrasternal fossa to, or to a little below, 
 the umbilicus, where it gradually becomes lost. The surface of the Rectus presents three trans- 
 verse furrows, the luiese transversse. The upper two of these, one opposite or a little below the 
 tip of the ensiform cartilage, and another, midway between this point and the umbilicus, are 
 usually well marked; the third, opposite the umbilicus, is not so distinct. The umbilicus, situ- 
 ated in the linea alba, varies very much in position as regards its level. It is always situated 
 above a zone drawn round the body opposite the highest point of the crest of the ilium, gen- 
 erally being about three-quarters of an inch to an inch above this line. It usually corresponds, 
 therefore, to the fibro-cartilage between the third and fourth lumbar vertebrae. 
 
OF THE 18CHI0- RECTAL REGION 449 
 
 2. The Deep Muscles of the Abdomen. 
 
 Psoas magnus, Iliacus. 
 
 Psoas parvus. Quadratus lumborum. 
 
 The Psoas magnus, the Psoas parvus, and the IHacus muscles, with the fascia 
 covering them, will be described with the Muscles of the Lower Extremity. 
 
 The Fascia Covering the Quadratus Lumborum (Fig. 295).— This is the most 
 anterior of the three layers of the lumbar fascia. It is a thin layer of fascia, which, 
 passing over the anterior surface of the Quadratus lumborum, is attached, inter- 
 nally, to the bases of the transverse processes of the lumbar vertebrae; below, to 
 the ilio-lumbar ligament ; and above, to the apex and lower border of the last rib. 
 
 The portion of this fascia which extends from the transverse process of the 
 first lumbar vertebra to the apex and lower border of the last rib constitutes the 
 ligamentum arcuatum externum. 
 
 The Quadratus Lumborum (Fig. 283) is situated in the lumbar region. It is 
 irregularly quadrilateral in shape, and broader below than above. It arises by 
 aponeurotic fibres from the ilio-lumbar ligament and the adjacent portion of the 
 crest of the ilium for about two inches, and is inserted into the lower border of 
 the last rib for about half its length, and by four small tendons, into the apices 
 of the transverse processes of the four upper lumbar vertebrae. Occasionally a 
 second portion of this muscle is found situated in front of the preceding. This 
 arises from the upper borders of the transverse processes of three or four of the 
 lower lumbar vertebrae, and is inserted into the lower margin of the last rib. The 
 Quadratus lumborum is contained in a sheath formed by the anterior and middle 
 lamellae of the lumbar fasciae. 
 
 Relations. — Its anterior surface (or rather the fascia which covers its anterior 
 surface) is in relation with the colon, the kidney, the Psoas muscle, and the 
 Diaphragm. Between the fascia and the muscle are the last dorsal, ilio-hypogas- 
 tric, and ilio-inguinal nerves. Its posterior surface is in relation with the middle 
 lamella of the lumbar fascia, which separates it from the Erector spinae. The 
 Quadratus lumborum extends, however, beyond the outer border of the Erector 
 spinae. 
 
 Nerve-supply. — The anterior branches of the last dorsal and first lumbar nerves; 
 sometimes also a branch from the second lumbar nerve. 
 
 Actions. — ^The Quadratus lumborum draws down the last rib. It acts as a 
 muscle of inspiration by helping to fix the origin of the Diaphragm. If the thorax 
 and spine are fixed, it may act upon the pelvis, raising it toward its own side 
 when only one muscle is put in action; and when both muscles act together, either 
 from below or above, they flex the trunk. 
 
 IV. MUSCLES OF THE PELVIC OUTLET. 
 
 The muscles of this region are situated at the pelvic outlet in the ischio-rectal 
 region and the perinaeum. They include the following: 
 
 1. Muscles of the ischio-rectal region. 
 
 2. Muscles of the perinaeum in the male. 
 
 3. Muscles of the perinaeum in the female. 
 
 1. The Muscles of the Ischio-rectal Region. 
 
 Corrugator cutis ani. Internal sphincter ani. 
 
 External sphincter ani. Levator ani. 
 
 Coccygeus. 
 The Corrugator Cutis Ani. — Around the anus is a thin stratum of involuntary 
 muscular fibre, which radiates from the orifice. Internally, the fibres fade off 
 
 29 
 
450 
 
 THE MUSCLES AND FASCIA 
 
 into the submucous tissue, while externally they blend with the true skin. By 
 its contraction it raises the skin into ridges around the margin of the anus. 
 
 The External Sphincter Ani (m. sphincter ani externus) (Figs. 301, 306, 307, and 
 308) is a thin, flat plane of muscular fibres, elliptical in shape and intimately adher- 
 
 FRCNUM OF 
 PREPUCE 
 
 TUBEROSITY 
 OF ISCHIUM 
 
 INFERIOR 
 LAYER OF 
 TRIANGULAR 
 LIGAMENT 
 
 TRANSVERSUS 
 — PERINEI 
 
 SUPERFICIALiS 
 
 ISCHIO-RECTAL 
 fOSSA 
 
 ANO-COCCYGEAL LIGAMENT 
 
 Fig. 301. — The muscles of the male perinseum, viewed from below. (Spalteholz.) 
 
 ent to the integument surrounding the margin of the anus. It measures about 
 three or four inches in length from its anterior to its posterior extremity, being 
 about an inch in breadth opposite the anus. It arises from the tip and back of 
 the coccyx by a narrow tendinous band, and from the superficial fascia in front 
 
OF THE ISCHIO-BECTAL BEGION 
 
 451 
 
 of that bone ; and is inserted into the raphe of the Accelerator urinse muscle and 
 into the central tendinous point of the perinseum, joining with the two Superficial 
 transverse perineal, the Levator ani, and the Accelerator urinse muscles. Many 
 of the fibres are continuous with the Accelerator urinje in the male and with the 
 Sphincter vaginae in the female. Often some of the fibres are continuous with the 
 Transverse perineal muscles. It is continuous above with the Levator ani. Like 
 other sphincter muscles, it consists of two planes of muscular fibre, which sur- 
 round the margin of the anus and join in a commissure in front and behind, 
 some fibres crossing from side to side in front and behind the anus. 
 
 Nerve-supply. — A branch from the anterior division of the fourth sacral and 
 the inferior hfemorrhoidal branch of the internal pudic. 
 
 Actions. — The action of this muscle is peculiar: 1. It is, like other sphincter 
 muscles, always in a state of tonic contraction, and having no antagonistic muscle, 
 it keeps the anal orifice closed. 2. It can be put into a condition of greater con- 
 
 PECTINEUS 
 ADDUCTOR 
 LONGUS 
 GRACILIS. 
 
 Epididymis. 
 
 Ampxina. 
 
 Ampulla of vasn 
 deferens. 
 
 Testicle. 
 
 Ascending ramus of 
 
 ISCHIUM 
 
 Internal ptidic 
 vessels and nerve. 
 
 Fig. 302.-— Side view of pelvis, showing Levator ani. (From a preparation in the Museum of the Royal 
 
 College of Surgeons.) 
 
 traction under the influence of the will, so as to occlude more firmly the anal 
 aperture in expiratory eft'orts unconnected with defecation. 3. Taking its fixed 
 point at the coccyx, it helps to fix the central point of the perinaeum, so that the 
 Accelerator urinae may act from this fixed point. 
 
 The Internal Sphincter Ani {in. sphincter ani intemus) is a muscular ring 
 which surrounds the lower extremity of the rectum for about an inch, its inferior 
 border being contiguous to, but quite separate from, the External sphincter. 
 This muscle is about two lines in thickness, and is formed by an aggregation 
 of the involuntary circular fibres of the intestine. It is paler in color and less 
 coarse in texture than the External sphincter. 
 
 Actions. — Its action is entirely involuntary. It helps the External sphincter 
 to occlude the anal aperture. 
 
 The Levator Ani (Figs. 302, 303, 304, and 305) is a broad, thin muscle, 
 situated on each side of the pelvis. It is attached to the inner surface of the 
 
452 
 
 THE MUSCLES AND FASCIjE 
 
 sides of the true pelvis, and, descending, unites with its fellow of the opposite side 
 to form the floor of the pelvic cavity. It supports the viscera in this cavity and 
 surrounds the various structures which pass through it. It is usually possible to 
 detect an interval between the fibres rising from the pubis and those rising from 
 the pelvic fascia, and this interval marks the fact that the muscle described as one 
 is really two. The pubic fibres constitute the Pubococcygeus muscle and the 
 other fibres the Iliococcygeus muscle.^ 
 
 The Pubococcygeus muscle takes origin from the posterior aspect of the ramus 
 of the pubis and from the most anterior portion of the tendinous arch of the 
 Levator ani muscle. The fibres of origin from the pubis surround anteriorly the 
 origin of the Internal obturator muscle. The muscle is a band, about one inch in 
 width, thickest at its outer border, where it overlaps the Iliococcygeus. It passes 
 backward, downward, and inward, "near the prostate in the male, the urethra 
 and vagina in the female,"^ and near to the rectum. Most of the fibres pass back 
 
 ANTERIOR SACRO- 
 COCCYGEAL LIGAMENT 
 
 GREAT SACRO- 
 SCIATtC LIGAMENT 
 
 OBTURATOR 
 CANAL 
 
 SUPERIOR LAYER 
 OF TRIANGULAR 
 LIGAMENT 
 
 Fig. 303. — The Levator ani of the male, viewed from above. (Spalteholz.) 
 
 of the rectum, where they meet and join with the corresponding fibres of the 
 opposite side. These united fibres form a thick, tendinous aponeurosis. "This 
 is continued upward in front of the coccyx for some distance, and finally divides 
 into two lateral portions, which have been named the ligamenta sacro-coccygea 
 anterior. They are situated on either side of the middle sacral artery, and are 
 finally inserted into the last one or two pieces of the sacrum and the first piece 
 of the coccyx."^ A few of the fibres of the Pubococcygeus muscle pass to the 
 
 1 Peter Thompson. The Myology of the Pelvic Floor. 
 ^ Spalteholz's Atlas. Translated and edited by Barker. 
 * Peter Thompson. The Myology of the Pelvic Floor. 
 
OF THE ISCHIO- RECTAL REGION 
 
 453 
 
 central tendon of the perinseum, come in contact with but do not terminate in the 
 rectal wall, descend in front of and close to the anterior rectal wall, and terminate 
 in the anterior portion of the sphincter ani and in the skin of the anus (Peter 
 Thompson). 
 
 Luschka and others believe that these anterior fibres descend among the longi- 
 tudinal fibres of the rectum. It is certain that the most anterior fibres of the 
 
 COWPER-S SUPCRFICIAL TRANS- 
 GLANDS VERSUS PERINEI 
 
 Fig. 304.— The right Levator ani in the male, viewed from the left. (Spalteholz.) 
 
 Pubococcygeus muscle pass to the central point of the perinseum. They pass 
 "backward and downward on the side of the prostate, and in some cases on the 
 side of the urethra immediately it emerges from the prostate."^ These anterior 
 fibres in the female descend upon the side of the vagina. The anterior fibres 
 are the preanal fibres of the Levator ani. They constitute what Santorini named 
 
 » Peter Thompson. The Myology of the Pelvic Floor. 
 
454 
 
 THE MUSCLES AND FASCIA 
 
 the levator prostatas, because he regarded them as constituting a distinct 
 muscle, which surrounds the prostate as a sling. Krause calls these fibres 
 the levator urethrae ; Testut, the fibres pr^-rectales, and Prout, the Recto-urethralis 
 muscle. 
 
 The Iliococcygeus muscle arises from the tendinous arch of the Levator ani muscle 
 (arcus fendineus m. levatoris ani). This arch is concave upward. The anterior 
 end of the arch begins on the posterior surface of the superior ramus of the 
 pubis. "The posterior end can be followed as far as the linea arcuata of the 
 ilium, between these two points it descends for a variable distance, but always 
 leaves the canalis obturatorius free."^ The fibres, coursing internally and down- 
 ward, pass below the posterior portion of the Pubococcygeus. The anterior 
 fibres join the fibres of the other side, between the anus and the tip of the coccyx 
 in a median raph^. 
 
 The posterior fibres are inserted into the sides of the last two pieces and into 
 the tip of the coccyx. Peter Thompson points out that the Iliococcygeus muscle 
 is liable to variations. It is strongly developed in but few, is usually thin, the 
 muscular bundles being separated by membranous intervals; it may be replaced 
 by fibrous tissue and may even be absent.^ 
 
 INTERNAL 
 ILIAC artery' 
 
 obturator 
 nerve' 
 
 ANTERIOR LAYER OF 
 
 TRIANGULAR LIGAMENT 
 
 POSTERIOR LAYER OF 
 
 TRIANGULAR LIGAMENT 
 
 PARIETAL 
 PELVIC FASCIA 
 ATTACHMENT TO 
 ISCHIAL SPINE 
 
 WHITE LINE 
 ORIGIN OF 
 LEVATOR ANI 
 ITE LINE 
 
 VISCERAL 
 PELVIC FASCIA 
 
 OBTURATOR 
 FASCIA 
 
 Fig. 305. — The outer wall of the pelvis (pelvic fascia). (Cunningham.) 
 
 Relations of the Levator Ani. — By its inner or pelvic surface, with the recto- 
 vesical fascia, which separates it from the viscera of the pelvis and from the 
 peritoneum. By its outer or perineal surface, it forms the inner boundary 
 of the ischio-rectal fossa, and is covered by a thin layer of fascia, the ischio- 
 rectal or anal fascia, given off from the obturator fascia. Its posterior border is 
 free and separated from the Coccygeus muscle by a cellular interspace. Its 
 anterior border is separated from the muscle of the opposite side by a triangular 
 space, through which the urethra, and in the female the vagina, passes from the 
 pelvis. 
 
 Nerve-supply. — A branch from the anterior division of the fourth sacral nerve 
 and a branch from the pudic nerve, which is sometimes derived from the perineal 
 and sometimes from the inferior hemorrhoidal division. 
 
 Actions. — The entire Levator ani muscle enters into the formation of the 
 diaphragm of the pelvis and aids in supporting the rectum, vagina, and bladder. 
 
 1 Spalteholz's Atlas. Translated and edited by Barker. 
 
 2 Myology of Muscles. 
 
OF THE PERINEUM IN THE MALE 455 
 
 The two parts of the muscle have different functions. The IHococcygei have 
 no other function than that of supporting the viscera. In early life they flex the 
 vertebrae of the coccyx on one another and flex the coccyx on the sacrum, but do 
 not act directly at any age on the rectum or pelvic viscera (Peter Thompson). 
 The Pubococcygei, especially in the female, have most important functions. 
 They are the most influential supports of the pelvic floor and restore the pelvic 
 floor to its proper position after the depression induced by parturition, defecation, 
 and efforts at urination.^ Normally, they pull the perinseum upward after the 
 descending head has pulled it down. In some cases the contraction of the muscles 
 actually obstructs the descent of the head (Peter Thompson). The muscles are 
 strongly developed in females, and, acting with the Sphincter vaginae, they aid 
 in contracting the vaginal canal. The muscles constrict the rectum and also lift 
 the rectum with the pelvic floor. During defecation the position of the rectal 
 contents is maintained by intra-abdominal pressure, the muscles lift the perinseum 
 over the fecal matter (Goffe). The Levator ani is also a muscle of forced 
 expiration. 
 
 The Coccygeus is a flat, triangular muscle situated behind and parallel with 
 the preceding. It is a triangular plane of muscular and tendinous fibres, arising, 
 by its apex, from the spine of the ischium, the obturator fascia, the edge of the 
 great sacro-sciatic notch, and from the lesser sacro-sciatic ligament, and inserted, 
 by its base, into the side of the lower two vertebrae of the sacrum and the upper 
 two vertebrae of the coccyx. It assists the Levator ani and Pyriformis in closing 
 in the back part of the outlet of the pelvis. 
 
 Relations. — By its inner or 'pelvic surface, with the rectum. By its external 
 surface, with the lesser sacro-sciatic ligament. The lower border is in relation 
 with the posterior border of the Levator ani, but separated from it by a 
 cellular interval: its upper border is in relation with the lower border of the 
 Pyriformis, but separated from it by the sciatic and internal pudic vessels and 
 nerve. 
 
 Nerve-supply. — A branch from the fourth and fifth sacral nerves. 
 
 Action. — The Coccygei muscles raise and support the coccyx, after it has been 
 pressed backward during defecation or parturition. 
 
 2. The Muscles and Fasciae of the Perinseum in the Male (Figs. 301, 
 
 306, 307, 308). 
 
 Transversus perinei superficialis. Erector penis. 
 
 Accelerator urinae. Compressor urethrae. 
 
 Superficial Fascia (fascia superficialis perinei). — The superficial fascia of the 
 perinaeum consists of two layers, superficial and deep, as in other regions of the 
 body. The superficial fascia over the posterior portion of the perinaeum is 
 arranged in fatty layers which fill the ischio-rectal fossa on each side of the 
 rectum and anus. The superficial fascia over the anterior portion of the peri- 
 naeum (urethral region) requires fuller consideration. 
 
 The Superficial Layer is thick, loose, areolar in texture, and, except toward the 
 scrotum, contains much adipose tissue in its meshes, the amount of which varies 
 in different subjects. In front, it is continuous with the dartos of the scrotum; 
 behind, it is continuous with the subcutaneous areolar tissue surrounding the 
 anus; and, on either side, with the same fascia on the inner side of the thighs. In 
 the middle line it is adherent to the skin of the raphe and to the deep layer of 
 
 1 Peter Thompson. The Myology of the Pelvic Floor. 
 
456 
 
 THE MUSCLES AND FASCIA 
 
 the superficial fascia. This layer should be carefully removed after it has been 
 examined, when the deep layer will be exposed. 
 
 The Deep Layer of Superficial Fascia or the Fascia of Colles is thin, aponeurotic 
 in structure, and of considerable strength, serving to bind down the muscles of the 
 root of the penis. It is continuous, in front, with the deep fascia of the penis, 
 and the dartos of the scrotum, the fascia of the spermatic cord, and Scarpa's 
 fascia upon the anterior portion of the abdomen; on either side it is firmly 
 attached to the margins of the rami of the os pubis and ischium, external to 
 the crus penis, and as far back as the tuberosity of the ischium; posteriorly, 
 it curves down behind the Superficial transverse perineal muscles (reflected 
 portion of fascia) to join the lower margin of the triangular ligament, which 
 structure is a prolongation of the deep layer of the superficial fascia. The 
 deep layer is attached to the superficial layer in the median line and to the 
 
 Fig. 306. — The perinseum. The integument and superficial layer of superficial fascia reflected. 
 
 median septum of the Accelerator urinse muscle. At the central tendon of the 
 perineum the reflected portion of the fascia becomes blended with the inser- 
 tions of the External anal sphincter, the two Superficial transverse perineal 
 muscles, and the Accelerator urinse. This fascia not only covers the muscles 
 in this region, but sends upward a vertical septum from its deep surface, which 
 separates the back part of the subjacent space into two, the septum being 
 incomplete in front. 
 
 The Central Tendinous Point of the Perinseum. — This is a fibrous point in the 
 middle line of the perinseum, between the urethra and the rectum, being about 
 half an inch in front of the anus. At this point four muscles converge and are 
 attached — viz., the External sphincter ani, the Accelerator urinae, and the two 
 Superficial transverse perineal ; so that by the contraction of these muscles, which 
 extend in opposite directions, it serves as a fixed point of support. 
 
OF THE PERINJEUM IN THE MALE 
 
 457 
 
 The Transversus Perinei Superficialis is a narrow muscular slip, which passes 
 more or less transversely across the back part of the perineal space. It arises 
 by a small tendon from the inner and forepart of the tuberosity of the ischium, 
 and, passing inward, is inserted into the central tendinous point of the perinseum, 
 joining in this situation with the muscle of the opposite side, the External 
 sphincter ani behind, and the Accelerator urinse in front. The base of the tri- 
 angular ligament lies just beneath this muscle. 
 
 Nerve-supply. — The perineal branch of the internal pudic. 
 
 Actions. — By their contraction they serve to fix the central tendinous point of 
 the perinseum. 
 
 The Accelerator Urinse, called also the Ejaculator seminis and the Ejaculator 
 urinse (m. hulhocavernosus) , is placed in the middle line of the perinaeum, imme- 
 diately in front of the anus. It consists of two symmetrical halves, united 
 along the median line by a tendinous raph^. It arises from the central tendon 
 
 Transversus perinei 
 superficialis 
 
 GREAT SACRO- 
 SCIATIC LIGAMENT 
 
 Superficial perineal artery. 
 Superficial perineal nerve. 
 Internal pudic nerve. 
 Internal pudic artery. 
 
 Fig. 307. — The superficial muscles and vessels of the perinseum. 
 
 of the peringeum, and from the median raph^ in front. From this point its fibres 
 diverge like the plumes of a pen; the most posterior form a thin layer, which is 
 lost on the anterior surface of the triangular ligament; the middle fibres encircle 
 the bulb and adjacent parts of the corpus spongiosum, and join with the fibres 
 of the opposite side, on the upper part of the corpus spongiosum, in a strong 
 aponeurosis; the anterior fibres, the longest and most distinct, spread out over 
 the sides of the corpus cavernosum, to be inserted partly into that body, anterior 
 to the Erector penis, occasionally extending to the os pubis; partly terminating 
 in a tendinous expansion, which covers the dorsal vessels of the penis. The latter 
 fibres are best seen by dividing the muscle longitudinally, and dissecting it out- 
 ward from the surface of the urethra. Many fibres of the External sphincter 
 ani and of the Superficial transverse perineal muscles pass into this muscle. 
 
 Action. — ^This muscle serves to empty the canal of the urethra, after the 
 bladder has expelled its contents; during the greater part of the act of micturition 
 
458 
 
 THE MUSCLES AND FASCIA 
 
 its fibres are relaxed, and it only comes into action at the end of the process. 
 The middle fibres are supposed, by Krause, to assist in the erection of the corpus 
 spongiosum, by compressing the erectile tissue of the bulb. The anterior fibres, 
 on each side, which are known as Houston's muscles, according to Tyrrel, also 
 contribute to the erection of the penis, as they are inserted into, and continuous 
 with, the fascia of the penis, compressing the dorsal vein during the contraction 
 of the muscle. 
 
 The Erector Penis (m. ischiocavernosus) covers part of the crus penis. It is an 
 elongated muscle, broader in the middle than at either extremity, and situated on 
 either side of the lateral boundary of the perinaeum. It arises by tendinous and 
 fleshy fibres from the inner surface of the tuberosity of the ischium, behind the 
 crus penis, from the surface of the crus, and from the adjacent portion of the 
 ramus of the ischium. From these points fleshy fibres succeed, which end 
 in an aponeurosis which is inserted into the sides and under surface of the 
 crus penis. 
 
 Nerve-supply. — The perineal branch of the internal pudic. 
 
 Anterior layer of 
 
 deep peHneal fascia removed, 
 
 showing 
 
 COMPRESSOR URETHRC 
 
 _Jnternal pudic artery. 
 Artery of the bulb. 
 Cowper's gland. 
 
 Fig. 308. — Triangular ligament or deep perineal fascia. On the left side the anterior layer has been removed. 
 
 Actions. — It compresses the crus penis and retards the return of the blood 
 through the veins, and thus serves to maintain the organ erect. 
 
 Between the muscles just examined a triangular space exists, bounded inter- 
 nally by the Accelerator urinse, externally by the Erector penis, and behind by 
 the Transversus perinei superficialis. The floor of this space is formed by the 
 triangular ligament of the urethra (deep perineal fascia), and running from behind 
 forward in it are the superficial perineal vessels and nerves, the long pudendal 
 nerve, and the transverse perineal artery coursing along the posterior boundary 
 of the space on the Transversus perinei superficialis. 
 
 The Triangulax Ligament or the Deep Perineal Fascia (trigonum or diaphragma 
 urogenitale) (Figs. 305, 309, and 310) is stretched almost horizontally across the 
 pubic arch, so as to close in the front part of the outlet of the pelvis. It con- 
 
OF THE PERINEUM IN THE HALE 
 
 459 
 
 sists of two dense musculo-membranous laminae, which are united along their 
 posterior borders, but are separated in front by intervening structures. The 
 superficial of these two layers, the superficial, anterior, or inferior layer of the 
 triangular ligament (fascia trigoni urogenitalis inferior), is triangular in shape 
 and about an inch and a half in depth. Its apex is directed forward, and is 
 separated from the subpubic ligament by an oval opening for the transmission 
 of the dorsal vein of the penis. The apex of the triangular ligament is called the 
 
 DEEP LAYER OF 
 SUPERFICIAL FASCIA 
 
 PERITONEUM 
 
 PROSTATIC 
 FASCIA 
 
 DEEP LAYER 
 OF TRIANGULAR 
 '^ LIGAMENT 
 
 OMPRESSOR 
 URETHR>E 
 MUSCLE 
 SUPERFICIAL LAYER OF 
 TRIANGULAR LIGAMENT 
 
 Fig. 309. — The aponeurosis of the perinseum. (Denonvilliers.) 
 
 transverse perineal or transverse pelvic ligament (ligamentum transversum pelvis). 
 The lateral margins of the inferior layer of the triangular ligament are attached 
 on each side to the rami of the ischium and os pubis, above the crura penis. 
 The fusion of the two leaves posteriorly takes place beneath the Superficial 
 transverse perineal muscles. The region of fusion of the two leaflets posteriorly 
 is called the base. The base is directed toward the rectum, and connected to 
 
 DORSAL VEIN 
 
 OF PENIS 
 
 DORSAL NERVE 
 
 OF PEN 
 
 DORSAL ARTERY 
 
 OF PENIS 
 
 ARTERY TO 
 
 BULB 
 
 COMPRESSOR 
 
 URETHR/E 
 
 conpus. 
 
 SPONGIOSUM 
 
 ERECTOR 
 PENIS 
 
 CORPUS 
 CAVERNOSUM 
 TRIANGULAR 
 LIGAMENT 
 
 (upper margin) 
 
 Fig 310 — The superficial layer of the triangular liRament. The Compressor urethrse muscle lies behind the 
 superficial layer of the triangular ligament and is shown in the figure for convenience. (Poirier and Charpy.) 
 
 the central tendinous point of the perinseum. It is continuous with the deep 
 layer of the superficial fascia behind the Superficial transverse perineal muscles, 
 and with a thin fascia which covers the cutaneous surface of the Levator ani 
 muscle, the anal or ischio-rectal fascia. 
 
 This layer of the triangular ligament is perforated, about an inch below the 
 symphysis pubis, by the urethra, the aperture for which is circular in form and 
 
460 THE MUSCLES AND FASCIA 
 
 about three or four lines in diameter; by the arteries to the bulb and the ducts of 
 Cowper's glands close to the urethral orifice; by the arteries to the corpora caver- 
 nosa — one on each side, close to the pubic arch and about half-way along the 
 attached margin of the ligament ; by the dorsal arteries and nerves of the penis near 
 the apex of the ligament. Its base is also perforated by the superficial perineal 
 vessels and nerves, while between its apex and the subpubic ligament the dorsal 
 nerve of the penis and the dorsal vein of the penis passes upward into the 
 pelvis. 
 
 If this superficial or inferior layer of the triangular ligament is detached on 
 either side, the following structures will be seen between it and the deeper 
 layer: the dorsal vein of the penis; the membranous portion of the urethra, 
 arid the Compressor urethrse muscle; Cowper's glands and their ducts; the 
 pudic vessels and dorsal nerve of the penis; the artery and nerve of the bulb, 
 and a plexus of veins. The two layers join the urethral wall and vagina 
 medianward. 
 
 The deep, posterior, or superior layer (fascia trigoni urogenitalis superior) of the 
 triangular ligament is derived from the obturator fascia and stretches across 
 the pubic arch. If the obturator fascia is traced inward after covering the 
 Obturator internus muscle, it will be found to be attached by some of its 
 deeper or anterior fibres to the inner margin of the ischio-pubic ramus, while its 
 superficial or posterior fibres pass over this attachment to become the superior 
 layer of the triangular ligament. Behind, this layer of the fascia is continuous 
 with the inferior layer and with the fascia of Colles, and in front it is separated 
 from the apex of the prostate gland through the intervention of a prolongation of 
 the recto-vesical fascia. It is pierced by the urethra, or rather consists of two 
 halves which are separated in the middle line by the urethra passing between 
 them. 
 
 The Compressor or Constrictor Urethrae (m. constrictor urethrce) in the male 
 surrounds the whole length of the membranous portion of the urethra, and is 
 contained between the two layers of the triangular ligament. It arises, by apon- 
 eurotic fibres, from the junction of the rami of the os pubis and ischium, to the 
 extent of half or three-quarters of an inch: the point where the crura penis joins 
 the transverse ligament of the perineum and the layers of the triangular liga- 
 ment; each segment of the muscle passes inward, and divides into twofascicuH, 
 which surround the membranous urethra and unite, at the upper and lower 
 surfaces of this tube, with the muscle of the opposite side by means of a tendinous 
 raphe. The Compressor urethne is continuous posteriorly with the m. prostaticus 
 and is continuous anteriorly with the circular fibres of the cavernous portion of 
 the urethra. This muscle is frequently in two portions, an anterior and a 
 posterior, separated by a distinct interval. In such cases the posterior fibres are 
 called the transversus perinei profundus, and the anterior fibres are called the 
 sphincter urethrae membranacese. 
 
 Nerve-supply. — The perineal branch of the internal pudic. 
 
 Actions. — The muscles of both sides act together as a sphincter, compressing 
 the membranous portion of the urethra. During the transmission of fluids they, 
 like the Acceleratores urinte, are relaxed, and come into action only at the end of 
 the process, to eject the last drops of the fluid. 
 
 3. The Muscles of the Perinaeum in the Female (Fig. 311). 
 
 Transversus perinei superficialis. Erector clitoridis. 
 
 Sphincter vaginae. Compressor urethrae. 
 
 The Transversus Perinei Superficialis in the female is a narrow muscular slip, 
 which passes more or less transversely across the back part of the perineal space. 
 
OF THE PERINjEUM IN THE FEMALE 
 
 461 
 
 It arises by a small tendon from the inner and forepart of the tuberosity of the 
 ischium, and, passing inward, is inserted into the central point of the perinseum, 
 joining in this situation with the muscle of the opposite side, the External sphinc- 
 ter ani behind, and the Sphincter vaginae in front. 
 
 Nerve-supply. — The perineal branch of the internal pudic. 
 
 Actions. — By their contraction they serve to fix the central tendinous point of 
 the perinseum. 
 
 The Sphincter Vaginae (m. hulbocavemosus) surrounds the orifice of the 
 vagina, and is analogous to the Accelerator urinse in the male. It is attached 
 posteriorly to the central tendinous point of the perinseum, where it blends with 
 
 TRANSVERSUS 
 PERINjCI. 
 
 LIBER ISCHII. 
 
 Fig. 311. — Muscles of the female perinajum. 
 
 the External sphincter ani. Its fibres pass forward on each side of the vagina, to 
 be inserted into the corpora cavernosa of the clitoris, a fasciculus crossing over 
 the body of the organ so as to compress the dorsal vein. 
 
 Nerve-supply. — The perineal branch of the internal pudic. 
 
 Actions. — It diminishes the orifice of the vagina. The anterior fibres contribute 
 to the erection of the clitoris, as they are inserted into and are continuous with the 
 fascia of the clitoris; compressing the dorsal vein during the contraction of the 
 muscle. 
 
 The Erector Clitoridis (m. ischiocavemosus) resembles the Erector penis in the 
 male, but is smaller than it. It covers the unattached part of the crus clitoridis. 
 It is an elongated muscle, broader at the middle than at either extremity, and 
 situated on either side of the lateral boundary of the perinseum. It arises by 
 tendinous and fleshy fibres from the inner surface of the tuberosity of the ischium, 
 behind the crus clitoridis from the surface of the crus, and from the adjacent 
 portion of the ramus of the ischium. From these points fleshy fibres succeed, 
 
462 
 
 THE 3IU8CLES AND FASCIA 
 
 which end in an aponeurosis, which is inserted into the sides and under surface 
 of the crus chtoridis. 
 
 Nerve-supply. — The perineal branch of the internal pudic. 
 
 Actions. — It compresses the crus clitoridis and retards the return of blood 
 through the veins, and thus serves to maintain the organ erect. 
 
 The Triangular Ligament (trigonum urogenitale) in the female is not so strong 
 as in the male. It is divided in the middle line by the aperture of the vagina, 
 with the external coat of which it becomes blended, and in front of this is 
 perforated by the urethra. Its posterior border is continuous, as in the male, 
 with the deep layer of the superficial fascia around the Transversus perinei 
 muscle. 
 
 Like the triangular ligament in the male, it consists of two layers, between 
 which are to be found the following structures: the dorsal vein of the clitoris, 
 a portion of the urethra and the Compressor urethrae muscle, the glands of Bar- 
 tholin and their ducts; the pudic vessels and the dorsal nerve of the clitoris; the 
 arteries of the bulbi vestibuli, and a plexus of veins. 
 
 The Compressor Urethrae (m. constrictor urethrce) arises on each side from the 
 margin of the descending ramus of the os pubis. The fibres, passing inward, 
 divide into two sets: those of the forepart of the muscle are directed across the 
 subpubic arch in front of the urethra to blend with the muscular fibres of the 
 opposite side; while those of the hinder and larger part pass inward to blend with 
 the wall of the vagina behind the urethra. 
 
 Nerve-supply. — The perineal branch of the internal pudic. 
 
 MUSCLES AND FASCI-ffi OF THE UPPER EXTREMITY. 
 
 The muscles of the Upper Extremity are divisible into groups, corresponding 
 with the different regions of the limb. 
 
 I. Of the TfjORACic Region. 
 
 1. Anterior Thoracic Region. 
 
 Pectoralis major. Pectoralis minor. 
 Subclavius. 
 
 2. Lateral Thoracic Region. 
 
 Serratus magnus. 
 
 II. Of the Shoulder and Arm. 
 
 3. Acromial Region. 
 
 Deltoid. 
 
 4. Anterior Scapular Region. 
 
 Subscapularis. 
 
 5. Posterior Scapular Region. 
 
 Supraspinatus. Teres minor. 
 
 Infraspinatus. Teres major. 
 
 6. Anterior Humeral Region. 
 
 Coraco-brachialis. Biceps. 
 
 Brachialis anticus. 
 
 7. Posterior Humeral Region. 
 Triceps. Subanconeus. 
 
 III. Of the Forearm. 
 
 8. Anterior Radio-ulnar Region. 
 
 Pronator radii teres. 
 
 Flexor carpi radialis. 
 
 Palmaris longus. 
 
 Flexor carpi ulnaris. 
 L Flexor sublimis digitorum. 
 f Flexor profundus digitorum. 
 j Flexor longus pollicis. 
 [Pronator quadratus. 
 
 .2 
 
 9. Radial Region. 
 
 Supinator longus. 
 
 Extensor carpi radialis longior. 
 
 Extensor carpi radialis brevior. 
 
^_^ 
 
 
 .2 
 
 
 
 
 *5 
 
 t-l 
 
 ^ 
 
 
 0) 
 
 rf 1 
 
 ^^ 1 
 
 02 
 
 
 Oh 
 
 
 o 
 
 b5 
 1— 1 
 
 yff^ ANTERIOR THORACIC REGION 463 
 
 10. Posterior Radio-Ulnar Region. Flexor brevis pollicis. 
 
 J? ^ ^^„^\c, ^;^,-+^^,,rv. Adductor obliquus pollicis. 
 
 Extensor communis aigitorum. . , , , , ^ ^ „. . 
 
 t:, , • •_• ,1- :+; Adductor transversus pollicis. 
 
 Extensor minimi digiti. ^ 
 
 Extensor carpi ulnaris. 
 
 Anconeus. 1*^- Ulnar Region. 
 
 Supinator brevis. Palmaris brevis. 
 
 Extensor ossis metacarpi poUici. Abductor minimi digiti. 
 
 Extensor brevis pollicis. Ylexor brevis minimi digiti. 
 
 Extensor longus pollicis. p^g^^j. ossis metacarpi minimi digiti 
 
 Extensor indicis. (Opponens minimi digiti). 
 
 IV. Of the Hand. 
 
 11. Radial Region. l^- ^'^^^' ^^^^«^ ^'d^""' 
 
 Abductor pollicis. Lumbricales. 
 
 Flexor ossis metacarpi pollicis Interossei palmares. 
 
 (Opponens pollicis). Interossei dorsales. 
 
 Dissection of Pectoral Region and Axilla (Fig. 312). — The arm being drawn away from 
 the side nearly at right angles with the trunk and rotated outward, make a vertical incision 
 through the integument in the median line of the chest, from the upper to the lower part of the 
 sternum; a second incision along the lower border of the Pectoral muscle, from the ensiform 
 cartilage to the inner side of the axilla ; a third, from the sternum along the clavicle, as far as its 
 centre; and a fourth, from the middle of the clavicle obliquely downward, along the interspace 
 between the Pectoral and Deltoid muscles, as low as the fold of the armpit. The flap of integu- 
 ment is then to be dissected off in the direction indicated in the figure, but not entirely removed, 
 as it should be replaced on completing the dissection. If a transverse incision is now made 
 from the lower end of the sternum to the side of the chest, as far as the posterior fold of the 
 armpit, and the integument reflected outward, the axillary space will be more completely exposed. 
 
 I. THE MUSCLES AND FASGIiE OF THE THORACIC REGION. 
 1. The Anterior Thoracic Region. 
 
 Pectoralis major. Pectoralis minor. 
 
 Subclavius. 
 
 Superficial Fascia. — ^The superficial fascia of the thoracic region is a loose 
 cellulo-fibrous layer enclosing masses of fat in its spaces. It is continuous with 
 the superficial fascia of the neck and upper extremity above, and of the abdomen 
 below. Opposite the mamma it divides into two layers, one of which passes in 
 front, the other behind, that gland; and from both of these layers numerous septa 
 pass into its substance, supporting its various lobes : from the anterior layer fibrous 
 processes pass forward to the integument and nipple. These processes were called 
 by Sir A. Cooper the suspensory ligaments (ligamenta suspensoria) , from the sup- 
 port they afford to the gland in this situation. 
 
 Deep Fascia. — The deep thoracic fascia is a thin aponeurotic lamina, cover- 
 ing the surface of the great Pectoral muscle, and sending numerous prolongations 
 between its fasciculi: it is attached, in the middle line, to the front of the sternum, 
 and above to the clavicle; externally and below it becomes continuous with the 
 fascia over the shoulder, axilla, and thorax. It is very thin over the upper part 
 of the muscle, thicker in the interval between the Pectoralis major and Eatissimus 
 dorsi, where it closes in the axillary space, and is known as the axillary fascia (fascia 
 axillaris). It passes behind into the fascia of the Latissimus dorsi and Teres 
 major, in front into the fascia of the deltoid and outward into the brachial 
 fascia. The fascia of the liatissimus dorsi divides at the outer margin of the 
 muscle into two layers, one of which passes in front and the other behind it; these 
 proceed as far as the spinous processes of the dorsal vertebrae, to which they are 
 
464 
 
 THE MUSCLES AND FASCIA 
 
 attached. As the axillary fascia leaves the lower edge of the Pectoralis major to 
 pass across the floor of the axilla it sends a layer upward under cover of the 
 muscle, deep pectoral fascia: this lamina splits to envelop the Pectoralis minor, at 
 the upper edge of which it becomes continuous with the costo-coracoid membrane, 
 or the clavi-pectoral fascia. The hollow of the armpit, seen when the arm is 
 abducted, is mainly produced by the traction of this fascia on the axillary floor, 
 the axillary fascia (fascia axillaris), and hence it is sometimes named the 
 suspensory ligament of the axilla. The axillary fascia (Fig. 313) is not a dis- 
 tinct and complete rigid floor of the axillary space. Like all other fasciae, it 
 follows muscular planes, and splits to encompass vessels, nerves, and muscles. 
 In it are numerous perforations. In this fascia is a curved arch which often 
 contains muscular fibres and which passes from the tendon of the great Pectoral, 
 
 S. Dissection of 
 Shoulder and Arm, 
 
 1. Dissection of 
 Pectoral Region 
 and Axilla. 
 
 2. Bend of Elbow. 
 
 Jf, Forearm. 
 
 B. Palm of Hand. 
 
 Fig. 312. — Dissection of upper extremity. 
 
 the Coraco-brachialis or the fascia over the biceps to the tendon of the Latissimus 
 dorsi. This is called the axillary arch. Langer showed many years ago that there 
 is an opening in the centre of the dense axillary fascia, the foramen of Langer. 
 Through this opening axillary glands not unusually protrude. The axillary arch 
 is the inner margin of the foramen of Langer. At the lower part of the thoracic 
 region the deep thoracic fascia is well developed, and is continuous with the 
 fibrous sheath of the Recti muscles. 
 
 The Pectoralis Major (Fig. 314) is a broad, thick, triangular muscle, situated 
 at the upper and forepart of the chest, in front of the axilla. It arises from the 
 anterior surface of the sternal half of the clavicle; from half the breadth of the 
 anterior surface of the sternum, as low down as the attachment of the cartilage 
 of the sixth or seventh rib ; this portion of its origin consists of aponeurotic fibres, 
 which intersect with those of the opposite muscle; it also arises from the carti- 
 
THE ANTERIOR THORACIC REGION 
 
 465 
 
 lages of all true ribs, with the exception, frequently, of the first or of the seventh, 
 or both; and from the aponeurosis of the External oblique muscle of the abdo- 
 men. The fibres from this extensive origin converge toward its insertion, giving 
 to the muscle a radiated appearance. Those fibres which arise from the clavicle 
 pass obliquely outward and downward and are usually separated from the rest 
 by a cellular interval : those from the lower part of the sternum, and the cartilages 
 of the lower true ribs, pass upward and outward, whilst the middle fibres pass 
 horizontally. They all terminate in a flat tendon, about two inches broad, which 
 is inserted into the outer bicipital ridge of the humerus. This tendon consists of 
 two laminae, placed one in front of the other, and usually blended together below. 
 The anterior, the thicker, receives the clavicular and upper half of the sternal 
 portion of the muscle; and its fibres are inserted in the same order as that in 
 which they arise; that is to say, the outermost fibres of origin from the clavicle are 
 
 SUBSCAPULAR 
 ARTERY AND VelN 
 
 Fig. 313. — The fa.scia of the right axilla, viewed from below. (Spalteholz.) 
 
 inserted at the uppermost part of the tendon; the upper fibres of origin from the 
 sternum pass down to the lowermost part of this anterior lamina of the tendon 
 and extend as low as the tendon of the Deltoid and join with it. The posterior 
 lamina of the tendon receives the attachment of the lower half of the sternal por- 
 tion and the deeper part of the muscle from the costal cartilages. These deep 
 fibres, and particularly those from the lower costal cartilages, ascend, the higher, 
 turning backward successively behind the superficial and upper ones, so that the 
 tendon appears to be twisted. The posterior lamina reaches higher on the humerus 
 than does the anterior one, and from it an expansion is given off which covers 
 the bicipital groove and blends with the capsule of the shoiilder-joint. From the 
 deepest fibres of this lamina at its insertion an expansion is given off which lines 
 the bicipital groove of the humerus, while from the lower border of the tendon a 
 third expansion passes downward to the fascia of the arm. Between the poste- 
 
 30 
 
466 
 
 THE MUSCLED AND FASCIA 
 
 rior surface of the tendon of the great pectoral and the anterior surface of the 
 long head of the biceps there is usually a bursa {bursa m. pectoralis majoris). 
 
 Relations. — By its anterior surface, with the integument, the superficial fascia, 
 the Platysma, some of the branches of the descending cervical nerves, the mam- 
 mary gland, and the deep fascia; by its posterior surface: its thoracic 'portion, with 
 the sternum, the ribs and costal cartilages, the costo-coracoid membrane, the Sub- 
 clavius, Pectoralis minor, Serratus magnus, and the Intercostals ; its axillary por- 
 
 FiG. 314. — Muscles of the chest and front of the arm. Superficial view. 
 
 tion forms the anterior wall of the axillary space, and covers the axillary vessels and 
 nerves, the Biceps and Coraco-brachialis muscles. Its upper border lies parallel 
 with the Deltoid, from which it is separated by a slight interspace in which lie the 
 cephalic vein and humeral branch of the acromial thoracic artery. Its lower border 
 forms the anterior margin of the axilla, being at first separated from the Latissimus 
 dorsi by a considerable interval; but both muscles gradually converge toward the 
 outer part of the space. 
 
THE ANTERIOR THORACIC REGION 
 
 407 
 
 Dissection.— Detach the Pectoralis major by dividing the muscle along its attachment to 
 the clavicle, and by making a vertical incision through its substance a little external to its line of 
 attachment to the sternum and costal cartilages. The muscle should then be reflected outward, 
 and its tendon carefully examined. The Pectoralis minor is now exposed, and immediately 
 above it, in the interval between its upper border and the clavicle, a strong fascia, the costo- 
 coracoid membrane. 
 
 The Costo-coracoid Membrane or the Clavipectoral Fascia is a strong fascia, 
 situated under cover of the clavicular portion of the Pectorahs major muscle. It 
 occupies the interval between the Pectoralis minor and Subclavius muscle, and pro- 
 tects the axillary vessels and nerves. Traced upward, it splits to enclose the Sub- 
 clavius muscle, and its two layers are attached to the clavicle, one in front of and 
 the other behind the muscle; the latter layer fuses with the deep cervical fascia and 
 
 Fig. 315.^ — Muscles of the chest and front of the arm, showing some of the boundaries of the axilla. 
 
 with the sheath of the axillary vessels. Internally, it blends with the fascia covering 
 the first two intercostal spaces, and is attached also to the first rib internal to the 
 origin of the Subclavius muscle. Externally it is very thick and dense, and is 
 attached to the coracoid process. The portion extending from its attachment to 
 the first rib to the coracoid process is often whiter and denser than the rest; this 
 is sometimes called the costo-coracoid ligament. Below, it is thin, and at the upper 
 border of the Pectoralis minor it splits into two layers to invest the muscle; from 
 the lower border of the Pectoralis minor it is continued downward to join the axil- 
 lary fascia, and outward to join the fascia over the short head of the Biceps. The 
 costo-coracoid membrane is pierced by the cephalic vein, the acromial thoracic 
 artery and vein, superior thoracic artery, and anterior thoracic nerves. 
 
468 'J'HE MUSCLES AND FASCIA 
 
 The Pectoralis Minor (Fig. 315) is a thin, flat, triangular muscle, situated at 
 the upper part of the thorax, beneath the Pectoralis major. It arises by three 
 tendinous digitations from the upper margin and outer surface of the third, fourth, 
 and fifth ribs, near their cartilages, and from the aponeurosis covering the Inter- 
 costal muscles; the fibres pass upward and outward, and converge to form a flat 
 tendon, which is inserted into the inner border and upper surface of the coracoid 
 process of the scapula. 
 
 Relations. — By its anterior surface, with the Pectoralis major and the thoracic 
 branches of the acromial thoracic artery. By its 'posterior surface, with the 
 ribs, Intercostal muscles, Serratus magnus, the axillary space, and the axillary 
 vessels and brachial plexus of nerves. Its upper border is separated from the 
 clavicle by a triangular interval, broad internally, narrow externally, which is 
 occupied by the costo-coracoid membrane. This space contains the first part of 
 the axillary vessels and the axillary nerves. Running parallel to the lower border 
 of the muscle is the long thoracic artery. 
 
 The costo-coracoid membrane should now be removed, when the Subclavius muscle will 
 be seen. 
 
 The Subclavius is a small triangular muscle, placed in the interval between the 
 clavicle and the first rib. It arises by a short, thick tendon from the first rib and 
 its cartilage at their junction, in front of the rhomboid ligament; the fleshy fibres 
 proceed obliquely upward and outward, to be inserted into a deep groove on the 
 under surface of the clavicle. An extension from the aponeurosis of this muscle 
 lies upon the subclavian vein. 
 
 Relations. — By its upper surface, with the clavicle. By its deep surface it is 
 separated from the first rib by the subclavian vessels and brachial plexus of nerves. 
 Its anterior surface is separated from the Pectoralis major by the costo-coracoid 
 membrane, which, with the clavicle, forms an osseo-fibrous sheath in which the 
 muscle is enclosed. 
 
 If the costal attachment of the Pectoralis minor is divided across, and the muscle reflected 
 outward, the axillary vessels and nerves are brought fully into view, and should be examined. 
 
 Nerves. — The Pectoral muscles are supplied by the anterior thoracic nerves; 
 the Pectoralis major through these nerves receives filaments from all the spinal 
 nerves entering into the formation of the brachial plexus; the Pectoralis minor 
 receives its fibres from the eighth cervical and first dorsal nerves. The Subclavius 
 is supplied by a filament from the fifth cervical nerve. 
 
 Actions. — If the arm has been raised by the Deltoid, the Pectoralis major will, 
 conjointly with the Latissimus dorsi and Teres major, depress it to the side of the 
 chest. If acting alone, it adducts and draws forward the arm, bringing it across 
 the front of the chest, and at the same time rotates it inward. The Pectoralis minor 
 depresses the point of the shoulder, drawing the scapula downward and inward 
 to the thorax, and throwing the inferior angle backward. The Subclavius de- 
 presses the shoulder, drawing the clavicle downward and forward. When the 
 arms are fixed, all three muscles act upon the ribs, drawing them upward and 
 expanding the chest, and thus becoming very important agents in forced inspira- 
 tion. Asthmatic patients always assume an attitude which fixes the shoulders, so 
 that all these muscles may be brought into action to assist in dilating the cavity 
 of the chest. 
 
 2. The Lateral Thoracic Region. 
 
 Serratus magnus. 
 
 The Serratus Magnus (m. serratus anterior) (Figs. 315 and 316) is a thin, irregu- 
 larly quadrilateral muscle, situated between the ribs and the scapula at the upper 
 
THE LATERAL THORACIC REGION 
 
 469 
 
 Slip of SERRATUS 
 
 MAGNUS to first rib. 
 
 Spine of 
 scapula. 
 
 and lateral part of the chest. It arises by nine digitations or slips from the outer 
 surface and upper border of the eight upper ribs (the second rib giving origin to 
 two slips), and from the aponeurosis covering the corresponding intercostal muscles. 
 From this extensive attachment the fibres pass backward, closely applied to the 
 chest- wall, and reach the vertebral border of 
 the scapula, and are inserted into its ventral 
 aspect in the following manner. The upper 
 two digitations — i. e., the one from the first 
 rib and the higher of the two from the second 
 rib — converge to be inserted into a triangular 
 area on the ventral aspect of the superior 
 angle. The next two digitations spread out 
 to form a thin triangular sheet, the base of 
 which is directed backward and is inserted 
 into nearly the whole length of the ventral 
 aspect of the vertebral border. The lower 
 five digitations converge, as they pass back- 
 ward from the ribs, to form a fan-shaped 
 structure, the apex of which is inserted, 
 partly by muscular and partly by tendinous 
 fibres, into a triangular impression on the 
 ventral aspect of the inferior angle. The 
 lower four slips interdigitate at their origin 
 with the upper five slips of the External 
 oblique muscle of the abdomen. 
 
 Relations. — This muscle is partly covered, 
 in front, by the Pectoral muscles; l)ehind, 
 by the Subscapularis. The axillary vessels 
 and nerves lie upon its upper part, while its 
 deep surface rests upon the ribs and inter- 
 costal muscles. 
 
 Nerve. — The Serratus magnus is supplied 
 by the posterior thoracic nerve, which is de- 
 rived from the fifth, sixth, and generally the 
 seventh cervical nerves. 
 
 Actions. — The Serratus magnus, as a 
 whole, carries the scapula forward, and at 
 the same time raises the vertebral border of 
 the bone. It is therefore concerned in the 
 action of pushing. Its lower and stronger fibres move forward the lower angle 
 and assist the Trapezius in rotating the bone round an axis through its centre, 
 and thus assists this muscle in raising the acromion and supporting weights upon 
 the shoulder. It is also an assistant to the Deltoid in raising the arm, inasmuch as 
 during the action of this latter muscle it fixes the scapula and so steadies the glen- 
 oid cavity on which the head of the humerus rotat'es. After the Deltoid has raised 
 the arm to a right angle with the trunk, the Serratus magnus and the Trapezius, 
 by rotating the scapula, raise the arm into an almost vertical position. It is pos- 
 sible that when the shoulders are fixed the lower fibres of the Serratus magnus may 
 assist in raising and everting the ribs; but it is not the important inspiratory muscle 
 which it was formerly believed to be. 
 
 EXTERNAL 
 OBLIQUE. 
 
 Eighth rib. 
 
 Fig. 316. — Serratus magnus. (From a prepa- 
 ration in the Museum of the Royal College of Sur- 
 geons of England.) 
 
 Surgical Anatomy.— When the muscle is paralyzed, the vertebral border, and especially 
 the lower angle of the scapula, leaves the ribs and stands out prominently on the surface, giving 
 a peculiar "winged" appearance to the back. The patient is unable to raise the arm, and an 
 
470 THE MUSCLES AND FASCIA 
 
 attempt to do so is followed by a further projection of the lower angle of the scapula from the 
 back of the thorax. 
 
 Dissection.— After completing the dissection of the axilla, if the muscles of the back have 
 been dissected, the upper extremity should be separated from the trunk. Saw through the 
 clavicle at its centre, and then cut through the muscles which connect the scapula and arm with 
 the trunk — viz., the Pectoralis minor in front, Serratus magnus at the side, and the Levator 
 anguli scapulae, the Rhomboids, Trapezius, and Latissimus dorsi behind. These muscles should 
 be cleaned and traced to their respective insertions. Then make an incision through the integu- 
 ment, commencing at the outer third of the clavicle, and extending along the margin of that 
 bone, the acromion process, and spine of the scapula; the integument should be dissected from 
 above downward and outward, when the fascia covering the Deltoid is exposed (Fig. 312, No. 3). 
 
 II. MUSCLES AND FASCIiE OF THE SHOULDER AND ARM. 
 
 Superficial Fascia. — ^The superficial fascia of the upper extremity is a thin 
 cellulb-fibrous layer, containing the superficial veins and lymphatics, and the 
 cutaneous nerves; It is most distinct in front of the elbow, and contains very large 
 superficial veins and nerves ; in the hand it is hardly demonstrable, the integument 
 being closely adherent to the deep fascia by dense fibrous bands. Small sub- 
 cutaneous bursse are found in this fascia over the acromion, the olecranon, and 
 the knuckles. 
 
 Deep Fascia. — The deep fascia of the upper extremity comprises the aponeurosis 
 of the shoulder, arm, and forearm, the anterior and posterior annular ligaments of 
 the carpus, and the palmar fascia. These will be considered in the description 
 of the muscles of the several regions. 
 
 3. The Acromial Region. 
 Deltoid. 
 
 Deep Fascia. — The deep fascia covering the Deltoid, and known as the deltoid 
 aponeurosis, is a fibrous layer which covers the outer surface of the muscle, thick 
 and strong behind, where it is continuous with the infraspinatus fascia, thinner 
 over the rest of its extent. It sends down numerous prolongations between the 
 fasciculi of the muscle. In front, it is continuous with the fascia covering the 
 great Pectoral muscle; behind, with that covering the Infraspinatus; above, it 
 is attached to the clavicle, the acromion, and spine of the scapula; below, it is 
 continuous with the deep fascia of the arm. 
 
 The Deltoid (m. deltoideus) (Fig. 314) is a large, thick, triangular muscle, which 
 gives the rounded outline to the shoulder, and has received its name from its resem- 
 blance to the Greek letter a reversed. It surrounds the shoulder-joint in the greater 
 part of its extent, covering it on its outer side, and in front and behind. It arises 
 from the outer third of the anterior border and upper surface of the clavicle; from 
 the outer margin and upper surface of the acromion process, and from the lower lip 
 of the posterior border of the spine of the scapula, as far back as the triangular sur- 
 face at its inner end. From this extensive origin the fibres converge toward their 
 insertion, the middle passing vertically, the anterior obliquely backward, the pos- 
 terior obliquely forward; they unite to form a thick tendon, which is inserted into 
 a rough triangular prominence on the middle of the outer side of the shaft of the 
 humerus. At its insertion the muscle gives off an expansion to the deep fascia of 
 the arm. This muscle is remarkably coarse in texture, and the arrangement of 
 its muscular fibres is somewhat peculiar; the central portion of the muscle — that 
 is to say, the part arising from the acromion process — consists of oblique fibres, 
 which arise in a bipenniform manner from the sides of tendinous intersections, 
 generally four in number, which are attached above to the acromion process and 
 pass downward parallel to one another in the substance of the muscle. The 
 
THE ANTERIOR SCAPULAR REGION 471 
 
 oblique muscular fibres thus formed are inserted into similar tendinous intersec- 
 tions, generally three in number, which pass upward from the insertion of the 
 muscle into the humerus and alternate with the descending septa. The portions 
 of the muscle which arise from the clavicle and spine of the scapula are not 
 arranged in this manner, but pass from their origin above, to be inserted into the 
 margins of the inferior tendon. 
 
 Relations. — By its superficial surface, with the integument, the superficial and 
 deep fasciae, Platysma, and supra-acromial nerves. Its deep surface is separated 
 from the head of the humerus by a large sacculated synovial bursa, the subdeltoid 
 bursa (bursa suhdeltoidea) . It often communicates with the subacromial bursa 
 (bursa subacromialis), which is between the acromial process and the coraco- 
 acromial ligament above and the capsule of the shoulder-joint and the Supra- 
 spinatus muscle below. The deep surface of the deltoid covers the coracoid 
 process, coraco-acromial ligament, Pectoralis minor, Coraco-brachialis, both heads 
 of the Biceps, the tendon of the Pectoralis major, the insertions of the Supra- 
 spinatus, Infraspinatus, and Teres minor, the scapular and external heads of the 
 Triceps, the circumflex vessels and nerve, and the humerus. Its anterior border 
 is separated at its upper part from the Pectoralis major by a cellular interspace, 
 which lodges the cephalic vein and humeral branch of the acromial thoracic artery : 
 lower down the two muscles are in close contact. Its posterior border rests on the 
 Infraspinatus and Triceps muscles. 
 
 Nerves. — The Deltoid is supplied by the fifth and sixth cervical through the 
 circumflex nerve. 
 
 Actions. — The Deltoid raises the arm directly from the side, so as to bring it 
 at right angles with the trunk, but this act cannot be performed without the aid 
 of the Serratus magnus, which muscle steadies the lower angle of the scapula. 
 Its anterior fibres, assisted by the Pectoralis major, draw the arm forward; and its 
 posterior fibres, aided by the Teres major and Latissimus dorsi, draw it backward. 
 
 Surgical Anatomy. — The Deltoid is very liable to atrophy, and when in this condition 
 simulates dislocation of the shoulder-joint, as there is flattening of the shoulder and apparent 
 prominence of the acromion process; upon examination, however, it will be found that the 
 relative position of the great tuberosity of the humerus to the acromion and coracoid process is 
 unchanged. Atrophy of the Deltoid may be due to disuse or loss of trophic influence, either 
 from injury to the circumflex nerve or cord lesions, as in infantile paralysis. 
 
 4. The Anterior Scapular Region. 
 
 Subscapularis. 
 
 Dissection. — Divide the Deltoid across, near its upper part, by an incision carried along the 
 margin of the clavicle, the acromion process and spine of the scapula, and reflect it downward, 
 when the structures under cover of it will be seen. 
 
 The Subscapular Fascia {fascia subscapularis). — The subscapular fascia is a 
 thin membrane attached to the entire circumference of the subscapular fossa, and 
 affording attachment by its inner surface to some of the fibres of the Subscapu- 
 laris muscle : when this is removed, the Subscapularis muscle is exposed. 
 
 The Subscapularis (Fig. 315) is a large triangular muscle which fills up the 
 subscapular fossa, arising from its internal two-thirds, with the exception of a 
 narrow margin along the posterior border, and the surfaces at the superior and 
 inferior angles which afford attachment to the Serratus magnus : it also arises from 
 the lower two-thirds of the groove on the axillary border of the bone. Some fibres 
 arise from tendinous laminae, which intersect the muscle, and are attached to ridges 
 on the bone; and others from an aponeurosis, which separates the muscles from the 
 Teres major and the long head of the Triceps. The fibres pass outward, and, 
 gradually converging, terminate in a tendon, which is inserted into the lesser 
 
472 THE MUSCLES AND FASCIA 
 
 tuberosity of the humerus. Those fibres which arise from the axillary border of 
 the scapula are inserted into the neck of the humerus to the extent of an inch below 
 the tuberosity. The tendon of the muscle is in close contact with the anterior part 
 of the capsular ligament of the shoulder-joint, and glides over a large bursa, the- 
 bursa of the subscapularis muscle (bursa m. subscapular is, which separates it from 
 the base of the coracoid process. This bursa communicates with the cavity of the 
 joint by an aperture in the capsular ligament. 
 
 Relations. — Its anterior surface forms a considerable part of the posterior wall 
 of the axilla, and is in relation with the Serratus magnus, Coraco-brachialis, and 
 Biceps, the axillary vessels and brachial plexus of nerves, and the subscapular 
 vessels and nerves. By its posterior surface, with the scapula and the capsular 
 ligament of the shoulder-joint. Its lower border is contiguous with the Teres major 
 and Latissimus dorsi. 
 
 Nerves. — It is supplied by the fifth and sixth cervical nerves through the upper 
 and lower subscapular nerves. 
 
 Actions. — The Subscapularis rotates the head of the humerus inward; when 
 the arm is raised, it draws the humerus forward and downward. It is a powerful 
 defence to the front of the shoulder-joint, preventing displacement of the head of 
 the bone. 
 
 5. The Posterior Scapular Region (Fig. 317). 
 
 Supraspinatus. Teres minor. 
 
 Infraspinatus. Teres major. 
 
 Dissection. — To expose these muscles, and to examine their mode of insertion into the 
 humerus, detach the deltoid and Trapezius from their attachment to the spine of the scapula 
 and acrorfiion process. Remove the clavicle by dividing the ligaments connecting it with the 
 coracoid process, and separate it at its articulation with the scapula: divide the acromion process 
 near its root with a saw. The fragments being removed, the tendons of the posterior Scapular 
 muscles will be fully exposed, and can be examined. A block should be placed beneath the 
 shoulder-joint, so as to make the muscles tense. 
 
 The Supraspinatus Fascia (fascia supraspinata) . — The supraspinatus fascia is 
 a thick and dense membranous layer, which completes the osseo-fibrous case 
 in which the Supraspinatus muscle is contained, affording attachment, by its 
 inner surface, to some of the fibres of the muscle. It is thick internally, but 
 thinner externally under the coraco-acromial ligament. VSTien this fascia is 
 removed, the Supraspinatus muscle is exposed. 
 
 The Supraspinatus Muscle occupies the whole of the supraspinatus fossa, 
 arising from its internal two-thirds and from the strong fascia which covers its sur- 
 face. The muscular fibres converge to a tendon which passes across the upper 
 part of the capsular ligament of the shoulder-joint, to which it is intimately adher- 
 ent, and is inserted into the highest of the three facets on the great tuberosity of 
 the humerus. 
 
 Relations. — By its upper surface, with the Trapezius, the clavicle, the acromion, 
 the coraco-acromial ligament, and the Deltoid; by its under surface, with the 
 scapula, the suprascapular vessels and nerve, and upper part of the shoulder-joint. 
 
 The Infraspinatus Fascia {fascia infraspinata). — The infraspinatus fascia is 
 a dense fibrous membrane, covering in the Infraspinatus muscle and attached 
 to the circumference of the infraspinatus fossa; it affords attachment, by its inner 
 surface, to some fibres of that muscle. At the point where the Infraspinatus 
 commences to be covered by the Deltoid, this fascia divides into two layers: one 
 layer passes over the Deltoid muscle, helping to form the Deltoid fascia already 
 described; the other passes beneath the Deltoid to the capsule of the shoulder-joint. 
 
 The Infraspinatus is a thick, triangular muscle, which occupies the chief part 
 of the infraspinatus fossa, arising by fleshy fibres from its internal two-thirds, and 
 
THE POSTEBIOB SCAPULAR REGION 
 
 473 
 
 by tendinous fibres from the ridges on its surface: it also arises from a strong 
 fascia which covers it externally, and separates it from the Teres major and minor. 
 The fibres converge to a tendon which glides over the external border of the 
 spine of the scapula, and, passing across the posterior part of the capsular ligament 
 of the shoulder-joint, is inserted into the middle facet on the great tuberosity of 
 the humerus. The tendon of this muscle has interposed between it and the joint 
 capsule a synovial bursa, the bursa of the Infraspinatus muscle {bursa m. infra- 
 spinati), Avhich communicates with the synovial cavity of the shoulder-joint. 
 
 Relations. — By its posterior surface, with the Deltoid, the Trapezius, Latissimus 
 dorsi, and the integument; by its anterior surface, with the scapula, from which 
 it is separated by the suprascapular and dorsalis scapulae vessels, and with the 
 
 Fig. 317. — Muscles on the dorsum of the Scapula and the Triceps. 
 
 capsular ligament of the shoulder-joint. Its lower border is in contact with the 
 Teres minor, occasionally united with it, and with the Teres major. 
 
 The Teres Minor is a narrow, elongated muscle, which arises from the dorsal 
 surface of the axillary border of the scapula for the upper two-thirds of its extent, 
 and from two aponeurotic laminae, one of which separates this muscle from the 
 Infraspinatus, the other from the Teres major; its fibres pass obliquely upward 
 and outward, and terminate in a tendon which is inserted into the lowest of the 
 three facets on the great tuberosity of the humerus, and, by fleshy fibres, into the 
 humerus immediately below it. The tendon of this muscle passes across the 
 posterior part of the capsular ligament of the shoulder-joint. 
 
 Relations. — By its posterior surface, with the Deltoid and the integument; 
 by its anterior surface, with the scapula and dorsal branch of the subscapular 
 artery, the long head of the Triceps, and the shoulder-joint; by its upper border, 
 
474 THE MUSCLES AND FASCIAE 
 
 with the Infraspinatus; by its lower border, with the Teres major, from which it 
 is separated anteriorly by the long head of the Triceps. 
 
 The Teres Major is a thick but somewhat flattened muscle, which arises from 
 the oval surface on the dorsal aspect of the inferior angle of the scapula, and from 
 the fibrous septa interposed between it and the Teres minor and Infraspinatus ; the 
 fibres are directed upward and outward, and terminate in a flat tendon, about two 
 inches in length, which is inserted into the inner bicipital ridge of the humerus. 
 The tendon of this muscle, at its insertion into the humerus, lies behind that of the 
 Latissimus dorsi, from which it is separated by a synovial bursa, the bursa of the 
 Latissimus dorsi muscle (bursa m. latissimi dorsi), the two tendons being, however, 
 united along their lower borders for a short distance. Between the tendon of 
 the Teres major and the bone is the bursa m. teretis majoris. 
 
 Relations. — By its posterior surface, with the Latissimus dorsi below, and the 
 long head of the Triceps above. By its anterior surface, with the Subscapularis, 
 Latissimus dorsi, Coraco-brachialis, short head of the Biceps, the axillary vessels, 
 and brachial plexus of nerves. Its upper border is at first in relation with the 
 Teres minor, from which it is afterward separated by the long head of the Triceps. 
 Its lower border forms, in conjunction with the Latissimus dorsi, part of the pos- 
 terior boundary of the axilla. The Latissimus dorsi at first covers the origin of 
 the Teres major, then wraps itself obliquely round its lower border, so that its 
 tendon ultimately comes to lie in front of that of the Teres major. 
 
 Nerves. — ^The Supra- and Infraspinatus muscles are supplied by the fifth and 
 sixth cervical nerves through the suprascapular nerve; the Teres minor, by the 
 fifth cervical, through the circumflex; and the Teres major, by the fifth and sixth 
 cervical, through the lower subscapular. 
 
 Actions. — The Supraspinatus assists the Deltoid in raising the arm from the 
 side, and fixes the head of the humerus in the glenoid cavity. The Infraspinatus 
 and Teres minor rotate the head of the humerus outward : when the arm is raised, 
 they assist in retaining it in that position and carrying it backward. One of the 
 most important uses of these three muscles is the great protection they afford to 
 the shoulder-joint, the Supraspinatus supporting it above, and preventing displace- 
 ment of the head of the humerus upward, while the Infraspinatus and Teres minor 
 protect it behind, and prevent dislocation backward. The Teres major assists the 
 Latissimus dorsi in drawing the humerus downward and backward, when pre- 
 viously raised, and rotating it inward; when the arm is fixed, it may assist the 
 Pectoral and Latissimus dorsi muscles in drawing the trunk forward. 
 
 THE MUSCLES AND FASCIiE OF THE ARM. 
 
 6. The Anterior Humeral Region (Fig. 315). 
 Coraco-brachialis. Biceps. Brachialis anticus. 
 
 Dissection. — The arm being placed on the table, with the front surface uppermost, make 
 a vertical incision through the integument along the middle line, from the clavicle to about 
 two inches below the elbow-joint, where it should be joined by a transverse incision, extending 
 from the inner to the outer side of the forearm; the two flaps being reflected on either side, 
 the fascia should be examined (Fig. 312). 
 
 Deep Fascia (fascia brae hii). — ^The deep fascia of the arm is continuous with 
 that covering the Deltoid and the great Pectoral muscles, by means of which it is 
 attached, above, to the clavicle, acromion, and spine of the scapula, and is also 
 continuous with the axillary fascia. It forms a thin, loose, membranous sheath 
 investing the muscles of the arm, sending down septa between them, and com- 
 posed of fibres disposed in a circular or spiral direction, and connected together 
 by vertical and oblique fibres. It differs in thickness at different parts, being 
 
THE ANTERIOR HUMERAL REGION 475 
 
 thin over the Biceps, but thicker where it covers the Triceps, and over the 
 condyles of the humerus; it is strengthened by fibrous aponeuroses, derived 
 from the PectoraHs major and Latissimus dorsi on the inner side, and from the 
 Deltoid externally. On either side it gives off a strong intermusculax septum, 
 which is attached to the supracondylar ridge and condyle of the humerus. These 
 septa serve to separate the muscles of the anterior from those of the posterior 
 brachial region. The external intermusculax septum (septum intermuscular e 
 laterale) extends from the lower part of the anterior bicipital ridge, along the 
 external supracondylar ridge, to the outer condyle; it is blended with the tendon 
 of the Deltoid, gives attachment to the Triceps behind, to the Brachiailis anticus, 
 Supinator longus, and Extensor carpi radialis longior, in front, and is perforated 
 by the musculo-spiral nerve and superior profunda artery. The internal inter- 
 muscular septum {septum intermuscular e mediale), thicker than the preceding, 
 extends from the lower part of the posterior lip of the bicipital groove below the 
 Teres major, along the internal supracondylar ridge to the inner condyle; it is 
 blended with the tendon of the Coraco-brachialis, and affords attachment to the 
 Triceps behind, and the Brachialis anticus in front. It is perforated by the ulnar 
 nerve and the inferior profunda and anastomotic arteries. At the elbow the deep 
 fascia is attached to all the prominent points round the joint — viz., the condyles of 
 the humerus and the olecranon process of the ulna — and is continuous with the 
 deep fascia of the forearm. Just below the middle of the arm, on its inner side, in 
 front of the intermuscular septum, is an oval opening in the deep fascia which 
 transmits the basilic vein and some lymphatic vessels. On the removal of this 
 fascia the muscles, vessels, and nerves of the anterior humeral region are exposed. 
 
 The Coraco-brachialis, the smallest of the three muscles in this region, is 
 situated at the upper and inner part of the arm. It arises by fleshy fibres from 
 the apex of the coracoid process, in common with the short head of the Biceps, 
 and from the intermuscular septum between the two muscles; the fibres pass 
 downward, backward, and a little outward, to be inserted by means of a flat 
 tendon into an impression at the middle of the inner surface and internal border 
 of the shaft of the humerus between the origins of the Triceps and Brachialis 
 anticus. It is perforated by the musciilo-cutaneous nerve. The inner border of 
 the muscle forms a guide to the position of the brachial artery in tying the vessel 
 in the upper part of its course. Between the tendon of the subscapularis, 
 the coracoid process and the tendon of the Coraco-brachialis, is the bursa of the 
 Coraco-brachialis muscle (bursa m. coracobrachialis). 
 
 Relations. — By its anterior surface, with the Pectoralis major above, and at 
 its insertion with the brachial vessels and median nerve which cross it; by its 
 posterior surface, with the tendons of the Subscapularis, Latissimus dorsi, and 
 Teres major, the inner head of the Triceps, the humerus, and the anterior circum- 
 flex vessels; by its inner border, with the brachial artery, and the median and 
 musculo-cutaneous nerves; by its outer border, with the short head of the Biceps 
 and Brachialis anticus. 
 
 The Biceps or the Biceps Flexor Cubiti (m. biceps brachii) is a long fusiform 
 muscle, occupying the whole of the anterior surface of the arm, and divided above 
 into two portions or heads, from which circumstance it has received its name. The 
 short head (caput breve) arises by a thick flattened tendon from the apex of the cora- 
 coid process, in common with the Coraco-brachialis. The long head (caput longum) 
 arises from the upper margin of the glenoid cavity, and is continuous with the 
 glenoid ligament. This tendon arches over the head of the humerus, being enclosed 
 in a special sheath of the synovial membrane of the shoulder-joint; it then passes 
 through an opening in the capsular ligament at its attachment to the humerus, 
 and descends in the bicipital groove, in which it is retained by a fibrous prolonga- 
 tion from the tendon of the Pectoralis major. Each tendon is succeeded by an 
 
476 THE MUSCLES AND FASCIA 
 
 elongated muscular belly, and the two bellies, although closely applied to each 
 other, can readily be separated until within about three inches of the elbow-joint. 
 Here they end in a flattened tendon, which is inserted into the back part of the 
 tuberosity of the radius, a synovial bursa {bursa bicipito-radialis) , being interposed 
 between the tendon and the front of the tuberosity, and another bursa {bursa 
 cubitalis interossea) is often interposed between the ulna and the tendon. As the 
 tendon of the muscle approaches the radius it becomes twisted upon itself, so that 
 its anterior surface becomes external and is applied to the tuberosity of the 
 radius at its insertion : opposite the bend of the elbow the tendon gives off, from 
 its inner side, a broad aponeurosis, the bicipital or semilunar fascia {lacertus 
 fibrosus), which passes obliquely downward and inward across the brachial 
 artery, and is continuous with the deep fascia of the forearm (Fig. 314). The 
 inner border of this muscle forms a guide to the position of the vessel in tying the 
 brachial artery in the middle of the arm.^ 
 
 Relations. — Its anterior surface is overlapped above by the Pectoralis major 
 and Deltoid; in the rest of its extent it is covered by the superficial and deep 
 fasciae and the integument. Its posterior surface rests above on the shoulder- 
 joint and upper part of the humerus; below it rests on the Brachialis anticus, 
 with the musculo-cutaneous nerve intervening between the two, and on the 
 Supinator brevis. Its inner border is in relation with the Coraco-brachialis, and 
 overlaps the brachial vessels and median nerve; its outer border, with the Deltoid 
 and Supinator longus. 
 
 The Brachialis Anticus (w. brachialis) is a broad muscle, which covers the elbow- 
 joint and the lower half of the front of the humerus. It is somewhat compressed 
 from before backward, and is broader in the middle than at either extremity. It 
 wises from the lower half of the outer and inner surfaces of the shaft of the humerus, 
 and commences above at the insertion of the Deltoid, which it embraces by two 
 angular processes. Its origin extends below, to within an inch of the margin of 
 the articular surface, and is limited on each side by the external and internal 
 borders of the shaft of the humerus. It also arises from the intermuscular septa 
 on each side, but more extensively from the inner than the outer, from which it is 
 separated below by the Supinator longus and Extensor carpi radialis longior. Its 
 fibres converge to a thick tendon, which is inserted into a rough depression on 
 the anterior surface of the coronoid process of the ulna, being received into an 
 interval between two fleshy slips of the Flexor profundus digitorum. 
 
 Relations. — By its anterior surface, with the Biceps, the brachial vessels, mus- 
 culo-cutaneous, and median nerves; by its posterior surface, with the humerus 
 and front of the elbow-joint; by its inner border, with the Triceps, ulnar nerve, 
 and Pronator radii teres, from which it is separated by the intermuscular septum; 
 by its outer border, with the musculo-spiral nerve, radial recurrent artery, the 
 Supinator longus, and Extensor carpi radialis longior. 
 
 Nerves. — The muscles of this group are supplied by the musculo-cutaneous 
 nerve. The Brachialis anticus usually receives an additional filament from the 
 musculo-spiral. The Coraco-brachialis receives its supply primarily from the 
 seventh cervical, the Biceps and Brachialis anticus from the fifth and sixth cer- 
 vical nerves. 
 
 Actions. — The Coraco-brachialis draws the humerus forward and inward, and 
 at the same time assists in elevating it toward the scapula. The Biceps is a flexor 
 of the forearm; it is also a powerful supinator, and serves to render tense the 
 deep fascia of the forearm by means of the broad aponeurosis given off from 
 
 ' A third head to the Biceps is occasionally found (Theile says as often as once in eight or nine subjects), 
 arising at the upper and inner part of the Brachialis anticus, with the fibres of which it is continuous, and inserted 
 into the bicipital fascia and inner side of the tendon of the Biceps. In most cases this additional slip passes 
 behind the brachial artery in its course down the arm. Occasionally the third head con.sists of two slips which 
 pass down, one in front, the other behind the artery, concealing the vessel in the lower half of the arm. 
 
THE POSTERIOR HUMERAL REGION 477 
 
 its tendon. The Brachialis anticus is a flexor of the forearm, and forms an impoi^ 
 tant defence to the elbow-joint. When the forearm is fixed, the Biceps and 
 BrachiaUs anticus flex the arm upon the forearm, as is seen in efforts at climbing. 
 
 7. The Posterior Humeral Region. 
 Triceps. Subanconeus. 
 
 The Triceps or the Triceps Extensor Cubiti (m. trice'ps hrachii) (Fig. 317) is 
 situated on the back of the arm, extending the entire length of the posterior surface 
 of the humerus. It is of large size, and divided above into three parts; hence its 
 name. These three portions have been named (1 ) the middle, scapular, or long head ; 
 (2) the external or long humeral head; and (3) the internal or short humeral head. 
 
 The Middle, Long, or Scapular Head (caput longum) arises, by a flattened tendon, 
 from a rough triangular depression on the scapula, immediately below the glenoid 
 cavity, being blended at its upper part with the capsular ligament; the muscular 
 fibres pass downward between the two other portions of the muscle, and join with 
 them in the common tendon of insertion. 
 
 The External Head {caput laterale) arises from the posterior surface of the shaft 
 of the hinnerus, between the insertion of the Teres minor and the upper part of 
 the musculo-spiral groove; from the external border of the humerus and the 
 external intermuscular septum: the fibres from this origin converge toward the 
 common tendon of insertion. 
 
 The Internal Head {caput mediale) arises from the posterior surface of the shaft 
 of the humerus, below the groove for the musculo-spiral nerve; commencing above, 
 narrow and pointed, below the insertion of the Teres major, and extending to 
 within an inch of the trochlear surface : it also arises from the internal border of 
 the humerus, and from the back of the whole length of the internal and lower part 
 of the external intermuscular septum. The fibres of this portion of the muscle are 
 directed, some downward to the olecranon, whilst others converge to the common 
 tendon of insertion. 
 
 The Common Tendon of the Triceps commences about the middle of the back part 
 of the muscle : it consists of two aponeurotic laminae, one of which is subcutaneous 
 and covers the posterior surface of the muscle for the lower half of its extent; the 
 other is more deeply seated in the substance of the muscle: after receiving the 
 attachment of the muscular fibres, they join together above the elbow, and are 
 inserted, for the most part, into the back part of the upper surface of the olecranon 
 process; a band of fibres is, however, continued downward, on the outer side, 
 over the Anconeus, to blend with the deep fascia of the forearm. A small bursa 
 (bursa suhtendinea olecrani) occasionally multilocular, is situated on the front part 
 of this surface, beneath the tendon. The subcutaneous olecranon bursa (bursa sub- 
 cutanea olecrani) is situated between the olecranon process and the skin. Within 
 the tendon of the triceps is often found the bursa intratendinea olecrani. 
 
 The long head of the Triceps descends between the Teres minor and Teres 
 major, dividing the triangular space between these two muscles and the humerus 
 into two smaller spaces, one triangular, the other quadrangular (Fig. 317). The 
 triangular space contains the dorsalis scapulae vessels; it is bounded by the Teres 
 minor above, the Teres major below, and the scapular head of the Triceps exter- 
 nally: the quadrangular space transmits the posterior circumflex vessels and the 
 circumflex nerve; it is bounded by the Teres minor above, the Teres major below, 
 the scapular head of the Triceps internally, and the humerus externally. 
 
 Relations. — By its posterior surface, with the Deltoid above: in the rest of its 
 extent it is subcutaneous; by its anterior surface, with the humerus, musculo- 
 spiral nerve, superior profunda vessels, and back part of the elbow-joint. Its 
 
478 THE MUSCLES AND FASCIA 
 
 middle or long head is in relation, behind, with the Deltoid and Teres minor; in 
 front, with the Subscapularis, Latissimus dorsi, and Teres major. 
 
 The Subanconeus {m. anconaeus) is a name given to a few fibres from the under 
 surface of the lower part of the Triceps muscle, which are inserted into the posterior 
 ligament of the elbow-joint. By some authors it is regarded as the analogue of 
 the Subcrureus in the lower limb, but it is not a separate muscle. 
 
 Nerves. — The Triceps is supplied by the seventh and eighth cervical nerves 
 through the musculo-spiral nerve. 
 
 Actions. — The Triceps is the great extensor muscle of the forearm, serving, 
 when the forearm is flexed, to extend the elbow-joint. It is the direct antagonist 
 of the Biceps and Brachialis anticus. When the arm is extended the long head 
 of the muscles may assist the Teres major and Latissimus dorsi in drawing the 
 humerus backward and in adducting it to the thorax. The long head of the Tri- 
 ceps protects the under part of the shoulder-joint, and prevents displacement of 
 the head of the humerus downward and backward. The Subanconeus draws 
 up the posterior ligament during extension of the forearm. 
 
 Surgical Anatomy. — The existence of the band of fibres from the Triceps to the fascia of 
 the forearm is of importance in excision of the elbow, and should always be carefully preserved 
 from injury by the operator, as by means of these fibres the patient is enabled to extend the 
 forearm, a movement which would otherwise mainly be accomplished by gravity; that is to say, 
 allowing the forearm to drop from its own weight. 
 
 III. MUSCLES AND FASCI.® OF THE FOREARM. 
 
 Dissection. — To dissect the forearm, place the limb in the position indicated in Fig. 312, 
 make a vertical incision along the middle line from the elbow to the wrist, and a transverse 
 incision at the extremity of this; the superficial structures being removed, the deep fascia of 
 the forearm is exposed. 
 
 Deep Fascia {fascia antibrachii). — ^The deep fascia of the forearm, continuous 
 above with that enclosing the arm, is a dense, highly glistening aponeurotic 
 investment, which forms a general sheath enclosing the muscles in this region; 
 it is attached, behind, to the olecranon and posterior border of the ulna, and gives 
 off from its inner surface numerous intermuscular septa, which enclose each mus- 
 cle separately. Below, it is continuous in front with the anterior annular ligament 
 {ligamentum carpi volar e) , and forms a sheath for the tendon of the Palmaris longus 
 muscle, which passes over the annular ligament to be inserted into the palmar 
 fascia. Behind, near the wrist-joint, it becomes much thickened by the addition 
 of many transverse fibres, and forms the posterior annular ligament {ligamentum 
 carpi dorsale). It consists of circular and oblique fibres, connected together by 
 numerous vertical fibres. It is much thicker on the dorsal than on the palmar sur- 
 face, and at the lower than at the upper part of the forearm, and is strengthened 
 above by tendinous fibres derived from the Brachialis anticus and Biceps in front, 
 and from the Triceps behind. Its deep surface gives origin to muscular fibres, 
 especially at the upper part of the inner and outer sides of the forearm, and forms 
 the boundaries of a series of conical-shaped cavities, in which the muscles are 
 contained. Besides the vertical septa separating each muscle, transverse septa are 
 given off on the anterior and posterior surfaces of the forearm, separating the 
 deep from the superficial layer of muscles. Numerous apertures exist in the fascia 
 for the passage of vessels and nerves; one of these, of large size, situated at the 
 front of the elbow, serves for the passage of a communicating branch between 
 the superficial and deep veins. 
 
 The muscles of the forearm may be subdivided into groups corresponding to 
 the region they occupy. One group occupies the inner and anterior aspect of the 
 forearm, and comprises the Flexor and Pronator muscles. Another group occupies 
 its outer side, and a third its posterior aspect. The two latter groups include all 
 the Extensor and Supinator muscles. 
 
THE ANTERIOR RADIO -ULNAR REGION 479 
 
 8. The Anterior Radio-ulnar Region. 
 
 The muscles in this region are divided for convenience of description into two 
 groups or layers, superficial and deep. 
 
 The Superficial Layer. 
 
 Pronator radii teres. Palmaris longus. 
 
 Flexor carpi radialis. Flexor carpi ulnaris. 
 
 Flexor sublimis digitorum. 
 
 These muscles take origin from the internal condyle of the humerus by a 
 common tendon. 
 
 The Pronator Radii Teres (m. pronator teres) arises by two heads. One, the 
 larger and more superficial, humeral head (caput humerale) , arises from the humerus, 
 immediately above the internal condyle, and from the tendon common to the 
 origin of the other muscles ; also from the fascia of the forearm and the inter- 
 muscular septum between it and the Flexor carpi radialis. The other head, the 
 ulnar head {caput ulnare), is a thin fasciculus which arises from the inner side of 
 the coronoid process of the ulna, joining the preceding at an acute angle. 
 Between the two heads the median nerve enters the forearm. The muscle passes 
 obliquely across the forearm from the inner to the outer side, and terminates in a 
 flat tendon, which turns over the outer margin of the radius, and is inserted into 
 a rough impression at the middle of the outer surface of the shaft of that bone. 
 
 Relations. — By its anterior surface, throughout the greater part of its extent, 
 with the deep fascia; at its insertion it is crossed by the radial vessels and nerve, 
 and is covered by the Supinator longus ; by its posterior surface, with the Brachialis 
 anticus. Flexor sublimis digitorum, the median nerve, and ulnar artery, the small 
 or deep head being interposed })etween the two latter structures. Its outer border 
 forms the inner boundary of a triangular space in which are placed the brachial 
 artery, median nerve, and tendon of the Biceps muscle. Its inner border is in 
 contact with the Flexor carpi radialis. 
 
 Surgical Anatomy. — This muscle, when suddenly brought into very active use, as in the 
 game of lawn tennis, is apt to be strained, producing slight swelling and tenderness, and pain 
 on putting the muscle into action. This is known as lawn-tennis arm. 
 
 The Flexor Carpi Radialis lies on the inner side of the preceding muscle. It 
 arises from the internal condyle by the common tendon, from the fascia of the fore- 
 arm, and from the intermuscular septa between it and the Pronator radii teres, on 
 the outside, the Palmaris longus internally, and the Flexor sublimis digitorum 
 beneath. Slender and aponeurotic in structure at its commencement, it increases 
 in size, and terminates in a tendon which forms rather more than the lower half 
 of its length. This tendon passes through a canal on the outer side of the annular 
 ligament, runs through a groove in the os trapezium (which is converted into a 
 canal by a fibrous sheath, and is lined by a synovial membrane), and is inserted 
 into the base of the metacarpal bone of the index finger, and by a slip into the base 
 of the metacarpal bone of the middle finger. The radial artery lies between the 
 tendon of this muscle and the Supinator longus, and may easily be tied in this 
 situation. In the hand a bursa (bursa m. flexoris carpi radialis) lies between the 
 base of the second metacarpal bone and the tendon (Spalteholz) . 
 
 Relations.— By its superficial surface, with the deep fascia and the integument; 
 by its deep surface, with the Flexor subUmis digitorum. Flexor longus pollicis, 
 and wrist-joint; by its outer border, with, the Pronator radii teres and the radial 
 vessels ; by its inner border, with the Palmaris longus above and the median 
 nerve below. 
 
480 
 
 THE MUSCLES AND FASCIA 
 
 The Palmaris Longus (Fig. 318) is a slender, fusiform muscle lying on the inner 
 side of the preceding. It arises from the inner condyle of the humerus by the com- 
 mon tendon, from the deep fascia, and the inter- 
 muscular septa between it and the adjacent mus- 
 cles. It terminates in a slender flattened tendon, 
 which passes over the upper part of the annular 
 ligament, to end in the central part of the palmar 
 fascia and lower part of the annular ligament, 
 frequently sending a tendinous slip to the short 
 muscles of the thumb. This muscle is often 
 absent, and is subject to very considerable varia- 
 tions; it may be tendinous above and muscular 
 below; or it may be muscular in the centre, with 
 a tendon above and below; or it may present two 
 muscular bundles with a central tendon; or 
 finally it may consist simply of a mere tendinous 
 band. 
 
 Relations. — By its superficial surface, with the 
 deep fascia. By its deep surface, with the Flexor 
 sublimis digitorum. Internally, with the Flexor 
 carpi ulnaris. Externally, with the Flexor carpi 
 radialis. The median nerve lies close to the 
 tendon, just above the wrist, on its inner and 
 posterior side. 
 
 The Flexor Carpi Ulnaris (Fig. 318) lies along 
 the ulnar side of the forearm. It arises by two 
 heads, connected by a tendinous arch, beneath 
 which pass the ulnar nerve and posterior ulnar 
 recurrent artery. One head arises from the inner 
 condyle of the humerus, humeral head {caput 
 humerale) , by the common tendon ; the other from 
 the inner margin of the olecranon and from the 
 upper two-thirds of the posterior border of the 
 ulna, ulnar head (caput ulnare), by an aponeu- 
 rosis, common to it and the Extensor carpi 
 ulnaris and Flexor profundus digitorum; and from 
 the intermuscular septum between it and the 
 Flexor sublimis digitorum. The fibres terminate 
 in a tendon which occupies the anterior part of 
 the lower half of the muscle, and is inserted into 
 the pisiform bone, and is prolonged from this to 
 the fifth metacarpal and unciform bones, by the 
 piso-metacarpal and piso-uncinate ligaments: it is 
 also attached by a few fibres to the annular liga- 
 ment. The ulnar artery lies on the outer side of 
 the tendon of this muscle, in the lower two-thirds 
 of the forearm, the tendon forming a guide in tying the vessel in this situation. 
 A bursa (bursa m. flexoris carpi ulnaris) is placed between the tendon and a 
 part of the pisiform bone. 
 
 Relations. — By its superficial surface, with the deep fascia, with which it is 
 intimately connected for a considerable extent; by its deep surface, with the Flexor 
 sul)limis digitorum, the Flexor profundus digitorum, the Pronator quadratus, and 
 the ulnar vessels and nerve ; by its outer or radial border, with the Palmaris longus 
 above and the ulnar vessels and nerve below. 
 
 Fig. 318. — Front of the left forearm. 
 Superficial muscles. 
 
THE ANTERIOR RADIO- ULNAR REGION 481 
 
 The Flexor Sublimis Digitorum (m. jiexor digitorum suhlimis) (Fig. 318) 
 is placed beneath the preceding muscles, which therefore must be removed 
 in order to bring its attachment into view. It is the largest of the muscles of the 
 superficial layer, and arises by t? iree heads. One head, the humeral head {caput 
 humerale), arises from the internal condyle of the humerus by the common ten- 
 don, from the internal lateral ligament of the elbow-joint, and from the intermus- 
 cular septum common to it and the preceding muscles. The second head, ulnar 
 head (caput ulnar e), arises from the inner side of the coronoid process of the ulna, 
 above the ulnar origin of the Pronator radii teres (Fig. 133, p. 185). The third 
 head, radial head [caput radiate), arises from the oblique line of the radius, extend- 
 ing from the tubercle to the insertion of the Pronator radii teres. The fibres pass 
 vertically downward, forming a broad and thick muscle, which speedily divides into 
 two planes of muscular fibres, superficial and deep: the superficial plane divides 
 into two parts which end in tendons for the middle and ring fingers; the deep 
 plane also divides into two parts, which end in tendons for the index and little 
 fingers, but previously to having done so it gives off a muscular slip, which joins 
 that part of the superficial plane which is intended for the ring finger. As the 
 four tendons thus formed pass beneath the annular ligament into the palm of the 
 hand, they are arranged in pairs, the superficial pair corresponding to the middle 
 and ring fingers, the deep pair to the index and little fingers. The tendons diverge 
 from one another as they pass onward. Opposite the bases of the first phalanges 
 each tendon divides into two slips (chiasma tendinum) to allow of the passage of 
 the corresponding tendon of the Flexor profundus digitorum ; the two portions of 
 the tendon then unite and form a grooved channel for the reception of the accom- 
 panying deep flexor tendon. Finally they subdivide a second time, to be inserted 
 into the sides of the second phalanges 
 about their middle. The insertion in the 
 index finger is shown in Fig. 324. After 
 leaving the palm the tendons of the 
 superficial flexor, accompanied by the deep 
 flexor tendons, lie in osseo-aponeurotic 
 canals (Fig. 320). Each canal or theca 
 extends from the metacarpo-phalangeal 
 articulation to the proximal end of the 
 distal phalanx (Fig. 231). It is formed 
 
 by strong fibrous bands, which arch across Fig- 319. — Section passing through the middle 
 
 ,"' -P , , , 1 • 1 third of the first phalanx of the middle finger (frozen 
 
 the tendons, and are attached on each side section). The tendon of the Flexor subllmis digi- 
 
 , ,1 • i« ii 1 1 /-\ torum is divided into two small bands, which spread 
 
 to the margins Ot the phalanges. OppO- laterally and engage themselves between the osse- 
 
 site the middle of the proximal and second (XrfirTd'charly') ^^'"°'" ^^"^""^^"^ digitorum. 
 phalanges the sheath is very strong, and 
 
 the fibres pass transversely; but opposite the joints it is much thinner, and the 
 fibres pass obUquely. It is very thin over the metacarpo-phalangeal articulation. 
 It is absent over the distal phalanx. Each sheath is lined by a synovial mem- 
 brane, which is reflected on the contained tendons. 
 
 Relations. — In the forearm, by its superficial surface, with the deep fascia and 
 all the preceding superficial muscles; by its deep surface, with the Flexor profundus 
 digitorum. Flexor longus pollicis, the ulnar vessels and nerve, and the median 
 nerve. In the hand its tendons are in relation, in front, with the palmar fascia, 
 superficial palmar arch, and the branches of the median nerve; behind, with the 
 tendons of the deep Flexor and the Lumbricales. 
 
 31 
 
 FLEXOR PROFUNDUS 
 DIGITiORUM 
 SHEATH OF,^ ] /FLEXOR 
 
 flexor\ /'sublimis 
 tendons \^,0- l-^^/ digitorum 
 /^^ -,^-^v digital 
 
 ff^L'^ fr''Jh^Xi'' *''TERIES 
 /./^"'•'iOiJ^^MJMl *'*" NERVES 
 
 
 kjwb^J 
 
 
 
 \^ps/. 
 
 COMMON TENDON OF 
 'extensor MUSCLE 
 OF FINGERS 
 
 
 FIRST PHALANX 
 
 
482 THE MUSCLES AND FASCIA 
 
 The Deep Layer (Fig. 320). 
 
 Flexor profundus digitorum. Flexor longus polllcis. 
 
 Pronator quadratus. 
 
 Dissection. — Divide each of the superficial muscles at its centre, and turn either end aside; 
 the deep layer of muscles, together with the median nerve and ulnar vessels, will then be exposed. 
 
 The Flexor Profundus Digitorum (m. flexor digitorum profundiis) (Fig. 320) 
 is situated on the ulnar side of the forearm, immediately beneath the superficial 
 Flexors. It arises from the upper three-fourths of the anterior and inner 
 surfaces of the shaft of the ulna, embracing the insertion of the Brachialis anticus 
 above, and extending, below, to within a short distance of the Pronator quadratus. 
 It also arises from a depression on the inner side of the coronoid process; by an apo- 
 neurosis from the upper three-fourths of the posterior border of the ulna, in common 
 with the Flexor and Extensor carpi ulnaris; and from the ulnar half of the inter- 
 osseous membrane. The fibres form a fleshy belly of considerable size, which divides 
 into four tendons : these pass under the annular ligament beneath the tendons of the 
 Flexor sublimis digitorum. Opposite the first phalanges the tendons pass through 
 the openings in the two slips of the tendons of the Flexor sublimis digitorum, and 
 are finally inserted into the bases of the last phalanges. The portion of the muscle 
 for the index finger (Fig. 324) is usually distinct throughout, but the tendons for 
 the three inner fingers are connected together by cellular tissue and tendinous slips 
 as far as the palm of the hand. The tendons of this muscle and those of the Flexor 
 sublimis digitorum, whilst contained in the osseo-aponeurotic canals of the fingers, 
 are invested in a synovial sheath, and are connected to each other and to the 
 phalanges by slender tendinous filaments, called vincula accessoria tendinum (vin~ 
 culum tendinum). One of these connects the deep tendon to the bone before it 
 passes through the superficial tendon ; a second connects the two tendons together, 
 after the deep tendons have passed through; and a third connects the deep ten- 
 don to the head of the second phalanx. This last consists largely of yellow elastic 
 tissue, and may assist in drawing down the tendon after flexion of the finger.^ 
 
 Four small muscles, the Lumbricales, are connected with the tendons of the Flexor 
 profundus in the palm. They will be described with the muscles in that region. 
 
 Relations. — By its superficial surface, in the forearm, with the Flexor sublimis 
 digitorum, the Flexor carpi ulnaris, the ulnar vessels and nerve, and the median 
 nerve; and in the hand, with the tendons of the superficial Flexor; by its deep 
 surface, in the forearm, with the ulna, the interosseous membrane, the Pronator 
 quadratus; and in the hand, with the Interossei, Adductor pollicis, and deep 
 palmar arch; by its ulnar border, with the Flexor carpi ulnaris; by its radial border, 
 with the Flexor longus pollicis, the anterior interosseous vessels and nerve being 
 interposed. 
 
 The Flexor Longus Pollicis (m. flexor pollicis longus) (Fig. 320) is situated on 
 the radial side of the forearm, lying on the same plane as the preceding. It arises 
 from the grooved anterior surface of the shaft of the radius, commencing above, 
 immediately below the tuberosity and oblique line, and extending below to within 
 a short distance of the Pronator quadratus. It also arises from the adjacent part 
 of the interosseous membrane and generally by a fleshy slip from the inner border 
 of the coronoid process or from the internal condyle of the humerus. The fibres 
 pass downward, and terminate in a flattened tendon which passes beneath the 
 annular ligament, is then lodged in the interspace between the outer head of the 
 Flexor brevis pollicis and the Adductor obliquus polHcis, and, entering an osseo- 
 aponeurotic canal similar to those for the other flexor tendons, is inserted into the 
 base of the last phalanx of the thumb. 
 
 1 Marshall, Brit, and For. Med -Chir. Rev., 1853. 
 
THE ANTERIOR RADIO- ULNAR REGION 
 
 483 
 
 Relations. — By its superficial sur- 
 face, with the Flexor suhlimis digi- 
 torum, Flexor carpi radialis, Supi- 
 nator longus, and radial vessels; by 
 its deep surface, with the radius, 
 interosseous membrane, and Pro- 
 nator quadratus ; by its ulnar border, 
 with the Flexor profundus digitorum, 
 from which it is separated by the 
 anterior interosseous vessels and 
 nerve. 
 
 The Pronator Quadratus (Figs. 
 320 and 329) is a small, flat, quadri- 
 lateral muscle, extendingtransversely 
 across the front of the radius and 
 ulna, above their carpal extremities. 
 It arises from the oblique or pronator 
 ridge on the lower part of the ante- 
 rior surface of the shaft of the ulna; 
 from the lower fourth of the anterior 
 surface and the anterior border of 
 the ulna; and from a strong aponeu- 
 rosis which covers the inner third of 
 the muscle. The fibres pass out- 
 ward and slightly downward, to be 
 inserted into the lower fourth of the 
 anterior surface and anterior border 
 of the shaft of the radius. 
 
 Relations. — By its superficial sur- 
 face, with the Flexor profundus digi- 
 torum, the Flexor longus polhcis, 
 Flexor carpi radialis, and the radial 
 vessels; by its deep surface, with the 
 radius, ulna, and interosseous mem- 
 brane. 
 
 Nerves. — All the muscles of the 
 superficial layer are supplied by the 
 median nerve, excepting the Flexor 
 carpi ulnaris, which is supplied by the 
 ulnar nerve. The Pronator radii teres 
 and the Flexor carpi radialis derive 
 their supply primarily from the sixth 
 cervical; the Pahnaris longus from 
 the eighth cervical; the Flexor sub- 
 limis digitorum from the seventh and 
 eighth cervical and first dorsal, and 
 the Flexor carpi ulnaris from the 
 eighth cervical and first dorsal nerves. 
 Of the deep layer, the Flexor pro- 
 fundus digitorum is supplied by the 
 eighth cervical and first dorsal 
 through the ulnar and anterior in- 
 terosseous branch of the median. 
 The remaining two muscles, the 
 
 Fro. 320. — Front of the left forearm. Deep muscles. 
 
484 THE MUSCLES AND FASCIA 
 
 Flexor longus pollicis and Pronator quadratus, are also supplied by the eighth 
 cervical and first dorsal through the anterior interosseous branch of the median. 
 Actions. — These muscles act upon the forearm, the wrist, and hand. The 
 Pronator radii teres helps to rotate the radius upon the ulna, rendering the hand 
 prone: when the radius is fixed it assists the other muscles in flexing the forearm. 
 The Flexor carpi radialis is one of the flexors of the wrist; when acting alone it 
 flexes the wrist, inclining it to the radial side. It can also assist in pronating the 
 forearm and hand, and, by continuing its action, in bending the elbow. The Flexor 
 carpi ulnaris is one of the flexors of the wrist : when acting alone it flexes the wrist, 
 inclining it to the ulnar side (adducts the wrist), and, by continuing to contract, 
 it bends the elbow. The Palmaris longus is a tensor of the palmar fascia, and 
 tension of this fascia protects the parts beneath it. It also assists in flexing the 
 wrist and elbow. The Flexor sublimis digitorum flexes the middle phalanx and 
 then assists in flexing the wrist and elbow. The Flexor profundus digitorum is 
 the flexor of the distal phalanx. After the Flexor sublimis has bent the second 
 phalanx, the Flexor profundus flexes the terminal one, but it cannot do so until 
 after the contraction of the superficial muscle. After flexing the distal phalanx, 
 it assists in flexing the middle phalanx, the proximal phalanx, and the wrist. The 
 Flexor longus pollicis is the flexor of the distal phalanx of the thumb. When the 
 thumb is fixed it also assists in flexing the wrist. The Pronator quadratus helps 
 to rotate the radius upon the ulna, rendering the hand prone. 
 
 Surgical Anatomy. — -When a finger is amputated so that the fibrous sheath of the flexor ten- 
 dons is divided in a region in which it is firm and dense, the tendon contracts but the theca does 
 not, and the rigid theca constitutes a permeable passage to the palm. If the parts should be 
 infected the theca will draw pus toward the palm. Hence it is best to close the theca by sutures. 
 "Over the terminal phalanx, and over the joint between the middle and terminal phalanges, 
 there is no fibrous sheath. In front of the metacarpo-phalangeal joint it is scarcely evident. 
 Over the first and second (proximal and middle) phalanges, and in front of the joint between 
 these bones, the fibrous sheath is well marked, and appears as a rigid tube when cut across. 
 As the sheath crosses the metacarpo-phalangeal and first interphalangeal joints, it is adherent 
 to the glenoid ligament, and is easily closed by two fine catgut sutures passed vertically — i- e., 
 from the dorsal to the palmar wall. Opposite the shafts of the first and second phalanges, 
 however, there is much difficulty in effecting closure, since the sheath is united to the periosteum, 
 and that membrane is very thin. In these situations the periosteum should be stripped up a 
 little from the palmar aspect of the bone, and the orifice of the tube secured by two fine sutures 
 passed either vertically or transversely, as may appear the more convenient. This stripping 
 off of periosteum should be effected before the bone is divided. "• 
 
 9. The Radial Region (Figs. 318, 321, 322). 
 
 Supinator longus. Extensor carpi radialis longior. 
 
 Extensor carpi radialis brevior. 
 
 Dissection. — Divide the integument in the same manner as in the dissection of the anterior 
 brachial region, and, after having examined the cutaneous vessels and nerves and deep fascia, 
 remove all those structures. The muscles will then be exposed. The removal of the fascia 
 will be considerably facilitated by detaching it from below upward. Great care should be 
 taken to avoid cutting across the tendons of the muscles of the thumb, which cross obliquely 
 the larger tendons running down the back of the radius. 
 
 The Supinator Longus (m. brachioradialis) (Fig. 318) is the most superficial 
 muscle on the radial side of the forearm ; it is fleshy for the upper two-thirds of 
 its extent, tendinous below. It arises from the upper two-thirds of the external 
 supracondylar ridge of the humerus, and from the external intermuscular septum, 
 being limited above by the musculo-spiral groove. The fibres terminate above 
 the middle of the forearm in a flat tendon, which is inserted into the outer side 
 of the base of the styloid process of the radius. 
 
 ^ Operative Surgery. By Sir Frederick Treves. 
 
THE RADIAL REGION 
 
 485 
 
 Relations. — By its superficial sur- 
 face, with the integument and fascia 
 for the greater part of its extent ; near 
 its insertion it is crossed by the Ex- 
 tensor ossis metacarpi polKcis and the 
 Extensor brevis polhcis; by its deep 
 surface, with the humerus, the Ex- 
 tensor carpi radiahs longior and bre- 
 vior, the insertion of the Pronator 
 radii teres, and the Supinator brevis; 
 by its inner border, above the elbow, 
 with the BrachiaHs anticus, the mus- 
 culo-spiral nerve, and the radial recur- 
 rent artery; and in the forearm with 
 the radial vessels and nerve. 
 
 The Extensor Carpi Radialis 
 Longior (m. extensor carpi radialis 
 loncjus) (Fig. 321) is placed partly 
 beneath the preceding muscle. It 
 arises from the lower third of the ex- 
 ternal supracondylar ridge of the 
 humerus, and from the external in- 
 termuscular septum by a few fibres 
 from the common tendon of origin of 
 the Extensor muscles of the forearm. 
 The fibres terminate at the upper third 
 of the forearm in a flat tendon, which 
 runs along the outer border of the 
 radius, beneath the extensor tendons 
 of the thumb; it then passes through 
 a groove common to it and the Ex- 
 tensor carpi radialis brevior, immedi- 
 ately behind the styloid process, and 
 is inserted into the base of the meta- 
 carpal bone of the index finger, on 
 its radial side. 
 
 Relations. — By its superficial sur- 
 face, with the Supinator longus and 
 fascia of the forearm; its outer side 
 is crossed obliquely by the extensor 
 tendons of the thumb; by its deep 
 surface, with the elbow-joint, the 
 Extensor carpi radialis brevior, and 
 back part of the wrist. 
 
 The Extensor Carpi Radialis 
 Brevior (m, extensor carpi radialis 
 brevis) (Fig. 321) is shorter, as its 
 name implies, and thicker than the 
 preceding muscle, beneath which it is 
 placed. It arises from the external 
 condyle of the humerus by a tendon 
 common to it and the three following 
 muscles ; from the external lateral 
 ligament of the elbow-joint, from a 
 strong aponeurosis which covers its 
 
 Fig. 321. 
 
 -Posterior surface of the forearm, 
 muscles. 
 
 Superficial 
 
486 THE MUSCLES AND FASCIAE 
 
 surface, and from the intermuscular septa between it and the adjacent muscles. 
 The fibres terminate about the middle of the forearm in a flat tendon which is 
 closely connected with that of the preceding muscle, and accompanies it to the 
 wrist, lying in the same groove on the posterior surface of the radius ; it passes 
 beneath the extensor tendons of the thumb, then beneath the annular ligament, 
 and, diverging somewhat from its fellow, is inserted into the base of the meta- 
 carpal bone of the middle finger, on its radial side. There is often a bursa 
 {bursa m. extensoris carpi radialis brevis) between a portion of the base of the 
 bone and the tendon. 
 
 The tendons of the two preceding muscles pass through the same compartment 
 of the annular ligament, and are lubricated by a single synovial membrane, but are 
 separated from each other by a small vertical ridge of bone as they lie in the groove 
 at the back of the radius. 
 
 Relations. — By its superficial surface, with the Extensor carpi radialis longior, 
 and with the Extensor muscles of the thumb which cross it; by its deep surface, 
 with the Supinator brevis, tendon of the Pronator radii teres, radius, and wrist- 
 joint; by its ulnar border, with the Extensor communis digitorum. 
 
 10. The Posterior Radio-ulnar Region (Fig. 321). 
 
 The muscles in this region are divided for purposes of description into two 
 groups or layers, superficial and deep. 
 
 The Superficial Layer. 
 
 Extensor communis digitorum. Extensor carpi ulnaris. 
 
 Extensor minimi digiti. Anconeus. 
 
 The Extensor Communis Digitorum (m. extensor digitorum communis) is 
 situated at the back part of the forearm. It arises from the external condyle of 
 the humerus by the common tendon, from the deep fascia, and the intermus- 
 cular septa between it and the adjacent muscles. Just below the middle of 
 the forearm it divides into three fleshy masses, from which tendons proceed; 
 these pass, together with the Extensor indicis, through a separate compartment 
 of the annular ligament, lubricated by a synovial membrane. The tendons 
 then diverge, the innermost one dividing into two; and all, after passing across the 
 back of the hand, are inserted into the second and third phalanges of the fingers in 
 the following manner: the outermost tendon, accompanied by the Extensor indicis, 
 goes to the index finger (Figs. 321, 323, and 324) ; the second tendon is sometimes 
 connected to the first by a thin transverse band, and receives a slip from the third 
 tendon (Fig. 321); it goes to the middle finger; the third tendon gives off the slip 
 to the second (Fig. 321), and receives a very considerable part of the fourth tendon; 
 the fourth, or innermost tendon, divides into two parts: one goes to join the third 
 tendon; the other, reinforced by the Extensor minimi digiti, goes to the little 
 finger. Each tendon opposite the metacarpo-phalangeal articulation becomes 
 narrow and thickened, and gives off a thin fasciculus upon each side of the joint, 
 which blends with the lateral ligaments and serves as the posterior ligament; 
 after having passed the joint it spreads out into a broad aponeurosis, which covers 
 the whole of the dorsal surface of the first phalanx, being reinforced, in this 
 situation, by the tendons of the Interossei and Lumbricales. Opposite the first 
 phalangeal joint. this aponeurosis divides into three slips, a middle and two 
 lateral: the former is inserted into the base of the second phalanx; and the two 
 lateral, which are continued onward along the sides of the second phalanx, unite 
 by their contiguous margins, and are inserted into the dorsal surface of the last 
 phalanx. As the tendons cross the phalangeal joints they furnish them with pos- 
 terior ligaments. The accessory slips or lateral vincula which join the tendon 
 
THE POSTERIOR RADIO- ULNAR REGION 437 
 
 of the ring finger to the tendon of the little finger and the tendon of the middle 
 finger are constant. If the middle and little fingers are held flexed the lateral 
 vincula greatly limit the range of extension possible in the ring finger — a limi- 
 tation which interferes with a piano-player (Prof. William S. Forbes). 
 
 Relations. — By its superficial surface, with the fascia of the forearm and hand, 
 the posterior annular ligament, and integument; by its deep surface, with the 
 Supinator brevis, the Extensor muscles of the thumb and index finger, the pos- 
 terior interosseous vessels and nerve, the wrist-joint, carpus, metacarpus, and 
 phalanges; by its radial border, with the Extensor carpi radialis brevior; by its 
 ulnar border, with the Extensor minimi digiti and Extensor carpi ulnaris. 
 
 The Extensor Minimi Digiti (m. extensor digiti quinti proprius) is a slender 
 muscle placed on the inner side of the Extensor communis, with which it is gen- 
 erally connected. It arises from the common tendon by a thin, tendinous slip, and 
 from the intermuscular septa between it and the adjacent muscles. Its tendon 
 runs through a separate compartment in the annular ligament behind the inferior 
 radio-ulnar joint, then divides into two as it crosses the hand, the outermost 
 division being joined by the slip from the innermost tendon of the common exten- 
 sor. The two slips thus formed spread into a broad aponeurosis, which after 
 receiving a slip from the Abductor minimi digiti is inserted into the second and 
 third phalanges. The tendon is situated on the ulnar side of, and somewhat more 
 superficial than, the common extensor. 
 
 The Extensor Carpi Ulnaris is the most superficial muscle on the ulnar side of 
 the forearm. It arises from the external condyle of the humerus by the common 
 tendon; by an aponeurosis from the posterior border of the ulna in common 
 with the Flexor carpi ulnaris and the Flexor profundus digitorum; and from the 
 deep fascia of the forearm. This muscle terminates in a tendon which runs 
 through a groove behind the styloid process of the ulna, passes through a separate 
 compartment in the annular ligament, and is inserted into the prominent tubercle 
 on the ulnar side of the base of the metacarpal bone of the little finger. 
 
 Relations. — By its superficial surface, with the deep fascia of the forearm; by 
 its deep surface, with the ulna and the muscles of the deep layer. 
 
 The Anconeus {m. anconceus) is a small triangular muscle placed behind and 
 below the elbow-joint, and appears to be a continuation of the external portion of 
 the Triceps. It arises by a separate tendon from the back part of the outer condyle 
 of the humerus, and is inserted into the side of the olecranon and upper fourth of 
 the posterior surface of the shaft of the ulna; its fibres diverge from their origin, 
 the upper ones being directed transversely, the lower obliquely inward. 
 
 Relations. — By its superficial surface, with a strong fascia derived from the 
 Triceps; by its deep surface, with the elbow-joint, the orbicular ligament, the 
 ulna, and a small portion of the Supinator brevis. 
 
 The Deep Layer (Fig. 323). 
 
 Supinator radii brevis. Extensor brevis pollicis. 
 
 Extensor ossis metacarpi pollicis. Extensor longus pollicis. 
 
 Extensor indicis. 
 
 The Supinator Radii Brevis (w. supinator) (Figs. 322 and 323) is a broad muscle, 
 of hollow cylindrical form, curved round the upper third of the radius. It consists of 
 two distinct planes of muscular fibres, between which lies the posterior interosseous 
 nerve (Fig. 322). The two planes arise in common : the superficial one by tendin- 
 ous, and the deeper by muscular, fibres from the external condyle of the humerus; 
 from the external lateral ligament of the elbow-joint and the orbicular ligament of 
 the radius; from the ridge on the ulna, which runs obliquely downward from the 
 
488 
 
 THE MUSCLES AND FASCIjE 
 
 posterior extremity of the lesser sigmoid cavity; from the triangular depression in 
 front of it; and from a tendinous expansion which covers the surface of the muscle. 
 
 Int. 
 Condyle. 
 
 Coronoid 
 proc. 
 
 Head of 
 radius. 
 
 TENDON OF.\^ 
 BICEPS 
 
 Olecranon. 
 
 Fig. 322. — Supinator brevis. (From a prepa- 
 ration in the Museum of the Royal College of 
 Surgeons of England.) 
 
 The superficial fibres surround the 
 upper part of the radius, and are in- 
 serted intothe outer edge of the bicip- 
 ital tuberosity and into the oblique 
 line of the radius, as low down as the 
 insertion of the Pronator radii teres. 
 The upper fibres of the deeper plane 
 form a sling-like fasciculus, which 
 encircles the neck of the radius 
 above the tuberosity and is at- 
 tached to the back part of its inner 
 surface : the greater part of this por- 
 tion of the muscle is inserted into 
 the posterior and external surface 
 of the shaft, midway between the 
 oblique line and the head of the 
 
 Fig. 323. — Posterior surface of the forearm. Deep muscles. 
 
 - - bone. Between the insertion of the two 
 
 planes the posterior interosseous nerve lies on the shaft of the bone (Fig. 322). 
 
THE POSTERIOR RADIO- ULNAR REGION 
 
 489 
 
 Relations. — By its superficial surface, with the superficial Extensor and Supina- 
 tor muscles, and the radial vessels and nerve; by its deep surface, w^ith the elbow- 
 joint, the interosseous membrane, and the radius. 
 
 The Extensor Ossis Metacarpi PoUicis (m. abductor pollicis longus) is the most 
 external and the largest of the deep extensor muscles: it lies immediately below 
 the Supinator brevis, with which it is sometimes united. It arises from the outer 
 part of the posterior surface of the shaft of the ulna below the insertion of the 
 Anconeus, from the interosseous membrane, and from the middle third of the 
 posterior surface of the shaft of the radius. Passing obliquely downward and 
 outward, it terminates in a tendon which runs through a groove on the outer side 
 of the styloid process of the radius, accompanied by the tendon of the Extensor 
 brevis pollicis, and is inserted into the base of the metacarpal bone of the thumb. 
 It occasionally gives oft' two slips near its insertion — one to the Trapezium, and the 
 other to blend with the origin of the Abductor pollicis. 
 
 Relations. — By its superficial surface, with the Extensor communis digitorum, 
 Extensor minimi digiti, and fascia of the forearm, and with the branches of the 
 posterior interosseous artery and nerve which cross it; by its deep surface, with 
 the ulna, interosseous membrane, radius, the tendons of the Extensor carpi radialis 
 longior and brevior, which it crosses obliquely, and, at the outer side of the wrist, 
 with the radial vessels; by its upper border, with the Supinator brevis; by its 
 loiver border, with the Extensor brevis pollicis. 
 
 The Extensor Brevis Pollicis, often called the extensor primi intemodii pollicis 
 (m. extensor pollicis brevis), the smallest muscle of this group, lies on the inner 
 side of the preceding. It arises from the posterior surface of the shaft of the radius, 
 below the Extensor ossis metacarpi 
 pollicis, and from the interosseous 
 membrane. Its direction is similar to 
 that of the Extensor ossis metacarpi 
 poUicis, its tendon passing through the 
 same groove on the outer side of the 
 styloid process, to be inserted into the 
 base of the first phalanx of the thumb. 
 
 Relations. — The same as those of 
 the Extensor ossis metacarpi pollicis. 
 
 The Extensor Longus Pollicis, 
 often called the extensor secundi inter- 
 nodii pollicis {m. extensor pollicis longus) 
 is much larger than the preceding 
 muscle, the origin of which it partly 
 covers in. It arises from the outer 
 part of the posterior surface of the 
 shaft of the ulna, below the origin of 
 the Extensor ossis metacarpi pollicis, 
 and from the interosseous membrane. 
 It terminates in a tendon which passes 
 through a separate compartment in 
 the annular ligament, lying in a nar- 
 row, oblique groove at the back part 
 
 of the lower end of the radius. It then crosses obliquely the tendons of the 
 Extensor carpi radialis longior and brevior, being separated from the other 
 extensor tendons of the thumb by a triangular interval, in which the radial artery 
 is found, and is finally inserted into the base of the last phalanx of the thumb. 
 
 Relations. — By its superficial surface, with the same parts as the Extensor ossis 
 metacarpi pollicis ; by its deep surface, with the ulna, interosseous membrane, the 
 
 LICAMENTUM 
 BREVIS 
 
 LICAMENTUM 
 LONGUS 
 
 LIGAMtNTUM BREVIS 
 
 FLEXOR SUBLIMIS 
 DIGITORUM 
 EXPANSION OF 
 EXTENSOR TENDON 
 FLEXOR PROFUNDUS 
 TORUM 
 
 ST LUM8RICAL 
 MUSCLE 
 
 FIRST DORSAL 
 INTEROSSEOUS 
 SOLE 
 
 XTENSOR INDICiS 
 TENDON 
 
 EXTENSOR COMMUNIS 
 DIGITORUM TENDON 
 
 Fig. 324.- 
 
 -The tendons attached to the index finger. 
 (Cunningham. ) 
 
490 THE MUSCLES AND FASCIAE 
 
 posterior interosseous nerve, radius, the wrist, the radial vessels, and metacarpal 
 bone of the thumb. 
 
 The Extensor Indicis (m. extensor indicis proprius) (Figs. 321, 323, and 324) is 
 a narrow, elongated muscle placed on the inner side of, and parallel with, the 
 preceding. It arises from the posterior surface of the shaft of the ulna, below 
 the origin of the Extensor longus poUicis and from the interosseous membrane. 
 Its tendon passes with the Extensor communis digitorum through the same canal 
 in the annular ligament, and subsequently joins the tendon of the Extensor 
 communis which belongs to the index finger, opposite the lower end of the 
 corresponding metacarpal bone, lying to the ulnar side of the tendon from the 
 common extensor. 
 
 Relations. — ^The relations are similar to those of the preceding muscles. 
 
 Nerves. — The Supinator longus is supplied by the sixth, the Extensor carpi 
 radialis longior by the sixth and seventh, and the Anconeus by the seventh and 
 eighth cervical nerves, all through the musculo-spiral nerve; the remaining muscles 
 of the radial and posterior brachial region are supplied through the posterior 
 interosseous nerve, the Supinator brevis being supplied by the sixth cervical, the 
 Extensor carpi radialis brevior by the sixth and seventh cervical, and all the other 
 muscles by the seventh cervical. 
 
 Actions. — The muscles of the radial and posterior brachial regions, which 
 comprise all the extensor and supinator muscles, act upon the forearm, wrist, and 
 hand; they are the direct antagonists of the pronator and flexor muscles. The 
 Anconeus assists the Triceps in extending the forearm. The chief action of the 
 Supinator longus is that of a flexor of the elbow-joint, but in addition to this it 
 may act both as a supinator or a pronator; that is to say, if the forearm is forcibly 
 pronated it will act as a supinator, and bring the bones into a position midway 
 between supination and pronation; and vice versa, if the arm is forcibly supinated, 
 it will act as a pronator, and bring the bones into the same position, midway 
 between supination and pronation. The action of the muscle is therefore to throw 
 the forearm and hand into the position they naturally occcupy when placed across 
 the chest. The Supinator brevis is a supinator; that is to say, when the radius 
 has been carried across the ulna in pronation and the back of the hand is directed 
 forward, this muscle carries the radius back again to its normal position on the 
 outer side of the ulna, and the palm of the hand is again directed forward. The 
 Extensor carpi radialis longior extends the wrist and abducts the hand. It may 
 also assist in bending the elbow-joint; at all events, it serves to fix or steady this 
 articulation. The Extensor carpi radialis brevior assists the Extensor carpi 
 radialis longior in extending the wrist, and may also act slightly as an abductor of 
 the hand. The Extensor carpi ulnaris helps to extend the hand, but when acting 
 alone inclines it toward the ulnar side; by its continued action it extends the 
 elbow-joint. The Extensor communis digitorum extends the phalanges, then the 
 wrist, and finally the elbow. It acts principally on the proximal phalanges, the 
 middle and terminal phalanges being extended by the Interossei and Lumbri- 
 cales. It has also a tendency to separate the fingers as it extends them. The 
 Extensor minimi digiti extends similarly the little finger, and by its continued 
 action it assists in extending the wrist. It is owing to this muscle that the little 
 finger can be extended or pointed whilst the others are flexed. The chief action of 
 the Extensor ossis metacarpi pollicis is to carry the thumb outward and backward 
 from the palm of the hand, and hence it has been called the abductor pollicis longus. 
 By its continued action it helps to extend and abduct the wrist. The Extensor 
 brevis pollicis extends the proximal phalanx of the thumb. By its continued 
 action it helps to extend and abduct the wrist. The Extensor longus pollicis 
 extends the terminal phalanx of the thumb. By its continued action it helps to 
 extend and abduct the wrist. The Extensor indicis extends the index finger, and 
 
OF THE HAND 49I 
 
 by its continued action assists in extending the wrist. It is owing to this muscle 
 that the intlex finger can be extended or pointed while the others are flexed. 
 
 Surgical Anatomy. — The tendons of the extensor muscles of the thumb are liable to become 
 strained and their sheaths inflamed after excessive exercise, producing a sausage-shaped swell- 
 ing along the course of the tendon, and giving a peculiar creaking sensation to the finger when 
 the muscle acts. In consequence of its often being caused by such movements as wringing 
 clothes, it is known as washerwoman^ s sprain. In piano-players the slips which join the ten- 
 dons of the Extensor communis digitorum may limit freedom of motion in individual fingers. 
 " When the middle finger and little finger of the hand are brought down by the flexor muscles, 
 and their balls are held down firmly against the keys of a musical instrument, as in perform- 
 ing on a piano for the purjxjse of producing continuous sounds, and when at the same time 
 it is necessary to extend and then to flex the ring-finger in order to produce accompanying 
 sounds, it will be found that in the still-flexed position of the middle and little fingers, the 
 ring finger can be but very slightly extended. Its complete extension, without operative mter- 
 ference, can only be brought about by long-continued exertion in practice, when elongation 
 of certain accessory, but restricting, tendons is made by nutritive growth."' If there is much 
 limitation division of the hindering slips is proper. This was suggested by Prof. William S. 
 Forbes in 1857. 
 
 IV. MUSCLES AND FASGIiE OF THE HAND. 
 
 The muscles of the hand are subdivided into tliree groups: 1. Those of the 
 thumb, which occupy the radial side and produce the thenar eminence. 2. Those 
 of the little finger, which occupy the ulnar side and give rise to the hsrpothenar 
 eminence. 3. Those in the middle of the palm and within the interosseous spaces. 
 
 Dissection (Fig. 312). — Make a transverse incision across the front of the wrist, and a 
 second across the heads of the metacarpal bones: connect the two by a vertical incision in the 
 middle line, and continue it through the centre of the middle finger. The anterior and poste- 
 rior annular ligaments and the palmar fascia should then be dissfected. 
 
 ANTERIOR 
 ANNULAR 
 LIGAMENT, 
 
 FLEXOR LONGus poLLicis. / Median nerve. 
 
 FLEXOR CARPI RADiALis. \ I I .Ulnar vessels. 
 
 MUSCLES OF THUMB.^ \ \ / / / fPALMARIS BREVrS. 
 
 MUSCLES OF 
 ^^^^^^^^ _ ^y LITTLE 
 
 1st MetacarmlXi<lMB^''i^^B^^^^h--'-^~^~^-':^iiS)/f^^^^k^^Fi n g e r. 
 
 EXT. PRIM 
 INTERNOO 
 
 POLL. _ _ _ 
 
 EXT. CARPI 
 
 EXT. SEC. >i^:^^»>,^rN i.tiTJ^^: Sill ■J'Jmry^'jf'.^ i-A^f&Hi.i'v^'y^AV/'^ ulnaris. 
 
 INTERNOD. 
 POLL. 
 
 Trapezium." /^'^^^^!>?tf.5ji| W '^^'V-X'r*'s."%^^^^i^'<TENSOR 
 Radial vessels. / ^"^'^^^^^^^^L^fj^^^^^^^ digiti. 
 
 EXT. CARP. RAD. LONG. X^^^^^^^^^^^^'^v EXTENSOR 
 
 Trapezoid. /7 T~^ ^ ^communis 
 
 / / I digitorum. 
 
 EXTENSOR carpi RADIALIs/ / EXTENSOR INDICIS. 
 
 BREVIOR 
 
 Os magnum. 
 
 Fig. 325. — Transverse section through the carpus, showing the relative positions of the tendons, vessels, 
 
 and nerves. (Henle.) 
 
 The Ligamentum Carpi Volare is a thickening of the deep fascia of the forearm 
 (fascia antibrachii) by deep fibres just above the wrist (Fig. 330). It covers the 
 flexor muscles and joins the anterior annular ligament. 
 
 The Anterior Annular Ligament (ligamentum carpi transversum) (Fig. 325) is a 
 strong, fibrous band which arches over the carpus, converting the deep groove 
 on the front of the carpal bones into a canal, beneath which pass the flexor 
 tendons of the fingers. It is attached, internally, to the pisiform bone and 
 
 1 Prof. WiUiam S. Forbes in the Philadelphia Medical Journal, January 15, 1898. 
 
492 
 
 THE 3fUSCLES AND FASCIA 
 
 the hook of the unciform bone {eminentia carpi ulnaris), and externally to the 
 tuberosity of the scaphoid and to the inner part of the anterior surface and 
 the ridge of the trapezium {eminentia carpi radialis). It is continuous, above, 
 with the deep fascia of the forearm, of which it may be regarded as a thickened 
 portion, and, below, with the palmar fascia. It is crossed by the ulnar vessels and 
 nerve and the cutaneous branches of the median and ulnar nerves. At its outer 
 extremity is the tendon of the Flexor carpi radialis, which lies in the groove on the 
 
 trapezium between the attachments of 
 the annular ligaments to the bone. It 
 has inserted into its anterior surface a 
 part of the tendon of the Palmaris longus 
 and part of the tendon of the Flexor 
 carpi ulnaris, and has arising from it, 
 below, the small muscles of the thumb 
 and little finger. Beneath it pass the 
 tendons of the Flexor sublimis and Pro- 
 fundus digitorum, the Flexor longus 
 pollicis, and the median nerve. 
 
 The Synovial Membranes of the Flexor 
 Tendons at the Wrist. — ^There are two 
 vaginal synovial membranes which en- 
 close all the tendons as they pass be- 
 neath this ligament — one for the Flexor 
 sublimis and Profundus digitorum, the 
 other for the Flexor longus pollicis. 
 They extend up into the forearm for 
 about an inch above the annular liga- 
 ment, and downward about half-way 
 along the metacarpal bone, where they 
 terminate in a blind diverticulum around 
 each pair of tendons, with the exception 
 of that of the thumb and those of the 
 little finger — in each of these two digits the diverticulum is continued on, and 
 communicates with the synovial sheath of the tendons in the fingers. In the other 
 three fingers the synovial sheath of the tendons begins as a blind pouch without 
 communication with the large synovial sac (Fig. 326). 
 
 Surgical Anatomy. — This arrangement of the synovial sheaths explains the fact that thecal 
 abscess in the thumb and little finger is liable to be followed by abscesses in the forearm, from 
 extension of the inflammation along the continuous synovial sheaths. Tuberculous inflamma- 
 tion is apt to occur in this situation, constituting compound palmar ganglion ; it presents an hour- 
 glass outline, with a swelling in front of the wrist and in the palm of the hand, and a constriction 
 corresponding to the annular ligament between the two. The fluid can be forced from the one 
 swelling to the other under the ligament. 
 
 Bursae about the Hand and Wrist. — Bursse usually exist between the distal 
 extremities of the metacarpal bones (burses intermetacarpophalangece) , and a sub- 
 cutaneous bursa often exists over the dorsal surface of the head of the fifth 
 metacarpal bone. Subcutaneous digital dorsal bursse occur " almost constantly 
 in the first finger-joints (between the first and second phalanx), occasionally in 
 the second joint of the second and fourth fingers"^ (bursce subcutanece digitorum 
 dorsales). A bursa exists between the tendon of the Extensor carpi radialis 
 brevior and the base of the third metacarpal bone; another between the Flexor 
 carpi ulnaris and the pisiform bone; another between the Flexor carpi radialis 
 and the base of the second metacarpal bone. 
 
 1 Hand Atlas of Human Anatomy. By Werner Spalteholz. Translated and edited by Lewellys F. Barker. 
 
 Fia. 326. — Diagram showing the arrangement of the 
 synovial sheaths of the palm and fingers. 
 
OF THE HAND 493 
 
 The Posterior Annulax Ligament (ligamentum carpi dorsale) is a strong fibrous 
 band extending obliquely downward and inward across the back of the wrist, and 
 consisting of the deep fascia of the back of the forearm, strengthened by the 
 addition of some transverse fibres. It binds down the extensor tendons in their 
 passage to the fingers, being attached, internally, to the styloid process of the ulna, 
 the cuneiform and pisiform bones; externally, to the margin of the radius; and, in 
 its passage across the wrist, to the elevated ridges on the posterior surface of the 
 radius. It presents six compartments for the passage of tendons, each of which is 
 lined by a separate synovial membrane 
 
 (Fig. 327). These are, from without ,^ ^^-'^^SM^ 
 
 inward: 1. On the outer side of the 
 styloid process, for the tendons of the 
 Extensor ossis metacarpi and Extensor 
 brevis pollicis. 2. Behind the styloid 
 process, for the tendons of the Ex- 
 tensor carpi radialis longior and bre- 
 vior. 3. About the middle of the 
 posterior surface of the radius, for the 
 tendon of the Extensor longus pollicis. 
 
 4. To the inner side of the latter, for -"". uln.«-^-- •-"«. l?^^^^f-^V ^^^ ^ ^^ 
 
 the tendons of the Extensor communis ^ „„, ^ ! """°'®" ' 
 
 ... ^ -r\ • T • p- *"'• ^^'- — Transverse section through the wrist, show- 
 
 dlgltorum and Extensor mdlClS. 5. ing the annular ligaments and the canals for the passage 
 
 Opposite the interval between the 
 
 radius and ulna, for the Extensor minimi digiti. 6. Grooving the back of the 
 
 ulna, for the tendon of the Extensor carpi ulnaris. The synovial membranes 
 
 lining these sheaths are usually very extensive, reaching from above the annular 
 
 ligament down upon the tendons for a variable distance on the back of the 
 
 hand. 
 
 The Deep Palmar Fascia (aponeurosis palmaris). — The deep palmar fascia 
 (Fig. 32S) forms a common sheath which invests the muscles of the hand. 
 It consists of a central and two lateral portions. 
 
 The Central Portion occupies the middle of the palm, is triangular in shape, of 
 great strength and thickness, and binds down the tendons and protects the vessels 
 and nerves in this situation. It is narrow above, where it is attached to the lower 
 margin of the annular ligament, and receives the expanded tendon of the Pal- 
 maris longus muscle. Below, it is broad and expanded, and divides into four 
 slips for the four fingers. Each slip gives off superficial fibres, which are inserted 
 into the skin of the palm and finger, those to the palm joining the skin at the 
 furrow corresponding to the metacarpo-phalangeal articulation, and those to the 
 fingers passing into the skin at the transverse fold at the base of the fingers. The 
 deeper part of each slip subdivides into two processes, which are inserted into the 
 lateral margins of the anterior (glenoid) ligament of the metacarpo-phalangeal 
 joint. From the sides of these processes offsets are sent backward, to be attached 
 to the borders of the lateral surfaces of the metacarpal bones at their distal extrem- 
 ities. By this arrangement short channels are formed on the front of the lower 
 ends of the metacarpal bones, through which the flexor tendons pass. Dr. W. W. 
 Keen describes a fifth slip as frequently found passing to the thumb. The inter- 
 vals left in the fascia between the four fibrous slips transmit the digital vessels 
 and nerves and the tendons of the Lumbricales. At the points of division of the 
 palmar fascia into the slips above mentioned numerous strong, transverse fibres 
 bind the separate processes together. The palmar fascia is intimately adherent 
 to the integument by dense fibro-areolar tissue, forming the superficial palmar 
 fascia, and gives origin by its inner margin to the Palmaris brevis: it covers the 
 superficial palmar arch, the tendons of the flexor muscles, and the branches of 
 
494 
 
 THE MUSCLES AND FASCIA 
 
 the median and ulnar nerves, and on each side it gives off a vertical septum, which 
 is continuous with the interosseous aponeurosis and separates the lateral from 
 the middle palmar group of muscles. 
 
 The Lateral Portions of the Palmar Fascia are thin, fibrous layers, which cover, 
 on the radial side, the muscles of the ball of the thumb, and, on the ulnar side, the 
 muscles of the little finger; they are continuous with the dorsal fascia, and in the 
 palm with the central portion of the palmar fascia. 
 
 Digital artery 
 Digital nerves. 
 
 Fig. 328. — Palmar fascia. (From a preparation in the Museum of the Royal College of Surgeons of England.) 
 
 The Superficial Transverse Ligament of the Fingers is a thin, fibrous band which 
 stretches across the roots of the four fingers, and is closely attached to the skin 
 of the clefts, and internally to the fifth metacarpal bone, forming a sort of rudi- 
 mentary web. Beneath it the digital vessels and nerves pass onward to their 
 destination. 
 
 Surgical Anatomy. — The palmar fascia is liable to undergo contraction, producing a very 
 inconvenient deformity known as Dupuytren's contraction. The ring and little fingers are most 
 frequently implicated,"but the middle, index, and the thumb may be involved. The proximal 
 phalanx is drawn down and cannot be straightened, and the two distal phalanges become simi- 
 larly flexed as the disease advances. 
 
THE BADIAL REGION 
 
 495 
 
 11. The Radial Region (Figs. 329, 330). 
 
 Abductor pollicis. 
 Opponens pollicis. 
 
 Flexor brevis pollicis. 
 Adductor obliquus pollicis. 
 
 Adductor transversus pollicis. 
 
 The Abductor Pollicis (m. abductor 'pollicis brevis) (Fig. 330) is a thin, flat 
 muscle, placed immediately beneath the integument. It arises from the anterior 
 annular ligament, the tuberosity of the scaphoid, and the ridge of the trapezium, 
 
 Fig. 329. — -Adductor pollicis, Opponens pollicis, and Pronator quadratus. (Testut.) 
 
 frequently by two distinct slips; and, passing outward and downward, is inserted 
 by a thin, flat tendon into the radial side of the base of the first phalanx of the 
 thumb, sending a slip to join the tendon of the Extensor longus pollicis. 
 
496 THE MUSCLES AND FASCIA 
 
 Relations. — By its superficial surface, with the palmar fascia and siiperficialis 
 voloe artery, which frequently perforates it. By its deep surface, with the Opponens 
 pollicis, from which it is separated by a thin aponeurosis. Its inner border is 
 separated from the Flexor brevis pollicis by a narrow cellular interval. 
 
 Fig. 330. — Muscles of the left hand. Palmar surface. 
 
 The Opponens Pollicis (Figs. 329 and 330), often called the flexor ossis meta- 
 carpi pollicis, is a small, triangular muscle, placed beneath the preceding. It arises 
 from the palmar surface of the ridge on the trapezium and from the annular 
 ligament, passes downward and outward, and is inserted into the whole length of 
 the metacarpal bone of the thumb on its radial side. 
 
THE RADIAL REGION 497 
 
 Relations. — By its superficial surface, with the Abductor and Flexor brevis 
 polHcis. By its deep surface, with the trapezio-metacarpal articulation. By its 
 inner border, with the Adductor obliquus pollicis. 
 
 The Flexor Brevis Pollicis (m. flexor pollicis brevis) (Fig. 330) consists of two 
 portions, outer and inner. The outer and more superficial portion arises from the 
 outer two-thirds of the lower border of the anterior annular ligament, and passes 
 along the outer side of the tendon of the Flexor longus pollicis; and, becoming 
 tendinous, has a sesamoid bone developed in its tendon, and is inserted into the 
 outer side of the base of the first phalanx of the thumb. The inner and deeper 
 portion of the muscle is very small, and arises from the ulnar side of the first 
 metacarpal bone beneath the Adductor obliquus pollicis, and is inserted into the 
 inner side of the base of the first phalanx with this muscle. 
 
 Relations. — By its superficial surface, with the palmar fascia. By its deep sur- 
 face, with the tendon of the Flexor longus pollicis. By its external surface, with 
 the Opponens pollicis. Behind, with the Adductor obliquus poUicis. 
 
 The Adductor Obliquus Pollicis (m. adductor pollicis) (Figs. 329 and 330) 
 arises by several slips from the os magnum, the bases of the second and third 
 metacarpal bones, the anterior carpal ligaments, and the sheath of the tendon 
 of the Flexor carpi radialis. From this origin the greater number of fibres 
 pass obliquely downward and converge to a tendon, which, uniting with the 
 tendons of the deeper portion of the Flexor brevis pollicis and the Adductor 
 transversus, is inserted into the inner side of the base of the first phalanx of the 
 thumb, a sesamoid bone being developed in the tendon of insertion. A consid- 
 erable fasciculus, however, passes more obliquely outward beneath the tendon 
 of the long flexor to join the superficial portion of the short flexor and the 
 Abductor pollicis.^ 
 
 Relations. — By its superficial surface, with the Flexor longus pollicis and the 
 outer head of the Flexor brevis pollicis. Its deep surfdce is in relation with the 
 deep palmar arch, which passes between the two adductors. 
 
 The Adductor Transversus Pollicis (Figs. 329 and 330) is the most deeply 
 seated of this group of muscles. It is of a triangular form, arising, by its broad 
 base, from the lower two-thirds of the metacarpal bone of the middle finger on 
 its palmar surface; the fibres, proceeding outward, converge to be inserted, with 
 the inner part of the Flexor brevis pollicis, and the Adductor obhquus pollicis, 
 into the ulnar side of the base of the first phalanx of the thumb. From the 
 common tendon of insertion a slip is prolonged to the Extensor longus pollicis. 
 The name adductor pollicis is frequently used to mean both of the adductors 
 (Figs. 329 and 3.30). 
 
 Relations. — By its superficial surface, with the Adductor obliquus pollicis, the 
 tendons of the Flexor profundus, and the Lumbricales. Its deep surface covers 
 the first two interosseous spaces, from which it is separated by a strong aponeu- 
 rosis. 
 
 Three of these muscles of the thumb, the Abductor, the Adductor transversus, 
 and the Flexor brevis pollicis, at their insertions give off fibrous expansions which 
 join the tendon of the Extensor longus pollicis. This permits of flexion of the 
 proximal phalanx and extension of the terminal phalanx at the same time. These 
 expansions, originally figured by Albinus, have been more recently described by 
 M. Duchenne.^ 
 
 Nerves. — ^The Abductor, Opponens, and outer head of the Flexor brevis pollicis 
 are supplied by the sixth cervical through the median nerve; the inner head of the 
 Flexor brevis, and the Adductors, by the eighth cervical through the ulnar nerve. 
 
 * This muscle is described by some as the deep portion of the Flexor brevis pollicis. 
 ^ Physiologie des Mouvements. 
 
 32 
 
498 THE MUSCLES AND FASCIA 
 
 Actions. — The actions of the muscles of the thumb are almost sufficiently indi- 
 cated by their names. This segment of the hand is provided with three extensors 
 — an extensor of the metacarpal bone, an extensor of the first, and an extensor of 
 the second phalanx; these occupy the dorsal surface of the forearm and hand. 
 There are also three flexors on the palmar surface — a flexor of the metacarpal 
 bone, a flexor of the proximal, and a flexor of the terminal phalanx; there is also 
 an Abductor and two Adductors. The Abductor pollicis moves the metacarpal 
 bone of the thumb outward; that is, away from the index finger. The Flexor 
 ossis metacarpi pollicis flexes the metacarpal bone — that is, draws it inward over 
 the palm — and at the same time rotates the bone, so as to turn the ball of the 
 thumb toward the fingers, thus producing the movement of opposition. The 
 Flexor brevis pollicis flexes and adducts the proximal phalanx of the thumb. The 
 Adductores pollicis move the metacarpal bone of the thumb inward; that is, 
 toward the index finger. These muscles give to the thumb its extensive range of 
 motion. It will be noticed, however, that in consequence of the position of the 
 first metacarpal bone, these movements differ from the corresponding movements 
 of the metacarpal bones of the other fingers. Thus extension of the thumb more 
 nearly corresponds to the motion of abduction in the other fingers, and flexion to 
 adduction. 
 
 12. The Ulnar Region (Fig. 330). 
 
 Palmaris brevis. Flexor brevis minimi digiti. 
 
 Abductor minimi digiti. Opponens minimi digiti. 
 
 The Palmaris Brevis is a thin quadrilateral muscle placed beneath the integu- 
 ment on the ulnar side of the hand. It arises by tendinous fasciculi from the 
 anterior annular ligament and palmar fascia; the fleshy fibres pass inward, to be 
 inserted into the skin on the inner border of the palm of the hand. 
 
 Relations. — By its superficial surface, with the integument, to which it is inti- 
 mately adherent, especially by its inner extremity; by its deep surface, with the 
 inner portion of the palmar fascia, which separates it from the ulnar vessels and 
 nerve, and from the muscles of the ulnar side of the hand. 
 
 The Abductor Minimi Digiti (m. abductor digiti quinti) is situated on the ulnar 
 border of the palm of the hand. It arises from the pisiform bone and from the 
 tendon of the Flexor carpi ulnaris, and terminates in a flat tendon, which divides 
 into two slips; one is inserted into the ulnar side of the base of the first phalanx 
 of the little finger. The other slip is inserted into the ulnar border of the aponeu- 
 rosis of the Extensor minimi digiti. 
 
 Relations. — By its superficial surface, with the inner portion of the palmar fascia 
 and the Palmaris brevis; by its deep surface, with the Opponens minimi digiti; 
 by its outer border, with the Flexor brevis minimi digiti. 
 
 The Flexor Brevis Minimi Digiti (m. fiexor digiti quinti brevis) lies on the same 
 plane as the preceding muscle, on its radial side. It arises from the convex aspect 
 of the hook of the unciform bone and anterior surface of the annular ligament, 
 and is inserted into the inner side of the base of the first phalanx of the little finger. 
 It is separated from the Abductor at its origin by the deep branches of the ulnar 
 artery and nerve. This muscle is sometimes wanting; the Abductor is then, 
 usually, of large size. 
 
 Relations. — By its superficial surface, with the internal portion of the palmar 
 fascia and the Palmaris brevis ; by its deep surface, with the Opponens. The deep 
 branch of the ulnar artery and the corresponding branch of the ulnar nerve pass 
 between the Abductor and Flexor brevis minimi digiti muscles. 
 
 The Opponens Minimi Digiti {m. opponens digiti quinti).— T\\\s muscle is 
 sometimes called the flexor ossis metacarpi (Fig. 320), is of a triangular form, and 
 placed immediately beneath the preceding muscles. It arises from the convexity 
 
THE MIDDLE PALMAR REGION 499 
 
 of the hook of the unciform bone and the contiguous portion of the anterior 
 annular ligament; its fibres pass downward and inward, to be inserted into the 
 whole length of the metacarpal bone of the little finger, along its ulnar margin. 
 
 Relations. — By its superficial surface, with the Flexor brevis and Abductor 
 minimi digiti ; by its deep surface, with the Interossei muscles in the fourth meta- 
 carpal space, the metacarpal bone, and the Flexor tendons of the little finger. 
 
 Nerves. — All the muscles of this group are supplied by the eighth cervical nerve 
 through the ulnar nerve. 
 
 Actions. — ^The Abductor minimi digiti abducts the little finger from the middle 
 line of the hand. It corresponds to a dorsal interosseous muscle. It also assists 
 in flexing the proximal phalanx and extending the second and third phalanges. 
 The Flexor brevis minimi digiti abducts the little finger from the middle line of 
 the hand. It also assists in flexing the proximal phalanx. The Opponens minimi 
 digiti draws forward the fifth metacarpal bone, so as to deepen the hollow of the 
 palm. The Palmaris brevis corrugates the skin on the inner side of the palm of 
 the hand and probably serves to protect the ulnar nerve and artery from damage 
 by the pressure of grasping a hard object. 
 
 13. The Middle Palmar Region. 
 
 Lumbricales. Interossei dorsales. 
 
 Interossei palmares. 
 
 The Lumbricales (Fig. 330) are four small fleshy fasciculi, accessories to the 
 deep Flexor muscle. They arise from the tendons of the deep Flexor: the first and 
 second, from the radial side and palmar surface of the tendons of the index and 
 middle fingers respectively; the third, from the contiguous sides of the tendons of 
 the middle and ring fingers; and the fourth, from the contiguous sides of the 
 tendons of the ring and little fingers. They pass to the radial side of the corre- 
 sponding fingers and opposite the metacarpo-phalangeal articulation each tendon 
 is inserted into the tendinous expansion of the Extensor communis digitorum, 
 covering the dorsal aspect of each finger. 
 
 The Interossei Muscles (Figs. 331 and 332) are so named from occupying 
 the intervals between the metacarpal bones, and are divided into two sets, dorsal 
 and palmar. 
 
 The Dorsal interossei (mm. interossei dorsales) are four in number, larger than the 
 palmar, and occupy the intervals between the metacarpal bones. They are bipen- 
 niform muscles, arising by two heads from the adjacent sides of the metacarpal 
 bones, but more extensively from the metacarpal bone of the finger into which the 
 muscle is inserted. They are inserted into the bases of the first phalanges and into 
 the aponeurosis of the common Extensor tendon. Between the double origin of 
 each of these muscles is a narrow triangular interval, through the first of which 
 passes the radial artery; through each of the other three passes a perforating 
 branch from the deep palmar arch. 
 
 The First dorsal interosseous muscle or Abductor indicis is larger than the 
 others. It is flat, triangular in form, and arises by two heads, separated by a 
 fibrous arch, for the passage of the radial artery from the dorsum to the palm of 
 the hand. The outer head arises from the upper half of the ulnar border of the 
 first metacarpal bone; the inner head, from almost the entire length of the radial 
 border of the second metacarpal bone; the tendon is inserted into the radial side 
 of the index finger. The second and third dorsal interossei are inserted into the 
 middle finger, the former into its radial, the latter into its ulnar side. The fourth 
 is inserted into the ulnar side of the ring finger. 
 
 The Palmar interossei {mm. interossei volar es), three in number, are smaller than 
 the Dorsal, and placed upon the palmar surface of the metacarpal bones, rather 
 
500 
 
 THE MUSCLES AND FASCIA 
 
 than between them. Each muscle arises from the entire length of the meta- 
 carpal bone of one finger, and is inserted into the side of the base of the first 
 phalanx and aponeurotic expansion of the common extensor tendon of the same 
 finger. The first arises from the ulnar side of the second metacarpal bone, and 
 is inserted into the same side of the first phalanx of the index finger. The second 
 arises from the radial side of the fourth metacarpal bone, and is inserted into the 
 
 Fig. 331. — The Dorsal interossei of left hand. 
 
 Fig. 332. — The Palmar interossei of left hand. 
 
 same side of the ring finger. The third arises from the radial side of the fifth 
 metacarpal bone, and is inserted into the same side of the little finger. From 
 this account it may be seen that each finger is provided with two Interosseous 
 muscles, with the exception of the little finger, in which the Abductor muscle 
 takes the place of one of the pair. 
 
 Nerves. — The two outer Lumbricales are supplied by the sixth cervical nerve, 
 through the third and fourth digital branches of the median nerve: the two inner 
 I^umbricales and all the Interossei are supplied by the eighth cervical nerve, 
 through the deep palmar branch of the ulnar nerve. Brooks states that the third 
 lumbrical received a twig from the median in twelve out of twenty-one cases. 
 
 Actions. — The Palmar interossei muscles adduct the fingers to an imaginary 
 line drawn longitudinally through the centre of the middle finger; and the Dorsal 
 interossei abduct the fingers from that line. In addition to this, the Interossei, in 
 conjunction with the Lumbricales, jiex the first phalanges at the metacarpo-phalan- 
 geal joints, and extend the second and third phalanges in consequence of their 
 insertion into the expansion of the extensor tendons. The Extensor communis 
 digitorum is believed to act almost entirely on the first phalanges. 
 
 SURFACE FORM OF THE UPPER EXTREMITY. 
 
 The Pectoralis major muscle largely influences surface form and conceals a considerable part 
 oi the thoracic wall in front. Its sternal origin presents a festooned border which bounds and 
 determines the width of the sternal furrow. Its clavicular origin is somewhat depressed and flat- 
 tened, and between the two portions of the muscle is often an oblique depression which differen- 
 tiates the one from the other. The outer margin of the muscle is generally well marked above, 
 and bounds the infraclavicular fossa, a triangular interval which separates the Pectoralis major 
 
SURFACE FORM OF THE UPPER EXTREMITY 501 
 
 from the Deltoid. It gradually becomes less marked as it approaches the tendon of insertion, 
 and becomes more closely blended with the Deltoid muscle. The lower border of the Pectoralis 
 major forms the rounded anterior axillary fold, and corresponds with the direction of the fifth rib. 
 The Pectoralis minor muscle influences surface form. When the arm is raised its lowest shp 
 of origin produces a local fulness just below the border of the anterior fold of the axilla, and so 
 serves to break the sharp line of the lower border of the Pectoralis major muscle, which is pro- 
 duced when the arm is in this position. The origin of the SerratUS magnus muscle produces a 
 very characteristic surface marking. When the arm is raised from the side in a well-developed 
 subject, the five or six lower serrations are plainly discernible, forming a zigzag line, caused by 
 the series of digitations, which diminish in size from above downward, and have their apices 
 arranged in the form of a curve. W^hen the arm is lying by the side, the first serration to 
 appear, at the lower margin of the Pectoralis major, is the one attached to the fifth rib. The 
 Deltoid muscle, with the prominence of the upper extremity of the humerus, produces the 
 rounded outline of the shoulder. It is rounder and fuller in front than behind, where it presents 
 a somewhat flattened form. Its anterior border, above, presents a rounded, slightly curved 
 eminence, which bounds externally the infraclavicular fossa; below, it is closely united with the 
 Pectoralis major. Its posterior border is thin, flattened, and scarcely marked above; below, it 
 is thicker and more prominent. When the muscle is in action, the middle portion becomes 
 irregular, presenting alternate longitudinal elevations and depressions, the elevations correspond- 
 ing to the fleshy portions, the depressions to the tendinous intersections of the muscle. The 
 insertion of the Deltoid is marked by a depression on the outer side of the middle of the arm. 
 Of the scapular muscles, the only one which materially influences surface form is the Teres 
 major, which assists the Latissimus dorsi in forming the thick, rounded fold of the posterior 
 boundary of the axilla. When the arm is raised, the Goraco-brachialis reveals itself as a long, 
 narrow elevation which emerges from under cover of the anterior fold of the axilla and runs 
 downward, internal to the shaft of the humerus. When the arm is hanging by the side, its 
 front and inner part presents the prominence of the Biceps, bounded on either side by an inter- 
 muscular depression. This muscle determines the contour of the front of the arm, and extends 
 from the anterior margin of the axilla to the bend of the elbow. Its upper tendons are con- 
 cealed by the Pectoralis major and the Deltoid, and its lower tendon sinks into the space at the 
 bend of the elbow. When the muscle is in a state of complete contraction — that is to say, 
 when the forearm has been flexed and supinated — it presents a rounded convex form, bulged 
 out laterally, and its length is diminished. On each side of the Biceps, at the lower part of 
 the arm, the Brachialis anticus is discernible. On the outer side it forms a narrow eminence 
 which extends some distance up the arm along the border of the Biceps. On the inner side it 
 shows itself only as a little fulness just above the elbow. On the back of the arm the long head 
 of the Triceps may be seen as a longitudinal eminence emerging from under cover of the Deltoid, 
 and gradually merging into the longitudinal flattened plane of the tendon of the muscle on the 
 lower part of the back of the arm. The tendon of insertion of the muscle extends about half- 
 way up the back of the arm, where it forms an elongated flattened plane when the muscle is in 
 action. Under similar conditions the surface forms produced by the three heads of the muscle 
 are well seen. On the anterior aspect of the elbow are to be seen two muscular elevations, 
 one on each side, separated above and converging below so as to form a triangular space. 
 Of these, the inner elevation, consisting of the flexors and pronator, forms the prominence 
 along the inner side and front of the forearm. It is a fusiform mass, pointed above at the 
 internal condyle and gradually tapering off below. The Pronator radii teres, the innermost 
 muscle of the group, forms the boundary of the triangular space at the bend of the elbow. It 
 is shorter, less prominent, and more oblique than the outer boundary. The most prominent 
 part of the eminence is produced by the Flexor carpi radialis, the muscle next in order on the 
 inner side of the preceding one. It forms a rounded prominence above, and can be traced 
 downward to its tendon, which can be felt lying on the front of the wrist, nearer to the radial 
 than to the ulnar border, and to the inner side of the radial artery. The Palmaris long^s pre- 
 sents no surface marking above, but below is the most prominent tendon on the front of the 
 wrist, standing out, when the muscle is in action, as a sharp, tense cord beneath the skin. The 
 Flexor sublimis digitorum does not directly influence surface form. The position of its four 
 tendons on the front of the lower part of the forearm is indicated by an elongated depression 
 between the tendons of the Palmaris longus and the Flexor carpi ulnaris. The Flexor carpi 
 ulnaris occupies a small part of the posterior surface of the forearm, and is separated from the 
 extensor and supinator group, which occupies the greater part of this surface, by the ulnar 
 furrow, produced by the subcutaneous posterior border of the ulna. Its tendon can be perceived 
 along the ulnar border of the front of the forearm, and is most marked when the hand is flexed 
 and adducted. The deep muscles of the front of the forearm have no direct influence on sur- 
 face form. The external group of muscles of the forearm, consisting of the extensors and supi- 
 nators, occupy the outer and a considerable portion of the posterior surface of this region. It 
 has a fusiform outline, which is altogether on a higher level than the pronato-flexor group. Its 
 apex emerges from between the Triceps and Brachialis anticus muscles some distance above the 
 
502 THE MUSCLES AND FASCIA 
 
 elbow-joint, and acquires its greatest breadth opposite the external condyle, and thence gradually 
 shades off into a flattened surface. About the middle of the forearm it divides into two 
 longitudinal eminences which diverge from each other, leaving a triangular interval between 
 them. The outer of these two groups of muscles consists of the Supinator longus and the 
 Extensor carpi radialis longior et brevior, which form a longitudinal eminence descending from 
 the external condylar ridge in the direction of the styloid process of the radius. The other and 
 more posterior group consists of the Extensor communis digitorum, the Extensor minimi digiti, 
 and the Extensor carpi ulnaris. It commences above as a tapering form at the external con- 
 dyle of the humerus, and is separated behind at its upper part from the Anconeus by a well- 
 marked furrow, and below, from the pronato-flexor mass, by the ulnar furrow. In the triangular 
 interval left between these two groups the extensors of the thumb and index finger are seen. 
 The only two muscles of this region which require special mention as independently influencing 
 surface form are the Supinator longus and the Anconeus. The inner border of the Supinator 
 longus forms the outer boundary of the triangular space at the bend of the elbow. It com- 
 mences as a rounded border above the condyle, and is longer, less oblique, and more prominent 
 than the inner boundary. Lower down, the muscle forms a full fleshy mass on the outer side of 
 the upper part of the forearm, and below tapers into a tendon, which may be traced down to 
 the styloid process of the radius. The Anconeus presents a well-marked and characteristic 
 surface form in the shape of a triangular, slightly elevated surface, immediately external to the 
 subcutaneous posterior surface of the olecranon, and differentiated from the common extensor 
 group by a well-marked oblique longitudinal depression. The upper angle of the triangle corre- 
 sponds to the external condyle, and is marked by a depression or dimple in this situation. In 
 the interval caused by the divergence from each other of the two groups of muscles into which 
 the extensor and supinator group is divided at the lower part of the forearm an oblique elongated 
 eminence is seen, caused by the emergence of two of the extensors of the thumb from their 
 deep origin at the back of the forearm. This eminence, full above and becoming flattened 
 out and partially subdivided below, runs downward and outward over the back and outer sur- 
 face of the radius to the outer side of the wrist-joint, where it forms a ridge, especially marked 
 when the thumb is extended, which passes onward to the posterior aspect of the thumb. The 
 tendons of most of the extensor muscles are to be seen and felt at the level of the wrist-joint. 
 Most externally are the tendons of the Extensor ossis metacarpi pollicis and the Extensor brevis 
 poUicis, forming a vertical ridge over the outer side of the joint from the styloid process of the 
 radius to the thumb. Internal to this is the oblique ridge produced by the tendon of the Exten- 
 sor longus pollicis, very noticeable when the muscle is in action. The Extensor carpi radialis 
 longior is scarcely to be felt, but the Extensor carpi radialis brevior can be distinctly perceived 
 as a vertical ridge emerging from under the inner border of the tendon of the Extensor longus 
 pollicis, when the hand is forcibly extended at the wrist. Internal to this, again, can be felt 
 the tendons of the Extensor indicis. Extensor communis digitorum, and Extensor minimi digiti; 
 the latter tendon being separated from those of the common extensor by a slight furrow. The 
 muscles of the hand are principally concerned, as far as regards surface-form, in producing 
 the thenar and hjrpothenar eminences, and individually are not to be distinguished, on the sur- 
 face, from each other. The Adductor trans versus pollicis is, however, an exception to this; 
 its anterior border gives rise to a ridge across the web of skin connecting the thumb to the rest 
 of the hand. The thenar eminence is much larger and rounder than the hypothenar one, which 
 presents a longer and narrower eminence along the ulnar side of the hand. When the Palmaris 
 brevis is in action it produces a wrinkling of the skin over the hypothenar eminence, and a deep 
 dimple on the ulnar border of the hand. The anterior extremities of the Lumbrical muscles 
 help to produce the soft eminences just behind the clefts of the fingers, separated from each 
 other by depressions corresponding to the flexor tendons in their sheaths. Between the thenar 
 and hypothenar eminences, at the wrist-joint, is a slight groove or depression, widening out as 
 it approaches the fingers; beneath this we have the strong central part of the palmar fascia. 
 Here we have some furrows, which are pretty constant in their arrangement, and bear some 
 resemblance to the letter M. One of these furrows passes obliquely outward from the groove 
 between the thenar and hypothenar regions near the wrist to the head of the metacarpal bone 
 of the index finger. A second passes inward, with a slight inclination upward, from the ter- 
 mination of the first to the ulnar side of the hand. A third runs nearly parallel with the second 
 and about three-quarters of an inch below it. Lastly, crossing these two latter furrows, is an 
 oblique furrow parallel with the first. The skin of the palm of the hand differs considerably 
 from that of the forearm. At the wrist it suddenly becomes hard and dense, and covered with 
 a thick layer of cuticle. The skin in the thenar region presents these characteristics less than 
 elsewhere. In spite of this hardness and density, the skin of the palm is exceedingly sensitive 
 and very vascular. It is destitute of hair, and no sebaceous follicles have been found in this 
 region. Over the fingers the skin again becomes thinner, especially at the flexures of the joints, 
 and over the terminal phalanges it is thrown into numerous ridges in consequence of the arrange- 
 ment of the papillse in it. These ridges form, in different individuals, distinctive and permanent 
 patterns, which may be used for purposes of identification. The superficial fascia in the palm 
 
SURGICAL ANATOMY OF THE UPPER EXTREMITY 503 
 
 is made up of dense fibro-fatty tissue. This tissue binds down the skin so firmly to the deep 
 palmar fascia that very little movement is permitted between the two. On the back of the hand 
 the Dorsal interossei produce elongated swellings between the metacarpal bones. The first 
 dorsal interosseous (Abductor indicis), when the thumb is closely adducted to the hand, forms 
 a prominent fusiform bulging; the other interossei are not so marked. 
 
 SURGICAL ANATOMY OF THE UPPER EXTREMITY. 
 
 The student, having completed the dissection of the muscles of the upper extremity, should 
 consider the effects likely to be produced by the action of the various muscles in fracture of the 
 bones. 
 
 In considering the actions of the various muscles upon fractures of the upper extremity, the 
 most common forms of injury have been selected both for illustration and description. 
 
 Fracture of the middle of the clavicle (Fig. 333) is always attended with considerable dis- 
 placement; the inner end of the outer fragment is displaced inward and backward, while the 
 outer end of the same fragment is rotated forward. The whole outer fragment is somewhat 
 depressed. The deformity is described by saying that the shoulder goes downward, forward, 
 and inward. 
 
 The displacement is produced as follows: inward, by the muscles passing from the chest to 
 the outer fragment of the clavicle, to the scapula, and to the humerus — viz., the Subclavius and 
 the Pectoralis minor, and, to a less extent, the Pectoralis major and the Latissimus dorsi; hack- 
 ward, in consequence of the rotation of the outer fragment. The Serratus magnus causes the 
 scapula to rotate on the wall of the chest; this carries the acromion and outer end of the outer 
 fragment of the clavicle forward and causes the piece of bone to rotate round a vertical axis 
 through its centre, and so carries the inner end of the outer portion backward. The depression 
 of the whole outer fragment is produced by the weight 
 of the arm and by the contraction of the Deltoid. The 
 outer end of the inner fragment appears to be elevated, 
 the skin being drawn tensely over it ; this is owing to 
 the depression of the outer fragment, as the inner frag- 
 ment is usually kept fixed by the costo-clavicular liga- 
 ment and by the antagonism between the Sternomastoid 
 and Pectoralis major muscles. But it may be raised by 
 an unusually strong Sterno-mastoid, or by the inner end 
 of the outer fragment getting below and behind it. The 
 causes of displacement having been ascertained, it is 
 easy to apply the appropriate treatment. The outer 
 fragment is to be drawn outward, and, together with the 
 scapula, raised upward to a level with the inner frag- 
 ment, and retained in that position. The formula for 
 correcting the deformity is as follows : carry the shoulder 
 upward, outward, and backward. 
 
 In fracture of the acromial end of the clavicle, between 
 the conoid and trapezoid ligaments, only slight displace- 
 ment occurs, as these ligaments, from their oblique in- 
 sertion, serve to hold both portions of the bone in appo- 
 sition. Fracture, also, of the sternal end, internal to 
 the costoclavicular ligament, is attended with only slight 
 displacement, this ligament serving to retain the frag- 
 ments in close apposition. 
 
 Fracture of the acromion process usually arises from 
 violence applied to the upper and outer part of the 
 shoulder; it is generally known by the rotundity of the 
 shoulder being lost, from the Deltoid drawing the fractured portion downward and forward; 
 and the displacement may easily be discovered by tracing the macgin of the clavicle outward, 
 when the fragment will be found resting on the front and upper part of the head of the 
 humerus. In order to relax the anterior and outer fibres of the Deltoid (the opposing muscle), 
 the arm should be drawn forward across the chest and the elbow well raised, so that the head 
 of the bone may press the acromion process upward and retain it in its position. 
 
 Fracture of the coracoid process is an extremely rare accident, and is usually caused by a 
 sharp blow on the point of the shoulder. Displacement is here produced by the combined 
 actions of the Pectoralis minor, short head of the Biceps, and Coraco-brachialis, the former 
 muscle drawing the fragment inward, and the latter muscles directly downward, the amount of 
 displacement being limited by the connection of this process to the acromion by means of the 
 coraco-acromial ligament. In many cases there appears to have been little or no displacement, 
 
 Fig. 333. 
 
 -Fracture of the middle of the 
 clavicle. 
 
504 
 
 THE MUSCLES AND FASCIA 
 
 from the fact that the coraco-clavicular ligament has remained intact, and has kept the separated 
 fragment from displacement. In order to relax these muscles and replace the fragments in 
 close apposition, the forearm should be flexed so as to relax the Biceps, and the arm drawn 
 forward and inward across the chest, so as to relax the Coraco-brachialis; the humerus should 
 then be pushed upward against the coraco-acromial ligament, and the arm retained in that 
 position. 
 
 Fracture of the surgical neck of the humerus (Fig. 334) is very common, is attended with 
 considerable displacement, and its appearances correspond somewhat with those of dislocation 
 of the head of the humerus into the axilla. The upper fragment is slightly elevated under the 
 coraco-acromial ligament by the muscles attached to the greater and lesser tuberosities; the 
 lower fragment is drawn inward by the Fectoralis major, Latissimus dorsi, and Teres major; and 
 the humerus is thrown obliquely outward from the side by the Deltoid, and occasionally elevated 
 
 so as to cause the upper end of the lower fragment to project 
 beneath and in front of the coracoid process. The deformity 
 is reduced by fixing the shoulder, and drawing the arm out- 
 ward and downward. To counteract the opposing muscles, 
 and to keep the fragments in position, a conical-shaped pad 
 should be placed with the apex in the axilla ; while the fore- 
 arm is flexed to an angle of 90 degrees the shoulder is padded 
 with cotton, a shoulder-cap of plaster-of-Paris is applied to 
 cover the shoulder, a portion of the chest and back, and the 
 arm down to the external condyle (Scudder). The arm, with 
 the elbow slightly forward, is bandaged to the side. In some 
 cases a splint is placed between the axillary pad and the 
 inner side of the arm. 
 
 In fracture of the shaft of the humerus below the insertion 
 of the Fectoralis major, Latissimus dorsi, and Teres major, 
 and above the insertion of the Deltoid, there is also consider- 
 able deformity, the upper fragment being drawn inward by 
 the first-mentioned muscles, and the lower fragment upward 
 and outward by the Deltoid, producing shortening of the limb 
 and a considerable prominence at the seat of fracture, from 
 the fractured ends of the bone riding over one another, espe- 
 cially if the fracture takes place in an oblique direction. The 
 fragments may be brought into apposition by extension from 
 the elbow, and are retained in that position by adopting the same means as in the preceding 
 injury, or by the use of an internal angular splint with three short humeral splints. 
 
 In fractures of the shaft of the humerus immediately below the insertion of the Deltoid, the 
 amount of deformity depends greatly upon the direction of the fracture. If it occurs in a trans- 
 verse direction, only slight displacement takes place, the upper fragment being drawn a little 
 forward; but in oblique fracture the combined actions of the Biceps and Brachialis anticus 
 muscles in front and the Triceps behind draw upward the lower fragment, causing it to glide 
 over the upper fragment, either backward or forward, according to the direction of the fracture. 
 Simple extension reduces the deformity, and the application of an internal angular splint and 
 three short humeral splints will retain the fragments in apposition. Care should be taken not 
 to raise the elbow, but the forearm and hand may be supported in a sling. 
 
 Fracture of the humerus (Fig. 335) above the condyle deserves very attentive considera- 
 tion, as the general appearances correspond somewhat with those produced by separation 
 of the epiphysis of the humerus, and with those of dislocation of the radius and ulna back- 
 ward. If the direction of the fracture is oblique from above, downward and forward, the 
 lower fragment is drawn upward by the Brachialis anticus and Biceps in front and the Triceps 
 behind ; and at the same time is drawn backward behind the upper fragment by the Triceps. 
 This injury may be diagnosticated from dislocation by the increased mobility in fracture, the 
 existence of crepitus, and the fact of the deformity being remedied by extension, on the discon- 
 tinuance of which it is reproduced. The age of the patient is of importance in distinguishing 
 this form of injury from separation of the epiphysis. If fracture occurs in the opposite direc- 
 tion to that shown in Fig. 335, the lower fragment is drawn upward and forward, causing a 
 considerable prominence in front, and the upper fragment projects backward beneath the 
 tendon of the Triceps muscle. 
 
 Fractures of the lower extremity of the humerus are spoken of as fractures in the neighbor- 
 hood of the elbow-joint. The term includes fracture of the external condyle, of the internal condyle, 
 at the base of the condyles, and T- or Y-shaped fracture, the two condyles being separated 
 from each other and from the shaft of the humerus. Such injuries are followed by great and 
 rapid swelling. Whenever possible the .r-rays are used to aid in diagnosis, and the patient is 
 placed under ether, to set and dress the fracture. 
 
 In fracture of the inner condyle the fragment with the ulna passes up and back, and when 
 
 Fig. 334. — Fracture of the surgical 
 neck of the humerus. 
 
SURGICAL ANATOMY OF THE UPPER EXTREMITY 
 
 505 
 
 the forearm is extended the ulna projects posteriorly. The " carrying function " of the arm is 
 lost, because the forearm deviates to the ulnar side. 
 
 In all cases of fracture of the lower end of the humerus, except fracture at the base of 
 the condyles, effect reduction by traction upon the forearm, and supination, extension, and 
 bending the forearm slowly into acute flexion. In transverse fracture above the condyles 
 draw the forearm and the lower fragment downward and forward and push the upper frag- 
 ment back. A case can be treated by maintaining a position of acute flexion (Jones's position) 
 or by using an anterior angular splint. Allis and others treat in extension. 
 
 Fracture of the olecranon process (Fig. 336) is a frequent accident. The detached fragment 
 is displaced u]n\ard, by the action of the Triceps muscle, from half an inch to two inches; the 
 prominence of the elbow is consequently lost, and a deep hollow is felt at the back part of the 
 joint, which is much increased on flexing the limb. The patient at the same time loses, more 
 or less, the power of extending the forearm. The treatment consists in relaxing the Triceps by 
 extending the limb, and retaining it in the extended position by means of a long straight splint 
 applied to the front of the arm; the fragments are thus brought into close apposition, and 
 may be further approximated by drawing down the upper fragment. Union is generally 
 ligamentous. 
 
 Fracture of the neck of the radius is an exceedingly rare accident, and is generally caused 
 by direct violence. Its diagnosis is somewhat obscure, on account of the slight deformity visible, 
 the injured part being surrounded by a large number of muscles; but the movements of prona- 
 tion and supination are entirely lost. The upper fragment is drawn outward by the Supinator 
 
 Tig. 335. 
 
 -Fracture of the humerus above 
 the condyles. 
 
 Fig. 336. — Fracture of the olecranon. 
 
 brevis, the extent of displacement being limited by the attachment of the orbicular ligament. 
 The lower fragment is drawn forward and slightly upward by the Biceps, and inward by the 
 Pronator radii teres, its displacement forward and upward being counteracted in some degree 
 by the Supinator brevis. The treatment essentially consists in relaxing the Biceps, Supinator 
 brevis, and Pronator radii teres muscles by flexing the forearm, and placing it in a position mid- 
 way between pronation and supination, extension having been previously made so as to bring 
 the parts in apposition. 
 
 In fracture of the radius below the insertion of the Biceps, but above the insertion of the 
 Pronator radii teres, the upper fragment is strongly supinated by the Biceps and Supinator 
 brevis, and at the same time drawn forward and flexed by the Biceps; the lower fragment is 
 pronated and drawn inward toward the ulna by the pronators. Thus there is extreme dis- 
 placement with very little deformity. In treating such a fracture the arm must be put up in 
 a position of supination, otherwise union will take place with great impairment of the move- 
 ments of the hand. In fractures of the radius below the insertion of the Pronator radii teres 
 (Fig. 337), the upper fragment is drawn upward by the Biceps and inward by the Pronator 
 radii teres, holding a position midway between pronation and supination, and a degree of fulness 
 in the upper half of the forearm is thus produced; the lower fragment is drawn downward and 
 inward toward the ulna by the Pronator quadratus, and thrown into a state of pronation by the 
 same muscle; at the same time, the Supinator longus, by elevating the styloid process, into which 
 
506 
 
 THE MUSCLES AND FASCIA 
 
 it is inserted, will serve to depress the upper end of the lower fragment still more toward the ulna. 
 In order to relax the opposing muscles the forearm should be bent, and the limb placed in a 
 position midway between pronation and supination; the fracture is then easily reduced by 
 extension from the wrist and elbow: well-padded splints should be applied on both sides of 
 the forearm from the elbow to the wrist; the hand being allowed to fall, will, by its own weight, 
 counteract the action of the Pronator quadratus and Supinator longus, and elevate the lower 
 fragment to the level of the upper one. 
 
 In fracture of the sha]t of the ulna the upper fragment retains its usual position, but the 
 lower fragment is drawn outward toward the radius by the Pronator quadratus, producing a 
 well-marked depression at the seat of fracture and some fulness on the dorsal and palmar sur- 
 faces of the forearm. The fracture is easily 
 reduced by extension from the wrist and fore- 
 arm. The forearm should be flexed, and 
 placed in a position midway between pronation 
 and supination, and well-padded splints ap- 
 plied from the elbow to the ends of the fingers. 
 In fracture of the shafts of the radius and 
 ulna together the lower fragments are drawn 
 upward, sometimes forward, sometimes back- 
 ward, according to the direction of the frac- 
 ture, by the combined actions of the Flexor and 
 Extensor muscles, producing a degree of ful- 
 ness on the dorsal or palmar surface of the 
 forearm; at the same time the two fragments are drawn into contact by the Pronator quad- 
 ratus, the radius being in a state of pronation : the upper fragment of the radius is drawn 
 upward and inward by the Biceps and Pronator radii teres to a higher level than the ulna; 
 the upper portion of the ulna is slightly elevated by the Brachialis anticus. The fracture may 
 be reduced by extension from the wrist and elbow, and the forearm should be placed in the 
 same position as in fracture of the ulna. 
 
 In fracture of the lower end of the radius {Colles'r fracture) (Fig. 338) the displacement 
 which is produced is very considerable, and bears some resemblance to dislocation of the 
 carpus backward, from which it should be carefully distinguished. The lower fragment is 
 displaced backward and upward, but this displacement is probably due to the force of the 
 blow driving the portion of the bone into this position and not to any muscular influence. 
 The upper fragment projects forward, often lacerating the substance of the Pronator quad- 
 ratus, and is drawn by this muscle into close contact with the lower end of the ulna, causing a 
 
 Fig. 337. — Fracture of the shaft of the radius. 
 
 Fig. 338. — Fracture of the lower end of the radius. 
 
 projection on the anterior surface of the forearm, immediately above the carpus, from the flexor 
 tendons being thrust forward. This fracture may be distinguished from dislocation by the 
 deformity being removed on making sufficient extension, when crepitus may be occasionally 
 detected; at the same time, on extension being discontinued, the parts immediately resume 
 their deformed appearance. The age of the patient will also assist in determining whether 
 the injury is fracture or separation of the epiphysis. Reduction is effected by hyperextension, 
 longitudinal traction, and forced flexion.' The posterior straight splint with suitable pads is 
 the best dressing. 
 
 ^ R. J. Levis. 
 
OF THE LOWER EXTREMITY 
 
 507 
 
 MUSCLES AND FASCI-ffi OF THE LOWER EXTREMITY. 
 
 The Muscles of the liower Extremity are subdivided into groups corresponding 
 with the different regions of the Umb. 
 
 I. Iliac Region. 
 
 Psoas magnus. 
 Psoas parvus. 
 Iliacus. 
 
 11. Thigh. 
 1. Anterior Femoral Region. 
 
 Tensor fascise Femoris. 
 
 Sartorius. 
 
 Rectus. 
 
 Quadriceps 
 extensor. 
 
 Vastus externus. 
 Vastus internus. 
 Crureus. 
 Subcrureus. 
 
 2. Internal Femoral Region. 
 
 Gracilis. 
 Pectineus. 
 Adductor longus. 
 Adductor brevis. 
 Adductor magnus. 
 
 3. Gluteal Region. 
 Gluteus maximus. 
 Gluteus medius. 
 Gluteus minimus 
 Pyriformis. 
 Obturator internus. 
 Gemellus superior. 
 Gemellus inferior. 
 Quadratus femoris. 
 Obturator externus. 
 
 4. Posterior Femoral Region. 
 
 Biceps. 
 
 Semitendinosus. 
 
 Semimembranosus. 
 
 III. Leg. 
 
 5. Anterior Tibio-fibular Region. 
 
 Tibialis anticus. 
 Extensor proprius hallucis. 
 Extensor longus digitorum. 
 Peroneus tertius. 
 
 6. Posterior Tibio-fibular Region. 
 
 Superficial Layer. 
 
 Gastrocnemius. 
 Soleus. 
 , Plantaris. 
 
 Deep Layer. 
 
 Popliteus. 
 
 Flexor longus hallucis. 
 Flexor longus digitorum. 
 Tibialis posticus. 
 
 7. Fibular Region. 
 
 Peroneus longus. 
 Peroneus brevis. 
 
 IV. Foot. 
 
 8. Dorsal Region. 
 Extensor brevis digitorum. 
 
 9. Plantar Region. 
 
 First Layer. 
 
 Abductor hallucis. 
 Flexor brevis digitorum. 
 Abductor minimi digiti. 
 
 Second Layer. 
 
 Flexor accessorius. 
 Lumbricales. 
 
 Third Layer. 
 
 Flexor brevis hallucis. 
 Adductor obliquus hallucis. 
 Flexor brevis minimi digiti. 
 Adductor transversus hallucis. 
 
 Fourth Layer. 
 The Interossei. 
 
508 
 
 THE MUSCLES AND FASCIA 
 
 I. MUSCLES AND FASCI-ffl OF THE ILIAC REGION. 
 
 Psoas magnus. 
 
 Psoas parvus. 
 
 Iliacus. 
 
 Dissection. — No detailed description is required for the dissection of these muscles. On 
 the removal of the viscera from the abdomen they are exposed, covered by the peritoneum and 
 a thin layer of fascia, the iliac fascia. 
 
 Iliac Fascia {fascia iliaca). — ^The iliac fascia^ is the aponeurotic layer which 
 lines the back part of the abdominal cavity, and covers the Psoas and Iliacus 
 muscles throughout their whole extent. It is thin above, and becomes gradually 
 thicker below as it approaches the crural arch. 
 
 The Portion Covering the Psoas is attached, above, to the ligamentum arcuatum 
 internum; internally, by a series of arched processes to the intervertebral sub- 
 stances and prominent margins of the bodies of the vertebrae, and to the upper part 
 of the sacrum, the intervals so left, opposite the constricted portions of the bodies, 
 
 PELVIC 
 ILIACUS PERITONEUM 
 
 FASCIA ILIACA 
 
 PELVIC FASCIA 
 
 EXTRA- PERITONEAL 
 
 TISSUE 
 
 PARIETAL LAYER 
 OF PELVIC FASCIA 
 
 VISCERAL LAYER 
 
 OF PELVIC FASCIA 
 
 FASCIAL CANAL 
 
 FAT OF ISCHIO- 
 RECTAL FOSSA 
 
 SPHINCTER 
 ANI EXTERNUS 
 
 Fig. 339. — Oblique section across the pelvis, to show the disposition of the pelvic fascia and the 
 boundaries of the ischio-rectal fossa. (Cunningham. ) 
 
 transmitting the lumbar arteries and veins and filaments of the sympathetic cord. 
 Externally, above the crest of the ilium, this portion of the iliac fascia is continu- 
 ous with the anterior lamella of the lumbar fascia, but below the crest of the 
 ilium it is continuous with the fascia covering the Iliacus. 
 
 The Portion Investing the Iliacus is connected externally to the whole length 
 of the inner border of the crest of the ilium, and internally to the brim of the true 
 pelvis, where it is continuous with the periosteum; and at the ilio-pectineal emi- 
 nence it receives the tendon of insertion of the Psoas parvus, when that muscle 
 exists. External to the femoral vessels, this fascia is intimately connected to the 
 posterior margin of Poupart's ligament, and is continuous with the fascia transver- 
 salis. Immediately to the outer side of the femoral vessels the fascia iliaca is pro- 
 longed backward and inward from Poupart's ligament as a band, the ilio-pectineal 
 ligament, which is attached to the ilio-pectineal eminence. This ligament divides 
 the space between Poupart's ligament and the innominate bone into two parts, the 
 inner of which {lacuna vasorum) transmits the femoral vessels, and contains the 
 
 * The student must not confound this fascia with the iliac portion of the fascia lata (see p. 515). 
 
THE ILIAC REGION 
 
 509 
 
 margin of Gimbernat's ligament and also the femoral ring; the outer {lacuna 
 musculorum) the ilio-psoas and the anterior crural nerve (Fig. 340). Internal to 
 the vessels the iliac fascia is attached to the ilio-pectineal line behind the con- 
 joined tendon, where it is again continuous with the transversalis fascia; and, 
 corresponding to the point where the femoral vessels pass into the thigh, this 
 fascia descends behind them, forming the posterior wall of the femoral sheath. 
 This portion of the iliac fascia which passes behind the femoral vessels is also 
 attached to the ilio-pectineal line beyond the limits of the attachment of the con- 
 joined tendon ; at this part it is continuous with the pubic portion of the fascia lata 
 of the thigh. The external iliac vessels lie in front of the iliac fascia, but all the 
 branches of the lumbar plexus behind it; it is separated from the peritoneum by a 
 quantity of loose areolar tissue. The femoral or crural sheath {fascia cruris) is 
 
 POUPART'S 
 LIGAM ENT 
 ANTERIOR 
 CRURAL NERVE 
 
 FEMORAL ARTERY 
 
 LIAC FASCIA 
 
 FEMORAL VEIN 
 
 GIMBERNAT'S 
 LIGAMENT 
 
 PECTINEUS 
 
 Fig. 340. — Poupart's ligament and the relation of the parts passing beneath it. (Poirier and Charpy.) 
 
 formed by the transversalis fascia in front of the vessels and the iliac fascia back 
 of them. The fascia? join to the inner side of the femoral vein, a space, the 
 femoral canal, intervening between the vein and the junction. 
 
 Between the femoral vein and the edge of Gimbernat's ligament is the femoral or 
 crural ring {annulus femoralis) (Fig. 342). The crural or femoral canal {canalis 
 femoralis) is the interval between the femoral vein and the inner wall of the femoral 
 (crural) sheath. This canal extends from the femoral ring to the saphenous 
 opening. The femoral ring is closed by the septum crurale of Cloquet {septum 
 femorale [Cloqueti]) , which is a process of transversalis fascia. 
 
 The Psoas Magnus {rn. psoas major) (Fig. 343) is a long fusiform muscle placed 
 on the side of the lumbar region of the spine and the margin of the pelvis. It arises 
 from the front of the bases and lower borders of the transverse processes of the 
 
510 THE MUSCLES AND FASCIA 
 
 lumbar vertebrae by five fleshy slips; also from the sides of the bodies and the corre- 
 sponding intervertebral substances of the last dorsal and all the lumbar vertebrae. 
 The muscle is connected to the bodies of the vertebrae by five slips; each slip is 
 attached to the upper and lower margins of two vertebrae, and to the intervertebral 
 substance between them, the slips themselves being connected by the tendinous 
 arches which extend across the constricted part of the bodies, and beneath which 
 pass the lumbar arteries and veins and filaments of the sympathetic cord. These 
 tendinous arches also give origin to muscular fibres, and protect the blood-vessels 
 and nerves from pressure during the action of the muscle. The first slip is attached 
 to the contiguous margins of the last dorsal and first lumbar vertebrae; the last 
 to the contiguous margins of the fourth and fifth lumbar vertebrae, and to the 
 intervertebral substance. From these points the muscle descends across the 
 brim of the pelvis, and, diminishing gradually in size, passes beneath Pou- 
 part's ligament, and terminates in a tendon which, after receiving nearly the 
 whole of the fibres of the Iliacus, is inserted into the lesser trochanter of the 
 femur. 
 
 Relations. — In the lumbax region: by its anterior surface, which is placed behind 
 the peritoneum, with the ihac fascia, the ligamentumarcuatum internum, the kidney, 
 Psoas parvus, renal vessels, ureter, spermatic vessels, genito-crural nerve, and the 
 colon. In many cases the vermiform appendix rests upon the Psoas muscle (page 
 511). By its posterior surface, with the transverse processes of the lumbar vertebrae 
 and the Quadratus lumborum muscle, from which it is separated by the anterior 
 lamella of the lumbar fascia. The lumbar plexus is situated in the posterior part 
 of the substance of the muscle. By its inner side the muscle is in relation with the 
 bodies of the lumbar vertebrae, the lumbar arteries, the ganglia of the sympathetic 
 nerve, and their branches of communication with the spinal nerves; the lumbar 
 glands ; the vena cava inferior on the right and the aorta on the left side, and along 
 the brim of the pelvis with the external iliac artery. In the thigh it is in relation, 
 in front, with the fascia lata; behind, with the capsular ligament of the hip, from 
 which it is separated by a synovial bursa (bursa ilio-pectinea) , which frequently 
 communicates with the cavity of the joint through an opening of variable size; 
 between the tendon and part of the lesser trochanter is the bursa iliaca sub- 
 tendinea ; by its inner border, with the Pectineus and internal circumflex artery, 
 and also with the femoral artery, which slightly overlaps it: by its outer border, 
 with the anterior crural nerve and Iliacus muscle. 
 
 The Psoas Parvus (m. psoas minor) (Fig. 343) is a long slender muscle placed 
 in front of the Psoas magnus. It arises from the sides of the bodies of the last 
 dorsal and first lumbar vertebrae and from the intervertebral substance between 
 them. It forms a small flat muscular bundle, which terminates in a long flat 
 tendon inserted into the ilio-pectineal eminence, and, by its outer border, into 
 the iliac fascia. This muscle is often absent, and, according to Cruveilhier, is 
 sometimes double. 
 
 Relations. — It is covered by the peritoneum, and, at its origin, by the ligamentum 
 arcuatum internum; it rests on the Psoas magnus. 
 
 The Hiacus (Fig. 343) is a flat, triangular muscle which fills up the whole of the 
 iliac fossa. It arises from the upper two-thirds of this fossa and from the inner 
 margin of the crest of the ilium; behind, from the ilio-lumbar ligament and base 
 of the sacrum; in front, from the anterior superior and anterior inferior spinous 
 processes of the ilium, from the notch between them. The fibres converge to be 
 inserted into the outer side of the tendon of the Psoas, some of them being pro- 
 longed on to the shaft of the femur for about an inch below and in front of the 
 lesser trochanter.^ The most external fibres are inserted into the capsule of the 
 
 ^ The Psoas magnus, Psoas parvus, and Iliacus are regarded by His and others as a single muscle, the Ilio- 
 psoas (Fig. 340). 
 
THE ILIAC REGION 511 
 
 hip-joint. If these fibres are separate they constitute the Ilio-capsularis muscle or 
 the niacus minor. 
 
 Relations. — Within the abdomen: by its anterior surface, with the ihac fascia, 
 which separates the muscle from the peritoneum, and with the external cutaneous 
 nerve ; on the right side, with the caecum ; on the left side, with the sigmoid flexure 
 of the colon; by its posterior surface, with the iliac fossa; by its inner border, with 
 the Psoas magnus and anterior crural nerve. In the thigh, it is in relation, by its 
 anterior surface, with the fascia lata, the Rectus and Sartorius muscles, and the 
 profunda femoris artery; behind, with the capsule of the hip-joint, a synovial 
 bursa common to it and the Psoas magnus being interposed. 
 
 Nerves. — The Psoas magnus is supplied by the anterior branches of the second 
 and third lumbar nerves; the Psoas parvus, when it exists, is supplied by the 
 anterior branch of the first lumbar nerve ; and the Iliacus by the anterior branches 
 of the second and third lumbar nerves through the anterior crural. 
 
 Actions. — The Psoas and Iliacus muscles, acting from above, flex the thigh 
 upon the pelvis. Acting from below, the femur being fixed, the muscles of 
 both sides bend the lumbar portion of the spine and pelvis forward. They also 
 serve to maintain the erect position, by supporting the spine and pelvis upon 
 the femur, and assist in raising the trunk when the body is in the recumbent 
 posture. 
 
 The Psoas parvus is a tensor of the iliac fascia. It assists in flexing the lumbar 
 spine laterally, the pelvis being its fixed point. 
 
 Surgical Anatomy. — There is no definite septum between the portions of the iliac fascia 
 covering the Psoas and IHacus respectively, and the fascia is only connected to the subjacent 
 muscles by a quantity of loose connective tissue. When an abscess forms beneath this fascia, 
 as it is very apt to do, the matter is contained in an osseo-fibrous cavity, which is closed on all 
 sides within the abdomen, and is open only at its lower part, where the fascia is prolonged over 
 the muscle into the thigh. 
 
 Abscess within the sheath of the Psoas muscle (psoas abscess) is generally due to tuberculous 
 caries of the bodies of the lower dorsal or of the lumliar vertebrae. When the disease is in the dorsal 
 region, the matter tracts down the posterior mediastinum, in front of the bodies of the vertebrae, 
 and, passing beneath the ligamentum arcuatum internum, enters the sheath of the Psoas muscle, 
 down which it passes as far as the pelvic brim ; it then gets beneath the iliac portion of the fascia 
 and fills up the iliac fossa. In consequence of the attachment of the fascia to the pelvic brim, it 
 rarely finds its way into the pelvis, but passes by a narrow opening under Poupart's ligament 
 into the thigh, to the outer side of the femoral vessels. It thus follows that a Psoas abscess may 
 be described as consisting of four parts: (1) a somewhat narrow channel at its upper part, in the 
 Psoas sheath; (2) a dilated sac in the iliac fossa; (3) a constricted neck under Poupart's ligament; 
 and (4) a dilated sac in the upper part of the thigh. When the lumbar vertebrae are the seat of the 
 disease, the matter finds its way directly into the substance of the muscle. If a Psoas abscess 
 forms the muscular fibres are destroyed, and the nervous cords contained in the abscess are isolated 
 and exposed in its interior; the femoral vessels which lie in front of the fascia remain intact, and 
 the peritoneum seldom becomes implicated. All Psoas abscesses do not, however, pursue this 
 course: the matter may leave the muscle above the crest of the ilium, and, tracking backward, 
 may point in the loin (lumbar abscess) ; or it may point above Poupart's ligament in the inguinal 
 region; or it may follow the course of the iliac Vessels into the pelvis, and, passing through the 
 ^eat sacro-sciatic notch, discharge itself on the back of the thigh; it may open into the bladder 
 or find its way into the perinaeum, or it may pass down the thigh to the popliteal space or even 
 lower. Strain of the Psoas muscle is not unusual, and induces pain which may be mistaken 
 for appendicitis. The bursa beneath the tendon of the Psoas and Iliacus and the hip-joint or 
 that between the tendon and the lesser trochanter may greatly enlarge and produce pain and 
 disablement. Byron Robinson* pointed out that trauma of the Psoas muscle may be an 
 important factor in the etiology of appendicitis, trauma may induce periappendicular adhe- 
 sions and adhesions interfere with the circulation of blood and faeces. Robinson says, in the 
 previously quoted article, that in 46 per cent, of men and in 20 per cent, of women the 
 appendix rests on the Psoas muscle. 
 
 1 Annals of Surgery, April, 1901. 
 
512 
 
 THE MUSCLES AND FASCIA 
 
 II. MUSCLES AND FASCIA OF THE THIGH. 
 1. The Anterior Femoral Region. 
 
 Tensor fascise femoris. 
 Sartorius. 
 
 i Rectus. 
 Vastus externus. 
 Vastus internus. 
 Crureus. 
 Subcrureus. 
 
 
 1. Dissection of 
 femoral hernia, 
 
 and Scarpa's 
 
 triangle. 
 
 Dissection. — To expose the muscles and fasciae in this region, make an incision along 
 Poupart's ligament, from the anterior superior spine of the ilium to the spine of the os pubis; 
 a vertical incision from the centre of this, along the middle of the thigh to below the knee-joint; 
 and a transverse incision from the inner to the outer side of the leg, at the lower end of the ver- 
 tical incision. The flaps of integument having been removed, the superficial and deep fasciae 
 should be examined. The more advanced student should commence the study of this region by 
 an examination of the anatomy of femoral hernia and Scarpa's triangle, the incisions for the 
 dissection of which are marked out in Fig. 341. 
 
 Superficial Fascia. — The superficial fascia forms a continuous layer over the 
 whole of the thigh. It consists of areolar tissue, containing in its meshes much fat, 
 
 and is capable of being separated into two or 
 more layers, between which are found the super- 
 ficial vessels and nerves. It varies in thickness 
 in different parts of the limb: in the groin it 
 is thick, and the two layers are separated from 
 one another by the superficial inguinal lymphatic 
 glands, the internal saphenous vein, and several 
 smaller vessels. One of these two layers, the 
 superficial, is continuous above with the super- 
 ficial fascia of the abdomen and the back. In- 
 ternally it is continuous with the superficial 
 fascia of the perineum. The deep layer of the 
 superficial fascia is a very thin fibrous layer, 
 best marked on the inner side of the k)ng 
 saphenous vein and below Poupart's ligament. 
 It is placed beneath the subcutaneous vessels 
 and nerves and upon the surface of the fascia 
 lata. It is intimately adherent to the fascia lata 
 a little below Poupart's ligament. It covers the 
 saphenous opening (Fig. 342) in the fascia lata, 
 being closely united to the margins of the open- 
 ing, and is connected to the sheath of the fem- 
 oral vessels by its under surface. The portion 
 of the fascia covering this aperture is perforated 
 by the internal saphenous vein and by numer- 
 ous blood- and lymphatic vessels; hence it has 
 been termed the cribriform fascia (fascia cribrosa), 
 theopenings for these vessels having been Hkened 
 to the holes in a sieve. The cribriform fascia 
 adheres closely both to the superficial fascia and 
 to the fascia lata, so that it is described by some 
 anatomists as part of the fascia lata, but is usually 
 considered (as in this work) as belonging to the 
 superficial fascia. It is not until the cribriform 
 fascia has been cleared away that the saphenous opening is seen, so that this open- 
 ing does not in ordinary cases exist naturally, but is the result of dissection. Mr. 
 
 g \ ^. Front of thigh. 
 
 S. Front of leg. 
 
 ^ / ^ I 4. Dorsum of foot. 
 
 Fig. 341.- 
 
 -Dissection of lower extremity. 
 Front view. 
 
THE ANTERIOR FEMORAL REGION 
 
 513 
 
 Callender, however, speaks of cases in which, probably as the result of pressure 
 from enlarged inguinal lymphatic glands, the fascia has become atrophied, and a 
 saphenous opening exists independent of dissection. A femoral hernia in passing 
 through the saphenous opening receives the cribriform fascia as one of its cover- 
 ings. A large subcutaneous bursa (bursa pra'patellaris subcutanea) is found in the 
 superficial fascia over the patella, and another (bursa trochanterica subcutanea) 
 in the superficial fascia over the great trochanter. 
 
 Deep Fascia or Fascia Lata (Fig. 342). — The deep fascia of the thigh is exposed 
 on the removal of the superficial fascia, and is named, from its great extent, the fascia 
 lata; it forms a uniform investment for the whole of this region of the limb, but varies 
 in thickness in different parts; thus, it is thicker in the upper and outer part of 
 the thigh, where it receives a fibrous expansion from the Gluteus maximus muscle, 
 and the Tensor fasciae femoris is inserted between its layers : it is very thin behind, 
 and at the upper and inner part where it covers the Adductor muscles, and again 
 
 POUPART'S 
 LIGAMENT 
 
 INTERCOLUMNAR 
 FIBRES 
 
 GIMBERNAT'S 
 LIGAMENT 
 
 SAPHENOUS 
 
 OPENING 
 
 FEMORAL 
 
 VEIN 
 
 LONG 
 
 SAPHENOUS 
 
 VEIN 
 
 EXTERNAL 
 •ABDOMINAL 
 RING 
 
 Fig. 342.— Right external abdominal ring and saphenous opening in the male. (Spalteholz). 
 
 becomes stronger around the knee, receiving fibrous expansions from the tendon of 
 the Biceps externally, from the Sartorius internally, and from the Quadriceps 
 extensor in front. The fascia lata is attached, above and behind, to the back of 
 the sacrum and coccyx; externally, to the crest of the ilium; in front, to Pou- 
 part's hgament and to the body of the os pubis; and internally, to the descend- 
 ing ramus of the os pubis, to the ramus and tuberosity of the ischium, and to the 
 lower border of the great sacro-sciatic ligament. From its attachment to the crest 
 of the ilium it passes down over the Gluteus medius muscle to the upper border 
 of the Gluteus maximus, where it splits into two layers, one passing superficial to 
 and the other beneath this muscle. At the lower border of the muscle the two layers 
 reunite. Externally the fascia lata receives the greater part of the tendon of inser- 
 tion of the Gluteus maximus, and becomes proportionately thickened. The 
 portion of the fascia lata arising from the front part of the crest of the ilium, cor- 
 
 33 
 
514 
 
 THE MUSCLES AND FASCIA 
 
 Wf I « 
 
 llllt V 
 
 X 
 
 ''(o 
 
 t^liW§BS! responding to the origin of the Tensor fasciae 
 femoris, passes down the outer side of the thigh 
 as two layers, one superficial to and the other 
 beneath this muscle. The deep layer is a con- 
 tinuation of the tendinous fibres of the Gluteus 
 maximus muscle and the superficial layer is 
 chiefly a continuation of the tendinous fibres of 
 the Tensor fasciae femoris, but receives some 
 fibres from the fascia covering the Gluteus 
 medius muscle/ These layers at the lower 
 end of the muscle become blended into a thick 
 and strong band, having first received the in- 
 sertion of the muscle. This band is continued 
 downward, under the name of the ilio-tibial band 
 (tractus iliotibialis [Maissiati]), to be inserted 
 into the external tuberosity of the tibia. A 
 strengthening band of transverse fibres is placed 
 in the gluteal groove or sulcus {sulcus glutceus) and 
 another is placed across the roof of the popliteal 
 space. Below, the fascia lata is attached to all 
 the prominent points around the knee-joint — 
 viz., the condyles of the fenmr, tuberosities of 
 the tibia, and head of the fibula. On each side 
 of the patella it is strengthened by transverse 
 fibres given off from the lower part of the Vasti 
 muscles, which are attached to and support this 
 bone. Of these the outer fibres are the stronger, 
 and are continuous with the ilio-tibial band. 
 From the inner surface of the fascia lata are 
 given off two strong intermuscular septa, which 
 are attached to the whole length of the linea 
 aspera and its prolongations above and below: 
 the external intermuscular septum {septum in- 
 termusculare laterale) is the stronger. It extends 
 from the insertion of the Gluteus maximus to 
 the outer condyle, separates the Vastus externus 
 in front from the short head of the Biceps be- 
 hind, and gives partial origin to these muscles; 
 the internal intermuscular septum {septum inter- 
 musculare mediale), the thinner of the two, 
 separates the Vastus internus from the Adductor 
 and Pectineus muscles. Besides these there 
 are numerous smaller septa, separating the in- 
 dividual muscles and enclosing each in a dis- 
 ,\^''^ "T^^^f/ tinct sheath. At the upper and inner part of 
 
 the thigh, a little below Poupart's ligament, a 
 large oval-shaped aperture is observed after 
 the superficial fascia has been cleared off: it 
 transmits the internal saphenous vein and other 
 smaller vessels, and is termed the saphenous 
 opening {fossa ovalis) (Fig. 342) . This opening 
 is covered by a portion of the deep layer of the 
 
 Fig. 343.— Muscles of the iliac and anterior i Werner Spalteholz's Hand Atlas of Human Anatomy. Edited 
 femoral region. and translated by Lewellys F. Barker. 
 
 Jr^r 
 
THE ANTERIOR FEMORAL REGION 515 
 
 superficial fascia, the cribriform fascia. In order more correctly to consider the 
 mode of formation of this aperture, the fascia lata in this part of the thigh is 
 described as consisting of two portions — an iliac portion and a pubic portion. 
 
 Iliac Portion. — The iliac portion, the superficial layer of the fascia lata or the 
 Sartorial portion of the fascia lata, is all that part of the fascia lata on the outer 
 side of the saphenous opening. It is attached, externally, to the crest of the 
 ilium and its anterior superior spine, to the whole length of Poupart's ligament as 
 far internally as the spine of the os pubis, and to the pectineal line in conjunction 
 with Gimbernat's ligament. From the spine of the os pubis it is reflected down- 
 ward and outward, forming an arched margin, the falciform process or the falciform 
 margin of Bm-ns (margo falciformw), or the superior comuof the saphenous opening 
 (cornu superius). This margin overlies and is adherent to the anterior layer of 
 the sheath of the femoral vessels: to its edge is attached the cribriform fascia; 
 and, below, it is continuous with the pubic portion of the fascia lata. The 
 femoral ligament, or the ligament of Hey, is the point at which the falciform 
 process joins the base of Gimbernat's ligament. 
 
 Pubic Portion. — The pubic portion, or the pectineal portion, or the deep layer of 
 the fascia lata, is situated at the inner side of the saphenous opening : at the lower 
 margin of this aperture it is continuous with the iliac portion. The lower concave 
 margin of the saphenous opening where the two layers of fascia are continuous is 
 called the inferior cornu {cornu injerim). Traced upward, the pubic portion covers 
 the surface of the Pectineus, Adductor longus, and Gracilis muscles, and, passing 
 behind the sheath of the femoral vessels, to which it is closely united, is continu- 
 ous with the sheath of the Psoas and Iliacus muscles, and is attached above to 
 the ilio-pectineal line, where it becomes continuous with the iliac fascia. From 
 this description it may be observed that the iliac portion of the fascia lata passes 
 in front of the femoral vessels, and the pubic portion behind them, so that an 
 apparent aperture exists between the two, through which the internal saphenous 
 joins the femoral vein.^ 
 
 Surgflcal Anatomy. — The ilio-tibial band at a point between the crest of the ilium and the 
 great trochanter is so tense that it is impossible to sink the fingers in deeply in this region. Dr. 
 Allis points out that in fracture of the neck of the femur the great trochanter mounts toward 
 the iliac crest, the ilio-tibial band relaxes, and the fingers can be sunk deeply into the space 
 between the great trochanter and the iliac crest — Alhs's sign. Allis's sign indicates shorten- 
 ing. A Psoas abscess usually points at the termination of the Psoas muscle, but the tuberculous 
 matter may be directed down the thigh beneath the fascia lata, and it may reach the popliteal 
 space or even lower. 
 
 The fascia should now be removed from the surface of the muscles. This may be effected by 
 pinching it up between the forceps, dividing it, and separating it from each muscle in the course 
 of its fibres. 
 
 The Tensor FasciaB Femoris (w. tensor fascice Iotas, m. tensor vagina femoris) 
 (Fig. ^43)' arises from the anterior part of the outer lip of the crest of the ilium, 
 and from the outer surface of the anterior superior spinous process, and part of 
 the outer border of the notch below it, between the Gluteus medius and Sartorius, 
 and from the surface of the fascia covering the Gluteus medius. It is inserted 
 between two layers of the fascia lata, about one-fourth down the outer side of 
 the thigh. From the point of insertion the fascia is continued downward to the 
 external tuberosity of the tibia as a thickened band, the ilio-tibial band. 
 
 Relations. — By its superficial surface, with the fascia lata and the integument; 
 by its deep surface, with the Gluteus medius. Rectus femoris, and Vastus externus 
 muscles, and the ascending branches of the external circumflex artery; by its 
 anterior border, with the Sartorius, from which it is separated below by a triangular 
 
 1 These parts will be again more particularly described with the anatomy of Hernia. 
 
516 THE MUSCLES AND FASCIA 
 
 space, in which is seen the Rectus femoris; by its posterior border, with the 
 Gluteus medius. 
 
 The Sartorius (Fig. 343) , the longest muscle in the body, is flat, narrow, and 
 ribbon-like; it arises by tendinous fibres from the anterior superior spinous process 
 of the ilium and the upper half of the notch below it, passes obliquely across the 
 upper and anterior part of the thigh, from the outer to the inner side of the limb, 
 then descends vertically, as far as the inner side of the knee, passing behind the 
 inner condyle of the femur, and terminates in a tendon which, curving obliquely- 
 forward, expands into a broad aponeurosis, inserted in front of the Gracilis and 
 Semitendinosus, into the upper part of the inner surface of the shaft of the tibia, 
 nearly as far forward as the crest. The upper part of the tendon is curved back- 
 ward over the upper edge of the tendon of the Gracilis so as to be inserted behind 
 it. An offset is derived from the upper margin of this aponeurosis, which blends 
 with the fibrous capsule of the knee-joint, and another, given off from its lower 
 border, blends with the fascia on the inner side of the leg. 
 
 The relations of this muscle to the femoral artery should be carefully examined, 
 as it constitutes the chief guide in tying the vessel. In the upper third of the 
 thigh it forms the outer side of a triangular space, Scarpa's triangle (trigonum 
 femorale) , the inner side of which is formed by the inner border of the Adductor 
 longus, and the base, which is turned upward, by Poupart's ligament; the femoral 
 artery passes perpendicularly through the middle of this space from its base to 
 its apex. In the middle third of the thigh the femoral artery lies first along 
 the inner border, and then behind the Sartorius. 
 
 Relations. — By its superficial surface, with the fascia lata and integument; by 
 its deejp surface, with the Rectus, Iliacus, Vastus internus, anterior crural nerve, 
 sheath of the femoral vessels. Adductor longus. Adductor magnus, Gracilis, 
 Semitendinosus, long saphenous nerve, and internal lateral ligament of the knee- 
 joint. Frequently there is a bursa (bursa to. sartorii propria) between the tendon 
 of the Sartorius and the tendons of the Gracilis and Semimembranosus. It may 
 be in communication with the bursa anserina. 
 
 The Quadriceps Extensor (to. quadriceps femoris) (Fig. 343) includes the four 
 remaining muscles on the front of the thigh. It is the great Extensor muscle 
 of the leg, forming a large fleshy mass which covers the front and sides of the 
 femur, being united below into a single tendon, attached to the patella, and 
 above subdivided into separate portions, which have received distinct names. 
 Of these, one occupying the middle of the thigh, connected above with the ilium, 
 is called the Rectus femoris, from its straight course. The other divisions lie in 
 immediate connection with the shaft of the femur, which they cover from the 
 trochanters to the condyles. The portion on the outer side of the femur is 
 termed the Vastus extemus; that covering the inner side, the Vastus internus; 
 and that covering the front of the femur, the Crureus. 
 
 The Rectus Femoris is situated in the middle of the anterior region of the thigh; 
 it is fusiform in shape, and its superficial fibres are arranged in a bipenniform 
 manner, the deep fibres running straight down to the deep aponeurosis. It arises 
 by two tendons: one, the anterior or straight, from the anterior inferior spinous 
 process of the ihum; the other, the posterior or reflected tendon, from a groove 
 above the brim of the acetabulum; the two unite at an acute angle and spread 
 into an aponeurosis, which is prolonged downward on the anterior surface of the 
 muscle and from which the muscular fibres arise.* The muscle terminates in a 
 broad and thick aponeurosis, which occupies the lower two-thirds of its posterior 
 surface, and, gradually becoming narrowed into a flattened tendon, is inserted 
 
 1 Mr. W. R. Williams, in an interesting paper in the Jourh. of Anat. and Phys., vol. xiii. p. 204, pomts 
 out that the reflected tendon is the real origin of the muscle, and is alone present in early foetal life. The 
 direct tendon is merely an accessory band of condensed fascia. The paper will well repay perusal, though in 
 some particulars I think the description in the text more generally accurate. — Ed. of 15th English edition. 
 
THE ANTERIOR FEMORAL REGION 517 
 
 into the patella in common with the Vasti and Crureus. Beiween the tendon of 
 origin and the acetabulum there is often a biirsa {bursa m. recti femoris). 
 
 Relations. — By its superficial surface, with the anterior fibres of the Gluteus 
 minimus, the Tensor fasciae femoris, the Sartorius, and the Iliacus; by its lower 
 three-fourths, with the fascia lata. By its posterior surface, with the hip-joint, 
 the external circumflex vessels, branches of the anterior crural nerve, and the 
 Crureus and Vasti muscles. 
 
 The Vastus Extemus (m. vastus lateralis) is the largest part of the Quadriceps 
 extensor. It arises by a broad aponeurosis, which is attached to the upper half 
 of the anterior intertrochanteric line, to the anterior and inferior borders of the 
 root of the great trochanter, to the outer lip of the gluteal ridge, and to the upper 
 half of the outer lip of the linea aspera; this aponeurosis covers the upper three- 
 fourths of the muscle, and from its inner surface many fibres take origin. A few 
 additional fibres arise from the tendon of the Gluteus maximus, and from the 
 external intermuscular septum between the Vastus externus and short head of the 
 Biceps. The fibres form a large fleshy mass, which is attached to a strong aponeu- 
 rosis, placed on the under surface of the muscle at its lower part: this becomes 
 contracted and thickened into a flat tendon, which is inserted into the outer 
 border of the patella, blending with the great Extensor tendon, and giving an 
 expansion to the capsule of the knee-joint. Some of the fibres run down by the 
 side of the patella to the condyle of the tibia, and are called the retinacula patellae 
 laterals. 
 
 Relations. — By its superficial surface, with the Rectus, the Tensor fasciae femoris, 
 the fascia lata, and the tendon of the Gluteus maximus, from which it is separated 
 by a synovial bursa. By its deep surface, with the Crureus, some large branches 
 of the external circumflex artery and anterior crural nerve being interposed. 
 
 The Vastus Intemus and Crureus appear to be inseparably united, but when 
 the Rectus femoris has been reflected, a narrow interval will be observed extending 
 upward from the inner border of the patella between the two muscles. Here they 
 can be separated, and the separation should be continued upward as far as the 
 lower part of the anterior intertrochanteric line, where, however, the two muscles 
 are frequently continuous. 
 
 The Vastus Intemus (m. vastus medialis) arises from the lower half of the 
 anterior intertrochanteric line, the spiral line, the inner lip of the linea aspera, 
 the upper part of the internal supra-condylar line, and the tendon of the Adductor 
 magnus and the internal intermuscular septum. Its fibres are directed downward 
 and forward, and are chiefly attached to an aponeurosis which lies on the deep 
 surface of the muscle and is inserted into the inner border of the patella and 
 the Quadriceps extensor tendon, an expansion being sent to the capsule of the 
 knee-joint. Some of the fibres run down by the side of the patella to the con- 
 dyle of the tibia and are called the retinacula patellae mediale. 
 
 The Crureus (m. vastus iniermedius) arises from the front and outer aspect of 
 the shaft of the femur in its upper two-thirds and from the lower part of the 
 external intermuscular septum. Its fibres end in a superficial aponeurosis, which 
 forms the deep part of the Quadriceps extensor tendon. 
 
 Relations. — The inner edge of the Crureus is in contact with the anterior edge 
 of the Vastus internus, but when separated from each other, as directed above, the 
 latter muscle is seen merely to overlap the inner aspect of the femoral shaft without 
 taking any fibres of origin from it. The Vastus internus is partly covered by the 
 Rectus and Sartorius, but where these separate near the knee it becomes superficial, 
 and produces a well-marked prominence above the inner aspect of the knee. In 
 the middle third of the thigh it forms the outer wall of Hunter's canal (canalis 
 adductorius [Hunteri]), which contains the femoral vessels and the long saphenous 
 nerve — the roof of the canal being formed by a strong fascia which extends from 
 
518 THE MUSCLES AND FASCIA 
 
 the Vastus internus to the Adductores longus and magnus. The Crureus is almost 
 completely hidden by the Rectus femoris and Vastus externus. The deep surface 
 of the two muscles is in relation with the femur and Subcrureus muscles. A 
 synovial bursa (bursa suprapatellaris) is situated between the femur and the 
 portion of the Quadriceps extensor tendon above the patella; in the adult it 
 communicates with the synovial cavity of the knee-joint. 
 
 The tendons of the different portions of the Quadriceps extensor unite at the 
 lower part of the thigh, so as to form a single strong tendon, which is inserted into 
 the upper part of the patella, some few fibres passing over it to blend with the 
 Ligamentum patellae. More properly, the patella may be regarded as a sesamoid 
 bone, developed in the tendon of the Quadriceps; and the Ligamentum patellae, 
 which is continued from the lower part of the patella to the tuberosity of the tibia, 
 as the proper tendon of insertion of the muscle. A synovial bursa, the deep patel- 
 lar bursa {bursa infrapatellaris profunda), is interposed between the tendon and 
 the upper part of the tuberosity of the tibia; and another, the pre-patellar bursa 
 (bursa proepatellaris subcutanea), is placed over the patella itself. This latter 
 bursa often becomes enlarged, constituting "housemaid's knee." 
 
 The Subcrureus {m. articularis genu) is a small muscle, usually distinct from 
 the Crureus, but occasionally blended with it, which arises from the anterior sur- 
 face of the lower part of the shaft of the femur, and is inserted into the upper 
 part of the cul-de-sac of the capsular ligament which projects upward beneath 
 the Quadriceps for a variable distance. It sometimes consists of several separate 
 muscular bundles. 
 
 Nerves. — The Tensor fasciae femoris is supplied by the fourth and fifth lumbar 
 and first sacral nerves through the superior gluteal nerve; the other muscles of 
 this region, by the second, third, and fourth lumbar nerves, through branches of 
 the anterior crural. 
 
 Actions. — ^The Tensor fasciae femoris is a tensor of the fascia lata; continuing 
 its action, the oblique direction of its fibres enables it to abduct and to rotate the 
 thigh inward. In the erect posture, acting from below, it will serve to steady the 
 pelvis upon the head of the femur, and by means of the ilio-tibial band it steadies 
 the condyles of the femur on the articular surfaces of the tibia, and assists the 
 Gluteus maximus in supporting the knee in the extended position. The Sartorius 
 flexes the leg upon the thigh, and, continuing to act, flexes the thigh upon the 
 pelvis; it next rotates the thigh outward. It was formerly supposed to adduct the 
 thigh, so as to cross one leg over the other, and hence received its name of Sar- 
 torius, or tailor's muscle (sartor, a tailor), because it was supposed to assist in cross- 
 ing the legs in the squatting position. When the knee is bent the Sartorius assists 
 the Semitendinosus, Semimembranosus, and Popliteus in rotating the tibia inward. 
 Taking its fixed point from the leg, it flexes the pelvis upon the thigh, and, if one 
 muscle acts, assists in rotating the pelvis. The Quadriceps extensor extends the 
 leg upon the thigh. The Rectus muscle assists the Psoas and Iliacus in supporting 
 the pelvis and trunk upon the femur. It also assists in flexing the thigh on the 
 pelvis, or if the thigh is fixed it will flex the pelvis. The Vastus internus draws 
 the patella inward as well as upward. 
 
 Surgical Anatomy. — A few fibres of the Rectus muscle are liable to be ruptured from 
 severe strain. This accident is especially liable to occur during the games of football and cricket, 
 and is sometimes known as cricket thigh. The patient experiences a sudden pain in the part, 
 as if he had been struck, and the Rectus muscle stands out and is felt to be tense and rigid. The 
 accident is often followed by considerable swelling from inflammatory effusion. Occasionally the 
 Quadriceps extensor may be torn away from its insertion into the patella, or the tendon of the 
 quadriceps may be ruptured about an inch above the bone. This accident is caused in the same 
 manner that fracture of the patella by muscular action is produced — viz., by a violent muscular 
 effort to prevent falling whilst the knee is in a position of semiflexion. A distinct gap can be 
 
THE INTERNAL FEMORAL REGION 5I9 
 
 felt above the patella, and, owing to the retraction of the muscular fibres, union may fail to take 
 place. Sudden and powerful contraction of the Quadriceps extensor femoris is the cause of 
 transverse fracture of the patella. 
 
 2. The Internal Femoral Region. 
 
 Gracilis. Adductor longus. 
 
 Pectineus. Adductor brevis. 
 
 Adductor magnus. 
 
 Dissection. — These muscles are at once exposed by removing the fascia from the forepart 
 and inner side of the thigh. The limb should be abducted, so as to render the muscles tense 
 and easier of dissection. 
 
 The Gracilis (Figs. 343, 346, and 349) is the most superficial muscle on the 
 inner side of the thigh. It is thin and flattened, broad above, narrowing and taper- 
 ing below. It arises by a thin aponeurosis from the lower half of the margin of the 
 symphysis and the anterior half of the pubic arch. The fibres pass vertically down- 
 ward, and terminate in a rounded tendon which passes behind the internal condyle 
 of the femur, and, curving round the inner tuberosity of the tibia, becomes flattened, 
 and is inserted into the upper part of the inner surface of the shaft of the tibia, below 
 the tuberosity. A few of the fibres of the lower part of the tendon are prolonged 
 into the deep fascia of the leg. The tendon of this muscle is situated immediately 
 above that of the Semitendinosus, and its upper edge is overlapped by the tendon 
 of the Sartorius, with which it is in part blended. As it passes across the internal 
 lateral ligament of the knee-joint it is separated from it by a synovial bursa 
 (bursa anserina) common to it and the Semitendinosus muscle. 
 
 Relations. — By its superficial surf ace, with the fascia lata and the Sartorius below: 
 the internal saphenous vein crosses it obliquely near its lower part, lying superficial 
 to the fascia lata; the internal saphenous nerve emerges between its tendon and 
 that of the Sartorius ; by its deep surface, with the Adductor brevis and the Adductor 
 magnus and the internal lateral ligament of the knee-joint. 
 
 The Pectineus (Fig. 343) is a flat, quadrangular muscle, situated at the anterior 
 part of the upper and inner aspect of the thigh. It arises from the linea ilio-pec- 
 tinea, and to a slight extent from the surface of the bone in front of it between the 
 pectineal eminence and spine of the os pubis, and from the fascia covering the 
 anterior surface of the muscle; the fibres pass downward, backward, and outward, 
 to be inserted into a rough line leading from the lesser trochanter to the linea aspera. 
 
 Relations. — By its anterior surface, with the pubic portion of the fascia lata, 
 which separates it from the femoral vessels and internal saphenous vein; by its 
 posterior surface, with the capsular ligament of the hip-joint, the Adductor brevis 
 and Obturator externus nuiscles, the obturator vessels and nerve being interposed ; 
 by its outer border, with the Psoas, a cellular interval separating them, through 
 which pass the internal circumflex vessels; by its inner border, with the margin of 
 the Adductor longus. There is usually a bursa (bursa m. pectinei) between the 
 pectineus and the tendon of the psoas and iliacus. 
 
 The Adductor Longus (Figs. 343 and 344), the most superficial of the three 
 Adductors, is a flat triangular muscle lying on the same plane as the Pectineus. 
 It arises, by a flat narrow tendon, from the front of the os pubis, at the angle of 
 junction of the crest with the symphysis; and soon expands into a broad fleshy 
 belly, which, passing downward, backward, and outward, is inserted, by an 
 aponeurosis, into the linea aspera, between the Vastus internus and the Adductor 
 magnus, with both of which it is usually blended. 
 
 Relations. — By its anterior surface, with the fascia lata, the Sartorius, and, near 
 its insertion, with the femoral artery and vein; by its posterior surface, with the 
 Adductor brevis and magnus, the anterior branches of the obturator nerve, and 
 
520 
 
 THE MUSCLES AND FASCIAE 
 
 with the profunda artery and vein near its insertion; by its outer border, with the 
 Pectineus; by its inner border, with the GraeiUs. 
 
 The Pectineus and Adductor longus should now 
 be divided near their origin, and turned down- 
 ward, when the Adductor brevis and Obturator ex- 
 ternus will be exposed. 
 
 The Adductor Brevis (Fig. 344) is situ- 
 ated immediately behind the two preceding 
 muscles. It is somewhat triangular in 
 form, and arises by a narrow origin from 
 the outer surface of the body and descend- 
 ing ramus of the os pubis, between the 
 Gracilis and Obturator externus. Its fibres 
 passing backward, outward, and downward, 
 are inserted, by an aponeurosis, into the 
 lower part of the line leading from the lesser 
 trochanter to the linea aspera and the upper 
 part of the same line, immediately behind 
 the Pectineus and upper part of the Ad- 
 ductor longus. 
 
 Relations. — By its anterior surface, with 
 the Pectineus, Adductor longus, profunda 
 femoris artery, and anterior branches of the 
 obturator nerve; by its 'posterior surface, 
 with the Adductor magnus and posterior 
 branch of the obturator nerve ; by its outer 
 border, with the internal circumflex artery, 
 the Obturator externus, and conjoined ten- 
 don of the Psoas and Iliacus; by its inner 
 border, with the Gracilis and Adductor 
 magnus. This muscle is pierced, near its 
 insertion, by the second or by the first and 
 second perforating branches of the pro- 
 funda femoris artery. 
 
 The Adductor brevis should now be cut away 
 near its origin, and turned outward, when the en- 
 tire extent of the Adductor magnus will be exposed. 
 
 The Adductor Magnus (Fig. 344) is a 
 large triangular muscle forming a septum 
 between the muscles on the inner and those 
 on the back of the thigh. It arises from a 
 small part of the descending ramus of the 
 OS pubis, from the ramus of the ischium, 
 and from the outer margin of the inferior 
 part of the tuberosity of the ischium. Those 
 fibres which arise from the ramus of the os 
 pubis are very short, horizontal in direction, 
 and are inserted into the rough line leading 
 from the great trochanter to the linea aspera, 
 internal to the Gluteus maximus. They are 
 considered by some a distinct muscle and called the Adductor minimus. The fibres 
 taking origin from the ramus of the ischium are directed downward and outward 
 
 Fig. 344.- 
 
 -Deep muscles of the internal femoral 
 region. 
 
THE INTERNAL FEMORAL REGION 521 
 
 with different degrees of obliquity, to be inserted, by means of a broad aponeurosis, 
 into the Unea aspera and the upper part of its internal prolongation below. The 
 internal portion of the muscle, consisting principally of those fibres which arise from 
 the tuberosity of the ischium, forms a thick fleshy mass consisting of coarse bundles 
 which descend almost vertically, and terminate about the lower third of the thigh 
 in a rounded tendon, which is inserted into the Adductor tubercle on the inner 
 condyle of the femur, being connected by a fibrous expansion to the line leading 
 upward from the tubercle to the linea aspera. Between the two portions of the 
 muscle an interval is left, tendinous in front, fleshy behind, for the passage of the 
 femoral vessels from Hunter's canal into the popliteal space. The external portion 
 of the muscle at its attachment to the femur presents three or four osseo-aponeurotic 
 openings, formed by tendinous arches attached to the bone, from which muscular 
 fibres arise. The three superior of these apertures are for the three perforating 
 arteries, and the fourth, when it exists, is for the terminal branch of the profunda. 
 
 Relations. — By its anterior surface, with the Pectineus, Adductor brevis. Ad- 
 ductor longus, and the femoral and profunda vessels and obturator nerve; by its 
 posterior surface, with the great sciatic nerve, the Gluteus maximus. Biceps, Semi- 
 tendinosus, and Semimembranosus. By its superior or shortest border it lies 
 parallel with the Quadratus femoris, the internal circumflex artery passing between 
 them; by its internal or longest border, with the Gracilis, Sartorius, and fascia 
 lata; by its ex ernal or attached border it is inserted into the femur behind the Ad- 
 ductor brevis and Adductor longus, which separate it from the Vastus internus, 
 and in front of the Gluteus maximus and short head of the Biceps, which sep- 
 arate it from the A'astus externus. 
 
 Nerves. The three Adductor muscles and the Gracilis are supplied by the 
 third and fourth lumbar nerves through the obturator nerve; the Adductor mag- 
 nus receiving an additional branch from the sacral plexus through the great sciatic. 
 The Pectineus is supplied by the second, third, and fourth lumbar nerves through 
 the anterior crural, and by the accessory obturator, from the third lumbar, when 
 it exists. Occasionally it receives a branch from the obturator nerve.^ 
 
 Actions. — The Pectineus and three Adductors adduct the thigh powerfully; 
 they are especially used in horse exercise, the flanks of the horse being grasped 
 between the knees by the actions of these muscles. In consequence of the obliquity 
 of their insertion into the linea aspera they rotate the thigh outward, assisting 
 the external Rotators, and when the limb has been abducted they draw it inward, 
 carrying the thigh across that of the opposite side. The Pectineus and Adductor 
 brevis and longus assist the Psoas and Iliacus in flexing the thigh upon the pelvis. 
 In progression, also, all these muscles assist in drawing forward the hinder limb. 
 The Gracilis assists the Sartorius in flexing the leg and rotating it inward; it is 
 also an adductor of the thigh. If the lower extremities are fixed, these muscles 
 may take their fixed point from below and act upon the pelvis, serving to maintain 
 the body in an erect posture, or, if their action is continued, to flex the pelvis 
 forward upon the femur. 
 
 Hunter's Canal (canalis adductorius [Hunteri]) extends from the apex of Scarpa's 
 triangle to the opening in the Adductor magnus muscle. The antero-internal 
 lx)undary or roof of Hunter's canal is the Sartorius and the aponeurotic expan- 
 sion from the Adductors to the Vastus internus. It is bounded externally by the 
 Vastus internus. The Adductor longus and Magnus constitute its floor or the 
 postero-internal boundary. The canal contains the femoral artery, femoral vein, 
 the long saphenous nerve, and the nerve to the Vastus internus. The anterior 
 opening of Hunter's canal is called the hiatus tendinous. 
 
 1 Professor Paterson describes the Pectineus as consisting of two incompletely separated strata, of which 
 the outer or dorsal stratum, which is constant, is supplied by the anterior crural nerve, or in its absence by the 
 accessory obturator, with which it is intimately related; while the inner or ventral stratum, when present, is 
 supplied by the obturator nerve. — Journ. of Anat. and Phys., vol. xxvi. p. 43. — Ed. of 15th lOnglish edition. 
 
522 
 
 THE MUSCLES AND FASCIJE 
 
 Surgical Anatomy. — The Adductor longus is liable to be severely strained in those who ride 
 much on horseback, or its tendon to be ruptured by suddenly gripping the saddle. Occasionally, 
 especially in cowboys and cavalry soldiers, the tendon of insertion of the Adductor magnus 
 may become ossified, constituting the rider's bone. 
 
 THE MUSCLES AND FASCI.ffi OF THE HIP. 
 
 3. The Gluteal Region (Figs. 346, 347). 
 
 Gluteus maximus. Obturator internus. 
 
 Gluteus medius. Gemellus superior. 
 
 Gluteus minimus. Gemellus inferior. 
 
 Pyriformis. Quadratus femoris. 
 
 Obturator externus. 
 
 Dissection (Fig. 345). — The subject should be turned on its face, a block placed beneath 
 the pelvis to make the buttocks tense, and the limbs allowed to hang over the end of the table, 
 with the foot inverted and the thigh abducted. Make an incision through the integument along 
 
 the crest of the ilium to the middle of the sacrum, and 
 thence downward to the tip of the coccyx, and carry a 
 second incision from that point obliquely downward and 
 outward to the outer side of the thigh, four inches be- 
 low the great trochanter. The portion of integument 
 included between these incisions is to be removed in 
 1. Dissection of the direction shown in the figure. 
 gluteal region. 
 
 The Gluteus Maximus (m. glutceus maximus) 
 (Fig. 346), the most superficial muscle in the 
 gluteal region, is a very broad and thick, fleshy 
 mass of a quadrilateral shape, which forms the 
 prominence of the buttock. Its large size is one 
 of the most characteristic points in the mus- 
 cular system of man, connected as it is with 
 the power he has of maintaining the trunk in 
 the erect posture. In structure the muscle is 
 remarkably coarse, being made up of muscular 
 fasciculi lying parallel with one another, and 
 collected together into large bundles, separated 
 by deep cellular intervals. It arises from the 
 superior curved line of the ilium and the por- 
 tion of bone, including the crest, immediately 
 above and behind it; from the posterior sur- 
 face of the lower part of the sacrum, the side of 
 the coccyx, the aponeurosis of the Erector spinse 
 muscle, the great sacro-sciatic ligament, and 
 the fascia covering the Gluteus medius. The 
 fibres are directed obliquely downward and 
 outward; those forming the upper and large 
 portion of the muscle, together with the super- 
 ficial fibres of the lower portion, terminate in 
 a thick tendinous lamina, which passes across 
 the great trochanter and is inserted into the 
 fascia lata covering the outer side of the thigh; 
 the deeper fibres of the lower portion of the muscles are inserted into the rough 
 line leading from the great trochanter to the linea aspera between the Vastus 
 externus and Adductor magnus. 
 
 3. Back of thigh. 
 
 2. Popliteal space. 
 
 Jf. / Jf. Back of leg. 
 
 5 \ 5. Sole of foot 
 
 Fig. 345.- 
 
 -Dissection of lower extremity. 
 Posterior view. 
 
THE GLUTEAL REGION 523 
 
 Several synovial bursae are found in relation with this muscle. One of these 
 (bursa trochanterica m. glutwi maximi), of large size, and generally multilocular, 
 separates it from the great trochanter. A second (bursa ischiadica m. glutcBi 
 maximi), often wanting, is situated on the tuberosity of the ischium. A third 
 bursa is found between the tendon of this muscle and the Vastus externus. Two 
 or three small bursse (burs(B glutaofemorales) are placed between the tendon of 
 the muscle and the gluteal ridge. 
 
 Relations. — By its superficial surface, with a thin fascia, which separates it from 
 the subcutaneous tissue; by its deep surface, from above downward, with the ilium, 
 sacrum, coccyx, and great sacro-sciatic ligament, part of the Gluteus medius, 
 Pyriformis, Gemelli, Obturator internus, Quadratus femoris, the tuberosity of 
 the ischium, great trochanter, the origin of the Biceps, Semitendinosus, Semimem- 
 branosus, and Adductor magnus muscles. The superficial part of the gluteal 
 artery reaches the deep surface of the muscle by passing between th? Pyriformis 
 and the Gluteus medius; the sciatic and internal pudic vessels and nerves and 
 muscular branches from the sacral plexus issue from the pelvis below the Pyri- 
 formis. The first perforating artery and the terminal branches of the internal cir- 
 cumflex artery are also found under cover of the muscle. Its upper border is thin, 
 and connected with the Gluteus medius by the fascia lata. Its lower border is free 
 and prominent. 
 
 Dissection. — Divide the Gluteus maximus near its origin by a vertical incision carried from 
 its upper to its lower border; a cellular interval will be exposed, separating it from the Gluteus 
 medius and External rotator muscles beneath. The upper portion of the muscle is to be alto- 
 gether detached, and the lower portion turned outward; the loose areolar tissue filling up the 
 interspace between the trochanter major and tuberosity of the ischium being removed, the parts 
 already enumerated as exposed by the removal of this muscle will be seen. 
 
 The Gluteus Medius (m. glutoem medium) (Fig. 346) is a broad, thick, radiated 
 muscle, situated on the outer surface of the pelvis. Its posterior third is covered by 
 the Gluteus maximus; its anterior two-thirds by the fascia lata, which separates 
 it from the integument. It arises from the outer surface of the ilium, between the 
 superior and middle curved lines, and from the outer lip of that portion of the 
 crest which is between them ; it also arises from the dense fascia, the gluteal aponeu- 
 rosis, covering its outer surface. The fibres converge to a strong flattened tendon 
 which is inserted into the oblique line which traverses the outer surface of the 
 great trochanter. A synovial bursa (bursa trochanterica m. glutcei medii anterior) 
 separates the tendon of the muscle from the summit of the great trochanter. 
 There is frequently a bursa (bursa trochanterica m. glutcei medii posterior) between 
 the tendons of the Gluteus medius and Pyriformis. 
 
 Relations. — By its superficial surface, with the Gluteus maximus behind, the 
 Tensor fascife femoris and deep fascia in front; by its deep surface, with the Glu- 
 teus minimus and the gluteal vessels and superior gluteal nerve. Its anterior border 
 is blended with the Gluteus minimus. Its posterior border Hes parallel with the 
 Pyriformis, the gluteal vessels intervening. 
 
 This muscle should now be divided near its insertion and turned upward, when the Gluteus 
 minimus will be exposed. 
 
 The Gluteus Minimus (m. glutceu^ minimus) (Fig. 346), the smallest of the 
 three Glutei, is placed immediately beneath the preceding. It is fan-shaped, 
 arising from the outer surface of the ilium, between the middle and inferior 
 curved lines, and behind, from the margin of the great sacro-sciatic notch; the 
 fibres converge to the deep surface of a radiated aponeurosis, which, terminating 
 in a tendon, is inserted into an impression on the anterior border of the great 
 trochanter. 
 
524 
 
 THE MUSCLES AND FASCIA 
 
 Inner hamstring 
 tendons. 
 
 SEMIMI 
 
 NOSUS 
 
 Fig. 346. — Muscles of the hip and thigh. 
 
 Relations. — By its superficial 
 surf ace, vi'ith. the Gluteus medius 
 and the gluteal vessels and supe- 
 rior gluteal nerve; by its deep 
 surface, with the ilium, the re- 
 flected tendon of the Rectus 
 femoris, and the capsular liga- 
 ment of the hip-joint. Its ante- 
 rior margin is blended with the 
 Gluteus medius; its posterior 
 margin is in contact and some- 
 times joined with the tendon of 
 the Pyriformis. There is a 
 synovial bursa {bursa m. glutoei 
 minimi) between the tendon of 
 the Gluteus minimus and the 
 great trochanter. 
 
 The Pyriformis (to. pirifor- 
 mis) (Figs. 346 and 347) is 
 a flat muscle, pyramidal in 
 shape, lying almost parallel 
 with the posterior margin of the 
 Gluteus medius. It is situated 
 partly within the pelvis at its 
 posterior part and partly at the 
 back of the hip-joint. It arises 
 from the front of the sacrum 
 by three fleshy digitations at- 
 tached to the portions of bone 
 between the first, second, third, 
 and fourth anterior sacral fora- 
 mina, and also from the groove 
 leading from the foramina: a 
 few fibres also arise from the 
 margin of the great sacro-sciatic 
 foramen and from the anterior 
 surface of the great sacro-sciatic 
 ligament. The muscle passes 
 out of the pelvis through the 
 great sacro-sciatic foramen, the 
 upper part of which it fills, and 
 is inserted by a rounded tendon 
 into the upper border of the 
 great trochanter, behind, but 
 often partly blended with, the 
 tendon of the Obturator in- 
 ternus and Gemelli muscles. 
 
 Relations. — By its anterior 
 surface, within the pelvis, with 
 the Rectum (especially on the 
 left side), the sacral plexus of 
 nerves, and the branches of the 
 internal iliac vessels; external 
 to the pelvis, with the posterior 
 
THE GLUTEAL REGION 525 
 
 surface of the ischium and the capsular ligament of the hip-joint; by its 'posterior 
 surface, within the pelvis, with the sacrum, and external to i^, with the Gluteus 
 maximus; by its upper border, with the Gluteus medius, from which it is 
 separated by the gluteal vessels and superior gluteal nerve; by its loiver border, 
 with the Gemellus superior and Coccygeus, the sciatic vessels and nerves, the 
 internal pudic vessels and nerve, and muscular branches from the sacral plexus, 
 passing from the pelvis in the interval between the two muscles. There is 
 usually a bursa {bursa m. piriformis) between the tendon of the pyriforaiis and 
 the ilium. 
 
 The Obturator Membrane (membrana obturatoria) (Fig. 215) is a thin layer of 
 interlacing fibres which closes almost completely the obturator foramen. It is 
 attached, externally, to the margin of the foramen; internally, to the posterior 
 surface of the ischio-pubic ramus, below and internal to the margin of the 
 foramen. It presents at its upper and outer part a small canal, obturator canal 
 {canalis obturator iu^s) for the passage of the obturator vessels and nerve. Both 
 obturator muscles are connected with this membrane. 
 
 Dissection. — The next muscle, as well as the origin of the Pyriformis, can only be seen when 
 the pelvis is divided and the viscera removed. 
 
 The Obturator Intemus(Figs. 346 and 347) , like the preceding muscle, is situated 
 partly within the cavity of the pelvis, and partly at the back of the hip-joint. It arises 
 from the inner surface of the anterior and external wall of the pelvis, where it sur- 
 rounds the greater part of the obturator foramen, being attached to the descending 
 ramus of the os pubis and the ramus of the ischium, and at the side to the inner sur- 
 face of the innominate bone below and behind the pelvic brim, reaching from the 
 upper part of the great sacro-sciatic foramen above and behind to the thyroid 
 foramen below and in front. It also arises from the inner surface of the obturator 
 membrane except at its posterior part, from the tendinous arch which completes 
 the canal for the passage of the obturator vessels and nerve and to a slight extent 
 from the obturator layer of the pelvic fascia, which covers it. The fibres converge 
 rapidly, and are directed backward and downward, and terminate in four or five 
 tendinous bands, which are found on its deep surface; these bands are reflected at 
 a right angle over the inner surface of the tuberosity of the ischium, which is 
 grooved for their reception; the groove is covered with cartilage, and lined by a 
 synovial bursa {bursa m. obturatoris interni). The muscle leaves the pelvis by 
 the lesser sacro-sciatic foramen ; and the tendinous bands unite into a single flat- 
 tened tendon, which passes horizontally outward, and, after receiving the attach- 
 ment of the Gemelli, is inserted into the forepart of the inner surface of the great 
 trochanter in front of the Obturator externus. A synovial bursa, narrow and 
 elongated in form, is usually found between the tendon of this muscle and the 
 capsular ligament of the hip: it occasionally communicates with the bursa 
 between the tendon and the tuberosity of the ischium, the two forming a 
 single sac. 
 
 In order to display the peculiar appearances presented by the tendon of this muscle, it must 
 be divided near its insertion and reflected inward. 
 
 Relations. — Within the pelvis this muscle is in relation, by its anterior surface, 
 with the obturator membrane and inner surface of the anterior wall of the pelvis; 
 by its posterior surface, with the pelvic and obturator fasciae, which separate it 
 from the Levator ani; and it is crossed by the internal pudic vessels and nerve. 
 This surface forms the outer boundary of the ischio-rectal fossa (Fig. 339). 
 External to the pelvis it is covered by the Gluteus maximus, is crossed by the 
 great sciatic nerve, and rests on the back part of the hip-joint. As the tendon 
 of the Obturator internus emerges from the lesser sacro-sciatic foramen it is over- 
 
526 
 
 THE MUSCLES AND FASCIA 
 
 lapped by the two Gemelli, while nearer its insertion the Gemelli pass in front of it 
 and form a groove in which the tendon lies. 
 
 The Gemelli (Fig. 346) are two small muscular fasciculi, accessories to the 
 tendon of the Obturator internus, which is received into a groove between them. 
 They are called superior and inferior. 
 
 The Gemellus Supenor, the smaller of the two, arises from the outer surface 
 of the spine of the ischium, and, passing horizontally outward, becomes blended 
 
 Fig. 347. — Muscles of the small or true pelvis on the right side, viewed from without and below. (Spalteholz.) 
 
 with the upper part of the tendon of the Obturator internus, and is inserted with 
 
 it into the inner surface of the great trochanter. This muscle is sometimes wanting. 
 
 Relations. — By its superficial surface, with the Gluteus maximus and the sciatic 
 
 vessels and nerves; by its deep surface, with the capsule of the hip-joint; by its 
 
THE GLUTEAL BEGION 
 
 527 
 
 upper border, with the lower margin of the Pyriformis; by its lower border, with 
 the tendon of the Obturator internus. 
 
 The Gemellus Inferior arises from the upper part of the tuberosity of the ischium, 
 where it forms the lower edge of the groove for the Obturator internus tendon, 
 and, passing horizontally outward, is blended with the lower part of the tendon 
 of the Obturator internus, and is inserted with it into the inner surface of the great 
 trochanter. 
 
 Relations. — By its superficial surface, with the Gluteus maximus and the sciatic 
 vessels and nerves; by its deep surface, with the scapular ligament of the hip-joint; 
 by its upper border, with the tendon of the Obturator internus; by its lower border, 
 with the tendon of the Obturator externus and Quadratus femoris. 
 
 The Quadratus Femoris (Fig. 346) is a short, flat muscle, quadrilateral in shape 
 (hence its name), situated between the Gemellus inferior and the upper margin 
 of the Adductor magnus. It arises from the upper part of the external lip of the 
 tuberosity of the ischium, and, proceeding horizontally outward, is inserted iato 
 the upper part of the linea quadrata ; that is, the line which crosses the posterior 
 intertrochanteric line. A synovial bursa is often found between the under surface 
 of this muscle and the lesser trochanter, which it covers. 
 
 Obturator 
 artery. 
 
 Anterior division of 
 obturator nerve. 
 
 Antenor inferior 
 iliac spine. 
 
 Posterior division 
 of obturator 
 nerve. 
 
 Internal clrcum 
 flex artery 
 
 liga- 
 partly 
 away. 
 
 Fig. 348. 
 
 -Obturator externus muscle. (From a preparation in the Museum of the Royal College of 
 Surgeons of England.) 
 
 Relations. — By its posterior surface, with the Gluteus maximus and the sciatic 
 vessels and nerves; by its anterior surface, with the tendon of the Obturator exter- 
 nus and trochanter minor and with the capsule of the hip-joint; by its upper 
 border, with the Gemellus inferior. Its lower border is separated from the Adductor 
 magnus by the terminal branches of the internal circumflex vessels. 
 
 Dissection. — In order to expose the next muscle (the Obturator externus) it is necessary 
 to remove the Psoas, IHacus, Pectineus, and Adductor brevis and longus muscles from the front 
 
528 THE MUSCLES AND FASCIA 
 
 and inner side of the thigh, and the Gluteus maximus and Quadratus femoris from the back 
 part. Its dissection should, consequently, be postponed until the muscles of the anterior and 
 internal femoral regions have been explained. 
 
 The Obturator Externus (Figs. 347 and 348) is a flat, triangular muscle, which 
 covers the outer surface of the anterior wall of the pelvis. It arises from the margin 
 of bone immediately around the inner side of the obturator foramen — viz., from the 
 body and ramus of the os pubis and the ramus of the ischium ; it also arises from 
 the inner two-thirds of the outer surface of the obturator membrane, and from 
 the tendinous arch which completes the canal for the passage of the obturator 
 vessels and nerves. The fibres from the pubic arch extend on to the inner sur- 
 face of the bone, from which they obtain a narrow origin between the margin of 
 the foramen and the attachment of the membrane. The fibres converging 
 pass backward, outward, and upward, and terminate in a tendon which runs 
 across the back part of the hip-joint, and is inserted into the digital fossa of the 
 femur. 
 
 Relations. — By its anterior surface, with the Psoas, Iliacus, Pectineus, Adductor 
 magnus, and Adductor brevis; and more externally, with the neck of the femur 
 and capsule of the hip-joint. The obturator artery and vein lie between this 
 muscle and the obturator membrane; the superficial part of the obturator nerve 
 lies above the muscle, and the deep branch perforates it; by its 'posterior surface , 
 with the obturator membrane and Quadratus femoris. 
 
 Nerves. — ^The Gluteus maximus is supplied by the fifth lumbar and first and 
 second sacral nerves through the inferior gluteal nerve from the sacral plexus; 
 the Gluteus medius and minimus, by the fourth and fifth lumbar and first sacral 
 nerves through the superior gluteal; the Pyriformis is supplied by the first and 
 second sacral nerves; the Gemellus inferior and Quadratus femoris by the last 
 lumbar and first sacral nerve; the Gemellus superior and Obturator internus by 
 the fifth lumbar and first and second sacral nerves, and the Obturator externus 
 by the second, third, and fourth lumbar nerves through the obturator. 
 
 Actions. — ^The Gluteus maximus, when it takes its fixed point from the pelvis, 
 extends the femur and brings the bent thigh into a line with the body. Taking 
 its fixed point from below, it acts upon the pelvis, supporting it and the whole 
 trunk upon the head of the femur, which is especially obvious in standing on one 
 leg. Its most powerful actions are to hold the head of the femur in close approxi- 
 mation to the acetabulum in walking and to cause the body to regain the erect 
 position after stooping by drawing the pelvis backward, being assisted in this action 
 by the Biceps, Semitendinosus, and Semimembranosus. The Gluteus maximus 
 is a tensor of the fascia lata, and by its connection with the ilio-tibial band it steadies 
 the femur on the articular surface of the tibia during standing, when the Extensor 
 muscles are relaxed. The lower part of the muscle also acts as an adductor and 
 external rotator of the limb. The Gluteus medius and minimus abduct the thigh 
 when the limb is extended, and are principally called into action in supporting 
 the body on one limb, in conjunction with the Tensor fascipe femoris. Their 
 anterior fibres, by drawing the great trochanter forward, rotate the thigh inward, 
 in which action they are also assisted by the Tensor fascite femoris. The remain- 
 ing muscles are powerful rotators of the thigh outward. In the sitting posture, 
 when the thigh is flexed upon the pelvis, their action as rotators cease, and they 
 become abductors, with the exception of the Obturator externus, which still 
 rotates the femur outward. When the femur is fixed, the Pyriformis and Obturator 
 muscles serve to draw the pelvis forward if it has been inclined backward, and 
 assist in steadying it upon the head of the femur. 
 
 Surgical Anatomy. — The fascia over the gluteal region is extremely dense and an abscess 
 beneath it may pass far down into the thigh. 
 
THE POSTERIOR FEMORAL REGION 
 
 529 
 
 4. The Posterior Femoral Region. 
 
 Biceps. Semitendinosus. Semimembranosus. 
 
 {Hamstring muscles.) 
 
 Dissection (Fig. 345).— Make a vertical incision along the middle of the back of the thigh, 
 from the lower fold of the buttock to about three inches below the back of the knee-joint, and 
 there connect it with a transverse incision, carried from the inner to the outer side of the leg. 
 Make a third incision transversely at the junction of the middle with the lower third of the 
 thigh. The integument having been removed from the back of the knee, and the boundaries 
 of the popliteal space having been examined, the removal of the integument from the remaining 
 T>art of the thigh should be continued, when the fascia and muscles of this region will be exposed. 
 
 BURSA OF 
 SCMIMCMBRANOSUS 
 
 BURSA OF 
 
 APONEUROTIC 
 
 EXPANSION 
 
 OF SARTORIUS 
 
 Fig. 349. — Region of the knee, seen obliquely from behind and within. Right limb. (Toldt.) 
 
 The Biceps or Biceps Flexor Cruris (m. biceps femoris) is a large muscle, of 
 considerable length, situated on the posterior and outer aspect of the thigh 
 (Figs. 346 and 349). It ariseshy two heads. One, the long head (caput longum), 
 arises from the lower and inner impression on the back part of the tuberosity 
 
 34 
 
530 THE MUSCLES AND FASCIA 
 
 of the ischium, by a tendon common to it and the Semitendinosus, and from 
 the lower part of the great sacro-sciatic Hgament. Between this tendon of 
 origin and the Semimembranosus there is often a bursa (bursa m. bicipitis 
 femoris superior). The femoral, or short head (caput breve), arises from the 
 outer Hp of the Hnea aspera, between the Adductor magnus and Vastus externus, 
 extending up almost as high as the insertion of the Gluteus maximus; from 
 the outer prolongation of the linea aspera to within two inches of the outer con- 
 dyle, and from the external intermuscular septum. The fibres of the long head 
 form a fusiform belly, which, passing obliquely downward and a little out- 
 ward, terminates in an aponeurosis which covers the posterior surface of the 
 muscle, and receives the fibres of the short head: this aponeurosis becomes 
 gradually contracted into a tendon, which is inserted into the outer side of the 
 head of the fibula, and by a small slip into the lateral surface of the external 
 tuberosity of the tibia. At its insertion the tendon divides into two portions, which 
 embrace the long external lateral ligament of the knee-joint. From the posterior 
 border of the tendon a thin expansion is given off to the fascia of the leg. The 
 tendon of this muscle forms the outer hamstring. Sometimes there is a bursa 
 (bursa bicipitogastrocnemialis) between the tendon of insertion of the Biceps and 
 the origin of the Gastrocnemius, and there is a bursa (bursa m. bicipitis femoris 
 inferior) between the tendon of the biceps and the external lateral ligament. 
 
 Relations. — By its superficial surface, with the Gluteus maximus and the small 
 sciatic nerve, the fascia lata, and integument. By its deep surface, with the Semi- 
 membranosus, Adductor magnus, and Vastus externus, the great sciatic nerve, 
 and, near its insertion, with the external head of the Gastrocnemius, the Plantaris, 
 the superior external articular artery, and the external popliteal nerve. 
 
 The Semitendinosus (Figs. 346 and 349), remarkable for the great length 
 of its tendon, is situated at the posterior and inner aspect of the thigh. It 
 arises from the lower and inner impression on the tuberosity of the ischium 
 by a tendon common to it and the long head of the Biceps ; it also arises from 
 an aponeurosis which connects the adjacent surfaces of the two muscles to 
 the extent of about three inches after their origin. There is a bursa (bursa 
 m. bicipitis femoris superior) between the tendons of origin of the Biceps and 
 Semitendinosus on one side and the tendon of origin of the Semimembranosus 
 on the other. The Semitendinosus is a fusiform muscle, which, passing down- 
 ward and inward, terminates a little below the middle of the thigh in a long 
 round tendon which lies along the inner side of the popliteal space, then 
 curves around the inner tuberosity of the tibia, and is inserted into the upper 
 part of the inner surface of the shaft of that bone nearly as far forward as its 
 anterior border. At its insertion it gives off from its lower border a prolongation 
 to the deep fascia of the leg. This tendon lies behind the tendon of the Sar- 
 torius, and below that of the Gracilis, to which it is united. A tendinous inter- 
 section is usually observed about the middle of the muscles. The bursa anserina 
 lies between the tendon of the Semitendinosus and the tibia. This bursa was 
 referred to in speaking of the Gracilis, p. 519. 
 
 Relations. — By its superficial surface, with the Gluteus maximus and fascia lata; 
 by its deep surface, with the Semimembranosus, Adductor magnus, inner head of 
 the Gastrocnemius, and internal lateral ligament of the knee-joint. 
 
 The Semimembranosus (Figs. 346 and 349), so called from its membranous 
 tendon of origin, is situated at the back part and inner side of the thigh. It 
 arises by a thick tendon from the upper and outer impression on the back part 
 of the tuberosity of the ischium, above and to the outer side of the Biceps and 
 Semitendinosus, and is inserted into the groove on the inner and back part of the 
 inner tuberosity of the tibia, beneath the internal lateral ligament. The tendon of 
 the muscle at its origin expands into an aponeurosis which covers the upper part 
 
THE ANTERIOR TIBIO- FIBULAR REGION 531 
 
 of its anterior surface: from this aponeurosis muscular fibres arise, and converge 
 to another aponeurosis, which covers the lower part of its posterior surface and 
 contracts into the tendon of insertion. The tendon of the muscle at its insertion 
 o;ives off certain fibrous expansions; one of these, of considerable size, passes 
 upward and outward to be inserted into the back part of the outer condyle of 
 the femur, forming part of the posterior ligament of the knee-joint; a second is 
 continued downward to the fascia which covers the Popliteus muscle. The 
 tendon also sends a few fibres to join the internal lateral ligament of the joint. 
 
 The tendons of the two preceding muscles, with that of the Gracilis, form 
 the inner hamstrings. 
 
 Relations.— By its superficial surface, with the Gluteus maximus, Semitendinosus, 
 Biceps, and fascia lata; by its deep surface, with the origin of the Quadratus 
 femoris, popliteal vessels. Adductor magnus, and inner head of the Gastroc- 
 nemius; by its inner border, with the Gracilis; by its outer border, with the great 
 sciatic nerve, and its internal popliteal branch. There is a bursa between the 
 Gastrocnemius and Semimembranosus and another bursa between the Semi- 
 membranosus and the inner condyle of the tibia. The first bursa usually com- 
 municates with the knee-joint. These two bursae are in communication and in 
 reality constitute a double bursa (bursa m. semimembranosi) . 
 
 Nerves. — The muscles of this region are supplied by the first, second, and 
 third sacral nerves through the great sciatic nerve. 
 
 Actions. — The hamstring muscles flex the leg upon the thigh. When the knee 
 is semiflexed, the Biceps, in consequence of its obhque direction downward and 
 outward, rotates the leg slightly outward; and the Semitendinosus, and to a 
 slight extent the Semimembranosus, rotate the leg inward, assisting the Popliteus. 
 Taking their fixed point from below, these muscles, especially the Semimem- 
 branosus, serve to support the pelvis upon the head of the femur and to draw 
 the trunk directly backward, as in raising it from the stooping position or in 
 feats of strength, when the body is thrown backward in the form of an arch. 
 When the leg is extended on the thigh, they limit the amount of flexion of the 
 trunk on the lower limbs. 
 
 Surgical Anatomy. — The hamstring tendons are occasionally ruptured. In disease of the 
 knee-joint the hamstrings may contract, flexing the knee, drawing the tibia backward, and some- 
 times causing incomplete dislocation. The tendons of these muscles occasionally require sub^ 
 cutaneous division in some forms of spurious ankylosis of the knee-joint dependent upon 
 permanent contraction and rigidity of the Flexor muscles, or from stiffening of the ligamentous 
 and other tissues surrounding the joint, the result of disease. Division of a tendon is effected 
 by putting the tendon upon the stretch, and inserting a narrow sharp-pointed knife between 
 it and the skin: the cutting edge being then turned toward the tendon, it should be divided, 
 taking great care that the wound in the skin is not at the same time enlarged. The relation of the 
 external popliteal nerve to the tendon of the Biceps must always be borne in mind in dividing this 
 tendon. 
 
 III. MUSCLES AND FASCIA OF THE LEG. 
 
 These may be divided into three groups: those on the anterior, those on the 
 posterior, and those on the outer side of the leg. 
 
 5. The Anterior Tibio-fibular Region (Fig. 350). 
 
 Tibialis anticus. Extensor longus digitorum. 
 
 Extensor proprius hallucis.^ Peroneus tertius. 
 
 ' There is no such word as ' 'Hallux, -cis." It is the result of some ignorant blunder, copied until it has become 
 established by usage; it has been thought better, therefore, to retain it. According to Lewis and Short, the 
 word is Allex, masculine; genitive, Allicis, the great toe, and the correct rendering would be Extensor pro- 
 prius allicis. It is a rare word, and is sometimes spelt, but not so correctly, "Hallex. It is used by Plautus, 
 in the "Pcenulus," V., v. 31. of a little man, as we might say "a hop-o'-my-thumb." "Tunc hie amator audes 
 esse, allex viri" (To think of you daring to make uo to her, you hop-o'-my-thumb!). The word "alex," some- 
 times spelt "allex," a fish sauce, is probably a different word altogether. It is used by Horace and Pliny. 
 — Ed. of 15th English edition. 
 
532 THE MUSCLES AND FASCIA 
 
 Dissection (Fig. 341). — The knee should be bent, a block placed beneath it, and the foot 
 kept in an extended position; then make an incision through the integument in the middle line 
 of the leg to the ankle, and continue it along the dorsum of the foot to the toes. Make a second 
 incision transversely across the ankle, and a third in the same direction across the bases of the 
 toes; remove the flaps of integument included between these incisions in order to examine the 
 deep fascia of the leg. 
 
 The Deep Fascia of the Leg (fascia cruris) forms a complete investment to 
 the muscles, but is not continuous over the subcutaneous surfaces of the bones. 
 It is continuous above with the fascia lata, receiving an expansion from the tendon 
 of the Biceps on the outer side, and from the tendons of the Sartorius, Gracilis, 
 and Semitendinosus on the inner side; in front it blends with the periosteum 
 covering the subcutaneous surface of the tibia, and with that covering the head 
 and external malleolus of the fibula; below it is continuous with the annular liga- 
 ments of the ankle. It is thick and dense in the upper and anterior part of the leg, 
 and gives attachment, by its deep surface, to the Tibialis anticus and Extensor 
 longus digitorum muscles, but is thinner behind, where it covers the Gastrocnemius 
 and Soleus muscles. Over the popliteal space it is much strengthened by trans- 
 verse fibres which stretch across from the inner to the outer hamstring muscles, 
 and it is here perforated by the external saphenous vein. Its deep surface gives 
 off, on the outer side of the leg, two strong intermuscular septa which enclose the 
 Peronei muscles, and separate them from the muscles of the anterior and posterior 
 tibial regions. It also gives off several smaller and more slender processes 
 which enclose the individual muscles in each region; at the same time a broad 
 transverse intermuscular septum, called the deep transverse fascia of the leg, 
 intervenes between the superficial and deep muscles in the posterior tibio-fibular 
 region. 
 
 Remove the fascia by dividing it in the same direction as the integument, excepting opposite 
 the ankle, where it should be left entire. Commence the removal of the fascia from below, 
 opposite the tendons, and detach it in the line of direction of the muscular fibres. 
 
 The Tibialis Anticus (m. tibialis anterior) is situated on the outer side of the 
 tibia; it is thick and fleshy at its upper part, tendinous below. It arises from the 
 outer tuberosity and upper two-thirds of the external surface of the shaft of the 
 tibia; from the adjoining part of the interosseous membrane; from the deep 
 surface of the fascia; and from the intermuscular septum between it and the 
 Extensor longus digitorum: the fibres pass vertically downward, and terminate 
 in a tendon which is apparent on the anterior surface of the muscle at the lower 
 third of the leg. After passing through the innermost compartment of the anterior 
 annular ligament, it is inserted into the inner and under surface of the internal 
 cuneiform bone and base of the metatarsal bone of the great toe. There is 
 usually a bursa (bursa subtendinea m. tibialis anterioris) between the tendon of 
 the tibialis anticus and the internal cuneiform bone. 
 
 Relations. — By its anterior surface, with the fascia and with the annular liga- 
 ment; by its posterior surface, with the interosseous membrane, tibia, ankle-joint, 
 and inner side of the tarsus : this surface also overlaps the anterior tibial vessels 
 and nerve in the upper part of the leg. By its inner surface, with the tibia; by 
 its outer surface, with the Extensor longus digitorum and Extensor proprius 
 hallucis, and the anterior tibial vessels and nerve. 
 
 The Extensor Proprius Hallucis (m. extensor hallucis longus) is a thin, elon- 
 gated, and flattened muscle situated between the Tibialis anticus and Extensor 
 longus digitorum. It arises from the anterior surface of the fibula for about the 
 middle two-fourths of its extent, its origin being internal to that of the Extensor 
 longus digitorum ; it also arises from the interosseous membrane to a similar 
 extent. The fibres pass downward, and terminate in a tendon which occupies 
 
THE ANTEBIOll TIBIO- FIBULAR REGION 
 
 533 
 
 the anterior border of the muscle, passes through a 
 distinct compartment in the lower portion of the 
 annular ligament, crosses the anterior tibial vessels 
 near the bend of the ankle, and is inserted into the 
 base of the last phalanx of the great toe. Opposite 
 the metatarso-phalangeal articulation the tendon 
 gives off a thin prolongation on each side, which 
 covers the surface of the joint. It usually sends an 
 expansion from the inner side of the tendon, to be 
 inserted into the base of the first phalanx. 
 
 Relations. — By its anterior surface, with the fascia 
 and the anterior annular ligament; by its posterior 
 surface, with the interosseous membrane, fibula, 
 tibia, and ankle-joint; by its outer side, with the 
 Extensor longus digitorum above, the dorsalis pedis 
 vessels, anterior tibial nerve, and Extensor brevis 
 digitorum below; by its inner side, with the Tibialis 
 anticus and the anterior tibial vessels above. The 
 muscle is external to the anterior tibial vessels in 
 the upper part of the leg; but in the lower third its 
 tendon crosses over them, so that it lies internal to 
 them on the dorsum of the foot. 
 
 The Extensor Longus Digitorum (m. extensor 
 digitorum longus) is an elongated, flattened, penni- 
 form muscle situated the most externally of all the 
 muscles on the forepart of the leg. It arises from 
 the outer tuberosity of the tibia; from the upper 
 three-fourths of the anterior surface of the shaft of 
 the fibula; from the interosseous membrane; from 
 the deep surface of the fascia; and from the inter- 
 muscular septa between it and the Tibialis anticus 
 on the inner and the Peronei on the outer side. 
 The tendon enters a canal in the annular ligament 
 with the Peroneus tertius, and divides into four 
 slips, which run across the dorsum of the foot and 
 are inserted into the second and third phalanges of 
 the four lesser toes. The mode in which the tendons 
 are inserted is the following: Each of the three 
 inner tendons opposite the metatarso-phalangeal 
 articulation is joined, on its outer side, by a ten- 
 don from the Extensor brevis digitorum. The outer 
 tendon does not receive such a tendinous slip. They 
 all receive a fibrous expansion from the Interossei 
 and Lumbricales, and then spread out into a broad 
 aponeurosis, which covers the dorsal surface of the 
 first phalanx: this aponeurosis, at the articulation of 
 the first with the second phalanx, divides into three 
 slips — a middle one, which is inserted into the base 
 of the second phalanx, and two lateral slips, which, 
 after uniting on the dorsal surface of the second 
 phalanx, are continued onward, to be inserted into 
 the base of the third. 
 
 Relations. — By its anterior surface, with the fascia 
 and the annular ligament; by its posterior surface. 
 
 I A I, 4! 
 
 \hl' 
 
 trl'd' 
 
 Fig. 350.- 
 
 the front of 
 
534 THE 3IUSCLE8 AND FASCIA 
 
 with the fibula, interosseous membrane, ankle-joint, and Extensor brevis digi- 
 torum; by its inner side, with the Tibialis anticus. Extensor proprius hallucis, 
 and anterior tibial vessels and nerve ; by its outer side, with the Peroneus longus 
 and brevis. 
 
 The Peroneus Tertius {m. peronoeus tertius) is a part of the Extensor longus 
 digitorum, and might be described as its fifth tendon. The fibres belonging to 
 this tendon arise from the lower fourth of the anterior surface of the fibula, from 
 the lower part of the interosseous membrane, and from an intermuscular septum 
 between it and the Peroneus brevis. The tendon, after passing through the same 
 canal in the annular ligament as the Extensor longus digitorum, is inserted into 
 the dorsal surface of the base of the metatarsal bone of the little toe. This 
 muscle is sometimes wanting. 
 
 Nerves. — These muscles are supplied by the fourth and fifth lumbar and first 
 sacral nerves through the anterior tibial nerve. 
 
 Actions. — The Tibialis anticus and Peroneus tertius are the direct flexors of the 
 foot at the ankle-joint; the former muscle, when acting in conjunction with the 
 Tibialis posticus, raises the inner border of the foot {i.e., inverts the foot); and 
 the latter, acting with the Peroneus brevis and longus, draws the outer border of 
 the foot upward and the sole outward (i. e., everts the foot). The Extensor longus 
 digitorum and Extensor proprius hallucis extend the phalanges of the toes, and, 
 continuing their action, flex the foot upon the leg. Taking their fixed point from 
 below, in the erect posture, all these muscles serve to fix the bones of the leg in the 
 perpendicular position, and give increased strength to the ankle-joint. 
 
 6. The Posterior Tibio-fibular Region (Figs. 349, 352). 
 
 Dissection (Fig. 345). — Make a vertical incision along the middle line of the back of the 
 leg, from the lower part of the popliteal space to the heel, connecting it below by a transverse 
 incision extending between the two malleoli; the flaps of integument being removed, the fascia 
 and muscles should be examined. 
 
 The muscles in this region of the leg are subdivided into two layers — superficial 
 and deep. The superficial layer constitutes a powerful muscular mass, forming 
 the calf of the leg. Their large size is one of the most characteristic features of 
 the muscular apparatus in man, and bears a direct connection with his ordinary 
 attitude and mode of progression. 
 
 The Superficial Layer. 
 
 Gastrocnemius. Soleus. Plantaris. 
 
 The Gastrocnemius is the most superficial muscle, and forms the greater part 
 of the calf. It arises by two heads, which are connected to the condyles of the femur 
 by two strong flat tendons. The inner and larger head {caput inediale) arises from 
 a depression at the upper and back part of the inner condyle and from the 
 adjacent part of the femur. There is a bursa (bursa m. gastrocnemii mediahs) 
 between the tendon of origin and the inner condyle. The outer head (caput 
 laterale) arises from an impression on the outer side of the external condyle and 
 from the posterior surface of the femur immediately above the condyle. There 
 is a bursa (bursa m. gastrocnemii lateralis) between the tendon of origin and the 
 outer condyle. Both heads, also, arise by a few tendinous and fleshy fibres 
 from the ridges which are continued upward from the condyles to the linea aspera. 
 Each tendon spreads out into an aponeurosis, which covers the posterior surface 
 of that portion of the muscle to which it belongs ; the muscular fibres of the 
 inner head being thicker and extending lower than those of the outer. From 
 the anterior surface of these tendinous expansions muscular fibres are given off. 
 
THE POSTERIOR TIBIO- FIBULAR REGION 
 
 535 
 
 The fibres in the median line, which correspond to the accessory portions of the 
 muscle derived from the bifurcations of the linea aspera, unite at an angle 
 upon a median tendinous raphe below: the remaining fibres converge to an 
 aponeurosis which covers the anterior surface of the muscle, and this, gradually 
 contracting, unites with the tendon of the Soleus, and forms with it the tendo 
 Achillis. 
 
 Relations. — By its superficial surface, with the fascia of the leg, which separates 
 it from the external saphenous vein and nerve; by its deep surface, with the pos- 
 terior ligament of the knee-joint, the Popliteus, Soleus, Plantaris, popliteal vessels, 
 and internal popliteal nerve. The tendon of the inner head corresponds with the 
 back part of the inner condyle, from which it is separated by a synovial bursa, 
 which, in some cases, communicates with the cavity of the knee-joint. The 
 tendon of the outer head contains a sesamoid fibro-cartilage (rarely osseous) 
 where it plays over the corresponding outer condyle; and one is occasionally 
 found in the tendon of the inner head. 
 
 The Gastrocnemius should be divided across, just below its origin, and turned downward, 
 in order to expose the next two muscles. 
 
 The Soleus is a broad flat muscle situated immediately beneath the Gastroc- 
 nemius. It has received its name from its resemblance in shape to a sole-fish. It 
 arises by tendinous fibres from the back part of the head of the fibula and from 
 the upper third of the posterior surface of its shaft; 
 from the oblique line of the tibia and from the mid- 
 dle third of its internal border; some fibres also arise 
 from a tendinous arch placed between the tibial and 
 fibular origins of the muscle, beneath which the 
 popliteal vessels and internal popliteal nerve pass. 
 The fibres pass backward to an aponeurosis which 
 covers the posterior surface of the muscle, and this, 
 gradually becoming thicker and narrower, joins with 
 the tendon of the Gastrocnemius, and forms with it 
 the tendo Achillis. 
 
 The triceps surm is the designation in the new 
 nomenclature of the Gastrocnemius and Soleus. 
 
 Relations. — By its superficial surface, with the 
 Gastrocnemius and Plantaris; by its deep surface, 
 with the Flexor longus digitorum. Flexor longus 
 hallucis, Tibialis posticus, and posterior tibial 
 vessels and nerve, from which it is separated by 
 the transverse intermuscular septum or deep transverse fascia of the leg. 
 
 The Tendo Achillis (tendo calcaneus), the common tendon of the Gastrocnemius 
 and Soleus,^ is the thickest and strongest tendon in the body. It is about six 
 inches in length, and commences about the middle of the leg, but receives fleshy 
 fibres on its anterior surface nearly to its lower end. Gradually becoming con- 
 tracted below, it is inserted into the lower part of the posterior surface of the os 
 calcis, a synovial bursa, the retro-calcaneal bursa (bursa tendinis calcanei 
 [Achillis]) (Fig. 351), being interposed between the tendon and the upper part 
 of this surface. The tendon spreads out somewhat at its lower end, so that its 
 narrowest part is usually about an inch and a half above its insertion. The tendon 
 is covered by the fascia and the integument, a bursa (bursa svbcutanea calcanea) 
 (Fig.. 351) being often interposed between the tendon and the fascia. The tendon 
 
 BURSA BETWEEN 
 — FASCIA AND 
 TENDON 
 
 BURSA BETWEEN 
 TENDON AND 
 OS CALCIS 
 
 Fig. 351. — Bursse of the tendo 
 Achillis. (Poirier and Charpy.) 
 
 * These two muscles with a common tendon are by some anatomists classed together as one muscle, the 
 Trictps surx, the two heads of origin of the Gastrocnemius and the Soleus constituting the three heads of the 
 Triceps, and the tendo Achillis the single tendon of insertion. — Ed. of 15th English edition. 
 
536 
 
 THE MUSCLES AND FASCIA 
 
 is separated from the deep muscles and vessels by a considerable interval filled 
 up with areolar and adipose tissue. Along its outer side, but superficial to it, is 
 the external saphenous vein. 
 
 Tendons of 
 
 RONEUS LONGUS 
 
 and BREvis. 
 
 Femur. 
 
 ilti- 
 
 i>» 
 
 mkiVi 
 
 Fig. 352. — Muscles of the back of the leg. 
 Superficial layer. 
 
 Fig. 3.53. — Muscles of the back 
 of the leg. Deep layer. 
 
 The Plantaris is an extremely diminutive muscle placed between the Gas- 
 trocnemius and Soleus, and remarkable for its long and delicate tendon. It arises 
 
THE POSTERIOR TIBIO- FIBULAR REGION 537 
 
 from the lower part of the outer prolongation of the Unea aspera and from the pos- 
 terior Hgament of the knee-joint. It forms a small fusiform belly, about three or 
 four inches in length, terminating in a long slender tendon which crosses obliquely 
 between the two muscles of the calf, and, running along the inner border of the 
 tendo Achillis, is inserted with it into the posterior part of the os calcis. This 
 muscle is occasionally double, and is sometimes wanting. Occasionally its tendon 
 is lost in the internal annular ligament or in the fascia of the leg. 
 
 Nerves. — The Gastrocnemius is supplied by the first and second sacral nerves, 
 and the Plantaris by the fourth and fifth lumbar and first sacral nerves through the 
 internal pophteal. The Soleus is supplied by the fifth lumbar and first and second 
 sacral nerves through the internal popliteal and posterior tibial. 
 
 Actions.— The muscles of the calf are the chief extensors of the foot at the 
 ankle-joint. They possess considerable power, and are constantly called into use 
 in standing, walking, dancing, and leaping; hence the large size they usually pre- 
 sent. In walking these muscles draw powerfully upon the os calcis, raising the 
 heel, and with it the entire body, from the ground; the body being thus supported 
 on the raised foot, the opposite limb can be carried forward. In standing, the 
 Soleus, taking its fixed point from below, steadies the leg upon the foot, and pre- 
 vents the body from falling forward, to which there is a constant tendency from the 
 superincumbent weight. The Gastrocnemius, acting from below, serves to flex the 
 femur upon the tibia, assisted by the Popliteus. The Plantaris is the rudiment of 
 a large muscle which exists in some of the lower animals and is continued over the 
 OS calcis to be inserted into the plantar fascia. In man it is an accessory to the 
 Gastrocnemius, extending the ankle if the foot is free, or bending the knee if the 
 foot is fixed. Possibly, acting from below, by its attachment to the posterior liga- 
 ment of the knee-joint, it may pull that ligament backward during flexion, and so 
 protect it from being compressed between the two articular surfaces. 
 
 The Deep Layer (Fig. 353). 
 
 Popliteus. Flexor longus digitorum. 
 
 Flexor longus hallucis. Tibialis posticus. 
 
 Dissection. — Detach the Soleus from its attachment to the fibula and tibia, and turn it down- 
 ward, when the deep layer of muscles is exposed, covered by the deep transverse fascia of the 
 leg. 
 
 Deep Transverse Fascia. — The deep transverse fascia of the leg is a trans- 
 versely placed, intermuscular septum, between the superficial and deep muscles 
 in the posterior tibio-fibular region. On either side it is connected to the margins 
 of the tibia and fibula. Above, where it covers the Pophteus, it is thick and dense, 
 and receives an expansion from the tendon of the Semimembranosus ; it is thinner 
 in the middle of the leg, but below, where it covers the tendons passing behind the 
 malleoli, it is thickened and continuous with the internal annular ligament. 
 
 This fascia should now be removed, commencing from below opposite the tendons, and 
 detaching it from the muscles in the direction of their fibres. 
 
 The Popliteus (Fig. 349) is a thin, flat, triangular muscle, which forms part of 
 the floor of the popliteal space. It arises by a strong tendon, about an inch in 
 length, from a deep depression on the outer side of the external condyle of the 
 femur, and from the posterior ligament of the knee-joint. A bursa (bursa m. 
 poplifei) is placed between the condyle and the muscle. The muscle is inserted 
 into the inner two-thirds of the triangular surface above the oblique line on the 
 posterior surface of the shaft of the tibia, and into the tendinous expansion 
 covering the surface of the muscle. The tendon of the muscle is covered by 
 that of the Biceps and by the external lateral ligament of the knee-joint; it grooves 
 
538 THE MUSCLES AND FASCIA 
 
 the posterior border of the external semikmar fibro-cartilage, and is invested by 
 the synovial membrane of the knee-joint. 
 
 Relations. — By its superficial surface, with the fascia covering it, which separates 
 it from the Gastrocnemius, Plantaris, popliteal vessels, and internal pophteal nerve; 
 by its deep surface, with the knee-joint and back of the tibia. 
 
 The Flexor LongUS Hallucis (m. flexor halhicis longu^) is situated on the fibular 
 side of the leg, and is the most superficial and largest of the three next muscles. 
 It arises from the lower two-thirds of the posterior surface of the shaft of the 
 fibula, with the exception of an inch at its lowest part; from the lower part of 
 the interosseous membrane; from an intermuscular septum between it and the 
 Peronei, externally; and from the fascia covering the Tibialis posticus internally. 
 The fibres pass obliquely downward and backward, and terminate in a tendon 
 which occupies nearly the whole length of the posterior surface of the muscle. 
 This tendon occupies a groove on the posterior surface of the lower end of the 
 tibia; it then lies in a second groove on the posterior surface of the astragalus, and 
 finally in a third groove, beneath the sustentaculum tali of the os calcis, and 
 passes into the sole of the foot, where it runs forward between the two heads of 
 the Flexor brevis hallucis, and is mserted into the base of the last phalanx of the 
 great toe (Fig. 355). The grooves in the astragalus and os calcis, which contain 
 the tendon of the muscle, are converted by tendinous fibres into distinct canals 
 lined by synovial membrane; and as the tendon crosses the sole of the foot, it is 
 connected to the common flexor by a tendinous slip. 
 
 Relations. — By its superficial surface, with the Soleus and tendo Achillis, from 
 which it is separated by the deep transverse fascia; by its deep surface, with the 
 fibula. Tibialis posticus, the peroneal vessels, the lower part of the interosseous 
 membrane, and the ankle-joint; by its outer harder, with the Peronei; by its inner 
 border, with the Tibialis posticus and posterior tibial vessels and nerve. In the 
 sole of the foot it lies above the Abductor hallucis and Flexor longus digitorum. 
 
 The Flexor Longus Digitorum (m. flexor digitorum longus) is situated on 
 the tibial side of the leg. At its origin it is thin and pointed, but gradually 
 increases in size as it descends. It arises from the posterior surface of the shaft 
 of the tibia, immediately below the oblique line to within three inches of its 
 extremity, internal to the tibial origin of the Tibialis posticus; some fibres also 
 arise from the fascia covering the Tibialis posticus. The fibres terminate in a 
 tendon which runs nearly the whole length of the posterior surface of the muscle. 
 This tendon passes behind the internal malleolus in a groove, common to it and 
 the Tibialis posticus, but separated from the latter by a fibrous septum, each 
 tendon being contained in a special sheath lined by a separate synovial membrane. 
 It then passes obliquely forward and outward, superficial to the internal lateral 
 ligament, into the sole of the foot (Fig. 355), where, crossing superficially to the 
 tendon of the Flexor longus hallucis,^ to which it is connected by a strong 
 tendinous slip, it becomes expanded, is joined by the Flexor accessorius, and finally 
 divides into four tendons which are inserted into the bases of the last phalanges 
 of the four lesser toes, each tendon passing through a fissure in the tendon of the 
 Flexor brevis digitorum opposite the base of the first phalanges (Fig. 354). 
 
 Relations. — In the leg: by its super flcial surface, with the posterior tibial vessels 
 and nerve, and the deep transverse fascia, which separates it from the Soleus 
 muscle; by its deep surface, with the Tibia and Tibialis posticus. In the foot it is 
 covered by the Abductor hallucis and Flexor brevis digitorum, and crosses super- 
 ficial to the Flexor longus hallucis. 
 
 The Tibialis Posticus (m. tibialis posterior) lies between the two preceding 
 muscles, and is the most deeply seated of all the muscles in the leg. It com- 
 
 * That is, in the order of dissection of the sole of the foot. 
 
THE FIBULAR REGION 539 
 
 mences above by two pointed processes, separated by an angular interval, 
 through which the anterior tibial vessels pass forward to the front of the leg. 
 It arises from the whole of the posterior surface of the interosseous membrane, 
 excepting its lowest part, from the outer portion of the posterior surface of the 
 shaft of the tibia, between the commencement of the oblique line above, and the 
 junction of the middle and lower third of the shaft below; and from the upper 
 two-thirds of the internal surface of the fibula; some fibres also arise from the 
 deep transverse fascia and from the intermuscular septa, separating it from the 
 adjacent muscles on each side. This muscle, in the lower fourth of the leg, 
 passes in front of the Flexor longus digitorum, and terminates in a tendon which 
 passes through a groove behind the inner malleolus with the tendon of that 
 muscle, but enclosed in a separate sheath ; it then passes through another sheath, 
 over the internal lateral ligament into the foot, and then beneath the inferior 
 calcaneo-scaphoid ligament, and is inserted into the tuberosity of the scaphoid 
 and internal cuneiform bones (Fig. 356). The tendon of this muscle contains a 
 sesamoid fibro-cartilage as it passes over the scaphoid bone, and gives off fibrous 
 expansions, one of which passes backward to the sustentaculum tali of the os calcis, 
 others outward to the middle and external cuneiform and cuboid, and some 
 forward to the base of the second, third, and fourth metatarsal bones (Fig. 355). 
 
 Relations. — By its superficial surface, with the Soleus, from which it is separated 
 by the deep transverse fascia, the Flexor longus digitorum, the posterior tibial 
 vessels and nerve, and the peroneal vessels; by its deep surface, with the inter- 
 osseous ligament, the tibia, fibula, and ankle-joint. 
 
 Nerves. — The Popliteus is supplied by the fourth and fifth lumbar and first sacral 
 nerves, through the internal popliteal; the Flexor longus digitorum and Tibialis 
 posticus by the fifth lumbar and first sacral; and the Flexor longus hallucis by the 
 fifth lumbar and first and second sacral nerves through the posterior tibial. 
 
 Actions. — The Popliteus assists in flexing the leg upon the thigh; when the leg 
 is flexed, it will rotate the tibia inward. It is especially called into action at the 
 commencement of the act of bending the knee, inasmuch as it produces a slight 
 inward rotation of the tibia, which is essential in the early stage of this movement. 
 The Tibialis posticus is a direct extensor of the foot at the ankle-joint; acting in 
 conjunction with the Tibialis anticus, it turns the sole of the foot inward (i. e., 
 inverts the foot), antagonizing the Peronei, which turn it outward (evert it). In 
 the sole of the foot the tendon of the Tibialis posticus lies directly below the inferior 
 calcaneo-scaphoid ligament, and is therefore an important factor in maintaining 
 the arch of the foot. The Flexor longus digitorum and Flexor longus hallucis are 
 the direct flexors of the phalanges, and, continuing their action, extend the foot 
 upon the leg; they assist the Gastrocnemius and Soleus in extending the foot, as in 
 the act of walking or in standing on tiptoe. In consequence of the oblique direction 
 of the tendon of the long flexor the toes would be drawn inward were it not for the 
 Flexor accessorius muscle, which is inserted into the outer side of its tendon and 
 draws it to the middle line of the foot during its action. Taking their fixed point 
 from the foot, these muscles serve to maintain the upright posture by steadying 
 the tibia and fibula perpendicularly upon the ankle-joint. They also serve to raise 
 these bones from the oblique position they assume in the stooping posture. 
 
 7. The Fibular Region (Fig. 353). 
 Peroneus longus. Peroneus brevis. 
 
 Dissection. — The muscles are readily exposed by removing the fascia covering their surface, 
 from below upward, in the line of direction of their fibres. 
 
 The Peroneus Longus (m. peronoeu^ longu^s) is situated at the upper part of 
 the outer side of the leg, and is the more superficial of the two muscles. It arises 
 
540 THE 3IUSCLES AND FASCIA 
 
 from the head and upper two-thirds of the outer surface of the shaft of the fibula, 
 from the deep surface of the fascia, and from the intermuscular septa between it 
 and the muscles on the front, and those on the back of the leg, occasionally also 
 by a few fibres from the outer tuberosity of the tibia. Between its attachment 
 to the head and to the shaft of the fibula there is a small interval of bone from 
 which no muscular fibres arise ; through this gap the external popliteal nerve passes 
 beneath the muscle. The muscle terminates in a long tendon, which passes behind 
 the outer malleolus, in a groove common to it and the tendon of the Peroneus 
 brevis, behind which it lies, the groove being converted into a canal by a fibrous 
 band, and the tendons being invested by a common synovial membrane; it is 
 then reflected obliquely forward across the outer side of the os calcis, below its 
 peroneal tubercle, being contained in a separate fibrous sheath, lined by a pro- 
 longation of the synovial membrane which lines the groove behind the malleolus. 
 Having reached the outer side of the cuboid bone, it runs in a groove on the 
 under surface of that bone, which is converted into a canal by the long calcaneo- 
 cuboid ligament, and is lined by a synovial membrane: the tendon then crosses 
 the sole of the foot obliquely, and is inserted into the outer side of the base of the 
 metatarsal bone of the great toe and the internal cuneiform bone (Figs. 355 and 
 356). Occasionally it sends a slip to the base of the second metatarsal bone. The 
 tendon changes its direction at two points: first, behind the external malleolus; 
 secondly, on the outer side of the cuboid bone; in both of these situations the 
 tendon is thickened, and in the latter a sesamoid fibro-cartilage, or sometimes a 
 bone, is usually developed in its substance. 
 
 Relations. — By its superficial surface, with the fascia and integument; by its 
 deep surface, with the fibula, external popliteal nerve, the Peroneus brevis, os 
 calcis, and cuboid bone; by its anterior border, with an intermuscular septum,, 
 which intervenes between it and the Extensor longus digitorum; by its posterior 
 border, with an intermuscular septum, which separates it from the Soleus above 
 and the Flexor longus hallucis below. 
 
 The Peroneus Brevis (w. peronceus brevis) lies beneath the Peroneus longus, 
 and is shorter and smaller than it. It arises from the lower two-thirds of the 
 external surface of the shaft of the fibula, internal to the Peroneus longus, and 
 from the intermuscular septa separating it from the adjacent muscles on the front 
 and back part of the leg. The fibres pass vertically downward, and terminate in 
 a tendon which runs in front of that of the preceding muscle through the same 
 groove, behind the external malleolus, being contained in the same fibrous 
 sheath and lubricated by the same synovial membrane. It then passes through 
 a separate sheath on the outer side of the os calcis, above that for the tendon of 
 the Peroneus longus, the two tendons being here separated by the peroneal 
 tubercle, and is finally inserted into the tuberosity at the base of the metatarsal 
 bone of the little toe, on its outer side. 
 
 Relations. — By its superficial surface, with the Peroneus longus and the fascia 
 of the leg and foot; by its deep surface, with the fibula and outer side of the os 
 calcis. 
 
 Nerves. — The Peroneus longus and brevis are supplied by the fourth and fifth 
 lumbar and first sacral nerves through the musculo-cutaneous branch of the 
 external popliteal nerve. 
 
 Actions. — The Peroneus longus and brevis extend the foot upon the leg, in 
 conjunction with the Tibialis posticus, antagonizing the Tibialis anticus and 
 Peroneus tertius, which are flexors of the foot. The Peroneus longus also everts 
 the sole of the foot; hence the extreme eversion occasionally observed in fracture 
 of the lower end of the fibula, where that bone offers no resistance to the action 
 of this muscle. From the oblique direction of the Peroneus longus tendon across 
 the sole of the foot it is an important agent in the maintenance of the transverse 
 
OF THE FOOT 544 
 
 arch of the foot. Taking their fixed point below, the Peronei serve to steady the 
 leg upon the foot. This is especially the case in standing upon one leg, when 
 the tendency of the superincumbent weight is to throw the leg inward: the 
 Peroneus longus overcomes this tendency by drawing on the outer side of the 
 leg, and thus maintains the perpendicular direction of the limb. 
 
 Surgical Anatomy. — The student should now consider the position of the tendons of the 
 various muscles of the leg, their relation with the ankle-joint and surrounding blood-vessels, and 
 especially their action upon the foot, as their rigidity and contraction give rise to one or other of 
 the kinds of deformity known as club-foot. The most simple and common deformity, and one 
 that is rarely, if ever, congenital, is the talipes equinus, the heel being raised by rigidity and con- 
 traction of the Gastrocnemius muscle, and the patient walking upon the ball of the foot. In the 
 talipes varus the foot is forcibly adducted and the inner side of the sole raised, sometimes to a 
 right angle with the ground, by the action of the Tibialis anticus and posticus. In the talipes 
 valgus the outer edge of the foot is raised by the Peronei muscles, and the patient walks on the 
 inner ankle. In the talipes calcaneus the toes are raised by the Extensor muscles, the heel is 
 depressed, and the patient walks upon it. Other varieties of deformity are met with, as the 
 talipes equino-varus, equino-valgus , and calcaneo-valgus, whose names sufficiently indicate their 
 nature. Of these, the talipes equino-varus is the most common congenital form: the heel is 
 raised by the tendo Achillis, the inner border of the foot drawn upward by the Tibialis anticus, 
 the anterior two-thirds twisted inward by the Tibialis posticus, and the arch increased by the 
 contraction of the plantar fascia, so that the patient walks on the middle of the outer border of 
 the foot. Each of these deformities may sometimes be successfully relieved by division of the 
 opposing tendons and fascia ; by this means the foot regains its proper position, and the tendons 
 subsequently heal. The operation is easily performed by putting the contracted tendon upon 
 the stretch, and dividing it by means of a narrow, sharp-pointed knife inserted beneath it. 
 Pes cavus or hollow foot is accentuation of the longitudinal arch. Pes planus or flat-foot has 
 been discussed elsewhere. 
 
 Rupture of a few of the fibres of the Gastrocnemius may take place. Rupture of the Plantaris 
 tendon not uncommonly occurs, especially in men somewhat advanced in life, from some sudden 
 exertion, and frequently occurs during the game of lawn tennis, and is hence known as lawn- 
 tennis leg. The accident is accompanied by a sudden pain, and produces a sensation as if the 
 individual had been struck a violent blow on the part. The tendo Achillis is also sometimes 
 ruptured. It is stated that John Hunter ruptured his tendo Achillis whilst dancing at the 
 age of forty. The retro-calcaneal bursa is interposed between the posterior surface of the os 
 calcis and the tendo Achillis, just above the point of insertion of the tendon. If it inflames 
 it produces disabling pain (achillodynia, or Albert's disease, retro-calcaneal bursitis). This bursa 
 may become cartilaginous or osteophytes may form on the surface toward the os calcis. 
 
 IV. MUSCLES AND FASCIA OF THE FOOT. 
 
 The fibrous bands, or thickened portions of the fascia of the leg, which bind down the tendons 
 in front of and behind the ankle in their passage to the foot should now be examined; they are 
 termed the annular ligaments, and are three in number — anterior, internal, and external. 
 
 The Anterior Annular Ligament (Fig. 350) consists of a superior or transverse portion 
 (ligamentum transversum cruris) which binds down the Extensor tendons as they 
 descend on the front of the tibia and fibula; and an inferior or Y-shaped portion 
 (ligamentum cruciatum cruris), which retains them in connection with the tarsus, 
 the two portions being connected by a thin intervening layer of fascia. The 
 transverse portion is attached externally to the lower end of the fibula and inter- 
 nally to the tibia; above it is continuous with the fascia of the leg; it contains 
 only one synovial sheath, for the tendon of the Tibialis anticus; the other tendons 
 and the anterior tibial vessels and nerve passing beneath it, but without any dis- 
 tinct synovial sheath. The Y-shaped portion is placed in front of the ankle-joint, 
 the stem of the Y, the fimdiform ligament of Retzius, being attached externally to 
 the upper surface of the os calcis, in front of the depression for the interosseous 
 ligament; it is directed inward, as a double layer, one lamina passing in front, 
 and the other behind, the tendons of the Peroneus tertius and Extensor longus 
 digitorum. At the inner border of the latter tendon these two layers join together. 
 
542 THE MUSCLES AND FASCIA 
 
 forming a sort of loop or sheath in which the tendons are enclosed, surrounded 
 by a synovial membrane. From the inner extremity of this loop the two limbs 
 of the Y diverge: one passes upward and inward, to be attached to the internal 
 malleolus, passing over the Extensor proprius hallucis and the vessels and nerves, 
 but enclosing the Tibialis anticus and its synovial sheath by a splitting of its 
 fibres. The other limb extends downward and inward to be attached to the 
 inner border of the plantar fascia, and passes over the tendons of the Extensor 
 proprius hallucis and Tibialis anticus and also the vessels and nerves. These 
 two tendons are contained in separate synovial sheaths situated beneath the 
 ligament. 
 
 The Internal Annular Ligament (ligamentum laciniatum) is a strong fibrous 
 band which extends from the inner malleolus above to the internal margin of the 
 OS calcis below, converting a series of grooves in this situation into canals for the 
 passage of the tendons of the Flexor muscles and vessels into the sole of the foot. 
 It is continuous by its upper border with the deep fascia of the leg, and by its lower 
 border with the plantar fascia and the fibres of origin of the Abductor hallucis 
 muscle. The four canals which it forms transmit, counting from before back- 
 ward, first, the tendon of the Tibialis posticus; second, the tendon of the Flexor 
 longus digitorum ; third, the posterior tibial vessels and nerve, which run through 
 a broad space beneath the ligament; lastly, in a canal formed partly by the 
 astragalus, the tendon of the Flexor longus hallucis. The canals for the tendons 
 are lined by a separate synovial membrane. 
 
 The External Aiinular Ligament is divided into two portions; a superior por- 
 tion (retinaculum mm. peroncBorum siiperias), which extends from the extremity 
 of the outer malleolus to the outer surface of the os calcis : it binds down the 
 tendons of the Peroneus longus and brevis muscles in their passage behind the 
 external malleolus. The two tendons are enclosed in one synovial sac. An 
 inferior portion (retinaculum mm. peronceorum inferius), which bridges the Peronei 
 on the side of the os calcis and is attached to the bone above and below them. 
 
 Dissection of the Sole of the Foot. — The foot should be placed on a high block with the 
 sole uppermost, and firmly secured in that position. Carry an incision round the heel and along 
 the inner and outer borders of the foot to the great and little toes. This incision should divide 
 the integument and thick layer of granular fat beneath until the fascia is visible; the skin and fat 
 should then be removed from the fascia in a direction from behind forward, as seen in Fig. 345. 
 
 Plantar Fascia (aponeurosis plantaris) .—The plantar fascia, the densest of all 
 the fibrous membranes, is of great strength, and consists of pearly-white glisten- 
 ing fibres, disposed, for the most part, longitudinally: it is divided into a central 
 and two lateral portions. 
 
 Central Portion. — The central portion, the thickest, is narrow behind and 
 attached to the inner tubercle of the os calcis, posterior to the origin of the 
 Flexor brevis digitorum, and, becoming broader and thinner in front, divides 
 near the heads of the metatarsal bones into five processes, one for each of the toes. 
 Each of these processes divides opposite the metatarso-phalangeal articulation 
 into two strata, superficial and deep. The superficial stratum is inserted into 
 the skin of the transverse sulcus which divides the toes from the sole. The 
 deeper stratum divides into two slips which embrace the sides of the flexor tendons 
 of the toes, and blend with the sheaths of the tendons, and laterally with the 
 transverse metatarsal ligament, thus forming a series of arches through which 
 the tendons of the short and long flexors pass to the toes. The intervals left 
 between the five processes allow the digital vessels and nerves and the tendons 
 of the Lumbricales muscles to become superficial. At the point of division of the 
 fascia into processes and slips numerous transverse fibres are superadded, which 
 serve to increase the strength of the fascia at this part by binding the processes 
 
THE DORSAL BEG ION 543 
 
 together and connecting them with the integument. The central portion of the 
 plantar fascia is continuous with the lateral portions at each side, and sends 
 upward into the foot, at their point of junction, two strong vertical intermuscular 
 septa, broader in front than behind, which separate the middle from the external 
 and internal plantar group of muscles; from these, again, thinner transverse 
 septa are derived, which separate the various layers of muscles in this region. 
 The upper surface of this fascia gives attachment behind to the Flexor brevis 
 digitorum muscle. 
 
 Lateral Portions. — The lateral portions of the plantar fascia are thinner than 
 the central piece, and cover the sides of the foot. The outer portion covers the 
 under surface of the Abductor minimi digiti; it is thick behind, thin in front, and 
 extends from the os calcis, forward, to the base of the fifth metatarsal bone, into 
 the outer side of which it is attached; it is continuous internally with the middle 
 portion of the plantar fascia, and externally with the dorsal fascia. The inner 
 portion is very thin, and covers the Abductor hallucis muscle; it is attached 
 behind to the internal annular ligament, and is continuous around the side of 
 the foot with the dorsal fascia, and externally with the middle portion of the 
 plantar fascia 
 
 Bursas about the Ankle and Foot. — (1) A subcutaneous bursa on the sole of 
 the foot, beneath the tuberosity of the os calcis. (2) A subcutaneous bursa 
 over the tendo Achillis {bursa subcutanea calcanea). (3) The retrocalcaneal 
 bursa, between the posterior surface of the os calcis and the insertion of the 
 tendo Achillis (bursa tendinis calcanei [Achillis]) . (4) A bursa between the 
 internal cuneiform bone and the tendon of the Tibialis anticus (bursa subten- 
 dinea m. iibialis anierioris). (5) Bursse between the heads of the metatarsal 
 bones (bursx infermetatarsophalangecB). (6) A subcutaneous bursa over the 
 internal malleolus (bursa subcutanea malleoli medialis). (7) Bursae between the 
 scaphoid and middle cuneiform bones on the one hand and the tendon of the 
 Tibialis posticus on the other (bursa subtendinea m. iibialis posterioris) . (8) Bursse 
 between the Lumbricales and the transverse ligaments (bursae mm. lumbricalium 
 'pedis) . (9) A bursa over the external malleolus (bursa subcutanea malleoli lateralis). 
 (10) A bursa over the head of the first metatarsal bone. Various muscles have 
 tendon-sheaths lined with synovial membrane (vaginal sheaths). 
 
 Surgical Anatomy. — ^The dense plantar fascia aids powerfully in maintaining the arch of the 
 foot. When this fascia stretches or gives way flat-foot forms. In some forms of club-foot 
 the plantar fascia is contracted. This contraction is usually a secondary change. 
 
 When inflammation causes tenderness and enlargement of the bursa over the metatarso- 
 phalangeal articulation of the great toe, the enlargement is called a bunion. Enlargement of 
 the retro-calcaneal bursa is known as Albert's disease, or achiUodynia. 
 
 8. The Dorsal Region (Fig. 350). 
 Extensor brevis digitorum. 
 
 Fascia (fascia dorsalis pedis). — The fascia on the dorsum of the foot is a thin 
 membranous layer continuous above with the anterior margin of the annular 
 ligament; it becomes gradually lost opposite the heads of the metatarsal bones, 
 And on each side blends with the lateral portions of the plantar fascia; it forms a 
 sheath for the tendons placed on the dorsum of the foot. On the removal of this 
 fascia the muscles and tendons of the dorsal region of the foot are exposed. 
 
 The Extensor Brevis Digitorum (m. extensor digitorum brevis) (Fig. 350) 
 is a broad thin muscle which arises from the forepart of the upper and 
 outer surfaces of the os calcis, in front of the groove for the Peroneus brevis, 
 from the external calcaneo-astragaloid ligament, and from the common limb of 
 the Y-shaped portion of the anterior annular ligament. It passes obliquely 
 
544 THE MUSCLES AND FASCIA 
 
 across the dorsum of the foot, and terminates in four tendons. The innermost, 
 which is the largest, is inserted into the dorsal surface of the base of the first 
 phalanx of the great toe, crossing the dorsalis pedis artery; the other three, into 
 the outer sides of the long extensor tendons of the second, third, and fourth toes. 
 
 Relations. — By its superficial surface, with the fascia of the foot, the tendons 
 of the Extensor longus digitorum and Peroneus tertius; by its deej) surface, with 
 the tarsal and metatarsal arteries and bones and the Dorsal interossei muscles. 
 
 Nerves. — It is supplied by the anterior tibial nerve. 
 
 Actions. — The Extensor brevis digitorum is an accessory to the long Extensor, 
 extending the phalanges of the four inner toes, but acting only on the first phalanx 
 of the great toe. The obliquity of its direction counteracts the oblique movement 
 given to the toes by the long Extensor, so that, both muscles acting together, the 
 toes are evenly extended. 
 
 9. The Plantar Region (Figs. 354, 355, 356, 357, 358). 
 
 The muscles in the plantar region of the foot may be divided into three groups^ 
 in a similar manner to those in the hand. Those of the internal plantar region 
 are connected with the great toe, and correspond with those of the thumb; those 
 of the external plantar region are connected with the little toe, and correspond 
 with those of the little finger; and those of the middle plantar region are con- 
 nected with the tendons intervening between the two former groups. But in order 
 to facilitate the dissection of these muscles it will be found more convenient to 
 divide them into four layers, as they present themselves, in the order in which 
 they are successively exposed. 
 
 The First Layer. 
 
 Abductor hallucis. Flexor brevis digitorum. 
 
 Abductor minimi digiti. 
 
 Dissection. — Remove the fascia on the inner and outer sides of the foot, commencing in 
 front over the tendons and proceeding backward. The central portion should be divided 
 transversely in the middle of the foot, and the two flaps dissected forward and backward. 
 
 The Abductor Hallucis lies along the inner border of the foot. It arises from 
 the inner tubercle on the under surface of the os calcis; from the internal annular 
 ligament; from the plantar fascia; and from the intermuscular septum between it 
 and the Flexor brevis digitorum. The fibres terminate in a tendon which is 
 inserted, together with the innermost tendon of the Flexor brevis hallucis, into 
 the inner side of the base of the first phalanx of the great toe. 
 
 Relations. — By its superficial surface, with the plantar fascia; by its deep sur- 
 face, with the Flexor brevis hallucis, the Flexor accessorius, and the tendons of 
 the Flexor longus digitorum and Flexor longus hallucis, the Tibialis anticus and 
 posticus, the plantar vessels and nerves. Its outer border is in relation to the 
 Flexor brevis digitorum. 
 
 The Flexor Brevis Digitorum (m. flexor digitorum brevis) lies in the 
 middle of the sole of the foot, immediately beneath^ the plantar fascia, with 
 which it is firmly united. It arises by a narrow tendinous process, from the 
 inner tubercle of the os calcis, from the central part of the plantar fascia, and 
 from the intermuscular septa between it and the adjacent muscles. It passes 
 forward, and divides into four tendons, one for each of the four outer toes. 
 Opposite the bases of the first phalanges each tendon divides into two slips, to 
 allow of the passage of the corresponding tendon of the Flexor longus digitorum ,• 
 
 ' That is, in order of dissection of the sole of the foot. 
 
THE PLANTAR REGION 
 
 545 
 
 the two portions of the tendon then unite and form a grooved channel for the 
 reception of the accompanying long flexor tendon. Finally, they divide a second 
 time, to be inserted into the sides of the second phalanges about their middle. The 
 mode of division of the tendons of the Flexor brevis digitorum and their insertion 
 into the phalanges is analogous to the division 
 and insertion of the Flexor sublimis digitorum 
 in the hand. 
 
 Relations. — By its superficial surface, with 
 the plantar fascia; by its deep surface, with the 
 Flexor accessorius, the Lumbricales, the ten- 
 dons of the Flexor longus digitorum, and the 
 external plantar vessels and nerve, from which 
 it is separated by a thin layer of fascia. The 
 outer and inner borders are separated from the 
 adjacent muscles by means of vertical pro- 
 longations of the plantar fascia. 
 
 Fibrous Sheaths of the Flexor Tendons. — 
 These are not so well marked as in the fingers. 
 The flexor tendons of the toes as they run 
 along the phalanges are retained against the 
 bones by a fibrous sheath, forming osseo- 
 aponeurotic canals. These sheaths are formed 
 by strong fibrous bands which arch across the 
 tendons and are attached on each side to the 
 margins of the phalanges. Opposite the mid- 
 dle of the proximal and second phalanges the 
 sheath is very strong, and the fibres pass 
 transversely, but opposite the joints it is 
 much thinner, and the fibres pass obliquely. 
 Each sheath is lined by a synovial mem- 
 brane which is reflected on the contained 
 tendon. 
 
 The Abductor Minimi Digiti (m. abductor 
 digiti quinti) lies along the outer border of the 
 foot. It arises, by a very broad origin, from 
 the outer tubercle of the os calcis, from the 
 under surface of the os calcis between the two 
 tubercles, from the forepart of the inner 
 tubercle, from the plantar fascia and the in- 
 termuscular septum, between it and the Flexor 
 brevis digitorum. Its tendon, after gliding 
 over a smooth facet on the under surface of 
 the base of the fifth metatarsal bone, is inserted 
 with the short Flexor of the little toe into the outer side of the base of the first 
 phalanx of this toe. 
 
 Relations. — By its superficial surface, with the plantar fascia; by its deep sur- 
 face, with the Flexor accessorius, the Flexor brevis minimi digiti, the long plantar 
 ligament, and the tendon of the Peroneus longus. On its inner side are the 
 external plantar vessels and nerve, and it is separated from the Flexor brevis 
 digitorum by a vertical septum of fascia. 
 
 Dissection. — The muscles of the superficial layer should be divided at their origin by insert- 
 ing the knife beneath each, and cutting obliquely backward, so as to detach them from the 
 bone; they should then be drawn forward, in order to expose the second layer, but not cut away 
 at their insertion. The two layers are separated by a thin membrane, the deep plantar fascia, 
 
 35 
 
 Fig. 354. 
 
 -Muscles of the sole of the foot. 
 First layer. 
 
546 THE MUSCLES AND FASCIA 
 
 on the removal of which is seen the tendon of the Flexor longus digitorum, the Flexor accessorius, 
 the tendon of the Flexor longus hallucis, and the Lumbricales. The long flexor tendons 
 diverge from each other at an acute angle; the Flexor longus hallucis runs along the inner side 
 of the foot, on a plane superior to that of the Flexor longus digitorum, the direction of which is 
 obliquely outward. 
 
 The Second Layer. 
 Flexor accessorius. Lumbricales. 
 
 The Flexor Accessorius (m. quadratus plantcc) arises by two heads, which are 
 separated from each other by the long plantar ligament : the inner or larger head, 
 which is muscular, being attached to the inner concave surface of the os calcis 
 below the groove which lodges the tendon of the Flexor longus digitorum; the 
 outer head, flat and tendinous, to the outer surface of the os calcis, in front of its 
 lesser tubercle, and to the long plantar ligament; the two portions join at an 
 acute angle, and are inserted into the outer margin and upper and under sur- 
 faces of the tendon of the Flexor longus digitorum, forming a kind of groove in 
 which the tendon is lodged.^ 
 
 Relations. — By its superficial surface, with the muscles of the superficial layer, 
 from which it is separated by the external plantar vessels and nerves; by its deep 
 surface, with the os calcis and long calcaneo-cuboid ligament. 
 
 The Lumbricales are four small muscles accessory to the tendons of the Flexor 
 longus digitorum: they arise from the tendons of the long Flexor, as far back as 
 their angle of division, each arising from two tendons, except the internal one. 
 Each muscle terminates in a tendon, which passes forward on the inner side of 
 the four lesser toes and is inserted into the expansion of the long Extensor tendon 
 on the dorsum of the first phalanx of the corresponding toe. 
 
 Dissection. — The flexor tendons should be divided at the back part of the foot, and the 
 Flexor accessorius at its origin, and drawn forward, in order to expose the third layer. 
 
 The Third Layer. 
 
 Flexor brevis hallucis. Flexor brevis minimi digiti. 
 
 Adductor obliquus hallucis. Adductor transversus hallucis. 
 
 The Flexor Brevis Hallucis (m. flexor hallucis brevis) arises, by a pointed 
 tendinous process, from the inner part of the under surface of the cuboid bone, 
 from the contiguous portion of the external cuneiform, and from the prolongation 
 of the tendon of the Tibialis posticus, which is attached to that bone. The 
 muscle divides, in front, into two portions, which are inserted into the inner 
 and outer sides of the base of the first phalanx of the great toe, a sesamoid bone 
 being developed in each tendon at its insertion. The inner portion of this 
 muscle is blended with the Abductor hallucis previous to its insertion, the outer 
 portion with the Adductor obliquus hallucis, and the tendon of the Flexor 
 longus hallucis lies in a groove between them. 
 
 Relations. — By its superficial surface, with the Abductor hallucis and the ten- 
 don of the Flexor longus hallucis; by its deep surface, with the tendon of the 
 Peroneus longus and metatarsal bone of the great toe; by its inner border, with 
 the Abductor hallucis; by its outer border, with the Adductor obliquus hallucis. 
 
 The Adductor Obliquus Hallucis is a large, thick, fleshy mass passing obliquely 
 across the foot and occupying the hollow space between the four inner meta- 
 tarsal bones. It arises from the tarsal extremities of the second, third, and fourth 
 metatarsal bones, and from the sheath of the tendon of the Peroneus longus, 
 
 ' According to Turner, the fibres of the Flexor accessorius end in aponeurotic bands, which contribute slips 
 to the second, third, and fourth digits. 
 
THE PLANTAR REGION 
 
 547 
 
 and is inserted, together with the outer portion of the Flexor brevis hallucis, into 
 the outer side of the base of the first phalanx of the great toe. 
 
 The small muscles of the great toe, the Abductor, Flexor brevis, Adductor 
 obliquus, and Adductor transversus, like the similar muscles of the thumb, give 
 off fibrous expansions, at their insertions, to blend with the long Extensor tendon. 
 
 Fig. 355.- 
 
 - Muscles of the sole of the foot. 
 Second layer. 
 
 Fig. 356. — Muscles of the sole of the foot. 
 Third layer. 
 
 The Flexor Brevis Minimi Digiti {m. flexor digiti quinti brevis) lies on the meta- 
 tarsal bone of the little toe, and much resembles one of the Interossei. It arises 
 from the base of the metatarsal bone of the little toe, and from the sheath of the 
 Peroneus longus; its tendon is inserted into the base of the first phalanx of 
 the little toe on its outer side. Occasionally some of the deeper fibres of the 
 muscle are inserted into the outer part of the distal half of the fifth metatarsal 
 bone; these are described by some as a distinct muscle, the Opponens minimi 
 digiti. 
 
 Relations. — By its superficial surface, with the plantar fascia and tendon of 
 the Abductor minimi digiti; by its deep surface, with the fifth metatarsal bone. 
 
548 
 
 THE MUSCLES AND FASCIA 
 
 The Adductor Transversus Hallucis (m. transversus pedis) is a narrow, flat, 
 muscular fasciculus, stretched transversely across the heads of the metatarsal bones, 
 between them and the flexor tendons. It arises from the inferior metatarso- 
 phalangeal ligaments of the three outer toes, sometimes only from the third and 
 fourth and from the transverse ligament of the metatarsus; and is inserted into 
 the outer side of the first phalanx of the great toe, its fibres being blended with 
 the tendon of insertion of the Adductor obliquus hallucis. 
 
 Relations. — By its superficial surface, with the tendons of the long and short 
 Flexors and Lumbricales; by its deep surface, with the Interossei. 
 
 The Fourth Layer. 
 
 The Interossei. 
 
 The Interossei Muscles in the foot are similar to those in the hand, with this 
 exception, that they are grouped around the middle line of the second toe, instead 
 of the middle line of the third finger, as in the hand. They are seven in number, 
 and consist of two groups. Dorsal and Plantar. 
 
 Fig. 357. — The Dorsal interossei. Left foot. 
 
 Fig. 358. — The Plantar interossei. Left foot. 
 
 The Dorsal Interossei (m. interossei dorsales), ionr in number, are situated between 
 the metatarsal bones. They are bipenniform muscles, arising by two heads from 
 the adjacent sides of the metatarsal bones, between which they are placed; their 
 tendons are inserted into the bases of the first phalanges, and into the aponeurosis 
 of the common extensor tendon. In the angular interval left between the heads 
 of each muscle at its posterior extremity the perforating arteries pass to the 
 dorsum of the foot, except in the First interosseous muscle, where the interval 
 allows the passage of the communicating branch of the dorsalis pedis artery. The 
 First dorsal interosseous muscle is inserted into the inner side of the second toe; 
 the other three are inserted into the outer sides of the second, third, and fourth toes. 
 
 The Plantar Interossei (m. interossei plantares), three in number, lie beneath, 
 rather than between, the metatarsal bones. They are single muscles, and are 
 each connected with but one metatarsal bone. They arise from the base and 
 
SURFACE FORM OF THE LOWER EXTREMITY 549 
 
 inner sides of the shaft of the third, fourth, and fifth metatarsal bones, and are 
 inserted into the inner sides of the bases of the first phalanges of the same toes, 
 and into the aponeurosis of the common extensor tendon. 
 
 Nerves. — The Flexor brevis digitorum, the Flexor brevis and Abductor hallucis, 
 and the innermost LumbricaP are supplied by the internal plantar nerve. All 
 the other muscles in the sole of the foot by the external plantar. The first dorsal 
 interosseous muscle frequently receives an extra filament from the internal 
 branch of the anterior tibial nerve on the dorsum of the foot, and the second 
 dorsal interosseous a twig from the external branch of the same nerve. 
 
 Actions. — All the muscles of the foot act upon the toes, and for purposes of 
 description as regard their action may be grouped as Abductors, Adductors, 
 Flexors, or Extensors. The Abductors are the Dorsal interossei, the Abductor 
 hallucis, and the Abductor minimi digiti. The Dorsal interossei are abductors 
 from an imaginary line passing through the axis of the second toe, so that the 
 first muscle draws the second toe inward, toward the great toe; the second muscle 
 draws the same toe outward; the third draws the third toe, and the fourth draws 
 the fourth toe, in the same direction. Like the interossei in the hand, they also 
 flex the proximal phalanges and extend the two terminal phalanges. The Abduc- 
 tor hallucis abducts the great toe from the others, and also flexes the proximal 
 phalanx of this toe. And in the same way the action of the Abductor minimi 
 digiti is twofold — as an abductor of this toe from the others, and also as a flexor 
 of the proximal phalanx. The Adductors are the Plantar interossei, the Adductor 
 obliquus hallucis, and the Adductor transversus hallucis. The Plantar inter- 
 osseous muscles adduct the third, fourth, and fifth toes toward the imaginary 
 line passing through the second toe, and by means of their insertion into the 
 aponeurosis of the extensor tendon they, with the dorsal interossei, flex the prox- 
 imal phalanges and extend the two terminal phalanges. The Adductor obliquus 
 hallucis is chiefly concerned in adducting the great toe toward the second one, 
 but also assists in flexing this toe. The Adductor transversus hallucis approxi- 
 mates all the toes, and thus increases the curve of the transverse arch of the 
 metatarsus. The Flexors are the Flexor brevis digitorum, the Flexor accessorius, 
 the Flexor brevis hallucis, the Flexor brevis minimi digiti, and the Lumbricales. 
 The Flexor brevis digitorum flexes the second phalanges upon the first, and, con- 
 tinuing its action, may flex the first phalanges also and bring the toes together. 
 The Flexor accessorius assists the Long flexor of the toes, and converts the 
 oblique pull of the tendons of that muscle into a direct backward pull upon the 
 toes. The Flexor brevis hallucis flexes and slightly adducts the first phalanx of 
 the great toe. The Flexor brevis minimi digiti flexes the little toe and draws its 
 metatarsal bone downward and inward. The Lumbricales, like the correspond- 
 ing muscles in the hand, assist in flexing the proximal phalanx, and by their 
 insertion into the long Extensor tendon aid in straightening the two terminal 
 phalanges. The only muscle in the Extensor group is the Extensor brevis digi- 
 torum. It extends the first phalanx of the great toe, and assists the long Exten- 
 sor in extending the next three toes, and at the same time gives to the toes an 
 outward direction when they are extended. 
 
 SURFACE FORM OF THE LOWER EXTREMITY. 
 
 Of the muscles of the thigh, those of the iliac region have no influence on surface form, 
 while those of the anterior femoral region, being to a great extent superficial, largely con- 
 tribute to the surface form of this part of the body. The Tensor fascise femoris pro- 
 
 1 Formerly the two inner Lumbricales were described as being supplied by the internal plantar nerve. Brooks 
 (Journal of Anatomy, vol. xxi. p. 575) in ten dissections found that in nine of them only the inner Lumbrical 
 obtained its nerve supply from this source. In the tenth instance the first and second Lumbricales were 
 supplied by both external and internal plantar. 
 
550 THE MUSCLES AND FASCIA 
 
 duces a broad elevation immediately below the anterior portion of the crest of the ilium and 
 behind the anterior superior spinous process. From its lower border a longitudinal groove, 
 corresponding to the ilio-tibial band, may be seen running down the outer side of the thigh to 
 the outer side of the knee-joint. The Sartorius muscle, when it is brought into action by flexing 
 the leg on the thigh and the thigh on the pelvis, and rotating the thigh outward, presents a 
 well-marked surface form. At its upper part, where it constitutes the outer boundary of 
 Scarpa's triangle, it forms a prominent oblique ridge, which becomes changed into a flattened 
 plane below, and this gradually merges in a general fulness on the inner side of the knee-joint. 
 When the Sartorius is not in action, a depression exists between the Quadriceps extensor and the 
 Adductor muscles, running obliquely downward and inward from the apex of Scarpa's triangle 
 to the inner side of the knee, which depression corresponds to this muscle. In the depressed angle 
 formed by the divergence of the Sartorius and Tensor fasci?e femoris muscles, just below the 
 anterior superior spinous process of the ilium, the Rectus femoris muscle appears, and, below 
 this, determines to a great extent the convex form of the front of the thigh. In a well-developed 
 subject the borders of the muscle, when in action, are clearly to be defined. The Vastus extemus 
 forms a long flattened plane on the outer side of the thigh, traversed by the longitudinal groove 
 formed by the ilio-tibial band. The Vastus intemus, on the inner side of the lower half of the 
 thigh, gives rise to a considerable prominence, which increases toward the knee and terminates 
 somewhat abruptly in this situation with a full, curved outline. The Crureus and Subcrureus 
 are completely hidden, and do not directly influence surface form. The Adductor muscles, 
 constituting the internal femoral group, are not to be individually distinguished from each 
 other, with the exception of the upper tendon of the Adductor longus and the lower tendon of 
 the Adductor magnus. The upper tendon of the Adductor longUS, when the muscle is in action, 
 stands out as a prominent ridge, which runs obliquely downward and outward from the neigh- 
 borhood of the pubic spine, and forms the inner boundary of a flattened triangular space on 
 the upper part of the front of the thigh, known as Scarpa's triangle. The lower tendon of the 
 Adductor magnus can be distinctly felt as a short ridge extending down to the Adductor tubercle 
 on the internal condyle, between the Sartorius and Vastus internus. The Adductor group 
 of muscles fills in the triangular space at the upper part of the thigh, formed between the oblique 
 femur and the pelvic wall, and to them is due the contour of the inner border of the thigh, the 
 Gracilis largely contributing to the smoothness of the outline. These muscles are not marked 
 off on the surface from those of the posterior femoral region by any intermuscular marking; but 
 on the outer side of the thigh these latter muscles are defined from the Vastus externus by a 
 distinct marking, corresponding to the external intermuscular septum. The Gluteus maximus 
 and a part of the Gluteus medius are the only muscles of the buttock which influence surface 
 form. The other part of the Gluteus medius, the Gluteus minimus, and the External rotators 
 are completely hidden. The Gluteus maximus forms the full rounded outline of the buttock; 
 it is more prominent behind, compressed in front, and terminates at its tendinous insertion in 
 a depression immediately behind the great trochanter. Its lower border does not correspond 
 to the gluteal fold, but is much more oblique, being marked by a line drawn from the side of 
 the coccyx to the junction of the upper with the lower two-thirds of the thigh on the outer side. 
 From beneath the lower margin of this muscle the Hamstring muscles appear, at first narrow 
 and not well marked, but as they descend becoming more prominent and widened out, and 
 eventually dividing into two well-marked ridges, which constitute the upper boundaries of the 
 popliteal space, and are formed by the tendons of the inner and outer hamstring muscles respect- 
 ively. In the upper part of the thigh these muscles are not to be individually distinguished 
 from each other, but lower down the separation between the Semitendinosus and Semimem- 
 branosus is denoted by a slight intermuscular marking. The external hamstring tendon formed 
 by the Biceps is seen as a thick cord running down to the head of the fibula. The inner ham- 
 string tendons comprise the Semitendinosus, the Semimembranosus, and the Gracilis. The 
 Semitendinosus is the most internal of these, and can be felt, in certain positions of the limb, 
 as a sharp cord; the Semimembranosus is thick, and the Gracilis is situated a little farther 
 forward than the other two. All the muscles on the front of the leg appear to a certain extent 
 somewhere on the surface, but the form of this region is mainly dependent upon the Tibialis 
 anticus and the Extensor longus digitorum. The Tibialis anticus is well marked, and presents 
 a fusiform enlargement at the outer side of the tibia, and projects beyond the crest of the shin- 
 bone. From the muscular mass its tendons may be traced downward, standing out boldly, 
 when the muscle is in action, on the front of the tibia and ankle-joint, and coursing down to its 
 insertion along the inner border of the foot. A well-marked groove separates this muscle exter- 
 nally from the Extensor longus digitorum, which fills up the rest of the space between the upper 
 part of the shaft of the tibia and fibula. It does not present so bold an outline as the Tibialis 
 anticus, and its tendon below, diverging from the tendon of the Tibialis anticus, forms with the 
 latter a sort of plane, in which may be seen the tendon of the Extensor proprius hallucis. A 
 groove on the outer side of the extensor longus digitorum, seen most plainly when the muscle 
 is in action, separates the tendon from a slight eminence corresponding to the Peroneus tertius. 
 The fleshy fibres of the Peroneus longus are strongly marked at the upper part of the outer 
 
SURGICAL ANATOMY OF THE LOWER EXTREMITY 551 
 
 side of the leg, especially when the muscle is in action. It forms a bold swelling, separated by 
 furrows from the Extensor longus digitorum in front and the Soleus behind. Below, the fleshy 
 fibres terminate abruptly in a tendon which overlaps the more flattened form of the Peroneus 
 brevis. At the external malleolus the tendon of the Peroneus brevis is more marked than that 
 of the Peroneus longus. On the dorsum of the foot the tendons of the Extensor muscles, 
 emerging from beneath the anterior annular ligament, spread out and can be distinguished 
 in the following order: The most internal and largest is the Tibialis anticus, then the Extensor 
 proprius hallucis ; next comes the Extensor longus digitorum, dividing into four tendons to 
 the four outer toes; and lastly, most externally, is the Peroneus tertius. The flattened form of 
 the dorsum of the foot is relieved by the rounded outline of the fleshy belly of the Extensor 
 brevis digitorum, which forms a soft fulness on the outer side of the tarsus in front of the external 
 malleolus, and by the Dorsal interossei, which bulge between the metatarsal bones. At the 
 back of the knee is the popliteal space, bounded above by the tendons of the hamstring muscle; 
 below, by the two heads of the Gastrocnemius. Below this space is the prominent fleshy mass 
 of the calf of the leg, produced by the Gastrocnemius and Soleus. When these muscles are 
 in action, as in standing on tiptoe, the borders of the Gastrocnemius are well defined, presenting 
 two curved lines, which converge to the tendon of insertion. Of these borders, the inner is 
 more prominent than the outer. The fleshy mass of the calf terminates somewhat abruptly 
 below in the tendo Achillis, which stands out prominently on the lower part of the back of the 
 leg. It presents a somewhat tapering form in the upper three-fourths of its extent, but widens 
 out slightly below. When the muscles of the calf are in action, the lateral portions of the Soleus 
 may be seen, forming curved eminences, of which the outer is the longer, on either side of the 
 Gastrocnemius. Behind the inner border of the lower part of the shaft of the tibia a well- 
 marked ridge, produced by the tendon of the Tibialis posticus, is visible when this muscle is in 
 a state of contraction. On the sole of the foot the superficial layer of muscles influences surface 
 form; the Abductor minimi digiti most markedly. This muscle forms a narrow rounded 
 elevation along the outer border of the foot, while the Abductor hallucis does the same, though 
 to a less extent, on the inner side. The Flexor brevis digitorum, bound down by the plantar 
 fascia, is not very apparent; it produces a flattened form, covered by the thickened skin of the 
 sole, which is here thrown into numerous wrinkles. 
 
 SURGICAL ANATOMY OF THE LOWER EXTREMITY. 
 
 The student should now consider the effects produced by the action of the various muscles 
 in fractures of the bones of the lower extremity. The more common forms of fractures are 
 selected for illustration and description. 
 
 PYRIFORMIS. 
 GEMELLUS SUPERIOR. 
 OBTURATOR INTERNUS. 
 GEMELLUS INFERIOR. 
 OBTURATOR EXTERNUS. 
 QUADRATUS FEMORIS. 
 
 Fig. 359.- -Fracture of the neck of the femur within the capsular ligament. 
 
 In fracture of the neck of the femur internal to the capsular ligament (Fig. 359) the charac- 
 teristic marks are slight shortening of the limb and eversion of the foot, neither of which symp- 
 
552 
 
 THE MUSCLES AND FASCIJE 
 
 toms occurs, however, in some cases until some time after the injury. The eversion is caused 
 by the weight of the Hmb rotating it outward. The shortening is produced by the action of the 
 Glutei, and by the Rectus femoris in front and the Biceps, Semitendinosus, and Semimem- 
 branosus behind. The treatment is extension by means of adhesive plaster and weights and 
 counter-extension by raising the foot of the bed, eversion being corrected by sand-bags. In 
 some cases Thomas's splint is used. 
 
 In fracture of the femur just below the trochanters (Fig. 360) the upper fragment, the por- 
 tion chiefly displaced, is tilted forward almost at right angles with the pelvis by the combined 
 
 action of the Psoas and Iliacus, and, at the same time, everted 
 and drawn outward by the External rotator and Glutei muscles, 
 causing a marked prominence at the upper and outer side of the 
 thigh, and much pain from the bruising and laceration of the 
 muscles. The limb is shortened, in consequence of the lower 
 fragment being drawn upward by the rectus in front, and the 
 Biceps, Semimembranosus, and Semitendinosus behind, and is 
 at the same time everted. This fracture may be reduced by 
 direct relaxation of all the opposing muscles, to effect which the 
 limb should be put up in such a manner that the thigh is flexed 
 on the pelvis and the leg on the thigh, the extremity being placed 
 
 SEMI- 
 MEMBRANOSUS. 
 SEMI- 
 / TENDINOSUS. 
 
 Fig. 360. — Fracture of the femur 
 below the trochanters. 
 
 Fig. 361. — Fracture of the femur 
 above the condyles. 
 
 Fig. 362.— Fracture of 
 the patella 
 
 upon a double inclined plane and extension being made in the axis of the partly flexed 
 thigh by means of adhesive plaster and weights. In some cases it is necessary to incise and 
 wire the fragments together. 
 
 Oblique fracture of the femur immediately above the condyles (Fig. 361) is a formidable 
 injury, and attended with considerable displacement. On examination of the limb the lower 
 fragment may be felt deep in the popliteal space, being drawn backward by the Gastrocnemius 
 and Plantaris muscles, and upward by the Hamstring and Rectus muscles. The pointed end 
 of the upper fragment is drawn inward by the Pectineus and Adductor muscles, and tilted for- 
 ward by the Psoas and Iliacus, piercing the Rectus muscle and occasionally the integument. 
 Relaxation of these muscles and direct approximation of the broken fragments are effected by 
 placing the limb on a double inclined plane. The greatest care is requisite in keeping the 
 pointed extremity of the upper fragment in proper position; otherwise, after union of the 
 fracture, the power of extension of the limb is partially destroyed from the Rectus muscle being 
 held down by the fractured end of the bone, and from the patella, when elevated, being drawn 
 upward against the projecting fragment. 
 
 In fracture of the patella (Fig. 362) the fragments are separated by the efi'usion which takes 
 place into the joint, and by the action of the Quadriceps extensor; the extent of separation of 
 the two fragments depending upon the degree of laceration of the ligamentous structures 
 around the bone. Some cases may be treated by a posterior straight splint, the fragments 
 being pulled together by strips of adhesive plaster. In many cases it is advisable to incise, 
 remove intervening pieces of fibrous tissue and wire the fragments together. 
 
SURGICAL ANATOMY OF THE LOWER EXTREMITY 553 
 
 The tibia is fractured most commonly by indirect force at the junction of the middle third 
 with the lower third of the shaft. Compound fractures are more common in the leg than 
 in any other region of the body because the tibia is such a superficial bone and is so much 
 exposed to injury. Most fractures from indirect force are oblique. 
 
 In oblique fracture of the shaft of the tibia (Fig. 363), if the fracture has taken place obliquely 
 from above, downward and forward, the fragments ride over one another, the lower fragments 
 being drawn backward and upward by the powerful action of the muscles of the calf; the 
 pointed extremity of the upper fragment projects forward immediately beneath the integu- 
 ment, often protruding through it and rendering the fracture a compound one. If the direc- 
 tion of the fracture is the reverse of that shown in the figure, the pointed extremity of the lower 
 fragment projects forward, riding upon the lower end of the upper one. By bending the knee. 
 
 Fig. 363. — Oblique fracture of 
 the shaft of the tibia. 
 
 Fig. 364. — Fracture of the fibula with dislocation of 
 the foot outward — " Pott's fracture." 
 
 which relaxes the opposing muscles, and making extension from the ankle and counter- 
 extension at the knee, the fragments may be brought into apposition. It is often necessary, 
 however, in a compound fracture, to remove a portion of the projecting bone with the saw 
 before complete adaptation can be effected. 
 
 Fracture of the fibula with dislocation of the foot outward (Fig. 364), commonly known as 
 Pott's fracture, is one of the most frequent injuries of the ankle-joint. The fibula is frac- 
 tured about three inches above the ankle; in addition to this the internal malleolus is broken 
 off, or the deltoid ligament torn through, and the end of the tibia displaced from the correspond- 
 ing surface of the astragalus. The foot is markedly everted, and the sharp edge of the upper 
 end of the fractured malleolus presses strongly against the skin; at the same time, the heel is 
 drawn up by the muscles of the calf. This injury can generally be reduced by flexing the leg at 
 right angles with the thigh, which relaxes all the opposing muscles, and by making extension 
 from the ankle and counter-extension at the knee. 
 
 ^ 
 
THE BLOOD-VASCULAE SYSTEM. 
 
 ANGIOLOGY is the branch of anatomy which treats of the blood-vessels. 
 The blood-vascular system comprises the heart and blood-vessels with 
 their contained fluid, the blood. 
 
 The Heart is the central organ of the entire system, and is a hollow muscle; 
 by its contraction the blood is pumped to all parts of the body through a com- 
 plicated series of tubes, termed arteries. The arteries undergo almost infinite 
 ramification in their course throughout the body, and end in very minute vessels, 
 called arterioles, which in their turn open into a close-meshed network of micro- 
 scopic vessels, termed capillaries . After the blood has passed through the capil- 
 laries it enters into minute vessels called venules and from them it is collected 
 into a series of larger vessels, called veins, by which it is returned to the heart. 
 The passage of the blood through the heart and blood-vessels constitutes what is 
 termed the circulation of the blood, of which the following is an outline. 
 
 The human heart is divided by a septum into two halves, right and left, each 
 half being further constricted into two cavities, the upper of the two being termed 
 the auricle and the lower the ventricle. The heart therefore consists of four 
 chambers or cavities, two forming the right half, the right auricle and right 
 ventricle; and two the left half, the left auricle and left ventricle. The right 
 half of the heart contains venous or impure blood; the left, arterial or pure blood. 
 From the cavity of the left ventricle the pure blood is carried into a large artery, 
 the aorta, through the numerous branches of which it is distributed to all parts 
 of the body, with the exception of the lungs. In its passage through the capil- 
 laries of the body the blood gives up to the tissues the materials necessary for 
 their growth and nourishment, and at the same time receives from the tissues the 
 waste products resulting from their metabolism, and in doing so becomes changed 
 from arterial or pure blood into venous or impure blood, which is collected by the 
 veins and through them returned to the right auricle of the heart. From this 
 cavity the impure blood passes into the right ventricle, from which it is conveyed 
 through the pulmonary arteries to the lungs. In the capillaries of the lungs it 
 again becomes arterialized, and is then carried to the left auricle by the pulmonary 
 veins. From this cavity it passes into that of the left ventricle, from which the 
 cycle once more begins. 
 
 The course of the blood from the left ventricle through the body generally to 
 the right side of the heart constitutes the greater or systemic circulation, while its 
 passage from the right ventricle through the lungs to the left side of the heart is 
 termed the lesser or pulmonary circulation. 
 
 It is necessary, however, to state that the blood which circulates through the 
 spleen, pancreas, stomach, small intestine, and the greater part of the large intes- 
 tine is not returned directly from these organs to the heart, but is collected into 
 a large vein, termed the portal vein, by which it is carried to the liver. In the 
 liver this vein divides, after the manner of an artery, and ultimately ends in 
 capillary vessels, from which the rootlets of a series of veins, called the hepatic 
 veins, arise; these carry the blood into the inferior vena cava, which conveys it 
 to the right auricle. 
 
 ( 555 ) 
 
556 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 Pulm onary Camllaries 
 
 From this it will be seen that the blood contained in the portal vein passes 
 through two sets of capillary vessels: (1) those in the spleen, pancreas, stomach, 
 etc., and (2) those in the liver. 
 
 Speaking generally, the arteries may be said to contain pure, and the veins 
 impure, blood. This is true of the systemic, but not of the pulmonary, vessels, 
 since it has been seen that the impure blood is conveyed from the heart to the 
 lungs by the pulmonary arteries, and the pure blood returned from the lungs to 
 
 the heart by the pulmonary veins. Arteries, 
 therefore, must be defined as vessels which 
 convey blood from the heart, and veins as 
 vessels which return blood to the heart. 
 
 The heart and lungs are contained within 
 the cavity of the thorax, the walls of which 
 afford them protection (Fig. 366). The heart 
 lies between the two lungs, and is there 
 enclosed within a sero-membranous bag, the 
 pericaxdium, while each lung is invested by a 
 serous membrane, the pleura. The skeleton 
 of the thorax was described on page 155. 
 
 The Cavity of the Thorax (cavum tho- 
 racis). — The capacity of the cavity of the 
 thorax does not correspond with its apparent 
 size externally, because (1) the space en- 
 closed by the lower ribs is occupied by some 
 of the abdominal viscera ; and (2) the cavity 
 extends above the first rib into the neck. 
 The size of the cavity of the thorax is con- 
 stantly varying during life, with the move- 
 ments of the ribs and diaphragm, and with 
 the degree of distention of the abdominal 
 viscera. From the collapsed state of the 
 lungs, as seen when the thorax is opened, 
 in the dead body, it would appear as if the 
 viscera only partly filled the cavity of the 
 thorax, but during life there is no vacant 
 space, that which is seen after death being 
 filled up during life by the expanded lungs. 
 The Upper Opening of the Thorax 
 {apertura thoracis superior) . — The parts 
 which pass through the upper opening of 
 the thorax are, from before backward in or 
 near the middle line, the Sterno-hyoid and 
 Sterno-thyroid muscles, the remains of the 
 thymus gland, the trachea, oesophagus, thoracic duct, the inferior thyroid veins, 
 and the Longus colli muscle of each side; at the sides, the innominate artery, 
 the left common carotid, and left subclavian arteries, the internal mammary 
 and superior intercostal arteries, the right and left innominate veins, the pneu- 
 mogastric, cardiac, phrenic, and sympathetic nerves, the anterior branch of the 
 first dorsal nerve, and the recurrent laryngeal nerve of the left side. The 
 apex of each lung, covered by the pleura, also projects through this aperture, a 
 little above the margin of the first rib. 
 
 The Lower Opening of the Thorax (apertura thoracis inferior) is wider trans- 
 versely than from before backward. It slopes obliquely downward and back- 
 ward, so that the cavity of the thorax is much deeper behind than in front. The 
 
 Fig. 365.- 
 
 -Diagram to show the course of the 
 circulation of the blood. 
 
THE PERICARDIUM 
 
 557 
 
 Diaphragm (see page 427) closes in the opening, forming the floor of the thorax. 
 The floor is flatter at the centre than at the sides, and is higher on the right side 
 than on the left, corresponding in the dead body to the upper border of the fifth 
 
 Fig. 366. — Front view of the thorax. The ribs and sternum are represented in relation to the lungs, heart, 
 and othpr internal organs. 1. Pulmonary orifice. 2. Aortic orifice. 3. Left auriculo- ventricular orifice. 4. 
 Right auriculo-ventricular orifice. 
 
 costal cartilage on the former, and to the corresponding part of the sixth costal 
 cartilage on the latter. From the highest point on each side the floor slopes sud- 
 denly downward to the attachment of the Diaphragm to the ribs; this is more 
 marked behind than in front, so that only a narrow space is left between it and 
 the wall of the thorax. 
 
 THE PERICARDIUM. 
 
 The pericardium (Figs. 367, 368, 369, 370, 371, and 372) is a conical sero- 
 membranous sac, placed in the middle mediastinum. In this sac the heart and 
 the commencement of the great vessels are contained. It is placed behind the 
 sternum and the cartilages of the third, fourth, fifth, sixth, and seventh ribs of 
 the left side, in the interval between the pleurae. 
 
 Its apex is directed upward, and surrounds the great vessels about two inches 
 above their origin from the base of the heart. Its base is attached to the central 
 tendon and to the left part of the adjoining muscular structure of the Diaphragm. 
 In front it is separated from the sternum by the remains of the thymus gland 
 
558 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 above and a little loose areolar tissue below, and is covered by the margins of the 
 lungs, especially the left. Behind, it rests upon the bronchi, the oesophagus, and 
 the descending aorta. Laterally, it is covered by the pleurae, and is in relation to 
 the inner surface of the lungs; the phrenic nerve with its accompanying vessels 
 descends between the pericardium and pleura on either side (Fig. 371). 
 
 Structure of the Pericardium. — ^The pericardium is a fibro-serous membrane, 
 and consi^s, therefore, of two layers, an external fibrous and an internal serous. 
 
 Right common 
 carotid artery. 
 Inferior thyroid 
 vein. 
 Left innomi- 
 nate vein. 
 Right innomi- 
 nate vein. 
 
 Superior vena 
 cava. 
 
 Right pulmo 
 nary veins. 
 
 Left common 
 carotid art. 
 
 Left sub- 
 chirian 
 (trtery. 
 
 ] Left pul- 
 > monary 
 J veins. 
 
 Fig. 367.- 
 
 -Pericardium from in front. The sac has been distended with plaster. (From a preparation 
 in the Museum of the Royal College of Surgeons of England.) 
 
 The Fibrous Layer is a strong, dense, connective-tissue membrane. Above, it 
 surrounds the great vessels arising from the base of the heart, on which it is 
 continued in the form of tubular prolongations which are gradually lost upon 
 their external coat, the strongest being that which encloses the aorta. The peri- 
 cardium may be traced over these vessels, to become continuous with the deep 
 layer of the cervical fascia. The prolongations to the cervical fascia constitute the 
 vertebro-pericardial ligaments (Fig. 370). In front the pericardium is connected to 
 the posterior surface of the sternum by two fibrous bands, the superior and inferior 
 stemo-pericardiac ligaments or ligaments of Luschka (ligamenta sternopericardiaca) 
 (Fig. 370). The superior sterno-pericardial ligament, called also the stemocosto- 
 
THE PERICARDIUM 
 
 559 
 
 pericardial ligament (Fig. 370), passes to the manubrium. The inferior sterno- 
 pericardial Hgament, called also the xipho-pericardial ligament (Fig. 370), passes to 
 the ensiform cartilage. On each side of the ascending aorta the pericardium sends 
 upward a diverticulum : the one on the left side, somewhat conical in shape, passes 
 upward and outward, between the arch of the aorta and the pulmonary artery, 
 as far as the ductus arteriosus, where it terminates in a csecal extremity, which is 
 attached by loose connective tissue to the obliterated duct (Fig. 367). The one on 
 the right side passes upward and to the right, between the ascending aorta and 
 
 Left subclavian artery 
 Bight pulmonary artery. 
 
 Right subclavian artery. 
 Left common 
 carotid artery. 
 
 Right common 
 carotid artery. 
 
 Inferior thyroid 
 _^__ vein. 
 
 . ./^^^^^ 
 
 "Aj^i-.. c^^lj^ ~ Vena azygos 
 
 '"'■ *'' (y f/ major. 
 
 Right pulmonary 
 veins. 
 
 Fig. 368. — Pericardium from behind. (From the same preparation as the preceding figure.) 
 
 vena cava superior, and also terminates in a csecal extremity. Below, the fibrous 
 layer is attached to the central tendon of the Diaphragm, and on the left side to 
 its muscular fibres. The pericardium is fixed to the Diaphragm by the anterior 
 phreno-pericardial ligament and by the lateral phreno-pericardial ligaments (Fig. 370). 
 The vessels receiving fibrous prolongations from this membrane are the aorta 
 the superior vena cava, the right and left pulmonary arteries, and the four pulmo- 
 nary veins. The inferior vena cava enters the pericardium through the central 
 tendon of the Diaphragm, and consequently it receives no covering from the 
 fibrous layer (Fig. 371). 
 
560 
 
 THE BLOOD -VASCULAB SYSTEM 
 
 The Serous Pericaxdium invests the heart, and is then reflected on the inner sur- 
 face of the fibrous pericardium. It consists, therefore, of a visceral layer (epicar- 
 dium) and a parietal layer. The former invests the surface of the heart, and the 
 commencement of the great vessels, to the extent of an inch and a half from 
 their origin ; from these it is reflected upon the inner surface of the fibrous layer. 
 The serous membrane encloses the aorta and pulmonary artery in a single tube, 
 so that a passage, termed the great transverse sinus of the pericardium (sinus trans- 
 versiis 'pericardii), exists between these vessels in front and the auricle behind. 
 This sinus is closed above and below but often to the right and left. The mem- 
 brane only partially covers the superior vena cava and the four pulmonary veins. 
 
 RIGHT 
 
 PULMONARY. 
 
 VEIN 
 
 PAR I ETA 
 PERICARDIUM 
 
 Fig. 369. — The line of reflection of the serous pericardium. (Modified from Poirier and Charpy.) 
 
 and scarcely covers the inferior cava, as this vessel enters the heart almost directly 
 after it has passed through the Diaphragm. A deep blind recess formed by the 
 serous pericardium is found behind the heart when that organ is raised up. 
 This recess runs backward between the left auricle and the posterior portion of 
 the fibrous pericardium, and forms a diverticulum between the heart and the 
 oesophagus. This recess is called the oblique sinus. It passes upward between 
 the inferior vena cava and the lower left pulmonary vein and terminates between 
 the right and left pulmonary veins. The inner surface of the pericardium 
 is covered with endothelium, which rests upon a mixture of fibrous and 
 elastic tissue, which is smooth and glistening, and secretes a serous fluid {liquor 
 
THE PERICARDIUM 
 
 561 
 
 'pericardii) , which serves to facilitate the movements of the heart. In the serous 
 layer of the pericardium are many blood-vessels, lymph vessels, and nerves. 
 
 Arteries of the Pericaxdium. — These are derived from the internal mammary and 
 its musculo-phrenic branch, and from the descending thoracic aorta. 
 
 Nerves of the Pericaxdium. — These are branches from the vagus, the phrenic, 
 and the sympathetic. 
 
 The Vestigial Fold of the Pericardium. — Between the left pulmonary artery and 
 subjacent pulmonary vein and behind the left extremity of the transverse sinus is 
 a triangular fold of the serous pericardium; it is known as the vestigial fold of 
 Marshall (ligamentum v. cavcB sinisiroe) . It is formed by the duplicature of the 
 serous layer over the remnant of the lower part of the left superior vena cava 
 
 SUPERIOR 
 VENA CAVA 
 
 INFERIOR 
 VENA CAVA 
 
 PHRENO- 
 
 PERICARDIAL 
 
 LIGAMENTS 
 
 OR STERNO- 
 RDIAL LIG- 
 TS 
 
 TERIOR 
 RFACE OF 
 RICARDIUM 
 
 XIPHO- 
 
 PERICARDIAL 
 
 LIGAMENTS 
 
 Fig. 370. — Ligaments of the pericardium. (Modified from Teutleben.) Right lateral view, showing the right 
 vertebra — pericardial ligaments, the right phreno-pericardial, and the superior and inferior sterno-pericardial 
 ligaments. (Poirier and Charpy.) 
 
 {v. cava sinistra) or the duct of Cuvier, which, after birth, becomes obliterated, 
 and remains as a fibrous band stretching from the left superior intercostal vein 
 to the left auricle, where it is continuous with a small vein, the oblique vein of 
 Marshall {v. ohliqua atrii sinistri [Marshalli]) , which opens into the coronary 
 sinus and is a remnant of the foetal left superior vena cava. 
 
 Surgical Anatomy. — Aspiration of the pericardium (paracentesis of the pericardium) is occa- 
 sionally though seldom performed. It is only to be thought of when pericardial effusion endangers 
 life. The operation is very dangerous, because the effusion lifts the heart and pushes it forward. 
 
 36 
 
562 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 and the needle is apt to wound the heart or even enter one of the cavities. There is also danger 
 of wounding the internal mammary artery. The operation is never to be thought of in puru- 
 lent pericarditis. The safest way to aspirate is to introduce the needle in the fifth interspace 
 two inches to the left of the sternum and push it straight backward. 
 
 A better operation, even in a case of serous effusion, and one invariably selected in purulent 
 pericarditis, is incision (pericardotomy). A portion of the cartilage of the fifth rib of the left 
 side is excised. The pericardium is exposed and is punctured, to learn the nature of the 
 contained fluid, and is then incised. By this method the surgeon avoids opening the pleural 
 cavity, and can obtain free drainage if pus is found. 
 
 Porter maintains that by "reason of the uncertain and varying relations of the pleura, and 
 also of the anterior position of the heart, whenever the pericardial sac is distended with fluid, 
 aspiration of the pericardium is a much more dangerous procedure than open incision when 
 done by skilled hands." 
 
 RIGHT 
 
 PULMONARY 
 
 VETNS 
 
 PERICARDIUM 
 
 PULMONARY 
 
 PERICARDIUM 
 
 DIAPriRAQM 
 
 Fig. 371.— Posterior wall of the pericardium, after the removal of the heart, .showing the relation of the serous 
 pericardium to the great vessels. (From a formalin preparation by Prof. Birmingham.) (Cunningham.) 
 
 THE HEART (COR). 
 
 The heart is a hollow muscular organ of a conical form, placed between the 
 lungs, and enclosed in the cavity of the pericardium. 
 
 Position (Fig. 372).— The heart is placed obliquely in the chest: the broad 
 attached end, or base (basis cordis), is directed upward, backward, and to the right, 
 and corresponds with the dorsal vertebra, from the fifth to the eighth inclusive; the 
 apex (apex cordis) is directed downward, forward, and to the left, and corresponds 
 to the space between the cartilages of the fifth and sixth ribs, three-quarters of an 
 
THE HEART 
 
 563 
 
 inch to the inner side, and an inch and a half below the left nipple, or about three 
 and a half inches from the middle line of the sternum. The heart is placed behind 
 the sternum, and projects farther into the left than into the right half of the cavity 
 of the chest, extending from the median line about three inches in the former 
 direction, and only one and a half in the latter; about one-third of the heart lies 
 to the right and two-thirds to the left of the mesial plane. The antero-superior 
 surface (fades sternocostalis) is round and convex, directed upward and forward, 
 is formed chiefly by the right auricle and ventricle, together with a small part of 
 the left ventricle. It lies behind the middle portion of the sternum and the costal 
 cartilages of the third, fourth, fifth, and sixth ribs on both sides. On account of 
 
 Fig. 372. — Pusition of the heart. The pericardium laid open. Adult male. (Poirier and Charpy.) 
 
 the heart's inclination to the left side, only a small part of it lies behind the carti- 
 lages of the right ribs. Lying in front of the heart, between it and the anterior 
 chest-wall, is the thin anterior margin of the lungs, covered by the pleura. On 
 the left side, however, owing to the notch in the anterior margin of the left 
 lung (incisura cardiaca), there is a portion of the pericardium lying in contact 
 with the Triangularis sterni muscle. This area is called the area of greatest or 
 of absolute cardiac duhiess or the area of superficial cardiac dulness. The postero- 
 inferior surface of the heart (fades dia^hragmatica) , which looks downward rather 
 
564 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 than backward, is flattened and rests upon the Diaphragm, and is formed chiefly 
 by the left ventricle. The right or lower border is long, thin, and sharp; the left 
 or upper border short, but thick and round. 
 
 Size and Weight. — The heart, in the adult, measures five inches in length, 
 three inches and a half in breadth in the broadest part, and two inches and a half 
 in thickness. The prevalent weight, in the male, varies from ten to twelve ounces; 
 in the female, from eight to ten: its proportions to the body being as 1 to 169 in 
 males; 1 to 149 in females. The heart continues increasing in weight, and also 
 in length, breadth, and thickness, up to an advanced period of life: this increase 
 is more marked in men than in women. 
 
 •"{,«-!nii.;i".r8i..i ,. 
 
 LEFT APPENDIX 
 
 AURICUUE 
 
 LEFT AuniCULA 
 
 VENTRICULA 
 
 GROOVE 
 
 CORONARY 
 SINUS 
 
 SULCUS 
 TERMINALES 
 
 INTERARTICULAR 
 SULCUS 
 
 (ESOPHAGUS 
 
 '^*i£fitti/ 
 
 Fig. 373. — Base of the heart in place. The attachments of the pericardium are outlined in red. 
 
 (Poirier and Charpy.) 
 
 Capacity of the Cavities of the Heart. — This matter is in dispute. Professor 
 Cunningham believes that during life the capacity of the ventricles is nearly iden- 
 tical, each holding about four ounces of blood. Each auricle holds a little less 
 than four ounces. Stewart maintains that at each heart beat each ventricle 
 throws out only eighty-seven grams of blood. Morrant Baker^ says that, "taking 
 the mean of various estimates, it may be inferred that each ventricle is able to 
 contain four to six ounces of blood." / 
 
 Fat upon the Heart. — Normally there is a certain amount of fat upon the 
 surface of the heart. This begins to appear in the early weeks of life and 
 increases in amount as age advances. It is found upon the surface of the 
 muscles and along the course of the vessels. Poirier is of the opinion that the 
 cardiac fat on the anterior surface of the heart is arranged in three movable 
 
 ^ Kirke's Physiology, 10th ed., p. 156. 
 
THE HEART 555 
 
 pads, which act as valves and fill vacant spaces about the heart created during 
 the cardiac contractions/ 
 
 Component Parts. — The heart is subdivided by a muscular septum into two- 
 lateral halves, which are named respectively the right or pulmonary heart and the 
 left or systemic heart; and a transverse constriction subdivides each half of the 
 organ into two cavities, the upper cavity on each side being called the auricle, 
 the lower the ventricle. The course of the blood through the heart cavities and 
 blood-vessels has already been described (page 555). 
 
 The division of the heart into four cavities is indicated by grooves upon its sur- 
 face. The groove separating the auricles from the ventricles is called the auriculo- 
 ventricular groove (sulcus coronarius). It is deficient, in front, where it is crossed 
 by the root of the pulmonary artery. It contains the trunks of the nutrient vessels 
 of the heart. The auricular portion occupies the base of the heart, and is sub- 
 divided into two cavities by a median septum. The two ventricles are also sepa- 
 rated into a right and left by two furrows, the interventricular grooves {sulci longi- 
 tudinales), which are situated one on the anterior (sulcus longitudinalis anterior), 
 the other on the posterior (sulcus longitudinalis posterior) surface; these extend 
 from the base of the ventricular portion to near the apex of the organ ; the former 
 being situated nearer to the left border of the heart, and the latter to the right. 
 It follows, therefore, that the right ventricle forms the greater portion of the 
 anterior surface of the heart, and the left ventricle more of its posterior surface. 
 The internal surface of the heart is lined with endocardium. 
 
 The auricular portion occupies the base of the heart and is subdivided into two 
 cavities or auricles (atria] by a septum. As before stated, this portion of the heart 
 corresponds to the middle segment of the dorsal spine. Its form is quadrilateral 
 in shape, and has two processes extending upward from its two upper angles, 
 called the auricular appendices (appendices auriculce), between which are found 
 the aorta and the pulmonary artery. The greater part of the base of the heart 
 is formed by the left auricle. Its boundaries are, above, the pulmonary artery; 
 below, the coronary sinus; on the left it is bounded by the left superior and 
 inferior pulmonary veins, while on the right side it is limited by the sulcus 
 terminalis. The latter corresponds to a ridge in the interior of the auricle, 
 called the crista terminalis. Running vertically on this surface, just to the 
 left of the openings of the two venae cavae, is the interauricular furrow, which 
 exactly indicates the proportion of the base of the heart formed by each 
 auricle. 
 
 Each of the cavities should now be separately examined. 
 
 The Right Auricle^ (atrium dextrum) is a little larger than the left, its walls 
 somewhat thinner, measuring about one line. It consists of two parts : a principal 
 cavity, the sinus venosus, situated posteriorly, and an anterior, smaller portion, 
 the appendix auriculae. The right auricle is separated from the left auricle by 
 the interauricular septum (septum atriorum). Part of tliis septum is muscular; 
 part is composed of connective tissue. 
 
 The sinus venosus (sinu3 venarum) is the large quadrangular cavity, placed 
 between the two venae cavse; its walls are extremely thin; it is connected below 
 with the right ventricle, and internally with the left auricle, being free in the 
 rest of its extent. It is derived from a portion of the sinus reuniens of the 
 fcetal heart. 
 
 The right auricular appendix (auricula dextra) , so-called from its fancied resem- 
 blance to a dog's ear, is a small conical muscular pouch, the margins of which 
 present a dentated edge. It projects from the sinus forward and to the left 
 side, overlapping the root of the aorta. 
 
 ' L'appariel sero-graisseux. La Presse M6dicale, December 7, 1904. 
 
 2 In the new nomenclature the auricle is called the atrium, and auricular appendix is called the auricle. 
 
566 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 To examine the interior of the right auricle, an incision should be made along its right border, 
 from the entrance of the superior vena cava to that of the inferior. A second cut is to be made 
 from the centre of this first incision to the tip of the auricular appendix, and the flaps raised. 
 
 The internal surface of the right auricle is smooth, except in the appendix 
 and adjacent part of the anterior wall of the sinus venosus, where the muscular 
 wall is thrown into parallel ridges resembling the teeth of a comb and hence 
 named the musculi pectinati. These end behind on a vertical smooth ridge, the 
 
 Bristle passed through. 
 Right Auricula- Ventricular opening. 
 
 Fig. 374. — The right auricle and ventricle laid open, the anterior walls of both being removed. 
 
 crista terminalis of His, the position of which is indicated on the surface of the 
 distended auricle by a furrow, the sulcus terminalis of His. The sulcus terminalis 
 passes from in front of the superior vena cava to the left of the inferior vena cava. 
 It represents the line of fusion of the sinus venosus of the embryo with the primi- 
 tive auricle proper. 
 
 The right auricle presents the following parts for examination: 
 
 Superior cava. 
 Inferior cava. 
 Openings \ Coronary sinus. 
 
 Foramini Thebesii. 
 Auriculo-ventricular. 
 
 Fossa ovalis. 
 
 Annulus ovalis. 
 
 Tuberculum Loweri. 
 
 Musculi pectinati. 
 
 The superior vena cava returns the blood from the upper half of the body, and 
 opens into the upper and back part of the auricle, the direction of its orifice being 
 downward and forward. The superior vena cava does not possess valves. 
 
 The inferior vena cava, larger than the superior, returns the blood from the 
 lower half of the body, and opens into the lowest part of the auricle near the 
 
 Valves I Eustachian. 
 C Coronary. 
 
THE HEART 567 
 
 septum, the direction of its orifice being upward and inward. The direction of 
 a current of blood through the superior vena cava would consequently be toward 
 the auriculo-ventricular orifice, whilst the direction of the blood through the 
 inferior cava would be toward the auricular septum. This is the normal direction 
 of the two currents in foetal life. The inferior vena cava does not possess valves 
 until its termination at the right auricle. 
 
 The coronary sinus (sinus coronarius) opens into the auricle, between the inferior 
 vena cava and the auriculo-ventricular opening. It returns the blood from the 
 substance of the heart, and is protected by a semicircular fold of the lining mem- 
 brane of the auricle, the coronary valve or valve of Thebesius. The sinus, before 
 entering the auricle, is considerably dilated — nearly to the size of the end of the 
 little finger. Its wall is partly muscular, and at its junction with the great coronary 
 vein it is somewhat constricted and is furnished with a valve consisting of two 
 unequal segments. 
 
 The foramini Thebesii (foramina venarum minimarum) are numerous minute 
 fossse or apertures on various parts of the inner surface of the auricle. Many of 
 these foramina have at their points the minute openings of small veins (vence 
 TninimoB cordis). They return the blood directly from the muscular substance 
 of the heart. Some of these foramina are minute depressions in the walls of the 
 heart, presenting a closed extremity. 
 
 The right auriculo-ventricular opening or the tricuspid orifice (ostium venosum 
 dextrum) is the large oval aperture of communication between the right auricle 
 and the ventricle, to be presently described. 
 
 The Eustachian valve (valvula vencB caves inferioris [Eu^tachii'\) is situated 
 between the anterior margin of the inferior vena cava and the auriculo-ventricular 
 orifice. It is semilunar in form, its convex margin being attached to the wall 
 of the vein; its concave margin, which is free, terminating in two cornua, of 
 which the left is attached to the anterior edge of the annulus ovalis, the right 
 being lost on the wall of the auricle. The valve is formed by a duplicature of the 
 lining membrane of the auricle and contains a few muscular fibres. 
 
 In the foetus this valve is of large size, and serves to direct the blood from the 
 inferior vena cava, through the foramen ovale, into the left auricle. 
 
 In the adidt it is occasionally large, and may assist in preventing the reflux 
 of blood into the inferior vena cava; more commonly it is small, and its free 
 margin presents a cribriform or filamentous appearance; occasionally it is alto- 
 gether wanting. 
 
 The coronary valve or valve of Thebesius (valvulce sinv^ coronarii [^ThebesHy) 
 is a semicircular fold of the lining membrane of the auricle, protecting 
 the orifice of the coronary sinus. It prevents the regurgitation of blood 
 into the sinus during the contraction of the auricle. This valve is occasionally 
 double. 
 
 The fossa ovalis is an oval depression corresponding to the situation of the 
 foramen ovale in the foetus. It is situated at the lower part of the septum atriorum, 
 above and to the left of the orifice of the inferior vena cava. In foetal life an 
 opening, the foramen ovale, exists at this point between the two auricles; almost 
 immediately after birth the valve-like edge is pressed down by the increased 
 pressure in the left auricle and by the tenth day it passes to the annulus and 
 closes the opening. 
 
 The annulus ovalis (limbus josser ovalis [VieusseniiJ) is a prominent oval margin 
 which surrounds anteriorly and superiorly the fossa ovalis. It is most distinct 
 above and at the sides; below, it is deficient. A small slit-like valvular opening 
 is occasionally found, at the upper margin of the fossa ovalis, which leads 
 upward beneath the annulus into the left auricle, and is the remains of the 
 aperture between the two auricles in the foetus. 
 
568 THE BLOOD -VASCULAR SYSTEM 
 
 The tubercle of Lower (tuherculum intervenosum {Loweri\) is a small projection 
 on the interauricular septum between the fossa ovalis and the opening of the 
 superior vena cava. It is most distinct in the hearts of quadrupeds; in man it 
 is scarcely visible. It was supposed by Lower to direct the blood from the 
 superior cava toward the auriculo-ventricular opening. 
 
 The Left Auricle {atrium sinistrum) is rather smaller than the right; its walls 
 are thicker, measuring about one line and a half; and it consists, like the right, 
 of two parts, a principal cavity, or sinus, and an appendix auriculae. 
 
 The sinus is cuboidal in form, and concealed in front by the pulmonary artery 
 and aorta; internally, it is separated from the right auricle by the septum auricu- 
 larum (septum atriorum); behind, it receives on each side two pulmonary veins, 
 being free in the rest of its extent. 
 
 The left auricular appendix {auricula sinistra) is somewhat constricted at its 
 junction with the auricle; it is longer, narrower, and more curved than that of 
 the right side, and its margins are more deeply indented, presenting a kind of 
 foliated appearance. Its direction is forward and toward the right side, over- 
 lapping the root of the pulmonary artery. 
 
 Within the auricle the following parts present themselves for examination: 
 
 The openings of the four pulmonary veins. 
 Auriculo-ventricular opening. 
 Musculi pectinati. 
 Foramina Thebesii. 
 
 The pulmonary veins, four in number, open, two into the right and two into 
 the left side of the auricle. The two left veins frequently terminate by a common 
 opening. They are not provided with valves. 
 
 The auriculo-ventricular opening or mitral orifice {ostium venosum ventriculi 
 sinistri) is the large oval aperture of communication between the left auricle 
 and the left ventricle. It is rather smaller than the corresponding opening on 
 the opposite side (see note, page 569). 
 
 The musculi pectinati are fewer in number and smaller than on the right side; 
 they are confined to the inner surface of the auricular appendix. 
 
 On the inner surface of the septum atriorum may be seen a lunated impres- 
 sion bounded below by a crescentic ridge the concavity of which is turned upward. 
 The depression is just above the fossa ovalis in the right auricle. The inner sur- 
 face of the auricle shows foramini Thebesii and venae minimis cordis. 
 
 To examine the interior of the left ventricle, make an incision a little to the left of the anterior 
 interventricular groove from the base to the apex of the heart, and carry it up from thence, 
 a little to the left of the posterior interventricular groove, nearly as far as the auriculo-ventricular 
 groove. 
 
 The ventricular portion of the heart is conical in shape with its base extending 
 backward and upward and fitting against the atrii of the auricles. Its apex 
 constitutes the apex of the heart {a'pex cordis) and extends to the fifth intercostal 
 space three and a quarter inches to the left of the middle line. The ventricles 
 are thick and muscular and have an antero -superior surface (fades sternalis) and 
 a postero-inferior surface (fades diaphragmatic 2) and two borders, a right and a 
 left border. The antero-superior surface is composed mainly of the right ven- 
 tricle; coursing on this surface, nearer the left border than the right from the 
 auriculo-ventricular groove to the apex, is the anterior interventricular groove 
 (sulcus longitudinalis anterior) . The inferior surface rests on the diaphragm and 
 is chiefly made by the left ventricle ; it is also traversed by a groove called the 
 inferior or posterior interventricular groove (sidcus longitudinalis posterior). The 
 two grooves meet in a groove (incisura apicis cordis) at the right side of the 
 
THE HEART 569 
 
 apex of the heart. Of the two borders of the ventricular portion the right is 
 sharp and thin (margo acutus) and is a continuation of the sulcus terminahs of 
 the base of the heart. It extends from right to left. The left border is thick 
 and rounded {margo ohtusus). The base of the ventricles is perforated by four 
 large openings, namely, the aorta, the pulmonary artery, the right and left 
 auriculo-ventricular openings. 
 
 The Right Ventricle (ventriculus dexter) is triangular in form, and extends 
 from the right auricle to near the apex of the heart. Its antero-superior surface 
 is rounded and convex, and forms the larger part of the front of the heart. Its 
 inferior surface is flattened, rests upon the Diaphragm, and forms only a small 
 part of the back of the heart. Its posterior wall is formed by the partition between 
 the two ventricles, the interventricular septum (septum ventriculorum) , so that a 
 transverse section of the cavity presents a semilunar outline. The surface of 
 the septum is convex and bulges into the cavity of the right ventricle. The 
 upper and inner angle of the ventricle is prolonged into a conical pouch, the 
 infundibulum (conus arteriosus), from which the pulmonary artery arises. The 
 balance of the ventricle, the body, is the portion into which the auriculo- 
 ventricular orifice opens. The conus arteriosus is marked off from the body of 
 the ventricle by a muscular projection (crista swpraventricularis) . The walls of 
 the right ventricle are thinner than those of the left, the proportion between them 
 being as 1 to 3. The wall is thickest at the base, and gradually becomes thinner 
 toward the apex. 
 
 To examine the interior of the right ventricle, its anterior wall should be turned downward 
 and to the right in the form of a triangular flap. This is accomplished by making two incisions : 
 (1) from the pulmonary artery to the apex of the ventricle parallel to, but a little to the right 
 of, the anterior interventricular furrow; (2) another, starting from the upper extremity of the 
 first and carried outward parallel to, but a little below, the auriculo-ventricular furrow, care 
 being taken not to injure the auriculo-ventricular valve. 
 
 The following parts present themselves for examination: 
 
 ^ . f Auriculo-ventricular. 
 P ^ ^ Opening of the pulmonary artery. 
 
 Valves {Tricuspid. 
 I Semilunar. 
 
 And a muscular and tendinous apparatus connected with the tricuspid valve: 
 
 Columnse carnese. Chordae tendinese. 
 
 The right auriculo-ventriculax opening or the tricuspid orifice {ostium venosum ven- 
 triculi dextri) is the large oval aperture of communication between the auricle and 
 ventricle. It is situated at the base of the ventricle, near the right border of 
 the heart. It is about an inch and a half in diameter,^ oval from side to side, 
 surrounded by a fibrous ring and covered by the lining membrane of the heart; 
 it is considerably larger than the corresponding aperture on the left side, being 
 sufficient to admit the ends of four fingers. It is guarded by the tricuspid 
 valve. 
 
 The opening of the pulmonary artery (ostium arteriosum) is circular in form, 
 and is situated at the summit of the conus arteriosus, close to the septum ven- 
 triculorum. It is placed above and on the left side of the auriculo-ventricular 
 
 ' In the Pathological Transactions, vol. vi. p. 119, Dr. Peacock has given some careful researches upon the 
 weight and tlimen.sions of the heart in health and di.sease. He states, as a result of his investigations, that 
 in the healthy athilt heart the right auriculo-ventricular aperture has a mean circumference of 54,4 lines, or 
 420/04 inches; the left auriculo-ventricular aperture a mean circumference of 44.3 lines, or 3*;24 inches; the pulmonic 
 orifice of 40 lines, or 3'-*/2i inches; and the aortic orifice of 35.5 lines, or 3'--/o4 inches; but the dimensions of the 
 orifices varied greatly in"different cases, the right auriculo-ventricular aperture having a range of from 40 to 50 
 lines, and the others in the same proportion. — Ed. of 15th English edition. 
 
570 THE BLOOD -VASCULAR 8Y8TEM 
 
 opening, upon the anterior aspect of the heart. Its orifice is guarded by the 
 pulmonary semilunar valves. 
 
 The tricuspid valve (valvula tricuspidalis) consists of three segments or cusps 
 (cuspides) of a triangular or trapezoidal shape, each formed by a duplicature of 
 the lining membrane of the heart, strengthened by a layer of fibrous tissue, which 
 contains, according to Kiirschner and Senac, muscular fibres. These segments 
 are connected by their bases to the oval fibrous ring surrounding the auriculo- 
 ventricular orifice (annulus fibrosus dexter), and by their sides with one another, 
 so as to form a continuous annular membrane, which is attached round the 
 margin of the auriculo-ventricular opening, their free margins and ventricular 
 surfaces affording attachment to a number of delicate tendinous cords, the 
 chordae tendineae. The largest and most movable segment is placed toward 
 the left side of the auriculo-ventricular opening, and is interposed between that 
 opening and the infundibulum; hence it is called the left or infundibulax cusp 
 (cuspis medialis). Another segment corresponds to the right part of the front 
 of the ventricle, the right or marginal cusp {cuspis anterior) , and a third to its 
 posterior wall, the posterior or septal cusp (cuspis posterior) . The central part of 
 each segment is thick and strong: the lateral margins are thin and translucent. 
 The chordse tendineae are connected with the adjacent margins of the principal 
 segments of the valve, and are further attached to each segment in the following 
 manner: 1. Three or four reach the attached margin of each segment, where 
 they are continuous with the auriculo-ventricular tendinous ring. 2. Others, four 
 to six in number, are attached to the central thickened part of each segment. 3. 
 The most numerous and finest are connected with the marginal portion of each 
 segment. 
 
 The columnse cameae (trabeculoe earners) are the rounded muscular columns 
 which project from nearly the whole of the inner surface of the ventricle, except- 
 ing near the opening of the pulmonary artery, where the wall is smooth. They 
 may be classified, according to their mode of connection with the ventricle, into 
 three sets. The first set merely forms prominent ridges on the inner surface of 
 the ventricle, being attached by their entire length on one side, as well as by 
 their extremities. The second set are attached by their two extremities, but are 
 free in the rest of their extent; while the third set (musculi papillares) are attached 
 by one extremity to the wall of the heart, the opposite extremity giving attach- 
 ment to the chordae tendineae. There are two papillary muscles, the anterior and 
 the posterior: of these, the anterior is the larger; its chordse tendinse are connected 
 with the right and left segments of the tricuspid valve. The posterior is not 
 always single, but sometimes consists of two or three muscular columns; its 
 chordae tendineae are connected with the posterior and the right segments of the 
 tricuspid valve. In addition to these, some few chordae may be seen springing 
 directly from the ventricular septum, or from small eminences on it, and passing 
 to the left and posterior segments. A fleshy band, well marked in the ox and 
 some other animals, is frequently seen passing from the base of the anterior 
 papillary muscle to the interventricular septum. From its attachments it may 
 assist in preventing overdistention of the auricle, and so has been named the 
 moderator band. 
 
 The right auriculo-ventricular orifice allows the blood to pass freely from the 
 right auricle into the right ventricle, and it will be noted that the surface of the 
 tricuspid valve next the blood-current is quite smooth. When the right ventricle 
 contracts to force the blood into the pulmonary artery, the segments of the tri- 
 cuspid valve come together and close the auriculo-ventricular opening, and so 
 prevent the blood from passing back into the auricle. The papillary muscles 
 and chordae tendineae moor the segments of the valve and prevent their being 
 forced through into the auricle by the weight of blood behind them. 
 
THE HEART 57I 
 
 The semilunar valves (valvulcB semilunares a. pulmonalis) , three in number,* 
 guard the orifice of the pulmonary artery. They consist of three semicircular 
 folds : two of which are anterior and one of which is posterior. They are formed 
 by duplicatures of the lining membrane of the ventricle, strengthened by fibrous 
 tissue. They are attached, by their convex margins, to the wall of the artery, at its 
 junction with the ventricle, the straight border being free, and directed upward in 
 the lumen of the vessel. The free margin of each is somewhat thicker than the rest 
 of the valve, is strengthened by a bundle of tendinous fibres, and presents, at its 
 middle, a small projecting thickened nodule, consisting of bundles of interlacing 
 connective-tissue fibres with branched connective-tissue cells and some few elastic 
 fibres. Such a nodule is called the corpus Arantii or body cf Arangi {nodulus valvules 
 semilunaris [Arantii^) . From this nodule tendinous fibres radiate through the valve 
 to its attached margin, and these fibres form a constituent part of its substance 
 throughout its whole extent, excepting two narrow lunated portions, the lunulas 
 (lunulw valvularum semilunarium) , placed one on each side of the nodule imme- 
 diately adjoining the free margin; here the valve is thin,' and formed merely by the 
 Uning membrane. During the passage of the blood along the pulmonary artery 
 these valves are opened, and the course of the blood along the tube is uninter- 
 rupted ; but during the ventricular diastole, when the current of blood along the 
 pulmonary artery is checked and partly thrown back by its elastic walls, these 
 valves become immediately expanded, and effectually close the entrance of the 
 tube. When the valves are closed, the lunated portions of each are brought into 
 contact with one another by their opposed surfaces, the three corpora Arantii fill- 
 ing up the small triangular space that would be otherwise left by the approxima- 
 tion of the three semilunar valves. 
 
 Between the semilunar valves and the commencement of the pulmonary artery 
 are three pouches or dilatations, one behind each valve. These are the pulmonary 
 sinuses of Valsalva. Similar sinuses exist between the semilunar valves and the 
 commencement of the aorta; they are larger than the pulmonary sinuses. The 
 blood, in its regurgitation toward the heart, finds its way into these sinuses, and 
 so shuts down the valve-flaps. 
 
 In order to examine the interior of the left auricle, make an incision on the posterior surface 
 of the auricle from the pulmonary veins on one side to those on the other, the incision being 
 carried a little way into the vessels. Make another incision from the middle of the horizontal 
 one to the appendix. 
 
 The Left Ventricle (ventriculus sinister) is longer and more conical in shape 
 than the right ventricle, and on transverse section its cavity presents an oval or 
 nearly circular outline. It forms a small part of the anterior surface of the heart 
 and a considerable part of its posterior surface. It also forms the apex of the 
 heart by its projection beyond the right ventricle. Its walls are much thicker 
 than those of the right side, the proportion being as 3 to 1 . They are thickest oppo- 
 site the widest part of the ventricle, becoming gradually thinner toward the base, 
 and also toward the apex, which is the thinnest part. 
 
 The following parts present themselves for examination : 
 
 J Auriculo-ventricular. ,,. , ( Mitral. 
 
 I Aortic. ^^^^^M Semilunar. 
 
 Chordae tendinese. Columnse carnese. 
 
 The left auriculo-ventricular opening or the mitral orifice (ostium venosum ven- 
 triculi sinistri) is placed below and to the left of the aortic orifice. It is a little 
 
 ' Thepulmonary semilunar valves have been found to be two in number instead of three (Dr. Hand, of St. 
 Paul, Mjnn., in North Western Med. and Surg. Journ., July, 1873), and the same variety is more frequently 
 noticed in the aortic semilunar valves. — Ed. of 15th English edition. 
 
572 
 
 THE BLOOD -VASCULAB SYSTEM 
 
 smaller than the corresponding aperture of the opposite side, admitting only two 
 fingers; but, like it, is broader in the transverse than in the antero-posterior 
 diameter. Its right, posterior, and left sides are surrounded by a dense horseshoe- 
 shaped fibrous ring (annulus fibrosus sinister) . The orifice is guarded by the 
 mitral valves, which are covered with endocardium. 
 
 The aortic opening (ostium arteriosum) is a circular aperture, in front and to 
 the right side of the auriculo-ventricular opening, from which it is separated by 
 one of the segments of the mitral valve. Its orifice is guarded by the semilunar 
 valves. The portion of the ventricle immediately below the aortic orifice is often 
 termed the aortic vestibule of Sibson. It possesses fibrous instead of muscular 
 walls, and so does not collapse during the ventricular diastole ; it thus gives space 
 for the segments of the aortic valve during its closure. 
 
 Bristle passed through left 
 auriculo-ventricular opening. 
 
 Passed through aortic opening. 
 
 Fig. 375. — The left auricle and ventricle laid open, the posterior walls of both being removed. 
 
 The mitral or bicuspid valve (valvula bicuspidalis) is attached to the circumfer- 
 ence of the auriculo-ventricular orifice in the same way that the tricuspid valve is 
 on the opposite side. It is formed by a duplicature of the lining membrane, 
 strengthened by fibrous tissue, and contains a few muscular fibres. It is larger 
 in size, thicker, and altogether stronger than the tricuspid, and consists of two 
 segments of unequal size. The larger segment, the anterior or aortic cusp (cuspis 
 anterior) , is placed in front and to the right between the auriculo-ventricular and 
 aortic orifices, the smaller, the posterior or marginal cusp (cuspis posterior), is 
 placed to the left and behind the opening, close to the wall of the ventricle. Two 
 smaller segments are usually found at the angles of junction of the larger. The 
 mitral valve-flaps are furnished with chordae tendinese, the mode of attachment 
 of which is precisely similar to those on the right side; but they are thicker, 
 stronger, and less numerous. 
 
 The aortic semilunar valves (valvules semilunares aortce) surround the orifice of 
 the aorta; one is posterior (valvula semilunaris posterior)', one right (valvula 
 
THE HEART 
 
 573 
 
 semilunaris dextra) , and one left {valvula semilunaris sinistra) : they are similar in 
 structure and in their mode of attachment to those of the pulmonary artery. They 
 are, however, larger, thicker, and stronger than those of the right side; the lunulas 
 are more distinct and the corpora Arantii larger and more prominent. Opposite 
 each segment the wall of the aorta presents a slight dilatation or bulging, the 
 sinus of Valsalva. 
 
 The columnae cameae admit of a subdivision into three sets, like those upon 
 the right side; but they are smaller, more numerous, and present a dense inter- 
 lacement, especially at the apex, and upon the posterior wall. Those attached by 
 one extremity only, the musculi papillares, are two in number, being connected 
 
 kilmonary 
 artery. 
 
 Fig. 376. — Section of the heart, showing the interventricular septum. 
 
 one to the anterior, the other to the posterior wall; they are of large size, and 
 terminate by free rounded extremities, from which the chordae tendineae arise. 
 
 The septum between the two ventricles {senium ventriculorum) is thick and 
 muscular, especially below (Fig. 376). At its upper part it suddenly tapers oflF, 
 becomes destitute of muscular fibres, and consists only of fibrous tissue, covered 
 by two layers of endocardium; and on the right side also covered, during dias- 
 tole, by one of the flaps of the tricuspid valve. This upper portion is termed 
 the undefended or membranous part of the septum (septum memhranaceum ven- 
 triculorum), and is continued upward and forms the septum between the 
 aortic vestibule and the right auricle. It is derived from the lower part of 
 the aortic septum of the foetus, and an abnormal communication may exist at 
 this part, owing to defective development of this septum. 
 
574 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 Structure of the Heart. — The heart is a hollow muscular organ and its walls 
 are divisible into three layers : the endocardium, myocardium, and visceral layer of 
 the pericardium (page 560). 
 
 The Endocardium is the lining membrane of the heart. It is composed of 
 endothelial cells resting upon a connective-tissue membrane which contains 
 unstriated muscle cells and elastic tissue. This connective-tissue membrane of 
 the endocardium is attached to the myocardium by loose elastic tissue. The endo- 
 thelial layer of the endocardium is continuous with the endothelial coat of the 
 blood-vessels. The endocardium is more opaque on the left than on the right 
 side of the heart, thicker in the auricles than in the ventricles, and thickest in 
 the left auricle. It is thin on the musculi pectinati and on the columnse carneee, 
 but thicker on the smooth parts of the auricular and ventricular walls and on the 
 tips of the musculi papillares. 
 
 The Fibrous Rings {annuli fibrosi) surround the auriculo-ventricular and arterial 
 orifices ; they are stronger upon the left than on the right side of the heart. The 
 auriculo-ventricular rings serve for the attachment of the muscular fibres of the 
 auricles and ventricles, and also for the mitral and tricuspid valves; the ring on the 
 
 LEFT AURICULO- 
 VENTRICULAR ORIFICE 
 
 Fig. 377. — Fibrous zones at the base of the ventricles. (Poirier and Charpy.) 
 
 left side is closely connected by its right margin with the aortic arterial ring. Be- 
 tween these and the right auriculo-ventricular ring is a mass of fibrous tissue, and in 
 some of the larger animals, as the ox and elephant, a nodule of bone, the os cordis. 
 
 The fibrous rings surrounding the arterial orifices serve for the attachment of 
 the great vessels and semilunar valves. Each ring receives, by its ventricular 
 margin, the attachment of the muscular fibres of the ventricles; its opposite margin 
 presents three deep semicircular notches, within which the middle coat of the 
 artery (which presents three convex semicircular segments) is firmly fixed, the 
 attachment of the artery to its fibrous ring being strengthened by the thin cellular 
 coat and serous membrane externally and by the endocardium within. It is 
 opposite the margins of these semicircular notches, in the arterial rings, that the 
 endocardium by its reduplication forms the semilunar valves, the fibrous structure 
 of the ring being continued into each of the segments of the valve at this part. 
 The middle coat of the artery in this situation is thin, and the sides of the vessel are 
 dilated to form the sinuses of Valsalva. 
 
 The Myocardium is composed of muscle fibres which differ from ordinary striated 
 muscle fibres, and are called cardiac fibres. Between individual fibres and be- 
 tween bundles of fibres is connective tissue carrying capillaries. 
 
THE HEART 
 
 575 
 
 The Muscular Structure of the heart consists of bands of fibres which present 
 an exceedingly intricate interlacement. They are of a deep red color and marked 
 with transverse striae. 
 
 The muscular fibres of the heart admit of a subdivision into two groups, those 
 of the auricles and those of the ventricles, which are quite independent of one 
 another. 
 
 Fibres of the Auricles (Fig. 378). — These are disposed in two layers — a 
 superficial layer common to both cavities, and a deep layer proper to each. The 
 superficial fibres are more distinct on the anterior surface of the auricles, across 
 the bases of which they run in a transverse direction, forming a thin but incomplete 
 layer. Some of these fibres pass into the septum atriorum. The internal or deep 
 fibres proper to each auricle consist of two sets, looped and annular fibres. The 
 looped fibres pass upward over each auricle, being attached by two extremities 
 to the corresponding auriculo-ventricular rings in front and behind. The annular 
 fibres surround the whole extent of the auricular appendices, and are continued 
 upon the walls of the vente cava? and coronary sinus on the right side, and upon 
 the pulmonary veins on the left side, at their connection with the heart. In the 
 appendices they interlace with the longitudinal fibres. 
 
 Fig. 378. — The arrangement of the muscles of the auricles. (Poirier and Charpy.) 
 
 Fibres of the Ventricles. — These are arranged in an exceedingly complex 
 manner, and the accounts given by various anatomists differ considerably. This 
 is probably due partly to the fact that the various layers of muscular fibres of 
 which the heart is said to be composed are not independent, but their fibres are 
 interlaced to a considerable extent, and therefore any separation into layers must 
 be to a great extent artificial; and also partly to the fact, pointed out by Henle, 
 that there are varieties in the arrangement due to individual differences. If the 
 epicardium and the subjacent fat are removed from a heart which has been sub- 
 jected to prolonged boiling, so as to dissolve the connective tissues, the superficial 
 fibres of the ventricles will be exposed. They will be seen to commence at the base 
 of the heart, where they are attached to the tendinous rings around the orifices, 
 and to pass obliquely downward toward the apex, with a direction from right to 
 left. At the apex the fibres turn suddenly inward into the interior of the ventricle, 
 forming what is called the vortex (Fig. 379). On the back of the heart it will be 
 seen that the fibres pass continuously from one ventricle to the other over the inter- 
 ventricular groove; and the same thing will be noticed on the front of the heart at 
 the upper and lower end of the anterior interventricular groove, but in the middle 
 portion of this groove the fibres passing from one ventricle to the other are inter- 
 
576 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 rupted by fibres emerging from the septum along the groove; many of the super- 
 ficial fibres pass in also at this groove to the septum. The vortex is produced, 
 
 as stated above, by the sudden turning 
 inward of the superficial fibres in a 
 peculiar spiral manner into the deepest 
 portion of the wall of the ventricle. 
 Those fibres which descended on the 
 posterior surface of the heart enter the 
 left ventricle at the vortex, and, ascend- 
 ing, form the posterior part of the inner 
 layer of muscular fibres lining this 
 cavity and the right (posterior) mus- 
 culus papillaris; those fibres which 
 descend on the front of the heart to 
 reach the apex also pass, at the vortex, 
 into the interior of the ventricle, where 
 they form the remainder of the inner- 
 most layer of the ventricle and the left 
 (anterior) musculus papillaris. The 
 fibres forming the inner layer of the wall of the ventricle ascend to be attached 
 to the fibrous rings around the orifices. 
 
 By dissection these superficial fibres may be removed as a thin stratum, and it 
 will then be found that the ventricles are made up of oblique fibres (Fig. 380), super- 
 
 FiG. 379. — The muscular arrangement of the apex 
 of the heart. (Poirier and Charpy.) 
 
 Fig. 380. — The muscular arrangement of the ventricle. (Poirier and Charpy.) 
 
 imposed in layers one on the top of another, and assuming gradually a less pblique 
 direction as they pass to the middle of the thickness of the ventricular wall, so that 
 
THE HEART 577 
 
 in the centre of the wall the fibres are transverse. Internal to this central transverse 
 layer the fibres become oblique again, but in the opposite direction to the external 
 ones. This division into distinct layers is, however, to a great extent artificial, as the 
 fibres pass across from one layer to another, and have therefore to be divided in 
 the dissection, and the change in the direction of the fibres is very gradual. These 
 oblique fibres commence above at the fibrous rings at the base of the heart, and, 
 descending toward the apex, they enter the septum near its lower end. In the 
 septum the fibres which form the left ventricle may be traced in three directions: 
 1. Some pass upward to be attached to the central mass of fibrous tissue. 2. 
 Others pass through the septum to become continuous with the fibres of the right 
 ventricle. 3. The remainder pass through the septum to encircle the ventricle 
 as annular fibres. Of the fibres of the right ventricle, some on entering the septum 
 pass upward to be attached to the central mass of fibrous tissue; some, entering 
 the septum from behind, pass forward to become continuous with the fibres on 
 the anterior surface of the left ventricle; and others, entering in front, pass back- 
 ward to join the fibres on the posterior wall of the left ventricle. The septum 
 therefore consists of three varieties of fibres — viz., annular fibres, special to the left 
 ventricle; ascending fibres, derived from both ventricles and ascending through 
 the septum to the central fibro-cartilage; and decussating fibres, derived from the 
 anterior wall of one ventricle and passing to the posterior wall of the other ven- 
 tricle, or from the posterior wall of the right ventricle and passing to the anterior 
 wall of the left. In addition to these fibres there are a considerable number 
 which appear to encircle both ventricles and which pass across the septum without 
 turning into it. 
 
 Vessels and Nerves. — The arteries supplying the heart are the right and left 
 coronary from the aorta. Branches from the coronary vessels supply the mus- 
 cular structure, the subendocardial, and the subepicardial tissue. There are no 
 vessels in the endocardium. The valves contain no vessels unless they contain 
 muscle, in which case minute vessels enter them. There are numerous capillary 
 networks about the muscular fibres. 
 
 The veins accompany the arteries. They are: the anterior or great, the posterior, 
 the left, and the anterior cardiac veins, the right or small, and the left or great, 
 coronary sinuses. The coronary sinus receives most of the veins of the heart and 
 empties into the right auricle. Some few small veins open directly into the right 
 and left auricles and into the ventricles. They are the venae minimse cordis. The 
 oblique vein of the left auricle is known as the oblique vein of Marshall. 
 
 The lymphatics are arranged in two networks: one in the muscle beneath the 
 endocardium, another in the muscle beneath the epicardium. The deep empties 
 into the superficial network, the anterior collecting trunks from the subepicardial 
 network pass to the tracheo-bronchial glands. The posterior collecting trunk 
 terminates in the same group of glands." 
 
 The nerves are derived from the superficial and deep cardiac plexuses, and from 
 these plexuses obtain fibres of the pneumogastric, spinal accessory, and sympa- 
 thetic. The superficial cardiac plexus lies under the arch of the aorta. The 
 deep cardiac plexus is in front of the tracheal bifurcation. The nerves from the 
 plexuses are freely distributed both on the surface and in the substance of the 
 heart, the separate filaments being furnished with small ganglia. 
 
 Surface Form. — In order to show the extent of the heart in relation to the front of the chest, 
 draw a line from the lower border of the second left costal cartilage, one inch from the sternum, 
 to the upper border of the third right costal cartilage, half an inch from the sternum. This 
 represents the base-line or upper limit of the organ. Take a point an inch and a half below 
 and three-quarters of an inch internal to the left nipple — that is, about three and a half inches 
 Id the left of the median line of the body. This represents the apex of the heart. Draw a line 
 
 1 The Lymphatics. By Poirier, Cun6o, and Delamare. Translated and edited by Cecil H. Leaf. 
 
 37 
 
578 THE BLOOD -VASCULAR SYSTEM 
 
 from this apex-point, with a slight convexity downward, to the junction of the seventh right 
 costal cartilage to the sternum. This represents the lower limit of the heart. Join the right 
 extremity of the first line — that is, the base-line — ^with the right extremity of this line — that is, 
 to the seventh right chondro-sternal joint — with a slight curve outward, so that it projects about 
 an inch and a half from the middle line of the sternum. Lastly, join the left extremity of the 
 base-line and the apex-point by a line curved slightly to the left. 
 
 The position of the various orifices is as follows — viz., the pulmonary orifice is situated in 
 the upper angle formed by the articulation of the third left costal cartilage with the sternum; 
 the aortic orifice is a little below and internal to this, behind the left border of the sternum, 
 close to the articulation of the third left costal cartilage to this bone. The left auriculo-ventric- 
 ular opening is behind the sternum, rather to the left of the median line, and opposite the fourth 
 costal cartilages. The right auriculo-ventricular opening is a little lower, opposite the fourth 
 interspace and in the middle line of the body (Fig. 366). 
 
 A portion of the area of the heart thus mapped out is uncovered by lung, and therefore 
 gives a dull note on percussion; the remainder, being overlapped by the lung, gives a more or 
 less resonant note. The former is known as the area of superficial cardiac dulness; the latter 
 as the area of deep cardiac dulness. The area of superficial cardiac dulness is included between 
 a line drawn from the centre of the sternum, on a level with the fourth costal cartilages, to the 
 apex of the heart and a line drawn from the same point down the lower third of the middle line 
 of the sternum. Below, this area merges into the dulness which corresponds to the liver. Dr. 
 McClellan states that the area of superficial cardiac dulness may be mapped out " by draw- 
 ing a line from the middle of the sternum opposite the fourth left costal cartilage to the point 
 of junction of the fiifth rib and its cartilage, and from this point horizontally back to the mid- 
 sternal line." 
 
 Surgical Anatomy. — Wounds of the heart are often immediately fatal, but not necessarily 
 so. They may be non-penetrating, when death may occur from hemorrhage, if one of the coro- 
 nary vessels has been wounded, or subsequently from pericarditis; or, on the other hand, the 
 patient may recover. Even a penetrating wound is not necessarily fatal, if the wound is a small 
 one. An attempt should be made to save the patient by means of a surgical operation. A 
 trap-door flap comprising the whole thickness of the thoracic wall should be made. The hinges 
 of the trap-door are the rib cartilages. The pericardium is exposed and opened freely, clots are 
 removed, the wound in the heart is sought for, and when discovered is sutured. In a pene- 
 trating wound the sutures include the whole thickness of the heart, except the endocardium. 
 Interrupted sutures should be used, and each one had better be tied during diastole. A number 
 of successful operations of this character have been performed. 
 
 Peculiarities in the Vascular System of the Foetus (Fig. 382). 
 
 The chief peculiarities in the heart of the foetus are the direct communication 
 between the two auricles through the foramen ovale, and the large size of the 
 Eustachian valve. There are also several minor peculiarities. Thus, the position 
 of the heart is vertical until the fourth month, when it commences to assume an 
 oblique direction. Its size is also very considerable as compared with the body, 
 the proportion at the second month being 1 to 50; at birth it is as 1 to 120; whilst 
 in the adult the average is about 1 to 160. At an early period of foetal life the 
 auricular portion of the heart is larger than the ventricular, the right auricle being 
 more capacious than the left; but toward birth the ventricular portion becomes 
 the larger. The thickness of both ventricles is at first about equal, but toward 
 birth the left becomes much the thicker of the two. 
 
 The foramen ovale (Fig. 381) is situated at the lower and back part of the septum 
 atriorum, forming a communication between the auricles. It remains as a free 
 oval opening until the middle period of foetal life. About this period a fold 
 grows up from the posterior wall of the auricle to the left of the foramen ovale, and 
 advances over the opening so as to form a sort of valve, which allows the blood 
 to pass only from the right to the left auricle, and not in the opposite direction. 
 
 The Eustachian valve (Fig. 381) is directed upward on the left side of the 
 opening of the inferior vena cava, and serves to direct the blood from this vessel 
 through the foramen ovale into the left auricle. 
 
 The peculiarities in the arterial system of the foetus are the communication 
 between the pulmonary artery and the descending aorta by means of the ductus 
 
THE HEART 
 
 579 
 
 arteriosus, and the communication between the internal iliac arteries and the 
 placenta by means of the umbilical arteries. 
 
 The Ductus Arteriosus (Fig. 382) . — The ductus arteriosus is a short tube, about 
 half an inch in length at birth, and of the diameter of a goose-quill. In the early 
 condition it forms the continuation of the pulmonary artery, and opens into the 
 descending aorta just below the origin of the left subclavian artery, and so con- 
 ducts the chief part of the blood from the right ventricle into this vessel. When 
 the branches of the pulmonary artery have become larger relatively to the ductus 
 arteriosus, the latter is chiefly connected to the left pulmonary artery; and the 
 fibrous cord (ligamentum arteriosum), which is all that remains of the ductus 
 arteriosus in later life, will be found to be attached to the root of that vessel. 
 
 The Umbilical Arteries. — The umbilical or hypogastric arteries arise from the 
 internal iliacs, in addition to the branches given off from those vessels in the 
 adult. Ascending along the sides of the bladder to its apex, they pass out of 
 the abdomen at the umbilicus and are continued along the umbilical cord to 
 the placenta, coiling round the umbilical vein. They carry to the placenta the 
 blood which has circulated in the system of the foetus. 
 
 CONUS 
 ARTERIOSUS 
 
 VALVE OF 
 FORAMEN OVALE 
 
 VALVE OF AURICULO-VENTRICULAR 
 CORONARY SINUS OPENING 
 
 Fig. 381. — The right auricle of a foetal heart (eighth month). Enlarged. (Spalteholz.) 
 
 The peculiarity in the venous system of the foetus is the communication estab- 
 lished between the placenta and the liver and portal vein through the umbilical 
 vein, and the inferior vena cava through the ductus venosus. 
 
 Foetal Circulation. — The blood destined for the nutrition of the foetus is 
 returned from the placenta to the foetus by the umbilical vein. This vein enters 
 the abdomen at the umbilicus, and passes upward along the free margin of the 
 suspensory ligament of the liver to the under surface of that organ, where it gives 
 ofT two or three branches to the left lobe, one of which is of large size, and others 
 to the lobus quadratus and lobulus Spigelii. At the transverse fissure it divides 
 into two branches : of these, the larger is joined by the portal vein and enters the 
 right lobe; the smaller branch continues outward, under the name of the ductus 
 venosus, and joins the left hepatic vein at the point of junction of that vessel with 
 the inferior vena cava. The blood, therefore, which traverses the umbilical vein 
 reaches the inferior vena cava in three different ways: the greater quantity cir- 
 culates through the liver with the portal venous blood before entering the vena 
 
580 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 cava by the hepatic veins ; some enters the Uver directly, and is also returned to 
 the inferior cava by the hepatic veins; the smaller quantity passes directly into the 
 vena cava by the junction of the ductus venosus w^ith the left hepatic vein. 
 
 Ductus arteriosus. 
 
 Internal iliac artery. 
 
 Fig. 382.— Plan of the foetal circulation. In this plan the figured arrows represent the kind of blood, as well 
 
 as the direction which it takes in the vessels. Thus, arterial blood is figured >> — --> ; venous blood, 
 
 >> >; mixed (arterial and venous) blood, >> •• — •• — >. 
 
 In the inferior cava the blood carried by the ductus venosus and hepatic veins 
 becomes mixed with that returning from the lower extremities and wall of the 
 abdomen. It enters the right auricle, and, guided by the Eustachian valve, passes 
 through the foramen ovale into the left auricle, where it becomes mixed with a 
 small quantity of blood returned from the lungs by the pulmonary veins. From 
 the left auricle it passes into the left ventricle, and from the left ventricle into 
 
THE HEART 581 
 
 the aorta, by means of which it is distributed almost entirely to the head and 
 upper extremities, a small quantity being probably carried into the descending 
 aorta. From the head and upper extremities the blood is returned by the tribu- 
 taries of the superior vena cava to the right auricle, where it becomes mixed 
 with a small portion of the blood from the inferior cava. From the right auricle 
 it descends over the Eustachian valve into the right ventricle, and from the right 
 ventricle passes into the pulmonary artery. The lungs of the foetus being inactive, 
 only a small quantity of the blood of the pulmonary artery is distributed to them 
 by the right and left pulmonary arteries, and is returned by the pulmonary veins 
 to the left auricle; the greater part passes through the ductus arteriosus into the 
 commencement of the descending aorta, where it becomes mixed with a small 
 quantity of blood transmitted by the left ventricle into the aorta. Through this 
 vessel it descends to supply the lower extremities and viscera of the abdomen 
 and pelvis, the chief portion being, however, conveyed by the umbilical arteries 
 to the placenta. 
 
 From the preceding account of the circulation of the blood in the foetus it will 
 be seen— 
 
 1. That the placenta serves the purposes of nutrition and excretion, receiving 
 the impure blood from the foetus, and returning it charged with additional nutri- 
 tive material. 
 
 2. That nearly the whole of the blood of the umbilical vein traverses the liver 
 before entering the inferior cava; hence the large size of this organ, especially at 
 an early period of foetal life. 
 
 3. That the right auricle is the point of meeting of a double current, the blood 
 in the inferior cava being guided by the Eustachian valve into the left auricle, 
 whilst that in the superior cava descends into the right ventricle. At an early 
 period of the foetal life it is highly probable that the two streams are quite dis- 
 tinct, for the inferior cava opens almost directly into the left auricle, and the 
 Eustachian valve would exclude the current along the vein from entering the 
 right ventricle. At a later period, as the separation between the two auricles 
 becomes more distinct, it seems probable that some mixture of the two streams 
 must take place. 
 
 4. The pure blood carried from the placenta to the foetus by the umbilical vein, 
 mixed with the blood from the portal vein and inferior cava, passes almost directly 
 to the arch of the aorta, and is distributed by the branches of that vessel to the 
 head and upper extremities; hence the large size and perfect development of 
 those parts at birth. 
 
 5. The blood contained in the descending aorta, chiefly derived from that 
 which has already circulated through the head and upper limbs, together with a 
 small quantity from the left ventricle, is distributed to the lower extremities; 
 hence the small size and imperfect development of these parts at birth. 
 
 Changes in the Vascular System at Birth. 
 
 At birth, when respiration is established, an increased amount of blood from 
 the pulmonary artery passes through the lungs, which now perform their office 
 as respiratory organs, and at the same time the placental circulation is cut off. 
 Almost immediately after birth the foramen ovale is closed by the valvular edge 
 being pressed against the annulus ovalis, the pressure being due to respiration, 
 which increases the pressure in the left auricle. The structures fuse, and closure 
 is complete by about the tenth day after birth. The valvular fold above men- 
 tioned becomes adherent to the margins of the foramen for the greater part of its 
 circumference, but above a slit-like opening is left between the two auricles which 
 sometimes remains persistent. 
 
582 THE BLOOD -VASCULAR SYSTEM 
 
 The ductus arteriosus begins to contract immediately after respiration is estab- 
 lished, becomes completely closed from the fourth to the tenth day, and ultimately 
 degenerates into an impervious cord which serves to connect the left pulmonary 
 artery to the descending aorta. When respiration begins, the caval opening of 
 th3 diaphragm being fixed and the balance of thi muscle rising and falling, the 
 ductus arteriosus is compressed by the muscular structures which pass from the 
 diaphragm to the pericardium, is narrowed, and is finally obhterated (Forbes). 
 
 Of the umbilical or hypogastric arteries, the portion continued on to the bladder 
 from the trunk of the corresponding internal iliac remains pervious as the superior 
 vesical artery, and the part extending from the side of the bladder to the umbilicus 
 becomes obliterated between the second and fifth days after birth, and projects 
 as a fibrous cord toward the abdominal cavity, carrying on it a fold of peritoneum 
 and separating two of the fossse of the peritoneum spoken of in the section on the 
 surgical anatomy of direct inguinal hernia. 
 
 The umbilical vein and the ductus venosus become completely obliterated 
 between the second and fifth days after birth, and ultimately dwindle to fibrous 
 cords, the former becoming the round ligament of the liver, the latter the fibrous 
 cord, which in the adult may be traced along the fissure of the ductus venosus. 
 
THE ARTERIES. 
 
 The Arteries are cylindrical tubular vessels which serve to convey blood from 
 both ventricles of the heart to every part of the body. These vessels were named 
 arteries {drjp, air; zr^pelu, to contain) from the belief entertained by the ancients 
 that they contained air. To Galen is due the honor of refuting this opinion; he 
 showed that these vessels, though for the most part empty after death, contain 
 blood in the living body. 
 
 The distribution of the systemic arteries is like a highly ramified tree, the 
 common trunk of which, formed by the aorta, commences at the left ventricle of 
 the heart, the smallest ramifications corresponding to the circumference of the 
 body and the contained organs. The arteries are found in nearly every part of 
 the body, with the exception of the hairs, nails, epidermis, cartilages, and cornea; 
 and the larger trunks usually occupy the most protected situations, running, in 
 a limb, along the flexor side, where they are less exposed to injury. 
 
 There is considerable variation in the mode of division of the arteries: occa- 
 sionally a short trunk subdivides into several branches at the same point, as 
 we observe in the coeliac and thyroid 
 
 axes; or the vessel may give off several a ^ 
 
 branches in succession, and still con- 
 tinue as the main trunk, as is seen in 
 the arteries of the limbs; but the usual 
 division is dichotomous; as, for instance, 
 the aorta dividing into the two common 
 iliacs, and the common carotid into the 
 external and internal carotids. 
 
 The branches of arteries arise at very 
 variable angles: some, as the superior 
 intercostal arteries from the aorta, arise 
 at an obtuse angle: others, as the lumbar 
 arteries, at a right angle; or, as the 
 spermatic, at an acute angle. An artery 
 from below the point at which a branch 
 is given off is smaller in size than be- 
 fore. It retains a uniform diameter 
 until a second branch is derived from 
 it. A branch of an artery is smaller 
 than the trunk from which it arises; but 
 if an artery divides into two branches, 
 the combined area of the two vessels is, in nearly every instance, somewhat 
 greater than that of the trunk; and the combined area of all the arterial branches 
 greatly exceeds the area of the aorta; so that the arteries collectively may be 
 regarded as a cone, the apex of which corresponds to the aorta, the base to the 
 capillary system. 
 
 The arteries, in their distribution, communicate with one another, forming 
 what is called an anastomosis {d.vd, between; azoixa, mouth) or inosculation (Fig, 
 383) ; and this communication is very free between the larger as well as between the 
 
 (583) 
 
 Fig. 383. — Diagram showing the anastomosis of 
 arteries. (Poirier and Charpy.) 
 
584 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 smaller branches. An anastomosis between trunks of equal size is found where 
 great activity of the circulation is requisite, as at the base of the brain ; here the 
 two vertebral arteries unite to form the basilar, and the two internal carotid 
 arteries are connected by a short communicating trunk; it is also found in the 
 abdomen, the intestinal arteries having very ample anastomoses between their 
 larger branches. In the limbs the anastomoses are most numerous and of 
 largest size around the joints, the branches of an artery above inosculating 
 with branches from the vessels below; these anastomoses are of considerable 
 interest to the surgeon, as it is by their enlargement that a collateral circula- 
 tion is established after the application of a ligature to an artery for the cure 
 of aneurism. The smaller branches of arteries anastomose more frequently 
 than the larger, and between the smallest twigs these inosculations become so 
 
 numerous as to constitute a close network 
 that pervades nearly every tissue of the body. 
 A terminal artery is one which forms no 
 anastomoses. Such vessels are found in the 
 brain, spleen, kidneys, lungs, and mesen- 
 tery. 
 
 Throughout the body generally the larger 
 arterial branches pursue a perfectly straight 
 course, but in certain situations they are tor- 
 tuous; thus the facial arteries in their course 
 over the face, and the arteries of the lips, 
 are extremely tortuous in their course, to 
 accommodate themselves to the movements 
 of the parts. The uterine arteries are also 
 tortuous, to accommodate themselves to the 
 increase of size which the organ undergoes 
 during pregnancy. Again, the internal 
 carotid and vertebral arteries, previous to 
 their entering the cavity of the skull, de- 
 scribe a series of curves, which are evidently 
 intended to diminish the velocity of the cur- 
 rent of blood by increasing the extent of 
 surface over which it moves and adding to 
 the resistance which is produced by friction. 
 The arteries are dense in structure, of 
 considerable strength, highly elastic, and, 
 when divided, they preserve, although empty, 
 their cylindrical form. 
 
 Histology of the Capillaries and Ar- 
 teries. The Capillaries (Fig. 386). — The 
 capillaries are very small endothelial tubes 
 which connect the venous system with the 
 arterial system. In diameter they vary from -gVro ^^ 2"oVo ^^ ^^ inch, in length 
 from yV to ^V of an inch. The nucleated endothelial cells which constitute the 
 wall of a capillary are flat, irregular in outline, and are united by a cement 
 material. Small openings (stomata) are frequently noted between these cells, 
 but they are probably artifacts and do not exist during life. 
 
 The capillaries anastomose and form vast networks. When an artery is about 
 to become a capillary the muscular coat disappears. The endothelial coat which 
 constitutes the capillaries extends as a system of endothelial tubes throughout the 
 entire blood-vascular system. The heart is a great muscular thickening around 
 a portion of the system of endothelial tubes. An artery consists of an endothelial 
 
 Fig. 384. — Tran.sverse section through a small 
 artery and vein of the mucous membrane of the 
 epiglottis of a child. Magnified about 350 diame- 
 ters. A, artery, showing the nucleated endothe- 
 lium e, which lines it: the vessel being con- 
 tracted, the endothelial cells appear very thick. 
 Underneath the endothelium is the wavy elastic 
 intima. The chief part of the wall of the vessel 
 is occupied by the circular muscle-coat ni; the 
 staff-shaped nuclei of the muscle-cells are well 
 seen. Outside this is a, part of the adventitia. 
 This is composed of bundles of connective-tissue 
 fibres, shown in section, with the nuclei of the 
 connective-tissue corpuscles. The adventitia 
 gradually merges into the surrounding connective- 
 tissue. V, vein showing a thin endothelial mem- 
 bra,ne e, raised accidentally from the intima, 
 which on account of its delicacy is seen as a mere 
 line on the media m. This latter is composed of 
 a few circular unstriped muscle-cells ; a, the ad- 
 ventitia, similar in structure to that of an artery. 
 (Klein and Noble Smith.) 
 
THE ARTERIES 
 
 585 
 
 tube covered by certain accessory coats. The wall of an artery diminishes 
 greatly in thickness (Fig. 387) and is found to be composed of endothelial cells 
 anfl scattered unstriated muscle-fibres, covered merely by thin connective tissue 
 or elastic-tissue sheath (adventitia capillaris). Such a structure is known as an 
 arteriole or a precapillary artery. By the loss of its thin sheath of connective or 
 elastic tissue it becomes a capillary. A capillary takes on a thin sheath and 
 becomes a venule or precapillary vein. Nerves do not terminate in capillaries, 
 but networks of nerve-filaments often encompass these small vessels. 
 
 An artery consists of an internal coat or tunica intima, a middle coat or tunica 
 media, and an external coat or tunica adventitia (Figs. 384 and 385). 
 
 The Inner Coat (tunica intima) consists of endothelial cells and yellow elastic 
 tissue. In some cases the elastic fibres are arranged longitudinally, but, as a rule, 
 they form a distinct fenestrated membrane known as the fenestrated membrane of 
 
 Endothelial and sub- 
 etidothelial layer of 
 ■"" inner coat. 
 "Elastic layer. 
 
 _ Innermost layers of 
 middle coat. 
 
 Outermost layers of 
 middle coat. 
 
 _ Innermost part 
 outer coat. 
 
 ^X:^-'' O ^-. -'- ^f - i 
 
 
 ^ I Outer part of outer 
 
 coat. 
 
 Fig. 385. — Section of a medium-sized artery. (After Griinstein.) 
 
 Henle, or the internal elastic coat. In medium-sized vessels the elastic layer of the 
 intima is separated from the endothelial layer by a layer of connective tissue. 
 In the large arteries the interposed layer of connective tissue is thicker and con- 
 tains elastic fibres. 
 
 The Middle Coat {tunica media) consists of muscle, elastic tissue, and white 
 fibrous tissue, and it is often called the elastomuscular coat. The arterioles con- 
 tain scattered unstriated muscle fibres. In the small arteries they constitute a 
 thin but definite coat. In larger arteries the muscular coat is much thicker. The 
 muscle is unstriated and the fibres are arranged circularly, and in the larger 
 vessels form layers which are separated by elastic fibres. Here and there longi- 
 tudinally-disposed muscle-fibres exist. The larger the artery the greater is the 
 amount of elastic tissue exi.sting in the middle coat. In the aorta and in some 
 of the very large arteries the amount of elastic tissue exceeds the amount of 
 
586 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 muscular tissue. "In the first part of the aorta, in the pulmonary artery and in 
 the arteries of the retina, the muscular fibres are entirely replaced by elastic 
 tissue."^ The arteries within the skull have no elastic tissue in the media, 
 although they have some in the adventitia. 
 
 The External Coat {tunica adventitia) is called the fibrous coat. It contains 
 fibrous connective tissue, elastic tissues, and in some arteries fibres of unstriated 
 muscle arranged longitudinally. The circular elastic membrane which sepa- 
 rates the outer coat from the middle coat is known as the external elastic mem- 
 brane. 
 
 Blood-vessels of the Blood-vessel Wall. — Many small blood-vessels course in the 
 external and middle coats of arteries of large and of moderate size. They are 
 mostly in the adventitia. They may arise from the vessel to which they are dis- 
 
 FiG. 386.— Capillaries from the 
 mesentery of a guinea-pig after treat- 
 ment with solution of nitrate of silver. 
 a, cells; b, their nuclei. 
 
 Fig. 387. — Finest vessels on the arterial aide. From the human 
 brain. Magnified 300 times. 1, small artery; 2, transition vessel; 
 3, coarser capillaries; 4, finer capillaries; o, structureless mem- 
 brane still with some nuclei, representative of the tunica adven- 
 titia; h, nuclei of the muscular fibre-cells; c, nuclei within the 
 small arterj;, perhaps appertaining to an endothelium; d, nuclei 
 in the transition vessels. 
 
 tributed or take origin from an adjacent vessel. These small arteries are called 
 the vasa vasorum. The blood is returned from the walls of the vessels by small 
 veins. 
 
 Lymphatics. — Distinct lymphatic vessels may exist in the adventitia, but are 
 not found in either of the other coats. Lymph-capillaries often surround small 
 blood-vessels or a small blood-vessel may lie in a perivascular lymph-space. 
 
 Nerves. — Arteries are supplied with nerves, medullated and non-medullated. 
 A network of nerve-fibres may surround a vessel and usually capillaries are so 
 surrounded. In the arteries a network of nerves exists in the media. These nerves 
 supply the muscle-fibres and are called vasomotor nerves. 
 
 The Arterial Sheath {vagina vasis) surrounds the artery. It is composed of con- 
 nective tissue and is attached to the vessel at numerous points by fibrous tissue. 
 
 * D. J. Cunningham. Text-book of Anatomy. 
 
THE AORTA 587 
 
 PULMONARY ARTERY (A. PULMONALIS) (Fig. 389, 391). 
 
 In the description of the arteries we shall first consider the efferent trunk of 
 the pulmonic circulation, the pulmonary artery, and then the efferent trunk of the 
 systemic circulation, the aorta and its branches. 
 
 The pulmonary artery conveys the venous blood from the right side of the heart 
 to the lungs. It is a short, wide vessel, about 2 inches in length and li inches 
 (30 mm.) in diameter, arising from the left side of the base (conus arteriosus) 
 of the right ventricle, in front of the aorta. It extends obliquely upward and 
 backward, passing at first in front of and then to the left of the ascending 
 aorta, as far as the under surface of the arch, where it divides, about on a level 
 with the intervertebral substance between the fifth and sixth dorsal vertebrae, 
 into two branches of nearly equal size, the right and left pulmonary arteries. 
 
 The Right Pulmonary Artery (ramus dexter a. pulmonalis), longer and 
 larger than the left, runs horizontally outward to the root of the right lung, where 
 it divides into two branches, of which the lower and larger supplies the middle 
 and lower lobes; the upper and smaller is distributed to the upper lobe. It has 
 in front of it the ascending aorta, the superior vena cava, and the right phrenic 
 nerve. It has behind it the right bronchus. Above it is the transverse portion of 
 the arch of the aorta. Below it is the right auricle. 
 
 The Left Pulmonary Artery (ramus sinister a. pulmonalis), shorter and 
 somewhat smaller than the right, passes horizontally to the root of the left lung, 
 where it divides into two branches for the two lobes. In front of it and below it 
 are the pulmonary veins of the left side. Behind are the descending aorta and the 
 left bronchus. Above it are the arch of the aorta, the left recurrent laryngeal 
 nerve, and the ductus arteriosus. The left bronchus in a portion of its course lies 
 below as well as behind. 
 
 Relations. — The whole of the vessel is contained, together with the ascending 
 aorta, in the pericardium. It is enclosed with the aorta in a single tube of the 
 serous pericardium, which is continued upward upon them from the base of the 
 heart and connects them together. The fibrous layer of the pericardium becomes 
 gradually lost upon the external coats of its two branches. In front, the pulmonary 
 artery is separated from the anterior extrerpity of the second left intercostal space 
 by the pleura and left lung, in addition to the pericardium; it rests at first upon 
 the ascending aorta, and higher up lies in front of the left auricle on a plane 
 posterior to the ascending aorta. On each side of its origin is the appendix of 
 the corresponding auricle and a coronary artery, the left coronary artery passing, 
 in the first part of its course, behind the vessel. 
 
 The root of the left pulmonary artery is connected to the under surface of the 
 arch of the aorta by a short fibrous cord, the ligamentum arteriosum; this is the 
 remains of a vessel peculiar to foetal life, the ductus arteriosus. 
 
 The terminal branches of the pulmonary artery will be described with the 
 anatomy of the lung. 
 
 THE AORTA (Figs. 388, 389, 390, 391). 
 
 The aorta or arteria magna (doprij) is the main trunk of a series of vessels which 
 convey the oxygenated blood to the tissues of the body for their nutrition. This 
 vessel commences at the upper part of the left ventricle, where it is aV)out one and 
 one-eighth inches in diameter, and, after ascending for a short distance, arches 
 backward and to the left side, over the root of the left lung, then descends within 
 the thorax on the left side of the vertebral column, passes through the aortic open- 
 ing in the Diaphragm, and, entering the abdominal cavity, terminates, consider- 
 
588 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 ably diminished in size (about seven-tenths of an inch in diameter), opposite the 
 lower border of the fourth lumbar vertebra, where it divides into the right and left 
 common iliac arteries. Hence it is divided into the ascending aorta, the arch of 
 the aorta, and the descending aorta, which last is again divided into the thoracic aorta 
 and the abdominal aorta, from the position of these parts. 
 
 THE ASCENDING AORTA (AORTA ASGENDENS). 
 
 The ascending aorta is about two inches in length. It commences at the 
 upper part of the left ventricle, on a level with the lower border of the third 
 costal cartilage, behind the left half of the sternum ; it passes obliquely upward, 
 forward, and to the right, in the direction of the heart's axis, as high as the 
 
 PNCUMOGASTRIC 
 NERVE 
 
 CARDIAC NERVE 
 SUPERIOR INTER- 
 COSTAL VEIN 
 CARDIAC NERVE 
 ARTERIAL 
 LIGAMENTS 
 
 VENA AZYGOS: 
 
 MINOR 
 
 SYMPATHETIC 
 GANGLION 
 
 SYMPATHETIC 
 NERVE 
 
 Fig. 388. — Arch of the aorta and its relations. (Poirier and Charpy.) 
 
 upper border of the second right costal cartilage, describing a slight curve in 
 its course, and being situated, when distended, about a quarter of an inch behind 
 the posterior surface of the sternum. A little above its commencement it is some- 
 what enlarged (bulhus aortoe), and presents three small dilatations, one of which is 
 anterior, two of which are posterior, which are called the sinuses of Valsalva {sinu» 
 aortce). Opposite to the sinuses are attached the three semilunar valves (Fig. 376), 
 
THE ASCENDING AORTA 
 
 589 
 
 which serve the purpose of preventing any regurgitation of blood into the cavity 
 of the ventricle. These valves are placed one in front and two behind. At the 
 union of the ascending with the transverse part of the aorta the calibre of the vessel 
 is increased, owing to a bulging outward of its right wall. This dilatation is termed 
 the great sinus of the aorta. A section of the aorta opposite this part has a some- 
 what oval figure; but below the attachment of the valves it is circular. This por- 
 tion of the aorta is contained in the cavity of the pericardium, and, together with 
 the pulmonary artery, is invested in a tube of serous membrane, continued on to 
 them from the surface of the heart. 
 
 Eight vagus 
 Recurrent laryngeal. 
 
 Left vagus. 
 I — Left phrenic. 
 Thoracic duct. 
 
 Fig. 389. — The arch of the aorta and its branches. 
 
 Relations. — The ascending aorta is covered at its commencement by the trunk 
 of the pulmonary artery and the right auricular appendix, and, higher up, is 
 separated from the sternum by the pericardium, the right pleura, and anterior 
 margin of the right lung, some loose areolar tissue, and the remains of the thymus 
 gland ; behind, it rests upon the right pulmonary artery, left auricle, and the right 
 bronchus. On the right side it is in relation with the superior vena cava and right 
 auricle; on the left side, with the pulmonary artery. 
 
590 THE BLOOD -VASCULAR SYSTEM 
 
 Plan of the Relations of the Ascending Aorta. 
 
 In front. 
 Pulmonary artery. 
 Right auricular appendix. 
 Pericardium. 
 Right pleura and lung. 
 Remains of the thymus gland. 
 
 Right side. 
 
 / \ 
 
 Left side. 
 
 Superior vena cava. 
 
 Ascending 
 
 Pulmonary artery. 
 
 Right auricle. 
 
 Aorta. 
 
 \ / 
 
 
 Behind. 
 Right pulmonary artery. 
 Left auricle. 
 Right bronchus. 
 
 Branches — The only branches of the ascending aorta are the coronary arteries. 
 They supply the heart, and are two in number, right and left, arising near the com- 
 mencement of the aorta, immediately above the free margin of the semilunar 
 valves. 
 
 The Coronary Arteries (Fig. 389). 
 
 The Right Coronary Artery (a. coronaria [cordis] dextra), about the size of a 
 crow's quill, arises from the anterior sinus of Valsalva. It passes forward between 
 the pulmonary artery and the right auricular appendix, then runs obliquely to the 
 right side, in the groove between the right auricle and ventricle, and, curving 
 around the right border of the heart, runs to the left along its posterior surface as 
 far as the posterior interventricular groove, where it divides into two branches, one 
 of which, the transverse, continues onward in the groove between the left auricle 
 and ventricle, and anastomoses with the left coronary; the other, the descending 
 {ramus descendens posterior a. coronarice [cordis] dextroe), courses along the posterior 
 interventricular furrow, supplying branches to both ventricles and to the septum, 
 and anastomosing at the apex of the heart with the descending branches of the left 
 coronary. This vessel sends a large branch, the marginal, along the thin margin 
 of the right ventricle to the apex, which in its course gives off numerous small 
 branches to the anterior and posterior surfaces of the ventricle. It also gives off 
 a branch, the infundibular, which ramifies over the front part of the conus arte- 
 riosus of the right ventricle. 
 
 The Left Coronary Artery (a. coronaria [cordis] sinistra), larger than the 
 former, arises from the left posterior sinus of Valsalva; it passes forward between 
 the pulmonary artery and the left auricular appendix, and divides into two 
 branches. Of these, one, the transverse, passes transversely outward in the left 
 auriculo-ventricular groove, and winds around the left border of the heart to its 
 posterior surface, where it anastomoses with the transverse branch of the right 
 coronary ; the other, the descending (ramus descendens anterior a. coronarioe [cordis] 
 sinistroe), passes along the anterior interventricular groove to the apex of the heart, 
 where it anastomoses with the descending branches of the right coronary. The left 
 coronary supplies the left auricle and its appendix, gives branches to both ventri- 
 cles, and numerous small branches to the pulmonary artery and commencement 
 of the aorta.^ 
 
 * According to Dr. Samuel West, there is a very free and complete anastomosis between the two coronary 
 arteries (Lancet, June 2, 1883, p. 945). This, however, is not the view generally held by anatomists, for, with 
 the exception of the anastomosis mentioned above in the auriculo-ventricular and interventricular grooves, it 
 is believed that the two arteries only communicate by very small vessels in the substance of the heart. — Ed. of 
 15th English edition. 
 
THE ABCH OF THE AORTA 591 
 
 Peculiarities. — These vessels occasionally arise by a common trunk, or their number may 
 be increased to three, the additional branch being of small size. More rarely there are two 
 additional branches. 
 
 THE ARCH OF THE AORTA. 
 
 The arch, or transverse aorta (arcus aort(B), commences at the upper border of 
 the second chondro-sternal articulation of the right side, and passes at first upward 
 and backward and from right to left, and then from before backward, to the left 
 side of the lower border of the fourth dorsal vertebra behind. Its upper border is 
 usually about an inch below the upper margin of the sternum. 
 
 Between the origin of the left subclavian artery and the attachment of the 
 ductus arteriosus the lumen of the foetal aorta is considerably narrowed, forming 
 what is termed the aortic isthmus (isthmus aorte), while immediately beyond the 
 ductus arteriosus the vessel presents a fusiform dilatation which His has named 
 the aortic spindle (aortenspindel) — the point of junction of the two parts being 
 marked in the concavity of the arch by an indentation or angle. These con- 
 ditions persist, to some extent, in the adult, where His found that the average 
 diameter of the spindle exceeded that of the isthmus by 3 mm. (about one-eighth 
 of an inch). 
 
 Relations. — Its anterior surface is covered by the pleurae and lungs (much 
 more by the left lung than by the right) and the remains of the thymus gland, and 
 crossed toward the left side by the left pneumogastric and phrenic nerves and 
 superficial cardiac branches of the left sympathetic and vagus, and by the left 
 superior intercostal vein. Its posterior surface lies on the trachea, just above its 
 bifurcation, on the great, or deep, cardiac plexus, the oesophagus, thoracic duct, 
 and left recurrent laryngeal nerve. Its upper border is in relation with the left 
 innominate vein, and from its upper part are given off the innominate, left com- 
 mon carotid and left subclavian arteries. Its lower border is in relation with the 
 bifurcation of the pulmonary artery, the remains of the ductus arteriosus, which 
 is connected with the left division of that vessel, and the superficial cardiac plexus; 
 the left recurrent laryngeal nerve winds round it from before backward, whilst 
 the left bronchus passes below it. 
 
 Plan of the Relations of the Arch of the Aorta. 
 
 Above. 
 
 Left innominate vein. 
 Innominate artery. 
 Left carotid. 
 Left subclavian. 
 In Front. Behind. 
 
 Pleurae and lungs. /"^ "^\ Trachea. 
 
 Remains of thymus gland. / \ Deep cardiac plexus. 
 
 Left pneumogastric nerve. ( Arch of j Oesophagus. 
 
 Left phrenic nerve. I '*^°'"'*- / Thoracic duct. 
 
 Superficial cardiac nerves. \ / Left recurrent nerve. 
 
 Left superior intercostal vein. ^- ^ 
 
 Below. 
 Bifurcation of pulmonary artery. 
 Remains of ductus arteriosus. 
 Superficial cardiac plexus. 
 Left recurrent nerve. 
 Left bronchus. 
 
 Peculiarities. — The height to which the aorta rises in the chest is usually about an inch below 
 the upper border of the sternum ; but it may ascend nearly to the top of that bone. Occasionally 
 it is found an inch and a half, more rarely two or even three inches, below this point. 
 
592 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 In Direction. — Sometimes in man, as is normal in birds, the aorta arches over the root of 
 the right instead of the left lung, and passes down on the right side of the spine. In such cases 
 all of the viscera of the thoracic and abdominal cavities are transposed. Less frequently, the 
 aorta, after arching over the root of the right lung, is directed to its usual position on the left 
 side of the spine, this peculiarity not being accompanied by any transposition of the viscera. 
 
 In Conformation. — The aorta occasionally divides, as in some quadrupeds, into an ascend- 
 ing and descending trunk, the former of which is directed vertically upward, and subdivides 
 into three branches, to supply the head and upper extremities. Sometimes the aorta subdivides 
 soon after its origin into two branches, which soon reunite. In one of these cases the oesophagus 
 and trachea were found to pass through the interval left by the division of the aorta; this is 
 the normal condition of the vessel in the reptilia. 
 
 Surgical Anatomy. — Of all the vessels of the arterial system, the aorta, and more especially 
 its arch, is most frequently the seat of disease; hence it is important to consider some of the 
 consequences that may ensue from aneurism of this part. 
 
 It will be remembered that the ascending aorta is continued in the pericardium, just behind 
 the sternum, being crossed at its commencement by the pulmonary artery and right auricular 
 appendix, and having the right pulmonary artery behind, the vena cava on the right side, and 
 the pulmonary artery and left auricle on the left side. 
 
 Right pulmonary 
 vein. 
 
 Right pulmonary 
 vein. 
 
 Vena asygos 
 major. 
 
 Left subclavian 
 artery. 
 
 Left common 
 carotid artery. 
 
 -Left innomi- 
 nate vein. 
 
 Inferior thyroid 
 vein. 
 
 Right innomi- 
 nate vein. 
 
 Right subclavian artery, 
 
 Right common carotid artery. 
 
 Fig. 391. 
 
 -Relation of great vessels at base of heart, seen from above. (From a preparation in the Museum 
 of the Royal College of Surgeons of England. ) 
 
 Aneurism of the ascending aorta, in the situation of the sinuses of Valsalva, in the great major- 
 ity of cases, affects the anterior sinus; this is mainly owing to the fact that the regurgitation 
 of blood upon the sinuses takes place chiefly on the anterior aspect of the vessel. As the aneuris- 
 mal sac enlarges it may compress any or all of the structures in immediate proximity to it, 
 but chiefly projects toward the right anterior side, and, consequently, interferes mainly with 
 those structures that have a corresponding relation with the vessel. In the majority of cases it 
 bursts into the cavity of the pericardium, the patient suddenly drops dead, and, upon a post- 
 mortem examination, the pericardial sac is found full of blood; or it may compre.ss the right 
 auricle, or the pulmonary artery and adjoining part of the right ventricle, and open into one or 
 the other of these parts, or may press upon the superior vena cava. 
 
 Aneurism of the ascending aorta, originating above the sinuses, most frequently implicates 
 the right anterior wall of the vessel, where, as has been explained, there exists a normal dilata- 
 tion, the great sinus of the aorta; this is probably mainly owing to the blood being impelled 
 against this part. The direction of the aneurism is also chiefly toward the right of the median 
 line. It attains a large size and projects forward, it may absorb the sternum and the cartilages 
 of the ribs, usually on the right side, and appear as a pulsating tumor on the front of the chest, 
 just below the manubrium; or it may burst into the pericardium, or may compress or open into 
 the right lung, the trachea, bronchi, or oesophagus. 
 
THE INNOMINATE ARTERY 593 
 
 Regarding the transverse aorta, the student is reminded that the vessel lies on the trachea, 
 the oesophagus, and thoracic duct; that the recurrent laryngeal nerve winds around it; and that 
 from its upper part are given off three large trunks, which supply the head, neck, and upper 
 extremities. An aneurismal tumor, taking origin from the posterior part of the vessel, its most 
 usual site, may press upon the trachea, impede the breathing, or produce cough, haemoptysis, 
 or stridulous breathing, or it may ultimately burst into that tube, producing fatal haemorrhage. 
 Again, its pressure on the laryngeal nerves may give rise to symptoms which so accurately 
 resemble those of laryngitis that the operation of tracheotomy has in some cases been resorted 
 to, from the supposition that disease existed in the larynx; or it may press upon the thoracic 
 duct and destroy life by inanition; or it may involve the cesophagus, producing dysphagia; or 
 may burst into the oesophagus, when fatal hemorrhage will occur. Again, the innominate 
 artery, or the subclavian, or left carotid, may be so obstructed by clots as to produce a weakness, 
 or even a disappearance, of the pulse in one or the other wrist or in the left temporal artery; or 
 the tumor may present itself at or above the manubrium, generally either in the median line 
 or to the right of the sternum, and may simulate an aneurism of one of the arteries of the neck. 
 
 Branches (Figs. 389 and 390). — The branches given off from the arch of the 
 aorta are three in number: the innominate, the left common carotid, and the left 
 subclavian arteries. 
 
 Peculiarities. Position of the Branches. — The branches, instead of arising from the high- 
 est part of the arch (their usual position), may be moved more to the right, arising from the 
 commencement of the transverse or upper part of the ascending portion; or the distance from 
 one another at their origin may be increased or diminished, the most frequent change in this 
 respect being the approximation of the left carotid toward the innominate artery. 
 
 The Number of the primary branches may be reduced to a single vessel, or more commonly 
 two: the left carotid arising from the innominate artery, or (more rarely) the carotid and sub- 
 clavian arteries of the left side arising from the innominate artery. But the number may be 
 increased to four, from the right carotid and subclavian arteries arising directly from the aorta, 
 the innominate being absent. In most of these latter cases the right subclavian has been found 
 to arise from the left end of the arch; in other cases it was the second or third branch given off 
 instead of the first. Another common form in which there are four primary branches is that 
 in which the left vertebral artery arises from the arch of the aorta between the left carotid and 
 subclavian arteries. Lastly, the number of trunks from the arch may be increased to five or 
 six; in these instances, the external and internal carotids arise separately from the arch, the 
 common carotid being absent on one or both sides. In some cases, where six branches have 
 been found, it has been due to a separate origin of the vertebral on both sides. 
 
 Number as Usual, Arrangement Different. — When the aorta arches over to the right 
 side, the three branches have an arrangement the reverse of what is usual, the innominate sup- 
 plying the left side, and the carotid and subclavian (which arise separately) the right side. In 
 other cases, where the aorta takes its usual course, the two carotids may be joined in a common 
 trunk, and the subclavians arise separately from the arch, the right subclavian generally arising 
 from the left end of the arch.' 
 
 In some instances other arteries are found to arise from the arch of the aorta. Of these the 
 most common are the bronchial, one or both, and the thyroidea ima; but the internal mammary 
 and the inferior thyroid have been seen to arise from this vessel. 
 
 The Innominate Artery (A. Anonyma) (Figs. 389, 390, 391). 
 
 The innominate or brachio-cephalic artery is the largest branch given off 
 from the arch of the aorta. It arises, on a level with the upper border of 
 the second right costal cartilage, from the commencement of the arch of the 
 aorta in front of the left carotid, and, ascending obliquely to the upper border of 
 the right sterno-clavicular articulation, divides into the right common carotid and 
 right subclavian arteries. This vessel varies from an inch and a half to two inches 
 in length. 
 
 Relations. — In front, it is separated from the first piece of the sternum by the 
 Sterno-hyoid and Sterno-thyroid muscles, the remains of the thymus gland, the 
 left innominate and right inferior thyroid veins which cross its root, and some- 
 times the inferior cervical cardiac branch of the right pneumogastric. Behind, it 
 
 ' The anomalies of the aorta and its branches are minutely described by Krause in Henle's Anatomy (Bruns- 
 wick, 1868), vol. iii. p. 203 et seq.— Ed. of 15th English edition 
 
 38 -^ 
 
594 THE BLOOD -VASCULAR SYSTEM 
 
 lies upon the trachea, which it crosses obliquely, and continuing upward it lies 
 in the right pleura. On the right side is the right innominate vein, right pneumo- 
 gastric nerve, and the pleura; and on the le]t side, the remains of the thymus gland, 
 the origin of the left carotid artery, the left inferior thyroid vein, and the trachea. 
 
 Branches.— The innominate usually gives off no branches, but occasionally a 
 small branch, the thjnroidea ima, is given off from this vessel. It also sometimes 
 gives off a thymic or bronchial branch. 
 
 The Thjrroidea Ima (a. thyroidea ima), which is occasionally present, ascends in 
 front of the trachea to the lower part of the thyroid body, which it supplies. It 
 varies greatly in size, and appears to compensate for the deficiency or absence of 
 one of the other thyroid vessels. It occasionally is found to arise from the right 
 common carotid or from the aorta, the subclavian, or internal mammary vessels. 
 
 Plan of the Relations of the Innominate Artery. 
 
 In front. 
 Sternum. 
 
 Sterno-hyoid and Sterno-thyroid muscles. 
 Remains of the thymus gland. 
 Left innominate and right inferior thyroid veins. 
 Inferior cervical cardiac branch from right pneumogastric nerve. 
 
 Right side. / \ Left side. 
 
 Right innominate vein. / innominate | Remains of thymus. 
 
 Right pneumogastric nerve. I Artery. ) Left carotid. 
 
 Pleura. \ / Left inferior thyroid vein. 
 
 ^-_^^^ Trachea. 
 
 Behind. 
 
 Trachea. 
 Right pleura. 
 
 Peculiarities in Point of Division. — When the bifurcation of the innominate artery varies 
 from the point above mentioned it sometimes ascends a considerable distance above the sternal 
 end of the clavicle; less frequently it divides below it. In the former class of cases its length 
 may exceed two inches, and in the latter be reduced to an inch or less. These are points of con- 
 siderable interest for the surgeon to remember in connection with the operation of tying this 
 vessel. 
 
 Position. — When the aorta arches over to the right side, the innominate is directed to the 
 left side of the neck instead of the right. 
 
 Collateral Circulation. — Allan Burns demonstrated, on the dead subject, the possibility of 
 the establishment of the collateral circulation after ligature of the innominate artery, by tying 
 and dividing that artery, after which, he says, "Even coarse injection, impelled into the aorta, 
 passing freely by the anastomosing branches into the arteries of the right arm, filling them and 
 all the vessels of the head completely."^ The branches by which this circulation would be car- 
 ried on are very numerous; thus, all the communications across the middle line between the 
 branches of the carotid arteries of opposite sides would be available for the supply of blood to 
 the right side of the head and neck; while the anastomosis between the superior intercostal of 
 the subclavian and the first aortic intercostal (see infra on the collateral circulation after oblitera- 
 tion of the thoracic aorta) would bring the blood, by a free and direct course, into the right 
 subclavian: the numerous connections, also, between the intercostal arteries and the branches 
 of the axillary and internal mammary arteries would, doubtless, assist in the supply of blood to 
 the right arm, while the deep epigastric, from the external iliac, would, by means of its anasto- 
 mosis with the internal mammary, compensate for any deficiency in the vascularity of the wall 
 of the chest. 
 
 Surgical Anatomy. — The innominate artery has been tied at least thirty times and in six 
 instances, according to Mr. Jacobson, the patient survived. Mott's patient, however, on 
 whom the operation was first performed, lived nearly four weeks, and Graefe's more than 
 two months. In 1895 Burrell, of Boston, resected the right sterno-clavicular articulation with 
 the upper end of the sternum and tied the innominate. The patient lived 104 days. The 
 
 ' Surgical Anatomy of the Head and Neck, p. 62. 
 
THE COMMON CAROTID ARTERY 595 
 
 ligation was first successfully performed by A. W. Smyth, of New Orleans, in 1864, for sub- 
 clavian aneurism. The patient died ten years later of the original aneurism, which was reformed 
 by the collaterals. The chief danger of the operation appears to be the frequency of secondary 
 hemorrhage; but in the present day, with the practice of aseptic surgery and our greater 
 knowledge of the use of the ligature, more favorable results may be anticipated. Other causes 
 of death after operation are pleurisy, pericarditis, and suppurative cellulitis. The main 
 obstacles to the operation are, as the student will perceive from his dissection of this vessel, 
 the deep situation of the artery behind and beneath the sternum, and the number of important 
 structures which surround it in every part. 
 
 In order to apply a ligature to this vessel, the patient is to be placed upon his back, with the 
 thorax slightly raised, the head bent a little backward, and the shoulder on the side of the aneu- 
 rism strongly depressed, so as to draw out the artery from behind the sternum into the neck. 
 An incision three or more inches long is then made along the anterior border of the Sterno-mas- 
 toid muscle, terminating at the sternal end of the clavicle. From this point a second incision is 
 carried about the same length along the upper border of the clavicle. The skin is then dissected 
 back, and the Platysma divided on a director: the sternal end of the Sterno-mastoid is now 
 brought into view, and, a director being passed beneath it and close to its under surface, so as to 
 avoid any small vessels, it is to be divided ; in like manner the clavicular origin is to be divided 
 throughout the whole or greater part of its attachment. By pressing aside any loose cellular 
 tissue or vessels that may now appear the Sterno-hyoid and Sterno-thyroid muscles will be 
 exposed, and must be divided, a director being previously passed beneath them. The inferior 
 thyroid veins may come into view, and must be carefully drawn, either upward or downward, by 
 means of a blunt hook, or tied with double ligatures and divided. After tearing through a 
 strong fibro-cellular lamina, the right carotid is brought into view, and, being traced downward, 
 the arteria innominata is arrived at. The left innominate vein should now be depressed; the 
 right innominate vein, the internal jugular vein, and the pneumogastric nerve drawn to the right 
 side; and a curved aneurism needle may then be passed around the vessel, close to its surface, 
 and in a direction from below upward and inward, care being taken to avoid the right pleural 
 sac, the trachea, and cardiac nerves. The ligature should be applied to the artery as high as 
 possible, in order to allow room between it and the aorta for the formation of the coagulum. 
 The importance of avoiding the thyroid plexus of veins during the primary steps of the opera- 
 tion, and the pleural sac whilst including the vessel in the ligature, should be most carefully borne 
 in mind. After the artery has been secured, the common carotid should be tied about half an 
 inch above its origin, and also the thyroidea ima if the vessel is of any size. The several muscles 
 are united by buried sutures. An easier and safer plan than the above is that employed by 
 Burrell — viz., resection of the right sterno-clavicular articulation and of the upper end of the 
 sternum. 
 
 ARTERIES OF THE HEAD AND NECK. 
 
 The chief artery which supplies the head and neck is the common carotid: it 
 ascends in the neck and divides into two branches: the External Carotid, supply- 
 ing the superficial parts of the head and face and the greater part of the neck; 
 and the Internal Carotid, supplying to a great extent the parts within the cranial 
 cavity. 
 
 THE COMMON CAROTID ARTERY (A. CAROTIS COMMUNIS) (Figs. 388, 389, 
 
 390, 392). 
 
 The common carotid arteries, although occupying a nearly similar position in 
 the neck, differ in position, and, consequently, in their relation at their origin. 
 The right common caxotid (a. carotis communis dextra) arises from the innom- 
 inate artery, behind the right sterno-clavicular articulation. The left common 
 caxotid {a. carotis communis sinistra) arises from the highest part of the arch of 
 the aorta, and is, consequently, longer, and at its origin is contained within 
 the thorax. The course and relations of that portion of the left carotid which 
 intervenes between the arch of the aorta and the left sterno-clavicular articulation 
 will first be described. (See Figs. 388, 389, and 390.) 
 
 The left carotid within the thorax ascends obliquely outward from the arch of 
 the aorta to the root of the neck. In front, it is separated from the first piece 
 of the sternum by the Sterno-hyoid and Sterno-thyroid muscles, the leftinnomi- 
 
596 THE BLOOD -VASCULAR SYSTEM 
 
 nate vein, and the remains of the thymus gland; behind, it Hes on the trachea, 
 oesophagus, thoracic duct, and the left recurrent laryngeal nerve. Internally, it 
 is in relation with the innominate artery, inferior thyroid veins and remains of the 
 thymus gland; externally, with the left pneumogastric nerve, left pleura, and left 
 lung. The left subclavian artery is posterior and slightly external to it. 
 
 Plan of the Relations of the Left Common Carotid. 
 Thoracic Portion. 
 
 In front. 
 Sternum. 
 
 Sterno-hyoid and Sternothyroid muscles. 
 Left innominate vein. 
 Remains of the thymus gland. 
 
 Internally. /Lft c \ Externally. 
 
 Innominate artery. / Caroua. | Left pneumogastric nerve. 
 
 Inferior thyroid veins. I pui-Uoq^ I Left pleura and lung. 
 
 Remains of the thymus gland. V y Left subclavian artery. 
 
 Behind. 
 Trachea. 
 (Esophagus. 
 Thoracic duct. 
 Left recurrent laryngeal nerve. 
 
 In the neck the two common carotids resemble each other so closely that one 
 description will apply to both. Each vessel passes obliquely upward from behind 
 the sterno-clavicular articulation to a level with the upper border of the thyroid 
 cartilage, opposite the fourth cervical vertebra, where it divides into the external 
 and internal carotid ; these names being derived from the distribution of the arteries 
 to the external parts of the head and face and to the internal parts of the cranium 
 and orbit respectively. 
 
 At the lower part of the neck the two common carotid arteries are separated 
 from each other by a small interval, which contains the trachea; but at the upper 
 part, the thyroid body, the larynx and pharynx project forward between the 
 two vessels, and give the appearance of their being placed farther back in this 
 situation. The common carotid artery is contained in a sheath derived from the 
 deep cervical fascia, which also encloses the internal jugular vein and pneumo- 
 gastric nerve, the vein lying on the outer side of the artery, and the nerve between 
 the artery and vein, on a plane posterior to both. On opening the sheath these 
 three structures are seen to be separated from one another, each being enclosed in 
 a separate fibrous investment. 
 
 Relations. — At the lower part of the neck the common carotid artery is very 
 deeply seated, being covered by the integument, superficial fascia, Platysma, and 
 deep cervical fascia, the Sterno-mastoid, Sterno-hyoid, and Sterno-thyroid muscles, 
 and by the Omo-hyoid, opposite the cricoid cartilage; but in the upper part of its 
 course, near its termination, it is more superficial, being covered merely by the 
 integument, the superficial fascia, Platysma, deep cervical fascia, and inner margin 
 of the Sterno-mastoid, and, when the latter is drawn backward, it is seen to be 
 contained in a triangular space, bounded behind by the Sterno-mastoid, above by 
 the posterior belly of the Digastric, and below by the anterior belly of the Omo- 
 hyoid. This part of the artery is crossed obliquely, from within outward, by the 
 sterno-mastoid artery; it is crossed also by the superior and middle thyroid veins, 
 which terminate in the internal jugular; and, descending on its sheath in front, is 
 seen the descendens hypoglossi nerve, this filament being joined by one or two 
 branches from the cervical nerves, which cross the vessel from without inward. 
 
THE COMMON CAROTID ARTERY 
 
 597 
 
 Sometimes the descendens hypoglossi is contained within the sheath. The middle 
 thyroid vein crosses the artery about its middle, and the anterior jugular vein below; 
 the latter, however, is separated from the artery by the Sterno-hyoid and Sterno- 
 thyroid muscles. Behind, the artery is separated from the transverse processes of 
 the vertebrae by the Longus colli and Rectus capitis anticus major muscles, the 
 sympathetic nerve being interposed between it and the muscles. The recurrent 
 
 Fig. 392. — Surgical anatomy of the arteries of the neck, showing the carotid and subclavian arteries. 
 
 laryngeal nerve and inferior thyroid artery cross behind the vessel at its lower part. 
 Internally, it is in relation with the trachea and thyroid gland, the latter overlapping 
 it, the inferior thyroid artery and recurrent laryngeal nerve being interposed: 
 higher up, with the larv^nx and pharynx. On its outer side are placed the internal 
 jugular vein and pneumogastric nerve. At the lower part of the neck the internal 
 jugular vein on the right side diverges from the artery, but on the left side it 
 
598 THE BLOOD -VASCULAR SYSTEM 
 
 approaches it, and often overlaps its lower part. This is an important fact to bear 
 in mind during the performance of any operation on the lower part of the left 
 common carotid artery. In this region the relation which the right and left recur- 
 rent laryngeal nerves bear to the arteries is not identical. The left recurrent laryn- 
 geal nerve lies behind the thoracic portion of the left common carotid artery and 
 internal to the cervical portion of the vessel. The right nerve passes obliquely 
 upward and inward behind the right common carotid to reach its inner side. 
 
 Plan of the Relations of the Common Carotid Artery. 
 
 In front. 
 
 Integument and superficial fascia. Omo-hyoid. 
 
 Deep cervical fascia. Descendens and Communicans hypoglossi 
 Platysma. nerves. 
 
 Sterno-mastoid. Sterno-mastoid artery. 
 
 Sterno-hyoid. Superior and middle thyroid veins. 
 
 Sterno-thyroid. Anterior jugular vein. 
 
 Externally. 
 
 
 Internally. 
 
 Internal jugular vein. 
 
 ^ ^\ 
 
 Trachea. 
 
 Pneumogastric nerve. 
 
 / \^ 
 
 Thyroid gland. 
 
 
 Common | 
 
 Recurrent laryngeal nerve, 
 
 
 Carotid. 1 
 
 Inferior thyroid artery. 
 Larynx. 
 
 
 V.___^ 
 
 Pharynx. 
 
 Behind. 
 Longus colli. Sympathetic nerve. 
 
 Rectus capitis anticus major. Inferior thyroid artery. 
 
 Recurrent laryngeal nerve. 
 
 Peculiarities as to Origin. — The right common carotid may arise above or below the upper 
 border of the sterno-clavicular articulation. This variation occurs in one out of about eight 
 cases and a half, and the origin is more frequently below than above; or the artery may arise 
 as a separate branch from the arch of the aorta or in conjunction with the left carotid. The 
 left common carotid varies more frequently in its origin than the right. In the majority of abnor- 
 mal cases it arises with the innominate artery, or, if the innominate artery is absent, the two 
 carotids arise usually by a single trunk. It rarely joins with the left subclavian, except in cases 
 of transposition of the arch. 
 
 Peculiarities as to Point of Division. — The most important peculiarities of this vessel, in 
 a surgical point of view, relate to its place of division in the neck. In the majority of abnormal 
 cases this occurs higher than usual, the artery dividing into two branches opposite the hyoid 
 bone, or even higher; more rarely it occurs below, opposite the middle of the larynx or the lower 
 border of the cricoid cartilage; and one case is related by Morgagni where the common carotid, 
 only an inch and a half in length, divided at the root of the neck. Very rarely the common 
 carotid ascends in the neck without any subdivision, the internal carotid being wanting; and 
 in a few cases the common carotid has been found to be absent, the external and internal carotids 
 arising directly from the arch of the aorta. This peculiarity existed on both sides in some instances, 
 on one side in others. 
 
 Occasional Branches. — The common carotid usually gives off no branch previous to its 
 bifurcation; but it occasionally gives origin to the superior thyroid or its laryngeal branch, the 
 ascending pharyngeal, the inferior thyroid, or, more rarely, the vertebral artery. 
 
 Surface Marking. — The carotid arteries are covered throughout their entire extent by the 
 Sterno-mastoid muscle, but their course does not correspond to the anterior border of the muscle, 
 which passes in a somewhat curved direction from the mastoid process to the sterno-clavicular 
 joint. The course of the artery is indicated more exactly by a line drawn from the sternal end 
 of the clavicle below, to a point midway between the angle of the jaw and the mastoid process 
 above. That portion of the line below the level of the upper border of the thyroid cartilage 
 would represent the course of the vessel. 
 
 Surgical Anatomy. — The operation of tying the common carotid artery may be necessary 
 in a case of wound of that vessel or its branches, in aneurism, or in a case of pulsating tumor of 
 the orbit or skull. If the wound involves the trunk of the common carotid, it will be necessary 
 to tie the artery through the wound above and below the wounded part. If the wound is too small 
 to admit of safe and rapid work it must be enlarged. In cases of aneurism, or where one of 
 
THE COMMON CAROTID ARTERY 599 
 
 the branches of the common carotid is wounded in an inaccessible situation, it may be judged 
 necessary to tie the trunk. In such cases the whole of the artery is accessible, and any part may 
 be tied except close to either end. When the case is such as to allow of a choice being made, 
 the lower part of the carotid should never be selected as the spot upon which to place a ligature, 
 for not only is the artery in this situation placed very deeply in the neck, but it is covered by 
 three layers of muscles, and, on the left side, in the great majority of cases, the internal jugular 
 vein passes obliquely in front of it. Neither should the upper end be selected, for here the 
 superior thyroid vein and its tributaries would give rise to very considerable difficulty in the appli- 
 cation of a ligature. The point most favorable for the operation is that part of the vessel which 
 is at the level of the cricoid cartilage. It occasionally happens that the carotid artery bifurcates 
 below its usual position: if the artery be exposed at its point of bifurcation, both divisions of 
 the vessel should be tied near their origin, in preference to tying the trunk of the artery near its 
 termination; and if, in consequence of the entire absence of the common carotid or from its 
 early division, two arteries, the external and internal carotids, are met with, the ligature should 
 be placed on that vessel which is found on compression to be connected with the disease. 
 
 Ligation of the Caxotid at the Level of the Cricoid Cartilage {Ligation in the Triangle of 
 Election). — The triangle of election is bounded jxisteriorly by the anterior edge of the sterno- 
 cleido-mastoid; is bounded above by the posterior belly of the digastric; is bounded below by the 
 anterior belly of the omohyoid. In this operation the direction of the vessel and the inner 
 margin of the Sterno-mastoid are the chief guides to its performance. The patient should be 
 placed on his back with the head thrown back and turned slightly to the opposite side: an 
 incision is to be made, three inches long, in the direction of the anterior border of the Sterno- 
 mastoid, so that the centre corresponds to the level of the cricoid cartilage; after dividing the 
 integument, superficial fascia, and Platysma, the deep fascia must be cut through on a director, 
 so as to avoid wounding numerous small veins that are usually found beneath. The head 
 may now be brought forward so as to relax the parts somewhat, and the margins of the wound 
 are held asunder by retractors. The descendens hypoglossi nerve may now be exposed, and must 
 be avoided, and, the sheath of the vessel having been raised by forceps, is to be opened to a small 
 •extent over the artery at its inner side. The internal jugular vein may present itself alternately 
 •distended and relaxed ; this should be compressed both above and below, and drawn outward, 
 in order to facilitate the operation. The aneurism needle is passed from the outside, care 
 being taken to keep the needle in close contact with the artery, and thus avoid the risk of 
 injuring the internal jugular vein or including the vagus nerve. Before the ligature is tied it 
 should be ascertained that nothing but the artery is included in it. 
 
 Ligation of the Common Carotid at the Lower Part of the Neck {Ligation in the Triangle 
 ■of Necessity). — The triangle of necessity is bounded above by the anterior belly of the omo- 
 hyoid; is bounded behind by the anterior margin of the sterno-cleido-mastoid ; is bounded 
 in front by the mid-lme of the neck. This operation is sometimes required in cases of 
 aneurism of the upper part of the carotid, especially if the sac is of large size. It is best 
 performed by dividing the sternal origin of the Sterno-mastoid muscle, but may be done 
 m some cases, if the aneurism is not of very large size, by an incision along the anterior 
 border of the Sterno-mastoid, extendmg down to the sterno-clavicular articulation, and by 
 then retractmg the muscle. The easiest and best plan, however, is to make an incision two 
 •or three inches long down the lower part of the anterior border of the Sterno-mastoid muscle 
 to the sterno-clavicular joint, and a second incision, starting from the termination of the first, 
 along the upper border of the clavicle for about two inches. This incision is made through the 
 superficial and deep fascia, and the sternal origin of the muscle is exposed. This is to be divided 
 on a director, and turned up, with the superficial structures, as a triangular flap. Some loose 
 connective tissue is to be divided or torn through, and the outer border of the Sterno-hyoid 
 muscle exposed. In doing this care must be taken not to wound the anterior jugular vein, which 
 •crosses the muscle to reach the external jugular or subclavian vein. The Sterno-hyoid, and with 
 it the Stern o-thyroid, are to be drawn inward by means of a retractor, and the sheath of the 
 vessel is exposed. This must be opened with great care on its inner or tracheal side, so as to 
 avoid the internal jugular vein. This is especially necessary on the left side, where the artery 
 is commonly overlapped by the vein. On the right side there is usually an interval between the 
 artery and the vein, and not the same risk of woundmg the latter. 
 
 The common carotid artery, being a long vessel without any branches, is particularly suitable 
 for the performance of Brasdor's operation for the cure of an aneurism of the lower part of the 
 vessel. Brasdor's procedure consists in ligaturing the artery on the distal side of the aneurism, 
 and in the case of the common carotid there are no branches given off from the vessel between 
 the aneurism and the site of the ligature; hence the flow of blood through the sac of the aneurism 
 is diminished and cure takes place in the usual way, by the deposit of laminated fibrin. 
 
 Collateral Circulation. — After ligature of the common carotid the collateral circulation 
 can be perfectly established, by the free communication which exists between the carotid arteries 
 of opposite sides, both without and within the cranium, and by enlargement of the branches of 
 the subclavian artery on the side corresponding to that on which the vessel has been tied — the 
 
600 THE BLOOD -VASCULAR SYSTEM 
 
 chief communication outside the skull taking place between the superior thyroid from the 
 external carotid and the inferior thyroid from the subclavian, the profunda cervicis from the 
 subclavian and the superior intercostal with the arteria princeps cervicis of the occipital; 
 the vertebral taking the place of the internal carotid within the cranium. 
 
 Sir A. Cooper had an opportunity of dissecting, thirteen years after the operation, the case 
 in which he first successfully tied the common carotid (the second case in which he performed 
 the operation).^ The injection, however, does not seem to have been a successful one. It showed 
 merely that the arteries at the base of the brain (circle of Willis) were much enlarged on the 
 side of the tied artery, and that the anastomosis between the branches of the external carotid on 
 the affected side and those of the same artery on the sound side was free, so that the external 
 carotid was pervious throughout. 
 
 The Intercarotid Body {carotid gland, retrocarotid corpuscle) (see the Ductless 
 Glands). 
 
 The External Carotid Artery (A. Carotis Externa) (Figs. 392, 393, 394). 
 
 The external carotid artery commences opposite the upper border of the thyroid 
 cartilage, and, taking a slightly curved course, passes upward and forward, and 
 then inclines backward to the space between the neck of the condyle of the lower 
 jaw and the external meatus, where it divides into the superficial temporal and 
 internal maxillary arteries. It rapidly diminishes in size in its course up the 
 neck, owing to the number and large size of the branches given off from it. In 
 the child it is somewhat smaller than the internal carotid, but in the adult the 
 two vessels are of nearly equal size. At its commencement this artery is more 
 superficial, and placed nearer the middle line than the internal carotid, and is 
 contained in the triangular space bounded by the Sterno-mastoid behind, the 
 anterior belly of the Omo-hyoid below, and the posterior belly of the Digastric 
 and the Stylo-hyoid above.. 
 
 Relations. — It is covered by the skin, superficial fascia, Platysma, deep fascia 
 and anterior margin of the Sterno-mastoid, and is crossed by the hypoglossal nerve, 
 and by the lingual and facial veins; it is afterward crossed by the Digastric and 
 Stylo-hyoid muscles, and higher up passes deeply into the substance of the parotid 
 gland, where it lies beneath the facial nerve and the junction of the temporal and 
 internal maxillary veins. Internally is the hyoid bone, wall of the pharynx, the 
 superior laryngeal nerve, and the ramus of the jaw, from which it is separated by 
 a portion of the parotid gland. Externally, in the lower part of its course, is the 
 internal carotid artery. Behind it, near its origin, is the superior laryngeal nerve; 
 and higher up, it is separated from the internal carotid by the Stylo-glossus and 
 Stylo-pharyngeus muscles, the glosso-pharyngeal nerve, and part of the parotid 
 gland. 
 
 Plan of the Relations of the External Carotid. 
 
 In front. 
 Skin, superficial fascia. 
 Platysma and deep fascia. 
 Anterior border of Sterno-mastoid. 
 Hypoglossal nerve. 
 Lingual and facial veins. 
 Digastric and Stylo-hyoid muscles. 
 
 Parotid gland with facial nerve and temporo-maxillary vein 
 in its substance. 
 
 IntemcUly. 
 
 X N 
 
 Externally. 
 
 Hyoid bone. 
 
 X \ 
 
 Internal carotid artery, 
 
 Pharynx. 
 
 / External \ 
 
 
 Superior laryngeal nerve. 
 
 1 Carotid. 1 
 
 
 Parotid gland. 
 
 \ / 
 
 
 Ramus of jaw. 
 
 ^- -^ 
 
 
 * Guy's Hospital Reports, i., 56. 
 
THE EXTERNAL CAROTID ARTERY 601 
 
 Behind. 
 Superior laryngeal nerve. 
 Stylo-glossus. 
 Stylo-pharyngeus. 
 Glosso-pharyngeal nerve. 
 Parotid gland. 
 
 Surface Maxkicg. — The position of the external carotid artery may be marked out with 
 sufficient accuracy by a line drawn from the front of the meatus of the external ear to the side 
 of the cricoid cartilage, slightly arching the line forward. 
 
 Surgical Anatomy. — The application of a ligature to the external carotid may be required 
 in case of wounds of this vessel, or of its branches when these cannot be tied, and in some cases 
 of pulsating tumor of the scalp or face. The operation has not received the attention which it 
 deserves, owing to the fear which surgeons have entertained of secondary hemorrhage, on account 
 of the number of branches given off from the vessel. This fear, however, has been shown by 
 Mr. Cripps not to be well founded. > Ligation is often very useful as a means of prevent- 
 ing excessive hemorrhage in operations about the face, jaws, and mouth. It is sometimes 
 employed with the hope of lessening the growth of tumors by cutting off the blood supply, but 
 ligation is useless for this purpose. Ligation of one external carotid artery arrests the circu- 
 lation for only a brief period, and within a very few days the circulation is practically freely 
 re-established. This result is seen to be inevitable when we recall the numerous branches of the 
 external carotid, their free anastomoses, and the fact that a very great number of extremely minute 
 vessels in the middle line join the external carotid system of one side to that of the other side. 
 Robert H. M. Dawbarn points out that ligation of both external carotids produces only temporary 
 anaemia, for "inside of a week or ten days thereafter the pulse can again be felt in the temporals and 
 facials upon both sides."^ Dawbarn points out that even after excision of the external carotids, 
 with separate ligation of each of the eight branches, blood can still reach the nose, tongue, etc., 
 from outside systems by twenty-nine distinct routes. Whereas ligation of even both carotids will 
 not prevent the growth of a malignant tumor, excision of each external carotid, with separate 
 control of its eight branches, will sometimes prove of great value in retarding the progress of a 
 growth. It " starves " the growth and may cause it to shrink (Dawbarn's operation). To tie the 
 external carotid near its origin, below the point where it is crossed by the Digastric, an incision 
 about three inches in length should be made along the margin of the Sterno-mastoid, from the 
 angle of the jaw to the upper border of the thyroid cartilage. The ligature should be applied 
 between the lingual and superior thyroid branches. To tie the vessel above the Digastric, 
 between it and the parotid gland, an incision should be made, from the lobe of the ear to the 
 great cornu of the os hyoides, dividing successfully the skin, Platysma, and fascia. By drawing 
 the Sterno-mastoid outward, the posterior belly of the Digastric and Stylo-hyoid muscles down- 
 ward, and separating them from the parotid gland, the vessel will be exposed, and a ligature may 
 be applied to it. The circulation is at once re-established by the free communication between 
 most of the large branches of the artery (facial, lingual, superior thyroid, occipital) and the corre- 
 sponding arteries of the opposite side and by the anastomosis of its branches with those of the 
 internal carotid, and of the occipital with the branches of the subclavian, etc. 
 
 Branches. — The external carotid artery gives oflP eight branches, which, for 
 convenience of description, may be divided into four sets. (See Fig. 393, Plan of 
 the Branches.) 
 
 Anterior. Posterior. Ascending. Terminal. 
 
 Superior Thyroid. Occipital. Ascending Phar- Superficial Temporal. 
 
 I^iingual. Posterior Auric- yngeal. Internal Maxillary. 
 
 Facial. ular. 
 
 The student is here reminded that many variations are met with in the number, 
 origin, and course of these branches in different subjects; but the above arrange- 
 ment is that which is found in the great majority of cases. 
 
 The Superior Th3rroid Artery (a. thyreoidea superior) (Figs. 392, 393, and 3^6) 
 is the first branch given off from the external carotid, being derived from that vessel 
 just below the great cornu of the hyoid bone. At its commencement it is quite 
 superficial, being covered by the integument, fascia, and Platysma, and is contained 
 
 > Med.-Chir Trans., Ixi., 229. * The Treatment of Certain Malignant Growths. 
 
602 THE BLOOD -VASCULAR SYSTEM 
 
 in the triangular space bounded by the Sterno-mastoid, Digastric, and Omo-hyoid 
 muscles. After running upward and inward for a short distance, it curves down- 
 ward and forward, in an arched and tortuous manner, to the upper part of the 
 thyroid gland, passing beneath the Omo-hyoid, Sterno-hyoid, and Sterno-thyroid 
 muscles, and supplying them. It distributes numerous branches to the upper part 
 of the gland, anastomosing with its fellow of the opposite side and with the 
 inferior thyroid arteries. The terminal branches supplying the gland are generally 
 two in number: one, the largest, the anterior branch {ramus anterior) , descends 
 at the anterior border of the lateral lobe of the gland, reaches the upper border 
 of the isthmus, and then passes in the substance of the isthmus to the middle 
 line of the neck, where it anastomoses with the corresponding artery of the 
 opposite side : the posterior branch {ramus 'posterior) descends along the posterior 
 border of the lateral lobe of the gland, the anterior and posterior branches 
 anastomose with each other and with branches of the inferior thyroid, and both 
 of them send branches to the thyroid gland {rami glandular es) . Besides the 
 arteries distributed to the muscles by which it is covered and to the substance 
 of the gland, the branches of the superior thyroid are the following: 
 
 Hyoid. Superior Laryngeal. 
 
 Superficial Descending Branch (Sterno-mastoid). Crico-thyroid. 
 
 The Hyoid or Infra-hyoid {ramus hyoideus) is a small branch which runs along 
 the lower border of the os hyoides beneath the Thyro-hyoid muscle; after sup- 
 plying the muscles connected to that bone, it forms an arch, by anastomosing 
 with the vessel of the opposite side. 
 
 The Superficial Descending or Sterno-mastoid Branch {ramus sternocleidomas- 
 toideus) runs downward and outward across the sheath of the common carotid 
 artery, and supplies the Sterno-mastoid and neighboring muscles and integument. 
 There is frequently a separate branch from the external carotid distributed to the 
 Sterno-mastoid muscle. 
 
 The Superior Laryngeal (a. laryngea superior), larger than either of the preceding, 
 accompanies the internal laryngeal nerve, beneath the Thyro-hyoid muscle: it 
 pierces the thyro-hyoid membrane, and supplies the muscles, mucous membrane, 
 and glands of the larynx, anastomosing with the branch from the opposite 
 side. 
 
 The Crico-thyroid {ramus cricothyreoideus) is a small branch which runs trans- 
 versely across the crico-thyroid membrane, communicating with the artery of the 
 opposite side. 
 
 Arteries of the Thyroid Gland. — The thyroid gland is supplied by the two 
 superior thyroids from the external carotid; the two inferior thyroids from the 
 subclavian, and sometimes also by the thyreoidea ima from the innominate. 
 
 The superior thyroid joins the gland at the summit of the upper horn, passes 
 down the posterior surface of the gland toward the inner surface of the upper horn, 
 comes forward to the anterior margin of the inner surface, descends to the isthmus, 
 and on the superior border of the isthmus anastomoses with the artery from the 
 other side. The superior thyroid artery sends numerous branches across the 
 anterior surface of the gland. 
 
 The inferior thyroid artery is larger than the superior artery. It passes to 
 the posterior surface of the gland and divides into branches. Some of the branches 
 enter the hilus; others track across the posterior surface of the gland. The inferior 
 thyroid artery is close to the recurrent laryngeal nerve. The artery, as a rule, 
 passes behind-theJiervebief ore it divides into branches. It may divide first and 
 then one or two branches may be in front of the nerve. In unusual cases the 
 artery before division is in front of the nerve, or all the branches are in front.' 
 
 1 Berry. Diseases of the Thyroid Gland. 
 
THE EXTERNAL CAROTID ARTERY 603 
 
 The thyreoidea ima passes to the lower portion of the gland. Berry points out 
 that the thyroid arteries communicate very freely with each other; only the small 
 branches pass into the interior of the gland; the larger branches "ramify on the 
 surface of the gland, just beneath the capsule."^ 
 
 Surgical Anatomy. — The superior thyroid, or one of its branches, is often divided in cases 
 of cut throat, giving rise to considerable hemorrhage. In such cases the artery should be secured, 
 the woiuid being enlarged for that purpose, if necessary. The operation may be easily per- 
 formed, the position of the artery being very superficial, and the only structures of importance 
 covering it being a few small veins. The operation of tying the superior thyroid artery to lessen 
 the size of a bronchocele has been performed in numerous instances with partial or temporary 
 success. When, however, the collateral circulation between this vessel and the artery of the 
 opposite side, and the inferior thyroid, is completely re-established, the tumor usually regains 
 its former size, and hence the operation has been given up, especially as better results are 
 obtained by other means. Both thyroid arteries on the same side, and indeed all the four 
 thyroid arteries, have been tied in enlarged thyroid. The superior and inferior thyroid arteries 
 of the involved side are ligated before extirpating a goitrous lobe of the thyroid. 
 
 The position of the superficial descending branch is of importance in connection with the 
 operation of ligation of the common carotid artery. It crosses and lies on the sheath of this 
 vessel, and may chance to be wounded in opening the sheath. The position of the crico-thyroid 
 branch should be remembered, as it may prove the source of troublesome hemorrhage during 
 the operation of laryngotomy. In performing the operation of quick laryngotomy the crico- 
 thyroid membrane should be incised transversely in order to avoid this vessel. 
 
 The Lingual Artery (a. lingualis) (Figs. 392 and 393) arises from the external 
 carotid between the superior thyroid and facial; it first runs obliquely upward 
 and inward to the great cornu of the hyoid bone; it then curves downward and 
 forward, forming a loop which is crossed by the hypoglossal nerve, and, passing 
 beneath the Digastric and Stylo-hyoid muscles, it runs horizontally forward, 
 beneath the Hyo-glossus, and finally, ascending almost perpendicularly to the 
 tongue, turns forward on its under surface as far as the tip, under the name of 
 the ranine artery. 
 
 Relations. — Its first, or oblique, portion is superficial, being contained in the 
 same triangular space as the superior thyroid artery, resting upon the middle con- 
 strictor of the pharynx, and covered by the Platysma and fascia of the neck. Its 
 second, or curved, portion also lies upon the middle constrictor, being covered at 
 first by the tendon of the Digastric and the Stylo-hyoid muscle, and afterward by 
 the Hyo-glossus, the latter muscle separating it from the hypoglossal nerve. Its 
 third, or horizontal, portion lies between the Hyo-glossus and Genio-hyo-glossus 
 muscles. The fourth, or terminal, part, under the name of the ranine, runs along 
 the under surface of the tongue to its tip: it is very superficial, being covered 
 only by the mucous membrane, and rests on the Lingualis on the outer side of 
 the Genio-hyo-glossus. The hypoglossal nerve crosses the lingual artery, and then 
 becomes separated from it, in the second part of its course, by the Hyo-glossus 
 muscle. 
 
 Branches. — The branches of the lingual artery are — the 
 
 Hyoid. Sublingual. 
 
 Dorsalis Linguae. Ranine. 
 
 The Hyoid or Supra-hyoid Branch (ramus hyoideus) runs along the upper border 
 of the hyoid bone, supplying the muscles attached to it and anastomosing with 
 its fellow of the opposite side. 
 
 The Dorsalis Linguae (ramus dorsalis linguae) (Fig. 445) arises from the lingual 
 artery beneath the Hyo-glossus muscle (which, in the figure, has been partly cut 
 away, to show the vessel) ; it ascends to the dorsum of the tongue, and supplies the 
 mucous membrane, the tonsil, soft palate, and epiglottis, anastomosing with its 
 
 1 Berry. Diseases of the Thyroid Gland 
 
604 THE BLOOD -VASCULAR SYSTEM 
 
 fellow from the opposite side. This artery is frequently represented by two or 
 three small branches. 
 
 The Sublingual (a. siihlingualis) , which may be described as a branch of bifur- 
 cation of the lingual artery, arises at the anterior margin of the Hyo-glossus muscle, 
 and runs forward between the Genio-hyo-glossus and the sublingual gland. It 
 supplies the substance of the gland, giving branches to the Mylo-hyoid and 
 neighboring muscles, the mucous membrane of the mouth and gums. One 
 branch runs behind the alveolar process of the lower jaw in the substance of the 
 gum to anastomose with a similar artery from the other side. 
 
 The Ranine or Deep Lingual (a. profunda lingua) may be regarded as the other 
 branch of bifurcation. It is usually described as the continuation of the lingual 
 artery; it runs along the under surface of the tongue, resting on the Inferior 
 lingualis, and covered by the mucous membrane of the mouth; it lies on the outer 
 side of the Genio-hyo-glossus, accompanied by the lingual nerve. On arriving 
 at the tip of the tongue it is said to anastomose with the artery of the opposite 
 side, but this is denied by Hyrtl. These vessels in the mouth are placed one on 
 each side of the frtenum. 
 
 Surgical Anatomy. — The lingual artery may be divided near its origin in cases of cut throat, 
 a complication that not unfrequently happens in this class of wounds; or severe hemorrhage 
 which cannot be restrained by ordinary means may ensue from a wound or deep ulcer of the 
 tongue. In the former case the primary wound may be enlarged if necessary, and the bleeding 
 vessels secured. In the latter case it has been suggested that the lingual artery should be tied 
 near its origin. Ligature of the lingual artery is also occasionally practised, as a paUiative measure, 
 in cases of cancer of the tongue, in order to check the progress of the disease by starving the 
 growth, and it is sometimes tied as a preliminary measure to removal of the tongue. The operation 
 is a somewhat difficult one, on account of the depth of the artery, the number of important 
 structures by which it is surrounded, the loose and yielding nature of the parts upon which it is 
 supported, and its occasional irregularity of origin. An incision is to be made in a curved direc- 
 tion from a point one finger's breadth external to the symphysis of the jaw downward to the 
 cornu of the hyoid bone, and then upward to near the angle of the jaw. Care must be taken not 
 to carry this incision too far backward, for fear of endangering the facial vein. In the first 
 incision the skin, superficial fascia, and Platysma will be divided, and the deep fascia exposed. 
 The deep fascia is then to be incised and the submaxillary gland exposed and pulled upward by 
 retractors. A triangular space is now exposed. Leaser's triangle, bounded internally by the pos- 
 terior border of the Mylo-hyoid muscle: below and externally, by the tendon of the Digastric; 
 and above, by the hypoglossal nerve. The floor of the space is formed by the Hyo-glossus muscle, 
 beneath which the artery lies. The fibres of this muscle are now to be cut through horizontally 
 and the vessel exposed, care being taken, while near the vessel, not to open the pharynx. 
 
 Troublesome hemorrhage may occur in the division of the franum in children if the ranine 
 arteries, which lie on each side of it, are wounded. The student should remember that the opera- 
 tion is always to be performed with a pair of blunt-pointed scissors, and the mucous membrane 
 only is to be divided by a very superficial cut, which cannot endanger any vessel. The scissors, 
 also, should be directed away from the tongue. Any further liberation of the tongue which may 
 be necessary can be effected by tearing. 
 
 The Facial or External Maxillary Artery (a. maxillaris externa) (Figs. 392, 
 393, 394, and 395) arises a little above the lingual, and passes obliquely upward, 
 beneath the Digastric and Stylo-hyoid muscles, and frequently beneath the hypo- 
 glossal nerve; it now runs forward under cover of the body of the lower jaw, lodged 
 in a groove on the posterior surface of the submaxillary gland ; this may be called 
 the cervical part of the artery. It then curves upward over the body of the jaw 
 at the anterior inferior angle of the Masseter muscle; passes forward and upward 
 across the cheek to the angle of the mouth, then upward along the side of the nose, 
 and terminates at the inner canthus of the eye, under the name of the angular artery 
 (a. angularis). The facial artery, both in the neck and on the face, is remarkably 
 tortuous : in the former situation its tortuosity enables it to accommodate itself to 
 the movements of the pharynx in deglutition, and in the latter to the movements, 
 of the jaw and the lips and cheeks. 
 
THE EXTERNAL CAROTID ARTERY 
 
 605 
 
 Relations. — In the neck its origin is superficial, being covered by the integu- 
 ment, Platysma, and fascia; it then passes beneath the Digastric and Stylo-hyoid 
 muscles and part of the submaxillary gland. It lies upon the middle constrictor 
 of the pharynx, and is separated from the Stylo-glossus and Hyo-glossus muscles 
 by a portion of the submaxillary gland. On the face, where it passes over the 
 body of the lower jaw, it is comparatively superficial, lying immediately beneath 
 the Platysma. In this situation its pulsation may be distinctly felt, and compres- 
 sion of the vessel against the bone can be effectually made. In its course over the 
 face it is covered by the integument, the fat of the cheek, and, near the angle of the 
 
 A rteria septi nast. 
 iiperior coronary. 
 
 Inferior coronary. 
 Inferior IcMal. 
 
 Fig. 394. — The arteries of the face and scalp.* 
 
 mouth, by the Platysma, Risorius, and Zygomatic muscles. It rests on the Bucci- 
 nator, the Levator anguli oris, and the I^evator labii superioris (sometimes piercing 
 or else passing under this last muscle). The facial vein lies to the outer side of 
 the artery, and takes a more direct course across the face, where it is separated 
 from the artery by a considerable interval. In the neck it lies superficial to the 
 artery. The branches of the facial nerve cross the artery, and branches of the 
 infraorbital nerve lie beneath it. 
 
 Branches. — The branches of this vessel may be divided into two sets: those 
 ^iven off below the jaw (cervical), and those on the face (facial). 
 
 * The muscular tissue of the lips must be supposed to have been cut away, in order to show the course of the 
 ■coronary arteries 
 
606 THE BLOOD -VASCULAR SYSTEM 
 
 Cervical Branches. Facial Branches, 
 
 Inferior or Ascending Palatine. Muscular. 
 
 Tonsillar. Inferior Labial. 
 
 Submaxillary. Inferior Coronary. 
 
 Submental. Superior Coronary. 
 
 Muscular. Lateral Nasal. 
 
 Angular. 
 
 The Inferior or Ascending Palatine (a. 'palatine ascendens) passes up between 
 the Stylo-glossus and Stylo-pharyngeus to the outer side of the pharynx, along 
 which it is continued between the Superior constrictor and the Internal ptery- 
 goid to near the base of the skull. It supplies the neighboring muscles, the 
 tonsil, and Eustachian tube, and divides, near the Levator palati, into two 
 branches: one follows the course of the Levator palati, and, winding over the 
 upper border of the Superior constrictor, supplies the soft palate and the palatine 
 glands, anastomosing with its fellow of the opposite side and with the posterior 
 palatine branch of the internal maxillary artery; the other pierces the Superior 
 constrictor and supplies the tonsil, anastomosing with the tonsillar and ascending 
 pharyngeal arteries. 
 
 The Tonsillar (ramus tonsillaris) passes up between the Internal pterygoid 
 and Stylo-glossus, and then ascends along the side of the pharynx, perforating 
 the Superior constrictor, to ramify in the substance of the tonsil and root of the 
 tongue. 
 
 Fig. 395. — The coronary arteries, the glands of the lips, and the nerves of the right side seen from the 
 posterior surface after removal of the mucous membrane. (Poirier and Charpy.) 
 
 The Submaxillary or Glandular Branches (rami glandulares) consist of three oi 
 four large vessels, which supply the submaxillary gland, some being prolonged to 
 the neighboring muscles, lymphatic glands, and integument. 
 
 The Submental (a. submentalis) (Fig. 392), the largest of the cervical branches, 
 is given off from the facial artery just as that vessel quits the submaxillary gland : 
 it runs forward upon the Mylo-hyoid muscle, just below the body of the "jaw and 
 beneath the Digastric; after supplying the surrounding muscles, and anastomosing 
 with the sublingual artery by branches which perforate the TVlylo-hyoid muscle, it 
 arrives at the symphysis of the chin, where it turns over the border of the jaw and 
 divides into a superficial and a deep branch; the former passes between the integu- 
 ment and Depressor labii inferioris, supplies both, and anastomoses with the 
 inferior labial. The deep branch passes between the latter muscle and the bone, 
 supplies the lip, and anastomoses with the inferior labial and mental arteries. 
 
 The Muscular Branches are distributed to the Internal pterygoid and Stylo- 
 hyoid in the neck, and to the Masseter and Buccinator on the face. 
 
THE EXTERNAL CAROTID ARTERY 607 
 
 The Inferior Labial (a. labialis inferior) (Fig. 394) passes beneath the Depressor 
 anguH oris, to supply the muscles and integument of the chin and lower lip, anas- 
 tomosing with the inferior coronary and submental branches of the facial, and with 
 the mental branch of the inferior dental artery. 
 
 The Inferior Coronary (Figs. 394 and 395) is derived from the facial artery, near 
 the angle of the mouth : it passes upward and inward beneath the depressor anguli 
 oris, and, penetrating the Orbicularis oris muscle, runs in a tortuous course along 
 the edge of the lower lip between this muscle and the mucous membrane, inoscu- 
 lating with the artery of the opposite side. This artery supplies the labial glands, 
 the mucous membrane, and muscles of the lower lip, and anastomoses with the 
 inferior labial from the facial and the mental branch of the inferior dental artery. 
 
 The Superior Coronary (a. labialis superior) (Figs. 394 and 395) is larger and more 
 tortuous in its course than the preceding. It follows the same course along the 
 edge of the upper lip, lying between the mucous membrane and the Orbicularis 
 oris, and anastomoses with the artery of the opposite side. It supplies the textures 
 of the upper lip, and gives off in its course two or three vessels which ascend to the 
 nose. One, named the inferior artery of the septum, ramifies on the septum of the 
 nostrils as far as the point of the nose, and there anastomoses with the naso- 
 palatine artery; another, the artery of the ala, supplies the ala of the nose. 
 
 The Lateralis Nasi is derived from the facial, as that vessel is ascending along 
 the side of the nose; it supplies the ala and dorsum of the nose, anastomosing 
 with its fellow, the nasal branch of the ophthalmic, the inferior artery of the sep- 
 tum, the artery of the ala, and the infraorbital. 
 
 The Angular Artery (a. angularis) is the termination of the trunk of the facial; 
 it ascends to the inner angle of the orbit, embedded in the fibres of the Levator 
 labii superioris ahieque nasi, and accompanied by a large vein, the angular vein; 
 it distributes some branches on the cheek which anastomose with the infraorbital. 
 After supplying the lachrymal sac and Orbicularis palpebrarum muscle, the 
 angular artery terminates by anastomosing with the nasal branch of the oph- 
 thalmic artery. 
 
 The anastomoses of the facial artery are very numerous, not only with the 
 vessel of the opposite side, but, in the neck, with the sublingual branch of the 
 lingual; with the ascending pharyngeal; and with the posterior palatine, a branch of 
 the internal maxillary, by its inferior or ascending palatine and tonsillar branches ; 
 on the face, with the mental branch of the inferior dental as it emerges from the 
 mental foramen, with the transverse facial, a branch of the temporal; with the 
 infraorbital, a branch of the internal maxillary, and with the nasal branch of 
 the ophthalmic. 
 
 Peculiarities. — The facial artery not unfrequently arises by a common trunk with the lingual. 
 This vessel is also subject to some variations in its size and in the extent to which it supplies 
 the face. It occasionally terminates as the submental, and not unfrequently supplies the face 
 only as high as the angle of the mouth or nose. The deficiency is then supplied by enlargement 
 of one of the neighboring arteries. 
 
 Surgical Anatomy. — The passage of the facial artery over the body of the jaw would appear 
 to afford a favorable position for the application of pressure in case of hemorrhage from the 
 lips, the result either of an accidental wound or during an operation ; but its application is useless, 
 except for a very short time, on account of the free communication of this vessel with its fellow 
 and with numerous branches from different sources. In a wound involving the lip it is better 
 to seize the part between the fingers, and evert it, when the bleeding vessel may be at once secured 
 with pressure-forceps. In order to prevent hemorrhage in cases of removal of diseased growths 
 from the part, the lip should be compressed on each side between the fingers and thumb or by 
 a pair of specially devised clamp-forceps, whilst the suigeon excises the diseased part. In order 
 to stop hemorrhage where the lip has been divided in an operation, it is necessary, in uniting 
 the edges of the wound, to pass the sutures through the cut edges from the skin alraost-as deep 
 as the mucous surface; by these means not only are the cut surfaces more neatly and securely 
 adapted to each other, but the possibility of hemorrhage is prevented by including in the suture 
 
608 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 the divided artery. If the suture is, on the contrary, passed through merely the cutaneous 
 portion of the wound, hemorrhage occurs into the cavity of the mouth. The student should, 
 lastly, observe the relation of the angular artery to the lachrymal sac, and it will be seen that, 
 as the vessel passes up along the inner margin of the orbit, it ascends on its nasal side. In 
 operating for fistula lacrimalis the sac should always be opened on its outer side, in order that 
 this vessel may be avoided. 
 
 The Occipital Artery (a. occipitalis) (Figs. 392, 393, 394, and 396) arises from 
 the posterior part of the external carotid, opposite the facial, near the lower margin 
 
 Internal jugular vein. 
 Occipital artery 
 
 Internal maxil- 
 lary artery. 
 
 Facial 
 nerve. 
 
 Ijnqaal 
 
 nerve. 
 Inferior dental 
 
 nerve. 
 
 Mylo-hyoiA 
 
 SUPERIOR OBLIQUE 
 MUSCLE. 
 
 Vertebral artery 
 
 INFERIOR OBLIQUE 
 MUSCLE. 
 
 Pneumogastri 
 nerve. 
 
 Hypo-glossal 
 nerve. 
 Internal carotid 
 
 STERNO-MASTOI 
 MUSCLE. 
 
 Superior thyroid 
 artery. 
 External carotid 
 artery. 
 
 Fig. 396. — The occipital artery and its relations. (From a dissection by Mr. Gerald S. Hughes.) 
 
 of the Digastric muscle. At its origin it is covered by the posterior belly of the 
 Digastric muscle and the Stylo-hyoid muscle, and the hypoglossal nerve winds 
 around it from behind forward; higher up, it passes across the internal carotid 
 artery, the internal jugular vein, and the pneumogastric and spinal accessory nerves; 
 
THE EXTERNAL CAROTID ARTERF 609 
 
 it then ascends to the interval between the transverse process of the atlas and the 
 mastoid process of the temporal bone, and passes horizontally backward, groov- 
 ing the surface of the latter bone, being covered by the Sterno-mastoid, Splenius, 
 Trachelo-mastoid, and Digastric muscles, and resting upon the Rectus lateralis, the 
 Superior oblique, and Complexus muscles; it then changes its course and passes 
 vertically upward, pierces the fascia which connects the cranial attachment of 
 the Trapezius with the Sterno-mastoid, and ascends in a tortuous course over 
 the occiput, as high as the vertex, where it divides into numerous branches (rami 
 occipifales). It is accompanied in the latter part of its course by the great occip- 
 ital nerve, and occasionally by a cutaneous filament from the suboccipital nerve. 
 Branches. — The branches given off from this vessel are — 
 
 Muscular. Meningeal. 
 
 Sterno-mastoid. Mastoid. 
 
 Auricular. Arteria Princeps Cervicis. 
 
 The Muscular Branches (rami musculares) supply the Digastric, Stylo-hyoid, 
 Splenius, and Trachelo-mastoid muscles. 
 
 The Sterno-mastoid (a. sternocleidomastoidea) is a large and constant branch, 
 generally arising from the artery close to its commencement, but sometimes 
 springing directly from the external carotid. It first passes downward and back- 
 ward over the hypoglossal nerve, and enters the substance of the muscle in com- 
 pany with the spinal accessory nerve. 
 
 The Auricular Branch (ramus auricidaris) supplies the back part of the concha. 
 It frequently gives off a branch, which enters the skull through the mastoid 
 foramen and supplies the dura mater, the diploe, and the mastoid cells. 
 
 The Meningeal Branch (ramus meningeus) ascends with the internal jugular 
 vein, and enters the skull through the foramen lacerum posterius, or through the 
 anterior condyloid foramen, to supply the dura mater in the posterior fossa. 
 
 The Mastoid Branch (ramus mastoideus) is a small vessel, by no means constant. 
 It passes into the skull through the mastoid foramen and is distributed upon the 
 dura mater of the posterior fossa. 
 
 The Arteria Princeps Cervicis (ramu^ descendens), the largest branch of the 
 occipital, descends along the back part of the neck and divides into a super- 
 ficial and a deep portion. The former runs beneath the Splenius, giving off 
 branches which perforate that muscle to supply the Trapezius, which anastomose 
 with the superficial cervical artery, a branch of the Transversalis colli : the latter 
 passes beneath the Complexus between it and the Semispinalis colli, and anasto- 
 moses with branches from the vertebral and with the deep cervical artery, a 
 branch of either the superior intercostal or the subclavian. The anastomosis 
 between these vessels serves mainly to establish the collateral circulation after 
 ligation of the carotid or subclavian artery. 
 
 The cranial branches (rami occipitales) of the occipital artery are distributed 
 upon the occiput; they are very tortuous, and lie between the integument and 
 Occipito-frontalis, anastomosing with the artery of the opposite side, the pos- 
 terior auricular and temporal arteries. They supply the back part of the 
 Occipito-frontalis muscle, the integument, and pericranium. 
 
 The Posterior Auricular Artery (a. auricularis posterior) (Figs. 392, 393, and 
 394) is a small vessel which arises from the external carotid, above the Digastric 
 and Stylo-hyoid muscles, opposite the apex of the styloid process. It ascends, 
 under cover of the parotid gland, on the styloid process of the temporal bone, to 
 the groove between the cartilage of the ear and the mastoid process, immediately 
 above which it divides into its two terminal branches, the auricular and mastoid. 
 Just before arriving at the mastoid process, this artery is crossed by the facial 
 nerve, and has beneath it the spinal accessory nerve. 
 
 39 
 
610 THE BLOOD -VASCULAR SYSTEM 
 
 Branches. — Besides several small branches to the Digastric, Stylo-hyoid, and 
 Sterno-mastoid muscles and to the parotid gland, this vessel gives off three 
 branches : 
 
 Stylo-mastoid. Auricular. Mastoid. 
 
 The Stylo-mastoid Branch {a. siylomastoidea) enters the stylo-mastoid foramen^ 
 and supplies the tympanum, mastoid cells, and semicircular canals. In the 
 young subject a branch from this vessel forms, with the tympanic branch from 
 the internal maxillary, a vascular circle, which surrounds the membrana tympani, 
 and from which delicate vessels ramify on that membrane. It anastomoses with 
 the petrosal branch of the middle meningeal artery by a twig, which enters the 
 hiatus Fallopii. 
 
 The Auricular Branch {ramus auricularis) , one of the terminal branches, ascends 
 behind the ear, beneath the Retrahens auriculam muscle, and is distributed to 
 the back part of the cartilage of the ear, upon which it ramifies minutely, some 
 branches curving round the margin of the fibro-cartilage, others perforating it, 
 to supply its anterior surface. It anastomoses with the posterior branch of the 
 superficial temporal and also with the anterior auricular branches. 
 
 The Mastoid Branch (ramus mastoideus) passes backward, over the Sterno- 
 mastoid muscle, to the scalp above and behind the ear. It supplies the posterior 
 belly of the Occipito-frontalis muscles and the scalp in this situation. It anasto- 
 moses with the occipital artery. 
 
 The Ascending Pharyngeal Artery (a. pharyngea ascendens) (Figs. 392 and 
 393), the smallest branch of the external carotid, is a long, slender vessel, deeply 
 seated in the neck, beneath the other branches of the external carotid and the 
 Stylopharyngeus muscle. It arises from the back part of the external carotid, near 
 the commencement of that vessel, and ascends vertically between the internal 
 carotid and the side of the pharynx, to the under surface of the base of the skull, 
 lying on the Rectus capitis anticus major muscle. 
 
 Branches. — Its branches may be subdivided into four sets: 
 
 Prevertebral. Pharyngeal. Tympanic. Meningeal. 
 
 The Prevertebral Branches are numerous small vessels which supply the Recti 
 capitis antici and Longus colli muscles, the sympathetic, hypoglossal, and pneu- 
 mogastric nerves, and the lymphatic glands. They anastomose with the ascending 
 cervical artery. 
 
 The Pharyngeal Branches {rami pharyngei) are three or four in number. Two 
 of these descend to supply the middle and inferior Constrictors and the Stylo- 
 pharyngeus, ramifying in the substance of the muscles and in the submucous 
 tissue of the mucous membrane lining them. The largest of the pharyngeal 
 branches passes inward, running upon the Superior constrictor, and sends rami- 
 fications to the soft palate and tonsil, which take the place of the ascending 
 palatine branch of the facial artery when that vessel is of small size. A twig 
 from this branch supplies the Eustachian tube. 
 
 The Tympanic Branch {a. tympanica inferior) is a small artery which passes 
 through a minute foramen in the petrous portion of the temporal bone, in com- 
 pany with the tympanic branch of the Glosso-pharyngeal nerve to supply the 
 inner wall of the tympanum and anastomose with the other tympanic arteries. 
 
 The Meningeal Branches consist of several small vess'els, which pass through 
 foramina in the base of the skull, to supply the dura mater. One, the posterior 
 meningeal (a. meningea posterior), enters the cranium through the foramen lacerum 
 posterius; a second passes through the foramen lacerum medium; and occasion- 
 ally a third through the anterior condyloid foramen. They are all distributed 
 to the dura mater. 
 
THE EXTERNAL CAROTID ARTERY 611 
 
 Surgical Anatomy. — The ascending pharyngeal artery has been wounded from the throat, 
 as in the case in which the stem of a tobacco-pipe was driven into the vessel, causing fatal hemor- 
 rhage. After removal of the tonsil there is sometimes severe bleeding. This is almost never 
 due to wounding of the internal carotid artery, as the latter vessel, if normally placed, is too 
 far away to be damaged. The bleeding comes from branches of the ascending pharyngeal, 
 tonsillar, or ascending palatine arteries. 
 
 The Superficial Temporal Artery (a. temporalis superficialis) (Fig. 392, 393, and 
 394), the smaller of the two terminal branches of the external carotid, appears, from 
 its direction, to be the continuation of that vessel. It commences in the substance 
 of the parotid gland, in the interspace between the neck of the lower jaw and the 
 external auditory meatus, crosses over the posterior root of the zygoma, passes 
 beneath the Attrahens auriculam muscle, lying on the temporal fascia, and 
 divides, about two inches above the zygomatic arch, into two branches, an anterior 
 and a posterior. This vessel is accompanied by the auriculo-temporal nerve. 
 
 The Anterior Temporal runs tortuously upward and forward to the forehead, 
 supplying the muscles, integument, and pericranium in this region, and anasto- 
 moses with the supra-orbital and frontal arteries. The terminal portion of the 
 anterior branch is called the frontal artery {ramus frontalis). 
 
 The Posterior Temporal, larger than the anterior, curves upward and backward 
 along the side of the head, lying superficial to the temporal fascia, and inosculates 
 with its fellow of the opposite side, and with the posterior auricular and occipital 
 arteries. The terminal portion of the posterior branch is named the parietal 
 artery (ramus parietalis) . 
 
 The superficial temporal artery, as it crosses the zygoma, is covered by the 
 Attrahens auriculam muscle, and by a dense fascia given off from the parotid 
 gland : it is crossed by the temporo-facial division of the facial nerve and one or 
 two veins, and is accompanied by the auriculo-temporal nerve, which lies behind 
 it. Besides some twigs to the parotid gland, the articulation of the jaw, and the 
 Masseter muscle. 
 
 Branches. — The branches of the superficial temporal artery are the — 
 
 Transverse Facial. Orbital. 
 
 Middle Temporal. Anterior Auricular. 
 
 The Transverse Facial Branch (a. transversa faciei) is given off from the tem- 
 poral before that vessel quits the parotid gland; running forward through its 
 substance, it passes transversely across the face, between Stenson's duct and 
 the lower border of the zygoma, and divides on the side of the face into numerous 
 branches, which supply the parotid gland, the Masseter muscle, and the integu- 
 ment, anastomosing with the facial, masseteric, and infra-orbital arteries. This 
 vessel rests on the Masseter, and is accompanied by one or two branches of the 
 facial nerve. It is sometimes a branch of the external carotid. 
 
 The Middle Temporal Artery (a. temporalis media) arises immediately above 
 the zygomatic arch, and, perforating the temporal fascia, gives branches to the 
 Temporal muscle, anastomosing with the deep temporal branches of the internal 
 maxillary. It occasionally gives off an orbital branch, which runs along the upper 
 border of the zygoma, between the two layers of the temporal fascia, to the outer 
 angle of the orbit. This branch, which may arise directly from the superficial 
 temporal artery, supplies, the Orbicularis palpebrarum, and anastomoses with 
 the lachrymal and palpebral branches of the ophthalmic artery. 
 
 The Orbital Artery (a. zygomaticoorhitalis) comes off from the temporal just 
 above the zygoma and is distributed to the upper orbital margin. 
 
 The Anterior Auricular Branches (rami auriculares anteriores) are distributed 
 to the anterior portion of the pinna, the lobule, and part of the external meatus, 
 anastomosing with branches of the posterior auricular. 
 
612 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 Surgical Anatomy. — Formerly the operation of arteriotomy was performed upon this vessel 
 in cases of inflammation of the eye or brain, but at the present time the operation is obsolete. 
 If the student will consider the relations of the trunk of the vessels as it crosses the zygomatic 
 arch, with the surrounding structures, he will observe that it is covered by a thick and dense 
 fascia, crossed by one of the main divisions of the facial nerve and one or two veins, and accom- 
 panied by the auriculo-temporal nerve. The anterior branch, on the contrary, is subcutaneous, 
 and is a large vessel. 
 
 The Internal Maxillary Artery (a. maxillaris interna) (Figs. 397 and 398), the 
 larger of the two terminal branches of the external carotid, arises from that vessel 
 opposite the neck of the condyle of the lower jaw, and is at first imbedded in the 
 
 Incisor. 
 
 Fig. 397. — The internal maxillary artery and its branches. 
 
 Bmall Meningeal, 
 middle Meningeal 
 Tympan 
 
 Inferior Dental- 
 
 Jterygofalatine^ ^^^^ 
 
 «5soS /Descending Palatin4 
 Deep ■^'^Po'-al^^/^^^^Spheno-paMine 
 
 [^S' ■ "'■6,, 
 
 Fig. 398. — Plan of the branches. 
 
 substance of the parotid gland; it passes inward between the ramus of the jaw 
 and the internal lateral ligament, and then upon the outer surface of the External 
 pterygoid muscle to the spheno-maxillary fossa, to supply the deep structures 
 of the face. For convenience of description it is divided into three portions : a 
 maxillary, a pterygoid, and spheno-maxillary. 
 
 In the first part of its course, the maxillary portion, the artery passes horizontally 
 forward and inward, between the ramus of the jaw and the internal lateral liga- 
 ment. The artery here lies parallel to and a little below the auriculo-temporal 
 nerve; it crosses the inferior dental nerve, and lies along the lower border of the 
 External pterygoid muscle. 
 
THE EXTERNAL CAROTID ARTERY 613 
 
 In the second part of its course, tli: pterygoid portion, it runs obliquely forward, 
 and upward upon the outer surface of the External pterygoid muscle, being 
 covered by the ramus of the lower jaw and lower part of the Temporal muscle; 
 or it may pass on the inner surface of the External pterygoid muscle to reach the 
 interval between its two heads, between which it passes to reach the spheno- 
 maxillary fossa. 
 
 In the third part of its course, the spheno-maxillaxy portion, it approaches the 
 superior maxillary bone, and enters the spheno-maxillary fossa in the interval 
 between the two heads of the External pterygoid nmscle, where it lies in relation 
 witli Meckel's ganglion, and gives off its terminal branches. 
 
 The branches of this vessel may be divided into three groups, corresponding 
 with its three divisions. 
 
 Branches of the First or Maxillary Portion (Fig. 398) ; 
 
 Anterior Tympanic. Small Meningeal. 
 
 Deep Auricular. Inferior Dental. 
 
 Middle Meningeal. 
 
 The Anterior Tympanic Branch (a. tympanica anterior) passes upward behind 
 the articulation of the lower jaw, enters the tympanum through the Glaserian 
 fissure, and ramifies upon the membrana tympani, forming a vascular circle 
 around the membrane with the stylo-mastoid artery, and anastomosing with 
 the Vidian and the tympanic branch from the internal carotid. 
 
 The Deep Auricular Branch (a. auricularis profunda) often arises in common 
 with the preceding. It passes upward in the substance of the parotid gland, 
 behind the temporo-maxillary articulation, pierces the cartilaginous or bony wall 
 of the external auditory meatus, and supplies its cuticular lining and the outer 
 surface of the membrana tympani. 
 
 The Middle Meningeal Branch (a. meningea media) is the largest of the branches 
 which supply the dura mater. It arises from the internal maxillary, between the 
 internal lateral ligament and the neck of the jaw, and passes vertically upward 
 between the two roots of tlie auriculo-temporal nerve to the foramen spinosum of 
 the sphenoid bone. On entering the cranium it divides into two branches, anterior 
 and posterior. The anterior branch, the larger, crosses the great ala of the sphenoid, 
 and reaches the groove, or canal, in the anterior inferior angle of the parietal 
 bone; it then divides into two branches which spread out between the dura mater 
 and internal surface of the cranium, one passing upward over the parietal bone as 
 far as the vertex, and sending rami backward to the occipital bone, the other 
 passing front to the inner surface of the frontal bone. The posterior branch 
 crosses the squamous portion of the temporal, and on the inner surface of the 
 parietal bone divides into branches which supply the posterior part of the dura 
 mater and cranium. The branches of this vessel are distributed partly to the 
 dura mater, but chiefly to the bones; they anastomose with the arteries of the 
 opposite side, and with the anterior and posterior meningeal arteries. 
 
 The middle meningeal on entering the cranium gives off the following collateral 
 branches: 1. Numerous small vessels to the Gasserian ganglion, and to the dura 
 mater in this situation. 2. A branch, the petrosal branch {ramus petrosus super- 
 ficialis), which enters the hiatus Fallopii, supplies the facial nerve, and anasto- 
 moses with the styio-mastoid branch of the posterior auricular artery. 3. A 
 minute superior tympanic branch (a. tympanica superior), which runs in the canal 
 for the Tensor tympani muscle, and supplies this muscle and the lining mem- 
 brane of the canal. 4. Orbital branches, which pass through the sphenoidal fissure, 
 or through separate canals in the great wing of the sphenoid to anastomose 
 with the lachrymal or other branches of the ophthalmic artery. 5. Temporal 
 or anastomotic branches, which pass through foramina in the great wing of the 
 
614 THE BLOOD -VASCULAR SYSTEM 
 
 sphenoid bone and anastomose in the temporal fossa with the deep temporal 
 arteries. 
 
 Surgical Anatomy. — The middle meningeal is an artery of considerable surgical importance, 
 as it may be injured in fractures of the temporal region of the skull. The vessel may be ruptured 
 by traumatism, even though the skull escapes fracture. Rupture of the middle meningeal artery 
 will be followed by considerable hemorrhage between the bone and dura mater, which may cause 
 compression of the brain and require the operation of trephining for its relief. This artery 
 crosses the anterior inferior angle of the parietal bone at a point 1 ^ inches behind the external 
 angular process of the frontal bone, and If inches above the zygoma. From this point the ante- 
 rior branch passes upward and slightly backward to the sagittal suture, lying about § inch to 
 f inch behind the coronal suture. The posterior branch passes upward and backward over the 
 squamous portion of the temporal bone. In order to expose the artery as it lies in the groove in 
 the parietal bone, a semilunar incision, with its convexity upward, should be made, commencing 
 an inch behind the external angular process, and carried backward for two inches. The struc- 
 tures cut through are: (1) skin; (2) superficial fascia, with branches of the superficial temporal 
 vessels and nerves; (3) the fascia continued down from the aponeurosis of the Occipito-frontalis; 
 (4) the two layers of the temporal fascia; (5) the temporal muscle; (6) the deep temporal vessels; 
 (7) the pericranium. The bone is trephined, the clot removed, and the vessel secured by 
 ligatures, suture ligatures, or gauze packing. 
 
 The Small Meningeal Branch (ramus meningeus accessorius) is sometimes derived 
 from the preceding, usually from the internal maxillary. It enters the skull 
 through the foramen ovale, and supplies the Gasserian ganglion and dura mater. 
 
 The Mandibular, Inferior Alveolar or Inferior Dental Branch (a. alveolaris inferior) 
 descends with the inferior dental nerve to the foramen on the inner side of the 
 ramus of the jaw. It runs along the dental canal in the substance of the bone, 
 accompanied by the nerve, and opposite the first bicuspid tooth divides into two 
 branches, the incisor and mental ; the incisor branch is continued forward beneath 
 the incisor teeth as far as the symphysis, where it anastomoses with the artery 
 of the opposite side; the mental branch (a. mentalis) escapes with the nerve at the 
 mental foramen, supplies the structures composing the chin, and anastomoses 
 with the submental, inferior labial and inferior coronary arteries. Near its origin 
 the inferior dental artery gives off a lingual branch, which descends with the lingual 
 (gustatory) nerve and supplies the mucous membrane of the mouth. As the 
 inferior dental artery enters the foramen it gives off a mylo-hyoid branch {ramus 
 mylohyoideus) , which runs in the mylo-hyoid groove, and ramifies on the under 
 surface of the Mylo-hyoid muscle. The dental and incisor arteries during their 
 course through the substance of the bone give off a few twigs which are lost in 
 the cancellous tissue, and a series of branches which correspond in number to 
 the roots of the teeth: these enter the minute apertures at the extremities of the 
 fangs and supply the pulp of the teeth. 
 
 Branches of the Second or Pterygoid Portion (Fig. 398) : 
 
 Deep Temporal. Masseteric. 
 
 Pterygoid. Buccal. 
 
 These branches are distributed, as their names imply, to the muscles in the 
 maxillary region. 
 
 The Deep Temporal Branches, two in number, anterior (a. temporalis profunda 
 anterior) and posterior (a. temporalis profunda posterior), each occupy that part 
 of the temporal fossa indicated by its name. Ascending between the Temporal 
 muscle and pericranium, they supply that muscle and anastomose with the middle 
 temporal artery. The anterior branch communicates with the lachrymal artery 
 through small branches which perforate the malar bone and great wing of the 
 sphenoid. 
 
 The Pterygoid Branches (rami pterygoidei) , irregular in their number and 
 origin, supply the Pterygoid muscles. 
 
THE EXTERNAL CAROTID ARTERY 615 
 
 The Masseteric (a. masseterica) is a small branch which passes outward, above 
 the sigmoid notch of the lower jaw, to the deep surface of the Masseter muscle. 
 It supplies that muscle, and anastomoses with the masseteric branches of the 
 facial and with the transverse facial artery. 
 
 The Buccal (a. huccinatoria) is a small branch which runs obliquely forward 
 between the Internal pterygoid and the ramus of the jaw, to the outer surface of 
 the Buccinator, to which it is distributed, anastomosing with branches of the 
 facial artery. 
 
 Branches of the Third or Spheno -maxillary Portion (Fig. 398): 
 
 Superior Alveolar or Alveolar. Vidian. 
 
 Infraorbital. Pterygo-palatine. 
 
 Descending or Posterior Palatine. Naso- or Spheno-palatine. 
 
 The Superior Alveolar, Alveolar or Posterior Dental Branch (a. alveolaris superior 
 posterior) is given off from the internal maxillary by a common branch with the 
 infraorbital, and just as the trunk of the vessel is passing into the spheno-maxillary 
 fossa. Descending upon the tuberosity of the superior maxillary bone, it divides 
 into numerous branches, some of which enter the posterior dental canals, to supply 
 the upper molar and bicuspid teeth and the lining of the antrum, and others are 
 continued forward on the alveolar process to supply the gums of the upper jaw. 
 
 The Infraorbital (a. infraorbitalis) appears, from its direction, to be the con- 
 tinuation of the trunk of the internal maxillary. It arises from that vessel by a 
 •common trunk with the preceding branch, and runs along the infra-orbital 
 canal with the superior maxillary nerve, emerging upon the face at the infra- 
 orbital foramen, beneath the Levator labii superioris muscle. Whilst contained 
 in the canal, it gives off branches which ascend into the orbit, and assist 
 in supplyitig the Inferior rectus and Inferior oblique muscles and the lachrymal 
 gland. Other branches, anterior dental (aa. alveolares swperiores anteriores) , descend 
 through the anterior dental canals in the bone, to supply the mucous membrane of 
 the antrum and the front teeth of the upper jaw. On the face, some branches pass 
 upward to the inner angle of the orbit and the lachrymal sac, anastomosing with 
 the angular branch of the facial artery; other branches pass inward toward the 
 nose, anastomosing with the nasal branch of the ophthalmic; and other branches 
 •descend beneath the Levator labii superioris muscle, and anastomose with the 
 transverse facial and buccal arteries. 
 
 The four remaining branches arise from that portion of the internal maxillary 
 which is contained in the spheno-maxillary fossa. 
 
 The Descending or Posterior Palatine (a. palatina descendens) descends through 
 the posterior palatine canal with the anterior palatine branch of Meckel's ganglion, 
 and, emerging from the posterior palatine foramen, runs forward in a groove on 
 the inner side of the alveolar border of the hard palate to the anterior palatine 
 •canal, where the terminal branch of the artery passes upward through the fora- 
 men of Stenson to anastomose with the naso-palatine artery. Its branches are 
 distributed to the gums, the mucous membrane of the hard palate, and the 
 palatine glands. Whilst it is contained in the palatine canal it gives off branches 
 which descend in the accessory palatine canals to supply the soft palate and 
 tonsil, anastomosing with the ascending palatine artery. 
 
 Surgical Anatomy. — The position of the descending palatine artery on the hard palate 
 should be borne in mind in performing an operation for the closure of a cleft in the hard 
 palate, as the vessel is in danger of being wounded, and may give rise to formidable hemor- 
 rhage. In case it should be wounded it may be necessary to plug the posterior palatine 
 canal in order to arrest the bleeding. This artery may bleed furiously in the operation of 
 resection of the upper jaw. 
 
616 THE BLOOn -VASCULAR SYSTEM 
 
 The Vidian Branch (a. canalis pterygoidei) passes backward along the Vidian 
 canal with the Vidian nerve. It is distributed to the upper part of the pharynx 
 and Eustachian tube, sending a small branch into the tympanum, which anasto- 
 moses with the other tympanic arteries. 
 
 The Pterygo-palatine is a very small branch, which passes backward through 
 the pterygo-palatine canal with the pharyngeal nerve, and is distributed to the 
 upper part of the pharynx and Eustachian tube. 
 
 The Naso- or Spheno -palatine (a. sfheno'palatina) passes through the spheno- 
 palatine foramen into the cavity of the nose, at the back part of the superior 
 meatus, and divides into two branches: one internal, the naso-palatin^ or artery of 
 the septum, passes obliquely downward and forward along the septum nasi, supplies 
 the mucous membrane, and anastomoses in front with the terminal branch of the 
 descending palatine and the inferior artery of the septum, which is a branch 
 of the superior coronary. The external branches, two or three in number, supply 
 the mucous membrane covering the lateral wall of the nose, the antrum, and 
 the ethmoid and sphenoid cells. 
 
 SURGICAL ANATOMY OF THE TRIANGLES OF THE NECK 
 
 (Fig. 269). 
 
 The student having considered the relative anatomy of the large arteries of the 
 neck and their branches, and the relations they bear to the veins and nerves, should 
 now examine these structures collectively, as they present themselves in certain 
 regions of the neck, in each of which important operations are constantly being 
 performed. 
 
 The side of the neck presents a somewhat quadrilateral outline, limited, above^ 
 by the lower border of the body of the jaw, and an imaginary line extending from 
 the angle of the jaw to the mastoid process; below, by the prominent upper border 
 of the clavicle; in jront, by the median line of the neck; behind, by the anterior 
 margin of the Trapezius muscle. This space is subdivided into two large triangles 
 by the Sterno-mastoid muscle, which passes obliquely across the neck, from the 
 sternum and clavicle below to the mastoid process above. The triangular space 
 in front of this muscle is called the anterior triangle ; and that behind it, the poste- 
 rior triangle. 
 
 Anterior Triangle of the Neck. — The anterior triangle is bounded in front, 
 by an imaginary line extending from the chin to the sternum; behind, by the 
 anterior margin of the Sterno-mastoid; its base, directed upward, is formed by 
 the lower border of the body of the jaw and an imaginary line extending from 
 the angle of the jaw to the mastoid process; its apex is below, at the sternum. 
 This space is subdivided into three smaller triangles by the Digastric muscle 
 above and the anterior belly of the Omo-hyoid below. These smaller triangles 
 are named, from below upward, the inferior carotid, the superior carotid, and the 
 submaxillary triangle. 
 
 The Inferior Carotid Triangle or the Triangle of Necessity is bounded, in jront, 
 by the median line of the neck; behind, by the anterior margin of the Sterno- 
 mastoid ; above, by the anterior belly of the Omo-hyoid ; and is covered by the 
 integument, superficial fascia, Platysma, and deep fascia, ramifying between 
 which are some of the descending branches of the superficial cervical plexus. 
 Beneath these superficial structures are the Sterno-hyoid and Sterno-thyroid 
 muscles, which, together with the anterior margin of the Sterno-mastoid, conceal 
 the lower part of the common carotid artery.^ The floor of this triangle is formed 
 
 _> Therefore the common carotid artery and internal jugular vein are not, strictly speaking, contained in this 
 triangle, since they are covered by the Sterno-mastoid muscle, that is to say, lie behind the anterior border of 
 that muscle, which forms the posterior border of the triangle. But, as they lie very close to the structure* 
 which are really contained in the triangle, and whose position it is essential to remember in operating on thia 
 part of the artery, it has seemed expedient to study the relations of all these parts together. — Ed. of 15th 
 English edition. 
 
SURGICAL ANATOMY OF THE TRIANGLES OF THE NECK QYJ 
 
 by the Longiis colli muscle below and by the Scalenus anticus muscle above, between 
 which muscles the vertebral artery and vein will be found passing into the foramen 
 of the transverse process of the sixth cervical vertebra. A small portion of the origin 
 of the Rectus capitis anticus major may also be seen on the floor of the space. 
 
 The common carotid artery is enclosed within its sheath, together with the 
 internal jugular vein and pneumogastric nerve; the vein lying on the outer side 
 of the artery on the right side of the neck, but overlapping it below on the left side ; 
 the nerve lying between the artery and vein, on a plane posterior to both. In 
 front of the sheath are a few filaments descending from the loop of communica- 
 tion between the Descendens and communicans hypoglossi; behind the sheath 
 are seen the inferior thyroid artery, the recurrent laryngeal nerve, and the sym- 
 pathetic nerve; and on its inner side, the trachea, the thyroid gland — much more 
 prominent in the female than in the male — and the lower part of the larynx. By 
 cutting into the upper part of this space and slightly displacing the Sterno-mastoid 
 muscle the common carotid artery may be tied below the Omo-hyoid muscle. 
 
 The Superior Caxotid Triangle or the Triangle of Election is bounded, behind, 
 by the Sterno-mastoid; below, by the anterior belly of the Omo-hyoid; and 
 above, by the posterior belly of the Digastric muscle. It is covered by the 
 integument, superficial fascia, Platysma, and deep fascia, ramifying between 
 which are branches of the facial and superficial cervical nerves. Its floor is 
 formed by parts of the Thyro-hyoid and Hyo-glossus muscles, and the Inferior 
 and Middle constrictor muscles of the pharynx. This space, when dissected, 
 is seen to contain the upper part of the common carotid artery, which bifur- 
 cates opposite the upper border of the thyroid cartilage into the external and 
 internal carotid. These vessels are occasionally somewhat concealed from view 
 by the anterior margin of the Sterno-mastoid muscle, which overlaps them. 
 The external and internal carotid lie side by side, the external being the more 
 anterior of the two. The following branches of the external carotid are also 
 met with in this space: the superior thyroid, running forward and downward; the 
 lingual, directly forward; the facial, forward and upward; the occipital, back- 
 ward; and the ascending pharyngeal directly upward on the inner side of the 
 internal carotid. The veins met with are: the internal jugular, which lies on the 
 outer side of the common and internal carotid arteries, and veins corresponding to 
 the above-mentioned branches of the external carotid — viz., the superior thyroid, 
 the lingual, facial, ascending pharyngeal, and sometimes the occipital, all of 
 which accompany their corresponding arteries and terminate in the internal jugular. 
 The nerves in this space are the following: In front of the sheath of the common 
 carotid is the descendens hypoglossi. The hypoglossal nerve crosses both the 
 internal and external carotids above, curving round the occipital artery at its 
 origin. Within the sheath, between the artery and vein, and behind both, is the 
 pneumogastric nerve; behind the sheath, the sympathetic. On the outer side of 
 the vessels the spinal accessory nerve runs for a short distance before it pierces 
 the Sterno-mastoid muscle; and on the inner side of the external carotid, just 
 below the hyoid bone, may be seen the internal laryngeal nerve; and, still more 
 inferiorly, the external laryngeal nerve. The upper part of the larynx and lower 
 part of the pharynx are also found in the front part of this space. 
 
 The Submaxillary Triangle corresponds to the part of the neck immediately 
 beneath the body of the jaw. It is bounded, above, by the lower border of the 
 body of the jaw and a line drawn from its angle to the mastoid process; below, by 
 the posterior belly of the Digastric muscle and the Stylo-hyoid muscle; in jront, 
 by the anterior belly of the Digastric. It is covered V)y the integument, superficial 
 fascia, Platysma, and deep fascia, ramifying between which are branches of the 
 facial and ascending filaments of the superficial cervical nerves. Its floor is formed 
 by the Mylo-hyoid and Hyo-glossus muscles. This space contains, in front, the sub- 
 
618 THE BLOOD 'VASCULAR SYSTEM 
 
 maxillary gland, superficial to which is the facial vein, while imbedded in it are the 
 facial artery and its glandular branches; beneath this gland, on the surface of the 
 Mylo-hyoid muscle, are the submental artery and the mylo-hyoid artery and nerve. 
 The posterior part of this triangle is separated from the anterior part by the stylo- 
 maxillary ligament: it contains the external carotid artery, ascending deeply in 
 the substance of the parotid gland : this vessel here lies in front of, and superficial 
 to, the internal carotid, being crossed by the facial nerve, and gives off in its 
 course the posterior auricular, temporal, and internal maxillary branches: more 
 deeply are the internal carotid artery, the internal jugular vein, and the pneumo- 
 gastric nerve, separated from the external carotid by the Stylo-glossus and Stylo- 
 pharyngeus muscles and the glosso-pharyngeal nerve/ 
 
 Posterior Triangle of the Neck. — The posterior triangle is bounded, in front, 
 by the Sterno-mastoid muscle; behind, by the anterior margin of the Trapezius; 
 its base corresponds to the middle third of the clavicle; its apex, to the occiput. 
 The space is crossed, about an inch above the clavicle, by the posterior belly of 
 the Omo-hyoid, which divides it unequally into two, an upper or occipital and a 
 lower or subclavian triangle. 
 
 The Occipital Triangle, the larger division of the posterior triangle, is bounded, 
 in front, by the Sterno-mastoid; behind, by the Trapezius; below, by the Omo- 
 hyoid. Its floor is formed from above downward by the Splenius, Levator anguli 
 scapulae, and the Middle and posterior scaleni muscles. It is covered by the 
 integument, the Platysma below, the superficial and deep fasciae; the spinal 
 accessory nerve is directed obliquely across the space from the Sterno-mastoid, 
 which it pierces, to the under surface of the Trapezius; below, the descending 
 branches of the cervical plexus and the transversalis colli artery and vein cross the 
 space. A chain of lymphatic glands is also found running along the posterior 
 border of the Sterno-mastoid, from the mastoid process to the root of the neck. 
 
 The Subclavian Triangle, the smaller of the two posterior triangles, is bounded, 
 above, by the posterior belly of the Omo-hyoid ; below, by the clavicle, its base, 
 directed forward, being formed by the Sterno-mastoid. The size of the subclavian 
 triangle varies according to the extent of attachment of the clavicular portion of the 
 Sterno-mastoid and Trapezius muscles, and also according to the height at which 
 the Omo-hyoid crosses the neck above the clavicle. Its height also varies much 
 according to the position of the arm, being much diminished by raising the limb, 
 on account of the ascent of the clavicle, and increased by drawing the arm down- 
 ward, when that bone is depressed. This space is covered by the integument, 
 the Platysma, the superficial and deep fasciae, and crossed by the descending 
 branches of the cervical plexus. Just above the level of the clavicle the third 
 portion of the subclavian artery curves outward and downward from the outer 
 margin of the Scalenus anticus, across the first rib, to the axilla. Sometimes this 
 vessel rises as high as an inch and a half above the clavicle, or to any point inter- 
 mediate between this and its usual level. Occasionally it passes in front of the 
 Scalenus anticus or pierces the fibres of that muscle. The subclavian vein lies 
 behind the clavicle, and is usually not seen in this space; but it occasionally rises 
 as high up as the artery, and has even been seen to pass with that vessel behind 
 the Scalenus anticus. The brachial plexus of nerves lies above the artery, and 
 in close contact with it. Passing transversely behind the clavicle are the supra- 
 scapular vessels, and traversing its upper angle in the same direction, the trans- 
 versalis colli artery and vein. The external jugular vein runs vertically downward 
 behind the posterior border of the Sterno-mastoid muscle, to terminate in the 
 
 The same remark will apply to this triangle as was made about the inferior carotid triangle. The structures 
 enumerated as contamed m the back part of the space lie, strictly speaking, beneath the muscles which form 
 ine posterior boundary of the triangle; but as it is very important to bear in mind their close relation to the 
 parotid gland and its boundaries (on account of the frequency of surgical operations on this gland), all these 
 parts are spoken of together.— Ed. of 15th English edition 
 
THE INTERNAL CAROTID ARTERY 
 
 619 
 
 subclavian vein ; it receives the transverse cervical and suprascapular veins, which 
 occasionally form a plexus in front of the artery, and a small vein which crosses 
 the clavicle from the cephalic. The small nerve to the Subclavius muscle also 
 crosses this triangle about its middle. A lymphatic gland is also found in the space. 
 Its floor is formed by the first rib with the first digitation of the Serratus magnus. 
 
 The Internal Carotid Artery (A. Carotis Interna). 
 
 The internal carotid artery supplies the anterior part of the brain, the eye, 
 and its appendages, and sends branches to the forehead and nose. Its size 
 in the adult is equal to that of the external carotid, though in the child it is 
 larger than that vessel. It is remarkable for the number of curvatures that it 
 presents in different parts of its course. It occasionally has one or two flexures 
 
 Fig. 399. — The internal carotid and vertebral arteries. Right side. 
 
620 THE BLOOD -VASCULAR SYSTEM 
 
 near the base of the skull, whilst in its passage through the carotid canal and 
 along the side of the body of the sphenoid bone it describes a double curve 
 which resembles somewhat the letter S placed horizontally. These curvatures most 
 probably diminish the velocity of the current of blood, by increasing the extent of 
 surface over which it moves and adding to the impediment produced from friction. 
 
 In considering the course and relations of this vessel it may be conveniently 
 divided into four portions: the cervical, petrous, cavernous, and cerebral portions. 
 
 Cervical Portion. — This portion of the internal carotid commences at the 
 bifurcation of the common carotid, opposite the upper border of the thyroid 
 cartilage, and runs perpendicularly upward, in front of the transverse processes 
 of the three upper cervical vertebrae, to the carotid canal in the petrous portion 
 of the temporal bone. It is superficial at its commencement, being contained in the 
 superior carotid triangle, and lying on the same level as the external carotid, but 
 behind that artery overlapped by the Sterno-mastoid and covered by the deep 
 fascia, Platysma, and integument: it then passes beneath the parotid gland, being 
 crossed by the hypoglossal nerve, the Digastric and Stylo-hyoid muscles, and 
 the occipital and posterior auricular arteries. Higher up, it is separated from the 
 external carotid by the Stylo-glossus and Stylo-pharyng^us muscles, the glosso- 
 pharyngeal nerve, and pharyngeal branch of the pneumogastric. 
 
 Relations. — It is in relation, behind, with the Rectus capitis anticus major, the 
 superior cervical ganglion of the sympathetic, and superior laryngeal nerve ; exter- 
 nally, with the internal jugular vein and pneumogastric nerve, the nerve lying 
 on a plane posterior to the artery; internally, with the pharynx, tonsil, the superior 
 laryngeal nerve, and ascending pharyngeal artery. At the base of the skull the 
 glosso-pharyngeal, vagus, spinal accessory, and hypoglossal nerves lie between 
 the artery and the internal jugular vein. 
 
 Plan of the Relations of the Internal Carotid Artery in the Neck. 
 
 In front. 
 Skin, superficial and deep fasciae. 
 Platysma. 
 Sterno-mastoid. 
 
 Occipital and posterior auricular arteries. 
 Hypoglossal nerve. 
 Parotid gland. 
 
 Stylo-glossus and Stylo-pharyngeus muscles. 
 Glosso-pharyngeal nerve. 
 Pharyngeal branch of the pneumogastric. 
 
 Externally. f \ Internally. 
 
 Internal jugular vein. ( ^^^l^^ \ Pharynx. 
 
 Pneumogastric nerve. \ Artery. I Superior laryngeal nerve. 
 
 \ / Ascending pharyngeal artery. 
 
 ^- -^ Tonsil. 
 
 Behind. 
 Rectus capitis anticus major. 
 Sympathetic. 
 Superior laryngeal nerve. 
 
 Petrous Portion. — When the internal carotid artery enters the canal in the 
 petrous portion of the temporal bone, it first ascends a short distance, then curves 
 forward and inward, and again ascends as it leaves the canal to enter the cavity of 
 the skull between the lingula and petrosal process. In this canal the artery lies 
 at first in front of the cochlea and tympanum ; from the latter cavity it is separated 
 by a thin, bony lamella, which is cribriform in the young subject, and is often 
 absorbed in old age. Farther forward it is separated from the Gasserian ganglion 
 by a thin plate of bone, which forms the floor of the fossa for the ganglion and the 
 roof of the horizontal portion of the canal. Frequently this bony plate is more 
 
THE INTERNAL CAROTID ARTERY 621 
 
 or less deficient, and then the ganghon is separated from the artery by a fibrous 
 membrane. The artery is separated from the bony wall of the carotid canal by a 
 prolongation of dura mater, and is surrounded by a number of small veins and 
 by filaments of the carotid plexus, derived from the ascending branch of the 
 superior cervical ganglion of the sympathetic. 
 
 Cavernous Portion.— The internal carotid artery in this part of its course is 
 situated between the layers of the dura mater forming the cavernous sinus, but is 
 covered by the lining membrane of the sinus. It at first ascends to the posterior 
 clinoid process, then passes forward by the side of the body of the sphenoid bone, 
 and again curves upward on the inner side of the anterior clinoid process, and 
 perforates the dura mater, forming the roof of the sinus. In this part of its course 
 it is surrounded by filaments of the sympathetic nerve, and has in relation with it 
 externally the sixth nerve. 
 
 Cerebral Portion. — Having perforated the dura mater, on the inner side of the 
 anterior clinoid process, the internal carotid passes between the second and third 
 cranial nerves to the anterior perforated spot at the inner extremity of the fissure 
 of Sylvius, where it gives off its terminal or cerebral branches. This portion 
 of the artery has the optic nerve on its inner side, and the third nerve externally. 
 
 Peculiaxities. — The length of the internal carotid varies according to the length of the neck, 
 and also according to the point of bifurcation of the common carotid. Its origin sometimes 
 takes place from the arch of the aorta; in such rare instances this vessel has been found to be 
 placed nearer the middle line of the neck than the external carotid, as far upward as the larynx, 
 when the latter vessel crossed the internal carotid. The course of the vessel, instead of being 
 straight, may be very tortuous. A few instances are recorded in which this vessel was altogether 
 absent: in one of these the common carotid passed up the neck, and gave off the usual branches 
 of the external carotid, the cranial portion of the internal carotid being replaced by two branches 
 of the internal maxillary, which entered the skull through the foramen rotundum and the foramen 
 ovale and joined to form a single vessel. 
 
 Surgical Anatomy. — The cervical part of the internal carotid is very rarely wounded. Mr. 
 Cripps, in an interesting paper in the Medico-Chirurgical Transactions, compares the rareness 
 of a wound of the internal carotid with one of the external carotid or its branches. It is, however, 
 sometimes injured by a stab or gunshot wound in the neck, or even occasionally by a stab from 
 within the mouth, as when a person receives a thrust from the end of a parasol or falls down 
 with a tobacco-pipe in his mouth. It used to be believed that the internal carotid was occa- 
 sionally wounded in the removal of the tonsil. Such an accident cannot happen if the artery is 
 normally placed. The severe and sometimes fatal hemorrhage which has followed this opera- 
 tion in a few instances probably had as its source enlarged branches of the ascending pharyn- 
 geal, tonsillar, or ascending palatine arteries. Recently, however, Dr. Gwilym G. Davis, of 
 Philadelphia, demonstrated a specimen in which the internal carotid could have been wounded 
 by incision of the tonsil. The indications for ligature are wounds, when the vessel should be 
 exposed by a careful dissection and tied above and below the bleeding point; and aneurism, 
 which if non-traumatic may be treated by ligature of the common carotid, but if traumatic in 
 origin by exposing the sac and tying the vessel above and below. The incision for ligature of 
 the cervical portion of the internal carotid should be made along the anterior border of the 
 Sterno-mastoid, from the angle of the jaw to the upper border of the thyroid cartilage. The 
 superficial structures being divided and the Sterno-mastoid defined and drawn outward, the 
 cellular tissue must be carefully separated and the posterior belly of the Digastric muscle and 
 the hypoglossal nerve sought for as guides to the vessel. When the artery is found the external 
 carotid should be drawn inward and the Digastric muscles upward, and the aneurism needle 
 passed from without inward. 
 
 Branches. — The branches given off from the internal carotid artery are — 
 
 From the Petrous portion . . Tympanic (internal or deep). 
 
 [ Arterife Receptaculi. 
 From the Cavernous portion . . ] Anterior Meningeal. 
 
 From the Cerebral portion 
 
 Ophthalmic. 
 Anterior Cerebral. 
 Middle Cerebral. 
 Posterior Communicating. 
 Anterior Choroid. 
 
622 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 The cervical portion of the internal carotid gives off no branches. 
 
 The Tympanic (ramiis caroticotympanicus) is a small branch from the petrous 
 portion, which enters the cavity of the tympanum through a minute foramen in 
 the carotid canal, and anastomoses with the tympanic branch of the internal 
 maxillary, and with the stylo-mastoid artery. 
 
 The Arteriae Receptaculi are numerous small vessels, derived from the inter- 
 nal carotid in the cavernous sinus; they supply the pituitary body, the Gasserian 
 ganglion, and the walls of the cavernous and inferior petrosal sinuses. Some of 
 these branches anastomose with branches of the middle meningeal. 
 
 The Anterior Meningeal (a. meningea anterior) is a small branch which 
 passes over the lesser wing of the sphenoid to supply the dura mater of the ante- 
 rior fossa; it anastomoses with the meningeal branch from the posterior ethmoidal 
 artery. 
 
 The Ophthalmic Artery (a. ophthalmica) arises from the internal carotid, 
 just as that vessel is emerging from the cavernous sinus, on the inner side of the 
 anterior clinoid process, and enters the orbit through the optic foramen, below and 
 
 Nasal. Palpebral. 
 Frontal. 
 
 a-orbital. 
 
 Anterior ethmoidal. 
 
 Posterior ethmoidal. 
 
 Muscular. 
 
 Temporal branches 
 of lachrymal. 
 
 centralis retime. 
 
 Lachrymal. 
 
 OphthalmiC' 
 
 Internal carotid. 
 
 Fig. 400. — The ophthalmic artery and its branches, the roof of the orbit having been removed. 
 
 on the outer side of the optic nerve. It then passes over the nerve to the inner wall 
 of the orbit, and thence horizontally forward, beneath the lower border of the 
 Superior oblique muscle, to a point behind the internal angular process of the 
 frontal bone, where it divides into two terminal branches, the frontal and nasal 
 branches. As the artery crosses the optic nerve it is accompanied by the nasal 
 nerve, and is separated from the frontal nerve by the Rectus superior and 
 Levator palpebrse superioris muscles. 
 
 Branches. — The branches of this vessel may be divided into an orbital group, 
 which are distributed to the orbit, and surrounding parts, and an ocular group^ 
 which supply the muscles and globe of the eye: 
 
THE INTERNAL CAROTID ARTERY 623 
 
 Orbital Group. Ocular Group. 
 
 Lachrymal. Short CiUary. 
 
 Supraorbital. Long Ciliary. 
 
 Posterior Ethmoidal. Anterior Ciliary. 
 
 Anterior Ethmoidal. Arteria Centralis Retinae. 
 
 Internal Palpebral. Muscular. 
 Frontal. 
 Nasal. 
 
 The Lachrymal (a. lachrimalis) is one of the largest branches derived from the 
 ophthalmic, arising close to the optic foramen; not infrequently it is given off from 
 the ophthalmic artery before it enters the orbit. It accompanies the lachrymal nerve 
 along the upper border of the External rectus muscle, and is distributed to the 
 lachrymal gland. Its terminal branches, escaping from the gland, are distributed to 
 the eyelids and conjunctiva : of those supplying the eyelids, two are of considerable 
 size and are named the external palpebral ; they run inward in the upper and lower 
 lids respectively, and anastomose with the internal palpebral arteries, forming an 
 arterial circle in this situation. The lachrymal artery gives off one or two malar 
 branches, one of which passes' through a foramen in the malar bone, to reach the 
 temporal fossa, and anastomoses with the deep temporal arteries; the other appears 
 on the cheek through the malar foramen, and anastomoses with the transverse facial. 
 A branch, the recurrent, is also sent backward through the sphenoidal fissure to the 
 dura mater, which anastomoses with a branch of the middle meningeal artery. 
 
 Peculiarities. — The lachrymal artery is sometimes derived from one of the anterior branches 
 of the middle meningeal artery. 
 
 The Supraorbital Artery (a. supraorbitalis) arises from the ophthalmic as that 
 vessel is crossing over the optic nerve. Ascending so as to arise above all the muscles 
 of the orbit, it passes forward, with the supraorbital nerve, between the periosteum 
 and Levator palpebrae muscle; and, passing through the supraorbital foramen, 
 divides into a superficial and deep branch, which supply the integument, the 
 muscles, and the pericranium of the forehead, anastomosing with the frontal, the 
 anterior branch of the temporal, and the supraorbital artery of the opposite side. 
 This artery in the orbit supplies the Superior rectus and the Levator palpebral 
 muscles, and sends a branch inward, across the pulley of the Superior oblique 
 muscle, to supply the parts at the inner canthus. At the supraorbital foramen 
 it frequently transmits a branch to the diploe. 
 
 The Ethmoidal Branches are two in number — posterior (a. ethmoidalis posterior) 
 and anterior (a. ethmoidalis anterior). The former, which is the smaller, passes 
 through the posterior ethmoidal foramen, supplies the posterior ethmoidal cells, 
 and, entering the cranium, gives off a meningeal branch, which supplies the adja- 
 cent dura mater, and nasal branches which descend into the nose through aper- 
 tures in the cribriform plate, anastomosing with branches of the spheno-palatine. 
 The anterior ethmoidal artery accompanies the nasal nerve through the anterior 
 ethmoidal foramen, supplies the anterior ethmoidal cells and frontal sinuses, and, 
 entering the cranium, gives off a meningeal branch, which supplies the adjacent 
 dura mater and nasal branches, which descend into the nose, through the slit by 
 the side of the crista galli, and, running along the groove on the under surface of 
 the nasal bone, supply the skin of the nose. 
 
 The Internal Palpebral Arteries (aa. palpebrales mediales), two in number, supe- 
 rior and inferior, arise from the ophthalmic, opposite the pulley of the Superior 
 oblique muscle; they leave the orbit to encircle the eyelids near their free margin, 
 forming a superior tarsal arch (arcus tarseus superior) and an inferior tarsal arch {arcus 
 tarseus inferior), which lie between the Orbicularis muscle and the tarsal plates; 
 
624 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 the superior palpebral inosculating at the outer angle of the orbit with the orbital 
 branch of the temporal artery, and with the upper of the two external palpebral 
 branches from the lachrymal artery — the inferior palpebral inosculating, at the 
 outer angle of the orbit, with the lower of the two external palpebral branches 
 
 Fig. 401.— The arteries of the base of the brain. The right half of the cerebellum and pons have been removed. 
 N. B. — It will be noticed that the two anterior cerebral arteries have been drawn at a considerable distance from 
 «ach other : this makes the anterior communicating artery appear very much longer than it really is. 
 
 from the lachrymal and with the transverse facial artery, and at the inner side 
 of the lid with a branch from the angular artery. From this last anastomosis a 
 branch passes to the nasal duct, ramifying in its mucous membrane, as far as the 
 inferior meatus. 
 
THE INTERNAL CAROTID ARTERY 
 
 625 
 
 The Frontal Artery (a. frontalis), one of the terminal branches of the ophthal- 
 mic, passes from the orbit at its inner angle, and, ascending on the forehead, sup- 
 plies the integument, muscles, and pericranium, anastomosing with the supra- 
 orbital artery and with the frontal artery of the opposite side. 
 
 The Nasal Artery (a. dorsalis nasi), the other terminal branch of the ophthalmic, 
 emerges from the orbit above the tendo oculi, and, after giving a branch to the 
 upper part of the lachrymal sac, divides into two branches, one of which crosses 
 the root of the nose, the transverse nasal, and anastomoses with the angular artery; 
 the other, the dorsalis nasi, runs along the dorsum of the nose, supplies its outer 
 surface, and anastomoses with the artery of the opposite side and with the lateral 
 nasal branch of the facial. 
 
 Fissure of 
 Rolando 
 
 Fig. 402. — Vascular area of the upper surface of the cerebrum. I. The part supplied by the external and 
 inferior frontal artery. II. The part supplied by the ascending frontal. III. The part supplied by the ascending 
 parietal. IV. The part supplied by the parieto-sphenoidal artery. (After Duret.) 
 
 The Ciliary Arteries (a. ciliares) are divisible into three groups, the short, long, 
 and anterior. The short ciliary arteries {aa. ciliaris posteriores breves), from six 
 to twelve in number, arise from the ophthalmic or some of its branches; they sur- 
 round the optic nerve as they pass forward to the posterior part of the eyeball, 
 pierce the sclerotic coat around the entrance of the nerve, and supply the choroid 
 coat and ciliary processes. The long ciliary arteries (aa. ciliares posteriores longce), 
 two in number, pierce the posterior part of the sclerotic at some little distance from 
 the optic nerve, and run forward, along each side of the eyeball, between the 
 sclerotic and choroid, to the ciliary muscle, where they divide into two branches; 
 these form an arterial circle, the circulus major, around the circumference of the 
 iris, from which numerous radiating branches pass forward, in its substance, to 
 its free margin, where they form a second arterial circle, the circulus minor, around 
 its pupillary margin. The anterior ciliary arteries (aa. ciliares anteriores) are 
 
 40 
 
626 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 derived from the muscular branches; they pass to the front of the eyeball in com- 
 pany with the tendons of the Recti muscles, form a vascular zone beneath the 
 conjunctiva, and then pierces the sclerotic a short distance from the cornea and 
 terminate in the circulus major of the iris. 
 
 The Arteria Centralis Retinae is the first and one of the smallest branches of the 
 ophthalmic artery. It runs for a short distance within the dural sheath of the 
 optic nerve, but about half an inch behind the eyeball it pierces the optic nerve 
 obliquely, and runs forward in the centre of its substance, and enters the globe 
 of the eve through the porus opticus. Its mode of distribution will be described 
 in the account of the anatomy of the eye. 
 
 The Muscular Branches {rami musculares) , two in number, superior and inferior, 
 frequently spring from a common trunk. The superior, the smaller, often wanting, 
 supplies the Levator palpebrse, Superior rectus, and Superior oblique. The infe- 
 rior, more constant in its existence, passes forward, between the optic nerve and 
 the Inferior rectus muscle, and is distributed to the External, Internal, and 
 Inferior recti, and Inferior oblique. This vessel gives off most of the anterior 
 ciliary arteries. Additional muscular branches are given off from the lachrymal 
 and supraorbital arteries or from the ophthalmic itself. 
 
 Fissure of Rolando 
 
 Fig. 403. — Vascular area of the internal surface of the cerebrum. I. The part supplied by the anterior 
 internal frontal. II. The part supplied by the middle internal frontal. III. The part supplied by the posterior 
 internal frontal. IV. The part supplied by the posterior temporal. V. The part supplied by the occipital, both 
 terminal branches of the posterior cerebral. (After Duret.) 
 
 The Anterior Cerebral (a. cerebri anterior) arises from the internal carotid 
 at the inner extremity of the fissure of Sylvius. It passes forward and inward across 
 the anterior perforated space, above the optic nerve, to the commencement of the 
 great longitudinal fissure. Here it comes into close relationship with the anterior 
 cerebral artery of the opposite side, and the two vessels are connected together by 
 a short* anastomosing trunk, about two lines in length, the anterior communicating 
 artery. From this point the two vessels run side by side in the longitudinal fissure, 
 curve round the genu of the corpus callosum, and, turning backward, continue 
 along its upper surface to its posterior part, where they terminate by anastomosing 
 with the posterior cerebral arteries. 
 
 Branches. — In their course the anterior cerebral arteries give off the following 
 branches : 
 
 Antero-median ganglionic. Anterior internal frontal. 
 
 Inferior internal frontal. Middle internal frontal. 
 
 Posterior internal frontal. 
 
THE INTERNAL CAROTID ARTERY 
 
 627 
 
 The Antero-median Ganglionic is a group of small arteries which arise at the 
 commencement of the anterior cerebral artery ; they pierce the anterior perforated 
 space and lamina cinerea, and supply the head of the caudate nucleus. 
 
 The Inferior Internal Frontal Branches or the Internal Orbital Arteries, two or 
 three in number, are distributed to the orbital surface of the frontal lobe, where 
 they supply the olfactory lobe, gyrus rectus, and internal orbital convolution. 
 
 The Anterior Internal Frontal supplies a part of the marginal convolution, and 
 sends branches over the edge of the hemisphere to the superior and middle frontal 
 convolutions and upper part of the ascending frontal convolution. 
 
 The Middle Internal Frontal supplies the corpus callosum, the convolution of the 
 corpus callosum, the inner surface of the first frontal convolution, and the upper 
 part of the ascending frontal convolution. 
 
 Fig. 404. — Vascular area of the inferior surface of the cerebrum. I. The part supplied by the anterior tem- 
 poral from the posterior cerebral artery. II. The part supplied by the posterior temporal from the posterior 
 cerebral artery. III. The part supplied by the occipital from the posterior cerebral artery. (After Duret.) 
 
 The Posterior Internal Frontal supplies the lobus quadratus and adjacent outer 
 surface of the hemisphere. 
 
 The Anterior Communicating Artery (a. communicans anterior) is a short branch, 
 about two lines in length, but of moderate diameter, connecting together the two 
 anterior cerebral arteries across the longitudinal fissure. Sometimes this vessel is 
 wanting, the two arteries joining together to form a single trunk, which afterward 
 divides. Or the vessel may be wholly or partially divided into two; frequently it 
 is longer and smaller than usual. It gives off some of the antero-median gan- 
 glionic group of vessels, which are, however, principally derived from the anterior 
 cerebral. 
 
 The Middle Cerebral Artery (a. cerebri media) (Fig. 405), the largest branch 
 of the internal carotid, passes obliquely outward along the fissure of Sylvius, and 
 opposite the island of Reil divides into its terminal branches. 
 
628 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 Branches. — The branches of the middle cerebral artery are — 
 
 Antero-lateral ganglionic. 
 Inferior external frontal. 
 
 Parieto-tem poral . 
 
 Ascending frontal. 
 Ascending parietal. 
 
 The Antero-lateral Ganglionic Branches are a group of small arteries which arise 
 at the commencement of the middle cerebral artery; they pierce the anterior 
 perforated space and supply the greater part of the caudate nucleus, the lenticular 
 nucleus, the internal capsule, and a part of the optic thalamus. One artery of this 
 group (one of the lenticulo-striate arteries) is of larger size than the rest, and is of 
 special importance, as being the artery in the brain most frequently ruptured; it 
 has been termed by Charcot the artery of cerebral hemorrhage. It passes up between 
 the lenticular nucleus and the external capsule, and ultimately ends in the caudate 
 nucleus. 
 
 FISSURE OP 
 ROLANDO. 
 / 
 
 Antero-lateraV 
 Ganglionic or Per- 
 forating Branches. 
 
 Middle Cerebral 
 Artery. 
 Fig. 405. — The distribution of the middle cerebral artery. 
 
 (After Charcot.) 
 
 The Inferior External Frontal supplies the third or inferior frontal convolution, 
 Broca's convolution, and the outer part of the orbital surface of the frontal lobe. 
 
 The Ascending Frontal supplies the ascending frontal convolution. 
 
 The Ascending Parietal supplies the ascending parietal convolution and the 
 lower part of the superior parietal convolution. 
 
 The Parieto-temporal or Parieto-sphenoidal supplies the supramarginal, the 
 superior, and part of the middle temporal convolutions, and the angular gyrus. 
 It sends branches to the temporal lobe. 
 
 The Posterior Communicating Artery (a. communicans posterior) arises 
 from the back part of the internal carotid, runs directly backward, and anasto- 
 moses with the posterior cerebral, a branch of the basilar. This artery varies 
 considerably in size, being sometimes small, and occasionally so large that the 
 posterior cerebral may be considered as arising from the internal carotid rather 
 than from the basilar. It is frequently larger on one side than on the other side. 
 From the posterior half of this vessel are given off a number of small branches, 
 the postero-median ganglionic branches, which, with similar vessels from the pos- 
 terior cerebral, pierce the posterior perforated space and supply the internal sur- 
 faces of the optic thalami and the walls of the third ventricle. 
 
 The Anterior Choroid (a. chorioidea) is a small but constant branch which 
 arises from the back part of the internal carotid, near the posterior communicating 
 artery. Passing backward and outward between the temporal lobe and the crus 
 
THE BLOOD-VESSELS OF THE BRAIN 
 
 629 
 
 cerebri, it enters the descending horn of the lateral ventricle through the trans- 
 verse fissure and ends in the choroid plexus. It is distributed to the hippocampus 
 major, corpus fimbriatum, velum interpositum, and choroid plexus. 
 
 THE BLOOD-VESSELS OF THE BRAIN. 
 
 Recent investigations have tended to show that the mode of distribution of 
 the vessels of the brain has an important bearing upon a considerable number of 
 the anatomical lesions of which this part of the nervous system may be the seat; 
 it therefore becomes important to consider a little more in detail the way in which 
 the cerebral vessels are distributed. 
 
 The cerebral arteries are derived from the internal carotid and the vertebral, 
 which at the base of the brain form a remarkable anastomosis known as the circle 
 
 —~~' Anterior cerebral artery. 
 
 I InterndC'carotid artery. 
 
 Middle ch'ebral artery. 
 
 /Posterior cef'ehral artery. 
 
 Fig. 406. — Diagram of the arterial circulation at the base of the brain. I. Antero-median group of ganglionic 
 branches. II. Postero-median group. III. Right and left antero-lateral group. IV. Right and left postero- 
 lateral group. The dotted line shows the limit of the ganglionic circle. (After Charcot.) 
 
 of Willis {circulus arteriosus \Willisi\)- The tortuosity of the constituent vessels 
 of the anastomosis lessens the impact of the circulation and saves the brain from 
 damage. The outline of the vessels forming the so-called circle is said by Sappey 
 to be hexagonal, and by Testut to be heptagonal. The circle of Willis is formed 
 in front by the anterior cerebral arteries, branches of the internal carotid, which 
 are connected together by the anterior communicating; behind by the two posterior 
 cerebrals, branches of the basilar which are connected on each side to the internal 
 carotid by the posterior communicating (Fig. 401). The parts of the brain 
 included within this arterial circle are the lamina cinerea, the commissure of the 
 optic nerves, the infundibulum, the tuber cinereum, the corpora albicantia, and 
 the posterior perforated space. This arrangement of the vessels of the circle of 
 Willis is not invariable; according to Windle it is maintained in little more than 
 half the recorded cases. In the other cases there are various anomalies. 
 
630 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 From the circle of Willis arise the three trunks which together supply each 
 cerebral hemisphere. From its anterior part proceed the two anterior cerebrals, 
 from its antero-lateral part the middle cerebrals, and from its posterior part the 
 posterior cerebrals. Each of these principal arteries gives origin to two very 
 different systems of secondary vessels. One of these systems has been named the 
 central ganglionic system, and the vessels belonging to it supply the central ganglia 
 of the brain; the other has been named the cortical arterial system, and its vessels 
 ramify in the pia mater and supply the cortex and subjacent medullary matter. 
 These two systems, though they have a common origin, do not communicate at any 
 point of their peripheral distribution, and are entirely independent of each other. 
 Though some of the arteries of the cortical system approach, at their terminations, 
 the regions supplied by the central ganglionic system, no communication between 
 the two sets of vessels takes place, and there is between the parts supplied by the 
 two systems a borderland of diminished nutritive activity, where, it is said, 
 softening is especially liable to occur in the brains of old people. 
 
 The Central Ganglionic System. — All the vessels belonging to this system 
 are given off from the circle of Willis or from the vessels immediately after their 
 origin from it, so that if a circle is drawn at a distance of about an inch from the 
 circle of Willis, it will include the origin of all the arteries belonging to this system 
 (Fig. 406). The vessels of this system form six principal groups: (I.) the antero- 
 median group, derived from the anterior cerebrals and anterior communicating; 
 (II.) the postero-median group, from the posterior cerebrals and posterior communi- 
 cating; (III.) the right and left antero-lateral group, from the middle cerebrals; and 
 (IV.) the right and left postero-lateral group, from the posterior cerebrals, after they 
 have wound round the crura cerebri. The vessels belonging to this system are 
 
 Fig. 407. — Distribution of the cortical arteries. 1. Medullary arteries. 1'. Group of medullary arteries in 
 the sulcus between two adjacent convolutions. 1". Arteries situated among the short association fibres. 2,2. 
 Cortical arteries, a. Capillary network with fairly wide meshes, situated beneath the pia mater, b. Net- 
 work with more compact, polygonal meshes, situated in the cortex. C. Transitional network with wider 
 meshes, a. Capillary network in the white matter. (After Charcot.) 
 
 larger than those of the cortical system, and are what Cohnheim has termed 
 terminal arteries ; that is to say, vessels which from their origin to their termination 
 neither supply nor receive any anastomotic branches, so that by one of the small 
 
THE SUBCLAVIAN ARTERY 631 
 
 vessels only a limited area of the central ganglia can be injected; and the injection 
 cannot be driven beyond the area of the part supplied by the particular vessel which 
 is the subject of the experiment. 
 
 The Cortical Arterial System. — The vessels forming this system are the ter- 
 minal branches of the anterior, middle, and posterior cerebral arteries, described 
 above. These vessels divide and ramify in the substance of the pia mater, and give 
 off nutrient arteries which penetrate the cortex perpendicularly. These nutrient 
 vessels are divisible into two classes — the long and short. The long — or, as they 
 are sometimes called, the medullary — arteries pass through the gray matter to pene- 
 trate the centrum ovale to the depth of about an inch and a half, without intercom- 
 municating otherwise than by very fine capillaries, and thus constitute so many 
 independent small systems. The short vessels are confined to the cortex, where 
 they form with the long vessels a compact network in the middle zone of the gray 
 matter, the outer and inner zones being sparingly supplied with blood (Fig. 407). 
 The vessels of the cortical arterial system are not so strictly terminal as those of the 
 central ganglionic system, but they approach this type very closely, so that injec- 
 tion of one area from the vessel of another area, though it may be possible, is fre- 
 quently very difficult, and is only effected through vessels of small calibre. As a 
 result of this, oljstruction of one of the main branches or its divisions may have 
 the effect of producing softening in a very limited area of the cortex.^ 
 
 ARTERIES OF THE UPPER EXTREMITY. 
 
 The artery which supplies the upper extremity continues as a single trunk 
 from its commencement down to the elbow, but different portions of it have 
 received different names according to the region through which it passes. That 
 part of the vessel which extends from its origin to the outer border of the first 
 rib is termed the subclavian artery ; beyond this point to the lower border of the 
 axilla it is termed the axillary artery; and from the lower margin of the axillary space 
 to the bend of the elbow it is termed the brachial artery; here the single trunk 
 terminates by dividing into two branches, the radial and ulnar — an arrangement 
 precisely similar to what occurs in the lower limb. 
 
 THE SUBCLAVIAN ARTERY (A. SUBCLAVIA) (Fig. 408). 
 
 The subclavian artery on the right side arises from the innominate artery 
 opposite the right sterno-clavicular articulation; on the left side it arises from 
 the arch of the aorta. It follows, therefore, that these two vessels must, in the first 
 part of their course, differ in their length, their direction, and their relation with 
 neighboring parts. 
 
 In order to facilitate the description of these vessels, more especially from a 
 surgical point of view, each subclavian artery has been divided into three parts. 
 The first portion, on the right side, passes upward and outward from the origin 
 of the vessel to the inner border of the Scalenus anticus. On the left side it ascends 
 nearly vertically, to gain the inner border of that muscle. The second part passes 
 outward, behind the Scalenus anticus; and the third part passes from the outer 
 margin of that muscle, beneath the clavicle, to the outer border of the first rib, 
 where it becomes the axillary artery. The first portion of these two vessels differs 
 so much in its course and in its relations with neighboring parts that it will be 
 described separately. The second and third parts are alike on the two sides. 
 
 ' The student who desires further information on this subject is referred to Charcot's Localization of Cerebral 
 and Spinal Diseases, p. 42 et seq., whence the facts above given have been principally derived. — Ed. of 15th 
 English edition. 
 
632 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 First Part of the Right Subclavian Artery (Figs. 389, 390, 392, 408). 
 
 On the right side the subclavian artery arises from the arteria innominata, oppo- 
 site the upper part of the right sterno-clavicular articulation, and passes upward 
 and outward to the inner margin of the Scalenus anticus muscle (Figs. 389, 390, 
 and 408) . In this part of its course it ascends a little above the clavicle, the extent 
 to which it does so varying in different cases. 
 
 Phrenic nerve. 
 
 Vertebral artery. 
 
 Inferior thyroid artery. 
 
 Supra-scapular 
 artery 
 Supra- 
 
 scapHlar\ ^i^ ^- 
 
 eumo- 
 gastric 
 nerve. 
 
 Subclavian 
 
 artery. 
 ^External jugu- 
 lar vein. 
 Eight innomi- 
 nate vein. 
 Jnnomi- 
 
 II life artery. 
 
 \ 
 
 Fig. 408.- 
 
 ' Profunda artery. 
 ■ Musculo-spiral nerve. 
 
 -The subclavian artery, showing its relations. (From a preparation in the Museum of the Royal 
 College of Surgeons of England.) 
 
 Relations. — It is covered, m front,hy the integument, superficial fascia, Platysma^ 
 deep fascia, the clavicular origin of the Sterno-mastoid, the Sterno-hyoid, and 
 Sterno-thyroid muscles, and a second layer of deep fascia. It is crossed by the 
 internal jugular and vertebral veins, and by the pneumogastric nerve and the 
 cardiac branches of the sympathetic nerve. A loop of the sympathetic nerve 
 itself also crosses the artery, forming a ring around the vessels. The anterior 
 jugular vein passes outward in front of the artery but is not in contact with it, 
 being separated from it by the Sterno-hyoid and Sterno-thyroid muscles. Below 
 and behind the artery is the pleura, which separates it from the apex of the lung; 
 behind is the cord of the sympathetic nerve; the recurrent laryngeal nerve winds 
 round the lower and back part of the vessel. 
 
THE SUBCLAVIAN ARTERY 633 
 
 Plan of the Relations of First Portion of the Right Subclavian Artery. 
 
 In front. 
 Skin, superficial fascia. 
 Platysma, deep fascia. 
 Clavicular origin of Sterno-mastoid. 
 Sterno-hyoid and Sterno-thyroid. 
 
 Anterior jugular, Internal jugular, and vertebral veins. 
 Pneumogastric and cardiac nerves. 
 Loop from the sympathetic. 
 
 Beneath. 
 Pleura. 
 Recurrent laryngeal nerve. 
 
 Behind. 
 Recurrent laryngeal nerve. 
 Sympathetic. 
 Pleura and apex of lung. 
 
 First Part of the Left Subclavian Artery (Figs. 388, 389). 
 
 The left subclavian artery arises from the end of the arch of the aorta, opposite 
 the fourth dorsal vertebra, and ascends nearly vertically to the inner margin of 
 the Scalenus anticus muscle. This part of the vessel is, therefore, longer than the 
 right, is situated deeply in the cavity of the chest, and is directed nearly vertically 
 upward, instead of arching outward like the vessel of the opposite side. 
 
 Relations. — It is in relation, in front, with the pneumogastric, cardiac, and phrenic 
 nerves, which lie parallel with it, the left carotid artery, left internal jugular 
 and vertebral veins, and the commencement of the left innominate vein and is 
 covered by the Sterno-thyroid, Sterno-hyoid, and Sterno-mastoid muscles; behind, 
 it is in relation with the oesophagus, thoracic duct, inferior cervical ganglion of the 
 sympathetic, and Longus colli muscle; higher up, however, the oesophagus and 
 thoracic duct lie to its right side; the latter ultimately arching over the vessel to 
 join the angle of union between the subclavian and internal jugular veins. To 
 its inner side are the oesophagus, trachea, and thoracic duct; to its outer side, the 
 left pleura and lung. 
 
 Plan of the Relations of First Portion of the Left Subclavian Artery. 
 
 In front. 
 Pneumogastric, cardiac, and phrenic nerves. 
 Left carotid artery. 
 Thoracic duct. 
 
 Left internal jugular, vertebral, and innominate veins. 
 Sterno-thyroid, Sterno-hyoid, and Sterno-mastoid muscles. 
 
 Inner side. / \ Outer side. 
 
 Trachea. / „ .i^^ft \ Pleura and left lung, 
 
 (lisophagus. 
 Thoracic duct. 
 
 Behind. 
 (Esophagus and thoracic duct. 
 Inferior cervical ganglion of sympathetic. 
 Longus colli. 
 
 Second and Third Parts of the Subclavian Artery (Figs. 392, 408). 
 
 The Second Portion of the Subclavian Artery lies behind the Scalenus anticus 
 muscle; it is very short, and forms the highest part of the arch described by that 
 vessel. 
 
634 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 Relations. — It is covered, in front, by the skin, superficial' fascia, Platysma, 
 deep cervical fascia, the Sterno-mastoid and the Scalenus anticus muscles. On 
 the right side the phrenic nerve is separated from the second part of the artery by 
 the Scalenus anticus muscle, while on the left side the nerve crosses the first part 
 of the artery immediately to the inner edge of the muscle. Behind, it is in rela- 
 tion with the pleura and the Scalenus medius muscle. Above, with the brachial 
 plexus of nerves. Below, with the pleura. The subclavian vein lies below and 
 in front of the artery, separated from it by the Scalenus anticus muscle. 
 
 Plan of the Relations of Second Portion of Subclavian Artery. 
 
 In front. 
 Skin and superficial fascia. 
 Platysma and deep cervical fascia. 
 Sterno-mastoid. 
 Phrenic nerve. 
 Scalenus anticus. 
 Subclavian vein. 
 
 Above. I Artery!''' ] Below. 
 
 Brachial plexus. 1 p^^a. J Pleura. 
 
 Behind. 
 Pleura and Middle Scalenus. 
 
 The Third Portion of the Subclavian Artery passes downward and outward 
 from the outer margin of the Scalenus anticus muscle to the outer border of the 
 first rib, where it becomes the axillary artery. This portion of the vessel is the 
 most superficial, and is contained in the subclavian triangle (see page 618). 
 
 Relations. — It is covered, in front, by the skin, the superficial fascia, the Platysma 
 the descending clavicular branches of the cervical plexus, and the deep cervical 
 fascia; by the clavicle, the Subclavius muscle, the suprascapular artery and 
 vein, and the transverse cervical vein; the nerve to the Subclavius muscle passes 
 vertically downward in front of the artery. The external jugular vein crosses 
 the artery at its inner side, and receives the suprascapular and transverse cervical 
 veins, which frequently form a plexus in front of it. The subclavian vein is 
 below and in front of the artery, lying close behind the clavicle. Behind, it lies on 
 the Middle scalenus muscle and the lowest cord of the brachial plexus, formed 
 by the union of the last cervical and first dorsal nerves. Above it, and to its 
 outer side, is the brachial plexus and Omo-hyoid muscle. Below, it rests on the 
 upper surface of the first rib. 
 
 Plan of the Relations of Third Portion of Subclavian Artery. 
 
 In front. 
 Skin and superficial fascia. 
 Platysma and deep cervical fascia. 
 
 Descending branches of cervical plexus. Nerve to Subclavius muscle. 
 Subclavius muscle, suprascapular artery, and vein. 
 The external jugular and transverse cervical veins. 
 The clavicle. 
 
 . , / Subclavian \ „ , 
 
 Above. I Artery. ] BelOW. 
 
 Brachial plexus. I portion. / First rib. 
 
 Omo-hyoid. 
 
 Behind. 
 Scalenus medius. 
 Lower cord of brachial plexus. 
 
THE SUBCLAVIAN ARTERY 635 
 
 Peculiarities. — The subclavian arteries vary in their origin, their course, and the height to 
 ■which they rise in the neck. 
 
 The origin of the right subclavian from the innominate takes place, in some cases, above the 
 sterno-clavicular articulation, and occasionally, but less frequently, in the cavity of the thorax, 
 below that point. Or the artery may arise as a separate trunk from the arch of the aorta. In 
 such cases it may be either the first, second, third, or even the last branch derived from that 
 vessel ; in the majority of cases it is the first or last, rarely the second or third. When it is the first 
 branch, it occupies the ordinary position of the innominate artery; when the second or third, it 
 gains its usual position by passing behind the right carotid; and when the last branch, it arises 
 from the left extremity of the arch, at its upper or back part, and passes obliquely toward the 
 right side, usually behind the trachea, oesophagus, and right carotid, sometimes between the 
 <Esophagus and trachea to the upper border of the first rib, whence it follows its ordinary course. 
 In very rare instances this vessel arises from the thoracic aorta, as low down as the fourth 
 dorsal vertebra. Occasionally it perforates the Scalenus anticus muscle; more rarely it passes 
 in front of that muscle. Sometimes the subclavian vein passes with the artery behind the 
 Scalenus anticus muscle. The artery may ascend as high as an inch and a half above the 
 clavicle or any intermediate point between this and the upper border of the bone, the right 
 subclavian usually ascending higher than the left. 
 
 The left subclavian is occasionally joined at its origin with the left carotid. 
 
 Surface Marking. — The course of the subclavian artery in the neck may be mapped out 
 by describing a curve, with its convexity upward at the base of the posterior triangle. The inner 
 •end of this curve corresponds to the sterno-clavicular joint, the outer end of the centre of the 
 lower border of the clavicle. The curve is to be drawn with such an amount of convexity that 
 its mid-point reaches half an inch above the upper border of the clavicle. The left subclavian 
 artery is more deeply placed than the right in the first part of its course, and, as a rule, does not 
 reach quite as high a level in the neck. It should be borne in mind that the posterior border of 
 the Sterno-mastoid muscle corresponds to the outer border of the Scalenus anticus muscle, so 
 that the third portion of the artery, that part most accessible for operation, lies immediately 
 external to the posterior border of the Sterno-mastoid muscle. 
 
 Surgical Anatomy. — The relations of the subclavian arteries of the two sides having been 
 examined, the student should direct his attention to a consideration of the best position in which 
 compression of the vessel may be effected, or in what situation a ligature may be best applied in 
 cases of aneurism or wound. 
 
 Compression of the subclavian artery is required in cases of operations about the shoulder, 
 in the axilla, or at the upper part of the arm; and the student will observe that there is only 
 ■one situation in which it can be effectually applied — viz., where the artery passes across the 
 upper surface of the first rib. In order to compress the vessel in this situation, the shoulder 
 should be depressed, and the surgeon, grasping the side of the neck, should press with his thumb 
 in the angle formed by the posterior border of the Sterno-mastoid with the upper border of 
 the clavicle, downward, backward, and inward against the rib; if from any cause the shoulder 
 cannot be sufficiently depressed, pressure may be made from before backward, so as to compress 
 the artery against the Scalenus medius muscle and the transverse process of the seventh cervical 
 vertebra. In appropriate cases, a preliminary incision may be made through the cervical 
 fascia, and the finger may be pressed down directly upon the artery. 
 
 Ligature of the subclavian artery may be required in cases of wounds or of aneurism in 
 the axilla, or in cases of aneurism on the cardiac side of the point of ligature; and the third part 
 •of the artery is that which is most favorable for an operation, on account of its being compara- 
 tively superficial and most remote from the origin of the large branches. In those cases where 
 the clavicle is not displaced, this operation may be performed with comparative facility; but 
 where the clavicle is pushed up by a large aneurismal tumor in the axilla the artery is placed at 
 a great depth from the surface, which materially increases the difficulty of the operation. Under 
 these circumstances it becomes a matter of importance to consider the height to which this 
 vessel reaches above the bone. In ordinary cases its arch is about half an inch above the clavicle, 
 occasionally it is as high as an inch and a half, and sometimes so low as to be on a level with 
 the upper border of the clavicle. If the clavicle is displaced, these variations will necessarily 
 make the operation more or less difficult according as the vessel is more or less accessible. 
 
 The chief points in the operation of tying the third portion of the subclavian artery are as 
 follows: The patient being placed on a table in the supine position, with the head drawn over to 
 the opposite side and the shoulder depressed as much as possible, the integument should be 
 drawn downward over the clavicle, and an incision made through it, upon that bone, from the 
 anterior border of the Trapezius to the posterior border of the Sterno-mastoid, to which may be 
 added a short vertical incision meeting the inner end of the preceding. The object in drawing 
 the skin downward is to avoid any risk of wounding the external jugular vein, for as it perforates 
 the deep fascia above the clavicle, it cannot be drawn downward with the skin. The soft parts 
 should now be allowed to glide up, and the cervical fascia should be divided upon a director, 
 and if the interval between the Trapezius and Sterno-mastoid muscles be insufficient for the per- 
 
636 THE BLOOD -VASCULAR SYSTEM 
 
 formance of the operation, a portion of one or both may be divided. The external jugular vein 
 will now be seen toward the inner side of the wound : this and the suprascapular and transverse 
 cervical veins, which terminate in it, should be held aside. If the external jugular vein is at all 
 in the way and exposed to injury, it should be tied in two places and divided. The suprascapu- 
 lar artery should be avoided, and the Omo-hyoid muscle held aside if necessary. In the space 
 beneath this muscle careful search must be made for the vessel : a deep layer of fascia and some 
 connective tissue having been divided carefully, the outer margin of the Scalenus anticus muscle 
 must be felt for, and, the finger being guided by it to the first rib, the pulsation of the subcla- 
 vian artery will be felt as it passes over the rib. The sheath of the vessels having been opened, 
 the aneurism needle may then be passed around the artery from above downward and inward, so 
 as to avoid including any of the branches of the brachial plexus. If the clavicle is so raised by 
 the tumor that the application of the ligature cannot be effected in this situation, the artery may 
 be tied above the first rib, or even behind the Scalenus anticus muscle; the difficulties of the 
 operation in such a case will be materially increased, on account of the greater depth of the artery 
 and the alteration in position of the surrounding parts. 
 
 The second part of the subclavian artery, from being that portion which rises highest in 
 the neck, has been considered favorable for the application of the ligature when it is difficult to 
 tie the artery in the third part of its course. There are, however, many objections to the opera- 
 tion in this situation. It is necessary to divide the Scalenus anticus muscle, upon which lies 
 the phrenic nerve, and at the inner side of which is situated the internal jugular vein; and a 
 wound of either of these structures might lead to the most dangerous consequences. Again, 
 the artery is in contact, below, with the pleura, which must also be avoided; and, lastly, the 
 proximity of so many of its large branches arising internal to this point must be a still further 
 objection to the operation. In cases, however, where the sac of an axillary aneurism encroaches 
 on the neck, it may be necessary to divide the outer half or two-thirds of the Scalenus anticus 
 muscle, so as to place the ligature on the vessel at a greater distance from the sac. The opera- 
 tion is performed exactly in the same way as a ligature of the third portion, until the Scalenus 
 anticus is exposed, when it is to be divided on a director (never to a greater extent than its outer 
 two-thirds), and it immediately retracts. The operation is therefore merely an extension of 
 ligature of the third portion of the vessel. 
 
 In those cases of aneurism of the axillary or subclavian artery in which the aneurism 
 encroaches upon the outer portion of the Scalenus muscle to such an extent that a ligature 
 cannot be applied in that situation, it may be deemed advisable, as a last resource, to tie the 
 first portion of the subclavian artery. On the left side this operation has been regarded as 
 almost impracticable; the great depth of the artery from the surface, its intimate relation 
 with the pleura, and its close proximity to the thoracic duct and to so many important veins 
 and nerves, present a series of difficulties which it is very difficult to overcome. Nevertheless, 
 Professor Halsted and Schumpert have each tied successfully the first portion of the left sub- 
 clavian for aneurism. J. K. Rodgers, of New York, also did it successfully. On the right 
 side the operation is practicable, and has been performed. Dr. Nassau, of Philadelphia, suc- 
 cessfully ligated the first part of the right subclavian. The main objection to the operation 
 in this situation is the smallness of the interval which usually exists between the com- 
 mencement of the vessel and the origin of the nearest branch. The operation may be per- 
 formed in the following manner: The patient being placed on the table in the supine position 
 with the neck extended, an incision should be made along the upper border of the inner part 
 of the clavicle, and a second along the inner border of the Sterno-mastoid, meeting the 
 former at an angle. The attachment of both heads of the Sterno-mastoid must be divided 
 on a director and turned outward; a few small arteries and veins, and occasionally the 
 anterior jugular vein, must be avoided, or, if necessary, ligatured in two places and divided, 
 and the Sterno-hyoid and Sterno-thyroid muscles are to be divided in the same manner as the 
 preceding muscle. After tearing through the deep fascia with the finger-nail, the internal jugular 
 vein will be seen crossing the subclavian artery; this should be pressed aside and the artery 
 secured by passing the needle from below upward, by which the pleura is more effectually 
 avoided. The exact position of the vagus, the recurrent laryngeal, the phrenic and sympa- 
 thetic nerves should be remembered, and the ligature should be applied near the origin of the 
 vertebral, in order to afford as much room as possible for the formation of a coagulum 
 between the ligature and the orgin of the vessel. It should be remembered that the right sub- 
 clavian artery is occasionally deeply placed in the first part of its course when it arises from 
 the left side of the aortic arch, and passes in such cases behind the oesophagus or between it 
 and the trachea. 
 
 Collateral Circulation. — After ligature of the third part of the subclavian artery the col- 
 lateral circulation is mainly established by three sets of vessels, thus described in a dissection: 
 
 "1. A posterior set, consisting of the suprascapular and posterior scapular branches of the 
 subclavian, anastomosing with the subscapular from the axillary. 
 
 "2. An internal set produced by the connection of the internal mammary on the one hand, 
 with the superior and long thoracic arteries, and the branches from the subscapular on the other. 
 
THE SUBCLAVIAN ARTERY 637 
 
 " 3. A middle or axillary set, which consisted of a number of small vessels derived from branches 
 of the subclavian, above, and, passing through the axilla, terminated either in the main trunk 
 or some of the branches of the axillary below. This last set presented most conspicuously the 
 peculiar character of the newly formed or, rather, dilated arteries, being excessively tortuous, 
 and forming a complete plexus. 
 
 "The chief agent in the restoration of the axillary artery below the tumor was the subscapular 
 artery, which communicated most freely with the internal mammary, suprascapular, and pos- 
 terior scapular branches of the subclavian, from all of which is received so great an influx of 
 blood as to dilate it to three times its natural size."' 
 
 When a ligature is applied to the first part of the subclavian aretry, the collateral circulation 
 is carried on by — 1, the anastomosis between the superior and inferior thyroid; 2, the anasto- 
 mosis of the two vertebrals; 3, the anastomosis of the internal mammary with the deep epi- 
 gastric and the aortic intercostals ; 4, the superior intercostal anastomosing with the aortic inter- 
 costals; 5, the profunda cervicis anastomosing with the princeps cervicis; 6, the scapular branches 
 of the thyroid axis anastomosing with the branches of the axillary; and 7, the thoracic branches 
 of the axillary anastomosing with the aortic intercostals. 
 
 Branches. — The branches given off from the subclavian artery are: 
 Vertebral. Internal mammary. 
 
 Thyroid axis. Superior intercostal. 
 
 On the left side all four branches generally arise from the first portion of the 
 vessel; but on the right side, the superior intercostal usually arises from the second 
 portion of the vessel. On both sides of the body the first three branches arise close 
 together at the inner margin of the Scalenus anticus; in the majority of cases a 
 free interval of from half an inch to an inch exists between the commencement of 
 the artery and the origin of the nearest branch; in a smaller number of cases an 
 interval of more than an inch exists, but it never exceeds an inch and three-quarters. 
 In a very few instances the interval has been found to be less than half an inch. 
 The vertebral artery arises from the upper and posterior part of the subclavian 
 artery, the internal mammary from the lower part of the artery; the thyroid axis 
 from in front and the superior intercostal from behind. 
 
 The Vertebral Artery (a. vertehralis) (Fig. 399) is generally the first and 
 largest branch of the subclavian ; it arises from the upper and back part of the 
 first portion of the vessel, and, passing upward, enters the foramen in the trans- 
 verse process of the sixth cervical vertebra,^ and ascends through the foramina 
 in the transverse processes of all the vertebrae above this. Above the upper border 
 of the axis it inclines outward and upward to the foramen in the transverse process 
 of the atlas, through which it passes ; it then winds backward behind its articular 
 process, runs in a deep groove on the upper surface of the posterior arch of this 
 bone (Fig. 16), and, passing beneath the posterior occipito-atlantal ligament 
 (Figs. 199 and 202), pierces the dura mater and arachnoid, and enters the skull 
 through the foramen magnum. It then passes forward and upward, incHning 
 from the lateral aspect to the front of the medulla oblongata. It unites in the 
 middle line with the vessel of the opposite side at the lower border of the pons 
 Varolii to form the basilar artery (Fig. 401). 
 
 Relations. — At its origin it is situated behind the internal jugular and vertebral 
 veins, and is crossed by the inferior thyroid artery: it lies between the Longus 
 colli and Scalenus anticus muscles, having the thoracic duct in front of it on the 
 left side. It rests on the transverse process of the seventh cervical vertebra and 
 the sympathetic nerve. Within the foramina formed by the transverse processes 
 of the vertebrae it is accompanied by a plexus of nerves from the inferior cervical 
 ganglion of the sympathetic, and is surrounded by a dense plexus of veins which 
 unite to form the vertebral vein at the lower part of the neck. It is situated in 
 
 ' Guy's Hospital Reports, vol. i., 1836: case of axillary aneurism, in which Mr. Aston Key had tied the sub- 
 •clavian artery on the outer edge of the Scalenus muscle twelve years previously. 
 
 2 The vertebral artery sometimes enters the foramen in the transverse process of the fifth vertebra. Dr. Smyth, 
 who tied this arter.v in the livinjt subject, found it, in one of his dissections, passing into the foramen in the 
 .seventh vertebra. — Ed. of 15th English edition. 
 
638 THE BLOOD -VASCULAR SYSTEM 
 
 front of the cervical nerves, as they issue from the intervertebral foramina. WTiile 
 winding round the articular process of the atlas, it is contained in a triangular 
 space, the suboccipital triangle, formed by the Rectus capitis posticus major, the 
 Superior oblique and the Inferior oblique muscles; and at this. point is covered 
 by the Complexus muscle (Fig. 283) . The suboccipital nerve here lies between 
 the artery and the bone. Within the skull, as the artery winds round the medulla 
 oblongata, it is placed between the hypoglossal nerve and the anterior root of the 
 suboccipital nerve, beneath the first digitation of the ligamentum denticulatum, 
 and finally ascends between the basilar process of the occipital bone and the 
 anterior surface of the medulla oblongata. 
 
 Branches. — These may be divided into two sets — those given off in the neck 
 and those within the cranium. 
 
 Cervical Branches. Cranial Branches. 
 
 Lateral Spinal. Posterior Meningeal. 
 
 Muscular. Anterior Spinal. 
 
 Posterior Spinal. 
 
 Posterior Inferior Cerebellar. 
 
 Bulbar. 
 
 The Lateral Spinal Branches {rami spinales) enter the spinal canal through the 
 intervertebral foramina and divide into two branches. Of these, one passes along 
 the roots of the nerves to supply the spinal cord and its membranes, anastomosing 
 with the other arteries of the spinal cord ; the other divides into an ascending and 
 a descending branch, which unite with similar branches from the artery above and 
 below, so that two lateral anastomotic chains are formed on the posterior surface 
 of the bodies of the vertebrae near the attachment of the pedicles. From these 
 anastomotic chains branches are given off to supply the periosteum and the bodies 
 of the vertebrae, and to communicate with similar branches from the opposite side; 
 from these communicating branches small branches are given off which join 
 similar branches above and below, so that a central anastomotic chain is formed 
 on the posterior surface of the bodies of the vertebrae. 
 
 Muscular Branches are given off to the deep muscles of the neck, where the 
 vertebral artery curves round the articular process of the atlas. They anastomose 
 with the occipital and with the ascending and deep cervical arteries. 
 
 The Posterior Meningeal {ramus meningeus) is a small branch given off from 
 the vertebral opposite the foramen magnum. It ramifies between the bone and 
 dura mater in the cerebellar fossae, and supplies the falx cerebelli. 
 
 The Anterior Spinal (a. spinalis anterior) is a small branch which arises near 
 the termination of the vertebral, and, descending in front of the medulla oblongata, 
 unites with its fellow on the opposite side at about the level of the foramen magnum. 
 One of these vessels is usually larger than the other, but occasionally they are about 
 equal in size. The single trunk thus formed descends on the front of the spinal 
 cord, and is reinforced by a succession of small branches which enter the spinal 
 canal through the intervertebral foramina; these branches are derived from the 
 vertebral artery and the ascending cervical branch of the inferior thyroid artery 
 in the neck; from the intercostal in the dorsal region; and from the lumbar, 
 ilio-lumbar, and lateral sacral arteries in the lower part of the spine. They unite, 
 by means of ascending and descending branches, to form a single anterior median 
 artery, which extends as far as the lower part of the spinal cord. This vessel is 
 placed in the pia mater along the anterior median fissure; it supplies that mem- 
 brane and the substance of the cord, and sends off branches at its lower part to 
 be distributed to the cauda equina, and ends on the central fibrous prolongation 
 of the cord. 
 
THE SUBCLAVIAN ARTERY 639 
 
 The Posterior Spinal (a. spinalis posterior) arises from the vertebral at the side 
 of the medulla oblongata: passing backward to the posterior aspect of the spinal 
 cord, it descends on each side, lying behind the posterior roots of the spinal 
 nerves, and is reinforced by a succession of small branches which enter the 
 spinal canal through the intervertebral foramina, and by which it is continued to 
 the lower part of the cord and to the cauda equina. Branches from these vessels 
 form a free anastomosis round the posterior roots of the spinal nerves, and com- 
 municate, by means of very tortuous transverse branches, with the vessel of the 
 opposite side. At its commencement it gives off an ascending branch, which 
 terminates on the side of the fourth ventricle. 
 
 The Posterior Inferior Cerebellar Artery (a. cerehelli inferior posterior) (Fig. 401), 
 the largest branch of the vertebral, winds backward round the upper part of the 
 medulla oblongata, passing between the origin of the pneumogastric and spinal 
 accesssory nerves, over the restiform body to the under surface of the cerebellum, 
 where it divides into two branches — an internal, which is continued backward 
 to the notch between the two hemispheres of the cerebellum ; and an external, 
 which supplies the under surface of the cerebellum as far as its outer border, 
 where it anastomoses with the anterior inferior cerebellar and the superior cere- 
 bellar branches of the basilar artery. Branches from this artery supply the 
 choroid plexus of the fourth ventricle. 
 
 The Bulbar Arteries comprise several minute vessels which spring from the 
 vertebral and its branches and are distributed to the medulla oblongata. 
 
 Surgical Anatomy. — The vertebral artery has been tied in several instances : 1 , for wounds 
 or traumatic aneurism ; 2, after ligation of the innominate, either immediately to prevent hem- 
 orrhage, or later on to arrest bleeding where it has occurred at the seat of ligation; and 3, 
 in epilepsy. In these latter cases the treatment has been recommended by Dr. Alexander, of 
 Liverpool, in the hope that by diminishing the supply of blood to the posterior part of the brain 
 and the spinal corda diminution or cessation of the epileptic fits would result. But, on account 
 of the uncertainty as to what cases, if any, derived benefit from the operation, it has now been 
 abandoned as a treatment for epilepsy. The operation of ligation of the vertebral is performed 
 by making an incision along the posterior border of the Sterno-mastoid muscle, just above the 
 clavicle. The muscle is pulled to the inner side, and the anterior tubercle of the transverse 
 process of the sixth cervical vertebra is sought for. A deep layer of fascia being now divided, 
 the interval between the Scalenus anticus and the Longus colli muscles just below their attach- 
 ment to the tubercle is defined, and the artery and vein are found in the interspace. The vein 
 is to be drawn to the outer side, and the aneurism needle is passed from without inward. Drs. 
 Ramskill and Bright have pointed out that severe pain at the back of the head may be symp- 
 tomatic of disease of the vertebral artery just before it enters the skull. This is explained by 
 the close connection of the artery with the suboccipital nerve in the groove on the posterior 
 arch of the atlas. Disease of the same artery has been also said to aifect speech, from pressure 
 on the hypoglossal nerve where it is in relation with the vessel, leading to paralysis of the muscles 
 of the tongue. 
 
 The Basilar Artery (a. basilaris) (Fig. 401), so named from its position at the 
 base of the skull, is a single trunk formed by the junction of the two vertebral 
 arteries; it extends from the posterior to the anterior border of the pons Varolii, 
 lying in the median pontine groove, under cover of the arachnoid. It ends by 
 dividing into the two posterior cerebral arteries. 
 
 Branches. — Its branches are, on each side, the following: 
 
 Transverse. Anterior Inferior Cerebellar. 
 
 Internal Auditory. Superior Cerebellar. 
 
 Posterior Cerebral. 
 
 The Transverse or Pontal Branches (rami ad pontem) supply the substance of 
 the pons Varolii. 
 
 The Internal Auditory (a. auditiva interna) accompanies the auditory nerve 
 into the internal auditory meatus. It supplies the internal ear. 
 
640 THE BLOOD -VASCULAR SYSTEM 
 
 The Anterior Inferior Cerebellar Artery (a. cerebelli inferior anterior) passes back- 
 ward across the crus cerebelH, to be distributed to the anterior border of the under 
 surface of the cerebellum, anastomosing with the posterior inferior cerebellar 
 branch of the vertebral. 
 
 The Superior Cerebellar Artery (a. cerebelli superior) on each side arises near 
 the termination of the basilar. It passes outward, immediately behind the third 
 nerve, which separates it from the posterior cerebral, winds round the crus 
 cerebri, close to the fourth nerve, and, arriving at the upper surface of the 
 cerebellum, divides into branches which ramify in the pia mater and, reaching 
 the circumference of the cerebellum, anastomose with the branches of the inferior 
 cerebellar arteries. Several branches are given to the pineal gland, the valve of 
 Vieussens, and the velum interpositum. 
 
 The Posterior Cerebral Artery (a. cerebri posterior) (Figs. 401, 403, 404, and 406) , on 
 each side, is the terminal branch of the basilar. It is larger than the preceding, from 
 which it is separated near its origin by the third nerve. Passing outward, parallel 
 to the superior cerebellar artery, and receiving the posterior communicating from 
 the internal carotid, it winds round the crus cerebri, and passes to the under surface 
 of the occipital lobes of the cerebrum, and break up into branches for the supply of 
 the temporal and occipital lobes. The branches of the posterior cerebral artery are : 
 
 Postero-median ganglionic. ( Anterior temporal. 
 
 Posterior choroid. Three terminal < Posterior temporal. 
 
 Postero-lateral ganglionic. [ Occipital. 
 
 The postero-median ganglionic branches (Fig. 406) are a group of small arteries 
 which arise at the commencement of the posterior cerebral artery; these, with simi- 
 lar branches from the posterior communicating, pierce the posterior perforated 
 space, and supply the internal surfaces of the optic thalamus and the walls of the 
 third ventricle. The posterior choroid enters the interior of the brain beneath the 
 splenium of the corpus callosum, and supplies the velum interpositum and the 
 choroid plexus. The postero-lateral ganglionic branches are a group of small 
 arteries which arise from the posterior cerebral artery, after it has turned round the 
 crus cerebri; they supply a considerable portion of the optic thalamus. The 
 terminal branches are distributed as follows: the first, or the anterior temporal 
 branches, to the under surface of the anterior portion of the temporal lobe; the 
 second, or the posterior temporal branches, to the external occipital and the third 
 temporal convolutions; and the third, or the occipital branches, to the inner and 
 outer surfaces of the occipital lobe. 
 
 Circle of Willis {circulus arteriosus \Willisi\). — The remarkable anastomosis 
 which exists between the branches of the internal carotid and vertebral arteries at 
 the base of the brain constitutes the circle of Willis. It is formed in front, by the 
 anterior cerebral arteries, branches of the internal carotid, which are connected 
 together by the anterior communicating; behind, by the two posterior cerebrals, 
 branches of the basilar, which are connected on each side with the internal carotid 
 by the posterior communicating arteries (Fig. 401). It is by this anastomosis 
 that the cerebral circulation is equalized, and provision made for effectually 
 carrying it on if one or more of the branches are obliterated. The parts of the 
 brain included within this arterial circle are — the lamina cinerea, the commissure 
 of the optic nerves, the infundibulum, the tuber cinereum, the corpora albicantia, 
 and the posterior perforated space. 
 
 The ThjTToid Axis (truncus thyreocervicalis) (Figs. 392 and 410) is a short thick 
 trunk which arises from the forepart of the first portion of the subclavian artery, 
 close to the inner border of the Scalenus anticus muscle, and divides, almost 
 immediately after its origin, into three branches — the inferior thyroid, supra- 
 scapular, and trans versalis colli. 
 
THE SUBCLAVIAN ARTEBY 641 
 
 The Inferior Thsrroid Artery (a. thyreoidea inferior) (Fig. 392) passes upward, in 
 front of the vertebral artery and Longus colli muscle; then turns inward behind the 
 sheath of the common carotid artery and internal jugular vein, and also behind 
 the sympathetic nerve, the middle cervical ganglion resting upon the vessel, and 
 reaching the lower border of the lateral lobe of the thyroid gland it divides into 
 two branches, which supply the posterior and imder part of the organ, and anasto- 
 mose in its substance with the superior thyroid and with the corresponding artery ^ 
 of the opposite side. (See page 602.) The recurrent laryngeal nerve passes upward, j > 
 generally behind but occasionally in front of the artery. Its branches are: n)^ 
 
 Inferior I^aryngeal. Gi^sophageal. 
 
 Tracheal. Ascending Cervical. 
 
 Muscular. 
 
 The inferior larjmgeal branch (a. laryngea inferior) ascends upon the trachea 
 to the back part of the larynx, in company with the recurrent laryngeal nerve, 
 and supplies the muscles and mucous membrane of this part, anastomosing with 
 the laryngeal branch from the superior thyroid artery and with the inferior laryn- 
 geal branch from the opposite side. The tracheal branches {rami tracheales) are 
 distributed upon the trachea, anastomosing below with the bronchial arteries. 
 The (esophageal branches {rami oesophagei) are distributed to the oesophagus, 
 and anastomose with the oesophageal branches of the aorta. The ascending 
 cervical (a. cervicalis ascendens) is a small branch which arises from the inferior 
 thyroid just where that vessel is passing behind the common carotid artery, and 
 runs up on the anterior tubercles of the transverse processes of the cervical 
 vertebrae in the interval between the Scalenus anticus and Rectus capitis anticus 
 major muscles. It gives muscular branches {rami musculares) to the muscles of 
 the neck, which anastomose with branches of the vertebral, and sends one or two 
 branches {rami spinales) into the spinal canal through the intervertebral foramina 
 to be distributed to the spinal cord and its membranes, and to the bodies of the 
 vertebra? in the same manner as the lateral spinal branches from the vertebral. 
 It anastomoses with the ascending pharyngeal and occipital arteries. The mus- 
 cular branches supply the depressors of the hyoid bone, the Longus colli, the 
 Scalenus anticus, and the Inferior constrictor of the pharynx. One of the mus- 
 cular branches passes between the transverse processes of the fourth and fifth 
 cervical vertebrae and reaches the deep muscles of the neck. It is called the 
 ramus profundus. 
 
 Surgical Anatomy. — The inferior thyroid artery has been tied, in conjunction with the 
 superior thyroid, in cases of bronchocele. An incision is made along the anterior border of the 
 Sterno-mastoid down to the clavicle. After the deep fascia has been divided, the Sterno-mas- 
 toid and carotid vessels are drawn outward and the carotid tubercle (C hassaignac' s tubercle) 
 sought for. The vessel will be found just below this tubercle, between the carotid sheath on the 
 outer side of the trachea and oesophagus on the inner side. In passing the ligature great care . 
 must be exercised to avoid including the recurrent laryngeal nerve, which is occasionally found 
 ^crossin g in front of the vessel. Before extirpating a goitrous lobe of the thyroid the superior 
 and inferior thyroid" arteries ot' the diseased side are to be ligated. 
 
 The Suprascapular or Transversalis Humeri Artery (a. transversa scapulce) (Figs. 392 
 and 409), smaller than the tranversalis colli, passes obliquely from within outward, 
 across the root of the neck. It at first passes downward and outward across the 
 Scalenus anticus muscle and phrenic nerve, being covered by the Sterno-mastoid; 
 it then crosses the subclavian artery and the cords of the brachial plexus, and runs 
 outward, behind and parallel with the clavicle and Subclavius muscle, and beneath 
 the posterior belly of the Omo-hyoid, to the superior border of the scapula, where 
 it passes over the transverse ligament of the scapula, which separates it froni the 
 suprascapular nerve, and reaches the supraspinous fossa. In this situation it lies 
 close to the bone, and ramifies between it and the Supraspinatus muscle, to which it 
 
 41 
 
642 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 supplies branches. It then passes downward behind the neck of the scapula, to 
 reach the infraspinous fossa, where it anastomoses with the dorsalis scapuhe branch 
 of the subscapular artery and branches of the posterior scapular arteries. Besides 
 distributing branches to the Sterno-mastoid, Subclavius, and neighboring muscles, 
 it gives off a suprasternal branch, which crosses over the sternal end of the clavicle to 
 the skin of the upper part of the chest; and a supra-acromial branch {ramus acro- 
 mialis), which, piercing the Trapezius muscle, supplies the skin over the acromion, 
 anastomosing with the acromial thoracic artery. As the artery passes over the trans- 
 verse ligament of the scapula, a V)ranch descends into the subscapular fossa, 
 ramifies beneath the subscapular muscle, and anastomoses with the posterior and 
 subscapular arteries. The suprascapular artery also sends branches to the 
 acromio-clavicular and shoulder joints, and a nutrient artery to the clavicle. 
 
 Posterior scapular. 
 
 Suprascapular. Acromial branch 
 
 of Thoracico-acromialis. 
 I 
 
 Anterior 
 circumfiex. 
 
 Fig. 409. — The scapular and circumflex arteries. 
 
 The Transverse Cervical or Transversalis Colli Artery (a. transversa colli) (Fig. 392) 
 passes transversely outward, across the upper part of the subclavian triangle, to 
 the anterior margin of the Trapezius muscle, beneath which it divides into two 
 branches, the superficial cervical and the posterior scapular. In its passage across 
 the neck it crosses in front of the phrenic nerve, Scaleni muscles, and the brachial 
 plexus, between the divisions of which it sometimes passes, and is covered by the 
 Platysma, Sterno-mastoid, Omo-hyoid, and Trapezius muscles. The superficial 
 cervical {ramus ascendens) ascends beneath the anterior margin of the Trapezius, 
 distributing branches to it and to the neighboring muscles and glands in the neck, 
 and anastomosing with the superficial branch of the arteria princeps cervicis. The 
 posterior scapular {ramus descendens) (Fig. 409) passes beneath the Levator anguli 
 scapulae muscle to the superior angle of the scapula, and then descends along the 
 posterior border of that bone as far as the inferior angle. In its course it is 
 covered by the Rhomboid muscles, supplying them and the Latissimus dorsi and 
 Trapezius, and anastomosing with the suprascapular and subscapular arteries, 
 and with the posterior branches of some of the intercostal arteries. 
 
 Peculiarities. — The superficial cervical frequently arises as a separate branch from the thyroid 
 axis; and the posterior scapular, from the third, more rarely from the second, part of the sub- 
 clavian. 
 
THE SUBCLAVIAN ARTERY 
 
 643 
 
 The Internal Mammary (a. mammaria interna) (Fig. 410) arises from the 
 under surface of the first portion of the subclavian artery, opposite the thyroid 
 
 Scalenus 
 anticus 
 
 Thyroid axis. 
 
 Common carotid. 
 
 Innominate. 
 
 ■Internal mam- 
 mary. 
 
 Anterior intercostal 
 branches. 
 
 Perforating 
 branches. 
 
 Musculo- 
 phrenic 
 
 Superior epi- 
 gastric. 
 
 Fig. 410. — The internal mammary artery and its branches. 
 
 axis. It passes downward and inward behind the costal cartilage of the first rib 
 to the inner surface of the anterior wall of the chest, resting against the costal 
 cartilages about half an inch from the margin of the sternum; and, at the interval 
 
644 THE BLOOD -VASCULAR SYSTEM 
 
 between the sixth and seventh cartilages, divides into two branches, the musculo- 
 phrenic and superior epigastric. 
 
 Relations. — At its origin it is covered by the internal jugular and subclavian 
 veins, and as it enters the thorax is crossed from without inward by the phrenic 
 nerve, and then passes forward close to the outer side of the innominate vein. In 
 the upper part of the thorax it lips behind the costal cartilages and Internal inter- 
 costal muscles, and is crossed by the terminations of the upper six intercostal 
 nerves. At first it lies upon the pleura, but at the lower part of the thorax the 
 Triangularis sterni separates the artery from this membrane. It has two venae 
 comites; these unite into a single vein, which joins the innominate vein of its own 
 side. t 
 
 Branches. — The branches of the internal mammary are — 
 
 Comes Nervi Phrenici (Superior Phrenic). Anterior Intercostal. 
 
 Mediastinal. Perforating. 
 
 Pericardiac. Musculo-phrenic. 
 
 Sternal. Superior Epigastric. 
 
 The Comes Nervi Phrenici or Superior Phrenic (a. pericardiaco'phrenica) is a long 
 slender branch which accompanies the phrenic nerve, between the pleura and 
 pericardium, to the Diaphragm. It gives branches to the pericardium and is 
 distributed upon the Diaphragm, anastomosing with the other phrenic branches 
 from the internal mammary and with phrenic branches of the abdominal aorta. 
 
 The Mediastinal Branches {aa. mediastinales anteriores) are small vessels 
 which are distributed to the areolar tissue and lymphatic glands in the anterior 
 mediastinum and to the remains of the thymus gland. 
 
 The Pericardiac Branches supply the upper part of the anterior surface of the 
 pericardium, the lower part receiving branches from the musculo-phrenic artery. 
 
 The Sternal Branches {raTni sternales) are distributed to the Triangularis sterni 
 and to the posterior surface of the sternum. 
 
 The mediastinal, pericardiac, and sternal branches, together with some twigs 
 from the comes nervi phrenici, anastomose with branches from the intercostal and 
 bronchial arteries, and form a minute plexus beneath the pleura, which has been 
 named by Turner the subpleural mediastinal plexus. 
 
 The Anterior Intercostal Arteries {rami intercostales) supply the five or six upper 
 intercostal spaces. The branch corresponding to each space soon divides into 
 two, or the two branches may come off separately from the parent trunk. The 
 small vessels pass outward in the intercostal spaces, one, the larger, lying near 
 the lower margin of the rib above, and the other, the smaller, near the upper 
 margin of the rib below, and anastomose with the intercostal arteries from the 
 aorta. They are at first situated between the pleura and the Internal intercostal 
 muscles, and then between the Internal and External intercostal muscles. They 
 supply the Intercostal muscles, and, by branches which perforate the External 
 intercostal muscle, reach the Pectoral muscles and the mammary gland. 
 
 The Perforating or Anterior Perforating Arteries {rami perforantes) correspond 
 to the five or six upper intercostal spaces. They arise trom the internal mam- 
 mary, pass forward through the intercostal spaces, and, curving outward, supply 
 the Pectoralis major and the integument. Those which correspond to the second, 
 third, and fourth spaces are distributed to the mammary gland. In females, 
 during lactation, these branches are of large size. 
 
 The Musculo-phrenic Artery (a. musculophrenica) is directed obliquely down- 
 ward and outward, behind the cartilages of the false ribs, perforating the Dia- 
 phragm at the eighth or ninth rib, and terminating, considerably reduced in size, 
 opposite the last intercostal space. It gives off anterior intercostal arteries to 
 each of the intercostal spaces across which it passes; these diminish in size as the 
 
SURGICAL ANATOMY OF THE AXILLA 645 
 
 spaces decrease in length, and are distributed in a manner precisely similar to 
 the anterior intercostals from the internal mammary. The musculo-phrenic also 
 gives branches to the lower part of the pericardium, and others which run back- 
 ward to the Diaphragm and downward to the abdominal muscles. 
 
 The Superior Epigastric (a. epigastrica superior) continues in the original direc- 
 tion of the internal mammary; it descends through the cellular interval between 
 the Costal and sternal attachments of the Diaphragm, and enters the sheath of the 
 Rectus abdominis muscle, at first lying behind the muscle, and then perforating 
 it and supplying it, and anastomosing with the deep epigastric artery from the 
 external iliac. Some branches perforate the sheath of the Rectus, and supply the 
 muscles of the ab<]omen and the integument, and a small branch, which passes 
 inward upon the side of the ensiform appendix, anastomoses in front of that 
 cartilage with the superior epigastric artery of the opposite side. It also gives 
 some twigs to the Diaphragm, while from the artery of the right side small 
 branches extend into the falciform ligament of the liver and anastomose with 
 the hepatic artery. 
 
 Surgical Anatomy. — The course of the internal mammary artery may be defined by draw- 
 ing a hne across the six upper intercostal spaces half an inch from and parallel with the sternum. 
 The position of the vessel must be remembered, as it is liable to be wounded in stabs of the 
 chest-wall. It is most easily reached by a transverse incision in the second intercostal space. 
 
 The Superior Intercostal (truncus costocervicalis)(Figs. 399 and 416) arises from 
 the upper and back part of the subclavian artery, behind the Scalenus anticus mus- 
 cle on the right side and to the inner side of that muscle on the left side. Passing 
 backward, it gives off the deep cervical branch, and then descends behind the 
 pleura in front of the necks of the first two ribs, and inosculates with the first 
 aortic intercostal. As it crosses the neck of the first rib it lies to the inner side 
 of the anterior division of the first dorsal nerve and to the outer side of the first 
 thoracic ganglion of the sympathetic. In the first intercostal space it gives off a 
 branch which is distributed in a manner similar to the distribution of the aortic 
 intercostals. The branch for the second intercostal space usually joins with one 
 from the highest aortic intercostal. Each intercostal gives off a branch to the 
 posterior spinal muscles, and a small branch which passes through the corre- 
 sponding intervertebral foramen to the spinal cord and its membranes. 
 
 The Deep Cervical Branch (a. cervicalis profunda) arises, in most cases, from 
 the superior intercostal, and is analogous to the posterior branch of an aortic 
 intercostal artery; occasionally it arises as a separate branch from the sub- 
 clavian artery. Passing backward, above the eighth cervical nerve and between 
 the transverse process of the seventh cervical vertebra and the first rib, it runs 
 up the back part of the neck, between the Complexus and Semispinalis colli 
 muscles, as high as the axis vertebra, supplying these and adjacent muscles, and 
 anastomosing with the deep branch of the arteria princeps cervicis of the occipital, 
 and with branches which pass outward from the vertebral. It gives off a special 
 branch which enters the spinal canal through the intervertebral foramen between 
 the seventh cervical and first dorsal vertebrae. 
 
 SURGICAL ANATOMY OF THE AXILLA. 
 
 The axilla is a pyramidal space, situated between the upper and lateral part 
 of the chest and the inner side of the arm. 
 
 Boundaries. — Its apex, which is directed upward toward the root of the neck, 
 corresponds to the interval between the first rib, the upper edge of the scapula, 
 and the clavicle, through which the axillary vessels, the brachial plexus of nerves, 
 and the long thoracic nerve pass. This interval is the cervico -axillary passage. 
 
646 THE BLOOD -VASCULAR SYSTEM 
 
 The base, directed downward, is formed by the integument and a thick layer of 
 fascia, the axillary fascia (fascia axillaris) (Fig. 313), extending between the lower 
 border of the Pectoralis major in front and the lower border of the Latissimus 
 dorsi behind (page 463). The axillary fascia is perforated at several points. 
 The large central opening is called the foramen of Langer. The inner margin of 
 the foramen of Langer is dense and constitutes a part of the axillary arch,. 
 which is a fibro-muscular slip derived from the latissimus dorsi. The axilla 
 is broad internally at the chest, but narrow and pointed externally at the 
 arm. The anterior boundary is formed by the Pectoralis major and minor mus- 
 cles, the former covering the whole of the anterior wall of the axilla, the latter 
 covering only its central part, the costo-coracoid membrane, the clavicle, and the 
 Subclavius muscle. The posterior boundary, which extends somewhat lower 
 than the anterior, is formed by the Subscapularis above, the Teres major and 
 Latissimus dorsi below. On the inner side are the first four ribs with their 
 corresponding Intercostal muscles, and part of the Serratus magnus. On 
 the outer side, where the anterior and posterior boundaries converge, the space 
 is narrow, and bounded by the humerus, the Coraco-brachialis and Biceps 
 muscles. 
 
 Contents.— This space contains the axillary vessels and brachial plexus of 
 nerves, with their branches, some branches of the intercostal nerves, and a large 
 number of lymphatic glands, all connected together by a quantity of fat and loose 
 areolar tissue. 
 
 Position of the Contents. — The axillary artery and vein, with the brachial plexus 
 of nerves, extend obliquely along the outer boimdary of the axillary space, from 
 its apex to its base, and are placed much nearer the anterior than the posterior wall, 
 the vein lying to the inner or thoracic side of the artery and partially concealing 
 it. At the forepart of the axillary space, in contact with the Pectoral muscles, and 
 along the anterior margin are the thoracic branches of the axillary artery, and 
 along the lower margin of the Pectoralis minor the long thoracic artery extends 
 to the side of the chest. At the back part, in contact with the lower margin of 
 the Subscapularis muscle, are the subscapular vessels and nerves; winding around 
 the outer border of this muscle is the dorsalis scapulae artery and veins; and, close 
 to the neck of the humerus, the posterior circumflex vessels and the circumflex 
 nerve are seen curving backward to the shoulder. 
 
 Along the inner or thoracic side no vessel of any importance exists, the upper 
 part of the space being crossed merely by a few small branches from the superior 
 thoracic artery. There are some important nerves, however, in this situation — 
 viz., the posterior thoracic or external respiratory nerve, descending on the sur- 
 face of the Serratus magnus, to which it is distributed; and perforating the upper 
 and anterior part of this wall, the intercosto-humeral nerve or nerves, passing 
 across the axilla to the inner side of the arm. 
 
 The cavity of the axilla is filled by a quantity of loose areolar tissue and a large 
 number of small arteries and veins, all of which are, however, of inconsiderable 
 size, and numerous lymphatic glands, the position and arrangement of which are 
 described on a subsequent page. 
 
 Surgical Anatomy. — The axilla is a space of considerable surgical importance. It trans- 
 mits the large vessels and nerves to the upper extremity, and these may be the seat of injury or 
 disease: it contains numerous lymphatic glands which may require removal when diseased; in it 
 is a quantity of loose connective and adipose tissue which may be readily infiltrated with blood 
 or pus. The axilla may be the seat of rapidly growing tumors. Moreover, it is covered at its 
 base by thin skin, largely supplied with sebaceous and sweat glands, which is frequently the 
 seat of small cutaneous abscesses and boils, and of eruptions due to irritation. 
 
 In suppuration in the axilla the arrangement of the fascije plays a very important part in the 
 direction which the pus takes. As described on page 464, the costo-coracoid membrane, after 
 covering in the space between the clavicle and the upper border of the Pectoralis minor, splits 
 
THE AXILLARY ARTERY 
 
 647 
 
 to enclose this muscle, and, reblending at its lower border, becomes incorporated with the axillary 
 fascia at the anterior fold of the axilla. This is known as the clavi-pectoral fascia. Suppura- 
 tion may take place either superficial to or beneath this layer of fascia; that is, either between 
 the Pectorals or below the Pectoralis minor: in the former case, the pus would point either at the 
 anterior border of the axillary fold or in the groove between the Deltoid and the Pectoralis major; 
 in the latter, the pus would have a tendency to surround the vessels and nerves and ascend into 
 the neck, that being the direction in which there is least resistance. Its progress toward the 
 skin is prevented by the axillary fascia; its progress backward, by the Serratus magnus; forward, 
 by the clavi-pectoral fascia; inward, by the wall of the thorax; and outward, by the upper limb. 
 The pus in these cases, after extending into the neck, has been known to spread through the 
 superior opening of the thorax into the mediastinum. 
 
 In opening an axillary abscess the knife should be entered in the floor of the axilla, midway 
 between the anterior and posterior margins and near the thoracic side of the space. It is well 
 to use a director and dressing forceps after an incision has been made through the skin and fascia 
 in the manner directed by the late Mr. Hilton. 
 
 The student should attentively consider the relation of the vessels and nerves in the several 
 parts of the axilla, for it is the universal plan, at the present day, to remove the glands from 
 the axilla in operating for cancer of the breast. In performing such an operation it will be 
 necessary to proceed with much caution in the direction of the outer wall and apex of the space, 
 
 Anterior 
 circumjlex. 
 
 Fig. 411. — The axillary artery and its branches. 
 
 as here the axillary vessels will be in danger of being wounded. Toward the posterior wall it 
 will be necessary to avoid the subscapular, dorsalis scapulae, and posterior circumflex vessels. 
 Along the anterior wall it will be necessary to avoid the thoracic branches. In clearing out the 
 axilla the axillary vein should be first defined and cleared up to the apex of the axilla. 
 When the apex of the space is reached, all fat and glands must be carefully removed and the 
 whole axilla cleared by separating the tissues along the inner and posterior walls, so that when 
 the proceeding is completed, the axilla is cleared of all its contents except the main vessels and 
 
 THE AXILLARY ARTERY (A. AXILLARIS) (Fig. 411). 
 
 The axillary artery, the continuation of the subclavian, commences at the 
 outer border of the first rib, and terminates at the lower border of the tendon 
 
648 THE BLOOD -VASCULAB SYSTEM 
 
 of the Teres major muscle, where it takes the name of brachial. Its direction 
 varies with the position of the limb: when the arm lies by the side of the 
 chest, the vessel forms a gentle curve, the convexity being upward and outward; 
 when the arm is directed at right angles with the trunk, the vessel is nearly 
 straight; and when the arm is elevated still higher, the arteries describe a curve 
 the concavity of which is directed upward. At its commencement the artery is 
 very deeply situated, but near its termination it is superficial, being covered only 
 by the skin and fascia. The description of the relations of this vessel is facili- 
 tated by its division into three portions, the first portion being above the 
 Pectoralis minor; the second portion behind; and the third below that muscle. 
 
 Relations. — The first portion of the axillary artery is in relation, in front, with 
 the clavicular portion of the Pectoralis major, the costo-coracoid membrane, the 
 external anterior thoracic nerve, and the acromio-thoracic and cephalic veins; 
 behind, with the first intercostal space, the corresponding Intercostal muscle, 
 the second and a portion of the third digitation of the Serratus magnus, and the 
 posterior thoracic and internal anterior thoracic nerves; on its outer side, with the 
 brachial plexus, from which it is separated by a little cellular interval; on its inner 
 or thoracic side, with the axillary vein, which overlaps the artery. 
 
 Relations of the First Portion of the Axillary Artery. 
 
 In front. 
 Pectoralis major. 
 Costo-coracoid membrane. 
 External anterior thoracic nerve. 
 Acromio-thoracic and cephalic veins. 
 
 Outer side. I Axillary \ Inner side. 
 
 Brachial plexus. I First portion, j Axillary vein. 
 
 Behind. 
 First Intercostal space and Intercostal muscle. 
 Second and third digitations of Serratus magnus. 
 Posterior thoracic and Internal anterior thoracic nerves. 
 
 The second portion of the axillary artery lies beyond the Pectoralis minor. It 
 is covered, in front, by the Pectoralis major and minor muscles; behind, it is 
 separated from the Subscapularis by a cellular interval; on the inner side is the 
 axillary vein, separated from the artery by the inner cord of the plexus and the 
 internal anterior thoracic nerve. The brachial plexus of nerves surrounds the 
 artery on three sides, and separates it from direct contact with the vein and 
 adjacent muscles. 
 
 Relations of the Second Portion of the Axillary Artery. 
 
 In front. 
 Pectoralis major and minor. 
 
 Outer side. / X Inner side. 
 
 Outer cord of plexus. [ Arte*/'' ) Axillary vein. 
 
 Inner cord of plexus. 
 
 Internal anterior thoracic nerve. 
 
 Behind. 
 Subscapularis. 
 Posterior cord of plexus. 
 
THE AXILLARY ABTEBY 649 
 
 The third portion of the axillary artery lies below the Pectoralis minor. It is 
 in relation, in front, with the lower part of the Pectoralis major above, being 
 covered only by the integument and fascia below, where it is crossed by the inner 
 head of the median nerve; behind, with the lower part of the Subscapularis and 
 the tendons of the Latissimus dorsi and Teres major; on its outer side, with the 
 Coraco-brachialis; on its inner or thoracic side, with the axillary vein. The nerves 
 of the brachial plexus bear the following relation to the artery in this part of its 
 course: on the outer side is the median nerve, and the musculo-cutaneous for a 
 short distance; on the inner side, the ulnar nerve (between the vein and artery) 
 and the lesser internal cutaneous nerve (to the inner side of the vein); in front 
 is the internal cutaneous nerve, and behind, the musculo-spiral and circumflex, the 
 latter extending only to the lower border of the Subscapularis muscle. 
 
 Relations of ihe Third Portion of the Axillary Artery. 
 
 In front. 
 Integument and fascia. 
 Pectoralis major. 
 Inner head of median nerve. 
 Internal cutaneous nerve. 
 
 Older side, /^ \ Inner side. 
 
 Coraco-brachialis. [ "A^rtery^ | Ulnar nerve. 
 
 Median nerve. I Third porticm. y Axillary vein. 
 
 Musculo-cutaneous nerve. \ / Lesser internal cutaneous nerve. 
 
 Behind. 
 Subscapularis. 
 
 Tendons of Latissimus dorsi and Teres major. 
 Musculo-spiral and circumflex nerves. 
 
 Peculiarities. — The axillary artery, in about one case out of every ten, gives off a large 
 branch, which forms either one of the arteries of the forearm or a large muscular trunk. In the 
 first set of cases this artery is most frequently the radial (1 in 33), sometimes the ulnar (1 in 72), 
 and, very rarely, the interosseous (1 in 506). In the second set of cases the trunk has been 
 found to give origin to the subscapular, circumflex, and profunda arteries of the arm. Some- 
 times only one of the circumflex, or one of the profunda arteries, arose from the trunk. In 
 these cases the brachial plexus surrounded the trunk of the branches and not the main vessel. 
 
 Surface Marking. — The course of the axillary artery may be marked out by raising the 
 arm to a right angle with the body and drawing a line from the middle of the clavicle to the 
 point where the tendon of the Pectoralis major crosses the prominence caused by the Coraco- 
 brachialis as it emerges from under cover of the anterior fold of the axilla. The third portion 
 of the artery can be felt pulsating beneath the skin and fascia, at the junction of the anterior 
 with the middle third of the space between the anterior and posterior folds of the axilla, close to 
 the inner border of the Coraco-brachialis muscle. 
 
 Surgical Anatomy. — The student, having carefully examined the relations of the axillary 
 artery in its various parts, should now consider in what situation compression of this vessel 
 may be most easily effected, and the best position for the application of a ligature to it when 
 necessary. 
 
 Compression of the vessel may be required in the removal of tumors or in amputation of 
 the upper part of the arm ; and the only situation in which this can be effectually made is in the 
 lower part of its course; by pressing on it in this situation from within outward against the 
 humerus the circulation may be effectually arrested. 
 
 The axillary artery is perhaps more frequently lacerated than any other artery in the body, 
 with the exception of the popliteal, by violent movements of the extremity, especially in those 
 cases where its coats are diseased. It has occasionally been ruptured in attempts to reduce old 
 dislocations of the shoulder-joint. This accident is most likely to occur during the preliminary 
 breaking down of adhesions, in consequence of the artery having become fixed to the capsule 
 of the joint. Aneurism of tfie axillary artery is of frequent occurrence, a large percentage of 
 the cases being traumatic in their origin, due to the violence to which the vessel is exposed in 
 the varied, extensive, and often violent movements of the limb. 
 
 The application of a ligature to the axillary artery may be required in cases of 
 aneurism of the upper part of the brachial or as a distal operation for aneurism of the sub- 
 
650 'J'HE BLOOD -VASCULAR JSYSTUIf 
 
 clavian; and there are only two situations in which the vessel can be secured — viz., in the first 
 and in the third parts of its course; for the axillary artery at its central part is so deeply seated, 
 and, at the same time, so closely surrounded with large nerve trunks, that the application of a 
 ligature to it in that situation would be almost impracticable. 
 
 In the third part of its course the operation is most simple, and may be performed in th- 
 following manner: The patient being placed on a bed and the arm separated from the side, with 
 the hand supinated, an incision about two inches in length is made through the integument 
 forming the floor of the axilla, the cut being a little nearer to the anterior than the posterior 
 fold of the axilla. After carefully dissecting through the areolar tissue and fascia, the median 
 nerve and axillary vein are exposed; the former having been displaced to the outer and the 
 latter to the inner side of the arm, the elbow being at the same time bent, so as to relax the 
 structures and facilitate their separation, the ligature may be passed round the artery from the 
 ulnar to the radial side. 
 
 This portion of the artery is occasionally crossed by a muscular slip, the axillary arch, derived 
 from the Latissimus dorsi, which may mislead the surgeon during an operation. The occasional 
 existence of this muscular fasciculus was spoken of in the description of the muscles. It may 
 easily be recognized by the transverse direction of its fibres. 
 
 The first portion of the axillary artery may be tied in cases of aneurism encroaching so far 
 upward that a ligature cannot be applied in the lower part of its course. Notwithstanding that 
 this operation 'has been performed in some few cases, and with success, its performance is at- 
 tended with much difficulty and danger. The student will remark that in this situation it would 
 be necessary to divide a thick muscle, and, after incising the costo-coracoid membrane, the 
 artery would be exposed at the bottom of a more or less deep space, with the cephalic and axil- 
 lary veins in such relation with it as must render the application of a ligature to this part of 
 the vessel particularly hazardous. Under such circumstances it is an easier, and at the same 
 time more advisable, operation to tie the subclavian artery in the third part of its course. 
 
 The vessel in the first part of its course can best be secured through a curved incision the 
 convexity of which is downward. This incision passes from a point half an inch external to 
 the sterno-clavicular joint to a point half an inch internal to the coracoid process. The limb 
 is to be well abducted and the head inclined to the opposite side, and this incision is carried 
 through the superficial structures, care being taken to avoid the cephalic vein at the outer angle 
 of the incision. The clavicular origin of the Pectoralis major is then divided in the whole 
 extent of the wound. The arm is now to be brought to the side, and the upper edge of the 
 Pectoralis minor defined and drawn downward. The costo-coracoid membrane is to be care- 
 fully divided close to the coracoid process, and the axillary sheath exposed; this is to be opened 
 with especial care on account of the vein overlapping the artery. The needle should be passed 
 from below, so as to avoid wounding the vein. 
 
 In a case of wound of the vessal the general practice of cutting down upon and tying it above 
 and below the wounded point should be adopted in all cases. 
 
 Collateral Circulation after Ligature of the Axillary Artery.— If the artery be tied 
 above the origin of the acromial thoracic, the collateral circulation will be carried on by the same 
 branches as after the ligature of the subclavian; if at a lower point, between the acromial thoracic 
 and subscapular arteries, the latter vessel, by its free anastomoses with the other scapular arteries, 
 branches of the subclavian, will become the chief agent in carrying on the circulation, to which 
 the long thoracic, if it be below the ligature, will materially contribute by its anastomoses with 
 the intercostal and internal mammary arteries. If the point included in the ligature be below 
 the origin of the subscapular artery, it will most probably also be below the origins of the cir- 
 cumflex arteries. The chief agents in restoring the circulation will then be the subscapular and 
 the two circumflex arteries anastomosing with the superior profunda from the brachial, which 
 will be afterward referred to as performing the same office after ligation of the brachial. The 
 cases in which the operation has been performed are few in number, and no published account 
 of dissections of the collateral circulation appears to exist. 
 
 Branches. — The branches of the axillary artery are — 
 
 From first part < '^P^^^^^ rrii*^^^^^^' From second part \ \ ?"^r 
 
 ' ^ [ Acromial 1 horacic. ^ ( Alar 
 
 Thoracic. 
 Thoracic. 
 ( Subscapular. 
 From third part < Posterior Circumflex. 
 ' Anterior Circumflex. 
 
 The Superior Thoracic (a. thoracalis suprema) is a small artery which arises 
 from the axillary separately or by a common trunk with the acromial thoracic. 
 Running forward and inward along the upper border of the Pectoralis minor, it 
 
THE AXILLARY ABTEBY 651 
 
 passes between it and the Pectoralis major to the side of the chest. It supplies 
 these muscles and the parietes of the thorax, anastomosing with the internal mam- 
 mary and intercostal arteries. 
 
 The Acromial Thoracic or the Thoracic Axis (a. thoracoacromialis) is a 
 short trunk which arises from the forepart of the axillary artery, its origin being 
 generally overlapped by the upper edge of the Pectoralis minor. Projecting 
 forward to the upper border of the Pectoralis minor, it divides into four sets of 
 branches — thoracic, acromial, descending, and clavicular. 
 
 The Thoracic Branches {rami pedorales), two or three in number, are distributed 
 to the Serratus magnus and Pectoral muscles, anastomosing with the intercostal 
 branches of the internal mammary. 
 
 The Acromial Branch (ramus acromialis) is directed outward toward the acro- 
 mion, supplying the Deltoid muscle, and anastomosing, on the surface of the 
 acromion, with the suprascapular and posterior circumflex arteries. 
 
 The Descending or Humeral Branch (ramus deltoideu^) passes in the space between 
 the Pectoralis major and Deltoid, in the same groove as the cephalic vein, and 
 supplies both muscles. 
 
 The Clavicular Branch (ramu^ clavicularis) , which is very small, passes upward 
 to the Subclavius muscle. 
 
 The Long Thoracic or the External Mammary (a. thoracalis lateralis) passes 
 downward and inward along the lower border of the Pectoralis minor to the side 
 of the chest, supplying the Serratus magnus, the Pectoral muscles, and mammary 
 gland, and sending branches across the axilla to the axillary glands and Sub- 
 scapularis; it anastomoses with the internal mammary and intercostal arteries. 
 
 The Alar Thoracic is a small branch which supplies the glands and areolar 
 tissue of the axilla. Its place is frequently supplied by branches from some of the 
 other thoracic arteries. 
 
 The Subscapular (a. subscapularis) , the largest branch of the axillary artery, 
 arises opposite the lower border of the Subscapularis muscle, and passes downward 
 and backward along its lower margin to the inferior angle of the scapula, where it 
 anastomoses with the long thoracic and intercostal arteries and with the posterior 
 scapular, a branch of the trans versalis colli, from the thyroid axis of the sub- 
 clavian. About an inch and a half from its origin it gives off a large branch, the 
 dorsalis scapulae, and terminates by supplying branches to the muscles in the 
 neighborhood. 
 
 The Dorsalis Scapulae (a. circumflexa scapulce) is given off from the subscapular 
 about an inch and a half from its origin, and is generally larger than the continua- 
 tion of the vessel. It curves round the axillary border of the scapula, leaving the 
 axilla through the space between the Teres minor above, the Teres major below, 
 and the long head of the Triceps externally (Fig. 409), and enters the infraspinous 
 fossa by passing under cover of the Teres minor, where it anastomoses with the 
 posterior scapular and suprascapular arteries. In its course it gives off two sets 
 of branches : one enters the subscapular fossa beneath the Subscapularis, which it 
 supplies, anastomosing with the posterior scapular and suprascapular arteries; 
 the other is continued along the axillary border of the scapula, between the Teres 
 major and minor, and, at the dorsal surface of the inferior angle of the bone, anas- 
 tomoses with the posterior scapular. In addition to these, small branches are 
 distributed to the back part of the Deltoid muscle and the long head of the 
 Triceps, anastomosing with an ascending branch of the superior profunda of the 
 brachial. 
 
 The Circumflex Arteries wind round the surgical neck of the humerus. The 
 posterior circumflex (a. circumflexa humeri posterior) (Fig. 409), the larger of the 
 two, arises from the back part of the axillary opposite the lower border of the 
 Subscapularis muscle, and, passing backward with the circumflex veins and nerve 
 
652 
 
 THE BLOOD -VASCULAB SYSTEM 
 
 through the quadrangular space bounded by the Teres major and minor, the 
 scapular head of the Triceps and the humerus, winds round the neck of that bone 
 and is distributed to the Deltoid muscle and shoulder-joint, anastomosing with the 
 anterior circumflex and acromial thoracic arteries, and with the superior profunda 
 branch of the brachial artery. The anterior circumflex {a. circumflexa humeri ante- 
 rior) (Figs. 409 and 411), considerably smaller than the preceding, arises nearly 
 opposite that vessel from the outer side of the axillary artery. It passes horizon- 
 tally outward beneath the Coraco-brachialis and short head of the Biceps, lying 
 
 upon the forepart of the neck of the 
 humerus, and, on reaching the bicipital 
 groove, gives off an ascending branch 
 which passes upward along the groove 
 to supply the head of the bone and the 
 shoulder-joint. The trunk of the vessel 
 is then continued outward beneath the 
 Deltoid, which it suppHes, and anasto- 
 moses with the posterior circumflex 
 artery. 
 
 THE BRACHIAL ARTERY (A. 
 
 OHIALIS) (Fig. 412). 
 
 BRA- 
 
 The brachial artery (a. brachialis) 
 commences at the lower margin of the 
 tendon of the Teres major, and, passing 
 down the inner and anterior aspect of 
 the arm, terminates about half an inch 
 below the bend of the elbow, where it 
 divides into the radial and ulnar arteries. 
 At first the brachial artery lies internal 
 to the humerus ; but as it passes down 
 the arm it gradually gets in front of 
 the bone, and at the bend of the elbow 
 it lies midway between the two condyles. 
 Relations. — This artery is superficial 
 throughout its entire extent, being cov- 
 ered, in front, by the integument, the 
 superficial and deep fasciae; the bicipital 
 fascia separates it opposite the elbow 
 from the median basilic vein ; the median 
 nerve crosses it at its middle; behind, it 
 is separated from the long head of the 
 Triceps by the musculo-spiral nerve and 
 superior profunda artery. It then lies 
 upon the inner head of the Triceps, next 
 upon the insertion of the Coraco-bra- 
 chialis, and lastly on the Brachialis an- 
 ticus; by its outer side, it is in relation with the commencement of the median 
 nerve and the Coraco-brachialis and Biceps muscles, which overlap the artery 
 to a considerable extent; by its inner side, its upper half is in relation with the 
 internal cutaneous and ulnar nerves, its lower half with the median nerve. The 
 basihc vein lies on the inner side of the artery, but is separated from it in the 
 lower part of the arm by the deep fascia. The brachial artery is accompanied by 
 
 Fig. 412. — The brachial artery. 
 
SURGICAL ANATOMY OF THE BEND OF THE ELBOW 653 
 
 two venae comites, which he in close contact with, the artery, being connected 
 together at intervals by short transverse communicating branches. 
 
 Plan of the Relations of the Brachial Artery. 
 
 In front. 
 
 Integument and fasciae. 
 
 Bicipital fascia, median basilic vein. 
 
 Median nerve. 
 
 Overlapped by Coraco-brachialis and Biceps. 
 
 Outer side. / \ Inner side. 
 
 Median nerve (above). I Brachial \ Internal cutaneous and Ulnar nerves. 
 
 Coraco-brachialis. I Artery. i jvie^jian nerve (below). 
 
 Biceps. \ / Basilic vein. 
 
 Behind. 
 
 Triceps (long and inner heads). 
 Musculo-spiral nerve. 
 Superior profunda artery. 
 Coraco-brachialis. 
 Brachialis anticus. 
 
 SURGICAL ANATOMY OF THE BEND OF THE ELBOW. 
 
 At the bend of the elbow the brachial artery sinks deeply into a triangular inter- 
 val, the antecubital space, the base of which is directed upward, and may be repre- 
 sented by a line connecting the two condyles of the humerus; the sides are bounded, 
 externally, by the inner edge of the Supinator longus; internally, by the outer mar- 
 gin of the Pronator radii teres; its floor is formed by the Brachialis anticus and 
 Supinator brevis. This space contains the brachial artery with its accompanying 
 veins, the radial and ulnar arteries, the median and musculo-spiral nerves, and the 
 tendon of the Biceps. The brachial artery occupies the middle line of this space, and 
 divides opposite the neck of the radius into the radial and ulnar arteries; it is 
 covered, in front, by the integument, the superficial fascia, and the median basilic 
 vein, the vein being separated from direct contact with the artery by the bicipital 
 fascia. Behind, it lies on the Brachialis anticus, which separates it from the 
 elbow-joint. The median nerve lies on the inner side of the artery, close to it 
 above, but separated from it below by the coronoid origin of the Pronator radii 
 teres. The tendon of the Biceps lies to the outer side of the space, and the mus- 
 culo-spiral nerve still more externally, situated upon the Supinator brevis and 
 partly concealed by the Supinator longus. 
 
 Peculiarities of the Brachial Artery as Regards its Course. — The brachial artery, accom- 
 panied by the median nerve, may leave the inner border of the Biceps and descend toward the 
 inner condyle of the humerus, where it usually curves round a prominence of bone, the supra- 
 condylar process. From this process, in most subjects, a fibrous arch is thrown over the 
 artery. The vessel then inclines outward, beneath or through the substance of the Pronator 
 radii teres muscle, to the bend of the elbow. The variation bears considerable analogy to the 
 normal condition of the artery in some of the carnivora: it has been referred to in the descrip- 
 tion of the humerus (page 180). 
 
 As Regards its Division. — Occasionally, the artery is divided for a short distance at its upper 
 part into two trunks, which are united above and below. A similar peculiarity occurs in the main 
 vessel of the lower limb. 
 
 The point of bifurcation may be above or below the usual point, the former condition being 
 by far the more frequent. Out of 481 examinations recorded by Mr. Quain, some made on the 
 right and some on the left side of the body, in 386 the artery bifurcated in its normal position. 
 In one case only was the place of division lower than usual, being two or three inches below the 
 elbow-joint. "In 94 cases out of 481, or about 1 in 5J, there were two arteries instead of one 
 in some part or in the whole of the arm." 
 
654 THE BLOOD -VASCULAR SYSTEM 
 
 There appears, however, to be no correspondence between the arteries of the two arms with 
 respect to their irregular division; for in 61 bodies it occurred on one side only in 43; on both 
 sides, in different positions, in 13; on both sides, in the same position, in 5. 
 
 The point of bifurcation takes place at different parts of the arm, being most frequent in 
 the upper part, less so in the lower part, and least so in the middle, the most usual point for 
 the application of a ligature; under any of these circumstances two large arteries would be found 
 in the arm instead of one. The most frequent (in three out of four) of these peculiarities is 
 the high origin of the radial. That artery often arises from the inner side of the brachial, 
 and runs parallel with the main trunk to the elbow, where it crosses it, lying beneath the fascia; 
 or it may perforate the fascia and pass over the artery immediately beneath the integument. 
 
 The ulnar sometimes arises from the brachial high up, and accompanies that vessel to the 
 lower part of the arm, and descends toward the inner condyle. In the forearm it generally lies 
 beneath the deep fascia, superficial to the flexor muscles; occasionally between the integument 
 and deep fascia, and very rarely beneath the flexor muscles. 
 
 The interosseous artery sometimes arises from the upper part of the brachial or axillary; as 
 it passes down the arm it lies behind the main trunk, and at the bend of the elbow regains its 
 .usual position. 
 
 In some cases of high origin of the radial the remaining trunk (ulnar interosseous) occa- 
 sionally passes, together with the median nerve, along the inner margin of the arm to the inner 
 condyle, and then passing from within outward, beneath or through the Pronator radii teres, 
 regains its usual position at the bend of the elbow. 
 
 Occasionally the two arteries representing the brachial are connected at the bend of the elbow 
 by a short transverse branch, and are even sometimes reunited. 
 
 Sometimes, long slender vessels, vasa aberrantia, connect the brachial or axillary arteries 
 with one of the arteries of the forearm or a branch from them. These vessels usually join the 
 radial. 
 
 Varieties in Muscular Relations.' — The brachial artery is occasionally concealed in some 
 part of its course by muscular or tendinous slips derived from the Coraco-brachialis, Biceps, 
 Brachialis anticus, and Pronator radii teres muscles. 
 
 Surface Marking. — The direction of the brachial artery is marked by a line drawn along 
 the inner edge of the Biceps from the junction of the anterior and middle thirds of the axillary 
 outlet to the middle of the front of the elbow-joint. 
 
 Surgical Anatomy. — Compression of the brachial artery is required in cases of amputation 
 and some other operations in the arm and forearm ; and it will be observed that it may be effected 
 in almost any part of the course of the artery. If pressure is made in the upper part of the 
 limb, it should be directed from within outward; and if in the lower part, from before backward, 
 as the artery lies on the inner side of the humerus above and in front of the humerus below. 
 The most favorable situation is about the middle of the arm, where it lies on the tendon of the 
 Coraco-brachialis on the inner flat side of the humerus. 
 
 The application of a ligature to the brachial artery may be required in case of wound of 
 the vessel and in some cases of wound of the palmar arch. It is also sometimes necessary in 
 cases of aneurism of the brachial, the radial, ulnar, or interosseous arteries. The artery may 
 be secured in any part of its course. The chief guides in determining its position are the sur- 
 face markings produced by the inner margin of the Coraco-brachialis and Biceps, the known 
 course of the vessel, and its pulsation, which should be carefully felt for before any operation is 
 performed, as the vessel occasionally deviates from its usual position in the arm. In whatever 
 situation the operation is performed, great care is necessary, on account of the extreme thinness 
 of the parts covering the artery and the intimate connection which the vessel has throughout its 
 whole course with important nerves and veins. Sometimes a thin layer of muscular fibre is 
 met with concealing the artery ; if such is the case, it must be cut across in order to expose the 
 vessel. 
 
 In the upper third of the arm the artery may be exposed in the following manner: The 
 patient being placed supine upon a table, the affected limb should be raised from the side and 
 the hand supinated. An incision about two inches in length should be made on the inner 
 side of the Coraco-brachialis muscle, and the subjacent fascia cautiously divided, so as to avoid 
 wounding the internal cutaneous nerve or basilic vein, which sometimes runs on the surface of 
 the artery as high as the axillary. The fascia having been divided, it should be remembered that 
 the ulnar and internal cutaneous nerves lie on the inner side of the artery, the median on the 
 outer side, the latter nerve being occasionally superficial to the artery in this situation, and that 
 the venje comites are also in relation with the vessel, one on either side. These being carefully 
 separated, the aneurism needle should be passed round the artery from the inner to the outer 
 side. 
 
 If two arteries are present in the arm in consequence of a high division, they are usually 
 placed side by side: and if they are exposed in an operation, the surgeon should endeavor to 
 
 1 See Struther's Anatomical and Physiological Observations. 
 
BRANCHES OF THE BRACHIAL ARTERY 655 
 
 ascertain, by alternately pressing on each vessel, which of the two communicates with the wound 
 or aneurism, when a ligature may be applied accordingly; or if pulsation or hemorrhage ceases 
 only when both vessels are compressed, both vessels may be tied, as it may be concluded that 
 the two communicate above the seat of disease or are reunited. 
 
 It should also be remembered that two arteries may be present in the arm in a case of high 
 division, and that one of these may be found along the inner intermuscular septum, in a line 
 toward the inner condyle of the humerus, or in the usual position of the brachial, but deeply 
 placed beneath the common trunk: a knowledge of these facts will suggest the precautions 
 necessary in every case, and indicate the measures to be adopted when anomalies are met with. 
 
 In the middle of the arm the brachial artery may be exposed by making an incision along 
 the inner margin of the Biceps muscle. The forearm being bent so as to relax the muscle, it 
 should be drawn slightly aside, and, the fascia being carefully divided, the median nerve will be 
 exposed lying upon the artery (sometimes beneath); this being drawn inward and the muscle 
 outward, the artery should be separated from its accompanying veins and secured. In this 
 situation the inferior profunda may be mistaken for the main trunk, especially if enlarged, from 
 the collateral circulation having become established; this may be avoided by directing the 
 incision externally toward the Biceps, rather than inward or backward toward the Triceps. 
 
 The lower part of the brachial artery is of interest in a surgical point of view, on account 
 of the relation which it bears to the veins most commonly opened in venesection. Of these 
 vessels, the median basilic is the largest and most prominent, and, consequently, the one usually 
 selected for the operation. It should be remembered that this vein runs parallel with the 
 brachial artery, from which it is separated by the bicipital fascia, and that care should be taken 
 in opening the vein not to carry the incision too deeply, so as to endanger the artery. 
 
 Collateral Circulation. — After the application of a ligature to the brachial artery in the 
 upper third of the arm, the circulation is carried on by branches from the circumflex and sub- 
 scapular arteries, anastomosing with ascending branches from the superior profunda. If the 
 brachial is tied helow the origin of the profunda arteries, the circulation is maintained by the 
 branches of the profundse, anastomosing with the recurrent radial, ulnar, and interosseous 
 arteries. In two cases described by Mr. South,' in which the brachial artery had been tied some 
 time previously, in one "a long portion of the artery had been obliterated, and sets of vessels 
 are descending on either side from above the obliteration, to be received into others which ascend 
 in a similar manner from below it. In the other the obliteration is less extensive, and a single 
 curved artery about as bi^ as a crow-quill passes from the upper to the lower open part of the 
 artery." 
 
 Branches. — The branches of the brachial artery are — the 
 
 Superior Profunda. Inferior Profunda. 
 
 Nutrient. Anastomotica Magna. 
 
 Muscular. 
 
 The Superior Profunda Artery (a. profunda hrachii) arises from the inner and 
 back part of the brachial, just below the lower border of the Teres major, and 
 passes backward to the interval between the outer and inner heads of the Triceps 
 muscle; accompanied by the musculo-spiral nerve it winds around the back part of 
 the shaft of the humerus in the spiral groove, between the outer head of the Triceps 
 and the bone, to the outer side of the humerus, where it reaches the external inter- 
 muscular septum and divides into two terminal branches. One of these pierces 
 the external intermuscular septum, and descends, in company with the musculo- 
 spiral nerve, to the space between the Brachialis anticus and Supinator longus, 
 where it anastomoses with the recurrent branch of the radial artery; while the 
 other, much the larger of the two, descends along the back of the external inter- 
 muscular septum to the back of the elbow-joint, where it anastomoses with the 
 posterior interosseous recurrent, and across the back of the humerus with the pos- 
 terior ulnar recurrent, the anastomotica magna, and inferior profunda (Fig. 415). 
 The superior profunda supplies the Triceps muscle and gives off a nutrient artery 
 which enters the bone at the upper end of the musculo-spiral groove. Near its 
 commencement it sends off a branch which passes upward between the external 
 and long heads of the Triceps muscle to anastomose with the posterior circumflex 
 
 ' Chelius's Surgery, vol. ii. p. 254. See also White'."? engravings, referred to by Mr. South, of the anastomos- 
 ing branches after ligature of the brachial, in White's Cases in Surgery. Porta also gives a case (with drawings) 
 of the circulation after ligature of both brachial and radial (Alterazioni Patoligiche delle Arterie). — Ed. of 15th 
 English edition. 
 
656 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 Radial recurrent.-^ 
 
 $\l 
 
 
 X 
 
 
 o 
 
 
 J 
 
 
 c 
 
 
 e 
 
 
 f 
 
 ' 
 
 < 
 
 
 z 
 
 
 'i*'l 
 
 
 III 
 
 artery, and, while in the groove, a small branch which accompanies a branch of 
 the musculo-spiral nerve through the substance of the Triceps muscle and ends 
 
 in the Anconeus below the outer 
 condyle of the humerus. 
 
 The Nutrient Artery (a. nutricia 
 humeri) of the shaft of the humerus 
 arises from the brachial, about the 
 middle of the arm. Passing down- 
 ward it enters the nutrient canal of 
 that bone near the insertion of the 
 Coraco-brachialis muscle. 
 
 The Inferior Profunda (a. col- 
 lateralis ulnar is superior), of small 
 size, arises from the brachial, a little 
 below the middle of the arm; pierc- 
 ing the internal intermuscular sep- 
 tum, it descends on the surface of 
 the inner head of the Triceps mus- 
 cle to the space between the inner 
 condyle and olecranon, accompanied 
 by the ulnar nerve, and terminates 
 by anastomosing with the posterior 
 ulnar recurrent and anastomotica 
 magna. It sometimes supplies a 
 branch to the front of the internal 
 condyle, which anastomoses with 
 the anterior ulnar recurrent. 
 
 The Anastomotica Magna (a. 
 collateralis ulnaris inferior) arises 
 from the brachial about two inches 
 above the elbow-joint. It passes 
 transversely inward upon the Bra- 
 chialis anticus, and, piercing the 
 internal intermuscular septum,winds 
 round the back of the humerus be- 
 tween the Triceps and the bone, 
 forming an arch above the olecranon 
 fossa by its junction with the poste- 
 rior articular branch of the superior 
 profunda. As this vessel lies on the 
 Brachialis anticus, branches ascend 
 to join the inferior profunda, and 
 others descend in front of the inner 
 condyle to anastomose with the an- 
 terior ulnar recurrent. Behind the 
 internal condyle an offset is given 
 off which anastomoses with the infe- 
 rior profunda and posterior ulnar 
 recurrent arteries and supplies the 
 Triceps. 
 
 The Muscular (rami muscidares) 
 are three or four large branches, 
 which are distributed to the muscles in the course of the artery. They supply 
 the Coraco-brachialis, Biceps, and Brachialis anticus muscles. 
 
 Deep branch 
 of ulnar. 
 
 Superficialis volse 
 
 Fig. 413. — The radial and ulnar arteries. 
 
THE BADIAL ABTEBY 657 
 
 The Anastomosis around the Elbow-joint (Fig. 415). — The vessels engaged 
 in this anastomosis may be conveniently divided into those situated in front and 
 behind the internal and external condyles. The branches anastomosing in front 
 of the internal condyle are the anastomotica magna, the anterior ulnar recurrent, 
 and the anterior terminal branch of the inferior profunda. Those behind the in- 
 ternal condyle are the anastomotica magna, the posterior ulnar recurrent, and the 
 posterior terminal branch of the inferior profunda. The branches anastomosing 
 in front of the external condyle are the radial recurrent and the anterior terminal 
 branch of the superior profunda. Those behind the external condyle (perhaps 
 more properly described as being situated between the external condyle and the 
 olecranon) are the anastomotica magna, the interosseous recurrent,and the posterior 
 terminal branch of the superior profimda. There is also a large arch of anasto- 
 mosis above the olecranon, formed by the interosseous recurrent, joining with the 
 anastomotica magna and posterior ulnar recurrent. 
 
 From this description it will be observed that the anastomotica magna is the 
 vessel most engaged, the only part of the anastomosis in which it is not employed 
 being that in front of the external condyle. 
 
 The Radial Artery (A. Radialis) (Figs. 413, 414). 
 
 The radial artery appears, from its direction, to be the continuation of the 
 brachial, but in size it is smaller than the ulnar. It commences at the bifurcation of 
 the brachial, just below the bend of the elbow, and passes alongthe radial side of the 
 forearm to the wrist; it then winds backward, round the outer side of the carpus, 
 beneath the extensor tendons of the thumb, to the upper end of the space between 
 the metacarpal bones of the thumb and index finger, and finally passes forward, 
 between the two heads of the First dorsal interosseous muscle, into the palm of the 
 hand, where it crosses the metacarpal bones to the ulnar border of the hand, to form 
 the deep palmar axch. At its termination it inosculates with the deep branch of the 
 ulnar artery. The relations of this vessel may thus be conveniently divided into 
 three parts — viz., in the forearm, at the back of the wrist, and in the hand. 
 
 Relations. — In the forearm this vessel extends from opposite the neck of the 
 radius to the forepart of the styloid process, being placed to the inner side of the 
 shaft of the bone above and in front of it below. It is overlapped in the upper 
 part of its course by the fleshy belly of the Supinator longus muscle; throughout 
 the rest of its course it is superficial, being covered by the integument, the super- 
 ficial and deep fasciae. In its course downward it lies upon the tendon of the 
 Biceps, the Supinator brevis, the Pronator radii teres, the radial origin of the 
 Flexor sublimis digitorum, the Flexor longus pollicis, the Pronator quadratus, and 
 the lower extremity of the radius. In the upper third of its course it lies between 
 the Supinator longus and the Pronator radii teres; in the lower two-thirds, between 
 the tendons of the Supinator longus and the Flexor carpi radialis. The radial 
 nerve lies close to the outer side of the artery in the middle third of its course, 
 and some filaments of the musculo-cutaneous nerve, after piercing the deep fascia, 
 run along the lower part of the artery as it winds round the wrist. The vessel is 
 accompanied by venje comites throughout its whole course. 
 
 Plan of the Relations of the Radial Artery in the Forearm. 
 
 In front. 
 Skin, superficial and deep fasciae. 
 Supinator longus. 
 
 Inner side. f Radial \ Outer side. 
 
 Pronator radii teres. I Foreara" ) Supinator longus. 
 
 Flexor carpi radialis. V / Radial nerve (middle third). 
 
658 THE BLOOD -VASCULAR SYSTEM 
 
 Behind. 
 Tendon of Biceps. 
 Supinator brevis. 
 Pronator radii teres. 
 Flexor sublimis digitorum. 
 Flexor longus pollicis. 
 Pronator quadratus. 
 Radiias. 
 
 At the wrist, as it winds round the outer side of the carpus from the styloid 
 process to the first interosseous space, it Hes upon the external lateral ligament, 
 and then upon the scaphoid bone and trapezium, being covered by the extensor 
 tendons of the thumb, subcutaneous veins, some filaments of the radial nerve, and 
 the integument. It is accompanied by two veins and a filament of the musculo- 
 cutaneous nerve. 
 
 In the hand it passes from the upper end of the first interosseous space, 
 between the heads of the Abductor indicis or First dorsal interosseous muscle, 
 transversely across the palm, to the base of the metacarpal bone of the little 
 finger, where it inosculates with the communicating branch from the ulnar artery, 
 forming the deep palmax arch. 
 
 The Deep Palmar Arch {arcus volaris profundus) (Fig. 414). — It lies upon the 
 carpal extremities of the metacarpal bones and the Interossei muscles, being 
 covered by the Adductor obliquus pollicis, the flexor tendons of the fingers, the 
 Lumbricales, the Opponens, and Flexor brevis minimi digiti. Alongside of it is 
 the deep branch of the ulnar nerve, but running in the opposite direction; that 
 is to say, from within outward. The branches of the deep palmar arch are the 
 palmar interosseous, perforating and palmar recurrent vessels (page 660) . 
 
 Peculiarities. — The origin of the radial artery, according to Quain, is, in nearly one case 
 in eight, higher than usual ; more frequently arising from the axillary or upper part of the brachial 
 than from the lower part of this vessel. The variations in the position of this vessel in the arm 
 and at the bend of the elbow have been already mentioned. In the forearm it deviates less fre- 
 quently from its position than the ulnar. It has been found lying over the fascia instead of 
 beneath it. It has also been observed on the surface of the Supinator longus, instead of under 
 its inner border; and in turning round the wrist it has been seen lying over, instead of beneath, 
 the extensor tendons of the thumb. 
 
 Surface Marking. — The position of the radial artery in the forearm is represented by a line 
 drawn from the outer border of the tendon of the Biceps in the centre of the hollow in front 
 of the elbow-joint with a straight course to the inner side of the forepart of the styloid process 
 of the radius. 
 
 Surgical Anatomy. — The radial artery is much exposed to injury in its lower third, and is 
 frequently wounded by the hand being driven through a pane of glass, by the slipping of a 
 knife or chisel held in the other hand, and similar accidents. The injury is often followed by 
 a traumatic aneurism, for which the operation of extirpating or laying open the sac after securing 
 the vessel above and below is required. 
 
 The operation of tying the radial artery is required in cases of wounds either of its trunk or 
 of some of its branches, or for aneurism ; and it will be observed that the vessel may be exposed 
 in any part of its course through the forearm without the division of any muscular fibres. The 
 operation in the middle or inferior third of the forearm is easily performed, but in the upper 
 third, near the elbow, it is attended with some difficulty, from the greater depth of the vessel 
 and from its being overlapped by the Supinator longus muscle. 
 
 To tie the artery in the upper third an incision three inches in length should be made through 
 the integument, in a line drawn from the centre of the bend of the elbow to the front of the 
 styloid process of the radius, avoiding the branches of the median vein; the fascia of the arm 
 being divided and the Supinator longus drawn a little outward, the artery will be exposed. The 
 venae comites should be carefully separated from the vessel, and the ligature passed from the 
 radial to the ulnar side. 
 
 In the middle third of the forearm the artery may be exposed by making an incision of similar 
 length on the inner margin of the Supinator longus. In this situation the radial nerve lies in close 
 relation with the outer side of the artery, and should, as well as the veins, be carefully avoided. 
 
 In the lower third the artery is easily secured by dividing the integument and fascia in the 
 interval between the tendons of the Supinator longus and Flexor carpi radialis muscles. 
 
THE RADIAL ABTEBY 659 
 
 Branches (Figs. 413, 414, and 415). — The branches of the radial artery may 
 be divided into three groups, corresponding with the three regions in which the 
 vessel is situated. 
 
 In the 
 Forearm 
 
 Radial Recurrent 
 
 Muscular. w ' i i 
 
 Anterior Radial Carpal ^^ 
 
 Superficialis Vola? 
 
 Posterior Radial Carpal. 
 Metacarpal. 
 Dorsales Pollicis. 
 Dorsalis Indicis. 
 
 Hand 
 
 Princeps Pollicis. 
 Radialis Indicis. 
 Perforating. 
 Palmar Interosseous. 
 Palmar Recurrent. 
 
 The Radial Recurrent (a. recurrens radialis) (Fig. 414) is given off imme- 
 diately below the elbow. It ascends between the branches of the musculo-spiral 
 nerve lying on the Supinator brevis, and then between the Supinator longus and 
 Brachialis anticus, supplying these muscles and the elbow-joint, and anastomosing 
 with the terminal branches of the superior profunda. 
 
 The Muscular Branches {rami musculares) are distributed to the muscles on 
 the radial side of the forearm. 
 
 The Anterior Radial Carpal {ramus carpeus volaris) (Fig. 414) is a small 
 vessel which arises from the radial artery near the lower border of the Pronator 
 quadratus, and, running inward in front of the radius, anastomoses with the ante- 
 rior carpal branch of the ulnar artery. In this way an arterial anastomosis, the 
 anterior carpal arch (rete carpi volare), is formed in front of the wrist; it is joined 
 by branches from the anterior interosseous above, and by recurrent branches from 
 the deep palmar arch below, and gives off branches which descend to supply the 
 articulations of the wrist and carpus. 
 
 The Superficiahs Volae {ramus volaris superficialis) (Fig. 414) arises from the 
 radial artery, just where this vessel is about to wind round the wrist. Running 
 forward, it passes between, occasionally over, the muscles of the thumb, which it 
 supplies, and sometimes anastomoses with the palmar portion of the ulnar artery, 
 completing the superficial palmar arch. This vessel varies considerably in size: 
 usually it is very small, and terminates in the muscles of the thumb; sometimes 
 it is as large as the continuation of the radial. 
 
 The Posterior Radial Carpal {ramus carpeus dorsalis) (Fig. 415) is a small 
 vessel which arises from the radial artery beneath the extensor tendons of the 
 thumb; crossing the carpus transversely to the inner border of the hand, it 
 anastomoses with the posterior carpal branch of the ulnar, forming the posterior 
 carpal arch {rete carpi dorsale), which is joined by the termination of the anterior 
 interosseous artery. From this arch are given off descending branches, the 
 dorsal interosseous arteries {aa. metacarpea; dorsales) for the second, third, and 
 fourth interosseous spaces, which run forward on the Second, Third, and 
 Fourth dorsal interossei muscles, and divide into dorsal digital branches {aa. 
 digital es dorsales), which supply the adjacent sides of the index, middle, ring, 
 and little fingers respectively, communicating with the digital arteries of the 
 superficial palmar arch. The dorsal interosseous arteries anastomose with the 
 perforating branches from the deep palmar arch {rami per for antes) . 
 
 The Dorsales Pollicis (Fig. 415) are two vessels which run along the sides of 
 the dorsal aspect of the thumb. They arise separately, or occasionally by a 
 common trunk, near the base of the first metacarpal bone. 
 
 The Dorsalis Indicis (Fig. 415), also a small branch, runs along the radial side 
 of the back of the index finger, sending a few branches to the Abductor indicis. 
 
660 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 Anastomotica, 
 magna. 
 
 Radial , 
 recurrent. 
 
 Posterior 
 interosseous. 
 
 Anterior ulnar 
 recurrent. 
 
 Posterior ulnar 
 recurrent. 
 
 The Princeps PoUicis (a. princeps pollicis) (Fig. A\^) arises from the radial just as 
 it turns inward to the deep part of the hand; it descends between the Abductor incHcis 
 
 and Adductor obhquu ponicis,then 
 between the Adductor transversus 
 poUicis and Adductor obUquus 
 pollicis, along the ulnar side of the 
 metacarpal bone of the thumb, to 
 the base of the first phalanx, where 
 it divides into two branches, which 
 run along the sides of the palmar 
 aspect of the thumb, and form an 
 arch on the palmar surface of the 
 last phalanx, from which branches 
 are distributed to the integument 
 and pulp of the thumb. 
 
 The Radialis Indicis (a. volaris 
 indicis radialis) (Fig. 414) arises 
 close to the preceding, descends 
 between the Abductor indicis and 
 Adductor transversus pollicis, and 
 runs along the radial side of the 
 index finger to its extremity, where 
 it anastomoses with the collateral 
 digital artery from the superficial 
 palmar arch. At the lower border 
 of the Adductor transversus pollicis 
 this vessel anastomoses with the 
 princeps pollicis, and gives a com- 
 municating branch to th^ super- 
 ficial palmar arch. 
 
 The Perforating Arteries {rami 
 perforantes) (Fig. 414), three in 
 number, pass backward from the 
 deep palmar arch between the 
 heads of the last three Dorsal inter- 
 ossei muscles, to inosculate with 
 the dorsal interosseous arteries. 
 
 The Palmar Interosseous (aa. 
 
 metacarpecB volar es) (Fig. 414), three 
 
 or four in number, arise from the 
 
 convexity of the deep palmar arch; 
 
 they run forward upon the Inter- 
 
 ossei muscles,and anastomose at the 
 
 clefts of the fingers with the digital 
 
 branches of the superficial arch. 
 
 The Palmar Recurrent Branches arise from the concavity of the deep palmar 
 
 arch. They pass upward in front of the wrist, supplying the carpal articulations 
 
 and anastomosing with the anterior carpal arch. 
 
 MiisciUar. 
 
 Anterior carpal. 
 Superficialis volse. 
 
 Muscular. 
 
 Anterior carpal. 
 
 Deep branch of 
 jdnar. 
 
 Fig. 414. — Ulnar and radial arteries. Deep view. 
 
 The Ulnar Artery (A. Uhiaris) (Figs. 413, 414). 
 
 The ulnar artery, the larger of the two terminal branches of the brachial, 
 commences a little below the bend of the elbow, and crosses obliquely the 
 
THE ULNAR ARTERY 661 
 
 inner side of the forearm to the commencement of its lower half; it then 
 runs along its ulnar border to the wrist, crosses the annular ligament on the 
 radial side of the pisiform bone, and immediately beyond this bone divides into 
 two branches which enter into the formation of the superficial and deep palmar 
 arches. 
 
 Relations. In the Foreaxm. — In its upper half it is deeply seated, being cov- 
 ered by all the superficial Flexor muscles, excepting the Flexor carpi ulnaris; the 
 median nerve is in relation with the inner side of the artery for about an inch and 
 then crosses the vessel, being separated from it by the deep head of the Pronator 
 radii teres; it lies upon the Brachialis anticus and Flexor profundus digitorum 
 muscles. In the lower half of the forearm it lies upon the Flexor profundus, being 
 covered by the integument, the superficial and deep fasciae, and is placed between 
 the Flexor carpi ulnaris and Flexor sublimis digitorum muscles. It is accompanied 
 by two venae comites; the ulnar nerve lies on its inner side for the lower two- 
 thirds of its extent, and a small branch from the nerve descends on the lower part 
 of the vessel to the palm of the hand. 
 
 Plan of Relations of the Ulnar Artery in the Forearm. 
 
 In front. 
 Superficial layer of flexor muscles. ) yj , ,. 
 
 Median nerve. ) "" 
 
 Superficial and deep fasciae. Lower half. 
 
 Inner side. I Ulnar \ Outer side. 
 
 Artery in ,,..,.. 
 
 Flexor carpi ulnaris. \ Forearm, y Flexor sublmus digitorum. 
 
 Ulnar nerve (lower two-thirds). \ / 
 
 Behind. 
 Brachialis anticus. 
 Flexor profundus digitorum. 
 
 At the wrist (Fig. 413) the ulnar artery is covered by the integument and fascia, 
 and lies upon the anterior annular ligament. On its inner side is the pisiform bone. 
 The ulnar nerve lies at the inner side, and somewhat behind the artery; here the 
 nerve and artery are crossed by a band of fibres, which extends from the pisiform 
 bone to the anterior annular ligament. 
 
 Peculiarities. — The ulnar artery has been found to vary in its origin nearly in the propor- 
 tion of one in thirteen cases, in one case arising lower than usual, about two or three inches 
 below the elbow, and in all other cases much higher, the brachial being a more frequent source 
 or origin than the axillary. 
 
 Variations in the position of this vessel are more frequent than in the radial. When its origin 
 is normal the course of the vessel is rarely changed. When it arises high up it is almost invaria- 
 bly superficial to the Flexor muscles in the forearm, lying commonly beneath the fascia, more 
 rarely between the fascia and integument. In a few cases its position was subcutaneous in the 
 upper part of the forearm, subaponeurotic in the lower part. 
 
 Surface Marking.— On account of the curved direction of the ulnar artery the line on the 
 surface of the body which indicates its course is somewhat complicated. First, draw a line from 
 the front of the internal condyle of the humerus to the radial side of the pisiform bone; the 
 lower two-thirds of this line represents the course of the middle and lower third of the ulnar 
 artery. Secondly, draw a line from the centre of the antecubital space to the junction of the 
 upper and middle third of the first line; this represents the course of the upper third of the 
 artery. 
 
 Surgical Anatomy.— The application of a ligature to this vessel is required in cases of wound 
 of the artery or of its branches, or in consequence of aneurism. In the upper half of the fore- 
 arm the artery is deeply seated beneath the superficial flexor muscles, and the application of a 
 ligature in this situation is attended with some difficulty. An incision is to be made in the 
 course of a line drawn from the front of the internal condyle of the humerus to the outer side 
 
662 THE BLOOD VASCULAR SYSTEM 
 
 of the pisiform bone, so that the centre of the incision is three fingers' breadth below the internal 
 condyle. The skin and superficial fascia having been divided and the deep fascia exposed, 
 the white line which separates the Flexor carpi ulnaris from the other flexor muscles is to be 
 sought for, and the fascia incised in this line. The Flexor carpi ulnaris is now to be carefully 
 separated from the other muscles, when the ulnar nerve will be exposed, and must be drawn 
 aside. Some little distance below the nerve the artery will be found accompanied by its venae 
 comites, and it may be ligatured by passing the needle from within outward. In the middle and 
 lower third of the forearm this vessel may be easily secured by making an incision on the radial 
 side of the tendon of the Flexor carpi ulnaris: the deep fascia being divided, and the Flexor 
 carpi ulnaris and its companion muscle, the Flexor sublimis, being separated from each other, 
 the vessel will be exposed, accompanied by its venae comites, the ulnar nerve lying on its inner 
 side. The veins being separated from the artery, the ligature should be passed from the ulnar 
 to the radial side, taking care to avoid the ulnar nerve. 
 
 Branches (Figs. 413, 414, and 415). — The branches of the ulnar artery may 
 be arranged in the following groups: 
 
 Forearm 
 
 Wrist 
 Hand 
 
 Anterior Ulnar Recurrent. 
 
 Posterior Ulnar Recurrent. 
 
 T . I Anterior Interosseous. 
 
 Interosseous { -n . • x ^ 
 
 ( rosterior Interosseous. 
 
 Muscular. 
 
 Anterior Carpal. 
 
 Posterior Carpal. 
 
 Deep Palmar or Communicating. 
 
 . Superficial Palmar Arch. 
 
 The Anterior Ulnar Recurrent (a. recurrentes ulnaris anterior) (Fig. 414) 
 arises immediately below the elbow-joint, passes upward and inward between the 
 Brachialis anticus and Pronator radii teres, supplies twigs to those muscles, and, 
 in front, of the inner condyle anastomoses with the anastomotica magna and 
 inferior profunda. 
 
 The Posterior Ulnar Recurrent (a. recurrentes ulnaris posterior) (Figs. 414 and 
 415) is much larger, and arises somewhat lower than the preceding. It passes 
 backward and inward, beneath the Flexor sublimis, and ascends behind the inner 
 condyle of the humerus. In the interval between this process and the olecranon 
 it lies beneath the Flexor carpi ulnaris, and ascending between the heads of that 
 muscle, in relation with the ulnar nerve; it supplies the neighboring muscles and 
 joint, and anastomoses with the inferior profunda, anastomotica magna, and 
 interosseous recurrent arteries. 
 
 The Interosseous Artery (a. interossea communis) (Fig. 414) is a short trunk 
 about half an inch in length, and of considerable size, which arises immediately, 
 below the tuberosity of the radius, and, passing backward to the upper border ol 
 the interosseous membrane, divides into two branches, the anterior and posterioi 
 interosseous. 
 
 The Anterior Interosseous (a. interossea volaris) (Fig. 414) passes down the fore- 
 arm on the anterior surface of the interosseous membrane, to which it is connected 
 by a thin aponeurotic arch. It is accompanied by the interosseous branch of the 
 median nerve, and overlapped by the contiguous margins of the Flexor profundus 
 digitorum and Flexor longus pollicis muscles, giving off in this situation muscular 
 branches and the nutrient arteries of the radius and ulna. At the upper border 
 of the Pronator quadratus a branch, anterior communicating artery, descends 
 beneath the muscle to anastomose in front of the carpus with the anterior carpal 
 arch. The continuation of the artery passes behind the Pronator quadratus, and, 
 piercing the interosseous membrane, reaches the back of the forearm, and anasto- 
 moses with the posterior interosseous artery (Fig. 415). It then descends to the 
 back of the wrist to join the posterior carpal arch. The anterior interosseous gives 
 
THE ULNAR ARTERY 
 
 663 
 
 off a long, slender branch, the median artery or artery comes nervi mediana 
 (a. mediana), which accompanies the median nerve and gives offsets to its sub- 
 stance. This artery is some- 
 
 _ Descending branch from 
 superior profunda. 
 
 Anastomotica 
 magna. 
 
 Posterior ulnar 
 recurrent. 
 
 Posterior interosseous. 
 
 times much enlarged, and ac- 
 companies the nerve into the 
 palm of the hand. 
 
 The Posterior Interosseous 
 Artery (a. interossea dorsalis) 
 (Figs. 414 and 415) passes 
 backward through the inter- 
 val between the oblique liga- 
 ment and the upper border of 
 the interosseous membrane. 
 It appears between the con- 
 tiguous borders of the Supina- 
 tor brevis and the Extensor 
 ossis metacarpi poUicis, and 
 runs down the back part of 
 the forearm, between the su- 
 perficial and deep layer of 
 jnuscles, to both of which it 
 distributes branches. At the 
 lower part of the forearm it 
 anastomoses with the termina- 
 tion of the anterior interosse- 
 ous artery. Then, continuing 
 its course over the head of 
 the ulna, it joins the posterior 
 carpal branch of the ulnar 
 artery. This artery gives off, 
 near its origin, the interosseous 
 recurrent branch. 
 
 The interosseous recurrent 
 artery (a. interossea recurrens) 
 (Fig.415)is a large vessel which 
 ascends to the interval between 
 the external condyle and olec- 
 ranon, on or through the fibres 
 of the Supinator brevis, but 
 beneath the Anconeus, anas- 
 tomosing with a branch from 
 the superior profunda, and 
 with the posterior ulnar recur- 
 rent and anastomotica magna. 
 
 The Muscular Branches 
 {rami musculares) are distri- 
 buted to the muscles along 
 the ulnar side of the forearm. 
 
 The Anterior Carpal {ramus carpeus volaris) (Fig. 414) is a small vessel 
 which crosses the front of the carpus beneath the tendons of the Flexor pro- 
 fundus, and inosculates with a corresponding branch of the radial artery. 
 
 The Posterior Carpal {ramus carpem dorsalis) (Fig. 415) arises immediately 
 above the pisiform bone, and winds backward beneath the tendon of the Flexor 
 carpi ulnaris : it passes across the dorsal surface of the carpus beneath the extensor 
 
 Posterior carpal 
 
 (ulnar). 
 
 Termination of an- 
 terior interosseous. 
 
 Posterior carpal 
 
 {radial). 
 
 Radial. 
 
 Dorsalis pollicis. 
 salis indicis. 
 
 Fig. 415. — Arteries of the back of the forearm and.hand. 
 
664 THE BLOOD -VASCULAR SYSTE3I 
 
 tendons, anastomosing with a corresponding branch of the radial artery, and 
 forming the posterior carpal arch {rete carpi dor sale) (Fig. 415). Immediately after 
 its origin it gives off a small branch which runs along the ulnar side of the meta- 
 carpal bone of the little finger, forming one of the metacarpal arteries, and supplies 
 the ulnar side of the dorsal surface of the Uttle finger. 
 
 The Deep or Communicating Branch to the Deep Palmar Arch {ramus 
 volaris ^profundus) (Fig. 414) passes deeply inward between the Abductor minimi 
 digiti and Flexor brevis minimi digiti, near their origins; it anastomoses with the 
 termination of the radial artery, completing the deep palmar arch. 
 
 The continuation of the trunk of the ulnar artery in the hand forms the greater 
 part of the superficial palmar arch. 
 
 The Superficial Palmar Arch (arcus volaris superficialis) (Fig. 413) is formed 
 by the ulnar artery in the hand, and is completed on the outer side by this vessel 
 anastomosing with a branch from the radialis indicis, though sometimes the arch 
 is completed by the ulnar anastomosing with the superficialis volte or the princeps 
 pollicis of the radial artery. The arch passes across the palm, describing a curve, 
 with its convexity forward, to the space between the ball of the thumb and the 
 index finger, where the above-mentioned anastomosis takes place. 
 
 Relations. — The superficial palmar arch is covered by the skin, the Palmaris 
 brevis, and the palmar fascia. It lies upon the annular ligament, the Flexor 
 brevis of the little finger, the tendons of the superficial flexor of the fingers, and 
 the divisions of the median and ulnar nerves. 
 
 Plan of the Relations of the Superficial Palmar Arch. 
 
 In front. 
 Skin. 
 
 Palmaris brevis. 
 Palmar fascia. 
 
 Behind. 
 Annular ligament. 
 Flexor brevis of little finger. 
 Superficial flexor tendons. 
 Divisions of median and ulnar nerves. 
 
 Branches. — The branches of the Superficial Palmar Arch are the 
 
 Digital. 
 
 The Digital Branches (aa. digitales volares communes) (Fig. 413), four in number, 
 are given off from the convexity of the superficial palmar arch. They supply the 
 ulnar side of the little finger and the adjoining sides of the little, ring, middle, and 
 index fingers, the radial side of the index finger and thumb being supplied from 
 the radial artery. The digital arteries at first lie superficial to the flexor tendons, 
 but as they pass forward with the digital nerves to the clefts between the fingers 
 they lie between them, and are there joined by the interosseous branches from the 
 deep palmar arch. The digital arteries on the sides of the fingers lie beneath the 
 digital nerves ; and about the middle of the last phalanx the two branches for each 
 finger form an arch, from the convexity of which branches pass to supply the 
 pulp of the finger. 
 
THE THORACIC AORTA 665 
 
 Surface Marking. — The superficial palmar arch is represented by a curved line, starting 
 from the outer side of the pisiform bone and carried downward as far as the middle third of 
 the palm, and then curved outward on a level with the upper end of the cleft between the thumb 
 and index finger. The deep palmar arch is situated about half an inch nearer to the carpus. 
 
 Surgical Anatomy. — Wounds of the palmar arches are of special interest, and are always 
 difficult to deal with. When the superficial arch is wounded it is generally possible, by enlarging 
 the wound if necessary, to secure the vessel and tie it; or in cases where it is found impossible to 
 encircle the vessel with a ligature, a pair of haemostatic forceps may be applied and left on for 
 twenty-four or forty-eight hours. Wounds of the deep arch are not so easily dealt with. It may 
 be possible to secure the vessel by ligature or by forcipressure forceps, which may be left on; 
 or, failing in this, the wound may be carefully plugged with gauze and an outside dressing care- 
 fully bandaged on. The plug should be allowed to remain untouched for three or four days. 
 In wounds of the deep palmar arch a ligature may be applied to the bleeding points from the 
 dorsum of the hand by resection of the upper part of the third metacarpal bone. It is useless 
 in these cases to ligate one of the arteries of the forearm alone, and indeed simultaneous liga- 
 tion of both radial and ulnar arteries above the wrist is often unsuccessful, on account of the 
 anastomosis carried on by the carpal arches. Therefore, if unable to ligate the divided ends 
 of the arch, upon the failure of pressure to arrest hemorrhage, it is expedient to apply a ligature 
 to the brachial artery. 
 
 ARTERIES OF THE TRUNK. 
 THE DESCENDING AORTA (Figs. 416, 417). 
 
 The descending aorta is divided into two portions, the thoracic and abdominal, 
 in correspondence with the two great cavities of the trunk in which it is situated. 
 
 The Thoracic Aorta (Aorta Thoracalis) (Fig. 416). 
 
 The thoracic aorta commences at the lower border of the fourth dorsal 
 vertebra, on the left side, and terminates at the aortic opening in the Diaphragm, 
 in front of the lower border of the last dorsal vertebra. At its commencement it 
 is situated on the left side of the spine; it approaches the median line as it 
 descends, and at its termination lies directly in front of the spinal column. The 
 direction of this vessel being influenced by the spine, upon which it rests, it 
 describes a curve which is concave forward in the dorsal region. As the branches 
 given off from it are small, the diminution in the size of the vessel is inconsider- 
 able. It is contained in the back part of the posterior mediastinum. 
 
 Relations. — It is in relation, in front, from above downward, with the root of 
 the left lung, the pericardium, the cesophagus, and the Diaphragm: behind, with 
 the vertebral column and the vense azygos minor; on the right side, with the vena 
 azygos major and thoracic duct; on the lejt side, with the left pleura and lung. 
 The oesophagus, with its accompanying nerves, lies on the right side of the aorta 
 above; but at the lower part of the thorax it gets in front of the aorta, and close 
 to the Diaphragm is situated to its left side. 
 
 Plan of the Relations of the Thoracic Aorta. 
 
 In front. 
 Root of left lung. 
 
 
 Pericardium. 
 
 
 
 (Esophagus. 
 Diaphragm. 
 
 
 Right side. 
 
 y^' ^ 
 
 Left side. 
 
 (Esophagus (above). 
 Vena azygos major. 
 Thoracic duct. 
 
 1 Thoracic \ 
 1 Aorta. 1 
 
 Behind. 
 
 Pleura. 
 Left lung. 
 (Esophagus (below) 
 
 Vertebral column. 
 
 
 Superior 
 
 and inferior azygos minor 
 
 veins. 
 
666 THE BLOOD-VASCULAB SYSTEM 
 
 The aorta is occasionally found to be obliterated at a particular spot — viz., at the junction of 
 the arch with the thoracic aorta just below the ductus arteriosus. Whether this is the result of 
 disease or of congenital malformation is immaterial to our present purpose; it affords an interest- 
 ing opportunity of observing the resources of the collateral circulation. The course of the anas- 
 tomosing vessels, by which the blood is brought from the upper to the lower part of the artery, 
 will be found well described in an account of two cases in the Pathological Transactions, vols. viii. 
 and X. In the former (p. 162) Mr. Sydney Jones thus sums up the detailed description of the 
 anastomosing vessels: "The principal communications by which the circulation was carried on, 
 were — Firstly, the internal mammary, anastomosing with the intercostal arteries, with the phrenic 
 of the abdominal aorta by means of the musculo-phrenic and comes nervi phrenici, and largely 
 with the deep epigastric. Secondly, the superior intercostal, anastomosing anteriorly by means 
 of a large branch with the first aortic intercostal, and posteriorly with the posterior branch of the 
 same artery. Thirdly, the inferior thyroid, by means of a branch about the size of an ordinary 
 radial, formed a communication with the first aortic intercostal. Fourthly, the transversalis colli, 
 by means of very large communications with the posterior branches of the intercostals. Fifthly, 
 the branches (of the subclavian and axillary) going to the side of the chest were large, and anas- 
 tomosed freely with the lateral branches of the intercostals." In the second case also (vol. x. 
 p. 97) Mr. Wood describes the anastomoses in a somewhat similar manner, adding the remark 
 that "the blood which was brought into the aorta through the anastomoses of the intercostal 
 arteries appeared to be expended principally in supplying the abdomen and pelvis, while the 
 supply to the lower extremities had passed through the internal mammary and epigastrics." 
 
 Surgical Anatomy. — The student should now consider the effects likely to be produced by 
 aneurism of the thoracic aorta, a disease of common occurrence. When we consider the great 
 depth of the vessel from the surface and the number of important structures which surround it 
 on every side, it may easily be conceived what a variety of obscure symptoms may arise from dis- 
 ease of this part of the arterial system, and how they may be liable to be mistaken for those of 
 other affections. Aneurism of the thoracic aorta most usually extends backward along the left 
 side of the spine, producing absorption of the bodies of the vertebrae, with curvature of the spine; 
 whilst the irritation or pressure on the cord will give rise to pain, either in the chest, back, or 
 loins, with radiating pain in the left upper intercostal spaces, from pressure on the intercostal 
 nerves; at the same time the tumor may project backward on each side of the spine, beneath the 
 integument, as a pulsating swelling, simulating abscess connected with diseased bone, or it may 
 displace the oesophagus and compress the lung on one or the other side. If the tumor extend 
 forward, it may press upon and displace the heart, giving rise to palpitation and other symptoms 
 of disease of that organ; or it may displace, or even compress, the oesophagus, causing pain and 
 difficulty of swallowing, as in stricture of that tube; and ultimately even open into it by ulcera- 
 tion, producing fatal hemorrhage. If the disease extends to the right side, it may press upon 
 the thoracic duct; or it may burst into the pleural cavity or into the trachea or lung; and, lastly, 
 it may open into the posterior mediastinum. 
 
 Branches. — Branches of the thoracic aorta supply the thoracic viscera. 
 They are known as rami viscerales. The rami viscerales are the bronchial, oesoph- 
 ageal, pericardial, and mediastinal arteries. Other branches of the thoracic aorta 
 supply the walls of the chest. They are known as rami parietales or intercostal arteries. 
 
 The Bronchial Arteries (aa. hronchiales) are the nutrient vessels of the lungs, 
 and vary in number, size, and origin. That of the right side arises from the first 
 aortic intercostal, or by a common trunk with the left bronchial from the front of 
 the thoracic aorta. Those of the left side, usually two in number, arise from the 
 thoracic aorta, one a little lower than the other. Each vessel is directed to the 
 back part of the corresponding bronchus along which it runs, dividing and sub- 
 dividing along the bronchial tube, supplying them, the cellular tissue of the lungs, 
 the bronchial glands, and the oesophagus. 
 
 The (Esophageal Arteries {aa. oesophagece), usually four or five in number, 
 arise from the front of the aorta, and pass obliquely downward to the oesophagus, 
 forming a chain of anastomoses along that tube, anastomosing with the oesoph- 
 ageal branches of the inferior thyroid arteries above, and with ascending branches 
 from the phrenic and gastric arteries below. 
 
 The Pericardiac (rami pericardiaci) are a few small vessels, irregular in their 
 origin, distributed to the pericardium. 
 
 The Posterior Mediastinal Arteries (rami mediastinales) are numerous 
 small vessels which supply the glands and loose areolar tissue in the mediastinum. 
 
THE THORACIC AORTA 
 
 667 
 
 The lower mediastinal branches are known as the superior phrenic arteries {aa. 
 phrenicoB superiores), and are distributed to the posterior portion of the Diaphragm. 
 The Intercostal Arteries (aa. intercostales) (Fig. 416) arise from the back of the 
 aorta. The aortic intercostals are usually nine in number on each side, the two 
 superior intercostal spaces being supplied 
 by the superior intercostal, a branch of the 
 subclavian. The second space usually 
 receives a considerable branch from the 
 first aortic intercostal, which joins with 
 the branch from the superior intercostal 
 of the subclavian. The branch which runs 
 along the lower border of the last rib is 
 named the subcostal artery. The right 
 intercostals are longer than the left, on 
 account of the position of the aorta on th( 
 left side of the spine: they pass outward, 
 across the bodies of the vertebrae, to the 
 intercostal spaces, being covered by the 
 pleura, the oesophagus, thoracic duct, 
 sympathetic nerve, and the vena azygos 
 major; the left, passing outward, are 
 crossed by the sympathetic; the upper two 
 are also crossed by the superior inter- 
 costal vein, the lower by the azygos minor 
 veins. In each intercostal space the artery 
 passes outward, the External intercostal 
 muscle being behind, the pleura and a thin 
 fascia being in front. It then passes be- 
 tween the two layers of Intercostal mus- 
 cles, and, having ascended obliquely to 
 the lower border of the rib above it, is 
 continued forward in the groove on its 
 lower border and anastomoses with the 
 anterior intercostal branches of the in- 
 ternal mammary. The first aortic inter- 
 costal anastomoses with the superior in- 
 tercostal branch of the subclavian, and 
 the last three intercostals pass between 
 the abdominal muscles, inosculating with the epigastric in front and with the 
 phrenic and lumbar arteries. Each intercostal artery is accompanied by a vein and 
 nerve, the former being above, and the latter below, except in the upper inter- 
 costal spaces, where the nerve is at first above the artery. The arteries are pro- 
 tected from pressure during the action of the Intercostal muscles by fibrous arches 
 thrown across, and attached by each extremity to the bone. The lower intercostal 
 arteries are continued anteriorly from the intercostal spaces into the abdominal 
 wall, except the subcostal, which lies throughout its whole course in the abdominal 
 wall, since it is placed below the last rib. They pass behind the costal cartilages 
 between the Internal oblique and Transversalis muscle to the sheath of the Rectus, 
 where they anastomose with the internal mammary and the deep epigastric 
 arteries. Behind, the subcostal artery anastomoses with the first lumbar artery. 
 Branches. — Each intercostal artery gives off numerous muscular branches {rami 
 musculares). 
 
 Lateral cutaneous. Muscular. 
 
 Posterior or dorsal branch. Collateral intercostal. 
 
 Fig. 416. — Thoracic aorta. (Testut.) 
 
66S THE BLOOD -VASCULAR SYSTEM 
 
 Lateral Cutaneous Branches {rami cutanei laterales) come off from each intercostal 
 and take a similar course to that of the lateral cutaneous branch of the intercostal 
 nerve. These arteries are distributed to the walls of the chest and to the mammary 
 gland {rami mammarii laterales). 
 
 Small branches pass to the mammary gland through the fourth, fifth, and sixth 
 interspaces {rami mammarii medialis), and to the skin to the inner side of the 
 nipple {rami cutanei arteriores). 
 
 The portion of the artery considered here as the prolongation of the main trunk 
 is called by Spalteholz and others the anterior branch {ramus anterior). 
 
 The Posterior or Dorsal Branch {ramus posterior) of each intercostal artery passes 
 backward to the inner side of the anterior costo-transverse ligament, and divides 
 into an external branch {ramus cutaneus lateralis), and an internal branch {ramus 
 cutaneus medialis), which are distributed to the muscles and integument of the 
 back. Muscular branches {rami musculares) are given off by the dorsal branch soon 
 after its origin. A spinal branch {ramus spinalis) comes off from the dorsal 
 branch of the intercostal. It traverses the vertebral arches and enters the spinal 
 canal through the intervertebral foramen, is distributed to the spinal cord and 
 its membranes, and to the bodies of the vertebra? in the same manner as the 
 lateral spinal branches from the vertebral. It gives off three branches, the 
 neural, which accompanies the spinal nerve-roots, and is distributed to the mem- 
 branes of the spinal cord. The post-central branch divides into ascending and 
 descending branches, which, anastomosing with similar branches above and 
 below, form a series of vertical arches in the back of the bodies of the verte- 
 brae.^ The prelaminar branch is distributed to "the posterior wall of the spinal 
 canal."^ 
 
 The Collateral Intercostal Branch comes off from the intercostal artery near the 
 angle of the rib, and descends to the upper border of the rib below, along which 
 it courses to anastomose with the anterior intercostal branch of the internal 
 mammary or its branch, the musculo-phrenic. 
 
 The two lower intercostals on each side have not constant collateral branches. 
 Even when present they are of small size and end in the wall of the abdomen. 
 Each collateral intercostal branch gives off muscular branches. 
 
 Surgical Anatomy. — The position of the intercostal vessels should be borne in mind in 
 performing the operation of paracentesis thoracis. The puncture should never be made nearer 
 the middle line posteriorly than the angle of the rib, as the artery crosses the space internal to 
 this point. In the lateral portion of the chest, where the puncture is usually made, the artery 
 lies at the upper part of the intercostal space, and therefore the puncture should be made just 
 above the upper border of the rib forming the lower boundary of the space. 
 
 The Abdominal Aorta (Aorta Abdominalis) (Fig. 417). 
 
 The abdominal aorta commences at the aortic opening of the Diaphragm, in 
 front of the lower border of the body of the last dorsal vertebra, and, descending a 
 little to the left side of the vertebral column, terminates on the body of the fourth 
 lumbar vertebra, commonly a little to the left of the middle line,^ where it 
 divides into the two common iliac arteries. It diminishes rapidly in size, in 
 consequence of the many large branches which it gives off. As it lies upon the 
 bodies of the vertebrae, the curve which it describes is convex forward, the 
 greatest convexity corresponding to the third lumbar vertebra, which is a little 
 above and to the left side of the umbilicus. 
 
 ' Cunningham's Text-book of Anatomy. . ° Ibid- . 
 
 ^ Lord Lister, having accurately examined 30 bodies in order to ascertain the exact point of termmation of 
 this vessel, found it " either absolutely, or almost absolutely, mesial in 15, while in 13 it deviated more or less. 
 totheleft,andin2 was slightly to the right" (System of Surgery, edited by T.Holmes, 2d ed., vol. v. p. 652). 
 — Ed. of 15th English edition. 
 
THE ABDOMINAL AORTA 
 
 669 
 
 Relations.— It is covered, in front, by the lesser omentum and stomach behind 
 which are the branches of the cochac axis and the solar plexus; below these by 
 the splenic vein, the pancreas, the left renal vein, the transverse portion ot he 
 duodenum, the mesentery, and aortic plexus. Behind, it is separated from the 
 lumbar vertebra and intervening disks by the anterior common ligament and lett 
 
 Fig. 417. — The abdominal aorta and its branches. 
 
 lumbar veins. On the right side it is in relation with the inferior vena cava (the 
 right crus of the Diaphragm being interposed above), the vena azygos major, 
 thoracic duct, and right semilunar ganglion; on the left side, with the sympathetic 
 nerve and left semilunar ganglion. 
 
670 
 
 THE BLOOD -VASCULAR SYSTEM 
 Plan of the Relations of the Abdominal Aorta. 
 
 In front. 
 Lesser omentum and stomach. 
 Branches of the coeliac axis and solar plexus. 
 Splenic vein. 
 Pancreas. 
 Left renal vein. 
 Transverse duodenum. 
 Mesentery. 
 Aortic plexus. 
 Right side. 
 Right crus of Diaphragm. / \ Left side 
 
 Inferior vena cava. . "* Aom"*' ' Sympathetic nerve. 
 
 Vena azygos major. \ ' / Left semilunar ganglion. 
 
 Thoracic duct. 
 Right semilunar ganglion. 
 
 Behind. 
 
 Left lumbar veins. 
 
 Vertebral column. 
 
 Surface Marking. — In order to map out the abdominal aorta on the surface of the abdomen, 
 a line must be drawn from the middle line of the body, on a level with the distal extremity of 
 the seventh costal cartilage, downward and slightly to the left, so that it just skirts the umbilicus, 
 to a zone drawn round the body opposite the highest point of the crest of the ilium. This 
 point is generally half an inch below and to the left of the umbilicus, but as the position of this 
 structure varies with the obesity of the individual, it is not a reliable landmark as to the situation 
 of the bifurcation of the aorta. 
 
 Surgical Anatomy. — Aneurisms of the abdominal aorta near the coeliac axis communicate 
 in nearly equal proportion with the anterior and posterior parts of the artery. 
 
 When an aneurismal sac is connected with the back part of the abdominal aorta, it usually 
 produces absorption of the bodies of the vertebrae, and forms a pulsating tumor that presents 
 itself in the left hypochondriac or epigastric regions, and is accompanied by symptoms of dis- 
 turbance in the alimentary canal. Pain is invariably present, and is usually of two kinds — a 
 fixed and constant pain in the back, caused by the tumor pressing on or displacing the branches 
 of the solar plexus and splanchnic nerves; and a sharp lancinating pain, radiating along those 
 branches of the lumbar nerves which are pressed on by the tumor; hence the pain in the loins, 
 the testes, the hypogastrium, and in the lower limb (usually of the left side). This form of 
 aneurism usually bursts into the peritoneal cavity or behind the peritoneum in the left hypo- 
 chondriac region; or it may form a large aneurismal sac, extending down as low as Poupart's 
 ligament; hemorrhage in these cases being generally very extensive, but slowly produced, and 
 not rapidly fatal. 
 
 When an aneurismal sac is connected with the front of the aorta near the coeliac axis it 
 forms a pulsating tumor in the left hypochondriac or epigastric regions, usually attended with 
 symptoms of disturbance of the alimentary canal, as sickness, dyspepsia, or constipation, and 
 is accompanied by pain, which is constant, but nearly always fixed in the loins, epigastrium, or 
 some part of the abdomen; the radiating pain being rare, as the lumbar nerves are seldom 
 implicated. This form of aneurism may burst into the peritoneal cavity or behind the peri- 
 toneum, between the layers of the mesentery, or, more rarely, into the duodenum; it seldom 
 extends backward so as to affect the spine. 
 
 The abdominal aorta has been tied 15 times, and although none of the patients permanently 
 recovered, still, as Prof. Keen's lived 48 days, the possibility of the re-establishment of the 
 circulation is proved. In the lower animals this artery has been often successfully tied. The 
 vessel may be reached in several ways. In the original operation, performed by Sir A. Cooper, 
 in 1817, an incision was made in the linea alba, the peritoneum opened in front, the finger 
 carried down amongst the intestines toward the spine, the peritoneum again opened behind by 
 scratching through the mesentery, and the vessel thus reached. Or either of the operations 
 described below for securing the common iliac artery may, by extending the dissection a suf- 
 ficient distance upward, be made use of to expose the aorta. The chief difficulty in the 
 dead subject consists in isolating the artery in consequence of its great depth; but in the 
 living subject the embarrassment resulting from the proximity of the aneurismal tumor, and 
 the great probability of disease in the vessel itself, add to the dangers and difficulties of this 
 formidable operation so greatly that it is very doubtful whether it ought ever to be performed. 
 
 The collateral circulation would be carried on by the anastomosis between the internal mam- 
 
THE ABDOMINAL AORTA 671 
 
 mary and the deep epigastric; by the free communication between the superior and inferior 
 mesenteries if the Hgature were placed above the latter vessel; or by the anastomosis between 
 the inferior mesenteric and the internal pudic when (as is more common) the point of ligature is 
 below the origin of the inferior mesenteric; and possibly by the anastomoses of the lumbar 
 arteries with the branches of the internal iliac. 
 
 During an amputation at the hip the circulation through the abdominal aorta may be com- 
 manded \>^ an assistant, who throws the entire weight of his body upon his rigidly extended 
 forearm, the fist of which lies directly upon the patient's aorta (Macewen's method). The 
 abdominal tourniquet is no longer used, as modern methods enable the surgeon to do a prac- 
 tically bloodless hi{>joint amputation (Wyeth's method, Senn's method, McBurney's method). 
 
 Branches (Fig. 417). — The branches of the abdominal aorta are — the 
 
 Phrenic f ^^^*^^^- Superior Mesenteric. Ovarian in female. 
 
 Coehac Axisi Hepatic. Suprarenal. Inferior Mesenteric. 
 
 ( Splenic. Renal. Lumbar. 
 
 Spermatic in male. Sacra Media. 
 
 Branches. — ^The branches of the abdominal aorta may be divided into two 
 sets: 1. Those supplying the viscera (rami vicerales). 2. Those distributed to 
 the walls of the abdomen {rami parietales). 
 
 Visceral Branches. Parietal Branches. 
 
 ( Gastric. 
 Cceliac Axiss Hepatic. Inferior Phrenic. 
 
 I Splenic. I^umbar. 
 
 Superior Mesenteric. Sacra Media. 
 
 Inferior Mesenteric. 
 Suprarenal. 
 Renal. 
 Spermatic or Ovarian. 
 
 To expose the coeliac axis raise the liver, draw down the stomach, and then tear through the 
 layers of the lesser omentum. 
 
 The Coeliac Axis or Artery (a. cceliacd) (Figs. 417, 418, and 419). — The coeHae 
 axis is a short thick trunk, about half an inch in length, which arises from the 
 aorta, close to the margin of the opening in the Diaphragm, behind the posterior 
 parietal peritoneum, above the pancreas, and below the twelfth dorsal vertebra, 
 and, passing nearly horizontally forward (in the erect posture), divides into three 
 large branches, the gastric, hepatic, and splenic, occasionally giving off one of the 
 phrenic arteries. 
 
 Relations. — It is covered by the lesser omentum. On the right side it is in 
 relation with the right semilunar ganglion and the lobus Spigelii; on the lejt side, 
 with the left semilunar ganglion and cardiac end of the stomach. Below, it rests 
 upon the upper border of the pancreas. 
 
 The Gastric or Coronary Artery (a. gastrica sinistra) (Figs. 418 and 419), the small- 
 est of the three branches of the coeliac axis, passes upward and to the left side, 
 behind the peritoneum of the lesser peritoneal cavity, raising this portion of the 
 peritoneum into a fold, known as the left or secondary pancreatico -gastric fold. It 
 continues this course until it nearly reaches the lesser curvature of the stomach just 
 below the cardia. It then turns to the front and curves forward to the cardiac 
 orifice of the stomach, distributing branches to the oesophagus which anastomose 
 with the aortic oesophageal arteries; others supply the cardiac end of the stomach, 
 inosculating with branches of the splenic artery; it then passes from left to 
 right, along and upon the lesser curvature of the stomach and beneath the 
 peritoneum to the pylorus, lying in its course between the layers of the lesser 
 omentum, and sometimes dividing into two vessels, which run along each side 
 
672 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 of the lesser curvature. One vascular arch gives branches to the anterior wall 
 of the stomach and the other to the posterior wall (Fig. 886), and both give 
 them to the lesser omentum or the single artery gives branches to both sur- 
 faces of the organ and to the lesser omentum: at its termination it anastomoses 
 with the pyloric branch or the two pyloric branches of the hepatic. It gives off 
 gastric branches to both the anterior and posterior surfaces of the stomach, 
 branches to the lesser omentum, a small hepatic branch, to the left lobe of the liver 
 and oesophageal branches {rami cesophagei) which anastomose with oesophageal 
 branches from the thoracic aorta and the inferior phrenic. 
 
 Oysti^ artery. 
 
 Fig. 418. — The ccsliac axis and its branches, the liver having been raised and the lesser omentum removed. 
 
 The Hepatic Artery (a. hepatica) (Figs. 418 and 419) in the adult is intermediate 
 in size between the gastric and splenic ; in the foetus it is the largest of the three 
 branches of the coeliac axis. It is first directed forward and to the right, in the 
 right pancreatico-gastric fold, to the upper margin of the pyloric end of the 
 stomach, forming the lower boundary of the foramen of Winslow. It then passes 
 upward between the layers of the lesser omentum, and in front of the foramen of 
 Winslow, to the transverse fissure of the liver, where it divides into two branches, 
 right and left, which supply the corresponding lobes of that organ, accompanying 
 the ramifications of the vena portae and hepatic duct. The hepatic artery, in 
 its course along the right border of the lesser omentum, is in relation with the 
 ductus communis choledochus and portal veins, the duct lying to the right of 
 the artery and the vena portse behind. 
 
THE ABD03£INAL AOBTA 
 
 673 
 
 Its branches (Figs. 418 and 419) are — the 
 
 Pyloric. 
 
 r^ , 1 , ,. i Gastro-epiploica Dextra. 
 (jrastro-duodenalis i o 4.- j j to 
 
 ( rancreatico-duodenalis bupenor 
 
 Cystic. 
 
 The pyloric or superior pyloric branch (a. gastrica dextra) arises from the 
 hepatic, above the pylorus, descends between the layers of the lesser omentum 
 to the pyloric end of the stomach, and passes from right to left along its lesser cur- 
 vature, supplying it with branches and inosculating with the gastric branches of 
 the coronary artery. The vessel often divides into two vascular arches to anas- 
 tomose with two vascular arches from the gastric. 
 
 jucHfis 
 
 to Great Omentum. 
 
 Fig. 419. — The coeliac axis and its branches, the stomach having been raised and the transverse mesocolon 
 removed (semi-diagrammatic). 
 
 The gastro-duodenalis (Fig. 419) is a short but large branch, which descends 
 near the pylorus, behind the first portion of the duodenum, and divides at the 
 lower border of this viscus into two branches, the gastro-epiploica dextra and the 
 pancreatico-duodenalis superior. Previous to its division, it gives off two or three 
 small inferior pyloric branches, to the pyloric end of the stomach and pancreas. 
 
 The gastro-epiploica dextra runs from right to left along but distinctly below 
 the greater curvature of the stomach, between the layers of the great omentum, 
 anastomosing about the middle of the lower border of the stomach with the gastro- 
 epiploica sinistra from the splenic artery. This vessel gives off numerous branches, 
 
 43 
 
674 THE BLOOD -VASCULAR SYSTEM 
 
 some of which ascend to supply both surfaces of the stomach, whilst others 
 descend to supply the great omentum {rami epiploici). 
 
 The pancreatico-duodenalis superior descends between the contiguous margins 
 of the duodenum and pancreas. It supplies the head of the pancreas by means 
 of the rami pancreatica, and the duodenum by means of the rami duodenalis, 
 and anastomoses with the inferior pancreatico-duodenal branch of the superior 
 mesenteric artery and with the pancreatic branches of the splenic. 
 
 The cystic artery (a, cystica) (Fig, 418), usually a branch of the right hepatic, 
 passes downward and forward along the cystic duct to the gall-bladder, and 
 divides into two branches, one of which ramifies on its free surface beneath 
 the peritoneum, the other between the gall-bladder and the substance of the 
 liver. 
 
 The Splenic Artery (a. lienalis) (Figs. 418 and 419), in the adult, is the largest of 
 the three branches of the coeliac axis, and is remarkable for the extreme tortuosity 
 of its course. It passes horizontally to the left side, behind the peritoneum and 
 along the upper border of the pancreas, accompanied by the splenic vein, which lies 
 below it, and on arriving near the spleen divides into branches, some of which 
 enter the hilum of that organ to be distributed to its structure, whilst others are 
 distributed to the pancreas and great end of the stomach. Its branches are — the 
 
 Pancreaticse Parvse. Gastric (Vasa Brevia). 
 
 Pancreatica Magna. Gastro-epiploica Sinistra. 
 
 Rami Lienalis. 
 
 The pancreatic branches {rami pancreatici) are numerous small branches 
 derived from the splenic as it runs behind the upper border of the pancreas, 
 supplying its middle and left parts. One of these, larger than the rest, is given 
 off from the splenic near the left extremity of the pancreas; it runs from left 
 to right near the posterior surface of the gland, following the course of the pan- 
 creatic duct, and is called the pancreatica magna. The others are called the 
 pancreaticoB parvcB. These vessels anastomose with the pancreatic branches of the 
 pancreatico-duodenal arteries, derived from the hepatic on the one hand and 
 superior mesenteric on the other. 
 
 The gastric branches or vasa brevia {aa. gastriccB breves) consists of from five to 
 seven small branches, which arise either from the termination of the splenic 
 artery or from its terminal branches, and, passing from left to right, between 
 the layers of the gastro-splenic omentum, are distributed to the great curvature 
 of the stomach, anastomosing with branches of the gastric and gastro-epiploica 
 sinistra arteries. 
 
 The gastro-epiploica sinistra, the largest branch of the splenic, runs from left 
 to right along but distinctly below the great curvature of the stomach, between 
 the layers of the great omentum, and anastomoses with the gastro-epiploica 
 dextra. In its course it distributes several branches to the stomach, which 
 ascend upon both surfaces; others descend to supply the omentum. 
 
 The rami lienales leave the splenic artery in the hilum and pass into the spleen. 
 
 Surgical Anatomy. — The operation of pyloredomy can be made an almost bloodless pro- 
 cedure by tying the gastric, the pyloric, and the right and left gastro-epiploic arteries. "The 
 gastric is doubly tied about one inch below the cardiac orifice at a point where it joins the lesser 
 curvature and is divided between the ligatures. The superior pyloric is doubly tied and divided. 
 The fingers are passed beneath the pylorus, raising the gastro-colic omentum from the trans- 
 verse mesocolon, and in this way safe ligation behind the pylorus of the right gastro-epiploic 
 artery, or in most cases its parent vessel, the gastro-duodenal, is secured. The left gastro- 
 epiploic is now tied at an appropriate point, and the necessary amount of gastro-colic omentum 
 doubly tied and cut."' 
 
 * William J. Mayo. Annals of Surgery, March, 1904. 
 
THE ABDOMINAL AORTA 675 
 
 The Superior Mesenteric Artery (a. mesenterica superior) (Figs. 417 and 420). 
 — The superior mesenteric artery supplies the whole length of the small intestine, 
 except the first part of the duodenum ; it also supplies the ctecum and the ascending 
 and transverse colon ; it is a vessel of large size, arising from the forepart of the 
 aorta about a quarter of an inch below the coeliac axis ; being covered at its origin 
 by the splenic vein and pancreas. It passes forward, between the pancreas and the 
 transverse portion of the duodenum, crosses in front of this portion of the intes- 
 tine, and descends between the layers of the mesentery to the right iliac fossa, 
 where, considerably diminished in size, it anastomoses with one of its own branches 
 — viz., the ileo-colic. In its course it forms an arch, the convexity of which is 
 directed forward and downward to the left side, the concavity backward and 
 upward to the right. It is accompanied by the superior mesenteric vein, and is 
 surrounded by the superior mesenteric plexus of nerves. 
 
 In order to expose the superior mesenteric artery raise the great omentum and transverse 
 colon, draw down the small intestines, and cut through the peritoneum where the transverse 
 mesocolon and mesentery join; the artery will then be exposed just as it issues from beneath 
 the lower border of the pancreas 
 
 Branches. — Its branches are — the 
 
 Inferior Pancreatico-duodenal. Ileo-colic. 
 
 Vasa Intestini Tenuis. Right Colic. 
 
 Middle Colic. 
 
 The Inferior Pancreatico-duodenal (a. pancreaticoduodei talis inferior) is given 
 off from the superior mesenteric, or from its first intestinal branch behind the 
 pancreas. It courses to the right between the head of the pancreas and duodenum, 
 and then ascends to anastomose with the superior pancreatico-duodenal artery. 
 It distributes branches to the head of the pancreas and to the transverse and 
 descending portions of the duodenum. 
 
 The Vasa Intestini Tenuis (aa. intestinales) arise from the convex side of the 
 superior mesenteric artery. They are usually from twelve to fifteen in number, 
 and are distributed to the jejunum {aa. jejunales) and ileum {aa. ilece). They 
 run parallel with one another between the layers of the mesentery, each vessel 
 dividing into two branches, which unite with similar branches on each side, 
 forming a series of arches the convexities of which are directed toward the 
 intestine. From this first set of arches branches arise, which again unite with 
 similar branches from either side, and thus a second series of arches is formed; 
 and from these latter, a third and a fourth, or even a fifth, series of arches is 
 constituted, diminishing in size the nearer they approach the intestine. From 
 the terminal arches numerous small straight vessels arise which encircle the 
 intestine, upon which they are distributed, ramifying between its coats. Through- 
 out their course small branches are given off to the glands and other structures 
 between the layers of the mesentery. (See the description of the vascular loops 
 in the section upon the Intestines. The form and arrangement of the loops 
 have been studied by Monks, of Boston.) 
 
 The Ileo-colic Artery (a. ileocolica) is the lowest branch given off from the 
 concavity of the superior mesenteric artery. It descends between the layers of 
 the mesentery to the right iliac fossa, where it divides into two branches. Of 
 these, the inferior division inosculates with the termination of the superior mesen- 
 teric artery, forming with it an arch, from the convexity of which branches 
 proceed to supply the termination of the ileum, the ctecum, the vermiform 
 appendix, and the ileo-cfecal valve. The superior division inosculates with 
 the colica dextra and supplies the commencement of the colon. 
 
 The Right Colic Artery (a. colica dextra) arises from about the middle of the 
 concavity of the superior mesenteric artery, and, passing behind the peritoneum 
 
676 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 to the middle of the ascending colon, divides into two branches — a descending 
 branch, which inosculates with the ileo-colic, and an ascending branch, which 
 anastomoses with the colica media. These branches form arches, from the 
 convexity of which vessels are distributed to the ascending colon. The branches 
 of this vessel are covered with peritoneum only on their anterior aspect. 
 
 The Middle Colic Artery (a. colica media) arises from the upper part of the 
 concavity of the superior mesenteric, and, passing forward between the layers 
 of the transverse mesocolon, divides into two branches, the one on the right 
 side inosculating with the colica dextra; that on the left side, with the colica 
 sinistra, a branch of the inferior mesenteric. From the arches formed by their 
 inosculation branches are distributed to the transverse colon. The branches 
 of this vessel lie between the two layers of the transverse mesocolon. 
 
 Fig. 420. — The superior mesenteric artery and its branches. 
 
 Blood-supply of the Right Iliac Fossa.— The descending branch of the right colic artery by 
 anastomosing with the ascending branch of the ileo-coHc artery forms a vascular loop. The 
 union of the descending branch of the ileo-coUc artery with the terminal vessel of the superior 
 mesenteric artery forms another vascular loop. These two loops give off secondary loops, and 
 from the secondary loops come the vessels which supply the appendix, the caecum, and the 
 lower end of the ileum. The branch which goes to the appendix is called the appendicular 
 artery (a. appendicularis). If there is a distinct meso-appendix the artery passes along its 
 unattached edge. If there is a rudimentary meso-appendix or no meso-appendix the artery 
 
THE ABDOMINAL AORTA 
 
 677 
 
 usually lies upon the appendix from base to tip beneath the peritoneal covering. In females 
 the appendix may receive an additional vessel from the ovarian, which vessel lies in the 
 appendiculo-ovarian ligament. 
 
 The Inferior Mesenteric Artery (a. mesenterica inferior) (Figs. 417 and 421). — 
 The inferior mesenteric artery supplies the descending colon, the sigmoid flexure 
 of the colon and the greater part of the rectum. It is smaller than the superior 
 mesenteric, and arises from the left side of the aorta, between one and two inches 
 above the division of that vessel into the common iliacs. It passes downward 
 to the left iliac fossa, and then descends between the layers of the mesorectum, 
 
 Middle hxmorrhoidai, 
 Inferior hsemorrhoiddl, 
 
 Fig. 421. — The inferior mesenteric and its branches. 
 
 into the pelvis, under the name of the superior hsemorrhoidal artery. It lies at first 
 in close relation with the left side of the aorta, and then passes as the superior 
 haemorrhoidal in front of the left common iliac artery. 
 
 In order to expose the inferior mesenteric artery draw the small intestines and mesentery over 
 to the right side of the abdomen, raise the transverse colon toward the thorax, and divide the 
 peritoneum covering the front of the aorta. 
 
 Branches. — Its branches are — the 
 
 Left Colic. 
 
 Superior Hsemorrhoidal. 
 
 Sigmoid. 
 
678 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 The Left Colic Artery {a. colica sinistra) passes behind the peritoneum, in 
 front of the left kidney, to reach the descending colon, and divides into two 
 branches — an ascending branch, which inosculates with the colica media; and 
 a descending branch, which anastomoses with the sigmoid artery. From the 
 arches formed by these inosculations branches are distributed to the descending 
 colon. 
 
 The Sigmoid Arteries (aa. sigmoideae). — As a rule there are two of these vessels, 
 but may be three. They run obliquely downward across the Psoas muscle to the 
 sigmoid flexure of the colon, and divide into branches which supply that part of 
 the intestine, anastomosing above with the left colic, and below with the superior 
 hsemorrhoidal artery. 
 
 The Superior Hsemorrhoidal Artery (a. hcemorrhoidalis superior) (Figs. 421 and 
 424) , the continuation of the inferior mesenteric, descends into the pelvis between 
 the layers of the mesorectum, crossing, in its course, the ureter and left common 
 iliac vessels. Opposite the middle of the sacrum it divides into two branches, 
 which descend one on each side of the rectum, and about five inches from the 
 anus break up into several small branches, which pierce the muscular coat of the 
 bowel and run downward, as straight vessels, placed at regular intervals from 
 each other in the wall of the gut between its muscular and mucous coat, to the 
 level of the internal sphincter; here they form a series of loops around the lower 
 end of the rectum, and communicate with the middle hemorrhoidal arteries which 
 are branches of the internal iliac and with the inferior hsemorrhoidal branches 
 of the internal pudic. 
 
 Fig. 422. — Corrosion anatomy. Hyrtl's exsanguinated renal zone. (Byron Robinson.) 
 
 The Suprarenal Artery (a. suprarenalis media) (Fig. 417). — A suprarenal or 
 capsular artery arises, one on each side of the aorta, opposite the superior mesenteric 
 artery. It is a small vessel which passes obliquely upward and, out ward, over 
 the crura of the Diaphragm, to the under surface of the suprarenal capsule, to 
 which it is distributed, anastomosing with capsular branches from the phrenic 
 and renal arteries. In the adult these arteries are of small size; in the foetus 
 they are as large as the renal arteries. 
 
 The Renal Arteries (aa. renales) (Fig. 417). — The renal arteries are two 
 large trunks which arise from the sides of the aorta immediately below the superior 
 
THE ABDOMINAL AOBTA 
 
 679 
 
 mesenteric artery. Each is directed outward across the crus of the Diaphragm, 
 so as to form nearly a right angle with the aorta. The right is longer than the 
 left, on account of the position of the aorta; it passes behind the inferior vena 
 cava. The left is somewhat higher than the right. Before reaching the hilum 
 of the kidney, each artery usually divides into four branches. Two of these vessels 
 enter the anterior portion and two the posterior portion of the kidney. There 
 may be but one renal artery; there may be two, three, four, or five branches. The 
 greater number of the branches generally lie between the renal vein and ureter, the 
 vein being in front of the arteries, the ureter behind. The anterior branches supply 
 three-fourths of the kidney, the posterior supply one-fourth. Each vessel gives 
 off a small branch to the suprarenal capsule (a. swprarenalis inferior) and branches 
 to the ureter, ureteral branches, and to the surrounding cellular tissue and muscles, 
 perirenal branches. Hyrtl, in 1870, pointed out that the renal artery gives off a 
 branch which divides and supplies the dorsal or posterior portion of the kidney and 
 
 Fig. 423. — Corrosion anatomy. The renal vascular blades opened like a book. (Byron Robinson.) 
 
 its pelvis, and a branch which divides and supplies the ventral or anterior portion 
 of the kidney and its pelvis. The two circulations are distinct and do not anas- 
 tomose even at the periphery. Between these two sets of vessels is a bloodless zone 
 called by Byron Robinson the exsanguinated renal zone of Hyrtl, which does not cor- 
 respond to the median line, but is "one-half inch dorsal to the lateral longitudinal 
 renal border."^ The ventral or anterior segment is much the larger. In very rare 
 instances the bloodless zone corresponds to the median line (Kiimmel) . An incision 
 of the middle third of the kidney exactly at the junction of the two segments does 
 not divide vessels. As the incision approaches either pole there is danger of cutting 
 a branch (Schede). Frequently there is a second renal artery, which is given off 
 from the abdominal aorta either above or below the renal artery proper, the former 
 being the more common position. Instead of entering the kidney at the hilum, 
 an accessory renal artery usually pierces the upper or the lower part of the gland. 
 The Spermatic Arteries (aa. spermaticoB internee) (Fig. 417). — The internal 
 spermatic arteries are distributed to the testes. They are two slender vessels of 
 
 1 Byron Robinson. The Circulation of the Kidney, American Journal of Surgery. 
 
680 THE BLOOD -VASCULAR SYSTEM 
 
 considerable length, which arise from the front of the aorta a little below the renal 
 arteries. Each artery passes obliquely outward and downward behind the peri- 
 toneum, resting on the Psoas muscle, the right spermatic lying in front of the 
 inferior vena cava, the left behind the sigmoid flexure of the colon. It then crosses 
 obliquely over the ureter (to which it sends a few branches) and the lower part 
 of the external iliac artery to reach the internal abdominal ring, through which 
 it passes, and accompanies the other constituents of the spermatic cord along 
 the inguinal canal to the scrotum, where it becomes tortuous and is prolonged 
 as the testicular artery, which accompanies the vas deferens, anastomosing with 
 the artery of the vas deferens and is distributed to the epididymis, the back part 
 of the tunica albuginea, and the substance of the testes. The spermatic artery 
 in the inguinal canal gives off cremasteric branches to supply the Cremaster muscle. 
 In the canal and scrotum the artery lies behind the pampiniform plexus and in 
 front of the vas deferens. 
 
 The Ovarian Arteries {aa. ovaricce). — The ovarian arteries (Fig. 425) are 
 the corresponding arteries in the female to the spermatic in the male. They 
 supply the ovaries, are shorter than the spermatic, and do not pass out of 
 the abdominal cavity. The origin and course of the first part of the artery are the 
 same as the spermatic in the male, but on arriving at the margin of the pelvis the 
 ovarian artery passes inward, between the two layers of the broad ligament of the 
 uterus, to be distributed to the ovary, ovarian branches. Branches go to the Fallopian 
 tube, tubal branches, the ureter, ureteral branches, and the broad ligament, ligamentous 
 branches. A branch passes on to the side of the uterus and anastomoses with the 
 uterine arteries, uterine branch. Other offsets are continued along the round 
 ligament through the inguinal canal, to the integument of the labium and groin. 
 
 At an early period of foetal life, when the testes or ovaries lie by the side of 
 the spine below the kidneys, the spermatic or ovarian arteries are short; but as 
 these organs descend from the abdomen into the scrotum or pelvis, the arteries 
 become gradually lengthened. 
 
 The Inferior Phrenic Arteries (aa. phrenicoB inferiores) (Fig. 417). — ^The inferior 
 phrenic arteries are two small vessels which present much variety in their origin. 
 They may arise separately from the front of the aorta, immediately above the 
 coeliac axis, or by a common trunk, which may spring either from the aorta or 
 from the coeliac axis. Sometimes one is derived from the aorta, and the other 
 from one of the renal arteries. In only one out of thirty-six cases examined did 
 these arteries arise as two separate vessels from the aorta. They diverge from 
 one another across the crura of the Diaphragm, and then pass obliquely upward 
 and outward upon the under surface of the Diaphragm. The left phrenic passes 
 behind the oesophagus and runs forward on the left side of the oesophageal 
 opening. The right phrenic passes behind the inferior vena cava, and ascends 
 along the right side of the aperture for transmitting that vein. Near the back 
 part of the central tendon each vessel divides into two branches. The internal 
 branch runs forward to the front of the thorax, supplying the Diaphragm and 
 anastomosing with its fellow of the opposite side, and with the musculo-phrenic 
 and comes nervi phrenici branches of the internal mammary. The external branch 
 passes toward the side of the thorax and inosculates with the intercostal arteries. 
 The internal branch of the right phrenic gives off a few vessels to the inferior 
 vena cava, and the left one some branches to the oesophagus. Each vessel also 
 sends capsular branches (rami suprarenales superior) to the suprarenal capsule 
 of its own side. The spleen on the left side and the liver on the right also 
 receive a few branches from these vessels. 
 
 The Lumbar Arteries (aa. lumhales). — The lumbar arteries are analogous to 
 the intercostals. They are usually four in number on each side, and arise from 
 the back part of the aorta, nearly at right angles with that vessel. They pass 
 
THE COMMON ILIAC ARTERIES 681 
 
 outward and backward, around the sides of the bodies of the lumbar vertebrae, 
 behind the sympathetic nerve and the Psoas magnus muscle, those on the right 
 side being covered by the inferior vena cava, and the two upper ones on each side 
 by the crura of the Diaphragm. In the interval between the transverse processes 
 of the vertebrae each artery gives off a dorsal branch. 
 
 After the formation of the dorsal branch the artery passes outward, having 
 a variable relation to the Quadratus lumborum muscle. Most frequently the 
 first lumbar passes in front of the muscle and the others behind it; sometimes 
 the order is reversed and the lowest lumbar passes in front of the muscle. At 
 the outer border of the Quadratus they are continued between the abdominal 
 muscles, anastomose with branches of the epigastric and internal mammary 
 in front, the intercostals above, and branches of the ilio-lumbar and circumflex 
 iliac below. The lumbar arteries are also distributed to the skin of the sides of 
 the abdomen. 
 
 The Dorsal Branch {ramus dorsalis) gives off, immediately after its origin, a 
 spinal branch, which enters the spinal canal. The dorsal branch then continues 
 its course backward between the transverse processes, and is distributed to the 
 muscles and integument of the back, anastomosing with similar branches of the 
 adjacent lumbar arteries and with the posterior branches of the intercostal 
 arteries. 
 
 The Spinal Branch (ramus spinalis) enters the spinal canal through the inter- 
 vertebral foramen, to be distributed to the spinal cord and its membranes and 
 to the bodies of the vertebrae in the same manner as the lateral spinal branches 
 from the vertebral (see page 638). 
 
 The Middle Sacral Artery (a. sacralis media) (Fig. 424). — The middle sacral 
 artery is a small vessel, which arises from the back part of the aorta just at its bifur- 
 cation. It descends upon the last lumbar vertebra, and along the middle line of the 
 front of the sacrum, to the upper part of the coccyx, where it anastomoses with 
 the lateral sacral arteries, and terminates in a minute branch, which runs down 
 to the situation of the body described as Luschka's gland. It gives off on each 
 side opposite the body of the fifth lumbar vertebra a branch known as the a. 
 lumbalis ima. From the middle sacral artery branches arise which run through 
 the mesorectum to supply the posterior surface of the rectum. Other branches 
 are given off on each side, which anastomose with the lateral sacral arteries, 
 and send off small offsets which enter the anterior sacral foramina. 
 
 The artery is the representative of the caudal prolongation of the aorta of 
 animals, and its lateral branches correspond to the intercostal and lumbar arteries 
 in the dorsal and lumbar regions. 
 
 THE COMMON ILIAC ARTERIES (AA. ILIAC^ COMMUNES) (Figs. 417, 424). 
 
 The abdominal aorta divides into the two common iliac arteries. The bifurca- 
 tion usually takes place on the left side of the body of the fourth lumbar ver- 
 tebra. The common iliac arteries are about two inches in length; diverging 
 from the termination of the aorta, they pass downward and outward to the margin 
 of the pelvis, each divides opposite the intervertebral substance, between the last 
 lumbar vertebra and the sacrum, into two branches, the internal and external 
 iliac arteries, the latter supplying the lower extremity; the former, the viscera and 
 parietes of the pelvis. 
 
 The right common iliac is somewhat longer than the left, and passes more 
 obliquely across the body of the last lumbar vertebra. In front of it are the 
 peritoneum, the small intestines, branches of the sympathetic nerve, and, at its 
 point of division, the ureter. Behind, it is separated from the fourth and fifth 
 
682 
 
 THE BLOOD- VASCULAR SYSTEM 
 
 lumbar vertebrae, with the intervening intervertebral disk, by the two common 
 iliac veins. On its outer side, it is in relation with the inferior vena cava and 
 the right common iliac vein, above, and the Psoas magnus muscle below. 
 
 The left common iliac is in relation, in jront, with the peritoneum, branches 
 of the sympathetic nerve, and the superior hiemorrhoidal artery; and is crossed 
 at its point of bifurcation by the ureter. It rests on the bodies of the fourth and 
 fifth lumbar vertebrae, with the intervening intervertebral disk. The left common 
 iliac vein lies partly on the inner side, and partly beneath the artery; on its outer 
 side, the artery is in relation with the Psoas magnus muscle. 
 
 Plan of the Relations of the Common Iliac Arteries. 
 
 In front. 
 Peritoneum. 
 Small intestines. 
 Sympathetic nerves. 
 Ureter. 
 
 Outer side. 
 Vena cava. 
 Right common . 
 
 iliac vein. 
 Psoas muscle. 
 
 Behind. 
 Fourth and fifth lumbar vertebrae. 
 Right and left common iliac veins. 
 
 Inner side. 
 
 Left common 
 
 iliac vein. 
 
 In front. 
 Peritoneum. 
 Sympathetic nerves. 
 Superior hsemorrhoidal artery. 
 Ureter. 
 
 Outer side. 
 
 Psoas magnus 
 muscle. 
 
 Behind. 
 
 Fourth and fifth lumbar vertebrae. 
 Left common iliac vein. 
 
 Branches. — The common iliac arteries give off small branches to the perito- 
 neum. Psoas magnus, ureters, and the surrounding cellular tissue, and occasionally 
 give origin to the ilio-lumbar or renal arteries. 
 
 Peculiaxities. — The point of origin varies according to the bifurcation of the aorta. In 
 three-fourths of a large number of cases the aorta bifurcated either upon the fourth lumbar 
 vertebra or upon the intervertebral disk between it and the fifth, the bifurcation being, in one 
 case out of nine below, and in one out of eleven above, this point. In ten out of every thirteen 
 cases the vessel bifurcated within half an inch above or below the level of the crest of the ilium, 
 more frequently below than above. 
 
 The point of division is subject to great variety. In two-thirds of a large number of cases 
 it was between the last lumbar vertebra and the upper border of the sacrum, being above that 
 point in one case out of eight and below it in one case out of six. The left common iliac artery 
 divides lower down more frequently than the right. 
 
 The relative length, also, of the two common iliac arteries varies. The right common iliac 
 was the longer in sixty-three cases, the left in fifty-two, whilst they were both equal in fifty- 
 three. The length of the arteries varied in five-sevenths of the cases examined from an inch 
 and a half to three inches; in about half of the remaining cases the artery was longer and in 
 the other half shorter, the minimum length being less than half an inch, the maximum four 
 and a half inches. In two instances the right common iliac has been found wanting, the external 
 and internal iliacs arising directly from the aorta. 
 
 Surface Marking. — Draw a zone around the body opposite the highest part of the crest of 
 the ilium; in this line take a point half an inch to the left of the middle line. From this draw 
 two lines to points midway between the anterior superior spines of the ilium and the symphysis 
 pubis. These two diverging lines will represent the course of the common and external iliac 
 arteries. Draw a second zone round the body corresponding to the level of the anterior superior 
 spines of the ilium: the portion of the diverging lines between the two zones will represent the 
 course of the common iliac artery; the portion below the lower zone, that of the external iliac 
 artery. 
 
 Surgical Anatomy. — The application of a ligature to the common iliac artery may be 
 required on account of aneurism or hemorrhage implicating the external or internal iliacs. 
 Now that the surgeon no longer dreads opening the peritoneal cavity, there can be no question 
 that the easiest and best method of tying the artery is by a transperitoneal route. The abdomen 
 is opened by an incision in either the semilunar line or the linea alba; the intestines are drawn 
 to one side and the peritoneum covering the artery divided. The sheath is then opened, and 
 the needle passed from within outward. On the right side great care must be exercised in 
 
THE INTERNAL ILIAC ARTERY 683 
 
 passing the needle, since both the common iliac veins lie behind the artery. After the vessel 
 has been tied the incision in the peritoneum over the artery should be sutured. Formerly there 
 were two different methods by which the common iliac artery was tied without opening the 
 peritoneal cavity: 1, an anterior or iliac incision, by which the vessel is approached more directly 
 from the front; and 2, a posterior abdominal or lumbar incision, by which the vessel is reached 
 from behind. If the surgeon select the iliac region, a curved incision, from five to eight inches 
 in length, according to the amount of fat, is made, commencing just outside the middle of 
 Poupart's ligament and a finger's breadth above it, and carried outward toward the anterior 
 superior iliac spine, then upward toward the ribs, and finally curving inward toward the umbili- 
 cus. The abdominal muscles and transversalis fascia are divided, and the peritoneum raised 
 upward and inward until the Psoas is reached. The artery will be found on the inner side of 
 this muscle, and is to be cleared with a director, especial care being taken on the right side, as 
 here the common iliac veins lie behind the artery. The aneurism needle is to be passed from 
 within outward. But if the aneurismal tumor should extend high up in the abdomen, along 
 the external iliac, it is better to select the posterior or lumbar route, making an incision partly in 
 the abdomen, partly in the loin. The incision is commenced at the anterior extremity of the 
 last rib, proceeding directly downward to the ilium; it is then curved forward along the crest of 
 the ilium and a little above it to the anterior superior spine of that bone. The abdominal mus- 
 cles having been cautiously divided in succession, the transversalis fascia must be carefully cut 
 through, and the peritoneum, together with the ureter, separated from the artery and pushed 
 aside; the sacro-iliac articulation must then be felt for, and upon it the vessel will be felt pulsat- 
 ing, and may be fully exposed in close connection with the accompanying vein. On the right 
 side both common iliac veins, as well as the inferior vena cava, are in close connection with the 
 artery, and must be carefully avoided. On the left side the vein usually lies on the inner side 
 and behind the artery; but it occasionally happens that the two common iliac veins are joined on 
 the left instead of the right side, which would add much to the difficulty of an operation in such 
 a case. The common iliac artery may be so short that danger may be apprehended from sec- 
 ondary hemorrhage if a ligature is applied to it. It would be preferable, in such a case, to tie 
 both the external and internal iliacs near their origin. 
 
 Collateral Circulation. — The principal agents in carrying on the collateral circulation after 
 the ai)plication of a ligature to the common iliac are— the anastomoses of the hsemorrhoidal 
 branches of the internal iliac with the superior hsemorrhoidal from the inferior mesenteric; the 
 anastomoses of the uterine and ovarian arteries and of the vesical arteries of opposite sides; of 
 the lateral sacral with the middle sacral artery; of the epigastric with the internal mammary, 
 inferior intercostal, and lumbar arteries; of the circumflex iliac with the lumbar arteries; of the 
 ilio-lumbar with the last lumbar artery; of the obturator artery, by means of its pubic branch, 
 with the vessel of the opposite side and with the deep epigastric. 
 
 Compression of the Common Iliac Arteries. — The common iliac arteries may be com- 
 pressed by Davy's lever. The instrument consists of a gum-elastic tube about two feet long, 
 in which fits a round wooden "lever" considerably longer than the tube. A small quantity 
 of olive oil having been injected into the rectum, the gum-elastic tube, softened in hot water, 
 is passed into the bowel sufficiently far to permit its pressing upon the common iliac artery 
 as it lies in the groove between the last lumbar vertebra and the Psoas muscle. The wooden 
 lever is then inserted into the tube, and the projecting end carried toward the opposite thigh 
 and raised, when it acts as a lever of the first order, the anus being the fulcrum. In cases where 
 the mesorectum is abnormally short it may be impossible, without unjustifiable force, to com- 
 press the artery on the right side. In amputation of the hip-joint the common iliac can be 
 compressed inost certainly and safely by opening the abdomen and compressing the vessel by 
 means of the fingers against the Psoas muscle (McBurney's method). 
 
 The Internal Iliac Artery (Figs. 417, 424). 
 
 The internal iliac or hypogastric artery (a. hypogastrica) supplies the walls and 
 viscera of the pelvis, the generative organs, and inner side of the thigh. It is 
 a short thick vessel, smaller in the adult than the external iliac, and about an 
 inch and a half in length. It arises at the point of bifurcation of the common 
 iliac, and, passing downward to the upper margin of the great sacro-sciatic 
 foramen, divides into two large trunks, an anterior and posterior; from its anterior 
 division a partially obliterated cord, a part of the foetal hypogastric artery, extends 
 forward to the bladder. 
 
 Relations. — In front, with the ureter, which is between the artery and the 
 peritoneum. Behind, with the internal iliac vein, the lumbo-sacral cord, and 
 Pyriformis muscle. By its outer side, near its origin, with the Psoas magnus muscle. 
 
684 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 Plan of the Relations of the Internal Iliac Artery, 
 
 In front. 
 Peritoneum. 
 Ureter. 
 
 Outer side. 
 Psoas magnus. 
 
 Behind. 
 Internal iliac vein. 
 Lumbo-sacral cord. 
 Pyriformis muscle. 
 
 lumbar. 
 
 Gluteal. 
 
 Fig. 424. — Arteries of the pelvis. 
 
 In the foetus the hypogastric artery is twice as large as the external iUac, and 
 appears to be the continuation of the common iUac. Instead of dipping into 
 the pelvis, it passes forward to the bladder, and ascends along the sides of that 
 viscus to its summit, to which it gives branches; it then passes upward along the 
 back part of the anterior wall of the abdomen to the umbilicus, converging 
 toward its fellow of the opposite side. Having passed through the umbilical 
 
THE INTERNAL ILIAC ARTERY 685 
 
 opening, the two arteries twine round the umbilical vein in the umbilical cord, 
 and ultimately ramify in the placenta. The portion of the vessel within the 
 abdomen is called the hypogastric axtery; the portion external to that cavity, the 
 umbilical artery. 
 
 At l)irth, when the placental circulation ceases, the upper portion of the hypo- 
 gastric artery, extending from the summit of the bladder to the umbilicus, con- 
 tracts, and ultimately dwindles to a solid fibrous cord; but the lower portion, 
 extending from its origin (in what is now the internal iliac artery) for about an 
 inch and a half to the wall of the bladder, and thence to the summit of that organ, 
 is not totally impervious, though it V)ecomes considerably reduced in size, and 
 serves to convey blood to the bladder under the name of the superior vesical 
 artery. 
 
 Peculiarities as Regards Length. — In two-thirds of a large number of cases the length of 
 the internal iliac varied between an inch and an inch and a half; in the remaining third it was 
 more frequently longer than shorter, the maximum length being three inches, the minimum 
 half an inch. 
 
 The lengths of the common and internal iliac arteries bear an inverse proportion to each 
 other, the internal iliac artery being long when the common iliac is short, and vice versa. 
 
 As Regards its Place of Division. — The place of division of the internal iliac varies 
 between the upper margin of the sacrum and the upper border of the sacro-sciatic foramen. 
 
 The arteries of the two sides in a series of cases often differed in length, but neither seemed 
 constantly to exceed the other. 
 
 Surgical Anatomy. — The application of a ligature to the internal iliac artery may be 
 required in cases of aneurism or hemorrhage affecting one of its branches. The vessel may be 
 secured by making an incision through the abdominal parietes in the iliac region in a direction 
 and to an extent similar to that for securing the common iliac; the transversalis fascia having 
 been cautiously divided, and the peritoneum pushed inward from the iliac fossa toward the 
 pelvis, the finger may feel the pulsation of the external iliac at the bottom of the wound, and by 
 tracing this vessel upward the internal iliac is arrived at, opposite the sacro-iliac articulation. It 
 should be remembered that the vein lies behind and on the right side, a little external to the 
 artery, and in close contact with it; the ureter and peritoneum, which lie in front, must also be 
 avoided. The degree of facility in applying a ligature to this vessel will mainly depend upon 
 the length of the vessel. It has been seen that in the great majority of the cases examined the 
 artery was short, varying from an inch to an inch and a half; m these cases the artery is deeply 
 seated in the pelvis; when, on the contrary, the vessel is longer, it is found partly above that 
 cavity. If the artery is very short, as occasionally happens, it would be preferable to apply a 
 ligature to the common iliac or to both the external and internal iliacs at their origin. 
 
 A better method of tying the internal iliac artery is by an abdominal section in the median 
 line and reaching the vessel through the peritoneal cavity. This plan has been advocated by 
 Dennis, of New York, on the following grounds: (1) It in no way increases the danger of the 
 operation ; (2) it prevents a series of accidents which have occurred during ligature of the artery 
 by the older methods; (3) it enables the surgeon to ascertain the exact extent of disease in the 
 main arterial trunk, and select his spot for the application of the ligature; and (4) it occupies 
 much less time. 
 
 Collateral Circulation. — In Professor Owen's dissection of a case in which the internal 
 iliac artery had been tied by Stevens ten years before death for aneurism of the sciatic artery, 
 the internal iliac was found impervious for about an inch above the point where the ligature had 
 been applied, but the obliteration did not extend to the origin of the external iliac, as the ilio- 
 lumbar artery arose just above this point. Below the point of obliteration the artery resumed 
 its natural diameter, and continued so for half an inch, the obturator, lateral sacral, and gluteal 
 arising in succession from the latter portion. The obturator artery was entirely obliterated. 
 The lateral sacral artery was as large as a crow's quill, and had a very free anastomosis with the 
 artery of the opposite side and with the middle sacral artery. The sciatic artery was entirely 
 obliterated as far as its point of connection with the aneurismal tumor, but on the distal side of 
 the sac it was continued down along the back of the thigh nearly as large in size as the femoral, 
 being pervious about an inch below the sac by receiving an anastomosing vessel from the pro- 
 funda.* The circulation was carried on by the anastomoses of the uterine and ovarian arteries; 
 of the opposite vesical arteries; of the hemorrhoidal branches of the internal iliac with those 
 from the inferior mesenteric; of the obturator artery, by means of its pubic branch, with the 
 vessel of the opposite side and with the epigastric and internal circumflex; of the circumflex 
 
 ' Medico-Chirurgical Transactions, vol. xvi. '' 
 
686 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 From the Posterior Trunk. 
 Ilio-lumbar. 
 Lateral Sacral. 
 Gluteal. 
 
 and perforating branches of the profunda femoris with the sciatic; of the gluteal with the poste- 
 rior branches of the sacral arteries; of the ilio-lumbar with the last lumbar; of the lateral sacral 
 with the middle sacral; and of the circumflex iliac with the ilio-lumbar and gluteal. 
 
 Branches (Fig. 424). — The branches of the internal iliac are; 
 
 From the Anterior Trunk. 
 
 Superior Vesical. 
 
 Middle Vesical. 
 
 Inferior Vesical. 
 
 Middle Hsemorrhoidal. 
 
 Obturator. 
 
 Internal Pudic. 
 
 Sciatic. 
 
 r , if Uterine. 
 In female < ^j . , 
 ' ( Vaginal. 
 
 The Superior Vesical (a. vesicalis superior) (Fig. 424) is that part of the foetal 
 hypogastric artery, which remains pervious after birth. It extends to the side of 
 the bladder, distributing numerous branches to the apex and body of the organ. 
 From one of these a slender vessel is derived which accompanies the vas deferens 
 in its course to the testis, where it anastomoses with the spermatic artery. This is 
 the axtery of the vas deferens. Other branches supply the ureter. 
 
 Branches to fundus. 
 
 Branches to tube. 
 
 Vaginal arteries. 
 Fig. 425. — The arteries of the internal organs of generation of the female, seen from behind. 
 
 (After Hyrtl.) 
 
 The Middle Vesical (a. vesicalis medialis) (Fig. 424), usually a branch of the 
 superior, is distributed to the base of the bladder and under surface of the vesiculse 
 seminales. 
 
 The Inferior Vesical (a. vesicalis inferior) (Fig. 424) arises from the anterior 
 division of the internal iliac, frequently in common with the middle hemorrhoidal, 
 and is distributed to the base of the bladder, the prostate gland, and vesiculse 
 
THE INTERNAL ILIAC ARTERY 
 
 687 
 
 seminales. The branches distributed to the prostate communicate with the 
 corresponding vessel of the opposite side. 
 
 The Middle Hsemorrhoidal Artery (a. hoBmorrhoidalis media) (Fig. 424) 
 usually arises together with the preceding vessel. It supplies the anus and 
 parts outside the rectum, anastomosing with the other hemorrhoidal arteries. 
 
 The Uterine Artery (a. uterina) (Fig. 425) passes inward from the anterior 
 trunk of the internal iliac to the neck of the uterus. Ascending in a tortuous course 
 on the side of this viscus, between the layers of the broad ligament, it distributes 
 branches to its substance and to the round ligament and the Fallopian tube (ramus 
 tubarius), anastomosing, near its termination, with the ovarian artery. It gives a 
 branch to the ovary {ramus ovarii), which anastomoses with a branch from the 
 ovarian branches to the cervix uteri (cervico-uieri) , and a branch which descends 
 
 Fig. 426. — The utero-ovarian artery forming the circle described by Byron Robinson. 
 
 on the vagina (cervico-vaginal) , and, joining with branches from the vaginal 
 arteries, form a median longitudinal vessel both in front and behind; these 
 descend on the anterior and posterior surfaces of the vagina, and are named 
 the azygos arteries of the vagina. 
 
 The Vaginal Artery (a. vaginalis) (Fig. 426) is analogous to the inferior vesical 
 in the male; it descends upon the vagina, supplying its mucous membrane, and 
 sending branches to the neck of the bladder and contiguous part of the rectum. 
 There may be several vaginal arteries. The vaginal artery assists in forming the 
 azygos arteries of the vagina, which are anterior and posterior vessels, running 
 longitudinally, and due to anastomoses of the branches of the vaginal from each 
 side and the cervico-vaginal artery. 
 
 Luschka, Hyrtl, Waldeyer, Byron Robinson, and others, instead of describing 
 the ovarian and uterine arteries as two distinct vessels, regard them as constituting 
 
688 THE BLOOD -VASCULAR SYSTEM 
 
 the chief parts of one vessel, the axteria uterina ovarica. What has been called " the 
 circle of Byron Robinson" is composed of a spiral segment (the arteria uterina 
 ovarica), with a portion of the abdominal aorta, common iliacs, and internal iliacs 
 (Fig. 426). 
 
 Byron Robinson* has made a careful study of this vascular circle; he shows 
 that it is of great importance in certain surgical procedures, and that its remark- 
 able "capacity for extension" saves it from damage when the uterus is enormously 
 distended by pregnancy, or when it is "drawn through the pudendum with trac- 
 tion forceps for palpation, inspection, or repair." 
 
 The author just quoted says further that the utero-ovarian artery has three 
 origins, because it develops from the Wolffian body: The ovarian segment arises 
 from the abdominal aorta. The uterine segment arises from the anterior branch 
 of the internal iliac artery. The artery of the round ligament arises from the deep 
 epigastric. The arteria uterina ovarica artery secures nutrition to the uterus by 
 bringing blood from three sources. It is spiral throughout its entire course, in 
 certain parts is convoluted or looped, and it is accompanied by the pampiniform 
 plexus of veins. 
 
 The three origins of this vessel are freely united by anastomoses, and rami 
 laterales are given off, which unite the bilateral vessels in the median line. Robin- 
 son describes three bifurcations of the utero-ovarian artery. The distal bifurcation, 
 which is "about midway between the uterus and the pelvic wall," and forms an 
 acute angle with the main vessel. This bifurcation indicates the point of division 
 of the external from the internal genitals. The cervico-vaginal artery supplies the 
 external genitals. The proximal bifurcation marks the situation of the ovary. The 
 artery bifurcaies at an acute angle into two branches to supply the ovary and 
 Fallopian tube. The middle bifurcation consists of (1) the division of the uterine 
 segment at the angle formed by the uterus and oviduct ("forming the ramus ovi- 
 ductus and ramus ovarii") and (2) "the bifurcation of the ramus oviductus form- 
 ing the ramus oviductus and the ramus ligamenti teretis, or the segment of the 
 round ligament."^ The relations of the utero-ovarian artery and the ureter are 
 shown in Fig. 426. 
 
 Surgical Anatomy. — As pointed out by Byron Robinson, the source of bleeding after vaginal 
 hysterectomy is usually the torn and undamped cervico-vaginal artery. 
 
 As previously pointed out, the spiral and convoluted shape of the utero-ovarian artery allows 
 the uterus, ovary, and tube to be drawn into the vagina without injury to the vessels. Bryon 
 Robinson points out that in vaginal hysterectomy the genital circle is not divided and only the 
 rami laterales which go to the uterus are cut, the ovaries retaining a normal blood-supply and 
 continuing to functionate. 
 
 The Obturator Artery (a. obturatoria) (Fig. 424) usually arises from the anterior 
 trunk of the internal iliac; frequently from the posterior. It passes forward, below 
 the brim of the pelvis, to the upper part of the obturator foramen, accompanied by 
 the obturator nerve and vein, and, escaping from the pelvic cavity through a short 
 canal formed by a groove on the under surface of the ascending ramus of the os 
 pubis and the arched border of the obturator membrane, it divides into an internal 
 and external branch. In the pelvic cavity this vessel lies upon the pelvic fascia, 
 beneath the peritoneum, and a little below the obturator nerve. 
 
 Branches. — Within the pelvis, the obturator artery gives off an iliac branch 
 {ramus iliacus) to the iliac fossa, which supplies the bone and the Iliacus muscle, 
 and anastomoses with the ilio-lumbar artery; a vesical branch (ramus vesicalis), 
 which runs backward to supply the bladder; and a pubic branch [ramus pubicus), 
 which is given off from the vessel just before it leaves the pelvic cavity. This 
 branch ascends upon the back of the os pubis, communicating with offsets from 
 
 ' The Utero-ovarian Artery. 2 Byron Robinson. The Utero-ovarian Artery. 
 
THE INTERNAL ILIAC ABTEBY 689 
 
 the deep epigastric artery and with the corresponding vessel of the opposite 
 side. It is placed on the inner side of the femoral ring. External to the pelvis, 
 the obturator artery divides into an internal and an external branch, which are 
 deeply situated beneath the Obturator externus muscle. 
 
 The Internal Branch {ramus anterior) curves downward along the inner margin 
 of the obturator foramen, lying beneath the Obturator externus muscle; it dis- 
 tributes branches to the Obturator externus, Pectineus, Adductors, and Gracilis, 
 and anastomoses with the external branch and with the internal circumflex artery. 
 
 The External Branch {ramus 'posterior) curves round the outer margin of 'the 
 obturator foramen, also lying beneath the Obturator externus muscle, to the space 
 between the Gemellus inferior and Quadratus femoris, where it divides into two 
 branches: one, smaller, courses inward around the lower margin of the foramen 
 and anastomoses with the internal branch and with the internal circumflex; the 
 other inclines outward in the groove below the acetabulum {a. acetabulis) , and 
 supplies the muscles attached to the tuberosity of the ischium and anastomoses 
 with the sciatic artery. It sends a branch to the hip-joint through the cotyloid 
 notch, which ramifies on the round ligament as far as the head of the femur. 
 
 Peculiarities (Fig. 427). — In two out of every three cases the obturator arises from the 
 internal iliac ; in one case in three and a half from the epigastric ; and in about one in seventy- 
 two cases by two roots from both vessels. It arises in about the same proportion from the 
 external iliac artery. The origin of the obturator from the epigastric is not commonly found 
 on both sides of the same body. 
 
 Fig. 427. — Variations in origin and course of the obturator artery. 
 
 When the obturator artery arises at the front of the pelvis from the epigastric, it descends 
 almost vertically to the upper part of the obturator foramen. The artery in this course usually 
 lies in contact with the external iliac vein and on the outer side of the femoral ring (Fig. 427, A); 
 in such cases it would not be endangered in the operation for femoral hernia. Occasionally, 
 however, it curves inward along the free margin of Gimbernat's ligament (Fig. 427, B), and 
 under such circumstances would almost completely encircle the neck of a hernial sac (supposing 
 a hernia to exist in such a case), and would be in great danger of being wounded if an operation 
 was performed. 
 
 The Internal Pudic Artery (a. pudenda interna) (Figs. 424, 428, and 429) is the 
 smaller of the two terminal branches of the anterior trunk of the internal iliac, 
 and supplies the external organs of generation. Though the course of the artery 
 is the same in the two sexes, the vessel is much smaller in the female than in the 
 male, and the distribution of its branches somewhat dift'erent. The description of 
 its arrangement in the male will first be given, and subsequently the differences 
 which it presents in the female will be mentioned. 
 
 The Internal Pudic Artery in the Male passes downward and outward to the 
 lower border of the great sacro-sciatic foramen, and emerges from the pelvis 
 between the Pyriformis and Coccygeus muscles: it then crosses the spine of the 
 ischium and re-enters the pelvis through the lesser sacro-sciatic foramen. The 
 artery now crosses the Obturator internus muscle along the outer wall of the ischio- 
 rectal fossa, being situated about an inch and a half above the lower margin of the 
 ischial tuberosity. It is here contained in a sheath of the obturator fascia, and 
 
 44 
 
690 THE BLOOD -VASCULAR SYSTEM 
 
 gradually approaches the margin of the ramus of the ischium, along which it passes 
 forward and upward, pierces the base of the superficial layer of the triangular 
 ligament of the urethra, and runs forward along the inner margin of the ramus of 
 the OS pubis, and divides into its two terminal branches, the dorsal artery of the 
 penis and the artery of the corpus cavemosum. 
 
 Relations. — In the first part of its course, within the pelvis, it lies in front of 
 the Pyriformis muscle and sacral plexus of nerves, and the sciatic artery, and 
 on the outer side of the rectum (on the left side). As it crosses the spine of the 
 ischium it is covered by the Gluteus maximus and overlapped by the great sacro- 
 sciatic ligament. Here the obturator nerve lies to the inner side and the nerve 
 to the Obturator internus to the outer side of the vessel. In the pelvis it lies on 
 the outer side of the ischio-rectal fossa, upon the surface of the Obturator internus 
 muscle, contained in a fibrous canal, the canal of Alcock, formed by the splitting of 
 the obturator fascia. It is accompanied by the pudic veins and the pudic nerve. 
 
 Peculiarities.— The internal pudic is sometimes smaller than usual, or fails to give off one 
 or two of its usual branches; in such cases the deficiency is supplied by branches derived from 
 an additional vessel, the accessory pudic, which generally arises from the internal pudic artery 
 before its exit from the great sacro-sciatic foramen. It passes forward along the lower part of 
 the bladder and across the side of the prosta^'^ gland to the root of the penis, where it perforates 
 the triangular ligament and gives off the branches usually derived from the pudic artery. The 
 •deficiency most frequently met with is that in which the internal pudic ends as the artery of the 
 bulb, the artery of the corpus cavemosum and arteria dorsalis penis being derived from the 
 accessory pudic. Or the pudic may terminate as the superficial perineal, the artery of the bulb 
 being derived, with the other two branches, from the accessory vessel. Occasionally the acces- 
 sory pudic artery is derived from one of the other branches of the internal iliac, most frequently 
 the inferior vesical or the obturator. 
 
 Surgical Anatomy.— The relation of the accessory pudic to the prostate gland and urethra 
 is of the greatest interest in a surgical point of view, as this vessel is in danger of being wounded 
 in the operation of lateral lithotomy. The student should also study the position of the internal 
 pudic artery and its branches, when running a normal course with regard to the same operation. 
 The superficial and the transverse perineal arteries are, of necessity, divided in this operation, 
 but the hemorrhage from these vessels is seldom excessive; should a ligature be required, it 
 can readily be applied on account of their superficial position. The artery of the bulb may 
 be divided if the incision be carried too far forward, and injury of this vessel may be attended 
 with serious or even fatal consequences. The main trunk of the internal pudic artery may be 
 wounded if the incision be carried too far outward; but, being bound down by the strong obtura- 
 tor fascia and under cover of the ramus of the ischium, the accident is not very likely to occur 
 unless the vessel runs an anomalous course. 
 
 Branches. — ^The branches of the internal pudic artery are — the 
 
 Muscular. Transverse Perineal. 
 
 Inferior H hemorrhoidal. Artery of the Bulb. 
 
 Superficial Perineal. Artery of the Corpus Cavemosum. 
 
 Dorsal Artery of the Penis. 
 
 The Muscular Branches consist of two sets — one given off in the pelvis, the 
 •other as the vessel crosses the ischial spine. The former are several small offsets 
 which supply the Levator ani, the Obturator internus, the Pyriformis, and the 
 Coccygeus muscles. The branches given off outside the pelvis are distributed to 
 the adjacent part of the Gluteus maximus and External rotator muscles. They 
 anastomose with branches of the sciatic artery. 
 
 The Inferior H hemorrhoidal Artery (a. hcemorrhoidalis inferior) arises from 
 the internal pudic as it passes above the tuberosity of the ischium. Crossing the 
 ischio-rectal fossa it is distributed by two or three terminal branches to the 
 muscles and integument of the anal region. Instead of one inferior hemor- 
 rhoidal artery two or three small vessels may arise from the internal pudic. 
 
 The Superficial Perineal Artery (a. perinei)(Fig. 428) supplies the scrotum and the 
 muscles and integument of the perinseum. It arises from the internal pudic in front 
 
THE INTERNAL ILIAC ARTERY 
 
 691 
 
 of the preceding branches, and turns upward, crossing either over or under the 
 Transversus perinei superficiaUs muscle, and runs forward, parallel to the pubic 
 arch, in the interspace between the Accelerator urinse and Erector penis muscles, 
 both of which it supplies, and is finally distributed to the skin and dartos of the 
 scrotum. In its passage through the perinseum it lies beneath the superficial 
 perineal fascia. 
 
 The Transverse Perineal Artery is a small branch which arises either from the 
 internal pudic or from the superficial perineal artery as it crosses the Transversus 
 perinaei muscle. It runs transversely inward along the cutaneous surface of the 
 Transversus perinei superficialis muscle, which it supplies, as well as the structures 
 between the anus and bulb of the urethra, and anastomoses with 'the like vessel 
 of the opposite side. 
 
 Transversus perinei 
 superficialis. 
 
 GREAT SACRO- 
 SCIATIC LIGAMENT 
 
 Superficial perineal artery. 
 Superficial perineal nerve. 
 Internal pudic nerve. 
 Internal pudic artery. 
 
 Fig. 428. — The superficial muscles and vessels of the perinaeum. 
 
 The Artery of the Bulb (a. bulbi urethrce) is a large but very short vessel which 
 arises from the internal pudic between the two layers of the triangular ligament, 
 and, passing nearly transversely inward, between the fibres of the Compre sor 
 urethrse muscle, it pierces the bulb of the urethra, which it supplies, and con- 
 tinues anteriorly in the corpus spongiosum to the glans and anastomoses with its 
 fellow of the opposite side. It gives off a small branch which descends to supply 
 Cowper's gland. 
 
 Surgical Anatomy. — Thi.s artery is of considerable importance in a surgical point of view, 
 as it is in dan2;er of being wounded in the median or the lateral operation of lithotomy— an 
 accident usually attended in the adult with alarming hemorrhage. The vessel is sometimes 
 very small, occasionally wanting, or even double. It sometimes arises from the internal pudic 
 earlier than usual, and cros.ses the perinaeum to reach the back part of the bulb. In such a case 
 the ve.s.sel could hardly fail to be wounded in the performance of the lateral operation of lith- 
 otomy. If, on the contrary, it should arise from an accessory pudic, it lies more forward than 
 usual and is out of danger in the operation. 
 
 The Artery of the Corpus Cavemosum (a. profunda penis), one of the terminal 
 branches of the internal pudic, arises from that vessel while it is situated between 
 
692 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 the two layers of the triangular ligament; it pierces the superficial layer, and, 
 entering the crus penis obliquely, it runs forward in the centre of the corpus 
 cavernosum, to which its branches are distributed. 
 
 The Dorsal Artery of the Penis (a. dorsalis penis) ascends between the crus and 
 pubic symphysis, and, piercing the triangular ligament, passes between the two 
 
 layers of the suspensory ligament 
 of the penis, and runs forward 
 on the dorsum of the penis to the 
 glans, where it divides into two 
 branches which supply the glans 
 and prepuce. On the dorsum 
 of the penis it lies immediately 
 beneath the integument, parallel 
 with the dorsal vein and the 
 corresponding artery of the op- 
 posite side. It supplies the in- 
 tegument and fibrous sheath of 
 the corpus cavernosum, sending 
 branches through the sheath to 
 anastomose with the preceding 
 vessel. 
 
 The Internal Pudic Artery in 
 the Female is smaller than in the 
 male. Its origin and course are 
 similar, and there is consider- 
 able analogy in the distribution 
 of its branches. The superficial 
 perineal artery supplies the labia 
 pudendi; the artery of the bulb 
 supplies the bulbi vestibuli and 
 the erectile tissue of the vagina; 
 the artery of the corpus cav- 
 ernosum (a. profunda clitoridis) 
 supplies the cavernous body of 
 the clitoris; and the arteria 
 dorsalis clitoridis supplies the 
 dorsum of that organ, and ter- 
 minates in the glans and in the 
 membranous fold corresponding 
 to the prepuce of the male. 
 
 The Sciatic Artery (a. glutoea 
 inferior) (Fig. 429), the larger of 
 the two terminal branches of the 
 anterior trunk of the internal 
 iliac, is distributed to the mus- 
 cles at the back of the pelvis. 
 It passes down to the lower part 
 of the great sacro-sciatic fora- 
 men behind the internal pudic artery, resting on the sacral plexus of nerves and 
 Pyriformis muscle, and escapes from the pelvis through this foramen between the 
 Pyriformis and Coccygeus. It then descends in the interval between the tro- 
 chanter major and tuberosity of the ischium, accompanied by the sciatic nerves, 
 and covered by the Gluteus maximus, and is continued down the back of the thigh 
 supplying the skin, and anastomosing with branches of the perforating arteries. 
 
 Superior internal 
 articular. 
 
 Fig. 429.- 
 
 Termination 
 of internal 
 circumflex. 
 
 Superior 
 perforating 
 
 Middle 
 perforating. 
 
 Inferior 
 perforating. 
 
 Termination of 
 profunda. 
 
 Superior muscular. 
 
 Superior external 
 articular. 
 
 Inferior muscular. 
 
 The arteries of the gluteal and posterior femoral 
 regions. 
 
THE INTERNAL ILIAC ABTEBY 693 
 
 Within the 'pelvis it distributes branches to the Pyriformis, Coccygeus, and 
 Levator ani muscles; some hemorrhoidal branches, which supply the rectum, and 
 occasionally take the place of the middle hemorrhoidal artery; and vesical 
 branches to the base anfl neck of the bladder, vesiculse seminales, and prostate 
 gland. External to the pelvis it gives off the following branches : 
 
 Coccygeal. Muscular. 
 
 Inferior Gluteal. Anastomotic. 
 
 Comes Nervi Ischiadici. Articular. 
 
 The Coccygeal Branch runs inward, pierces the great sacro-sciatic ligament, and 
 supplies the Gluteus maximus, the integument, and other structures on the back 
 of the coccyx. 
 
 The Inferior Gluteal Branches, three or four in number, supply the Gluteus 
 maximus muscle, anastomosing with the gluteal artery in the substance of the 
 muscle. 
 
 The Comes Nervi Ischiadici (a. comitans n. ischiadici) is a long, slender vessel 
 which accompanies the great sciatic nerve for a short distance; it then penetrates 
 it and runs in its substance to the lower part of the thigh. 
 
 The Muscular Branches supply the Gluteus maximus, anastomosing with the 
 gluteal artery in the substance of the muscle; the external rotators, anastomosing 
 with the internal pudic artery; and the muscles attached to the tuberosity of the 
 ischium, anastomosing with the external branch of the obturator and the internal 
 circumflex arteries. 
 
 The Anastomotic Artery is directed downward across the external rotators and 
 assists in forming the so-called crucial anastomosis by anastomosing with the 
 superior perforating and the internal and external circumflex arteries. 
 
 The Articular Branch, generally derived from the anastomotic, is distributed to 
 the capsule of the hip-joint. 
 
 The Ilio-lumbar Artery (a. ilio lumbalis), given off from the posterior trunk 
 of the internal iliac, turns upward and outward between the obturator nerve and 
 lumbo-sacral cord, to the inner margin of the Psoas muscle, behind which it divides 
 into a lumbar and an iliac branch. 
 
 The Lumbar Branch {ramus lumbalis) supplies the Psoas and Quadratus lum- 
 borinn muscles, anastomosing with the last lumbar artery, and sends a small 
 spinal branch (ramus spinalis) through the intervertebral foramen, between the last 
 lumbar vertebra and the sacrum, into the spinal canal, to supply the cauda equina. 
 
 The Iliac Branch (ramus iliacus) descends to supply the Iliacus muscle; some 
 offsets, running between the muscle and the bone, anastomose with the iliac branch 
 of the obturator; one of these enters an oblique canal to supply the diploe, whilst 
 others run along the crest of the ilium, distributing branches to the Gluteal and 
 Abdominal muscles, and anastomose in their course with the gluteal, circumflex 
 iliac, and external circumflex arteries. 
 
 The Lateral Sacral Artery (a. sacralis lateralis) (Fig. 424) runs downward. 
 It may be single, but usually there are two on each side, the superior and inferior 
 divisions. 
 
 The Superior Division, which is of large size, passes inward, and, after anastomos- 
 ing with branches from the middle sacral, enters the first or second anterior sacral 
 foramen, gives spinal branches (rami spinalis) to the contents of the sacral canal, 
 and, escaping by the corresponding posterior sacral foramen, supplies the skin 
 and muscles on the dorsum of the sacrum, anastomosing with the gluteal. 
 
 The Inferior Division passes obliquely across the front of the Pyriformis muscle 
 and sacral nerves to the inner side of the anterior sacral foramina, descends on the 
 front of the sacrum, and anastomoses over the coccyx with the middle sacral and 
 opposite lateral sacral arteries. In its course it gives off spinal branches which 
 
694 THE BLOOD -VASCULAR SYSTEM 
 
 enter the anterior sacral foramina {rami spinalcs) ; these, after supplying the con- 
 tents of the sacral canal, escape by the posterior sacral foramina, and are dis- 
 tributed to the muscles and skin on the dorsal surface of the sacrum, anastomosing 
 with the gluteal. 
 
 The Gluteal Artery (a. glutoea superior) (Fig. 429) is the largest branch of 
 the internal iliac, and appears to be the continuation of the posterior division of 
 that vessel. It is a short thick trunk, which passes out of the pelvis above the 
 upper border of the Pyriformis muscle, and immediately divides into a superficial 
 and deep branch. Within the pelvis it gives off a few muscular branches to the 
 Iliacus, Pyriformis, and Obturator internus, and, just previous to emerging from 
 that cavity, a nutrient artery, which enters the ilium. 
 
 The Superficial Branch passes beneath the Gluteus maximus and divides into 
 numerous branches, some of which supply that muscle, whilst others perforate its 
 tendinous origin, and supply the integument covering the posterior surface of the 
 sacrum, anastomosing with the posterior branches of the sacral arteries. 
 
 The Deep Branch runs between the Gluteus medius and minimus, and sub- 
 divides into two. Of these, the superior division (ramus superior), continuing the 
 original course of the vessel, passes along the upper border of the Gluteus minimus 
 to the anterior superior spine of the ilium, anastomosing with the circumflex iliac 
 and ascending branches of the external circumflex artery. The inferior division 
 {ramus inferior) crosses the Gluteus minimus obliquely to the trochanter major, 
 distributing branches to the Glutei muscles, and inosculates with the external 
 circumflex artery. Some branches piece the Gluteus minimus to supply the hip- 
 joint. 
 
 Surface Marking. — The position of the three main branches of the internal iliac, the 
 sciatic, internal pudic, and gluteal, which may occasionally be the object of surgical interference, 
 is indicated on the surface in the following way: A line is to be drawn from the posterior supe- 
 rior iliac spine to the posterior superior angle of the great trochanter, with the limb slightly 
 flexed and rotated inward: the point of emergence of the gluteal artery from the upper part of 
 the sciatic notch will correspond with the junction of the upper with the middle third of this 
 line. A second line is to be drawn from the same point to the outer part of the tuberosity of 
 the ischium; the junction of the lower with the middle third marks the point of emergence of 
 the sciatic and pudic arteries from the great sciatic notch. 
 
 Surgical Anatomy. — Any of these three vessels may require ligating for a wound or for 
 aneurism, which is generally traumatic. The gluteal artery is ligated by turning the patient 
 two-thirds over on his face and making an incision from the posterior superior spine of the ilium 
 to the upper and posterior angle of the great trochanter. This must expose the Gluteus maxi- 
 mus muscle, and its fibres are to be separated through the whole thickness of the muscle and 
 pulled apart with retractors. The contiguous margins of the gluteus medius and Pyriformis 
 are now to be separated from each other, and the artery will be exposed emerging from the 
 sciatic notch. In ligation of the sciatic artery, the incision should be made parallel with that 
 for ligation of the gluteal, but one inch and a half lower down. After the fibres of the Gluteus 
 maximus have been separated, the vessel is to be sought for at the lower border of the Pyri- 
 formis; the great sciatic nerve, which lies just above it, forming the chief guide to the artery. 
 The internal pudic can be reached through the incision used to reach the sciatic. 
 
 The External Iliac Artery (A. Iliaca Externa) (Fig. 424). 
 
 The external iliac artery is larger in the adult than is the internal iliac. It 
 passes obliquely downward and outward along the inner border of the Psoas, 
 muscle, from the bifurcation of the common iliac to Poupart's ligament, where 
 it enters the thigh and becomes the femoral artery. 
 
 Relations. — In front, with the peritoneum, subperitoneal areolar tissue or Aber- 
 nethy's fascia, the termination of the ileum on the right side, and the sigmoid flexure 
 on the left, and a thin layer of fascia derived from the iliac fascia, which surrounds 
 the artery and vein. At its origin it is occasionally crossed by the ureter. The 
 spermatic vessels descend for some distance upon it near its termination, and it is 
 
THE EXTERNAL ILIAC ARTERY 695 
 
 crossed in this situation by the genital branch of the genito-crural nerve and the deep 
 circumflex ihac vein; the vas deferens curves down along its inner side. Behind, 
 it is in relation with the external iliac vein, which, at Poupart's ligament, lies at 
 its inner side; on the left side the vein is altogether internal to the artery. Exter- 
 nally, it rests against the Psoas muscle, from which it is separated by the iliac 
 fascia. The artery rests upon this muscle, near Poupart's ligament. Numerous 
 lymphatic vessels and glands are found lying on the front and inner side of the 
 vessel. 
 
 Plan of the Relations of the External Iliac Artery. 
 
 In front. 
 Peritoneum, intestines, and fascia. 
 Near [Lymphatic vessels and glands. 
 
 Poupart's Spermatic vessels. 
 
 Ligament I Genito-crural nerve (genital branch). 
 
 ° * [Deep circumflex iliac vein. 
 
 Outer side. / \ Inner side. 
 
 Psoas magnus. ^'iHar'!'*' External iliac vein and vas deferens 
 
 Iliac fascia. \ J near Poupart's ligament. 
 
 Behind. 
 External iliac vein. 
 Psoas magnus. 
 
 Surface Marking. — The surface line indicating the course of the external iliac artery has 
 been already given (see page 682). 
 
 Surgical Anatomy, — The application of a ligature to the external iliac may be required in 
 cases of aneurism of the femoral artery or for a wound of the artery. This vessel may be 
 secured in any part of its course, excepting near its upper end, which is to be avoided on account 
 of the proximity of the great stream of blood in the internal iliac, and near its lower end, which 
 should also be avoided, on account of the proximity of the deep epigastric and circumflex iliac 
 vessels. The patient having been placed in the supine position, an incision should be made, 
 commencing below at a point about three-quarters of an inch above Poupart's ligament, and 
 a little external to its middle, and running upward and outward, parallel to Poupart's ligament, 
 to a point one inch internal and one inch above the anterior superior spine of the ilium. When 
 the artery is deeply seated more room will be required, and may be obtained by curving the 
 incision from the point last named inward toward the umbilicus for a short distance. Another 
 mode of ligating the vessel is the plan advocated by Sir Astley Cooper, by making an incision 
 close to Poupart's ligament from about half an inch outside of the external abdominal ring to 
 one inch internal to the anterior superior spine of the ilium. This incision, being made in the 
 course of the fibres of the aponeurosis of the external oblique, is less likely to be followed by a 
 ventral hernia, but there is danger of wounding the epigastric artery, and only the lower end 
 of the vessel can be ligated. Abernethy, who first tied this artery, made his incision in the 
 course of the vessel. The abdominal muscles and transversalis fascia having been cautiously 
 divided, the peritoneum should be separated from the iliac fossa and raised toward the pelvis; 
 and on introducing the finger to the bottom of the wound, the artery may be felt pulsating along 
 the inner border of the Psoas muscle. The external iliac vein is generally found on the inner 
 side of the artery, and must be cautiously separated from it by the finger-nail or handle of the 
 knife, and the aneurism needle should be introduced on the inner side, between the artery and 
 the vein. 
 
 Ligation of the external iliac artery has recently been performed by a transperitoneal method. 
 An incision four inches in length is made in the semilunar line, commencing about an inch 
 below the umbilicus and carried through the abdominal wall into the peritoneal cavity. The 
 intestines are then pushed upward and held out of the way by a broad abdominal retractor, and 
 an incision is made through the peritoneum at the margin of the pelvis in the course of the artery, 
 and the vessel is secured in any part of its course which may seem desirable to the operator. The 
 advantages of this operation appear to be that if it is found necessary, the common iliac artery 
 can be ligated instead of the external iliac without extension or modification of the incision; 
 and secondly, that the vessel can be ligated without in any way interfering with the coverings 
 of the sac of an aneurism. Possibly a disadvantage may exist in the greater risk of hernia after 
 this method. 
 
 k 
 
696 THE BLOOD -VASCULAR SYSTEM 
 
 Collateral Circulation. — The principal anastomoses in carrying on the collateral circulation, 
 after the application of a ligature to the external iliac, are — the ilio-lumbar with the circumflex 
 iliac; the gluteal with the external circumflex; the obturator with the internal circumflex; the 
 sciatic with the superior perforating and circumflex branches of the profunda artery; and the 
 internal pudic with the external pudic. When the obturator arises from the epigastric it is 
 supplied with blood by branches, either from the internal iliac, the lateral sacral, or the internal 
 pudic. The epigastric receives its supply from the internal mammary and inferior intercostal 
 arteries, and from the internal iliac by the anastomoses of its branches with the obturator. 
 
 In the dissection of a limb eighteen years after the successful ligature of the external iliac 
 artery by Sir A. Cooper, the report of which is to be found in Guys Hospital Reports, vol. 
 i. p. 50, the anastomosing branches are described in three sets: An anterior set. — 1, a very 
 large branch from the ilio-lumbar artery to the circumflex iliac; 2, another branch from the 
 ilio-lumbar, joined by one from the obturator, and breaking up into numerous tortuous branches 
 to anastomose with the external circumflex; 3, two other branches from the obturator, which 
 passed over the brim of the pelvis, communicated with the epigastric, and then broke up into a 
 plexus to anastomose with the internal circumflex. An internal set. — Branches given off from 
 the obturator, after quitting the pelvis, which ramified among the adductor muscles on the 
 inner side of the hip-joint, and joined most freely with branches of the internal circumflex. 
 A posterior set. — 1, three large branches from the gluteal to the external circumflex; 2, several 
 branches from the sciatic around the great sciatic notch to the internal and external circumflex, 
 and the perforating branches of the profunda. 
 
 Branches. — Besides several small branches to the Psoas muscle and the neigh- 
 boring lymphatic glands, the external iliac gives off two branches of considerable 
 size — the deep epigastric and deep circumflex iliac arteries. 
 
 The Internal or Deep Epigastric Artery (a. epigastrica inferior) (Fig. 424) 
 arises from the external iliac a few lines above Poupart's ligament. It at first 
 descends to reach this ligament, and then ascends obliquely along the inner margin 
 of the internal abdominal ring, lying between the transversalis fascia and peri- 
 toneum, and, continuing its course upward, it pierces the transversalis fascia, and 
 passing over the semilunar fold of Douglas, enters the sheath of the Rectus muscle. 
 It then ascends on the posterior surface of the muscle, and finally divides into 
 numerous branches which anastomose, above the umbilicus, with the superior 
 epigastric branch of the internal mammary and with the inferior intercostal arteries 
 (Fig. 410). The deep epigastric artery bears a very important relation to the 
 internal abdominal ring as it passes obliquely upward and inward from its origin 
 from the external iliac. In this part of its course it lies along the lower and inner 
 margin of the ring and beneath the commencement of the spermatic cord. As 
 it passes to the inner side of the internal abdominal ring it is crossed by the vas 
 deferens in the male and the round ligament in the female. 
 
 Branches. — The branches of this vessel are the following: The cremasteric 
 (a. spermatica externa in the male, a. ligamenti teretis uteri in the female), which 
 accompanies the spermatic cord, and supplies the Cremaster muscle and other 
 coverings of the cord, anastomosing with the spermatic artery in the male, 
 and which accompanies the round ligament in the female; a pubic branch 
 {ramus pvbicus), which runs along Poupart's ligament, and then descends behind 
 the OS pubis to the inner side of the femoral ring, and anastomoses with offsets 
 from the obturator artery; muscular branches, some of which are distributed to the 
 abdominal muscles and peritoneum, anastomosing with the lumbar and circum- 
 flex iliac arteries; cutaneous branches perforate the tendon of the External oblique, 
 and supply the integument, anastomosing with branches of the superficial epi- 
 gastric. 
 
 Peculiarities. — The origin of the deep epigastric may take place from any part of the 
 external iliac between Poupart's ligament and two inches and a half above it, or it may arise 
 below this ligament, from the common femoral or from the deep femoral. 
 
 Union with Branches. — It frequently arises from the external iliac by a common trunk 
 with the obturator. Sometimes the epigastric arises from the obturator, the latter vessel being 
 furnished by the internal iliac, or the epigastric may be formed by two branches, one derived 
 from the external iliac, the other from the internal iliac. 
 
THE FEMORAL ABTEBY 697 
 
 Surgical Anatomy. — The deep epigastric artery follows a line drawn from the middle of 
 Poupart's ligament toward the umbilicus; but shortly after this line crosses the linea semilunaris 
 the direction changes, and the course of the vessel is directly upward in the line of junction of 
 the inner third with the outer two-thirds of the Rectus muscle. It has important surgical rela- 
 tions, in addition to the fact that it is one of the principal means, through its anastomosis with 
 the internal mammary, in establishing the collateral circulation after ligature of either the com- 
 mon or external iliac arteries. It lies close to the internal abdominal ring, and is therefore 
 internal to an oblique inguinal hernia, but external to a direct inguinal hernia, as the hernia 
 emerges from the abdomen. It forms the outer boundary of Hesselbach's triangle. It is in 
 close relationship with the spermatic cord, which lies in front of it in the inguinal canal, 
 separated only by the transversalis fascia. The vas deferens hooks round its outer side. 
 
 The Deep Circumflex Hiac Artery (a. circumflexa ilium profunda) (Fig. 424) 
 -arises from the outer side of the external iUac nearly opposite the epigastric artery. 
 It ascends obliquely outward behind Poupart's ligament, contained in a fibrous 
 sheath formed by the junction of the transversalis and iliac fasciae, to the anterior 
 superior spinous process of the ilium. It then runs along the inner surface of the 
 crest of the ilium to about its middle, where it pierces the Transversalis, and 
 runs backward between that muscle and the Internal oblique, to anastomose with 
 the ilio-lumbar and gluteal arteries. Opposite the anterior superior spine of the 
 ilium it gives off a large branch which ascends between the Internal oblique and 
 Transversalis muscles, supplying them, and anastomosing with the lumbar and 
 epigastric arteries. It also gives off cutaneous branches. 
 
 ARTERIES OF THE LOWER EXTREMITY. 
 
 The artery which supplies the greater part of the lower extremity is the direct 
 continuation of the external iliac. It continues as a single trunk from Poupart's 
 ligament to the lower border of the Popliteus muscle, and here divides into two 
 branches, the anterior and posterior tibial, an arrangement exactly similar to what 
 occurs in the upper limb. For convenience of description, the upper part of the 
 main trunk is named femoral, the lower part, popliteal. 
 
 THE FEMORAL ARTERY (A. FEMORALIS) (Figs. 430, 431, 432). 
 
 The femoral artery commences immediately behind Poupart's ligament, 
 midway between the anterior superior spine of the ilium and the symphysis 
 pubis, and, passing down the forepart and inner side of the thigh, terminates 
 at the opening in the Adductor magnus, at the junction of the middle with the 
 lower third of the thigh, where it becomes the popliteal artery. The vessel, at 
 the upper part of the thigh, lies in front of the hip-joint, just on a line with the 
 innermost part of the head of the femur; in the lower part of its course it is in close 
 relation with the inner side of the shaft of the bone, and between these two parts 
 the vessel is some distance from the bone. In the upper third of the thigh it is 
 contained in a triangular space called Scarpa's triangle. In the middle third of the 
 thigh it is contained in an aponeurotic canal called Hunter's canal. 
 
 Scarpa's Triangle (trigonum femorale). — Scarpa's triangle corresponds to the 
 depression seen immediately below the fold of the groin. It is a triangular space, 
 the apex of which is directed downward, and the sides formed externally by the 
 Sartorius, internally by the inner margin of the Adductor longus, and above by 
 Poupart's ligament. The floor of the space is formed from without inward by the 
 Iliacus, Psoas, Pectineus (in some cases a small part of the Adductor brevis), and 
 the Adductor longus muscles ; and it is divided into two nearly equal parts by the 
 femoral vessels, which extend from the middle of its base to its apex, the artery 
 
698 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 giving off in this situation its superficial and profunda branches, the vein receiving 
 the deep femoral and internal saphenous. On the outer side of the femoral artery 
 is the anterior crural nerve dividing into its branches. In the outer corner of the 
 space is the external cutaneous nerve. Within the sheath of the artery, and lying 
 upon the outer side of the vessel, is the crural branch of the genito-crural nerve. 
 At the base of the triangle the vein is to the inner side of the artery; at the apex 
 of the triangle it is passing behind the artery. Besides the vessels and nerves, 
 this space contains some fat and lymphatics. 
 
 SUPERFICIAL 
 EPIGASTRIC 
 
 SUPERFICIAL CIR- 
 CUMFLEX ILIAC 
 
 COMMON 
 FEMORAL 
 
 EXTERNAL 
 CIRCUMFLEX 
 
 DESCENDING 
 RAMUS OF 
 EXTERNAL 
 
 CIRCUMFLEX 
 
 SUPERFICIAL 
 
 EXTERNAL 
 
 PUDIC 
 
 SUPERIOR EXTER- 
 NAL ARTICULAR 
 BRANCH OF 
 POPLITEAL 
 
 DEEP 
 
 EXTERNAL 
 
 PUDIC 
 
 INTERNAL 
 
 CIRCUMFLEX 
 
 ANASTOMOTICA 
 MAGNA 
 
 SUPERIOR INTERNAL 
 ARTICULAR 
 BRANCH OF 
 POPLITEAL 
 
 Fig. 430. — Scheme of the femoral artery. (Poirier and Charpy.) 
 
 Hunter's Canal or the Adductor Canal (canalis addvdorius [Hunteri]). — 
 This is the aponeurotic space in the middle third of the thigh, extending from 
 the apex of Scarpa's triangle to the femoral opening in the Adductor magnus 
 muscle. It is bounded, externally, by the Vastus internus; internally by the 
 Adductors longus and magnus muscles; and is covered in by a strong apon- 
 eurosis which extends transversely from the Vastus internus across the femoral 
 
THE COMMON FEMORAL ARTERY 
 
 699 
 
 Scrotum. 
 
 vessels to the Adductor longus and magnus; lying on which aponeurosis is the 
 Sartorius muscle. It contains the femoral artery and vein enclosed in their own 
 sheath of areolar tissue, the vein being behind and on the outer side of the artery, 
 and the internal or long saphenous 
 nerve lying at first on the outer side 
 and then in front of the vessels. 
 
 For convenience of description, 
 and also in reference to its surgi- 
 cal anatomy, the femoral artery is 
 divided into a short trunk, about 
 an inch and a half or two inches 
 long, which is known as the com- 
 mon femoral artery, while the re- 
 mainder of the vessel is termed 
 the superficial femoral artery, to 
 distinguish it from the deep femoral 
 (profunda femoris), a large branch 
 given off from the common femoral 
 at its termination, and which, 
 by its derivation, from the parent 
 trunk, marks the commencement 
 of the superficial femoral artery. 
 
 The Common Femoral Artery 
 
 (Figs. 430, 431, 432). 
 
 The common femoral artery is 
 very superficial, being covered by 
 the skin and superficial fascia, 
 superficial inguinal lymphatic 
 glands, the iliac portion of the 
 fascia lata, and the prolongation 
 downward of the transversalis 
 fascia, which forms the anterior 
 part of the sheath of the vessels. 
 It has in front of it filaments from 
 the crural branch of the genito- 
 crural nerve, the superficial cir- 
 cumflex iliac vein, and occasionally 
 the superficial epigastric vein. It 
 rests on the inner margin of the 
 Psoas muscle, which separates it 
 from the capsular ligament of the 
 hip-joint, and a little lower on the 
 Pectineus muscle ; and crossing 
 behind it is the branch to the 
 Pectineus from the anterior crural 
 nerve. Separating the artery from 
 the Pectineus muscles is the pubic portion of the fascia lata and the prolongation 
 from the fascia covering the Iliacus muscle, which forms the posterior layer of the 
 sheath of the vessels. The anterior crural nerve lies about half an inch to the 
 outer side of the common femoral artery, being separated from the artery by a 
 small part of the Psoas muscle. To the inner side of the artery is the femoral vein, 
 between the margins of the Pectineus and Psoas muscles. The two vessels are 
 
 Long saphenous 
 
 nerve. 
 
 Anastomotica 
 magna. 
 
 Superior external 
 articular. 
 
 Inferior internal 
 articular 
 
 Anterior tibial 
 recurrent. 
 
 Anastomotica 
 
 magna. 
 Superior internal 
 
 articular. 
 
 Inferior internal 
 articular. 
 
 Fig. 431. — The femoral artery. 
 
700 
 
 THE BLOOD - VASCULAR SYSTEM 
 
 enclosed in a strong fibrous sheath formed by the proper sheath of the vessels, 
 strengthened by fascia (see page 509) ; the artery and vein are separated, however, 
 from one another by a thin fibrous partition. 
 
 Plan of the Relations of the Common Femoral Artery. 
 
 In front. 
 Skin and superficial fascia. 
 Superficial inguinal glands. 
 Iliac portion of fascia lata. 
 Prolongation of transversalis fascia. 
 Crural branch of genito-crural nerve. 
 Superficial circumflex iliac vein. 
 Superficial epigastric vein. 
 
 Inner side. 
 Femoral vein. 
 
 Outer side. 
 Small part of Psoas muscle, 
 separating the artery from the 
 anterior crural nerve. 
 
 Behind. 
 Prolongation of fascia covering the Iliacus muscle. 
 Pubic portion of fascia lata. 
 Nerve to Pectineus. 
 Psoas muscle. 
 Pectineus muscle. 
 Capsule of hip-joint. 
 
 The Superficial Femoral Artery (Figs. 430, 431, 432). 
 
 The superficial femoral artery is only superficial where it lies in Scarpa's tri- 
 angle. Here it is covered by the skin, superficial and deep fascia, and crossed 
 by the internal cutaneous branch of the anterior crural nerve. In Hunter's canal 
 it is more deeply seated, being covered by the integument, the superficial and 
 deep fascia, the Sartorius and the aponeurotic covering of Hunter's canal. The 
 internal saphenous nerve crosses the artery from without inward. Behind, the 
 artery lies at its upper part on the femoral vein and the profunda artery and 
 vein, which separate it from the Pectineus muscle, and lower down on the Adduc- 
 tor longus and Adductor magnus muscles. To the outer side is the long saphenous 
 nerve and the nerve to the Vastus internus, the Vastus internus muscle, and, 
 at its lower part, the femoral vein. To the inner side is the Adductor longus 
 above and the Adductor magnus and Sartorius below. 
 
 Plan of the Relations of the Superficial Femoral Artery. 
 
 In front. 
 Skin, superficial and deep fasciae. 
 Internal cutaneous nerve. 
 Sartorius. 
 
 Aponeurotic covering of Hunter's canal. 
 Internal saphenous nerve. 
 
 Outer side. 
 
 Long saphenous nerve. 
 
 Nerve to vastus internus. 
 
 Vastus internus. 
 
 Femoral vein (below). 
 
 Behind. 
 Femoral vein. 
 Profunda artery and vein. 
 Pectineus muscle. 
 Adductor longus. 
 Adductor magnus. 
 
 Inner side. 
 Adductor longus. 
 Adductor magnus. 
 Sartorius. 
 
THE SUPERFICIAL FEMORAL ARTERY 701 
 
 The femoral vein, at Poupart's ligament, lies close to the inner side of the artery, 
 separated from it by a thin fibrous partition; but lower down it is behind it, and 
 then to its outer side. 
 
 The internal saphenous nerve is situated on the outer side of the artery, in the 
 middle third of the thigh, beneath the aponeurotic covering of Hunter's canal, but 
 not usually within the sheath of the vessels. The internal cutaneous nerve passes 
 obliquely across the upper part of the sheath of the femoral artery. 
 
 Peculiarities. Double Femoral Reunited. — Several cases are recorded in which the femoral 
 artery divided into two trunks below the origin of the profunda, and became reunited near the 
 opening of the Adductor magnus so as to form a single popliteal artery. One of them occurred 
 in a patient operated upon for popliteal aneurism. 
 
 Change of Position. — A few cases have been recorded in which the femoral artery was 
 situated at the back of the thigh, the vessel being continuous above with the internal iliac, escap- 
 ing from the pelvis through the great sacro-sciatic foramen, and accompanying the great sciatic 
 nerve to the pophteal space, where its division occurred in the usual manner. The external 
 iliac in these cases was small, and terminated in the profunda. 
 
 Position of the Vein. — The femoral vein is occasionally placed along the inner side of the 
 artery, throughout the entire extent of Scarpa's triangle, or it may be slit so that a large vein is 
 placed on each side of the artery for a greater or less extent. 
 
 Origin of the Profunda. — This vessel occasionally arises from the inner side, and, more 
 rarely, from the back of the common trunk; but the more important peculiarity, in a surgical 
 point of view, is that which relates to the height at which the vessel arises from the femoral. In 
 three-fourths of a large number of cases it arose between one or two inches below Poupart's 
 ligament; in a few cases the distance was less than an inch; more rarely, opposite the ligament; 
 and in one case, above Poupart's ligament, from the external iliac. Occasionally, the distance 
 between the origin of the vessel and Poupart's ligament exceeds two inches, and m one case it 
 was found to be as much as four inches. 
 
 Surface Marking. — The upper two-thirds of a line drawn from a point midway between 
 the anterior superior spine of the ilium and the symphysis pubis to the adductor tubercle on 
 the inner condyle of the femur, with the thigh abducted and rotated outward, will indicate the 
 course of the femoral artery. 
 
 Surgical Anatomy. — Com-pression of the femoral artery, which is constantly requisite in 
 amputations and other operations on the lower limbs, and also for the cure of popliteal aneurisms, 
 is most effectually made immediately below Poupart's ligament. In this situation the artery is 
 very superficial, and is merely separated from the ascending ramus of the os pubis by the Psoas 
 muscle; so that the surgeon, by means of his thumb or a compressor, may effectually control the 
 circulation through it. This vessel may also be compressed in the middle third of the thigh by 
 placing a compress over the artery, beneath the tourniquet, and directing the pressure from 
 within outward, so as to compress the vessel against the inner side of the shaft of the femur. 
 
 The application of a ligature to the femoral artery may be required in the cases of wound 
 or aneurism of the arteries of the leg, of the popliteal or femoral ;^ and the vessel may be exposed 
 and tied in any part of its course. The great depth of this vessel at its lower part, its close con- 
 nection with important structures, and the density of its sheath render the operation in this 
 situation one of much greater difficulty than the application of a ligature at its upper part, 
 where it is more superficial. 
 
 Ligature of the common femoral artery is usually considered unsafe, on account of the con- 
 nection of large branches with it — viz., the deep epigastric and the deep circumflex iliac arising 
 just above Poupart's ligament; on account of the number of small branches which arise from 
 it in its short course; and on account of the uncertainty of the origin of the profunda femoris, 
 which, if it arise high up, would be too close to the ligature for the formation of a firm coagu- 
 lum. The profunda sometimes arises higher than the point above mentioned, and rarely between 
 two or three inches (in one case four) below Poupart's ligament. It would appear, then, that 
 the most favorable situation for the application of a ligature to the femoral is on the superficial 
 femoral at the apex of Scarpa's triangle. In order to expose the artery in this situation, an inci- 
 sion between three and four inches long should be made in the course of the vessel, the patient 
 lying in the recumbent position, with the limb slightly flexed and abducted, and rotated outward. 
 A large vein is frequently met with, passing in the course of the artery to join the internal saphe- 
 nous vein; this must be avoided, and the fascia lata having been cautiously divided and the 
 Sartorius exposed, that muscle must be drawn outward in order to expose fully the sheath of 
 the vessels. The finger being introduced into the wound and the pulsation of the artery felt, 
 the sheath should be opened on the outer side of the vessel to a sufficient extent to allow of the 
 
 1 Ligation of the femoral artery has been also recommended and performed for elephantiasis of the leg and 
 acute inflammation of the knee-joint (Maunder, Clin. Soc. Trans., vol. ii. p. 37). — Ed. of 15th English edition. 
 
702 THE BLOOD -VASCULAR SYSTEM 
 
 introduction of the ligature, but no farther; otherwise the nutrition of the coats of the vessel 
 naay be interfered with, or muscular branches which arise from the vessel at irregular intervals 
 may be divided. In this part of the operation the long saphenous nerve and the nerve to the 
 Vastus internus, which is in close relation with the sheath, should be avoided. The aneurism 
 needle must be carefully introduced and kept close to the artery, to avoid the femoral vein, which 
 lies behind the vessel in this part of its course. 
 
 To expose the artery in Hunter's canal, an incision should be made between three and four 
 inches in length, a finger's breadth internal to the line of the artery, in the middle of the thigh 
 — i. e., midway between the groin and the knee. The integument is first divided. The fascia 
 lata having been divided, and the outer border of the Sartorius muscle exposed, it should be 
 drawn inward, when the strong fascia which is stretched across from the Adductors to the Vastus 
 internus will be exposed, and must be freely divided; the sheath of the vessels is now seen, 
 and must be opened, and the artery secured by passing the aneurism needle between the vein 
 and artery in the direction from without inward. The femoral vein in this situation lies on the 
 outer side of the artery and the long saphenous nerve on the anterior and outer side of the 
 artery. 
 
 It has been seen that the femoral artery occasionally divides into two trunks below the origin 
 of the profunda. If in the operation for tying the femoral two vessels are met with, the surgeon 
 should alternately compress each, in order to ascertain which vessel is connected with the 
 aneurismal tumor or with the bleeding from the wound, and that one only should be tied which 
 controls the pulsation or hemorrhage. If, however, it is necessary to compress both vessels 
 before the circulation in the tumor is controlled, both should be tied, as it would be probable that 
 they became reunited, as in the instances referred to above. 
 
 In wounds of the femoral artery the question of the mode of treatment is of considerable 
 importance. If the wound in the superficial structures is a large one, the injured vessel must 
 be exposed and tied; but if the wound is a punctured one and the bleeding has ceased, the ques- 
 tion will arise whether to cut down upon the artery or to trust to pressure. Mr. Cripps' advises 
 that if the wound is in the "upper part of the thigh — that is to say, in a position where the 
 femoral artery is comparatively superficial — the surgeon may enlarge the opening with a good 
 prospect of finding the wounded vessel without an extensive or prolonged operation, if the 
 wound be in the lower half of the thigh, owing to the greater depth of the artery and the possi- 
 bility of its being the popliteal that is wounded, the search is rendered a far more severe and 
 hazardous operation, and it should not be undertaken until a thorough trial of pressure has 
 proved ineffectual." 
 
 Great care and attention are necessary for the successful application of pressure. The limb 
 should be carefully bandaged from the foot upward to the wound, which is not covered, and then 
 onward to the groin. The wound is then dusted with iodoform or boracic powder and a conical 
 pad applied over the wound. Rollers the thickness of the index finger are then placed along 
 the course of the vessel above and below the wound, and the whole carefully bandaged to a back 
 splint with a foot-piece. 
 
 Collateral Circulation. — ^When the common femoral is tied the main channels for carrying 
 on the circulation are the anastomoses of the gluteal and circumflex iliac arteries above with the 
 external circumflex below; of the obturator and sciatic above with the internal circumflex below; 
 and of the comes nervi ischiadici with the arteries in the ham. 
 
 The principal agents in carrying on the collateral circulation after ligature of the superficial 
 femoral artery are, according to Sir A. Cooper, as follows: 
 
 " The arteria profunda formed the new channel for the blood. The first artery sent off 
 passed down close to the back of the thigh-bone, and entered the two superior articular branches 
 of the popliteal artery. 
 
 "The second new large vessel, arising from the profunda at the same part with the former, 
 passed down by the inner side of the Biceps muscle to a branch of the popliteal which was dis- 
 tributed to the Gastrocnemius muscle; whilst a third artery, dividing into several branches, 
 passed down with the sciatic nerve behind the knee-joint, and some of its branches united them- 
 selves with the inferior articular arteries of the popliteal, with some recurrent branches of those 
 arteries, with arteries passing to the Gastrocnemii, and, lastly, with the origin of the anterior 
 and posterior tibial arteries. 
 
 "It appears, then, that it is those branches of the profunda which accompany the sciatic 
 nerve that are the principal supporters of the new circulation."^ 
 
 In Porta's work' (tab. xii., xiii.) is a good representation of the collateral circulation after 
 the ligature of the femoral artery. The patient had survived the operation three years. The 
 lower part of the artery is at least as large as the upper; about two inches of the vessel appear 
 to have been obliterated. The external and internal circumflex arteries are seen anastomosing 
 by a great number of branches with the lower branches of the femoral (muscular and anasto- 
 
 ' Heath's Dictionary of Practical Surgery, vol. i. p. 525. - Med.-Chir. Trans., vol. ii., 18H. 
 
 8 Alterazioni patologiche delle Arterie. 
 
THE SUPERFICIAL FEMORAL ARTERY 
 
 703 
 
 motica magna) and with the articular branches of the pophteal. The branches from the external 
 circumflex are extremely large and numerous. One very distinct anastomosis can be traced 
 between this artery on the outside and the anastomotica magna on the inside through the inter- 
 vention of the superior external articular artery, with which they both anastomose; and blood 
 reaches even the anterior tibial recurrent from the external circumflex by means of anastomosis 
 with the same external articular artery. The perforating branches of the profunda are also 
 seen bringing blood round the obliterated portion of the artery into long branches (muscular) 
 
 External iliac artery. 
 
 Deep epiiv'^tric artery. 
 ^ I' 'III tic void. 
 
 Superior 
 
 circumfle.t' 
 
 iliac artery 
 
 Common femoral. ■ 
 
 Profniula . 
 femoris. 
 
 External cir- I'.lS 
 cumflex. 
 
 l^nperficial 
 ^ J femoral. 
 
 I- Opening in 
 adductor 
 magnus. 
 
 Fig. 432.- 
 
 - Femoral artery and its branches. (From a preparation in the Museum of the Royal College of 
 Surgeons of England.) 
 
 which have been given off just below that portion. The termination of the profunda itself 
 anastomoses most freely with the superior external articular. A long branch of anastomosis 
 is also traced down from the internal iliac by means of the comes nervi ischiadici of the sciatic, 
 which anastomoses on the popliteal nerves with branches from the popliteal and posterior tibial 
 arteries. In this case the anastomosis had been too free, since the pulsation and growth of the 
 aneurism recurred, and the patient died after ligature of the external iliac. 
 
 There is an interesting preparation in the Museum of the Royal College of Surgeons of a 
 limb on which John Hunter had tied the femoral artery fifty years before the patient's death. 
 
 k 
 
704 '^HE BLOOD -VASCULAR SYSTEM 
 
 The whole of the superficial femoral and popliteal artery seems to have been obliterated. The 
 anastomosis by means of the comes nervi ischiadici, which is shown in Porta's plate, is distinctly 
 seen: the external circumflex and the termmation of the profunda artery seem to have been the 
 chief channels of anastomoses; but the injection has not been a very successful one. 
 
 Branches (Figs. 430, 431, and 432). — The branches of the femoral artery 
 are — the 
 
 Superficial Epigastric. ( External Circumflex. 
 
 Superficial Circumflex Ihac. Profunda Femoris \ Internal Circumflex. 
 
 Superficial External Pudic. ( Three Perforating. 
 
 Deep External Pudic. Muscular. 
 
 Anastomotica Magna. 
 
 The Superficial Epiglistric (a. epigastrica swperficiaUs) arises from the fem- 
 oral about half an inch below Poupart's ligament, and, passing through the 
 saphenous opening in the fascia lata, ascends on the abdomen, in the superficial 
 fascia covering the External oblique muscle, nearly as high as the umbilicus. It 
 distributes branches to the superficial inguinal glands, the superficial fascia, and 
 the integument, anastomosing with branches of the deep epigastric. 
 
 The Superficial Circumflex Iliac (a. circumflexa ilium super ficialis), the 
 smallest of the cutaneous branches, arises close to the preceding, and, piercing the 
 fascia lata, runs outward, parallel with Poupart's ligament, as far as the crest of 
 the ilium, dividing into branches which supply the integument of the groin, the 
 superficial fascia, and the superficial inguinal lymphatic glands, anastomosing 
 with the deep circumflex iliac and with the gluteal and external circumflex 
 arteries. 
 
 The Superficial External Pudic or the Superior Superficial External Pudic 
 (a. pudenda externa superficialis) arises from the inner side of the femoral artery, 
 close to the preceding vessels, and, after passing through the saphenous opening, 
 courses inward, across the spermatic cord or round ligament, to be distributed to 
 the integument on the lower part of the abdomen, the penis and scrotum in the 
 male, and the labium in the female, anastomosing with branches of the internal 
 pudic. 
 
 The Deep External Pudic or the Deep Superficial External Pudic (a. pudenda 
 externa profunda), more deeply seated than the preceding, passes inward across 
 the Pectineus and Adductor longus muscles, covered by the fascia lata, which it 
 pierces at the inner border of the thigh, its branches being distributed, in the male, 
 to the integument of the scrotum and perimeum; and in the female to the labium, 
 anastomosing with branches of the superficial perineal artery. 
 
 The Deep Femoral or the Profunda Femoris (a. profunda femoris) (Figs. 430, 
 431, and 432) nearly equals the size of the superficial femoral. It arises from the 
 outer and back part of the femoral artery, from one to two inches below Poupart's 
 ligament. It at first lies on the outer side of the superficial femoral, and then 
 passes behind it and the femoral vein to the inner side of the femur, and, passing 
 downward beneath the Adductor longus, terminates at the lower third of the thigh 
 in a small branch which pierces the Adductor magnus (and from this circum- 
 stance is sometimes called the fourth perforating artery), and is distributed to the 
 flexor muscles on the back of the thigh, anastomosing with branches of the 
 popliteal and inferior perforating arteries. 
 
 Relations. — Behind, it lies first upon the Iliacus, and then on the Pectineus, 
 Adductor brevis, and Adductor magnus muscles. In front, it is separated from 
 the superficial femoral artery, above by the femoral and profunda veins, and 
 below by the Adductor longus. On its outer side the origin of the Vastus internus 
 seoarates it from the femur. 
 
THE SUPERFICIAL FEMORAL ARTERY 705 
 
 Plan of the Relations of the Profunda Artery. 
 
 In front. 
 Superficial femoral artery. 
 Femoral and profunda veins. 
 Adductor longus. 
 
 Outer side. 
 Vastus internus. 
 
 Behind. , 
 Iliacus. 
 Pectineus. 
 Adductor brevis. 
 Adductor magnus. 
 
 Branches. — The profunda gives off the following named branches: 
 
 Muscular. Internal circumflex. 
 
 External circumflex. Four perforating. 
 
 Muscular Branches are given off in Scarpa's triangle, and also from the vessel as 
 it lies between the Adductor muscles. 
 
 The External Circumflex Artery (a. circumflexa femoris lateralis) supplies the 
 muscles on the front of the thigh. It arises from the outer side of the profunda, 
 passes horizontally outward, between the divisions of the anterior crural nerve and 
 behind the Sartorius and Rectus muscles, and divides into three sets of branches — 
 ascending, transverse, and descending. 
 
 The ascending branch (ramus ascendens) passes upward, beneath the Tensor 
 fasciae femoris muscle, to the outer side of the hip, anastomosing with the terminal 
 branches of the gluteal and deep circumflex iliac arteries. It sends out muscular 
 branches. The descending branch {ramus descendens) passes downward, behind 
 the Rectus, upon the Vasti muscles, to which its branches are distributed, one 
 or two passing beneath the Vastus externus as far as the knee, anastomosing with 
 the superior articular branches of the popHteal artery. These are accompanied by 
 the branch of the anterior crural nerve to the Vastus externus. The transverse 
 branch, the smallest, passes outward over the Crureus, pierces the Vastus externus, 
 and winds round the femur to its back part, just below the great trochanter, 
 anastomosing at the back of the thigh with the internal circumflex, sciatic, and 
 superior perforating arteries. 
 
 The Internal Circumflex Artery (a. circumflexa femoris medialis), smaller than 
 the external, arises from the inner and back part of the profunda, and winds 
 round the inner side of the femur, between the Pectineus and Psoas muscles. On 
 reaching the upper border of the Adductor brevis it gives off two muscular branches, 
 one of which passes inward to be distributed to the Adductor muscles, the Gracilis, 
 and Obturator externus, anastomosing with the obturator artery; the other 
 descends, and passes beneath the x\dductor brevis, to supply it and the great 
 Adductor; while the continuation of the vessel passes backward and divides into 
 an ascending and a transverse branch (Fig. 348). The ascending branch {ramus 
 profundus) passes obliquely upward upon the tendon of the Obturator externus 
 and under cover of the Quadratus femoris toward the digital fossa, where it 
 anastomoses with twigs from the gluteal and sciatic arteries. The transverse 
 branch (ramus super ficialis), larger than the ascending, appears between the 
 <5uadratus femoris and upper border of the Adductor magnus, anastomosing with 
 the sciatic, external circumflex, and superior perforating arteries, the crucial anas- 
 
 45 
 
706 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 tomosis. Opposite the hip-joint the artery gives off an articular vessel (ramus 
 acetahuli), which enters the joint beneath the transverse Hgament; and, after sup- 
 plying the adipose tissue, passes along the round ligament to the head of the bone. 
 The Perforating Arteries (Figs. 429, 430, and 431), usually three in number, are 
 so called from their perforating the tendon of the Adductor magnus muscle to 
 
 Internal 
 saphenous^ 
 vein. 
 
 '--Femoral 
 artery. 
 
 Fig. 433.- 
 
 -Side view of the popliteal artery. (From a preparation in the Museum of the Royal College of 
 
 Surgeans of England.) 
 
 reach the back of the thigh. They pass backward close to the linea aspera of the 
 femur, under cover of small tendinous arches in the Adductor magnus. The 
 first is given off above the Adductor brevis, the second in front of that muscle, 
 and the third immediately below it. 
 
 The first perforating artery (a. perforans prima) passes backward between the 
 Pectineus and Adductor brevis (sometimes perforates the latter); it then pierces 
 
THE POPLITEAL SPACE 707 
 
 the Adductor magnus close to the Hnea aspera. It gives off branches which supply 
 the Adductor brevis, the Adductor magnus, the Biceps, and Gluteus maximus 
 muscles, and anastomoses with the sciatic, internal and external circumflex, and 
 middle perforating arteries. The second perforating artery (a. perforans secunda), 
 larger than the first, pierces the tendons of the Adductor brevis and Adductor 
 magnus muscles, and divides into ascending and descending branches, which 
 supply the flexor muscles of the thigh, anastomosing with the first and third 
 perforating arteries. The second artery frequently arises in common with the first. 
 The nutrient artery of the femur is usually given off from this branch. The third 
 perforating artery (a. perforans tertia) is given off below the Adductor brevis; it 
 pierces the Adductor magnus, and divides into branches which supply the flexor 
 muscles of the thigh ; anastomosing above with the higher perforating arteries, and 
 below with the terminal branches of the profunda and the muscular branches of 
 the popliteal. A fourth perforating artery is represented by the termination of the 
 profunda femoris artery. 
 
 The nutritive artery of the femur (a. nutricia femoris), if single, comes from the 
 second perforating artery; if double, from the first and third perforating arteries. 
 If double, one vessel is called superior and the other inferior. 
 
 Muscular Branches (rami musculares) are given off from the superficial femoral 
 throughout its entire course. They vary from two to seven in number, and supply 
 chiefly the Sartorius and Vastus internus. 
 
 The Anastomotica Magna (a. genu swprema) (Figs. 430,431, and 433) arises 
 from the femoral artery just before it passes through the tendiVious opening in the 
 Adductor magnus muscle, and immediately divides into a superficial and deep branch. 
 
 The Superficial Branch {ramus saphenous) pierces the aponeurotic covering of 
 Hunter's canal, and accompanies the long saphenous nerve to the inner side of the 
 thigh. It passes between the Sartorius and Gracilis muscles, and, piercing the fascia 
 lata, is distributed to the integument of the upper and inner part of the leg, anasto- 
 mosing with the inferior internal articular artery. 
 
 The Deep Branch (ramus musculoarticularis) descends in the substance of the 
 Vastus internus, lying in front of the tendon of the Adductor magnus, to the inner 
 side of the knee, where it anastomoses with the superior internal articular artery 
 and the anterior recurrent branch of the anterior tibial. A branch from this vessel 
 crosses outward above the articular surface of the femur, forming an anastomotic 
 arch with the superior external articular artery, and supplies branches to the 
 knee-joint. 
 
 THE POPLITEAL ARTERY (A. POPLITEA) (Figs. 429, 430, 433). 
 
 The popliteal artery commences at the termination of the femoral at the 
 opening in the Adductor magnus, and, passing obliquely downward and out- 
 ward behind the knee-joint to the lower border of the Popliteus muscle divides 
 into the anterior and posterior tibial arteries. A portion of the artery lies in the 
 popliteal space; but above and below, to a considerable extent, it is covered 
 by the muscles which form the boundaries of the space, and is therefore beyond 
 the confines of the hollow. 
 
 The Popliteal Space (Fig. 434). 
 
 Dissection. — A vertical incision about eight inches in length should be made along the back 
 part of the knee-joint, connected above and below by a transverse incision from the inner to the 
 outer side of the Hmb. The flaps of integument included between these incisions should be 
 reflected in the direction shown in Fig. 345, page 522. 
 
 Boundaries. — The popliteal space, or the ham, is a lozenge-shaped space, 
 widest at the back part of the knee-joint, and deepest above the articular end of 
 
708 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 the femur. It is bounded externally, above the joint, by the Biceps, and below 
 the joint by the Plantaris and external head of the Gastrocnemius. Internally, 
 above the joint, by the Semimembranosus, Semitendinosus, Gracilis, and Sartorius; 
 
 below the joint, by the inner head of the 
 Gastrocnemius. 
 
 Above, it is limited by the apposition of the 
 inner and outer hamstring muscles ; below, by 
 the junction of the two heads of the Gastroc- 
 nemius. The floor is formed by the lower 
 part of the posterior surface of the shaft of 
 the femur, the posterior ligament of the knee- 
 joint, the upper end of the tibia, and the 
 fascia covering the Popliteus muscle, and the 
 -Sural arteries space is covered in by the fascia lata. 
 
 Contents. — It contains the popliteal vessels 
 and their branches, together with the termina- 
 tion of the external saphenous vein, the in- 
 ternal and external popliteal nerves and some 
 of their branches, the lower extremity of the 
 small sciatic nerve, the articular branch from 
 the obturator nerve, a few small lymphatic 
 glands, and a considerable quantity of loose 
 adipose tissue. 
 
 Position of Contained Parts. — The in- 
 ternal popliteal nerve descends in the middle 
 line of the space lying superficial and cross- 
 ing the artery from without inward. The 
 external popliteal nerve descends on the outer 
 side of the upper part of the space, lying 
 close to the tendon of the Biceps muscle. 
 More deeply at the bottom of the space are 
 the popliteal vessels, the vein lying superficial 
 to the artery, to which it is closely united by 
 dense areolar tissue ; it is a thick-walled 
 vessel, and lies at first to the outer side of the 
 artery, and then crosses it to gain the inner 
 side below; sometimes the vein is double, the 
 artery lying between the two venae comites, 
 which are usually connected by short trans- 
 verse branches. INIore deeply and, at its 
 upper part, close to the surface of the bone 
 is the popliteal artery, and passing off from 
 it at right angles are its articular branches. 
 The articular branch from the obturator 
 nerve descends upon the popliteal artery to 
 supply the knee, and occasionally there is 
 found deep in the space an articular filament 
 from the great sciatic nerve. 
 
 The popliteal lymphatic glands, four or 
 five in number, are found surrounding the 
 artery ; one usually lies superficial to the 
 vessel ; another is situated between it and 
 the bone, and the rest are placed on either 
 
 -The popliteal, posterior tibial, and oirlp nf it 
 peroneal arteries. blue Ol 11. 
 
 -Anterior peroneal. 
 
 434.- 
 
THE POPLITEAL SPACE 709 
 
 The Popliteal Artery, in its course downward from the aperture in the Adductor 
 magnus to the lower border of the PopHteus muscle, rests first on the inner surface 
 of the femur, and is then separated by a Httle fat from the hollowed popliteal 
 surface of the bone; in the middle of its course it rests on the posterior ligament 
 of the knee-joint, and below on the fascia covering the Popliteus muscle. Super- 
 ficially, it is covered above by the Semimembranosus; in the middle of its course, 
 by a quantity of fat, which separates it from the deep fascia and integument; and 
 below it is overlapped by the Gastrocnemius, Plantaris, and Soleus muscles, the 
 popliteal vein, and the internal popliteal nerve. The popliteal vein, which is 
 intimately attached to the artery, lies superficial and external to it above; it then 
 crosses it and lies to its inner side. The internal popliteal nerve is still more 
 superficial and external above, but below the joint it crosses the artery and lies 
 on its inner side. Laterally, the artery is bounded by the muscles which are 
 situated on either side of the popliteal space. 
 
 Plan of the Relations of the Popliteal Artery. 
 
 In front. 
 Femur. 
 
 Ligamentum posticum. 
 Popliteus. 
 Inner side /^^ ^ Outer side. 
 
 Semimembranosus. / \ oiceps. 
 
 Internal condyle ( P^P'^'-ai ] Outer condyle. 
 
 Gastrocnemius (inner head). V ''" / Gastrocnemius (outer head). 
 
 \ / rlantaris. 
 
 Behind. 
 Semimembranosus. 
 Fascia. 
 
 Popliteal vein. 
 Internal popliteal nerve. 
 Gastrocnemius. 
 Plantaris. 
 Soleus. 
 
 Peculiarities in Point of Division.— Occasionally the popliteal artery divides prematurely 
 into its terminal branches; this unusual division occurs most frequently opposite the knee-joint. 
 The anterior tibial under these circumstances may pass in front of the Popliteus muscle. 
 
 Unusual Branches. — The artery sometimes divides into the anterior tibial and peroneal, the 
 posterior tibial being wanting or very small. Occasionally the popliteal is found to divide into 
 three branches, the anterior and posterior tibial and peroneal. 
 
 Surface Marking. — The course of the upper part of the popliteal artery is indicated by 
 a line drawn from the outer border of the Semimembranosus muscle at the junction of the 
 middle and lower third of the thigh obliquely downward to the middle of the popliteal space, 
 exactly behind the knee-joint. From this point it passes vertically downward to the level of a 
 line drawn through the lower part of the tubercle of the tibia. 
 
 Surgical Anatomy.— The popliteal artery is not infrequently the seat of injury. It may be 
 torn l)y direct violence, as by the passage of a cart-wheel over the knee or by hyper-extension of 
 the knee; and in the dead body, at all events, the middle and internal coats may be ruptured by 
 extreme flexion. It may also be lacerated by fracture of the lower part of the shaft of the 
 femur or by antero-posterior dislocation of the knee-joint. It has been torn in breaking down 
 adhesions in cases of fibrous ankylosis of the knee, and is in danger of being wounded, and in 
 fact has been wounded, in performing Macewen's operation of osteotomy of the lower end of the 
 femur for genu valgum. In addition, Spencer records a case in which the popliteal artery was 
 wounded from in front by a stab just below the knee, the knife passing through the interosseous 
 space. The popliteal artery is more frequently the seat of aneurism than is any other artery 
 in the body, with the exception of the thoracic aorta. This is due no doubt, in a great measure, 
 to the amount of movement to which it is subjected, and to the fact that it is supported by loose 
 and lax tissue only, and not by muscles, as is the case with most arteries. 
 
 Ligature of the popliteal artery is required in cases of wound of that vessel, but for aneurism 
 of the posterior tibial it is preferable to tie the superficial femoral. The popliteal may be tied 
 in the upper or lower part of its course; but in the middle of the ham the operation is attended 
 
710 THE BLOOD -VASCULAR SYSTEM 
 
 with considerable difficulty, from the great depth of the artery and from the extreme degree of 
 tension of the lateral boundaries of the space. 
 
 In order to expose the vessel in the upper part of its course, the patient should be placed 
 in the supine position, with the knee flexed and the thigh rotated outward, so that it rests on 
 its outer surface; an incision three inches in length, beginning at the junction of the middle 
 and lower third of the thigh, is to be made parallel to and immediately behind the tendon of 
 the Adductor magnus, and the skin, superficial and deep fascia divided. The tendon of the 
 muscle is thus exposed, and is to be drawn forward and the hamstring tendons backward. A 
 quantity of fatty tissue will now be opened up, in which the artery will be felt pulsating. This 
 is to be separated with the point of a director until the artery is exposed. The vein and nerve 
 will not be seen, as they lie to the outer side of the artery. The sheath is to be opened and 
 the aneurism needle passed from before backward, keeping its point close to the artery for fear 
 of injuring the vein. The only structure to avoid is the long saphenous vein in the superficial 
 incision. The upper part of the popliteal artery may also be tied by an incision on the back of 
 the limb, along the outer margin of the Semimembranosus, but the operation is a more difficult 
 one, as the internal popliteal nerve and the popliteal vein are first exposed, and great care has 
 to be exercised in separating them from the artery. 
 
 To expose the vessel in the lower part of its course, where the artery lies between the two 
 heads of the Gastrocnemius, the patient should be placed in the prone position with the limb 
 extended. An incision should then be made through the integument in the middle line, com- 
 mencing opposite the bend of the knee-joint, care being taken to avoid the external saphenous 
 vein and nerve. After dividing the deep fascia and separating some dense cellular membrane, 
 the artery, vein, and nerve will be exposed, descending between the two heads of the Gastrocne- 
 mius. Some muscular branches of the popliteal should be avoided if possible, or, if divided, 
 tied immediately. The leg being now flexed, in order the more effectually to separate the two 
 heads of the Gastrocnemius, the nerve should be drawn inward and the vein outward, and the 
 aneurism needle passed between the artery and vein from without inward. 
 
 Branches. — The branches of the popliteal artery are — the 
 
 ^ , f Superior. Superior External Articular. 
 
 \ Inferior or Sural. Azygos Articular. 
 
 Cutaneous. Inferior Internal Articular. 
 
 Superior Internal Articular. Inferior External Articular. 
 
 The Superior Muscular Branches, two or three in number, arise from the 
 upper part of the popliteal artery, and are distributed to the lower part of the 
 Adductor magnus and flexor muscles of the thigh, anastomosing with the fourth 
 perforating branch of the profunda. 
 
 The Inferior Muscular {aa. surales) are two large branches which are dis- 
 tributed to the two heads of the Gastrocnemius and to the Plantaris muscle. They 
 arise from the popliteal artery opposite the knee-joint. 
 
 The Cutaneous Branches arise separately from the popliteal artery or from 
 some of its branches; they descend between the two heads of the Gastrocnemius 
 muscle, and, piercing the deep fascia, are distributed to the integument of the 
 calf. One branch usually accompanies the short, or external, saphenous vein, 
 the superficial sural artery. 
 
 The Superior Articular Arteries, two in number, arise one on each side of the 
 popliteal, and wind round the femur immediately above its condyles to the front 
 of the knee-joint. The internal branch (a. genu superior medialis) winds inward 
 beneath the hamstring muscles, to which it supplies branches, above the inner 
 head, of the Gastrocnemius, and, passing beneath the tendon of the Adductor 
 magnus, divides into two branches, one of which supplies the Vastus internus, 
 inosculating with the anastomotica magna and inferior internal articular; the other 
 ramifies close to the surface of the femur, supplying it and the knee-joint, and an- 
 astomosing with the superior external articular artery. This branch is frequently 
 of small size, a condition which is associated with an increase in the size of the an- 
 astomotica magna. The external branch (a. genu superior lateralis) passes above 
 the outer condyle, beneath the tendon of the Biceps, and divides into a superficial 
 and deep branch: the superficial branch supplies the Vastus externus, and anasto- 
 
i 
 
 » 
 
 TMU ANTERIOR TIBIAL ARTERY 711 
 
 moses with the descending branch of the external circumflex and the inferior exter- 
 nal articular arteries; the deep branch supplies the lower part of the femur and 
 knee-joint, and forms an anastomotic arch across the bone with the anastomotica 
 magna and the inferior internal articular arteries. 
 
 The Azygos Articular (a. genu media) is a small branch arising from the pop- 
 liteal artery opposite the bend of the knee-joint. It pierces the posterior ligament, 
 and supplies the ligaments and synovial membrane in the interior of the articu- 
 lation. 
 
 The Inferior Articular Arteries, two in number, arise from the popliteal 
 beneath the Gastrocnemius, and wind round the head of the tibia below the joint. 
 The internal branch (a. genu inferior medialis) first descends along the upper mar- 
 gin of the Popliteus muscle, to which it gives branches; it then passes below the 
 inner tuberosity, beneath the internal lateral ligament, at the anterior border of 
 which it ascends to the front and inner side of the joint, to supply the head of the 
 tibia and the articulation of the knee, anastomosing with the inferior external 
 articular and superior internal articular arteries. The external branch (a. genu 
 inferior lateralis) passes outward above the head of the fibula, to the front of the 
 knee-joint, passing in its course beneath the outer head of the Gastrocnemius, the 
 external lateral ligament, and the tendon of the Biceps muscle, and divides into 
 branches which anastomose with the inferior internal articular artery, the superior 
 external articular artery, and the anterior recurrent branch of the anterior tibial. 
 
 Circumpatellar Anastomosis. — Around and above the patella, and on the con- 
 tiguous ends of the femur and tibia, is a large network of vessels, forming a super- 
 ficial and a deep plexus. The superficial plexus is situated between the fascia and 
 skin round about the patella; the deep plexus, which forms a close network of 
 vessels, lies on the surface of the lower end of the femur and upper end of the 
 tibia around their articular surfaces, and sends numerous offsets into the interior 
 of the joint. The arteries from which this plexus is formed are the two internal and 
 two external articular branches of the popliteal, the anastomotica magna, the ter- 
 minal branch of the profunda, the descending branch from the external circumflex 
 and the anterior recurrent branch of the anterior tibial. 
 
 The Anterior Tibial Artery (A. Tibialis Anterior) (Fig. 435). 
 
 The anterior tibial artery commences at the bifurcation of the popliteal at 
 the lower border of the Popliteus muscle, passes forward between the two 
 heads of the Tibialis posticus, and through the large oval aperture above the 
 upper border of the interosseous membrane to the deep part of the front of the 
 leg; it here lies close to the inner side of the neck of the fibula; it then descends on 
 the anterior surface of the interosseous membrane, gradually approaching the 
 tibia; and at the lower part of the leg lies on this bone, and then on the anterior 
 ligament of the ankle to the bend of the ankle-joint, where it lies more superficially, 
 and becomes the dorsalis pedis. 
 
 Relations. — In the upper two-thirds of its extent it rests upon the interosseous 
 membrane, to which it is connected by delicate fibrous arches thrown across it; 
 in the lower third, upon the front of the tibia and the anterior ligament of the 
 ankle-joint. In the upper third of its course it lies between the Tibialis anticus 
 and Extensor longus digitorum; in the middle third, between the Tibialis anticus 
 and Extensor proprius hallucis. At the bend of the ankle it is crossed by the 
 tendon of the Extensor proprius hallucis, and lies between it and the innermost 
 tendon of the Extensor longus digitorum. It is covered, in the upper two- 
 thirds of its course, by the muscles which lie on either side of it and by the 
 deep fascia ; in the lower third, by the integument, anterior annular ligament, 
 and fascia. 
 
712 THE BLOOD -VASCULAR SYSTEM 
 
 The anterior tibial artery is accompanied by two veins, venae comites, which 
 lie one on each side of the artery; the anterior tibial nerve, coursing round the 
 outer side of the neck of the fibula, comes into relation with the outer side of the 
 artery shortly after it has passed through the opening in the interosseous mem- 
 brane; about the middle of the leg it is placed superficial to it; at the lower part 
 of the artery the nerve is generally again on the outer side. 
 
 Plan of the Relations of the Anterior Tibial Artery. 
 
 In front. 
 
 Integument, superficial and deep fasciae. 
 
 Anterior tibial nerve. 
 
 Tibialis anticus (overlaps it in the upper part of the leg). 
 
 Extensor longus digitorum I . , . i-p,ux| n 
 
 Extensor proprius hallucis ) ^ " o JJ- 
 
 Anterior annular ligament. 
 
 Inner side. / \ Outer side. 
 
 Tibialis anticus. [ Anterior \ Anterior tibial nerve. 
 
 Extensor proprius hallucis i Tibial. I Extensor longus digitorum. 
 
 (crosses it at its lower V / Extensor proprius hallucis. 
 
 part). -~ -^ 
 
 Behind. 
 
 Interosseous membrane. 
 
 Tibia. 
 
 Anterior ligament of ankle-joint. 
 
 Peculiaxities in Size. — ^This vessel may be very small, may be deficient to a greater or less 
 extent, or may be entirely vi^anting, its place being supplied by perforating branches from the 
 posterior tibial or by the anterior division of the peroneal artery. 
 
 Course. — The artery occasionally deviates in its course toward the fibular side of the leg, 
 regaining its usual position beneath the annular ligament at the front of the ankle. In two 
 instances the vessel has been found to approach the surface in the middle of the leg, being covered 
 merely by the integument and fascia below that point. 
 
 Surface Marking. — Draw a line from the inner side of the head of the fibula to midway 
 between the two malleoli. In this line take a point one inch and a quarter below the head of 
 the fibula, and the portion of the line below this point will mark the course of the artery. 
 
 Surgical Anatomy.— The anterior tibial artery may be tied in the upper or lower part of 
 the leg. In the upper part the operation is attended with great difficulty, on account of the 
 depth of the vessel from the surface. An incision, about four inches in length, should be made 
 through the integument, midway between the spine of the tibia and the outer margin of the 
 fibula, and the deep fascia exposed. The wound must now be carefully dried, its edges retracted, 
 and the white line separating the Tibialis anticus from the Extensor longus digitorum sought 
 for. When this has been clearly defined, the deep fascia is to be divided in this line, and the 
 Tibialis anticus separated from adjacent muscles with the handle of the scalpel or a director until 
 the interosseous membrane is reached. The foot is to be flexed in order to relax the muscles, and 
 upon drawing them apart the artery will be found lying on the interosseous membrane with the 
 nerve on its outer side or on the top of the artery. The nerve should be drawn outward, and 
 the venae comites separated from the artery and the needle passed round it. 
 
 To tie the vessel in the lower third of the leg above the ankle-joint an incision about three 
 inches in length should be made through the integument between the tendons of the Tibialis 
 anticus and Extensor proprius hallucis muscles, the deep fascia being divided to the same extent. 
 The tendon on either side should be held aside, when the vessel will be seen lying upon the 
 tibia, with the nerve on the outer side and one of the venae comites on either side. 
 
 Branches. — The branches of the anterior tibial artery are — the 
 
 Posterior Recurrent Tibial. Muscular. 
 
 Superior Fibular. Internal Malleolar. 
 
 Anterior Recurrent Tibial. External Malleolar. 
 
THE ANTERIOR TIBIAL ARTERY 
 
 713 
 
 Inferior xnierndl 
 articular. 
 
 The Posterior Recurrent Tibial 
 
 (a. recurrens tibialis posterior) is not 
 a constant branch, and is given off 
 from the anterior tibial before that 
 vessel passes through the interosse- 
 ous space. It ascends beneath the 
 Popliteus muscle, which it supplies, 
 and anastomoses with the lower 
 articular branches of the popliteal 
 artery, giving off an offset to the 
 superior tibio-fibular joint. 
 
 The Superior Fibular is some- 
 times given off from the anterior 
 tibial, sometimes from the posterior 
 tibial. It passes outward, round 
 the neck of the fibula, through the 
 Soleus, which it supplies, and ends 
 in the substance of the Peroneus 
 longus muscle. 
 
 The Anterior Recurrent Tibial 
 (a. recurrens tibialis anterior) arises 
 from the anterior tibial as soon as 
 that vessel has passed through the 
 interosseous space; it ascends in the 
 Tibialis anticus muscle, and ramifies 
 on the front and sides of the knee- 
 joint, anastomosing with the artic- 
 ular branches of the popliteal, with 
 the anastomotica magna, and the 
 external articular branches of the 
 popliteal, assisting in the formation 
 of the circumpatellar plexus. 
 
 The Muscular Branches are 
 numerous ; they are distributed to 
 the muscles which lie on each side 
 of the vessel, some cutaneous branches 
 piercing the deep fascia to supply 
 the integument, others passing 
 through the interosseous membrane, 
 and anastomosing with branches 
 of the posterior tibial and peroneal 
 arteries. 
 
 The Malleolar Arteries supply 
 
 the ankle-joint. The internal branch 
 
 (a. malleolaris anterior medialis) 
 
 arises about two inches above the 
 
 articulation, and passes beneath the 
 
 tendons of the Extensor proprius 
 
 hallucis and Tibialis anticus to the 
 
 inner ankle, upon which it ramifies, 
 
 '~1 anastomosing with branches of the 
 
 / posterior tibial and internal plantar arteries and with the internal calcanean 
 
 V^from the posterior tibial. The external branch (a. malleolaris anterior lateralis) 
 
 passes beneath the tendons of the Extensor longus digitorum and Peroneus 
 
 Communicating. 
 
 Fig. 435. — Surgical anatomy of the anterior tibial 
 and dorsalis pedis arteries. 
 
714 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 tertius, and supplies the outer ankle, anastomosing with the anterior peroneal 
 artery and with ascending branches from the tarsal branch of the dorsalis 
 pedis. 
 
 The Dorsalis Pedis Artery (A. Dorsalis Pedis) (Figs. 435, 436). 
 
 The dorsalis pedis, the continuation of the anterior tibial, passes forward from 
 the bend of the ankle along the tibial side of the foot to the back part of the first 
 intermetatarsal space, where it divides into two branches, the dorsalis hallucis and 
 communicating. 
 
 ANTERIOR 
 
 PERONEAL' 
 
 ARTERY 
 
 EXTERNAL 
 
 MALLEOLAR 
 
 ARTERY 
 
 METATARSAL 
 ARTERY 
 
 DORSAL 
 INTEROSSEOUS 
 
 INTERNAL 
 
 MALLEOLAR 
 
 ARTERY 
 
 DORSALIS PEDIS 
 ARTERY 
 
 COMMUNICATING 
 ARTERY 
 
 DORSALIS 
 HALLUCIS 
 ARTERY 
 
 Fig. 436. — Diagram of the arteries of the dorsal surface of the foot. (Poirier and Charpy.) 
 
 Relations. — ^This vessel, in its course forward, rests upon the astragalus, navic- 
 ular, and middle cuneiform bones and the ligaments connecting them, being cov- 
 ered by the integument and fascia, anterior annular ligament, and crossed near 
 its termination by the innermost tendon of the Extensor brevis digitorum. On 
 its tibial side is the tendon of the Extensor proprius hallucis; on its fibular side, 
 the innermost tendon of the Extensor longus digitorum, and the termination of 
 the anterior tibial nerve. It is accompanied by two veins. 
 
THE DOBSALIS PEDIS ABTEJRY 715 
 
 Plan of the Relations of the Dorsalis Pedis Artery. 
 
 In front. 
 Integument and fascia. 
 Anterior annular ligament. 
 Innermost tendon of Extensor brevis digitorum. 
 
 Tibial side. I \ Fibular side. 
 
 Extensor proprius hallucis. I pedis. ) Extensor longus digitorum. 
 
 \ / Anterior tibial nerve. 
 
 Behind. 
 Astragalus. 
 Navicular. 
 Middle cuneiform. 
 And their ligaments. 
 
 Peculiarities in Size. — The dorsal artery of the foot may be larger than usual, to compen- 
 sate for a deficient plantar artery; or it may be deficient in its terminal branches to the toes, 
 which are then derived from the internal plantar; or its place may be supplied altogether by a 
 large anterior peroneal artery. 
 
 Position. — This artery frequently curves outward, lying external to the line between the 
 middle of the ankle and the back part of the first interosseous space. 
 
 Surface Marking. — The dorsalis pedis artery is indicated on the surface of the dorsum of 
 the foot by a line drawn from the centre of the space between the two malleoli to the back of the 
 first intermetatarsal space. 
 
 Surgical Anatomy. — This artery may be tied, by making an incision through the integu- 
 ment between two and three inches in length, on the fibular side of the tendon of the Extensor 
 proprius hallucis, in the interval between it and the inner border of the short Extensor muscle. 
 The incision should not extend farther forward than the back part of the first intermetatarsal 
 space, as the artery divides in that situation. The deep fascia being divided to the same extent, 
 the artery will be exposed, the nerve lying upon its outer side. 
 
 Branches. — The branches of the dorsalis pedis are — the 
 
 Cutaneous. Metatarsal — Interosseous. 
 
 Tarsal. Dorsalis Hallucis. 
 
 Communicating. 
 
 Cutaneous Branches go to the skin of the dorsum and inner surface of the 
 foot. 
 
 The Tarsal Artery (a. tarsea lateralis) arises from the dorsalis pedis, as that 
 vessel crosses the navicular bone; it passes in an arched direction outward, lying 
 upon the tarsal bones, and covered by the Extensor brevis digitorum; it supplies 
 that muscle and the articulations of the tarsus, and anastomoses with branches 
 from the metatarsal, external malleolar, peroneal, and external plantar arteries. 
 
 The Metatarsal (a. arcuata) arises a little anterior to the preceding; it passes 
 outward to the outer part of the foot, over the bases of the metatarsal bones, 
 beneath the tendons of the short Extensor, its direction being influenced by its 
 point of origin; and it anastomoses with the tarsal and external plantar arteries. 
 This vessel gives off three branches, the dorsal interosseous arteries {aa. meta- 
 tarsece dorsales), which pass forward upon the three outer Dorsal interossei mus- 
 cles, and, in the clefts between the toes, divide into two dorsal collateral branches 
 for the adjoining toes {aa. digitales dorsales). At the back part of each inter- 
 osseous space these vessels receive the posterior perforating branches from the 
 plantar arch, and at the forepart of each interosseous space they are joined by 
 the anterior perforating branches from the digital arteries. The outermost 
 interosseous artery gives off a branch which supplies the outer side of the little 
 toe. 
 
716 THE BLOOD -VASCULAR SYSTEM 
 
 The Dorsalis Hallucis or the First Dorsal Interosseous (a. dorsalis hallucis) is one 
 of the terminal branches of the dorsalis pedis. It runs forward along the outer 
 border of the first metatarsal bone, and at the cleft between the first and second 
 toes divides into two branches, one of which passes inward, beneath the tendon of 
 the Extensor proprius hallucis, and is distributed to the inner border of the great 
 toe; the outer branch bifurcates, to supply the adjoining sides of the great and 
 second toes. 
 
 The Communicating Artery {ramus plantaris profwidus), the other terminal 
 branch of the dorsalis pedis, dips down into the sole of the foot, between the two 
 heads of the First dorsal interosseous muscle, and inosculates with the termina- 
 tion of the external plantar artery, to complete the plantar arch. It here gives 
 off its plantar digital branch, which is named the arteria magna hallucis, or the 
 princeps hallucis. This artery passes forward along the first interosseous space, 
 and, after sending a branch along the inner side of the great toe, bifurcates for 
 the supply of the adjacent sides of the great and second toes. 
 
 The Posterior Tibial Artery (A. Tibialis Posterior) (Fig. 434). 
 
 The posterior tibial is an artery of large size, which extends obliquely down- 
 ward from the lower border of the Popliteus muscle, along the tibial side of the 
 leg, to the fossa between the inner ankle and the heel, where it divides beneath 
 the origin of the Abductor hallucis, on a level with a line drawn from the point 
 of the internal malleolus to the centre of the convexity of the heel, into the 
 internal and external plantar arteries. At its origin it lies opposite the interval 
 between the tibia and fibula; as it descends, it approaches the inner side of 
 the leg, lying behind the tibia, and, in the lower part of its course, is situated 
 midway between the inner malleolus and the tuberosity of the os calcis. 
 
 Relations. — It lies successively upon the Tibialis posticus, the Flexor longus 
 digitorum, the tibia, and the back part of the ankle-joint. It is covered by the 
 deep transverse fascia, which separates it above from the Gastrocnemius and 
 Soleus muscles: at its termination it is covered by the Abductor hallucis muscle. 
 In the lower third, where it is more superficial, it is covered only by the integu- 
 ment and fascia, and runs parallel with the inner border of the tendo Achillis. 
 It is accompanied by two veins and by the posterior tibial nerve, which lies at 
 first to the inner side of the artery, but soon crosses it, and is, in the greater part 
 of its course, on its outer side. 
 
 Plan of the Relations of the Posterior Tibial Artery. 
 
 In front. 
 Tibialis posticus. 
 Flexor longus digitorum. 
 Tibia. 
 Ankle-joint. 
 Inner side. Outer side. 
 
 Posterior tibial nerve, Posterior tibial nerve, 
 
 upper third. lower two-thirds. 
 
 Behind. 
 Integument and fascia. 
 Gastrocnemius. 
 Soleus. 
 
 Deep transverse fascia. 
 Posterior tibial nerve. 
 Abductor hallucis. 
 
 Behind the inner ankle the tendons and blood-vessels are arranged, under 
 cover of the internal annular ligament, in the following order, from within out- 
 
THE POSTERIOR TIBIAL ARTERY 'JYJ 
 
 ward: First, the tendons of the Tibiahs posticus and Flexor longus digitorum, 
 lying in the same groove, behind the inner malleolus, the former being the most 
 internal. External to these is the posterior tibial artery, having a vein on either 
 side: and, still more externally, the posterior tibial nerve. About half an inch 
 nearer the heel is the tendon of the Flexor longus hallucis. 
 
 Peculiarities in Size. — The posterior tibial is not unfrequently smaller than usual, or absent, 
 its place being suppHed by a large peroneal artery which passes inward at the lower end of the 
 tibia, and either joins the small tibial artery or continues alone to the sole of the foot. 
 
 Surface Marking. — The course of the posterior tibial artery is indicated by a line drawn from 
 a point one inch below the centre of the popliteal space to midway between the tip of the 
 internal malleolus and the centre of the convexity of the heel. 
 
 Surgical Anatomy. — The application of a ligature to the posterior tibial may be required 
 in cases of wound of the sole of the foot attended with great hemorrhage, when the vessel 
 should be tied at the inner anlvle. In cases of wound of the posterior tibial it will be necessary 
 to enlarge the opening so as to expose the vessel at the wounded point, excepting where the 
 vessel is injured by a punctured wound from the front of the leg. In cases of aneurism from 
 wound of the artery low down, the vessel should be tied in the middle of the leg. But in aneurism 
 of the posterior tibial high up it would be better to tie the femoral artery. 
 
 To tie the posterior tibial artery at the ankle, a semilunar incision, convex backward, should 
 be made through the integument, about two inches and a half in length, midway between the 
 heel and the inner ankle or a little nearer the latter. The subcutaneous cellular tissue having been 
 divided, a strong and dense fascia, the internal annular ligament, is exposed. This ligament is 
 continuous above with the deep fascia of the leg, covers the vessels and nerves, and is intimately 
 adherent to the sheaths of the tendons. This having been cautiously divided upon a director, 
 the sheath of the vessels is exposed, and, being opened, the artery is seen with one of the venae 
 comites on each side. The aneurism needle should be passed round the vessel from the heel 
 toward the ankle, in order to avoid the posterior tibial nerve, care being at the same time taken 
 not to include the vente comites. 
 
 The vessel may also be tied in the lower third of the leg by making an incision, about three 
 inches in length, parallel with the inner margin of the tendo Achillis. The internal saphenous 
 vein being carefully avoided, the Iwo layers of fascia must be divided upon a director, when the 
 artery is exposed along the outer margin of the Flexor longus digitorum, with one of its vense 
 comites on either side and the nerve lying external to it. 
 
 To tie the posterior tibial in the middle of the leg is a very difficult operation, on account of 
 the great depth of the vessel from the surface. The patient being placed in the recumbent posi- 
 tion, the injured limb should rest on its outer side, the knee being partially bent and the foot 
 extended, so as to relax the muscles of the calf. An incision about four inches in length should 
 then be made through the integument a finger's breadth behind the inner margin of the tibia, 
 taking care to avoid the internal saphenous vein. The deep fascia having been divided, the 
 margin of the Gastrocnemius is exposed, and must be drawn aside, and the tibial attachment of 
 the Soleus divided, a director being previously passed beneath it. The artery may now be 
 felt pulsating beneath the deep fascia about an inch from the margin of the tibia. The fascia 
 having been divided, and the limb placed in such a position as to relax the muscles of the calf 
 as much as possible, the veins should be separated from the artery, and the aneurism needle 
 passed round the vessel from without inward, so as to avoid wounding the posterior tibial nerve. 
 
 Branches. — The branches of the posterior tibial artery are — the 
 
 Peroneal. Cutaneous. 
 
 Nutrient. Communicating. 
 
 Muscular. Internal Calcanean. 
 
 Malleolar cutaneous. 
 
 The Peroneal Artery (a. peroncBo) (Fig. 434) lies, deeply seated, along the back 
 part of the fibular side of the leg. It arises from the posterior tibial about an inch 
 below the lower border of the Popliteus muscle, passes obliquely outward to the 
 fibula, and then descends along the inner border of that bone, contained in a 
 fibrous canal between the Tibialis posticus and the Flexor longus hallucis, or in 
 the substance of the latter muscle to the lower third of the leg, where it gives off 
 the anterior peroneal. It then passes across the articulation between the tibia and 
 fibula to the outer side of the os calcis, where it gives off its terminal branches, the 
 external calcanean. 
 
718 THE BLOOD -VASCULAR SYSTEM 
 
 Relations.— This vessel rests at first upon the TibiaHs posticus, and then, for 
 the greater part of its course, in a fibrous canal between the origins of the Flexor 
 longus hallucis and Tibialis posticus, covered or surrounded by the fibres of the 
 Flexor longus hallucis. It is covered, in the upper part of its course, by the Soleus 
 and deep transverse fascia; helow, by the Flexor longus hallucis. 
 
 Plan of the Relations of the Peroneal Artery. 
 
 In front. 
 
 Tibialis posticus. 
 Flexor longus hallucis. 
 
 Outer side. f \ Jnn^r side. 
 
 Fibula. I ^»*T"!f^ I Flexor longus hallucis. 
 
 Flexor longus hallucis. 
 
 Behind. 
 Soleus. 
 
 Deep transverse fascia. 
 Flexor longus hallucis. 
 
 Peculiarities in Origin. — The peroneal artery may arise three inches below the Popliteus, 
 or from the posterior tibial high up, or even from the popliteal. 
 
 Its size is more frequently increased than diminished ; and then it either reinforces the poste- 
 rior tibial by its junction with it, or altogether takes the place of the posterior tibial in the lower 
 part of the leg and foot, the latter vessel only existing as a short muscular branch. In those 
 rare cases where the peroneal artery is smaller than usual a branch from the posterior tibial 
 supplies its place, and a branch from the anterior tibial compensates for the diminished anterior 
 peroneal artery. In one case the peroneal artery has been found entirely wanting. 
 
 The anterior peroneal is sometimes enlarged, and takes the place of the dorsal artery of the 
 foot. 
 
 Branches. — ^The branches of the peroneal are — the 
 
 Muscular. Communicating. 
 
 Nutrient. Posterior Peroneal. 
 
 Anterior Peroneal. External Calcanean. 
 
 Muscular Branches. — The peroneal artery in its course gives off branches to the 
 Soleus, Tibialis posticus. Flexor longus hallucis, and Peronei muscles. 
 
 The Nutrient Artery (a. nutritia fibulcB) supplies the fibula. 
 
 The Anterior Peroneal (ramus perforans) (Fig. 436) pierces the interosseous 
 membrane, about two inches above the outer malleolus, to reach the forepart of 
 the leg, and, passing down beneath the Peroneus tertius to the outer ankle, ramifies 
 on the front and outer side of the tarsus, anastomosing with the external malleolar 
 and tarsal arteries. 
 
 The Communicating (ramus communicans) is given off from the peroneal about 
 an inch from its lower end, and, passing inward, joins the communicating branch 
 of the posterior tibial. 
 
 The Posterior Peroneal passes down behind the outer ankle to the back of the 
 external malleolus, to terminate in branches which ramify on the outer surface 
 and back of the os calcis. 
 
 External Calcanean (ramus calcaneus lateralis) are the terminal branches of the 
 peroneal artery; they pass to the outer side of the heel, and communicate with the 
 external malleolar, and, on the back of the heel, with the internal calcanean 
 arteries. 
 
 Cutaneous Branches come from the posterior tibial and supply the skin of 
 the inner side and back of the leg. 
 
THE POSTERIOR TIBIAL ARTERY 
 
 719 
 
 The Nutrient Artery of the tibia (a. nutricia tibioe) arises from the posterior 
 tibial near its origin, and, after supplying a few muscular branches, enters the 
 nutrient canal of that bone, which it traverses obliquely from above downward. 
 This is the largest nutrient artery of bone in the body. 
 
 The Muscular Branches of the posterior tibial are distributed to the Soleus and 
 deep muscles along the back of the leg. 
 
 The Communicating Branch (ramus communicafis), to join a similar branch 
 of the peroneal, runs transversely across the back of the tibia, about two inches 
 above its lower end, passing beneath the Flexor longus hallucis. 
 
 The Malleolar or Internal Malleolar (a. malleolaris posterior medialis) lies 
 upon the tibia, sends branches over the inner ankle, and anastomoses with the 
 inner malleolar branch of the anterior tibial. 
 
 The Internal Galcanean (rami calcanei mediates) are several large arteries 
 which arise from the posterior tibial just before its division: they are distributed 
 
 Communicating 
 
 branch of 
 dorsalis pedis. 
 Its digital 
 branches. 
 
 Fig. 437. — The plantar arteries. Superficial view. 
 
 Fig. 438. — The plantar artenes. Deep view. 
 
 to the fat and integument behind the tendo Achillis and about the heel, and to the 
 muscles on the inner side of the sole, anastomosing with the peroneal and internal 
 malleolar, and, on the back of the heel, with the external calcanean arteries. 
 
 The Internal Plantar Artery (a. plantaris medialis) (Figs. 437 and 438), much 
 smaller than the external, passes forward along the inner side of the foot. It is 
 at first situated above^ the Abductor hallucis, and then between it and the Flexor 
 brevis digitorum, both of which it supplies. At the base of the first metatarsal 
 bone, where it has become much diminished in size, it passes along the inner border 
 of the great toe, inosculating with its digital branch. Small superficial digital 
 branches accompany the digital branches of the internal plantar nerve and join 
 the plantar digital arteries of the three inner spaces. In addition, this vessel gives 
 off numerous cutaneous branches. 
 
 ' Thi.s refers to the erect position of the body. In the ordinary position for dissection the artery is deeper 
 than the muscle. 
 
720 • THE BLOOD -VASCULAR SYSTEM 
 
 The External Plantar Artery (a. plantaris lateralis) (Figs. 437 and 438), much 
 larger than the internal, passes obliquely outward and forward to the base of the 
 fifth metatarsal bone. It then turns obliquely inward to the interval between 
 the bases of the first and second metatarsal bones, where it anastomoses with 
 the communicating branch from the dorsalis pedis artery, thus completing the 
 plantax axch (arcus plantaris) (Fig. 438). As this artery passes outward, it is first 
 placed between the os calcis and Abductor hallucis, and then between the Flexor 
 brevis digitorum and Flexor accessorius, and as it passes forward to the base of 
 the little toe it lies more superficially between the Flexor brevis digitorum and 
 Abductor minimi digiti, covered by the deep fascia and integument. The remain- 
 ing portion of the vessel is deeply situated : it extends from the base of the meta- 
 tarsal bone of the little toe to the back part of the first interosseous space, and 
 forms the plantar arch; it is convex forward, lies upon the Interossei muscles 
 opposite the tarsal ends of the metatarsal bones, and is covered by the Adductor 
 obliquus hallucis, the flexor tendons of the toes, and the Lumbricales. 
 
 Surface Marking. — The course of the internal plantar artery is represented by a line 
 drawn from the mid-point between the tip of the internal malleolus and the centre of the con- 
 vexity of the heel to the middle of the under surface of the great toe; the external plantar by 
 a line from the same point to within a finger's breadth of the tuberosity of the fifth metatarsal 
 bone. The plantar arch is indicated by a line drawn from this point — i. e., a finger's breadth 
 internal to the tuberosity of the fifth metatarsal bone transversely across the foot to the back of 
 the first interosseous space. 
 
 Surgical Anatomy.^Wounds of the plantar arch are always serious, on account of the 
 depth of the vessel and the important structures which must be interfered with in an attempt 
 to ligate it. They must be treated on similar lines to those of wounds of the palmar arches 
 (see page 665). Delorme has shown that the plantar arch may be ligated from the dorsum of the 
 foot in almost any part of its course by removing a portion of one of the three middle metatarsal 
 bones. 
 
 Branches. — The plantar arch, besides distributing numerous branches to the 
 muscles, integument, and fasciae in the sole, gives off the following branches: 
 
 Posterior Perforating. Digital. 
 
 The Posterior Perforating {rami perforantes posteriores) are three small branches 
 which ascend through the back part of the three outer interosseous spaces, between 
 the heads of the Dorsal interossei muscles, and anastomoses with the interosseous 
 branches from the metatarsal artery. 
 
 The Digital Branches (aa. metatarsece plantares) are four in number, and supply 
 the three outer toes and half the second toe. It will be remembered that the 
 arteria princeps hallucis is the plantar digital branch of the communicating 
 arms in the first interosseous space and supplies the adjacent sides of the great 
 and little toes. The first digital branch of the plantar arch passes outward 
 from the outer side of the plantar arch, and is distributed to the outer side of the 
 little toe, passing in its course beneath the Abductor and short Flexor muscles. 
 The second, third, and fourth run forward along the interosseous spaces, and on 
 arriving at the clefts between the toes divides into collateral digital branches {aa. 
 digitales plantares), which supply the adjacent sides of the three outer toes and 
 the outer side of the sscond. At the bifurcation of the toes each digital artery 
 sends upward, through the forepart of the corresponding interosseous space, a 
 small branch which inosculates with the interosseous branches of the metatarsal 
 artery. These are the anterior perforating branches {rami perforantes anteriores). 
 
 From the arrangement already described of the distribution of the vessels to 
 the toes it will be seen that both sides of the three outer toes and the outer side 
 of the second toe are supplied by branches from the plantar arch ; both sides of 
 the great toe and the inner side of the second are supplied by the communicating 
 branch of the dorsalis pedis. 
 
THE VEINS. 
 
 The Veins are the vessels which serve to return the blood from the capillaries 
 of the different parts of the body to the heart. They consist of two distinct sets 
 of vessels, the pulmonary and systemic veins, and an appendage to the systemic, 
 the portal system. 
 
 The Pulmonary Veins are concerned in the circulation in the lungs. Unlike 
 other vessels of this kind, they contain arterial blood, which they return from the 
 lungs to the left auricle of the heart. The pulmonary veins are four in number. 
 
 i; 
 
 Fig. 439.— Valves of a vein. In the lower part 
 of the figure is seen the parietal valves; the upper 
 part .shows the mouth of a vein guarded by a valve. 
 (Poirier and Charpy.) 
 
 Fig. 440. — Collateral anastomosis of veins. The arrows 
 indicate the direction of the flow of blood (schematic). 
 (Poirier and Charpy.) 
 
 The Systemic Veins are concerned in the general circulation; they return the 
 venous blood from the body generally to the right auricle of the heart. The .sys- 
 temic veins are the superior vena cava, the inferior vena cava, and the coronary 
 sinus. 
 
 The Portal Vein constitutes the portal system. The portal system is in reality 
 an appendage to the systemic venous system. It is confined to the abdominal 
 cavity, returning the venous blood from the viscera of digestion, and carrying it 
 to the liver by a single trunk of large size, the portal vein or vena portae. This 
 vessel ramifies in the substance of the liver and breaks up into a minute network 
 
 46 ( 721 ) 
 
722 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 of capillaries. These capillaries then re-collect to form the hepatic veins, by 
 which the blood is conveyed to the inferior vena cava. 
 
 The veins, like the arteries, are found in nearly every tissue of the body. They 
 commence by minute plexuses which receive the blood from the capillaries. The 
 branches which have their commencement in these plexuses unite together 
 into trunks, and these, in their passage toward the heart, constantly increase in 
 size as they receive tributaries or join other veins. The veins are larger and 
 altogether more numerous than the arteries; hence the entire capacity of the 
 venous system is much greater than that of the arterial, the pulmonary veins 
 excepted, which only slightly exceed in capacity the pulmonary arteries. From 
 the combined area of the smaller venous branches being greater than the main 
 trunks, it results that the venous system represents a cone, the summit of which 
 corresponds to the heart, its base to the circumference of the body. In form the 
 veins are perfectly cylindrical, like the arteries, their walls being collapsed when 
 empty, and the uniformity of their surface being interrupted at intervals by slight 
 constrictions, which indicate the existence of valves in their interior (Fig. 439). 
 They usually retain, however, about the same calibre as long as they receive no 
 branches, but not so uniformly as do the arteries. 
 
 The veins communicate very freely with one another (Fig. 441), especially in 
 certain regions of the body, and this communication exists between the larger 
 
 trunks as well as between the smaller 
 branches. Thus, in the cavity of the 
 cranium and between the veins of the 
 neck, where obstruction would be at- 
 tended with imminent danger to the 
 cerebral venous system, we find that 
 the sinuses and larger veins have large 
 and very frequent anastomoses (Fig. 
 440). The same free communication 
 exists between the veins throughout 
 the whole extent of the spinal canal, 
 and between the veins composing the 
 various venous plexuses in the abdo- 
 men and pelvis, as the spermatic, 
 uterine, vesical, and prostatic. 
 
 Veins have thinner walls than 
 
 arteries, the difference in thickness 
 
 being due to the small amount of 
 
 elastic and muscular tissues which 
 
 the veins contain. The superficial veins usually have thicker coats than the deep 
 
 veins, and the veins of the lower limb are thicker than those of the upper. 
 
 Histology of the Veins.^ — As previously stated, capillaries enter into venules 
 or precapillary veins. The venules empty into larger veins. Vein walls are much 
 thinner than arterial walls. A vein has a much thinner media and much less 
 elastic tissue than an artery, and a very strongly developed adventitia. The 
 intima is a connective-tissue layer containing a small number of elastic fibres 
 and lined with endothelium. The media contains some circular muscle fibres 
 and some fine elastic fibres. In some veins the media is thoroughly well devel- 
 oped (veins of the lower extremities), in others it is practically absent (veins of 
 the retina, of the pia mater, of bone, the superior vena cava). The adventitia 
 IS dense and strong, and is composed of connective-tissue elastic fibres and 
 non-striated muscle fibres placed longitudinally. Fig. 442 shows a transverse sec- 
 tion of part of the wall of a vein. The vein valves (Fig. 439) are composed 
 of intima and contain elastic fibres. The large veins and the veins of medium 
 
 Fig. 441. — The venous circle of Braune (schematic). 
 The arrows indicate the direction of the blood current. 
 (Poirier and Charpy.) 
 
THE PULMONARY VEINS 723 
 
 size possess vasa vasorum, in the adventitia and to some extent in the media. 
 The walls of veins contain vasomotor nerves. " Small blood-vessels are often 
 surrounded by lymph capillaries and sometimes by endothelium-lined spaces 
 which are in communication with the lymphatic system. These are called peri- 
 vascular lymph spaces."* 
 
 The systemic veins are subdivided into three sets: superficial, deep, and sinuses. 
 
 The Superficial or Cutaneous Veins are found between the layers of the super- 
 ficial fascia, immediately beneath the integument; they return the blood from 
 these structures, and communicate with the deep veins by perforating the deep 
 fascia. 
 
 Endothelial and 
 y subendothelial 
 ^^^-^ • layers. 
 
 ^B!Wte'-v-, ^./^t^SSa^ Elastic layer. 
 
 ifll^f '""" ~ ''■''"" " '■^^gBaBBmA\ — Middle coat. 
 
 -Outer coat. 
 
 Fig. 442. — Transverse section of part of the wall of one of the posterior tibial veins. (After Schafer.) 
 
 The Deep Veins accompany the arteries, and are usually enclosed in the same 
 sheath with those vessels. With the smaller arteries — as the radial, ulnar, brachial, 
 tibial, and peroneal — they exist generally in pairs, one lying on each side of the 
 vessel, and are called venae comites. The larger arteries — as the axillary, sub- 
 clavian, popliteal, and femoral — have usually only one accompanying vein. In 
 certain organs of the body, however, the deep veins do not accompany the 
 arteries; for instance, the veins in the skull and spinal canal, the hepatic veins in 
 the liver, and the larger veins returning blood from the osseous tissue. 
 
 Sinuses are venous channels which, in their structure and mode of distribution, 
 differ altogether from the veins. They are found only in the interior of the skull, 
 and consist of channels formed by a separation of the two layers of the dura mater, 
 their outer coat consisting of fibrous tissue, their inner of an endothelial layer 
 continuous with the lining membrane of the veins. 
 
 THE PULMONARY VEINS (V. PULMONALES) (Fig. 443). 
 
 The pulmonary veins return the arterial blood from the lungs to the left auricle 
 of the heart. They are four in number, two for each lung. The pulmonary veins 
 differ from other veins in several respects: 1. They carry arterial instead of 
 venous blood. 2. They are destitute of valves. 3. They are only slightly larger 
 than the arteries they accompany. 4. They accompany those vessels singly. 
 They commence in a capillary network upon the walls of the air-cells, where they 
 are continuous with the capillary ramifications of the pulmonary artery, and, 
 uniting together, form one vessel for each lobule. These vessels, uniting suc- 
 cessively, form a single trunk for each lobe, three for the right and two for the 
 left lung. The vein from the middle lobe of the right lung generally unites with 
 that from the upper lobe, forming two trunks on each side, which open separately 
 into the left auricle. Occasionally they remain separate; there are then three 
 
 * Histology and Microscopic Anatomy. By Szymonowicz and MacCallum. 
 
724 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 veins on the right side. Not unfrequently the two left pulmonary veins terminate 
 by a common opening. 
 
 ^ Within the lung, the branches of the pulmonary artery are in front, the veins 
 behind, and the bronchi between the two. 
 
 At the root of the lung, the veins are in front, the artery in the middle, and the 
 bronchus behind. 
 
 ENTRANCE OF 
 — VENA AZVGOS 
 BRANCH OF PUL- 
 MONARY ARTERY 
 
 Fig. 443. — Pulmonary veins, seen in a dorsal view of the heart and lungs. The left lung is pulled to the 
 left, and the right lung has been partly cut away to show the ramifications of the air-tubes and blood-vessels. 
 (Testut.) 
 
 Within the pericardium, their anterior surface is invested by the serous layer 
 of this membrane. The right pulmonary veins pass behind the right auricle and 
 ascending aorta and superior vena cava; the left pass in front of the thoracic 
 aorta with the left pulmonary artery. 
 
 THE SYSTEMIC VEINS. 
 
 The systemic veins may be arranged into three groups: 1. Those of the head 
 and neck, upper extremity, and thorax, which terminate in the superior vena cava. 
 2. Those of the lower extremity, abdomen, and pelvis, which terminate in the 
 inferior vena cava. 3. The cardiac veins, which open directly into the right auricle 
 of the heart. 
 
 VEINS OF THE HEAD AND NECK. 
 
 The veins of the head and neck may be subdivided into three groups: 1. The 
 veins of the exterior of the head and face. 2. The veins of the neck. 3. The veins 
 of the diplo'e and interior of the cranium. 
 
VEINS OF THE EXTERIOR OF THE HEAD AND FACE 725 
 
 Veins of the Exterior of the Head and Face (Fig. 444). 
 The veins of the exterior of the head and face are — the 
 
 Frontal. 
 Supraorbital. 
 Angular. 
 Facial. 
 
 Temporal. 
 Internal Maxillary. 
 Tempo ro-m axillary. 
 Posterior Auricular. 
 
 Occipital. 
 
 The Frontal Vein {v. frontalis) commences on the anterior part of the skull by 
 a venous plexus which communicates with the anterior tributaries of the temporal 
 vein. The veins converge to form a single trunk, which runs downward near the 
 
 Frontal 
 Communicating 
 branch with 
 hthalmic vein. 
 Angular. 
 
 Interior 
 facial. 
 
 Comm,on 
 facial 
 ngual. 
 yngeai. 
 
 Fig. 444. — Veins of the head and neck. 
 
 middle line of the forehead parallel with the vein of the opposite side, and unites 
 with it at the root of the nose by a transverse branch called the nasal arch (v. naso- 
 frontalis). Occasionally the frontal veins join to form a single trunk, which 
 
726 THE BLOOD -VASCULAR SYSTEM 
 
 bifurcates at the root of the nose into the two angular veins. At the root of 
 the nose the veins diverge and join the supraorbital vein, at the inner angle of 
 the orbit, to form the angular vein. 
 
 The Supraorbital Vein {v. swpraorhitalis) commences on the forehead, com- 
 municating with the anterior temporal vein, and runs downward and inward, 
 superficial to the Occipito-frontalis muscle, receiving tributaries from the neigh- 
 boring structures, and from the frontal vein of the diploe, and joins the frontal 
 vein at the inner angle of the orbit to form the angular vein. 
 
 The Angular Vein {v. angularis), formed by the junction of the frontal and 
 supraorbital veins, runs obliquely downward and outward on the side of the root 
 of the nose, and receives the veins of the ala nasi on its inner side and the superior 
 palpebral veins on its outer side; it moreover communicates with the ophthalmic 
 vein, thus establishing an important anastomosis between this vessel and the 
 cavernous sinus. Some small veins from the dorsum of the nose terminate in the 
 nasal arch. 
 
 The Anterior Facial Vein {v. facialis anterior) commences at the side of the 
 root of the nose, being a direct continuation of the angular vein, which is itself 
 formed by the union of the frontal vein and the supraorbital vein. It lies behind 
 and follows a less tortuous course than the facial artery. It passes obliquely 
 downward and outward, beneath the Zygomaticus major and minor muscles, 
 descends along the anterior border of the Masseter, crosses over the body of the 
 lower jaw, with the facial artery to beneath the angle, and unites with the anterior 
 division of the temporo-maxillary vein {v. facialis posterior) to form the common 
 facial vein. 
 
 The Common Facial Vein (v. facialis communis) is formed by the union of the 
 anterior facial and the anterior division of the temporo-maxillary vein, just beneath 
 the angle of the mandible. The vein is covered by the Platysma myoid muscle, 
 runs downward and backward beneath the Sterno-cleido-mastoid muscle, crosses 
 the external carotid artery, and empties into the internal jugular vein at the level 
 of the hyoid line. It receives a large branch at the anterior border of the Sterno- 
 cleido-mastoid muscle, which comes from the anterior jugular vein in the supra- 
 sternal fossa. 
 
 Tributaries of the Anterior and Common Facial Veins. — The anterior facial vein 
 receives, near the angle of the mouth, communicating tributaries of considerable 
 size, the deep facial or anterior internal maxillary vein, from the pterygoid 
 plexus. It is also joined by the inferior palpebral, the superior and inferior 
 labial veins, the buccal veins from the cheek, and the masseteric veins. The 
 common facial vein receives the submental; the inferior palatine, which returns 
 the blood from the plexus round the tonsil and soft palate; the submaxillary 
 vein, which commences in the submaxillary gland; and, generally, the ranine 
 vein. 
 
 Surgical Anatomy. — There are some points about the facial vein which render it of great 
 importance in surgery. It is not so flaccid as are most superficial veins, and, in consequence of 
 this, remains more patent when divided. It has, moreover, no valves. It communicates freely 
 with the intracranial circulation, not only at its commencement by its tributaries, the angular 
 and supraorbital veins, communicating with the ophthalmic vein, a tributary of the cavernous 
 sinus, but also by its deep branch, which communicates through the pterygoid plexus with the 
 cavernous sinus by branches which pass through the foramen ovale and foramen lacerum 
 medium. These facts have an important bearing upon the surgery of some diseases of the 
 face, for on account of its patency the facial vein favors septic absorption, and therefore any 
 phlegmonous inflammation of the face following a poisoned wound is liable to set up thrombosis 
 in the facial vein, and detached portions of the clot may give rise to purulent foci in other 
 parts of the body. And on account of its communications with the cerebral sinuses these 
 thrombi are apt to extend upward into them and so induce a fatal issue. 
 
VEINS OF THE EXTERIOR OF THE HEAD AND FACE 727 
 
 The Superficial Temporal Vein {w. temporales superficiales) commences by a 
 minute plexus on the side and vertex of the skull, which communicates with the 
 frontal and supraorbital veins in front, the corresponding vein of the opposite 
 side, and the posterior auricular and occipital veins behind. From this network 
 anterior and posterior branches are formed which unite above the zygoma, form- 
 ing the trunk of the vein. The trunk is joined in this situation by a large vein, 
 the middle temporal (v. temporalis media), which receives blood from the sub- 
 stance of the Temporal muscle and pierces the fascia at the upper border of 
 the zygoma. The junction of the superficial temporal and the middle temporal 
 veins forms the common temporal vein (v. temporalis communis), which descends 
 between the external auditory meatus and the condyle of the jaw, enters the 
 substance of the parotid gland, and unites with the internal maxillary vein to form 
 the temporo-maxillary vein. 
 
 Tributaries. — The common temporal vein receives in its course some parotid 
 veins, an articular branch from the articulation of the jaw, anterior auricular veins 
 from the external ear, and a vein of large size, the transverse facial (v. transversa 
 faciei), from the side of the face. The middle temporal vein, previous to its junc- 
 tion with the temporal vein, receives a branch, the orbital vein (v. orhitalis), which 
 is formed by some external palpebral branches, and passes backward between 
 the layers of the temporal fascia. 
 
 The Pterygoid Plexus (plexus pterygoideus) and the Internal Maxillary 
 Vein. — The internal maxillary vein is a vessel of considerable size, receiving 
 branches which correspond with those of the internal maxillary artery. Thus it 
 receives the two middle meningeal veins, the deep temporal, the pterygoid, mas- 
 seteric, buccal, and alveolar veins, some palatine veins, the spheno-palatine and the 
 inferior dental veins. The deep temporal veins {vv. temporales profundce) come to 
 the pterygoid plexus from the temporal muscle. These branches form a large 
 plexus, the pterygoid plexus, which is placed between the Temporal and External 
 pterygoid and partly between the Pterygoid muscles. This plexus is a tributary 
 of the internal maxillary vein, and communicates very freely with the facial vein 
 and with the cavernous sinus by branches through the foramen Vesalii, foramen 
 ovale, and foramen lacerum medium, at the base of the skull. The trunk of 
 the internal maxillary vein comes from the plexus, then passes backward behind 
 the neck of the lower jaw, and unites with the temporal vein, forming the 
 temporo-maxillary vein. 
 
 The Temporo-maxillary Vein (v. facialis posterior), formed by the union of 
 the superficial temporal and internal maxillary veins, descends in the substance of 
 the parotid gland on the outer surface of the external carotid artery, between the 
 ramus of the jaw and the Sterno-mastoid muscle, and divides into two branches, 
 an anterior, which passes inward to join the facial vein, and a posterior, which 
 is joined by the posterior auricular vein and becomes the external jugular. 
 
 The Posterior Auricular Vein (v. auricularis posterior) commences upon the 
 side of the head by a plexus which communicates with the tributaries of the tem- 
 poral and occipital veins. The vein descends behind the external ear and joins 
 the posterior division of the temporo-maxillary vein, forming the external jugular. 
 This vessel receives the stylo-mastoid vein and some tributaries from the back 
 part of the external ear. 
 
 The Occipital Vein (v. occipitalis) commences at the back part of the vertex 
 of the skull by a plexus in a similar manner to the other veins. From the plexus 
 comes one or two veins, which follow the course of the occipital artery, passing 
 deeply beneath the muscles of the back part of the neck, and terminating in the 
 suboccipital triangle by becoming continuous with the posterior vertebral vein. 
 Sometimes they are more superficial, and in this case they are tributaries of the 
 
 k 
 
728 THE BLOOD -VASCULAR SYSTEM 
 
 external jugular vein. As the outermost occipital vein passes across the mastoid 
 portion of the temporal bone, it receives the mastoid vein, which thus establishes 
 a communication with the lateral sinus. 
 
 The Veins of the Neck (Fig. 444). 
 
 The veins of the neck, which return the blood from the head and face, are — the 
 
 External Jugular. Anterior Jugular. 
 
 Posterior External Jugular. • Internal Jugular. 
 
 Vertebral. 
 
 The External Jugular Vein {v. jugularis externa) receives the greater part 
 of the blood from the exterior of the cranium and deep parts of the face, being 
 formed by the junction of the posterior division of the temporo-maxillary and 
 the posterior auricular veins. It commences in the substance of the parotid gland, 
 on a level with the angle of the lower jaw, and runs perpendicularly down the neck 
 in the direction of a line drawn from the angle of the jaw to the middle of the 
 clavicle. In its course it crosses the Sterno-mastoid muscle, and runs parallel with 
 its posterior border as far as its attachment to the clavicle, where it perforates the 
 deep fascia, and terminates in the subclavian vein, on the outer side of, or in front 
 of, the Scalenus anticus muscle. In the neck it is separated from the Sterno- 
 mastoid by the investing layer of the deep cervical fascia, and is covered by the 
 Platysma, the superficial fascia, and the integument. This vein is crossed about 
 its middle by the superficialis colli nerve, and throughout the upper half of its 
 course is accompanied by the auricularis magnus nerve. The external jugular vein 
 varies in size, bearing an inverse proportion to that of the other veins of the neck; 
 it is occasionally double. It is provided with two pairs of valves, the lower pair 
 being placed at its entrance into the subclavian vein, the upper pair in most cases 
 about an inch and a half above the clavicle. The portion of vein between the two 
 sets of valves is often dilated, and is termed the sinus. These valves do not prevent 
 the regurgitation of the blood or the passage of injection from below upward.^ 
 
 Tributaries. — ^This vein receives the occipital occasionally, the posterior external 
 jugular, and, near its termination, the suprascapular and transverse cervical veins. 
 It communicates with the anterior jugular, and, in the substance of the parotid, 
 receives a large branch of communication from the internal jugular. 
 
 The Posterior External Jugular Vein {v. jugularis 'posterior) commences in 
 the occipital region, and returns the blood from the integument and superficial 
 muscles in the upper and back part of the neck, lying between the Splenius and 
 Trapezius muscles. It runs down the back part of the neck, and opens into the 
 external jugular just below the middle of its course. 
 
 The Anterior Jugular Vein (^». jugularis anterior) commences near the 
 hyoid bone from the convergence of the inferior coronary, the submental and the 
 mental veins, and communicating branches. It passes down between the median 
 line and the anterior border of the Sterno-mastoid, and at the lower part of the 
 neck passes beneath that muscle to open into the termination of the external 
 jugular or into the subclavian vein (Fig. 465). This vein varies considerably in 
 size, bearing almost always an inverse proportion to the external jugular. Most 
 frequently there are two anterior jugulars, a right and left, but occasionally only 
 one. This vein receives some laryngeal veins, and occasionally a small thyroid 
 vein. Just above the sternum the two anterior jugular veins communicate by a 
 
 1 The student may refer to an interesting paper by Dr. Struthers, " On Jugular Venesection in Asphyxia. 
 Anatomically and Experimentally Considered, including the Demonstration of Valves in the Veins of the Neck," 
 in the Edinburgh Medical Journal for November, 1856.— Ed. of 15th English edition. 
 
THE VEINS OF THE NECK 
 
 729 
 
 transverse trunk, which receives tributaries from the inferior thyroid veins. It 
 also communicates with the internal jugular. There are no valves in this vein. 
 The Internal Jugular Vein {v. jugularis interna) collects the blood from 
 the interior of the cranium, from the superficial parts of the face, and from the 
 neck. It commences just external to the jugular foramen, at the base of the skull, 
 being formed by the coalescence of the lateral and inferior petrosal sinuses (Fig. 
 458). At its origin it is somewhat dilated, and this dilatation is called the sinus 
 or gulf of the internal jugular vein (bulbus v. jugularis superior). It runs down the 
 side of the neck in a vertical direction, lying at first on the outer side of the internal 
 carotid artery, and then on the outer side of the common carotid artery, and at 
 the root of the neck unites with the subclavian vein to form the innominate vein. 
 Just before its termination it is distinctly dilated {bulhus v. jugularis inferior). The 
 
 DORSALIS 
 LINGU/C ARTERY 
 LINGUAL VEIN 
 VEINS OF 
 DORSUM OF— -^ 
 
 HYPOGLOSSAL NERVE 
 
 Fig. 445. — Veins of the tongue 
 
 (Testut, modified from Hirschfeld.) 
 
 internal jugular vein, at its commencement, lies upon the Rectus capitis lateralis, 
 and behind the internal carotid artery and the nerves passing through the jugular 
 foramen; lower down, the vein and artery lie upon the same plane, the glosso- 
 pharyngeal and hypoglossal nerves passing forward between them ; the pneumo- 
 gastric descends between and behind them in the same sheath, and the spinal 
 accessory passes obliquely outward, behind or in front of, the vein. At the root of 
 the neck the vein of the right side is placed at a little distance from the artery; on 
 the left side it usually lies over the artery at its lower part. The right internal 
 jugular vein crosses the first part of the subclavian artery. The internal jugular 
 vein is of considerable size, but varies in different individuals, the left one being 
 usually the smaller. It is provided with a pair of valves, which are placed at its 
 point of termination or from half to three-quarters of an inch above it. 
 
 Tributaries. — This vein receives in its course the facial, lingual, pharyngeal, 
 superior, and middle thyroid veins. A branch from the cochlea opens into the 
 sinus of the internal jugular vein. A venous plexus from the lateral sinus (plexus 
 venosus caroticus internus) surrounds the internal carotid artery in the carotid 
 canal and empties into the internal jugular vein. At its point of junction with the 
 common facial vein it becomes increased in size. (See Facial Veins, p. 726.) 
 
 The Lingual Veins {vv. linguale) (Fig. 445) commence on the dorsum, sides, and 
 under surface of the tongue, and, passing backward, following the course of the 
 lingual artery and its branches, terminate in the internal jugular. Sometimes the 
 ranine vein, which is a branch of considerable size commencing below the tip of the 
 
730 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 tongue, joins the lingual. Generally, however, it passes backward, crosses the 
 Hyo-glossus muscle in company with the hypoglossal nerve, and joins the internal 
 jugular. The lingual vein receives the subhngual vein and the dorsalis lingute veins. 
 The Phax3mgeal Veins (vv. pharyngeir) vary in number. They commence in a 
 minute plexus, the pharyngeal plexus (plexus pharyngeus), at the back part and 
 sides of the pharynx, and, after receiving meningeal tributaries, the meningeal 
 veins {vv. meningea), the Vidian veins {vv. canalis pterygoidei), and the spheno- 
 palatine veins, terminate in the internal jugular. They occasionally open into the 
 facial, lingual, or superior thyroid vein. 
 
 Fig. 446. 
 
 SUBCLAVIAN 
 
 -The veins of the neck, viewed from in front. 
 
 (Spalteholz.) 
 
 The Superior Th3n:oid Vein {v. thyreoidea superioris) (Fig. 446) commences in the 
 substance and on the surface of the thyroid gland by tributaries corresponding 
 with the branches of the superior thyroid artery, and terminates in the upper 
 part of the internal jugular vein. It receives the superior laryngeal and crico- 
 thyroid veins. Some anatomists teach that there are two superior thyroid veins 
 on each side, the upper vein being the one just considered, the lower vein being 
 the one usually pointed out as the middle thyroid. 
 
 The Middle Thyroid Vein (Fig. 448) collects the blood from the lower part of the 
 lateral lobe of the thyroid gland, and, being joined by some veins from the larynx 
 and trachea, terminates in the lower part of the internal jugular vein. Often in 
 
THE VEINS OF THE NECK 
 
 731 
 
 place of the middle thyroid vein there are two veins, the superior and inferior 
 accessory thyroid. These veins pass into the internal jugular. 
 
 SUPERtOR 
 
 THYROID 
 
 ARTERY 
 
 INFERrOR 
 
 THYROID 
 
 VEIN 
 
 Fig. 447. — Diagram showing common arrangement of thyroid veins. (Kocher.) 
 
 INFERIOR 
 THYROID 
 VEIN 
 
 Fig. 448.— The fascia and middle thyroid veins. The veins here designate^~TBeTnferior thyroid are called by 
 Kocher the thyreoidea ima. (Poirier and Charpy.) 
 
 Veins of the Thyroid Gland^ (Fig. 447) . — On the surface qf the thyroid glands 
 the veins form a plexus between the capsule and the gland. A number of veins 
 
 ' See Kocher's description in Langenbeck's Arch. f. klin. Chir., vol. xxix., and James Berry's description in his 
 treatise on Diseases of the Thyroid Gland. 
 
732 THE BLOOD -VASCULAR SYSTEM 
 
 penetrate the capsule and pass into adjacent trunks. The most important veins 
 coming from the gland are the superior, middle, and inferior thyroids (or instead 
 of the middle thyroid the superior and inferior accessory thyroid) and the 
 thyreoidea ima. 
 
 The superior thyroid vein emerges from the summit of the superior horn of the 
 gland, runs along by the superior thyroid artery, and terminates in the internal 
 jugular vein. A large branch which passes along the inner margin of the upper 
 horn and across the upper surface of the isthmus joins the superior thyroid veins 
 of each side. The middle thyroid vein when present emerges from the side of the 
 gland and empties into the internal jugular. This single vein may be replaced by 
 two veins, the superior and inferior accessory thyroid veins. The superior vein 
 emerges from the outer surface of the upper horn somewhat below the apex. The 
 inferior vein comes from the posterior and inferior portion of the gland. Both 
 empty into the internal jugular. The lower surface of the isthmus and the inner 
 side of each inferior horn is drained by two veins. Each vein is called the thy- 
 reoidea ima (Kocher). The left vein empties into the left innominate vein. The 
 right vein empties into either the right or left innominate vein. These veins may 
 be very small, may be absent, or may join and form one vein which empties into 
 the left innominate. An inferior thyroid is often also present. It comes from the 
 outer portion of the inferior horn of the gland and empties into the innominate vein. 
 
 The facial and occipital veins have been described on pages 726 and 727. 
 
 Surgical Anatomy. — The internal jugular vein occasionally requires ligature in eases of septic 
 thrombosis of the lateral sinus from suppuration in the middle ear. This is done in order to 
 prevent septic emboli being carried into the general circulation. This operation has been 
 performed in a number of cases, with satisfactory results. The cases are generally those of 
 chronic disease of the middle ear, with discharge of pus which perhaps has existed for many 
 years. The patient is seized with acute septic inflammation, spreading to the mastoid cells, 
 and, consequent on this, septic thrombosis of the lateral sinus extending to the internal jugular 
 vein. Such cases are always extremely grave, for there is danger that a portion of the septic 
 clot will be detached and cause septic embolism in the thoracic viscera. If thrombo-phlebitis 
 of the sinus is suspected the mastoid should be opened and cleansed and the sinus should be at 
 once exposed and explored. If the sinus is found to be thrombosed the surgeon should at 
 once proceed to ligate the internal jugular vein, by an incision along the anterior border of the 
 sterno-mastoid, the centre of which is on a level with the greater cornu of the hyoid bone. The 
 vein should be ligated in two places and divided between. After the vessel has been secured 
 and divided the lateral sinus is to be thoroughly cleared out, and, by removing the ligature from 
 the upper end of the divided vein, all septic clots may be removed by syringing from the sinus 
 through the vein. If hemorrhage occurs from the distal end of the sinus, it can be arrested by 
 careful plugging with antiseptic gauze. 
 
 The thyroid veins are small vessels when the gland is of normal size, but become enormous 
 when the gland is much enlarged. 
 
 In the operation of thyroidectomrj the veins as well as the arteries are ligated before the gland, 
 or rather before one lobe of it is extirpated. 
 
 The Vertebral Vein {v. vertebralis) (Fig. 449) commences by numerous small 
 veins from the intraspinal venous plexuses (plexus venosi vertebrates); these pass 
 outward and enter the foramen in the transverse process of the atlas, and descend, 
 forming a dense plexus around the vertebral artery in the canal formed by the 
 foramina in the transverse processes of the cervical vertebrje. The vessels of this 
 plexus unite at the lower part of the neck into two main trunks, one of which 
 emerges from the foramen in the transverse process of the sixth cervical vertebra, 
 and the other through that of the seventh. Uniting, these two trunks form a 
 single vessel which terminates at the root of the neck in the back part of the 
 innominate vein near its origin, its mouth being guarded by a pair of valves. 
 On the right side it crosses the first part of the subclavian artery. 
 
 Tributaries. — ^The vertebral vein receives in its course a vein from the inside 
 of the skull through the posterior condyloid foramen. It anastomoses with the 
 
THE VEINS OF THE DIPLOE 
 
 733 
 
 occipital vein and receives muscular veins from the muscles in the prevertebral 
 region; dorsi-spinal veins, from the back part of the cervical portion of the spine; 
 meningo-rachidian veins, from the interior of the spinal canal; the anterior and 
 posterior vertebral veins ; and close to its termination it is joined by a small vein 
 from the first intercostal space which accompanies the superior intercostal artery. 
 The Anterior Vertebral or Anterior Deep Cervical Vein commences in a plexus 
 around the transverse processes of the upper cervical vertebrae, descends in com- 
 pany with the ascending cervical artery between the Scalenus anticus and Rectus 
 capitis anticus major muscles, and opens into the vertebral vein just before its 
 termination. 
 
 VERTEBRAL- 
 
 POSTERIOR 
 
 DEEP 
 
 CERVICAL 
 
 POSTERIOR 
 
 EXTERNAL 
 
 JUGULAR 
 
 VERTEBRAL 
 
 ASCENDING 
 CERVICAL 
 
 Fig. 449. — The vertebral vein. (Poirier and Charpy.) 
 
 The Posterior Vertebral or Posterior Deep Cervical Vein {v. cervicalis profunda) 
 (Fig. 449) accompanies the profunda cervicis artery, lying between the Com- 
 plexus and Semispinalis colli. It commences in the suboccipital region by com- 
 municating branches from the occipital vein and tributaries from the deep muscles 
 at the back of the neck. It receives tributaries from the plexuses around the spinous 
 processes of the cervical vertebrae, and terminates in the lower end of the vertebral 
 vein. 
 
 The Veins of the Diploe (Vense Diploicae) (Fig. 450). 
 
 The diploe of the cranial bones is channelled in the adult by a number of 
 tortuous canals, the diploic canals or canals of Breschet (canales diploid [Brescheti]) , 
 which are lined by a more or less complete layer of compact tissue. The veins 
 they contain are large and capacious, their walls being thin, and formed only of 
 endothelium resting upon a layer of elastic tissue, and they present at irregular 
 intervals pouch -like dilatations, or culs-de-sac, which serve as reservoirs for the 
 blood. These are the veins of the diploe ; they can only be displayed by removing 
 the outer table of the skull. 
 
 In adult life, as long as the cranial bones are distinct and separable, these 
 veins are confined to the particular bones; but in old age, when the sutures are 
 
734 
 
 THE BLOOD -VASCULAB SYSTEM 
 
 united, they communicate with each other and increase in size. These vessels 
 communicate, in the interior of the cranium, with the meningeal veins and with 
 the sinuses of the dura mater, and on the exterior of the skull with the veins of 
 the pericranium. They are divided into the frontal diploic vein {v. diploica fron- 
 talis), which opens into the supraorbital vein by an aperture in the supraorbital 
 notch and into the superior longitudinal sinus; the anterior temporal diploic vein 
 (v. diploica temporalis anterior), which is confined chiefly to the frontal bone, 
 communicates with the spheno-parietal sinus and, after escaping by an aperture 
 in the great wing of the sphenoid, opens into one of the deep temporal veins; the 
 posterior temporal, or external parietal diploic vein (v. diploica temporalis posterior), 
 is between the emissarium parietale and the emissarium mastoideum; and the 
 occipital diploic vein {v. diploica occipitalis), the largest of the four, which is 
 confined to the occipital bone, and opens into the emissarium occipitale. 
 
 Fig. 450. — Veins of the diploe as displayed by the removal of the outer table of the skull. 
 
 The Emissary Veins are considered on page 743. 
 
 The Meningeal Veins (vv. meningeoe). — They are numerous in the dura mater, 
 are without valves, anastomose freely with each other, do not increase in size as 
 they reach the sinus which receives them, and bear no regular relation to the 
 meningeal arteries. The middle meningeal artery has two vense comites. The 
 other meningeal arteries usually have two apiece, but may have but one. The 
 middle meningeal veins {vv. meningece medics) accompany the middle meningeal 
 artery, are united to the spheno-parietal sinus, pass through the foramen spino- 
 sum, and join the pterygoid plexus. The other meningeal veins empty into the 
 superior longitudinal sinus and communicate with the plexus of the foramen 
 ovale. 
 
 The Cerebral Veins (Venae Cerebri). 
 
 The cerebral veins are remarkable for the absence of valves and for the extreme 
 thinness of their coats. The coats are thin because they contain no muscular 
 tissue. The cerebral veins may be divided into two sets: the superficial veins, 
 which are placed on the surface, and the deep veins, which occupy the interior of 
 the organ. The veins of the brain do not accompany associated arteries. 
 
THE CEREBRAL VEINS 735 
 
 The Superficial or Cortical Cerebral Veins {venoe cerebri externce) (Fig. 546) 
 ramify upon the surface of the brain, being lodged in the sulci between the con- 
 volutions, a few running across the convolutions. They receive branches from the 
 substance of the brain and terminate in the sinuses. They are named, from the 
 position they occupy, superior, median, and inferior cerebral veins. 
 
 The Superior Cerebral Veins (yy. cerebri super iores), eight to twelve in number 
 on each side, return the blood from the convolutions on the superior surface of the 
 hemisphere; they pass forward and inward toward the great longitudinal fissure, 
 where they receive the median cerebral veins ; near their termination they become 
 invested with a tubular sheath of the arachnoid membrane, and open into the 
 superior longitudinal sinus in the opposite direction to the course of the current of 
 the blood. 
 
 The Median Cerebral Veins (v. cerebri mediana) return the blood from the con- 
 volutions of the mesial surface of the corresponding hemisphere; they open into 
 the superior cerebral veins, or occasionally into the inferior longitudinal sinus. 
 
 The Inferior Cerebral Veins {vv. cerebri inferiores) ramify on the lower part of the 
 outer surface and on the under surface of the cerebral hemisphere. Some, collecting 
 tributaries from the under surface of the anterior lobes of the brain, terminate in 
 the cavernous sinus. One vein of large size, the middle cerebral or superficial 
 Sylvian vein (v. cerebri media), commences on the under surface of the temporal 
 lobe, and, running along a portion of the fissure of Sylvius, opens into the cav- 
 ernous sinus. The great anastomotic vein of Trolard or the superficial communi- 
 cating vein establishes a union between the sinuses of the vertex and those of the 
 base of the brain. It comes from one of the superior cerebral veins, passes down- 
 ward into the fissure of Sylvius, and, by means of the middle cerebral vein, effects a 
 communication with the cavernous sinus. The posterior anastomotic vein connects 
 the middle cerebral vein with the lateral sinus. Other veins commence on the 
 under surface of the base of the brain, and unite to form from three to five veins, 
 which open into the superior petrosal and lateral sinuses from before backward. 
 
 The Deep Cerebral, Central, or Ventricular Veins, Veins of Galen (venoe 
 Galeni, vv. cerebri internoe) (Fig. 548), are two in number. Each is formed by 
 the union of two veins, the vena corporis striati, and the choroid vein, on either side. 
 The deep cerebral veins run backward, parallel with one another, between the 
 layers of the velum interpositum, and in the region of the pineal body unite 
 to form one vein, the vena magna Galeni {v. cerebri magna), which passes out 
 of the brain at the great transverse fissure, between the posterior extremity, or 
 splenium, of the corpus callosum and the tubercula quadrigemina, to enter the 
 straight sinus. The two deep cerebral veins receive branches from the callosal 
 region, from a portion of the occipital lobe, and just before their union each vein 
 receives the basilar vein. The vena magna Galeni receives the vermian vein from 
 the superficial cerebellar veins. 
 
 The Vena Corporis Striati on each side commences in the groove between the 
 corpus striatum and thalamus opticus, receives numerous veins from both of these 
 parts, and unites behind the anterior pillar of the fornix with the choroid vein to 
 form one of the deep cerebral veins. 
 
 The Choroid Vein {v. choroidea) originates in the extreme end of the middle 
 cornu of the lateral ventricle and runs along the whole length of the outer border of 
 the choroid plexus, receiving veins from the hippocampus major, the fornix, and 
 corpus callosum, and unites, at the anterior extremity of the choroid plexus, with 
 the vein of the corpus striatum to form the deep cerebral vein of that side. 
 
 The Basilar Vein (v. basalis) commences at the anterior perforated space at the 
 base of the brain by the union of a small anterior cerebral vein, which courses 
 backward between the anterior lobes of the cerebrum, with the deep Sylvian vein, 
 which descends through the lower part of the Sylvian fissure and receives veins from 
 
736 THE BLOOD -VASCULAR SYSTEM 
 
 the island of Reil. It passes backward over the crus cerebri, receiving the inferior 
 striate vein from the corpus striatum, interpeduncular veins from the interpedun- 
 cular space, ventricular veins from the middle cornu of the lateral ventricles, and 
 tributaries from the uncinate convolution, and enters the vein of Galen just 
 before its junction with the vein of the opposite side. 
 
 The Superficial Cerebellar Veins (Fig. 546) occupy the surface of the cere- 
 bellum, and are disposed in two sets, superior and inferior. 
 
 The Superior Superficial Cerebellar Veins {vv. cerebelli swperiores) pass partly 
 forward and inward, across the superior vermiform process, to terminate in lateral 
 branches which pass partly to the straight sinus and partly outward to the lateral 
 and superior petrosal sinuses. 
 
 The Inferior Superficial Cerebellar Veins {vv. cerebelli inferiores), of large size, 
 terminate in the lateral, inferior petrosal, and occipital sinuses. 
 
 The Deep Cerebellar Veins bring blood from the interior of the cerebellum 
 to the superficial veins. 
 
 Veins of the Pons Varolii. — Veins come from the depth of the pons, the deep 
 veins, and empty into a plexus of superficial veins. From this superficial venous 
 plexus a superior vein passes to the basilar vein, and an inferior vein either into a 
 cerebellar vein or into the superior petrosal sinus. 
 
 Veins of the Medulla Oblongata. — Veins pass from the depth of the medulla and 
 end in a plexus on the surface. From this plexus comes an anterior median 
 vein, which is a prolongation of a like vein of the spinal cord — a posterior median 
 vein corresponding to a like vein of the cord — and small branches which pass 
 with the roots of the ninth, tenth, eleventh, and twelfth cranial nerves, and empty 
 into the occipital and the inferior petrosal sinuses. 
 
 The perivascular lymph-spaces are especially found in connection with the vessels of the brain. 
 These vessels are enclosed in a sheath, which acts as a lymphatic channel, through which the 
 lymph is carried to the subarachnoid and subdural spaces, from which it is returned into the 
 general circulation. 
 
 The Sinuses of the Dura Mater (Sinus Diirae Matris)(Figs.451, 452 ,453,456,457) 
 Ophthalmic Veins and Emissary Veins. 
 
 The sinuses of the dura mater are venous channels, analogous to the veins. 
 The outer coat of a sinus is formed by the dura mater; the inner coat, by a 
 continuation of the lining membrane of the veins. The thick walls of a sinus 
 resist intracranial pressure.^ They are divided into two sets: (1) those situated 
 at the upper and back part of the skull; (2) those at the base of the skull. The 
 former are — the 
 
 Superior Longitudinal Sinus. Straight Sinus. 
 
 Inferior Longitudinal Sinus. Lateral Sinuses. 
 
 Occipital Sinus. 
 
 The Superior Longitudinal Sinus (sinus sagittalis superior) (Figs. 451, 452, 
 and 453) occupies the attached margin of the falx cerebri. Commencing at the 
 foramen caecum, through which, in the child, it constantly communicates by a 
 small branch with the veins of the nasal fossse, it runs from before backward, 
 grooving the inner surface of the frontal, the adjacent margins of the two parietal, 
 and the superior division of the crucial ridge of the occipital bone, and terminates 
 by opening into the torcular Herophili. The sinus is triangular on transverse 
 section, is narrow in front, and gradually increases in size as it passes backward. 
 On examining its inner surface it presents the internal openings of the superior 
 cerebral veins, which run, for the most part, from behind forward, and open 
 
 1 A. W. Hughes. 
 
THE SINUSES OF THE DUB A MATER 
 
 737 
 
 chiefly at the back part of the sinus, their orifices being concealed by fibrous 
 folds; numerous fibrous bands, chordae Willisii (Fig. 453), are also seen extend- 
 ing transversely across the inferior angle of the sinus; and some small, white, 
 projecting bodies, the glandulse Pacchioni (granulationes arachnoidales) . This 
 sinus communicates by numerous small apertures with spaces in the dura 
 mater known as lacunae laterales or parasinoidal spaces (Fig. 453). The 
 
 SUPERIOR 
 
 LONGITUDINAL 
 
 SINUS 
 
 STRAIGHT 
 SINUS 
 
 _. LATERAL 
 SINUS 
 
 Fig. 451. 
 
 -Coronal section of the skull to show tne situations and shapes of the chief sinuses. 
 (Poirier and Charpy.) 
 
 Pacchionian bodies project into these spaces. This sinus receives the superior 
 cerebral veins, numerous veins from the diploe and dura mater, the outlets of the 
 parasinoidal spaces, and, at the posterior extremity of the sagittal suture, veins 
 from the pericranium, which pass through the parietal foramina. In children a 
 twig from the longitudinal sinus passes through the foramen csecum and into 
 the nose. 
 
 Torcular herophili. 
 
 Foramen csccum. 
 
 Fig. 452. — Vertical section of the skull, showing the sinuses of the dura mater. 
 
 The Torcular Herophili or the confluence of the sinuses (Figs. 452 and 456) is the 
 dilated extremity of the superior longitudinal sinus. It is of irregular form, and 
 
 47 
 
738 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 is lodged on one side (generally the right) of the internal occipital protuberance. 
 From it the lateral sinus of the side to which it is deflected is derived. It receives 
 also the blood from the occipital sinus. 
 
 The Inferior Longitudinal Sinus (sinus sagittalis inferior) (Fig. 452), more 
 correctly described as the inferior longitudinal vein, is contained in the posterior 
 part of the free margin of the falx cerebri. It is of a cylindrical form, increases 
 in size as it passes backward, and terminates in the straight sinus. It receives 
 several veins from the falx cerebri, and occasionally a few from the mesial surface 
 of the hemispheres. 
 
 The Straight Sinus (sinus rectus) (Figs. 451 and 452) is situated at the line of 
 junction of the falx cerebri with the tentorium. It is triangular in form, increases 
 in size as it proceeds backward, and runs obliquely downward and backward from 
 
 MENINGEAL 
 VEIN 
 
 SUPERIOR 
 
 LONGITUDINAL 
 
 SINUS 
 
 \ PARASI- 
 
 NOIDAL 
 SINUS 
 
 PARASINOIDAL 
 SINUS 
 
 Fig. 453. — ^Superior longitudinal sinus seen from above after removal of the skull-cap. The chorda Willisii 
 are clearly visible. The para-sinoidal sinuses are also well shown. Probes passing from the latter to the 
 longitudinal sinus show that they communicate. (Poirier and Charpy.) 
 
 the termination of the inferior longitudinal sinus to the lateral sinus of the oppo- 
 site side to that into which the superior longitudinal sinus is prolonged. It com- 
 municates by a cross-branch with the torcular Herophili. Besides the inferior 
 longitudinal sinus, it receives the vena magna Galeni and the superior cerebellar 
 veins. A few transverse bands cross its interior. This sinus is usually considered 
 to be formed by the union of the great vein of Galen and the inferior longitudinal 
 sinus. 
 
 The Lateral Sinus (sinus transversus) (Figs. 451, 452, 456, and 457) is of 
 large size. There are two lateral sinuses situated in the attached margin of 
 the tentorium cerebelli throughout most of its extent. They commence at 
 
THE SINUSES OF THE DUBA MATER 739 
 
 the internal occipital protuberance, one, generally the right, being the direct 
 continuation of the superior longitudinal sinus, the other of the straight sinus. 
 Each passes outward and forward, describing a slight curve with its convexity 
 upward, to the base of the petrous portion of the temporal bone, then, leaving 
 the tentorium, curves downward and inward to reach the jugular foramen, 
 where it terminates in the internal jugular vein. It rests, in its course, upon 
 the inner surface of the occipital, the posterior inferior angle of the parietal, 
 and the mastoid portion of the temporal bone, and on the occipital again, at 
 the jugular process, just before its termination. The portion of the sinus rest- 
 ing on the mastoid process of the temporal and the jugular process of the 
 occipital bone is not covered by the tentorium and is often called the sigmoid 
 sinus because of its shape, which resembles the letter S. These sinuses are fre- 
 quently of unequal size, that formed by the superior longitudinal sinus being 
 the larger, and they increase in size as they proceed from behind forward. The 
 horizontal portion is of a triangular form, the curved portion semicylindrical. 
 Their inner surface is smooth, and not crossed by the fibrous bands found in the 
 other sinuses. The lateral sinuses receive the blood from the superior petrosal 
 sinuses at the base of the petrous portion of the temporal bone, and they unite 
 with the inferior petrosal sinus, just external to the jugular foramen, to form the 
 internal jugular vein (Fig. 457). They communicate with the veins of the 
 pericranium by means of the mastoid and posterior condyloid veins, and they 
 receive some of the inferior cerebral and inferior cerebellar veins, some veins 
 from the diploe, and often veins from the internal ear {w. auditivcB internae), 
 which come out of the internal auditory meatus. The petro-squamous sinus, when 
 present, runs backward along the junction of the petrous and squamous portions 
 of the temporal bone, and opens into the lateral sinus. 
 
 Surgical Anatomy. — The lateral sinus may, as a result of middle-ear disease, be attacked by 
 suppurative inflammation, which leads to blocking {septic thrombo-phlebitis) . In such a case 
 the surgeon will be obliged to open the sinus to remove infected clot and tie the internal jugular 
 vein to intercept thrombi. The lines overlying the sinus is as follows: Draw a line horizontally 
 outward from the occipital protuberance to a point one inch posterior to a vertical line drawn 
 through the external auditory meatus and from this point drop a second line to the mastoid 
 process. 
 
 The Occipital Sinus (sinus occipitalis) (Fig. 452) is the smallest of the cranial 
 sinuses. There is often but a single occipital sinus, but occasionally there are 
 two. It is situated in the attached margin of the falx cerebelli. It commences 
 by several small veins around the margin of the foramen magnum, one of which 
 joins the termination of the lateral sinus; it communicates with the posterior 
 spinal veins and terminates in the torcular Herophili. 
 
 The sinuses at the base of the skull are — the 
 
 Cavernous Sinuses. Superior Petrosal Sinuses. 
 
 Spheno-parietal Sinuses. Inferior Petrosal Sinuses. 
 
 Circular Sinus. Transverse Sinus. 
 
 The Cavernous Sinus (sinus cavernosu^) (Figs. 456 and 457) is named from 
 presenting a reticulated structure, due to being traversed by numerous interlacing 
 filaments (Fig. 454). There are two cavernous sinuses, of irregular form, larger 
 behind than in front, and placed one on each side of the sella turcica, extending 
 from the sphenoidal fissure to the apex of the petrous portion of the temporal bone. 
 Each receives anteriorly the ophthalmic vein through the sphenoidal fissure, and 
 opens behind into the petrosal sinuses. On the inner wall of each sinus is found 
 the internal carotid artery, accompanied by filaments of the carotid plexus and 
 by the sixth nerve; and on its outer wall, the third, fourth, and ophthalmic division 
 
740 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 of the fifth nerve (Fig. 454) . These parts are separated from the blood flowing 
 along the sinus by the lining membrane, which is continuous with the inner coat 
 of the veins. The cavernous sinuses receive some of the cerebral veins, and also 
 the spheno-parietal sinuses. They communicate with the lateral sinuses by 
 means of the superior and inferior petrosal sinuses, and with the facial veins 
 through the ophthalmic veins. They also communicate with each other by means 
 of the circular sinus. 
 
 TRANSVERSE 
 SINUS 
 
 CAVERNOUS 
 
 ilNUS 
 
 
 THIRD 
 NERVE 
 
 OPHTHALMIC 
 DIVISION OF 
 FIFTH NERVE 
 
 SUPERIOR MAXIL 
 LARY DIVISION 
 OF FIFTH NERVE 
 
 Fig. 454. — Frontal section through the right ca\ernoui5 sinus (Spalteholz.) 
 
 Surgical Anatomy. — An arterio-venous communication may be established between the 
 cavernous sinus and the carotid artery, as it lies in it, giving rise to a 'pulsating tumor in the 
 orbit. Such a communication may be the resuH of injury, such as a bullet wound, a stab, or 
 a blow or fall sufficiently severe to cause a fracture of the base of the skull in this situation, 
 or it may occur from the rupture of an aneurism or a diseased condition of the internal 
 carotid artery. The disease begins with sudden noise and pain in the head, followed by 
 exophthalmos, swelling and congestion of the lids and conjunctivae. A pulsating tumor 
 develops at the margin of the orbit, with thrill and the characteristic bruit; accompanying 
 these symptoms there may be impairment of sight, paralysis of the iris and orbital muscles, 
 and pain of varying intensity. In some cases the opposite orbit becomes affected by the passage 
 of the arterial blood into the opposite sinus by means of the circular sinus. Or the arterial 
 blood may find its way through the emissary veins into the pterygoid plexus, and thence into the 
 veins of the face. Pulsating tumors of the orbit may also be due to traumatic aneuri.sm of 
 one of the orbital arteries, and symptoms resembling those of pulsating tumor may be produced 
 by pressure on the ophthalmic vein, as it enters the sinus, by an aneurism of the internal 
 carotid artery. 
 
 The Spheno-parietal Sinus or Sinus Alse Parvae {sinus sphenoparietalis).— 
 Each of these sinuses is lodged in the dura mater on the imder surface of the 
 lesser wing of the sphenoid bone. It takes origin from one of the middle menin- 
 geal veins, usually receives blood from the diploe of the skull, passes inward, and 
 ends in the anterior part of the cavernous sinus. 
 
 The Ophthalmic Veins are two in number, superior and inferior. 
 
 The superior ophthalmic vein (v. ophthalmica superior) (Fig. 455) begins as the 
 naso-frontal vein (v. nasofrontalis) , at the inner angle of the orbit, which communi- 
 cates with the angular vein. It joins the angular vein with the cavernous sinus; 
 it pursues the same course as the ophthalmic artery, and receives tributaries corre- 
 sponding to the branches derived from that vessel. Forming a short single trunk, 
 it passes through the inner extremity of the sphenoidal fissure, and terminates in 
 the cavernous sinus. It anastomoses with the inferior ophthalmic vein and receives 
 lachrymal, anterior, and posterior ethmoidal and muscular branches, and veins 
 of the eyelids and of the bulbus oculi. 
 
THE SINUSES OF THE DURA MATEB 
 
 741 
 
 The inferior ophthalmic vein {v. ophthalmica inferior) (Fig. 455) arises in the veins 
 of the eyelids and lachrymal sac, receives the veins from the floor of the orbit, and 
 
 CAVERNOUS 
 SINUS 
 
 INFERIOR 
 OPHTHALMIC 
 
 Fig. 455 — Veins of the orbit. (Poirier and Charpy.) 
 
 from the portion of the nasal fossa supplied by the anterior and posterior ethmoidal 
 arteries. It either passes out of the orbit through the spheno-m axillary fissure to 
 join the pterygoid plexus of veins, or else, passing backward through the sphenoidal 
 
 Opening of mastoid 
 vein. 
 
 ' Torcular Herophili. 
 Fig. 456.— The sinuses at the base of the skull. 
 
 fissure, it enters the cavernous sinus, either by a separate opening, or, more fre- 
 quently, in common with the superior ophthalmic vein. It receives muscular 
 
742 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 branches and veins of the bulbus ocuh, and anastomoses with the superior 
 ophthalmic vein. 
 
 The Circular Sinus (sinus circularis) (Figs. 454 and 456) is formed by two 
 transverse vessels, the anterior and posterior intercavernous sinuses {sinus inter- 
 cavernous anterior and sinu^ intercavernous posterior), which connect together the 
 two cavernous sinuses ; the one passing in front and the other behind the pituitary 
 body, and thus forming with the cavernous sinuses a venous circle around that 
 body. The anterior one is usually the larger of the two, and one or other is occa- 
 sionally found to be absent. 
 
 •' Falx cerebri 
 
 Optic nerve 
 Int. carotid artery 
 
 Motor oculi nerve 
 
 Inferior 
 petrosal sinus 
 
 Dorsum sellse 
 
 9th, 10th, and 11th 
 cranial nerves 
 
 Lateral sinus 
 Fig. 457. — Relation of nerves to sinuses in jugular foramen. (Henle.) 
 
 The Superior Petrosal Sinus (sinv^ petrosus superior) (Figs. 452 and 456) 
 is situated along the superior border of the petrous portion of the temporal 
 bone, in the front part of the attached margin of the tentorium. It is small 
 and narrow, and connects together the cavernous and lateral sinuses at each side. 
 It receives some cerebellar and inferior cerebral veins, and usually veins from the 
 tympanic cavity (vv. auditivoB internee). 
 
 The Inferior Petrosal Sinus {sinus petrosus inferior) (Figs. 452 and 456) is 
 situated in the groove formed by the junction of the posterior border of the 
 petrous portion of the temporal with the basilar process of the occipital bone. 
 It commences in front at the termination of the cavernous sinus, and behind joins 
 the lateral sinus after it has passed through the jugular foramen; the junction of 
 these two sinuses forming the commencement of the internal jugular vein. The 
 inferior petrosal sinus receives a vein from the internal ear and also veins from 
 the medulla, pons, and under surface of the cerebellum. 
 
 The junction of the two sinuses takes place at the lower border of, or just 
 external to, the jugular foramen. The exact relation of the parts to one another 
 
THE SINUSES OF THE DURA MATER 743 
 
 in the foramen is as follows: The inferior petrosal sinus is in front, with the 
 meningeal branch of the ascending pharyngeal artery, and is directed obliquely 
 downward and backward; the lateral sinus is situated at the back part of the 
 foramen with a meningeal branch of the occipital artery, and between the two are 
 the glosso-pharyngeal, pneumogastric, and spinal accessory nerves (Fig. 457). 
 These three sets of structures are divided from each other by two processes of 
 fibrous tissue. The junction of the sinuses takes place superficial to the nerves, 
 so that these latter lie a little internal to the venous channels in the foramen (see 
 Fig. 457). These sinuses are semicylindrical in form. 
 
 The Transverse or Basilar Sinus {plexus hasilaris) (Figs. 456 and 457) con- 
 sists of several interlacing veins between the layers of the dura mater over the 
 basilar process of the occipital bone, which serve to connect the two inferior 
 petrosal sinuses. With them the anterior spinal veins communicate. 
 
 Emissary Veins (emissaria) . — The emissary veins are vessels which pass 
 through apertures in the cranial wall and establish communications between the 
 sinuses inside the skull and the diploic veins in the diploe, and the veins external 
 to the skull. Some of these are always present, others only occasionally so. 
 They vary much in size in different individuals. The principal emissary veins 
 are the following: 1. A vein, almost always present, which passes through the 
 mastoid foramen (emissarium masioideum) and connects the lateral sinus with 
 the posterior auricular or with an occipital vein. 2. A constant vein which 
 passes through the parietal foramen {emissarium parietale) and connects the 
 superior longitudinal sinus with the veins of the scalp. 3. A plexus of minute veins 
 which pass through the anterior condyloid foramen {emissarium condyloideum) 
 and connect the occipital sinus with the vertebral vein and deep veins of the neck. 
 4. An inconstant vein which passes through the posterior condyloid foramen and 
 connects the lateral sinus with the deep veins of the neck. 5. One or two veins 
 of considerable size which pass through the foramen ovale and connect the cav- 
 ernous sinus with the pterygoid and pharyngeal plexuses. 6. Two or three small 
 veins which pass through the foramen lacerum medium and connect the cavernous 
 sinus with the pterygoid and pharyngeal plexuses. 7. There is sometimes a small 
 vein connecting the same parts and passing through the inconstant foramen of 
 Vesalius at the root of the pterygoid process of the sphenoid bone. 8. A plexus of 
 veins passing through the carotid canal and connecting the cavernous sinus with 
 the internal jugular vein. 9. A small vein {emissarium occipitale) usually con- 
 nects the occipital vein with the lateral sinus or the torcular Herophili and the 
 occipital diploic vein. 
 
 Surgical Anatomy. — These emissary veins are of great importance in surgery. In addition 
 to them there are, however, other communications between the intra- and extra-cranial circula- 
 tion, as, for instance, the communication of the angular and supra-orbital veins with the ophthal- 
 mic vein at the inner angle of the orbit, and the communication of the veins of the scalp with 
 the diploic veins. Through these communications inflammatory processes commencing on the 
 outside of the skull may travel inward, leading to osteo-phlebitis of the diploe and inflammation 
 of the membranes of the brain. To this in former days was to be attributed one of the principal 
 dangers of scalp wounds and other injuries of the scalp. 
 
 By means of these emissary veins blood may be abstracted almost directly from the intra- 
 cranial circulation. For instance, leeches applied behind the ear abstract blood almost directly 
 from the lateral sinus by means of the vein passing through the mastoid foramen. Again, 
 epistaxis in children will frequently relieve severe headache, the blood which flows from the nose 
 being derived from the longitudinal sinus by means of the vein which passes through the foramen 
 caecum, which is another communication between the intracranial and extracranial circulation 
 constantly found in children. 
 
744 THE BLOOD -VASCULAR SYSTEM 
 
 VEINS OF THE UPPER EXTREMITY AND THORAX. 
 
 The veins of the Upper Extremity are divided into two sets, superficial and 
 deep. 
 
 The Superficial Veins are placed immediately beneath the integument between 
 the layers of superficial fascia. * 
 
 Fig. 458. — The veins on the dorsum of the hand. (Bourgery.) 
 
 The Deep Veins accompany the arteries, and constitute the venae comites of 
 those vessels. 
 
 Both sets of vessels are provided with valves, which are more numerous in the 
 deep than in the superficial veins. 
 
THE SUPERFICIAL VEINS OF THE UPPER EXTREMITY 745 
 
 The Superficial Veins of the Upper Extremity (Fig. 459). 
 
 The superficial veins of the upper extremity are — the 
 
 Superficial Veins of the Hand. Median. 
 
 Anterior Ulnar. Median Cephalic. 
 
 Posterior Ulnar. Median Basilic. 
 
 Common Ulnar. Basilic. 
 
 Radial. Cephalic. 
 
 The Superficial Veins of the Hand and Fingers (Figs. 458 and 459) are 
 principally situated on the dorsal surface. These dorsal veins begin in each finger 
 as a venous plexus, in which are distinct veins running in a longitudinal direction, 
 and called dorsal digital veins {vv. digitales dorsales propria^). The dorsal digital 
 veins terminate over the first phalanges, in the venous arches of the fingers {arcus 
 venosi digitales). From these arches take origin the four dorsal interosseous or 
 the interdigital veins (vv. metacarpecB dorsales). These veins form the dorsal venous 
 plexus of the hand (rete venosum dor sale manus). This plexus lies in a line w^ith the 
 lower ends of the shafts of the metacarpal bones. It receives the dorsal inter- 
 osseous veins, the radial digital vein of the index finger, and numerous superficial 
 veins from the back of the hand. It gives origin to the superficial radial vein and 
 the posterior ulnar vein. The superficial veins of the palmar surface are of less 
 diameter than the dorsal veins. They arise from each of the phalanges by a 
 plexus {vv. digitales volares propria;). Vessels at the edges of the fingers take most 
 of the blood to the dorsal veins. There are also veins in the finger webs (vv. inter- 
 capitulares) , which take blood from the palm to the dorsum. A superficial plexus, 
 the palmar plexus, lies upon the palmar fascia, the fascia of the thenar eminence, 
 and the fascia of the hypothenar eminence. 
 
 The Anterior Ulnar Vein (v. ulnaris anterior) (Fig. 459) commences on the 
 anterior surface of the ulnar side of the hand and wrist, and ascends along the 
 anterior surface of the ulnar side of the forearm to the bend of the elbow, where 
 it joins with the posterior ulnar vein to form the common ulnar. Occasionally it 
 opens separately into the median basilic vein. It communicates with branches 
 of the median vein in front and with the posterior ulnar behind. 
 
 The Posterior or Dorsal Ulnar Vein (v. ulnaris posterior) (Fig. 458) commences 
 on the posterior surface of the ulnar side of the wrist. It runs on the posterior 
 surface of the ulnar side of the forearm, and just below the elbow unites with 
 the anterior ulnar vein to form the common ulnar, or else joins the median 
 basilic and helps to form the basilic. It communicates with the deep veins 
 of the palm by a branch which emerges from beneath the Abductor minimi digiti 
 muscle. 
 
 The Common Ulnar Vein (v. ulnaris communis) (Fig. 459) is a short trunk 
 which is not constant. When it exists it is formed by the junction of the two 
 preceding veins, and, passing upward and outward, joins the median basilic to 
 form the basilic vein. When it does not exist the anterior and posterior ulnar 
 veins open separately into the median basilic vein. 
 
 The Radial Vein (1;. radiaUs) (Figs. 459 and 460) commences upon the dorsal 
 surface of the wrist, communicating with the deep veins of the palm by a branch 
 which passes through the first interosseous space. The radial vein soon forms a 
 large vessel, which ascends along the radial side of the forearm and receives 
 numerous veins from both its surfaces. At the bend of the elbow it unites with 
 the median cephalic to form the cephalic vein. Spalteholz considers the ulnar 
 vein as a portion of the basilic and the radial vein a portion of the cephalic. 
 
 The Median Vein (v. mediana cubiti) (Fig. 459) ascends on the front of the 
 forearm, and communicates with the anterior ulnar and radial veins. At the bend 
 
746 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 Median cephalic. 
 
 External 
 cutaneous nerve. 
 
 r Internal 
 < cutaneous 
 ( nerve. 
 Median 
 basilic. 
 
 'Common 
 ulnar. 
 
 Fig. 459. — The superficial veins of the flexor aspect 
 of the upper extremity. 
 
 of the elbow it receives a branch of 
 communication from the deep veins, 
 the deep median vein, and di\ides into 
 two branches, the median cephalic and 
 median basilic, which diverge from each 
 other as they ascend. 
 
 The Median Cephalic (v. mediana 
 cephalica) (Fig. 459) , usually the smaller 
 of the two, passes outward in the groove 
 between the Supinator longus and Bi- 
 ceps muscles, and joins with the radial 
 to form the cephalic vein. The branches 
 of the external cutaneous nerve pass 
 beneath this vessel. 
 
 The Median Basilic Vein (v. mediana 
 basilica) (Fig. 459) passes obliquely in- 
 ward, in the groove between the Biceps 
 and Pronator radii teres muscles, and 
 joins the common ulnar to form the 
 basilic. This vein passes in front of 
 the brachial artery, from which it is 
 separated by a fibrous expansion, the 
 bicipital fascia, which is given off from 
 the tendon of the Biceps to the fascia 
 covering the Flexor muscles of the fore- 
 arm. Filaments of the internal cuta- 
 neous nerve pass in front as well as 
 behind this vessel.^ 
 
 Venesection is usually performed at the 
 bend of the elbow, and as a matter of practice 
 the largest vein in this situation is commonly 
 selected. This is usually the median basilic, 
 and there are anatomical advantages and dis- 
 advantages in selecting this vein. The advan- 
 tages are, that in addition to its being the 
 largest, and therefore yielding a greater supply 
 of blood, it is the least movable and can be 
 easily steadied on the bicipital fascia on which 
 it rests. The disadvantages are, that it is in 
 close relationship with the brachial artery,^ 
 separated only by the bicipital fascia; and 
 formerly, when venesection was frequently 
 practised, arterio-venous aneurism was no 
 uncommon result of this practice. Another 
 disadvantage is, that the median basilic is 
 crossed by some of the branches of the internal 
 cutaneous nerve, and these may be divided 
 in the operation, giving rise to " traumatic 
 neuralgia of extreme intensity" (Tillaux). 
 
 The Basilic Vein (v. basilica) (Figs» 
 460 and 462) is of considerable size and 
 is formed by the coalescence of the 
 common ulnar vein with the median 
 
 Cruveilhier says: "Numerous varieties are observed in the disposition of the veins of the elbow; some- 
 "Jnes the comrnon median vein is wanting; but in those cases its two branches are furnished by the radial vein, 
 and the cephalic is almost always in a rudimentary condition. In other cases only two veins are found at the 
 bend of the elbow, the radial and ulnar, which are continuous, without any demarcation, with the cephalic and 
 basihc."— Ed. of 15th Engli.sh edition. 
 
THE DEEP VEINS OF THE UPPER EXTREMITY 747 
 
 basilic. It passes upward along the inner side of the Biceps muscle and pierces 
 ihe deep fascia a little below the middle of the arm. The opening in the fascia 
 is known as the semilunar hiatus (hiatus semilunaris). The vein ascends in the 
 course of the brachial artery to the lower border of the tendons of the Latissimus 
 dorsi and Teres major muscles, and is continued onward as the axillary vein. 
 
 The Cephalic Vein (v. cephalica) (Fig. 459) is formed by the union of the 
 median cephalic and the radial veins. It courses along the outer border of the 
 Biceps muscle, lying in the same groove with the upper external cutaneous branch 
 of the musculo-spiral nerve, to the upper third of the arm; it then passes in the 
 interval between the Pectoralis major and Deltoid muscles, lying in the same 
 groove with the descending or humeral branch of the acromial-thoracic artery. 
 It pierces the costo-coracoid membrane, and, crossing the axillary artery, ter- 
 minates in the axillary vein just below the clavicle. This vein is occasionally 
 connected with the external jugular or subclavian by a branch which passes 
 from it upward in front of the clavicle. 
 
 The Deep Veins of the Upper Extremity (Fig. 460). 
 
 The deep veins of the upper extremity follow the course of the arteries, forming 
 their venae comites or companion veins. Usually there is one vein lying on each 
 side of the corresponding artery, and they are connected at intervals by short 
 transverse branches. 
 
 There are two digital veins accompanying each artery along the sides of the 
 fingers: these, uniting at their base, pass along the interosseous spaces in the 
 palm, and terminate in the two venai comites which accompany the superficial 
 palmar arch. Branches from these vessels on the radial side of the hand accom- 
 pany the superficialis volae, and on the ulnar side terminate in the deep ulnar 
 veins (Fig. 460) . The deep ulnar veins, as they pass in front of the wrist, com- 
 municate with the interosseous and superficial veins, and at the elbow unite with 
 the deep radial veins to form the vena comites of the brachial artery. The venae 
 comites of the brachial communicate by numerous transverse branches, which 
 cross over or under the artery. 
 
 The Interosseous Veins (Fig. 460) accompany the anterior and posterior 
 interosseous arteries. The anterior interosseous veins commence in front of the 
 wrist, where they communicate with the deep radial and ulnar veins; at the upper 
 part of the forearm they receive the posterior interosseous veins, and terminate in 
 the vense comites of the ulnar artery. 
 
 The Deep Pahnar Veins accompany the deep palmar arch, being formed by 
 tributaries which accompany the ramifications of that vessel. At the wrist they 
 receive a dorsal and a palmar tributary from the thumb. The deep palmar veins 
 communicate with the deep ulnar veins at the inner side of the hand, and on the 
 outer side terminate in the deep radial veins (Fig. 460), which are the vense 
 comites of the radial artery. Accompanying the radial artery the deep radial 
 veins terminate in the vena? comites of the brachial artery. 
 
 The Brachial Veins (w. brachiales) (Fig. 460) are placed one on each side of 
 the brachial artery, receiving tributaries corresponding with the branches given off 
 from that vessel; at the lower margin of the Subscapularis muscle they join the 
 axillary vein. 
 
 These deep veins have numerous anastomoses, not only with each other, but 
 also with the superficial veins. One of the brachial veins empties into the 
 axillary, the other, usually the smaller, generally unites with the basilic. 
 
 The Axillary Vein (v. axillaris) (Fig. 461) is of large size, and may be regarded 
 as the continuation upward of the basilic vein, or as formed by the fusion of a 
 brachial vein with the basilic vein. If the first view is accepted a brachial vein 
 is described as one of the tributaries of the axillary vein. The axillary vein com- 
 
748 
 
 THE BLOOD-VASGULAB SYSTEM 
 
 mences at the lower border of the tendons of the Teres major and I^atissimus dorsi 
 muscles, increases in size as it ascends, by receiving tributaries corresponding with 
 the branches of the axillary artery, and terminates immediately beneath the clavicle 
 at the outer border of the first rib, where it becomes the subclavian vein. This 
 vessel is covered in front by the Pectoral muscles and costocoracoid membrane, 
 and Ues on the thoracic side of the axillary artery, which it partially overlaps. It 
 receives the brachial veins, the vense comites of the axillary artery except the cir- 
 cumflex veins; and near its termination the cephalic vein. This vein is provided 
 with a pair of valves opposite the lower border of the Subscapularis muscle; valves 
 are also found at the termination of the cephalic and subscapular veins. The 
 circumflex veins end in the subscapular or one of the brachial veins. 
 
 The Long Thoracic Branch {v. thoracalis lateralis) (Fig. 462) receives the thoracico- 
 epigastric vein {v. thoracoepigastrica), which comes all the way from the superficial 
 epigastric or from the femoral vein. 
 
 The Costo-axillary Veins {w. costoaxillares) (Fig. 462) come from the first six 
 intercostal spaces and bring blood from the intercostal veins to the axillary. 
 
 INTEROSSEOUS 
 VEINS 
 
 ULNAR DEEP 
 VEINS 
 
 VEN>E COMITES 
 OF BRACHIAL 
 ARTERY 
 
 ANASTOMOSIS 
 OF RADIAL 
 AND ULNAR 
 
 RADIAL DEEP 
 VEINS 
 
 Fig. 460. — The deep veins of the upper extremity. (Bourgery.) 
 
 Surgical Anatomy. — There are several points of surgical interest in connection with the 
 axillary vein. Being more superficial, larger, and slightly overlapping the axillary artery, it is 
 more liable to be wounded in the operation of extirpation of the axillary glands, especially as 
 these glands, when diseased, are apt to become adherent to the vessel. When wounded there 
 is always danger of air being drawn into its interior, and death resulting. This is due not only 
 to the fact that it is near the thorax, and therefore liable to be influenced by the respiratory 
 movements, but also because it is adherent by its anterior surface to the costo-coracoid membrane, 
 and therefore if wounded is likely to remain patulous and favor the chance of air being sucked 
 in. This adhesion of the vein to the fascia prevents its collapsing, and therefore favors the 
 furious bleeding which takes place in these cases. 
 
THE DEEP VEINS OF THE UPPER EXTREMITY 
 
 749 
 
 To avoid wounding the axillary vein in the extirpation of glands from the axilla no undue 
 force should be used in isolating the glands. If the vein is found to be so embedded in the 
 malignant deposit that the latter cannot be removed without taking away a part of the vein, 
 this must be done, the vessel having been first ligated above and below. 
 
 AXILLARY 
 ARTERY 
 MUSCULO- 
 CUTANEUS NERVC 
 MEDIAN NERVE 
 
 LONG THORACIC 
 
 Fig. 461. — The veins of the right axilla, viewed from in front. (Spalteholz.) 
 
 PECTORALIS 
 
 MAJOR 
 
 MUSCLE 
 
 SUBCLAVIUS 
 MUSCLE 
 
 The Subclavian Vein {v. suhdavia) (Figs. 421 and 446), the continuation of the 
 axillary, extends from the outer border of the first rib to the inner end of the clavicle, 
 where it unites with the internal jugular to form the. innominate vein. It is in 
 relation, in jront, with the clavicle and Subclavius muscle; behind and above, with 
 the subclavian artery, from which it 
 is separated internally by the Scal- 
 enus anticus muscle and phrenic 
 nerve. Below, it rests in a depres- 
 sioTi on the first rib and upon the 
 pleura. Above, it is covered by the 
 cervical fascia and integument. 
 
 An expansion of the aponeurosis 
 of the Subclavius muscle lies upon 
 the vein (Fig. 462). 
 
 The subclavian vein occasionally 
 rises in the neck to a level with the 
 third part of the subclavian artery, and in two instances has been seen passing 
 with this vessel behind the Scalenus anticus. This vessel is usually provided 
 with valves about an inch from its termination in the innominate, just external 
 to the entrance of the external jugular vein. 
 
 Tributaries.^ — It receives the external and anterior jugular veins and a small 
 branch from the cephalic, outside the Scalenus, and on the inner side of that 
 muscle the internal jugular vein. At the angle of junction with the internal 
 
 Fig. 462. — The aponeurotic expansion of the Subclavius 
 muscle over the subclavian vein. (Poirier and Charpy.) 
 
750 
 
 THE BLOOD -VASCULAB SYSTEM 
 
 jugular the left subclavian vein receives the thoracic duct (Fig. 463), while the 
 right subclavian vein receives the right lymphatic duct. 
 
 The Innominata or Brachio-cephalic Veins {w. anonymcB) (Fig. 464) are 
 two large trunks, placed one on each side of the root of the neck, and formed by 
 the union of the internal jugular and subclavian veins of the corresponding side. 
 
 The Right Innominate Vein (v. anonyma dextra) is a short vessel, an inch 
 in length, which commences at the inner end of the clavicle, and, passing almost 
 vertically downward, joins with the left innominate vein just below the cartilage 
 of the first rib, close to the right border of the sternum, to form the superior vena 
 cava. It lies superficial and external to the innominate artery; on its right side 
 is the phrenic nerve, and the pleura is here interposed between it and the apex of 
 the lung. This vein, at the angle of junction of the internal jugular with the sub- 
 clavian, receives the right vertebral vein, and, lower down, the right internal 
 mammary, right inferior thyroid, and sometimes the right thyroidea ima and the 
 right superior intercostal veins. 
 
 The Left Innominate Vein {v. anonyma sinistra), about two and a half 
 inches in length, and larger than the right, passes from left to right across the 
 upper and front part of the chest, at the same time inclining downward, and unites 
 
 LONGUS COLLI MUSCLE 
 
 COMMON CAROTrO 
 
 ARTERY 
 
 LEFT PNEUMOGASTRIC 
 
 NERVE 
 
 VERTEBRAL ARTERY 
 
 VERTEBRAL VEIN 
 
 THORACIC DUCT 
 
 INTERNAL JUGULAR 
 
 VEIN 
 
 EXTERNAL JUGULAR 
 
 VEIN 
 
 ANTERIOR JUGULAR 
 
 VEIN 
 
 SUBCLAVIAN 
 
 VEIN 
 
 Fig. 463. — The bend of the thoracic duct at its termination in the subclavian vein. (Poirier and Charpy.) 
 
 with the right innominate vein to form the superior vena cava. It is in relation, 
 in jront, with the first piece of the sternum, from which it is separated by the 
 Sterno-hyoid and Sterno-thyroid muscles, the thymus gland or its remains, and some 
 loose areolar tissue. Behind, it lies across the roots of the three large arteries 
 arising from the arch of the aorta. This vessel is joined by the left vertebral, 
 left internal mammary, left inferior thyroid, left thyroidea ima, and the left 
 superior intercostal veins, and occasionally some thymic and pericardiac veins, 
 and the right thyroidea ima. There are no valves in the innominate veins. 
 
 Peculiarities. — Sometimes the innominate veins open separately into the right auricle; in such 
 cases the right vein takes the ordinary course of the superior vena cava; but the left vein — the left 
 superior vena cava, as it is termed — after communicating by a small branch with the right one, 
 passes in front of the root of the left lung, and, turning to the back of the heart, receives the 
 cardiac veins, and terminates in the back of the right auricle. This occasional condition in the 
 adult is due to the persistence of the early foetal condition, and is the normal state of things in 
 birds and some mammalia. 
 
 The Internal Mammary Vein {v. mammaria interna) corresponds to the internal 
 mammary artery, follows the course of that vessel, and receives branches corre- 
 sponding with those derived from it. There are two internal mammary veins in the 
 region of the Triangularis sterni muscle, but above this point the vein is single. The 
 double vein is formed by the union of the vense comites of the superior epigastric 
 
THE DEEP VEINS OF THE UPPER EXTREMITY 
 
 751 
 
 Superior thyroid. 
 
 Middle thyroid. 
 
 — External jugular. 
 
 artery (vv. epigastricoe superiores) and the venae comites of the musculo-phrenic 
 
 artery (vv. musculophrenicce) . It receives the twelve anterior intercostal veins from 
 
 the upper six intercostal spaces of the corresponding side — six anterior perforating 
 
 veins {rami per] or antes) — 
 
 veins from the surface of the i^.^^Antertor jugxdar. 
 
 sternum {rami sternales) — 
 
 muscular veins, and vessels 
 
 from the mediastinum and 
 
 pleura. The two veins of 
 
 each side unite into a single 
 
 trunk, at the upper margin 
 
 of the triangularis sterni 
 
 muscle, which terminates in 
 
 the innominate vein. 
 
 The Vertebral Vein (see 
 p. 732). 
 
 Thelnferior Thyroid Veins 
 {vv. thyreoideoe inferiores) 
 (Fig. 464), two, frequently 
 three or four, in number, 
 arise in the venous plexus 
 on the thyroid body {plexus 
 ihyreoideus impar), commu- 
 nicating with the middle 
 and superior thyroid veins. 
 (See Kocher's views, pages 
 731 and 732.) Kocher states 
 that two thyroidea ima veins 
 are present, and that inferior 
 thyroid veins may also be 
 present. The veins from the 
 lower portion of the gland 
 form a plexus in front of the 
 trachea, behind the Sterno- 
 thyroid muscles. From this 
 plexus a left vein descends 
 and joins the left innomi- 
 nate trunk, and a right vein 
 passes obliquely downward 
 and outward across the in- 
 nominate artery to open into 
 the right innominate vein, 
 just at its junction with the 
 superior vena cava. The thy- 
 roidea ima vein {v. thyreoidca 
 ima) passes downward in 
 front of the trachea and ter- 
 minates in the left innominate 
 vein. These veins receive 
 tributaries from the tracheal 
 y%v[iz{vv.tracheales),irou\ the 
 oesophageal veins {vv. cesopha- 
 c)e(jc), from the inferior laryn- 
 geal y6ili(v .larunaea inferior) ■^'"' ^^^' — '^^^ vense cavae and azygos veins, with their formative 
 
752 THE BLOOD -VASCULAR SYSTEM 
 
 The Intercostal Veins {w. intercostales) are divided into anterior and posterior 
 intercostals. 
 
 The Anterior Intercostal Veins are tributaries of the internal mammary or the 
 musculo-phrenic veins (p. 731). 
 
 The Posterior Intercostal Veins (Fig. 464) number eleven on each side, there 
 being one vein in each intercostal space. Each vein lies in the groove at the 
 lower margin of the rib above the corresponding intercostal artery. On the right 
 side the first posterior intercostal vein crosses the neck of the first rib anteriorly 
 and opens into the vertebral vein or the innominate vein. The first posterior 
 intercostal of the left side follows a like course, and empties into the vertebral 
 or innominate vein. The posterior intercostals of the right side, from the fifth 
 to the eleventh, inclusive, open individually into the vena azygos major. The 
 left upper azygos vein receives the fifth, sixth, seventh, and eighth posterior 
 intercostals of the left side. The left lower azygos vein receives the ninth, tenth, 
 and eleventh left posterior intercostals. 
 
 The Right Superior Intercostal Vein {v. intercostalis suprema dextra) is formed 
 by the vmion of the second, third, and fourth right posterior intercostals. It 
 passes downward and inward and opens into the vena azygos major. 
 
 The Left Superior Intercostal Vein {v. intercostalis suprema sinister) runs across 
 the transverse aorta and opens into the left innominate vein. It usually receives 
 the left bronchial and left superior phrenic vein, and communicates below with 
 the vena azygos minor superior. Each posterior intercostal vein obtains branches 
 from the ribs and muscles and also a dorsal branch, which receives blood from the 
 muscles of the back, from in front of the vertebral bodies, from back of the ver- 
 tebral arches, and from the spinal canal by way of a vein which passes through 
 the intervertebral foramen. 
 
 The Superior Vena Cava (v. cava superior) (Fig. 464) receives the blood 
 which is conveyed to the heart from the whole of the upper half of the body. 
 It is a short trunk, varying from two inches and a half to three inches in length, 
 formed by the junction of the two innominate veins. It commences immediately 
 below the cartilage of the first rib close to the sternum on the right side, and, 
 descending vertically, enters the pericardium about an inch and a half above the 
 heart, and terminates in the upper part of the right auricle opposite the upper 
 border of the third right costal cartilage. In its course it describes a slight curve, 
 the convexity of which is turned to the right side. 
 
 Relations. — In front, with the pericardium and process of cervical fascia which 
 is continuous with it: this separates it from the thymus gland and from the ster- 
 num; behind, with the root of the right lung; on its right side, with the phrenic 
 nerve and right pleura; on its left side, with the commencement of the innominate 
 artery and ascending part of the aorta. The portion contained within tlie peri- 
 cardium is covered by the serous layer of that membrane in its anterior three- 
 fourths. It receives the vena azygos major just before it enters the pericardium, 
 and several small veins from the pericardium and parts in the mediastinum. The 
 superior vena cava has no valves. 
 
 The Azygos Veins connect together the superior and inferior venoe cavse, 
 taking the place of those vessels in that part of the chest occupied by the heart. 
 
 The Larger or Right Azygos Vein or the Vena Azygos Major (v. azygos) (Fig. 464) 
 commences opposite the first or second lumbar vertebra by a branch from the right 
 lumbar veins, called the right ascending lumbar vein (v. lumbalis ascendens dextra) ; 
 sometimes by a branch from the right renal vein or from the inferior vena cava. It 
 enters the thorax through the aortic opening in the Diaphragm, and passes along 
 the right side of the vertebral column to the fourth dorsal vertebra, where it 
 arches forward over the root of the right lung, and terminates in the superior vena 
 cava just before that vessel enters the pericardium. Whilst passing through the 
 
THE SPINAL VEINS 753 
 
 aortic opening of the Diaphragm it lies with the thoracic duct on the right side 
 of the aorta, and in the thorax it Hes upon the intercostal arteries on the right 
 side of the aorta and thoracic duct, and is partly covered by pleura. 
 
 Tributaries. — It receives the lower ten posterior intercostal veins of the right side, 
 the upper two or three of these opening first of all into the right superior intercostal 
 vein. It receives the azygos minor veins, several oesophageal, mediastinal, and 
 pericardial veins; near its termination, the right bronchial vein; and generally 
 the right superior intercostal vein. A few imperfect valves are found in this vein; 
 but its tributaries are provided with complete valves. 
 
 The intercostal veins on the left side, below the three upper intercostal spaces, 
 usually form two trunks, named the left lower and the left upper azygos veins. 
 
 The Left Lower or Smaller Azygos Vein or the Vena Azygos Minor {v. hemiazygos) 
 (Fig. 464) commences in the lumbar region by a branch from one of the lumbar 
 veins, ascending lumbar (v. lumhalis ascendens), or from the left renal. It passes 
 into the thorax through the left crus of the Diaphragm, and, descending on the 
 left side of the spine as high as the ninth dorsal vertebra, passes across the 
 column, behind the aorta and thoracic duct, to terminate in the right azygos vein. 
 It receives the four or five lower intercostal veins of the left side, and some 
 oesophageal and mediastinal veins. 
 
 The Left Upper Azygos Vein {v. hemiazygos accessoria) varies inversely with the 
 size of the left superior intercostal. It receives veins from the intercostal spaces 
 between the left superior intercostal vein and highest tributary of the left lower 
 azygos. They are usually three or four in number, usually the fourth, fifth, sixth, 
 and seventh left posterior intercostal veins. They join to form a trunk which ends 
 in the right azygos vein or in the left lower azygos. It sometimes receives the left 
 bronchial vein. When this vein is small or altogether wanting, the left superior 
 intercostal vein will extend as low as the fifth or sixth intercostal space. 
 
 Surgical Anatomy. — In obstruction of the inferior vena cava the azygos veins are one of the 
 principal means l)y which the venous circulation is carried on, connecting as they do the superior 
 and inferior venae cavse, and communicating with the common iliac veins by the ascending lum- 
 bar veins, and with many of the tributaries of the inferior vena cava. 
 
 The Bronchial Veins (vv. hronchiales) return the blood from the substance of 
 the lungs, except from the smaller bronchial tubes and alveola. The blood from 
 them is received by the pulmonary veins. The bronchial vein of the right side 
 opens into the vena azygos major near its termination. The bronchial vein of 
 the left side opens into the left superior intercostal vein or the left upper azygos 
 vein. The bronchial veins are joined by veins from the trachea and medias- 
 tinum. 
 
 The Spinal Veins. 
 
 The numerous venous plexuses placed upon and within the spine may be 
 arranged into four sets: 
 
 1. Those placed on the exterior of the spinal column, the dorsi-spinal veins. 
 
 2. Those situated in the interior of the spinal canal, between the vertebrae and 
 the theca vertebralis, meningo-rachidian veins. 
 
 3. The veins of the bodies of the vertebra% venae basis vertebrarum. 
 
 4. The veins of the spinal cord, medulli-spinal veins. 
 
 1. The Dorsi-spinal Veins {plexus vcnosi vertebrates externi) commence by 
 small branches which receive their blood from the integument of the back of the 
 spine and from the muscles in the vertebral grooves. They constitute two plexuses : 
 an anterior plexus (plexus venosi verfebrales anteriores) upon the vertebral bodies 
 and a posterior plexus (plexus venosi vertehrales posteriores) , which surrounds the 
 spinous processes, the laminae, and the transverse and articular processes of 
 
 48 
 
754 
 
 THE BLOOD VASCULAR SYSTEM 
 
 all the vertebrse. At the bases of the transverse processes they communicate, by 
 means of ascending and descending branches, with the veins surrounding the 
 contiguous vertebrae, and they join v^ith the veins in the spinal canal by branches 
 which perforate the ligamenta subflava. Other branches pass obliquely forward, 
 between the transverse processes, and communicate with the intraspinal veins 
 through the intervertebral foramina {vv. intervertehrales). The dorsi-spinal veins 
 terminate by joining the vertebral veins in the neck, the intercostal veins in the 
 thorax, and the lumbar and sacral veins in the loins and pelvis. 
 
 The dorsi-spinal veins. 
 
 Fig. 465. — Transverse section of a dorsal vertebra, showing the spinal veins. 
 
 2. The MeningO-rachidian Veins (plexus venosi vertebrates interni). — The 
 principal veins contained in the spinal canal are situated between the theca verte- 
 bralis and the vertebrae. They consist of two longitudinal plexuses, one of which 
 runs along the posterior surface of the bodies of the vertebra;, anterior longitudinal 
 spinal veins. The other plexus, posterior longitudinal spinal veins, is placed on the 
 inner or anterior surface of the laminae of the vertebrae. 
 
 Fig. 466. — Vertical section of two dorsal vertebrae, showing the spinal veins. 
 
 The Anterior Longitudinal Spinal Veins (sinus vertehrales longitudmales) consist 
 of two large, tortuous veins which extend along the whole length of the vertebral 
 column, from the foramen magnum, where they communicate by a venous ring 
 around that opening, to the base of the coccyx, being placed one on each side of 
 the posterior surface of the bodies of the vertebrae along the margin of the posterior 
 common ligament. These veins communicate together opposite each vertebra by 
 
VEINS OF LOWER EXTREMITY, ABDOMEN AND PELVIS 755 
 
 transverse trunks which pass beneath the Hgament. Each transverse trunk 
 receives the large vena basis vertebrae {v. hasivertehralis) from the interior of the 
 body of the vertebra. The anterior longitudinal spinal veins are least developed 
 in the cervical and sacral regions. They are not of uniform size throughout, 
 being alternately enlarged and constricted. At the intervertebral foramina they 
 communicate with the dorsi-spinal veins, and with the vertebral veins in the neck, 
 with the intercostal veins in the dorsal region, and with the lumbar and sacral 
 veins in the corresponding regions. 
 
 The Posterior Longitudinal Spinal Veins, smaller than the anterior, are situated 
 one on each side, between the inner surface of the laminae and the theca verte- 
 bralis. They communicate (like the anterior) opposite each vertebra by trans- 
 verse trunks, and with the anterior longitudinal veins by lateral transverse branches 
 which pass from behind forward. The posterior longitudinal veins, by branches 
 which perforate the ligamenta subflava, join with the dorsi-spinal veins. From 
 them branches are given off which pass through the intervertebral foramina and 
 join the vertebral, intercostal, lumbar, and sacral veins. The anterior and pos- 
 terior longitudinal spinal veins join by numerous branches and really constitute 
 one plexus, the plexus venosi vertebrales interni. 
 
 The Intervertebral Veins {vv. intervertehrales) accompany the spinal nerves 
 in the intervertebral foramina, receive veins from the spinal cord, and join the 
 meningo-rachidian and the dorsi-spinal veins. 
 
 3. The Veins of the Bodies of the Vertebrae or the Venae Basis Vertebramm 
 {w. hasivertehrales) emerge from the foramen on the posterior surface of each 
 vertebra and join the transverse trunk connecting the anterior longitudinal spinal 
 veins. They are contained in large, tortuous channels in the substance of the 
 bones, similar in every respect to those found in the diploe of the cranial bones. 
 These canals lie parallel to the upper and lower surface of the bones. They com' 
 mence by small openings on the front and sides of the bodies of the vertebrae, 
 through which communicating branches from the veins external to the bone pass 
 into its substance, and converge to the principal canal, which is sometimes double 
 toward its posterior part. They open into the corresponding transverse branch unit- 
 ing the anterior longitudinal veins. They become greatly developed in advanced age. 
 
 4. The Veins of the Spinal Cord or the Medulli-spinal Veins {w. syinales) 
 emerge from the cord substance and enter the pia mater plexus. The pia mater 
 plexus is a minute, tortuous, venous plexus which covers the entire surface of the 
 cord, being situated between the pia mater and arachnoid, " In this plexus there 
 are six longitudinal channels — one antero-median, along the anterior fissure — 
 two antero-lateral, immediately behind the anterior nerve roots — two postero- 
 lateral, immediately behind the posterior nerve roots — and one postero-median, 
 over the postero-septum."^ These vessels are largest in the lumbar region. 
 Near the base of the skull they unite and form two or three small trunks, which 
 communicate with the vertebral veins, and terminate in the inferior cerebellar 
 veins or in the inferior petrosal sinuses. Each of the spinal nerves is accompanied 
 by a branch as far as the intervertebral foramina, where it joins the other veins 
 from the spinal canal. 
 
 There are no valves in the spinal veins, 
 
 VEINS OF THE LOWER EXTREMITY, ABDOMEN, AND PELVIS 
 
 (Figs. 467, 468). 
 
 The Veins of the I>ower Extremity are subdivided, like those of the upper, 
 into two sets, superficial and deep, the superficial veins being placed beneath the 
 
 ' D. J. Cunningham. A Text-book of Anatomy. 
 
756 THE BLOOD -VASCULAR SYSTEM 
 
 integument, between the two layers of superficial fascia, the deep veins accom- 
 panying the arteries, and forming the venae comites of those vessels. Both sets 
 of veins are provided with valves, which are more numerous in the deep than in 
 the superficial set. These valves are also more numerous in the lower than in 
 the upper limb. 
 
 The Superficial Veins of the Lower Extremity. 
 
 The Superficial Veins of the Foot. — On the sole of the foot there is a sub- 
 cutaneous venous plexus {rete venosum plantare cutaneum), from which some 
 branches go to the deep veins, but most of the branches pass around the margins 
 to the dorsum of the foot. There is a transverse venous arch at the root of the 
 toes which receives plantar vessels from the toes and sends branches between the 
 toes (vv. intercapitulares) to the venous arch of the dorsum. On the dorsum of each 
 toe the veins gather into two vessels, known as the dorsal digital veins {vv. digitales 
 pedis dorsales). The dorsal digital veins from the opposed margins of two toes 
 unite to form a dorsal interdigital vein. There are four dorsal interdigital veins 
 {vv. digitales communes pedis), and they pass into the venous arch of the dorsum. 
 The dorsal digital vein, from the inner surface of the great toe, passes directly 
 into the internal saphenous vein, and the dorsal digital vein, from the outer 
 surface of the little toe, passes directly into the external saphenous vein. 
 
 On the dorsum of the foot is a venous arch {arcus venosus dorsalis pedis 
 [cutaneus]), situated in the superficial structures over the anterior extremities of 
 the metatarsal bones. It has its convexity directed forward, and receives digital 
 tributaries from the upper surface of the toes; at its concavity it is joined by 
 numerous small veins which form a plexus on the dorsum of the foot {rete 
 venosum dorsale pedis cutaneum). The arch terminates internally in the long 
 saphenous, externally in the short saphenous vein. 
 
 The chief superficial veins of the lower extremity are the internal or long saphenous 
 and the external or short saphenous. 
 
 The Internal or Long Saphenous Vein {v. saphena magna) (Figs. 467 and 470) 
 commences at the inner side of the arch on the dorsum of the foot ; it ascends in front 
 of the inner malleolus and along the inner side of the leg, behind the inner margin 
 of the tibia, accompanied by the internal saphenous nerve. At the knee it passes 
 backward behind the inner condyle of the femur, ascends along the inside of the 
 thigh, and, passing through the saphenous opening in the fascia lata, terminates 
 in the femoral vein about an inch and a half below Poupart's ligament. This vein 
 receives in its course cutaneous tributaries from the leg and thigh, and at the 
 saphenous opening receives the superficial epigastric, superficial circumflex iliac, 
 and external pudic veins. The veins from the inner and back part of the thigh 
 frequently unite to form a large vessel, which enters the main trunk near the 
 saphenous opening; and sometimes those on the outer side of the thigh join to form 
 another large vessel; so that occasionally three large veins are seen converging from 
 different parts of the thigh toward the saphenous opening. The internal saphenous 
 vein communicates in the foot with the internal plantar vein; in the leg, with the 
 posterior tibial veins by branches which perforate the tibial origin of the Soleus 
 muscle, and also with the anterior tibial veins; at the knee, with the articular 
 veins; in the thigh, with the femoral vein by one or more branches. The valves 
 in this vein vary from two to six in number; they are more numerous in the thigh 
 than in the leg. 
 
 The External or Short Saphenous Vein {v. saphena parva) (Fig. 468) com- 
 mences at the outer side of the arch on the dorsum of the foot ; it ascends behind the 
 outer malleolus, and along the outer border of the tendo Achillis, across which it 
 passes at an acute angle to reach the middle line of the posterior aspect of the leg. 
 
 I 
 
THE SUPERFICIAL VEINS OF THE LOWER EXTREMITY 757 
 
 Passing directly upward, it perforates the deep fascia in the lower part of the 
 popHteal space, and terminates in the popUteal vein, between the heads of the 
 
 vV 
 
 F^^: 
 
 m 
 
 I mh 
 
 Fig. 468. — External or short saphenous vein. 
 
 Gastrocnemius muscle/ It receives numerous large 
 tributaries from the back part of the leg, and com- 
 municates with the deep veins on the dorsum of the 
 foot and behind the outer malleolus. Before it per- 
 forates the deep fascia it gives off a communicating 
 branch, which passes upward and inward to join the 
 internal saphenous vein. This vein has a variable 
 number of valves, from three to nine (Gay), one of 
 which is always found near its termination in the 
 popliteal vein. The external saphenous nerve lies 
 close beside this vein. 
 
 Surgical Anatomy.— The saphenous veins are of consider- 
 ^ . able surgical importance, since a varicose condition of these 
 
 saphtn^ouTvei'n andTts branch'eT^ vessels is more frequently met with than of those in other parts 
 
 ' Mr. Gay calls attention to the fact that the external saphenous vein often (he says invariably) penetrates 
 the fascia at or about the point where the tendon of the Gastrocnemius commences, and runs below the fascia 
 in the rest of its course, or sometimes among the muscular fibres, to join the popliteal vein. (See Gay on Vari- 
 cose Disease of the Lower Extremities, p. 24, where there is also a careful and elaborate description of the 
 branches of the saphena veins.) — Ed. of 15th English edition. 
 
758 
 
 THE BLOOD -VASCULAB SYSTEM 
 
 of the body, except perhaps the spermatic and hemorrhoidal veins. The course of the internal 
 saphenous is in front of the tip of the inner malleolus, over the subcutaneous surface of the lower 
 end of the tibia, and then along the internal border of this bone to the back part of the internal 
 condyle of the femur, whence it follows the course of the Sartorius muscle, and is represented on 
 the surface by a line drawn from the posterior border of the Sartorius on a level with the internal 
 condyle to the saphenous opening. The external saphenous lies behind the external malleolus, 
 and from this follows the middle line of the calf to just below the ham. It is not generally so 
 apparent beneath the skin as the internal saphenous. Both these veins in the leg are accom- 
 panied by nerves, the internal saphenous being joined by its companion nerve just below the 
 level of the knee-joint. No doubt much of the pain of varicose veins in the leg is due to this 
 fact. 
 
 The Deep Veins of the Lower Extremity. 
 
 The deep veins of the lower extremity accompany the arteries and their branches 
 and are called the venae comites of those vessels. The vense comites in the lower 
 
 extremity pass into one trunk, the popliteal vein, 
 whereas in the upper extremity the vena? comites con- 
 tinue with the artery to the axilla. 
 
 The Deep Veins of the Foot.— The plantar digital 
 veins {vv. digitales 'plantar es) form the plantar metatarsal 
 veins {vv. metatarsew plantares), which communicate 
 with the veins of the dorsum of the foot by perfor- 
 ating veins and also communicate with the deep venous 
 arch of the sole of the foot (arcus venosus plantaris pro- 
 fundus). The plantar arch gives off lateral or external 
 plantar veins, which unite with median or internal plantar 
 veins to form the posterior tibial veins. On the dorsum 
 of the foot the deep veins begin as the dorsal metatarsal 
 veins (vv. metatarsece dor sales pedis), which form the 
 vense comites of the dorsalis pedis artery. 
 
 The Posterior Tibial Veins {w. tihiales posteriores) 
 accompany the posterior tibial artery and are joined 
 by the peroneal veins. 
 
 The Anterior Tibial Veins (vv. tihiales anteriores) 
 are formed by a continuation upward of the vense 
 comites of the dorsalis pedis artery. They pass be- 
 tween the tibia and fibula, through the large oval aper- 
 ture above the interosseous membrane, and form, by 
 their junction with the posterior tibial, the popliteal 
 vein. 
 
 The valves in the deep veins are very numerous. 
 The Popliteal Vein (v. poplitea) (Fig. 469) is formed 
 by the junction of the anterior and posterior tibial 
 veins; it ascends through the popliteal space to the 
 aperture in the Adductor magnus, where it becomes the femoral vein. In the 
 lower part of its course it is placed internal to the artery; between the heads of 
 the Gastrocnemius it is superficial to that vessel; but above the knee-joint it is 
 close to the outer side of the artery. It receives the sural veins from the Gastroc- 
 nemius muscle, the articular veins, and the external saphenous vein. The valves 
 in this vein are usually four in number. 
 
 The Femoral Vein (v. femoralis) (Figs. 470 and 471) accompanies the femoral 
 artery through the upper two-thirds of the thigh. In the lower part of its course 
 it lies external to the artery; higher up it is behind it; and at Poupart's ligament 
 it lies to its inner side and on the same plane. It receives numerous muscular 
 tributaries, and about an inch and a half below Poupart's ligament it is joined by 
 
 Fig. 469.— The popliteal vein. 
 (Poirier and Charpy.) 
 
THE DEEP VEINS OF THE LOWER EXTREMITY 
 
 759 
 
 the profunda femoris {v. profunda femoris); near its termination it is joined by 
 the internal saphenous vein. The valves in this vein are four or five in number. 
 The External Iliac Vein (v. iliaca externa) (Figs. 464, 471, and 473) commences 
 at the termination of the femoral, beneath the crural arch, and, passing upward 
 along the brim of the pelvis, terminates opposite the sacro-iliac synchondrosis by 
 uniting with the internal iliac to form the common iliac vein. On the right side it 
 lies at first along the inner side of the external iliac artery, but as it passes upward 
 gradually inclines behind it. On the left side it lies altogether on the inner side 
 of the artery. It receives, immediately above Poupart's ligament, the deep epi- 
 
 UMBILICUS 
 
 SUPERFICIAL 
 EPIGASTRIC 
 
 SUPERFICIAL 
 
 INTERNAL 
 
 CIRCUMFLEX 
 
 SUPERFICIAL 
 
 EXTERNAL 
 
 CIRCUMFLEX 
 
 Fig. 470. — The femoral vein and its tributaries. (Poirier and Charpy.) 
 
 gastric and deep circumflex iliac veins and a small pubic vein, corresponding to 
 the pubic branch of the obturator artery. According to Friedreich, it frequently 
 contains one and sometimes two valves. 
 
 The Deep Epigastric Vein (v. epigastrica inferior) (Fig. 471). — Two veins 
 accompany the deep epigastric artery; they usually unite into a single trunk 
 before their termination in the external iliac vein. 
 
 The Deep Circumflex Hiac Vein (v. circumflexa ilium profunda) (Fig. 471). — 
 Two veins accompany the deep circumflex iliac artery. These unite into a single 
 trunk which crosses the external iliac artery just above Poupart's ligament and 
 terminates in the external iliac vein. 
 
760 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 The Hypogastric or Internal Iliac Vein {v. iliaca interna or v. hypogastrica) 
 (Figs. 464, 471, and 473) is formed by the veins corresponding to all the branches 
 of the internal iliac artery except the umbilical branch. It receives the blood 
 from the exterior of the pelvis by the gluteal, sciatic, internal pudic, and obturator 
 veins, and from the organs in the cavity of the pelvis by the middle hemor- 
 rhoidal veins, the superior vesical plexus and the prostatico-vesical plexus in the 
 male, and the superior vesical, inferior vesical, uterine and vaginal plexuses in 
 the female. The vessels forming these plexuses are remarkable for their large size, 
 their frequent anastomoses, and the number of valves which they contain. The 
 internal iliac vein lies at first on the inner side, and then behind the internal iliac 
 artery, and terminates opposite the sacro-iliac articulation by uniting with the 
 external iliac to form the common iliac vein. This vessel has no valves. 
 
 The Internal Pudic Veins (vv. pudendce intern(F)(Fig. 471) have the same course as 
 the internal pudic artery. They receive tributaries corresponding to the branches 
 of the artery, except the tributary corresponding to the dorsal artery of the 
 penis ; that is, the deep dorsal vein of the penis, which opens into the prostatico- 
 vesical plexus. 
 
 CIRCUMFLEX 
 ILIAC 
 
 DEEP 
 EPIGASTRIC 
 
 LATERAL 
 SACRAL 
 
 MID 
 SACRAL 
 
 Fig. 471. — The iliac veins. (Poirier and Charpy.) 
 
 The Inferior or External Haemorrhoidal Veins (Figs. 472 and 473) collect blood 
 from the anus. They pass outward over the External sphincter muscle, unite with 
 numerous subcutaneous veins, and form larger vessels which join the internal 
 pudic veins. 
 
 The Middle Haemorrhoidal Veins (Figs. 472 and 473) help to form the hemor- 
 rhoidal plexus, perforate the rectal wall, and empty into the internal iliac vein. 
 These veins, by their anastomoses in the hemorrhoidal plexus, establish a 
 communication between the portal and systemic venous systems. 
 
 The Lateral Sacral Veins (vv. sacrales latcrales) (Fig. 471) accompany the lateral 
 sacral arteries and terminate in the internal iliac vein. 
 
THE DEEP VEINS OF THE LOWER EXTREMITY 
 
 761 
 
 Surgical Anatomy. — The veins of the hemorrhoidal plexus are apt to become dilated and 
 varicose, and form piles, hemorrhoids. This is due to several anatomical reasons: the vessels are 
 contained in very loose, or connective tissue, so that they obtain less support from surrounding 
 structures than most other veins, and are less capable of resisting increased blood pressure: 
 the condition is favored by gravitation, being influenced by the erect posture, either sitting or 
 standing, and by the fact that the superior hemorrhoidal and portal veins have no valves. The 
 veins pass through muscular tissue and are liable to be compressed by its contraction, especially 
 during the act of defecation, and they are affected by every form of portal obstruction. 
 
 The Obturator Vein {v. ohturatorke) (Figs, 471 and 473) follows the course of 
 the obturator artery, lying below the artery as it passes over the side of the 
 pelvis; this vein empties into the front part of the internal iliac vein. 
 
 The Sciatic Veins are two in number; they accompany the sciatic artery in 
 the upper part of the back of the thigh, and just before their termination in the 
 internal iliac the two veins unite. 
 
 The Gluteal Veins {w. glutea) are usually two in number, and return to the 
 internal iliac vein the blood that has been distributed by the gluteal artery and 
 its branches. 
 
 MIDDLE 
 HCMORRHOiDAL' 
 
 Fig. 472. — Scheme of the anastomosis of the veins of the rectum. (Poirier and Charpy.) 
 
 The Superior Vesical Plexus (Fig. 473) is placed upon the fundus and 
 lateral aspects of the bladder on the external aspect of the muscular coat. It 
 receives vessels from the mucous membrane and from the muscular walls. It 
 empties into the internal pudic vein: in the male it communicates with the 
 prostatico-vesical plexus, and in the female with the inferior vesical plexus. 
 
 The Prostatic or the Prostatico-vesical Plexus (Fig. 473) surrounds the 
 prostate gland and the neck of the bladder. It is contained between the recto- 
 vesical fascia which surrounds the base and sides of the gland and the true capsule 
 of the glaijd. It communicates with the superior vesical plexus behind and 
 above, and receives the deep dorsal vein of the penis, which enters the pelvis 
 between the subpubic and triangular ligaments. This plexus receives veins from 
 the seminal vesicles and vasa deferentia. On each side one or more vessels pass 
 
762 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 from the prostatico-vesical plexus to the internal iliac vein. The veins composing 
 the prostatic plexus are very liable to become varicose, and often contain hard, 
 earthy concretions called phleboliths. 
 
 The Inferior Vesical Plexus exists only in the female, and corresponds to the 
 prostatico-vesical plexus in the male, and surrounds the neck of the bladder and 
 the upper portion of the urethra. It receives the dorsal vein of the clitoris and 
 sends efferents to the internal iliac vein. 
 
 THIRD LUMBAR 
 
 SUPERIOR 
 HEMORRHOIDAL 
 
 DEEP 
 
 CIRCUMFLEX 
 
 ILIAC 
 
 OBTURATOR 
 
 PROSTATIC 
 PLEXUS 
 
 HEMORRHOIDAL 
 PLEXUS 
 
 MIDDLE 
 HEMORRHOIDAL 
 
 INFERIOR 
 HEMORRHOIDAL 
 
 DORSAL 
 OF PEN 
 
 VESICAL PLEXUS INTERNAL PUDIC 
 
 Fig. 473. — The veins of the male pelvis, right half, viewed from the left. The psoas mu-scle has been removed 
 and the rectum drawn down somewhat to the side. (Spalteholz.) 
 
 Surgical Anatomy. — The prostatico-vesical plexus is wounded in the lateral operation of 
 lithotomy, and it is through it that septic matter finds its way into the general circulation after 
 this operation. In enucleating the prostate the gland is shelled out from its capsule of recto- 
 vesical fascia. The veins of the plexus remain attached to the sheath. 
 
 The Dorsal Veins of the Penis.— The Superficial Dorsal Vein of the Penis (Fig. 
 474) receives blood from the prepuce and runs backward beneath the skin, and 
 divides into two branches which terminate in the superficial external pudic vein. 
 
 The Deep Dorsal Vein of the Penis {v. dorsalis 'penis) (Figs. 473 and 474) is a vessel 
 of large size which returns the blood from the body of that organ. At first it con- 
 
THE DEEP VEINS OF THE LOWER EXTREMITY 
 
 763 
 
 SUPERFICIAL DOR- 
 SAL VEIN 
 DORSAL ARTERY i .DEEP DORSAL VEIN 
 
 CORPUS cavernosum', ■ 
 
 ^i ,__ 
 
 AREOLAR 
 TISSUE 
 
 CAVERNOUS, 
 ARTERY 
 
 sists of two branches, which are contained in the groove on the dorsum of the penis, 
 and it receives numerous superficial veins and veins from the glans penis and the 
 corpus spongiosum. These vessels unite into a single trunk, which passes between 
 the two parts of the suspensory ligament of the penis, and through an aperture 
 between the subpubic ligament and 
 the apex of the triangular ligament, 
 and divides into two branches, which 
 enter the prostatico-vesical plexus. 
 The dorsal vein of the clitoris corre- 
 sponds in woman to the dorsal vein 
 of the penis in man, and runs into 
 the inferior vesical plexus. 
 
 The Vaginal Plexuses and Veins 
 (Fig. 475). — The vaginal plexuses are 
 placed at the sides of the vagina, being 
 especially developed at the orifice of 
 the canal. They receive vessels from 
 the vaginal walls. The plexuses 
 communicate with the uterine plexus above, with the bulbar veins 'below, with 
 the inferior vesical plexus in front and with the hemorrhoidal plexus behind. 
 From the upper part of each vaginal plexus comes a vaginal vein which passes 
 to the internal iliac. 
 
 The Uterine Plexuses (Fig. 475) are situated along the sides and superior angles 
 of the uterus, between the layers of the broad ligament. They receive the veins 
 from the uterus, which veins are without valves. During pregnancy these veins 
 
 URETHRA 
 
 BULBO-CAVERNOUS ARTERY/ 
 
 — ANTERIOR BRANCH '\ 
 
 CORPUS 
 SPONGIOSUM 
 
 Fig. 474. — The penis in transverse section, showing the 
 blood-vessels. (Testut.) 
 
 FALLOPIAN 
 
 UTERINE 
 
 VEINS 
 
 VAGINAL VENOUS PLEXUS 
 
 UTERINE ARTERY 
 
 SUPERIOR VAGINAL 
 ARTERIES 
 
 OS UTERI VAGINA CUT OPEN BEHIND 
 
 Fig. 475. — Vessels of the uterus and its appendages, rear view. (Testut.) 
 
 become large venous canals known as the uterine sinuses, and bring blood from the 
 substance of the placenta. These veins join the ovarian above and the vaginal 
 below, and anastomose with each other. They are not tortuous like the artery. 
 
 The Uterine Veins {vv. uterinoe) (Fig. 475) arise from the lower part of the 
 plexus, and there are usually two veins on each side and they are without valves. 
 These veins for the first portion of their course are placsd in the base and inner 
 portion of the broad ligament; they then pass back with the uterine artery in a 
 peritoneal fold between the back of the broad ligament and the recto-uterine 
 fold (Cunningham) ; they then pass upward and enter the internal iliac vein. 
 
764 '^'HE BLOOD -VASCULAR SYSTEM 
 
 The Common Iliac Vein {v. iliaca communis) (Figs. 464, 471, and 473) on 
 each side is formed by the union of the external and internal iliac veins in 
 front of the sacro-iliac articulation : passing obliquely upward toward the right 
 side, each vein terminates upon the intervertebral substance between the fourth 
 and fifth lumbar vertebrae, where the veins of the two sides unite at an acute 
 angle to form the inferior vena cava. The right common iliac {v. iliaca communis 
 dextra) is shorter than the left, nearly vertical in its direction, and ascends behind 
 and then to the outer side of its corresponding artery. The left common iliac 
 {v. iliaca communis sinistra), longer and more obUque in its course, is at first 
 situated on the inner side of the corresponding artery, and then behind the right 
 common iliac. Each common iliac receives the ilio-lumbar, and sometimes the 
 lateral sacral, veins. The left receives, in addition, the middle sacral vein. No 
 valves are found in these veins. 
 
 The Middle Sacral Veins (Figs. 471 and 472) accompany the corresponding 
 artery along the front of the sacrum, and join to form a single vein (v. sacralis 
 media), which terminates in the left common iliac vein; occasionally in the angle 
 of junction of the two iliac veins. The middle sacral veins communicate with 
 the inferior hemorrhoidal. 
 
 The Ilio-lumbar Veins (t'v. iliolumhales) receive branches from the iliac fossae, 
 spinal muscles, and spinal canal. One vein on each side runs with the artery, 
 passes posterior to the psoas muscle, and joins the common iliac vein. 
 
 Peculiarities. — The left common iliac vein, instead of joining with the right in its usual 
 position, occasionally ascends on the left side of the aorta as high as the kidney, where, after 
 receiving the left renal vein, it crosses over the aorta, and then joins with the right vein to form 
 the vena cava. In these cases the two common iliacs are connected by a small communicating 
 branch at the spot where they are usually united.^ 
 
 The Ascending or Inferior Vena Cava {v. cava inferior) (Figs. 464 and 471) 
 returns to the heart the blood from all the parts below the Diaphragm. It is 
 formed by the junction of the two common iliac veins on the right side of the 
 intervertebral substance between the fourth and fifth lumbar vertebrae. It passes 
 upward along the front of the spine on the right side of the aorta, and, having reached 
 the under surface of the liver, is contained in a groove on its posterior surface. It 
 then perforates the central tendon of the Diaphragm, enters the pericardium, 
 where it is covered for a very short distance by the serous layer of the pericardium, 
 and terminates in the lower and back part of the right auricle. At its termination 
 in the auricle it is provided with a valve, the Eustachian valve (valvida v. cavas 
 [inferioris Eustachii]) , which is of large size during foetal life. 
 
 Relations. — In front, from below upward, with the mesentery, right spermatic 
 artery, transverse portion of the duodenum, the pancreas, portal vein, and the 
 posterior surface of the liver, which, in most cases, partly and occasionally com- 
 pletely surrounds it; behind, with the vertebral column, the right crus of the 
 Diaphragm, the right renal and lumbar arteries, and the right semilunar ganglion; 
 on the left side, with the aorta. 
 
 Peculiarities. In Position. — This vessel is sometimes placed on the left side of the aorta, 
 as high as the left renal veins, after receiving which it crosses over to its usual position on the 
 right side; or it may be placed akogether on the left side of the aorta, as far upward as its ter- 
 mination in the heart: in such cases the abdominal and thoracic viscera, together with the great 
 vessels, are all transposed. 
 
 Point of Termination. — Occasionally the inferior vena cava joins the right azygos vein, 
 which is then of large size. In such cases the superior cava receives the whole of the blood 
 from the body before transmitting it to the right auricle, except the blood from the hepatic veins, 
 which passes directly into the right auricle. 
 
 * See two cases which have been described by Mr. Walsham in the St. Bartholomew's Hospital Reports, 
 vols. xvi. and xvii. — Ed. of 15th English edition. 
 
THE DEEP VEINS OE THE LOWER EXTREMITY 765 
 
 Tributaries. — It receives in its course the following veins: 
 
 Lumbar. Suprarenal. 
 
 Right Spermatic. Phrenic. 
 
 Renal. Hepatic. 
 
 The Lmnbax Veins {vv. lumbales), four in number on each side, collect the 
 blood by dorsal tributaries from the muscles and integument of the loins and by 
 abdominal tributaries from the walls of the abdomen, where they communicate 
 with the epigastric veins. At the spine they receive veins from the spinal plexuses, 
 and then pass forward, round the sides of the bodies of the vertebrae beneath the 
 
 Fig. 476. — Spermatic veins. (Testut.) 
 
 Psoas magnus muscle, and terminate at the back part of the inferior cava. The 
 left lumbar veins are longer than the right, and pass behind the aorta. The lumbar 
 veins of a side are connected together by a longitudinal vein which passes in front 
 of the transverse processes of the lumbar vertebrae, and is called the ascending 
 lumbar vein (v. lumhalis ascendens) (Fig. 464) . It forms the most frequent origin 
 of the corresponding vena azygos, and serves to connect the common iliac, ilio- 
 lumbar, lumbar, and azygos veins of the corresponding side of the body. 
 
 The Spermatic Veins {vv. spermatic(E) (F\g. 476) emerge from the back of the testis, 
 and receive tributaries from the epididymis; they unite and form a convoluted 
 plexus called the spermatic plexus {plexus pampiniformis), which forms the chief 
 
766 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 mass of the cord : the vessels composing this plexus are very numerous, and ascend 
 along the cord in front of the vas deferens; below the external abdominal ring they 
 unite to form three or four veins, which pass along the inguinal canal, and, enter- 
 ing the abdomen through the internal abdominal ring, coalesce to form two veins, 
 which ascend on the Psoas muscle behind the peritoneum, lying one on each side 
 of the spermatic artery, and unite to form a single vein, which opens on the right 
 side into the inferior vena cava at an acute angle; on the left side into the left renal 
 vein at a right angle (Fig. 477). The termination of the left spermatic vein 
 
 SPERtMATIC VEIN- 
 LEFT SIDE 
 
 SPERMATIC VEIN— _ 
 RIGHT SIDE 
 
 Fig. 477. — Terminations of the right and left spermatic veins. (Poirier and Charpy.) 
 
 is called the emulgent vein. Professor John H. Brinton pointed out that a 
 valve is usually absent in the emulgent vein (Fig. 478), but regularly present in 
 the right spermatic vein.^ The left spermatic vein passes behind the sigmoid 
 flexure of the colon, and is thus exposed to pressure from the contents of that 
 bowel. 
 
 Surgical Anatomy. — The spermatic veins are very frequently varicose, constituting the dis- 
 ease known as varicocele. Though it is quite possible that the originating cause of this affection 
 may be a congenital abnormaUty either in the size or number of the veins of the pampiniform 
 plexus, still it must be admitted that there are many anatomical reasons why these veins should 
 become varicose — viz., the imperfect support afforded to them by the loose tissue of the scrotum; 
 their great length; their vertical course; their dependent position; their plexiform arrangement 
 in the scrotum, with their termination in one small vein in the abdomen ; their few and imperfect 
 valves; and the fact that they may be subjected to pressure in their passage through the abdominal 
 wall. The left veins more often become varicose than the right veins, probably, as Brinton sug- 
 gests, because the right spermatic vein practically always has a valve and opens into the vena 
 cava at an acute angle, whereas the left spermatic vein is not unusually destitute of a valve at 
 its opening and passes into the left renal vein at a right angle. 
 
 The Ovarian Veins {vv. ovaricoe) (Fig. 475) are analogous to the spermatic in the 
 male; they form a plexus near the ovary in the broad ligament and about the Fallo- 
 pian tube, communicating with the uterine plexus. They terminate in the same way 
 as the spermatic veins in the male. Valves are occasionally found in these veins. 
 These vessels, like the uterine veins, become much enlarged during pregnancy. 
 
 1 See John H. Brinton in the American Journal of the Medical Sciences, and also Handbuch der Topographi- 
 schen Anatomic, von Joseph Hyrtl. Rivington maintains that a valve is usually found at the orifices of both the 
 right and left spermatic veins. When no valves exist at the opening of the left spermatic vein into the left renal 
 vein, valves are generally present in the left renal vein within a quarter of an inch from the orifice of the 
 spermatic vein. (Journal of Anatomy and Physiology, vol. vii. p. 163). — Ed. of 15th English edition. 
 
THE DEEP VEINS OF THE LOWER EXTREMITY 
 
 767 
 
 The Renal Veins {vv. renales) (Fig. 465) are of large size, and are placed in front 
 of the renal arteries.^ The left is longer than the right, and passes in front of the 
 aorta, just below the origin of the superior mesenteric artery. It receives the left 
 spermatic, the left inferior, and, generally, the left suprarenal veins. It opens into 
 the vena cava a little higher than the right. The utero-venous triangle of Byron 
 Robinson is formed by the ureter, the renal veins, and the ovarian veins. 
 
 The Suprarenal Veins (vv. swprarenales) (Fig. 464) are two in number: that on 
 the right side terminates in the vena cava; that on the left side, in the left renal 
 or in the left phrenic vein. 
 
 The Phrenic Veins {vv. phrenicce) follow the course of the phrenic arteries. 
 The two superior phrenic veins (vv. phrenicoB superior es) , of small size, accom- 
 pany the phrenic nerve and comes nervi phrenici artery, and join the internal 
 mammary vein. The two inferior phrenic veins {vv. phrenicoe inferiores) follow 
 the course of the phrenic arteries, and terminate, the right in the inferior vena 
 cava, the left in the left renal vein. 
 
 Fig. 478. — Dis.section of the vena cava, emulgent- and spermatic veins, showing the right spermatic valve 
 and its accompanying sinus, c, vena cava; e, emulgent vein; r, right spermatic vein; /, left spermatic vein; 
 a. aperture by which the right spermatic vein empties into the vena cava; v, right spermatic valve; s, sinus 
 across which the valve is stretched; /, termination of the left spermatic vein in the emulgent vein. (John H. 
 Brinton.) 
 
 The Hepatic Veins {vv. hepaticce) commence in the substance of the liver, in 
 the capillary terminations of the portal vein and hepatic artery, intralobular veins: 
 these tributaries, gradually uniting into sublobular veins; usually form three large 
 hepatic veins, which converge toward the posterior surface of the liver and open 
 into the inferior vena cava, whilst that vessel is situated in the groove at the back 
 part of this organ. Of these three veins, one from the right and another from 
 
 1 The student may observe that all veins above the Diaphragm, which do not lie on the same plane as the 
 arteries which they accompany, lie in front of them, and that all veins below the Diaphragm, which do not 
 lie on the same plane as the arteries which they accompany, lie behind them, except the renal and profunda 
 femoris vein. — En. of 15th English edition. 
 
768 THE BLOOD -VASCULAR SYSTEM 
 
 the left lobe open obliquely into the inferior vena cava, that from the middle of 
 the organ and lobulus Spigelii having a straight course. The hepatic veins run 
 singly, and are in direct contact with the hepatic tissue. They are destitute of 
 valves. 
 
 The Portal System of Veins (Fig. 479). 
 
 The portal venous system is composed of four large veins which collect the venous 
 blood from the viscera of digestion (stomach, intestine, and pancreas) and from 
 the spleen. The trunk formed by their union, the Portal Vein {vena portce), 
 enters the liver and ramifies throughout its substance after the manner of an 
 artery and ends in capillaries, from which the blood is collected into the hepatic 
 veins, which terminate in the inferior vena cava. The branches of this vein are 
 in all cases single, and destitute of valves. 
 
 The veins forming the portal system are — the 
 
 Superior Mesenteric. Inferior Mesenteric. 
 
 Splenic. Gastric. 
 
 Cystic. 
 
 The Superior Mesenteric Vein (v. mesenterica superior) (Fig. 479) returns the 
 blood from the small intestines and from the caecum and ascending and transverse 
 portions of the colon, corresponding with the distribution of the branches of the 
 superior mesenteric artery. The large trunk formed by the union of these branches 
 ascends along the right side and in front of the corresponding artery, passes in front 
 of the transverse portion of the duodenum, and unites, behind the upper border 
 of the pancreas, with the splenic vein to form the vena portse. It receives the 
 right gastro-epiploic vein. The appendicular vein is a tributary of the superior 
 mesenteric vein. 
 
 The Splenic Vein (v. lienalis) (Fig. 479) commences by five or six large branches 
 which return the blood from the substance of the spleen. These, uniting, form a 
 single vessel, which passes from left to right, grooving the upper and back part of 
 the pancreas below the artery, and terminates at its greater end by uniting at a 
 right angle with the superior mesenteric to form the vena portse. The splenic vein 
 is of large size, and not tortuous like the artery. It receives the vasa brevia from 
 the left extremity of the stomach, the left gastro-epiploic vein, pancreatic branches 
 from the pancreas, the pancreatico-duodenal vein, and the inferior mesenteric vein. 
 
 The Inferior Mesenteric Vein {v. mesenterica inferior) (Fig. 479) returns the 
 blood from the rectum, sigmoid flexure, and descending colon, corresponding with 
 the ramifications of the branches of the inferior mesenteric artery. It lies to the left 
 of the artery, and ascends beneath the peritoneum in the lumbar region ; it passes 
 behind the transverse portion of the duodenum and pancreas, and terminates 
 in the splenic vein. Its hemorrhoidal branches, the superior haemorrhoidal veins, 
 inosculate with the middle hemorrhoidal branches of the internal iliac, and thus 
 establish a communication between the portal and the general venous system.^ 
 
 The Gastric Veins (vv. gastricce) (Fig. 479) ai-e two in number: one, a small vein, 
 corresponds to the pyloric branch of the hepatic artery; the other, considerably 
 larger, corresponds to the gastric artery. The former, the pyloric vein (v. pylorica), 
 runs along the lesser curvature of the stomach toward the pyloric end, receives 
 branches from the pylorus and duodenum, and ends in the vena portse. The 
 latter, the gastric or coronary vein (v. coronaria veniriculi), begins near the pylorus, 
 
 1 Besides this anastomosis between the portal vein and the branches of the vena cava, other anastomoses 
 between the portal and systemic veins are formed by the communication between the gastric veins and the 
 oesophageal veins, which empty themselves into the vena azygos minor; between the left renal vein and the 
 vems of the intestines, especially of the colon and duodenum; between the veins of the round ligament of the 
 liver and the portal veins; and between the superficial branches of the portal veins of the liver and the phrenic 
 yems, as pointed out by Mr. Kiernan. (See Physiological Anatomy, by Todd and Bowman, 1859, vol. ii. p. 
 348).— Ed. of 15th English edition. 
 
THE PORTAL SYSTEM OF VEINS 
 
 769 
 
 runs along the lesser curvature of the stomach toward the oesophageal opening 
 in the diaphragm, and then passes across the front of the spine from left to right 
 to end in the vena portse, at a point a little above the junction of the pyloric vein. 
 The Cystic Vein {v. cystica) (Fig. 479) . — The vena portae generally receives the 
 cystic vein, although that vessel sometimes terminates in the right branch of the 
 vena portae. 
 
 Fig. 479. — Portal vein and its branches. 
 
 Note. In this diagram the right gastro-epiploic vein opens into the splenic vein; generally 
 It empties itself into the superior mesenteric, close to its termination. 
 
 The Portal Vein {vena 'porta:) (Fig. 479) is formed by the junction of the superior 
 mesenteric and splenic veins, their union taking place in front of the vena cava and 
 behind the upper border of the head of the pancreas. Passing upward through 
 the right border of the lesser omentum to the under surface of the liver, it enters 
 the transverse fissure, where it is somewhat enlarged, forming the sinus of the 
 portal vein, and divides into two branches which accompany the ramifications of 
 the hepatic artery and hepatic duct throughout the substance of the liver. Of 
 
 49 
 
770 
 
 THE BLOOD -VASCULAR SYSTEM 
 
 these two branches, the right is the larger, but the shorter, of the two. The portal 
 vein is about three or four inches in length, and, whilst contained in the lesser 
 omentum, lies behind and between the common bile-duct and the hepatic artery, 
 the former being to the right, the latter to the left. These structures are accom- 
 panied by filaments of the hepatic plexus of nerves and numerous lymphatics, 
 and are surrounded by a quantity of loose areolar tissue, the capsule of Glisson. 
 
 The portal vein divides, in the substance of the liver, like an artery, and its 
 minute ramifications end in capillaries, from which the blood is carried to the 
 inferior vena cava by the hepatic veins; these veins also collect the blood which 
 has been brought to the liver by the hepatic artery. It will therefore be seen 
 that the blood which is carried to the liver by the portal vein passes through two 
 sets of capillary vessels — viz. : (1) the capillaries in the stomach, intestine, pancreas, 
 and spleen, and (2) the capillaries of the portal vein in the liver. 
 
 THE CARDIAC VEINS (Fig. 480). 
 The veins which return the blood from the substance of the heart are — the 
 
 Great Cardiac Vein. 
 Posterior Cardiac Vein. 
 Left Cardiac Veins. 
 
 Anterior Cardiac Veins. 
 Right or Small Coronary Vein. 
 Coronary Sinus. 
 Vense Thebesii. 
 
 The Great Cardiac or Left Coronary Vein {v. cordis magna) is a vessel of 
 considerable size, which commences at the apex of the heart, and ascenrls along 
 the anterior interventricular groove to the base of the ventricles. It then curves 
 
 PULMONARY 
 VEINS. 
 LEFT AURICULAR, 
 APPENDIX 
 
 RIGHT CORONARY ARTERY 
 
 AURICULAR- VENTRICULAR. 
 GROOVE 
 
 CORONARY. 
 SINUS 
 
 LEFT 
 VENTRICLE 
 
 VENA AZYGOS 
 MAJOR 
 
 PULMONARY 
 
 VEINS 
 LEFT 
 
 AURICLE 
 
 POSTERIOR CARDIAC 
 VEIN 
 
 POSTERIOR 
 INTERVENTRIO 
 ULAR GROOVE 
 
 'BIGHT 
 VENTRICLE 
 
 RIGHT CORONARY 
 ARTERY DESCEND- 
 ING BRANCH 
 
 Fig. 480. — Cardiac veins, dorsal view. (Testut.) 
 
 to the left side, around the auriculo-ventricular groove, between the left auricle 
 and ventricle, to the back part of the heart, and opens into the left extremity 
 of the coronary sinus, its aperture being guarded by two valves. It receives, in 
 
THE CARDIAC VEINS 771 
 
 its course, tributaries from both ventricles, but especially from the left, and also 
 from the left auricle; one of these ascending along the thick margin of the left 
 ventricle is of considerable size, and is called the left marginal vein. The vessels 
 joining the great cardiac vein are provided with valves. 
 
 The Posterior or Middle Cardiac Vein (v. cordis media) commences by small 
 tributaries, at the apex of the heart, communicating with those of the preceding. 
 It ascends along the posterior interventricular groove to the base of the heart, 
 and terminates in the coronary sinus, its orifice being guarded by a valve. It 
 receives veins from the posterior surface of both ventricles. 
 
 The Left Cardiac Vein {v. 'posterior ventriculi sinistri) receives three or four 
 small vessels, which collect the blood from the posterior surface of the left ven- 
 tricle. It opens into the lower border of the coronary sinus. 
 
 The Anterior Cardiac Veins {w. cordis anteriores) are three or four small 
 vessels, which collect the blood from the anterior surface of the right ventricle. 
 One of these, the vein of Galen, larger than the rest, runs along the right border 
 of the heart. They open separately into the lower part of the right auricle. 
 
 The Right Cardiac or Small Coronary Vein {v. cordis parva) runs along the 
 groove between the right auricle and ventricle, to open into the right extremity of 
 the coronary sinus. It receives blood from the back part of the right auricle and 
 ventricle. 
 
 The Coronary Sinus (sinus coronarius) is that portion of the anterior or great 
 cardiac vein which is situated in the posterior part of the left auriculo-ventricular 
 groove. It is about an inch in length, presents a considerable dilatation, and is 
 covered by the muscular fibres of the left auricle. It receives most of the veins of 
 the heart. Besides those mentioned it receives the oblique vein of Marshall {v. obliqua 
 atrii sinistri) from the back part of the left auricle, the remnant of the obliterated 
 left Cuvierian duct of the foetus, described by Mr. Marshall. The great coronary 
 sinus terminates in the right auricle, between the inferior vena cava and the 
 auriculo-ventricular aperture, its orifice being guarded by a semilunar fold of the 
 lining membrane of the heart, the Thebesian valve. All the veins joining this 
 vessel, excepting the oblique vein above mentioned, are provided with valves. 
 
 The Venae Thebesii (vence cordis minimcE) are numerous minute veins, which 
 return the blood directly from the muscular substance, without entering the venous 
 current. They open by minute orifices, foramina Thebesii (foramina venarum 
 minamarum), chiefly on the inner surface of the right auricle. 
 
THE LYMPHATIC SYSTEM. 
 
 Lymph is obtained from the blood-plasma. From lymph the body cells 
 obtain food, into lymph they discharge their waste materials, and there is a 
 distinct lymphatic circulation, the constituents of the plasma passing into the 
 perivascular lymph-spaces and returning to the heart by way of the lymphatics 
 and certain veins. 
 
 The lymphatic system consists of lymphatic glands— large lymph-vessels, small 
 lymph- vessels (lymphatic capillaries), the perivascular lymph-spaces, the lymph 
 canalicular system, and the body cavities. To this system also belong the lacteal or 
 chyliferous vessels. The lacteals are the lymphatic vessels of the small intestine,, 
 and differ in no respect from the lymphatics generally, excepting that during the 
 process of digestion they contain a milk-white fluid, the chyle, which passes into 
 the blood through the thoracic duct. 
 
 The lymph canalicular system is the system of spaces in areolar connective 
 tissue. The spaces are called lymph-spaces. In these spaces lie the cells of the 
 tissue. The larger spaces are lined with endothelium, the smaller spaces are not 
 lined -with endothelium; they form connections with each other by anastomotic 
 channels and constitute a system of spaces and channels which probably join 
 the lymphatic capillaries. 
 
 The perivascular lymph-spaces are found around certain blood-vessels. Each 
 space is lined with endothelium, and is joined to other spaces by trabecuhe of con- 
 nective tissue. The spaces form a system which joins the lymphatic capillaries. 
 Perivascular lymph-spaces have been demonstrated in the Haversian canals and 
 in the subdural space of the pia mater. 
 
 The pleural, pericardial, peritoneal, and S3movial cavities belong to the lymphatic 
 system. These cavities are lined by endothelial cells. Beneath the layer of lining 
 cells are lymph-spaces or lymph-vessels, which communicate with the body cavity 
 by means of numerous openings in the lining membrane. These openings are 
 called stomata. 
 
 Lymph-capillaries are larger than blood-capillaries, but the diameter of a lymph- 
 capillary is different at different points, at some places being much larger than 
 at others. Lymph-capillaries are formed of flattened endothelial cells. In some 
 situations networks of lymphatic capillaries surround the blood-vessels. The 
 lymph- vessels are called the lymphatics. 
 
 The lymphatics have derived their name from the appearance of the fluid con- 
 tained in their interior (lympha, water). They are also called absorbents, from the 
 property they possess of absorbing certain materials from the tissues and con- 
 veying them into the circulation. Larger lymphatics are called trunks and the 
 largest are called ducts. 
 
 The lymphatics are exceedingly delicate vessels, the coats of which are so 
 transparent that the fluid they contain is readily seen through them, and they 
 appear milky-white; hence the name Asellius gave them of lacteal veins. They 
 retain a nearly uniform size, and may be cylindrical in shape, but usually are inter- 
 rupted at intervals by constrictions which give them a knotted, beaded, or sac- 
 like appearance. These constrictions are due to the presence of valves in the 
 interior of the vessel. Lymphatic vessels do not invariably contain valves. Valves 
 (772) 
 
 J 
 
THE LYMPHATIC SYSTEM 773 
 
 are absent at the starting points of lymphatics, are absent in lymphatic capillaries, 
 are not numerous in the largest ducts (thoracic duct), and are seldom found in vis- 
 ceral lymphatics. The valves are not found in fixed situations and vary in number. 
 Between the ends of the fingers and the axillary glands Sappey counted from sixty 
 to eighty. " They are arranged in pairs and resemble the aortic semilunar valves."^ 
 The lymphatic capillaries are composed purely of endothelium, but the collecting 
 trunks possess not only an endothelial inner coat, but an investing elasto-muscular 
 coat. Vessels in the subcutaneous connective tissue are devoid of muscle. Lymph- 
 atics have been found in nearly every texture and organ of the body v^hich contains 
 blood-vessels. Such non-vascular structures as cartilage, the nails, cuticle, and 
 hair have none, but with these exceptions it is probable that eventually all parts 
 will be found to be permeated by these vessels. 
 
 A larger lymphatic vessel is composed of three coats. The inner coat is 
 composed of elastic tissue hned with endothelium. The middle coat is com- 
 posed of elastic and muscular fibres. The external coat is composed of connec- 
 tive tissue intermixed with smooth muscular fibres longitudinally or obliquely 
 placed. 
 
 The thoracic duct possesses a subendothelial layer of connective tissue like that 
 found in the arteries, and in the middle coat there is a longitudinal layer of 
 connective tissue. The wall of a smaller lymphatic contains no elastic and no 
 muscular tissue, and consists merely of connective tissue lined with endothelium. 
 
 The lymphatics are arranged in superficial and deep sets. The superficial lym- 
 phatics, on the surface of the body, are placed immediately beneath the integument, 
 accompanying the superficial veins; they join the deep lymphatics in certain situa- 
 tions by perforating the deep fascia. In the interior of the body the lymphatics 
 lie in the submucous areolar tissue throughout the whole length of the gastro- 
 pulmonary and genito-urinary tracts, and in the subserous tissue of the thoracic 
 and abdominal cavities. In the cranial cavity the perivascular sheaths are lymph- 
 spaces. A plexiform network of minute, closed, capillary lymphatics may be found 
 interspersed among the proper elements and blood-vessels of the several tissues, the 
 vessels composing which, as well as the meshes between them, are much larger than 
 those of the capillary blood-vessel plexus. From these networks small collecting 
 vessels emerge, pass to a neighboring gland, and divide into a capillary network 
 in the gland. Numerous small vessels emerge from the gland, which unite into 
 one lymphatic vessel, which joins a larger lymphatic trunk, which empties into 
 a branch of the superior vena cava. The deep lymphatics, fewer in number and 
 larger than the superficial, accompany the deep blood-vessels. Their mode of 
 origin is probably similar to that of the superficial vessels. The lymphatics of 
 any part or organ exceed the veins in number and in capacity, but in size they 
 are much smaller. Their anastomoses also, especially those of the large trunks, 
 are more frequent, and are effected by vessels equal in diameter to those which 
 they connect. The continuous trunks retain the same diameter throughout. As 
 the lymphatic vessels approach their point of discharge their number diminishes, 
 but the calibre of the remainder does not increase in proportion. 
 
 The gaps in the connective tissue, the larger of which are lined with endothelium, 
 the smaller of which are devoid of endothelial lining, and all of which communicate 
 with the lymphatic capillaries, are known as lymphatic spaces. It is asserted by 
 some, but is not proved, that the spaces are continuous with the lymph-capillaries. 
 Some hold that lymph gets from the spaces into the capillaries by means of open- 
 ings in intervening tissue. The perivascular spaces, the serous cavities, and the 
 ventricles of the brain resemble in function lymphatic structures. 
 
 > Treatise on Anatomy. By P. Poirier and A. Charpy. Article on the Lymphatics. By G. Delamare, P. Poirier, 
 and B. Cun6o. 
 
774 
 
 THE LYMPHATIC SYSTEM 
 
 The lymphatic or absorbent glands (iymphoglandulae) , named also conglobate 
 glands and lymph-nodes, are small, solid, glandular bodies situated in the course of 
 the lymphatic and lacteal vessels. They vary from microscopic dimensions to the 
 size of an olive, and their color, on section, is of a pinkish-gray tint, excepting the 
 bronchial glands, which in the adult are mottled with black, the hepatic glands, 
 which are yellow, and the splenic glands, which are brown. Each gland has 
 a layer or capsule of cellular tissue investing it, from which prolongations dip 
 into its substance, forming partitions. The lymphatic and lacteal vessels pass 
 
 through these glands in their passage to the lymph- 
 atic ducts. A lymphatic or lacteal vessel, previous to 
 entering a gland, divides into several small branches, 
 which are named afferent vessels {vasa afferentia). 
 As they enter the gland, the external coat of each 
 becomes continuous with the capsule of the gland, 
 and the vessels becoming much thinned, and consist- 
 ing only of their internal or endothelial coat, pass 
 into the gland, and branch out upon and in the tissue 
 of the capsule, these branches opening into the lymph- 
 sinuses of the gland. There is an extensive sinus 
 beneath the capsule; from this subcapsular sinus 
 numerous branches run inward to a central sinus. 
 From both sinuses fine branches proceed to form a 
 plexus, the vessels of which unite to form a single 
 efferent vessel (vas efferens), which, on emerging 
 from the gland, is again invested with an external 
 coat from the gland capsule. The lymph-glands are 
 filters through which lymph and chyle flow. Car- 
 cinoma cells are caught in them, and the dissemina- 
 tion of the disease is retarded. In the glands are 
 masses of newly formed leukocytes which attack any 
 bacteria in the lymph or chyle. 
 
 The size of the lymphatic glands decreases as age 
 advances, and in very old individuals many glands 
 actually disappear. It is impossible to estimate the 
 number of macroscopic glands. Sappey estimated the number to be from 600 to 
 700. Glands are embedded in fat and are distinctly movable. Some of them are 
 superficial (above the deep fascia); others are deep (below the deep fascia). 
 Occasionally a gland exists alone, but, as a rule, they are assembled in com- 
 munities or chains of from eight to twelve, or even more. They are usually 
 arranged around vessels, and often are upon vessels. The glands have a plen- 
 tiful blood-supply, and contain not only vascular nerves, but definite nerve- 
 plexuses. Besides the glands, the body contains numerous lymphoid areas, 
 which, in structure and function, are allied to lymph-glands (tonsils, Peyer's 
 patches, etc.). 
 
 Surgical Anatomy. — In an operation for cancer it is not sufficient to cut wide of the growth 
 and remove it; it is imperatively necessary to remove the lymphatic glands which receive lymph 
 from the diseased area, and also, when possible, the lymphatic vessels between the cancer and 
 the glands. Glands are diseased very early in cancer, long before they are palpably enlarged, 
 and are usually infected by emboU of cancer cells. The rule is in any cancer, however recent, 
 to regard the associated glands as diseased, whether enlarged or not, and to thoroughly remove 
 them, if possible, in one piece, with the intervening lymph-vessels and the area of primary 
 malignant growth. 
 
 P^iG. 481. — A lymph-node with its 
 afferent and effeient vessels. (Tes- 
 tut.) 
 
THE THORACIC AND BIGHT LYMPHATIC DUCT 
 
 lib 
 
 Intercostal 
 glands. 
 
 THE THORACIC DUCT AND THE RIGHT LYMPHATIC DUCT. 
 
 The thoracic tkict or the left lymphatic duct (ductus thoracicus) (Figs. 482 and 
 483) conveys the great mass of lymph and chyle into the blood. It is the common 
 trunk of all the lymphatic vessels 
 
 of the body below the Diaphragm, i=: .iiiil — li ^" 
 
 and usually, but not always, also 
 receives the lymph from the left 
 side of the body above the Dia- 
 phragm. It does not drain the 
 right side of the head and neck, 
 the right upper extremity, the right 
 lung, right side of the heart, and the 
 convex surface of the liver. It partly 
 drains the right chest wall. It varies 
 in length from fifteen to eighteen 
 inches in the adult, and extends from 
 the second lumbar vertebra to the 
 root of the neck. It commences in the 
 abdomen by a triangular dilatation, 
 the receptaculum chyli or the reser- 
 voir or cistern of Pecquet (cisterna 
 chyli), which is situated upon the 
 front of the bodies of the first and 
 of the second lumbar vertebra*, to 
 the right side and behind the aorta, 
 by the side of the right crus of the 
 Diaphragm. The receptaculum is 
 absent in some individuals. The 
 thoracic duct ascends into the thorax 
 through the aortic opening in the 
 Diaphragm, lying to the right of 
 the aorta, and is placed in the pos- 
 terior mediastinum in front of the 
 vertebral column, lying between 
 the aorta and vena azygos major. 
 Opposite the fourth dorsal vertebra 
 it inclines toward the left side, and 
 ascends behind the arch of the aorta 
 on the left side of the oesophagus, 
 and behind the first portion of the 
 left subclavian artery, to the upper 
 orifice of the thorax. Opposite the 
 seventh cervical vertebra it turns 
 outward and then curves downward 
 over the subclavian artery and in 
 front of the Scalenus anticus mus- 
 cle, so as to form an arch, and ter- 
 minates in the left subclavian vein 
 at its angle of junction with the left 
 internal jugular vein. It usually 
 opens at the apex of the angle in the superior and outer surface, but may open 
 on the posterior surface. Sometimes it terminates by two branches. Figs. 482 
 
 Fig. 482. — The thoracic and right lymphatic ducts. 
 
776 
 
 THE LYMPHATIC SYSTEM 
 
 and 485 show the termination of the thoracic duct. The thoracic duct, at 
 its commencement, is about equal in diameter to that of a goose-quill, dimin- 
 ishes considerably in its calibre in the middle of the thorax, and is again 
 dilated just before its termination, the ampulla. It is generally flexuous in its 
 
 SUPERIOR INTER- 
 COSTAL VEIN 
 MEDIASTINAL LYM- 
 PHATIC VESSEL 
 
 SCALENUS ANTICU8 
 MUSCLE 
 
 SUBCLAVIAN 
 ARTERY 
 
 SUPERIOR 
 
 INTERCOSTAL 
 
 VEIN 
 
 BRONCHIAL 
 LYMPHATIC 
 VESSEL 
 
 VENA AZYGOS 
 
 MINOR 
 
 SUPERIOR 
 
 VENA AZYGOS 
 MAJOR 
 
 DESCENDING 
 THORACIC LYM- 
 PHATIC TRUNK 
 
 RECEPTACULUM 
 CHYLI 
 
 VENA AZYGOS 
 MINOR INFERIOR 
 
 — OESOPHAGUS 
 
 DESCENDING THORACIC 
 LYMPHATIC TRUNK 
 
 INFERIOR 
 PHRENIC ARTERY 
 SUPRARENAL 
 BODY 
 
 COELIAC AXIS 
 
 SUPERIOR 
 MESENTERIC 
 COMMON INTESTINAL 
 LYMPHATIC TRUNK 
 
 RENAL ARTERY 
 
 LUMBAR 
 VEINS 
 
 COMMON LUMBAR 
 LYMPHATIC TRUNK 
 
 Fig. 483. -^Thoracic duct and its tributaries. (Cunningham.) 
 
 course, the older the person the greater the flexuosity, and it is constricted at inter- 
 vals so as to present a varicose appearance. The thoracic duct not infrequently 
 divides in the middle of its course into two branches of unequal size, which 
 soon reunite, or divides into several branches, which form a plexiform interlace- 
 ment. It occasionally divides, at its upper part, into two branches, of which the 
 
THE THORACIC AND BIGHT LYMPHATIC DUCT 
 
 111 
 
 one on the left side terminates in the usual manner, while that on the right opens 
 into the right subclavian vein, in connection with the right lymphatic duct. The 
 thoracic duct has several valves throughout its whole course, but they are more 
 numerous in the upper than in the lower part, and the lower valves are not com- 
 petent; at its termination it is provided with a pair of competent valves, the free 
 borders of which are turned toward the vein, so as to prevent the passage of 
 venous blood into the duct. 
 
 The common intestinal trunk (truncus intestinalis) (Figs, 483, 484, and 511) 
 empties into the receptaculum and brings lymph from the small intestine (lacteals), 
 the stomach, the pancreas, and the spleen. 
 
 Radicals of Origin and Tributaries. — In most individuals the juxta-aortic 
 glands which are placed on each side of the aorta send a vessel upward and 
 inward, which unite to form the thoracic duct. The right vessel is known as 
 the truncus lymphaticus lumbalis dextra. The left vessel is known as the truncus 
 lymphaticus lumbalis sinistra. A vessel from the glands in front of (pre-aortic) 
 and back (retro-aortic) of the aorta empties into each of the above-named vessels. 
 In some cases a large vessel forms from the glands in front of the aorta and helps 
 form the duct. The receptaculum chyli receives the common intestinal lymphatic 
 trunk, which conveys lymph from the small intestine, stomach, spleen, pancreas, 
 and a portion of the liver. 
 
 Fig. 484.— Modes of origin of the thoracic duct, o, thoracic duct; a', receptaculum chyh; b, common 
 trunk of the eflerents of the right juxta-aortic glands; c, common trunk of the efferents of the left juxta- 
 aortic glands; d, one of these efferents passing through the left pillar of the diaphragm; e, right juxta-aortic 
 gland; f. left juxta-aortic gland; h, retro-aortic gland; i, common trunk of the pre-aortic glands (truncus 
 mtestinalis); j, collecting trunks of the interco.stal lymphatics, which reach the receptaculum chyh by takmg 
 the downward course. (Poirier and Charpy.) 
 
 The branches of the left lymphatic duct are (Fig. 483) : 1. A descending trunk, 
 which collects lymph from the posterior intercostal glands of the seven lower 
 intercostal spaces. 2. A trunk is formed by vessels coming from the superior juxta- 
 aortic glands beneath the Diaphragm. 3. The lymphatic vessels form the upper 
 five intercostal spaces. 4. The lymphatic vessels form the posterior mediastinal 
 glands and retrosternal glands. 5. The left jugular trunk (truncus jugularis), 
 although this may open directly into the junction of the subclavian and internal 
 jugular veins. 6. In rare cases the thoracic duct receives near its termination 
 the left subclavian trunk (truncus suhclavius) and a broncho-mediastinal trunk. 
 As a rule, however, the two last-mentioned trunks empty into the jugulo-subclavian 
 junction separately or as one duct. 
 
 The thoracic duct receives the lymph from the extremities, the deep portion 
 of the abdominal wall and of the pelvic waJl, the pelvic viscera, the kidneys and 
 suprarenal capsules, the large intestine, the small intestine, the walls of the 
 thoracic cavity, the under surface and anterior portion of the liver, th^ stomach. 
 
778 
 
 THE LYMPHATIC SYSTEM 
 
 the spleen, the pancreas, the sternal and intercostal glands, the left lung, left 
 side of the heart, trachea, and oesophagus, and often, just before its termination, 
 the lymphatics of the left side of the head and neck, and of the left upper 
 extremity. 
 
 Structure. — ^The thoracic duct is composed of three coats, which differ in some 
 respects from those of the lymphatic vessels. The internal coat consists of a single 
 layer of flattened endothelial cells; of a subendothelial layer, similar to that found 
 in the arteries; and an elastic fibrous coat, the fibres of which run in a longitudinal 
 direction. Each endothelial cell is shaped like a lance-head and has serrated 
 
 LONGUS COLLI MUSCLE 
 
 COMMON CAROTID 
 
 ARTERY 
 
 LEFT PNEUMOGASTRIC 
 
 NERVE 
 
 VERTEBRAL ARTERY 
 
 VERTEBRAL VEIN 
 
 THORACIC DUCT 
 
 INTERNAL JUGULAR 
 
 VEIN 
 
 EXTERNAL JUGULAR 
 
 VEIN 
 
 ANTERIOR JUGULAR 
 
 VEIN 
 
 SUBCLAVIAN 
 
 VEIN 
 
 Fig. 485. — The bend of the thoracic duct at its termination in the .subclavian vein. (Poirier and Charpy.) 
 
 borders. The middle coat consists of a longitudinal layer of white connective 
 tissue with elastic fibres, external to which are several laminae of muscular 
 tissue, the fibres of which are for the most part disposed transversely, but some 
 are oblique or longitudinal. The muscular fibres are intermixed with elastic 
 fibres. The external coat is composed of areolar tissue, with elastic fibres and 
 isolated fasciculi of muscular fibres. 
 
 The Right Lymphatic Duct (Ductus Lymphaticus Dexter) 
 
 (Figs. 482, 486, 487, 511). 
 
 A right lymphatic duct is frequently present. It is a short trunk, about half an 
 inch in length and a line or a line and a half in diameter. It is formed by the union 
 
 Fig. 486. — Terminal collecting trunks of the right half of the supra-diaphragmatic portion of the body, o, 
 jugular trunk; 6, subclavian trunk; c, broncho-mediastinal trunk; rf, right lymphatic trunk; e, gland of the 
 internal mammary chain; /, gland of the deep cervical chain. (Poirier and Charpy.) 
 
 of the right jugular, right broncho-mediastinal, and right subclavian trunks. 
 Often on the right side the jugular, subclavian, and broncho-mediastinal trunks 
 
LYMPHATICS OF THE CRANIAL REGION, FACE AND NECK 779 
 
 are double. Usually they open into the junction of the internal jugular and 
 subclavian veins separately. Sometimes^ they unite and open by one duct, and 
 that is the right lymphatic duct. The orifice of the right lymphatic duct is 
 guarded by tvi^o semilunar valves, which prevent the passage of venous blood 
 into the duct. 
 
 Tributaries. — The right lymphatic duct, if present, receives lymph from the 
 right side of the head and neck, the right upper extremity, the right side of 
 the thorax, the right lung, and the right side of the heart, and from part of the 
 convex surface of the liver. 
 
 LYMPHATICS OF THE CRANIAL REGION, FACE, AND NECK. 
 
 It is customary to divide the lymphatics of this region into intracranial and 
 extracranial lymphatics. The statement is made by Poirier and Cun^o^ that the 
 
 Fig. 487. — 1 lie lyinpiiancs oi t lie neau and neck. (Sappey.) 
 
 brain and its membranes are without lymphatics. They state that there are 
 spaces in the nervous centres comparable to lymphatic channels, but which are 
 not truly lymphatic vessels and which are regarded by most as independent of the 
 lymphatic system. Other writers^ believe that there are cerebral and meningeal 
 lymphatic vessels. It is highly probable that the perivascular spaces around the 
 cerebral arteries are the beginning of a cerebral lymph system, antl that these peri- 
 
 ' Article on the Lymphatics in the Treatise on Human Anatomy. 
 2 Cunningham's Text-book of Anatomy. 
 
 By Poirier and Charpy. 
 
780 
 
 THE LYMPHATIC SYSTEM 
 
 vascular lymph-channels pass out of the cranium with the arteries and the internal 
 jugular vein and terminate in the superior deep cervical glands. It is also probable 
 that lymph-spaces surround the meningeal blood-vessels and terminate in the 
 superior deep cervical and the internal maxillary glands. 
 
 The extracranial lymphatics are divided into superficial and deep, and the two 
 systems freely communicate. All of these vessels run into glands about the 
 head and neck. The superficial lymphatics take origin in the subcutaneous 
 tissue and superficial muscles. The deep vessels arise in the orbit, mouth, nose, 
 pharynx, oesophagus, tongue, larynx, and the muscular, ligamentous, and osseous 
 structures. 
 
 The Lymphatic Glands of the Head and Face. 
 
 The lymphatic glands of the head and face are as follows: 
 
 1. The Occipital. 
 
 2. The Posterior Auricular. 
 
 3. The Parotid and Subparotid. 
 
 4. The Internal Maxillary. 
 
 5. The Facial. 
 
 The Occipital or Suboccipital Glands (lymphoglandulae occipitales) (Figs. 
 488 and 49.3) . — There are only two or three of these glands on each side. They 
 are situated beneath the deep fascia, a little in front of the anterior edge of the 
 
 MASTOID 
 OCCIPITAL 
 
 FACIAL 
 
 SUBMAXILLARY 
 SUBMENTAL 
 
 Fig. 488.— General arrangement of the lymphatic gland groups of the head and neck. (Poirier and Charpy.) 
 
 Trapezius muscle, near to but seldom upon the insertion of the Complexus 
 rnuscle. They receive lymph from the occipital region of the scalp and from 
 them it is sent to the upper deep cervical glands. 
 
 The Posterior Auricular Retro-auricular or Mastoid Glands (lymphoglandulae 
 aunculares posteriores) (Figs. 488, 492, and 493).— There are two of these on each 
 side. They are situated just beneath the lower margin of the Retrahens aurem 
 muscle. They receive lymph from the parietal lymph- vessels, "from the internal 
 
THE LYMPHATIC GLANDS OF THE HEAD AND FACE 781 
 
 surface of the auricle, with the exception of the lobule, and from the posterior 
 surface of the external auditory meatus."^ The lymph-vessels from these glands 
 empty into the upper deep cervical glands. 
 
 GLANDS OF 
 EXTERNAL JUGULAR i 
 CHAIN 
 
 SUBMAXILLARY 
 
 GLAND OF 
 INTERNAL JUGULAR 
 CHAIN 
 
 Fig. 489. — The lymphatics of the neck. (Kiittner.) 
 
 The Parotid Lymph-glands {lymphoglandulae auriculares anteriores) (Figs. 
 488, 489, and 493) are divided into two groups, the superficial and the deep. 
 
 The Superficial Paxotid or Pre-auricular Lymph-glands. — The superficial parotid 
 lymph-glands are not the subcutaneous lymph-glands occasionally but very rarely 
 
 SUBORBITAL 
 GLAND OF NASO« 
 GENIAL GROOVE 
 BUCCINATOR 
 
 (posterior mass) 
 
 BUCCINATOR 
 
 (middle mass) 
 
 SUPRAMAXILLARY 
 INFRAMAXILLARV 
 
 Fig. 490. — Facial glands. (Poirier and Charpy.) 
 
 found in this region, and which have been described by Richet, but are lymph- 
 nodes situated between the parotid fascia and the parotid salivary gland. There 
 may be three glands, two glands, or only one gland. 
 
 ' The Lymphatics. By G. Delamare, P. Poirier, and B. Cun#o. 
 Cecil H. Leaf. 
 
 English edition, translated and edited by 
 
782 THE LYMPHATIC SYSTEM 
 
 The Deep Parotid Lymph-glands. — The deep parotid lymph-glands are situated 
 within the parotid salivary gland. There are from fifteen to twenty of the deep glands. 
 The parotid glands receive lymph from the eyelids, eyebrows, the root of the nose, 
 upper portion of the cheek, frontal portion of the scalp, temporal portion of the 
 scalp, from the outer surface of the pinna, from the external auditory meatus, 
 from the tympanum, and possibly from the mucous membrane of the nose, the 
 posterior alveolar region of the superior maxillary bone, and the soft palate. 
 Lymphatics pass from the superficial parotid glands into the superficial cervical 
 and the upper deep cervical glands. Lymphatics pass from the deep parotid 
 glands into the upper deep cervical glands. 
 
 The Subparotid Glands (lymphoglandulae parotidae). — The subparotid glands 
 lie between the parotid salivary gland and the pharynx, and they are close to the 
 internal carotid artery and the internal jugular vein. They receive lymph from 
 the nasal fossfe, naso-pharynx, and Eustachian tube, and send vessels to the upper 
 deep cervical glands. 
 
 The Internal Maxillary or Zygomatic Glands (lymphoglandulae jaciales pro- 
 f undue) (Fig. 493). — The internal maxillary glands lie in the course of the internal 
 maxillary artery in the anterior pharyngeal wall. They receive vessels from the 
 naso-pharynx, palate, zygomatic fossa, temporal fossa, and orbit. From them 
 vessels go to the upper deep cervical glands. 
 
 The Facial Glands or Genial Glands {lymphoglandulae jaciales) (Figs. 488, 
 489, and 490). — The facial glands lie in three groups in the course of the lymphatic 
 vessels which are passing to the submaxillary glands. According to Poirier and 
 Cun^o the supramaxillary or inferior group (Fig. 490) lies upon the outer surface 
 of the mandible, at the anterior margin of the Masseter muscle, and beneath the 
 Platysma myoides. There may be only one or two glands in this group, but often 
 there are ten or twelve. These glands lie about the facial artery and vein and 
 are not constantly present. In many cases a salivary gland, the inframaxillary 
 (Fig. 490), is interposed between the supramaxillary and submaxillary glands. 
 The buccinator, buccal, or middle group (Figs. 490 and 493) is present in about 
 one-third of the subjects and lies upon the outer surface of the Buccinator muscle 
 external to the buccal fascia. Some of these glands are situated in the region 
 where Steno's duct perforates the Buccinator muscle. Others are beneath the 
 posterior fibres of the Zygomaticus major muscle. 
 
 The superior group of facial glands (Fig. 490) includes a malar gland, a suborbital 
 gland, and a gland in the naso-genial groove.^ An anterior gland is sometimes 
 found, subcutaneous, on the outer surface of the Orbicularis oris muscle, the 
 commissural gland. 
 
 The Lymphatic Vessels of the Cranial Region (Figs. 487, 493). 
 
 The lymphatic vessels of the cranial subcutaneous tissues are divided into 
 anterior, lateral, and posterior. The anterior or frontal terminate in the parotid 
 lymph-glands. The lateral or parietal terminate in the parotid and mastoid lymph- 
 glands. The posterior or occipital terminate in the sterno-mastoid and occipital 
 glands. 
 
 The Lymphatic Vessels of the Face, the Interior of the Nose, Tongue, Floor 
 of the Mouth, Pharynx, Larynx, and Thyroid Gland 
 
 (Figs. 487, 489, 490, 491, 492, 494). 
 
 The lymphatic vessels of the face are more numerous than those of the cranial 
 region, and commence over its entire surface. Those from the frontal region 
 accompany the frontal vessels; they then pass obliquely across the face, running 
 
 ^ Article on the Lymphatics in the Treatise on Human Anatomy. By P. Poirier and B. Cun6o. 
 
THE LYMPHATIC VESSELS OF THE FACE 
 
 783 
 
 with the facial vein, pass through the glands on the buccal surface of the Buccina- 
 tor muscle, and join the submaxillary lymphatic glands. The submaxillary lymph 
 glands receive the lymphatic vessels from the lips, and are often found enlarged 
 in cases of malignant disease of those parts. 
 
 The lymphatics of the orbit and of the temporal and zygomatic fossae run with 
 the branches of the internal maxillary artery to the maxillary glands, and after- 
 ward to the deep cervical glands. 
 
 VESSELS FROM 
 BASE OF TONGUE 
 
 MARGINAL COL- 
 ING TRUNKS 
 
 PRINCIPAL 
 GLANO 
 
 SUBMENTAL 
 
 TRUNKS OF 
 MARGIN 
 
 SUPRA-OMO 
 HYOID GLAND 
 
 Fig. 491. — The lymphatics of thfe tongue; anterior view. (Poirier and Charpy.) 
 
 The lymphatics of the nose can be injected from the subdural and subarachnoid 
 spaces. They terminate in the retro-pharyngeal and suprahyoid glands. The 
 lymphatics of the tongue (Fig. 491) chiefly accompany the ranine vein first to the 
 lingual glands and from these to the deep cervical glands. The lymphatics from 
 the anterior part of the tongue and floor of the mouth pierce the Mylo-hyoid muscles 
 and so reach the submaxillary lymph-glands (p. 1093). From the upper part of 
 the pharynx the lymphatics pass to the retro-pharyngeal glands; from the lower 
 part of the phaiynx to the deep cervical glands. From the larynx two sets of vessels 
 arise: an upper, piercing the thyro-hyoid membrane and joining the upper set 
 of deep cervical glands; and a lower, perforating the crico-thyroid membrane to 
 join the lower set of deep cervical glands. The lymphatics of the thyroid gland 
 accompany the superior and inferior thyroid arteries, and open partly into the 
 upper and partly into the lower set of deep cervical glands. 
 
784 
 
 THE LYMPHATIC SYSTEM 
 
 The Lymphatic Glands of the Neck. 
 
 The lymphatic glands of the neck are: 
 
 1. The Superficial Cervical, including the external jugular and the superficial 
 anterior cervical. 
 
 2. The Submaxillary. 
 
 3. The Submental. 
 
 4. The Retro-pharyngeal. 
 
 5. The Deep Cervical, including the anterior deep cervical. 
 
 The Superficial Cervical Glands {lymphoglandulae cervicales superficiales) 
 (Figs. 492 and 493) . — The superficial cervical glands are composed of two groups, 
 the external jugular and the superficial anterior cervical glands. 
 
 The External Jugular Glands (Figs. 489 and 492). — The external jugular glands 
 are superficial to the Sterno-cleido-mastoid muscle. They are four to six in 
 
 LYMPHATIC VESSELS 
 OF AURICLE 
 
 MASTOID GLANDS 
 
 STERNO-MASTOID 
 
 GLAND (external 
 group) 
 
 GLAND OF 
 
 EXTERNAL JUGULAR 
 CHAIN 
 
 STERNO-MASTOID 
 
 GLAND (internal 
 group) 
 
 SUBHYOID GLAND 
 
 Fig. 492. — Deep cervical chain. (Poirier and Charpy.) 
 
 number and lie along the external jugular vein upon the outer surface of the deep 
 cervical fascia, each gland occupying a depression in the fascia. The sterno- 
 cleido-mastoid muscle is beneath them. They are usually gathered in a group 
 a little below the parotid gland, but sometimes extend to the middle of the vein. 
 They receive vessels from the occipital, the posterior auricular, the parotid, and 
 the submaxillary lymph-glands, from the auricle, and from the skin and subcu- 
 taneous structures of the neck. From them lymphatic vessels pass to the upper 
 deep cervical and to the lower deep cervical glands. 
 
 The Superficial Anterior Cervical Glands. — The superficial anterior cervical glands 
 lie along the anterior jugular vein and from them vessels pass to the deep cervical 
 glands. 
 
 The Submaxillary or Lateral Suprahyoid Glands (lymphoglandulae submaxil- 
 lares) (Figs. 488, 489, and 493), — The submaxillary glands are in the submaxil- 
 lary triangle beneath the deep fascia. They number three to six; are embedded 
 in the superficial surface of the sheath of the submaxillary gland, but are not found 
 within the sheath. Occasionally one or two are found in the deep portion of the 
 sheath toward the floor of the mouth. The middle gland of Stahr is situated at 
 the point where the submaxillary group is crossed by the facial artery. This is 
 the largest gland of the group. The submaxillary glands receive vessels from the 
 
THE LYMPHATIC GLANDS OF THE NECK 
 
 785 
 
 "nose, the cheek, the upper Hp, and the external part of the lower lip, almost 
 the whole of the gums, and the anterior third of the lateral border of the tongue."^ 
 They also obtain lymph from the floor of the mouth and from the sublingual and 
 submaxillary salivary glands.^ They send vessels to the jugular and to the upper 
 deep cervical glands. 
 
 The Submental or Median Suprahyoid Glands (Figs. 4S8, 491, and 493).— 
 There are usually two glands situated between the anterior bellies of the two 
 digastric muscles and upon the Mylo-hyoid muscle. They receive lymph from the 
 cutaneous surface of the chin, from the cutaneous and mucous surfaces of the 
 
 YGOMATIC 
 
 SUPERFICIAL 
 PAROTID 
 
 Fig. 493.— The lymphatic glands and vessels of the head and neck. The deep lymphatics are colored blue 
 and the superficial black. In each set the afferent vessels are shown in continuous lines; the efferent and inter- 
 glandular ves.seis are represented by dotted lines. (Cunningham.) 
 
 central portion of the lower lip, from the central portion of the gums, from the 
 floor of the mouth, and from the tip of the tongue. They send some vessels to 
 the submaxillary lymph-glands, and frequently a gland is interposed on the anterior 
 belly of the Digastric muscle. They send other vessels to the upper deep cervical 
 glands. 
 
 The Retro-pharyngeal or Post-pharyngeal Glands (Fig. 494).— The retro- 
 pharyngeal glands are placed between the upper lateral portion of the posterior 
 part of the pharynx and the first two cervical vertebrae. Leaf tells us that, as a 
 
 ' The Lymphatics. By G. Delamare, P. Poirier, and B. Cuneo. Translated and edited by Cecil H. Leaf. 
 ^ Cunningham's Text-book of Anatomy. 
 
 50 
 
786 
 
 THE LYMPHATIC SYSTEM 
 
 rule, there is but one gland on each side, though two may be present. The retro- 
 pharyngeal glands lie upon the Rectus capitis anticus major muscle, which sepa- 
 rates them from the vertebrae. They receive vessels from the muscles and fascia 
 in front of the vertebrse, from the nasal fossae and accessory cavities, from the naso- 
 pharynx and Eustachian tube, and possibly from the cavity of the tympanum. 
 They send vessels to the upper deep cervical glands. 
 
 The Deep Cervical, Carotid, or Sterno-mastoid Glands (hjmphoglandulae 
 cervicales profundae) (Figs. 488, 489, 491, 492, 493, and 494).— The deep cervical 
 glands are divided into the upper deep cervical and the lower deep cervical, and are 
 associated with certain accessory glands, including the jugular and superficial anterior 
 cervical, which have been discussed under the head of superficial cervical glands; 
 and the anterior deep cervical and the recurrent glands, which have not yet been 
 studied. The deep cervical chain extends from the apex of the mastoid process 
 of the temporal bone to the junction of the internal jugular and subclavian veins. 
 
 LYMPHATICS 
 OF PHARYNX 
 
 INTERRUPTING 
 
 GLANDULAR 
 
 NODULE 
 
 GLAND OF 
 
 DEEP CERVICAL 
 
 CHAIN 
 
 EFFERENT 
 
 VESSEL OF 
 
 RETRO- PHARYNGEAL 
 
 GLANDS 
 
 Fig. 494. — The retro-pharyngeal glands. (Poirier and Charpy.) 
 
 The Upper Deep Cervical or Substerno -mastoid Glands (lymphoglandulae cervi- 
 cales profundae superiores). — The upper deep cervical glands extend from the" 
 tip of the mastoid process of the temporal bone to about the region where the 
 common carotid artery is crossed by the Omo-hyoid muscle. One group, 
 the external group, is placed external and posterior to the internal jugular vein. 
 The glands are small and numerous, are embedded in the fatty tissue about the 
 nerves from the deep cervical plexus, and at the posterior margin of the Sterno- 
 cleido-mastoid muscle constitute a continuous mass passing to join the subclavian 
 glands. Another group, known as the internal group or the internal jugular 
 glands, lie directly upon or close by the outer border of the internal jugular vein. 
 This group forms a chain along the internal jugular vein, and the glands are 
 of larger size than those of the external group. Some glands of this group 
 are beneath the vein. The glands of the internal jugular group communicate 
 freely with each other and with the external group. The external group receives 
 lymph-vessels from the posterior auricular, occipital, and external jugular glands, 
 from the occipital region of the scalp, from the auricle, and from the skin, sub- 
 cutaneous tissue, and muscles of the upper portion of the neck.* The internal 
 group receives lymph-vessels from the retro-pharyngeal, parotid, subparotid, sub- 
 
 1 The Lymphatics. By G. Delamare, P. Poirier, and B. CunSo. Translated and edited by Cecil H. Leaf. 
 
THE LYMPHATIC VESSELS OF THE NECK 'J^'J 
 
 maxillary, and submental glands, the anterior cervical glands (superficial and 
 deep), and the recurrent glands, and from the tongue, naso-pharynx, larynx, soft 
 palate, roof of the mouth, oesophagus (cervical portion), nasal fossfe, trachea 
 (cervical portion), and the thyroid gland.^ The external group terminates in 
 the supraclavicular glands. The internal jugular group terminates in the 
 jugular trunk, which, on the right side, helps to form the right lymphatic duct 
 or empties directly into the junction of the internal jugular and subclavian veins, 
 and on the left side empties directly into the venous junction or into the thoracic 
 duct. 
 
 The Lower Deep Cervical or Supraclaviculax Glands (lymphoglandulae cervicales 
 projundae injeriores). — The lower deep cervical glands lie along the internal 
 jugular vein in the lower part of its course. They receive lymph-vessels 
 from the superficial cervical glands, the upper deep cervical glands, the 
 axillary glands, the accessory chain, the occipital region of the scalp, the skin of 
 the neck, the lower prevertebral muscles, the skin of the pectoral and mammary 
 regions, and the skin of the arm. The supraclavicular glands send vessels which 
 unite with the vessels of the upper deep glands to form the jugular lymphatic 
 trunk. The jugular trunk on the right side may empty directly into the junc- 
 tion of the internal jugular and subclavian veins or may unite with the subclavian 
 trunk to form the right lymphatic duct. On the left side it may empty into the 
 thoracic duct or directly into the venous junction. 
 
 Accessory Chains to the Deep Cervical Glands. — The accessory chains to the deep 
 cervical glands are: 1. The external jugular glands (p. 784). 2. The superficial 
 anterior cervical (p. 784). 3. The prelaryngeal or infralaryngeal glands (Fig. 493) 
 between the Crico-thyroid muscles. They receive lymph from the trachea, larynx, 
 and thyroid gland, and send vessels to the pretracheal glands and to the upper 
 deep cervical glands. 4. The tracheal or pretracheal glands (Fig. 493) lie upon the 
 front of the trachea, receive vessels from the trachea, thyroid body, and prelaryngeal 
 glands, and send vessels to the lower deep cervical glands. Some anatomists speak 
 of the prelaryngeal and the pretracheal glands as the anterior deep cervical glands. 
 5. The recurrent glands lie on the sides of the oesophagus and trachea, by the recur- 
 rent laryngeal nerves. They receive vessels from the larynx, trachea, oesophagus, 
 and thyroid gland, and send vessels to the upper and lower deep cervical glands. 
 
 The Lymphatic Vessels of the Neck (Figs. 487, 491, 492, 493). 
 
 The superficial and deep cervical lymphatic vessels are continuations of those 
 already described on the cranium and face. After traversing the glands in those 
 regions, they pass through the chain of glands which lie along the sheath of the 
 carotid vessels, being joined by the lymphatics from the pharynx, oesophagus, 
 larynx, trachea, and thyroid gland. At the lower part of the neck, after receiving 
 some lymphatics from the thorax, they unite to form the jugular trunk (Fig. 486), 
 which often terminates, on the left side, in the thoracic duct, and on the right side, 
 in the right lymphatic duct, but which may on either side open directly into the vein. 
 
 Surgical Anatomy. — In secondary syphilis there is general enlargement of the lymphatic 
 glands, and in the posterior triangle of the neck the enlarged glands are distinctly palpable. The 
 occipital glands may enlarge because of inflammation or suppuration about the occipital region 
 of the scalp, and the posterior-auricular glands enlarge from inflammation or szippuration of the 
 temporal portion of the scalp, the external ear (except the lobule), and the external auditory meatus. 
 Otorrhxfa sometimes causes them to enlarge. 
 
 The cervical glands are very frequently the seat of tuberculous disease. This condition is 
 usually preceded by a lesion in those parts from which they receive their lymph. The lesion may 
 be tuberculous or inflammatory. If tuberculous it furnishes bacilli directly to the lymph. If 
 inflammatory it lessens tissue resistance and opens the portals to infection. The glands receive 
 
 1 The Lymphatics. By G. Delamare, P. Poirier, and B. Cun6o. Translated and edited by Cecil H. Leaf. 
 
788 THE LYMPHATIC SYSTEM 
 
 the lymph from the seat of primary disease and become tuberculous. It is very desirable, there- 
 fore, for the surgeon, in dealing with these cases, to possess a knowledge of the relation of the 
 respective groups of glands to the periphery. Some years ago Sir Frederick Treves prepared a 
 table to show to what glandular group lymph from each region is sent. The table is practically 
 as follows: 
 
 Scalp. — Posterior part = suboccipital and mastoid glands. Frontal and parietal portions = 
 parotid glands. 
 
 Lymphatic vessels from the scalp also enter the superficial cervical set of glands. 
 
 Skin of face and neck -= submaxillary, parotid, and superficial cervical glands. 
 
 External ear = superficial cervical glands. 
 
 Lower lip = submaxillary and suprahyoid glands. 
 
 Buccal cavity =^ submaxillary and upper set of deep cervical glands. 
 
 Gums of lower jaw = submaxillary glands. 
 
 Tongue. — Anterior portion = suprahyoid and submaxillary glands. Posterior portion = 
 upper set of deep cervical glands. 
 
 Tonsils and palate = upper set of deep cervical glands. 
 
 Pharynx. — Upper part =: parotid and retro-pharyngeal glands. Lower part = upper set of 
 deep cervical glands. 
 
 Larynx, orbit, and roof of mouth = upper set of deep cervical glands. 
 
 Nasal fossir = retropharyngeal glands, upper set of deep cervical glands. Some lymphatic 
 vessels from posterior part of the fossae enter the parotid glands. 
 
 Treves's table indicates the glands usually involved, but the seat of primary disease cannot in- 
 variably be affirmed from a knowledge of the seat of glandular involvement, because the course 
 of the lymphatic vessels is sometimes varied from that which usually maintains ; for instance, in 
 some cases lymphatics from the right side of the tongue pass to glands in the left side of the 
 neck. 
 
 Glands may enlarge directly because of primary inflammation, injury, or tumor, but usually 
 a glandular enlargement is secondary to a bacterial disease or to cancer involving the lymph- 
 vessels which come to the gland. The seat of disease may be distant. Disease of the nasal 
 fossae may cause retropharyngeal abscess or enlargement of the submaxillary glands. Cancer 
 of the breast, stomach, or oesophagus may be followed by disease of the cervical glands. Dis- 
 ease of the teeth, tongue, gums, floor of the mouth, and alveolar processes may cause enlarge- 
 ment of the submaxillary and other glands, and disease of the tonsil may lead to enlargement 
 of the glands at the angle of the jaw. 
 
 The modern radical surgery of cancer depends on a knowledge of these glandular relations, 
 and consists in thoroughly removing the growth and also the associated lymphatic glands, and, 
 when possible, the lymph-vessels running from the tumor to the glands. The lower deep cer- 
 vical glands occasionally enlarge secondarily to malignant growths of the abdomen or medias- 
 tinum, but this is not due to a direct flow of lymph, as the mediastinal glands do not send ves- 
 sels to the supraclavicular glands. It is due to blocking of lymphatic vessels and reversal of 
 the lymph-stream, so that lymph containing cancerous cells regurgitates. 
 
 A retropharyngeal abscess begins to the side of the pharynx. It enlarges toward the centre 
 rather than from it, because the constrictions of the pharynx limit the outward progress of the 
 pus. 
 
 The glands within the parotid salivary gland not unusually become tuberculous, and the 
 surgeon may be led to believe that the salivary gland is the seat of primary disease. 
 
 Sometimes, though seldom, after the extensive removal of lymph-glands the region drained 
 by their tributaries becomes the seat of persistent hard oedema {lymph a'dema). It used to be 
 thought that wounds of the thoracic duct were of necessity fatal, but it is now known that, unless 
 close to the vein, they are seldon even very dangerous. It may be possible to suture a partly 
 divided duct.' In an unsutured wound of the duct recovery follows if a collateral lymphatic 
 circulation is established.'^ 
 
 THE LYMPHATICS OF THE UPPER EXTREMITY. 
 
 The Lymphatic Glands of the Upper Extremity. 
 
 The lymphatic glands of the upper extremity are divided into two sets, super- 
 ficial and deep. 
 
 Superficial Lymphatic Glands (Figs. 495 and 503).— The superficial lymphatic 
 glands of the upper extremity are few in number and small in size. They lie in the 
 
 ' Dudley P. Allen's case. See Allen and Briggs, in American Medicine. September 21. 1901. 
 ^ Harvey Gushing, Annals of Surgery, .June, 1898. 
 
THE LYMPHATIC GLANDS OF THE UPPER EXTREMITY 789 
 
 subcutaneous tissue. They are not receiving depots of great areas, but interrupt 
 lymphatic vessels here and there. The glands in the axilla receive all of the 
 lymphatic vessels, superficial and deep. There may be three sets of superficial 
 glands. 
 
 One set, the ante-cubital glands, lies in front of the elbow. These glands are 
 often absent. When these glands are present they receive vessels from the anterior 
 portion of the forearm and the middle of the palm. The vessels from them pass 
 upward along the front and iimer aspect of the arm. 
 
 Axillary glands, 
 
 Fig. 495. — The superficial lymphatics and glands of the upper extremity. 
 
 Another superficial gland lies above the internal condyle. It is the supratrochlear 
 or supraepitrochlear gland or group of glands. There is usually but one gland, but 
 there may be two or more. It receives vessels from the inner portion of the hand, 
 the three inner fingers, and the inner portion of the forearm, but, because of free 
 anastomoses, also may receive lymph from any portion of the hand and forearm. 
 Lymph-vessels from the supratrochlear gland pass up along the basilic vein to 
 the axillary glands. 
 
790 
 
 THE LYMPHATIC SYSTEM 
 
 There are sometimes several small glands by the cephalic vein in the groove 
 between the Deltoid and great Pectoral muscles. These are called infraclavicular 
 glands. The lymph-tract from the infraclavicular glands does not terminate in 
 the axillary glands, but ends in the subclavian glands. 
 
 The Deep Lymphatic Glands of the Upper Extremity or the Axillary Glands 
 {lymphoglandulae axillares) (Figs. 495, 496, 497, 498, and 503). — The chief deep 
 (ylands are situated adjacent to the axillary vessels. There are also a few small 
 glands along the radial, ulnar, and brachial arteries which receive deep lymphatics 
 from bones, muscles, and ligaments, and send lymphatics to the axillary glands. 
 The axillary glands number from fifteen to thirty-five in each axilla. They are 
 embedded in the axillary fat and receive the lymphatic vessels from the upper 
 extremity, from the skin of the upper portion of the chest, from the Pectoral 
 muscles, and from the mammary gland. The following division of the axillary 
 glands is made by Poirier, Cun^o, and Delamare:^ 1. An external group, the 
 
 DELTA-PECTORAL HUMERAL CHAIN 
 
 Y LYMPHATIC 
 IN SUB- 
 G LAN OS 
 
 RY COL- 
 TRUNKS 
 
 THORACIC 
 CHAIN 
 
 CUTANEOUS COLLECTING 
 
 TRUNK FROM THE 
 
 THORACIC WALL 
 
 SUBAREOLAR 
 PLEXUS 
 
 Fig. 496. 
 
 CUTANEOUS COL- '^ -%jr ■ ^COLLECTING TRUNKS 
 
 LECTENG TRUNKS \ V PASSI NG TO I NTE RNAL 
 
 MAMMARY GLANDS 
 
 Axillary glands and lymphatics of the breast. 
 
 humeral chain, lying on the inner surface of the vessels and nerves, particularly the 
 axillary vein, to the sheath of which they are adherent. Occasionally one or several 
 of these glands are found beneath the vein. Some of the vessels from these glands 
 pass into the central group of lymph-nodes; others enter the subclavian glands; 
 others pass above the clavicle and terminate in glands situated in that region. 2. 
 An anterior group, the thoracic chain, called also the pectoral glands. One mass of this 
 chain, the supero-intemal, is situated in the second or third intercostal space in 
 front of the long thoracic artery and beneath the lower edge of the great Pectoral 
 muscle. Another mass, the infero-extemal, is situated in the fourth and fifth 
 intercostal spaces along the course of the long thoracic artery. The vessels from 
 this chain end in the central group, and some few of them in the subclavian glands. 
 3. A posterior group, the scapular chain, lying along the dorsalis scapula? artery in the 
 groove between the Teres major and the Subscapularis muscles. They send vessels 
 
 ' The Lymphatics. Translated and edited by Cecil H. Leaf. 
 
THE LYMPHATIC GLANDS OF THE UPPER EXTREMITY 791 
 
 to the humeral and central chains. 4. A central group, the intermediate glands, placed 
 near the base of the axilla, between the previously described chains. Their efferent 
 
 
 Fig. 497. — Lymphatics of the antero-lateral portion of the thorax. (Sappey.) 
 
 vessels end in the subclavian glands. The glands of the central group in many indi- 
 viduals protrude through the opening in the axillary fascia known as the foramen 
 
 SUPRA 
 CLAVICULAR 
 
 SUBCLAVIAN 
 
 HUMERAL 
 
 SCAPULAR 
 CHAIN 
 
 TRAL GROUP 
 
 RO-INTERNAL 
 ION OF 
 ACIC CHAIN 
 
 O-EXTERNAL 
 ON OF 
 CIC CHAIN 
 
 Fig. 498. — Scheme of the axillary glands. The dotted line indicates the position of the clavicle. 
 
 (Poirier and Charpy.) 
 
 of Langer (Fig. 313). 5. A subclavian group, situated above the upper margin 
 of the lesser Pectoral muscle. Most of them are internal to the axillary vein, 
 
792 
 
 THE LYMPHATIC SYSTEM 
 
 " between this vein and the first digitation of the Serratus magnus."^ The humeral 
 chain and the thoracic chain cime together and form the subclavian group of 
 glands situated at the apex of the axilla. From the axillary glantis come many 
 vessels which, by anastomosing, form the infraclavicular plexus, they then unite 
 into a trunk, the subclavian trunk, which courses between the subclavian vein and 
 Subclavius muscle. On the right side it empties into the junction of the internal 
 jugular and subclavian vein or unites with the jugular trunk to form the right 
 lymphatic duct. On the left side it may empty into the venous junction or into 
 the thoracic duct. 
 
 The Lymphatic Vessels of the Upper Extremity (Figs. 495, 496, 497, 498, 499). 
 
 The lymphatic vessels of the upper extremity are divided into the superficial 
 and the deep. 
 
 The Superficial Lymphatic Vessels of the Upper Extremity. — The superficial 
 vessels begin as plexuses in the skin and form vessels which ascend in the sub- 
 cutaneous tissue. These plexuses are particularly plentiful in the palm and 
 palmar surface of the digits (Fig. 499). On each side of each finger two lymph- 
 
 FiG. 499. — Superficial lymphatics of the digits and of the dorsal aspect of the hand. (Cunningham.) 
 
 vessels are formed; they ascend toward the hand, cross the dorsum, and anas- 
 tomose frequently with each other. The vessels from the dorsum of the hand 
 join the lymph-vessels of the forearm, which ascend chiefly along the superficial 
 veins. The lymph-vessels which ascend with the superficial ulnar vein pass into 
 the supratrochlear gland. The vessels which accompany the median veins pass 
 into the ante-cubital or supratrochlear glands. Some of the lymph-vessels on 
 the radial side of the forearm run up along the cephalic vein. All the other 
 lymph-vessels of the upper extremity pass direct to the axillary glands. In the 
 forearm there are about thirty vessels, in the middle of the arm there are from 
 fifteen to eighteen (Sappey). 
 
 The Deep Lymphatic Vessels of the Upper Extremity.— The deep lymph- 
 vessels convey the lymph from bone, periosteum, muscle, ligament, etc. They pass 
 up the limb with the chief vessels, there usually being two trunks to each artery. 
 In the arm there are two or three vessels. Some few vessels terminate in the 
 small glands along the radial, ulnar, and brachial arteries, but most of them pass 
 directly to the axillary glands. 
 
 Surgical Anatomy. — In malignant diseases, or other affections implicating the upper part of 
 the back and shoulder, the front of the chest and mamma, the upper part of the front and side 
 of the abdomen, or the hand, forearm, or arm, the axillary glands are liable to be found enlarged. 
 
 In secondary syphilis the supratrochlear gland is found to be enlarged. This gland is sub- 
 cutaneous and readily palpable when enlarged. Normal axillary glands cannot be palpated. 
 
 ' The Lymphatics. By Poirier, Cuneo, and Delamare. Translated and edited by Cecil H. Leaf. 
 
THE LYMPHATIC GLAND.S OF THE LOWER EXTREMITY 793 
 
 The axilla is a passage-way for structures between the neck and the upper extremity, and puru- 
 lent collections or tumors may extend from the neck into the axilla or from the axilla into the 
 neck. 
 
 The axillary glands are involved early in cases of cancer of the mammary gland, and later 
 the lower deep cervical glands are involved, and, as Snow has pointed out, regurgitation of 
 lymph containing cancer cells leads to retrosternal involvement and to secondary cancer of the 
 head of the humerus. In operating for cancer of the breast, follow the principle of Halsted and 
 remove the breast, the skin over it, the muscles and fascia, the lymph-vessels, and the axillary 
 glands in one piece. By this plan thorough removal is possible, and as lymph-vessels containing 
 carcinoma cells are not cut across, the wound is not grafted with malignant epithelial cells. Dis- 
 eased axillary glands are apt to adhere to the sheath of the vein. In removing cancerous glands, 
 always excise the sheath of the vein. 
 
 THE LYMPHATICS OF THE LOWER EXTREMITY. 
 
 The Ljrmphatic Glands of the Lower Extremity. 
 
 Tlie lymphatic glands of the lower extremity are divided into two sets, super- 
 ficial and deep. The superficial are confined to the inguinal i-egion, forming the 
 superficial inguinal lymphatic glands. 
 
 The Superficial Inguinal Lymphatic Glands (lymphoglandulae inguinales 
 superfciales) (Figs. 500,501, 502, and 503). — The superficial inguinal lymphatic 
 glands, placed immediately beneath the integument in Scarpa's triangle, are of 
 
 SUPERIOR 
 
 EXTERNAL 
 
 GROUP 
 
 SUPERIOR 
 
 INTERNAL 
 
 GROUP 
 
 INFERIOR 
 
 INTERNAL 
 
 GROUP 
 
 EXTERNAL 
 GROUP 
 
 Fig. 500. — Superficial inguinal glands. Cribriform fascia has been removed so as to expose the femoral 
 
 vessels. (Poirier and Charpy.) 
 
 large size, and vary in number from ten to twenty. It is customary to divide 
 these glands into groups according to the region in which they are found. The 
 following division is suggested by Poirier, Cuneo, and Delamare:^ A horizontal 
 line carried through the saphenous opening divides the glands into two groups, 
 a superior group and an inferior group. A vertical line through the saphenous 
 opening divides each of the two groups into two secondary groups, an external and 
 an internal group. We thus have an external and superior group, and internal and 
 superior group, an external and inferior group, and an internal and inferior group. 
 
 1 The Lymphatics. Translated and edited by Cecil H. Leaf. 
 
794 
 
 THE LYMPHATIC SYSTEM 
 
 Directly in the saphenous opening there are often several glands constituting a 
 central group. 
 
 Leaf joints out that a gland usually exists near the saphenous opening, which 
 is interposed between the superficial inguinal and deep inguinal glands. The 
 superior group of glands, sometimes called the oblique group, is so placed that the 
 glands lie with a certain regularity along and below Poupart's ligament, the long 
 axis of each gland corresponding with the direction of the ligament. It is now 
 known that each group of the superficial glands does not receive with regularity 
 the lymph from and only from a definite and accurately determined area. Hence, it 
 is not possible, as was once taught, to determine with certainty the exact situation 
 of a lesion by the group of superficial glands involved. The superficial inguinal 
 glands receive vessels from the skin of the lower extremity, gluteal region, peri- 
 
 FiG. 501. — Glands of the inguinal region with the afferent and efferent lymphatics. (Poirier and Charpy.) 
 
 neum, abdominal wall, scrotum, anus, and from the prepuce of the clitoris and 
 penis. Occasionally, though not normally, they receive vessels from the glans 
 penis and glans clitoris. The superficial glands send vessels to the deep inguinal 
 glands and to the external iliac glands, and these vessels penetrate the femoral 
 sheath. The vessels which go to the iliac glands ascend with the femoral vessels. 
 Leaf ^ figures some of the efferent vessels from these glands as terminating directly 
 in the veins of this region. 
 
 Surgical Anatomy. — The superficial inguinal glands frequently become enlarged in diseases 
 implicating the parts from which their lymphatics originate. Thus, in malignant or syphilitic 
 affections of the prepuce and penis, or of the labia majora in the female, in cancer scroti, in 
 abscess in the perinseum, and in other diseases affecting the integument and superficial structures 
 
 1 The Surgical Anatomy of the Lymphatic Glands, 1898. 
 
THE LYMPHATIC GLANDS OF THE LOWER EXTREMITY 795 
 
 in those parts, or the subumbihcal part of the 
 abdominal wall or the gluteal region, the upper 
 chain of glands is almost invariably enlarged, the 
 lower chain being implicated in diseases affecting 
 the lower limb. 
 
 The Deep Lymphatic Glands of the 
 Lower Extremity. — The tleep glands are 
 the inguinal, anterior tibial, popliteal, gluteal, 
 and ischiatic. 
 
 The Deep Inguinal or Deep Femoral 
 Lymphatic Glands (lymphoglandidae in- 
 guinalcs profundae) (Fig. 503). — The deep 
 inguinal lymphatic glands are beneath the 
 deep fascia. There are only two or three of 
 them, and they lie to the inner side of the 
 femoral vein, the upper gland being in the 
 crural canal and projecting into the pelvis. 
 It is called the gland of Cloquet or the 
 gland of RosenmuUer. The deep inguinal 
 glands receive vessels from the superficial 
 inguinal glands, deep lymphatics from 
 along the femoral vessels, and vessels from 
 the glans penis or clitoris. They send 
 vessels to the ilio-pelvic glands. 
 
 The Anterior Tibial Gland (lympho- 
 glandula tibialis anterior) (Fig. 503).— The 
 anterior tibial gland is not constant in its 
 existence. It is generally found by the 
 side of the anterior tibial artery, upon the 
 interosseous membrane at the upper part 
 of the leg. Occasionally, two glands are 
 found in this situation. It receives a deep 
 anterior tibial lymphatic trunk and sends 
 off a vessel to the popliteal glands. 
 
 The Popliteal Glands (lymphoglandidae 
 popliteae). — Tlie popliteal glands are em- 
 bedded in the cellular tissue and fat of 
 the popliteal space and about the peroneal 
 vessels The juxta-articular gland receives 
 lymph-vessels from the knee-joint. The 
 popliteal glands send vessels to the super- 
 ficial and deep inguinal glands. 
 
 The popliteal glands are divided into 
 three groups •} 1 . A gland external to the 
 termination of the external saphenous 
 vein, the external saphenous gland. 2. A 
 middle group of three or four glands on 
 the sides of the popliteal vessels. The 
 inferior glands of this group are the inter- 
 condyloid glands of Leaf. The superior 
 glands are the supracondyloid glands of 
 Leaf. 3. A gland adherent to the posterior 
 
 Superficial 
 i7iguinal 
 glands. 
 
 vm 
 
 ' The Lymphatics. By Poirier, Cun^o, and Delamare. 
 Translated and edited by Cecil H. Leaf. 
 
 Fio. 502. — The superficial lymphatics and glands 
 of the lower extremity. 
 
796 
 
 THE LYMPHATIC SYSTEM 
 
 ligament of the knee-joint, the juxta-articular gland of Poirier and Cun6o. Tlie ex- 
 ternal saphenous gland receives vessels which ascend along the external saphenous 
 
 INTRACLAVIC 
 
 EXTERNAL AXILLA 
 ANTERIOR AXILLA 
 
 POSTERIOR AXILLA 
 
 NFRACLAVICULAR 
 
 PERFICIAL FEMORAL 
 EP FEMORAL 
 ETHRAL 
 
 Fig. 503. — Superficial lymphatic vessel.? of the trunk, and the lymphatic glands and vessel.*, superficial and 
 deep, of the limbs (diagrammatic). Afferent vessels are represented by continuous lines; efferent and mter- 
 glandular vessels by dotted lines. (Cunningham.) 
 
THE ILIAC OB ILIO -PELVIC GLANDS 797 
 
 vein. The middle group receives vessels from the anterior tibial glands and deep 
 lymphatic vessels which ascend with the posterior tibial. 
 
 The Gluteal and Ischiatic Glands. — The gluteal and ischiatic glands are placed, 
 the former above, the latter below, the Pyriformis muscle, resting on their corre- 
 sponding blood-vessels as they pass through the great sacro-sciatic foramen. 
 
 The Lymphatic Vessels of the Lower Extremity (Figs. 502, 503). 
 
 The lymphatic vessels of the lower extremity, like the veins, may be divided 
 into two sets, superficial and deep. 
 
 The Superficial Lymphatic Vessels of the Lower Extremity. — The superficial 
 lymphatic vessels are placed beneath the integument in the superficial fascia, and 
 are divisible into three sets: trunks which follow the course of the internal 
 saphenous vein, trunks which accompany the external saphenous vein, and 
 trunks from the <jluteal region. 1. Trunks which follow the course of the 
 internal saphenous vein arise from a plexus on the dorsum of the foot, which 
 plexus obtains lymphatics from all the toes, the sole, and both borders of the foot. 
 The internal trunks, three or four in number, pass to the superficial inguinal 
 glands. Theexternal trunks run upward and inward and end in the internal trunks. 
 2. The trunks which follow the external saphenous vein number two or three, and 
 they take origin from the heel and from the posterior half of the outer edge of 
 the foot. They empty into the superficial inguinal glands. 3. The lymph-trunks 
 from the gluteal region join vessels from the anus and enter the superficial 
 inguinal glands. 
 
 The Deep Lymphatic Vessels of the Lower Extremity.— The deep lymphatic 
 vessels of the lower extremity are few in number and accompany the deep blood- 
 vessels. In the leg they consist of three sets, the anterior tibial, peroneal, and 
 posterior tibial, which accompany the corresponding blood-vessels, two or three 
 to each artery; they ascend with the blood-vessels and enter the lymphatic glands 
 in the popliteal space; the efferent vessels from these glands accompany the femoral 
 vein and join the deep inguinal glands; from these glands vessels pass beneath Pou- 
 part's ligament and communicate with the chain of glands surrounding the exter- 
 nal iliac vessels. The deep lymphatic vessels of the gluteal and ischiatic regions 
 follow the course of the blood-vessels, and join the gluteal and ischiatic glands at 
 the great sacro-sciatic foramen. 
 
 THE LYMPHATICS OF THE PELVIS AND ABDOMEN. 
 
 The lymphatics of the pelvis and abdomen constitute a continuous chain, but 
 for convenience of study it is customary to divide them into two groups, which 
 we call, with Poirier and Cuneo,* the ilio-pelvic glands and the abdomino-aortic 
 glands; the first group being below and the second above the level of the bifurca- 
 tion of the aorta into the two common iliac arteries. 
 
 The Iliac or Ilio-pelvic Glands (Lymphoglandulae Iliacae) (Figs. 504, 505). 
 
 The ilio-pelvic glands are at the level of the inlet of or in the cavity of the 
 pelvis. They follow the course of the blood-vessels and are divisible into the 
 external iliac, the internal iliac, and the common iliac chains. 
 
 The External Hiac Glands. — The external iliac glands form chains around 
 the external iliac vessels. There are three chains of these glands. An external 
 chain of three or four glands lies between the artery and the Psoas muscle. 
 
 ' Treatise on Human Anatomy. ^'' 
 
798 
 
 THE LYMPHATIC SYSTEM 
 
 The lowest gland of the external chain is called by Poirier and Cun^o the external 
 retro-crural gland (Fig. 504). A middle chain of three glands lies upon the front 
 surface of the external iliac vein. The lowest gland of this group is called by 
 Poirier and Cun^o the middle retro-crural gland. An internal chain of three or 
 four glands is placed to the inner side of the external iliac vein. The lowest gland 
 of this chain is called the internal retro-crural gland, and is close to the upper gland 
 of the deep inguinal chain, the gland of Cloquet. The obturator gland belongs to 
 the inner chain of external iliac glands. The external iliac glands receive vessels 
 from the superficial and deep iliac glands, from the glans penis or glans clitoris, 
 
 LEFT JUXTA 
 
 PROMONTORY 
 
 COMMON ILIAC 
 
 (middle group) 
 
 EXTERNAL ILIAC 
 
 (external chain) 
 
 COMMON ILIAC 
 ZXTERNAL ILIAI 
 
 EXTERNAL ILIA( 
 
 (middle chain) 
 
 OBTURATOR 
 NERVE 
 OBTURATOR 
 ARTERY 
 
 EXTERNAL 
 RETROCRURAL 
 
 OBTURATOR 
 ARTERY 
 
 OBTURATOR 
 GLAND 
 
 Fig. 504. — Ilio-pelvic glands. (Poirier and Charpy.) 
 
 deep lymphatics from the umbilicus and lower part of the belly wall, vessels from the 
 superior portion of the vagina, the uterine neck, the prostate gland, the bladder, 
 the membranous portion of the urethra, and the internal iliac glands, and the 
 obturator gland receives deep lymph-vessels from along the course of the obtu- 
 rator vessels. The external iliac glands send vessels direct to the common iliac 
 glands and also lymphatics to join vessels from the internal iliac glands on their 
 way to the common iliac group. The glands along the deep epigastric artery 
 and those along the deep circumflex iliac artery are accessory chains to the main 
 group of external iliac glands. 
 
THE ABDOMINO- AORTIC GLANDS 
 
 799 
 
 The Internal Iliac or Hypogastric Glands.— The internal iliac glands are 
 placed along the internal iliac artery and its branches. The gland on the middle 
 hsemorrhoidal artery is called the middle hsemorrhoidal gland. The lateral sacral 
 gland is on the lateral sacral artery. The internal iliac glands receive lymph from 
 the pelvic viscera, perinieum, and penile portion of the urethra, deep tissues of the 
 posterior portion of the thigh, and from the buttocks. They send vessels to the 
 common iliac glands and also to the external iliac g-lands. 
 
 The Common Hiac Glands. — The common iliac glands are found about the 
 common iliac artery and are divided into an external group, which lies upon the 
 
 INTERPELVIC 
 GLUTEAL 
 
 PROMONTORY 
 
 EXTERNAL ILIAC 
 
 (middle chain) 
 
 EXTERNAL ILIAC 
 
 (middle chain) 
 
 EXTERNAL ILIAC 
 
 (external chain) 
 
 RETROCRURAL 
 
 EXTERNAL 
 
 RETROCRURAL- 
 
 INTERNAL 
 
 LYMPHATICS 
 
 OF BLADDER 
 
 LYMPHATIC FROM 
 
 CLANS PENIS 
 
 LYMPHATICS 
 OF BLADDER 
 
 J_HYPOGASTBIC 
 
 HYPOGASTRIC 
 SATELLITE TRUNK 
 OF INTERNAL 
 PUDIC VESSELS 
 TRUNK OF 
 MIDDLE HEMOR- 
 RHOIDAL VESSELS 
 
 PROSTATIC COL- 
 LECTING TRUNK 
 
 tETHRAL COL- 
 LECTING TRUNKS 
 
 LYMPHATIC GLANDULAR NODULE 
 IN FRONT OF SYMPHYSIS 
 
 PROSTATIC COL- 
 LECTING TRUNK 
 
 Fig. 505. — Ilio-pelvic gland.s (lateral view.) (Poirier and Charpy.) 
 
 inner edge of the Psoas muscle; a middle group, behind the artery, and an internal 
 group, which lies upon the front of the body of the fifth lumbar vertebra or upon 
 the sacro-vertebral junction. They receive vessels from the external and internal 
 iliac glands and from the pelvic viscera, the vessels from the pelvic viscera ascend- 
 nig to the promontory of the sacrum and containing perhaps, here and there, 
 mterrupting glands, known as sacral glands {lymphoglandulae sacrales) (Fig. 511). 
 They also receive lymph-vessels from the lumbo-sacral region. They send vessels 
 to the aortic glands. Some anatomists place the common ihac glands and the 
 glands al)out the lower portion of the aorta and vena cava in a group called the 
 lumbar glands {lymphoglandulae lumhales) (F\g. 511). 
 
 The Abdomino-aortic Glands (Figs. 484, 511). 
 
 The abdomino-aortic glands are placed about the abdominal aorta. There are 
 twenty-five or thirty of them. They are divided by Poirier, Cun^o, and Delamare^ 
 
 ' The Lymphatics. Translated and edited by Cecil H. Leaf. 
 
800 THE LYMPHATIC SYSTEM 
 
 into the right and left juxta-aortic glands, the retro-aortic glands, and the pre-aortic 
 glands. 
 
 The Right Juxta-aortic Glands. — The right juxta-aortic glands are grouped 
 in front of and behind the inferior vena cava, the posterior glands lying upon the 
 Psoas muscle and the adjacent pillar of the Diaphragm. They receive lymph- 
 vessels from the right common iliac glands, from the right testicle or the right 
 half of the uterus, and the right tube, ovary, broad ligament, the right kidney 
 and suprarenal capsule, and also lymph-vessels which pass along the lumbar 
 arteries. They send vessels to the pre-aortic and the retro-aortic glands and the 
 receptaculum chyli. 
 
 The Left Juxta-aortic Glands. — The left juxta-aortic glands lie by the side of 
 the abdominal aorta, upon the Psoas muscle, and the left pillar of the Diaphragm. 
 They receive tributaries from the left side corresponding to those received by 
 the glands of the right side, and also send out corresponding efferent vessels, and 
 several additional vessels which pass through the left pillar of the Diaphragm and 
 empty into the thoracic duct. 
 
 The Retro-aortic Glands. — The retro-aortic glands are placed beneath the 
 receptaculum chyli and in front of the bodies of the fourth and fifth lumbar ver- 
 tebrae. They receive lymph-vessels from both juxta-aortic groups, and also from 
 the pre-aortic glands, and they send vessels to the receptaculum chyli. 
 
 The Pre-aortic Glands. — The pre-aortic glands lie upon the front of the aorta, 
 and in most subjects are divisible into three groups: an inferior, lying at the origin 
 of the inferior mesenteric artery; a middle, at the origin of the superior mesenteric 
 artery, and a superior, about the coeliac axis, the coeliac glands (lymphoglandulae 
 coeliacae). Glands which are found along the course of all the branches of the 
 abdominal aorta empty into and belong to the group of pre-aortic glands. The 
 pre-aortic glands receive vessels from the juxta-aortic glands and from all the 
 glands along the mesenteric vessels and the coeliac axis and its branches, 
 and receive lymph from the stomach, intestines, liver, pancreas, and spleen. 
 They anastomose with each other and send vessels to the retro-aortic glands and 
 to the receptaculum chyli. Instead of the glands terminating in the receptaculum 
 by separate vessels, the vessels may unite and form a common trunk, the intes- 
 tinal trunk (truncus intestinalis) , which runs along with the common trunk from 
 the juxta-aortic glands, and empties into the receptaculum (Fig. 484). 
 
 1 . The Glands along the Mesenteric Arteries {lymphoglandulae mesentericae) receive 
 the lymph from the colon, csecum, appendix, ileum, jejunum, duodenum, and 
 perhaps also some from the stomach. 
 
 2. The Glands Connected with the Coeliac Axis and its Branches. — There are three 
 groups of these glands: the gastric or coronary, the splenic, and the hepatic (in- 
 cluding those of the bile-ducts). 
 
 The Gastric Glands (lymphoglandulae gasiricae). — One group is situated in the 
 gastro-pancreatic fold; another group is connected with the lesser curvature of the 
 stomach (Fig. 508) . Some of them are in the lesser omentum close to insertion of 
 the thicker part upon the stomach, and lie near the ascending branches of the gastric 
 artery, that is to say, upon the vertical portion of the lesser curvature. Others lie 
 within the lesser omentum and accompany the descending branches of the gas- 
 tric artery, and particularly gather near the point where the gastric artery comes 
 toward the stomach wall. The gastric glands receive lymph from most of the 
 stomach. They send lymph to the upper group of pre-aortic glands, the coeliac 
 glands. 
 
 The Splenic Glands {lymphoglandulae pancreaticolienales) . — ^The splenic glands 
 accompany the splenic artery and lie upon the posterior surface of the spleen, 
 between the spleen and pancreas. They receive lymph from the fundus of the 
 stomach, from the spleen, and from the pancreas, and send it to the coeliac glands. 
 
THE LYMPHATIC VESSELS OF THE ABDOMEN AND PELVIS 801 
 
 The Hepatic Glands (lympJwglatidulae hepaticae). — These glands lie along the 
 hepatic artery, some on the level of the floor of the foramen of Winslow, others by 
 the left side of the portal vein.^ The authors previously quoted point out that there 
 is a secondary chain of hepatic glands about the right gastro-epiploic artery, the 
 gastro -epiploic chain, and that this comprises a subpyloric group and a retro-pyloric 
 group. The subpyloric group (Fig. 508) is placed in the great omentum below the 
 pylorus, and is usually distinctly separated from it. The retro-pyloric group is not 
 constant. It is placed along the gastro-duodenalis artery back of the pylorus. 
 There is also a group of glands, secondary to the hepatic glands, to the right of 
 or posterior to the cystic duct and the common bile-ducts. The hepatic glands 
 proper receive lymph from the liver and send it to the coeliac glands. The 
 subpyloric glands receive lymph from the inferior portion of the stomach and 
 from the superior portion of the great omentum. They send lymph to the hepatic 
 glands proper, the retro-pyloric glands, and sometimes also to the glands about 
 the superior mesenteric artery. The retro-pyloric glands receive lymph from the 
 suljpyloric glands, from the upper surface and from the posterior surface of 
 the pylorus, and from the duodenum. They send lymph to the hepatic glands 
 proper and sometimes to the glands along the superior mesenteric artery. The 
 glands along the gall-ducts empty into the hepatic glands proper. 
 
 The Lymphatic Vessels of the Abdomen and Pelvis. 
 
 The lymphatic vessels of the abdomen and pelvis may be divided into two sets, 
 superficial and deep. 
 The Superficial Lymphatic Vessels of the Walls of the Abdomen.— The 
 
 superficial lymphatic vessels of the walls of the abdomen follow the course of the 
 superficial blood-vessels. The superficial lymphatics are derived from the integu- 
 ment. Those of the lower part of the abdomen below the umbilicus follow the course 
 of the superficial epigastric vessels and converge to the superior group of the super- 
 ficial inguinal glands (Figs. 501 and 503). Those from the costal margins of the 
 abdomen terminate in the axillary glands (Fig. 497). The superficial lymphatics 
 from the sides of the lumbar part of the abdominal wall wind aroimd the crest of 
 the ilium, accompanying the superficial circumflex iHac vessels, to join the super- 
 ficial inguinal glands (Fig. 501). 
 
 The Superficial Lymphatic Vessels of the Gluteal Region. — The superficial lym- 
 phatic vessels of the gluteal region turn horizontally around the outer side of the 
 nates, and join the superficial inguinal glands. 
 
 The Superficial Lymphatic Vessels of the Scrotum and Perinaeum. — The superficial 
 lymphatic vessels of the scrotum and perinaium terminate in the superficial inguinal 
 glands. 
 
 The Superficial Lymphatic Vessels of the Penis. — The superficial lymphatic vessels 
 of the penis occupy the sides and dorsum of the organ, the latter receiving the 
 lymphatics from the prepuce ; they all converge to the superficial inguinal glands. 
 Lymph vessels from the glans penis empty into the deep inguinal and the external 
 iliac glands. 
 
 In the female the lymphatic vessels of the vulva and prepuce of the clitoris pass 
 to the superficial inguinal glands; those of the glans of the clitoris pass to the 
 deep inguinal and the external iliac glands. 
 
 The Deep Lymphatic Vessels of the Abdominal Wall. — The deep lymphatic 
 vessels of the abdominal wall take the course of the principal blood-vessels, and 
 arise from muscular or aponeurotic layers. One set of lymph-vessels runs along 
 with the deep epigastric artery and terminates in the external iliac glands. Another 
 
 ' The Lymphatics. By Poirier, Cun6o, and Delamare. Translated and edited by Cecil H. Leaf. 
 
 51 
 
g02 THE LYMPHATIC SYSTEM 
 
 accompanies the deep circumflex iliac artery, and also terminates in the external 
 iUac glands. Several lymph-vessels accompany the lumbar arteries and empty 
 into the juxta-aortic glands. A vessel accompanies the internal mammary artery 
 and empties into the internal mammary glands. Lymph-vessels of the parietes of 
 the pelvis, which accompany the gluteal, ischiatic, and obturator vessels, follow 
 the course of the internal iliac artery, and ultimately join the external iUac, internal 
 iUac, and common iliac glands, and the glands about the lower portions of the aorta 
 and vena cava. 
 
 The Lymphatic Vessels of the Umbilicus. — The lymphatics of the umbilicus are 
 divided into three groups:^ The cutaneous lymphatics, which are very superficial, 
 and empty into the superficial inguinal glands. The lymphatics of the fibrous 
 nucleus, which pass through the rectus sheath, reach the deep epigastric artery 
 and join the deep lymphatics which come from the muscular and aponeurotic 
 layers of the belly wall. The lymphatics of the aponeurotic margin are in two sets: 
 An anterior set, some of which penetrate the rectus sheath and join the lymphatics 
 from the fibrous nucleus; others of which pass outward, penetrate the external and 
 internal oblique muscles, and join the posterior lymph-vessels from the aponeu- 
 rotic margin. A posterior set, which forms a collection of vessels on the posterior 
 aspect of the rectus sheath, from which several trunks emerge. One trunk passes 
 outward, penetrates the Transversalis muscle, joins the anterior trunk from the 
 aponeurotic margin, and empties into the external iliac glands.^ Other ducts run 
 along with the deep epigastric artery and pass into the external iliac glands. 
 Glands lie along the lower portion of these lymph-ducts, and are known as 
 the superior epigastric glands, and a gland may exist in the subperitoneal tissue 
 beneath the umbihcus. 
 
 The Lymphatic Vessels of the Peritoneum. — It seems probable that the peritoneal 
 cavity is a lymph-sac and that lymphatics take origin from the peritoneum in 
 several ways. Byron Robinson^ points out three modes of origin: 1. By stomata 
 between endothelial cells. These stomata are in direct communication with 
 lymph-vessels. 2. By interstitial spaces in the subperitoneal tissue. 3. By a 
 plexiform origin similar to interstitial spaces. 
 
 Surgical Anatomy. — The fact emphasized by Byron Robinson that the peritoneum is a great 
 lymph-sac explains the quick absorption of septic material and the rapid spread of infectious pro- 
 cesses. If the exudate clots and blocks the lymph-channels, absorption is slow and life may be 
 saved. If it does not clot, absorption is rapid and death is certain. Whether it clots or not 
 depends on the nature of the bacteria present.'' Fowler, impressed by the fact that absorption 
 takes place most rapidly from the diaphragmatic region and least rapidly from the pelvic region, 
 advises placing the victim of peritonitis in bed, with his head and body elevated.* 
 
 The Lymphatic Vessels of the Bladder. — No lymphatics exist in the mucous mem- 
 brane of the bladder, although they do exist in the mucous membrane of the pros- 
 tate. There are some lymphatics in the bladder muscle, and numerous lymphatics 
 in the subperitoneal tissue. The network of lymph-vessels in the muscles is con- 
 nected with the network beneath the peritoneum and prevesical fascia, and collect- 
 ing trunks come from both the anterior and posterior surfaces of the bladder. 
 The anterior collecting trunks are divided into two sets. One set comes from the 
 inferior portion of the anterior surface and passes outward to terminate in an 
 external iliac gland "between the external iUac vein and the obturator nerve. "^ 
 The other set comes from the superior and anterior vesical surface, runs upward 
 and outward, and terminates in the external ihac glands. Each set of vessels 
 possesses interrupting lymph-nodes, some of which are directly in front of the 
 bladder. 
 
 * The Lymphatics. By Poirier, Cun6o, and Delamare. Translated and edited by Cecil H. Leaf. 
 
 2 Poirier. Cun6o, and Delamare. " The Peritoneum. ♦ Byron Rbbinson. The Peritoneum. 
 
 * George Ryerson Fowler, on Diffuse Septic Peritonitis, in the Medical Record, .\pril 14, 1900. 
 
 * The Lymphatics. By Poirier, Cuneo, and Delamare. Translated and edited by Cecil H. Leaf. 
 
THE LYMPHATIC VESSELS OF THE ABDOMEN AND PELVIS 803 
 
 The posterior collecting trunks are divided into four sets. The first set comes 
 from the superior and posterior portion and passes outward, exhibiting interrupting 
 nodes in its course. These trunks terminate in the external iliac glands. The 
 second set runs directly back into the external iliac glands. The third set comes 
 from the middle of the posterior portion of the bladder and terminates in the 
 hypogastric glands. The fourth set comes from the vesical neck, passes back 
 and then ascends and terminates in the glands in front of the sacral promontory. 
 This fourth set joins with the lymphatics from the prostate and seminal vesicles. 
 
 The Lymphatic Vessels of the Prostate Gland. — These vessels form a peri-pros- 
 tatic plexus, which receives its afferents from the gland structure. This plexus is 
 drained by four vessels, three of which commence on the posterior surface of the 
 gland. Although these vessels begin on the posterior surface of the prostate, their 
 termination in each case is different. One passes on the under surface of the 
 bladder, crosses the superior vesical artery, runs outward, and ends in the middle 
 chain of the external iliac group. Another passes upward, outward, and back- 
 ward, and terminates in the hypogastric group. A third passes along the 
 floor of the pelvis, runs by the side of the rectum, and ascends on the anterior 
 surface of the sacrum to terminate in the lateral sacral glands and in the hypo- 
 gastric group. Occasionally a fourth trunk is found on the anterior surface of 
 the prostate, which descends and joins the vessels from the membranous urethra 
 and ends in the hypogastric glands. 
 
 The Lymphatic Vessels of the Male Urethra. — These vessels are divided into two 
 groups: First, those of the penile portion of the urethra; second, those of the bulb 
 and membranous portion. The lymphatics of the prostatic urethra belong to those 
 of the prostate gland. The lymph-vessels of the penile urethra in front of the 
 sulcus all run toward the frsenum, at which point they bend backward to the sul- 
 cus; here they run to the dorsal surface of the penis and terminate in the same man- 
 ner as the vessels from the glans. The trunks from the remainder of the penile 
 urethra emerge from the inferior surface, run around the corpus cavernosa, and 
 mostly unite with the vessels from the glans penis. One vessel, though, passes over 
 the symphysis and enters in the internal retro-crural gland, whilst another passes 
 beneath the symphysis and terminates with the vessels from the bulb and mem- 
 branous portion of the urethra. The lymphatics of the bulb and membranous 
 portions end in three trunks, one of which accompanies first the artery of the bulb 
 and then the internal pudic artery, and ends in the hypogastric gland attached to 
 the pelvic portion of this artery. A second trunk runs behind the pubes, to end 
 in the internal retro-crural gland. A third trunk runs on the bladder, where it 
 joins with vessels from this organ, to end in the internal chain of external iliac 
 glands. 
 
 The Lymphatic Vessels of the Female Urethra. — The lymphatics of the female 
 urethra terminate in the same manner as do the lymphatics of the bulb and mem- 
 branous portions of the male urethra 
 
 The Lymphatic Vessels of the Uterus. — These consist of three sets, each of which 
 arises by a network of capillaries. There is a mucous network, a muscular network, 
 and a peritoneal network. The vessels from these three regions of origin are col- 
 lected in the subperitoneal tissue, from which area the collecting trunks take origin. 
 From the cervix, according to Poirier and Cun^o, come from five to eight collecting 
 trunks, which pass toward the sides of the body of the uterus, forming on each 
 side, by twisting and dilatation, the juxta-cervical lymphatic knot of Cun^o. The 
 cervical connecting trunks are divisible into three groups on each side. One group 
 is composed of two vessels, which pass to the middle chain of the external iliac 
 glands (superior and middle glands). Another group is composed of two vessels, 
 which enter the hypogastric glands. A third group is composed of several vessels, 
 some of which enter the lateral sacral glands, and the balance of which terminate 
 
804 THE LYMPHATIC SYSTE^I 
 
 in the glands of the sacral promontory. From the body of the uterus come three 
 groups on each side. One group is composed of four or five vessels which emerge 
 below the uterine cornu, pass beneath the ovary, where they receive the ovarian 
 lymphatics, and terminate in the juxta-aortic glands of the same side. One 
 so-called accessory lymphatic pedicle terminates in the external iliac glands, the 
 other in the inguinal glands. 
 
 The Lymphatic Vessels of the Fallopian Tube. — The lymphatics of the Fallopian 
 tube join with those of the uterus and ovary and terminate in the lateral aortic 
 glands. 
 
 The Lymphatic Vessels of the Ovary. — The ovary is extremely rich in lymphatics ; 
 thev form a plexus which is superficial to the veins. The vessels leading from this 
 plexus, four or five in number, pass upward in company with the ovarian vessels 
 and end in the lateral aortic glands. Above the fifth lumbar vertebra these ves- 
 sels anastomose with the lymphatics from the fundus of the uterus and Fallopian 
 tube. Quite often there is a lymph-vessel which emerges from the ovary, passes 
 downward and outward and ends in the middle chain of the internal iliac glands. 
 
 The Lymphatic Vessels of the Vagina. — The lymphatics of the vagina are cHvided 
 into those of the mucous coat and those of the muscular coat; these anastomose 
 freely with each other and terminate in a peri-vaginal network, which is drained 
 by three groups of trunks. One group drains the upper third of the vagina and 
 passes to the middle chain of the external iliac glands. A second group is efl^erent 
 to the middle third of the vagina and ends in the hypogastric glands. A third 
 group carries the lymph from the lower third of the vagina to the gland of the 
 promontory. 
 
 The Lymphatic Vessels of the Testicle. — The lymphatic vessels of the testicle 
 consist of two sets, superficial and deep; the former commence on the visceral sur- 
 face of the tunica vaginalis, the latter in the epididymis and body of the testis. 
 They form several large trunks which ascend with the spermatic cord, and, accom- 
 panying the spermatic vessels into the abdomen, terminate in the juxta-aortic 
 and sometimes also in the pre-aortic glands ; hence the enlargement of these glands 
 in malignant disease of the testis. 
 
 The Lymphatic Vessels of the Vas Deferens. — These lymphatics empty into the 
 external iliac glands. 
 
 The Lymphatic Vessels of the Seminal Vesicles. — A network exists on the surface 
 of each vesicle, formed by a collection of lymph-vessels from the mucous lining and 
 from the muscular structure of the vesicle. The trunks from this network empty 
 into the external and internal iliac glands. 
 
 The Lymphatic Vessels of the Kidney, Ureter, and Suprarenal Capsule. — Their 
 courses and terminations differ on the two sides. They take origin from a super- 
 ficial network just beneath the capsule of the kidney and a deep network in the in- 
 terior of the organ. The superficial network is connected to the collecting vessels 
 of the deep network at the hilum. From the superficial network numerous ves- 
 sels penetrate the capsule of the kidney and join the lymphatics of the fatty cap- 
 sule. According to Poirier, Cuneo, and Delamare,^ anterior and posterior trunks 
 come off from the deep lymphatics of the right kidney. The anterior trunk 
 usually terminates in the right juxta-aortic glands which lie upon the vena cava. 
 The posterior trunks terminate in the juxta-aortic glands which lie behind the 
 vena cava. On the left side all the collecting trunks terminate in the juxta-aortic 
 glands of the left side of the aorta. 
 
 The lymphatics of the fatty capsule of the kidney communicate with the lym- 
 phatics of the kidney^ and both terminate in the same glands. The lymphatics of 
 the suprarenal capsule terminate in the juxta-aortic glands of the same side. From 
 
 ' The Lymphatics. Translated and edited by Cecil H. Leaf. 
 
THE LYMPHATIC VESSELS OF THE ABDOMEN AND PELVIS 805 
 
 the ureter lymph-vessels come off and terminate in the juxta-aortic and adjacent 
 glands. 
 
 The Lymphatic Vessels of the Liver. — The lymphatic vessels of the liver are 
 divisible into two sets, superficial and deep. The former arise in the lobules at the 
 periphery of the liver and pass to the subperitoneal connective tissue over the 
 entire organ. The latter arise from the deeper lobules, and emerge from the liver 
 along the portal vein or the hepatic veins. 
 
 According to Poirier, Cuneo, and Delamare,* three groups of superficial collect- 
 ing trunks arise from the subperitoneal network. The 'posterior trunks divide 
 into three groups. The single right posterior trunk terminates in a gland about the 
 coeliac axis. The middle posterior trunks (five to seven in number) pass through 
 the opening in the Diaphragm. The left posterior trunks pass into glands 
 
 LEFT LATERAL 
 
 LIGAMENT 
 
 OBLrTERATED 
 UMBILICAL VEIN 
 
 Fig. 506. — Lymphatics of the inferior surface of the liver. (Sappey.) 
 
 about the subdiaphragmatic portion of the oesophagus. The anterior collecting 
 trunks terminate in the lymph-glands of the hilum of the liver. The superior 
 trunks ascend. One of these trunks or a posterior trunk passes with the vena cava 
 through the Diaphragm and terminates in glands about the vena cava. Another 
 trunk, an anterior one, pas.ses over the anterior border of the liver, runs for a time 
 wnth the round ligament, and terminates in the hepatic glands. Numerous middle 
 trunks ascend in the suspensory ligament, unite beneath the Diaphragm into a 
 short trunk of large size, which passes through the Diaphragm and divides into 
 several smaller ducts, which terminate in the glands back of the xiphoid cartilage. 
 Trunks from the superficial lymphatic network also emerge from the inferior 
 surface of the liver. The posterior trunks from the right lobe reach the vena cava 
 and terminate in the glands about the intra-thoracic end of that vessel. The 
 middle and anterior trunks from the right lobe reach the glands along the cystic 
 duct. The trunks from the left lobe terminate in the glands along the hepatic 
 artery. The trunks from the lobus Spigelii reach the glands of the hilum and the 
 glands about the lower intra-thoracic portion of the vena cava. The trunks from 
 the quadrate lobe terminate in the glands of the hilum. The deep collecting trunks 
 
 ' The Lympliatics. Translated and edited by Cecil H. Leaf. 
 
806 
 
 THE LYMPHATIC SYSTEM 
 
 are divisible into two groups. One group descends along the portal vein, the other 
 ascends along the hepatic veins. 
 
 Sappey pointed out that the deep descending trunks accompany the bile pass- 
 ages and the branches of the portal vein, several anastomosing vessels accom- 
 panying each branch of the portal vein. The same authority affirmed that from 
 fifteen to eighteen trunks emerge from the hilum and terminate in the adjacent 
 glands. The dee'p ascending trunks surround as a sheath the branches of the 
 hepatic vein (Sappey). As they approach the Diaphragm they diminish in num- 
 ber to five or six, pass through the opening for the vena cava, and terminate in 
 the glands about the lower portion of the intra-thoracic cava. 
 
 The Lymphatic Vessels of the Bile-ducts. — The lymphatics of the bile-ducts arise 
 from the mucous membrane and from within the muscular tissue, and terminate 
 in glands along the cystic and common ducts. 
 
 The Lymphatic Vessels of the Stomach (Figs. 507 and 508). — The lymphatic 
 vessels of the stomach consist of two sets, superficial and deep. The superficial 
 arise from the outer (serous) and the middle (muscular) coats. The deep arise 
 from the mucous membrane and form a network in the submucous tissue. Trunks 
 from the submucous network pass through the muscular tunic and terminate in 
 the trunks coming from the sero-muscular layers. These latter, the musculo-serous 
 
 CORONARY 
 CURRENT 
 
 RIGHT 
 
 OASTRO-EPIPLOIC 
 
 CURRENT 
 
 SPLENIC 
 CURRENT 
 
 Fig. 507. — Lymphatic areas of the stomach. (Cun6o.) 
 
 collecting trunks, are divided into three groups. The first group is composed of six 
 or eight vessels which pass toward the lesser curvature (Sappey). There are from 
 three to ten glands upon the lesser curvature along the course of the gastric artery 
 which receive these superior trunks. Vessels come to these glands from the cardia, 
 from the body of the stomach, and from the pyloric end. In the lesser curvature 
 the lymphatic vessels lie in the wall of the stomach. According to Cun^o, two- 
 thirds of the stomach is drained by the lymph-vessels of group I. The second 
 group comprises the trunks from the greater curvature which end in the subpyloric 
 glands. The glands along the greater curvature are some distance from the 
 stomach wall in the pyloric region, and lymph-streams flow from left to right, that 
 is, toward the pylorus and not from it. These lymphatics drain one-third of the 
 stomach. The first and second groups send lymph eventually to the coeliac 
 glands and juxta-aortic glands. The third group comprises trunks which come 
 from the fundus of the stomach and enter the lymphatic glands about the spleen. 
 
 Surgical Anatomy. — Mikulicz pointed out the early infection of the glands of the lesser curva- 
 ture in pyloric cancer, and insisted that in operation for pyloric cancer the entire lesser curvature 
 must be removed. Cuneo showed us that in pyloric cancer the fundus and two-thirds of the 
 greater curvature usually remain free from disease, because the lymph-current is toward the 
 pylorus and not from it. Of course, if the lymphatics become blocked, the lymph-current may 
 be reversed (regurgitation), and then infection of these parts can occur. William J. Mayo has 
 noted the ''lymphatic isolation" of the dome of the stomach. In operating for cancer of the 
 
THE LYMPHATIC SYSTEM OF THE INTESTINES 
 
 807 
 
 pylorus, make the section of the stomach as directed by Hartmann, that is, a section which 
 removes all of the lesser curvature and cuts the greater curvature well to the left of the subpyloric 
 glands. • 
 
 The Lymphatic Vessels of the Pancreas.— The lymphatics of the pancreas arise 
 from a network about the pancreatic lobules. The collecting trunks anastomose 
 freely on the surface of the pancreas. Some of the trunks terminate in the 
 splenic glands, which send vessels to the coeliac glands. Others terminate directly 
 in the coeliac glands. The lymphatics of the head of the pancreas communicate 
 with the duodenal lymphatics and the lymphatics of the lower end of the com- 
 mon duct. The pancreatic and splenic lymphatics probably communicate. 
 
 The Lymphatic Vessels of the Spleen. — The lymphatics of the spleen consist of 
 two sets, superficial and deep; the former are placed beneath its peritoneal covering, 
 the latter in the substance of the organ; they accompany the blood-vessels, passing 
 through a series of small glands, and pass into the splenic glands which are placed 
 in the omentum between the spleen and pancreas. The gastro-splenic omentum 
 contains no glands. 
 
 THE LYMPHATIC SYSTEM OF THE INTESTINES. 
 
 The Lymphatic Glands of the Small Intestine (Fig. 509). — The lymphatic 
 glands of the small intestine are placed between the layers of the mesentery, and are 
 
 RIGHT GASTRO 
 EPIPLOIC ARTCRY 
 
 SUBPYLORIC 
 GLAND 
 
 LEFT PNEUMO- 
 GASTRIC NERVE 
 
 RIGHT PNEUMO- 
 GASTRIC NERVE 
 
 CORONARY 
 
 VEIN 
 
 GLANDS OFTHE 
 
 LESSER CURVATURE 
 
 RIGHT GASTRO 
 EPIPLOIC VEIN 
 
 Fig. 508. — General view of the subperitoneal lymphatic plexus of the stomach prepared by the method of 
 
 Gerota. (Cun6o.) 
 
 called mesentery glands (lymphoglandulae mesentericae) . They vary in number from 
 a hundred to a hundred and fifty, and in size from that of a pea to that of a small 
 
808 
 
 THE LYMPHATIC SYSTEM 
 
 almond/ These glands are most numerous and largest above, the glands of the 
 jejunum being more numerous than those of the ileum. This latter group becomes 
 enlarged and infiltrated with deposit in cases of fever accompanied v^ith ulceration 
 of the intestines. The glands diminish in number as we descend until the ileo- 
 csecal region is reached, when a number of glands appear about the ileo-ceecal 
 artery. The mesenteric glands receive the lacteals and send out trunks to the 
 receptaculum chyli. The chyle from the intestine passes through the glands on 
 its way to the thoracic duct. 
 
 The glands may be divided into: I. A group of glands the members of which 
 are chiefly found along the terminal vessels from the vascular loops of the intestinal 
 branches of the superior mesenteric artery. Some glands of this group are placed 
 upon "the anterior surface of the upper end of the jejunum."^ II. A group of 
 glands along the vascular loops of the superior mesenteric artery. Most of them 
 are between the primary loops. Some of them are between the secondary and 
 tertiary loops. III. A group of glands along the trunk of the superior mesenteric 
 artery. 
 
 Fig. 509. — Lymphatics of the small intestine. (Poirier and Charpy.) 
 
 The L3miphatic Vessels of the Small Intestine (Fig. 509).— The lymphatic 
 vessels of the small intestine are called lacteals, from the milk-white fluid they 
 usually contain. They take origin in the intestinal villi and in lymphatic sinuses 
 around the bases of the solitary glands. Lymphatic plexuses exist in the submucous 
 tissue, the muscular coat, and the subserous tissue. The lymphatic vessels pass 
 between the layers of the mesentery, enter the mesenteric glands, and finally unite 
 to form two or three large trunks which terminate separately in the receptaculum 
 chyli; frequently, however, they first unite to form a single large trunk, termed the 
 intestinal lymphatic trunk (Figs. 483, 484, and 511). 
 
 The Lymphatic Glands of the Large Intestine.— The lymphatic glands of the 
 large intestine are divided into the colic glands and rectal glands. 
 
 The Colic Glands {lymphoglandulae coliacae). — The colic glands are subdivided 
 into: 1. The ileo-colic or ileo-ca^cal glands (Fig. 510), which he along the course 
 of the ileo-cohc artery, one or two of the glands being placed upon the anterior 
 surface of the caecum. The mesoappendix also contains a gland which com- 
 
 ' Leaf (Surgical Anatomy of the Lymphatic Glands) says it is very common" to find not more than forty or 
 fifty. 
 
 ■•i The Surgical Anatomy of the Lymphatic Glands. By Cecil H. Leaf. 
 
THE LYMPHATIC SYSTEM OF THE INTESTINES 
 
 809 
 
 municates with glands in the mesocolon, and receives lymph from the appendix 
 and, in the female, from the ovary. 2. Glands in the mesocolon along the right 
 colic artery, which receive lymph from the ascending colon and the hepatic flexure. 
 3. Glands in the mesocolon along the middle colic artery, which receive lymph 
 from the hepatic flexure and transverse colon. 4. Glands in the mesocolon 
 along the left colic artery, which receive lymph from the descending colon and 
 sigmoid flexure. The vessels from the colic glands pass to the pre-aortic 
 glands. 
 
 The Rectal Glands. — The rectal glands lie in the mesorectum; they receive lymph 
 from the anus antl rectum and it passes from them to the lumbar and sacral glands. 
 
 The Lymphatic Vessels of the Large Intestine.— The lymphatic vessels of the 
 large intestine consist of three sets: those of the caecum, ascending and transverse 
 
 ANTERIOR 
 LYMPHATICS 
 OF OECUM 
 
 GLAND OF 
 APPENDIX 
 
 Fig. 510. — Anterior view of the lymphatics of the Cffcum and appendix. (Poirier and Charpy.) 
 
 colon, which, after passing through their proper glands, enter the mesenteric 
 glands; those of the descending colon and sigmoid flexure, which pass to the lumbar 
 glands, and those of the rectum and anus, which pass to the sacral and superficial 
 inguinal glands. 
 
 Lymphatics of the Anus and Rectum. — These vessels take origin from two 
 networks, one from the skin and mucous membrane and the other from the mus- 
 cular coat. The lymph-vessels from the skin at the anal margin pass to the super- 
 ficial inguinal glands. Some vessels from the skin of the anus ascend and reach 
 the submucous plexus of the rectum, from which region lymph-vessels pass to 
 the rectal glands, to the glands along the middle haemorrhoidal artery, and along 
 the inferior haemorrhoidal artery, and to a pelvic gland near the origin of the 
 internal pudic artery.* The vessels from the anal mucous membrane and from 
 the muscular wall of the rectum penetrate the muscular wall of the rectum 
 with the arteries and reach the rectal glands. 
 
 ' The Lymphatics. By Poirier, Cun<!'o, and Delamare. Translated and edited by Cecil H. Lieaf. 
 
810 THE LYMPHATIC SYSTEM 
 
 THE LYMPHATICS OF THE THORAX. 
 
 The thoracic lymphatics are divided into the deep lymphatics of the chest wall, 
 the diaphragmatic lymphatics, and the visceral lymphatics. 
 
 The Lymphatic Glands of the Thoracic Wall or the Parietal Lymphatics. 
 
 The lymphatic glands of the thoracic wall include the internal mammary and 
 intercostal glands. 
 
 The Internal Mammary Glands. — The internal mammary, retro-sternal, or 
 sternal glands form a chain of five or six glands on each side of the sternum along 
 the course of the corresponding internal mammary artery, and back of the Internal 
 intercostal muscles. The glands are separated from the pleura by cellular tissue. 
 The internal mammary glands receive vessels from the diaphragmatic glands, the 
 abdominal muscles above the umbilicus, the anterior ends of the intercostal spaces, 
 the skin over the sternum, and the mammary gland. The vessels given off by 
 each chain form a single trunk. On the right side this trunk terminates at the 
 junction of the internal jugular and subclavian veins, unites with the subclavian 
 lymph-trunk to form the right lymphatic duct, or empties directly into the sub- 
 clavian trunk (Fig. 486). On the left side it empties either at the junction of 
 the subclavian and internal jugular veins or into the thoracic duct. 
 
 The Intercostal Glands (lymphoglandulae intercostales) (Fig. 511). — The inter- 
 costal glands are small glands lying in the intercostal spaces along the intercostal 
 arteries. In the posterior end of each space they are constantly found. These are 
 called the posterior glands, and there are one, two, or three in each space. These 
 glands are opposite the neck of the rib or over the articulation of the rib with the 
 vertebra. The pleura is in front of them, and they lie upon the external inter- 
 costal muscles. In the middle of the intercostal spaces are inconstant glands 
 which are called lateral glands. They are merely interrupting nodes in the 
 trunks from the intercostal muscles. The intercostal glands receive vessels from 
 the intercostal muscles and pleura. They send vessels back toward the spine, 
 which unite with lymphatics from the back part of the thorax and spinal canal, 
 and which pass down the spine and terminate in the thoracic duct. 
 
 The Diaphragmatic Ljmiphatics.— The diaphragmatic lymph-glands are dis- 
 tinct and numerous. These glands are on the convex surface of the Diaphragm 
 and are divided into an anterior, a middle, and a posterior group. They receive 
 vessels from the Diaphragm and liver and send vessels to the internal mammary 
 and posterior mediastinal glands. The lymph- vessels of the Diaphragm take 
 origin from a capillary network contained in the spaces between the muscular 
 and tendinous fasciculi of the Diaphragm. Numerous lymph-vessels descend 
 until they reach the subperitoneal tissues and then ascend. Others immediately 
 ascend to beneath the pleura. The collecting trunks are all on the convex surface 
 of the Diaphragm. The lymphatic vessels of the Diaphragm anastomose with 
 the lymphatic vessels of the pleura and the peritoneum. This subperitoneal 
 network is so extensive that absorption in this region is extremely rapid. 
 Hence, after an abdominal operation, if salt solution has been left in the ab- 
 domen, it will be very rapidly absorbed if the foot of the bed is elevated. 
 Influenced by the knowledge that the pelvic peritoneum absorbs comparatively 
 slowly and the peritoneum in the upper abdomen very rapidly, and that septic 
 processes in the upper abdomen are more rapidly fatal than septic processes in 
 the pelvis. Fowler was led to recommend the elevation of the head of the bed 
 after operations for abdominal infections. This posture causes poisonous fluids 
 to gravitate away from the Diaphragm. 
 
THE LYMPHATIC GLANDS OF THE THORACIC WALL 811 
 
 The Visceral Lymphatics. — The visceral lymphatics include the anterior medi- 
 astinal glands, the posterior mediastinal glands, and the peritracheo-bronchial glands. 
 
 The Anterior Mediastinal Glands {lymphoglandulae mediastinales anteriores) . — The 
 anterior mediastinal glands are in the upper portion of the anterior mediastinum, 
 a group of six or seven glands lying above and upon the front of the transverse 
 
 MEDIASTINAL 
 
 GLANDS AND 
 
 VESSELS 
 
 INTERCOSTAL 
 
 GLANDS AND 
 
 VESSELS 
 
 COMMON INTE8 
 TINAL TRUNK 
 
 PRE-AORTIC 
 GLANDS AND 
 VESSELS 
 LUMBAR 
 
 COMMON INTES- 
 TINAL TRUNK 
 
 INTERNAL ILIAC 
 EXTERNAL ILIAC 
 
 Fig. 511. — Deep lymphatic glands and vessels of the thorax and abdomen (diagrammatic). Afferent vessels are 
 represented by continuous lines, and efferent and interglandular vessels by dotted lines. (Cunningham.) 
 
 portion of the arch of the aorta and sending glandular chains toward the neck. 
 On the right side these glands are found between the innominate artery and vein 
 and in front of the vein. On the left side they are in front of and behind the left 
 common carotid and left subclavian arteries. They receive lymph from the heart, 
 pericardium, thymus gland, and anterior mediastinum. 
 
§12 THE LYMPHATIC SYSTEM 
 
 The Posterior Mediastinal Glands (lymphoglandulae mediastinales posteriores) 
 (Fig. 511). — The posterior mediastinal glands are behind the pericardium and 
 in front of the oesophagus. Occasionally one or two are placed back of the 
 oesophagus. They receive vessels from the intercostal glands, aortic glands, 
 deep cervical glands, and pleura, and send vessels to the thoracic duct. 
 
 The Peritracheo-bronchial Glands. — The peritracheo-bronchial glands are divided 
 by Barety into four groups. One group is in the angle formed by the junction 
 of the trachea and right bronchus. Another group is in a corresponding situation 
 on the left side. Another group is below the tracheal bifurcation. The glands of 
 the fourth group are about the points of division of the larger bronchi. The 
 peritracheo-bronchial glands receive lymph-vessels from the lung, heart, peri- 
 cardium, oesophagus, trachea, and thymus. 
 
 In infancy these glands present the same appearance as the lymphatic glands in other situa- 
 tions. In early adult life they assume a brownish tinge, and in old age become deep black, 
 because they arrest particles of carbon brought from the bronchi. This change is known as 
 anthracosis, and the darkened glands are usually sclerotic. In fact, in old age these glands often 
 lose all lymphatic characters and become fibrous masses. These glands enlarge from infection, 
 and when very large may compress the bronchi, the pulmonary artery, etc. They are often the seat 
 of tuberculous deposits. 
 
 The Lsnnphatic Vessels of the Thoracic Wall. — The lymphatic vessels of the 
 thoracic wall include the deep lymphatic vessels, intercostal and internal mammary, 
 which have been described, the cutaneous lymphatics, and the lymphatics of the 
 mammary gland. 
 
 The Cutaneous Lymphatics (Fig. 497).— The area drained by these lymphatics 
 is very extensive. It is divided by Poirier, Cun^o, and Delamare into three regions. 
 The anterior region extends from over the middle of the sternum to the anterior axil- 
 lary line. The trunks pass to the axilla and terminate in the thoracic chain of the 
 axillary glands. From this anterior region some accessory trunks pass above the 
 clavicle and reach the supra-clavicular glands, and trunks may arise to one side 
 of the mid-sternal line and pass to the opposite axilla. From the lateral region the 
 trunks ascend to the thoracic chain of axillary glands. This region is between 
 the anterior and posterior axillary lines. The posterior region is back of the 
 posterior axillary line, and includes the thorax to the mid-line, and the posterior 
 portion of the root of the neck. The trunks from the posterior area empty into 
 the scapular group of axillary glands. 
 
 Lymphatics of the Mammary Gland (Figs. 496 and 512).— There are two sets 
 of lymphatics in this gland, the cutaneous or superficial and the glandular or deep. 
 
 The Peripheral Cutaneous Lymphatics of the Mammary Gland. — The peripheral 
 cutaneous lymphatics do not arise from the nipple. Their collecting trunks are 
 arranged as are other collecting trunks of the anterior portion of the thorax, and 
 end in the thoracic group of axillary glands of the same side. Trunks arising from 
 the sternal margin of the skin of the breast may run to the glands of the opposite 
 axilla. 
 
 The Central Deep Lymphatics of the Mammary Gland. — The central lymphatics 
 form a very extensive network in the nipple and areola, and from this network 
 numerous vessels pass into a plexus beneath the areola, Sappey's subareolar plexus; 
 most of the trunks coming from the gland also enter the subareolar plexus. 
 
 The Glandular Lymphatics of the Mammary Gland. — The glandular lymphatics 
 arise from spaces about the lobules and from networks about the milk-ducts. We 
 can distinguish a chief lymphatic channel and three accessory channels. 
 
 The chief lymphatic channel takes origin from collecting trunks which begin 
 in the spaces about the lobules and in the lymph-capillaries about the milk-ducts. 
 These collectors pass toward the nipple and terminate in the subareolar plexus, 
 which plexus also receives the vessels from the areola and nipple. Two large 
 
THE LYMPHATIC GLANDS OF THE THORACIC WALL 813 
 
 trunks take origin from the subareolar plexus : one from its inner side, the other 
 from its outer side. "The internal trunk runs at first downward and then out- 
 ward, turning round the inferior border of the subareolar plexus. It is thus 
 directed toward the axilla and runs in the subcutaneous cellular tissue, along the 
 lower border of the Pectoralis major, which it crosses at the level of the third 
 rib to reach the base of the axilla. This collecting trunk constantly receives as 
 afferents one or two fair-sized trunks coming directly from the inferior portion of 
 the mammary gland. The external trunk, which is usually smaller than the pre- 
 ceding, runs directly outward toward the axilla. Before it reaches the latter it 
 is augmented by a vessel coming from the superior part of the gland. At the base 
 of the axilla these two collecting trunks perforate the axillary aponeurosis and 
 terminate in one or two glands, placed on the inner wall of the axilla on the third 
 digitation of the Serratus magnus muscle. These glands (the principal regional 
 glands of the breast) may or may not be covered by the lower part of the Pec= 
 
 Fig. 512. — The vessels and lymphatics of the anterior face of the mammary glands. (Sappey.) 
 
 toralis major muscle according to the muscular development of the subject (Sur- 
 gius)."^ These glands constitute the supero-internal mass of the anterior axillary 
 chain. An interrupting gland is sometimes found in the course of these two 
 trunks, the paxamammaxy gland. 
 
 The Accessory Channels from the Mammary Gland. — The accessory channels from 
 the mammary gland, according to Poirier, Cun^o, and Delamare, are three. They 
 call one the accessory axillary channel. It is not constant, and there may be inter- 
 rupting glands on its collectors. Its collectors come off from the inferior portion 
 of the mammary gland and pass directly to the axillary glands. Another channel 
 is the subclavian channel. Neither is it constant. It comes off from the posterior 
 surface of the mammary gland, pierces the great Pectoral muscle, and ascends 
 between the greater and lesser Pectorals to reach the subclavian glands. There 
 
 ' The Lymphatics. By Poirier, Cun<5o, and Delamare. Translated and edited by Cecil H. Leaf. 
 
814 THE LYMPHATIC SYSTEM 
 
 are usually interrupting glands along this channel, the retro-pectoral glands. The 
 subclavian channel runs along the superior thoracic artery. They call the third 
 accessory channel the internal mammary channel. The collecting trunks arise 
 from the inner portion of the mammary gland and pass along the vessels sent off 
 from the internal mammary artery to the gland. They pierce the Pectoral and 
 Intercostal muscles and reach the internal mammary glands. This channel is 
 constant and along it there may be interrupting glands. 
 
 Lymphatics of the Great Pectoral Muscle. — The lymphatics of the great Pectoral 
 muscle end in the subclavian glands, the thoracic group of axillary glands, and 
 the internal mammary glands. 
 
 Surgical Anatomy. — A knowledge of the lymphatics of the breast and of the glands into which 
 the lymphatics drain is of the first importance to a surgeon. Certain surgical deductions from 
 the anatomy of this region are perfectly obvious — viz. : 1 . If the skin of the mammary gland is 
 involved in carcinoma, the thoracic group of axillary glands of the same side is involved. If the 
 skin over the sternal margin of the gland is involved, the glands of the opposite axilla may be can- 
 cerous, as from this point lymph-vessels rise and pass across the mid-line. If the skin of the 
 sternal margin is involved the prognosis is worse than if it is free, the opposite axilla may be 
 cancerous, and the opposite breast may become diseased. 2. When lymphatic ducts become 
 blocked by cancer cells the lymph backs up, flows backward instead of in its proper direc- 
 tion, and may cause infecton in the most unsuspected situations. For instance, a block in the 
 cutaneous lymphatics of a portion of the breast may lead to infection of the opposite breast and 
 axilla, though, of course, it is not so likely to as is cancer of the skin of the sternal margin. By 
 regurgitation of lymph the head of the humerus or the retro-sternal structures may become dis- 
 eased in mammary cancer. 3. If the nipple or areola is cancerous, the entire gland is sure to be 
 diseased, as the lymphatic network of this region empties into the subareolar plexus, and most 
 of the trunks coming from the gland also enter this plexus. 4. If the mammary gland is cancer- 
 ous, all of the axillary glands are regarded as diseased, as the main lymphatic channel from the 
 breast reaches the glands on the inner wall of the axilla upon the third digitation of the Ser- 
 ratus magnus. Furthermore, in many cases an accessory lymph-channel comes off from the 
 lower portion of the mammary gland and passes directly to the axilla. 5. The subclavian glands 
 are to be regarded as diseased, because in a certain proportion of cases (the exact proportion 
 being uncertain) an accessory lymph-channel comes off from the posterior surface of the mam- 
 mary gland, passes through the great Pectoral muscle and ascends between the greater and 
 lesser Pectorals to reach the subclavian glands. 6. The element which greatly interferes with 
 the cure of mammary carcinoma is the existence of lymph-channels which arise from the inner 
 portion of the mammary gland, pierce the greater Pectoral and Internal intercostal muscles, and 
 reach the internal mammary glands. Mediastinal involvement is apt to be earlier in carcinoma 
 of the inner portion of the breast than in carcinoma of other portions, and the prognosis is par- 
 ticularly bad in cancer of the inner portion of the breast. What is known as the sternal symptom 
 of Snow is bulging of the sternum due to involvement of the thymus gland. 7. The sternal 
 portion of the great Pectoral and the tissue between it and the lesser Pectoral muscle are to be 
 regarded as diseased, because in some cases an accessory lymph-channel from the breast pene- 
 trates the greater Pectoral and ascends to the subclavian glands. This trunk has several inter- 
 rupting or satellite glands, the retro-pectoral glands, in the tissue back of the great Pectoral 
 muscle. 8. When the great Pectoral muscle is diseased, cancer cells soon spread widely through 
 the sternal portion of the muscle, and this entire portion of the muscle becomes cancerous. The 
 clavicular portion does not suffer early, but escapes until the cancer becomes extensive, as it 
 is anatomically distinct from the sternal portion. If the fibres of the great Pectoral are exten- 
 sively diseased, the thoracic group of axillary glands, the subclavian glands, and possibly the 
 internal mammary glands are involved. 9. The only operation in cancer of the breast which 
 offers any real hope of cure is one which is done early and is radical. 10. It must be done 
 early, because delay permits involvement of the mediastinum, and if the disease has entered 
 the mediastinum operation is hopeless. If the sternum is bulged operation is useless, and 
 nothing short of amputation at the shoulder-joint could be of help if the head of the humerus 
 is enlarged by the disease. Even this radical procedure is of no avail, because the mediastinum 
 is certainly involved if the head of the humerus is diseased. 11. If the lymph-glands above 
 the clavicle are extensively diseased operation is useless, as in such cases the mediastinum is 
 sure to be involved. 12. A radical operation means the removal of the skin of the breast with 
 the nipple and areola, the subcutaneous tissue of this region, the entire breast the sternal 
 portion of the great Pectoral with its fascia, the retro-pectoral glands and tissue, all the con- 
 tents of the axilla except vessels and nerves, the glands and cellular tissue beneath the anterior 
 margin of the Latissimus dorsi, and the subclavian glands. It is probably always wisest to 
 open above the clavicle as well as below to facilitate the removal of glands. It is seldom necessary 
 
THE LYMPHATIC GLANDS OF THE THORACIC WALL 815 
 
 to remove the clavicular portion of the greater Pectoral. The lesser Pectoral does not require 
 removal, but it should be taken away, because of the added safety and speed thus obtained 
 in cleaning the great vessels and because its retention does not improve the functional result. 
 The surgeon must remember that the breast is a much larger organ than we used to think, and 
 all of its irregular projections and outlying lobules must be removed (p. 793). Formerly, 
 surgeons did not completely remove the breast, but only got rid of a large portion of it. 
 
 The Pulmonary Lymphatics. — The pulmonary lymphatics arise from net- 
 works betw^een the lobules, around the bronchi and under the mucous membrane. 
 The collecting trunks are in two sets, superficial and deep: the former are placed 
 beneath the pleura, forming a minute plexus which covers the outer surface of 
 the lung; the latter accompany the blood-vessels and run along the bronchi; they 
 both terminate at the root of the lungs in the tracheo-bronchial glands. 
 
 The Pleural Lymphatics. — The lymphatics of the pulmonary pleura pass into the 
 superficial pulmonary trunks; those from the costal pleura enter the intercostal 
 trunks; those from the diaphragmatic pleura enter the diaphragmatic trunks, and 
 those from the mediastinal pleura enter the posterior mediastinal glands.^ 
 
 The Cardiac Ljnnphatic Vessels. — The cardiac lymphatic vessels consist of 
 two sets, superficial and deep: the former arise in the subpericardial areolar tissue of 
 the surface, and the latter in the subendocardial tissue. From the network of deep 
 lymphatics trunks pass to the superficial lymphatics. The superficial lymphatics 
 follow the course of the coronary vessels. Two trunks are formed: an anterior, 
 which lies in the anterior interventricular furrow, and an inferior, which lies in 
 the inferior interventricular furrow. These two trunks collect the lymph from the 
 ventricles and pass to the base of the heart, where they receive lymph from the 
 auricles. The anterior or left trunk ascends between the left auricle and the pul- 
 monary artery on the posterior surface of the artery, perforates the pericardium, and 
 enters the glands about the tracheal bifurcation. The right, posterior or inferior 
 trunk ascends between the aorta and pulmonary artery and terminates in the same 
 group of glands as the left tnmk. 
 
 The Thymic Ljnnphatic Vessels. — The thymic lymphatic vessels arise from 
 the under surface of the thymus gland, and enter the anterior mediastinal, the 
 internal mammary, and the peritracheo-bronchial glands. 
 
 The Lymphatic Vessels of the CEsophagus. — The lymphatics of the thoracic 
 oesophagus arise from two networks, one beneath the mucous membrane and one 
 beneath the muscular fasciculi. The connecting trunks terminate in the peri- 
 oesophageal glands. 
 
 The Ljrmphatic Vessels of the Thoracic Trachea. — The lymphatics of the 
 thoracic trachea take origin from a network in the submucous tissue. From this 
 a number of collecting trunks pass through the trachea in the line of junction of 
 the cartilaginous with the membranous portion. They terminate the peritracheo- 
 bronchial glands. 
 
 ' The Lymphatics. By Poirier, Cun6o, and Delamare. Translated and edited by Cecil H. Leaf. 
 
THE NEEVOUS SYSTEM. 
 
 THE nervous system consists of (1) the cerebro -spinal nervous system and (2) 
 the sympathetic nervous system. 
 1. The Cerebro-spinal Nervous System is composed of the spinal cord and 
 brain and of nerves joined to the brain and cord. The spinal cord and brain 
 constitute the cerebro-spinal axis, or, as it is also called, the encephalo-spinal axis, 
 the neuraxis, or the central nervous system. The nerves which join the cord and 
 which join the brain constitute the peripheral nervous system. The term central 
 nervous system is applied to structures contained altogether within the spinal 
 and cranial cavities, but this narrow uc? is not strictly accurate. By far the greater 
 part of the central nervous system i: contained within those cavities, but any 
 centre of energy must be regarded as a portion of the central system, and certain 
 ganglia which are centres of energy lie along certain nerves and really belong to 
 the central nervous system, though they are discussed with the peripheral nerves. 
 
 The term peripheral nervous system does not mean, as it would seem to, 
 structures outside the spinal and cranial cavities. The chief part of the peripheral 
 system is outside of the spinal and cerebral cavities, but peripheral nerves 
 "sometimes run a considerable distance within these cavities."^ The peripheral 
 nerv^ous syst.^m is composed of thirty-one pairs of spinal nerves and twelve 
 pairs of cranial nerves. Each spinal nerve is joined to the spinal cord by two roots, 
 an anterior and a posterior root, and the posterior root at one point has an enlarge- 
 ment called a spinal ganglion. The fifth cranial nerve, alone among cranial nerves, 
 takes origin by two roots, as does a spinal nerve. Five of the cranial nerves 
 possess ganglia similar to the ganglia on the posterior roots of the spinal nerves. 
 The cranial nerves which possess ganglia are the trigeminal or fifth, the facial or 
 seventh, the auditory or eighth, the glosso-pharyngeal or ninth, and the pneumo- 
 gastric or tenth. 
 
 2. The Sympathetic Nervous System consists of a chain of ganglia on either side 
 of the vertebral column. The ganglia of each chain are joined by cords of nervous 
 matter. The sympathetic system contains, beside the gangliated cords, numerous 
 nerve plexuses and ganglia in various regions. The sympathetic nervous system 
 is closely connected at many points with the cerebro-spinal nervous system, and 
 the two systems in all probability develop from a common origin. 
 
 Structure of the Cerebro-spinal Nervous System. — The spinal cord and 
 brain contain gray matter and white matter. The gray matter is vascular and is 
 composed chiefly of nerve-cells: the white matter is less vascular and is composed 
 chiefly of nerve-fibres. Until recently it was the custom to regard nerve-cells and 
 nerve-fibres as definitely distinct elements, but we now know that nerve-fibres are 
 processes of nerve-cells. One process, several processes, or many processes come 
 off from nerve-cells. If there is but one process from a cell, that process becomes 
 Deiters' process, the axis- cylinder or axone of a nerve-fibre. If more than one 
 process comes off from a cell, one of the processes becomes an axone, and the 
 other processes are known as protoplasmic or dendritic processes, or, as His named 
 
 ' The Nervous System and its Diseases. By Charles K. Mills. 
 
 52. (817) 
 
818 
 
 THE NERVOUS SYSTEM 
 
 them, dendrites. There are no nerve-fibres unconnected with cells. The nerve- 
 cell, with its axone and its dendrites, constitutes what is called a nerve-unit or 
 neurone. The nervous system is said to be composed of aggregations of multitudes 
 of neurones. The term neurone was devised by Waldeyer in 1891. 
 
 Gray, vesicular, or cineritious substance is of a dark, reddish-gray color and of a 
 soft consistence. It is found in the spinal cord, brain, and various ganglia, in 
 some of the nerves of special sense, and in gangliform enlargements in the course 
 of certain spinal nerves. It is composed of nerve-cells and contains blood-vessels, 
 both the cells and vessels being embedded in a ground substance named by 
 Virchow the neuroglia. The nerve-fibres and the vessels in the white substance 
 are also embedded in neuroglia. Neuroglia consists of fibres and neuroglia cells. 
 Some of the cells are stellate in shape and their fine processes become neuroglia- 
 fibres, which extend radially and unbranched (Fig. 513 B) among the nerve-cells 
 and fibres, which they aid in supporting. Other cells give off fibres, which branch 
 repeatedly (Fig. 513 A). 
 
 Fici. 513.— Neuroglia-cells of brain shown by Golgi's method. A. Cell with branched processes. B. Spider- 
 cell with unbranched processes. (After Andriezen.) (Copied from Schiifer's Essentials of Histology.) 
 
 In addition to these fibres there are others which do not appear to be connected 
 with the neuroglia-cells. They start from the lining ependi/mal cells, that is, the 
 epithelial cells lining the ventricles of the brain and central canal of the spinal 
 cord, and pass through the nervous tissue, branching repeatedly, to terminate in 
 slight enlargements on the pia mater. Thus, neuroglia is evidently a connective 
 tissue in function, though it is not in development; it is epiblastic in origin, whereas 
 all true connective tissues are mesoblastic. 
 
 The white or fibrous tissue is composed of nerve-fibres, which, with blood- 
 vessels, are embedded in neuroglia. 
 
 Nerve-cells or the Cell-bodies of the Neurones (Figs. 514, 515, 516, 517, 518, and 
 519). — Nerve-cells constitute the essential element of nervous tissue. They are the 
 originators of nervous impulses and impressions. All nervous conduction is from 
 nerve-cell to nerve-cell by contact (Mills), and the transmission of an impulse 
 from one nerve-cell to another may be over a long distance. The nerve-cells of 
 the brain and cord differ in origin, development, and connections from the nerve- 
 cells of the spinal ganglia. They vary greatly in shape and size (Fig. 515). 
 Some are so small that they become visible only under a microscope of high 
 
STRUCTURE OF THE CEBEBBO- SPINAL NERVOUS SYSTEM 819 
 
 power; some "almost come within the range of unaided vision."* The largest 
 cells are found in the anterior cornua of the spinal cord, in the vesicular columns 
 of Clarke, in the large pyramidal cell-layer of the cerebral cortex, and the Purkin- 
 jean cell-layer of the cerebellum. The smallest cells are in the olfactory bulbs, 
 in the substantia gelatinosa Rolandi of the cord, and in the granular cortical 
 layers of the cerebrum and cerebellum. 
 
 Fig. .514. — Nerve-cells from the Gasserian 
 Kanglion of the human subject, a. A globu- 
 lar one with defined border, h. Its nucleus, 
 c. Its nucleolus, d. Caudate cell. e. Elon- 
 gated cell with two groups of pigment-par- 
 ticles. /. Cell surrounded by its sheath or 
 capsule of nucleated particles, a. The sanrie, 
 the sheath only being in focus. Magnified 300 
 diameters. 
 
 Axone. 
 
 Fig. 515. — Nerve-cells from the inner part of the 
 gray matter of the convolutions of the human brain. 
 Nerve-cells: a. Larger, b. Smaller, c. Nerve-fibre 
 with axis-cylinder. Magnified 350 times. 
 
 'heath of 
 cell body. 
 
 Nucleus. 
 
 Cell protoplasm. 
 
 Axone. 
 Myelin sheath. 
 
 Fig. 516. — Bipolar nerve-cells from the spinal gan- 
 glion of the pike. (After Kiilliker.) 
 
 •>^ A.rnne. 
 
 Fig. 517. — Motor nerve-cell from ventral horn 
 of spinal cord of rabbit. The angular and spindle- 
 shaped Nissl bodies are well shown. (After 
 Nissl.) 
 
 The Body of the nerve-cell may possess a limiting membrane, as is seen in the 
 cells of the spinal ganglia (Fig. 516) and sympathetic ganglia, and some of the 
 cells of the Gasserian ganglion (Figs. 514, / and g), but may be devoid of any 
 limiting membrane, as is .seen in the motor cells of the anterior cornua of the cord 
 (Fig. 517). All cell-bodies, like all cell-processes, show intracellular fibrillation, 
 and the fibrils of the cell-body are continuous with those of the axone and run in 
 
 ' Text-book of Anatomy. By Prof. D. J. Cunningham. 
 
820 
 
 THE NERVOUS SYSTEM 
 
 various directions. The cell-body is composed of protoplasm, which contains, 
 besides fibrils, many fine spindle-shaped granules. The granules stain deeply 
 and are called chromatophile granules, Nissl's bodies, or trigoid bodies (Fig. 517). 
 They are probably nucleo-albumins (Held). Most nerve-cells, certainly most large 
 nerve-cells, possess considerable pigmented material, a nucleus, and a nucleolus. 
 The nucleus (Fig. 514 h) is, as a rule, a large, well-defined, round, vesicular 
 body, often presenting an intranuclear network. It contains a nucleolus (Fig. 
 
 514 c), which is peculiarly clear and bril- 
 liant. Figment granules (Fig. 514 e), 
 when present, he by the side of the nu- 
 cleus. Masses of pigment are present 
 in the cells of the substantia nigra and 
 locus caeruleus. 
 
 Nerve-cells are divided for purposes 
 of study into three groups, according to 
 the number of their processes. 
 
 1. Unipolar Cells. — The single process 
 of such a cell, after a short course, divides 
 in a T-shaped manner. Unipolar cells 
 are found in the spinal ganglia of the 
 adult and among the olfactory cells of 
 mammals. 
 
 Fig. 518. — Pyramidal cell from the cerebral cortex 
 of a mouse. (After Ramon y Cajal.) 
 
 Fig. 519. — Cell of Purkinje from the cerebellum of 
 a cat. (After Ramon y Cajal.) 
 
 2. Bipolar cells (Fig. 516) are found in spinal ganglion-cells when the cells are in 
 an embryonic condition. They are best demonstrated in the sympathetic ganglion- 
 cells of a frog. Sometimes the processes come off from opposite poles of the cell, 
 and the cell then assumes a spindle shape; in others they both emerge at the same 
 point. In some cases where two fibres are apparently connected with a cell, one 
 of the fibres is really derived from an adjoining nerve-cell and is passing to end 
 in a ramification around the ganglion-cell, or, again, it may be coiled spirally 
 around the nerve-process which is issuing 'from the cell. 
 
 I 
 
STRUCTURE OF THE CEBEBRO- SPINAL NERVOUS SYSTEM 821 
 
 3. Multipolar cells (Fig. 517) are caudate or stellate in shape, and are character- 
 ized by their large size and by the tail-hke processes which issue from them. The 
 processes are of two kinds : one of them is the axis-cyhnder or axone ; the others 
 are the protoplasmic processes or dendrites. 
 
 The Axone (Figs. 515, 516,. 517, 518, and 519). — ^The axone emerges from the 
 nerve-cell by a slender stalk; it is smooth and free from Nissl's bodies; it main- 
 tains a uniform diameter for a considerable distance; it does not, as a rule, divide 
 into branches, although it may possess collaterals, and it becomes the axis-cylinder 
 of a nerve-fibre. Cerebro-spinal axones, as a rule, are medullated, except near 
 their terminations. Sympathetic axones are non-medullated. Axones may be 
 extremely short or may be several feet in length. The fibres of the pyramidal 
 tract are axones of great length. Some short axones divide at their terminations 
 into many branches. Short axones are called dendraxones, and the cells with den- 
 draxones are called the second type of Golgl cells. An axone may remain throughout 
 its entire course in the brain or cord or may enter into a spinal or cerebral nerve. 
 Most cells possess but one axone, and such a neurone is called monoaxonic. A cell 
 may possess two axones, the neurone being called diaxonic, or several axones, the 
 neurone being called polyaxonic. The collaterals are branches given off from the 
 neurone at right angles to it. Some axones have a number of collaterals; others 
 do not have any. They are present everywhere in the central nervous system 
 (Cajal, Kolliker). Some collaterals are medullated; others are not. They 
 approach the dendrites of the nerve-cells of the neurones. Each axone and col- 
 lateral ends in a button-like termination or end-tuft, or in a free arborization, the 
 end-brush. If the termination is within the brain or cord, it may wrap around 
 nerve-cells or arborize about dendrites. If the axone emerges from the cerebro- 
 spinal axis, it terminates about muscle-cell or some other structure. The termi- 
 nation of the axone or the collateral is never continued into the structure about 
 which it lies. It may surround that tissue; it may touch it; it may lie close against 
 it, but the termination is free, and the relation is simply one of contact and not of 
 continuity. 
 
 The Dendrites. — ^The dendrites are protoplasmic processes resembling in struc- 
 ture and staining reactions the protoplasm of the body of the cell. Each emerges 
 by a thick base (gemmule), and divides into many fine branches, with free ends. 
 They are not straight, are not smooth, and do not maintain the same diameter for 
 a considerable distance as does the axis-cylinder. A dendrite may branch at 
 any distance from the body of the cell, and the branches do not join. The den- 
 drites from a single cell vary greatly in number, thickness, and length. Some 
 cells are devoid of dendrites; some give off a few; some give off many. As a rule, 
 they are non-medullated. 
 
 The Theory of Neurones. — This theory maintains that the nervous system is com- 
 posed of a multitude of units called neurones. Each neurone consists of a cell and 
 processes. The neurones in aggregation form cell groups and fibre systems. The 
 connection of nerve-cells with other nerve-cells is not by continuity of structure. 
 It is by contact and not by actual junction; it is physiological and not anatomical. 
 "When fully developed in man, perhaps a very small number of neurones are 
 united together by concrescence or protoplasmic bridges, but their predominant 
 relation is certainly that of contact or synapsis."^ Process comes in contact with 
 process, or process with cell. The terminal tufts of the axone of a cortical motor- 
 cell surround a cell in the anterior horn of the spinal cord, and this spinal cell 
 sends out an axone, the termination of which reaches a muscle. Doubt has of 
 late arisen as to the neurone theory, because of the investigations of Apathy and 
 others. Apathy claims that ganglion cells join directly and that the ultimate 
 
 1 Anatomy of the Brain and Nervous System. By Harris E. Santee. 
 
822 
 
 THE NERVOUS SYSTEM 
 
 elements of the nervous system are neurofibrils, which pass from cell to celL 
 However, as stated by Szymonowicz/ Apathy's observations, even if correct, do 
 not disprove the neurone theory, but indicate that the nervous units or neurones 
 are occasionally connected by neurofibrils. 
 
 Nerve-fibres. — Nerve-fibres serve to conduct nervous impulses and bring nerve- 
 cells into relation with each other and into relation with other structures. Nerves 
 are composed of numbers of nerve-fibres bound into bundles. There are two sorts 
 of fibres: medullated or white and non-meduUated or gray. 
 
 The Medullated fibres form the white part of the brain and spinal cord, and 
 also the greater part of the cerebro-spinal nerves, and gives to these structures 
 their opaque, white aspect. When perfectly fresh they appear to be homoge- 
 neous; but soon after removal from the body they present, when examined by 
 transmitted light, a double outline or contour, as if consisting of two parts (Figs. 
 520 and 521). The central portion is named the axis-cylinder of PUrkinje (Fig. 
 521); around this is a sort of sheath of fatty material, staining black with osmic 
 
 Fig. 520. — White or medullated nerve- 
 fibres showing the sinuous outline and 
 double contours. (After Schafer.) 
 
 Fibrils of axis- 
 cylinder. 
 
 Neurilemma. 
 
 Segment of 
 Lantermann. 
 
 White substance 
 of Schwann 
 stained black 
 by osmic add. 
 
 Fig. 521. — Longitudinal section through a nerve-fibre- 
 from the sciatic nerve of a frog. X 830. (After Buhm and 
 Davidoff.) 
 
 acid, named the white substance of Schwann (Fig. 521), which gives to the fibre 
 its double contour, and the whole is enclosed in a delicate membrane, the neuri- 
 lemma, primitive sheath, or nucleated sheath of Schwann (Fig. 521). 
 
 The axis-cylinder is the essential part of the nerve-fibre, and is always present ; 
 the other parts, the medullary sheath and the neurilemma, being occasionally 
 absent, especially at the origin and termination of the nerve-fibre. It undergoes 
 no interruption from its origin in the nerve-centre to its peripheral termination, 
 and must be regarded as a direct prolongation of a nerve-cell. It constitutes 
 about one-half or one-third of the nerve-tube, the whole substance being greater 
 in proportion in the nerves than in the central organs. It is perfectly transparent, 
 and is therefore indistinguishable in a perfectly fresh and natural state of the 
 nerve. It is made up of exceedingly fine fibrils, which stain darkly with gold 
 chloride (Fig. 521). At its termination the axis-cylinder of a nerve-fibre may be 
 seen to break up into fibrillse, confirming the accepted view of its structure. These 
 fibrillae 6ave been termed the primitive fibrillae of Schultze. The axis-cylinder is said 
 
 ' Text-book of Histology and Microscopic Anatomy. By Dr. Ladislaus Szymonowicz. Translated and edited 
 by John Bruce MacCallum, M.D. 
 
DEVELOPMENT OF NERVE CELLS AND FIBRES 823 
 
 by some to be enveloped in a special, reticular sheath, which separates it from the 
 white matter of Schwann, and is composed of a substance called neurokeratin. 
 The more common opinion is that this network or reticulum is contained in the 
 white matter of Schwann, and by some it is believed to be produced by the action 
 of the reagents employed to demonstrate it. The medullary sheath or white sub- 
 stance of Schwann (Fig. 521) is regarded as being fatty matter in a fluid state, which 
 insulates and protects the essential part of the nerve — the axis-cylinder. The white 
 matter varies in thickness to a very considerable extent, in some nerve-fibres forming 
 a layer of extreme thinness, so as to be scarcely distinguishable; in others forming 
 about one-half of the nerve-tube. The size of the nerve-fibres, which varies from 
 ^q^qO to xToT of an inch, depends mainly upon the amount of the white substance, 
 though the axis-cylinder also varies in size within certain limits. The white sub- 
 stance of Schwann does not always form a continuous sheath for the axis-cylinder, 
 but undergoes interruptions in its continuity at regular intervals, giving to the 
 fibre the appearance of constriction at these points. These constrictions were first 
 described by Ranvier,and are known as the nodes of Ranvier (Fig. 522). The portion 
 
 Fig. 522. — \ node of Ranvier of a medullated nerve-fibre, viewed from_ above, magnified about 750 diameters. 
 The medullary sheath is discontinuous at the node, whereas the axi.s-cylinder passe.s from one segment into the 
 other. At the node the sheath of Schwann appears thickened. (Klein and Noble Smith.) 
 
 of nerve-fibre between two nodes is called an intemodal segment. The neurilemma 
 or primitive sheath is not interrupted at the nodes, but passes over them as a con- 
 tinuous membrane. In addition to these interruptions obHque clefts may be seen 
 in the medullary .sheath, subdividing it into irregular portions, which are termed 
 medullary segments or segments of Lantermann (Fig. 521). There is reason to 
 believe that these clefts are artificially produced in the preparation of the speci- 
 mens. Medullated nerve-fibres, when examined, frequently present a beaded or 
 varicose appearance; this is due to manipulation and pressure causing the oily 
 matter to collect into drops, and in consequence of the extreme delicacy of the 
 primitive sheath, even slight pressure will cause the transudation of the fatty 
 matter, which collects as drops of oil outside the membrane. This is, of course, 
 promoted by the action of certain reagents. 
 
 The neurilemma or primitive sheath, sometimes called the tubular membrane or 
 sheath of Schwann (Fig. 521), presents the appearance of a delicate, structureless 
 membrane. Here and there beneath it, and situated in depressions in the white 
 matter of Schwann, are nuclei surrounded by a small amount of protoplasm. 
 The nuclei are oval and somewhat flattened, and bear a definite relation to the 
 nodes of Ranvier; one nucleus generally lying in the centre of each internode. 
 The primitive sheath is not present in all medullated nerve-fibres, being absent 
 in those fibres which are found in the brain and spinal cord. 
 
 Non-medullated Fibres. — Most of the nerves of the sympathetic system, and 
 some of the cerebro-spinal, consist of another variety of nervous fibres, which are 
 called the gray or gelatinous nerve- fibres — fibres of Remak (Fig. 523). These con- 
 sist of a central core or axis-cylinder enclosed in a nucleated sheath, which tends 
 to split into fibrillse, and is probably of the nature of neurokeratin. In external 
 appearance the gelatinous nerves are semi-transparent and gray or yellowish- 
 gray. The individual fibres vary in size, generally averaging about half the size 
 of the medullated fibres. 
 
 Development of Nerve-cells and Fibres. — The nerve-cells are developed 
 from certain of the cells which line the neural canal and form the neural crest of the 
 embryo. Some of these cells assume a rounded form and are termed neuroblasts, 
 
824 
 
 THE NERVOUS SYSTEM 
 
 and from each neuroblast there grows out a process, the axis-cyhnder process or 
 axone, and subsequently the branching processes or dendrons. The axis-cylin- 
 ders, at first naked, acquire their medullary sheaths, possibly by some metamor- 
 phosis of their outer layer. The neurilemma is thought to be derived from 
 mesoblastic cells which become flattened and wrapped around the fibre, the 
 cement-substance at their opposed ends forming the material which stains with 
 silver nitrate at the nodes of Ranvier. Nerve-cells in the sympathetic and periph- 
 eral ganglia take their origin from small collections of neuroblasts, which are split 
 off from the rudimentary spinal ganglia. Cells which are, originally, similar to 
 neuroblasts seem to give rise to neuroglia-cells, numerous processes sprouting from 
 the cell to form the neuroglial fibres. 
 
 Chemical Composition. — The amount of water in nervous tissue varies with 
 the situation. Thus in the gray matter of the cerebrum it constitutes about 83 per 
 cent., in the white matter from the 
 same region about 70 per cent., while 
 in the peripheral nerves, such as the 
 sciatic, it may fall to 60 per cent. 
 The solids consist of proteids (in 
 the gray matter proteids constitute 
 half the total solids), neurokeratin, 
 nuclein, protagon, lecithin, cerebro- 
 
 FiG. 523. — A small nervous branch from the 
 sympathetic of a mammal, a. Two medullated 
 nerve-fibres among a number of gray nerve-fibres, 6. 
 
 Fig. 524. — Transverse section through a microscopic 
 nerve, representing a compound nerve-bundle, sur- 
 rounded by perineurium. Magnified 120 diameters. 
 The medullated fibres are seen as circles with a cen- 
 tral dot — viz.. medullary sheath and axis-cylinder — in 
 transverse section. They are embedded in endoneurium, 
 containirig numerous nuclei, which belong to the con^ 
 nective-tissue cells of the latter, p. Perineurium, con- 
 sisting of lamina; of fibrous connective tissues, alter- 
 nating with flattened nucleated connective-tissue cells. 
 /. Lymph-space between epineurium and surface of 
 nerve-bundle. (Klein and Noble Smith.) 
 
 sides, cholesterin, nitrogenous extractives, and salts, with some gelatin and fat 
 from the adherent connective tissue. 
 
 The nervous structures are divided, as before mentioned, into two great systems 
 — viz., the cerebro-spinal, comprising the spinal cord and brain, the nerves con- 
 nected with these structures and the ganglia situated on them; and the sympa- 
 thetic, consisting of a double chain of ganglia and the nerves connected with thern. 
 All these structures require separate consideration ; they are composed of the two 
 kinds of nervous tissue above described, intermingled in various proportions, and 
 having, in some parts, a very intricate arrangement. 
 
 The nerves are round or flattened cords, formed of a number of nerve-fibres. 
 They are connected at one end with the cerebro-spinal centre or with the ganglia, 
 and are distributed at the other end to the various textures of the body; they 
 are subdivided into two great classes — the cerebro-spinal, which proceed from the 
 cerebro-spinal axis, and the S3rmpathetic or ganglionic nerves, which proceed from 
 the ganglia of the sympathetic. The cerebro-spinal nerves consist of numerous 
 
CHEMICAL COMPOSITION 825 
 
 nerve-fibres collected together and enclosed in a membranous sheath (Fig. 524). 
 A small bundle of primitive fibres, enclosed in a tubular sheath, is called a funiculus: 
 if the nerve is of small size, it may consist only of a single funiculus; but if large, 
 the funiculi are collected together into larger bundles or fasciculi, which are bound 
 together in a common membranous investment. 
 
 In structure the common membranous investment, or sheath of the whole nerve, 
 which is called the epineurium, as well as the septa given off from it, and which 
 separate the fasciculi, consists of connective tissue, composed of white and yellow 
 elastic fibres, the latter existing in great abundance. The tubular sheath of the 
 funiculi, called the perineurium, consists of a fine, smooth, transparent membrane, 
 which may be easily separated, in the form of a tube, from the fibres it encloses; 
 in structure it consists of connective tissue, which has a distinctly lamellar arrange- 
 ment, being composed of several lamella?, separated from each other by spaces 
 containing lymph. The nerve-fibres are held together and supported within the 
 funiculus by delicate connective tissue called the endoneurium. It is continuous 
 with septa which pass inward from the innermost layer of the perineurium, and 
 consists of a ground-substance in which are embedded fine bundles of fibrous 
 connective tissue which run for the most part longitudinally. It serves to support 
 the capillary vessels, which are arranged so as to form a network with elongated 
 meshes. The cerebro-spinal nerves consist almost exclusively of medullated nerve- 
 fibres the non-medullated existing in very small proportions. 
 
 The blood-vessels supplying a nerve terminate in a minute capillary plexus, 
 the vessels composing which pierce the perineurium and run, for the most part, 
 parallel with the fibres; they are connected together by short, transverse vessels, 
 forming narrow, oblong meshes, similar to the capillary system of muscle. Fine 
 non-medullated nerve-fibres accompany these capillary vessels, the vaso-motor 
 fibres, and break up into elementary fibrils, which form a network around the 
 vessel. Horsley has also demonstrated certain medullated fibres as running in the 
 epineurium and terminating in small spheroidal tactile corpuscles or end-bulbs of 
 Krause. These nerve-fibres, which Marshall believes to be sensory, and which he 
 has termed nervi nervorum, are considered by him to have an important bearing 
 upon certain neuralgic pains. 
 
 Nerves, in their course, subdivide into branches, and these frequently commu- 
 nicate with branches of a neighboring nerve. 
 
 The nerve-fibres, as far as is at present known, do not coalesce, but pursue an 
 uninterrupted course from the centre to the periphery. In separating a nerve, 
 however, into its component funiculi, it may be seen that they do not pursue a 
 perfectly insulated course, but occasionally join at a very acute angle with other 
 funiculi proceeding in the same direction; from this, branches are given off, to 
 join again in like manner with other funiculi. It must be distinctly understood, 
 however, that in these communications the nerve-fibres do not coalesce, but merely 
 pass into the sheath of the adjacent nerve, become intermixed with its nerve-fibres, 
 and again pass on, to become blended with the nerve-fibres in some adjoining 
 funiculus. 
 
 The communications which take place between two or more nerves form what 
 is called a plexus. Sometimes a plexus is formed by the primary branches of the 
 trunks of the nerves — as the cervical, brachial, lumbar, and sacral plexuses — and 
 occasionally by the terminal funiculi, as in the plexuses formed at the periphery 
 of the body. In the formation of a plexus the component nerves divide, then 
 join, and again subdivide in such a complex manner that the individual funiculi 
 become interlaced most intricately; so that each branch leaving a plexus may 
 contain filaments from each of the primary nervous trunks which form it. In the 
 formation also of smaller plexuses at the periphery of the body there is a free 
 interchange of the funiculi and primitive fibres. In each case, however, the 
 
826 THE NERVOUS SYSTEM 
 
 individual filaments remain separate and distinct, and do not inosculate with one 
 another. 
 
 It is probable that through this interchange of fibres the different branches 
 
 passing off from a plexus have a more extensive connection with the spinal cord 
 
 than if they each had proceeded to be distributed without such connection with 
 
 lother nerves. Consequently the parts supplied by these nerves have more extended 
 
 1 relations with the nervous centres; by this means, also, groups of muscles may be 
 
 associated for combined action. 
 
 The sympathetic nerves are constructed in the same manner as the cerebro- 
 spinal nerves, but consist mainly of non-medullated fibres, collected into funiculi, 
 and enclosed in a sheath of connective tissue. There is, however, in these nerves a 
 certain admixture of medullated fibres (Fig. 523), and the amount varies in different 
 nerves, and may be known by their color. Those branches of the sympathetic 
 which present a well-marked gray color are composed more especially of gelatinous 
 nerve-fibres, intermixed with a few medullated fibres; while those of a white 
 color contain more of the latter fibres and a few of the former. Occasionally, the 
 gray and white cords run together in a single nerve, without any intermixture, as 
 in the branches of communication between the sympathetic ganglia and the spinal 
 nerves, or in the communicating cords between the ganglia. 
 
 The nerve-fibres, both of the cerebro-spinal and sympathetic system, convey 
 impressions of a twofold kind. The sensory nerves, called also centripetal or 
 afferent nerves, transmit to the nervous centres impressions made upon the periph- 
 eral extremities of the nerves, and in this way the mind, through the medium 
 of the brain, becomes conscious of external objects. The motor nerves, called 
 also centrifugal or efferent nerves, transmit impressions from the nervous centres 
 to the parts to which the nerves are distributed, these impressions either exciting 
 muscular contraction, or influencing the processes of nutrition, growth, and 
 secretion. 
 
 Origin and Termination of Nerves. — By the expression "the termination of 
 nerve-fibres" is signified their connection with the nerve-centres, and with the 
 parts they supply. The former are sometimes called their origin, or central 
 termination; the latter their peripheral termination. The origin in some cases is 
 single — that is to say, the whole nerve emerges from the nervous centre by a single 
 root; in other instances the nerve arises by two or more roots, which come off 
 from different parts of the nerve-centre, sometimes widely apart from each other, 
 and it often happens, when a nerve arises in this way by two roots, that the 
 functions of these two roots are different; as, for example, in the spinal nerves, 
 each of which arises by two roots, the anterior of which is motor and the posterior 
 sensory. The point where the nerve-root or roots emerge from the nervous centre 
 is named the superficial or apparent origin, but the fibres of which the nerve con- 
 sists can be traced for a certain distance into the nervous centre to some portion 
 of the gray substance, which constitutes the deep or real origin of the nerve. 
 
 The manner in which these fibres arise at their deep origin varies with their 
 functions. The centrifugal or efferent nerve-fibres originate in the nerve-cells of 
 the gray substance, the axis-cylinder processes of these cells being prolonged to 
 form the fibres. In the case of the centripetal or afferent nerves the fibres grow 
 inward either from nerve-cells in the organs of special sense (e. g., the retina) 
 or from nerve-cells in the ganglia. Having entered the nerve-centre, they branch 
 and send their ultimate twigs among the cells, without, however, uniting with 
 them. 
 
 Peripheral Terminations of Nerves. — Nerve-fibres terminate peripherally in 
 various ways, and these may be conveniently studied in the sensory and motor 
 nerves, respectively. Sensory nerves would appear to terminate either in minute 
 primitive fibrillar or networks of fibrillae; or else in special terminal organs, which 
 
ORIGIN AND TERMINATION OF NERVES 
 
 827 
 
 have been termed peripheral end-organs, and of which tliere are several principal 
 varieties — viz., the end-bulbs of Krause, the tactile corpuscles of Wagner, the Pacinian 
 corpuscles, and the neuro-tendinous and neuro-muscular spindles. 
 
 Termination in Fibrillae. — When a medullated nerve-fibre approaches its termi- 
 nation, the white matter of Schwann suddenly disappears, leaving only the axis- 
 cylinder, surrounded by the neurilemma, and forming a non-medullated fibre. 
 This, after a time, loses its neurilemma, and consists only of an axis-cylinder, 
 which can be seen, in preparations stained with chloride of gold, to be made up 
 of fine varicose fibrils. Finally, the axis-cylinder breaks up into its constituent 
 primitive nerve-fibrillje, which often present regular varicosities and anastomose 
 with one another, thus forming a network. This network passes between the 
 elements of the tissue to which the nerves are distributed, which is always epithe- 
 lial, the nerve-fibrils lying in the interstitial substance between the epithelial cells, 
 and there terminating, though some observers maintain that the actual termina- 
 tions are within the cells. In this way nerve-fibres have been found to terminate 
 in the epithelium of the skin and mucous membranes, and in the anterior epithe- 
 lium of the cornea. 
 
 Fio. 525. — End-bulb of Krause. o. Medul- 
 lated nerve-fibre. b. Capsule of corpu.scle. 
 (From Klein's Elements of Histology.) 
 
 Fig. 526.— Tactile papilla of the hand treated with acetic 
 acid. Magnified 350 time.s. A. Side view of a papilla of the 
 hand. a. Cortical layer, h. Tactile corpuscle, with trans- 
 verse nuclei, c. Small nerve of the papilla, with neuri- 
 lemma, d. Its two nervous fibres running with spiral 
 coils around the tactile corpuscle, e. Apparent termina- 
 tion of one of these fibres. B. A tactile papilla seen from 
 above, so as to show its transverse section, a. Cortical 
 layer h. Nerve-fibre. _ c. Outer layer of the tactile body, 
 with nuclei, d. Clear interior substance. 
 
 The End-bulbs of Krause (Fig. 525) are minute cylindrical or oval bodies, con- 
 sisting of a capsule formed by the expansion of the connective-tissue sheath of a 
 medullated fibre, and containing a soft semifluid core in which the termination of 
 the axis-cylinder is situated, ending either as a bulbous extremity, or in a coiled- 
 up plexiform mass. End-bulbs are found in the conjunctiva of the eye, where 
 they are spheroidal in shape in man, but cylindrical in most other animals, in the 
 mucous membrane of the lips and tongue, and in the epineurium of nerve-trunks. 
 They are also found in the genital organs of both sexes, the penis in the male, 
 and the clitoris in the female. In this situation they have a mulberry-like appear- 
 ance, from being constricted by connective-tissue septa into from two to six 
 knob-like masses, and have received the name of genital corpuscles. Very similar 
 corpuscles are found in the epineurium of nerve-trunks. In the synovial mem- 
 brane of certain joints {e. cj., those of the fingers) rounded or oval end-bulbs have 
 been found; these are designated articular end-bulbs. 
 
 Tactile Corpuscles, known as Grandry's corpuscles, have been described by 
 Grandry as occurring in the papillae of the beak and tongue of birds, and by 
 Merkel as occurring in the papillae and epithelium of the skin of man and animals. 
 
828 
 
 THE NERVOUS SYSTEM 
 
 especially in those parts of the skin devoid of hair. They consist of a capsule com- 
 posed of a very delicate, nucleated membrane, and contain two or more granular, 
 somewhat flattened cells, between which the medullated nerve-fibre, which enters 
 the capsule by piercing its investing membrane, is supposed to terminate. 
 
 Meissner's corpuscles are the tactile corpuscles (Fig. 526), described by Wagner 
 and Meissner. They are oval-shaped bodies, made up of connective tissue, 
 and consisting of a capsule, and imperfect membranous septa, derived from it, 
 which penetrate its interior. The axis-cylinder of the medullated fibres passes 
 through the capsule, and having entered the corpuscle terminates in a small 
 globular or pyriform enlargement, near the inner surface of the capsule. These 
 tactile corpuscles have been described as occurring in the papillae of the corium 
 of the skin, hand, foot, front of the forearm, and skin of the lips, and the mucous 
 membrane of the tip of the tongue, the palpebral conjunctiva, and the skin of the 
 nipple. They are not found in all the papillae, but from their existence in those 
 parts in which the skin is highly sensitive, it is probable that they are especially 
 concerned in the sense of touch, though their absence from the papillae of other 
 tactile parts shows that they are not essential to this sense. They may be regarded 
 as end-bulbs. 
 
 Ruffini has described a special variety of nerve-ending in the subcutaneous 
 tissue of the human finger (Fig. 527). These are usually known as Ruffini's 
 
 Nerve-fibres. 
 
 Terminal ramifications 
 of axis-cylinder. 
 
 Fig. 527.— Nerve-ending of Ruffini. (After A. Ruffini, Arch. ital. de Biol., Turin, 1894, t. xxi.) 
 
 nerve -endings. They are principally situated at the junction of the corium with the 
 subcutaneous tissue; they are oval in shape, and consist of a strong connective- 
 tissue sheath, inside which the nerve-fibre divides into numerous branches, which 
 show varicosities and end in small free knobs. They resemble the corpuscles of 
 Golgi. 
 
 The Pacinian Corpuscles or Corpuscles of Vater (Fig. 528) are found in the 
 human subject chiefly on the nerves of the palm of the hand and sole of the 
 foot and in the genital organs of both sexes, lying in the subcutaneous tissue; 
 but they have also been described as connected with the nerves of the joints, 
 and in some other situations in the lower animals, as the mesentery of the 
 cat and along the tibia of the rabbit. Each of these corpuscles is attached 
 to and encloses the termination of a single nerve-fibre. The corpuscle which 
 is perfectly visible to the naked eye (and which can be most easily demon- 
 strated in the mesentery of a cat) consists of a number of lamellae or capsules, 
 arranged more or less concentrically around a central clear space, in which the 
 nerve-fibre is contained. Each lamella is composed of bundles of fine connective- 
 tissue fibres, and is lined on its inner surface by a single layer of cells. The central 
 clear space, which is elongated or cylindrical in shape, is filled with a transparent 
 material, in the middle of which is the single medullated fibre, which traverses 
 the space to near its distal extremity. Here it terminates in a rounded knob or 
 end, sometimes bifurcating previously, in which case each branch has a similar 
 
ORIGIN AND TERMINATION OF NERVES 
 
 829 
 
 arrangement. Todd and Bowman have described minute arteries as entering by 
 the sides of the nerves and forming capillary loops in the intercapsular spaces, 
 and even penetrating into the central space. 
 Other authors describe the artery as entering the 
 corpuscle at the pole opposite to the nerve-fibre. 
 
 Herbst has described a somewhat similar 
 "nerve-ending" to the Pacinian corpuscle, as 
 being found in the mucous membrane of the 
 tongue of the duck and in some other situations. 
 It differs, however, from the Pacinian corpuscles 
 in being smaller, its capsules thinner and more 
 closely approximated, and especially in the fact 
 that the axis-cylinder in the central clear space is 
 coated with a continuous row of nuclei. These 
 bodies are known as the corpuscles of Herbst. 
 
 Neuro-tendinous Spindles. — Hie nerves supplying 
 tendons have a special modification of the terminal 
 fibres, especially numerous at the point where the 
 tendon is becoming muscular. The tendon bundles 
 become enlarged, and the nerve-fibres — one, two, 
 or more in number — penetrate between the fas- 
 ciculi of the tendon and spread out between the 
 fibres to end in irregular disks or varicosities. A 
 spindle-shaped body is thus formed, composed of 
 tendon bundles and nerve-fibres, which is known 
 as the organ of Golgi (Fig. 529). 
 
 Neuro-muscular Spindles. — In the majority of 
 voluntary muscles there have been found special 
 end-organs consisting of a small bundle of pecu- 
 
 ,. , r.-, /• . e if»i \ 1 • capsular spaces, and one penetrates to 
 
 liar muscular nbres (mtraiusal nbres), embryonic the central capsule, t. The fibrous tis- 
 
 , • ill 1 •J.^ ' 1*1 sue of the stalk prolonged from the peri- 
 
 in type, invented by a capsule within which nerve- neurium. n. Nerve-tube advancing to 
 
 fibres, experimentally shown to be sensory in ^^Vtl?!;^'d''s'?rethinraK^he''^^^^^^^ 
 origin, terminate. These neuro-muscular spindles tube^cuw^enCfrgrmlnl'* " ^""^"^ ^^ * 
 vary in length from ^^ to ^ of an inch and have a 
 
 distinctly fusiform appearance. The large medullated nerve-fibres passing to the 
 end-organ are from one to three or four in number; entering the fibrous capsule 
 
 Fig. 528. — Pacinian corpuscle, with its 
 system of capsules and central cavity. 
 a. Arterial twig, ending in capillaries, 
 which form loops in some of the inter- 
 capsular 
 
 Organ of Golgi, showing Tendon bundles, 
 
 ramification of nerve-fibrils. 
 Muscular fibres. 
 Fig. 529. — Organ of Golgi (neuro-tendinous spindle) from the human tendon Achillis. (After Ciaccio.) 
 
 they divide several times^ and, losing their medulla, ultimately end in naked axis- 
 cylinders encircling the intrafusal fibres by flattened expansions, or irregular ovoid 
 
830 
 
 THE NERVOUS SYSTEM 
 
 or rounded disks (Fig. 530). Neuro-muscular spindles have not yet been demon- 
 strated in the tongue or eye muscles. 
 
 In the organs of special sense the nerves appear to terminate in cells which 
 belong to the epithelial class, and have received the name of sensory or nerve- 
 epithelium cells. This is not, however, the real state of the case; the nerve-fibre 
 is in reality a process from the epithelial cell, and terminates by branching around 
 a ganglion-cell. The stimulus carried by it is continued onward by an axis- 
 cylinder, derived from the ganglion, to the brain. These nerve-epithelium cells 
 must therefore be regarded as modified forms of nerve-cells. They will be more 
 particularly described in connection with the description of the organs of special 
 sense. 
 
 Motor nerves are to be traced either into unstriped or striped muscular fibres. 
 In the unstriped or involuntary muscles the nerves are derived from the sympa- 
 
 Dendritic branchings 
 
 Spirals. 
 
 Spirals.'/ 
 Fig. 530. — Middle third of a terminal plaque in the muscle spindle of an adult cat. (After Ruffinl.) 
 
 thetic, and are composed mainly of the non-medullated fibres. Near their termi- 
 nation they divide into a number of branches, which communicate and form an 
 intimate plexus. At the junction of the branches small triangular nuclear bodies, 
 the ganglion-cells, are situated. From these plexuses minute branches are given 
 off, which divide and break up into the ultimate fibrillse of which the nerve is com- 
 posed. These fibrillse course between the involuntary muscle-cells, and, according 
 to Elischer, terminate on the surface of the cell, opposite the nucleus, in a minute 
 swelling. Arnold and Frankenhiiuser believed that these ultimate fibrillse pene- 
 trated the muscular cell and ended in the nucleus. More recent observation, 
 however, has tended to disprove this. 
 
 In the striped or voluntary muscle the nerves supplying the muscular fibres are 
 derived from the cerebro-spinil nerves, and are composed mainly of medullated 
 fibres. The nerve, after entering the sheath of the muscle, breaks up into fibres, 
 or bundles of fibres, which form plexuses, and gradually divide until, as a rule, 
 a single nerve-fibre enters a single muscular fibre. Sometimes, however, if the 
 muscular fibre is long, more than one nerve-fibre enters it. Within the muscular 
 fibre the nerve-fibre terminates in a special expansion, called by Kuhne, who first 
 
ORIGIN AND TERMINATION OF NERVES 
 
 831 
 
 accurately described it, the motorial end-plates (Fig. 531)/ The nerve-fibre, 
 on approaching the muscular fibre, suddenly loses its white matter of Schwann, 
 which abruptly terminates; the neurilemma becomes continuous with the sarco- 
 
 FiG. 531. — Muscular fibres of Lacerta mridis with the terminations of nerves, a. Seen in profile, p p. The 
 nerve end-plates, s .s. The base of the plate, consisting of a granular mass with nuclei, b. The same as seen in 
 looking at a perfectly fresh fibre, the nervous ends being probably still excitable. (The forms of the variously 
 divided plate can hardly be represented in a wood-cut by sufficiently delicate and pale contours to reproduce 
 correctly what is seen in nature.) c. The same as seen two hours after death from poisoning by curare. 
 
 lemma of the muscle, and only the axis-cylinder enters the muscular fibre, where 
 it immediately spreads out, ramifying like the roots of a tree, immediately beneath 
 the sarcolemma, and is embedded in a layer of granular matter, containing a 
 number of clear, oblong nuclei, the 
 whole constituting an end-plate from 
 which the contractile wave of the mus- 
 cular fibre is said to start. 
 
 The Ganglia may be regarded as sepa- 
 rate small aggregations of nerve-cells, 
 connected with each other, with the 
 cerebro-spinal axis, and with the nerves 
 in various situations. They are found 
 on the posterior root of each of the 
 spinal nerves; on the posterior or sensory 
 root of the fifth cranial nerve; on the 
 facial and auditory nerves; and on the 
 glosso-pharyngeal and pneumogastric 
 nerves. They are also found in a con- 
 nected series along each side of the ver- 
 tebral column, forming the trunk of the 
 sympathetic; and on the branches of 
 that nerve, generally in the plexuses or 
 
 at the point of junction of two or more Fig. 532.— Section through a microscopic ganglion. 
 
 fibres which entered the ganglion are not represented. 
 The nerve-fibres are ordinary medullated fibres, but the 
 details of their structure are not shown, owing to the 
 low magnifying power. The ganglion-cells are invested 
 
 • , 1 1 ,1 • , 1 1 1 Magnified 300 diameters, c. Capsule of the ganglion 
 
 nerves with each other or with branches n. Nerve^fibres pa.s.sing out of the ganglion. The nerve- 
 
 of the cerebro-spinal system. On sec- 
 tion they are seen to consist of a reddish- 
 gray substance, traversed by numerous by speciaTcapsules lined by afew nuclei which are 
 <-'..•' •' here represented as il contained in the capsule. (Klein 
 
 white nerve-nbres; they vary consider- and Noble Smith.) 
 
 ably in form and size; the largest are 
 
 found in the cavity of the abdomen; the smallest, not visible to the naked eye, 
 
 exist in considerable numbers upon the nerves distributed to the difl'erent viscera. 
 
 ' They had, however, previously been noticed, though not accurately described, by Doydre, who named them 
 "nerve-hillocks." — Ed. of 15th English edition. 
 
832 THE NERVOUS SYSTEM 
 
 The ganglia are invested by a smooth and firm, closely adhering membranous 
 envelope, consisting of dense areolar tissue; this sheath is continuous with the 
 perineurium of the nerves, and sends numerous processes into the interior of the 
 ganglion, which support the blood-vessels supplying its substance. 
 
 In structure all ganglia are essentially similar (Fig. 532), consisting of the same 
 structural elements as the other nervous centres — viz., a collection of nerve-cells 
 and nerve-fibres. Each nerve-cell has a nucleated sheath, which is continuous 
 with the sheath of the nerve-fibre with which the cell is connected. The nerve- 
 cells in the ganglia of the spinal nerves are pyriform in shape, and have only one 
 process, the axis-cylinder or axone. A short distance from the cell, and while 
 still within the ganglion, this process divides in a T-shaped manner, one limb 
 of the cross-bar passing centrally and forming the central portion of a sensory 
 nerve-fibre; the other limb passing peripherally to form the axis-cylinder process 
 of the peripheral nerve-fibre. In the sympathetic ganglia the nerve-cells are 
 multipolar and have one axis-cylinder process or axone and several protoplasmic 
 processes or dendrons. The former of these emerges from the ganglion as a non- 
 medullated nerve-fibre. Similar cells are found in the ganglia connected with the 
 fifth cranial nerve, and these ganglia are therefore regarded by some as the cranial 
 portions of the sympathetic system. The nerve-cells are disposed in the ganglia 
 in groups of varying size, and these groups are separated from each other by 
 bundles of nerve-fibres, some of which traverse the ganglia without being con- 
 nected with the cells. 
 
 THE CEREBRO-SPINAL AXIS. 
 
 The cerebro-spinal axis consists of the spinal cord and the brain or encephalon, 
 which are contained within the skull and spinal canal. The spinal cord and its 
 coverings will be first considered, and then the brain and its membranes. 
 
 THE SPINAL CORD AND ITS MEMBRANES. 
 
 Dissection. — To dissect the cord and its membranes it will be necessary to lay open the 
 whole length of the spinal canal. For this purpose the muscles must be separated from the 
 vertebral grooves, so as to expose the spinous processes and laminie of the vertebrae; and the 
 latter must be sawed through on each side, close to the roots of the transverse processes, from 
 the third or fourth cervical vertebra above to the sacrum below. The vertebral arches having 
 been displaced by means of a chisel and the separate fragments removed, the dura mater will be 
 exposed, covered by a plexus of veins and a quantity of loose areolar tissue, often infiltrated with 
 serous fluid. The arches of the upper vertebrae are best divided by means of a strong pair of 
 cutting bone-forceps. 
 
 MEMBRANES OF THE CORD. 
 
 The membranes which envelop the spinal cord are three in number. The most 
 external is the dura mater, a strong fibrous membrane which forms a loose sheath 
 around the cord. The most internal is the pia mater, a cellulo-vascular membrane 
 which closely invests the entire surface of the cord. Between the two is the arach- 
 noid membrane, a non-vascular membrane which envelops the cord and is con- 
 nected to the pia mater by slender filaments of connective tissue. 
 
 The Spinal Dura Mater (Dura Mater Spinalis) (Figs. 533, 534, 535, 537). 
 
 I he spinal dura mater represents only the meningeal or supporting layer of 
 the cranial dura mater. The endocranial or endosteal layer ceases at the foramen 
 magnum posteriorly, but reaches as low as the third cervical vertebra in front; 
 below these levels its place is taken by the periosteum. The dura mater forms a 
 
THE SPINAL DUB A MATEB 
 
 833 
 
 loose sheath which surrounds the cord and the cauda equina, and is loosely con- 
 nected with the vertebral periosteum and the ligaments by a quantity of lax 
 areolar tissue and a plexus of veins, the meningo-rachidian veins (plexus venosi 
 vertehrales interni). The space containing the fat and veins is called the epidural 
 space (cavum epidurale) . The situation of the veins between the dura mater and the 
 periosteum of the vertebrae corresponds therefore to that of the cranial sinuses 
 between the endocranial and supporting layers. The dura is attached to the 
 circumference of the foramen magnum and to the axis and third cervical vertebra; 
 it is also fixed to the posterior common ligament, especially near the lower end of 
 the spinal canal, by fibrous slips; it extends below as far as the second or third 
 piece of the sacrum; here it becomes imper- 
 vious, and, ensheathing the filum terminale, 
 constitutes the filum durae matris spinalis (Fig. 
 537), and descends to the back of the coccyx, 
 to blend with the periosteum. This part of 
 the dura is called the coccygeal ligament, 
 
 I 
 
 ANTERIOR 
 NERVE ROOt 
 
 Dili 
 
 Fig. 533. — The spinal cord and its membranes. 
 
 Fig. 534— The dentate ligament. The dura 
 mater has been opened and turned back. The 
 anterior surface is seen. (Hirschfeld.) 
 
 (Fig. 537). The dura mater is much larger than is necessary for its contents, 
 and its size is greater in the cervical and lumbar regions than in the dorsal. 
 Its inner surface is smooth. On each side may be seen the double openings, 
 which transmit the two roots of the corresponding spinal nerve, the fibrous layer 
 of the dura mater being continued in the form of a tubular prolongation on 
 them as they pass through these apertures. These prolongations of the dura 
 mater are short in the upper part of the spine, but become gradually longer 
 below, forming a number of tubes of fibrous membrane, which enclose the sacral 
 nerves, and are contained in the spinal canal. 
 
 The chief peculiarities of the dura mater of the cord, as compared with that 
 investing the brain, are the following: 
 
 The dura mater of the cord is not closely adherent to the bones of the spinal 
 canal, and is not, as is the cerebral dura, the internal periosteum of the vertebrae. 
 The vertebrae have an independent periosteum. 
 
834 THE NERVOUS SYSTEM 
 
 It does not send partitions into the fissures of the cord, as the cerebral dura 
 sends partitions into certain fissures of the brain. 
 
 Its fibrous laminfE do not separate to form venous sinuses, as in the brain. 
 
 It contains no Pacchionian bodies. 
 
 Structure. — The dura mater consists of white fibrous and elastic tissue arranged 
 in bands or lamellte, which, for the most part, are parallel with one another and 
 have a longitudinal arrangement. Each surface is covered by a layer of endothelial 
 cells. It is sparingly supplied with vessels, and some few nerves have been traced 
 into it. 
 
 The Arachnoid Membrane (Arachnoidea Spinalis) (Figs. 533, 535). 
 
 The arachnoid is exposed by slitting up the dura mater and reflecting that 
 membrane to either side. It is a thin, delicate, tubular membrane which invests 
 the surface of the cord, and is connected to the pia mater by slender filaments 
 of connective tissue. Above, it is continuous with the cerebral arachnoid; on 
 each side it is continued on the various nerves, so as to form a sheath for them 
 as they pass outward to the intervertebral foramina. The outer surface of the 
 arachnoid is in contact with the inner surface of the dura mater, and the two 
 are, here and there, joined together by isolated connective-tissue trabeculse. These 
 trabecule are especially numerous on the posterior surface of the cord. For the 
 most part, however, the membranes are not connected together, and the interval 
 between them is named the subdural space (cavum suhdurale). The subdural 
 space contains a very small amount of lymph-like fluid. There is no com- 
 munication between the subdural space and the subarachnoid space. The sub- 
 dural space is prolonged outward for a short distance on each emerging nerve 
 and communicates with the lymph tract of the nerve. The inner surface of the 
 arachnoid is separated from the pia mater by a considerable interval, which is 
 called the subarachnoid or subarachnoidean space {cavum suharachnoideale) . The 
 space is largest at the lower part of the spinal canal, and encloses the mass 
 of nerves which form the cauda equina. Superiorly it is continuous with the 
 cranial subarachnoid space, and communicates with the general ventricular 
 cavity of the brain by means of openings in. the pia mater, in the roof of the 
 fourth ventricle, foramen of Majendie and foramina of Key and Retzius (p. 852). 
 It contains an abundant serous secretion, the cerebro-spinal fluid {liquor cerebro- 
 spinalis). This secretion is sufficient in amount to expand the arachnoid mem- 
 brane, and thus to distend completely the whole of the space included in the 
 dura mater. The subarachnoid space is occupied by trabeculae of delicate 
 endothelial covered connective tissue, connecting the pia mater on the one 
 hand with the arachnoid membrane on the other. This is named subarachnoid 
 tissue. 
 
 In addition to this the space is partially subdivided by a longitudinal mem- 
 branous partition, the septum posticum or the posterior fenestrated septum {septum 
 suharachnoideale), which serves to connect the arachnoid with the pia mater, 
 opposite the posterior median fissure of the spinal cord. It is a partition, but an 
 incomplete and cribriform partition, consists of bundles of white fibrous tissue 
 interlacing with each other, and is coated with endothelium. The ligamenta 
 denticulata, which run from the pia mater to the dura mater on either side of 
 the cord, divide the subarachnoid space into an anterior and a posterior space 
 {cavum suharachnoideale anterius et posterius), which join like spaces in the cavity 
 of the cranium. The medulli-spinal veins {venae spinales externae) lie in the sub- 
 arachnoid space. 
 
 Structure. — The arachnoid is a delicate membrane made up of closely 
 arranged interlacing bundles of connective tissue in several layers. It con- 
 
THE PI A MATER OF THE CORD 835 
 
 tains many elastic fibres, and is covered on each side by endothelial cells. 
 The arachnoid contains neither vessels or nerves. 
 
 The Pia Mater of the Cord (Pia Mater Spinalis). 
 
 The pia mater of the cord is exposed on the removal of the arachnoid (Figs. 533 
 and 535). It covers the entire surface of the cord, to which it is very intimately 
 adherent, forming its neurilemma, and sending a process downward into its ante- 
 rior fissure. It also forms a sheath for each of the filaments of the spinal nerves, 
 and invests the nerves themselves. A longitudinal fibrous band extends along the 
 middle line on its anterior surface, called by Haller the linea splendens; and a 
 somewhat similar band, the ligamentum denticulatum, is situated on each side. 
 At the point where the cord terminates the pia mater becomes contracted, and is 
 continued down as a long, slender filament, the filum terminale (Fig. 537), which 
 descends within the sheath of the dura and 
 
 the arachnoid and through the centre of the /^ Dura mater 
 
 mass of nerves forming the cauda equina. It 
 
 unites with the dura and arachnoid about the J^^V /^'■««*"o»a 
 
 level of the third sacral vertebra, and as the fnt^veT yit^Ss/ /^^^- '"""^ 
 
 central ligament of the spinal cord, the coccygeal \S<:^J^i^^^^ y^n<. root 
 
 ligament, or the filum durae matris spinalis the 
 fused membranes extend downward as far 
 as the base of the coccyx, where they blend 
 with the periosteum. It assists in maintain- 
 ing the cord in its position during the move- 
 ments of the trunk. It contains a little gray ^ /xjsv?>4'5»;'i?-v^ i 
 nervous substance, which may be traced for / ^'^^S'^^*^ ^««« vertebraiia 
 
 ]• , • , ., '' . 1 . Plexus venosvs 
 
 some distance into its upper part, and is ac- 
 
 . II II , 1 • i ■ Fro. 535. — Transverse section of the spinal cord 
 
 COmpanied by a small artery and vein. At and its membranes. (Gegenbauer.) 
 
 the upper part of the cord the pia mater pre- 
 sents a grayish, mottled tint, which is owing to yellow or brown pigment-cells 
 scattered among the elastic fibres. 
 
 Structure. — ^The pia mater of the cord is less vascular in structure, but thicker 
 and denser, than the pia mater of the brain, with which it is continuous. It 
 consists of two layers: an outer, resembling the arachnoid, composed of bundles 
 of connective-tissue fibres, arranged for the most part longitudinally; and an inner 
 (intima pia), consisting of stiff circular bundles of the same tissue, which present 
 peculiar angular bends. It is covered on both surfaces by a layer of endothelium. 
 Between the two layers are a number of cleft-like lymphatic spaces which com- 
 municate with the subarachnoid cavity, and a number of blood-vessels which are 
 enclosed in a perivascular sheath, derived from the inner layer of the pia mater, 
 into which the lymphatic spaces open. The pia mater contains the anterior spinal 
 artery and its branches, the two posterior spinal arteries, and numerous veins 
 which pass to the medulli-spinal veins. It is also supplied with nerves, which are 
 derived in part from the sympathetic and in part from the cerebro -spinal nerves. 
 These nerves supply the walls of the blood-vessels and enter the cord with the 
 vessels. 
 
 The Dentate Ligament (ligamentum denticulatum) (Figs. 533 and 534) is a narrow 
 fibrous band, situated on each side of the spinal cord, throughout its entire length, 
 running from the pia mater to the dura mater, and separating the anterior from the 
 posterior roots of the spinal nerves. It has received its name from the serrated 
 appearance which it presents. Its inner border is continuous with the pia mater 
 at the side of the cord. Its outer border presents a series of triangular, dentated 
 serrations, the points of which are fixed at intervals to the dura mater. These 
 
836 
 
 THE NERVOUS SYSTEM 
 
 
 Fio. 536. — Posterior view of the 
 spinal cord in situ. 
 
 serrations are twenty-one in number on each side, the 
 first being attached to the dura mater, opposite the 
 margin of the foramen magnum between the vertebral 
 artery and the hypoglossal nerve, and the last near the 
 lower end of the cord. Its use is to support the cord 
 in the fluid by which it is surrounded. 
 
 Surgical Anatomy. — Evidence of value in the diagnosis of 
 meningitis may be obtained by the operation of lumbar puncture, 
 that is, by puncturing the theca of the cord and withdrawing 
 some of the cerebro-spinal fluid, and the operation is regarded 
 by some as curative, under the supposition that the draining 
 away of the cerebro-spinal fluid relieves the patient by diminish- 
 ing the intracranial pressure. Lumbar puncture may give im- 
 portant diagnostic aid after a head injury by disclosing bloody 
 cerebro-spinal fluid. The operation is performed by inserting a 
 trocar, of the smallest size, below the level of the fourth lumbar 
 vertebra. In an adult the cord terminates at the lower border 
 of the first lumbar vertebra, and in a child opposite the body 
 of the third lumbar vertebra. The canal may be punctured 
 below the fourth vertebra without any risk of injuring its con- 
 tents. The point of puncture is indicated by laying the child on 
 its side and dropping a perpendicular line from the highest point 
 of the crest of the ilium; this will cross the upper border of the 
 spine of the fourth lumbar vertebra. In a child the puncture is 
 made just below the vertebral spine. In adults one-half an inch 
 to one side of the end of the vertebral spine. However the pre- 
 liminary puncture is made, the needle penetrates the dura in the 
 middle line. In entering the needle it should be directed up- 
 ward and forward in a child; upward, forward, and slightly 
 inward in an adult. 
 
 THE SPINAL CORD (MEDULLA SPINALIS) (Fig. 536). 
 
 The spinal cord is the cylindrical, elongated part of 
 the cerebro-spinal axis which is contained in the verte- 
 bral canal. Its length is usually about seventeen or 
 eighteen inches, and its weight, when divested of its 
 membranes and nerves, about one ounce and a half, 
 its proportion to the encephalon being about 1 to 33. 
 It does not nearly fill the canal in which it is con- 
 tained, its investing membranes being separated from 
 the surrounding walls by areolar tissue and a plexus of 
 veins. It occupies, in the adult, the upper two-thirds 
 of the vertebral canal, extending from the upper border 
 of the atlas to the lower border of the body of the first 
 lumbar vertebra, where it terminates in a slender fila- 
 ment of gray substance, which is continued for some 
 distance into the filum terminale (Fig. 537). In the 
 foetus, before the third month, it extends to the bottom 
 of the sacral canal, but after this period it gradually 
 recedes from below, as the growth of the bones com- 
 posing the canal is more rapid in proportion than that 
 of the cord, so that in the child at birth the cord extends 
 as far as the third lumbar vertebra. Its position varies 
 also according to the degree of curvature of the spinal 
 column, being raised somewhat in flexion of the spine. 
 The spinal cord is cylindrical, being somewhat flattened 
 
THE SPINAL COBD 
 
 837 
 
 anteriorly and posteriorly (Fig. 538). On examining its surface it presents a 
 difference in its diameter in different parts, being marked by two enlarge- 
 ments, an upper or cervical, and a lower or lumbar. The cervical enlargement 
 {intumescentia cervicalis) extends from about the third cervical to the first or 
 second dorsal vertebra; its greatest diameter is in the transverse direction (13 
 mm.), and it corresponds with the origin of the nerves which supply the upper 
 extremities. The lumbar enlargement {intumescentia lumbalis) is situated oppo- 
 site the last two or three dorsal vertebrte, and corresponds with the origin of 
 the nerves which supply the lower extremities. Below the lumbar enlargement 
 the cord gradually tapers to form a cone, the conus terminalis {conus medullaris), 
 the apex of which is continuous with the filum terminale. 
 
 FILUM 
 TERMINALt 
 
 I 
 
 Fig. 537. — The filum terminale. (Poirier and Charpy.) 
 
 Fissures and Grooves (Fig. 538).— It presents on its anterior or ventral sur- 
 face, along the middle line, a longitudinal fissure, the anterior median or ventro- 
 median fissm-e, and on its posterior or dorsal surface another fissure, which also 
 extends along the entire length of the cord, the posterior median or dorso-median 
 fissure or sulcus. These fissures penetrate through the greater part of the 
 thickness of the cord, and incompletely divide the cord into symmetrical 
 halves, united in the middle line by a transverse band of nervous substance, 
 the commissure. 
 
 The Anterior Median or Ventro-median Fissure (fissura mediana anterior) (Fig. 
 538). — The anterior median fissure is wider, but of less depth, than the posterior, 
 extending into the cord for about one-third of its thickness, and is deepest at the 
 
838 
 
 THE NERVOUS SYSTEM 
 
 lower part of the cord. It contains a prolongation from the pia mater, and its 
 floor is formed by the anterior or white commissure, which is perforated by numer- 
 ous blood-vessels passing to the centre of the cord. 
 
 The Posterior Median or Dorso-median Fissure or Sulcus (sulcus medianus pos- 
 terior) (Fig. 538). — The posterior median sulcus is not an actual fissure, as the 
 space between the lateral halves of the posterior part of the cord is crossed by 
 connective tissue and numerous blood-vessels, so that no actual hiatus exists, 
 and there is consequently no prolongation of the pia mater into it. It extends 
 into the cord to about one-half its width. The floor of the posterior median 
 sulcus is formed by the posterior or gray commissure. 
 
 Lateral Fissures. — On each side of the posterior median fissure, along the line 
 of attachment of the posterior roots of the nerves, a delicate fissure may be seen, 
 leading down to the gray matter which approaches the surface in this situation; 
 this is called the postero-lateral or dorso-lateral sulcus or fissure of the spinal cord 
 (sulcus lateralis posterior). On the posterior surface of the spinal cord, between 
 
 VENTRAL AAEDIAN 
 FISSURE 
 
 VENTRAL ROOTS 
 
 VENTRAL HORN 
 
 LATERAL HORN 
 
 RETICULAR 
 FORMATION 
 
 DORSAL HORN 
 
 DORSO-LATERAL 
 FISSURE 
 
 DORSAL ROOTS 
 
 'LUMN 
 
 DORSAL MEDIAN 
 FISSURE 
 
 Fig. 538. — Transverse section of the spinal cord at the middle of the thoracic region. The neuroglia septum 
 has been removed from between the dorsal columns. (Testut, after Pierret.) 
 
 the posterior median fissure and the postero-lateral fissure on each side, is a slight 
 longitudinal furrow, the posterior intermediate furrow or the posterior paramedian 
 groove (sulcus intermedins posterior), marking off two slender tracts, the postero- 
 median and postero-lateral columns. These are most distinct in the cervical 
 region, but are stated by Foville to exist throughout the whole length of the 
 cord. On each side of the anterior median fissure the anterior roots of the spinal 
 nerves emerge from the cord, not in one vertical line, but by separate bundles 
 which occupy an area of some width. This is called, by some anatomists, the 
 antero-lateral fissure of the cord (sulcus lateralis anterior), although no actual 
 fissure exists in this situation. 
 
 Columns of the Cord (funiculi medtdlae spinalis) (Figs. 538 and 539).— Each 
 half of the spinal cord is thus divided into four columns: an anterior column, a lateral 
 column, a posterior column, and a postero-median column. This division, however, is 
 very imperfect, since the limit between the so-called anterior and lateral columns 
 cannot be defined on account of the bundles of the anterior roots being spread over 
 
THE SPINAL CORD 839 
 
 a considerable area. It is therefore customary to divide each half of the spinal cord 
 into two columns, separated by the postero-lateral sulcus: (1) a small posterior 
 column (funiculus posterior), which is bounded internally by the posterior median 
 fissure, and externally by the postero-lateral sulcus, and the posterior column is 
 subdivided by the posterior intermediate septum into an outer portion, the column 
 or tract of Burdach {fasciculus cuneatu^) , and an inner portion, the column or tract 
 of GoU {fasciculus gracilis)', (2) a large antero-lateral column, which comprises 
 the rest of the cord. The antero-lateral column is divided arbitrarily into the 
 lateral column (funiculus lateralis) and the anterior column (funiculus anterior). 
 
 Structure of the Cord (Fig. 538). — If a transverse section of the spinal cord 
 be made, it will be seen to consist of white and gray nervous substance. The 
 white matter is situated externally, and constitutes the greater part. The gray 
 substance occupies the centre, and is so arranged as to present on the surface of 
 the section two crescentic masses, placed one in each lateral half of the cord, united 
 together by a transverse band of gray matter, the gray commissure. Each cres- 
 centic mass has an anterior or ventral horn (coluvma grisea anterior) and a posterior 
 or dorsal horn (columna grisea posterior). The posterior horn is long and narrow, and 
 approaches the surface of the postero-lateral fissure, near which it presents a slight 
 enlargement, the caput comu; from this it tapers to form the apex comu {apex 
 columna grisea posterior), which at the surface of the cord becomes continuous 
 with some of the fibres of the posterior roots of the spinal nerves. The constriction 
 near the gray commissure is called the cervix comu (cervix columna grisea posterior). 
 The anterior horn is short and thick, and does not quite reach the surface, but 
 extends toward the point of attachment of the anterior roots of the nerves. Its 
 margin presents a dentate or stellate appearance. What is known as the lateral 
 horn (columna grisea lateralis) projects from the outer aspect of the gray matter 
 nearly on the line of the gray commissure. It is distinct in the upper dorsal region ; 
 in the cervical enlargement it is merged in the anterior horn, but it reappears in 
 the upper cervical region. In the lumbar region it merges with the anterior horn. 
 Owing to the projections toward the surface of the anterior and posterior horns 
 of the gray matter, each half of the cord is divided by the gray matter, more or 
 less completely, into three columns, anterior, middle, and posterior, the anterior 
 and middle being joined to form the antero-lateral column, as the anterior horn 
 does not quite reach the surface. 
 
 The Commissure of the Spinal Cord. — The commissure of the spinal cord is com- 
 posed of white and gray matter, and is therefore divided into the white and gray 
 commissure. 
 
 The Anterior or White Commissure (commissura anterior alba) is situated at the 
 bottom of the anterior median fissure, and is formed of medullated nerve-fibres, 
 which pass between the gray matter of the anterior horn and the anterior and 
 lateral white columns of one side into similar parts on the other side. The 
 fibres are oblique in direction; many which enter at the posterior part of the 
 commissure on the one side leave it at the anterior part of the commissure on the 
 other, and vice versa, a decussation taking place in the middle line. 
 
 The Posterior or Gray Commissure (commissura grisea), which connects the two 
 crescentic masses of gray matter, is separated from the bottom of the anterior 
 median fissure by the anterior white commissure. It consists of transverse 
 medullated nerve-fibres, with a considerable quantity of neuroglia between them. 
 The fibres w^hen they reach the lateral crescents diverge : some pass backward to 
 the posterior roots; others spread out, at various angles, into the crescent. The 
 portion of the gray commissure in front of the central canal is called the anterior 
 gray commissure (commissura grisea anterior) ; the portion behind the central canal 
 is called the posterior gray commissure (commissura grisea posterior). 
 
 Running through the gray commissure of the whole length of the cord is a 
 
840 THE NERVOUS SYSTEM 
 
 minute canal, which is barely visible to the naked eye in the human cord, but is 
 proportionately larger in some of the lower vertebrata. It is called the central 
 canal (canalis centralis); it opens above into the fourth ventricle, and terminates 
 below in a somewhat dilated extremity, the inferior rhomboid fossa (fossa rhom- 
 boidea inferior). It is surrounded by an area of neuroglia, which, in the recent 
 state, has a gelatinous appearance, and in which there are no nerve-fibres. This 
 is sometimes called the substantia gelatinosa centralis. When hardened in alcohol 
 or chromic salts it has a finely reticulated appearance. The canal is lined in the 
 foetus by columnar ciliated epithelium, but in the adult the cilia have disappeared, 
 and the canal is filled with their remains. 
 
 The mode of arrangement of the gray matter, and its amount in proportion to 
 the white, vary in different parts of the cord. Thus, the posterior horns are long 
 and narrow in the cervical region; short and narrower in the dorsal; short, but 
 wider, in the lumbar region. In the cervical region the crescentic portions are 
 small, and the white matter more abundant than in any other region of the cord. 
 In the dorsal region the gray matter is least developed, the white matter being 
 also small in quantity. In the lumbar region the gray matter is more abundant 
 than in any other region of the cord. Toward the lower end of the cord the white 
 matter gradually ceases. The crescentic portions of the gray matter soon blend 
 into a single mass, which forms the only constituent of the extreme point of the 
 cord. 
 
 Blood Supply of the Cord. — Spinal branches are given off by the vertebral, 
 ascending cervical, deep cervical, intercostal, lumbar, lumbar branches of the ilio- 
 lumbar, lateral and middle sacral arteries.^ Many of these spinal arteries give 
 branches to the cord and the branches reach the cord in the spinal nerve-roots 
 and form three vascular chains in the cord. The arteries of the cord are the 
 anterior spinal and the two posterior spinal, which take origin from the vertebral 
 arteries (pp. 638 and 639). The anterior spinal lies at the surface of the anterior 
 median fissure. The posterior spinal arteries descend on either side of the cord 
 behind the posterior nerve-roots. The central supply of the cord is chiefly from 
 the anterior spinal artery. It sends sulcal branches inward in the fissure toward 
 the cord, and branches of these vessels enter the cord. The vessels of the cord 
 are terminal arteries. The gray matter is chiefly supplied by the anterior spinal, 
 partly by the posterior spinal. The white matter is supplied by both vessels. From 
 the interior of the cord blood is brought by fissural veins (which emerge from the 
 fissures), root-veins (which emerge with the fibres of the anterior and posterior 
 roots), and a few veins which emerge from different parts of the surface of the 
 cord. These vessels unite to form the meduUi-spinal plexus, which is between the 
 pia mater and the arachnoid membrane. (See Spinal Veins.) 
 
 Lymphatics. — There are no lymph-vessels in the cord, but l\Tnph is collected by 
 perivascular lymph-spaces and by spaces about the nerve-fibres. 
 
 Minute Anatomy of the Cord. — The cord consists of an outer part, composed 
 of medullated nerve-fibres, which is the white substance ; and of a central part, the 
 gray matter, both supported in a stroma. 
 
 The stroma is composed of connective tissue, which is derived from the pia by 
 ingrowth, and hence is of mesodermic origin, and of neurogUa. 
 
 The Neuroglia. — ^The neuroglia consists of a homogeneous transparent matrix, 
 of a network of very delicate fibrillae, and of small stellate or branched cells, the 
 neuroglia-cells. 
 
 It takes origin from cells which were derived from the large columnar cells of 
 the wall of the neural canal, and hence is of epithelial origin. 
 
 „\^ Manual of Practical Anatomy. By the late Prof. Alfred W. Hughes. Edited and completed by Arthur 
 
THE SPINAL COBD 
 
 841 
 
 In addition to forming a ground substance, in which the nerve-fibres, nerve- 
 cells, and blood-vessels are embedded, a considerable accumulation of neuroglia 
 takes place in three situations: (1) on the surface of the cord, beneath the pia 
 mater; (2) around the central canal, the substantia gelatinosa centralis; and (3) 
 as a cap over the extremity of the posterior horn, forming the substantia cinerea 
 gelatinosa. 
 
 The White Substance of the Cord (substantia alba). — The white substance of the 
 cord is placed at the periphery and in the anterior commissure. It consists of 
 medullated nerve-fibres, mostly disposed longitudinally, with blood-vessels and 
 neuroglia, sustained by a network of connective tissue from the pia. When stained 
 with carmine it presents a very striking appearance on transverse section. It is 
 seen to be studded all over with minute dots, surrounded by white areas. This 
 is due to the longitudinal medullated fibres seen on section. Each dot is an axis- 
 cylinder, the white area about it is the substance of Schwann. Externally, the 
 neuroglia forms a sheath closely in- 
 vesting the outer surface of the cord 
 immediately beneath the pia mater; 
 from it numerous septa pass in- 
 ward and separate the respective 
 bundles of fibres and extend between 
 the individual nerve-fibres, acting 
 as a supporting medium, in which 
 they are embedded. There are 
 transverse, oblique or dorso-ventral 
 and longitudinal fibres in the white 
 substance. 
 
 Transverse Fibres. — These fibres 
 pass between the longitudinal tracts 
 of the cord and the gray matter. 
 They constitute the anterior or 
 white commissure, which joins the 
 anterior and lateral white columns 
 and the anterior gray horn of one side 
 to like parts of the opposite side. 
 
 As previously stated, it is in front 
 of the gray commissure, and is the 
 floor of the anterior median fissure. 
 It contains four sets of fibres: (1) 
 those belonging to the direct pyram- 
 idal tract, (2) those belonging to the 
 antero-lateral ground bundle, (3) those belonging to the antero-lateral ascending 
 cerebellar tract, (4) crossed fibres to the anterior spinal nerve-roots.^ 
 
 Oblique or Dorso-ventral Fibres. — These are the anterior root-fibres passing from 
 the anterior gray horn to the periphery of the cord and the posterior root-fibres 
 passing from the periphery of the cord to the posterior gray horn. 
 
 Longitudinal Fibres. — They constitute the conducting tracts (Fig. 539). 
 
 It is impossible to trace the course of the nerve-fibres in their passage through 
 the cord; but the investigation of pathological lesions has shown that the white 
 matter of the cord consists of certain columns or tracts of fibres; for it has been 
 found that certain lesions are strictly limited to certain well-determined parts of 
 the cord without involving neighboring regions. That these parts or fasciculi 
 correspond to so many distinct anatomical systems, each endowed with special 
 
 Fig. 539. — Columns of the cord. 
 
 ' Santee. The Anatomy of the Brain and Spinal Cord. 
 
 I 
 
842 THE NERVOUS SYSTEM 
 
 functions, seems abundantly proved by the researches of Flechsig and others on 
 the development of the spinal cord during the later periods of utero-gestation and 
 in the newly born infant. By these researches several tracts can be traced along 
 the greater part of the cord and into or from the encephalon (Fig. 539). Thus ( 1) in 
 the antero-lateral column of the cord, on either side of the anterior median fissure, a 
 portion of the column may be divided off as the uncrossed or direct pyramidal tract 
 or the fasciculus of Turck (fasciculus cerebrospinalis anterior [ventralis]) . This tract 
 is a continuation of the corresponding tract in the medulla. It is only found in the 
 upper part of the cord; it gradually diminishes as it is traced downward, and dis- 
 appears about the middle of the dorsal region. It consists of centrifugal or descend- 
 ing fibres which can be traced downward from the pyramid of the medulla of the 
 same side, and are derived from the motor area of the cerebral cortex. The fibres 
 of this tract decussate in their course down the cord, passing across the middle 
 line through the anterior white commissure and terminating in the anterior gray 
 horn of the opposite side; this explains the gradual diminution and eventual dis- 
 appearance of the tract. (2) In the hinder part of the antero-lateral column is a 
 somewhat triangular area, larger than the preceding, which is named the crossed 
 pyramidal tract (fasciculus cerebrospinalis lateralis). In the cervical and dorsal 
 regions the crossed pyramidal tract is overlaid by the direct cerebellar tract, but 
 in the lumbar cord it is at the surface. This also consists of descending fibres, 
 which are derived from the pyramid of the medulla of the opposite side, and 
 which have crossed in the decussation of the pyramids. After crossing in the 
 medulla the fibres descend and terminate about the cells in the anterior cornu 
 of the same side as the column. The fibres are derived from the motor area 
 of the cerebral cortex of the opposite side. Thus it will be seen that all the 
 fibres from the motor area, which descend through the internal capsule, the crus 
 cerebri, and the pons Varolii to the pyramidal body of the medulla, decussate. 
 Some decussate in the lower part of the medulla, and descend through it as the 
 crossed pyramidal tract. Others do not decussate in the medulla but descend as the 
 direct pyramidal tract and cross through the anterior commissure of the cord to ter- 
 minate in the anterior gray horn of the opposite side, where the fibres end by forming 
 synapses around its cells. Investigations render it probable that the crossed pyram- 
 idal tract contains some fibres from the main pyramidal tract in the medulla, which 
 have descended from the corresponding side of the brain undecussated and terminate 
 about the cells of the gray cornu of the same side of the cord. The crossed descending 
 tract of the red nucleus is found within the crossed pyramidal tract at the junction of 
 its lateral and dorsal portions. This tract from the opposite red nucleus reaches 
 the lumbar cord and ends in the gray matter. (3) The antero-lateral tract is an 
 extensive crescent-shaped strand which skirts the circumference of the anterior 
 three-quarters of the antero-lateral colunm of the cord. Behind, where it is 
 thickest, it lies in the angle formed by the direct cerebellar and crossed pyramidal 
 tracts, becoming narrower as it passes forward toward the direct pyramidal tract. 
 It contains two sets of fibres, centripetal or ascending, and centrifugal or descend- 
 ing, and hence is divided into two tracts, the antero-lateral ascending and the 
 antero-lateral descending cerebellar tracts, (a) The antero-lateral ascending cerebellar 
 tract or the column of Gowers (fasciculus anterolateralis superficialis ascendens) 
 is chiefly in the posterior part of the antero-lateral tract, although some of its 
 fibres mingle with the descending tract. The axones which compose this tract 
 arise from cells in the central gray matter and the gray matter of the base of the 
 anterior horn, chiefly from the opposite side of the cord (Santee), most of the 
 fibres crossing soon after their beginning by way of the anterior commissure. The 
 fibres of the column of Gowers pass through the dorsal portion of the lateral region 
 of the medulla (sending nerve fibres to the lateral nucleus) and the formatio reticu- 
 laris of the pons, turn backward over the superior peduncle of the cerebellum, and 
 
THE SPINAL CORD 843 
 
 pass into the superior vermis through the valve of Yieussens (San tee, from Hoche). 
 Between the ascending and descending tracts is the olivary bundle of the cord or the 
 triangular tract of Helwig (tractus triangularis [Helwigi]) . It arises in the lumbar cord 
 and terminates in the olive of the medulla, (b) The antero-lateral descending cere- 
 bellar tract or the column of Marchi and Lowenthal (Jasciculus anterolateralis super- 
 ficialis descendens) is situated chiefly in the anterior portion of the antero-lateral 
 tract, but some of its fibres are scattered among the fibres of Gowers' column. The 
 axones of the descending tract are derived from Purkinjean cells in the cerebellar 
 cortex. The fibres pass through the inferior peduncle of the cerebellum and the 
 lateral region of the medulla and terminate in the anterior gray horn. (4) The 
 direct cerebellar or dorso-lateral cerebellar tract (fasciculus cerebellospinalis) is situ- 
 ated at the circumference of the cord behind the preceding and external to the 
 crossed pyramidal tract, occupying a narrow area which extends backward as far 
 as the postero-lateral fissure or nearly so. It commences at the upper level of the 
 lumbar cord. Below this level it is absent, and where it is absent the crossed pyram- 
 idal tract reaches the surface. As the direct cerebellar tract ascends it increases in 
 size. It passes through the restiform body of the medulla and terminates in the 
 superior vermis of the cerebellum. Its fibres are derived from the cells of the 
 posterior vesicular column of Clarke in the gray matter of the cord. (5) Close to 
 the point where the posterior roots enter the cord, in the antero-lateral column, is 
 a small collection of fibres, which is known as the marginal tract of Spitzka and 
 Lissauer (fasciculus marginalis) ; it is formed by some of the outer fibres of the 
 posterior roots which run upward in the tract for a short distance, and end about 
 the cell-bodies of the substantia gelatinosa (Santee). (6) The rest of the antero- 
 lateral column of the spinal cord is occupied by the antero-lateral ground bundle 
 (fasciculus proprius anterolateralis). It surrounds the anterior cornu and sepa- 
 rates the antero-lateral tract and the crossed pyramidal tract from the gray matter 
 of the cord. Nowhere does it reach the surface of the cord, but at one place it very 
 closely approaches it. The direct pyramidal tract separates it from the antero- 
 median fissure. The fibres are very short and are commissural and associative. 
 The portion of the ground bundle in the anterior column is chiefly coinmissural, 
 its fibres passing between the anterior cornua. The portion in the lateral column 
 is chiefly for association, its fibres joining different areas of the cord on the same 
 side. It consists of (a) longitudinal fibres. A posterior longitudinal bundle (fas- 
 ciculus longitudinalis medialis) ,vfh\Qh. ascends to reach the motor nuclei of cranial 
 nerves and the subthalamic region. An anterior longitudinal bundle (fasciculus 
 veniralis) passes from the superior corpus quadrigeminum to the cilio-spinal and 
 other centres (Santee). Longitudinal commissural fibres, which unite the groups 
 of cells in the gray matter with one another; (b) of fibres which pass across the 
 anterior commissure from the gray matter of the opposite side; and (c) horizontal 
 fibres belonging to the anterior roots of the nerves, which pass through it before 
 leaving the cord. In the posterior column of the cord there are two definite tracts. 
 They are marked off fr6m each other by the posterior intermediate furrow on the 
 surface of the cord. The part which has been described previously as the posterior 
 median column pretty nearly corresponds to the one tract, the tract of GoU, and 
 the remainder of the posterior column corresponds to the other, the tract of Bur- 
 dach. (7) The postero-median tract or tract of GoU (fasciculus gracilis) increases 
 as it ascends, and consists of long, but small, fibres derived from the posterior 
 roots of the spinal nerves, which ascend to the medulla oblongata, the fascic- 
 ulus gracilis of the medulla, and end in the nucleus gracilis. Some fibres leave 
 the tract and end in the gray matter of the cord. A few fibres pass to the 
 thalamus and a few to the cerebellum. (8) The postero-lateral tract or the tract 
 of Burdach (fasciculus cuneatus) consists of shorter, but larger, fibres than the 
 preceding; they are derived from the posterior roots and from cells in the gray 
 
844 THE NERVOUS SYSTEM 
 
 matter of the cord; some ascend only for a short distance in the tract and then 
 enter the gray matter and come into close relationship with the cells of the pos- 
 terior vesicular column of Clarke; others incline toward the mesial plane, and, 
 entering Goll's column, can be traced as far as the medulla. The tract of Burdach 
 becomes in the medulla the fasciculus cuneatus and the fasciculus of Rolando. 
 Some of its fibres continue along the interolivary fillet, others along the arciform 
 fibres, and some terminate in the gray matter of the cord (Santee). In the cervical 
 and upper dorsal regions there is contained in the substance of Burdach's column 
 a small strand of fibres, called the descending comma tract. It presents, on trans- 
 verse section, the appearance of a comma, the blunt extremity of which is directed 
 forward. The fibres forming it probably represent in part descending portions of 
 the dorsal nerve-roots, together with descending commissural fibres within the 
 cord itself. 
 
 What is known as the comu commissural tract is in the lumbar and lower dorsal 
 regions, between the posterior cornu and the gray commissure. The septo- 
 marginal tract is only found in a portion of the lumbar cord. It is between the 
 septum and the dorsal surface of the cord (Santee). 
 
 Functions of the Various Tracts in the Cord. — 1. The direct pyramidal 
 tract is motor, and conveys impulses chiefly to the arms and trunk. It conducts 
 motor impulses from the cerebral cortex of one side, along the spinal cord of the 
 same side, and to the multipolar nerve-cells of the anterior horn of the opposite 
 side of the cord. A given muscular region is supplied chiefly by the crossed 
 pyramidal tract of the corresponding side of the cord and partly by the direct 
 pyramidal tract of the opposite side of the cord, but both tracts are innervated 
 by the same brain area. It is further to be remembered that there are prob- 
 ably direct or uncrossed fibres in the crossed pyramidal tracts of the cord which 
 convey motor impulse from the cortex to muscles of the same side. 
 
 2. The crossed pyramidal tract conveys motor impulses and impulses which 
 control reflex movements. It descends from the cortex, decussates in the lower 
 part of the medulla, and descends in the cord on the side opposite to the brain area 
 from which it arose. It supplies muscles on the same side of the body as the tract 
 is of the cord. This tract also contains a few uncrossed fibres from the same side 
 of the brain. Hence the muscles of one side receive their chief innervation from 
 the opposite side of the brain by way of the crossed and the direct pyramidal tracts, 
 but receive some slight innervation from the same side of the brain by way of the 
 direct fibres in the crossed pyramidal tract. Gowers^ says: "There is abundant 
 evidence that each hemisphere of the brain is connected with both legs, although 
 chiefly with that of the opposite side. There is also a similar and even more 
 equal connection with the trunk muscles, and a slighter connection with certain 
 muscles of the arm. Such muscles invariably regain some power on the paralyzed 
 side, even with a complete interruption to the motor path, and they are weakened 
 on the unparalyzed side." 
 
 3. The antero-lateral descending cerebellar tract is a ''segment of an indirect 
 motor path" (Santee). The antero-lateral ascending cerebellar tract conveys 
 impressions of temperature and pain. 
 
 4. The direct cerebellar tract conveys impressions of equilibrium, particularly 
 from the viscera. 
 
 5. The antero-lateral ground bundle is associative between the anterior cornua 
 and is commissural between different segments of the cord. These commissural 
 and associative connections are of great importance, for if the regular route of 
 nervous conduction is interrupted they may serve to convey the nerve current 
 around the block. 
 
 ' Diseases of the Nervous System. 
 
THE SPINAL CORD 845 
 
 6. The marginal tract of Spitzka and Lissauer is composed of ascending fibres 
 from the posterior nerve-roots. 
 
 7. The postero-lateral tract conveys impressions of common sensation. 
 
 8. The postero-median tract conveys impressions of muscular sense. 
 
 The Gray Substance of the Cord {substantia grisea). — The gray substance of the 
 cord occupies its central part in the shape of two crescentic horns, joined together 
 by the gray commissure. Each of these crescents has an anterior or ventral and 
 a posterior or dorsal comu. 
 
 The Posterior or Dorsal Horn (columna grisea posterior) consists of a slightly nar- 
 rowed portion, at its base, where it is connected with the rest of the gray substance 
 — this is, the cervix comu; from this it gradually expands into the main part of the 
 horn, the caput comu, and tapers to form the apex comu; around its extremity is a 
 lamina or layer of gelatinous material, which covers the head like a cap, and 
 from this it tapers almost to a point, which approaches the surface of the cord at 
 the postero-lateral groove. 
 
 The gelatinous substance is a peculiar accumulation of neuroglia (Klein) 
 similar to that found around the central canal, and has been named by Rolando 
 the substantia cinerea gelatinosa. It probably takes its origin from the columnar 
 cells which line the posterior part of the embryonic spinal canal. 
 
 The Anterior or Ventral Hom of the Gray Substance (columna grisea anterior) in 
 the cervical and lumbar swellings, where it gives origin to the motor nerves of the 
 extremities, is much larger than in any other region, and contains several distinct 
 groups of large and variously shaped cells. 
 
 In addition to this, a lateral horn (columna grisea lateralis) is found projecting 
 outward from the lateral region of the gray matter on a level with the gray com- 
 missure in the upper part of the dorsal region of the cord; in the cervical and 
 lumbar regions this lateral horn blends with the anterior horn, which thus becomes 
 broad and expanded. From the concavity of the crescent, between the anterior 
 and posterior horns, processes of gray matter extend into the white substance, 
 where they divide and anastomose to form a network, termed the formatio reticu- 
 laris. 
 
 The gray commissure contains the central canal (canalis centralis), and is situated 
 behind the white commissure, which separates it from the bottom of the anterior 
 median fissure. 
 
 The gray substance of the cord is composed of — (1) the substantia gelatinosa, 
 which envelops the head of the posterior horn and which encircles the central canal 
 of the cord; (2) the substantia spongiosa, which forms the crescentic horns (except 
 the heads of the posterior horns and the envelope of the central canal). Further, 
 it may be stated that the gray matter consists of nerve-fibres of variable but 
 smaller average diameter than those of the white column; (3) nerve-cells of various 
 shapes and sizes, with from two to eight processes; (4) blood-vessels and con- 
 nective tissue. 
 
 The nerve- fibres of the gray matter of the posterior horn are for the most part 
 composed of a dense interlacement of minute fibrils, intermingled with nerves 
 of a larger size. This interlacement is formed partly by the axones and dendrites 
 of the cells of the gray matter, and partly by fibres which enter the gray matter 
 and which come from various sources. 
 
 The nerve-cells of the gray matter are collected into groups as seen on trans- 
 verse section, but they really form columns of cells placed longitudinally; or else 
 they are found scattered throughout the whole of the gray matter. 
 
 In the anterior horn the cells consist of two chief groups; one medial, the more 
 constant, near the anterior column; the other lateral, near the lateral column. 
 The axones of these cells constitute the bulk of the anterior roots of the spinal 
 nerves. The spinal nerves obtain axones from the entire lateral gray column and 
 
 k 
 
846 
 
 THE NERVOUS SYSTEM 
 
 from part of the medial gray column of the same side, and also from the gray 
 matter of the medial column of the opposite side by way of the white commissure. 
 The nerve-fibres from these cells are distributed to the muscles of the trunk and 
 extremities. A second lateral group is present in the cervical and lumbar enlarge- 
 ments. In the centre of the gray crescent (substantia intermedia grisea) the cells 
 are collected into three groups or columns. The intermedio-lateral column runs 
 throughout the length of the cord, but is most distinct in the thoracic region. Its 
 cells are in relation with fibres from the posterior nerve-roots and send off axones 
 to the anterior nerve-roots. It is believed by Morris and others that these fibres are 
 sympathetic and pass to glands and blood-vessels. Other axones enter the antero- 
 lateral ascending cerebellar tract (San tee). The middle column is most distinct in the 
 cervical cord. It certainly receives fibres from the posterior roots, and possibly 
 sends fibres to the antero-lateral ascending cerebellar tract. At the base of the pos- 
 terior horn on its inner side, adjoining the gray commissure, is a group of nerve- 
 cells, called Clarke's posterior or dorsal column or Clarke's vesicular column {nucleus 
 dorsalis) , which extends from the 
 eighth cervical to the second lum- 
 bar nerve. In the cervical and 
 lumbar cord the nuclei of Stilling 
 are its representatives, and in the 
 medulla the accessory cuneate nu- 
 cleus represents it. This column 
 
 Fig. 540. 
 
 -Formation of a spinal nerve. 
 (Testut.) 
 
 Fig. 541. — Dorsal roots entering cord and dividing into ascend- 
 ing and descending branches, a. Stem-iibre. b, b. Ascending and 
 descending limbs of bifurcation, c. Collateral arising from stem- 
 fibre. (Van Gehuchten.) 
 
 is in relation with the fibres of the posterior nerve-roots, and the axones from 
 the cells of the column compose the direct cerebellar tract, and some, which are 
 sympathetic, enter the anterior roots of the spinal nerves. In the posterior cornu 
 are many cells not definitely arranged, but groups which are named peripheral, 
 central, and basal. The axones of the cells of the posterior cornu enter the 
 ground bundles, the column of Burdach, the anterior cornu of the same side, and 
 the anterior and posterior cornua of the opposite side. Many fibres of the poste- 
 rior roots are in relation with the cells of the posterior cornu. 
 
 At the junction of the anterior and posterior cornua, in the outer portion of the- 
 gray matter, is a third group of cells, the lateral cell column; this is best seen in 
 the dorsal region. In certain regions of the cord these cells extend in among 
 the fibres of the white matter of the lateral column, and give rise to the lateral 
 horn. 
 
THE DURA MATER OF THE BRAIN 847 
 
 In addition to these groups a few large scattered cells are found in the posterior 
 horn and in the substantia gelatinosa of Rolando. 
 
 Origin of the Spinal Nerves (Figs. 538 and 540). — The roots of the spinal nerves 
 are attached to the surface of the cord, opposite the horns of gray matter. 
 
 A Posterior Nerve-root enters the cord in two bundles, medial and lateral. The 
 medial strand consists of coarse fibres which enter the outer part of the column of 
 Burdach. The lateral strand is sometimes divided into a middle and an external 
 bundle. The former contains large fibres, and passes through the gelatinous sub- 
 stance of Rolando into the posterior horn. The external bundle consists of fine 
 fibres which assume a longitudinal direction in the Spitzka-Ivissauer tract. All the 
 posterior root-fibres divide into ascending and descending branches on entering the 
 cord, and these in their turn give off collaterals (Fig. 541). The fibres and their 
 collaterals terminate by forming arborescences, some around the cells in the 
 posterior horn, and others around the cells of Clarke's column, while the long 
 ascending branches pass up in the columns of GoU and Burdach, and end by 
 arborizing around the cells in the gracile and cimeate nuclei. Some of the fibres, 
 however, pass to the gray matter of the opposite horn, and others to the anterior 
 horn of the same side of the cord. 
 
 Anterior Nerve-roots. — The majority of the fibres of the anterior nerve-roots are 
 the continuations outward of the axones of the large or small multipolar cells in the 
 anterior horn of gray matter. Some, however, appear to pass across in the anterior 
 a white commissure to the cells in the anterior horn of the opposite side, while others 
 extend backward to the posterior horn and outward to the lateral column of the 
 same side. 
 
 THE MENINGES OR MENINGEAL MEMBRANES OF THE BRAIN 
 (MENINGES ENOEPHALI). 
 
 Dissection. — To examine the brain with its membranes, the skull-cap must be removed. 
 In order to effect this, saw through the external table, the section commencing, in front, about 
 an inch above the margin of the orbit, and extending, behind, to a Httle above the level with 
 the occipital protuberance. Then break the internal table with the chisel and hammer, to avoid 
 injuring the investing membranes or brain; loosen and forcibly detach the skull-cap, when the 
 dura mater will be exposed. The adhesion between the bone and the dura mater is very 
 intimate, and much more so in the young subject than in the adult. 
 
 The membranes of the brain are from without inward : the dura mater, arachnoid 
 membrane, and the pia mater. 
 
 The Dura Mater of the Brain (Dura Mater Encephali) (Figs. 543,544,545,547). 
 
 The dura mater of the brain is a thick and dense inelastic fibrous membrane 
 which lines the interior of the skull. It is a covering for the brain and is also 
 the internal periosteum. Its outer surface is rough and fibrillated, and adheres 
 closely to the inner surface of the bones by fibrous processes and blood-vessels. 
 The adhesion is most marked on bony projections, opposite the sutures and at 
 the base of the skull. Except at the sutures the adhesions are not dense, and 
 between the fibrous processes which pass to the bone are spaces which are 
 thought to be lymph-spaces, and are called epidural spaces. At these points 
 the outer surface of the dura is covered with endothelium. Fibrous tissue 
 passes through the open sutures and joins the outer layer of the dura to the 
 external periosteum. It is known as the sutural membrane. The inner sur- 
 face of the dura limits the subdural space. It is smooth and lined by a layer of 
 endothelium. The dura mater sends four processes inward, into the cavity of 
 the skull, for the support and protection of the different parts of the brain, and is 
 prolonged to the outer surface of the skull through the various foramina which 
 
848 THE NERVOUS SYSTEM 
 
 exist at the base, and thus becomes continuous with the pericranium; its fibrous 
 layer forms sheaths for the nerves which pass through these apertures. At the 
 base of the skull it sends a fibrous prolongation into the foramen ciecum ; it sends 
 a series of tubular prolongations around the filaments of the olfactory nerves as 
 they pass through the cribriform plate, and also around the nasal nerve as it passes 
 through the nasal slit; a prolongation is also continued through the sphenoidal 
 fissure into the orbit, and another is continued into the same cavity through the 
 optic foramen, forming a sheath for the optic nerve, which is continued as far as the 
 eyeball. In the posterior fossa it sends a process into the internal auditory meatus, 
 ensheathing the facial and auditory nerves; another through the jugular foramen, 
 forming a sheath for the structures which pass through this opening; and a third 
 through the anterior condyloid foramen. Around the margin of the foramen mag- 
 num it is closely adherent to the bone, and is continuous with the dura mater lining 
 the spinal canal. The cavity or cave of Meckel (cavum Meckeli) (Fig. 545) is an 
 osteo-fibrous recess near the apex of the petrous portion of the temporal bone, 
 formed by folding of the dura mater in a bony depression. It contains the Gas- 
 serian ganglion. In certain situations, as already mentioned (p. 736), the fibrous 
 layers of this membrane separate to form sinuses for the passage of venous blood. 
 Upon the outer surface of the dura mater, in the situation of the longitudinal sinus, 
 may be seen numerous small, whitish bodies, the glandulae Pacchioni (p. 854). 
 
 Structure (Fig. 542). — The dura mater consists of white fibrous tissue with 
 connective-tissue cells and elastic fibres arranged in flattened laminae, which are 
 imperfectly separated by lacunar spaces and blood-vessels into two layers, 
 endosteal and meningeal. The endosteal layer is the internal periosteum for the 
 
 ENDOSTEAL 
 LAYER 
 MENINGEAL 
 LAYER 
 
 ENDOTHELIAL 
 LINING 
 
 Fig. 542. — The structure of the dura mater. Section through the cranial vault of a child, slightly enlarged. 
 
 (Poirier and Charpy.) 
 
 cranial bones and contains the blood-vessels for their supply. At the margin 
 of the foramen magnum it becomes continuous with the periosteum lining the 
 spinal canal. The meningeal or supporting layer is lined on its inner surface by a 
 layer of nucleated endothelium, similar to that found on serous membranes; 
 these cells were formerly regarded as belonging to the arachnoid membrane. 
 By its reduplication the meningeal layer forms the falx cerebri, the tentorium 
 and falx cerebelli, and the diaphragma sellae. The two layers are connected by 
 fibres which intersect each other obliquely. 
 
 The Arteries of the Dura Mater (see section on Arteries). — Its arteries are very 
 numerous, but are chiefly distributed to the bones. Those found in the anterior 
 fossa are tlie anterior meningeal branches of the anterior and posterior ethmoidal 
 and internal carotid, and a branch from the middle meningeal. In the middle 
 fossa are the middle and small meningeal branches of the internal maxillary, a 
 branch from the ascending pharyngeal, which enters the skull through the 
 foramen lacerum medium basis cranii, branches from the internal carotid, and 
 a recurrent branch from the lachrymal. In the posterior fossa are meningeal 
 branches from the occipital, one of which enters the skull through the jugular 
 foramen, and the other through the mastoid foramen; the posterior meningeal, 
 
THE DUBA MATER OF THE BRAIN 
 
 849 
 
 from the vertebral; occasionally meningeal branches from the ascending pharjm- 
 geal, which enter the skull, one at the jugular foramen, the other at the anterior 
 condyloid foramen, and a branch from the middle meningeal. 
 
 The Veins of the Dura Mater. — The veins which return the blood from the dura 
 mater (see p. 734) , and partly from the bones, anastomose with the diploic veins 
 (see p. 733). These vessels terminate in the various sinuses, with the exception 
 of two which accompany the middle meningeal artery, and pass out of the skull 
 at the foramen spinosum to join the internal maxillary vein ; above, the meningeal 
 veins communicate with the superior longitudinal sinus. The sinuses are con- 
 sidered on pages 736 to 743 inclusive. On either side of the superior longitu- 
 dinal sinus, especially near its middle, and also near the lateral and straight 
 sinuses, are numerous spaces in the dura mater which communicate with the 
 sinus, either by a small opening or a distinct venous channel. These spaces are 
 the parasinoidal sinuses {lacunae laterales) (Fig. 453). Many of the meningeal 
 veins do not open directly into the sinuses, but indirectly through the parasinoidal 
 sinuses. These venous lacunae are often invaginated by Pacchionian bodies, and 
 they communicate with the underlying cerebral veins, and also with the diploic 
 and emissary veins. 
 
 The Lymphatics of the Dura Mater. — The existence of lymphatic vessels is not 
 proved. Some anatomists claim to have injected such vessels along the middle 
 meningeal arteries (Mascagni, Arnold). Perivascular lymph-spaces do exist. 
 
 The Nerves of the Dura Mater. — The nerves of the dura mater are filaments from 
 the fourth, the ophthalmic division of the fifth, the Gasserian ganglion, the pneumo- 
 gastric, the hypoglossal, and the sympathetic. 
 
 Processes of the Dura Mater (processus durae matris). — The processes of the 
 dura mater, sent inward into the cavity of the skull, are four in number: the falx 
 cerebri, the tentorium cerebelli, the falx cerebelli, and the diaphragma sellae. 
 
 SUPERIOR LONGI- 
 TUDINAL SINUS 
 
 TENTORIUM 
 CEREBELLI 
 
 FALX CEREBELLI 
 
 Fic. 543. — Crucial prolongation of the dura mater. Frontal section passing through the tentorium cerebelli. 
 The torcular Herophili is seen in the centre. (Poirier and Charpy.) 
 
 The Falx Cerebri (Figs. 543 and 545). — The falx cerebri, so named from its 
 sickle-like form, is a strong arched process of the dura mater, which descends 
 vertically in the longitudinal fissure between the two hemispheres of the brain. 
 It is narrow in front, where it is attached to the crista galli of the ethmoid bone, 
 and broad behind, where it is connected with the upper surface of the tentorium. 
 Its upper margin is convex, and attached to the inner surface of the skull, in the 
 
 54 
 
850 
 
 THE NERVOUS SYSTEM 
 
 middle line, as far back as the internal occipital protuberance; it contains the 
 superior or great longitudinal sinus {sinus sagittalis superior). Its lower margin 
 is free, concave, and presents a sharp curved edge, which contains the inferior 
 longitudinal sinus (sinus sagittalis inferior). The straight sinus (sinus rectus) is 
 formed by the attachment of the falx cerebri to the tentorium cerebelli. 
 
 The Tentorium Cerebelli (Figs. 543, 544, and 545). — The tentorium cerebelli is 
 an arched lamina of dura mater, elevated in the middle and inclining downward 
 
 DIAPHRAGMA SELLAE 
 
 ANTERIOR 
 
 CLINOID 
 
 PROCESS 
 
 INCISURA 
 TENTORII 
 
 TENTORIUM 
 CEREBELLI 
 
 Fig. 544. — The tentorium cerebelli. (Poirier and Charpy.) 
 
 toward the circumference. It covers the upper surface of the cerebellum, and 
 supports the occipital lobes of the brain, and prevents them pressing upon the 
 cerebellum. It is attached, behind, by its convex border to the transverse ridges 
 upon the inner surface of the occipital bone, and there encloses on each side the 
 lateral sinus (sinus transversus) ; in front, to the superior margin of the petrous 
 portion of the temporal bone on either side, enclosing the superior petrosal 
 sinus (sinus petrosus superior); and at the apex of this bone the free or internal 
 border and the attached or external border meet, and, crossing one another, are 
 continued forward, to be attached to the anterior and posterior clinoid processes 
 respectively. Along the middle line of its upper surface the posterior border 
 of the falx cerebri is attached, the straight sinus being placed at their point of 
 junction. Its anterior border is free and concave, and with the dorsum sellae 
 forms a large oval opening. This opening is called the incisura tentorii and 
 transmits the mesencephalon. 
 
 The Falx Cerebelli (Fig. 543) . — The falx cerebelli is a small triangular process 
 of dura mater received into the indentation between the two lateral lobes of the 
 cerebellum behind. Its base is attached, above, to the under and back part of 
 
THE ARACHNOID MEMBRANE 
 
 851 
 
 the tentorium; its posterior margin, to the lower division of the vertical crest on 
 the inner surface of the occipital bone. As it descends it sometimes divides into 
 two smaller folds, which are lost on the sides of the foramen magnum. 
 
 The Diaphragma Sellae (Fig. 544), — The diaphragma sellae is a horizontal process 
 formed by a reduplication of the meningeal layer of the dura mater. It forms 
 a small circular fold, which constitutes a roof for the sella turcica. This almost 
 
 Fio. 545. — Falx cerebri and tentorium, left lateral view. (Testut.) 
 
 completely covers the pituitary body, presenting merely a small central opening 
 (foramen diaphragmatis sellae) for the infundibulum to pass through. 
 
 The Arachnoid Membrane (Arachnoidea Encephaii) (Fig. 546). 
 
 The term arachnoid is from the Greek aftdj^uT^ £^ooc, like a spider's web, so 
 named for its extreme thinness. The cranial arachnoid is a delicate membrane 
 which envelops the brain, lying between the pia mater internally and the dura 
 mater externally; from this latter membrane it is separated by a very fine slit or 
 space, the subdural space (cavum suhdurale). The subdural space contains a very 
 minute quantity of fluid of the nature of lymph. This fluid obtains exit by way 
 of the parasinoidal sinuses. The subdural space is prolonged upon emerging 
 nerves and joins the lymph spaces of the nerves. The subdural space does not 
 communicate with the subarachnoid space. 
 
 The arachnoid invests the brain loosely, being separated from direct contact 
 with the cerebral substance by the pia mater, and a quantity of loose areolar 
 tissue, the subarachnoidean areolar tissue. On the upper surface of the cere- 
 brum the arachnoid is thin and transparent, and may be easily demonstrated by 
 
852 
 
 THE NERVOUS SYSTEM 
 
 injecting a stream of air beneath it by means of a blowpipe; it passes over the 
 convolutions without dipping down into the sulci between them, but does pass 
 into the Sylvian and great longitudinal fissures and is prolonged upon the nerves 
 as a sheath. At the base of the brain the arachnoid is thicker, and slightly 
 opaque toward the central part; it covers the orbital surface of the anterior 
 lobes, and extends across between the two temporal lobes so as to leave a con- 
 siderable interval between it and the brain, the cistema basalis. 
 
 The Subarachnoid Space (cavum subarachnoideale) (Fig. 547). — The subarach- 
 noid space is the interval between the arachnoid and pia mater. It is not only on 
 
 OLFACTORY 
 NERVE 
 
 VERTEBRAL 
 ARTERY 
 
 SPIN/ 
 ARACHNOID 
 
 Fig. 546. — The arachnoid upon the base of the brain. On the right the arachnoid ha.s been partly removed 
 to show the cerebrum and cerebellum with their superficial veins. (Poirier and Charpy.) 
 
 the surface, but dips between the convolutions. It is not, properly speaking, 
 a space, for it is occupied everywhere by a spongy tissue consisting of trabeculse 
 of delicate connective tissue covered with endothelium, which pass from the pia 
 mater to the arachnoid, and in the meshes of which the subarachnoid fluid is con- 
 tained. This so-called space is small on the surface of the hemispheres; but at 
 the base of the brain the subarachnoid tissue is less abundant and its meshes 
 larger. 
 
 In certain regions the arachnoid and pia are farther apart than was previously 
 .ndicated, and these spaces are called subarachnoid cisternae (cisternae subarach- 
 noidalis). The largest space is the continuation of the posterior part of the sub- 
 arachnoid space of the spinal cord. It is called the posterior subarachnoid space 
 
THE ARACHNOID MEMBRANE 853 
 
 or cistema magna (cisterna cerehellomedullaris). It is a space formed by the 
 arachnoid passing across the back and under portions of the medulla and cere- 
 bellum. It communicates with the fourth ventricle by three foramina. The 
 largest opening is the foramen of Majendie (apertura medialis veniriculi quarti). 
 It is in the middle line of the tela choroidea inferior. At the end of each recessus 
 lateralis of the fourth ventricle there is also an opening, and each opening is 
 called the foramen of Key and Retzius (apertura lauralis ventriculi quarti). 
 The cistema pontis is the continuation upward of the anterior part of the sub- 
 arachnoid space of the cord. About the medulla it is continuous with the 
 cisterna magna, so this important nerve centre is surrounded by a large sub- 
 arachnoid space. The cistema basalis (cisterna interpeduncularis) is formed 
 by the arachnoid extending between the two temporal lobes, and it contains the 
 arteries forming the circle of Willis. The anterior subarachnoid space (cisterna 
 pontis, interpeduncularis et chiasmatis) includes the cisterna pontis, the cisterna 
 basalis and the cisterna of the chiasm. There is a cisterna between the inferior 
 edge of the falx cerebri and the superior surface of the corpus callosum which 
 contains the anterior cerebral arteries, a cisterna in the fissure of Sylvius which 
 contains the anterior cerebral artery, and a cisterna between the corpora quad- 
 rigemina which contains the vena magna Galeni. 
 
 It is stated by Merkel that the lateral ventricles also communicate with the 
 subarachnoid space at the apices of their descending horns. 
 
 =ARACHNOID 
 -PIA MATER 
 
 CONVOLUTION 
 OF BRAIN 
 
 Fig. 547. — The subarachnoid space. (Schematic.) (Poirier and Charpy.) 
 
 The cerebro-spinal fluid (liquor cerebrospinalis) fills the subarachnoid space. It 
 IS a clear, limpid fluid, having a saltish taste and a slightly alkaUne reaction. 
 According to I^assaigne, it consists of 98.5 parts of water, the remaining 1.5 per 
 cent, being solid matters, animal and saline. It varies in quantity, being most 
 abundant in old persons, and is quickly reproduced. Its chief use is probably 
 to afford mechanical protection to the nervous centres, and to prevent the effects 
 of concussions communicated from without. 
 
 Structure. — The arachnoid consists of bundles of connective tissue, the fine 
 fibres of which form one layer and cross each other in every direction. At the 
 level of the large fissures, and especially around the circle of Willis, it is reinforced 
 by thick fibrous tissue. Both surfaces are covered with endothelium. There are 
 no blood-vessels in the arachnoid; the vessels which appear to be in it are really 
 in the pia. There is no positive proof that nerves are present in the arachnoid. 
 It is true that Bochdalek and I>uschka long ago described arachnoid nerves, but 
 these observations have never been corroborated. 
 
g54 THE NERVOUS SYSTEM 
 
 Glandulae Pacchioni, Luschka's Villi or the Arachnoid Villi (Granulationes 
 
 Arachnoideales). 
 
 The glandulae Pacchioni are numerous small whitish or purplish projections, 
 usually collected into clusters of variable size, which are found in the following 
 situations: 1. Upon the outer surface of the dura mater, in the vicinity of the 
 superior longitudinal sinus, being received into little depressions on the inner 
 surface of the calvarium. 2. On the inner surface of the dura mater. 3. In the 
 superior longitudinal sinus and the other sinuses. 4. On the pia mater, near 
 the margin of the hemispheres. 
 
 A hasty examination would lead us to suppose that these bodies spring from 
 the dura, but, as a matter of fact, they originate from the arachnoid. They are 
 not glandular in structure, but are simply enlarged normal villi of the arachnoid. 
 In their growth they appear to perforate the dura mater, and when a group of 
 villi is of large size it causes absorption of the })one, and comes to be lodged in a 
 pit or depression (foveola granularis [Pacchioni]) on the inner table of the skull. 
 Their manner of growth is as follows : at an early period they project through 
 minute holes in the inner layer of the dura mater, which open into large venous 
 spaces situated in the tissues of the membrane, on either side of the longitudinal 
 sinus and communicating with it. In their onward growth the villi push the outer 
 layer of the dura mater before them, and this forms over them a delicate mem- 
 branous sheath. In structure they consist of spongy trabecular tissue, covered 
 over by a membrane, which is continuous with the arachnoid. The space between 
 these two coverings, derived from the dura mater and arachnoid respectively, 
 corresponds to and is continuous with the subdural space. The spongy tissue of 
 which they are composed is continuous with the . trabecular tissue of the sub- 
 arachnoid space; so that fluid injected into the subarachnoid space finds its 
 way into the Pacchionian bodies, and through their coverings filters into the 
 superior longitudinal sinus. They are supposed to be a means of getting rid of 
 an excess of cerebro-spinal fluid, when its quantity is increased above normal. 
 Another means of getting rid of cerebro-spinal fluid is absorption by the lymph- 
 spaces of the cranial nerves, which possess sheaths of arachnoid up to the points 
 at which they emerge from the skull. 
 
 These bodies are not found in infancy, and very rarely until the third year. 
 They are usually found after the tenth year; and from this period they increase 
 in number as age advances. Occasionally they are wanting. 
 
 The Pia Mater of the Brain (Pia Mater Encephali) (Figs. 547, 548). 
 
 The pia mater of the brain is a vascular membrane, and derives its blood from 
 the Internal carotid and vertebral arteries. It consists of a minute plexus of blood- 
 vessels, held together by an extremely fine areolar tissue. It invests the entire 
 surface of the brain, dipping down between the convolutions and laminje, and 
 is prolonged into the interior, forming the velum interpositum and the choroid 
 plexuses of the lateral and fourth ventricles. 
 
 The Velum Interpositum or the Tela Chorioidea Superior (tela chorioidea 
 ventriculi tertii) (Fig. 548). — The velum interpositum is the prolongation of the 
 pia mater into the interior of the brain through the middle of the transverse 
 fissure. It is a double triangular vascular fokl, lies between the body of the 
 fornix above and the optic thalami and the epithelial roof of the third ventricle 
 below, and passes forward to the foramen of Monro. At each edge of the 
 velum interpositum is the choroid plexus (plexus chorioideus ventriculi lateralis) 
 of the corresponding lateral ventricle. In front the two plexuses join behind 
 
THE PIA MATER OF THE BRAIN 
 
 855 
 
 ANTERIOR PILLAR 
 OF FORNIX 
 
 CAUDATE 
 NUCLEUS 
 
 VEINS OF 
 GALEN 
 
 VENA MAGNA 
 OALENI 
 
 Fig. 548. — Velum interpositum. (Poirier and Charpy.) 
 
 :rior 
 municating 
 
 RY 
 
 RNAL 
 OTID 
 
 EXTERNAL 
 
 GENICULATE 
 
 BODY 
 
 INTERNAL 
 
 6ENICULATE 
 
 BODY 
 
 PULVINAR 
 
 MIDDLE CORNU 
 OF LATERAL 
 VENTRICLE 
 
 ERIOR 
 MUNICATING 
 RY 
 BASILAR 
 ARTERY 
 
 POSTERIOR 
 
 CEREBRAL 
 
 ARTERY 
 
 RA 
 IGEMINA 
 
 Fig. 549. — The anterior cerebral and choroid arteries. (Spalteholz.) 
 
856 
 
 THE NERVOUS SYSTEM 
 
 the foramen of Monro, and at the point of junction two lesser choroid plexuses 
 pass back along the under surface of the velum to the third ventricle, the median 
 plexus {plexus chorioideus ventriculi tertii). The veins of Galen or the deep 
 cerebral veins (p. 735) are two veins which lie on either side of the middle of the 
 velum interpositum and pass back. Each vein of Galen is formed by the union 
 of the vein from the corpus striatum and the choroid vein from the choroid 
 plexus. The two veins of Galen unite and form the vena magna Galeni, which 
 empties into the straight sinus. 
 
 The pia mater of the surfaces of the hemispheres, where it covers the gray 
 matter of the convolutions, is very vascular, and gives off from its inner surface 
 a multitude of minute vessels, which extend perpendicularly for some distance 
 into the cerebral substance. At the base of the brain, in the situation of the 
 anterior and posterior perforated spaces, a number of long straight vessels are 
 given off, which pass through the white matter to reach the gray substance in the 
 
 CALLOSO-MARGINAL 
 FISSURE 
 
 PARIETO-OCCIPITAL 
 ULCUS 
 
 ANTERIOR CERE 
 BRAL ARTERY 
 
 OPTIC 
 NERVE 
 
 CALCARINE 
 FISSURE 
 
 ANTERIOR COM- 
 MUNICATING ARTERY 
 
 INTERNAL POSTERIOR POSTERIOR 
 
 CAROTID COMMUNICATING CEREBRAL 
 ARTERY ARTERY ARTERY 
 
 Fig. 550. — The arteries of the medial surface of the right cerebral hemisphere. (Spalteholz.) 
 
 interior. On the cerebellum the membrane is more delicate, and the vessels from 
 its inner surface are shorter. The pia mater of the spinal cord is thicker, firmer, 
 and less vascular than that of the brain, and as it is traced upward over the 
 medulla it is seen to preserve these characters. At the upper border of the medulla 
 it is prolonged over the lower half of the fourth ventricle, forming a covering for 
 it called the tela chorioidea inferior {tela chorioidea ventriculi quarti), before it is 
 reflected on to the under surface of the cerebellum, and which carries the choroid 
 plexus of the fourth ventricle {plexus chorioideus ventriculi quarti). 
 
 The arteries of the pia mater (see pp. 626, 627, and 628) (Figs. 549 and 550) 
 are the anterior cerebrals, middle cerebrals, posterior cerebrals, anterior choroids, 
 posterior choroids, the superior cerebellars, and the anterior and posterior inferior 
 cerebellars. (The vessels of the cerebral ganglionic system and of the cortical 
 arterial system are considered on pp. 630 and 631.) 
 
 The veins of the pia mater (see pp. 734, 735, and 736) are the basilar vein, 
 the veins of Galen (Fig. 548), the veins constituting the choroid plexuses of the 
 
THE BRAIN 857 
 
 third ventricle, the lateral ventricles, and the fourth ventricle; the cerebral veins 
 (Fig. 546) and the cerebellar veins (Fig. 540). 
 
 The nerves of the pia mater accompany the branches of the arteries and are 
 derived from the sympathetic and from the third, fifth, sixth, seventh, ninth, tenth, 
 and eleventh cranial nerves. 
 
 According to Fohmann, Arnold, and Mascagni, this membrane contains numer- 
 ous lymphatic vessels, but the question is uncertain. 
 
 THE BRAIN (ENCEPHALON) . 
 
 The encephalon or brain is that portion of the cerebro-spinal axis which is 
 contained in the cavity of the cranium. 
 
 The Development of the Brain. — The nervous system (brain, ganglia, spinal 
 cord, and nerves) is derived from the ectoderm (the epiblastic layer of the blasto- 
 dermic vesicle). This, it will l)e remembered, is an epithelial layer, and nervous 
 structure is composed of epithelial cells variously modified. The embryonal area 
 of the surface of the developing germ is a white spot, which at first is round, but 
 becomes pear-shaped and develops a transverse ridge, the terminal ridge, on its 
 posterior margin. From the embryonal layer, and from this alone, the new indi- 
 vidual is developed. 
 
 About the twelfth or the thirteenth day of the development of the human 
 embryo, cell-proliferation occurs at a certain portion of the under surface of the 
 ectoderm. This proliferation gives rise to a white, longitudinal streak in the 
 embryonal area, known as the primitive streak or axis plate. The head process of 
 the primitive streak appears somewhat later, and is situated directly in front 
 of the anterior end of the streak. 
 
 At the anterior end of the primitive streak is a group of epiblastic cells known 
 as Hensen's node. The epiblastic cells of the head-process of the primitive streak 
 enlarge and become columnar, and the cells at each side of the streak become 
 flat (Heisler). Thus is formed from the ectoderm the medullary plates; and the 
 turning up of the edge of the medullary plates forms the* spinal or medullary 
 furrow or groove. As the curling up of the edges of the medullary plates continues 
 the groove deepens, finally becoming a tube known as the medullary or neural tube 
 or canal. 
 
 The neural tube lies beneath the ectoderm; is finally separated from it; runs 
 from one end of the body to the other; forms the primitive nervous system, and 
 gives origin to the entire nervous system. The constricted portion between the 
 hind-brain and the mid-brain is known as the isthmus rhombencephali. 
 
 It is thus seen that the medullary or neural groove is converted into a canal, 
 the neural canal. Its cephalic end dilates into a sac, from which the brain is 
 developed, and the remainder forms the spinal cord. In consequence of the curve 
 that the cephalic portion of the embryo undergoes, a marked bend in the canal 
 takes place forward, so that the plane of the ventricles is placed almost at a right 
 angle with the long axis of the central canal of the cord. The rudimentary brain 
 consists of a hollow sac — the rudimentary corrl of a hollow canal. The sac and 
 the canal communicate freely with each other. 
 
 The sac elongates, and in it appear two constrictions, which partially divide it 
 into three portions, namely, the anterior, middle, and posterior primitive cerebral 
 vesicles, or the fore-brain (prosencephalon), the mid-brain {mesencephalon), and the 
 hind-brain {rhombencephalon) (Fig. 551). Subsequently the anterior and the pos- 
 terior vesicles become constricted, each into two, while the middle remains 
 undivided (Figs. 553 and 554). It will thus be seen that at the anterior 
 extremity of the medullary canal there are five dilatations, separated from' each 
 
858 
 
 THE NERVOUS SYSTEM 
 
 other by constrictions, through which, however, they freely communicate with 
 one another. These five vesicles are the fundamental or primitive divisions of 
 the adult brain. They are named, from before backward, the fore-brain (pros- 
 encephalon), the inter-brain (thalamencephalon, formed from the prosencephalon), 
 the mid-brain (mesencephalon), the upper portion of the hind-brain (metencephalon). 
 
 - -Head fold of amnion. 
 
 Forebraiii. 
 
 — Optic vesicle. 
 
 M^hrain.--'^-''~- 
 
 Eindbrain.- 
 
 Auditory vesicle. - 
 
 Medullary ridge. —-,4*- 
 
 Remains of primitive— t 
 streak. 
 
 Heart. 
 
 (tmphalo-mesenterie vem. 
 
 I Protorertebrx or 
 
 ) mesoblastic somites. 
 
 -9— -Sinus rhomboidalis. 
 
 Fig. 551. 
 
 -Chick embryo of thirty-three hours' incubation, \ iewed from the dorsal a.spect. 
 (From Duval's Atlas d'Embryologie.) 
 
 X 30. 
 
 and the lower portion of the hind-brain (myelencephalon). The constricted por- 
 tion between the hind-brain and the mid-brain is known as the isthmus rhomb- 
 encephali. 
 
 These five vesicles are at first fairly uniform in size and in shape, but they soon 
 begin to grow at different rates and to assume different forms. The changes are 
 most marked in the first vesicle. 
 
THE BRAIN 
 
 859 
 
 The first secondary vesicle sends out two hollow protrusions, one on each side, 
 from the forepart of its lateral surface. These grow rapidly, spread out, and 
 extend forward, laterally, and backward, over the sides of the first and second 
 ventricles, forming large cavities, which become the lateral ventricles (Fig. 552, G). 
 From each protrusion three prolongations take place: one forward and out- 
 ward; the second backward and inward, and the 
 third at first backward, outward, and downward, 
 and then forward and inward. These prolonga- 
 tions form the horns of the lateral ventricles, and 
 they far exceed in size the original vesicle from 
 which they have taken origin, which does not 
 increase to any great extent, but remains as the 
 anterior part of the third ventricle. The com- 
 munication between it and the future lateral ven- 
 tricle persists as the foramen of Monro (Fig. 552). 
 
 The second vesicle or thalamencephalon be- 
 comes elongated from before backward and com- 
 pressed laterally, so as to form the greater part 
 of the third ventricle (Fig. 552, J?). From each 
 side of that part of the fore-brain, which ulti- 
 mately becomes the lateral ventricle, is budded 
 off a hollow projection, the primary optic vesicle, 
 that is developed eventually into the optic nerve 
 and the retina. It will be considered later. 
 
 The constriction between the first and the 
 second vesicle disappears, so as to throw the 
 whole cavity of the future third ventricle, formed 
 by the remains of the first ventricle and the whole 
 of the second vesicle, into one. 
 
 The third vesicle or mesencephalon forms a 
 very insignificant part of the brain of the adult. 
 It constitutes a stem of junction between the 
 parts that take origin from the rhombencephalon 
 and those that arise from the prosencephalon. 
 The wall of the mesencephalon is completely 
 converted into nerve-tissue, and forms the corpora 
 quadrigemina, the two crm-a cerebri, and the aque- 
 duct of Sylvius, which join the third ventricle with 
 the fourth. 
 
 The metencephalon gives origin to the cere- 
 bellum and the pons Varolii. The cerebellum 
 takes origin from a thickening of the superior 
 
 wall of the vesicle, while the pons takes origin from a thickening of the lateral 
 and inferior walls of the vesicle. 
 
 The myelencephalon gives origin to the bulb or medulla oblongata, chiefly by a 
 thickening of the lateral walls of the vesicle. The original hind-brain remains in 
 the brain of the adult as the fourth ventricle. 
 
 As already stated , these vesicles do not remain in the same plane. The formation 
 of certain definite flexures alters the position of the vesicles with regard to one another 
 (Fig. 554). The cephalic flexure is opposite the base of the mid-brain, which 
 becomes sharply bent upon itself over the end of the notochord. This bending 
 causes the mid-brain to become the most prominent part of the encephalon on the 
 convexity of the curve. The pontine or pontal flexure is a curve in the hind-brain, 
 in the opposite direction to that of the cephalic flexure. At the junction of the 
 
 \J 
 
 Fig. 552. 
 
 Plan showing the mode of 
 formation of the ventricles of the brain 
 and the central canal of the spinal cord. 
 A. Prosencephalon. B. Thalamenceph- 
 alon. C. Mesencephalon. D. Metenceph- 
 alon. E. Myelencephalon. F. Central canal 
 of cord. G. Lateral ventricle. H. Fora- 
 men of Monro. (After Gerrish.) 
 
860 
 
 THE NERVOUS SYSTEM 
 
 hind-brain with the spinal cord is the cervical or nuchal flexure. In the develop- 
 ment of the brain the cephalic flexure remains permanent, but the other two 
 flexures completely disappear. 
 
 The manner in which the different parts of the encephalon are formed from 
 the walls of this greatly altered medullary canal will now be considered, it being 
 remembered that the ventricles are developed, as previously described, from the 
 five secondary vesicles. 
 
 The first vesicle, or prosencephalon, sends out two hollow protrusions, which 
 spread rapidly, and in the walls of these nervous matter is developed, which con- 
 stitutes the cerebral hemispheres (Fig. 554, H), the cavities remaining as the 
 lateral ventricles. As these hemispheres extend they grow forward in front of 
 the anterior extremity of the primitive brain, and lie side by side, separated by the 
 longitudinal fissure; they also grow upward, and again lying side by side are 
 separated by another portion of the same fissure, containing a thin layer of meso- 
 blast, which forms the falx cerebri; behind and laterally they overlap the roof 
 and sides of the other cerebral vesicles, so that by the seventh month they project 
 
 Fig. 553. — Vertical section of the head in early embryos of the rabbit. Magnified. A. From an embryo five 
 millimetres long. 13. From an embryo six millimetres long. C. Vertical section of the anterior end of the 
 notochord and pituitary body, etc., from an embryo sixteen millimetres long. In A, the faucial opening is still 
 closed. In B, it is formed, c. Anterior cerebral vesicle, inc. Mesocerebrum. mo. Medulla oblongata, co. 
 Corneous layer, to. Medullary layer, if Tnfundibulum. owi. _ Amnion, spe. Spheno^ethmoidal, 6c, central 
 (dorsum sellae), and sp.o, spheno-occipital parts of the basis-cranii. h. Heart. /. Anterior extremity of primi- 
 tive alimentary canal and opening (later) of the fauces, i. Cephalic portion of primitive intestine, tha. Thalamus. 
 p'. Closed opening or the involuted part of the pituitary body (jpy) ch. Notochord. ph. Pharynx. (From 
 Mihalkovics.) 
 
 behind them In the floor of each of these hemispheres there occurs a local 
 thickening, which forms the corpus striatum, which is continuous behind with the 
 optic thalamus presently to be described The surface of the hemisphere is at 
 first smooth, but about the fifth month a sulcus or groove appears in either hemi- 
 sphere just external to the corpus striatum; this is the fissure of Sylvius: subse- 
 quently other fissures appear on the surface, three of which are of sufficient depth 
 to cause a projection into the lateral ventricle. These are the hippocampal fissure, 
 corresponding to the hippocampus major of the lateral ventricle, the collateral 
 fissure, corresponding with the bend of the posterior horn of the ventricle; and 
 the calcarine fissure, corresponding with the projection of the calcar avis. 
 
 The remainder of the first vesicie and the second, as we have seen, form the 
 third ventricle, in its normal wails a thickening takes place, which forms the 
 optic thalamus. From the floor of this ventricle a hollow protrusion passes down- 
 ward, and is intimately connected with a diverticulum from the stomodaeum, to 
 form part of the pituitary body {hypophysis cerebri) (Figs 553, 554, and 555). The 
 greater part of the roof of the third ventricle is very thin, and with the pia mater 
 
THE BBAIN 
 
 861 
 
 NK. 
 
 Fig. 554. — Profile views of the brain of human embryos at three several stages, reconstructed from sections. 
 (Copied from Quain's Anatomy.) A. Brain of an embryo vif about fifteen days, magnified 35 diameters. _ B. 
 I5rain of an embryo about three and a half weeks old. The optic vesicle has been cut away. C. Brain of 
 an embryo about seven and a half weeks old. The optic stalk is cut through. A. Optic vesicle. H. Vesicle of 
 cerebral hemisphere, first secondary vesicle. Z. Thalamencephalon, second secondary vesicle. M. Mid-brain. 
 J. Isthmus between mid-brain and hind-brain. Hh. Fourth secondary vesicle. A'. Fifth .secondary vesicle. Ob. 
 Otic vesicle. Rf. Fourth ventricle. NK. Neck curvature. Br. Pons curvature. Pm. Mammillary process. 
 TV. Infundibulum. Hp. (in B). Outline of hypophysis-fold of buccal epiblast. Kl. Olfactory fold. In C the 
 basilar artery is represented along its whole course. (His.) 
 
862 
 
 THE NERVOUS SYSTE3£ 
 
 forms the velum interpositum ; from its posterior part an outgrowth of cells forms 
 the pineal body {epiphysis cerebri). Where the cerebral hemispheres are not 
 separated in the middle line by the falx, in front and for some distance backward 
 over the roof of the third ventricle their mesial surfaces come in contact, and to a 
 certain extent fuse together, leaving, however, a small portion where no union 
 takes place, and thus a slit-like cavity is left; this is termed the fifth ventricle,' 
 though it will be at once seen that its development is quite different from that 
 of the other ventricles. Its lateral walls form the septum lucidum. The roof of 
 this cavity becomes thickened, and nerve-fibres pass across from the one hemi- 
 sphere to the other to form the corpus callosum, while in its floor longitudinal fibres 
 are developed to form the fornix. 
 
 The third vesicle, the cavity of which forms the iter a tertio ad quartum ven- 
 triculum, develops in its roof four well-marked thickenings, which together form 
 
 Optic thalamus. 
 Foramen of Monro 
 
 Posterior commissure. 
 Pineal body. 
 
 Cms cerebri. 
 
 Aqueduct of Sylvius. 
 
 Corpora quadrigemina. 
 
 1 Cerebellum. 
 
 '~IV. Ventncle. 
 
 Cerebral hemisphere. 
 
 Olfactory lobe or 1 1 , 
 rhinencephalon. 1 1 ' | 
 Lamina cinerea. [ \ | 
 Optic nerve, j ' 
 Optic commissure. i 
 Pituitary body, 
 Infundibulum. 
 
 Corpus 
 albicans. 
 
 Spinal cord. 
 
 Fig. 555, — Median section of brain of human foetus during the third month. (After His.) 
 
 the corpora quadrigemina, while its lateral regions become thickened to form the 
 crura cerebri (Fig. 555). 
 
 The dorsal surface of the fourth vesicle forms the covering of the fourth ventricle, 
 and in it a thickening occurs which is developed into the cerebellum; its ventral 
 and lateral regions form the pons (Fig. 555). 
 
 In the fifth vesicle the lateral parts increase and grow downward on each side 
 toward the middle line, forming the medulla, while the dorsal surface assists in 
 forming the roof of the fourth ventricle. 
 
 On making a transverse section of the lower part of the fourth ventricle, the 
 alar and basal laminae, already referred to as being present in the cord, are readily 
 recognized, while the thin roof-plate is seen to be greatly expanded laterally. 
 The dorsal part of the alar lamina becomes folded outward and downward, form- 
 
THE BRAIN 
 
 863 
 
 ing what is termed the rhomboid lip (Fig. 556). This is at first separated by a 
 groove from the lateral aspect of the alar lamina, but ultimately fuses with it. As 
 the central canal of the cord opens out to form the fourth ventricle, the alar and 
 basal laminae come to occupy the floor of the ventricle — the basal lamina lying 
 nearest the mesial plane. 
 
 ■l...Rhomho%d, 
 --^yy lip. 
 
 Tractus 
 solitarius. 
 
 I'agua nerve. 
 
 Raphe. \ 
 
 Fig. 556. — Transverse section of medulla oblongata of human embryo. (After His.) 
 
 /jwglossal 
 nerve. 
 
 The Communications of the Parts of the Brain. — In the posterior fossa of the 
 cranium lies the medulla oblongata, the pons Varolii, and the cerebellum, and 
 between these structures and the cerebrum is the tentorium cerebelli. The pons, 
 medulla, and cerebellum surroimd the fourth ventricle. The greater portion of 
 the fibres of the medulla are continued into the pons, but some fibres from the 
 dorsal aspect of the medulla (the restiform bodies) pass into the cerebellum and 
 
 Mesencephalon 
 
 Superior cerebellar peduncle 
 
 Middle cerebellar peduncle 
 Inferior cerebellar peduncle 
 
 Fig. 557.— Scheme showing the connection.s of the several parts of the brain. (Cunningham.) 
 
 become the inferior cerebellar peduncles (Fig. 557). On each side of the pons a 
 thick strand of transverse fibres passes to the cerebellum. These strands are the 
 middle cerebellar pedimcles (Fig. 557). 
 
 The cerebral hemispheres are joined together by the corpus callosum, a com- 
 missure lying within the depths of the great longitudinal fissure. Between and 
 beneath the cerebral hemispheres is the inter -brain (thalamencephalon) , composed 
 chiefly of the optic thalami. In the interior of each hemisphere is a space called 
 
864 THE NERVOUS SYSTEM 
 
 the lateral ventricle. Between the optic thalami is the third ventricle. The foramen 
 of Monro connects the third ventricle with the lateral ventricles. 
 
 The mid-brain connects the cerebrum with the pons, medulla, and cerebellum. 
 It is composed of the crura cerebri, which join together the pons and the cere- 
 brum; the corpora quadrigemina, and the superior cerebellar peduncles (Fig. 557), 
 which connect together the cerebrum and the cerebellum. In the mid-brain the 
 aqueduct of Sylvius joins the third ventricle and the fourth ventricle. 
 
 General Considerations and Divisions. — For the purposes of description the 
 brain may be divided into five parts, as follows: (1) the two cerebral hemispheres; 
 (2) the inter-brain (thalamencephalon) ; (3) the mid-brain (mesencep^talan) ; the hind- 
 brain (rhombencephalon) , which includes (4) the pons Varolii and cerebellum ; and 
 (5) the medulla oblongata. If the student will refer to the section on the Development 
 of the Brain he will find that these five portions correspond fairly accurately to 
 the five secondary cerebral vesicles, of which the brain at an early period of em- 
 bryonal life consisted ; the prosencephalon, or first vesicle, by means of a protrusion 
 from its front part on either side, forms the cerebral hemispheres and the lateral 
 ventricles; the remainder of the prosencephalon, together with the ^econc? vesicle, 
 the thalamencephalon, form the inter-brain and third ventricle; the third vesicle, 
 the mesencephalon, forms the mid-brain, or that portion which connects the inter- 
 brain and hemispheres above with the pons Varolii below, and the cavity of the 
 vesicle forms the aqueduct of Sylvius, or iter a tertio ad quartum ventriculum ; the 
 fourth vesicle, the metencephalon, becomes the future pons Varolii and cerebellum, 
 and its cavity forms the upper half of the fourth ventricle; and, finally, the fifth 
 vesicle, the myelencephalon, develops into the medulla oblongata, and its cavity 
 forms the lower half of the fourth ventricle. It will thus be seen that the five 
 divisions of the encephalon mentioned above correspond to the five secondary cere- 
 bral vesicles, with the exception of the first two, which together form the cerebral 
 hemispheres and the inter-brain. In consequence of this these two portions of 
 the brain are sometimes grouped together as the cerebrum. 
 
 I. The Hemispheres of tjie Cerebrum (Hemisphaeria Cerebri). 
 
 General Considerations. — The two hemispheres constitute the largest portion 
 of the encephalon, and, together with the parts derived from the inter-brain 
 (thalamencephalon) form what is called by some writers the fore-brain (pros- 
 encephalon). They occupy the whole of the vault of the skull, and consist of a 
 central cavity, in either hemisphere, surrounded by exceedingly thick and con- 
 voluted walls of nervous tissue. The under surface or base of the cerebrum is 
 of an irregular form, resting in front on the anterior and middle fossae of the 
 skull and behind upon the tentorium cerebelli. The upper surface is of an 
 ovoid form, broader behind than in front and convex in general outline. The 
 frontal pole (polus frontalis) is the most prominent portion of the anterior end 
 of the hemisphere. The most prominent portion of the posterior end is the 
 occipital pole (polus occipitalis). The most prominent part of the temporal 
 lobe below the fissure of Sylvius is the temporal pole (polus temporalis). The 
 upper surface is divided into two lateral halves or hemispheres, the right and 
 left, by the great longitudinal fissure (fissura longitudinalis cerebri), which extends 
 throughout the entire length of the cerebrum in the middle line, reaching down 
 to the base of the brain in front and behind, but interrupted in the middle 
 by a broad transverse commissure of white matter, the corpus callosum, which 
 connects the two hemispheres together. 
 
 The Constituent Parts of the Hemisphere. — The hemisphere is composed 
 of three distinct parts: the brain-mantle (pallium), the chief mass of the hemi- 
 sphere; the olfactory brain or lobe (rhinencephalon) , composed of the olfactory 
 
THE HEMISPHERES OF THE CEREBRUM 865 
 
 bulb, anterior perforated space, a portion of the uncinate gyrus, the hippocampus, 
 the septum hicidum, etc., and the corpus striatum. 
 
 The Surface of the Cerebrum. — Each hemisphere presents an outer convex 
 surface (fades convexa cerebri), fiUing the concavity of the corresponding half of 
 the vault of the cranium; an inner, flattened surface {fades medialis cerebri), which 
 is vertical and directed toward the corresponding surface of the opposite hemi- 
 sphere (the two inner surfaces forming the sides of the longitudinal fissure) ; and an 
 under surface or base {basis cerebri), of irregular form, which rests in front on the 
 anterior and middle fossae of the base of the skull, and behind upon the tentorium 
 cerebelli. The hemispheres are composed of an outer stratum of gray matter {sub- 
 stantia grisea), called the cortical substance or the cerebral cortex, and in the inte- 
 rior of a mass of white matter (substantia alba) called the medullary centre. The 
 cortex is thrown into a number of creases or infoldings, which are termed 
 fissures and sulci (sulci cerebri), and these separate the surface into a number 
 of irregular eminences, named convolutions or gyri (gyri cerebri). 
 
 The infoldings or creases are of two kinds, complete fissures and incomplete 
 fissures or sulci. The complete fissures (fissurae) are of large size, and appear 
 early in foetal life; they are few in number, nearly constant in their arrangement, 
 and are produced by infoldings of the entire thickness of the wall of the cerebrum, 
 producing corresponding elevations in the interior of the ventricle, and hence are 
 termed complete fissures. They comprise (a) the hippocampal or dentate fissure; 
 (b) the anterior part of the calcarine fissure; (c) the collateral fissure. The sulci are 
 vastly more numerous than the complete fissures; they are superficial depressions 
 of the gray matter, which is folded inward and only indents the central white 
 substance. They produce no corresponding elevations in the interior of the 
 ventricle, and are therefore spoken of as incomplete fissures. They are fairly con- 
 stant in their arrangement, and have received names indicative of their position 
 and direction, but at the same time vary, within certain limits, in different indi- 
 viduals. They are similar, without being absolutely identical, on the two sides of 
 the brain. It therefore follows that the gyri or convolutions (gyri cerebri) which 
 lie between these sulci are fairly constant in their general arrangement. The 
 gyri upon the surface are called superficial gyri. Within the sulci, adjacent super- 
 ficial gyri are joined by deep gjrri (gyri profundi). Short gyri, superficial or deep 
 which connect two gyri of greater length are called annectant or transitional 
 gyri (gyri transitivi). 
 
 The number and extent of the convolutions, as well as the depth of the inter- 
 vening sulci, appear to bear a close relation to the intellectual power of the indi- 
 vidual, as is shown in their increasing complexity of arrangement as one ascends 
 from the lowest mammalia up to man, where they present a most complex arrange- 
 ment. Again, in the child, at birth, before the intellectual faculties are exercised, 
 the convolutions are simpler, and the sulci between them shallower, than in the 
 adult. In old age, when the mental faculties have diminished in activity, the 
 gyri and sulci become less prominently marked. By their arrangement the con- 
 volutions are adapted to increase the amoimt of gray matter without occupying 
 much additional space, while they also afford a greater extent of surface for the 
 termination of white fibres in gray matter. 
 
 It will be convenient in the first instance to describe the fissure which sepa- 
 rates the two hemispheres from each other, and those which divide each hemisphere 
 into its larger divisions. 
 
 Fissures and Sulci of the Outer Surface of the Hemispheres. The Longitu- 
 dinal Fissure (fssura Inngitudinalis cerebri) (Fig. 560). — This great fissure separates 
 the cerebrum into two hemispheres, and reaches from the front to the back of the 
 organ ; it contains a vertical process of the dura mater, the falx cerebri (p. 849). In 
 front and behind the longitudinal fissure extends from the top (dorsal surface) to 
 
 55 
 
866 
 
 THE NERVOUS SYSTEM 
 
 the bottom (ventral surface) of the cerebrum, and completely separates the two 
 hemispheres, but its middle portion only separates the hemispheres for about 
 half their vertical extent, the floor of this part of the fissure being formed by the 
 great central white commissure, the corpus callosum (Figs. 567 and 571), which 
 connects the two hemispheres together. 
 
 The remaining fissures are situated in one or other of the two hemispheres, with 
 the exception of the transverse fissure, one-half of which is contained in each 
 hemisphere. 
 
 Sylvian Fissure (fissura cerebri lateralis [Sylvii]) (Figs. 558, 561, 565, and 570). 
 — This fissure is a well-marked cleft on the base and side of the hemisphere. 
 Starting at the base of the brain in a depression, the vallecula Sylvii, in which is 
 situated the anterior perforated space (Fig. 570). The fissure passes outward 
 between the frontal and temporal lobes, along the lesser wing of the sphenoid 
 
 Parieto- 
 occipital 
 Sulcus. 
 
 Fig. 558. — Chief fissures and lobes on the external surface of the cerebral hemispheres. 
 
 bone to the external surface of the hemisphere. The point at which it reaches 
 the external surface is called the Sylvian point. It here gives off a short anterior 
 horizontal limb (ramus anterior horizontalis) , which passes forward, and a short 
 ascending or vertical limb (ramus anterior ascendens), which passes upward into 
 the inferior frontal convolution. It also gives off the posterior horizontal limb 
 (ramus posterior), which is the most distinct of the three branches. The posterior 
 horizontal limb lies under the middle third of the lateral surface of the hemisphere 
 and above the temporal lobe. It passes backward and slightly upward for about 
 two and a half inches and terminates by an upward inflexion in the parietal lobe, 
 which is called the ascending terminal portion. The anterior horizontal and the 
 vertical limbs are separated by the frontal operculum (pars triangularis) , which is the 
 foot of the inferior frontal convolution. A portion of the same convolution below 
 the anterior limb is called the orbital operculum (pars orbitaUs) . Between the vertical 
 and posterior horizontal limbs is the fronto -parietal operculum (pars opercularis). 
 
THE HEMISPHERES OF THE CEREBRUM 
 
 867 
 
 Limiting Sulcus of Rell {sulcus circularis Reili) (Fig. 566). — If the lips of the 
 posterior liorizontal Hmb of the Sylvian fissure are widely separated, the island of 
 Reil (insula) (Figs. 566 and 568) is seen* in the depths, surrounded by the limiting 
 sulcus. The upper or external portion of the sulcus separates the island from 
 the parietal and frontal lobes, the lower or posterior portion from the temporal 
 lobe, and the anterior portion from the frontal lobe. 
 
 The Central Sulcus of Rolando or the Fissure of Rolando (sulcus centralis 
 [Rolandi]) (Figs. 558, 559, 561, 565, and 574). — The fissure of Rolando is situ- 
 ated about the middle of the outer surface of the hemisphere, and, coursing 
 obliquely downward and forward, divides the surface of the hemisphere into 
 approximately equal parts. It is between the frontal and parietal lobes. It com- 
 mences as a rule on the mesial surface of the longitudinal fissure, runs forward 
 a short distance, and ascends to the superior mesial border, which it reaches a 
 little behind its mid-point, that is at a point half an inch behind the middle of a 
 line drawn from the nasal eminence to the external occipital protuberance. It 
 then runs sinuously downward and forward, to terminate a little above the hori- 
 
 INTERLOCKING 
 'GYRI 
 
 ASCENDING 
 
 FRONTAL 
 
 CONVOLUTION 
 
 Fig. 559.- 
 
 -Sulcus of Rolando fully opened up, so as to exhibit the interlocking gyri and deep annectant 
 gyrus behind it. (Cunningham.) 
 
 zontal limb of the fissure of Sylvius, and about half an inch behind the ascend- 
 ing limb of the same fissure. The angle made by the fissure of Rolando and the 
 mesial plane is known as the Rolandic angle, and it varies in the adult between 
 69 degrees and 74 degrees (Cunningham). It forms two chief curves: the upper 
 or superior curve or genu is concave forward and upward, while the lower or 
 inferior curve or genu has its concavity directed backward. If the lips of the 
 Rolandic fissure are opened, we will see in the depths frontal gyri interlocked 
 with parietal gyri (Fig. 559). Two of these gyri are often fused, and this fused 
 gyrus is named the deep annectant gyrus (Fig. 559) . 
 
 The Parieto-occipital Sulcus (sulcus occipitoparietalis) (Figs. 558, 562, 564, and 
 565). — The parieto-occipital sulcus is only seen to a slight extent on the outer 
 surface of the hemisphere, being situated for the most part on its mesial aspect. 
 The portion on the outer surface is called the external parieto-occipital sulcus, 
 to distinguish it from the part continued on to the internal surface, which is 
 termed the internal parieto-occipital sulcus. The external parieto-occipital sulcus 
 commences about midway between the posterior extremity or occipital pole of 
 the brain and the central sulcus of Rolando, and runs downward and outward for 
 about half an inch, and is ended by an arch-shaped convolution (arcus parieto- 
 
868 
 
 THE NERVOUS SYSTE3I 
 
 occipitalis). The internal parieto-occipital sulcus is vertical in direction, is very 
 distinct, and passes into the calcarine fissure. When its lips are fully separated, 
 deep annectant gyri come into view. 
 
 Besides the three fissures which have been discussed, the following must be 
 mentioned (the situation of each is shown in Fig. 561). On the outer surface 
 of the hemisphere there are the three frontal sulci, the sulcus frontalis superior, 
 medius, and inferior. The sulcus paxamedialis, the superior and inferior precentral 
 sulci, sulcus diagonalis, the superior and inferior temporal sulci, tiie superior and 
 inferior post-central sulci, the ramus occipitalis, the sulcus occipitalis transversus, 
 
 OCCIPITAL 
 POLE 
 
 LONGITUDINAL 
 FISSURE 
 
 FRONTAL LONGITUDINAL 
 
 POLE FISSURE 
 Fig. 560. — The cerebral hemispheres \ievviKl from above. 
 
 fSpalteholz.) 
 
 the ramus horizontalis, the callo so -marginal sulcus, the inferior transverse furrow 
 (Fig. 561). The sulcus interparietalis (of Turner) is a group of four sulci: the 
 sulcus post-centralis inferior, the sulcus post-centralis superior, the ramus horizontalis, 
 and the ramus occipitalis. The first two are usually joined; the last two remain 
 distinct and separate. When the lips of the intraparietal sulcus are widely 
 opened, deep annectant gyri come into view. 
 
 The fissures of Sylvius, of Rolando, and the parieto-occipital sulcus divide 
 the external surface of tlie hemisphere into four lobes: the frontal, the parietal, the 
 occipital, and the temporal lobes. To these must be added (1) the central lobe or 
 island of Reil, which is situated deeply in the Sylvian fissure, and (2) the olfactory 
 
 I 
 
THE HEMISPHERES OF THE CEREBRUM 
 
 869 
 
 lobe, which is found at the base of the brain and was formerly described under the 
 name of the olfactory nerve. 
 
 The Lobes on the External Surface. — The lobes on the external surface have 
 received their names from the bones of the skull with which they are most nearly 
 in relation, but it must be borne in mind that they do not correspond in shape or 
 limit with the bone after which they are named. The division is, moreover, to a 
 certain extent artificial, as will be seen from the following description. If a line 
 is drawn in continuation of the external oarieto-occipital sulcus downward and 
 outward to the lower border of the hemisphere, it will impinge on a slight notch, 
 the pre-occipital notch, and if a second line is prolonged backward from the hori- 
 zontal part of the fissure of Sylvius to join the first line, the division of the outer 
 surface of the hemisphere into four lobes will be accomplished (Fig. 558). The 
 portion in front of the central sulcus of Rolando is the frontal lobe ; that behind the 
 central sulcus of Rolando and above the fissure of Sylvius is the parietal lobe; the 
 
 Fig. 561.- — Gyri and sulci on the outer surface of the cerebral hemisphere, f', sulcus frontalis superior; 
 /^, sulcus frontalis inferior; i.m., sulcus frontalis medius; p.m.. sulcus paramedialis; A, pars basilaris; B, pars 
 triangularis; C, pars orbitalis; <S, Sylvian fissure; s', anterior horizontal limb (Sylvian fi.ssure); s', ascending 
 limb (Sylvian fissure); s^, posterior horizontal limb (Sylvian fissure); p.c.i., inferior precentral sulcus; p.c.s., 
 superior precentral sulcus; r, fissure of Rolando; g.s.. superior genu; q.i., inferior genu; d, sulcus diagonalis; 
 <', superior temporal sulcus (parallel); <-, inferior temporal sulcus; pi. inferior post-central sulcus; ;>-, superior 
 post-central sulcus; p-', ramus horizontalis; p*, ramus occipitalis; s.o.t., sulcus occipitalis transversus; cm., 
 calloso-marginal sulcus; c.l.r., inferior transverse furrow. (Cunningham). 
 
 portion behind the parieto-occipital sulcus and its imaginary line of continuation 
 to the pre-occipital notch is the occipital lobe; and the part below the fissure of 
 Sylvius and in front of the occipital lobe is the temporal lobe. 
 
 The Fissures, Sulci, and Lobes of the Mesial and Tentorial Surfaces.— The 
 mesial surface of the cerebrum can only be fully viewed by dividing the corpus 
 callosum and the structures beneath it longitudinally in the middle line; in order 
 to expose the tentorial surface, the pons Varolii, cerebellum, and medulla must 
 be removed, by division of the crus cerebri on either side. The diagram (Fig. 562) 
 and the section (Fig. 564) show these fissures and sulci. The parts in the centre, 
 below the corpus callosum, belong to the interior of the brain, and will be disre- 
 garded for the present, while the lobes and fissures of the remaining portion of the 
 hemisphere are considered. The fissures and sulci are ten in number on each side, 
 m addition to a small part of the fissure of Sylvius, the commencement of which 
 is seen separating the frontal and temporal lobes and the beginning and end of 
 the great longitudinal fissure. These fissures and sulci are named the olfactory 
 
870 
 
 THE NERVOUS SYSTEM 
 
 sulci, the orbital sulci, the inferior and middle temporal sulci, the occipito -temporal 
 sulci, the calloso-marginal and the internal parieto-occipital sulci, the calcarine, the 
 collateral, and the dentate or hippocampal fissures. 
 
 The Olfactory Sulcus (sulcus olfadorius) (Figs. 563 and 566) . — The olfactory 
 sulcus is a straight furrow which lodges the olfactory tract and bulb. 
 
 The Orbital Sulcus (sulcus orbitalis) (Figs. 563 and 566) . — The orbital sulcus is 
 usually shaped somewhat like the letter H, and is then composed of an external 
 limb (sulcus orbitalis externus), an internal limb (sulcus orbitalis internus), and 
 a transverse portion (sulcus orbitalis transversus). The parts of the orbital sulcus 
 are often complicated and irregular, and are sulci rather than parts of a sulcus. 
 
 The Inferior Temporal Sulcus (sulcus temporalis inferior). — The inferior temporal 
 sulcus is shown in Fig. 563. 
 
 The Occipito-temporal Sulcus (Fig. 563). — The occipito-temporal sulcus is in 
 the tentorial base of the occipital lobe. It is external to the collateral fissure, is 
 not limited purely to the temporal lobe, and bounds the occipito-temporal gyrus 
 externally. It often consists of two or more portions. 
 
 Fig. 562. — The gyri and sulci on the mesial asjiect of the cerebral hemisphere: r, fissure of Rolando; 
 r.o., rostral sulcus; i.t., incisura temporalis. (Cunningham.) 
 
 The Calloso-marginal Sulcus (sulcus cingulus) (Figs. 562, 564, and 567). — The 
 calloso-marginal sulcus commences below the anterior extremity of the corpus 
 callosum; it at first runs forward and upward, parallel with the rostrum of 
 the corpus callosum, and, winding round in front of the genu of that body, it 
 continues from before backward, between the upper margin of the hemisphere 
 and the convolution of the corpus callosum, to about midway between the ante- 
 rior and posterior extremities of the brain, where it ascends to reach the upper 
 margin of the hemisphere, a short distance behind the superior extremity of the 
 fissure of Rolando. 
 
 The Internal Parieto-occipital Sulcus (sulcus parietooccipitalis) (Figs. 562, 564, 
 and 567) . — The internal parieto-occipital sulcus extends in an oblique direction 
 downward and forward to join the calcarine fissure, on a level with the hinder 
 end of the corpus callosum. 
 
 The Calcarine Fissure (fissura calcarina) (Figs. 562, 564, and 567). — The cal- 
 carine fissure commences, usually by two branches, close to the posterior extremity 
 of the hemisphere. These soon unite, and the fissure runs nearly horizontally for- 
 ward, and is joined by the parieto-occipital fissure, and continues as far as the 
 
THE HEMISPHERES OF THE CEREBRUM 
 
 871 
 
 posterior extremity of the corpus callosum, a little below the level of which it 
 terminates in the limbic lobe. Its anterior part causes the prominence in the 
 interior of the brain known as the hippocampus minor or calcar avis. 
 
 The Collateral Fissure {fissura collateralis) (Figs. 562, 563, 564, and 567). — The 
 collateral fissure is situated on the tentorial surface, below and external to the 
 preceding, being separated from it by the subcollateral or uncinate gyrus. It runs 
 forward, from the posterior extremity of the brain, nearly as far as the tip of the 
 temporal lobe. It lies below the posterior and descending horns of the lateral 
 ventricle, and its middle part causes the prominence in the interior of the brain 
 known as the eminentia collateralis. 
 
 The Dentate or Hippocampal Fissure (fissura hippocampi) (Figs. 563, 564, and 
 567). — The dentate or hippocampal fissure commences immediately behind 
 
 Fig. 563. — Gyri and sulci on the tentorial and orbital aspects of the cerebral hemisphere. (Cunningham.) 
 
 the posterior extremity of the corpus callosum, and runs forward to terminate 
 at the recurved part of the hippocampal gyrus. It causes the prominence of the 
 hippocampus major in the descending horn of the lateral ventricle. 
 
 In addition to these fissures, which are constant, there is frequently an irregular 
 broken fissure, which is sometimes an independent sulcus, but which often appears 
 to be a continuation backward of the posterior part of the calloso-marginal 
 fissure, before it ascends to reach the upper edge of the hemisphere. This 
 has been termed the post-limbic fissure (Fig. 562) . The fissures of the internal 
 and tentorial surfaces map off portions of the hemisphere, which form parts 
 of the lobes found on the external surfaces. That portion which lies in front and 
 above the calloso-marginal fissure belongs almost entirely to the frontal lobe; its 
 posterior extremity, which extends for a short distance behind the upper end of the 
 
872 
 
 THE NERVOUS SYSTEM 
 
 fissure of Rolando, forms a small part of the parietal lobe; that portion which lies 
 above the internal parieto-occipital fissure and behind the calloso-marginal fissure 
 forms apart of the parietal lobe; that between the parieto-occipital fissure above 
 and the calcarine fissure below is a portion of the occipital lobe; and all the region 
 below the calcarine fissure behind and the collateral fissure in front belongs to 
 the temporal lobe. The remainder of the mesial and tentorial surfaces of the 
 hemisphere constitute what Broca termed the limbic lobe, which is subsequently 
 referred to (p. 878). 
 
 The surface of the hemisphere has thus been divided by large sulci and 
 fissures into its different parts — viz., the frontal, the parietal, the occipital, the 
 temporal, the limbic, the olfactory lobes, and the island of Reil. Each of these 
 lobes is further subdivided into convolutions or gyri by smaller fissures, which, 
 though less constant in their arrangement than the larger fissures, have a fairly 
 definite course. 
 
 1. The Frontal Lobe (lohus frontalis) (Figs. 558, 561, 562, 563, 564, 565, and 566). 
 — It is the largest of the lobes of the cerebrum. Its outer surface is bounded behind 
 
 Fig. 564. — Fissures and lobes on the internal surface of the cerebral hemispheres. 
 
 by the central sulcus of Rolando and below by the posterior horizontal limb of 
 the fissure of Sylvius. On the orbital surface the fissure of Sylvius bounds it 
 posteriorly. On the mesial surface it is bounded by the calloso-marginal sulcus. 
 
 External Surface. — On its external surface the frontal lobe presents three sulci 
 and four gyri or convolutions. The sulci are the precentral, the superior frontal, 
 and the inferior frontal. 
 
 The Precentral Sulcus (sulcus 'praecentralis) is divided into two parts: The 
 inferior precentral sulcus (sulcus praecentralis inferior) is composed of two parts 
 (Figs. 561 and 565): one part (the vertical) is placed before the Rolandic fissure; 
 the other part (the horizontal) passes upward and to the front into the middle 
 frontal convolution. The superior precentral sulcus (sulcus praecentralis superior) 
 is vertical in direction and is placed in front of the upper part of the Rolandic 
 fissure. The other frontal sulci are shown in the diagrams. 
 
 The ascending frontal convolution or praecentral g3mis (gyrus centralis anterior or 
 gyrus frontalis ascendens) (Figs. 561 and 565), one of the chief motor areas of the 
 
THE HEMISPHERES OF THE CEREBRUM 
 
 873 
 
 cortex, is a simple convolution, and is limited in front by the precentral sulcus and 
 behind by the fissure of Rolando. It extends from the upper margin of the hemi- 
 sphere above to a little behind the bifurcation of the fissure of Sylvius below. From 
 it two sulci, the superior and inferior frontal sulci [sulcus frontalis superior and sulcus 
 frontalis inferior), run forward and downward, and divide the remainder of the 
 outer surface of the lobe into three parallel principal convolutions, named respect- 
 ively the superior, middle, and inferior frontal convolutions (Figs. 561 and 565). 
 
 The superior or first frontal convolution (gyrus frontalis superior) (Figs. 561 and 
 565) is situated between the margin of the longitudinal fissure and the superior 
 frontal sulcus. It extends above on to the inner aspect of the hemisphere, forming 
 the greater part of the marginal convolution (Figs. 562, 564, and 567), and in front 
 on to the orbital surface, forming the internal orbital convolution (Figs. 563 and 
 
 End of calloso- 
 marginal fissure. 
 
 Ascending fissure 
 of Sylvius. 
 
 Fissure 
 of Sylvius 
 
 ^^P0R^\. 
 
 Fig. 565. — Convolutions and sulci on the external surface of the cerebral hemisphere. 
 
 566). It is usually more or less completely subdivided into two (pars superior 
 and pars inferior) by several depressions of trivial length, the aggregation being 
 called by Cunningham the sulcus paramedians. It is frequently interrupted and 
 broken into several parts by bridging convolutions. 
 
 The second or middle frontal convolution (gyrus frontalis medius) (Figs. 561 and 
 565) is situated between the superior and inferior frontal sulci, and extends from 
 the precentral sulcus on to the orbital surface of the lobe, where it forms the 
 anterior orbital convolution (Figs. 563 and 566). The middle frontal convolution 
 is frequently subdivided into two (pars superior and pars inferior) by a sagittally 
 directed sulcus, the sulcus frontalis medius of Eberstaller. 
 
 The third or inferior frontal convolution (gijrus frontalis inferior) (Figs. 561 and 565) 
 is situated below the inferior frontal sulcus, and extends forward from the lower part 
 of the precentral sulcus, on to the under surface of the lobe, where it forms the pos- 
 
874 
 
 THE NERVOUS SYSTEM 
 
 terior orbital convolutions (Figs. 563 and 566). The inferior frontal convolution is 
 subdivided by the anterior and ascending limbs of the fissure of wSylvius into three 
 parts — viz. : (1) anterior part or the orbital operculum {jyars orhitalis), below the ante- 
 rior limb of the fissure of Sylvius; (2) middle part or "cap" of Broca or the frontal 
 operculum {'pars triangularis) , between the anterior horizontal and the vertical limbs 
 of the fissure of Sylvius; and (3) posterior part or the fronto- parietal operculum (pars 
 hasilaris) , behind the posterior horizontal and vertical limbs of the fissure of Sylvius. 
 In the basilar part is the sulcus diagonalis (d in Fig. 561). The left inferior frontal 
 convolution is, as a rule, more highly developed than the right, and is named the 
 convolution of Broca, from the fact that in 1861 Broca declared that it was the centre 
 for speech. It is now known that the region of speech comprises the posterior part 
 of the inferior frontal convolution and the fronto-parietal operculum. 
 
 GYRUS 
 RECTUS 
 
 ANTERIOR 
 
 PERFORATED 
 
 SPACE 
 
 Fig. 566. — Convolutions and sulci on the under surface of the anterior lobe. 
 
 Under Surface (Figs. 563 and 566).— The under surface of the frontal lobe rests 
 on the orbital plate of the frontal bone, and is sometimes named the orbital lobe. 
 It is divided into three convolutions by a well-marked sulcus, the orbital or 
 tri-radiate sulcus (sulci orhitales). These convolutions are named, from their 
 position, the internal, anterior, and posterior orbital convolutions, and are the con- 
 tinuations respectively of the superior, middle, and inferior frontal convolutions 
 of the external surface. The internal orbital convolution presents a well-marked 
 antero-posterior groove or sulcus, the olfactory sulcus {sulcus olfactorius), for 
 the olfactory bulb and tract; and the portion internal to this is named the gyrus 
 rectus, and is continuous with the marginal gyrus, presently to be described. 
 
 Mesial or Internal Surface (Figs. 562 and 567).— The mesial or internal surface 
 of the frontal lobe is occupied by a single curved convolution, which from its 
 
THE HEMISPHERES OF THE CEREBRUM 
 
 875 
 
 situation is termed the maxginal gyrus (gyrus marginalis). It commences in front 
 of the anterior perforated space, runs along the margin of the longitudinal fissure 
 on the mesial surface of the orbital lobe, where it is continuous with the internal 
 orbital convolution; it then ascends, and runs backward to the point where the 
 calloso-marginal fissure turns upward to reach the superior border of the hemi- 
 sphere. An oval portion at the posterior part of this convolution is sometimes 
 marked off by a vertical fissure, and is distinguished as the paracentral lobule 
 (lobulus paracentralis) , because it is continuous with the convolutions in front and 
 behind the central fissure or fissure of Rolando. In the anterior portion of the 
 marginal gyrus are two sulci named the sulci rostrales. 
 
 2. The Parietal Lobe (lobus pariefalis) (Figs. 558,561,562,564, 565, and 567).— 
 This lobe includes a considerable portion of the surface of the hemisphere. 
 
 Fig. 567. — Convolutions and sulci on the internal surface of the cerebral hemispheres. 
 
 and it also occupies the portion of the mesial surface known as the quadrate 
 lobule or cuneus. It is bounded in front by the central sulcus of Rolando, 
 Posteriorly it is partly separated from the occipital lobe by the external parieto- 
 occipital sulcus. Below it is partly limited by the posterior horizontal limb of the 
 fissure of Sylvius. 
 
 External Surface. — On its external surface the parietal lobe presents for examina- 
 tion one sulcus (which is divided into four parts) and three convolutions. 
 
 The Intraparietal Sulcus of Turner (sulcus intraparietalis) (Figs. 561 and 565), 
 according to Prof. Cunningham, is a group of four sulci — viz., the superior post- 
 central sulcus (sulcus postcentralis superior), the inferior post-central sulcus (sulcus 
 postcentralis inferior), the horizontal ramus (ramus horizontalis) , and the occipital 
 ramus (ramus occipitalis). The first named lies back of the upper portion of the 
 central sulcus of Rolando; the second lies back of the lower portion of the same 
 sulcus. In front of the post-central sulci is the ascending parietal (post-central) 
 convolution (gyrus centralis posterior). The superior and inferior post-central sulci 
 are usually continuous. The upper end of the inferior post-central sulcus is pro- 
 longed upward and backward as the ramus horizontalis between the superior 
 and inferior parietal gyri. The ramus occipitalis may or may not be joined to the 
 ramus horizontalis. It is the external boundary of the arcus parieto-occipitalis. 
 
876 THE NERVOUS SYSTEM 
 
 The ascending parietal convolution or the post-central g3rras {gyrus ascendens parte- 
 talis or gyrus posicentralis) (Figs. 561 and 565) is usually regarded as one of the 
 chief motor areas of the cortex, although Mills, Sherrington and others are of the 
 opinion that the motor areas are all in front of the central sulcus of Roland. The 
 ascending parietal convolution is bounded in front by the central sulcusof Rolando, 
 behind by the superior and inferior post-central sulci. It extends from the great lon- 
 gitudinal fissure above to the posterior horizontal limbof the fissureof Sylvius below. 
 It lies parallel with the ascending frontal convolution, with which it is connected 
 below, and also, sometimes, above the termination of the central sulcus of Rolando. 
 
 The superior parietal convolution (lobulus parietalis superior) (Figs. 561 and 565), 
 still regarded by some as a part of the motor area of the cortex, is bounded in front 
 by the superior post-central sulcus, which lies between it and the previous convolu- 
 tion, but with which it is usually connected above the upper extremity of the sulcus; 
 behind, it is joined to the occipital lobe by a narrow convolution, the first annectant 
 gyrus {arcus parietooccipitalis) ; below, it is separated from the inferior parietal con- 
 volution by the horizontal portion of the intraparietal sulcus; and above, it is 
 continuous on the inner surface of the hemisphere with the quadrate lobe. 
 
 The inferior parietal convolution (lobulus parietalis inferior) (Figs. 561 and 565) is 
 that portion of the parietal lobe which is situated between the ascending portion of 
 the intraparietal sulcus in front, the horizontal portion of the same sulcus above, the 
 horizontal limb of the fissure of Sylvius below, and the posterior boundary of the 
 parietal lobe behind. It is divided into three convolutions: the supramarginal, the 
 angular, and the post-parietal. One, the supramarginal convolution {gyrus supra- 
 marginalis), lies behind the ascending part of the intraparietal sulcus and above the 
 horizontal limb of the fissure of Sylvius, over the extremity of which it arches. It is 
 connected in front with the ascending parietal convolution below the intraparietal 
 sulcus, and behind with the first or superior temporal convolution around the pos- 
 terior extremity of the fissure of Sylvius (Fig. 561) . The angular convolution or the 
 angular gyrus {gyrus angularis) is united anteriorly with the foregoing, while pos- 
 teriorly it is continuous with the middle or second temporal convolution by a process 
 which curves around the superior temporal or parallel sulcus (Fig. 561). The 
 post-parietal convolution or the second annectant gyrus passes around the posterior 
 end of the middle temporal convolution and into the inferior temporal convolu- 
 tion. It joins the inferior parietal convolution to the occipital lobe. 
 
 The Internal or Mesial Surface (Figs. 562 and 564) . — The internal or mesial surface 
 of the parietal lobe is continuous with the external surface over the upper edge of 
 the hemisphere. It is of small size, and forms one square-shaped convolution, 
 which from its shape is termed the quadrate lobe. From its situation above the 
 cuneate lobe it is named the precuneus (praecuneus). The post-limbic sulcus imper- 
 fectly separates the precuneus from the limbic lobe. 
 
 3. The Occipital Lobe {lohus occipitalis) (Figs. 558, 561, 5()2, 563, 564, 565, 
 and 567). — The occipital lobe is indefinitely separated from the temporal and 
 parietal lobes. It is defined by Cunningham as the portion of "the hemisphere 
 which encloses the posterior horn of the lateral ventricle." In form it is pyram- 
 idal, and it possesses an apex, the occipital pole {polus occipitalis), and three 
 surfaces. The inferior surface is directly continuous with the temporal and 
 limbic lobes. On the outer surface the external parieto-occipital fissure partly 
 separates it from the parietal lobe. On the mesial surface the internal 
 parieto-occipital fissure separates it from the precuneus. 
 
 External Surface (Figs. 561 and 565) . — The occipital lobe is divided on its external 
 surface into three convolutions by two indistinct sulci, the superior and middle occip- 
 ital sulci {sulcus occipitalis transversus and sulcus occipitalis lateralis). They are 
 directed backward across the lobe, being frequently small and ill marked ; the supe- 
 rior is sometimes continuous with the horizontal portion of the intraparietal sulcus. 
 
THE HEMISPHERES OF THE CEREBRUM 877 
 
 The superior occipital convolution {gyrus occipitalis superior) is situated above 
 the superior sulcus, and is connected to the superior parietal convolution by the 
 first annectant gyrus. 
 
 The middle occipital convolution (gyrus occipitalis medius) is situated between 
 the superior and middle occipital sulci, and is connected to the angular convolution 
 by the second annectant gyrus, and to the middle temporal convolution by the 
 third annectant gyrus. 
 
 The inferior occipital convolution {gyrus occipitalis inferior) is situated below the 
 middle occipital sulcus, and is sometimes separated from the external occipito- 
 temporal convolution on the under surface of the hemisphere by an inconstant 
 sulcus, the inferior occipital sulcus (sulcus occipitalis inferior). The inferior occipi- 
 tal convolution is connected to the inferior temporal convolution by the fourth 
 annectant gyrus. 
 
 Internal or Mesial Surface (Figs. 562, 564, and 567).— The internal or mesial sur- 
 face of the occipital lobe presents a triangular convolution, which is known as the 
 cuneate lobule {cimeus). I is situated between the internal parieto-occipital sulcus 
 and the calcarine fissure, which, as already mentioned, meet some distance behind 
 the posterior extremity of the corpus callosum. 
 
 The lingual gyrus or subcalcarine convolution {gyrus lingualis) is between the 
 calcarine and collateral fissures, and runs forward into the hippocampal portion 
 of the limbic lobe. A portion of the gyrus lingualis is on the mesial aspect and 
 a portion on the inferior aspect of the occipital lobe (Fig. 563) . 
 
 Inferior Surface (Fig. 563). — The inferior or tentorial surface of the occipital lobe 
 possesses one convolution, the occipito -temporal gyrus, which is continuous wath 
 the temporal lobe and the limbic lobe (p. 878), and is bounded externally by the 
 occipito-temporal sulcus. 
 
 The centre for visual memory is in the external surface of the occipital lobe 
 and the angular gyrus. 
 
 4. The Temporal Lobe (lobus temporalis) (Figs. 558, 561, 562, 563, 564, 565, 
 and 567). — The temporal lobe is sometimes called the temporo-sphenoidal lobe. 
 This lobe lies behind the junction point and below the posterior horizontal limb 
 of the Sylvian fissure. On its inferior (tentorial) surface the collateral fissure 
 separates it from the hippocampal portion of the limbic lobe. The apex of the 
 temporal lobe projects in front of the Sylvian junction. The lobe presents an 
 outer and an inferior surface. 
 
 Outer Surface (Figs. 561 and 565). — The outer surface is subdivided by two 
 sulci, named respectively the first and second temporal sulci. 
 
 The First Temporal Sulcus (sulcus temporalis superior) is well marked, and runs 
 from before backward through the temporal lobe parallel with, but some little 
 distance below, the posterior horizontal limb of the fissure of Sylvius; hence it 
 is often termed the parallel sulcus. 
 
 The Second Temporal Sulcus (sulcus temporalis medius) takes the same direction 
 as the first, but is situated at a lower level, and is often interrupted by one or more 
 bridging convolutions. These two sulci subdivide this surface of the temporal lobe 
 into three convolutions. 
 
 The first or superior temporal convolution (gyrus temporalis superior) is situated 
 between the posterior horizontal limb of the fissure of Sylvius and the first tem- 
 poral sulcus, and is continuous behind with the supramarginal convolution. 
 
 The second or middle temporal convolution (gyrus temporalis medius) lies between 
 the first and second temporal sulci, and is continued behind into the angular and 
 middle occipital convolutions. 
 
 The third or inferior temporal convolution (gyrus temporalis inferior) is placed 
 below the second temporal sulcus; it is connected posteriorly with the inferior 
 occipital convolution, and is also prolonged on to the under or tentorial surface 
 
878 
 
 THE NEBVOUS SYSTEM 
 
 of the temporal lobe (Fig. 563), where it is limited internally by the third tem- 
 poral sulcus, about to be described. 
 
 Inferior Surface (Fig. 563). — The inferior or tentorial surface presents two 
 fissures — viz., the third temporal sulcus and the collateral fissure — the latter fissure 
 has already been described (p. 871). 
 
 The Third Temporal Sulcus {sulcus temporalis in]erior) extends from near the 
 occipital pole behind to near the anterior extremity of the temporal lobe in front, 
 but is, however, frequently subdivided by bridging gyri. 
 
 The convolution on the inferior surface is the fourth temporal or subcollateral 
 or the occipito-temporal convolution. It is situated between the third temporal 
 sulcus and the collateral fissure. 
 
 5. The Central Lobe or Island of Reil (Insula) (Figs. 566, 568, 576, and 577). 
 — The central lobe or island of Reil lies deeply in the Sylvian fissure, and can only 
 be seen when the lips of that fissure are widely separated, since it is overlapped 
 and hidden by the convolutions which bound the fissure. These convolutions are 
 termed the opercula of the insula (opercula insulae) (operculum, a lid) ; they are 
 separated from each other by the three limbs of the Sylvian fissure, and are 
 named the orbital, frontal, fronto-parietal, and temporal opercula (p. 866). The insula 
 
 Fig. 568. — The island of Reil. Left side. The overlapping parts of the hemisphere have been removed. 
 1, 2, 3. Gyri breves. 4, 5. Gyrus longus, bifurcated at its upper extremity. (Dalton.) 
 
 is almost surrounded by a deep limiting sulcus, the limiting sulcus of Reil (sulcus 
 circularis Reili) (Fig. 566 and p. 867) , which separates it from the frontal, parietal, 
 and temporal lobes. When the opercula have been removed, the insula presents the 
 form of a triangular eminence; its apex is directed downward and inward toward 
 the anterior perforated space, and is continuous in front with the posterior 
 orbital convolution. At the apex of the insula the limiting sulcus does not exist, 
 and the gray matter passes into the anterior perforated space. This point is 
 called the limen insulae. The insula is continuous behind with the hippocampal 
 convolution. It is divided into a pre-central and a post-central lobe by the sulcus 
 centralis, which runs backward and upward from the apex of the insula. The pre- 
 central lobe is further subdivided by shallow sulci into three or four short con- 
 volutions, the gjii breves insulae, while the post-central lobe is named the gjTV& 
 longus insulae, and is often bifurcated at its upper extremity. The gray matter of 
 the insula is continuous with that of the different opercula, while its mesial surface 
 corresponds with the external surface of lenticular nucleus of the corpus striatum, 
 from which it is separated by the external capsule and claustrum. 
 
 6. Limbic Lobe (Figs. 564 and 569) . — ^The term limbic lobe or grande lobe 
 limhyjue was introduced by Broca in 1878, and under it he included two convolu- 
 tions — viz., the callosal and hippocampal convolutions, which together arch around 
 
THE HEMISPHERES OF THE CEREBRUM 879 
 
 the corpus callosum and the hippocampal fissure. These he separated on the 
 morphological ground that they are well developed in animals possessing a keen 
 sense of smell (osmatic animals), such as the dog and fox. To the lobe thus de- 
 fined the following parts must be added — viz., the laminae of the septum lucidum, 
 together with the fornix and its fimbriae, which may be regarded as forming an 
 inner or deep arch; the peduncles and 
 longitudinal striae of the corpus cal- ^loIe*^ * a''i,"h°'' 
 
 losum, together with the gyrus den- 1 ;| 
 
 tatus, which form a middle arch, while / i ^~^^\l 
 
 the outer arch is constituted by the / ...-•■ •-.. ^N^^ 
 
 callosal and hippocampal convolutions; / P N. \ 
 
 the first two arches are separated from I ! \ \ 
 
 each other by the corpus callosum. \ \ \ \ 
 
 Convolutions of the Limbic Lobe.— \ "'"; ■^- .:::^^:r~2r^^l 
 
 (1) The callosal convolution {gyrus ^---_L,_ — - — "^ ^^^ctLry 
 
 jornicatiis or qyrus cinquli) (Figs. 562 • "-obe 
 
 ' , _„_. . -'■^ , ^ 1 1 INFERIOR PEDUNCLE 
 
 and 5o7) is an arch-shaped convolu- arch 
 
 tion, lying in close relation to the Fig. 569.-Scheme of ^the^Umbic lobe. (Poirierand 
 
 superficial surface of the corpus cal- 
 losum, from which it is separated by a slit-like sulcus, the callosal sulcus (sulcus 
 corporis callosi). It commences below the rostrum of the corpus callosum. The inner 
 root of the olfactory tract enters the beginning of the convolution. The callosal con- 
 volution curves around in front of the genu, extends along the upper surface of the 
 body, and finally turns downward behind the splenium, where it becomes narrow 
 because the calcarine fissure cuts it. The narrow portion is the isthmus (isthmus 
 gijri fornicati). The isthmus connects the callosal convolution with the gyrus hippo- 
 campi. The callosal convolution is separated from the marginal convolution by the 
 calloso-marginal sulcus, from the precuneus by the post-limbic sulcus, and from the 
 lingual gyrus by the anterior portion of the calcarine fissure. 
 
 (2) The hippocampal convolution (gyrus hippocampi) (Figs. 562 and 563) is 
 bounded above by the hippocampal or dentate fissure, and below by the anterior 
 part of the collateral fissure. Behind, it is continuous superiorly, through the 
 isthmus, with the callosal convolution, and inferiorly with the subcalcarine or lingual 
 convolution. Its anterior extremity is recurved in the form of a hook, and is named 
 the uncinate convolution or uncus (Fig. 567) . Running in the substance of the callosal 
 and hippocampal convolutions, and connecting them together, is a tract of arched 
 fibres, named the fillet of the gyrus fomicatus or the cingulum. The outer root of the 
 olfactory tract passes into the anterior extremity of the hippocampal convolution, 
 and the inner root into the commencement of the callosal convolution, so that these 
 two convolutions, with the addition of the olfactory tract, present a racquet-like 
 appearance — the olfactory tract constituting the handle and the two convolutions 
 the circumference of the blade. 
 
 (3) The dentate convolution (gyrus dentatus) (Figs. 562 and 581) , also called the 
 dentate fascia (fascia dentata hippocampi) . It is situated above the gyrus hippo- 
 campi, from which it is separated by the hippocampal or dentate fissure (fissura 
 hippocampi) (Figs. 562, 564, and 567). The dentate convolution is covered by the 
 fimbria, a prolongation of the posterior pillar of the fornix, and is a narrow, elon- 
 gated convolution, the free surface of which presents a notched or toothed appear- 
 ance, hence its name. Posteriorly it is prolonged as a delicate lamina, the fasciola 
 cinerea, around the splenium of the corpus callosum, and becomes continuous on 
 the upper surface of that body with its mesial and lateral longitudinal striae. 
 Anteriorly it is prolonged into the notch produced by the recurving of the uncus, 
 where it forms a sharp curve; from here it can be traced as a delicate band, the 
 band of Giacomini, over the uncus, on the outer surface of which it is lost. 
 
880 
 
 THE NERVOUS SYSTEM 
 
 The remaining structures which contribute to the formation of the Hmbic lobe 
 will be subsequently described. 
 
 7. The Olfactory Lobe or Rhinencephalon {lohus oljactorius) (Figs. 555 and 
 569). — The olfactory lobe is situated on the under surface of the frontal lobe. It is 
 rudimentary in man and some other mammals, but in vertebrates generally it is well 
 developed, and consists of a distinct extension of the cerebral hemisphere, enclosing 
 a portion of the anterior horn of the lateral ventricle. In man it is long and slender, 
 and may be described as consisting of two parts, the anterior and posterior olfactory 
 lobules. 
 
 The Anterior Olfactory Lobule. — The anterior olfactory lobule is made up of: 
 (1) the olfactory bulb; (2) the olfactory tract; (3) the trigonum olf actorium ; (4) the 
 area of Broca. 
 
 OLFACTORY 
 BULB 
 , GENU OF 
 "CALLOSUM 
 
 SYLVIAN 
 FISSURE 
 
 ANTERIOR PEH- 
 , FORATED SPACE 
 k ..INFUNDI- 
 BULUM 
 
 ..POSTERIOR PER- 
 FORATED SPACE 
 CRUS CEREBRI 
 
 MIDDLE CEREBEL- 
 LAR PEDUNCLE 
 
 OBLONGATA 
 
 '- —CEREBELLUM 
 
 Fig. 570. — Under surface of the brain, showing the superficial origins of the cranial nerves, 
 numerals indicate the nerves. (Testut.) 
 
 The Roman 
 
 (1) The Olfactory Bulb (bulbus olfactorius) (Fig. 570) is an oval mass of reddish- 
 gray color, which rests on the cribriform plate of the ethmoid bone below and 
 the olfactory sulcus of the orbital surface of the frontal lobe above. It forms 
 the anterior expanded extremity of the olfactory tract. Its under surface receives 
 the olfactory nerves, which pass upward through the cribriform plate from the 
 olfactory region of the nose. Its minute structure will be subsequently described. 
 
 (2) The Olfactory Tract (tractus olfactorius) (Fig. 570), often called the olfactory 
 nerve or first cranial nerve, is a band of white matter, triangular on section, the 
 apex being directed upward. It lies in the olfactory sulcus on the under surface 
 of the frontal lobe. Traced backward, it is seen to divide into two roots, an outer 
 
THE HEMISPHERES OF THE CEREBRUM 881 
 
 and an inner. Some have called the olfactory tubercle a middle root. The outer 
 root passes across the outer part of the anterior perforated space to the nucleus 
 amygdalae and the anterior part of the gyms hippocampi. The inner root turns 
 sharply inward, and ends partly in Broca's area and partly in the callosal convolu- 
 tion; in other words, the inner root is continuous with one extremity and the outer 
 root with the other extremity of the limbic lobe (Fig. 569). 
 
 (3) The Trigonum Olfactorium or Olfactory Tubercle is situated between the 
 diverging roots of the olfactory tract, and is sometimes described at the middle or 
 gray root of the tract. It is part of an area of gray matter, which forms the base 
 of the anterior olfactory lobule; another portion of it is termed (4) the area of 
 Broca (area par olf actor ia), the portion of gray matter between the internal root 
 and the peduncle of the corpus callosum; and a third portion, of no special sig- 
 nificance, is situated external to the outer root of the olfactory tract. This area of 
 gray matter is bounded internally and posteriorly by a sulcus, the fissura prima 
 (sidcus par olf actor ius posterior) , which separates it from the peduncle of the corpus 
 callosum and from the posterior olfactory lobule. The area of Broca is continuous 
 with the gyrus fornicatus, and receives fibres from the inner or mesial root. 
 
 The Posterior Olfactory Lobule. — The posterior olfactory lobule corresponds to 
 the portion of the hemisphere called the anterior perforated space (locus perforatum 
 anticus or substantia perforata anterior) (Figs. 566 and 570). It is marked off from 
 the anterior lobule by the sulcus parolfactorius posterior, and is situated at the com- 
 mencement of the fissure of Sylvius. Internally, it is bounded by the peduncle of 
 the corpus callosum, and is continuous with the lamina cinerea. Posteriorly it is 
 bounded by the optic tract, and it is partially concealed by the temporal lobe which 
 overlaps it. It has received the name of anterior perforated space from its being 
 perforated by numerous openings, which transmit blood-vessels to the interior of 
 the brain, and it coi'responds to the under surface of the lenticular nucleus. 
 
 Under Surface or Base of the Encephalon (fades hasalis encephali) (Fig. 
 570). — Having considered the surface of the hemispheres, the student should 
 direct his attention to the base of the brain, before commencing the study of the 
 component parts which make up the two hemispheres. 
 
 The base of the brain presents for examination the under surfaces of the frontal 
 and temporal lobes; the structures contained in the interpeduncular space, with 
 the crura cerebri or cerebral peduncles; the under surfaces of the pons Varolii, 
 cerebellum, and medulla oblongata; and the superficial origins of the cranial 
 nerves. 
 
 The various objects exposed to view (with the exception of the superficial 
 origins of the cranial nerves, which will be considered in another section), in the 
 middle line and on either side of the middle line, are here arranged in the order 
 they are met with from before backward. 
 
 In the Middle Line. On Each Side of the Middle Line. 
 
 Longitudinal fissure. Frontal lobe. 
 
 Rostrum and peduncles of Olfactory lobe. 
 
 corpus callosum. The anterior perforated space. 
 
 Lamina cinerea. Fissure of Sylvius. 
 
 Optic commissure. Optic tracts. 
 
 Tuber cinereum. Crura cerebri. 
 
 Tnfundibulum. Temporal lobe. 
 
 Pituitary body. . Hemisphere of cerebellum. 
 
 Corpora albicantia. 
 Posterior perforated space. 
 Pons Varolii. 
 Medulla oblongata. 
 
 56 
 
882 'J'HE NERVOUS SYSTEM 
 
 The Longitudinal Fissure (fissura longitudinal is cerebri) (p. 865). — The longi- 
 tudinal fissure partially separates the two hemispheres from each other. It 
 divides completely the anterior portions of the two frontal lobes; and on raising 
 the cerebellum and pons it will be seen to separate completely the two occipital 
 lobes; of these two portions of the longitudinal fissure, that which separates the 
 occipital lobes is the longer. The intermediate part of the fissure is filled up by the 
 great transverse band of white matter, the corpus callosum. In the fissure between 
 the two frontal lobes the anterior cerebral arteries ascend on the corpus callosum. 
 
 The Corpus Callosum. — The corpus callosum, the transverse commissure which 
 joins the two cerebral hemispheres, is described on p. 886. It terminates at the 
 base of the brain by a concave margin, which is connected with the tu})er cinereum 
 through the intervention of a thin layer of gray substance, the lamina cinerea. This 
 may be exposed by gently raising and drawing back the optic commissure. A 
 white band may be observed on each side, passing backward from the under sur- 
 face of the corpus callosum, across the posterior margin of the anterior perforated 
 space to the hippocampal gyrus, where it meets the corres}X)nding outer root 
 of the olfactory tract; this band is called the peduncle of the corpus callosum or the 
 gyrus subcallosus (pedunculus corporis callosi). The band may be traced upward 
 around the genu to become continuous with the striae longitudinales on its upper 
 surface. Laterally, this portion of the corpus callosum extends into the frontal 
 lobe. 
 
 The Lamina Cinerea. — The lamina cinerea is a thin layer of gray substance, 
 extending upward in the anterior portion of the great longitudinal fissure from the 
 optic commissure to join the rostrum of the corpus callosum. It is continuous on 
 each side with the gray matter of the anterior perforated space, and forms the 
 anterior part of the inferior boundary of the third ventricle. The portion of the 
 lamina cinerea which is turned upward is called the lamina terminalis. 
 
 The Optic Commissure or Optic Chiasma (chiasmaopticum) . — The optic commissure 
 is situated in the middle line, immediately in front of the tuber cinereum and below 
 the lamina cinerea; that is to say, the commissure is superficial to the lamina in 
 the order of dissection when the base is uppermost. It is the point of junction 
 between the two optic tracts, and will be described with the cranial nerves. Imme- 
 diately behind the diverging optic tracts, and between them and the pedimcles 
 of the cerebrum (crura cerebri or pedunculi cerebri), is a lozenge-shaped interval, 
 the interpeduncular space {fossa interpeduncularis [Tarini]). The posterior recess 
 (recessus posterior) of this space passes for a little way underneath the anterior 
 margin of the pons; the anterior recess (recessus anterior) passes between the 
 corpora albicantia. The floor of the interpeduncular space is the substantia 
 perforata posterior, and in the space are found the following parts: the tuber 
 cinereum, infundibulum, pituitary body, corpora albicantia, and the posterior 
 perforated space. 
 
 The Tuber Cinereum. — The tuber cinereum is an eminence of gray matter, 
 situated between the optic tracts, and extending from the corpora albicantia to the 
 optic commissure, to which it is attached; it is connected with the surrounding 
 parts of the cerebrum, forms part of the floor of the third ventricle, and is con- 
 tinuous with the gray substance in that cavity. From the middle of its under sur- 
 face a conical tubular process of gray matter, about two lines in length, is con- 
 tinued downward and forward to be attached to the posterior lobe of the pituitary 
 body. This is the infundibulum, and its canal, which is funnel-shaped, com- 
 municates with the third ventricle. 
 
 The Pituitary Body (hypophijsis cerebri). — The pituitary body is a small, reddish- 
 gray, vascular mass, weighing from five to ten grains, and of an oval form, situated 
 in the sella turcica, where it is retained by a process of dura mater, named the 
 diaphragma sellae (Fig. 544). This process of the dura covers in the sella turcica, 
 
THE HEMISPHEBES OF THE CEREBRUM 883 
 
 and has a small hole in its centre through which the infundibulum passes, the 
 foramen diaphragmatis sellae (Fig. 544). 
 
 Structure. — The pituitary body is very vascular, and consists of two lobes, 
 separated from one another by a fibrous lamina. Of these, the anterior and the 
 larger is of an oblong form, and somewhat concave behind, where it receives 
 the posterior lobe, which is round. The two lobes differ both in development 
 and structure. The anterior lobe, of a dark, reddish-brown color, is developed 
 from the epiblast of the buccal cavity, and resembles to a considerable extent, in 
 microscopic structure, the thyroid body. It consists of a number of isolated 
 vesicles and slightly convoluted tubules, lined by epithelium and united together 
 by a very vascular connective tissue. The epithelium is columnar and occasion- 
 ally ciliated. The alveoli sometimes contain a colloid material, similar to that 
 found in the thyroid body, and their walls are surrounded by a close network of 
 lymphatic and capillary blood-vessels. The posterior lobe is developed as an 
 outgrowth from the embryonic brain, and during foetal life contains a cavity 
 which communicates through the infundibulum with the cavity of the third 
 ventricle. In the adult it becomes firmer and more solid, and consists of a 
 sponge-like connective tissue arranged in the form of reticulating bundles, 
 between which are branched cells, some of them containing pigment. In the 
 lower animals the two lobes are quite distinct, and it is only in the mammalia 
 that they become fused together. The pituitary body is believed to be a ductless 
 gland, which furnishes an internal secretion. In many cases of acromegaly the 
 gland is enlarged or otherwise diseased. 
 
 The Corpora Albicantia or Corpora Mamillaria. — The corpora albicantia or mam- 
 illaria are two small, round, white masses, each about the size of a pea, placed 
 side by side immediately behind the tuber cinereum, and connected with each 
 other across the mesial plane. They are mainly formed by the anterior crura or 
 pillars of the fornix, which, after descending to the base of the brain, are 
 twisted upon themselves to form loops, and constitute the white covering of the 
 corpora albicantia. A second fasciculus, the bundle of Vicq d'Az3n: (fasciculus 
 ihalamomamillaris) (Figs. 574 and 586), converges from the optic thalamus, and 
 enters the anterior part of each body on its dorso-mesial surface. The corpora 
 albicantia are composed externally of white substance, and internally of gray 
 matter; the nerve-cells of the gray matter are arranged in two sets, inner and 
 outer, the cells of the former set being the smaller. Each corpus is connected 
 to the tegmentum by a small bundle of fibres, the peduncle of the mamillary 
 body (pedunculus corporis mamillaris (Fig. 586).' At an early period of foetal 
 life the corpora albicantia are blended together into one large mass, but become 
 separated about the seventh nionth. In most vertebrates there is only one median 
 corpus albicans. 
 
 The Posterior Perforated Space or Lamina or the Pons Tarini (locu^ perforatum 
 posticus, substantia perforata posterior). — The posterior perforated space cor- 
 responds to a whitish-gray fossa placed between the corpora albicantia in front, 
 the pons Varolii behind, and the crus cerebri on either side. It is in reality a 
 visible portion of the substantia nigra and forms the floor of the interpeduncular 
 fossa. It forms the posterior part of the floor of the third ventricle, and is per- 
 forated by numerous small orifices for the passage of the postero-median ganglionic 
 branches of the posterior cerebral and posterior communicating arteries. Slender 
 white bands are observed in some subjects coming from the gray matter of the 
 posterior perforated space, passing around the crura cerebri, and entering into the 
 pons Varolii. The bands bear the name of the taenia pontis. 
 
 The Pons Varolii (p. 922). — The pons Varolii is situated immediately behind the 
 two crura of the cerebrum. It consists of a broad band of white fibres, which pass 
 transversely from one cerebellar hemisphere to the other; the band becoming 
 
884 
 
 THE NERVOUS SYSTEM 
 
 narrower as it enters the cerebellum. In the middle line on its under surface a 
 narrow groove runs from before backward and accommodates the basilar aitery. 
 
 The Medulla Oblongata, Medulla Spinalis or Bulb (p. 938). — The medulla oblongata 
 emerges from the posterior border of the pons Varolii; it is pyramidal in form, and 
 is continuous below with the cervical portion of the spinal cord. It is marked on 
 its ventral surface by a median fissure, continuous below with the anterior median 
 fissure of the cord, and on either side by secondary fissures and columns, which 
 will be described in the sequel. 
 
 The Frontal Lobe. — The under surface of the frontal lobe, sometimes named 
 the orbital lobe, is seen on the anterior part of the base of the brain on either side 
 of the median line. It has already been described (p. 874). 
 
 The Olfactory Lobe (p. 880). 
 
 The Anterior Perforated Space (p. 881). 
 
 The Fissure of Sylvius (fissura lateralis cerebri). — The fissure of Sylvius at the 
 base of the brain separates the frontal from the temporal lobe, and lodges the 
 middle cerebral artery. It has also been described (p. 866). 
 
 Fig. 671. — Section of the brain. Made on a level with the corpus callosum. 
 
 The Optic Tracts. — The optic tracts are well-marked, flattened bands of fibres, 
 which run obliquely across the crus cerebri on either side, and unite anteriorly to 
 form the optic commissure. They will be described in connection with the cranial 
 nerves. 
 
 The Crura Cerebri or the Peduncles of the Cerebrum (pedunculi cerebri) (p. 906). — 
 The crura cerebri are two thick cylindrical bundles of white matter, which appear 
 
 1 
 
THE HEMISPHERES OF THE CEREBRUM 8S5 
 
 in front of the anterior border of the pons, and diverge as they pass forv/ard and 
 outward to enter the under surface of each hemisphere. They compose the chief 
 portion of the mesencephalon. Each crus is about three-quarters of an inch in 
 length, and is about the same in breadth anteriorly, but somewhat less posteriorly. 
 They are marked upon their surface with longitudinal striae, and each is crossed, 
 just before entering the hemisphere, by the fourth nerve and the optic tract, the 
 latter of which is adherent by its upper surface to the peduncle. Each crus is 
 composed of two parts, a superior or dorsal part, and an inferior, ventral, or pedal part. 
 The dorsal part is known as the tegmentum of the crus cerebri {tegmentum) , the fibres 
 (p. 90S) of which pass up into the region beneath the optic thalamus, a region known 
 as the subthalamic tegmental region. The ventral portion is known as the crusta 
 (basis pedunculi), the fibres of which (p. 907) pass up external to the optic thala- 
 mus and into the internal capsule. On the surface of the crus are two grooves 
 which mark the separation between the tegmentum and the crusta. One groove 
 is on the inner (mesial) surface; it is called the sulcus nervi oculo-motorii, and 
 from it comes the third or motor oculi nerve. The other groove on the outer 
 (lateral) surface is called the sulcus lateralis mesencephali. It passes down into the 
 interval between the superior and middle cerebellar peduncles. From the outer 
 surface of the tegmentum some slender fibres, called the lateral fillet (lemniscus 
 lateralis) , pass to the inferior quadrigeminal body. If a transverse section of the 
 crus is made, the substantia nigra is seen between the tegmentum and the crusta. 
 It is a band of pigmented gray matter which begins somewhat below the 
 upper margin of the pons and ascends into the subthalamic area. 
 
 The Temporal Lobe (Fig. 878). — The under surface of the temporal lobe is 
 visil)le at the base of the brain, on either side of the crura and the structures con- 
 tained in the interpeduncular space. It is separated anteriorly from the frontal 
 lobe by the fissure of Sylvius, and behind is limited by the anterior border of 
 the lateral hemispheres of the cerebellum. The fissures and lobes on its surface 
 have already been described (p. 877). 
 
 The Hemispheres of the Cerebellum (hemisphaeria cerehelli) (p. 929). — The 
 hemispheres of the cerebellum are situated on either side of the middle line, 
 and cover the occipital lobes of the cerebrum, when viewed from the base. 
 The cerebellum differs much in appearance from the rest of the encephalon, 
 being of a darker color, while its convolutions are smaller and narrower, are 
 arranged like the leaves of a book, and hence are called folia. 
 
 General Arrangement of the Parts Composing the Cerebrum. — Each hemi- 
 sphere, as already stated, consists of a central cavity, the lateral ventricle, surrounded 
 by thick and convoluted walls of nervous tissue. 
 
 Interior of the Cerebrum. — If the upper part of either hemisphere is removed 
 with a knife, about half an inch above the level of the corpus callosum, its internal 
 white matter will be exposed. It is an oval-shaped centre, of white substance, 
 surrounded on all sides by a narrow convoluted margin of gray matter, which 
 presents an equal thickness in nearly every part. This white central mass has 
 been called the centrum ovale minus. Its surface is studded with numerous minute 
 red dots (puncta vasculosa), produced by the escape of blood from divided blood- 
 vessels. In inflammation or great congestion of the brain these are very numerous 
 and of a dark color. If the remaining portion of one hemisphere is slightly sepa- 
 rated from the other, a broad band of white substance will be observed, connect- 
 ing them at the bottom of the longitudinal fissure; this is the corpus callosum. The 
 margins of the hemispheres which overlap this portion of the brain are called the 
 labii cerebri. Each labium is part of the callosal convolution already described; 
 and the space between it and the upper surface of the corpus callosum is termed 
 the callosal sulcus (sulcus corporis callosi) (Figs. 562 and 567). The hemispheres 
 should now be sliced off to a level with the upper surface of the corpus callosum, 
 
886 
 
 THE NERVOUS SYSTEM 
 
 when the white substance of that structure will be seen connecting the two 
 hemispheres. The large expanse of medullary matter now exposed, surrounded 
 by the convoluted margin of gray substance, is called the centrum ovale majus 
 of Vieussens (Fig. 571). 
 
 The Corpus Callosum (Figs. 571, 574, and 586). — The corpus callosum is a thick 
 stratum of transversely directed nerve-fibres, by which probably almost every 
 part of one hemisphere is connected with the corresponding part of the other hemi- 
 sphere (Figs. 572 and 573). It connects not only corresponding but also non- 
 corresponding portions of the cortices. The fibres of this body, when they pass 
 from it into the hemispheres radiate in various directions (radiatio corporis callosi) 
 between the fibres of the corona radiata, to terminate in the gray matter of the 
 periphery. According to Cajal the termination is in the layer of small pyramidal 
 cells of the cortex. The corpus callosum thus connects the two hemispheres of 
 the brain, forming their great transverse commissure, and at the same time roofs 
 in the lateral ventricles (Fig. 575). The best conception of its size and form is 
 
 Fig. 572. — Diagram of coronal section of cerebrum to 
 show course of fibres of callosum. (Testut.") 
 
 Fig. 573. — Diagram of lioiizoutal section of cerehnim 
 to show course of fibres of callosum. (Testut . ) 
 
 obtained by making an anterior posterior vertical section through the centre of 
 the brain (Figs. 574 and 586) . It is then seen to be a long, thick, irregularly 
 flattened arch, body of the corpus callosum {truncus corporis callosi); in front taking 
 a sharp bend, the genu {genu corporis callosi) (Fig. 577) , and dipping downward 
 and backward to the base of the brain by a reflected portion, the beak or rostrum 
 {rostrum corporis callosi), which is connected with the lamina cinerea; behind it 
 terminates by a rounded end, which is folded over and is named the splenium 
 {splenium corporis callosi) (Fig. 577) . The corpus callosum is about four inches 
 in length, and extends to within an inch and a half of the anterior and two 
 inches and a half of the posterior extremity of the cerebrum. It is somewhat 
 broader behind than in front, and is thicker at either end than in its central 
 part. The reflected anterior portion of the corpus callosum is called the beak 
 or rostrum; it becomes gradually thinner as it descends, and is attached by 
 its lateral margins to the frontal lobes. At its termination, in addition to 
 joining the lamina cinerea, the corpus callosum gives off on each side a band 
 of white substance, the peduncle of the corpus callosum {gyrus suhcallosus or 
 pedunculus corporis callosi), already described fp. 882). 
 
 Posteriorly, the corpus callosum forms a thick rounded fold, called the pad or 
 splenium, which is free for a little distance as it curves forward, and is then con- 
 tinuous by its under surface with the fornix. The splenium overlaps the mesen- 
 cephalon, but is separated from it by the pia mater, which is prolonged forward to 
 
THE HEMISPHERES GF THE CEREBRUM 
 
 887 
 
 form the velum interpositum (Fig. 548) . On the upper surface of the corpus cal- 
 losum the structure is very apparent, the fibres being collected into coarse transverse 
 bundles (Fig. 571). Along the middle line is a longitudinal depression, the so-caMed 
 raphe, bounded laterally on each side by two or more slightly elevated longitudinal 
 bands (Fig. 571). The internal band on each side is called the stria longitudinalis 
 medialis or nerve of Lancisi. The external band is the stria longitudinalis lateralis or 
 taenia tectae. The external band is beneath the convolution of the corpus callosum. 
 There is an attenuated sheet of gray matter with the external and internal striae, and 
 it, with the striae, constitutes the so-called gyms supra-callosus (pp. 882 and 886). 
 On each side of the middle line the under surface of the corpus callosum forms the 
 roof of the lateral ventricle, while in the mesial plane it is continuous behind with 
 the fornix, being separated from it in front by the septum lucidum, which forms 
 
 Fig. 574. — Vertical median section of the encephalon. showing the parts of the middle line. 
 
 1. Convolution of the corpus callosum. Above it is 
 the calloso-marginal fi.ssure. 
 
 2. Fissure of Rolando. 
 
 3. The parieto-occipital fissure. 
 
 4. 4, point to the calcarine fissure, which is just 
 above the numbers. Between 2 and 3 are the convo- 
 lutions of the quadrate lobe. Between 3 and 4 is the 
 cuneate lobe. 
 
 5. The corpus callosum. 
 
 6. The septum lucidum. 
 
 7. The fornix. 
 
 8. Anterior crus of the fornix, descending to the 
 base of the brain, and turning on itself to form the 
 corpus albicans. The bundle of Vicq d'Azyr is indi- 
 cated by a dotted line. 
 
 9. The optic thalamus. Behind the anterior crus of 
 the fornix a shaded part indicates the foramen of 
 Monro; in front of the number an oval mark shows 
 the position of the gray or middle commissure. 
 
 10. The velum interpositum. 
 
 11. The pineal gland. 
 
 12. The corpora quadrigemina. 
 
 13. The crus cerebri. 
 
 14. The valve of Vieussens (to right of the number). 
 
 15. The pons Varolii. 
 
 16. The third nerve. 
 
 17. The pituitary body. 
 
 18. The optic nerve. 
 
 19 points to the anterior commissure, indicated by 
 the oval outline behind the number. 
 
 a vertical partition between the two ventricles (Figs. 574 and 586). On each 
 side the fibres of the corpus callosum extend into the substance of the hemispheres, 
 connecting them together. The greater thickness of the two extremities of this 
 commissure is explained by the fact that the fibres from the anterior and posterior 
 parts of each hemisphere cannot pass directly across, but have to take a curved 
 direction. The part of the corpus callosum which curves forward on each side 
 from the genu into the frontal lobe and covers the front part of the anterior cornu 
 of the lateral ventricle is called the forceps anterior or forceps minor. The part which 
 
THE NERVOUS SYSTEM 
 
 curves backward from each side of the splenium into the occipital lobe is known 
 as the forceps posterior or forceps major. Between these two parts on each side is 
 a collection of fibres, which cover in the body of the lateral ventricle. These 
 constitute the tapetum or mat. The tapetum helps to form the roof and outer wall 
 of the posterior horn of the lateral ventricle and the outer wall of the posterior 
 portion of the descending horn of the ventricle. These fibres were formerly 
 regarded as fibres of the callosum, but in reality are the fibres of the fasciculus 
 occipito-frontalis which diverge posteriorly. The corpus callosum contains a few 
 projection fibres, but is chiefly composed of association fibres and branches 
 from both association and projection fibres. 
 
 An incision should now be made through the corpus callosum, on either side of the raph^, 
 when two large irregular cavities will be exposed, which extend through a great part of the 
 length of each hemisphere. These are the lateral ventricles. 
 
 The Lateral Ventricle (ventriculus lateralis) (Fig, 575). — The lateral ventricle is an 
 irregular cavity situated in the lower and inner parts of the cerebral hemisphere. 
 
 Fig. 575. — The lateral ventricles of the brain. 
 
 There are two lateral ventricles, one being placed on either side of the middle fine. 
 They are separated from each other by a mesial vertical partition, the septum lucidum 
 (Figs. 574 and 586), but communicate with the third ventricle and indirectly with 
 each other through the foramen of Monro (Figs. 548, 574, and 575) . They are lined 
 by a thin, diaphanous membrane, the ependyma, which is neuroglia covered by 
 ciliated epithelium. The layer of neuroglia is absent over the optic thalamus and 
 the choroid plexus. The lateral ventricles communicate with each other and with 
 
THE HEMISPHEBES OF THE CEREBRUM 889 
 
 the third ventricle, and are moistened by the cerebro-spinal fluid, which, even in 
 health, may be secreted in considerable amount. Each lateral ventricle consists of 
 a central cavity or body and three prolongations from it, termed comua. The 
 anterior ^:ovn\l cnvxes, forward and outward into the frontal lobe; the posterior 
 backward and inward into the occipital lobe; and the middle descends into the 
 temporal lobe. 
 
 The Septum Lucidum (septum pellucidum) (Figs. 574, 586, and 587) is composed 
 of two thin, vertical laminae, which lie in the median line with their mesial sur- 
 faces almost in contact. These sheets are triangular and can be separated, and 
 the cavity thus shown is called the fifth ventricle (cavum septi pellucidi) (Fig. 575). 
 It contains a little fluid, but does not communicate with the general ventricular 
 cavity. Each lamina of the septum lucidum bears the name of the lamina septi 
 pellucidi. The front part of the septum lucidum lies behind the genu of the corpus 
 callosum, and below it passes toward the base of the brain between the fornix and 
 the posterior margin of the rostrum, to terminate in the subcallosal gyrus. Pos- 
 teriorly, the septum lucidum passes back between the fornix and the body of the 
 corpus callosum, being attached to each structure. 
 
 The Central Cavity or Body of the lateral ventricle (ventriculus lateralis [pars 
 centralis]) (Fig. 575) is situated in the lower part of the parietal lobe. It is an 
 irregularly curved cavity, triangular in shape on transverse section, and presents 
 a roof, a floor, an inner wall, and an outer wall. Its roof is formed by the under 
 surface of the corpus callosum; its mesial wall is the septum lucidum, which sepa- 
 rates it from the opposite ventricle and connects the under surface of the corpus 
 callosum with the fornix; its external wall is the internal capsule; its floor is formed 
 by the following parts, enumerated in their order of position, from before back- 
 ward ; the caudate nucleus of the corpus striatum, taenia semicircularis, the epithe- 
 lial covered optic thalamus, the epithelial covered choroid plexus, the superior 
 surface of the body of the fornix and part of its posterior pillar. 
 
 The Anterior Comu or Frontal Horn (cornu anterius) (Fig. 575) passes forward and 
 outward, with a slight inclination downward, from the foramen of Monro into the 
 frontal lobe, curving round the anterior extremity of the caudate nucleus. Its roof 
 is the forceps minor of the corpus callosum, and its floor the upper surface of 
 the reflected portion of the corpus callosum, the rostrum. It is bounded mesially 
 by the anterior portion of the septum lucidum, and externally by the head of 
 the caudate nucleus of the corpus striatum. Its apex reaches the posterior surface 
 of the genu of the corpus callosum. 
 
 The Foramen of Monro (foramen interventriculare) (Figs. 548, 574, 575, and 587) 
 extends from the anterior and superior extremity of the third ventricle and the point 
 of junction of the anterior horn with the central cavity of the lateral ventricle. It 
 lies between the anterior pillar of the fornix and the anterior margin of the optic 
 thalamus This foramen connects the third ventricle with the two lateral ventricles. 
 
 The Posterior Comu or Occipital Horn (cornu posterius) (Fig. 575) curves backward 
 into the substance of the occipital lobe, its direction being backward and outward, 
 and then inward ; itsconcavity is therefore directed inward. Its roof is formed by the 
 tapetum of the corpus callosum passing to the temporal and occipital lobes, which 
 also helps to bound this horn externally. On its mesial wall is seen a longitudinal 
 eminence, which is in an involution of the ventricular wall produced by the 
 calcarine sulcus; this is called the hippocampus minor (calcaravis). Just above this 
 the forceps major of the splenium, sweeping around to enter the occipital lobe, 
 causes another projection, which is known as the bulb of the posterior horn (bulbus 
 cornu posterius). The hippocampus minor and bulb of the posterior horn are 
 extremely variable in their degree of development, being in some cases ill defined, 
 while in others they are unusually prominent. The balance of the posterior horn 
 is bounded by the white substance of the occipital lobe. 
 
890 
 
 THE NERVOUS SYSTEM 
 
 Between the middle and posterior cornu is a triangular area, called the txigonum 
 ventriculi (see Descending Horn). 
 
 The Middle or Descending Cornu or Temporal Horn {cornu injerius) (Figs. 575, 581, 
 and 583), the largest of the three traverses the temporal lobe of the brain, forming in 
 its course a remarkable curve around the back of the optic thalamus. It passes at 
 first backward, outward, and downward, and then curves around the crus cerebri, 
 forward and inward, to within an inch of the apex of the temporal lobe, its direction 
 being fairly well indicated on the surface of the brain by that of the parallel sulcus. 
 Its antero-extemal boundary or roof is formed by the under surface of the tapetum of 
 the corpus callosum, the pulvinar of the optic thalamus, and the inferior layer of the 
 internal capsule. The tail of the nucleus caudatus of the corpus striatum and the 
 taenia semicircularis are also prolonged into it, and extend forward in the roof of 
 the descending horn to its extremity, where they end in a mass of gray matter, the 
 amygdaloid nucleus {nucleus amygdalae); this nucleus is merely a localized thick- 
 ening of the adjacent gray cortex. The posterior boundary or floor of the lateral 
 ventricle presents for examination the following parts: the hippocampus major 
 {hippocampus), pes hippocampi (digitationes hippocampi), eminentia collateralis 
 or pes accessorius, corpus fimbriatum (fimbria hippocampi), prolonged from the 
 posterior pillar of the fornix, and the choroid plexus. Along the medial aspect of 
 the descending cornu there is a cleft-like opening, the choroid fissure, which is 
 
 the lower part of the trans- 
 verse fissure, through which 
 the choroid plexus of the pi a 
 mater is invaginated into the 
 ventricle, but covered by the 
 epithelium of the ependyma, 
 which is pushed in before it. 
 Upon the inner wall are also 
 noted the epithelial covering, 
 the pulvinar, and the dentate 
 convolution or fascia (fascia 
 dentata hippocampi) (Figs. 562 
 and 581) , which is the irregu- 
 lar and free cortical margin. 
 
 The Corpus Striatum (Figs. 
 575,576, 577, 580, and 584), 
 the basal ganglion of the hemi- 
 sphere, has received its name 
 from the striped appearance 
 which its section presents, 
 in consequence of diverging 
 white fibres being mixed with 
 the gray matter which forms 
 the greater part of its sub- 
 stance. It is situated to the 
 front and to the outside of the 
 optic thalamus. The corpus 
 striatum measures about two 
 inches in its antero-posterior 
 diameter and one and a quarter inches transversely.^ The larger portion of this body 
 is embedded in the white substance of the hemisphere, and is therefore external 
 to the ventricle. It is termed the extra-ventricular portion or the lenticular nucleus 
 
 CLAUS 
 TRUM 
 
 ANTERIOR PILLARS 
 OF FORNIX 
 
 POSTERIOR PILLAR 
 OF FORNIX 
 
 Fig. 576. — Horizontal section of Icn iicniisphere through the basal 
 ganglia, viewed from above. C.N., caudate nucleus. (Testut.) 
 
 ' Anatomy of the Brain and Spinal Cord. By Harris E. Santee. 
 
THE HEMISPHERES OF THE CEREBRUM 
 
 891 
 
 (nucleus lent if or mis); a part, however, is visible in the ventricle and its anterior 
 cornu; this is the intra-ventriculax portion or the caudate nucleus (nucleus caudatus). 
 These two portions are separated by the internal capsule. 
 
 The caudate nucleus (nucleus caudatus) (P^igs. 576, 577, 579, and 580) is a pear- 
 shaped, highly arched mass of gray matter; its broad anterior extremity, the bulb 
 or head {caput nuclei caudati), is directed forward into the forepart of the body 
 and anterior cornu of the lateral ventricle; its narrow posterior end, the tail or 
 surcingle [cauda nuclei caudati), is directed outward and backward on the floor 
 of the body of the lateral ventricle and on the outer side of the optic thalamus, 
 from which structure it is separated by the taenia semicircularis (Fig. 577) ; it 
 is continued downward into the descending cornu of the lateral ventricle and 
 
 Fig. 577. — Middle part of a horizontal section through the cerebrum at the level of the dotted line in the 
 small figure in one hemisphere. (From Ellis, after Dalton.) 
 
 is continued forward in the roof to terminate in the amygdaloid nucleus, a collec- 
 tion of gray matter in the apex of the temporal lobe. It is covered by the lining 
 of the ventricle, and crossed by some veins of considerable size. It is separated 
 from the extra-ventricular portion, in the greater part of its extent, by a lamina 
 of white matter which is called the internal capsule, but the two portions of the 
 corpus striatum are united in front. 
 
 The lenticular nucleus (nucleus lentiformis) (Figs. 576, 577, 579, and 580) is a 
 mass of gray matter which lies external to the caudate nucleus and the thalamus, 
 and is only seen in sections of the hemisphere. The laminae of the internal capsule 
 separate it from the ventricle. If a coronal section is made through the anterior 
 portion of the lenticular nucleus, it is seen to be continuous below with the head of 
 the caudate nucleus (Fig. 578) . Above strands of gray matter join the two nuclei. 
 
892 
 
 THE NERVOUS SYSTEM 
 
 and these bands pass through the anterior part of the white internal capsule and' 
 give it a striated appearance; hence the term corpus striatum, which is applied to 
 the mass of which the two nuclei are parts. When divided horizontally, it pre- 
 sents, to some extent, the appearance of a biconvex lens, while a vertical trans- 
 verse section of it gives a somewhat triangular outline. It does not extend as far 
 forward or backward as the nucleus caudatus. It is bounded externally by a 
 lamina of white matter called the external capsule {capsula externa) (Figs. 576, 
 577, 578, and 579) , on the outer surface of which is a thin layer of gray matter 
 termed the bulwark or claustrum (Figs. 576, 577, 578, and 579) . The claustrum 
 presents ridges and furrows on its outer surface, corresponding to the convolu- 
 tions and sulci of the island of Reil, from which it is separated by a thin white 
 lamina (Figs. 576, 577, and 578). 
 
 Upon making a transverse vertical section through the middle of the lenticular 
 nucleus, it is seen to present two white lines, external and internal medullary 
 laminae {laminae medullare externa et interna) (Fig. 579) , parallel with its lateral 
 border, which divide it into three zones, of which the outer and largest is of a 
 reddish color, and is known as the putamen, while the two inner are paler and of a 
 yellowish tintj and constitute the globus pallidus (Figs. 578 and 579) . All three 
 zones are marked by fine radiating white fibres, which are most distinct in the 
 putamen. The gray matter of the corpus striatum is traversed by nerve-fibres, 
 some of which are believed to originate in it. The cells of the corpus striatum 
 are multipolar, both large and small; those of the lenticular nucleus containing 
 yellow pigment. 
 
 The internal capsule (capsula interna) (Figs. 576, 577, 578, 579, and 580) is 
 formed by fibres of the crusta of the crus cerebri, supplemented by fibres derived 
 from the corpus striatum and optic thalamus on each side. Sagittal section ex- 
 hibits a superior lamina and an inferior lamina, continuous with each other behind, 
 but separated in front by the Sylvian fissure. The inferior lamina is thin and 
 its fibres terminate in the parietal and temporal lobes. The superior lamina 
 is thick, contains most of the crusta, and the term internal capsule as usually 
 employed is synonymous with it. In horizontal section (Figs. 576, 577, 578, 
 and 579) the internal capsule is seen to be somewhat abruptly curved, with its 
 convexity inward; the prominence of the curve is called the knee or genu of the 
 internal capsule (genu capsule internal) (Fig. 578) , and projects between the cau- 
 date nucleus and the optic thalamus. The portion in front of the genu is termed 
 the frontal portion, the anterior limb or the lenticulo -striate division (pars frontalis 
 capsulae internae), and separates the lenticular from the caudate nucleus; the por- 
 tion behind the genu is the occipital portion, the posterior limb or the lenticulo -optic 
 division (pars occipitalis capsulae internae), and separates the lenticular nucleus 
 from the optic thalamus. 
 
 Fibres of the Internal Capsule (Figs. 578 and 579). Inferior Lamina. — The 
 fibres of the inferior lamina of the internal capsule pass externally under the len- 
 ticular nucleus, over the amygdala and descending horn of the lateral ventricle, 
 and reach the parietal lobe and the temporal lobe. The motor fibres constitute 
 a portion of the motor tempore -pontal tract which extend from the temporal cortex 
 to the nucleus pontis. The sensory fibres consist of a portion of the acustic radia- 
 tion, which passes from the corpus geniculata interna to the auditory cortex in the 
 temporal lobe, and ansa peduncularis, a tract of common sensation which passes 
 from the optic thalamus to the sensory region of the cortex. Some of the fibres 
 of the median fillet join the ansa peduncularis and pass through the inferior lamina. 
 
 Superior Lamina. — This portion is often spoken of as though it were the entire 
 internal capsule. It contains the greater part of the crusta and enters the 
 corona radiata. The pyramidal tract is in the knee of the internal capsule. Its 
 fibres come from the cortical region about the central sulcus of Rolando and 
 
THE HE3IISPHEIIES OF THE CEREBRUM 
 
 893 
 
 pass through the knee of the internal capsiile; most of them, by way of the 
 middle of the crusta, to reach the spinal cord (p. 907) ; some of them end in the 
 pons and medulla. The anterior segment of the superior lamina of the internal 
 capsule contains motor fibres which come from the prefrontal region of the 
 cortex and pass by way of the inner one-fifth of the crusta to the nucleus pontis 
 
 B. Kn. 
 
 Hypoglossus 
 
 r. lie. 
 
 Audifory 
 
 tract 
 
 Fig. 578. — Horizontal section through the right hemisphere. B. kn, knee of corpus callosum; Vh, anterior 
 horn of lateral ventricle; Fg, inferior part of third frontal convolution; /. stric, lenticulo-striate division of in- 
 ternal capsule; Knie. ic, knee of internal capsule; I. optic, lenticulo-optic division of internal capsule; Th, optic 
 thalamus; ./, i.sland of Reil; cl, claustrum; Operc, operculum; T\, first temporal convolution; r. lie, retrolenticular 
 region of internal capsule; C.A., hippocampus major; cnlc, calcarine fissure; Hh, posterior horn of lateral ventricle; 
 8S, optic radiation of Gratiolet; T«, second temporal convolution; Facialis, position in capsule of motor tract 
 to the face; Hypofjlossus, position of tract to the tongue; Arm, position of tract to the arm; Bein, position of 
 tract to the leg; iS.fi., sensory fibres; S, visual tract; A, auditory tract. (M. Allen Starr, after von Monakow.) 
 
 and nuclei of cranial nerves. These fibres constitute the fronto-pontal tract 
 (tractus cerebrocorticofrontalis fontalis). In the posterior segment of the supe- 
 rior lamina of the internal capsule is a part of the tract from the temporal 
 cortex to the nucleus pontis and the nuclei of cranial motor nerves, the balance 
 
894 
 
 THE NEBVOUS SYSTEM 
 
 of which tract is in the inferior lamina. This path occupies the outer one-fifth 
 of the crusta, and is the temporo-pontal tract (tractus cerebrocorticopontalis tem- 
 poralis). 
 
 The sensory fibres include common sensory fibres and fibres of special sense. 
 Fibres of common sensation exist in both the anterior and posterior segments, 
 and these fibres pass from the optic thalamus to the sensory region of the cortex, 
 and are known as the cortical fillet. The fibres of special sense are found where 
 the superior lamina joins the inferior lamina. 
 
 The optic radiations of Gratiolet (radiatio occipitothalamica [Grafioleti]) are in 
 the portion back of the lenticular nucleus, and pass from the optic thalamus 
 and corpus geniculatum externum to the cuneus. 
 
 The auditory radiations (radiatio temporothalamica) are also back of the len- 
 ticular nucleus and pass from the corpus geniculatum externum to the temporal 
 cortex. 
 
 Numerous fibres of the internal capsule give off collaterals which reach the 
 opposite hemisphere by way of the corpus callosum, none of them reaching the 
 cortex. 
 
 Note. — The above description of the fibres of the internal capsule is largely taken from 
 the Anatomy of the Brain and Cord, by Harris E. Santee, M.D. 
 
 As the fibres of the internal capsule ascend to reach the various convolutions 
 of the cerebral hemisphere they spread out like an open fan. This expansion 
 is the corona radiata. The constituent parts and fibre-groups of the internal 
 capsule are shown in Figs. 578 and 579. 
 
 The external capsule (capsula externa) (Figs. 576, 577, 578 and 579) is a lamina 
 of white matter, situated on the outer side of the lenticular nucleus, between it 
 
 and the claustrum, and is continuous 
 with the internal capsule in front 
 of and behind the putamen. It is 
 made up of fibres derived partly from 
 the anterior white commissure (Fig. 
 580) and partly from the subthalamic 
 region. 
 
 The Claustrum (Figs. 576, 577, 578, 
 and 579) is a thin layer of gray mat- 
 ter, situated on the outer surface of 
 the external capsu'le. On transverse 
 section it is seen to be triangular, 
 with its apex directed upward and its 
 base downward. Its inner surface, 
 which is contiguous to the external 
 capsule, is smooth, but its outer sur- 
 face presents ridges and furrows 
 which correspond with the convolutions and sulci of the island of Reil, with 
 which it is in close relationship. The claustrum is regarded as a detached por- 
 tion of the gray matter of the island of Reil, from which it is separated by a 
 layer of white fibres, the band of Baillarger (capsula extrema) (Figs. 576 and 577). 
 The cells of the claustrum are small and spindle-shaped, and contain yellow 
 pigment ; they are similar to those found in the deepest layer of the cortex. 
 
 The Taenia Semicircularis (stria terminalis) (Figs. 575, 577, and 584) is a narrow, 
 whitish band of medullary substance, situated in the depression between the cau- 
 date nucleus and the optic thalamus. Anteriorly its fibres are partly continued into 
 the anterior pillar of the fornix; some, however, pass over the anterior commissure 
 to the gray matter between the caudate nucleus and septum lucidum, while 
 
 Fio. 579. — Scheme of the internal capsule. (Jakob.) 
 
THE HEMISPHERES OF THE CEREBRUM 895 
 
 others penetrate the caudate nucleus. Posteriorly it is continued into the roof of the 
 middle or descending horn of the lateral ventricle, at the extremity of which it enters 
 the amygdaloid nucleus, an oval mass of gray matter, situated in the roof of the 
 lower extremity of the descending horn. Like the corpus striatum, it is formed 
 by a localized thickening of the gray matter of the cortex cerebri. Superficial to it 
 is a large vein, vena corporis striati, which receives numerous small veins from the 
 surface of the corpus striatum and optic thalamus; it unites with the choroid 
 vein to form the vein of Galen (p. 856). On the surface of the vein of the 
 corpus striatum is a narrow band of white fibres, named the lamina cornea. 
 The remains of the corpus callosum should now be removed in order to ex{X)se the fornix. 
 
 The Fornix (Figs. 574, 575, 576, 577, 580, 582, 583, 586, and 587).— The fornix 
 is a longitudinal, arch-shaped lamella of white matter, situated beneath the 
 corpus callosum, with which it is continuous behind, but from which it is sep- 
 arated in front by the septum lucidum. It may be described as consisting of 
 two symmetrical halves, one for either hemisphere. The two portions are not 
 united to each other in front and behind, but their central parts are joined together 
 in the middle line. The two anterior, separated parts are called the anterior 
 pillars; the intermediate united portions constitute the body of the fornix; and 
 the posterior parts, which are also separated from each other, are called the 
 posterior pillars. 
 
 The Body of the Fornix (corpiis Jomicis) is triangular, narrow in front, broad 
 behind. Its upper surface is connected, in the median line, to the septum lucidum 
 in front, and the corpus callosum behind; laterally this surface forms part of the 
 floor of each lateral ventricle. Its under surface rests upon the velum interpositum, 
 which separates it from the third ventricle and the inner portion of the upper 
 surface of the optic thalami. Its outer edge, on each side, is free, and is connected 
 with the choroid plexuses. 
 
 The Anterior Pillars of the Fornix (columnae fornicis) arch downward toward 
 the base of the brain and are separated from each other by a narrow interval. 
 They are composed of white fibres, which descend immediately behind the 
 anterior commissure, where each anterior pillar passes through the inner part of 
 the optic thalamus of that side. At the base of the brain each pillar becomes 
 twisted upon itself to form a loop, somewhat resembling the figure 8. The lowest 
 part of the loop constitutes the white matter of the corresponding corpus albicans, 
 from which the fibres can apparently be traced upward and backward, as the bundle 
 of Vicq d'Azyr, into the substance of the corresponding optic thalamus (Figs. 574 
 and 586). It must be stated, however, that there is probably no direct continuity 
 between this bundle and the anterior pillar of the fornix — the latter possibly ending 
 in the gray matter of the corpus albicans. The anterior pillars of the fornix are 
 joined in their course by the peduncles of the pineal gland and the superficial fibres 
 of the taenia semicircularis, and receive fibres from the septum lucidum. Zucker- 
 kandl describes an olfactory fasciculus, which becomes detached from the main 
 portion of the anterior pillar of the fornix, and passes downward, in front of the 
 anterior commissure, to the base of the brain, where it divides into two bundles, 
 one joining the inner root of the olfactory tract; the other, the peduncle of the 
 corpus callosum, and through it reaching the hippocampal convolution. 
 
 Between the anterior pillars of the fornix and the anterior extremity of the 
 optic thalamus an oval aperture is seen on each side; this is the foramen of Monro 
 {foramen interventriculare) (Figs. 548, 574, 575, and 587). The two openings 
 descend toward the middle line, and lead into the upper part of the third ven- 
 tricle. Through this foramen the lateral ventricles communicate with the third 
 ventricle, and consequently with each other; through it also the two choroid plex- 
 uses become joined with each other across the middle line. The boundaries of the 
 
896 
 
 THE NERVOUS SYSTEM 
 
 opening are, above and in front, the anterior pillars of the fornix; behind, the 
 anterior extremity of the optic thalamus. 
 
 The Posterior Pillars of the Fornix (crura fornicis) are the backward prolongations 
 of the two halves of the body of the fornix. They are flattened bands, and, at their 
 commencement, are intimately connected by their upper surfaces with the corpus 
 callosum. Diverging from one another, each curves round the posterior extremity 
 of the optic thalamus, and then passes downward and forward into the descending 
 horn of the lateral ventricle. Here it lies along the concavity of the hippocampus 
 major, on the surface of which some of its fibres are spread out, the alveus, while 
 the remainder are continued, as the fimbria, the corpus fimbriatum, the taenia 
 fornicis or the taenia hippocampi (for it bears these different names) (Figs. 562, 
 575, 577, and 583), into the hook or uncus of the hippocampal convolution. Upon 
 examining the under surface of the fornix, between its diverging posterior pillars, 
 a triangular portion of the under surface of the corpus callosum may be seen. 
 On it are a number of curved or oblique lines passing between the two pillars 
 of the fornix. This portion has been termed the lyra or psalterium (Fig. 583) , 
 from the fancied resemblance it bears to a harp. It is also called the commissura 
 hippocampi. In some cases there is a small space intervening between the lyra 
 and the under surface of the corpus callosum known as Verga's ventricle. 
 
 The Anterior Commissure of the Cerebrum (commissura anterior cerebri) (Figs. 580, 
 584, and 587) . — The anterior commissure of the cerebrum is a bundle of white fibres, 
 
 in the anterior wall of the third ven- 
 tricle, placed in front of the ante- 
 rior pillars of the fornix, behind the 
 rostrum of the corpus callosum, 
 and resting upon the lamina ter- 
 minalis. The anterior commissure 
 connects the two hemispheres, and 
 in vertebrates possessing a corpus 
 callosum is an extremely import- 
 ant structure. On transverse sec- 
 tion it is oval in shape, its largest 
 diameter being vertical in direction 
 and measuring about one-fifth of 
 an inch. Its fibres pass backward 
 and downward through the globus 
 pallidus and below the putamen 
 on each side, from which point 
 most of the fibres radiate to the 
 cortex, but some go to the external 
 capsule. The fibres of the an- 
 terior commissure are divisible into two groups: 1. An anterior group (-pars ante- 
 rior or pars olfactoria), the fibres of which join the limbic lobes and connect each 
 limbic lobe to the olfactory tract of the opposite side. The fact that the pais 
 anterior contains fibres from the olfactory tract of the opposite side may serve to 
 explain the condition of crossed anosmia, e. g., where there is a lesion in one 
 temporal lobe with a loss of smell in the olfactory area of the opposite side of the 
 nose. 2. A posterior group (pars posterior or pars occipitotemporalis) , the fibres 
 of which pass to the cortex of the temporal lobe and of the lower part of the 
 occipital lobe. 
 
 The Septum Lucidum (septum pellucidum) (Figs. 574,586, and 587) .—The septum 
 lucidum is a thin, double, vertically placed partition, which forms the internal 
 bpundary of the body and anterior horn of the lateral ventricle. It consists of two 
 distinct laminae, separated in part of their extent by a narrow chink or interval, 
 
 ANTERIOR PILLARS 
 OF FORNIX 
 
 Fio. 580. — Anterior commissure, left half, viewed from above. 
 (Testut.) 
 
THE HEMISPHERES OF THE CEREBRUM 
 
 897 
 
 called the fifth ventricle. It is a thin, semitransparent septum, attached, above, 
 to the under surface of the corpus callosum ; in front to the reflected portion of the 
 corpus callosum; below it passes between the fornix and the posterior margin of 
 the rostrum to terminate in the sub-callosal gyrus; posteriorly it is between the 
 fornix and body of the corpus callosum, being attached to each. It is triangular 
 in form, broad in front and narrow behind; its inferior angle corresponds with 
 the upper part of the anterior commissure. The outer surface of each lamina is 
 directed toward the lateral ventricle, and is covered by the ependyma of that 
 cavity, while its medial surface bounds the cavity of the fifth ventricle (p. 889). 
 Fifth Ventricle {cavum septi pellucidi). — The fifth ventricle was originally a part 
 of the great longitudinal fissure, which was shut off by the union of the hemi- 
 spheres in the formation of the corpus callosum above and the fornix below. 
 Each half of the septum is therefore formed by the medial wall of the hemisphere, 
 and consists of an internal layer of gray matter, derived from the gray matter of 
 the cortex, and an external layer of white substance continuous with the white 
 matter of the cerebral hemispheres. The fifth ventricle differs from the other 
 ventricles of the brain, inasmuch as it is not developed from the cavity of the cere- 
 
 Eminentia ) 
 collateralis. j 
 
 Hippocampus 
 major. 
 
 Gray matter 
 
 of the 
 hippocampus. 
 
 r Fascia 
 
 \ dentata. 
 
 f Uncinate 
 
 I convolution. 
 Uncinate 
 process or 
 uncus. 
 
 Fig. 581. — Transverse section of the middle horn of the lateral ventricle. 
 
 Mr. F. A. Barton.) 
 
 (From a drawing by 
 
 bral vesicles, it is not lined by ciliated epithelium but by altered pia mater, and 
 it does not communicate with the general ventricular cavity; further, tlie fluid 
 it contains is not cerebro-spinal fluid but is of the nature of lymph. 
 
 The structures on the floor of the descending horn of the lateral ventricle will 
 now be described. 
 
 The Hippocampus Major or Comu Ammonis (Figs. 581 and 583) is a white emi- 
 nence, about two inches in length, of a curved elongated form, extending through- 
 out the entire length of the floor of the descending horn of the lateral ventricle. 
 At its lower extremity it becomes enlarged, and presenting two or three rounded 
 elevations with intervening depressions, it resembles the paw of an animal, and 
 is called the pes hippocampi (digitationes hippocampi) (Fig. 583) . If a transverse 
 section is made through the hippocampus major, it will be seen that this eminence 
 is produced by the folding of the cortex of the brain to form the dentate or hippo- 
 campal sulcus (Figs. 562, 563, 564, and 567). The dentate fissure is separated 
 from the choroid fissure by the dentate gyrus or dentate fascia (fascia dentata) 
 (Figs. 562 and 581) . The hippocampal gyrus and the fifth temporal gyrus together 
 constitute the uncinate convolution (Figs. 567 and 581) . The uncus (Fig. 581) is the 
 
 57 
 
898 
 
 THE NERVOUS SYSTEM 
 
 hook-like anterior extremity of the hippocampal or uncinate gyrus. To the outer 
 side and parallel with the hippocampus major an elongated eminence, the 
 eminentia collateralis, is frequently recognized (Fig. 581). It corresponds with 
 the middle part of the collateral fissure, and its size depends on the direction and 
 depth of this fissure. The main mass of the hippocampus major consists of gray 
 matter, but on its ventricular surface is a thin layer of white matter, known as 
 the alveus, which is continuous with the corpus fimbriatum of the fornix and 
 is covered by the ependyma of the ventricle. Dr. J. G. Macarthy, of McGill 
 University, Montreal, has shown^ that, if the alveus and superficial strata of gray 
 matter be reflected from the surface of the hippocampus by an incision carried 
 along its convexity, the "core" of the hippocampus, as he terms it, presents in 
 many cases a corrugated or crimped appearance. 
 
 The Corpus Fimbriatum, Taenia Fomicis, or Fimbria {taenia hippocampi or taenia 
 fimbriae) (Figs. 562, 575, 577, and 583) has already been mentioned as a part of the 
 posterior pillar of the fornix. It consists of a narrow white band, which is placed 
 immediately below the choroid plexus, and is attached by its deep surface to the 
 
 _ Fornix 
 
 Optic thalamus 
 Corpora quadrigemina 
 
 FiQ. 682. — Diagram showing the mode of formation of the velum interpositum. 
 
 white matter or alveus of the hippocampus major as it courses through the descend- 
 ing cornu of the lateral ventricle. It can be traced as far as the uncus or hook of 
 the hippocampal gyrus. Its inner margin is free, and rests upon the dentate fascia, 
 from which it is separated by a slit-like fissure, the fimbrio-dentate fissure. The 
 groove between the fimbria and tHe hippocampal convolution is the defile of the 
 dentate fissure. Its outer margin is attenuated and irregular, and forms the line 
 along which the ependyma is reflected over the choroid plexus as the latter is 
 invaginated through the inferior part of the transverse fissure. When the choroid 
 plexus is pulled away it carries the ependyma with it, and the descending horn 
 opens on to the surface of the brain through the transverse fissure. If now 
 the inner border of the corpus fimbriatum be raised, a notched band of gray 
 matter, which is a free border of cortex, and is called the dentate fascia (fascia 
 dentata hippocampi) (Figs. 562 and 581), will be exposed; this has already been 
 described as forming part of the limbic lobe (p. 879). 
 
 ' Journal of Anat. and Phys., 1899, vol. xxiii. 
 
THE HEMISPHERES OF THE CEREBRUM 
 
 899 
 
 The Choroid Plexus {plexus chorioideus) (Figs. 548, 575, and 583) is a highly 
 vascular, fringe-like structure, which is situated partly in the body and partly in 
 the descending cornu of the lateral ventricle, It will be desirable to consider these 
 two portions separately, in order to get a just conception of how they are formed. 
 
 The portion in the body of the ventricle is the vascular, fringed border of a 
 triangular fold of pia mater, the velum interpositum {tela chorioidea superior or tela 
 chorioidea ventriculi tertii), which lies on the under surface of the fornix and forms 
 the roof of the third ventricle. The developing brain vesicles are covered by pia 
 mater. As the prolongation from the first vesicle, which is to form the cerebral 
 hemispheres, increases in size, it grows backward and downward and covers the 
 other vesicles, with the result that the pia mater covering the hemisphere comes in 
 
 Fig. 583. — The fornix, velum interpositum, and middle or descending cornu of the lateral ventricle. 
 
 contact with that covering the upper surface of the second vesicle. Portions of the 
 two layers which are in contact form the velum interpositum. Immediately above is 
 the body of the fornix, which is formed by the fusion of the cerebral hemispheres in 
 the middle line, and below is the cavity of the second vesicle (the third ventricle), 
 with the optic thalamus on either side. Just beyond the free lateral border of the 
 fornix, between it and the taenia semicircularis, is a portion of the first cerebral 
 vesicle, which is not developed into nervous matter, but is made up only of epen- 
 dyma covered by pia mater. The vessels of this portion of the highly vascular pia 
 mater become dilated and prolonged, and grow into the ventricle, pushing the 
 
900 THE NEBVOUS SYSTEM 
 
 ependyma before them, and forming an irregular congeries of vessels, apparendy 
 encroaching on the cavity of the lateral ventricle, but in reality being external to it, 
 because they are separated from it by the lining membrane of the cavity, the 
 ependyma. This vascular structure is the choroid plexus of the body of the ventricle. 
 
 The part of the choroid plexus seen in the descending cornu is formed in 
 exactly the same way — viz., by an ingrowth of the vessels of the pia mater into the 
 cavity, pushing the ependyma before it, at a part of the wall of the horn where 
 there is a similar absence of nervous tissue and where it consists simply of pia 
 mater and ependyma in close contact. This portion lies between the corpus fim- 
 briatum in the floor and the taenia semicircularis in the roof of the descending 
 horn. This area, destitute of nervous matter, is continuous with the area in the 
 body of the ventricle, from which the choroid plexus of this region originated, and 
 in it the vessels of its pia mater increase, and, invaginating the ependyma, appear 
 in the descending horn as its choroid plexus. In the body of the ventricle the 
 choroid plexus is really the vascular fringed margin of the velum ; beyond the pos- 
 terior margin of the velum the plexus of the descending horn is continuous with 
 the pia mater on the surface of the gyrus hippocampi; the two portions of the 
 plexus are, however, directly continuous with each other, and constitute the 
 choroid plexus of the lateral ventricle (plexus chorioideus ventriculi lateralis). The 
 gap or cleft through which the invagination of the pia mater takes place is called 
 the choroid fissure. 
 
 In front the choroid plexus of the lateral ventricle is small and tapering, and 
 communicates with the plexus of the opposite side through the foramen of Monro. 
 In structure it consists of minute and highly vascular villous processes, contain- 
 ing an afferent and efferent vessel, and covered by a single layer of flattened epi- 
 thelium, the cells of which often contain yellowish fat molecules. The anterior 
 choroidal artery is derived from the internal carotid, and enters the ventricle at the 
 extremity of the descending cornu, and, after ramifying in the plexus, sends 
 branches into the adjacent parts of the brain. The posterior choroidal arteries, 
 one or two in number on each side, are derived from the posterior cerebral artery, 
 and reach the plexus by passing forward under the splenium of the corpus cal- 
 losum. The veins of the choroid plexus unite to form a prominent vein, the choroid 
 vein, which courses from behind forward to the foramen of ]\Ionro. On each 
 side of the foramen of Monro a deep cerebral vein or vein of Galen is formed by 
 the union of the choroid vein and the vein of the corpus striatum. The veins of 
 Galen pass back in the velum interpositum, unite to form the common vein of 
 Galen or the vena magna Galeni (v. cerebri magna), which empties into the straight 
 sinus (p. 735). 
 
 The Transverse Fissure or Fissure of Bichat (fissura cerebri transversa) , separates 
 the cerebrum from the cerebellum. This fissure passes forward and ends in the 
 cerebrum as the lateral part of the transverse fissure or the choroid fissure (fissura 
 chorioidea). The posterior part of the transverse fissure is occupied by the 
 tentorium. Posteriorly the transverse fissure has above it the mass of the 
 cerebral hemisphere and below it the upper surface of the cerebellum, the cor- 
 pora quadrigemina, and the pineal gland. The transverse fissure is a complete 
 fissure, but it is filled by the invagination of the pia mater, forming laterally 
 the velum interpositum and the choroid plexuses, which invagination is covered 
 by the fining of the ventricular cavities. If this involution of pia mater is pulled 
 out, the ventricular lining will necessarily be torn away with it, and a cleft-like 
 space will be left on either side, extending from the foramen of Monro to the 
 bottom of the descending horn of the lateral ventricle. The upper part of the 
 cleft, that is to say, the part nearest the foramen of Monro, is between the lateral 
 border of the body of the fornix and the optic thalamus; below this, at the com- 
 mencement of the middle horn, it is between the commencing corpus fimbriatum 
 
THE INTEB-BBAIN 901 
 
 of the fornix and the pulvinar of the optic thalamus; and lower still, in the 
 descending horn, between the corpus fimbriatum on the floor and the taenia 
 semicircularis in the roof of the cornu. The course of the choroid fissure from 
 the foramen of Monro is backward, downward, and forward, to near the apex 
 of the temporal lobe. The choroid fissures of the two sides are continuous 
 between the fornix and the roof of the third ventricle. 
 
 The Velum Interpositum^or Tela Chorio idea Superior (te/a c^onoitim -yenincM/i 
 tertii) (Fig. 548) is a vascular membrane, and is a prolongation of the pia mater 
 into the interior of the brain through the middle part of the transverse fissure. 
 It is of a triangular form, and separates the under surface of the body and pos- 
 terior pillars of the fornix from the cavity of the third ventricle. Laterally it covers 
 the inner part of the upper surface of the optic thalamus. Its posterior border or 
 base lies beneath the splenium of the corpus callosum above, and the optic thala- 
 mus, the corpora quadrigemina, and pineal body below. The upper layer of the 
 base is continuous with the pia mater of the occipital lobe, and the lower layer of 
 the base is continuous with the pia mater of the dorsal aspect of the cerebellum 
 and mid-brain. Its anterior extremity or a'pex ends just behind the anterior com- 
 missure, where it receives the anterior extremities of the choroid plexuses, which 
 are here vmited through the foramen of Monro, and are then prolonged back- 
 ward on the under surface of the velum as the choroid plexus of the third 
 ventricle (plexus chorioideus ventriculi tertii). The inferior layer of the velum which 
 carries the choroid plexus of the third ventricle is called the superior choroid tela 
 (tela chorioidea ventriculi tertii). The external portion of the inferior layer of the 
 velum interpositum covers the inner half of the superior surface of the optic 
 thalamus. In front the plexuses of the third ventricle lie close to the middle line, 
 but diverge from each other behind. Each lateral margin of the velum inter- 
 ])ositum constitutes the choroid plexus of the corresponding lateral ventricle. It 
 is supplied by the anterior and posterior choroidal arteries, already described. 
 The veins of the velum interpositum, the venae Galeni (vv. cerebri internae), two 
 in number, riin between its layers, each being formed by the union of the vein 
 of the corpus striatum (v. corporis striata) with the choroid vein (v. chorioidea). The 
 venae Galeni unite posteriorly into a single trunk, the vena magna Galeni or the 
 common vein of Galen (v. cerebri magna), which terminates in the straight sinus 
 (Fig. 548). The portion of the pia mater prolonged over the lower half of the 
 fourth ventricle is known as the tela chorioidea inferior quarti. It carries the 
 choroid plexus of the fourth ventricle (plexus chorioideus ventriculi quarti.) 
 
 II. The Inter-brain (Thalamencephalon). 
 
 The inter-brain is the region of the third ventricle, and comprises the parts 
 developed from the second cerebral vesicle, together with parts from that portion of 
 the first vesicle which is not concerned in the formation of the cerebral hemispheres. 
 
 The inter-brain is connected above and in front with the cerebral hemispheres; 
 behind, with the raid-brain or mesencephalon. On its upper surface it is entirely 
 concealed from view, as it is covered by those portions of the internal surfaces of 
 the cerebral hemispheres which have fused together to form the corpus callosum 
 and the fornix, and is separated from the latter by the two layers of pia mater 
 which form the velum interpositum. Inferiorly it reaches the base of the brain, 
 forming the structures contained in the interpeduncular space. 
 
 The Third Ventricle (ventriculus tertius) (Fig. 584). — The third ventricle is 
 the cavity of the inter-brain; it is in the mid-line, is at a lower level than the lateral 
 ventricles; and the epithelial layer of the ependyma from the lateral ventricles 
 is prolonged into the third ventricle through the foramen of Monro. The third ven- 
 
902 
 
 THE NERVOUS SYSTEM 
 
 tricle contains cerebro-spinal fluid. It is a narrow median crevice between the two 
 optic thalami, which constitute the side walls of the inter-brain. It is "about an 
 inch in length from before backward and one-quarter of an inch broad at its 
 widest part."^ Its roof is formed by the velum interpositum, from which is sus- 
 pended the choroid plexus of the third ventricle. Its floor, somewhat oblique in 
 its direction, is formed, from before backward, by the tuber cinereum, with its 
 infundibulum and pituitary body; the corpora albicaijtia; the posterior perforated 
 space; and the tegmenta of the crura cerebri. Its sides are formed by the optic 
 thalami, and are limited above by a delicate band of white fibres, the pineal stria 
 {stria medullaris thalami), which runs along the junction of the mesial and upper 
 
 Fio. 684. — ^The third and fourth ventricles. An arrow has been placed in the position of the foramen of Monro. 
 
 surfaces of the optic thalamus to join the anterior pillars of the fornix. Its sides 
 are somewhat convex, so that in the middle of the ventricle the two lateral walls 
 are almost in contact, and are here united across the middle line by a band of gray 
 nervous matter, the middle, gray, or soft commissure (Fig. 584). The ventricle is 
 bounded in front by the anterior pillars of the fornix and the lamina cinerea; behind 
 by the pineal gland, the posterior commissure, and the upper end of the aqueduct 
 of Sylvius, the iter a tertio ad quartum ventriculum. The cavity is much deeper in 
 front than behind, and presents a recess at its anterior part, which lies over the optic 
 commissure and is, therefore, termed the optic recess (recessus opticus). Behind 
 and below this is the conical depression of the infundibulum (Fig. 587), passing 
 
 ' Anatomy of the Brain and Spinal Cord. By Harris E. Santee. 
 
THE INTER-BBAIN 903 
 
 downward and forward to the pituitary body. At its posterior extremity the 
 cavity forms another and smaller recess, which extends into the stalk of the 
 pineal gland, and is termed the pineal recess (recessus pinealis). The anterior 
 part of the third ventricle is called the aula. At the upper and anterior part of 
 the third ventricle, immediately behind the anterior pillars of the fornix and in 
 front of the optic thalamus, is an opening, the foramen of Monro {foramen inter- 
 ventriculare [Monroi\), by which this ventricle communicates with the lateral 
 ventricle on either side (Figs. 548, 574, 575, and 587). The foramen of Monro 
 opens into each lateral ventricle at the point of junction of the anterior horn and 
 the body of the ventricle. It lies between the anterior pillar of the fornix and the 
 anterior margin of the optic thalamus and ends by opening into the anterior and 
 superior extremity of the third ventricle. Running back from the foramen of 
 Monro toward the aqueduct of Sylvius is a furrow called the sulcus of Monro 
 (sulcus hypothalamicus [Monroi]). At the posterior part of the floor of the third 
 ventricle, beneath the posterior commissure, is the opening of the aqueduct of 
 Sylvius or iter a tertio ad quartum ventriculum (Fig. 587) , the channel which joins 
 the third and fourth ventricles (p. 912). The roof of the cavity of the third ventricle 
 is limited in front and behind by transverse bands of white matter, known 
 respectively as the anterior and posterior commissures. The former has already 
 been described in connection with the corpus striatum (p. 896). 
 
 The Middle, Gray, or Soft Commissure (massa intermedia or commissura mollis) 
 (Fig. 584). — The middle, gray, or soft commissure consists almost entirely of 
 gray matter. It connects the two optic thalami, and is continuous with the 
 gray matter lining the anterior part of the third ventricle. It is frequently 
 broken in examining the brain, and might then be supposed to be wanting; it is 
 sometimes double. 
 
 The Posterior Commissure (commissura posterior) (Figs. 584 and 587. — The poste- 
 rior commissure is a rounded band of white fibres, which stretches across from one 
 optic thalamus to the other, overlying the upper end of the aqueduct of Sylvius. 
 It is usually described as belonging to the inter-brain, but would appear to 
 belong in part to the mid-brain, since some of its fibres are commissural and 
 connect the anterior corpora quadrigemina to the fillet of the opposite side (see 
 below). In addition there are other decussating fibres, which come from the 
 tegmentum of the crus cerebri on one side and decussate with those of the 
 opposite side in the posterior commissure, and passing through the optic 
 thalamus reach the cerebral hemispheres. Fibres have also been described as 
 taking their origin in the pineal body and ganglion habenulae, and passing across 
 to the posterior longitudinal bundle and oculomotor nucleus of the opposite side; 
 these fibres occupy the ventral part of the commissure, and receive their myelin 
 sheath before those in its dorsal part. But to a certain extent the posterior com- 
 missure belongs to the inter-brain, since it contains fibres which serve as com- 
 missural fibres between the two optic thalami. 
 
 The Optic Thalamus (thalamus) (Figs. 576,577, 578, 579, 580, 582, and 584). 
 — ^The optic thalami are two large oblong masses, situated on either side of the third 
 ventricle, and lying between the diverging portions of the corpora striata. They are 
 composed mainly of gray matter, but the free surface of each is coated with a thin 
 layer of white nervous tissue, the stratum zonale. They present outer and under 
 surfaces, which are not free, but are blended with contiguous parts of the brain, 
 and upper, inner, and posterior surfaces, which are free. The anterior extremity 
 is narrow, and forms the posterior boundary of the foramen of Monro. The outer 
 surface is in contact with the posterior limb of the internal capsule, which sepa- 
 rates it from the lenticular nuclues. The inferior surface rests upon and is con- 
 tinuous with the tegmentum of the crus cerebri. Its upper surface is free, and 
 is separated from the caudate nucleus by a furrow which lodges the vein of the 
 
904 THE NERVOUS SYSTEM 
 
 corpus striatum, and the taenia semicircularis. It is divided into an outer and an 
 inner part by a groove which runs from behind, forward, and inward. The outer 
 part forms a portion of the floor of the lateral ventricle, and is covered by the 
 ependyma of that cavity; it terminates in front in a tubercle, the anterior tubercle 
 of the optic thalamus (tuberculum anterius thalami). The inner part is covered by 
 the velum interpositum, which separates it from the fornix, and is excluded from 
 both the lateral and third ventricles by the reflection of the lining of these cavities, 
 and is therefore destitute of an ependymal covering. 
 
 The internal surface forms the lateral wall of the third ventricle, and running 
 along its upper border is the peduncle of the pineal gland, from which the ependyma 
 of the third ventricle is reflected on to the under surface of the velum interpositum. 
 The shelf-like edge of the ependyma separates the superior from the internal 
 surface of the thalamus. The edge is called the taenia thalami, and close to it is a 
 narrowband of longitudinal fibres called the pineal striae (striae medullaris thalami). 
 The taenia thalami and the pineal striae pass backward and then inward into the 
 stalk of the pineal gland. The portion of the taenia which turns inward has pos- 
 terior to it a small triangular depression called the trigone of the habenula {trigonum 
 hahenulae). This depression is just in front of the superior quadrigeminal body. 
 Passing in a medial direction from the trigonum habenulae is a collection of 
 white fibres, the habenula. The fibres of the anterior portion of this band are 
 continuous with those of the opposite side, and constitute the commissure of the 
 habenula (commmwra hahenularmn). The fibres of the posterior portion consti- 
 tute the peduncle of the pineal gland (p. 906). The posterior surface projects 
 beyond the level of the corpora quadrigemina, and forms a well-marked rounded 
 prominence, the posterior tubercle or pulvinar. The pulvinar is continued exter- 
 nally into a second eminence, the external geniculate body {corpus geniculatum 
 laterale), which is placed above and to the outer side of the internal geniculate body 
 (corpus geniculatum mediale), and from which it is separated by the superior 
 brachiimi, one of the roots of the optic tract. 
 
 The optic or free upper surface of the thalamus is covered by white fibres derived, 
 in part, at least, from the optic tract and radiation. The thalamus is formed chiefly 
 of gray matter, which is arranged in three masses partially separated from each 
 other by white matter called the internal medullary lamina (lamina medullaris 
 interna), which is named internal in contradistinction to a second or external 
 medullary lamina (lamina medullaris externa), which coats the outer surface of the 
 thalamus and lies between it and the internal capsule. These masses of gray 
 matter are the nuclei of the optic thalamus. Twenty nuclei have been described 
 (Nissl). The chief nuclei are the following: 
 
 1. The External or Lateral Nucleus (nucleus lateralis thalami). — The external or 
 lateral nucleus, the largest of the nuclei, between the external and internal medul- 
 lary laminae and extending the entire length of the thalamus, including, as Prof. 
 Cunningham points out, the entire pulvinar, most of the tegmental fibres, and one- 
 fifth of the optic fibres, terminate in this nucleus, and from it originate the fibres 
 of the thalamic radiation. 
 
 2. The Middle or Internal Nucleus (nucleus medialis thalami). — The middle or 
 internal nucleus is separated by the internal medullary lamina from the other gray 
 nuclei of the same side. It joins the middle nucleus of the opposite thalamus by 
 means of the middle commissure. 
 
 3. The Anterior Nucleus (nucleus anterior thalami). — The anterior nucleus is in 
 the anterior tubercle, and in it terminate the fibres of the bundle of Vicq d'Azyr 
 which come from the corpus mamillare (Fig. 586). 
 
 In the substance of the thalamus are two other distinct nuclei, (4) the central 
 nucleus of Luys and (5) the nucleus arcuatus. The nucleus or ganglion of the habenula 
 lies in the trigonum habenulae. 
 
THE INTER- BBAIN 905 
 
 Connections of the Optic Thalamus (Figs. 586, 589, and 590). — The optic thalamus 
 is a ganglion interposed between the sensory tracts in the tegmentum and the cere- 
 bral cortex, being connected also with the optic tract. In this ganglion or in the 
 adjacent ganglia of the subthalamic region, " almost every impulse of general sen- 
 sation, on its journey to the cerebral cortex, is transferred to a higher neurone."^ 
 The crusta of the crus cerebri is external to the optic thalamus and passes into 
 the internal capsule. The tegmental fibres of the crus (Fig. 586) pass to the under 
 surface of the thalamus, and the forward prolongation of the tegmentum which 
 becomes continuous with the under surface of the thalamus is called the sub- 
 thalamic region, and most of the longitudinal fibres enter this ganglion, some of 
 them terminating in it, some of them traversing it and entering the internal 
 capsule. The internal capsule (Figs. 578, 589, and 590) is composed of fibres going 
 to and coming from the cerebral cortex. Most of these fibres are descending and 
 form the crus cerebri. From all over the external surface of the optic thalamus 
 fibres emerge, pass into the internal capsule, and from there go to the cerebral 
 cortex. These fibres constitute the thalamic radiation. 
 
 The nuclei of the thalamus have been described (p. 904). The white matter 
 receives the fibres of the tegmentum and fillet, the majority of which enter the 
 lateral nucleus; it receives fibres (axones) from the entire cerebral cortex and 
 sends fibres to the cortical special sense areas of sight, hearing, and smell and 
 to the area of general sensation) the somaesthetic area). 
 
 The following groups of fibres of white matter are found in the thalamus: 1. 
 The anterior pillar of the fornix, which passes through the inner part of the optic 
 thalamus on its way to the corpus mamillare, and the bundle of Vicq d'Azyr, 
 (fasciculus thalavwmamillaris) (Fig. 586), which arises in the corpus mamil- 
 lare and ascends to the anterior gray nucleus. 2. Two bundles of fibres emerging 
 from the external surface of the. thalamus. The superior bundle {ansa lenticu- 
 laris) arises largely in the lateral nucleus, passes through the internal capsule and 
 the lenticular nucleus; it then enters the external capsule, and passes to the 
 insula, the paracentral lobule, the superior frontal convolution, and "the entire 
 limbic lobe "^ (Fig. 589). The inferior bundle (ansa peduncularis) arises in the 
 lateral nucleus, passes through the internal capsule below the lenticular nucleus, 
 "enters into both the medullary laminae of that nucleus and the external capsule. 
 It ends chiefly in the cortex of the ascending frontal and ascending parietal 
 convolutions"^ (Fig. 589). These fibres constitute the ventral or inferior stalk 
 of the thalamic radiation. 8. The anterior stalk of the thalamic radiation (Figs. 588 
 and 500) arises in the lateral nucleus, passes to the frontal portion of the 
 internal capsule, and reaches the inferior and middle frontal convolutions, 
 the anterior portion of the superior frontal convolution, and the middle of the 
 gyrus fornicatus (Santee), The anterior stalk of the thalamic radiation, plus 
 the ansa lenticularis and the ansa peduncularis, constitutes the cortical fillet or 
 the three systems of Flechsig (p. 915). 4. The posterior stalk of the thalamic 
 radiation (Fig. 590) is called the optic radiation (radiatio occipitothalamica). 
 The afferent part arises in the pulvinar and the external geniculate body, passes 
 through the internal capsule, and terminates in the occipital cortex. The 
 efferent portion terminates in the superior quadrigeminal body. 5. The acoustic 
 radiation (Fig. 590) arises about the internal geniculate body, passes through the 
 internal capsule, and reaches the auditory region in the temporal cortex. 
 
 The Pineal Body, Epiphysis Cerebri, Conarium, or Pineal Gland (corpus 
 pineale) (Figs. 584 and 587). — The pineal body or gland, so named from 
 its peculiar shape (pinus, a fir-cone), is a small reddish-gray body, conical in 
 shape (hence its synonym, conarium), placed immediately above and behind the 
 
 ^ Anatomy of the Brain and Spinal Cord. By Harris E. Santee. - Ibid. • Il)id. 
 
906 THE NERVOUS SYSTEM 
 
 posterior commissure and between the anterior corpora quadrigemina, on which 
 it rests. It is covered by the velum interpositum, which intervenes between it 
 and the splenium of the corpus callosum. It is an upgrowth from the second 
 cerebral vesicle (hence the name epiphysis), and is at first hollow, but soon 
 becomes solid and loses its connection with the ventricular cavity. It is 
 retained in its position by a duplicature of pia mater, derived from the under 
 surface of the velum interpositum, which almost completely invests it. The 
 pineal gland is about four lines in length and from two to three in width at 
 its base, and is said to be larger in the child than in the adult, and in the 
 female than in the male. It is attached on either side by a flattened stalk 
 or peduncle of white matter, the pedunculus conaxii (habenula). This stalk 
 consists of two laminae, upper and lower, separated by a little recess, the 
 pineal recess (recessus pinealis). The lower lamina is prolonged into the pos- 
 terior commissure. The upper divides into two strands, the peduncles of the 
 pineal gland (striae pinealis) ; these extend on either side along the optic thalamus 
 at the junction of its mesial and upper surfaces to the anterior pillars of the 
 fornix, with which they blend. The two stalks join together at their posterior 
 extremity, in front of the pineal gland, forming a sort of festoon, and the base of 
 the gland is connected to their posterior margin at the point of junction. 
 
 Structure. — ^The pineal gland consists of a number of follicles, lined by epithe- 
 lium, and connected together by ingrowths of connective tissue. The follicles con- 
 tain a transparent viscid fluid and a quantity of sabulous matter named brain sand 
 (acervulus cerebri), composed of phosphate and carbonate of lime, phosphate of 
 magnesia and ammonia, with a little animal matter. These concretions are almost 
 constant in their existence, and are present at all periods of life. They are found 
 upon the surface of the pineal body and occasionally upon its peduncles. 
 
 Morphologically the pineal gland is regarded as the homologue of the structure 
 termed the pineal eye of the lizards. In these reptiles the epiphysis cerebri is 
 attached by an elongated stalk and projects through the parietal foramen. Its 
 extremity lies immediately under the epidermis, and on microscopic examination 
 presents, in a rudimentary fashion, structures similar to those found in the eyeball. 
 
 III. The Mid-brain (Mesencephalon) (Figs. 557, 584, 585, 587). 
 
 The mid-brain is the short and constricted portion of the brain which lies in 
 the opening of the tentorium cerebelli (incisura tentorii) and which connects the 
 pons Varolii with the inter-brain and hemispheres, and hence it is frequently 
 called the isthmus cerebri (isthmus rhombencephali) . It is developed from the 
 third cerebral vesicle, the cavity of which becomes the aqueduct of Sylvius. 
 It comprises the crura cerebri, the corpora quadrigemina, the geniculate bodies, 
 and the Sylvian aqueduct. Its direction is from before backward and down- 
 ward. In front and above it is continuous with the inter-brain; below with 
 the pons. Its two surfaces are ventral and dorsal. They are free, but concealed: 
 the ventral surface by the apices of the temporal lobes which overlap it; the dorsal, 
 by the overhanging cerebral hemispheres. The ventral surface, when exposed by 
 drawing aside the temporal lobes, is seen to consist of two cylindrical bundles of 
 white matter which emerge from the pons and diverge as they pass forward and out- 
 ward to enter the inner and under part of either hemisphere. They are the cerebral 
 peduncles (crura cerebri), and between them is a triangular area, already described 
 as part of the interpeduncular space (fossa inter peduncularis) (see pp. 884 and 885) ; 
 near the point of divergence of the crura the roots of the third nerve are seen to 
 emerge in several bundles from a groove, the sulcus oculomotorius (sulcus nervi 
 oculomotorii) (Fig. 570) . The dorsal surface (Fig. 584) is not visible until a con- 
 siderable portion of the cerebral hemispheres and other overlying structures have 
 
 I 
 
THE MIDBRAIN 
 
 907 
 
 C. Quadrigemina. 
 Aqueduct. 
 
 Interpeduncular space. 
 
 Fig. 585. — Transverse section of the 
 mid-brain. 
 
 been removed. It then presents four rounded eminences placed in pairs, two in 
 front and two behind, and separated from one another by crucial depression. 
 These are termed the corpora quadrigemina (tubercula quadrigemina) (Figs. 584 and 
 585). The ventral and dorsal surfaces meet on the side of the mid-brain, and 
 are separated from each other by a furrow, the lateral groove (sulcus lateralis 
 mesencephali) , which runs from below upward and forward (Fig. 585). 
 
 If a cross-section be made through the mesencephalon (Fig. 585), it will be seen 
 that each lateral half is divided into two unequal portions by a lamina of deeply 
 pigmented gray matter, named the substantia nigra. The postero-superior portion 
 of the crus is named the tegmentum, and the antero-inferior the crusta or pes. The 
 substantia nigra is curved on section with its concavity upward, and extends from 
 the lateral groove externally to the oculomotor 
 sulcus internally. The two crustae are in con- 
 tact in front of the pons, from which point they 
 diverge from one another, but the two halves of 
 the tegmentum are joined to each other in the 
 mesial plane by a prolongation forward of the 
 raphe or median septum of the pons. Laterally' 
 the tegmenta are free, but dorsally they blend 
 with the corpora quadrigemina. 
 
 Crusta or Pes (basis pedunculi) (Fig. 585) . — 
 The crusta is known as the pes of the crus 
 cerebri. The crustae are two in number, are 
 semilunar on section, and are separated by the 
 interpeduncular space (Fig. 570) . From the front 
 
 of the pons each crusta passes upward, forward, and outward, enters the cerebrum 
 to the outer side of the thalamus, and its fibres enter and spread out in the internal 
 capsule (Figs. 589 and 590) . The great bulk of the fibres are limited to the superior 
 lamina of the capsule. The deep portion of the crusta contains the intermediate 
 bundle or tract (Fig. 590), the fibres of which rise in the corpus striatum and 
 terminate in motor cranial nuclei and the nucleus pontis, and from this nucleus 
 fibres pass by way of the middle peduncle of the cerebellum to the cortex of the 
 opposite cerebellar hemisphere. 
 
 The superficial portion of the crusta contains three sets of fibres (Figs. 589 
 and 590): 1. The outer one-fifth is composed, according to Dejerine, of fibres 
 which take origin in the cortex of the superior, middle, and inferior temporal 
 convolutions, the cerebro-cortico-pontal tract (tractus cerebrocorticopontalis tem- 
 poralis). They pass through the inferior lamina of the internal capsule and 
 through a portion of the superior lamina, and mostly terminate in the nucleus 
 pontis. Some few of these fibres terminate in the motor nuclei of the cranial 
 nerves.^ 2. The middle three-fifths, which is largely composed of motor fibres, 
 is known as the pyramidal tract (fasciculus longitudinalis pyramidalis). These 
 fibres take origin in the cells of the Rolandic area of the cortex, converge to 
 the internal capsule, and pass down through its genu and through the ante- 
 rior two-thirds of its posterior limb to the crusta, from which they are pro- 
 longed as longitudinal fibres through the ventral portion of the pons and as 
 the pyramid through the medulla. Below the medulla they pass into the direct 
 and crossed pyramidal tracts of the spinal cord. The median portion of the 
 pyramidal tract occupies the genu of the internal capsule and passes to the 
 muscles of the face and the muscles of speech. The fibres which pass to the arm 
 muscles, in the crusta, are posterior and external to the fibres which go to the face. 
 Behind and external to the arm fibres are the fibres to the muscles of the trunk 
 
 ' Spitzka; Santee. 
 
908 THE NERVOUS SYSTEM 
 
 and leg. A few fibres from the cerebellum are placed among the pyramidal fibres. 
 These fibres reached the pons by way of the middle cerebellar peduncle, ascend 
 from the pons with the longitudinal fibres, and reach the crusta. 3. The inner 
 one-fifth of the crusta is formed by the fibres of the median fillet {lemniscus 
 medialis) and motor fibres coming from the cortex in front of the Rolandic fissure 
 (from the prefrontal lobe). This tract from the prefrontal lobe descends through 
 the anterior limb of the internal capsule and through the crusta and reaches the 
 nucleus pontis, from which point it is connected by fibres with the cerebellar 
 hemisphere of the opposite side. It is called the frontal cerebro-cortico-pontal tract 
 (tractus cerebrocorticopontalis frontalis). The median fillet is composed of central 
 sensory fibres from the spinal nerves and all the cranial nerves, except the 
 cochlear branch of the auditory (Santee). It arises from the fillet, and at the 
 lower part of the crusta is situated at the mesial border. As it ascends it courses 
 obliquely outward to meet the lateral border of the pyramidal tract. It enters 
 the sub-thalamic region, and ends in the lateral nucleus of the optic thalamus. 
 Some of the fibres of this tract reach the cortex by joining the ansa peduncularis 
 and the ansa lenticularis. 
 
 The Tegmentum (Fig. 585). — The tegmentum (the cover) is that portion of the 
 mid-brain which is superior to the substantia nigra and covers the two crustae 
 and the substantia nigra. Its ventral surface is placed within the concave sur- 
 face of the substantia nigra. The internal geniculate bodies and the corpora 
 quadrigemina are upon its dorsal surface. The anterior extremity of the 
 tegmentum enters the optic thalami, and the posterior extremity is continued 
 into the pons. The tegmentum contains the aqueduct of Sylvius (p. 912 and 
 Figs. 585 and 587). 
 
 Fibres of the Tegmentum (Fig. 590). — The pontine formatio reticularis, the gray 
 matter of the floor of the fourth ventricle, and the longitudinal fibres of the dorsal 
 portion of the pons are continued and compose the tegmentum, which structure 
 has upon its dorsal aspect the geniculate and quadrigeminal ganglia. Each half 
 of the tegmentum consists of strands of longitudinal white fibres separated from 
 each other by transversely arched fibres. There is also a considerable quantity of 
 gray matter. The peculiarly reticulated structure formed by the gray and white 
 matter is named the formatio reticularis, and is similar to the structure met with in 
 the pons and medulla, with which it is continuous. 
 
 The Red Nucleus of the Tegmentum (nucleus tegmenti) (Fig. 589) . — ^The red nucleus 
 of the tegmentum is a tract of gray matter situated partly in the tegmentum and 
 partly in the subthalamic tegmental region on either side of the middle line. It is 
 composed of numerous large cells which are deeply pigmented. It is pierced by 
 the fibres of the third nerve. The red nucleus sends fibres to the corpus dentatum 
 by means of the opposite superior peduncles of the cerebellum, and also gives 
 off the crossed descending tract. The nucleus of Luys (nucleus hypothalamicus) 
 is above and external to the red nucleus and between it and the crusta. It 
 receives fibres from the median fillet and from the corpus striatum, and is con- 
 nected by fibres to the lamina cinerea and tuber cinereum, which are known as 
 the commissure of Meynert (Santee). 
 
 The longitudinal fibres in some parts of the tegmentum are arranged in six 
 fairly well-defined tracts, which are described as follows by Harris E. Santee in 
 the Anatomy of the Brain and Spinal Cord: 
 
 1. The Posterior Longitudinal Bundle (fasciculus longitudinalis medialis) (Fig. 
 586) is in large part an associated tract. It lies by the side of the raphe just below 
 the aqueduct. These fibres ascend from the gray substance of the anterior cornu 
 of the spinal cord. In the anterior column of the cord they probably form short 
 longitudinal commissures between different segments of the cord. They ascend 
 through the pyramid of the medulla, form the posterior longitudinal bundle of the 
 
THE MID BRAIN 
 
 909 
 
 pons, and enter the tegmentum. The posterior longitudinal bundle, while travers- 
 ing the pons, receives fibres from the cerebellum, and in the pons and medulla 
 receives fibres from the sensory nuclei of cranial nerves. "It carries motor fibres 
 from the sixth to the third nerve; also descending motor fibres from the nucleus 
 of the motor oculi to the genu of the seventh or facial nerve." Soon after entering 
 the tegmentum the posterior longitudinal bundle decussates across the raph€ with 
 the bundle of the opposite side. This constitutes the lower decussation, and the 
 decussated fibres pass to the nuclei of the third, fourth, and other cranial nerves. 
 The undecussated fibres ascend, and in the posterior commissure decussate. This 
 is known as the upper decussation, and the fibres enter "the pineal body and 
 stratum dorsale of the hypothalamic region." 
 
 Fig. 586.— The short tracts in the brain-stem and inter-brain. Sagittal section through the middle of the 
 brain-.st em : mf, infundibulum; c. mam, corpus mamillare; jasc. Vic, bundles of Vicq d'Azyr; /. teg, tegmental 
 bundle; perf. m, peduncle of corpus mamillare; /asc. rt, fasciculus retroflexus; jasc. I. in/, posterior longitudinal 
 bundle; II, III, VI, XII. corresponding cranial nerves; c, pineal gland. (Jakob.) 
 
 2. The Anterior Longitudinal Bundle is composed of fibres which pass from the 
 superior quadrigeminal body to the ciliary centre (dilator fibres of the pupil) and 
 other centres in the spinal cord. 
 
 3. The Fillet or Lemniscus is "a segment in the direct sensory tract. It 
 carries spinal and cranial impulses to the corpora quadrigemina and optic 
 thalamus." It takes its chief origin from the medulla, and passes through the 
 formatio reticularis of the pons to the ventral portion of the tegmentum, where it 
 divides into two portions, the interolivary fillet and the lateral fillet. 
 
 The interolivary fillet (lemniscus interolivaris) arises from the opposite side of 
 the medulla oblongata (from the nucleus gracilis and nucleus cuneatus), decus- 
 sates with the sensory fibres, and terminates in the lateral nucleus of the thalamus. 
 A bundle of fibres come off from the interolivary fillet soon after its origin and 
 
910 THE NERVOUS SYSTEM 
 
 passes to the superior quadrigeminal bodies. This bundle is the upper or superior 
 fillet {lemniscus superior). The interoHvary bundle after giving off the superior 
 fillet is known as the median or mesial fillet (lemniscus medialis or mesiqjtis). It 
 ascends, turns toward the ventral surface of the tegmentum, passes through the 
 substantia nigra, and along the inner one-fifth of the crusta to the thalamus, and 
 from the thalamus connection with the cortex is established by the ansa lenticularis 
 and the ansa peduncularis. 
 
 The lower or lateral fillet {lemniscus lateralis) arises almost entirely from the 
 cochlear nuclei, and mostly from the opposite nucleus. It is situated in the ventral 
 part of the tegmentum, through which it passes obliquely and emerges at its side, 
 and after crossing the superior peduncle of the cerebellum, passes to the inferior 
 quadrigeminal bodies. It is reinforced by some fibres from the superior medullary 
 velum. It is a path in the conduction of auditory impressions. These impressions 
 pass from the auditory nerve to the lateral fillet, from this to the inferior brachium, 
 and then to the cortex by the acoustic radiation (Fig. 590). 
 
 4. The Superior Peduncle of the Cerebellum (brachium conjunctivum) (Figs. 590 
 and 599) ascends from the dorsal surface of the pons. It is connected to its fellow 
 peduncle by a band of white matter called the valve of Vieussens {velum medullare 
 anterius) (Fig. 584). The fibres of the superior peduncles of the cerebellum pass 
 beneath the quadrigeminal bodies, and to a large extent decussate across the raphd 
 and below the Sylvian aqueduct. It is thus evident that the fibres from one-half 
 of the cerebellum pass largely to the opposite half of the cerebrum. The numerous 
 crossed and the few uncrossed fibres pass forward, enclosing the red nucleus (in 
 which structure many of the fibres terminate and from which structure it obtains 
 some fibres), and passes to the "stratum dorsale of the hypothalamic region." 
 
 5. The Olivary Fasciculus (fasciculus tegmenti centralis) (Fig. 589) arises from 
 the inferior olivary nucleus of the medulla, ascends through the medulla and 
 pons to the tegmentum, passes through the decussation of the superior peduncles 
 of the cerebellum, and ascends to the outer side of the posterior longitudinal 
 bundle of tegmental fibres, to end in the lenticular nucleus. 
 
 6. The Crossed Descending Tract arises in the red nucleus (Fig. 589) , decussates 
 with the opposite tract, enters the lateral fillet, reaches the medulla, where it 
 "mingles with the antero-lateral ascending cerebellar tract," and passes into the 
 pyramidal tract of the cord, to end in "the lateral horn and centre of the gray 
 crescent. " The nucleus of Luys (Fig. 589) is the anterior termination of the 
 substantia nigra. 
 
 The Substantia Nigra (Figs. 585 and 589).— This, as already stated, constitutes 
 the central portion of the mid-brain. It is a layer of deeply pigmented gray matter, 
 which separates the crusta below from the tegm.entum above. It can be seen at 
 the base of the brain between the crustae. In this region it is known as the posterior 
 perforated lamina (substantia perforata posterior) (Fig. 570) . In each lateral sulcus 
 the edge of the substantia nigra reaches the surface (Fig. 585) . The substantia 
 nigra extends from the pons behind to the corpora albicantia and nucleus of Luys 
 in front. It is thicker internally than externally, where it is partially divided up 
 by the mesial fillet passing from the tegmentum to the crusta. It is traversed 
 at its inner part by some of the fibres of origin of the third cranial nerve, which 
 emerge from the motor oculi groove. The cells are small and multipolar, and are 
 characterized by containing a large amount of dark pigment granules. 
 
 The Interpeduncular Ganglion (ganglion interpedunculare) is just in front of the 
 pons in the median line. Some fibres (the fasciculus retroflexus) (Fig. 586) join 
 this ganglion to the nucleus habenulae of the thalamus (Forel, Santee). In 
 each half of the substantia nigra, laterally and anteriorly, is a nucleus known as 
 the nucleus of Luys (nucleus hypothalamicus) (Fig. 589). The zona incerta sepa- 
 rates the nucleus of Luys from the red nucleus of the tegmentum. 
 
THE MID~BBAIN 911 
 
 The Corpora or Tubercula Quadrigemina (Figs. 574, 584, 585, 586, and 587). — 
 The corpora or tubercula quadrigemina are four rounded eminences placed in pairs, 
 two in front and two behind, and separated from one another by the crucial groove 
 or depression. They are situated on the dorsal surface of the mid-brain, imme- 
 diately behind the third ventricle and posterior commissure, and beneath the 
 splenium of the corpus callosum. The anterior or upper pair (colliculi superiores), 
 called the nates, are the larger. They are oval, their long diameter being directed 
 forward and outward, and are of a gray color. The posterior or lower pair (col- 
 liculi injeriores), called the testes, are hemispherical in form, and lighter in color 
 than the preceding. From the outer side of each of these eminences a prominent 
 white band, termed the brachium, is continued forward and outward. The band 
 from the nates [brachium quadrigeminum super ius) passes obliquely outward 
 between the pulvinar and the inner. geniculate bodies into the external geniculate 
 body. The band from the testes {brachium quadrigeminum inferius) loses itself 
 beneath an oval prominence on the side of the quadrigeminal body. This promi- 
 nence is calledthe internal geniculate body. The corpora quadrigemina are larger in 
 the lower animals than in man. In fishes, reptiles, and birds they are hollow, and 
 only two in number (corpora bigemina) ; they represent the anterior quadrigeminals 
 of mammals. In these lower animals the corpora bigemina are frequently termed 
 the optic lobes, because of their connection with the optic tracts. In the mammalia 
 the corpora are four in number, and solid. In the human foetus all four bodies 
 are differentiated by the fifth month, and form at this time a considerable propor- 
 tion of the brain. In man the anterior quadrigeminal bodies are sometimes called 
 the optic lobes and the posterior bodies the auditory lobes. 
 
 Structure, — The corpora quadrigemina are composed of white matter externally, 
 and gray matter within. The posterior pair consist almost entirely of gray matter, 
 covered over by a very thin stratum of white substance. Beneath the gray matter 
 is a thin layer of white fibres, forming a part of the lower fillet. This separates 
 the gray matter of the posterior corpora quadrigemina from the central gray 
 matter of the aqueduct. The anterior pair are covered superficially by a thin 
 stratum of white matter. The stratum zonale, the fibres of which are fine and 
 arranged transversely. Beneath this is the stratum cinereum, a layer of gray 
 matter which resembles a cup, semilunar in shape, thicker in the centre, and 
 thinning off toward the margins, and consisting of numerous multipolar cells, for 
 the most part of small size, embedded in a fine network of nerve-fibres. Below 
 this again is the stratum opticum or upper gray-white layer, characterized by the 
 large amount of fine nerve-fibres which intersect the gray matter. These fibres 
 vary in size in different parts of the layer, but have for the most part a longitudinal 
 direction. The nerve-cells between the fibres are larger, and send their axis- 
 cylinder processes into the next stratum. Finally there is the stratum lemnisci, 
 or deep gray-white layer, which separates the rest of the quadrigeminal body from 
 the gray matter around the aqueduct. It consists of fibres partly derived from 
 the upper fillet and partly from the cells of the preceding layer. Interspersed 
 among these fibres are nerve-cells of large size. 
 
 The anterior quadrigeminal body contains an anterior layer of longitudinal 
 fibres, which takes origin in close relation to the optic fibres and ends in the ciliary 
 centre of the spinal cord. In the posterior quadrigeminal body the white fibres 
 are continuous posteriorly with the lateral fillet, and are continuous laterally with 
 the brachium. The anterior quadrigeminal bodies "associate optic fibres with 
 the nuclei of the third, fourth, and sixth cranial nerves and with the cilio-spinal 
 centre in the cervical cord" (Santee). The posterior bodies constitute "a way- 
 station in the auditory conduction path" (Santee) (Fig. 590). 
 
 The Corpora Geniculata. — The corpora geniculata are two small, oblong 
 masses on each side, situated behind and beneath the posterior end of the optic 
 
912 
 
 THE NERVOUS SYSTEM 
 
 thalamus, and named, from their position, external and internal geniculate bodies. 
 These two bodies are separated from each other by the brachium anterius of the 
 anterior quadrigeminal body. It is convenient and customary to describe these 
 two bodies together, but the student should bear in mind that the corpus genic- 
 ulatum externum belongs in reality to the optic thalamus; the corpus geniculatum 
 internum, which is part of the tegmentum, alone belonging to the mid-brain. 
 
 The External Geniculate Body (corpus geniculatum laterale) (Fig. 613). — The 
 external geniculate body is of a dark color, and presents a laminated arrangement, 
 consisting of alternate layers of gray and white matter. Its cells are large, multi- 
 polar, and pigmented; their processes are intimately related with the visual area 
 in the cerebral cortex of the occipital region (Fig. 590). It is believed that the 
 intercellular gray matter of these bodies is composed, to a considerable extent, of 
 the terminations of the optic nerve, which form synapses around the cells. About 
 80 per cent, of the optic fibres enter the external geniculate body (von Monokow, 
 Santee). It is, in fact, the termination of the outer root of the optic tract. 
 
 The Internal Geniculate Body {corpus geniculatum mediale) (Fig. 613) . — The inter- 
 nal geniculate body is the termination of the inner root of the optic tract. It seems 
 
 MEN 
 ONRO 
 RIOR 
 MISSURE 
 
 OPTIC NERVC 
 DIBULUM 
 
 Fig. 587. — Median section through the third and fourth ventricles, left half. M.C., middle commissure. (Testut.) 
 
 to receive some of the fibres of the optic tract and is "a way-station in the auditory 
 tract" (Santee). It is smaller in size and lighter in color than the external genicu- 
 late body, and does not present a laminated arrangement. It receives the pos- 
 terior brachium from the inferior quadrigeminal body. The internal geniculate 
 bodies are connected with each other through the optic commissure by a band 
 of intercerebral fibres of the optic tract named Gudden's commissure. The anterior 
 quadrigeminal body, the pulvinar, and the external geniculate body are intimately 
 concerned with vision. They constitute the lower cerebral centre for the optic 
 nerve-fibres which end in them. Extirpation of the eyes in newly born animals 
 entails an arrest of their development, but has no effect on the posterior quadri- 
 geminal body or the internal geniculate body. These latter also are well developed 
 in the mole, in which animal the superior quadrigeminal body is rudimentary. 
 
 The Aqueduct of Sylvius or Iter a Tertio ad Quartum Ventriculum (aquae- 
 ductus cerebri) (Figs. 574, 584, 585, and 587).^This is a narrow canal, about 
 
THE MID -BRAIN 913 
 
 half an inch in length and from one-sixteenth to one-eighth of an inch in height, 
 situated between the corpora quadrigemina and the tegmentum, and connecting 
 the third with the fourth ventricle. Its shape on transverse section varies, being 
 T-shaped below, triangular above, and oval about the middle of its course. It 
 is lined by columnar ciliated epithelium, and is surrounded by a layer of gray 
 matter, called the central gray matter of the aqueduct, which is continuous with 
 the gray matter of the third and fourth ventricles. This gray matter is sepa- 
 ratetl above from that of the corpora quadrigemina by the stratum lemnisci; 
 below the central gray matter lie the posterior longitudinal bundle and the 
 formatio reticularis of the tegmentum. The central gray matter is more abun- 
 dant below the canal than above it. In the gray matter are certain defined groups 
 of cells, which are the nuclei of the third and fourth cranial nerves. 
 
 Subthalamic Region. — One other structure, to which allusion has already 
 been made, recjuires mention in this connection; it is the subthalamic region. It is 
 a prolongation forward of the tegmentum of the crus cerebri, which becomes con- 
 tinuous with the lower surface of the optic thalamus. Toward the anterior part 
 of the crus cerebri the tegmentum becomes thinned out, and is blended with the 
 superjacent portion of the optic thalamus. To this region, the name subthalamic 
 tegmental region has been given. In front it is lost at the base of the brain in 
 the gray matter of the anterior perforated space, and is continuous with the gray 
 matter of the floor of the third ventricle. The subthalamic tegmental region con- 
 tains a forward prolongation of the red nucleus, and consists from above down- 
 ward of three layers: (1) stratum dorsale, which is directly applied to the under 
 surface of the optic thalamus, and consists of fine longitudinal fibres; (2) the zona 
 incerta, a continuation forward of the formatio reticularis of the tegmentum ; and 
 (3) the corpus subthalamicum or the nucleus of Luys (nucleus of Luys or nucleus 
 hypothalamic us), a mass of gray matter which on section presents a lenticular 
 shape, and is the termination of the substantia nigra. 
 
 Structure of the Cerebrum. — The cerebrum, like the other parts of the great 
 nerve centre, is composed of gray and white matter. In order to give some general 
 idea of its construction, at all events in part, it may be compared, for the sake of 
 illustration, to a tree, the trunk of which divides into two main divisions, and 
 these break up into smaller branches, which finally end in twigs, to which are 
 attached the leaves, forming an investment to the branches and covering the whole 
 tree. The trunk is represented by the medulla oblongata as it passes through the 
 foramen magnum; the two main divisions by the crura cerebri, which break up 
 into smaller branches; these diverge from each other, divide and subdivide, 
 until they reach the surface of the hemispheres, where they terminate in single 
 nerve-fibres, which are continuous with the basal axial cylinder processes of the 
 nerve-cells, the representatives of the leaves. These cells are arranged on the 
 surface, covering the hemispheres like a cap, and constitute the cerebral cortex. 
 But here the analogy ends, for in the cerebrum there are, in addition to this 
 cortex, other masses of gray matter situated in the middle of the brain; and 
 other white fibres besides the diverging ones that have been mentioned, and which 
 serve either to connect the two cerebral hemispheres, or to unite different structures 
 in the same hemisphere. 
 
 The White Matter of the Cerebrum. — The white matter of the cerebrum con- 
 sists of medullated fibres, varying in size and arranged in bundles, separated 
 by neuroglia. They may be divided into three distinct systems, according to 
 the course they take. 1. Projection or peduncular fibres (Figs. 588, 589, and 590), 
 which connect the hemisphere with the medulla oblongata and corfl. 2. Trans- 
 verse or commissural fibres (C.C. in Fig. 588), which unite together the two 
 hemispheres. 3. Association fibres (Figs. 591 and 592) , which connect different 
 structures in the same hemisphere. Many of the association fibres are collateral 
 
 58 
 
914 
 
 THE NEBVOUS SYSTEM 
 
 branches of the projection fibres, but others are the axones of independent 
 cells. 
 
 1. The Projection or Peduncular Fibres (Figs. 588, 589, and 590) are either cen- 
 trifugal (motor) or centripetal (sensory), and they connect the cerebral cortex with 
 every portion of the body, and either project impulses from the cortex to every por- 
 tion of the body or bring impressions from all parts to the cortex. The basal ganglia 
 
 intercept many projection fibres, 
 especially centripetal fibres. The 
 projection fibres are composed first 
 of the "medullated axis-cylinders 
 of the large and medium-sized pyr- 
 amids and a few of the polymor- 
 phous neurones in the cerebral cor- 
 tex; and second, of medullated ax- 
 ones of neurones whose centres are 
 situated in masses of gray matter 
 below the cerebral cortex."* These 
 fibres form in the hemisphere the 
 corona radiata and the internal 
 capsule, and in the mid-brain the 
 crus. The fibres of the crus are 
 arranged in two strata, the ventral 
 or superficial stratum or crusta and 
 the dorsal or deep stratum or teg- 
 mentum. Between the two strata 
 is the substantia nigra. 
 
 The Centrifugal or Motor 
 Projection Fibres. — Most of 
 
 • ^^^'- 588.— Section through the frontal lobe, showing the be- ^hc lliotor fibres are iucludcd in 
 ginning of the most anterior bundles of the corona radiata, 
 
 •which contain the first fibres of the pyramidal tract (R). C. C, -{^iQ crUSta. Thc deep DOl'tlOn of 
 corpus callosum; C. V., centrum semiovale Vieussenii; C. A., . ' . ^ -^ , 
 
 anterior limb of the internal capsule; ^^ /., inferior frontal con- the Cn*5 IS COmpOSCd 01 the mter- 
 volution (base of the third frontal convolution — motor speech ,. . , ,. . ^ / r\n'y\ 
 
 centre). (Jakob.) mediate bundle or tract (p. 907), 
 
 and the superficial portion of the 
 crus is composed of three sets of fibres (p. 907): 1. The temporal cerebro-cortico- 
 pontal tract (tractus cerehrocortico'pontalis temporalis), occupying the outer one- 
 fifth of the crus. 2. The pyramidal tract (fasciculus longitudinalis 'pyramidalis) , 
 occupying the middle three-fifths of the crus. These fibres pass to the pyramid 
 of the medulla and to the direct and crossed pyramidal tracts of the spinal 
 cord A few fibres from the cerebellum are placed among the pyramidal fibres. 
 They reach the pons by way of the middle cerebellar peduncle, ascend from the 
 pons with the longitudinal fibres, and reach the crusta. 3. The inner one- 
 fifth of the crusta is formed by the median fillet and motor fibres coming from 
 the cortex in front of the Rolandic fissure. The tegmentum contains some few 
 motor fibres arranged in several bundles — viz., the anterior longitudinal bundle, 
 a portion of the superior peduncle of the cerebellum : the descending or motor 
 root of the fifth nerve, the crossed descending tract from the red nucleus. To 
 these previously mentioned motor fibres in the tegmentum, San tee adds "certain 
 fibres in the formatio reticularis."^ 
 
 The Centripetal or Sensory Projection Fibres. — In the tegmentum are 
 the sensory fibres, some of the fibres of the formatio reticularis, some of the fibres 
 of the posterior longitudinal bundle, the fillets, most of the fibres of the superior 
 cerebellar peduncle, the outer root of the optic tract, and the olivary fasciculus. 
 Nearly all of the bundles terminate in the basal ganglia, "but the paths of con- 
 
 ' Anatomy of the Brain and Spinal Cord. By Harris E. Santee. 
 
 « Ibid. 
 
THE MID -BRAIN 
 
 915 
 
 duction are continued through the internal capsule" (Santee). In the internal 
 capsule the sensory projection fibres comprise the three systems of Flechsig (the 
 cortical fillet), the optic radiation, 
 and the acoustic radiation. 
 
 The Three Systems of Flech- 
 sig. — The chief origin of the three 
 systems of Flechsig is in the lateral 
 nucleus of the thalamus. The first 
 system of Flechsig is composed of 
 fibres of common sensation and is 
 called the ansa peduncularis. It 
 passes from the thalamus to the 
 cortex of the ascending frontal and 
 parietal convolutions. The fibres of 
 this first system are in the inferior 
 lamina of the internal capsule, and 
 are posterior to the pyramidal tract. 
 Some fibres of the ansa peduncularis 
 pass through the lenticular nucleus, 
 others pass through the external 
 capsule, but all of them terminate 
 as do those in the internal capsule, 
 in the cortex. The second system of 
 Flechsig is called the ansa lenticularis. 
 Its fibres convey impressions of com- 
 mon sensation. It arises from the 
 thalamus at a higher level than the 
 ansa peduncularis, and in the in- 
 ternal capsule its fibres are among 
 the pyramidal fibres. It terminates 
 in the cortex about the central con- 
 volution, the superior frontal con- 
 volution, the paracentral lobule, and 
 the limbic lobe. Some fibres pass 
 through the internal capsule to the 
 lenticular nucleus and aid in form- 
 ing the external capsule. The third FPyc-- 
 system of Flechsig is the anterior 
 stalk of the thalamic radiation. It 
 
 arises ni the thalamus, passes to the Fig. 589.— Scheme of the projection fibres of the cerebral 
 
 frontal nnrtinn nf tlio infernal r.Qt-. cortex. Cc. Corpus callosum. Cr. Internal capsule, into 
 
 lionidl portion or me internal cap- ^hich fibres pa.ss from the cortex above the Sylvian fissure. 
 
 Sule, and reaches the inferior, mid- ^S{ Caudate nucleus. NL Lenticular nucleus. Th. Optic 
 
 . . .jiv,i.vi, liiiM thalamus, m which many fibres from all parts of the cortex 
 
 die, and superior frontal COnVolu- ^^^- Cip. Posterior divi.sion of the internal cap.sule (the sen- 
 
 . , , ^ (• • m(i sory tract)- Ci»l. Sublenticular part of the internal capsule, 
 
 tlOIlS and the gyrus forniCatUS. The containing fibres of auditory tract and fibres to the thalamus 
 
 .1 • 1 , , from the cortex below the Sylvian fissure. Ch. Luys's body. 
 
 tnircl system also conveys common NR. Red nucleus of tegmentum. Ln. Locus niger. YP. 
 
 oo,Tc/-.T.-ir It-t. * Tract from capsule to pons. Po. Pons. NP. Gray matter 
 
 bensor\ impressions. of pons. Oi. OUve. Py. Pyramidal tract in medulla, passing 
 
 TVip f>nti/» ra/li'Q+iftn (Ti ir, "C.'r, KO^^ *<3 PPyd. anterior median column of cord, and to FPyc, 
 
 i ne optic raaiatlOn [U in l^lg. 59U) lateral column of cord of opposite side, and to fPyh, lateral 
 
 takes oricrin in tlif» nnlvintir nf +]io column of cord of same side. fi. Medulla. (Dejerine, Anat- 
 
 idKtt, origin in tne pUiVinar Ot tne omie des Centres Nerveux, vol. ii. p. 2.) 
 
 thalamus and in the external corpus 
 
 geniculatum. The fibres pass back of the lenticular nucleus and reach the cortex 
 
 of the cuneate lobe, in which region the corresponding half of each retina is 
 
 represented. 
 
 The acoustic radiation (D in Fig. 590) with the inferior brachium from the 
 inferior quadrigeminal body, according to Barker, constitute the continuation of 
 
916 
 
 THE NERVOUS SYSTEM 
 
 the auditory path "from the end of the lateral fillet, in the inferior qiiadrigeminal 
 body, to the internal geniculate body, and then, through the retro-lenticular part of 
 the internal capsule, to the transverse temporal gyri and the third and fourth 
 fifths of the superior temporal convolution."* 
 
 2. The Transverse or Commissural Fibres (Figs. 572, 573, and C.C. in Fig. 588) 
 connect the two hemispheres. They include: (a) the transverse fibres of the 
 corpus callosum (p. 886) ; (6) the anterior commissure (p. 896) ; (c) the posterior 
 commissure (p. 903), and have already been described. 
 
 Fig. 590. — The projection tracts joining the cortex with lower nerve centres. Sagittal section, showing the 
 arrangements of tracts in the internal capsule. A, tract from the frontal lobe to the anterior half of the capsule, 
 thence in part to the optic thalamus, A-, and in part to the pons, and thus to the cerebellar hemisphere of the 
 oppcsite side; B, motor tract from the central convolutions to the facial nucleus in the pons and to the spinal 
 cord; C, sensory tract from posterior columns of the cord, through the posterior part of the medulla, pons, cru.s, 
 and capsule to the parietal lobe; D, visual tract from the optic thalamus (OT) to the occipital lobe; E, auditory 
 tract from the int. geniculate body (to which a tract passes from the VIII . N . nucleus) to the temporal lobe; 
 F, superior cerebellar peduncle; G, middle cerebellar peduncle; H, inferior cerebellar peduncle; CN, caudate 
 nucleus; CQ, corpora quadrigemina. The numerals refer to the cranial nerves. (Starr.) 
 
 3. The Association Fibres (Figs. 591 and 592) connect different structures in the 
 same hemispheres, and are in or near to the cortex. They take origin from the 
 small pyramidal and polymorphous cells of the deep layer of the cortex. Their 
 direction is parallel to the surface of the hemisphere, and in their course they 
 cross the projection and commissural fibres. They are of two kinds: (1) those 
 which unite adjacent convolutions, short association fibres; (2) those which pass 
 between more distant parts in the same hemisphere, long association fibres. 
 
 The short association fibres are situated immediately beneath the gray substance i 
 of the cortex of the hemispheres, and connect together adjacent convolutions. 
 They constitute subcortical tracts and are divided into arcuate fibres and tangen- 
 tial fibres. Some of these fibres connect the "visual sensory area with the visual 
 memory area, and the auditory sensory with the auditory memory area."^ 
 
 The long association fibres associate cerebral centres which are far apart. They j 
 are gathered into bundles and dip down deep into the centrum ovale. Theyi 
 
 ' Anatomy of the Brain and Spinal Cord, by Harris E. Santee 
 
 2 Ibid. 
 
THE MID -BRAIN 
 
 917 
 
 include the following: (a) the uncinate fasciculus; (6) the cingulum; (c) the superior 
 longitudinal fasciculus; {d) the inferior longitudinal fasciculus; (e) the perpendicular 
 fasciculus; (/) the fornix; {g) the occipito-frontal fasciculus. 
 
 Loee 
 Fig. 591. — Diagram showing association-fibres of the hemisphere. (Testut.) 
 
 (a) The Uncinate Fasciculus (fasciculus uncinatus) (Fig. 592) . — The unci- 
 nate fasciculus passes across the bottom of the Sylvian fissure and connects the 
 
 Fio. 592. — The long association fibres.^ A shows the bundles contained in the lateral white substance of the 
 hemispheres; B, those in the mesial white matter. At the upper border a few short association bundles are 
 shown diagrammatically. (Jakob.) 
 
 uncinate convolution with the orbital portion of the frontal lobe. Barker points 
 out that this fasciculus joins the third frontal, internal orbital, and posterior 
 orbital convolutions with the limbic lobe. 
 
918 THE NERVOUS SYSTEM 
 
 (b) The Cingulum or the Fillet of the Gyrus Fornicatus (Fig. 592) is 
 a band of white matter which encircles the hemisphere in an antero-posterior 
 direction, lying in the substance of the convolution of the corpus callosum. 
 Commencing in front at the anterior perforated space, it passes forward and 
 upward parallel with the rostrum, wind around the genu, runs in the convolu- 
 tion from before backward, immediately above the corpus callosum, turns around 
 its posterior extremity, and passes into the Hippocampus major, through which 
 it courses to its anterior extremity. According to Beem there are three sets of 
 fibres in the cingulum. The anterior fibres join the internal olfactory root and 
 the anterior perforated lamina with the front of the frontal lobe. The horizontal 
 fibres join the gyrus fornicatus with the frontal lobe. The posterior fibres join 
 the fusiform convolution (the fourth temporal) with the hippocampal convolution 
 and the temporal lobe.^ 
 
 (c) The Superior Longitudinal Fasciculus {jasciculus longitudinalis supe- 
 rior) (Fig. 592). — The superior longitudinal fasciculus is beneath the convex 
 surface of the hemisphere. It joins the frontal cortex with the parietal and tem- 
 poral cortex and brings into relation the motor speech centres and the centres of 
 auditory and visual memories. 
 
 (d) The Inferior Longitudinal Fasciculus (fasciculus longitudinalis infe- 
 rior) (Fig. 592). — The inferior longitudinal fasciculus associates the centres of 
 auditory and visual memory. It is a collection of fibres which connects the 
 temporal and occipital lobes, running along the outer wall of the descending 
 and posterior cornua of the lateral ventricle. 
 
 (e) The Perpendicular Fasciculus or Fasciculus Rectus (Fig. 592) . — 
 The perpendicular fasciculus runs vertically in front of the occipital lobe, and 
 connects the inferior parietal lobule with the second and third temporal convolu- 
 tions, and also connects the superior occipital convolution with the inferior occipital 
 and the fourth temporal convolutions. 
 
 (/) The Fornix (corpus fornicis) (Fig. 586) . — The fornix by its anterior pillar is 
 connected with the corpus albicans and by means of the bundle of Vicq d'Azyr 
 with the optic thalamus. Most of the posterior pillar ends in the hippocampus 
 major, but some of the fibres (the corpus fimbriatum) go to the uncinate con- 
 volution. Through the fibres of the lyra it probably also unites the opposite 
 hippocampal convolutions. 
 
 {g) The Occipito-frontal Fasciculus of Forel {fasciculus occipitofron- 
 talis) (Fig. 592). — The occipito-frontal fasciculus is placed between the cingulum 
 and the superior longitudinal fasciculus. It connects the frontal cortex with the 
 occipital cortex. Some regard it as a part of the corpus callosum. 
 
 The Gray Matter of the Cerebrum. — The gray matter of the cerebrum, in 
 accordance with its situation, is disposed in three great groups: (1) The gray 
 matter of the cerebral cortex or cortical gray matter. (2) The gray matter of the 
 ganglia or ganglionar gray matter. (3) The central or ventricular gray matter. 
 
 The Gray Matter of the Cortex. — ^The cortex, bark or envelope of the cerebrum, 
 is a thin layer of gray matter on the surface, which encompasses the white matter 
 of the hemispheres {centrum ovale). The cortex has been mapped out into definite 
 areas and centres, each of which is connected with a well-defined function 
 (p. 952). 
 
 On examining a section through one of the convolutions of the Rolandic area 
 with a lens, it is seen to consist of alternating white and gray layers thus disposed 
 from the surface inward: (1) a thin layer of white substance; (2) a layer of gray 
 substance; (3) a second layer of white substance (outer band of Baillarger or 
 band of Gennari); (4) a second gray layer; (5) a third white layer (inner band of 
 
 ' Anatomy of the Brain and Nervous System. By Harris E. Santee. 
 
THE MID- BRAIN 
 
 919 
 
 Molectilar layer 
 
 Layer of small 
 
 pyramidal cells. 
 
 Baillarger) ; (C) a third gray layer, which rests on the medullary substance of the 
 convolution. 
 
 The cortex is made up of nerve-cells which vary in size and shape, and of nerve- 
 fibres, some of which are medullated, but most of which are non-medullated, 
 embedded in a matrix of neuroglia. 
 
 The nerve-cells in a typical section of the cortex are arranged in five layers (Fig. 
 593); named from the surface inward as follows: (1) the molecular layer; (2) the layer 
 of small pyramidal cells; (3) the layer of large pyramidal cells; (4) the layer of poly- 
 morphous cells; (5) the layer of fusiform cell-bodies (Santee) (not shown in Fig. 593). 
 
 The Molecular, the Superficial or the Neuroglia I^ayer. — This layer 
 is immediately adjacent to the pia mater. Neuroglia constitutes the greatest 
 amount of the superficial layer; 
 hence its other name of neuroglia 
 layer. In this layer the cells are 
 irregular and are known as the neu- 
 rones of Cajal. The cells are polyg- 
 onal, triangular, and fusiform in 
 shape, and are associative in func- 
 tion. Each polygonal cell gives off 
 some four or five dendrites, while 
 its axones may arise directly from 
 the cell or from one of its dendrites. 
 The axones and dendrites of these 
 cells ramify in the molecular layer. 
 Each triangular cell gives off two or 
 three dendrites, from one of which 
 the axone arises, the dendrites and 
 the axone ramifying in the molec- 
 ular layer. The fusiform cells are 
 placed with their long axes parallel 
 to the surface and are mostlybipolar, 
 each pole being prolonged into a 
 dendrite, which runs horizontally for 
 some distance and furnishes ascend- 
 ing branches. Their axones, two or 
 three in number, arise from the den- 
 drites, and, like them, take a hori- 
 zontal course, giving off numerous 
 ascending collaterals. The distri- 
 bution of the axones and dendrites 
 of all three sets of cells is limited to 
 the molecular layer. 
 
 Besides the neuroglia, the cells, 
 and the gray fibres, this layer contains medullated nerve-fibres arranged in a 
 network and constituting the superficial white layer. 
 
 The Layer of Small and the Layer of Large Pyramidal Cells. — The 
 cells in the second and third layers may be studied together, since, with the excep- 
 tion of the difference in size and the more superficial position of the smaller cells, 
 they resemble each other. The body of each cell is pyramidal in shape, its base 
 being directed to the deeper parts and its apex toward the surface. It contains 
 granular pigment, and stains deeply with ordinary reagents. The nucleus is 
 nucleolated, of large size, and round or oval in shape. The base of the cell gives 
 off the axone, and this passes into the central white substance, giving off collaterals 
 in its course, and is distributed as a projection, commissural, or association fibre. 
 
 Layer of large 
 pyramidal cells. 
 
 Polymorphous 
 layer. 
 
 White medullary 
 
 substance. 
 
 Fig. 593. — The four layers of cells in the cerebral cortex. 
 Modified from Testut. (After Cajal.) 
 
920 THE NERVOUS SYSTEM 
 
 Both the apical and basal parts of the cell give off dendrites. The apical dendrite 
 is directed toward the surface, and ends in the molecular layer by dividing into 
 numerous branches, all of which may be seen, when prepared by the silver or 
 methylene-blue method, to be studded with projecting bristle-like processes. The 
 larger pyramidal cells, especially in the Rolandic area, may exceed 50// in length 
 and 40// in breadth, and are termed giant cells. The chief function of the small 
 pyramids is commissural and associative. The chief function of the large pyramids 
 is motor, but they have also commissural and associative functions. 
 
 Layer of Polymorphous Cells. — The cells in this layer, as their name implies, 
 are very irregular in contour, the commonest varieties being of a spindle, star, 
 oval, or triangular shape. Their dendrites are directed outward, toward, but do 
 not reach, the molecular layer; their axones pass into the subjacent white matter. 
 From this layer come commissural fibres, long association fibres, and some pro- 
 jection fibres. 
 
 There are two other kinds of cells in the cerebral cortex, but their axones pass 
 in a direction opposite to that of the pyramidal and polymorphous cells, among 
 which they lie. They are: (a) the cells of Golgi, the axones of which do not 
 become medullated, but divide immediately after their origin into a large number 
 of branches, which are directed toward the surface of the cortex; {h) the cells of 
 Martinotti, which are chiefly found in the polymorphous layer. Their dendrites 
 are short, and may have an ascending or descending course, while their axones 
 pass out into the molecular layer and form an extensive horizontal arborization. 
 
 Layer of Fusiform Cell-bodies. — It receives the name of the claustral 
 formation, because it is formed like the claustrum. This layer is not sharply 
 defined from the white matter beneath; the change from one to the other is gradual. 
 The long axes of most of the cells are perpendicular to the surface of the hemi- 
 sphere, but beneath the fissures they are parallel to the surface (San tee). "The 
 commissural and long association fibres belong, for the most part, to the fusi- 
 form and polymorphous neurones."^ 
 
 Nerve-fibres. — These fill up a large part of the intervals between the cells. Some 
 of these fibres form fascicului; some are isolated, and others are arranged in 
 plexuses. They may be medullated or non-medullated — the latter comprising 
 the axones of the smallest pyramidal cells and the cells of Golgi. In their direction 
 the fibres may be either transverse, the transverse tangential or horizontal fibres, 
 or vertical, the vertical or radial fibres. The transverse fibres run parallel to the 
 surface of the hemisphere, intersecting the vertical fibres at a right angle. They 
 consist of several strata, of which the following are the most important: (1) a 
 stratum of white fibres covering the superficial aspect of the molecular layer; (2) 
 the band of Bechterew, found in certain parts of the superficial portion of the 
 layer of the smaller pyramidal cells; (3) the external or outer band of Baillarger 
 or ths band of Gennari, which runs through the layer of large pyramidal cells; 
 (4) the internal band of Baillarger, which intervenes between the layer of large 
 pyramidal cells and the polymorphous layer. According to Cajal, the transverse 
 fibres consist of (a) the collaterals of the pyramidal and polymorphous cells and 
 of the cells of Martinotti; (6) the arborizations of the axones of Golgi's cells; 
 (c) the collaterals and terminal arborizations of the projection, commissural, 
 or association fibres. The vertical fibres. — Some of these— viz., the axones of the 
 pyramidal and polymorphous cells — ^are directed toward the central white matter, 
 while others, the terminations of the commissural, projection, or association fibres, 
 pass outward to end in the cortex. The axones of the cells of Martinotti are also 
 ascending fibres. 
 
 In certain parts of the cortex this typical structure is departed from. The chief 
 
 ' Anatomy of the Brain and Spinal Cord. By Harris E. Santee. 
 
THE MIB-BBAIN 921 
 
 of these regions are: (1) the occipital lobe, (2) the hippocampus major, (3) the 
 dentate convolution, and (4) the olfactory bulb. 
 
 Special Tjrpes of Gray Matter. 1. The Occipital Lobe. — In the cuneiis and 
 the calcarine fissure of the occipital lobe, Cajal has recently described as many as 
 nine layers. Here the inner band of Baillarger is absent; the outer band of Bail- 
 larger or band of Gennari is, on the other hand, of considerable thickness. If a 
 section be examined microscopically, an additional layer is seen to be interpolated 
 between the molecular layer and the layer of small pyramidal cells. This extra 
 layer consists of two or three strata of fusiform cells, the long axes of which are at 
 right angles to the surface. Each cell gives off two dendrites, external and internal, 
 from the latter of which the axone arises and passes into the white central sub- 
 stance. In the layer of small pyramidal cells, fusiform cells, identical with the 
 above, are seen, as well as ovoid or star-like cells with ascending axones, the cells 
 of Martinotti. This area of the cortex forms the visual centre, and it has been 
 shown by Dr. J. S. Bolton* that in old-standing cases of optic atrophy the thick- 
 ness of Gennari's band is reduced by nearly 50 per cent. 
 
 2. The Hippocampus Major. — In the hippocampus major the molecular layer is 
 very thick and contains a large number of Golgi cells. It has been divided into 
 three strata: (a) S. convolutum or S. granulosum, containing many tangential 
 fibres; (6) S. lacunosum, presenting numerous lymphatic or vascular spaces; (c) 
 S. radiatum, exhibiting a rich plexus of fibrils. The two layers of pyramidal cells 
 are condensed into one, and the cells are mostly of large size. The axones of the 
 cells in the polymorphous layer may run in an ascending, descending, or horizontal 
 direction. Between the polymorphous layer and the ventricular ependyma is the 
 white substance of the alveus. 
 
 3. The Dentate Convolution. — In the rudimentary dentate convolution the molec- 
 ular layer contains some pyramidal cells, while the layer of pyramidal cells is 
 almost entirely represented by small ovoid cells. 
 
 4/ The Olfactory Bulb. — In many of the lower animals this contains a cavity 
 which communicates through the hollow olfactory stalk with the cavity of the 
 lateral ventricle. In man the original cavity is filled up by neuroglia and its 
 wall becomes thickened, but much more so on its ventral than on its dorsal aspect. 
 Its dorsal part contains a small amount of gray and white matter, but it is scanty 
 and ill defined. A section through the ventral part shows it to consist of the 
 following layers from without inward. (1) A layer of olfactory nerve-fibres, which 
 are the non-medullated axones prolonged from the olfactory cells of the nose, and 
 which reach the bulb by passing through the cribriform plate of the ethmoid bone. 
 At first they cover the bulb, and then penetrate it to end by forming synapses 
 with the dendrites of the mitral cells, presently to be described. (2) Glomerular 
 layer {stratum glomerulosum). — This contains numerous spheroidal reticulated 
 enlargements, termed glomeruli, which are produced by the branching and arbor- 
 ization of the processes of the olfactory nerve-fibres with the descending dendrites 
 of the mitral cells. (3) Molecular layer. — ^This layer is formed of a matrix of 
 neuroglia, embedded in which are the mitral cells. These cells are pyramidal in 
 shape, and the basal part of each gives off a thick dendrite which descends into 
 the glomerular layer, where it arborizes as indicated above, and others which 
 interlace with similar dendrites of neighboring mitral cells. The axones pass 
 through the next layer into the white matter of the bulb, from which, after becom- 
 ing bent on themselves at a right angle, they are continued into the olfactory tract. 
 (4) N erve-fihre layer. — This lies next the central core of neuroglia, and its fibres 
 consist of the axones or afferent processes of the mitral cells which are passing to 
 the brain; some efferent fibres are, however, also present, and terminate in the 
 
 ^ Phil. Trans, of Royal Society, Series B, vol. exciii. p. 165. 
 
922 ^'HE NERVOUS SYSTEM 
 
 molecular layer, but nothing is known as to their exact origin. It is to be remem- 
 bered that the olfactory path is uncrossed or almost completely uncrossed. 
 
 The Gray Matter of the Ganglia or the Ganglionar Gray Matter. — These ganglia 
 have been previously described. They are as follows: The corpus striatum, the 
 optic thalamus, the external geniculate body, the internal geniculate body, the 
 nucleus of Luys, the red nucleus of the tegmentum, the anterior quadrigeminal 
 body, the posterior quadrigeminal body, the substantia nigra, and the inter- 
 peduncular ganglion. 
 
 The €entral or Ventricular Gray Matter. — This includes the lamina cinerea, the 
 tuber cinereum, the middle commissure, the nuclei of the third and fourth 
 cranial nerves, and the gray matter about the aqueduct of Sylvius. 
 
 IV. The Hind-brain (Rhombencephalon). 
 
 From the hind-brain or rhombencephalon, as previously stated, come two vesi- 
 cles, the metencephalon, or upper portion of the hind-brain or the hind-brain proper, 
 and the myelencephalon, or lower portion of the hind-brain. From the metence- 
 phalon come the pons and the cerebellum. From the myelencephalon comes the 
 medulla oblongata. The original hind-brain remains in the brain of the adult 
 as the fourth ventricle. 
 
 Pons Varolii (Figs. 557, 599, and 693). — The pons Varolii is the bond of union 
 between the various segments of the encephalon, connecting the cerebrum above, 
 the medulla oblongata below, and the cerebellum behind. It lies upon a portion 
 of the clivus, the groove of bone between the foramen magnum and the dorsum 
 sellae, and is situated above the medulla oblongata, below the crura cerebri, and 
 between the hemispheres of the cerebellum. It is about an inch in length, an 
 inch in thickness, and an inch and a half in width. It presents four surfaces: the 
 superior surface, which is attached, by direct continuation of fibres, to the mid- 
 brain; the inferior surface, which is continuous with the medulla oblongata;- the 
 anterior or ventral and the posterior or dorsal surfaces are free. 
 
 The Anterior or Ventral Surface, the Tuber Annulare or Base {^ars hasilaris pontis)^ 
 is very prominent, markedly convex from side to side, but less so from before back- 
 ward. It consists of transverse white fibres (Fig. 594) , which arch like a bridge 
 across the middle line, and on either side are gathered together into a compact mass, 
 forming the middle peduncle of the cerebellum (Fig. 599). Above and below it 
 presents a well-defined border; below, its transverse fibres slightly overlap the 
 pyramidal bodies of the medulla, which disappear into its substance; above, the 
 transverse fibres slightly overlap the crura cerebri which emerge from it. This 
 surface rests upon the clivus of the sphenoid bone, and presents in the middle 
 line a longitudinal groove (sulcus hasilaris) (Fig. 603), wider in front than behind, 
 in which rests the basilar artery. Slightly in advance of the middle of the ventral 
 surface of the pons and at the margin the two roots of the fifth nerve emerge. 
 
 The Posterior or Dorsal Surface (jpars dorsalis pontis). — The posterior or dorsal 
 surface of the pons is free, but is concealed from view by the cerebellum. It forms 
 the upper part of the floor of the fourth ventricle, and will be described with this 
 cavity (Fig. 604 and p. 942). 
 
 Structure. — Transverse sections of the pons Varolii show that it consists of two 
 parts, which differ in appearance and structure from each other: the anterior or 
 ventral portion (Fig. 594) consists for the most part of fibres arranged in transverse 
 and longitudinal bundles with a small amount of gray matter; the posterior or dorsal 
 portion is chiefly constituted by a continuation upward of the reticular formation 
 of the gray matter of the medulla, and is called the tegmental portion, as most 
 of its constituents are continued into the tegmentum of the crus cerebri. It is 
 subdivided into lateral halves by a median raphe continuous with that of the 
 
THE IIEXB-BHAIJV 
 
 923 
 
 medulla, but the raphe does not extend into the ventral half of the pons, behig 
 here obliterated by the transverse fibres. 
 
 Transverse Fibres of the Pons. — The transverse fibres are placed in the ventral 
 portion of the pons. These are disposed in three sets: 
 
 1 . The Superficial or Ventral Transverse Fibres (fihrae pontis superficiales) (Fig. 
 594) constitute a rather thin layer on the ventral surface of the pons. This thin 
 white layer is called the tuber annulare. 
 
 2. The Middle or Deep Transverse Fibres are placed dorsally or above the 
 superficial transverse fibres, and form a thick layer, with much gray matter 
 between them. These collections of gray matter are named the nuclei pontis. In 
 this layer of transverse fibres are longitudinal fibres coming from the middle 
 three-fifths of the crustae and passing to the pyramids of the medulla and also 
 
 Fig. 594. — Superficial dissection of the medulla oblongata and pons. (Ellis.) 
 
 fibres of the fronto-pontal, intermediate, and temporo-frontal tracts (Santee). 
 The middle cerebellar peduncles (brachia pontis) (Fig. 599) are formed by the 
 superficial and middle transverse fibres. 
 
 3. The Dorsal Transverse or Dorsal Deep Transverse Fibres lie dorsally to the 
 middle transverse fibres and the pyramidal fibres between them and the formatio 
 reticularis. These fibres are collected into a distinct bundle which is most defi- 
 nite in the posterior portion of the pons and in which region it is named the trape- 
 zium (corpus trapezoideum) , because of its shape. The trapezium is the mark of 
 the boundary between the dorsal and ventral surfaces. The chief origin of the 
 trapezium is from the cochlear nerve nuclei; they decussate and pass by the 
 lateral fillet to the inferior quadrigeminal body. Santee points out that the trape- 
 zium and lateral fillet are part of the auditory conduction path. 
 
 Longitudinal Fibres of the Pons. — These are found in both the ventral and dorsal 
 portions. There are three sets: 
 
924 THE NERVOUS SYSTEM 
 
 The Ventral Longitudinal or Ventral Deep Longitudinal Fibres (Fig. 594) are chiefly 
 the continuation of the pyramidal fibres of the crustae which reach the pyramids 
 of the medulla. They form a thick bundle. Among these fibres are some from 
 the opposite cerebellar peduncles and the nuclei pontis. During the descent of 
 the pyramidal tract it grows constantly smaller, because it loses here and there 
 fibres which pass to motor cranial-nerve nuclei. The pressure of the thick bundle 
 of pyramidal fibres causes a bulging of the superficial transverse fibres on the 
 ventral surface of the pons and the formation of the mesial groove between them. 
 
 The Middle Longitudinal or Dorsal Deep Longitudinal Fibres are placed in the 
 floor of the fourth ventricle in the 'pontine formatio reticularis, which is continuous 
 with the formatio reticularis of the medulla oblongata. The pontine formatio 
 reticularis is a network of these longitudinal fibres with some oblique fibres, the 
 network containing gray matter. Some of the gray matter of the formatio retic- 
 ularis forms the nuclei of certain cranial nerves; the rest of it forms the nuclei 
 of the formatio reticularis. Santee describes six bundles of longitudinal fibres in 
 the formatio reticularis : 1 . The fillet (lemniscus) , consisting of the lateral, the median, 
 and the superior fillet {lemniscus lateralis, lemniscus medialis, lemniscus superior), 
 passing to and through the tegmentum to the thalamus and the two quadri- 
 geminal bodies. 2. The posterior longitudinal bundle (fascic^dus longitudinalis 
 medialis) contains both ascending and descending fibres; most of the fibres do 
 not decussate but reach the anterior column of the same side of the cord. 
 Some of its fibres decussate through the pons, medulla, and mid-brain. 
 According to Santee, it receives ascending fibres from the gray matter of the 
 anterior cornu of the spinal cord, from the sensory nuclei of cranial nerves, and 
 through the middle peduncle from the cerebellum. It terminates in the sub- 
 thalamic region. The fibres decussate across the posterior commissure. In this 
 bundle are motor fibres passing from the sixth to the third nerves and from the 
 third to the seventh. 3. The anterior longitudinal bundle {fasciculus ventralis) 
 passes from the superior quadrigeminal body to the gray matter of the anterior 
 cornu of the cervical cord. "It is the pupillo-dilator tract. "^ 4. The olivary 
 bundle or the central tegmental tract (fascicidus tegmenti centralis) arises from 
 the inferior olivary nucleus of the medulla, ascends to the lenticular nucleus, 
 from which situation some of the fibres pass to the cortex. 5. The crossed descend- 
 ing tract from the red nucleus. It arises in the red nucleus of the tegmentum, 
 soon crosses the raph^, and, as Barker points out, reaches the lumbar region of 
 the cord. In the pons the fibres are in the lateral fillet. 6. The ascending or infe- 
 rior sensory root of the fifth nerve {tractus spinalis nervi trigemini) arises near the 
 Rolandic tubercle in the medulla and effects a junction with the superior root 
 ventrally to the superior peduncles of the cerebellum. 
 
 The Dorsal Longitudinal or Superficial Longitudinal Fibres constitute the roof 
 of the superior portion of the fourth ventricle, and form the superior peduncles 
 of the cerebellum (p. 932) and the valve of Vieussens (p. 933). 
 
 Gray Matter of the Pons. — The nuclei pontis constitute a portion of it, th«» gray 
 matter of the formatio recticularis the balance. 
 
 The Nuclei Pontis, which have been previously referred to, are collections of 
 gray matter .on each side of the pons, between the fibres of the middle transverse 
 bundle and of the ventral longitudinal bundle of the pons. The nucleus pontis 
 of each side receives fibres from the crusta — viz., the intermediate bundle, the frontal 
 cerebro-cortico-pontal tract (p. 893), and the temporal cerebro-cortico-ponval tract 
 (p. 894), and also receives fibres from the middle peduncle of the cericbellum 
 (p. 934) . It sends fibres by the middle peduncle to the opposite cerebellar hemi- 
 sphere. The nuclei pontis contain numerous multipolar ganglion cells. 
 
 ' Anatomy of the Brain and Spinal Cord. By Harris E. Santee. 
 
THE HIND-BRAIN 925 
 
 The Gray Matter of the Pontine or Formatio Reticularis forms the superior 
 olivary nucleus, the nuclei of the trapezium, numerous nuclei of the formatio reticu- 
 laris, and nuclei of certain cranial nerves. The portion of the formatio reticularis 
 between the roots of the sixth pair of cranial nerves is called the formatio reticularis 
 alba; the portion between the roots of the sixth and seventh nerves is called the 
 formatio reticularis grisea. 
 
 The Superior Olivary Nucleus (nucleus olivaris superior) is upon the dorsal surface 
 of the outer part of that collection of fibres known as the trapezium. It is not large 
 enough to be visible to the naked eye and contains very small nerve-cells. It is a 
 part of the auditory pathway, and its fibres enter the accessory auditory nucleus 
 of the opposite sitle. The nuclei of the trapezium are in the auditory pathway. 
 There are numerous other nuclei in the formatio reticularis (nuclei of the formatio 
 reticularis, or the nucleus magnocellularis diffusus of Koelliker). The cells of 
 these nuclei are large and multipolar, and their axones cross to the opposite side 
 of the pons. They receive fibres from cranial-nerve nuclei and axones from the 
 cells of the folium of the cerebellum which are called cells of Purkinje. These 
 nuclei are probably connected with various pontine tracts. 
 
 The Nuclei of the Fifth Nerve (Fig. 613) in the pons are two in number, one for 
 the motor root and the other for the sensory. The motor nucleus is situated in the 
 higher portion of the pons, close under the dorsal surface and along the line of the 
 lateral margin of the fourth ventricle. The sensory nucleus lies external to the motor 
 one, beneath the superior peduncle of the cerebellum, which forms the lateral 
 boundary of the upper half of the fourth ventricle. Some of the fibres from these 
 nuclei pass to the raphe of the pons, and thence probably to the higher parts of the 
 brain ; the rest form the nerve-roots of the motor and sensory parts of the fifth 
 nerve respectively. They pass through the pons to emerge on its ventral surface 
 at its lateral and constricted portion, nearer its superior than its inferior margin. 
 It must be mentioned that the whole of the roots of the fifth nerve are not formed 
 from these nuclei. The sensory root is partly formed by a long tract of fibres, 
 known as the ascending root, which can be traced through the pons to the nucleus 
 of Rolando in the medulla. The motor root, in like manner, is partly formed by 
 a long tract of fibres, which passes downward from the gray matter in the floor 
 of the fourth ventricle and the floor of the Sylvian aqueduct and which is termed 
 the descending root. 
 
 The Nucleus of the Sixth Nerve (Fig. 613) is situated beneath the floor of the fourth 
 ventricle, on either side of the middle line. It lies close to the root of the facial nerve, 
 immediately to be described, being a little external to and beneath it, and corre- 
 sponds to the upper half of the fasciculus teres of the floor of the fourth ventricle 
 (Fig. 606). The fibres pass through the substance of the pons, and emerge at the 
 lower margin of this structure, between it and the upper end of the medulla. 
 
 The Nucleus of the Facial Nerve (nucleus n. facialis) (Fig.613) is of elongated form, 
 and is situated deeply in the reticular formation below the superior fovea of the floor 
 of the fourth ventricle. The roots of the nerve derived from it pursue a remarkably 
 tortuous course in the substance of the pons. At first they pass backward and 
 inward till they reach the floor of the fourth ventricle, close to the median groove, 
 where they are collected into a rounded bundle. This passes upward and for- 
 ward, producing an elevation (fasciculus teres) in the floor of the ventricle, and 
 then takes a sharp bend and arches outward through the substance of the pons 
 to emerge at its lower border in the interval between the olivary and restiform 
 bodies of the medulla. The pars intermedia of Wrisberg takes origin from the 
 floor of the fourth ventricle beneath the inferior fovea. 
 
 The Nuclei of the Auditory Nerve (nuclei n. acu^tici) (Fig. 613) are two in number, 
 dorsal and ventral. The origin of the dorsal or vestibular root is from a nucleus situ- 
 ated in the medulla, but prolonged upward into the pons, where it lies beneath the 
 
926 THE NERVOUS SYSTEM 
 
 upper half of the floor of the fourth ventricle {nuclei n. vestibularis) . The dorsal 
 root also takes origin from the cerebellum (from the nucleus fastigii and the 
 nucleus globosus). iVccording to Golgi, the vestibular root is also in connection 
 with the nucleus of Deiters and the nucleus of Bechterew. The ventral or 
 cochlear root arises from the ventral or accessory nucleus (nuclei n. cochlearis) 
 which is also partly contained in the medulla and partly in the pons. In the 
 medulla it is situated on the antero-external surface of the restiform body, 
 lying between the vestibular and cochlear divisions of the auditory nerve, the 
 latter being to its outer side. In the pons it is seen to lie beyond the boundary of 
 the fourth ventricle on the outer and ventral aspect of the restiform body. A third 
 nucleus, nucleus of Deiters, is sometimes termed the outer nucleus of the auditory 
 nerve. It is situated below the outer angle of the fourth ventricle, and contains 
 multipolar nerve-cells of large size. The outer portion of the nucleus of Deiters 
 is called Bechterew's nucleus. The root of the auditory nerve consists of two 
 portions, lateral and mesial, which pass, one to the outer and the other to the 
 inner side of the restiform body, those from the lateral part arising mainly from 
 the ventral nucleus, those from the mesial part arising from the dorsal auditory 
 nucleus. They emerge at the lower border of the pons, in the groove between 
 the olivary and restiform bodies. 
 
 The Cerebellum or Little Brain (Figs. 557, 595, 596, 597, 598, and 599).— 
 The cerebellum is contained in the inferior occipital fossse, and is situated beneath 
 the occipital lobes of the cerebrum, from which it is separated by the tentorium 
 cerebelli. In form it is oblong and flattened from above downward, its great 
 diameter being from side to side. It measures from three and a half to four inches 
 transversely, two to two and a half inches from before backward, and is about 
 two inches thick in the centre, and about six lines thick at the circumference. 
 It consists of gray and white matter: the former, darker than that of the cere- 
 brum, occupies the surface (substantia corticalis), and masses of it are also 
 found in the interior. The white matter is in the interior (corpus medullare). 
 The surface of the cerebellum is not convoluted like that of the cerebrum, but 
 is traversed by numerous curved furrows or sulci, which vary in depth at dif- 
 ferent parts, and separate the laminae of which it is composed. 
 
 Lobes of the Cerebellum. — The cerebellum consists of three parts or lobes, a 
 median and two lateral. They are all continuous with each other, and are sub- 
 stantially the same in structure. The median portion is called the worm or vermi- 
 form process (vermis), from the annulated appearance which it presents, owing to 
 transverse ridges and furrows upon it. On the upper surface of the cerebellum, 
 the worm is only slightly elevated above the level of the lateral portions, but on the 
 under surface it is sunk almost out of sight in a deep depression, which is called 
 the valley or vallecula (vallecula cerebelli). The lateral parts of the cerebellum are 
 called hemispheres (hemisphaeria cerebelli) ; they attain a considerable size, overlap- 
 ping and obscuring the inferior part of the worm. Below and behind they are 
 separated by a deep notch, the posterior cerebellar notch or the incisura marsupialis 
 (incisura cerebelli posterior), and in front by a broader, shallower notch, the anterior 
 cerebellar notch or the incisura semilunaris (incisura cerebelli anterior). The anterior 
 notch lies close to the pons and upper part of the medulla, and its upper edge encir- 
 cles the posterior corpora quadrigemina. The posterior notch is free, and contains, 
 in the recent state, the upper part of the falx cerebelli. The sides of the notches are 
 formed by the margins of the hemispheres, while the bottom of the notches is 
 formed by the anterior and posterior extremities of the worm respectively. The 
 cerebellum is characterized by its laminated or foliated appearance ; it is everywhere 
 marked by deep, transverse, somewhat curved fissures, which lie close together, 
 and extend for a considerable depth into the substance of the cerebellum, dividing 
 it nito a senes of layers or leaves. Upon making sections across the laminae 
 
THE HIND -BRAIN 
 
 92: 
 
 it will be seen that the folia, though differing in appearance from the convolu- 
 tions of the cerebrum, are homologous with them, inasmuch as they consist of a 
 central white substance, with a covering or cortex of gray matter. 
 
 The largest and deepest fissure is the great horizontal fissure (sulcus horizontalis 
 cerehelli) (Figs. 595 and 596). It commences in front at the pons, and passes hori- 
 zontally around the free margin of the hemisphere to the middle line behind, and 
 divides the cerebellum into an upper and lower portion. Several secondary but 
 deep fissures separate thecerebelhun into lobes, and these are further subdivided by 
 shallower sulci, which separate the individual folia or laminae from each other. 
 
 When the cerebellum is removed from the pons and medulla, the transverse 
 fissure (fissura transversa cerehelli) is seen upon its anterior margin. This fissure 
 is between the superior and inferior medullary laminae. 
 
 The white matter in the interior of the cerebellum is known as the medullary 
 body (corpus medullare) . About the middle it divides into a superior and an inferior 
 lamina (Laminae medullares) . These laminae help to form the fourth ventricle. 
 The superior lamina is composed of the superior medullary velum and the 
 peduncles of the cerebellum. The inferior lamina constitutes the inferior 
 medullary velum. 
 
 The cerebellum is connected to the cerebrum, pons, and medulla by three pairs 
 of peduncles, which will be described in the sequel; a superior pair connect it 
 with the cerebrum; a middle pair, with the pons; and an inferior pair, with the 
 medulla. 
 
 Ala lohuli centralis. Post-central Pre-clival fissure. 
 Lohnlus centralis. 
 
 Great 
 liorisontal 
 
 Jissnre 
 
 clival fissure. 
 
 Fig 595. — Upper surface of the cerebellum. (Schafer.) 
 
 The Upper Surface of the Cerebellum (fades cerehelli superior) (Fig. 595). — The 
 superior surface of the cerebellum is somewhat elevated in the middle line and 
 sloped toward its circumference, its hemispheres being connected together by an 
 elevated median portion or lobe, the superior vermis or superior vermiform process 
 (vermis superior cerehelli). The front of the superior vermis is elevated, and the 
 highest point is called the monticulus cerehelli. The surface is traversed by four 
 curved fissures, which are named from their situation, in front or behind two 
 prominent lobes of the worm, the central lobe and the clivus: (1) the pre-central 
 fissure (sulcus praecentralis cerehelli) ; (2) the post-central fissure (sulcus postcentralis) ; 
 (3) the pre-clival fissure, and (4) the post-clival fissure. These four fissures divide 
 the entire upper surface of the cerebellum into five lobes, but the portion of the 
 lobe in the worm has received a different name from that in the hemisphere, 
 though the two are continuous with each other. The five lobes in the worm are 
 named from before backward : (1) the lingula, (2) the central lobule, (3) the culmen 
 monticuli, (4) the clivus monticuli, and (5) the folium cacuminis (folium vermis). 
 
928 THE NERVOUS SYSTEM 
 
 The five lobes in the hemispheres are named from before backward: (1) the 
 fraenulum, (2) the ala lobuli centralis, (3) anterior crescentic, (4) posterior crescentic, 
 and (5) posterior superior. The arrangement of these fissures and lol)ules will be 
 understood by reference to the accompanying schematic arrangement, in which 
 the lobules are named in order from before backward with the fissures which 
 separate them: 
 
 Worm. Hemisphere. 
 
 Lingula. Fraenulum. 
 
 Pre-central Fissure. 
 Lobulus centralis. Ala lobuli centralis. 
 
 Post-central Fissure. 
 Culmen monticuli. Anterior crescentic lobe. 
 
 Pre-clival Fissure. 
 Clivus monticuli. Posterior crescentic lobe. 
 
 Post-clival Fissure. 
 Folium cacuminis. Posterior superior lobe. 
 
 The Lingula (lingula cerebelli) (Fig. 598) is a tongue-shaped process of the vermis^ 
 which lies in the anterior cerebellar notch in front of the lobulus centralis, and is 
 partially or completely concealed by it. It is in relation, in front, with the valve of 
 Vieussens, on the dorsal surface of which it rests and with which it is connected ; 
 its white matter being continuous with that of the valve. At either side the 
 lingula gradually shades off, and is prolonged only for a short distance into the 
 hemispheres, where it forms the fraenulum {vinculum lingulae cerebelli). This does 
 not stretch beyond the superior peduncle of the cerebellum over which it lies. 
 
 The Central Lobe and Alae {lobulus centralis). — The lobusor lobulus centralis is 
 a small square lobe, situated in the anterior notch. It overlaps the lingula and is 
 in turn partially concealed l)y the culmen monticuli. I^aterally the lobulus cen- 
 tralis extends along the upper and anterior part of each hemisphere, where it 
 forms a wing-like prolongation, the ala lobuli centralis. 
 
 The Culmen Monticuli Cerebelli is much larger than the two lobes just described, 
 and constitutes, with the succeeding lobe, the clivus, the bulk of the upper worm. 
 In front it partially overlaps and obscures the lobulus centralis, and l)ehind it is 
 separated from the clivus by the pre-clival fissure. It forms the most prominent 
 part of the upper worm, and is marked on its surface by three or four secondary 
 fissures, dividing it up into smaller lobules. Laterally it is continuous with the 
 anterior crescentic lobe of the hemisphere {-pars anterior lobuli quadrangularis), 
 which is distinctly differentiated from the posterior crescentic lobe by the pre- 
 clival fissure, though the two were formerly classed together as the quadrate lobe 
 of the lateral hemisphere. 
 
 The Clivus Monticuli (declive monticuli cerebelli) is of considerable size, and, as 
 stated above, forms with the culmen the major part of the superior worm. It con- 
 sists of a group of laminae, which in front are separated from the culmen by the 
 pre-clival fissure and behind appear to be almost continuous with the folium 
 cacuminis, especially in the median line; but it will be found, on careful examina- 
 tion, to be separated from it by a well-defined fissure, the post-clival fissure. I^ater- 
 ally this lobe is continued into the hemispheres as the posterior crescentic lobe 
 (pars posterior lobuli quadrangularis), which is somewhat semilunar in shape, and, 
 with the anterior crescentic lobe, constitutes the greater part of the upper surface 
 of the hemispheres. 
 
THE HIND- BRAIN 
 
 929 
 
 The Folium Cacuminis {folium vermis) is a short and narrow, concealed band 
 at the posterior extremity of the worm, consisting apparently of a single folium, 
 but in reality marked on its upper and under surfaces by secondary fissures. 
 Laterally it expands in either hemisphere into a considerable lobe, which is semi- 
 lunar in shape, and is situated at the postero-superior part of the hemisphere and 
 
 Post- nodular fissure. 
 
 Fhcculus. 
 
 Pre- 
 
 pyramidal 
 
 fissure. 
 
 Great 
 
 orizontal 
 ssure. 
 
 pyram 
 fissure. 
 
 Fig. 596. — Under surface of the cerebellum. (Schafer.) 
 
 is bounded below by the great horizontal fissure. It is named the posterior superior 
 lobe {lobulus semilunaris superior), and occupies the posterior third of the upper 
 surface of the hemisphere, forming its rounded postero-lateral border. 
 
 The Under Surface of the Cerebellum (fades cerehelli inferior) (Figs. 596 and 597). 
 — The under surface of the cerebellum presents in the middle line the inferior vermis 
 
 Fig. 597. — Diagram showing fissures on under surface of the cerebellum. F. Flocculus. N. Nodule. 
 Py. Pyramid. Am. Amygdala. Bivent. Biventral lobe. 
 
 V. Uvula. 
 
 or inferior vermiform process (vermis inferior cerehelli), buried in the vallecula, 
 and separated from the hemispheres by lateral grooves. Here, as on the upper 
 surface, there are deep fissures, dividing it into separate segments or lobes, but 
 the arrangement is more complicated, and the relation of the segments of the 
 worm to those of the hemisphere is less clearly marked. The fissures are three 
 
 59 
 
930 THE NERVOUS SYSTEM 
 
 in number, but are not so regularly disposed as those on the upper surface (Fig. 
 597). They are named, from their relation to the pyramid and nodule, two of 
 the lobes on the under surface of the worm: (1) post-nodular, (2) pre-pyramidal, 
 and (3) post-pyramidal fissures. The part of the worm in front of the post-nodular 
 fissure is termed the nodule {nodulus vermis), and the lobule in the hemisphere 
 corresponding with this is the flocculus. The next lobe is situated between the 
 post-nodular and pre-pyramidal fissures. In the vermiform process it is known 
 as the uvula, and its lateral expansion in the hemisphere is named the amygdala 
 or tonsil. The lobule of the worm between the pre- and post-pyramidal fissures 
 is the pyramid, and its corresponding part in the hemisphere is the biventral or 
 digastric lobe. Finally, behind the post-pyramidal fissure in the worm i^ a small 
 lobe, the tuber valvulae or tuber posticum ; this, in the hemispheres, expands into a 
 large lobe, which occupies at least two-thirds of the inferior surface of the cere- 
 bellum, and is subdivided into two by a secondary fissure, named the post-gracile 
 fissure. The anterior of the two subdivisions is named the slender lobe; and the 
 posterior, the inferior semilunar or posterior inferior lobe. These fissures and lobes 
 are here arranged, from before backward, in a schematic form: 
 
 Worm. Hemisphere. 
 
 Nodule. Flocculus. 
 
 Post-nodular Fissure. 
 Uvula. Amygdala. 
 
 Pre-pyramidal Fissure. 
 Pyramid. Biventral lobe. 
 
 Post-pyramidal Fissure. 
 
 r Slender lobe. 
 Tuber valvulae s Post-gracile Fissure. 
 
 (.Inferior semilunar lobe. 
 
 The Fissures of the Under Surfaces of the Cerebellum. — The chief fissures of the 
 under surface, as stated above, are three in number, and are not so regularly dis- 
 posed as on the upper surface. 
 
 (1) The Post-nodular Fissure in the worm courses transversely across it, separat- 
 ing the nodule in front from the uvula behind. When it reaches the hemispheres 
 it passes in front of the amygdala, and then crosses between the flocculus in front 
 and the biventral lobe behind, and joins the anterior end of the great horizontal 
 fissure. 
 
 (2) The Pre-pyramidal Fissure crosses the worm between the uvula in front and 
 the pyramid behind, then curves laterally behind the amygdala, and passes forward 
 along the outer border of this lobe, between it and the biventral lobe, to join the 
 post-nodular sulcus. 
 
 (3) The Post-pyramidal Fissure passes across the worm behind the pyramid and 
 in front of the tuber valvulae, and in the hemispheres courses behind the amygdala 
 and biventral lobes, and then along the outer border of the biventral lobe to the 
 post-nodular sulcus. It cuts off at least two-thirds of the inferior surface of the 
 hemisphere. From it a secondary sulcus springs, and, coursing forward and 
 outward, divides this surface into two parts and falls into the great horizontal 
 fissure. This sulcus is termed the post-gracile fissure. 
 
 The Lobes of the Inferior Surface of the Cerebellum. — The Nodule (nodulus vermis) 
 is a distinct prominence, forming the anterior extremity of the inferior worm. It 
 projects into the roof of the fourth ventricle, and can only be distinctly seen after 
 the cerebellum has been separated from the medulla and pons. On each side of 
 
THE HIND- BRAIN 931 
 
 the nodule is a thin layer of white substance, named the inferior meduUaxy velum. 
 It is semilunar in form, its convex border being continuous with the middle 
 peduncle of the cerebellum; it extends on either side as far as the flocculus, 
 which it connects with the nodule. 
 
 The flocculus {flocculi secondarii) is a prominent, irregular lobule, situated 
 just in front of the biventral lobe, between it and the middle peduncle of the 
 cerebellum. It takes origin from a fold of gray matter in the inferior medullary 
 velum, which is anterior to the tonsil. This fold is called the peduncle of the 
 flocculus {peduncidus flocculi). Externally the gray fold enlarges and the enlarge- 
 ment is the flocculus. It is subdivided into a few small laminae. 
 
 The Uvula (uvula vermis) occupies a considerable portion of the inferior worm ; 
 it is separated on either side from the amygdala by a deep groove, the sulcus val- 
 leculae, at the bottom of which it is connected to the amygdala by a commissure 
 of gray matter, indented on its surface, and called the furrowed band. The uvula 
 is marked on its surface by three or four transverse fissures. 
 
 The Tonsil or Amygdala {tonsilla cerehelli) is a rounded mass in the lateral 
 hemisphere. There are two tonsils, one in each lateral hemisphere. Each lies 
 in a deep fossa' between the uvula and the biventral lobe; this fossa is known by 
 the name of the bird's nest {nidus avis). 
 
 The P3nramid Lobe {pyramis vermis) is a conical projection, forming the largest 
 prominence of the lower worm. It is separated from the hemispheres by the sulcus 
 valleculae, across which it is connected to the biventral lobe by an indistinct band 
 of gray matter, analogous to the furrowed band already described. 
 
 The Biventral Lobe or Digastric Lobule (lobulus hiventer) is triangular in shape, 
 with the apex pointing inward and backward to become joined by the connecting 
 band to the pyramid. The external border is separated from the slender lobe by 
 the post-pyramidal fissure. The base is directed forward, and is on a line with the 
 anterior border of the amygdala, and is separated from the flocculus by the post- 
 nodular fissure. 
 
 The Tuber Valvulae or Tuber Posticum {tuber vermis) is the posterior division of 
 the inferior worm. It is of small size, and laterally spreads out into the large poste- 
 rior inferior lobes of the hemispheres. These lobes, which, as stated above, com- 
 prise at least two-thirds of the inferior surface of the hemisphere, are divided into 
 two by the post-gracile fissure. The anterior lobe is named the slender lobe, and 
 the posterior, the inferior semilunar lobe {lobulus semilunaris inferior). Both these 
 lobes show a tendency to subdivision into two; that of the slender lobe is well 
 marked, and its subdivisions are sometimes described as distinct lobes and named 
 the anterior and posterior slender lobes, the fissure between them being termed the 
 intra-gracile fissure. 
 
 The Internal Structm-e of the Cerebellum. — The cerebellum consists of white and 
 gray matter. 
 
 The White Matter. — If a sagittal section (Fig. 598) is made through either 
 hemisphere of the cerebellum, the interior will be found to consist of a central 
 stem of white matter, the medullary body (corpus medullare), which contains in its 
 interior a gray mass, the corpus dentatimi (nucleus dentatus). It is a fold of gray 
 matter thrown into corrugations and surrounding a centre of white matter. From 
 the surface of this central stem a series of plates of medullary matter are de- 
 tached, which, covered with gray matter, form the laminae. In consequence of 
 the main branches from the central stem dividing and subdividing, the section 
 presents a characteristic appearance, which is named the arbor vitae cerebelli. If 
 a vertical section is made in the median plane of the cerebellum it will be found 
 that the central stem divides into two main branches, which, from their direction, 
 may be named respectively the vertical and the horizontal branch. The vertical 
 branch passes upward to the culmen, where it subdivides freely, some of its ramifi- 
 
932 
 
 THE NERVOUS SYSTEM 
 
 cations passing forward and upward to the central lobe. The horizontal branch 
 passes backward to the folium cacuminis, considerably diminished in size in 
 consequence of having given off large secondary branches : one, from its upper 
 surface, ascends to the clivus; the others descend, and enter the lobes in the 
 inferior vermiform process, the tuber valvulae, the pyramid, the uvula, and the 
 nodule. In the interior of the worm is white matter called the corpus trapezoides. 
 It is not necessary to describe in detail the various divisions of the white matter, 
 as they correspond to the lobes on the surface. 
 
 Anterior 
 
 crescenUc lobe. 
 
 Ala lohnli centralis. 
 
 Lingula. 
 
 Superior peduncles 
 of cerebellum. 
 
 Great 
 horizontal ^ 
 fissure. '"''^>' 
 
 Slender lobe. 
 
 Amygdala. 
 
 Nodule. Fourth ventricle. 
 
 Fig. 598. — Sagittal section of the cerebellum, near the point of junction of the worm with the hemisphere. 
 
 (Schiifer.) 
 
 The white matter of the cerebellum includes three systems of fibres: (1) 
 projection or peduncular fibres, which are directly continuous with those of the 
 peduncles of the cerebellum ; (2) the fibres proper {fibrae p-opriae) of the cere- 
 bellum itself. 
 
 Projection or Peduncular Fibres. — The medullary body, as it emerges from the 
 anterior cerebellar notch, is composed of projection fibres. These fibres are 
 continuous with the branches of the medullary body and constitute the arbor 
 vitae. The medullary body divides into a superior lamina and an inferior lamina, 
 and it also forms a portion of the fourth ventricle. The inferior lamina is the 
 inferior medullary velum, and its fibres reach the nodule and each flocculus. 
 The superior lamina forms the superior medullary velum and the cerebellar 
 peduncles. 
 
 The Peduncles of the Cerebellum (Figs. 599 and 600). — From the anterior part 
 of each hemisphere arise three large processes or peduncles — superior, middle, 
 and inferior peduncles — by which the cerebellum is connected with the rest of 
 the encephalon. 
 
 The Superior Cerebellar Peduncles or Crura ad Cerebrum (hrachia conjunctiva 
 cerebelli) form the upper lateral boundaries of the floor of the fourth ventricle. 
 As they extend forward and upward they converge on the dorsal aspect of the 
 ventricle, and thus assist in roofing it in. They may be traced as far as the corpora 
 quadrigemina, under which they pass. They enter the upper and mesial part of 
 
THE HIND -BRAIN 
 
 933 
 
 the medullary substance of the hemispheres, beneath the ala lobuli centralis and 
 the fraenulum, and pass to a great extent into the interior of the corpus dentatum, 
 though some of their fibres wind around it and reach the gray cortical matter, 
 especially of the inferior surface. 
 
 There are both afferent and efferent fibres in the superior peduncle, and the 
 fibres are in two bundles (Fig. 600) . The fibres to the cerebrum are axones of cells, 
 most of which are situated in the corpus dentatum, but some of the fibres to the 
 cerebrum come from the Purkinje cells of the cerebellar cortex, and probably 
 also a few come from the smaller nuclei in the central white substance. The 
 majority of the fibres decussate below the corpora quadrigemina, and pass to 
 the opposite red nucleus of the tegmentum, from which a relay is prolonged 
 through the optic thalamus to the cerebral cortex. The fibres of the second group 
 take origin in the opposite red nucleus and end in the corpus dentatum (Santee). 
 
 Fig. 599. — The peduncles of the cerebellum. On the left the three peduncles have been cut at their entrance 
 into the cerebellum; on the right side they are shown penetrating the cerebellar hemisphere. (Poirier and 
 Charpy.) 
 
 The Valve of Vieussens or Superior Medullary Velum (velum medullare 
 anierius) (Figs. 574, 584,604, and 606). — Stretched across from one superior cere- 
 bellar peduncle to the other is a thin, transparent lamina of white matter, the 
 valv« of Vieussens; on to the dorsal surface of its lower half the folia of the lingula 
 are prolonged. It helps to form with the superior peduncles the roof of the upper 
 part of the fourth ventricle, and is continuous with the central white stem of the 
 cerebellum. It is narrow above, where it passes beneath the corpora quadri- 
 gemina, and broader below, at its connection with the white substance of the 
 superior worm of the cerebellum. A slightly elevated ridge descends upon the 
 upper part of the valve from between the lower corpora quadrigemina, and on 
 either side of this may be seen the fourth nerve. The majority of the fibres of 
 the superior medullary velum are chiefly longitudinal fibres, passing between the 
 cerebrum and the worm of the cerebellum. What is known as the antero-lateral 
 ascending cerebellar tract of Gowers is said by Hoche to pass to the worm by way of 
 
934 
 
 THE NERVOUS SYSTEM 
 
 the superior velum. The velum also contains some commissural fibres and decus- 
 sating fibres of the roots of the fourth nerves. 
 
 The Middle Peduncles or Crura ad Posterior (brachia pontis) are the largest 
 of the three pairs. They consist of a mass of curved fibres, which, as already 
 described, pass to the pons and fovea, comprises most of the transverse fibres of 
 the pons. These tracts are both afferent and efferent, and the middle peduncle 
 emerges from the cerebellum at the anterior notch, between the margins of the 
 great horizontal fissure. The fibres of the middle peduncle (Fig. 600) rise from 
 
 
 Fig. 600. — Diagram showing the origin and course of the fibres of the peduncles of the cerebellum. 
 
 (Edinger.) 
 
 all portions of the cortex of the cerebellum. In the peduncle the fibres effect a 
 crossing, so that fibres from the anterior part of the hemisphere pass to the 
 posterior part of the pons, and fibres from the posterior portion of the hemisphere 
 pass to the anterior portion of the pons. The fibres approach the median line 
 and terminate on both sides of the raph^ in the nuclei pontis and the nuclei of 
 the formatio reticularis (Cajal). The balance of the fibres are "axones of cell- 
 bodies, situated mainly in the opposite nucleus pontis."^ These fibres "form a 
 segment in the indirect motor paths contained above the pons, in the medial 
 
 Anatomy of the Brain and Spinal Cord. By Harris E. Santee. 
 
THE HIND-BRAIN 
 
 935 
 
 and lateral fifths, and the intermediate bundle of the crusta. Collaterals from 
 both groups of fibres ascend and descend in the pons. They run upward with 
 both crustae, but chiefly with the opposite one; and they accompany the fillet 
 and posterior longitudfnal bundle of the same side to the nuclei of the third, 
 fourth, and sixth cranial nerves."^ 
 
 The Inferior Peduncles or Crura ad Medullam {corpora restiformia) connect the 
 cerebellum with the medulla oblongata. The fibres (Fig. 600) are both afferent 
 and efferent and begin in the gray cortex of the upper surface of the cerebellar 
 hemispheres and the worm. They descend in a direction downward and inward, 
 from part of the lateral walls of the fourth ventricle, reach the medulla, and 
 become the restiform bodies, which will be subsequently described (p. 941) . The 
 following are the chief sets of fibres in the inferior peduncles: 1. The direct 
 cerebellar tract, which takes origin in Clarke's column of the spinal cord and 
 terminates in the superior worm of the cerebellum. 2. The external arciform 
 fibres, which rise in the gracile and cuneate nuclei of the medulla and terminate 
 in the vermis superior. The posterior or uncrossed fibres terminate on the same 
 side, the anterior or crossed fibres on the opposite side. 3. The acustico-cerebellar 
 tract. These fibres originate from the nucleus of the auditory nerve in the floor of 
 the fourth ventricle, and terminate in the opposite nucleus fastigii and nucleus 
 globosus of the cerebellum. 4. Fibres which pass between the lateral nucleus of 
 the medulla oblongata and the corresponding side of the cerebellar cortex. 5. The 
 
 Punctated 
 
 molecular 
 
 layer. 
 
 Fig. 601. — Diagrammatic representation of the cells of the cerebellum. A. Molecular layer, 
 layer. C. White matter. (Modified from Foster's Physiology.) 
 
 B. Nuclear 
 
 descending cerebellar tract, which originates in the cerebellar cortex and which 
 passes down by way of the restiform body of the medulla and the antero-lateral 
 column of the spinal cord and reaches the anterior gray horn of the cord. 6. The 
 internal arciform fibres, which pass between the cerebellar cortex and the opposite 
 olivary body of the medulla (the cerebello -olivary tract). Santee emphasizes the 
 fact that most of the fibres which emerge from the cerebellum in the middle and 
 inferior peduncles are "axones of Purkinje's cells; they connect the cerebellum 
 with the motor nuclei of cranial and spinal nerves."^ 
 
 1 Anatomy of the Brain and Spinal Cord. By Harris E. Santee. 
 
 2 Ibid. 
 
936 THE NERVOUS SYSTEM 
 
 The Fibres Proper of the Cerebellum. — The fibrae propriae of the cerebellum are 
 of two kinds: (1) commissural fibres, which cross the middle line to connect the 
 opposite halves of the cerebellum, some at the anterior part and others at the 
 posterior part of the vermiform process; (2) association fibres, which are antero- 
 posterior fibres connecting adjacent laminae with each other. 
 
 The Gray Matter of the Cerebellum. — The gray matter of the cerebellum is found 
 in two situations: (1) on the surface, forming the cortex; (2) as independent masses 
 in the interior. 
 
 1. The Cortex of the Cerebellum (substantia corticalis) presents a characteristic 
 foliated appearance, due to the series of laminae which are given off from the 
 central white matter; these in their turn give off secondary laminae, which are 
 covered with gray matter. This arrangement gives to the cut surface of the organ 
 a foliated appearance (Fig. 598). Externally, the cortex is covered by pia matter; 
 internally, is the medullary centre, consisting mainly of nerve-fibres. 
 
 Microscopic Appearance of the Cortex (Figs. 601 and 602). — The cortex 
 presents a remarkable structure, consisting of two distinct layers — viz., an external 
 or superficial molecular layer, and an internal, deep, nuclear, rust-colored, or granular 
 layer. Between the two layers is an incomplete stratum of the characteristic cells 
 of the cerebellum, the corpuscles of Purkinje. 
 
 The external, superficial gray or molecular layer (Figs. 601 and 602) consists of 
 fibres and cells. The nerve-fibres are delicate fibrillae, and are derived from the fol- 
 lowing sources: (a) the dendrites and axone collaterals of Purkinje's cells; {b) fibres 
 from cells in the granular layer; (c) fibres from the central white substance of the 
 cerebellum; (c^) fibres derived from cells in the molecular layer itself. In addition 
 to these are other fibres, which have a vertical direction. These are the processes 
 of large glia-cells, situated in the granular layer. They pass outward to the 
 periphery of the gray matter, where they expand into little conical enlargements, 
 which form a sort of limiting membrane beneath the pia mater, analogous to the 
 membrana limitans interna in the retina, formed by the fibres of Miiller. 
 
 The cells of the molecular layer are small, and are arranged in two strata, an 
 outer and an inner. They all possess branching axis-cylinder processes; those of 
 the inner layer run for some distance horizontally, i. e., parallel with the surface of 
 the folia, giving off at intervals collaterals, which pass in a vertical direction 
 toward the cell-bodies of Purkinje's corpuscles, around which they become enlarged 
 and ramify like a basket. Hence these cells of the inner portion of the external 
 layer are named basket-cells (Fig. 601). 
 
 The cells or corpuscles of Purkinje (Fig. 602) are flask-shaped cells, situated at the 
 junction of the molecular and granular layers, their bases resting against the latter. 
 From the bottom of each flask one axis-cylinder process arises ; this passes through 
 the granular layer, and, becoming medullated, is continued as a nerve-fibre in 
 the medullary substance beneath. This axone gives off fine collaterals as it 
 passes through the granular layer, some of which run back into the molecular 
 layer. From the neck of the flask numerous dendrites are given off, which branch 
 in an antler-like manner in the molecular layer and terminate in free extremities. 
 
 The internal, rust-colored, nuclear or granular layer (Figs. 601 and 602) is charac- 
 terized by containing numerous small nerve-cells or granules of a reddish-brown 
 color, together with many nerve-fibrils. Most of the cells are nearly spherical and 
 provided with short dendrites, which spread out in a spider-like manner in the gran- 
 ular layer. Their axones pass outward into the molecular layer, and, bifurcating 
 at right angles, run horizontally for some distance. In the outer part of the gran- 
 ular layer are also to be observed some larger cells, of the type termed Golgi cells 
 (Fig. 601). Their axones undergo frequent division as soon as they leave the 
 nerve-cells, and pass into the granular layer, while their dendrites ramify chiefly 
 in the molecular layer. 
 
THE HIND-BMAIN 
 
 937 
 
 Finally, in the gray matter of the cerebellar cortex fibres are to be seen which 
 come from the white centre and penetrate the cortex. The cell origin of these 
 fibres is unknown, though it is believed that it is probably in the gray matter of 
 the spinal cord. Some of these fibres end in the granular layer, by dividing into 
 numerous branches, on which are to be seen peculiar moss-like appendages; hence 
 they have been termed by Ramon y Cajal the moss fibres (Fig. 601) ; they form 
 an arborescence around the cells of the granular layer. Other fibres derived 
 from the medullary centre can be traced into the molecular layer, where their 
 branches cling around the dendrites of Purkinje's cells, and hence they have been 
 named the clinging or tendril fibres (Fig. 601). 
 
 External gray or 
 cellular layer. 
 
 Corpuscles of PurMnje. 
 
 Intei-nal or rust- 
 colored layer. 
 
 — White substance. 
 
 Fig. 602. — Vertical section through the gray matter of the human cerebellum. Magnified about 100 diameters. 
 
 (Klein and Noble Smith.) 
 
 2. The Independent Centres of Gray Matter in the Cerebellum are four in number 
 on each side: one is of large size, and is known as the corpus dentatum; the other 
 three, much smaller, are situated near the middle of the cerebellum, and are known 
 as the nucleus emboliformis, nucleus globosus, and nucleus fastigii. 
 
 The corpus dentatum or ganglion of the cerebellum {nucleus dentatus) is a gray 
 nucleus situated a little to the inner side of the centre of the stem of the white 
 matter of the hemisphere. It consists of an irregularly folded lamina of a grayish- 
 yellow color, containing white fibres, and presenting on its antero-internal aspect 
 an opening, the hilum {hilus nuclei dentati), from which most of the fibres of the 
 
938 
 
 THE NERVOUS SYSTEM 
 
 superior cerebellar peduncle emerge. The nucleus emboliformis is a mass of gray 
 matter placed immediately to the inner side of the corpus dentatum, and partly 
 covering its hilum. The nucleus globosus is an elongated mass of gray matter, 
 directed antero-posteriorly, and placed to the inner side of the preceding. The 
 nucleus fastigii is somewhat larger than the other two, and is situated close to the 
 middle line at the anterior end of the superior vermiform process, and immediately 
 over the roof of the fourth ventricle, from which it is separated by a thin layer 
 of white matter. It is known as the roof nucleus of Stilling. 
 
 Weight of the Cerebellum. — Its average weight in the male is about 5 oz., 4 drs. 
 It attains its maximum weight between the twenty-fifth and fortieth years, its 
 increase in weight after the fourteenth year being relatively greater in the female 
 than in the male. The proportion between the cerebellum and cerebrum is, in the 
 male, as 1 to 83-, and in the female as 1 to 8. In the infant the cerebellum is 
 proportionately much smaller than in the adult, the relation between it and the 
 cerebrum being, according to Chaussier, between 1 to 13, and 1 to 26; by Cruveil- 
 hier, the proportion was found to be 1 to 20. 
 
 Middle 
 peduncle of 
 cerebellum. 
 
 V. The Medulla Oblongata (Myelencephaion) (Figs. 557, 594, 603, 604). 
 
 The medulla oblongata, known also as the spinal bulb, is the lowest division of 
 the encephalon, and is continuous with the spinal cord. It is, in fact, the intra- 
 cranial portion of the spinal cord. It is developed from the fifth cerebral vesicle, 
 the cavity of which forms the lower half of the fourth ventricle. It extends from 
 the lower margin of the pons Varolii to a plane passing transversely just below 
 the decussation of the pyramids, at which level the spinal cord commences. This 
 plane corresponds to the lower margin of the foramen magnum. The upper limit 
 
 of the medulla is marked off from the pons 
 Varolii on its ventral aspect by the abrupt 
 lower margin of the latter. 
 
 The medulla oblongata is directed from 
 above obliquely downward and backward; 
 its ventral surface rests on the basilar groove 
 of the occipital bone, while its dorsal surface 
 is received into the fossa between the hemi- 
 spheres of the cerebellum, and forms the 
 lower part of the floor of the fourth ventricle. 
 It is pyramidal in shape, its broad extremity 
 directed upward, its lower end being narrow 
 at its point of connection with the cord. It 
 measures an inch in length, three-quarters 
 of an inch in breadth at its widest part, and 
 half an inch in thickness. Its surface is 
 marked, in the median line, in front and be- 
 hind, by an anterior and a posterior median 
 fissure (fissura mediana anterior and fissura 
 mediana posterior), which are continuous with similar fissures on the anterior and 
 posterior surfaces of the cord, but neither one of them extends the entire length 
 of the bulb. The anterior fissure contains a fold of pia mater, and terminates just 
 below the pons in a cul-de-sac, the foramen caecum of Vicq d'Azyr. It is interrupted 
 at its lower part by some bundles of fibres, which cross obliquely from one side to 
 the other, forming the decussation of the p3n:amids (decussatio 'pyramidum) (Figs. 
 594 and 605) . The posterior fissure is a deep but narrow fissure, continued upward 
 to about the middle of the medulla. As it ascends its depth diminishes, and about 
 the middle of the posterior surface of the medulla the central canal of the cord 
 
 Fig. 603. — Medulla oblongata and pons Varolii. 
 Anterior surface. 
 
THE MEDULLA OBLONGATA 939 
 
 opens, and the lips of the shallow posterior fissure diverge and bound the triangular 
 opening, which is the lower portion of the floor of the fourth ventricle (Figs. 604 
 and 606). As the lower half of the medulla contains the central canal of the cord, 
 it is called the closed portion; the upper half of the medulla is above the opening 
 of the central canal and is called the open portion. 
 
 These two fissures divide the medulla into two symmetrical halves, each half 
 presenting elongated eminences, which are continuous with the columns of the cord. 
 By taking the lines along which some of the cranial nerves emerge from the 
 medulla as landmarks, the surface of this portion of the nervous system may be 
 divided into three columns, in the same way as the spinal cord is divided into three 
 columns by the lines corresponding to the points of exit of the anterior and poste- 
 rior roots of the spinal nerves. The hjrpoglossal nerve-roots arise from a furrow 
 on the antero-lateral surface of the medulla, which is known as the antero-lateral 
 furrow, or the ventro-lateral groove {sulcus lateralis anterior). There is no furrow 
 on the cord corresponding with this medullary furrow. The roots of the glosso- 
 pharyngeal and pnemnogastric nerves and the accessory root of the spinal accessory 
 nerve lie in a furrow upon the postero-lateral surface of the medulla. This furrow 
 is called the postero-lateral furrow or dorso-lateral groove (sulcus lateralis posterior). 
 This groove is the continuation of the postero-lateral fissure of the cord. It is not 
 straight, but turns forward as it ascends. At the termination of this groove ante- 
 riorly the seventh and eighth cranial nerves emerge. At the lower portion of the 
 medulla the groove ceases for a short distance as the direct cerebellar tract passes 
 from the lateral to the posterior surface of the bulb. The anterior column com- 
 prises that portion which is situated between the anterior median fissure and the 
 antero-lateral furrow; this column is called the anterior pyramid or simply the 
 pyramid (Fig. 603). The lateral column comprises that portion which is situated 
 between the antero-lateral and the postero-lateral furrows. In the lower part 
 of the medulla this column is single, and is called the lateral tract; but in the 
 upper part an oval -shaped body comes forward between it and the pyramid, and 
 pushes aside the lateral tract. This is called the olivary body (Fig. 603) The 
 posterior column (Fig. 604) comprises that portion which is situated between the 
 postero-lateral furrow and the posterior median fissure. It is marked by slight 
 furrows dividing it into smaller columns, and these in the lower part of the 
 medulla are named, from without inward, the fasciculus of Rolando, the fasciculus 
 cuneatus and the fasciculus gracilis; in the upper part of the medulla, the fasciculus 
 of Rolando and the fasciculus cuneatus appear to become fused together and seem 
 to form the single body, called the restiform body (Fig. 604). As a matter of fact 
 the restiform body is not so formed (p. 941) . 
 
 The Pyramid (pyramis medullae oblongatae) (Figs. 594 and 603). — The 
 pyramid is a pyramidal bundle of white matter. A pyramid is placed one 
 on either side of the anterior median fissure, and separated from the olivary 
 body by a slight depression, from which the roots of the hypoglossal nerve 
 emerge (antero-lateral furrow). At the lower border of the pons these bodies 
 are somewhat constricted and are here crossed by a band of arched fibres, 
 the ponticulus of Arnold; below this they become enlarged, and then taper as 
 they descend to their lower extremity. The fibres of which compose these 
 pyramids may be arranged in two bundles: an outer, continuous below with 
 the direct or uncrossed pyramidal tract of the anterior column of the same 
 side of the spinal cord, and an inner, continuous with the crossed pjnramidal tract 
 of the lateral column of the opposite side of the cord (Fig. 605). As will be 
 subsequently mentioned, the direct pyramidal tract in the cord lies next to the 
 anterior median fissure, but as the crossed pyramidal tract of the cord ascends to 
 the medulla it decussates with its fellow of the opposite side across the anterior 
 median fissure, and so displaces laterally the direct pyramidal tract, and ascends, 
 
940 
 
 THE NERVOUS SYSTE3f 
 
 after decussation, through the medulla to its inner or mesial side. This decussa- 
 tion is usually spoken of as the decussation of the pyramids (Figs. 594 and 605), 
 but it must be borne in mind that it is only a portion of the fibres of the 
 pyramid (90 percent, of them) which decussate ; namely, those derived from the 
 crossed pyramidal tract of the cord; the outermost fibres, derived from the anterior 
 column of the cord, do not decussate. Each pyramid enters the substance of the 
 pons in one bundle, and maybe traced through it, after breaking up into several 
 smaller fasciculi, into the corresponding crus cerebri. 
 
 PONS _,, 
 
 !*ife!3 
 
 
 Restiform body, 
 
 Clava. 
 
 Cuneate tubercle. 
 
 LONGITUDINAL 
 ■COMMISSURAL 
 
 VENTRAL PLANE 
 OF OBLONGATA 
 MIDDLE PLANE 
 OF OBLONGATA 
 DORSAL PLANE 
 OF OBLONGATA 
 
 Fig. 604.- 
 
 -Posterior surface of the medulla 
 oblongata. 
 
 Fig. 605. — Diagram to show the crossing of the pyramids 
 (red) and of the lemniscus (blue). (Testut.) 
 
 The Lateral Column or Lateral Area. — The lateral column or area is 
 between the antero-lateral and postero-lateral furrows. In the lower part of 
 the medulla it is of the same width as the lateral column of the cord, and 
 appears on the surface to be a direct continuation of it. As a matter of fact it is 
 only a part of the lateral column of the spinal cord which is continued upward into 
 this column; for the crossed pyramidal tract passes into the pyramid of the oppo- 
 site side, and the direct cerebellar tract of the lateral column of the cord passes into 
 the restiform body. The rest of the lateral column of the cord, that is to say, the 
 antero-lateral ground bundle (fasciculus proprius anterolateralis) and the antero- 
 lateral cerebellar tract (fasciculus anterolateralis super ficialis) , can be traced 
 
THE MEDULLA OBLONGATA • 941 
 
 upward into this area. In the upper part of the medulla, the lateral tract, on 
 account of the interpolation of the olivary body, becomes almost concealed by 
 this body. 
 
 The Oiive, Olivary Body or Olivary Eminence {oliva) (Figs. 586, 589, and 603). 
 — The olivary body or eminence is a prominent oval mass, bulging from the 
 upper part of the lateral column of the medulla. It is situated on the outer side 
 of the pyramid, from which it is separated by the slight groove, along which 
 the fibres of the hypoglossal nerve emerge. It is separated externally from the 
 restiform body by a longitudinal, narrow band of fibres, prolonged upward from 
 the lateral tract, and by the groove, from which the glosso-pharyngeal, pneu- 
 mogastric, and spinal accessory nerves arise. It is equal in breadth to the 
 pyramid; it is broader above than below, and is about half an inch in length, 
 being separated above from the pons Varolii by a slight depression, in which a 
 band of arched fibres is sometimes to be seen. Numerous white fibres, superficial 
 or external arciform or arcuate fibres (Fig. 607) , are seen winding across the lower 
 half of the pyramid and the olivary body to enter the restiform body. The 
 olivary body is formed by the olivary nucleus of the medulla (Fig. 607), a lamina 
 of gray matter, the surface of which is covered by a very thin layer of white 
 matter. 
 
 The Funiculus or Fasciculus of Rolando {fasciculus lateralis) (Fig. 604). — The 
 fasciculus of Rolando is a longitudinal prominence on the outer side of the lateral 
 tract. It begins at the lower end of the medulla by a tapering extremity, and has, 
 apparently, no corresponding column in the cord. It gradually enlarges as it 
 ascends, and forms, at a level with the lower border of the olivary body, a consid- 
 erable prominence, known as the tubercle of Rolando (tuberculum Rolandi) (Fig. 
 607). This is caused by the substantia gelatinosa of Rolando of the cord gradually 
 finding its way to the surface, so as to form a prominence there. About half an 
 inch below the pons the fasciculus of Rolando appears to blend with the fasciculus 
 cuneatus. In front, it is separated from the lateral tract by a distinct groove, the 
 continuation upward of the postero-lateral groove of the cord; behind, the 
 separation from the fasciculus cuneatus is much less distinct. 
 
 The Wedge-shaped or Guneate Funiculus or the Fasciculus Cuneatus (Fig. 
 604) is the direct continuation upward of the postero-lateral column (tract of 
 Burdach) of the cord. It is situated between the fasciculus of Rolando and the fas- 
 ciculus gracilis. It enlarges as it ascends, and forms, opposite the lower extremity 
 of the fourth ventricle, a slight eminence or enlargement, the cuneate tubercle 
 (tuberculum cuneatum) (Fig. 604), which is marked only in children. Above this 
 point it disappears from the surface. 
 
 The Slender Funiculus or the Fasciculus Gracilis (Fig. 604) is the direct 
 continuation upward of the postero-median column of the cord (tract of Goll). It 
 is a narrow white band, placed parallel to and along the side of the posterior 
 median fissure. It is separated from the fasciculus cuneatus by a slight groove, 
 continuous with that on the surface of the cord, which marks off the postero- 
 median column. At first the fasciculi of the two sides lie in close contact on 
 either side of the posterior median fissure. Opposite the apex of the fourth 
 ventricle each presents an enlargement, the clava (Fig. 604) ; they then diverge 
 and form the lateral boundaries of the lower part of the fourth ventricle, and 
 gradually tapering off become no longer traceable. The surface prominence 
 of the fasciculus gracilis is formed by the gray nucleus beneath. This nucleus 
 is known as the nucleus fasciculi gracilis. 
 
 The Restiform Body (corpus restijorme) (Fig. 604). — The upper part 
 of the posterior area of the medulla is occupied by the restiform body. It 
 appears, at first sight, as if this body were the direct continuation upward of 
 the fasciculus cuneatus and the fasciculus of Rolando, and it was formerly 
 
942 THE NERVOUS SYSTEM 
 
 described as such. This, however, is not so, for the restiform body is largely 
 formed by a set of fibres, the superficial or external arcifonn or arcuate fibres 
 (Fig. 607), which issue from the anterior median fissure and will presently be 
 described. They pass laterally over the pyramid and olive, and assist in form- 
 ing the restiform body. There is also a narrow strand of fibres, derived from 
 the lateral column of the cord, the direct cerebellar tract (fasciculus cerebello- 
 spinalis), which joins the above-mentioned arcuate fibres. These two sets of 
 fibres, reinforced by the internal arcuate fibres from the opposite side of the 
 medulla, form the restiform body. 
 
 The restiform bodies are the largest prominences of the medulla, and are 
 placed between the lateral tracts in front and the fasciculus cuneatus behind, from 
 both of which they are separated by slight grooves. As they ascend they diverge 
 from each other, assist in forming the lower part of the lateral boundaries of the 
 fourth ventricle, and then enter the corresponding hemisphere of the cerebellum, 
 forming its inferior peduncles. 
 
 The Posterior Surface of the Medulla Oblongata (fades posterius) (Fig. 
 604) . — The posterior surface of the medulla oblongata forms part of the floor of 
 the fourth ventricle (Fig. 606). This portion is of a triangular form, bounded 
 on each side by the diverging fasciculi graciles and cuneati and restiform bodies. 
 The divergence of these two fasciculi and of the restiform bodies, together with the 
 opening out of the posterior fissure and central canal of the spinal cord, displays 
 in the floor of the ventricle the gray matter of the medulla, which is continuous 
 below with the gray matter of the cord. In the middle line is seen a longitudinal 
 furrow, which divides this part of the ventricle into right and left halves, and is 
 continuous below with the central canal of the cord. 
 
 The Arciform or Arcuate Fibres (Fig. 607) . — The arciform or arcuate fibres, which 
 have been mentioned as forming part of the restiform body, are found in the upper 
 half of the medulla, crossing its surface and also traversing its substance. They 
 are divided for purposes of description into two sets — external and internal. The 
 external or superficial arciform or arcuate fibres (fibrae arcuatae externae) have already 
 been alluded to as crossing the pyramid and olivary body on each side. They 
 emerge from the anterior median fissure, and if traced into it are found to enter 
 the raph^ and cross to the opposite side, after which their further course is a matter 
 of some doubt. After emerging from the anterior median fissure they cross the 
 pyramid and olivary body, often concealing from view the upper part of the 
 cuneate and Rolandic fasciculi, and enter the restiform body. Kb they cross the 
 olivary body they are reinforced by some of the internal arciform fibres, which 
 come to the surface on the inner side of, or through, this structure. The internal 
 arciform or arcuate fibres (fibrae arcuatae internae) are described with the microscopic 
 anatomy of the medulla. 
 
 It is advisable, at this stage, to take up the consideration of the cavity of the 
 fourth ventricle, an acquaintance with which will render the description of the 
 internal structure of the medulla oblongata more intelligible. 
 
 The Fourth Ventricle (Ventriculus Quartus) (Fig. 606). 
 
 The fourth ventricle is the cavity common to the metencephalon, and the myel- 
 encephalon is in the pons and medulla oblongata and is anterior or ventral to the 
 cerebellimi. It is lozenge- or diamond-shaped ; that is to say, it is composed of two 
 triangles, with their bases in contact. The sides of the lower triangle are formed 
 by the divergence of the fasciculi graciles, fasciculi cuneati, and restiform bodies 
 of the medulla on either side. As these columns pass upward in the medulla they 
 turn outward from the median line, and, diverging from each other, form the 
 lateral boundaries of the lower half of the fourth ventricle. In like manner the 
 
THE FOURTH VENTRICLE 943 
 
 sides of the upper triangle are formed by the convergence of the superior peduncles 
 of the cerebellum. These peduncles are separated below by a somewhat wide 
 interval, but as they pass upward and forward toward the corpora quadrigemina 
 they gradually converge and ultimately come into contact with each other. This 
 cavity is therefore bounded laterally on each side by the superior peduncle of the 
 cerebellum in its upper half, and by the fasciculus gracilis, the fasciculus cuneatus, 
 and the restiform body in its lower half. It presents four angles. The upper 
 angle reaches as high as the upper border of the pons, and corresponds with the 
 lower opening of the aqueduct of Sylvius, by which this ventricle communicates 
 with the third ventricle (Fig. 587). The lower angle is on a level with the lower 
 border of the olivary body, and is continuous with the central canal of the spinal 
 cord. From the resemblance that it bears to the point of a writing pen it has been 
 named the calamus scriptorius. Its lateral angles extend for some distance between 
 the medulla and the cerebellum, each forming a pointed lateral recess. 
 
 The Roof or Posterior Wall of the Fourth Ventricle.— The roof of the fourth 
 ventricle is formed from above downward by the following structures: a part of 
 the superior peduncles of the cerebellum, the anterior or superior medullary velum, 
 the posterior or inferior medullary velum, the tela chorioidea inferior, the obex, and 
 the lingula. The superior half of the roof meets the inferior half at an acute angle 
 to form the tent of the fourth ventricle (fastigium). 
 
 The Superior Peduncles of the Cerebellum {brachia conjunctiva cerebelli) (Figs. 
 557, 598, 599, 604, and 606). — The superior peduncles of the cerebellum, when 
 they emerge from the medullary substance of its hemispheres, pass upward and 
 forward, forming the lateral boundaries of the upper half of the fourth ventricle, 
 but, converging as they approach the corpora quadrigemina, the mesial portions 
 of the peduncles form a part of the roof of the cavity, in consequence of the ven- 
 tricle extending to a slight extent underneath the peduncles. 
 
 The Anterior or Superior Medullary Velum (Valve of Vieussens) (velum medullare 
 anterius) (Figs. 584, 596, 605, and 606). — In the angular interval left between the 
 two superior peduncles is a thin lamina of white matter, continuous with the white 
 centre of the cerebellum, which bridges across from one peduncle to the other, 
 and so completes the roof of the superior part of the ventricle. This is the superior 
 medullary velum or valve of Vieussens. Its dorsal surface is covered by the folia 
 of the lingula, already described (p. 928). 
 
 The Posterior or Inferior Medullary Velum {velum medullare posterius). — The pos- 
 terior or inferior medullary velum is a thin layer of white substance, prolonged 
 from the white centre of the medulla on either side of the nodule, which assists in 
 forming a part of the roof of the fourth ventricle, stretching over it toward its 
 lateral angles. It is continuous with the white substance of the cerebellum by 
 its convex edge, while its thin concave margin is apparently free. In reality, 
 however, it is continuous with the epithelium of the ventricle, which is prolonged 
 downward from the velum to the edge of the lingula. 
 
 The Tela Chorioidea Inferior (tela chorioidea ventriculi quarti) . — The tela chorioidea 
 inferior is a layer of pia mater which covers in the lower part of the fourth ventricle 
 below the inferior medullary velum. Superiorly it is reflected on to the under 
 surface of the cerebellum, while inferiorly it is continued on to the restiform bodies 
 and lower part of the medulla. This part of the roof of the ventricle contains no 
 nervous matter, but consists merely of the ventricular epithelium covered by pia 
 mater. The tela chorioidea inferior, like the velum interpositum or tela chorioidea 
 superior (p. 855), really consists of two layers, which become more or less adherent, 
 viz., that covering the under surface of the cerebellum and that covering the epithe- 
 lium. It also possesses on each side a choroid plexus (plexus chorioideus ventriculi 
 ^war/i), which projects into the ventricular cavity invaginating before it the epithelial 
 lining. Each plexus consists of a vertical portion which extends forward, near the 
 
944 
 
 THE NERVOUS SYSTEM 
 
 middle line, from the foramen of Majendie, and of a transverse fart, which passes 
 outward into the lateral recess of the ventricle as far as the foramina of Key and 
 Retzius. The two plexuses present the form of a T, the vertical limb of which is, 
 however, double, || . The tela does not form a complete membrane, for in it 
 there are three openings: one in the middle line at the inferior angle of the ven- 
 tricle, just above the position of the opening of the central canal of the cord; this 
 is the foramen of Majendie (apertura medialis ventriculi quarti) ; the other two are 
 at the right and left extremities of the lateral recesses of the ventricle, and each is 
 named the foramen of Key and Retzius {apertura lateralis ventriculi quarti) (see 
 pp. 852 and 853). Through these foramina the ventricles of the brain commu- 
 nicate with the subarachnoid space. 
 
 The Obex. — The obex is a thin, triangular lamina of gray matter, continuous 
 below with the anterior gray commissure of the cord, which fills in the angle 
 between the two diverging fasciculi graciles for a short distance. 
 
 The Ligula. — The ligula {taenia ventriculi quarti) are narrow bands of white 
 matter, which project from the internal border of the funiculi graciles. They at 
 first run upward and forward, and then turn outward over the restiform bodies, 
 as far as the lateral recesses of the ventricle. Their inner borders are continuous 
 with the epithelial roof of the ventricle. 
 
 The Floor or Anterior Wall of the Fourth Ventricle (jossa rhomboidea) 
 (Figs. 599, 604, and 606). — The floor of the fourth ventricle is rhomboidal in shape, 
 
 Corpora qiiadrigemina. 
 
 (Superior peduncle 
 of cerebellum. 
 
 Locus cseruleus. 
 Fovea superior. 
 
 I^gonum hypogloasi, 
 
 Ala cinerea 
 
 Valve of Vieussens, 
 
 Fasciculus teres. 
 
 Conductor sonorus. 
 Strix acusticse. 
 
 Tr'igonum acustici. 
 Clava. 
 
 Tuberculiim cuneaium. 
 Lateral column. 
 
 Fig. 606. — Floor of the fourth ventricle. Diagrammatic. 
 
 and is traversed by a vertical median fissure {sidcus longitudinalis fossae rhom- 
 boideae), which below is continuous with the central canal of the spinal cord. At 
 the junction of the fourth ventricle with the central canal of the cord is a dilata- 
 tion or ampulla called the ventricle of Arantius. At the widest part of the fourth 
 ventricle, opposite the level of the lateral recesses, it is marked by some trans- 
 verse white lines, the striae medullares or striae acusticae. These consist of white 
 fibres, which emerge from the longitudinal sulcus, and pass outAvard across the 
 floor of the ventricle. Most of the striae acusticae take origin from cochlear 
 nucleus, but some arise from the cochlear root. Most of them pass to the trape- 
 
INTERNAL STBUCTUBE OF THE MEDULLA OBLONGATA 945 
 
 zium and lateral fillet of the opposite side, but some become external arciform 
 fibres (Koelliker). These striae divide the floor of the ventricle into two triangles, 
 inferior and superior. 
 
 The Inferior Triangle (Fig. 606). — The inferior triangle, or lower or posterior 
 half of the floor, presents above an angular groove, the fovea inferior, the apex of 
 which is at the striae, while the two limbs diverge below, and form the sides of a 
 triangular dark area, termed the ala cinerea, which becomes elevated into a promi- 
 nence below (eminentia cinerea). This area corresponds with the nuclei of the 
 vagus and glosso-pharyngeal nerves, and is therefore termed the trigonum vagi. 
 A second triangular area lies between the inner limb of the fovea and the median 
 sulcus ; its base is directed upward, and limited by the striae medullaris. It is 
 termed the trigonum n. hypoglossi, because it corresponds in position to the tract of 
 nerve-cells from which the hypoglossal nerve takes origin. A third triangular area 
 to the outer side of the fovea inferior is named the trigonum acustici (area acuMica). 
 It lies between the groove forming the outer boundary of the fovea inferior and 
 the lateral wall of the ventricle, and, like the trigonum hypoglossi, has its base 
 directed upward. Here it is continuous with a prominence, the tuberculum acusti- 
 cum, which extenfls into the anterior part of the floor of the ventricle. 
 
 The Superior Triangle (Fig. 606) . — The superior triangle or upper or anterior 
 half of the floor of the fourth ventricle, i. e., the part above the striae medullaris, 
 presents in the middle line the continuation of the median longitudinal sulcus. 
 On either side of this is a spindle-shaped longitudinal eminence, prominent in its 
 centre, but less so above and below. This is the eminentia teres or fasciculus 
 teres (colliculus facialis), and is produced by an underlying bundle of white fibres, 
 the fasciculus teres (eminentia medialis), formed, in part at all events, by the fibres 
 of the facial nerve. Immediately above and to the outer side of the eminentia 
 teres is an angular depression, the fovea superior; this is sometimes crossed by 
 a whitish band of fibres, the conductor sonorus, which is connected below with 
 the striae meduUares of the same side. Above the fovea is a bluish depressed 
 area, the locus caeruleus. Its color is due to some pigmented nerve-cells, showing 
 through the white covering of the floor. These pigmented cells are named the 
 substantia ferruginea, and in them one of the roots of the fifth nerve terminates. 
 
 The Lining Membrane. — The lining membrane of the fourth ventricle is con- 
 tinuous above with that of the third ventricle, through the aqueduct of Sylvius 
 (p. 912), and below with that of the central canal of the spinal cord. The cavity 
 of the ventricle communicates below with the subarachnoidean space by means 
 of the foramen of Majendie and the foramina of Key and Retzius, already 
 described. 
 
 The Internal Structure of the Medulla Oblongata (Figs. 607, 608, 609, 610, 611, 612). 
 
 If the cranial nerves emerging from the medulla are traced into its substance, 
 it will be seen that they divide each half of the bulb into three wedge-shaped areas, 
 which are named the anterior, lateral, and posterior areas of the medulla, and each 
 of which corresponds to one of the subdivisions already described on the surface 
 of this portion of the encephalon. 
 
 The Anterior Area. — The anterior area comprises that portion which is situ- 
 ated between the anterior median fissure and the fibres of superficial origin of the 
 hypoglossal nerve. On the surface of the medulla this area corresponds to the 
 pyramid (Fig. 607). 
 
 The Lateral Area. — The lateral area is situated between the fibres of super- 
 ficial origin of the hypoglossal nerve on the one hand, and the fibres of superficial 
 origin of the glosso-pharyngeal pneumogastric and spinal accessory nerves on the 
 other. On the surface of the medulla, in its lower part, this area is single, and is 
 
 60 
 
946 
 
 THE NERVOUS SYSTEM 
 
 called the lateral tract; but in the upper part an oval-shaped body, the olivary 
 body, comes forward between it and the pyramid, pushing aside the lateral tract 
 (Fig. 607). 
 
 The Posterior Area. — The posterior area comprises that portion which is situ- 
 ated between the fibres of superficial origin of the glosso-pharyngeal, pneumogas- 
 tric, and spinal accessory nerves, and the posterior median fissure. On the surface 
 of the medulla this area is marked by slight furrows, splitting it up into smaller 
 columns; those in the lower part of the medulla are named, from without inward, 
 the fasciculus of Rolando, the fasciculus cuneatus, and the fasciculus gracilis; in 
 the upper part of the medulla they are replaced by the restiform body. Finally, 
 the halves of the medulla are separated from each other by a median septum or 
 raph^ (Fig. 607). 
 
 Vagus nuclei. ^'ff"'"' Z"'"''^''^''' ^^'^'^• 
 Nucleus of^ypooiossal /\ ,- J_ / Nucleus gracilis, 
 fasciculus teres, nucleus. 
 
 ' ' ' ■''«*'■ ~^^ "^ Nucleus cuneatus. 
 
 Nucleus ambig. 
 
 Raphe- 
 Formatio reticularis 
 
 Continuation of antero- 
 lateral ground-bundle 
 
 AccessoiT/ olivary nuclei 
 
 Gorpus restiforme. 
 
 Nucleus or 
 tubercle of 
 Rolando. 
 -Ascending root of 
 fifth nerve. 
 
 Vagus root. 
 
 -Arciform fibres. 
 ■^Nucleus lateralis. 
 
 ivary nucleus. 
 
 Hyi'oglossal nerve. 
 Nucleus of ext. arc. fibres. 
 "External arciform fibres. 
 Anterior median fitssurc 
 
 Fig. 607. — Section of the medulla oblongata at about the middle of the olivary body. 
 
 (Schwalbe.) 
 
 Each of these three areas is made up of gray and white matter. The gray 
 matter is derived for the most part from that of the cord. In like manner the 
 white matter is partly made up of longitudinal fibres continuous with those of 
 the cord, and partly of transverse fibres which intersect them. 
 
 In order to understand the internal structure of the medulla, it is necessary to 
 describe the appearances as they are seen in the upper and lower portions of the 
 medulla, since they differ considerably in these two parts. 
 
 The Lower Part of the Medulla (Figs. 608 and 609).— The first change 
 in the internal structure is caused by the passage of the fibres of the crossed 
 pyramidal tract obliquely through the gray matter of the anterior horn. As 
 stated above, the pyramid is composed of fibres derived from the direct 
 pyramidal tract of the anterior column of the cord of the same side, and 
 from the crossed pyramidal tract of the lateral column of the opposite half 
 of the cord. Those fibres which are derived from the direct pyramidal tract 
 and which in the cord lie close to the median fissure are in the medulla 
 placed to the outer side of the pyramid, being pushed aside, as it were, by 
 the interpolation of the fibres derived from the crossed pyramidal tract, which 
 
INTERNAL STRUCTURE OF THE MEDULLA OBLONGATA 947 
 
 are much more numerous. The crossed pyramidal fibres ascend from the lat- 
 eral column of the spinal cord, and, passing through the anterior gray cornu 
 and across the middle line, form the inner part of the pyramid. In consequence 
 of this passage of white fibres through its substance the anterior gray cornu 
 is broken up into a coarse network, while one portion of it, the caput cornu, is 
 entirely separated from the rest; only the base of the cornu remains intact, close 
 to the ventrolateral aspect of the central canal. The caput cornu, thus separated, 
 is displaced laterally, and comes to lie close to the caput cornu posterioris, which 
 
 DOnSO-MEOIAN 
 FISSURE 
 
 DORSO-LATEHAU 
 COLUMN 
 
 DORSO-MEDIAN 
 FISSURE 
 
 CROSSED PYRAM- 
 IDAL TRACT 
 
 VENTRAL^' 
 ROOTS 
 
 VENTRAL MEDIAN 
 FISSURE 
 
 Fig. 608. — Transverse section of the oblongata at its 
 lower end. (Testut.) 
 
 MOTOR 
 ROOTS 
 
 VENTRO-MEDIAN 
 FISSURE 
 
 Fig. 609. — Transverse section of the oblon- 
 gata at the decussation of the pyramids. 
 (Testut, after Duval.) 
 
 has also shifted its position. In consequence of this breaking up of the greater 
 part of the anterior gray cornu by white fibres a coarse network is formed in the 
 anterior and lateral areas of the medulla, which is named the formatio reticularis 
 (Fig. 607). 
 
 The posterior cornu also undergoes somewhat similar changes. It becomes 
 subdivided by the passage through it of the sensory fibres of the columns of Goll 
 and Burdach. These pass across to the opposite anterior area of the medulla, 
 where they are seen to lie immediately on the dorsal aspect of the pyramids. In 
 
 NUCLEUS 
 
 QRACILIS 
 
 ^MEATUS j DORSOMEOiAn 
 
 -HEAD OF DORSAL HORN 
 BASE OF VENTRAL HORN 
 EAD OF VENTRAL HORN 
 
 Fio. 610. — Transverse section of the oblongata at the crossing of the fillets. (Testut.) 
 
 their passage through the posterior horns of gray matter the latter become sub- 
 divided, in a manner somewhat similar to what has been seen to occur in the 
 anterior horns. This crossing of the sensory fibres is termed the superior pyram- 
 idal or sensory decussation (Fig. 605). The caput cornu is displaced outward, so 
 as almost to reach the surface, where it forms a projection, the fasciculus of Rolando, 
 which enlarges above into a distinct prominence, the tubercle of Rolando (Fig. 607). 
 Above the level of the tubercle of Rolando the caput cornu is separated from 
 
948 
 
 THE NERVOUS /SYSTEM 
 
 the surface by a band of fibres termed the ascending root of the fifth nerve (tradus 
 spinalis n. trigemini) and by the external arcuate fibres (Fig. 607). The neck 
 of the cornu becomes broken up into a reticular formation by the decussation of 
 the columns of GoU and Burdach, and by this means the caput is separated from 
 the rest of the gray matter. The base of the cornu increases in size, and, as the 
 central canal expands into the fourth ventricle, becomes pushed outward, and 
 portions of it extend into the fasciculus graciles and cuneati, and produce exter- 
 nally the eminences of the clava and cuneate tubercle. A third portion of the 
 base becomes separated from the rest, and is placed outside the nucleus of the 
 fasciculus cuneatus. This is called the accessory cuneate nucleus, and is supposed 
 to be a continuation upward of Clarke's vesicular column of the cord. 
 
 The Upper Part of the Medulla (Figs. 607,611, and 612).— The upper part 
 of the medulla comprises the portion which enters into the formation of the 
 
 FLOOR OF FOURTH VENTRICLE 
 
 NUCLEUS GRACILIS 
 
 NUCLEUS CUNEATUS 
 
 BASE OF VENTRAL HORN 
 ROOT OF TRIFACIAL CAPPING 
 HEAD OF DORSAL HORN 
 
 VAGUS NERVE 
 
 HEAD OF VENTRAL HORN 
 
 HYPOGLOSSAL NERVE 
 
 LEIMNISCUS VENTRAL PYRAMID 
 
 Fig. 611. — Transverse section of the oblongata at the lower end of the olives. The roof of the fourth 
 ventricle is not represented. (Testut, after Duval.) 
 
 floor of the fourth ventricle, where, in fact, the upper end of the central canal 
 has opened out into this cavity. In this region the formatio reticularis is con- 
 fined chiefly to the anterior and lateral areas. In the ventral portion of the pos- 
 terior area there is only a small amount of reticular formation, but in addition to 
 this there are individual masses of cells scattered among the longitudinal fibres. 
 
 HYPOGLOSSAL 
 r«..™ NUCLEUS 
 
 qqB of_foubth ventbicle 
 
 SENSORY NUCLEUS 
 
 NUCLEUS CUNEATUS 
 
 HEAD OF DORSAL HORN 
 ROOT OF TRIFACIAL NERVE 
 
 MOTOR NUCLEUS OF MIXED 
 
 NERVES 
 
 ACCESSORY HYPOGLOSSAL 
 
 NUCLEUS 
 
 OLIVE 
 
 HYPOGLOSSAL NERVE 
 
 LEMNISCUS VENTROMEDI 
 FISSURE 
 
 ARCIFORM 
 NUCLEUS 
 
 Fig. 612. — Transverse section of the oblongata at the middle of the olives. The roof ol the fourth ventricle 
 is not represented. (Testut, after Duval.) 
 
 The Formatio Reticularis (Fig. 607). — The formatio reticularis is a network 
 of white matter in the deep portion of the medulla, the network containing 
 
INTERNAL STBUCTUBE OF THE MEDULLA OBLONGATA 949 
 
 gray matter. It is situated behind the pyramid and ohvary body, extending 
 laterally as far as the restiform bodies, and dorsally to within a short distance 
 of the floor of the fourth ventricle. It presents a peculiar reticulated appear- 
 ance, from which it derives its name, and which is due to the intersection of 
 bundles of fibres running at right angles to each other, some being longitudinal, 
 others transverse. The formatio reticularis presents a different appearance in 
 the anterior area from what it does in the lateral area. In the former there is 
 almost an entire absence of nerve-cells in the reticulated network, and hence it 
 is known as the formatio reticularis alba; whereas, in the lateral area, the nerve- 
 cells are numerous, and, as a consequence, this part is known as the formatio 
 reticularis grisea. In the substance of the formatio reticularis is a small nucleus 
 of gray matter. It is situated near the dorsal aspect of the hilum of the olivary 
 nucleus, and has been named the inferior central nucleus. The formatio reticu- 
 laris contains both longitudinal and transverse fibres. In the anterior area 
 the longitudinal fibres may be arranged in two well-defined sets: (1) One set 
 lies immediately behind the pyramid, and is named the interolivary fillet or 
 lemniscus {lemniscus interolivaris) (Fig. 610). The fibres of the fillet are chiefly 
 derived from the cells of the gracile and cuneate nuclei (Fig. 607), and may 
 therefore be regarded as relay fibres of the columns of Goll and Burdach of 
 the spinal cord, which terminate in synapses around the cells of the gracile and 
 cuneate nuclei. They are prolonged inward and forward across the middle line 
 forming the superior pyramidal or sensory decussation or the decussation of the 
 fillet (Fig. 605). (2) The other set is continuous from the antero-lateral ground 
 bundle of the cord, and a portion of these fibres forms the posterior longitu- 
 dinal bundle {fasciculus longitudinalis medialis), already referred to (p. 908). 
 Both these sets of fibres are continued upward into the pons and mid-brain. 
 The longitudinal fibres of the reticular formation in the lateral area are not 
 arranged in distinct bundles. They are derived from the lateral column of the 
 cord, after the crossed pyramidal tract has passed over to the opposite side. 
 The longitudinal fibres of the posterior area are merely indeterminate fibres of 
 the formatio reticularis, with the exception of two distinct bundles, which may 
 be regarded as ascending roots of the fifth nerve (Fig. 607) and vago-glosso- 
 pharyngeal nerves; the latter is termed the fasciculus solitarius (Fig. 607). 
 
 The Transverse Fibres of the reticular formation are the arched or arcuate fibres. 
 The external arciform or arcuate fibres have already been described. The internal arci- 
 form or arcuate fibres (fihrae arcuatae internae) are more numerous than the super- 
 ficial set; they traverse nearly the whole area of the upper half of the medulla, except 
 the pyramid. They pass from the raphe; some become superficial and join the 
 external arciform fibres, while others remain deep and pass to the olivary body, the 
 restiform body, and to the nuclei of the fasciculus cuneatus and fasciculus gracilis. 
 
 Independent Nuclei (Fig. 613). — In the upper part of the medulla are several 
 independent nuclei of gray matter, which may be divided into two sets: (1) those 
 which are traceable from the gray matter of the spinal cord, and (2) those which 
 are not represented in the cord. The former are the hypoglossal nucleus, the 
 nucleus of the fasciculus teres, and those of the auditory, glosso-pharyngeal, vagus, 
 and spinal accessory nerves. The latter are the nucleus of the olivary body and 
 the accessory olivary nuclei. In addition to these, small collections of gray matter 
 are to be found in the median septum or raphe. 
 
 The Hypoglossal Nucleus (Figs. 607, 612, and 613).— The base of the anterior 
 horn, which in the lower part of the medulla was situated on the ventro-lateral 
 aspect of the central canal, now approaches the floor of the ventricle, where it 
 lies close to the median sulcus under the fasciculus teres. In it is a column of 
 large nerve-cells, from which the roots of the hypoglossal nerve are derived. It 
 is accordingly designated the hypoglossal nucleus. 
 
950 
 
 THE NERVOUS SYSTEM 
 
 The Auditory Nuclei (Fig. 613). — Toward the upper part of the medulla, a con- 
 siderable tract of gray matter may be found lying immediately beneath that por- 
 tion of the floor of the fourth ventricle which is known as the trigonum acustici. 
 This is the dorsal or inner auditory nucleus, and it lies just external to the vago- 
 glosso-pharyngeal nucleus. In addition to this there is a small collection of 
 nerve-cells on the ventral surface of the restiform body, between the two roots 
 of the auditory nerve, which is known as the accessory or ventral auditory nucleus. 
 On the outer side of the restiform body is a mass of cells associated with the 
 cochlear root of the auditory nerve. This mass is termed the lateral acoustic 
 tubercle or ganglion radicis cochlearis. 
 
 Nuclei of the Glosso-pharjmgeal and Vagus Nerves (Fig. 613). — These are two in 
 number, principal and accessory. The principal nucleus of the two nerves lies beneath 
 that portion of the floor of the fourth ventricle which is known as the ala cinerea 
 
 INTERNAL 
 GENICULATE 
 
 BODY PULVINAR 
 
 SUPERIOR 
 
 QUADRIGEMINAL 
 
 BODY 
 
 NUCLEUS 
 OF FOURTH 
 
 INTERNAL ROOT 
 
 OF OPTIC TRACT 
 
 OPTIC 
 
 TRACT 
 
 EXTERNAL 
 
 GENICULATE 
 
 BODY 
 
 EXTERNAL ROOT 
 
 OF OPTIC tract" 
 
 SENSORY NUCLEUS. 
 OF FIFTH 
 SENSORY PORTION 
 OF FIFTH 
 SUPERIOR NUCLEUS 
 OF VESTIBULAR 
 INNER NUCLEUS 
 OF VESTIBULAR 
 OUTER NUCLEUS 
 OF VESTIBULAR' 
 VENTRAL NUCLEUS 
 OF COCHLEAR 
 COCHLEAR 
 ROOT 
 
 DESCENDING ROOT 
 AND NUCLEUS OF 
 DESCENDING ROOT 
 OF FIFTH 
 
 MOTOR ROOT 
 / OF FIFTH 
 
 GASSERIAN 
 GANGLION 
 
 SENSORY PORTION I 
 MOTOR PORTION J 
 
 EMERGING PORTION 1 
 INNER PORTION J 
 
 NUCLEUS OF SIXTH 
 PARS PRIMA RADICIS 
 N. FACIALIS 
 
 NUCLEUS 
 OF SEVENTH 
 SEVENTH 
 
 ROOT OF 
 SEVENTH 
 
 VESTIBULAR 
 ROOT 
 
 TENTH 
 
 DORSAL NUCLEUS 
 OF COCHLEAR 
 
 SPINAL ROOT 
 OF FIFTH 
 SPINAL NUCLEUS' 
 OF VESTIBULAR 
 
 NUCLEUS OF ALA 
 CINEREA AND 
 TRACTUS SOLITARIUS 
 COMMISSURAL GANGLI'C 
 
 OF ALA CINEREA' 
 
 Fig. 613. — The nuclei of the origin of the motor and primary terminal nuclei of sensory cerebral nerves, 
 schematically represented in a supposedly transparent brain stem, viewed from behind. Nuclei and roots of 
 motor nerves, red; of sensory, reddish- violet ; of the cochlear nerve, yellow; and of the optic nerve, bluish-violet. 
 X 2. (Held.) 
 
 and fovea inferior. They form an oblong mass of gray matter, above the nucleus 
 of the spinal accessory and lateral to the hypoglossal nucleus. The accessory nuclei 
 are situated in the reticular formation of the posterior area, some distance from 
 the floor of the fourth ventricle. They consist of a pear-shaped mass of cells, 
 which is connected with the rest of the gray matter by a sort of stalk or peduncle, 
 and was formerly known as the nucleus ambiguus (Fig. 607). 
 
 Nucleus of the Spinal Accessory Nerve (Fig. 613). — This nucleus consists of a 
 group of cells, which is situated partly in the lower part of the medulla at the 
 base of the posterior horn and close to the central canal. It extends upward. 
 
INTERNAL STRUCTURE OF THE MEDULLA OBLONGATA 951 
 
 lying beneath the lower part of the floor of the fourth ventricle and on the outer 
 side of the hypoglossal nucleus. 
 
 The Nucleus of the Olivary Body (nucleus olivaris inferior) (Fig. 607). — When 
 the olivary body is cut across, it is seen to be covered externally by white fibres, 
 and internally to consist of a gray layer. The fibres which invest the nucleus are 
 derived from the antero-lateral ground bundle. The gray layer is the nucleus of 
 the olivaxy body, or, as it is sometimes called, the corpus dentatum of the olive. It is 
 composed of a thin, wavy lamina, which is arranged in the form of a hollow capsule, 
 open at its upper and inner part, and presenting a zigzag or dentated outline. 
 Microscopically examined, the olivary nucleus is seen to consist of small, rounded, 
 yellowish nerve-cells embedded in a matrix of neuroglia and fine nerve-fibres. 
 White fibres, which can be traced from the raphe, and are probably derived 
 from the opposite olive, enter the interior of the capsule by the aperture at its upper 
 or inner part, these fibres constituting the olivary peduncle. The olivary peduncle 
 is the lower portion of the cerebello -olivary tract (fibrae cerebelloolivares) . This 
 tract connects the cerebellar hemisphere with the opposite olivary nucleus. 
 
 The fibres of the olivary peduncle as they enter the olivary body diverge and 
 some are lost in the gray matter of the olivary nucleus; others pass through it, and 
 of these some turn backward to join the restiform body, and pass to the cerebellum 
 as internal arcuate fibres; while others pierce the white matter of the olivary body 
 and, reaching the surface, are continued to the restiform body as external arcuate 
 fibres. The nucleus receives the olivary bundle of the spinal cord, the group of 
 fibres called the triangular tract of Helwig. The central tegmental tract arises 
 in the olivary nucleus and passes to the lenticular nucleus. The olivary 
 nucleus receives another descending tract besides the cerebello-olivary, namely, 
 the vestibule -olivary (Santee). From the nucleus fibres pass by way of the lateral 
 column to the anterior cornu of the same side of the spinal cord. Removal of 
 one cerebellar hemisphere is followed by atrophy of the opposite olivary nucleus. 
 Accessory Olivary Nuclei (Fig. 607) . — Two small isolated masses of gray matter 
 are to be found, one on the mesial and the other on the dorsal aspect of the corpus 
 dentatum. These are the medial or internal accessory olivary nucleus (nucleus 
 olivaris accessorius medialis) and the external or lateral accessory olivary nucleus 
 {nucleus olivaris accessorius dorsalis). They are connected with the restiform 
 body by some of the internal arcuate fibres. The fibres of the hypoglossal 
 nerve, as they traverse the bulb, pass between the medial accessory nucleus and 
 the chief olivary nucleus. 
 
 The Raphe (Fig. 607). — The raphd is situated in the middle line of the medulla, 
 above the decussation of the pyramids. It consists of nerve-fibres intermingled 
 with nerve-cells. The fibres have different directions, which can only be seen in 
 suitable microscopic sections, thus: 1. Some are antero-posterior ; these in front 
 are continuous with the superficial arciform fibres. 2. Some are longitudinal; 
 these are derived from the arciform fibres, which on entering the raph^ change 
 their direction and become longitudinal. 3. Some are oblique; these are continu- 
 ous with the deep arciform fibres which pass from the raph^. 
 
 The nerve-cells of the raphe are multipolar; some are connected with the 
 antero-posterior fibres, others with the superficial arcuate fibres. 
 
 Weight of the Encephalon. — ^The average weight of the brain in the adult male 
 is 49 J oz., or a little more than 3 lbs. avoirdupois; that of the female 44 oz.; the 
 average difference between the two being from 5 to 6 oz. The prevailing weight 
 of the brain in the male ranges between 46 oz. and 53 oz., and in the female 
 between 41 oz. and 47 oz. In the male the maximum weight out of 278 cases was 
 65 oz., and the minimum weight 34 oz. The maximum weight of the adult female 
 brain out of 191 cases was 56 oz., and the minimum weight 31 oz. According to 
 Luschka, the average weight of a man's brain is 1424 grammes (about 45 oz.). 
 
952 THE NERVOUS SYSTEM 
 
 of a woman's 1272 grammes (about 41 oz.), and, according to Krause, 1570 
 grammes (about 48| oz.) for the male and 1350 (about 43 oz.) for the female. It 
 appears that the weight of the brain increases rapidly up to the seventh year, more 
 slowly to between sixteen and twenty, and still more slowly to between thirty and 
 forty, when it reaches its maximum. Beyond this period, as age advances and the 
 mental faculties decline, the brain diminishes slowly in weight, about an ounce 
 for each subsequent decennial period. These results apply alike to both sexes. 
 Marshall concluded that if woman is judged by her height only, she has a smaller 
 amount of cerebral matter than has man; if she is judged by her weight alone, she 
 has more; but if both sexes are gauged by both standards, their "cerebral endow- 
 ment is seen to be practically equal. "^ 
 
 The size pf the brain was formerly said to bear a general relation to the intel- 
 lectual capacity of the individual. Cuvier's brain weighed rather more than 64 
 oz., that of Daniel Webster 63f oz., that of Dr. Abercrombie 63 oz. On the 
 other hand, the brain of an idiot seldom weighs more than 23 oz. But these 
 facts are by no means conclusive, and it is well known that these weights have been 
 equalled by the brains of persons who never displayed any remarkable intellect. 
 Dr. Haldennan, of Cincinnati, has recorded the case of a mulatto, aged forty-five, 
 whose brain weighed 68| oz.; he had been a slave, and was never regarded as 
 particularly intelligent; he was illiterate, but is said to have been reserved, medi- 
 tative, and economical. Dr. James Morris recorded the case of a bricklayer, who 
 could not read or write, whose brain weighed 67 oz. Dr. Ensor, district medical 
 officer at Port Elizabeth, reports that the brain of Carey, the Irish informer, 
 weighed 61 oz. In not a few instances the brains of very able men have been of 
 average weight or of less than average weight. The brain of Samuel D. Gross, 
 the surgeon, weighed 48 oz., the brain of Gambetta, the statesman, 40^ oz., the 
 brain of Walt Whitman, the poet, 43.3 oz,, the brain of Hughes Bennett, the 
 physician, 47 oz., the brain of Joseph Leidy, the naturalist and anatomist, 49.9 oz., 
 and the brain of Dollinger, the physiologist, 42.6 oz. M. Nikiforoff has published 
 an article in the Novosti on the subject of the weight of brains. According to 
 him, the weight of the brain has no influence whatever on the mental faculties. 
 It ought to be remembered that the significance of the weight of the brain should 
 depend upon the proportion it bears to the dimensions of the whole body and to 
 the age of the individual. There seems to be a relation between the weight of the 
 brain and the body weight and stature. Quain gives the ratio between the 
 brain weight and body weight as 1 to 41 in healthy individuals, but this propor- 
 tion is by no meaiis fixed and seems to vary widely in either direction. As the 
 stature increases the brain weight increases, but, as Mills says,^ "taller persons 
 have relatively less brain matter than shorter ones, although absolutely they have 
 more." The significance of the weight of the brain also depends upon the cause 
 of death, for long illness or old age wastes the brain. To define the real 
 degree of development of the brain, it is therefore necessary to have a knowl- 
 edge of the condition of the whole body, and, as this is usually lacking, the mere 
 record of weight possesses little significance. As Mills says:^ "Apparently there 
 is no invariable nor necessary relation between mere brain weight and the 
 degree of individual intelligence; but high brain weights occur in larger propor- 
 tions among civilized than among uncivilized races." Furthermore, it is to be 
 remembered that a heavy brain may be a diseased brain. For instance, Byron's 
 brain weighed nearly 64 oz. and showed evidences of disease. 
 
 The human brain is heavier than the brain of any of the lower animals, except- 
 ing the elephant and whale. The brain of the former weighs from eight to ten 
 pounds; and that of a whale, in a specimen seventy-five feet long, weighed rather 
 more than five pounds. 
 
 ' The Nervous System and its Diseases. By Prof. Charles K. Mills. 2 Jbid. 3 Jbid. 
 
CEREBRAL LOCALIZATION AND TOPOGRAPHY 
 
 953 
 
 CEREBRAL LOCALIZATION AND TOPOGRAPHY. 
 
 The cortex of the brain is highly speciaHzed, and different regions represent special functions. 
 In it are represented "the numerous manifestations associated with consciousness;" in it mem- 
 ories are stored up; and "in it occur the last and highest bodily processes concerned with sensa- 
 tions received from without, and with the setting free of impulses which are projected to lower 
 centres and to the outside world."' A centre is an aggregation of nerve-cells and fibres, which 
 "aggregation represents physiologically some action" (Mills). Physiological and pathological 
 researches and surgical operations have proved that the surface of the brain may be mapped out 
 into series of definite centres, each one of which is intimately connected with some well-defined 
 function. A group of centres is known as a zone, an area, or a region. As Hughlings Jackson 
 says, the study of centres is an investigation into the anatomical "substrata" of visual, motor, 
 tactile, and other ideas; of "the parts which represent impressions of sight, of touch, of move- 
 ment, and other functions" (Mills). Certain cortical centres are known as moior cewirfs. Stimu- 
 lation of these centres causes movement. Destruction of these centres renders movement impos- 
 
 FiG. 614. — Drawing to illustrate cranio-, (■itl)ral topography. (Taken from a cast in the Museum of the Royal 
 College of Surgeon.s of I'^ngiand, prepared by Professor Cunningham.) 
 
 sible. The centres are associated with contraction of muscular groups producing special move- 
 ments not with the contraction of individual muscles. They represent movements rather than 
 muscles. These centres are found particularly around the fissure of Rolando and on the mesial 
 surface of the hemisphere, and they are associated with movements of the extremities of the 
 opposite side of the body, and movements of the face, mouth, and tongue. Mills, von Monakow, 
 and Sherrington are of the opinion that the motor areas are entirely in front of the fissure of 
 Rolando (Figs. 61 5 and 61 6). This view is highly probable, but is not absolutely proved. Other 
 observers hold that the motor areas occupy the entire ascending frontal and ascending parietal con- 
 volutions, extend a little way forward into the third frontal convolution and backward into the 
 superior parietal convolution. The motor areas certainly extend on to the mesial surface in the 
 paracentral lobule and pass perhaps into the marginal convolution. On the convexity of the hemi- 
 
 ' The Nervous System and its Diseases. By Prof. Charles K. Mills. 
 
954 
 
 THE NERVOUS SYSTEM 
 
 sphere the highest centre is the leg area. Below this, in the order named, are the centres for the arm, 
 face, lips, tongue, larynx, and pharynx. On the mesial surface from before backward are areas for 
 the head, shoulder, trunk, hip, knee, leg, and foot. The centres for head and eye movements are 
 in front of the arm centre. In a large motor area there are certain smaller areas. For instance, 
 the area for the lower extremity contains separate centres, representing movements of the hip, 
 knee, leg, foot, and toes. 
 
 The arm centre contains centres for movements of the shoulder, arm, wrist, thumb, and 
 fingers. The face centre contains centres for movements of the upper face, the lower face, the 
 
 CONCRLTE CONCEPT 
 
 Fig. 615. — Side view of human brain, showing localization of functions. (Charles K. Mills.) 
 
 lips, and tongue. The somcesthetic area or the area of general sensation is not certainly marked 
 out. Those who believe that the motor area is both front and back of the Rolandic fissure 
 maintain that the area of general sensation largely corresponds to the motor area, but is of 
 greater extent as it enters into the limbic lobe. Mills places it back of the fissure of Rolando 
 in the convexity and also on the mesial surface of the hemisphere. 
 
 Fig. 616. — View of the mesial surface of human brain, showing localization of functions. (Charles K. Mills.) 
 
 The cortical centres are shown in Figs. 617 and 618. This is not the place, nor can space 
 be given, to describe the.se localities. 
 
 Cranio-cerebral Topography.— The position of the principal fissures and convolutions of the 
 cerebrum and their relation to the outer surface of the scalp (Fig. 614) have been the subject of 
 
CEREBRAL LOCALIZATION AND TOPOGRAPHY 
 
 955 
 
 much investigation, and many systems have been devised by which one may localize these parts 
 from an explanation of the external surface of the head. 
 
 These plans can only be regarded as approximately correct for several reasons; in the first 
 place, because the relations of the convolutions and sulci to the surface are found to be very 
 variable in different individuals; secondly, because the surface area of the scalp is greater than 
 the surface area of the brain, so that lines drawn on the one cannot correspond exactly to sulci 
 or convolutions on the other; and thirdly, because the sulci and convolutions in two individuals 
 are never precisely alike. Nevertheless, the principal fissures and convolutions can be mapped 
 out with sufficient accuracy for all practical purposes, so that any particular convolution can be 
 generally exposed by removing with the trephine a certain portion of the skull's area. 
 
 Fig. 617.- 
 
 -The localization of variou.s centres on the outer surface of the left side of the human brain. 
 (American Text-book of Surgery.) 
 
 The various landmarks on the outside of the skull, which can be easily felt, and which serve 
 as indications of the position of the parts beneath, have been already referred to (see page 149), 
 and the relation of the fissures and convolutions to these landmarks is as follows: 
 
 Longitudinal Fissure (Fig. 619). — This corresponds to a line drawn from the glabella at 
 the root of the nose to the external occipital protuberance. 
 
 The Fissure of Sylvius (Fig. 619).— The position of the fissure of Sylvius and its posterior 
 horizontal limb is marked by a line starting from a point one inch and a quarter horizontally 
 behind the external angular process of the frontal bone to a point three-quarters of an inch below 
 
 Fig. 618. 
 
 -The localization of various centres on the median surface of the human brain. 
 (American Text-book of Surgery.) 
 
 L 
 
 the most prominent point of the parietal eminence. The first three-quarters of an inch will rep- 
 resent the main fissure, the remainder the horizontal limb. The bifurcation of the fissure is 
 therefore two inches behind and about a quarter of an inch above the level of the external angu- 
 lar process. The ascending limb of the fissure passes upward from this point parallel to, and 
 immediately behind, the coronal suture. 
 
 The Transverse Fissure or Fissure of Bichat.— This is between the cerebrum and cerebellum 
 and corresponds to a line drawn from the inion to the external auditory meatus (the line B C in 
 Fig. 619). 
 
956 
 
 THE NERVOUS SYSTEM 
 
 Fissure of Rolando. — To find the upper end of the fissure of Rolando, a measurement should 
 be taken from the glabella to the external occipital protuberance. The position of the top 
 of the sulcus will be, measuring from in front, 55.6 per cent, of the whole distance from the 
 glabella to the external occipital protuberance. Professor Thane adopts a somewhat simpler 
 method. He divides the distance from the glabella to the external occipital protuberance over 
 the top of the head into two equal parts, and, having thus defined the middle point of the vertex, 
 he takes half an inch behind it as the top of the sulcus. This is not quite so accurate as the 
 former method, but it is sufficiently so for all practical purposes, and on account of its simplicity 
 is very generally adopted. From this point the fissure runs downward and forward for 3f inches, 
 its axis making an angle of 67° with the middle line. Cunningham states that this angle more 
 nearly averages 71.5°. In order to mark this groove, two strips of metal may be employed — 
 one, the shorter, being fixed to the middle of the other at the angle mentioned. If the longer 
 strip is now placed along the sagittal suture so that the junction of- the two strips is over the 
 point corresponding to the top of the furrow, the shorter, oblique strip will indicate the direction 
 and 3f inches will mark the length of the furrow. Dr. Wilson has devised an instrument, called 
 a cyrtometer, which combines the scale of measurements for localizing the fissure with data for 
 representing its length and direction. ' Professor Thane gives the lower end of the furrow as 
 
 Fig. 619. — Relations of the principal fissures and convolutions of the cerebrum to the outer surface of the 
 
 scalp. (Reid.) 
 
 "close to the posterior limb, and about half an inch behind the bifurcation of the fissure of 
 Sylvius." So that, according to this anatomist, a line drawn from a point half an inch behind 
 the mid-point between the glabella and external occipital protuberance to this spot would mark 
 out the fissure of Rolando. Dr. Reid adopts a different method (Fig. 619). He first indicates 
 on the surface the longitudinal fissure and the horizontal limb of the fissure of Sylvius (as above). 
 He then draws two perpendicular lines from his "base-line" (that is, a line from the lowest 
 part of the infraorbital margin through the middle of the external auditory meatus to the back 
 of the head) to the top of the cranium, one (Z) E, Fig. 619) from the depression in front of the 
 e:;?ternal auditory meatus, and the other ( F G, Fig. 619) from the posterior border of the mastoid 
 process at its root. He has thus described on the surface of the head a four-sided figure (F D G E, 
 Fig. 619), and a diagonal line from the posterior superior angle to the anterior perpendicular 
 line where it is crossed by the fissure of Sylvius will represent the furrow. 
 
 The ParietO-OCCipital Fissure on the upper surface of the cerebrum runs outward at right 
 angles to the great longitudinal fissure for about an inch, from a point one-fifth of an inch in 
 front of the lambda (posterior fontanelle). Reid states that if the horizontal limb of the fissure 
 of Sylvius be continued onward to the sagittal suture, the last inch of this line will indicate the 
 position of the sulcus (Fig. 619). 
 
 ' Lancet, 1888, vol. i. p. 408. 
 
CEREBRAL LOCALIZATION AND TOPOGRAPHY 
 
 957 
 
 The Pre-central Sulcus begins four-fifths of an inch in front of the middle of the fissure of 
 Rolando, and extends nearly, but not quite, to the horizontal limb of the fissure of Sylvius. 
 
 The Superior Frontal Fissure runs backward from the supraorbital notch, parallel with the 
 line of the longitudinal fissure to two-fifths of an inch in front of the line indicating the position 
 of the fissure of Rolando. 
 
 The Inferior Frontal Fissure follows the course of the superior temporal ridge on the frontal 
 bone. 
 
 The Intraparietal Fissure begins on a level with the junction of the middle and lower third 
 of the fissure of Rolando, on a line carried across the head from the back of the root of one 
 auricle to that of the other. After passing upward it curves backward, lying parallel to the 
 longitudinal fissure, midway between it and the parietal eminence; it then curves downward to 
 end midway between the posterior fontanelle and the parietal eminence. 
 
 
 
 
 ^ 
 
 1 
 
 
 jR, 
 
 
 
 S 
 
 Supra orbital line 
 (Superior HorizontaD K 
 
 /a 
 
 B 
 
 
 K' 
 
 Orhital-anricular line 
 ( Base line ) 
 
 
 
 
 Z A M 
 
 Fig. 620. — Kronlein's method for determining the situations of certain fissures of the brain. 
 
 Kronlein's method for determining the situations of certain fissures of the brain is very useful 
 and easy of application(Fig. 620). It is as follows: (1) The base line, Z If , is a horizontal line run- 
 ning at the level of the lower border of the orbit and the upper border of the external auditory 
 meatus. (2) Another horizontal line, K K' , is drawn parallel to Z M. The second horizontal line 
 is on a level with the supraorbital ridge. (3) A vertical line, Z K, is erected from Z M at the 
 middle of the zygoma and is carried to the line, K K'. (4) Another vertical line, A R, is erected 
 from the base-line at the level of the articulation of the mandible and is carried to R. (5) A third 
 vertical line, M P, is erected from the base-line at the posterior border of the mastoid process 
 and is carried to the middle line of the skull, which is marked P. (6) A line is drawn from 
 
958 THE NERVOUS SYSTEM 
 
 K to P. The portion of this Hne between R and P' corresponds to the fissure of Rolando. (7) 
 The angle P K K' is bisected by the line A' S. K S corrssponds to the fissure of Sylvius from 
 its bifurcation to its termination posteriorly, and K is directly over the bifurcation. To reach 
 the anterior branch of the middle meningeal, apply the trephine at A'; to reach the posterior 
 branch, apply it at K'. In abscess of the temporo-sphenoidal lobe the trephine should be applied, 
 according to von Bergmann, in the region Aa K' M. 
 
 THE NERVE-PATHS. 
 
 The anatomy of the various parts of the central nervous system having been 
 described, a short account will now be given of the course taken by its more impor- 
 tant nerve-paths, and of the direction in which impulses pass along them. Before 
 doing so, however, it is necessary to refer to the methods employed in elucidating 
 this complex subject. All nerve-fibres may be regarded as outgrowths from nerve- 
 cells, and it is found that if a nerve-fibre be cut, the portion of it which is severed 
 from the cell undergoes degeneration and becomes atrophied. Until recent years 
 it was believed that the cell itself showed no change under such circumstances. 
 This, however, is not the case, for if a nerve, the sciatic, for instance, be divided in 
 an animal, and after an interval of some weeks the animal be injected with methy- 
 lene blue and killed, it will be seen, on examining sections of the lumbar region 
 of the spinal cord, that the cells are stained imperfectly or not at all, owing to a 
 diminution, or, it may be, an entire disappearance of the chromatin, a substance 
 which, in a normal cell, shows marked affinity for staining reagents. Further, the 
 body of the cell is swollen, the nucleus displayed toward the periphery, and the 
 part of the axone still attached to the altered cell is diminished in size and some- 
 what atrophied. Under favorable conditions the cell is capable of reassuming its 
 normal appearance and the axone may commence to grow. This method of study by 
 injection of methylene blue is of great value in determining the origin of nerve-fibres 
 from their cells. Again, electrical stimulation of certain localized areas of the brain 
 or of the tracts arising from them is followed by the contraction of the muscles of 
 the body. The cortical centres of the motor tracts are situated in the convolutions 
 adjacent to the fissure of Rolando (page 953). When the stimulus is applied to one 
 part of the motor area the muscles of one limb of the opposite contract, while other 
 portions control the movements of the other limb of the opposite side, etc. Destruc- 
 tion of these paHs entails loss of function, paralysis of muscles, and degeneration 
 of the tracts below the seat of injury. During life injury and disease may give 
 rise to symptoms resembling either the effects of stimulation or those of destruc- 
 tion; and after death the tracts, or the centres of the tracts, are seen to be 
 degenerated or otherwise altered. It was long believed by all and is still main- 
 tained by many that the motor area includes the ascending parietal, ascending 
 frontal, and superior parietal convolutions. Mills, von Monakow, Sherrington and 
 other high authorities now teach that the motor region is entirely in front of the 
 central fissure, with the possible exception that the gyral mass between the foot 
 of the fissure of Rolando and the Sylvian fissure, and extending a little back of the 
 line of the central fissure, which may be included in the area for the face (Charles 
 K. Mills) (Figs. 615 and 616). The motor areas are separated from each other 
 and do not overlap, but probably interdigitate (Mills). The same is true of the 
 areas for cutaneous sensibility. By observing the development of the nervous sys- 
 tem during the growth of the embryo, the fact is disclosed that all axis-cylinders 
 do not acquire a medullary sheath at one and the same time. Speaking generally, 
 it may be said that afferent fibres become medullated before efferent, and that in 
 the case of the latter myelination occurs earlier in the brain than in the cord. 
 By watching the effects of these different processes the functions of a considerable 
 part of the brain and of the nerves leading from or to it have been determined. 
 
THE NERVE- PATHS 
 
 959 
 
 The Motor, Efferent, or Descending Tract (Figs. 621, 622, and 623).— The 
 constituent fibres of this tract are the axis-cyhnder processes of cells situated 
 in the cortex of the convolutions about and probably solely in front of the 
 fissure of Rolando, At first they are somewhat widely diffused, but as they 
 
 N motor 
 
 Fig. 621. — Scheme of the motor pathway: c. Fig. 622. — Scheme i~howing the course of the 
 
 central, p, peripheral, neurone; d, decussation: m, pyramidal tract. /, in the cerebrum and crus; //, 
 
 muscle. (Jakob.) m the pons; ///, in the medulla oblongata; /F, de- 
 
 cussation of the pyramids; V , in the cervical en- 
 largement; y/, in the lumbar enlargement. (Jakob.) 
 
 descend through the corona radiata they gradually approach each other and 
 pass between the lenticular nucleus and optic thalamus in the genu and 
 anterior two-thirds of the posterior limb of the internal capsule. Proceeding 
 downward they next occupy the middle three-fifths of the pes or crusta of the 
 crus cerebri, and enter the pons Varolii, where the 
 transverse fibres of this body not only conceal them, 
 but divide them up into irregular bundles. Eventu- 
 ally they reach the medulla, and here the motor 
 tracts form the anterior pyramids which lie one on 
 each side of the median fissure. The transit of the 
 fibres from the medulla is effected by two paths. 
 The fibres nearest to the anterior median fissure 
 cross the middle line, forming the decussation of 
 the pyramids (Figs. 594, 605, 609, 621, 622, and 623), 
 and flescend in the opposite side of the cord as the 
 indirect or crossed pyramidal tract (Figs. 605 and 623). 
 Throughout the length of the spinal cord fibres 
 from this column pass into the gray matter, to ter- 
 minate by ramifying around the cells of the ante- 
 rior horn. The more laterally placed portion of the 
 
 motor tract does not decussate in the medulla, but positTon"of"thepTrarSdaiTract.'* Py, 
 descends as the direct or microssed pyramidal tract ^xif!^c^u^''^^tlTVa^ih^^yI^to 
 (Fig. 605) ; these fibres, however, end in the anterior (jlkob"^"'"'"'^'"^ "^"""^^ "^'■''^'* 
 gray horn of the opposite side of the spinal cord by 
 
 passing across in the anterior white commissure. 1. Motor SiwA inhihiiing influ- 
 ences which reach the spinal nerves arise in the upper three-fourths of the motor 
 area in front of the Rolandic fissure, pass along the fibres of the corona radiata 
 
 Fig. 623. — Scheme showing the 
 
960 THE NERVOUS SYSTEM 
 
 and of the anterior two-thirds of the posterior hmb of the internal capsule, the 
 middle three-fifths of the crusta, the anterior or ventral pontine fibres, and the 
 medullary pyramids. From this point they may pass along either the crossed or the 
 uncrossed pyramidal tract to reach the gray horn of the opposite side of the spinal 
 cord. "By the former route the impulses cross over in the medulla, through the 
 decussation of the pyramids, and descend in the lateral column of the spinal cord ; 
 but by the uncrossed route they descend in the anterior column of the cord and 
 decussate in succession through the white commissure. Impulses by either route 
 finally reach the anterior gray cornu of the spinal cord, and, with the exception of a 
 small percentage of them, they reach the cornu opposite to their Rolandic origin. 
 The few undecussated fibres in the crossed pyramidal tract conduct uncrossed 
 impulses to the anterior cornu of the same side."^ 2. Motor and inhibiting influ- 
 ences which reach the cranial nerves arise in the lower portion of the motor 
 area, pass through the corona radiata and posterior two-thirds of the internal 
 capsule, but deviate from the pyramidal tract before reaching the medulla, and 
 pass to the nuclei of cranial nerves (Fig. 623). On the same side fibres pass to 
 the nuclei of the fourth nerve, but the balance of the fibres cross and pass to 
 nuclei on the opposite side — viz., the nuclei of the third, fifth, sixth, seventh, 
 ninth, tenth, eleventh, and twelfth cranial nerves. 
 
 The Oerebro-cortico-pontal Paths. — These paths pass through the cerebellum. 
 Impulses from the prefrontal region pass along the corona radiata, through the 
 anterior limb of the internal capsule and the inner portion of the crusta. Impulses 
 from the temporal region pass along the corona radiata, through the poste- 
 rior limb of the internal capsule and the outer portion of the crusta. The nucleus 
 pontis and cranial nerve nuclei of the same side receive the impulses from both the 
 frontal and the temporal paths, and from these depots the impulses are sent to 
 cranial nerves or to spinal nerves. To cranial nerves they are sent direct from 
 the synapses about the nuclei. In order to reach spinal nerves they pass to the 
 cerebellar cortex by means of the middle peduncle of the cerebellum. From the 
 cerebellar cortex the impulses pass through the inferior peduncles of the cerebellum 
 and the lateral region of the medulla to reach the anterior gray horn (by way of 
 the antero-lateral descending cerebellar tract). 
 
 The Intermediate Crusta Path (by Way of the Intermediate Bmidle). — Some 
 impulses which arise in the cerebral cortex pass to the corpus striatum, then to the 
 nucleus pontis of the same side (chiefly), then byway of the middle peduncle of 
 the cerebellum to the cerebellar cortex, and then along the antero-lateral descend- 
 ing cerebellar tract. 
 
 The Red Nucleus Path. — Impulses from the cerebral cortex may reach the red 
 nucleus by way of the optic thalamus (direct route) and by way of the corpus 
 striatum (indirect route). 
 
 Impulses which reach the red nucleus by the direct route travel along the 
 crossed descending tract of the red nucleus to the centre of the gray matter in the 
 crescent of the opposite side of the cord. Impulses which reach the red nucleus 
 by the indirect route pass to the cerebellar cortex of the opposite side and from 
 the cortex along the descending cerebellar tract. 
 
 Short Fibre Paths (chiefly in the formatio reticularis). — Santee presents a concise 
 explanation of the course of impulses along these paths.^ He describes five paths: 
 1. Impulses having reached the ganglia of the cerebrum and mesencephalon, 
 pass along the formatio reticularis and reach the antero-lateral ground bundle 
 of the spinal cord to ultimately reach the spinal nerves. Impulses leaving the 
 formatio reticularis may reach motor cranial nerve nuclei. 2. Impulses may 
 pass from the formatio in the pons and by way of the middle cerebellar peduncle 
 
 1 Anatomy of the Brain and Spinal Cord. By Harris E. Santee. ^ Ibid. 
 
THE NEBVE- PATHS 
 
 961 
 
 reach the cerebellar cortex. 3. Impulses which reach the cerebellar cortex may 
 reach the antero-lateral ground bundle of the opposite side of the cord. 4. From 
 the third cranial nerve nucleus fibres pass to the seventh nerve, and impulses come 
 from the third nerve and are sent to the Occipito-fontalis, Corrugator supercilii, and 
 Orbicularis palpebrarum muscles. 5. Fibres pass from the nucleus of the sixth 
 cranial nerve to the nucleus of the opposite third nerve, and impulses pass from 
 the nucleus of the sixth nerve of one side to the Internal rectus muscle of the 
 opposite side. 
 
 The Sensory, Afferent, or Ascending Tract (Figs. 624, 625, and 626). Path 
 by the Columns of GoU and Burdach. — The course taken by those fibres of the 
 posterior nerve-roots which ascend has been 
 arrived at by dividing the nerve-roots between 
 their ganglia and their entrance into the 
 spinal cord and subsequently examining the 
 degenerated areas. It has been found that 
 the fibres pursue an oblique course, being 
 situated at first in the outer part of Bur- 
 dach's column; higher up they occupy the 
 
 N. sens. 
 
 Fig. 624. — Scheme of the sensory pathway: c, central, p, peripheral, neurone; g, intervertebral ganglion 
 cell; b, short,, I, long, tract; d, decussation. (.Jakob.) 
 
 Fig. 625. — Scheme showing the course of the sensory pathway: /, in the cerebrum and cerebral pedun- 
 cles; //, pons and cerebellum; ///, medulla oblongata; IV, upper portion of cervical cord; V, middle portion of 
 cervical cord; VI, lumbar cord; a, fibres from the antero-lateral columns and fillet; b, fibres in the posterior 
 columns; c, fibres from the cerebellum and lateral columns. (.Jakob.) 
 
 Fip. 626. — Scheme of the sensory pathway. Peripheral neurone (dotted line): 1, 2, 3, short, 4, long, tracts. 
 The " switching stations " are indicated by smaller circles. Central neurone (broken line): /, columns of Clarke 
 (direct cerebellar tract); //, interrupted, ///. long, antero-lateral tracts; H, nuclei of posterior column (f. gra- 
 cilis and f. cuneatus); SIV, decussatio lemnisci. (.Jakob.) 
 
 middle of this column, being displaced inward by the accession of other entering 
 fibres, while still higher they enter and are continued upward in the column of 
 Goll. The upper cervical fibres do not reach the column of Goll, but are 
 entirely confined to that of Burdach: The degeneration method proves that the 
 localization of these fibres is very precise: the sacral nerves lying to the inner 
 side of GoU's column and near its periphery; the lumbar nerves to their outer 
 side; the dorsal nerves still more laterally; while the cervical nerves are con- 
 fined to the outer part of Burdach's column. 
 
 61 
 
962 
 
 THE NERVOUS SYSTEM 
 
 On reaching the medulla these ascending fibres end by arborizing around the 
 cells in the gracile and cuneate nuclei, and the further upward course of the tract 
 is effected by the axis-cylinder processes of these cells. There are two paths from 
 this region, the direct and the indirect. The fibres of the direct path decussate in 
 the medulla, dorsal to the crossing of the motor tract, in what is termed the superior 
 pyramidal decussation, the sensory decussation, or the decussation of the fillet(Figs. 605, 
 610, 624, and 626), terms which are synonymous. Having crossed the middle line 
 they ascend through the pons and tegmentum of the crus cerebri, and, reaching the 
 ventral surface of the optic thalamus, from which they pass by the three systems of 
 Flechsig to the cortex. The impulses ascending from the optic thalamus pass to the 
 cortex through the internal capsule and corona radiata. Impulses which take the indi- 
 rect path leave the medulla, pass to the cortex of the superior worm of the cerebellum, 
 
 Vt ^ly" \C) ,>-,'vN J* 
 
 
 I. Sacral 
 
 Fig. 627. 
 
 -Cutaneous areas corresponding to the sensory segments of the spinal cord. 
 B, posterior surface. (After Sticker.) 
 
 A , anterior surface. 
 
 and then through the superior peduncle to the optic thalamus and the red nucleus 
 of the opposite side. These fibres also reach the cortex by means of the systems 
 of Flechsig. The fibres of the sensory path are arranged as follows in the internal 
 capsule : those which go to the fronto-parietal cortex being situated in the extreme 
 front part of the anterior limb of the internal capsule, while in the hinder extremity 
 of the posterior limb other fibres pass to their distribution in the temporal and 
 occipital cortex. 
 
 Path of Cranial Nerves and Medial Fillet. — Common senisory impulses passing 
 along the fifth, the vestibular portion of the eighth, the ninth, and the tenth 
 nerves are conveyed by the medial fillet to the ventral portion of the opposite 
 optic thalamus, and from this region they are taken to the cortex by the systems 
 of Flechsig. 
 
THE NERVE-PATHS 963 
 
 Paths by the Direct Cerebellar Tract.— The direct cerebellar tract begins about 
 the level of the second lumbar vertebra, and is the continuation upward of the 
 axis-cylinders of Clarke's column. At the upper end of the cord it passes into the 
 restiform body and through this reaches the cortex of the superior vermis of 
 the cerebellum. This tract seems to lose some of its fibres in the cord, since the 
 area of degeneration resulting from a section of the lower part of the cord dimin- 
 ishes from below upward; only some of its fibres therefore pass directly to the 
 cerebellum. On the other hand, the tract is reinforced by an accession of fibres 
 from the cord itself, so that its transverse area is greater above than below. Im- 
 pulses of equilibrium pass from the posterior roots of the spinal nerves and 
 ascend along the direct cerebellar tract, chiefly to the cerebellar cortex of the same 
 side, partly to the cerebellar cortex of the opposite side. From the cerebellar 
 cortex they pass to the cerebral cortex by the route previously referred to. 
 
 The Path by the Antero-lateral Ascending Cerebellar Tract. — Ordinary sensory and 
 thermic impulses ascend along this tract to the cerebellar cortex of the opposite 
 side (the superior worm) and partly to the optic thalamus and parietal cortex. 
 
 Short Fibre Paths. — According to Santee there are three of these paths: 1. One 
 path is in the antero-lateral ground bundle and formatio reticularis. It conveys 
 sensory impressions from the gray matter of the cord or from pontine and medul- 
 lary nuclei which receive fibres of common sensation from cranial nerves to the 
 opposite optic thalamus. 2. Another path takes impulses from the formatio 
 reticularis to the cerebellar cortex and then to the red nucleus and optic thalamus. 
 3. Impulses may leave the antero-lateral ascending cerebellar tract along fibres 
 which diverge in the medulla. These impulses reach the lateral nucleus, pass to 
 the cerebellar cortex, and finally attain the cerebral cortex.^ 
 
 Paths of Special Sensations. — (See the section on Cranial Nerves.) 
 
 Reflex Paths. — Reflex paths are almost infinite in number and only a few can 
 be set forth. A spinal reflex action is produced as follows: A stimulus im- 
 parted to a sensory nerve ending is conveyed up the nerve to a centre or several 
 centres in the spinal gray matter, from which it is transferred to a motor nerve, 
 and by this to a muscle which responds to the stimulus by movement. Such a 
 path is called a reflex arc. 
 
 Spinal Reflexes (Fig. 628) may be very simple or somewhat complicated. In 
 the simple spinal reflex the cause of the stimulus is as indicated above. Among 
 these simple spinal reflexes are the patellar reflex, the reflex withdrawal of a part 
 when irritated, and the skin reflexes. 
 
 In a more complicated spinal reflex the "impulses traverse at least three neu- 
 rones" (Santee). The more complicated reflexes are those of "defecation, mic- 
 turition, parturition, vasomotor reflexes, cardio-accelerator reflexes, etc." (Santee). 
 
 A Cranial Reflex travels up a sensory cranial nerve and is transferred to a motor 
 cranial nerve. Among these impulses are "watering" of the mouth on smelling a 
 savory dish, the facial muscular contraction due to pain in the fifth nerve, cough- 
 ing, sneezing, vomiting, and swallowing. 
 
 Spinal Cranial Reflexes are due to the ascent of impulses in the cord by way of 
 the posterior longitudinal bundle or by Burdach's column, which impulses reach 
 the nuclei of cranial motor nerves. "Thus is brought about the movement of the 
 eyes toward the source of impulse, a change of facial expression to agree with 
 the painful or pleasing character of the impulses, etc."^ Cranial spinal reflexes 
 are produced by impulses from cranial sensory nerves being transferred to spinal 
 motor fibres. An example of one of these reflexes is the starting on hearing a 
 sudden loud sound. Among these numerous reflexes are the respiratory, auditory, 
 and pupillary. 
 
 ' Anatomy of the Brain and Spinal Cord. By Harris E. Santee. * I^id. 
 
964 
 
 THE NERVOUS SYSTEM 
 
 Cutaneous Areas Corresponding to the Sensory Segments of the Spinal Cord. — These 
 are shown in Figs. 627 and 628. 
 
 Muscular Supply from Motor Segments of the Cord. — This is shown in Fig. 628. 
 
 LOCATION OF THE SEGMENTS FOR 
 SENSIBILITY. MOTILITY 
 
 Smell 
 
 Ihalcam 
 
 aight j ; 
 
 PhnUal region • 
 
 Bye- 
 
 Face I 
 
 Tongue [ 
 
 Taste 
 
 Hearing • 
 
 Pharynx • 
 
 Larynx 
 £sophagus 
 
 Thoracic and abdominal • 
 viscera 
 Occipital region • 
 
 Front of neck 
 Back of neck 
 Shoulder . 
 
 (Musculo- 
 spiral n. 
 Median n. 
 Ulnar n. 
 
 :z 
 
 j^ 
 
 .jHf.^ 
 
 Nipple ' 
 
 Thorax 
 
 Epigastrium • 
 
 Spigattrie reflex 
 
 Abdomen • 
 Navel 
 
 Inferior abdominal reflex ■ 
 
 Gluteal region • 
 
 Inguinal region 
 
 Sips 
 
 ' Anterior ' 
 
 Thigh 
 
 Legi 
 
 Median 
 
 External .. . 
 
 . Posterior 
 
 j Internal — 
 
 ( External — 
 
 Foot,^ 
 
 Scrotum, penis, etc. — 
 
 Bladder, rectum w. 
 
 Anvx — 
 
 , Sphincter iridis 
 
 " Ciliaris 
 
 n Rectus int., levator palpehr. sup. 
 
 Rectus inf. and sup. 
 ' Obi. infer. 
 
 • Obi. super. 
 
 ' Masseter, temporal, pterygoids 
 
 • Rectus extern. 
 
 . Occipitofront., orbicularis oculi (upper facial) 
 ^Muscles of expression {lower facial) 
 ' Palatal and pharyngeal muscle* 
 ' Muscles of the larynx 
 ' Muscles of the tongue 
 
 " Sternocleidomastoid 
 
 • Deep muscles of the neck 
 
 • Scaleni 
 
 Trapezius, serratus anticut 
 
 • Diaphragm 
 
 ' Delt., biceps, pectoral, maj. {clavic. piyrtion) } ^ 
 ' Brachial, antic, supinator longus > 3 
 
 "^Triceps, latvi.dorsi,pect.maj. {costal " )J* 
 ' Extensores carpi et digitorum^ 
 
 • Flexores carpi et digitorum j '"'*'•''''' 
 ■ Interossei, lumbrical.e8 "J 
 
 C Band, 
 ' Thenar, hypothenar ) 
 
 Intereottali 
 Muscles of the back 
 Abdomirud mutclte 
 
 -•-• Iliopsoas "i 
 — — Sartorius I 
 ■^Adductors r ^*''* 
 "Abductors J 
 
 ' Quadriceps ^ 
 
 » Flexors fl^ 
 
 - Extensors y 
 
 'Peronei 
 
 . Flexors, extenaort of the foot and toes 
 
 . Glutei (?) 
 
 • Perineal > 
 •-«. Vesical > Muscidature 
 
 .Rectal S 
 
 Fig. 628. — Explanation of abbreviations: tr. oil., olfactory tract; c. g. I., lateral geniculate body; p, r, cr. A, 
 indicate approximately the location of the reflex centres for the pupillary (p), the respiratory (r), cremasteric (cr), 
 patellar (pat), and tendo Achillis (.4) reflexes. The vesical centre lies in the third and fourth sacral segments; 
 the anal centre in the fourth and fifth (represented by circlesK the centres for erection, ejaculation, labor 
 pains (?) are probably also situated in this region. In reality, the divisions between the various segments are, 
 of course, not so sharp as they are shown in the diagram, so that a given muscle or cutaneous region derives 
 some of its controlling nerve-roots from the segments lying immediately above and below the principal segment. 
 The sensory segment for any given regioa is regularly somewhat higher than the corresponding motor segment. 
 (Jakob.) 
 
 THE SPINAL NERVES (NERVI SPINALES). 
 
 The spinal nerves are so called because they take their origin from the spinal 
 cord, and are transmitted through the intervertebral foramina on either side of the 
 spinal column. There are thirty-one pairs of spinal nerves, which are arranged 
 
THE ROOTS OF THE SPINAL NERVES 
 
 965 
 
 into the following groups, corresponding to the region of the spine through which 
 they pass: 
 
 Cervical ....... 8 pairs. 
 
 Thoracic or Dorsal 
 Lumbar . 
 Sacral 
 Coccygeal 
 
 12 
 5 
 5 
 1 
 
 It will be observed that each group of nerves corresponds in number with the 
 vertebrae in that region, except the cervical and coccygeal. Sometimes there is no 
 thirty-first pair. Occasionally below the thirty-first pair there may be one or even 
 two filamentous pairs which do not pass out of the spinal canal. 
 
 Each spinal nerve arises by two roots, an anterior or motor root and a posterior 
 or sensory root, the latter being distinguished by a ganglion, termed the spinal 
 ganglion. 
 
 DORSA 
 NERVE 
 ROOTS 
 
 LIGAMENTUM 
 ,DENTICULATUM 
 DURA 
 PENED 
 
 SPINAL NERVE 
 IN ITS PIAL 
 SHEATH 
 
 The Roots of the Spinal Nerves (Figs. 538, 540, 541, 629, 630, 631). 
 
 The Anterior or Ventral Root {radix anterior). — The superficial origin is 
 from the antero-lateral columns of the cord, corresponding to the situation of the 
 anterior cornu of gray matter. Each root 
 is composed of from four to eight fila- 
 ments (fila radicularia). 
 
 The deep origin can be traced through 
 the antero-lateral column; the roots, after 
 penetrating horizontally through the lon- 
 gitudinal fibres of this tract, enter the gray 
 substance, where their fibrils diverge in 
 several directions: some passing inward, 
 are continued across the anterior com- 
 missure in front of the central canal, to 
 become continuous with the axis-cylinder 
 processes of the large cells of the anterior 
 cornu of the opposite side; others termi- 
 nate in the mesial group of cells of the 
 anterior column of the same side; other 
 fibrils pass outward, to become continuous 
 with the axis-cylinder processes of the 
 group of cells in the lateral part of the 
 anterior column. 
 
 The Posterior or Dorsal Root {radix 
 posterior). — The superficial origin is by 
 filaments (fila radicularia), from the pos- 
 tero-lateral fissure of the cord. The real 
 origin of these fibres is from the nerve- 
 cells in the posterior root ganglion, from 
 which they can be traced into the cord 
 in two main bundles, the course of which 
 has already been studied (p. 847). 
 
 The anterior roots are smaller than the 
 posterior, devoid of ganglionic enlargement, and their component fibrils are 
 collected into two bundles near the intervertebral foramina. 
 
 The posterior roots of the nerves are larger, but the individual filaments are 
 finer and more delicate than those of the anterior. As their component fibrils 
 
 LIGAMENTUM 
 DENTICULATUM 
 VENTRAL ROOTS 
 
 SPINAL NERVE 
 IN ITS SHEATH 
 
 Fig. 629. — A portion of the spinal cord, showing 
 its right lateral surface. The dura is opened and 
 arranged to show the nerve roots. (Testut.) 
 
 b 
 
966 
 
 THE NERVOUS SYSTEM 
 
 pass outward toward the aperture in the dura mater, they coalesce into two 
 bundles, receive a tubular sheath from that membrane, and enter the ganglion 
 (Figs. 629, 630, and 631) which is developed upon each root. 
 
 The posterior root of the first cervical nerve forms an exception to these char- 
 acters. It is smaller than the anterior, has occasionally no ganglion developed 
 upon it, and when the ganglion exists, it is often situated within the dura mater. 
 The first cervical may have a rudimentary posterior root or no posterior root. 
 
 NTERNAL BRANCH 
 
 EXTERNAL BRANCH 
 
 POSTERIOR PRIMARY 
 DIVISION 
 
 ^ANTERIOR PRIMARY 
 DIVISION 
 
 RAMUS COMMUNICANS 
 
 Fig. 630. — Plan of the constitution of a spinal nerve. (W. Xeiller, in Gerrish's Text -book of Anatomy.) 
 
 Within the spinal canal the nerve-roots are separated from each other by the 
 ligamentum denticulatum (Fig. 629). In the cervical region the spinal portion 
 of the spinal accessory nerve separates the roots. Each root obtains a covering 
 of pia mater, which becomes continuous with the neurilemma; " the arachnoid 
 invests each root as far as the point where it meets with the dura mater; the two 
 roots, after piercing the dura separately, are enclosed by it in a single tubular 
 sheath, in which is included the spinal ganglion of the dorsal root."* 
 
 Neuraxis of Peripheral 
 Sensory Neurone 
 
 Nerve Trunk 
 
 Spinal Ganglion 
 
 Dendrite of 
 
 Peripheral Sensory 
 
 Neurone 
 
 Neuraxis of 
 Sympathetic Neurone 
 
 'Neuraxis of Peripheral Motor Neurone 
 
 f -Sympathetic Ganglion 
 
 \ 
 
 Fig. 631. — Diagram to show the composition of a peripheral nerve-trunk. (Bohm and Davidoff.) 
 
 The Ganglia of the Spinal Nerves (Ganglia Spinales) (Figs. 629, 630, 631). 
 
 A ganglion is developed upon the posterior root of each of the spinal nerves. 
 The ganglion upon the posterior root of the first cervical nerve may be rudimentary 
 or absent. These ganglia are of an oval form and of a reddish color; they bear 
 a proportion in size to the nerves upon which they are formed, and are placed 
 in the intervertebral foramina, external to the point where the nerves perforate 
 
 1 Cunningham's Text-book of Anatomy. 
 
POINTS OF EMERGENCE OF THE SPINAL NERVES 967 
 
 the dura mater. Each gangHon is bifid internally, where it is joined by the 
 two bundles of the posterior root, the two portions being united into a single 
 mass externally. The ganglia upon the first and second cervical nerves form an 
 exception to these characters, being placed on the arches of the vertebrae over 
 which the nerves pass. The ganglia of the sacral nerves are placed within the 
 spinal canal; and that on the coccygeal nerve, also in the canal, is situated at 
 some distance from the origin of the posterior root. 
 
 The ganglion in an embryo is composed of bipolar nerve-cells. In an adult 
 the bipolar nerve-cells by fusion of their two poles form unipolar nerve-cells. The 
 process of each unipolar cell divides into two a short distance from the cell. One 
 of the processes from each cell passes to the spinal cord, and the other passes 
 into the spinal nerve. On the dorsal roots of the lumbar and sacral nerves, 
 between the spinal ganglia and the cord, small cellular masses occasionally exist. 
 They are called accessory spinal ganglia {ganglia aberrantia). 
 
 Distribution of the Spinal Nerves. 
 
 Immediately beyond the ganglion the two roots coalesce, their fibres inter- 
 mingle, and the trunk thus formed constitutes the spinal nerve; it passes out 
 of the intervertebral foramen, and divides into a posterior primary division for 
 the supply of the posterior part of the body, and an anterior primary division 
 for the supply of the anterior part of the body (Fig. 630). Each division contains 
 fibres from both roots. 
 
 Before dividing, each spinal nerve gives off a small recurrent or meningeal 
 branch (ramus meningeus) (Fig. 630), which is joined by a filament from the 
 communicating branch of the sympathetic (ramus communicans) (Fig. 630), which 
 connects the ganglion with the anterior division. The meningeal branches unite 
 and form one nerve, which passes inward through the intervertebral foramen and 
 supplies the dura mater, sending branches to the vertebrae and vertebral ligaments. 
 
 The Posterior Primary Divisions (rami posteriores) (Fig. 630). — ^The posterior pri- 
 mary divisions of the spinal nerves are generally smaller than the anterior; they arise 
 from the trunk resulting from the union of the roots, in the intervertebral foramina; 
 and, passing backward, divide into internal and external branches, which are dis- 
 tributed to the muscles and integument behind the spine. The posterior primary 
 divisions of the spinal nerves form two small plexuses, the posterior cervical plexus 
 and the posterior sacral plexus. The first cervical, the fourth and fifth sacral, and 
 the coccygeal nerves do not divide into external and internal branches. 
 
 The Anterior Primary Divisions (rami anteriores) (Fig. 630). — The anterior 
 primary divisions of the spinal nerves supply the parts of the body in front of 
 the spine, including the limbs. They are for the most part larger than the 
 posterior primary divisions. Each division, soon after its origin, receives a slen- 
 der filament from the sympathetic, which is called the gray ramus communi- 
 cans. In the dorsal region the anterior primary divisions of the spinal nerves 
 are quite separate from each other, and are uniform in their distribution ; but in the 
 cervical, lumbar, and sacral regions they form intricate plexuses previous to their 
 distribution. The anterior primary divisions of certain dorsal, lumbar, and sacral 
 nerves give off a delicate collection of nerve filaments to the sympathetic cord. 
 These are called the white rami communicantes or the visceral branches of the spinal 
 nerves. 
 
 Points of Emergence of the Spinal Nerves. 
 
 The roots of the spinal nerves from their origin in the cord run obliquely 
 downward to their point of exit from the intervertebral foramina, the amount of 
 obliquity varying in different regions of the spine, and being greater in the lower 
 
968 
 
 THE NERVOUS SYSTEM 
 
 than the upper part. The level of their emergence from the cord is within certain 
 limits variable, and of course does not correspond to the point of emergence of 
 the nerve from the intervertebral foramina. 
 
 The following table, from Macalister, shows as accurately as can be shown the 
 relation of these points of origin from the spinal cord to the bodies and spinous 
 processes of the vertebrae: 
 
 Level of body of 
 
 No. of nerve. 
 
 Level of tip of 
 spine of 
 
 Level of body of 
 
 No. of nerve. 
 
 Level of tip of 
 spine of 
 
 C. 1 
 
 C. 1 
 
 
 D. 8 
 
 9 
 
 7 d. 
 
 M 
 
 2 
 
 
 9 
 
 10 
 
 8 d. 
 
 3 
 
 i'c. 
 
 10 
 
 11 
 
 9 d. 
 
 3 
 
 4 
 
 2 c. 
 
 
 12 
 
 10 d. 
 
 4 
 
 5 
 
 3 c. 
 
 i'i 
 
 L. 1 
 
 11 d. 
 
 5 
 
 6 
 
 4 c. 
 
 f 
 
 2 
 
 
 6 
 
 7 
 8 
 
 5 c. 
 
 6 c. 
 
 '1 
 
 3 
 4 
 
 12 d. 
 
 7 
 
 D. 1 
 
 7 c. 
 
 r 
 
 5 
 
 ■ ■ 
 
 D. 1 
 
 2 
 
 1 d. 
 
 1 
 
 S. 1 
 
 2 
 
 3 
 
 
 L. 1-1 
 
 2 
 
 
 3 
 
 4 
 
 2'd. 
 
 
 3 
 
 
 4 
 
 5 
 
 3 d. 
 
 
 4 
 
 1 L. 
 
 5 
 
 6 
 
 4 d. 
 
 
 5 
 
 
 6 
 
 7 
 
 5 d. 
 
 
 C. 1 
 
 
 7 
 
 8 
 
 6 d. 
 
 L. '"2 
 
 
 
 THE CERVICAL NERVES (NN. CERVICALES). 
 
 The Roots of the Cervical Nerves. 
 
 The roots of the cervical nerves increase in size from the first to the fifth, and 
 then remain the same size to the eighth. The posterior roots bear a proportion 
 to the anterior as 3 to 1, which is much greater than in any other region, the 
 individual filaments being also much larger than those of the anterior roots. The 
 posterior root of the first cervical is an exception to this rule; it is smaller than 
 the anterior root. In direction the roots of the cervical are less oblique than 
 those of the other spinal nerves. The first cervical nerve is directed a little upward 
 and outward; the second is horizontal; the others are directed obliquely down- 
 ward and outward, the lowest being the most oblique, and consequently longer 
 than the upper, the distance between their place of origin and their point of exit 
 from the spinal canal never exceeding the depth of one vertebra. 
 
 The First Cervical or Suboccipital Nerve (w. suboccipitalis) (Fig. 632).— The 
 posterior root may be rudimentary or absent. The trunk of the first cervical 
 nerve leaves the spinal canal between the occipital bone and the posterior arch 
 of the atlas (Figs. 16 and 202). 
 
 The Trunk of the Second Cervical Nerve leaves the spinal canal between the 
 posterior arch of the atlas and the lamina of the axis; and the Eighth (the last), 
 between the last cervical and first dorsal vertebrae. 
 
 Each nerve, at its exit from the intervertebral foramen, divides into a posterior 
 and an anterior division. The anterior divisions of the four upper cervical nerves 
 form the cervical plexus. The anterior divisions of the four lower cervical nerves, 
 together with the first dorsal, form the brachial plexus. 
 
 The Posterior or Dorsal Divisions of the Cervical Nerves (Rami Posteriores) 
 
 (Fig. 633). 
 
 The Posterior Division of the First Cervical Nerve (Figs. 632 and 633) differs 
 from the posterior divisions of the other cervical nerves in not dividing into an 
 internal and external branch. It is larger than the anterior division, and escapes 
 from the spinal canal between the occipital bone and the posterior arch of the atlas, 
 
POSTERIOR OR DORSAL DIVISIONS OF CERVICAL NERVES 969 
 
 lying beneath the vertebral artery. It enters the suboccipital triangle formed by 
 the Rectus capitis posticus major, the Obliquus superior and Obliquus inferior, 
 and, by muscular branches, supphes the Recti and Obliqui muscles, and the 
 Complexus. From the branch which supplies the Inferior oblique a communi- 
 cating filament is given off which joins the second cervical nerve. This nerve 
 also occasionally gives off a cutaneous filament, which accompanies the occipital 
 artery and communicates with the occipitalis major and minor nerves. 
 
 The Posterior Division of the Second Cervical Nerve is three or four times greater 
 in diameter than the anterior division, and the largest of all the posterior 
 cervical divisions. It emerges from the spinal canal between the posterior arch 
 of the atlas and lamina of the axis, below the Inferior oblique. It supplies a twig 
 to this muscle, and receives a communicating filament from the first cervical. 
 It then divides into an internal and an external branch. 
 
 The internal branch, called, from its size and distribution, the great occipital nerve 
 (occipitalis major) (Figs. 632 and 633), ascends obliquely inward between the 
 Obliquus inferior and Complexus, and pierces the latter muscle and the Trapezius 
 
 GREAT OCCIPI- 
 TAL NERVE 
 
 RECTUS CAPITIS 
 LATERALIS 
 
 ANTERIOR PRIMARY DIV1-. 
 SION OF FIRST CERVICAL 
 
 POSTERIOR PRIMARY DIVI 
 SION OF FIRST CERVICAL 
 
 OBLIQUUS 
 SUPERIOR 
 
 BRANCH TO COMPLEXUS — OUT 
 
 VERTEBRAL ARTERY 
 
 POSTERIOR PRIMARY DIVI- 
 SION OF FIRST CERVICAL 
 ANASTOMOTIC BRANCH 
 
 ANASTOMOTIC 
 THIRD CERVICAL 
 
 BLIQUUS 
 NFERIOR 
 
 Fig. 632. — Dorsal primary divisions of the upper three cervical nerves. (Testut.) 
 
 near their attachments to the cranium. It is now joined by a filament from the 
 posterior division of the third cervical nerve, the anastomotic, and, ascending on 
 the back part of the head with the occipital artery, divides into two branches, 
 which supply the integument of the scalp as far forward as the vertex, com- 
 municating with the occipitalis minor. It gives off an auricular branch to the 
 back part of the ear and muscular branches to the Complexus. 
 
 The external branch is often joined by the external branch of the posterior 
 division of the third cervical nerve, and supplies the Splenius, Trachelo-mastoid, 
 and Complexus 
 
 The Posterior Division of the Third Cervical Nerve (Figs. 632 and 633) is smaller 
 than the preceding, but larger than the fourth; it differs from the posterior 
 divisions of the remaining cervical nerves in its supplying an additional filament, 
 the third occipital nerve, to the integument of the occiput. The posterior division 
 of the third nerve, like the others, divides into an internal and external branch. 
 
 The internal or cutaneous branch passes between the Complexus and Semi- 
 spinalis, and, piercing the Splenius and Trapezius, supplies the skin over the 
 latter muscle. 
 
970 
 
 THE NERVOUS SYSTEM 
 
 The external branch joins with that of the posterior division of the second to 
 supply the Splenius, Trachelo-mastoid, and Complexus. 
 
 The third or least occipital nerve {n. occipitalis minimus or n. occipitalis icriius) 
 (Fig. 632) arises from the internal or cutaneous branch of the posterior division of 
 the third cervical nerve, beneath the Trapezius; it then pierces that muscle, and 
 supplies the skin on the lower and back part of the head. It lies to the inner side 
 of the occipitalis major, with which it is connected. 
 
 SA:in> over* 
 
 
 
 Fig. 633. — Posterior divisions of the upper cervical nerves. 
 
 The posterior division of the suboccipital nerve and the internal branches of 
 the posterior divisions of the second and third cervical nerves are occasionally 
 joined beneath the Complexus by communicating branches. This communication 
 is described by Cruveilhier as the posterior cervical plexus. 
 
 The Posterior Divisions of the Fourth, Fifth, Sixth, Seventh, and Eighth Cervical 
 Nerves pass backward, and divide, behind the Intertransversales muscles, into 
 internal and external branches. 
 
 The internal branches, the larger, are distributed differently in the upper and 
 lower part of the neck. T^hose derived from the fourth and fifth nerves pass 
 
THE ANTERIOR DIVISIONS OF THE CERVICAL NERVES 97 1 
 
 between the Complexus and Semispinalis muscles, and, having reached the spin- 
 ous processes, perforate the aponeurosis of the Splenius and Trapezius, and are 
 continued outward to the integument over the Trapezius, whilst those derived 
 from the three lowest cervical nervies are the smallest, and are placed beneath 
 the Semispinalis colli, which they supply, and then pass into the Interspinalis, 
 Multifidus spinae, and Complexus, and send twigs through this latter muscle to 
 supply the integument near the spinous processes (Hirschfeld). 
 
 The external branches supply the muscles at the side of the neck — viz., the 
 Cervicalis ascendens, Transversalis colli, and Trachelo-mastoid. 
 
 The Anterior Divisions of the Cervical Nerves (Rami Anteriores). 
 
 The Anterior Division of the First Cervical Nerve (Fig. 635) is of small size. 
 It escapes from the spinal canal through a groove upon the posterior arch of the 
 atlas. In this groove it lies beneath the vertebral artery, to the inner side of the 
 Rectus capitis lateralis. As it crosses the foramen in the transverse process of 
 the atlas it receives a filament from the sympathetic. It then descends in front 
 of the transverse process, to communicate with an ascending branch from the 
 second cervical nerve. 
 
 Communicating filaments from the loop between this nerve and the second 
 cervical nerve join the pneumogastric, the hypoglossal, and sympathetic, and 
 some branches are distributed to the Rectus lateralis and the two Anterior recti. 
 The fibres which communicate with the hypoglossal simply pass through the 
 latter nerve to become for the most part the descendens h3rpoglossi. According 
 to Valentin, the anterior division of the suboccipital nerve distributes filaments 
 to the occipito-atlantal articulation and to the mastoid process of the temporal 
 bone. 
 
 The Anterior Division of the Second Cervical Nerve (Fig. 635) escapes from the 
 spinal canal, between the posterior arch of the atlas and the lamina of the axis, and, 
 passing forward on the outer side of the vertebral artery, divides in front of the 
 Intertransverse muscle into an ascending branch, which joins the first cervical; and 
 one or two descending branches, which join the third cervical. It gives off the 
 small occipital; a branch to assist in forming the great auricular; another to assist 
 in forming the superficial cervical; one of the communicantes h3rpoglossi, and a 
 filament to the Sterno-mastoid, which communicates in the substance of the 
 muscle with the spinal accessory. 
 
 The Anterior Division of the Third Cervical Nerve (Fig. 635) is double the size of 
 the preceding. At its exit from the intervertebral foramen it passes downward and 
 outward beneath the Sterno-mastoid muscle, and divides into two branches. The 
 ascending branch joins the anterior division of the second cervical; the descending 
 branch passes down in front of the Scalenus anticus muscle and communicates 
 with the fourth cervical. It gives off the larger part of the great auricular and 
 superficial cervical nerves; one of the communicantes h3rpoglossi; a branch to the 
 supraclavicular nerves; a filament to assist in forming the phrenic; and muscular 
 branches to the Levator anguli scapulae and Trapezius; this latter nerve com- 
 municates beneath the muscle with the spinal accessory. Sometimes the nerve 
 to the Scalenus medius is derived from this source. 
 
 The Anterior Division of the Fourth Cervical Nerve (Fig. 635) is of the same size as 
 the preceding. It receives a branch from the third, sends a communicating branch 
 to the fifth cervical, and, passing downward and outward, divides into numerous 
 filaments, which cross the posterior triangle of the neck, forming the supraclavicular 
 nerves. It gives a branch to the phrenic nerve, while it is contained in the inter- 
 transverse space, and sometimes a branch to the Scalenus medius muscle. It also 
 gives a branch to the Levator anguli scapulae and to the Trapezius, which unites 
 
972 
 
 THE NERVOUS SYSTEM 
 
 with the branch given off from the third nerve, and communicates beneath the 
 muscle with the spinal accessory. 
 
 The Anterior Divisions of the Fifth, Sixth, Seventh, and Eighth Cervical Nerves are 
 remarkable for their size. They are much larger than the preceding nerves, and 
 are all of equal dimensions. They assist in the formation of the brachial plexus. 
 
 The Cervical Plexus (Plexus Cervicalis) (Figs. 634 and 635). 
 
 The cervical plexus is formed by the anterior divisions of the four upper 
 cervical nerves. It is situated opposite the four upper cervical vertebrae, rest- 
 ing upon the Levator anguli scapulae and Scalenus medius muscles, and covered 
 in by the Stern o-mastoid. 
 
 Its branches may be divided into two groups, superficial and deep, which may 
 be thus arranged: 
 
 {Occipitalis minor. 
 Auricularis magnus. 
 Superficialis colli. 
 
 Superficial 
 
 Deep 
 
 Descending 
 
 Internal 
 
 External 
 
 1 Suprasternal. 
 Supraclavicular. 
 Supra-acromial. 
 Communicating. 
 Muscular. 
 
 Communicantes hypoglossi. 
 Phrenic. 
 Communicating. 
 Muscular. 
 
 The Superficial Branches of the Cervical Plexus. The Small Occipital Nerve 
 
 (n. occipitalis minor) (Fig. 634), — The small occipital nerve arises from the second 
 cervical nerve, sometimes also from the third ; it curves round the posterior border 
 of the Sterno-mastoid, and ascends, running parallel to the posterior border of the 
 muscle, to the back part of the side of the head. Near the cranium it perforates 
 the deep fascia, and is continued upward along the side of the head behind the 
 ear, supplying the integument, and communicating with the occipitalis major, the 
 auricularis magnus, and with the posterior auricular branch of the facial. 
 
 This nerve gives off an auricular branch, which supplies the integument of the 
 upper and back part of the auricle, communicating with the mastoid branch 
 of the auricularis magnus. The auricular branch is occasionally derived from 
 the great occipital nerve. The occipitalis minor varies in size; it is occasionally 
 double. 
 
 The Great Auricular Nerve (n. auricularis magnus) (Fig. 634). — The great 
 auricular nerve is the largest of the ascending branches. It arises from the 
 second and third cervical nerves, winds around the posterior border of the Sterno- 
 mastoid, and, after perforating the deep fascia, ascends upon that muscle beneath 
 the Platysma to the parotid gland, where it divides into facial, auricular, and 
 mastoid branches. 
 
 The Facial Branches pass across the parotid, and are distributed to the integ- 
 ument of the face over the parotid gland; others penetrate the substance of the 
 gland and communicate with the facial nerve. 
 
 The Auricular Branches ascend to supply the integument of the back of the 
 pinna, except at its upper part, communicating with the auricular branches of 
 the facial and pneumogastric nerves. A filament pierces the pinna to reach its 
 outer surface, where it is distributed to the lobule and lower part of the concha. 
 
THE CERVICAL PLEXUS 
 
 973 
 
 The Mastoid Branch communicates with the occipitaUs minor and the posterior 
 auricular branch of the facial, and is distributed to the integument behind the 
 
 ear. 
 
 The Superficial Cervical Nerve or the Superficialis Colli {n. cutaneus colli) (Fig. 
 634). — The superficial cervical nerve or the superficialis coUi arises from the 
 second and third cervical nerves, turns around the posterior border of the Sterno- 
 
 POSTERIOR 
 AURICULAR 
 NERVE 
 
 GREAT 
 
 OCCIPITAL 
 
 GREAT 
 AURICULAR 
 
 (posterior branch 
 
 SMALL 
 OCCIPITAL 
 
 THIRD 
 OCCIPITAL 
 
 GREAT 
 AURICULAR 
 
 (anierior branches) 
 
 BRANCHES TO 
 
 TRAPEZIUS 
 
 SUPRACLAVICULAR 
 
 NERVES 
 
 (acromial 
 branches; 
 
 BRANCHES 
 OF FACIAL 
 NERVE 
 
 SUPRACLAVrCULAR 
 
 NERVES (Sternal 
 branches) 
 
 Fig. 634.- 
 
 SUPRACLAVICULAH 
 
 NERVES (clavicular 
 branches) 
 
 -The cutaneous branche.s of the right cervical plexus, viewed from the right. The Platysma 
 has been partly removed. (Spalteholz ) 
 
 I 
 
 mastoid about its middle, and, passing obliquely forward beneath the external 
 jugular vein to the anterior border of the muscle, perforates the deep cervical 
 fascia, and divides beneath the Platysma into two branches, which are distributed 
 to the antero-lateral parts of the neck. 
 
 The Ascending Sranch or Branches {rami swperiores) gives a filament which 
 accompanies the external jugular vein; it then passes upward to the sub- 
 maxillary region, and divides into branches, some of which form a plexus with 
 the cervical branches of the facial nerve beneath the Platysma; others pierce 
 
974 THE NERVOUS SYSTEM 
 
 that muscle and are distributed to the integument of the upper half of the neck, 
 at its forepart, as high as the chin. 
 
 The Descending Branches {rami inferior es), usually represented by two or more 
 filaments, pierce the Platysma, and are distributed to the integument of the side 
 and front of the neck, as low as the sternum. 
 
 The Descending or Supraclavicular Branches {nn. swpraclaviculares) (Fig. 634). — 
 The descending or supraclavicular branches arise from the third and fourth 
 cervical nerves; emerging beneath the posterior border of the Sterno-mastoid, they 
 descend in the posterior triangle of the neck beneath the Platysma and deep 
 cervical fascia. Near the clavicle they perforate the fascia and Platysma to 
 become cutaneous, and are arranged, according to their position, into three 
 groups. 
 
 The Inner or Suprasternal Branches {nn. swpraclaviculares anteriores) cross 
 obliquely over the external jugular vein and the clavicular and sternal attach- 
 ments of the Sterno-mastoid muscle, and supply the integument as far as the 
 median line. They furnish one or two filaments to the sterno-clavicular joint. 
 
 The Middle or Supraclavicular Branches {nn. swpraclaviculares medii) cross the 
 clavicle, and supply the integument over the Pectoral and Deltoid muscles, com- 
 municating with the cutaneous branches of the upper intercostal nerves. 
 
 The External or Supra-acromial Branches {nn. supraclaviculares posteriores) pass 
 obliquely across the outer surface of the Trapezius and the acromion, and supply 
 the integument of the upper and back part of the shoulder. 
 
 The Deep Branches of the Cervical Plexus (Fig. 635). Internal Series. 
 The Communicating Branches. — The communicating branches consist of several 
 filaments which pass from the loop between the first and second cervical nerves 
 in front of the atlas to the pneumogastric, hypoglossal, and sympathetic; of 
 branches from all four cervical nerves to the superior cervical ganglion of the 
 sympathetic, together with a branch from the fourth to the fifth cervical. 
 
 Muscular Branches. — Muscular branches supply the Anterior recti and Rectus 
 lateralis muscles; they proceed from the first cervical nerve, and from the loop 
 formed between it and the second. 
 
 The Gommunicantes H3rpoglossi (Fig. 635). — The communicantes hypoglossi 
 consist usually of two filaments, one being derived from the second and the other 
 from the third cervical. These filaments pass downward on the outer side of the 
 internal jugular vein, cross in front of the vein a little below the middle of the 
 neck, and form a loop with the descendens hypoglossi in front of the sheath of 
 the carotid vessels. Occasionally, the junction of these nerves. takes place within 
 the sheath. 
 
 The Phrenic or the Internal Respiratory Nerve of Bell {n. phrenicus) (Figs. 635 and 
 636) . — ^The phrenic or the internal respiratory nerve of Bell arises chiefly from the 
 fourth cervical nerve, with a few filaments from the third and a communicating 
 branch from the fifth. It descends to the root of the neck, running obliquely 
 across the front of the Scalenus anticus muscle, and beneath the Sterno-mastoid 
 muscle, the posterior belly of the Omohyoid muscle, and the Transversalis colli 
 and suprascapular vessels. It next passes over the first part of the subclavian 
 artery, between it and the subclavian vein, and, as it enters the chest, crosses the 
 internal mammary artery near its origin. Within the chest it descends nearly 
 vertically in front of the root of the lung and by the side of the pericardium, 
 between it and the mediastinal portion of the pleura, to the Diaphragm, where 
 it divides into branches, some few of which are distributed to its thoracic surface, 
 but most of which separately pierce that muscle and are distributed to its under 
 surface {rami phrenicoahdominales) . 
 
 The two phrenic nerves differ in their length, and also in their relations at the 
 upper part of the thorax. 
 
THE CERVICAL PLEXUS 
 
 975 
 
 The right phrenic nerve is situated more deeply, and is shorter and more 
 vertical in direction than the left; it lies on the outer side of the right vena 
 innominata and superior vena cava. 
 
 The left phrenic nerve is rather longer than the right, from the inclination of 
 the heart to the left side, and from the Diaphragm being lower on this than on the 
 opposite side. It enters the thorax behind the left innominate vein, and crosses 
 in front of the vagus and the arch of the aorta and the root of the lung. In the 
 thorax each phrenic nerve is accompanied by a branch of the internal mammary 
 artery, the comes nervi phrenici. 
 
 Recti Cap. Lat. 
 
 \Rect. Ant. Major 
 iReci. Ant. Minor 
 
 ' To Sympathetic 
 
 3 To Hypoglossal 
 iTo Vagiix 
 
 — JTo Scalp and Occipito Frontalis 
 
 irr 
 
 Fig. 635. — Plan of the cervical plexus. 
 
 Each nerve supplies filaments to the Diaphragm, pericardium, and pleura, 
 and near the chest is joined by a filament from the sympathetic, and, occasion- 
 ally, by one from the union of the descendens hypoglossi with the spinal nerves; 
 this filament is found, according to Swan, only on the left side. The phrenic fre- 
 quently receives a filament from the nerve to the Subclavian muscle. Branches 
 have been described as passing to the peritoneum. 
 
 From the right nerve one or two filaments pass to join in a small ganglion with 
 phrenic branches of the solar plexus; and branches from this ganglion are 
 distributed to the hepatic plexus, the suprarenal capsule, and inferior vena 
 cava. 
 
 From the left nerve filaments pass to join the phrenic plexus of the sympathetic, 
 but without any ganglionic enlargement. 
 
976 
 
 THE NERVOUS SYSTEM 
 
 Surgical Anatomy. — Irritation of the phrenic nerve causes hiccough and persistent cough. 
 Bilateral paralysis of the phrenic causes death from paralysis of the Diaphragm. This form of 
 death is seen by the surgeon in fracture-dislocation of the third cervical vertebra. Division of 
 the phrenic on one side is not fatal, and is occasionally practised by the surgeon in removing 
 a tumor of the neck. In Hearn's and Franklin's cases of removal of the pneumogastric, the 
 phrenic was also divided. Unilateral division of the phrenic nerve causes paralysis of the corre- 
 sponding half of the Diaphragm, which is difficult of recognition, because, as Gowers points out, 
 the patient can still take deep inspirations, the thoracic muscles not being paralyzed. 
 
 ANTERIOR PRIMARY 
 
 DIVISION OF 
 
 FOURTH CERVICAL 
 
 BRACHIAL 
 PLEXUS 
 
 PNEUMOGASTRIC 
 
 PHRENIC 
 
 INFERIOR 
 CERVICAL 
 GANGLION 
 INFERIOR 
 LARYNGEAL 
 
 PNEUMOGASTRIO 
 
 rCRICARDIA 
 BRANCH 
 
 NERVE TO 
 
 SUBCLAVIUS 
 
 MUSCLE 
 
 COMMUNICATING 
 
 BRANCH FROM 
 BRACHIAL PLEXUS 
 
 THORACIC CARDIAC 
 BRANCH OF 
 PNEUMOGASTRIC 
 NFERIOR 
 RYNGEAL 
 
 ANTERIOR 
 PULMONARY 
 
 ANTERIOR 
 
 PULMONARY 
 
 PLEXUS 
 
 RAMIFICATIONS 
 OF PHRENIC 
 
 Fig. 636. — The phrenic nerve and its relations with the vagus nerve. (Toldt.) 
 
 The Deep Branches of the Cervical Plexus. External Series. Communicating 
 Branches. — The deep branches of the external series of the cervical plexus com- 
 municate with the spinal accessory nerve, in the substance of the Sterno-mastoid 
 muscle, in the posterior triangle, and beneath the Trapezius. 
 
 Muscular Branches. — Muscular branches are distributed to the Sterno-mastoid, 
 Trapezius, Levator anguli scapulae, and Scalenus medius. 
 
 The branch for the Sterno-mastoid is derived from the second cervical; the 
 Trapezius and Levator anguli scapulae receive branches from the third and fourth. 
 
THE BRACHIAL PLEXUS 
 
 977 
 
 The Scalenus medius is derived sometimes from the third, sometimes the fourth, 
 and occasionally from both nerves. 
 
 Surgical Anatomy.— The cervical plexus may be damaged by wounds or contusions, which 
 may or may not be associated with fracture of the clavicle. Paralysis ensues, the extent depend- 
 ing on the degree of damage. After a contusion the paralysis is apt to be temporary and to 
 be followed by pain and muscular spasm in the arm. Paralysis of the arm due to plexus injury 
 may be partial or com))lete. In some cases there is complete motor palsy and partial sensory 
 palsy, the sensory impulses passing along undamaged collaterals. In certain spasmodic diffi- 
 culties the surgeon occasionally stretches the cervical plexus. It is reached by an incision at the 
 posterior margin of the Sterno-cleido-mastoid muscle. This incision begins two inches below 
 the level of the tip of the mastoid and is carried downward for three inches. 
 
 The Brachial Plexus (Plexus Brachialis) (Figs. 637, 638, 639). 
 
 The brachial plexus is formed by the union of the anterior divisions of the 
 four lower cervical and the greater part of the first dorsal nerves, receiving usually 
 
 ANTERIOR 
 DIVISION OF 
 FOURTH CERVICAL' 
 
 DORSALIS- 
 SCAPULiE 
 
 DESCENDING 
 BRANCH OF 
 HYPOGLOSSAL 
 
 ANSA 
 HYPOGLOSSI 
 
 SUPRASCAPULAR 
 
 ^L^q 
 
 O. l''D« 
 
 ICTORALISi 
 
 FtG. 637. — The right brachial plexus with its short branches, viewed from in front. The sterno-cleido-mastoid 
 and trapezius muscles have been completely, the omohyoid and subclavian have been partially, removed; a piece 
 has been sawed out of the clavicle; the pectoralis muscles have been incised and reflected. (Spalteholz.) 
 
 a fasciculus from the fourth cervical nerve, and frequently one from the second 
 dorsal nerve. It extends from the lower part of the side of the neck to the axilla. 
 It is very broad, and presents little of a plexiform arrangement at its commence- 
 ment. It is narrow opposite the clavicle, becomes broad and forms a more dense 
 interlacement in the axilla, and divides opposite the coracoid process into numer- 
 ous branches for the supply of the upper limb. The nerves which form the plexus 
 are all similar in size, and their mode of communication is subject to considerable 
 variation, so that no one plan can be given as applying to every case. The follow- 
 ing appears, however, to be the most constant arrangement: above the clavicle 
 
 62 
 
978 
 
 THE NERVOUS SYSTEM 
 
 MUSCULOCUTANEOUS 
 NERVE 
 
 INTERCOSTC-HUMERAL 
 NERVES 
 
 LESSER INTERNAL 
 CUTANEOUS NERVES 
 
 LONG SUBSCAPULA 
 NERVE 
 
 SUBSCAPULAR 
 NERVES 
 
 LATERAL CUTA- 
 NEOUS BRANCH 
 OF FOURTH 
 INTERCOSTAL 
 
 LATERAL CUTANEOUS 
 
 BRANCH OF 
 
 THIRD INTERCOSTAL 
 
 LONG THORACIC 
 NERVE 
 
 Fig 638 —The riirht brachial plexus (infraclavicular portion) in the axilliary fossa, viewed from below and in 
 tfront. ' The Pectoralis major and minor muscles have been in large part removed; their attachments have been 
 reflected. (Spalteholz.) 
 
 "VCervical 
 
 Bkomboid 
 
 Subclavian 
 
 O. tetth Phrenic 
 
 VII Oe,rvical 
 
 Sranches to Longua 1/ — ^i^* 
 
 Colli and Scateni 
 
 Anterior division 
 of Middle. Trunk 
 
 J. Dorsal 
 
 Suprascapular 
 
 Upper Trunk 
 
 Middle Trunk 
 
 Anterior division of Upper Trunk 
 
 External Anterior Thoracic 
 Posterior division of Upper Trunk 
 Upper Sub-scapular 
 Middle and Lower 
 Sub-scapular 
 
 Circumflex 
 
 Lower Trunk 
 
 J^)8terior division of Middle Trunk 
 
 Posterior Thoracic' 
 Anterior division of Lower Trunk 
 
 Posterior division of Lower Trunk 
 
 Internal Anterior Thoracic 
 
 Lesser Internal Cutaneous 
 
 Internal Cutaneous 
 
 Musculo-cutaneous 
 
 Muaculo-spiral 
 Fig. 639. — Plan of the brachial plexus. 
 
THE BRACHIAL PLEXUS 
 
 979 
 
 {'pars supraclavicular is) the fifth and sixth cervical unite together soon after their 
 exit from the intervertebral foramina to form a common trunk. The eighth cer- 
 vical and first dorsal also unite to form one trunk. So that the nerves forming 
 the plexus, as they lie on the Scalenus medius external to the outer border of the 
 
 Fig. 640. — Cutaneous nerves of right upper 
 extremity. Anterior view. 
 
 Fig. 641. — Cutaneous nerves of right upper 
 extremity. Posterior view. 
 
 Scalenus anticus muscle, are blended into three trunks — an upper one, formed 
 by the junction of the fifth and sixth cervical nerves; a middle one, consisting 
 of the seventh cervical nerve; and a lower one, formed by the junction of the 
 eighth cervical and first dorsal nerves. As they pass beneath the clavicle, to 
 compose the infraclavicular part of the plexus (pars infraclavicularis), each of 
 
980 
 
 THE NEBVOU8 SYSTEM 
 
 these three trunks divides into two branches, an anterior and a posterior.^ The 
 anterior divisions of the upper and middle trunks then unite to form a common 
 
 cord, which is situated on the 
 outer side of the middle part 
 of the axillary artery, and is 
 called the outer cord of the 
 brachial plexus (fasciculus lat- 
 eralis) . The anterior division 
 of the lower trunk passes 
 down on the inner side of the 
 axillary artery in the middle 
 of the axilla, and forms the 
 inner cord of the brachial plexus 
 {fasciculus medialis) . The 
 posterior divisions of all three 
 trunks unite to form the pos- 
 terior cord of the brachial plexus 
 (fasciculus posterior), which is 
 situated behind the second 
 portion of the axillary artery. 
 From this posterior cord are 
 given off the two lower sub- 
 scapular nerves, the upper 
 subscapular nerve being given 
 off from the posterior division 
 of the upper trunk prior to its 
 junction with the posterior 
 division of the lower and mid- 
 dle trunks. The posterior cord 
 divides into the circumflex 
 and musculo-spiral nerves. 
 
 The brachial plexus com- 
 municates with the cervical 
 plexus by a branch from the 
 fourth to the fifth cervical 
 nerve, and with the phrenic 
 nerve by a branch from the 
 fifth cervical, which joins that 
 nerve on the Anterior scalenus 
 muscle; the fifth and sixth 
 cervical nerves are joined by 
 filaments to the middle cervical 
 ganglion of the sympathetic, 
 the seventh and eighth cervical 
 to its inferior ganglion, and the 
 first dorsal nerve to its first 
 thoracic ganglion. Close to 
 their exit from the interverte- 
 bral foramina the nerves give 
 off the filaments to the ganglia. 
 Relations. — In the neck, the brachial plexus lies in the posterior triangle, being 
 covered by the skin, Platysma, and deep fascia; it is crossed by the posterior belly 
 
 Fig. 642. — Cutaneous nerves of the upper limb, ventral aspect. 
 (W. Keiller, in Gerrish's Text-book of Anatomy.) 
 
 '_ The posterior division of the lower trunk is very much smaller than the others, and is frequently derived 
 entirely from the eighth cervical nerve. — En. of 15th English edition. 
 
 I 
 
THE BRACHIAL PLEXUS 
 
 981 
 
 of the Omo-hyoid muscle and by the transversahs colH artery. When the posterior 
 
 scapular artery arises from the third part of the subclavian it usually passes between 
 
 the roots of the plexus. The plexus lies at first between the Anterior and Middle 
 
 scaleni muscles, and then 
 
 above and to the outer side 
 
 of the subclavian artery; it 
 
 next passes behind the clavicle 
 
 and Subclavius muscle, lying 
 
 upon the first serration of the 
 
 Serratus magnus, and the 
 
 Subscapularis muscles. It is 
 
 in close relation with the apex 
 
 of the lung (Luschka). In the 
 
 axilla it is placed on the outer 
 
 side of the first portion of the 
 
 axillary artery; it surrounds 
 
 the artery in the second part 
 
 of its course, one cord lying 
 
 upon the outer side of that 
 
 vessel, one on the inner side, 
 
 and one behind it, and at the 
 
 lower part of the axillary space 
 
 gives off its terminal branches 
 
 to the upper extremity. 
 
 Branches. — The branches 
 of the brachial plexus are 
 arranged in two groups — viz., 
 those given off above the 
 clavicle, and those below the 
 clavicle. 
 
 Branches above the Clavicle 
 (Figs. 637 and 639).— The 
 branches above the clavicle, 
 from the jpars swpraclavicu- 
 laris, are — the 
 
 Communicating. 
 Muscular. 
 Posterior thoracic. 
 Suprascapular. 
 
 The Communicating Branch 
 
 (Figs. 636 and 639).— The 
 commvmicating branch with 
 the phrenic is derived from the 
 fifth cervical nerve or from 
 the loop between the fifth and 
 sixth; it joins the phrenic on 
 the Anterior scalenus muscle. 
 The communications with the 
 sympathetic have already been 
 referred to. 
 
 The Muscular Branches {rami musculares). — The muscular branches supply the 
 Longus colli, Scaleni, Rhomboidei, and Subclavius muscles. Those for the 
 I^ongus colli and Scaleni arise from the four lower cervical nerves at their exit 
 
 Fig. 643. — Cutaneous nerve of the upper limb, dorsal aspect. 
 (W. Keiller, in Gerrish's Text-book of Anatomy.) 
 
982 
 
 THE NERVOUS SYSTEM 
 
 from the intervertebral foramina. The Rhomboid branch is called the posterior 
 scapular nerve (n. dorsalis scapulae) (Figs. 637 and 639), arises from the fifth 
 
 External anterior thoracic. 
 
 Internal anterior thoracic. 
 
 Musculo - cutaneom. 
 
 Median. 
 
 Musculo-spiral. 
 Posterior 
 
 interosseous. 
 
 Anterior 
 interosseous. 
 
 Fig. 644. — Nerves of the left upper extremity. 
 
THE BRACHIAL PLEXUS 983 
 
 cervical, pierces the Scalenus medius, and passes beneath the Levator anguli 
 scapulae, which it occasionally supplies, to the Rhomboid muscles. The nerve to 
 the Subclavius {n. suhclavius) is a small filament which arises from the fifth cervical 
 at its point of junction with the sixth nerve; it descends in front of the third 
 part of the subclavian artery to the Subclavius muscle, and is usually connected 
 by a filament with the phrenic nerve. 
 
 The Posterior Thoracic, the Long Thoracic, or the External Respiratory Nerve of Bell 
 (n.thoracalis longus) (Figs. 637, 638, 639, and 644). — The posterior thoracic, the 
 long thoracic, or the external respiratory nerve of Bell supplies the Serratus 
 magnus muscle, and is remarkable for the length of its course. It sometimes 
 arises by two roots from the fifth and sixth cervical nerves immediately after 
 their exit from the intervertebral foramina, but generally by three roots from 
 the fifth, sixth, and seventh nerves. These unite in the substance of the Middle 
 scalenus muscle, and, after emerging from it, the nerve passes down behind the 
 brachial plexus and the axillary vessels, resting on the outer surface of the Serratus 
 magnus. It extends along the side of the chest to the lower border of that muscle, 
 supplying filaments to each of the muscular digitations. 
 
 The Suprascapular Nerve (n. suprascapularis) (Figs. 637, 639, and 645). — The 
 suprascapular nerve arises from the cord formed by the fifth and sixth cervical 
 nerves; passing obliquely outward beneath the Trapezius and the Omo-hyoid, it 
 enters the supraspinous fossa below the transverse or suprascapular ligament,, 
 and, passing beneath the Supraspinatiis muscle, curves around the external border 
 of the spine of the scapula to the infraspinous fossa. In the supraspinous fossa 
 it gives of? two branches to the Supraspinatus muscle, and an articular fila- 
 ment to the shoulder-joint; and in the infraspinous fossa it gives ofY two branches 
 to the Infraspinatus muscle, besides some filaments to the shoulder-joint and 
 scapula 
 
 Branches below the Clavicle (Figs. 638 and 639). — The branches below the 
 clavicle, that is, the branches from the pars suhclavicularis of the brachial 
 plexus, are derived from the three cords of the brachial plexus, in the following 
 manner: 
 
 From the Outer Cord. — From the outer cord arise the external anterior thoracic 
 nerve, the musculo-cutaneous, and the outer head of the median. 
 
 From the Inner Cord. — From the inner cord arise the internal anterior thoracic 
 nerve, the internal cutaneous, the lesser internal cutaneous (nerve of Wrisberg), 
 the ulnar, and inner head of the median. 
 
 From the Posterior Cord. — From the posterior cord arise two of the three sub- 
 scapular nerves, the third taking origin from the posterior division of the trunk 
 formed by the fifth and sixth cervical nerves; the cord then divides into the 
 musculo-spiral and circumflex nerves. 
 
 These branches from below the clavicle may be arranged according to the 
 parts they supply: 
 
 To the chest . . . . Anterior thoracic. 
 
 „- , , , , (Subscapular. 
 
 To the shoulder . . . -in- a 
 
 (Circumflex. 
 
 To the arm, forearm, and hand 
 
 Musculo-cutaneous. 
 
 Internal cutaneous. 
 
 Lesser internal cutaneous. 
 
 Median. 
 
 Ulnar. 
 
 Musculo-spiral. 
 
984 THE NERVOUS SYSTEM 
 
 The fasciculi of which these nerves are composed may be traced through the 
 plexus to the spinal nerves from which they originate. They are as follows: 
 
 External anterior thoracic from 5th, 6th, and 7th cervical. 
 Internal anterior thoracic " 8th cervical and 1st dorsal. 
 Subscapular " 5th, 6th, 7th, and 8th cervical. 
 
 Circumflex " 5th and 6th cervical. 
 
 Musculo-cutaneous " 5th and 6th cervical. 
 
 Internal cutaneous " 8th cervical and 1st dorsal. 
 
 Lesser internal cutaneous " 1st dorsal. 
 
 Median " 6th, 7th, and 8th cervical, and 1st dorsal. 
 
 Ulnar " 8th cervical and 1st dorsal. 
 
 Musculo-spiral " 6th, 7th, and 8th cervical, sometimes also 
 
 from the 5th. 
 
 The Anterior Thoracic Nerves {nn. thoracales anteriores) (Figs. 637, 638, and 639). 
 — The anterior thoracic nerves, two in number, supply the Pectoral muscles. 
 
 The External or Superficial Anterior Thoracic Nerve (Figs. 637 and 644) ,the larger 
 of the two, arises from the outer cord of the brachial plexus, through which its 
 fibres may be traced to the fifth, sixth, and seventh cervical nerves. It passes 
 inward, across the axillary artery and vein, pierces the costo-coracoid membrane, 
 and is distributed to the under surface of the Pectoralis major muscle. It sends 
 down a communicating filament to join the internal anterior thoracic nerve, and 
 this communicating filament forms a loop around the inner side of the axillary 
 artery. 
 
 The Internal or Deep Anterior Thoracic Nerve arises fi-om the inner cord, and 
 through it from the eighth cervical and first dorsal nerves. It passes behind 
 the first part of the axillary artery, then curves forward between the axillary 
 artery and vein, and joins with the filament from the anterior nerve. It then 
 passes to the under surface of the Pectoralis minor muscle, where it divides into 
 a number of branches, which supply the muscle on its under surface. Some 
 two or three branches pass through the muscle and reach the Pectoralis major. 
 
 The Subscapular Nerves {nn. svbscapulares) (Figs. 638 and 639). — The sub- 
 scapular nerves arise from the posterior cord of the plexus. There are three 
 subscapular nerves, and they supply the Subscapularis, Teres major, and Latis- 
 siraus dorsi muscles, and give filaments to the shoulder-joint. The fasciculi of 
 which they are composed may be traced to the fifth, sixth, seventh, and eighth 
 cervical nerves. 
 
 The First, Short or Upper Subscapular Nerve, the smallest, arises from the pos- 
 terior division of the upper trunk of origin of the brachial plexus, and enters 
 the upper part of the Subscapularis muscle ; this nerve is frequently represented 
 by two branches. 
 
 The Second or Lower Subscapular Nerve arises from the posterior end of the 
 brachial plexus, enters the axillary border of the Subscapularis and terminates in 
 the Teres major. The latter muscle is sometimes supplied by a separate branch. 
 
 The Third, Middle or Long Subscapular Nerve (n. thoracodorsalis) (Fig. 638) , the 
 largest of the three, arises from the posterior end of the brachial plexus and follows 
 the course of the subscapular artery, along the posterior wall of the axilla to the 
 Latissimus dorsi muscle, through which it may be traced as far as its lower border. 
 
 The Circumflex Nerve (n. axillaris) (Figs. 639 and 645). — The circumflex nerve 
 supplies some of the muscles, the shoulder-joint, and the integument of the shoulder 
 (Figs. 640 and 641) , It arises from the posterior cord of the brachial plexus, in 
 common with the musculo-spiral nerve, and its fibres may be traced through the 
 posterior cord to the fifth and sixth cervical nerves. It is at first placed behind the 
 axillary artery, between it and the Subscapularis muscle, and passes downward 
 
THE BRACHIAL PLEXUS 985 
 
 and outward to the lower border of that muscle. It then winds backward in com- 
 pany with the posterior circumflex artery, through a quadrilateral space bounded 
 above by the Teres minor muscle, below by the Teres major muscle, internally 
 by the long head of the Triceps muscle, and externally by the neck of the humerus. 
 The nerve then divides into two branches. 
 
 The Upper Branch (Fig. 645) winds backward around the surgical neck of the 
 humerus, beneath the Deltoid, with the posterior circumflex vessels, as far as the 
 a.nterior border of that muscle, supplying it, and giving off cutaneous branches, 
 which pierce the muscle and ramify in the integument covering its lower part 
 (Fig. 642). 
 
 The Lower Branch (Fig. 645), at its origin, distributes filaments to the Teres 
 minor and back part of the Deltoid muscles. Upon the filaments to the former 
 muscle an oval enlargement usually exists. The nerve then pierces the deep 
 fascia, and supplies the integument over the lower two-thirds of the posterior 
 surface of the Deltoid (n. cutaneus brachii lateralis), as well as that covering 
 the long head of the Triceps (caput longum n. tricipitis brachii) (Fig. 643). 
 
 The circumflex nerve, before its division, gives off an articular filament, which 
 enters the shoulder-joint below the Subscapularis muscle. 
 
 The Musculo-cutaneous or the External Cutaneous Nerve or the Perforating Nerve 
 of Casserius* (n. musculocutayieus) (Figs. 638, 639, and 644). — ^The musculo- 
 cutaneous, or the external cutaneous nerve, supplies some of the muscles of the 
 arm and the integument of the forearm. It arises from the outer cord of the 
 brachial plexus, opposite the lower border of the Pectoralis minor muscle, 
 receiving filaments from the fifth, sixth, and seventh cervical nerves. It per- 
 forates the Coraco-brachialis muscle (Fig. 644) , passes obliquely between the Biceps 
 and Brachialis anticus muscles to the outer side of the arm, and, a little above 
 the elbow, winds around the outer border of the tendon of the Biceps, and, per- 
 forating the deep fascia, becomes cutaneous (Fig. 640) . This nerve, in its course 
 through the arm, supplies the Coraco-brachialis, Biceps, and the greater part 
 of the Brachialis anticus muscles. The branch to the Coraco-brachialis is given 
 off from the nerve close to its origin, and in some instances, as a separate fila- 
 ment from the outer cord of the plexus. The branches to the Biceps and 
 Brachialis anticus are given off after the nerve has pierced the Coraco-brachialis. 
 The nerve also sends a small branch to the humerus, which enters the nutrient 
 foramen with the accompanying artery, and a filament, from the branch supplying 
 the Brachialis anticus, goes to the elbow-joint. The musculo-cutaneous furnishes 
 the chief nerve supply to this joint. 
 
 The Cutaneous Portion of the Musculo-cutaneous Nerve (n. cutaneiis antibrachii 
 lateralis) passes behind the median cephalic vein, and divides, opposite the 
 elbow-joint, into an anterior and a posterior branch. 
 
 The anterior branch descends along the radial border of the forearm to the 
 wrist, and supplies the integument over the outer half of the anterior surface. At 
 the wrist-joint it is placed in front of the radial artery, and some filaments, piercing 
 the deep fascia, accompany that vessel to the back of the wrist, supplying the 
 carpus. The nerve then passes downward to the ball of the thumb, where it 
 terminates in cutaneous filaments. It communicates with a branch from the radial 
 nerve and with the palmar cutaneous branch of the median. 
 
 The posterior branch passes downward along the back part of the radial side 
 of the forearm to the wrist. It supplies the integument of the lower third of the 
 forearm, communicating with the radial nerve and the external cutaneous branch 
 of the musculo-spiral. The cutaneous areas supplied by the musculo-cutaneous 
 nerve are indicated in Figs. 642 and 643. 
 
 The musculo-cutaneous nerve presents frequent irregularities. It may adhere 
 
 1 See foot-note, page 1027. 
 
986 THE NERVOUS SYSTEM 
 
 for some distance to the median and then pass outward, beneath the Biceps, 
 instead of through the Coraco-brachiaUs. Frequently some of the fibres of the 
 median run for some distance in the musculo-cutaneous and then leave it to join 
 their proper trunk. Less frequently the reverse is the case, and the median sends 
 a branch to join the musculo-cutaneous. Instead of piercing the Coraco-brachialis 
 muscle the nerve may pass under it or through the Biceps. Occasionally it gives a 
 filament to the Pronator radii teres muscle, and it has been seen to supply the 
 back of the thumb when the radial nerve was absent. 
 
 The Internal Cutaneous Nerve (w. cutaneus antihrachii medialis) (Figs. 638, 639, 
 and 644). — ^The internal cutaneous nerve is one of the smallest branches of 
 the brachial plexus. It arises from the inner cord in common with the ulnar 
 nerve and internal head of the median nerve, and, at its commencement, is 
 placed on the inner side of the axillary artery, and afterward of the brachial 
 artery. It derives its fibres from the eighth cervical and first dorsal nerves. 
 It passes down the inner side of the arm, pierces the deep fascia with the 
 basilic vein, about the middle of the limb, and, becoming cutaneous, divides into 
 two branches, anterior and posterior. 
 
 This nerve gives off, near the axilla, a cutaneous filament, which pierces the fascia 
 and supplies the integument covering the Biceps muscle nearly as far as the elbow. 
 This filament lies a little external to the common trunk, from which it arises. 
 
 The anterior branch, the larger of the two, passes usually in front of, but occa- 
 sionally behind, the median basilic vein. It then descends on the anterior surface 
 of the ulnar side of the forearm, distributing filaments to the integument as far 
 as the wrist, and communicating with a cutaneous branch of the ulnar nerve 
 (Fig. 640). 
 
 The posterior branch passes obliquely downward on the inner side of the basilic 
 vein, passes in front of, or over, the internal condyle of the humerus to the back 
 of the forearm, and descends on the posterior surface of its ulnar side ae far as 
 the wrist, distributing filaments to the integument (Fig. 641) . It communicates, 
 above the elbow, with the lesser internal cutaneous nerve, and above the wrist 
 with the dorsal cutaneous branch of the ulnar nerve (Swan). The cutaneous areas 
 supplied by the internal cutaneous nerve are indicated in Figs. 642 and 643. 
 
 The Lesser Internal Cutaneous Nerve or the Nerve of Wrisberg (n. cutaneus 
 brachii medialis) (Figs. 638, 639, and 644). — The lesser internal cutaneous nerve 
 is distributed to the integument on the inner side of the arm. It is the smallest of 
 the branches of the brachial plexus, and, arising from the inner cord, receives 
 its fibres from the first dorsal nerve. It passes through the axillary space, at first 
 lying behind, and then on the inner side of, the axillary vein, and communicates 
 with the intercosto-humeral nerve. It descends along the inner side of the brachial 
 artery to the middle of the arm, where it pierces the deep fascia, and is distributed 
 to the integument of the back part of the lower third of the arm, extending as far 
 as the elbow (Figs. 640, 641, and 642) , where some filaments are lost in the integu- 
 ment in front of the inner condyle, and others over the olecranon. It commu- 
 nicates with the posterior branch of the internal cutaneous nerve. 
 
 In some cases the nerve of Wrisberg and the intercosto-humeral nerve are 
 connected by two or three filaments which form a plexus at the back part of 
 the axilla. In other cases the intercosto-humeral is of large size, and takes the 
 place of the nerve of Wrisberg, receiving merely a filament of communication from 
 the brachial plexus, which filament represents the latter nerve. In other cases 
 this filament is wanting, the place of the nerve of Wrisberg being supplied 
 entirely by the intercosto-humeral. 
 
 The Median Nerve (n. medianus) (Figs. 638, 639, and644).— The median nerve has 
 received its name from the course it takes along the middle of the arm and forearm 
 to the hand, lying between the ulnar and musculo-spiral nerves, and the ulnar and 
 
THE BRACHIAL PLEXUS 987 
 
 the radial nerves. It arises by two roots, one from the outer, and one from the inner, 
 cord of the brachial plexus; these embrace the lower part of the axillary artery, 
 uniting either in front or on the outer side of that vessel. The median nerve 
 receives filaments from the sixth, seventh, and eighth cervical and the first 
 dorsal nerves. As it descends through the arm, it lies at first on the outer side 
 of the brachial artery, crosses that vessel in the middle of its course, usually in 
 front, but occasionally behind it, and lies on its inner side to the bend of the 
 elbow, where it is placed beneath the bicipital fascia, and is separated from the 
 elbow-joint by the Brachialis anticus muscle. In the forearm it passes between 
 the two heads of the Pronor radii teres muscle, and descends beneath the Flexor 
 sublimis muscle, lying on the Flexor profundus muscle, to within two inches 
 above the annular ligament, where it becomes more superficial, lying between the 
 tendons of the Flexor sublimis and Flexor carpi radialis muscles, beneath, and 
 rather to the radial side or under the tendon of the Palmaris longus, covered by 
 the integument and fascia. It then passes through the carpal canal (canalis carpi) 
 beneath the annular ligament into the hand. In its course through the forearm 
 it is accompanied by a branch of the anterior interosseous artery. 
 
 Branches. — With the exception of the nerve to the Pronator radii teres muscle, 
 which sometimes arises above the elbow-joint, and filaments to the elbow-joint, 
 the median nerve gives off no branches in the arm. In the forearm its branches 
 are muscular, anterior interosseous, and palmar cutaneous, and, according to 
 Riidinger and Macalister, two articular twigs to the elbow-joint. 
 
 The Muscular Branches (rami muscular es) supply all the superficial muscles on 
 the front of the forearm except the Flexor carpi ulnar.is. These branches are 
 derived from the nerve near the elbow. 
 
 The Anterior Interosseous (n. interosseus [antibrachii] volaris) (Fig. 644) supplies 
 the deep muscles on the front of the forearm, except the inner half of the Flexor 
 profuntlus digitorum. It accompanies the anterior interosseous artery along the 
 interosseous membrane, in the interval between the Flexor longus pollicis and 
 Flexor profundus digitorum muscles, both of which it supplies, and terminates 
 below in the Pronator quadratus muscle sending filaments to the inferior radio- 
 ulnar articulation and the wrist-joint. 
 
 The Palmar Cutaneous Branch (ramu^ cutaneus palmaris n. mediani) arises from 
 the median nerve at the lower part of the forearm. It pierces the fascia above 
 the annular ligament, and, descending over that ligament, divides into two 
 branches; of which the outer branch supplies the skin over the ball of the thumb, 
 and communicates with the anterior cutaneous branch of the musculo-cutaneous 
 nerve; and the inner branch supplies the integument of the palm of the hand, 
 communicating with the cutaneous branch of the ulnar. 
 
 In the palm of the hand the median nerve is covered by the integument and 
 palmar fascia and is crossed by the superficial palmar arch. It rests upon the 
 tendons of the flexor muscles. In this situation it becomes enlarged, somewhat 
 flattened, of a reddish color, and divides into two branches. Of these, the external 
 branch supplies a muscular branch to some of the muscles of the thumb and 
 digital branches to the thumb and index finger; the internal branch supplies digital 
 branches to the contiguous sides of the index and middle and of the middle and 
 ring fingers. The digital branches, before they subdivide, are called common 
 palmar digital branches of the median nerve {nn. digitales volares communes). 
 
 The branch to the muscles of the thumb (ramus muscularis) is a short nerve which 
 divides to supply the Abductor, Opponens, and the superficial head of the Flexor 
 brevis pollicis muscles, the remaining muscles of this group being supplied by 
 the ulnar nerve. 
 
 The Collateral Palmar Digital or the Digital Branches (nn. digitales volares proprii) 
 are five in number. The first and second pass along the borders of the thumb. 
 
988 THE NERVOUS SYSTEM 
 
 the external branch communicating with branches of the radial nerve. The third 
 passes along the radial side of the index finger, and supplies the First lumbricalis 
 muscle. The fourth subdivides to supply the adjacent sides of the index and 
 middle fingers, and sends a branch to the Second lumbricalis muscle. The fifth 
 supplies the adjacent sides of the middle and ring fingers, and communicates with 
 a branch from the ulnar nerve. 
 
 Each digital nerve, opposite the base of the first phalanx, gives off a dorsal 
 branch, which joins the dorsal digital nerve from the radial nerve and runs along 
 the side of the dorsum of the finger, to end in the integument over the last phalanx. 
 At the end of the finger the digital nerve divides into a palmar and a dorsal branch, 
 the former of which supplies the extremity of the finger, and the latter ramifies 
 around and beneath the nail. The digital nerves, as they run along the fingers, are 
 placed superficial to the digital arteries. The cutaneous areas supplied by the 
 median nerve are shown in Figs. 642 and 643. 
 
 The Ulnar Nerve {n. ulnaris) (Figs. 638, 639, and 644). — The ulnar nerve is 
 placed along the inner or ulnar side of the upper limb, and is distributed to the 
 muscles and integument of the forearm and hand. It is smaller than the median, 
 behind which it is placed, diverging from it in its course down the arm. It arises 
 from the inner cord of the brachial plexus, in common with the inner head of the 
 median and the internal cutaneous nerve, and derives its fibres from the eighth 
 cervical and first dorsal nerves. At its commencement it lies to the inner side of 
 the axillary artery, and holds the same relation with the brachial artery to the 
 middle of the arm. From this point it runs obliquely across the internal head 
 of the Triceps, pierces the internal intermuscular septum, and descends to the 
 groove between the internal condyle and the olecranon, accompanied by the in- 
 ferior profunda artery. At the elbow it rests upon the back of the inner condyle, 
 and passes into the forearm between the two heads of the Flexor carpi ulnaris 
 muscle. In the forearm it descends in a perfectly straight course along th« ulnar 
 side of the extremity, lying upon the Flexor profundus digitorum muscle, its 
 upper half being covered by the Flexor carpi ulnaris muscle, its lower half lying 
 on the outer side of the muscle, being covered by the integument and fascia. 
 The ulnar artery, in the upper third of its course, is separated from the ulnar 
 nerve by a considerable interval, but in the rest of its extent the nerve lies to 
 its inner side. At the wrist the ulnar nerve crosses the annular ligament on the 
 outer side of the pisiform bone, to the inner side of and a little behind the ulnar 
 artery, and immediately beyond this bone divides into two branches, the 
 superficial and the deep palmar. 
 
 Branches. — The branches of the ulnar nerve are — 
 Articular. 
 
 In the forearm J Muscular. j^ ^^^ ^^^^ rSuperficial palmar. 
 
 Cutaneous. (Deep palmar. 
 
 . Dorsal cutaneous. 
 
 The Articular Branches distributed to the elbow-joint consist of several small 
 filaments. They arise from the nerve as it lies in the groove between the inner 
 condyle of the humerus and the olecranon process of the ulnar. 
 
 The Muscular Branches {rami musculares) are two in number — one supplying 
 the Flexor carpi ulnaris; the other, the inner half of the Flexor profundus digi- 
 torum. They arise from the trunk of the nerve near the elbow. 
 
 The Cutaneous Branch arises from the ulnar nerve about the middle of the fore- 
 arm, and divides into two branches. 
 
 One branch (frequently absent) pierces the deep fascia near the wrist, and is 
 distributed to the integument, communicating with a branch of the internal 
 cutaneous nerve. 
 
 The second branch, the palmar cutaneous {ramus cutaneus palmaris) lies on the 
 
THE BRACHIAL PLEXUS 989 
 
 ulnar artery, which it accompanies to the hand, some filaments entwining around 
 the vessel; it ends in the integument of the palm, communicating with branches 
 of the median nerve. 
 
 The Dorsal Cutaneous Branch {ramus dorsalis manus) arises about two inches 
 above the wrist; it passes backward beneath the Flexor carpi ulnaris muscle, 
 perforates the deep fascia, and, running along the ulnar side of the back of the 
 wrist and hand, divides into branches (nn. digitales dorsales) ; one of these sup- 
 plies the inner side of the little finger; a second supplies the adjacent sides of 
 the little and ring fingers; a third joins the branch of the radial nerve which 
 supplies the adjoining sides of the middle and ring fingers, and assists in sup- 
 plying these parts; a fourth is distributed to the metacarpal region of the hand, 
 communicating with a branch of the radial nerve. 
 
 On the little finger the dorsal digital branches extend only as far as the base 
 of the terminal phalanx, and on the ring finger as far as the base of the second 
 phalanx; the more distal parts of these digits are supplied by dorsal branches 
 derived from the palmar digital branches of the ulnar. 
 
 The Superficial Palmar Branch [ramus superficialis n. ulnaris) supplies the 
 Palmaris brevis and the integument on the inner side of the hand, and terminates 
 in two digital branches, which are distributed, one to the ulnar side of the little 
 finger, the other to the adjoining sides of the little and ring fingers, the latter 
 communicating with a branch from the median. The digital branches are dis- 
 tributed to the fingers in the same manner as the digital branches of the median. 
 
 The Deep Palmar Branch (ramus jyrojundus n. ulnaris), accompanied by the 
 deep branch of the ulnar artery, passes between the Abductor and Flexor brevis 
 minimi digiti muscles; it then perforates the Opponens minimi digit! and follows 
 the course of the deep palmar arch beneath the flexor tendons. At its origin it 
 supplies the muscles of the little finger. As it crosses the deep part of the hand 
 it sends two branches to each interosseous space, one for the Dorsal and one for 
 the Palmar interosseous muscle, the branches to the Second and Third palmar 
 interossei supplying filaments to the two inner Lumbrical muscles. At its ter- 
 mination between the thumb and index finger, it supplies the Adductores trans- 
 versus et obliquus pollicis and the inner head of the Flexor brevis pollicis. It also 
 sends articular filaments to the wrist-joint, and to the bones and joints of the hand. 
 
 It will be remembered that the inner part of the Flexor profundus digitorum 
 muscle is supplied by the ulnar nerve; the two inner Lumbricales, which are 
 connected with the tendons of this part of the muscle, are therefore supplied by 
 the same nerve. The outer part of the Flexor profundus is supplied by the 
 median nerve; the two outer Lumbricales, which are connected with the tendons 
 of this part of the muscles, are therefore supplied by the same nerve. Brooks 
 states that in twelve instances out of twenty-one he found that the third lum- 
 brical received a twig from the median nerve, in addition to its branch from the 
 ulnar. The palmar branches of the ulnar which go to the fingers are called by 
 Toldt before division common palmar digital branches, and after division collateral 
 palmar digital branches. The cutaneous areas supplied by the ulnar nerve are 
 shown in Figs. 642 and 643. 
 
 The Musculo-spiral Nerve {n. radialis) (Figs. 639, 644, and 645). — The musculo- 
 spiral nerve, the largest branch of the brachial plexus, supplies the muscles of the 
 back part of the arm and forearm, and the integument of the same parts, as well as 
 that of the back of tlie hand (Figs. 642 and 643) . It arises from the posterior cord of 
 the brachial plexus, of which it maybe regarded as the continuation. It receives fila- 
 ments from the sixth, seventh, and eighth, and sometimes also from the fifth cervical 
 nerves. At its commencement it is placed behind the axillary artery and the upper 
 part of the brachial artery, passing down in front of the tendons of the Latissimus 
 dorsi and Teres major muscles. It winds around the humerus in the musculo-spiral 
 
990 
 
 THE NERVOUS SYSTEM 
 
 SuprascapuCar. 
 
 Circumflex. 
 
 groove with the superior profunda artery, passing from the inner to the outer side 
 of the bone, between the internal and external heads of the Triceps muscle (Fig. 
 645). It pierces the external intermuscular septum, and descends between the 
 
 Brachialis anticus and Supi- 
 nator longus muscles to the 
 front of the external condyle 
 of the humerus, where it sends 
 filaments to the elbow-joint 
 and divides into the radial and 
 posterior interosseous nerves. 
 
 Branches. — The branches of 
 the musculo-spiral nerve are — 
 Muscular. 
 Cutaneous. 
 Radial. 
 
 Posterior interosseous. 
 The Muscular Branches (rami 
 muscular es n. radialis) are di- 
 vided into internal, posterior, 
 and external; they supply the 
 Triceps, Anconeus, Supinator 
 longus. Extensor carpi radialis 
 longior, and Brachialis anticus 
 muscles. These branches are 
 derived from the nerve at the 
 inner side, back part, and outer 
 side of the arm. 
 
 The internal muscular branches 
 supply the inner and middle 
 heads of the Triceps muscle. 
 That to the inner head of the 
 Triceps is a long, slender fila- 
 ment which lies close to the 
 ulnar nerve, as far as the lower 
 third of the arm, and is there- 
 fore frequently spoken of as the 
 ulnar collateral branch. 
 
 The posterior muscular branch, 
 of large size, arises from the 
 nerve in the groove between the 
 Triceps muscle and the hu- 
 merus. It divides into branches 
 which supply the outer and in- 
 ner heads of the Triceps and 
 the Anconeus muscles. The 
 branch for the latter muscle is 
 a long, slender filament which 
 descends in the substance of 
 the Triceps to the Anconeus. 
 The external muscular branches supply the Supinator longus. Extensor carpi 
 radialis longior, and (usually) the outer part of the Brachialis anticus muscles. 
 The Cutaneous Branches are three in number, one internal and two external. 
 The internal cutaneous branch (n. cutaneus hrachii posterior) arises in the axil- 
 lary space with the inner muscular branch. It is of small size, and passes through 
 
 Fig. 645. — The suprascapular, circumflex, and musculo-spiral 
 nerves. 
 
THE BRACHIAL PLEXUS 991 
 
 the axilla to the inner side of the arm, supplying the integument on its posterior 
 aspect nearly as far as the olecranon. In its course it crosses beneath the inter- 
 costo-humeral nerve, with which it communicates. 
 
 The external cutaneous branch {n. cutaneus antibrachii dorsalis) divides into two 
 branches, and each one perforates the outer head of the Triceps muscle at its 
 attachment to the humerus. The upper and smaller one passes to the front of the 
 elbow, lying close to the cephalic vein, and supplies the integument of the lower half 
 of the arm on its anterior aspect. The lower branch pierces the deep fascia below 
 the insertion of the Deltoid muscle, and passes down along the outer side of the 
 arm and elbow, and then along the back part of the radial side of the forearm to 
 the wrist, supplying the integument in its course, and joining, near its termination, 
 with the posterior cutaneous branch of the musculo-cutaneous nerve. 
 
 The Radial Nerve (ramus superficialis n. radialis) (Fig. 644) , passes along the front 
 of the radial side of the forearm to the commencement of its lower third. It lies at 
 first a little to the outer side of the radial artery, concealed beneath the Supinator 
 longus muscle. In the middle third of the forearm it lies beneath the same 
 muscle, in close relation with the outer side of the artery. It leaves the artery 
 about three inches above the wrist, passes beneath the tendon of the Supinator 
 longus muscle, and, piercing the deep fascia at the outer border of the forearm, 
 divides into two branches. 
 
 The external branch, the smaller of the two, supplies the integument of the 
 radial side and ball of the thumb, joining with the anterior branch of the musculo- 
 cutaneous nerve. 
 
 The internal branch communicates, above the wrist, with the posterior cuta- 
 neous branch from the musculo-cutaneous, and on the back of the hand forms an 
 arch with the dorsal cutaneous branch of the ulnar nerve. It then divides into 
 four digital nerves (nn. digitales dorsales), which are distributed as follows: The 
 first supplies the ulnar side of the thumb; the second, the radial side of the index 
 finger; the third, the adjoining sides of the index and middle fingers; and the 
 fourth, the adjacent borders of the middle and ring fingers.^ The latter nerve 
 communicates with a filament from the dorsal branch of the ulnar nerve. 
 
 The Posterior Interosseous Nerve {ramus 'profundus n. radialis) (Figs. 644 and 
 645) . — ^The posterior interosseous nerve winds to the back of the forearm around 
 the outer side of the radius, passes between the two planes of fibres of the Supinator 
 brevis muscle, and is prolonged downward between the superficial and deep layer 
 of muscles, to the middle of the forearm. Considerably diminished in size, it 
 descends on the interosseous membrane, beneath the Extensor longus pollicis 
 muscle, to the back of the carpus, where it presents a gangliform enlargement 
 from which filaments are distributed to the inferior radio-ulnar articulation, to 
 the wrist -joint, and to the ligaments and articulations of the carpus. It supplies all 
 the muscles of the radial and posterior brachial regions, excepting the Anconeus, 
 Supinator longus, and Extensor carpi radialis longior. 
 
 Surgical Anatomy, — The brachial plexus may be ruptured by traction on the limb, leading 
 to complete paralysis. Bristow'* has reported three cases of avulsion of the plexus and has 
 described twenty-four cases. In these cases it is generally believed that the lesion is rather a 
 tearing away of the nerves from the spinal cord than a solution of continuity of the nerve-fibres 
 themselves. In a case operated upon by Bristow it was found that the plexus had given way 
 where the four cervical nerves and the first dorsal nerve unite to form three trunks. In supraclavic- 
 ular division of the brachial plexus, not only will there be motor and sensory paralysis in the limb, 
 but the Serratus magnus muscle will probably be paralyzed, because of injury to the posterior 
 thoracic nerve. In the axilla any of the nerves forming the brachial plexus may be injured by a 
 wound of this part, the median being the one which is most frequently damaged from its exposed 
 
 ' According to Hutchinson, the digital nerve to the thumb reaches only as high as the root of the nail; the 
 one to the forefinger as high as the middle of the second phalanx, and the one to the middle and ring fingers not 
 higher than the first phalangeal joint (London Hospital Gazette, vol. iii. p. 319). — Ed. of 15th English edition. 
 
 ^ Annals of Surgery, September, 1902. 
 
992 
 
 THE NERVOUS SYSTEM 
 
 position. The musculo-spiral, on account of its sheltered and deep position, is least often 
 wounded. The brachial plexus in the axilla is often damaged from the pressure of a crutch, pro- 
 ducing the condition known as crutch paralysis. In these cases the musculo-spiral is the nerve most 
 frequently implicated; the ulnar nerve being the one that appears to suffer next in frequency. 
 
 The circumflex nerve is of particular surgical interest. On account of its course around the 
 surgical neck of the humerus, it is liable to be torn in fractures of this part of the bone, and 
 in dislocations of the shoulder-foint, leading to paralysis of the deltoid, and, according to Erb, 
 inflammation of the shoulder-joint is liable to be followed by a neuritis of this nerve from extension 
 of the inflammation to it. 
 
 Mr. Hilton takes the circumflex nerve as an illustration of a law which he lays down, that 
 "the same trunks of nerves whose branches supply the groups of muscles moving a joint furnish 
 also a distribution of nerves to the skin over the insertions of the same muscles, and the interior 
 of the joint receives its nerves from the same source." In this way he explains the fact that an 
 inflamed joint becomes rigid, because the same nerves which supply the interior of the joint 
 supply the muscles which move that joint. 
 
 The median nerve is liable to injury in wounds of the forearm. When paralyzed, there is 
 loss of flexion of the second phalanges of all the fingers and of the terminal phalanges of the 
 index and middle fingers. Flexion of the terminal phalanges of the ring and middle fingers can 
 still be effected by that portion of the Flexor profundus digitorum which is supplied by the ulnar 
 nerve. There is power to flex the proximal phalanges through the Interossei. The thumb 
 cannot be flexed or opposed, and is maintained in a position of extension and adduction. All 
 power of pronation is lost. The wrist can be flexed, if the hand is first adducted, by the action 
 of the Flexor carpi ulnaris. There is loss or impairment of sensation on the palmar surface 
 of the thumb, index, middle, and outer half of the ring fingers, and on the dorsal surface of the 
 same fingers over the last two phalanges; except in the thumb, where the loss of sensation is 
 limited to the back of the last phalanx. In order to expose the median nerve for the purpose 
 of stretching it an incision should be made along the radial side of the tendon of the Palmaris 
 longus muscle, which serves as a guide to the nerve. 
 
 The ulnar nerve is liable to be injured in wounds of the forearm. When paralyzed, there 
 is loss of power of flexion in the ring and little fingers; there is impaired power of ulnar 
 flexion and adduction of the hand; there is inability to spread out the fingers from paralysis of 
 the Interossei; and there is inability to adduct the thumb. The fingers cannot be flexed at the 
 first joints, and cannot be extended at the other joints. A claw-hand develops, the first pha- 
 langes being overextended and the others flexed. Sensation is lost or impaired in the skin of the 
 ulnar side of the hand anteriorly and posteriorly, involving the little finger, the ring finger, and 
 the ulnar half of the middle finger posteriorly, and anteriorly involving the little finger and the 
 ulnar half of the ring finger. In order to expose the nerve in the lower part of the forearm, 
 an incision should be made along the outer border of the tendon of the Flexor carpi ulnaris, and 
 the nerve will be found lying on the ulnar side of the ulnar artery. 
 
 The musculo-spiral nerve is probably more frequently injured than any other nerve of the 
 upper extremity. In consequence of its close relationship to the humerus as it lies in the 
 musculo-spiral groove, it is frequently torn or injured in fractures of this bone, or subsequently 
 involved in the callus that may be thrown out around a fracture, and thus pressed upon and its 
 functions interfered with. It is also liable to be squeezed against the Vjone by kicks or blows and 
 it may be divided by wounds of the arm. When paralyzed, the hand is flexed at the wrist 
 and lies flaccid. This condition is known as drop-wrist. The fingers are also flexed, and on 
 an attempt being made to extend them the last two phalanges only will be extended through the 
 action of the Interossei, the first phalanges remaining flexed. There is no power of extending 
 the wrist. Supination is completely lost when the forearm is extended on the arm, but is 
 possible to a certain extent if the forearm is flexed so as to allow of the action of the Biceps. 
 The power of extension of the forearm is lost on account of paralysis of the Triceps. liOss of 
 sensation may be considerable or slight. Its area is shown in Fig. 643. The best position in 
 which to expose the nerve for the purpose of stretching is to make an incision along the inner border 
 of the Supinator longus muscle, just above the level of the elbow-joint. The skin and superficial 
 structures are to be divided and the deep fascia exposed. The white line in this structure indicat- 
 ing the border of the muscle is to be defined, and the deep fascia divided in this line. By now raising 
 the Supinator longus the nerve will be found lying beneath it, on the Brachialis anticus muscle. 
 
 Post-anoEsthetic paralysis. When a person emerges from the influence of a general anesthetic 
 palsy of the arm may be found to exist. The brachial plexus may have been compressed during 
 the operation by drawing the arm strongly from the body or elevating it by the side of the 
 head. In such a case the plexus was compressed by the head of the humerus (Braun). 
 
 The median nerve is stretched when the arm is rotated externally and drawn backward and 
 outward. The ulnar nerve is stretched when the forearm is flexed and supinated (Braun). 
 Garrigues believes that in most cases of post-anjesthetic paralysis the brachial plexus was squeezed 
 between the collar bone and the first rib by the head of the patient being drawn to the opposite 
 side or being allowed to fall back. 
 
ANTERIOR DIVISIONS OF THORACIC OR DORSAL NERVES 993 
 
 THE THORACIC OR DORSAL NERVES (NN. THORACALES.) 
 
 The thoracic or dorsal nerves are twelve in number on each side. The first 
 appears between the first and second dorsal vertebrae, and the last between the 
 last dorsal and first lumbar. 
 
 The Roots of the Thoracic or Dorsal Nerves. 
 
 The roots of the thoracic or dorsal nerves are of small size, and vary but slightly 
 from the second to the last. Both roots are very slender, the posterior roots 
 slightly exceeding the anterior in thickness. They gradually increase in length 
 from above downward, and in the lower part of the dorsal region pass down in 
 contact with the spinal cord for a distance equal to the height of at least two ver- 
 tebrae, before they emerge from the spinal canal. They then join in the inter- 
 vertebral foramen, and at their exit divide into two primary divisions, a posterior 
 (dorsal) and an anterior (intercostal). 
 
 The Posterior Divisions of the Thoracic or Dorsal Nerves (Rami Posteriores) 
 
 (Fig. 646). 
 
 The posterior divisions of the thoracic or dorsal nerves are smaller than the 
 anterior, pass backward between the transverse processes, and divide into interna! 
 and external branches. 
 
 Each internal branch is called a ramus medialis ; each external branch is called 
 a ramus lateralis. 
 
 The Internal Branches. — The internal branches of the six upper nerves pass 
 inward between the Semispinalis dorsi and INIultifidus spinae muscles, which they 
 supply, and then, piercing the origins of the Rhomboidei and Trapezius muscles, 
 become cutaneous by the side of the spinous processes and ramify in the integu- 
 ment. The internal branches of the six lower nerves are distributed to the 
 Multififlus spinae, without giving off any cutaneous filaments. 
 
 The External Branches. — The external branches increase in size from above 
 downward. They pass through the Longissimus dorsi muscle to the cellular 
 interval between it and the Iliocostalis muscle, and supply those muscles, as well 
 as their continuations upward to the head, and also the Ijcvatores costarum 
 muscles; the five or six lower nerves also give off cutaneous filaments, which pierce 
 the Serratus posticus inferior and Latissimus dorsi muscles in a line with the 
 angles of the ribs, and then ramify in the integument. 
 
 The Cutaneous Branches.— The cutaneous branches of the posterior primary 
 divisions of the dorsal nerves are twelve in number. From each ramus medialis 
 of the upper six nerves comes a ramies cutaneus medialis, and from each ramus 
 lateralis of the lower six nerves comes a ramus cutaneus lateralis. The six upper 
 cutaneous nerves are derived from the internal branches of the posterior divisions 
 of the dorsal nerves. They pierce the origins of the Rhomboidei and Trapezius 
 muscles, and become cutaneous by the side of the spinous processes, and then 
 ramify in the integument. They are frequently furnished with gangliform enlarge- 
 ments. The six lower cutaneous nerves are derived from the external branches 
 of the posterior divisions of the dorsal nerves. They pierce the Serratus posticus 
 inferior and Latissimus dorsi mugcles in a line with the angles of the ribs, and 
 then ramify in the integument. 
 
 The Anterior Divisions of the Thoracic or Dorsal Nerves or the Intercostal 
 
 Nerves (Rami Anteriores). 
 
 The anterior divisions of the dorsal nerves or the intercostal nerves {nn. inter- 
 costales) are twelve in number on each side. They are, for the most part, 
 
 63 
 
994 
 
 THE NERVOUS SYSTEM 
 
 distributed to the parietes of the thorax and abdomen, separately from each 
 other, without being joined in a plexus; in which respect they differ from the 
 
 Fig. 646. — Superficial and deep distribution of the posterior divisions of the spinal nerves. (After Hirschfeld 
 and Leveill6.) On the left side the cutaneous branches are represented lying on the sunerficial layer of muscles. 
 On the right side the superficial muscles have been removed, the Splenius capitis and Complexus divided in the 
 neck, and the Erector spinae divided and partly removed in the back, so as to expose the posterior divisions of 
 the spinal nerves near their origin, a a. Lesser occipital nerve from the cervical plexus. 1. External muscular 
 branches of the first cervical nerve, and union by a loop with the second. 2, placed on the Rectus capitis 
 posticus major muscle, marks the great occipital nerve, passing round the short muscles and piercing the Com- 
 plexus : the external branch is seen to the outside. 3. External branch from the posterior division of the third 
 nerve. 3'. Its internal branch, sometimes called the third occipital. 4' to 8'. The internal branches of the 
 several corresponding nerves on the left side. The external branches of these nerves, proceeding to muscles, 
 are displayed on the right .side, d 1 to rf 6, and thence to d 12. External muscular branches of the posterior 
 divisions of the twelve dorsal nerves on the right side, i^ 1' to d 6'. The internal cutaneous branches of the six 
 upper dorsal nerves on the left side, d 7' to d 12'. Cutaneous twigs from the external branches of the six lower 
 dorsal nerves. 1 1. External branches from the posterior divisions of several lumbar nerves on the right side, 
 piercing the muscles, the lower descending over the gluteal region V I'. The same, more superficially, on the 
 left side, 8 8. The issue and union by loops of the posterior divisions of four sacral nerves on the right side 
 « s'. Some of those distributed to the skin on the left side. 
 
ANTERIOR DIVISIONS OF THORACIC OR DORSAL NERVES 995 
 
 other spinal nerves. Each nerve is connected with the adjoining ganglion of the 
 sjrmpathetic by one or two filaments {ramus communicans) . The intercostal nerves 
 may be divided into two sets, from the difference they present in their distribution. 
 The six upper, with the exception of the first and the intercosto-humeral branch 
 of the second, are limited in their distribution to the parietes of the chest. The 
 six lower supply the parietes of the chest and abdomen, the last one sending a 
 cutaneous filament to the buttock. 
 
 The Anterior Division of the First Thoracic or First Dorsal Nerve. — 
 The anterior division of the first dorsal nerve divides into two branches: one, the 
 larger, leaves the thorax in front of the neck of the first rib, and enters into the 
 formation of the brachial plexus ; the other and smaller branch runs along the first 
 intercostal space, forming the first intercostal nerve (n. intercostalis I), giving off 
 muscular branches, and terminates on the front of the chest by forming the first 
 anterior cutaneous nerve (ramus cutaneus anterior n. intercostalis I) of the thorax. 
 Occasionally this anterior cutaneous branch is wanting. The first intercostal 
 nerve, as a rule, gives off no lateral cutaneous branch, but sometimes a small 
 branch is given off which communicates with the intercosto-humeral. It frequently 
 receives a connecting twig from the second dorsal nerve, which passes upward 
 over the neck of the second rib. 
 
 The Anterior Divisions of the Upper Thoracic or Dorsal Nerves (nn. 
 intercostales) (Fig. 646). — ^The anterior divisions of the second, third, fourth, fifth, 
 and sixth dorsal nerves and the small branch from the first dorsal are confined to 
 the parietes of the thorax, and are named upper or pectoral intercostal nerves. 
 They pass forward in the intercostal spaces with the intercostal vessels, being 
 situated below them. At the back of the chest they lie between the pleura and 
 the External intercostal muscle, but are soon placed between the two planes cf 
 Intercostal muscles as far as the middle of the rib. They then enter the sub- 
 stance of the Internal intercostal muscles, and, running amidst their fibres as far 
 as the costal cartilages, they gain the inner surface of the muscles and lie 
 between them and the pleura. Near the sternum, they cross in front of the internal 
 mammary artery and Triangularis sterni muscle, pierce the Internal intercostal 
 muscles, the anterior intercostal membrane, and Pectoralis major muscle, and 
 supply the integument of the front of the chest and over the mammary gland, 
 forming the anterior cutaneous nerves of the thorax; the branch from the second 
 nerve is joined with the supraclavicular nerves of the cervical plexus. 
 
 Branches. — Numerous slender muscular filaments (rami musculares) supply the 
 Intercostals, the Infracostales, the Levatores costarum, Serratus posticus superior, 
 and Triangularis sterni muscles. Some of these branches, at the front of the chest, 
 cross the costal cartilages from one to another intercostal space. 
 
 Lateral Cutaneous Nerves of the Thorax (rami cutanei laterales [j)ectorales\j (Fig. 
 638). — These are derived from the intercostal nerves, midway between the vertebrae 
 and sternum; they pierce the External intercostal and Serratus magnus muscles, 
 and divide into two branches, anterior and posterior. 
 
 The Anterior Branches (rami anteriores) are reflected forward to the side and the 
 forepart of the chest, supplying the integument of the chest and mamma; those 
 of the fifth and sixth nerves supply the upper digitations of the External oblique 
 muscle. 
 
 The Posterior Branches (rami posteriores) are reflected backward to supply the 
 integument over the scapula and over the lyatissimus dorsi muscle. 
 
 The Lateral Cutaneous Branch of the Second Intercostal Nerve (n. intercosto- 
 brachialis) is of large size, and does not divide, like the other nerves, into an 
 anterior and posterior branch. It may unite with a branch of the third intercostal. 
 The single nerve or the unitefl nerve is named, from its origin and distribution, the 
 intercosto-humeral nerve (Figs. 638 and 644). It pierces the External intercostal 
 
996 THE NERVOUS SYSTEM 
 
 muscle, crosses the axilla to the inner side of the arm, and joins with a filament from 
 the nerve of Wrisberg. It then pierces the fascia, and supplies the skin of the upper 
 half of the inner and back part of the arm (Figs. 642 and 643), communicating 
 with the internal cutaneous branch of the musculo-spiral nerve. The size of this 
 nerve is in inverse proportion to the size of the other cutaneous nerves, especially 
 the nerve of Wrisberg. A second intercosto-humeral nerve is frequently given off 
 from the third intercostal. It supplies filaments to the armpit and inner side of 
 the arm. It may or may not send a branch to the intercosto-humeral. 
 
 The Anterior Divisions of the Lower Thoracic or Dorsal Nerves. — The 
 anterior divisions of the seventh, eighth, ninth, tenth, and eleventh dorsal nerves 
 are continued anteriorly from the intercostal spaces into the abdominal wall, and 
 the twelfth dorsal is continued throughout its whole course in the abdominal wall, 
 since it is placed below the last rib; hence these nerves are named lower or abdom- 
 inal intercostal nerves. They have (with the exception of the last) the same arrange- 
 ment as the upper ones as far as the anterior extremities of the intercostal spaces, 
 where they pass behind the costal cartilages, and between the Internal oblique and 
 Transversalis muscles, to the sheath of the Rectus, which they perforate. They 
 supply the Rectus muscle, and terminate in branches which become subcutaneous 
 near the linea alba. These branches are named the anterior cutaneous nerves of 
 the abdomen. They are directed outward as far as the lateral cutaneous nerves, 
 supplying the integument of the front of the belly. The lower intercostal nerves 
 supply the Intercostals, Serratus posticus inferior, and Abdominal muscles, and, 
 about the middle of their course, give off lateral cutaneous branches which pierce 
 the External intercostal and External oblique muscles, in the same line as the 
 lateral cutaneous nerves of the thorax, and divide into anterior and posterior 
 branches, which are distributed to the integument of the abdomen and back; the 
 anterior branches supply the digitations of the External oblique muscle and extend 
 downward and forward nearly as far as the margin of the Rectus muscle; the 
 posterior branches pass backward to supply the skin over the Latissimus dorsi 
 muscle. 
 
 The Last Thoracic or Dorsal Nerve. — The last dorsal is larger than the other 
 dorsal nerves. Its anterior division runs along the lower border of the last rib, 
 and passes under the external arcuate ligament of the Diaphragm. It then runs 
 in front of the Quadratus lumborum muscle, perforates the Transversalis muscle, 
 and passes forward between it and the Internal oblique muscle, to be distributed 
 in the same manner as the lower intercostal nerves. It communicates with the 
 ilio-hypogastric branch of the lumbar plexus, and is frequently connected with 
 the first lumbar nerve by a slender branch, the dorsi-lumbar nerve, which descends 
 in the substance of the Quadratus lumborum muscle. It gives a branch to the 
 Pyramidalis muscle. 
 
 The Cutaneous Branches. — ^There are two cutaneous branches, an anterior and 
 a lateral. 
 
 The Anterior Cutaneous Branch is a terminal branch and is a direct prolongation 
 from the intercostal. It supplies an area of skin of the abdominal wall between 
 the umbilicus and pubis. 
 
 The Lateral Cutaneous Branch {ramu^s cutaneus lateralis [abdominalis] inter- 
 costalis XII) is remarkable for its large size; it perforates the Internal and Exter- 
 nal oblique muscles, passes downward over the crest of the ilium in front of the 
 iliac branch of the ilio-hypogastric, and is distributed to the integument of the 
 front part of the gluteal region, some of its filaments extending as low down as 
 the trochanter major. It does not divide into an anterior and a posterior branch, 
 like the other lateral cutaneous branches of the intercostal nerves. 
 
 Surgical Anatomy. — The lower seven intercostal nerves and the ilio-hypogastric from the 
 first lumbar nerve supply the skin of the abdominal wall. They run downward and inward j 
 
I 
 
 POSTERIOR DIVISIONS OF THE LUMBAR NERVES 997 
 
 fairly equidistant from each other. The sixth and seventh supply the skin over the "pit of the 
 stomach;" the eighth corresponds to about the position of the middle linea transversa; the 
 tenth to the umbilicus; and the ilio-hypogastric supplies the skin over the pubes and external 
 abdominal ring. There are several points of surgical significance about the distribution of these 
 nerves, and it is important to remember their origin and course, for in many diseases affecting 
 the nerve-trunks at or near their origin the pain is referred to their peripheral terminations. Thus 
 in Pott's disease of the spine children will often be brought to the surgeon suffering from pain 
 in the belly. This is due to the fact that the nerves are irritated at the seat of disease as they 
 issue from the spinal canal. When the irritation is confined to a single pair of nerves, the sen- 
 sation complained of is often a feeling of constriction, as if a cord were tied around the abdomen; 
 and in these cases the situation of the sense of constriction may serve to localize the disease in 
 the spinal column. In other cases, where the bone disease is more extensive and two or more 
 nerves are involved, a more diffused pain in the abdomen is complained of. A similar conditon 
 is sometimes present in affections of the cord itself, as in tabes dorsalis. 
 
 Again, it must be borne in mind that the same nerves which supply the skin of the abdomen 
 supply also the muscles which constitute the greater part of the abdominal wall. Hence, it follows 
 that any irritation applied to the peripheral terminations of the cutaneous branches in the 
 skin of the abdomen is immediately followed by reflex contraction of the abdominal muscles. 
 A good practical illustration of this may sometimes be seen in watching two surgeons examine 
 the abdomen of the same patient. One, whose hand is cold, causes the muscles of the abdom- 
 inal wall to at once contract and the belly to become rigid, and thus not nearly so suitable 
 for examination; the other, who has taken the precaution to warm his hand, examines the 
 abdomen without exciting any reflex contraction. The supply of both muscles and skin from 
 the same source is of importance in protecting the abdominal viscera from injury. A blow 
 on the abdomen, even of a severe character, will do no injury to the viscera if the muscles are 
 in a condition of firm contraction; whereas in cases where the muscles have been taken unawares, 
 and the blow has been struck while they were in a state of rest, an injury insufficient to produce 
 any lesion of the abdominal wall has been attended with rupture of some of the abdominal con- 
 tents. The importance, therefore, of immediate reflex contraction upon the receipt of an injury 
 cannot be overestimated, and the intimate association of the cutaneous and muscular fibres in 
 the same nerve produces a much more immediate response on the part of the muscles to any 
 peripheral stimulation of the cutaneous filaments than would be the case if the two sets of fibres 
 were derived from independent sources. 
 
 Again, the nerves supplying the abdominal muscles and skin are derive'd from the lower inter- 
 costal nerves and are intimately connected with the sympathetic supplying the abdominal viscera 
 through the lower thoracic ganglia from which the splanchnic nerves are derived. In conse- 
 quence of this, in rupture of the abdominal viscera and in acute peritonitis the muscles of the 
 belly-wall become firmly contracted, and thus as far as possible preserve the abdominal contents 
 in a condition of rest. 
 
 THE LUMBAR NERVES (NN. LUMBALES). 
 
 The lumbar nerves are five in number on each side. The first lumbar nerve 
 appears l)etween the first and second lumbar vertebrae, and the last between the 
 last lumbar vertebra and the base of the sacrum. 
 
 The Roots of the Lumbar Nerves. 
 
 The roots of the lumbar nerves are the largest, and their filaments the most 
 numerous, of all the spinal nerves, and they are closely aggregated together upon 
 the lower end of the cord. The anterior roots are the smaller, but there is not the 
 same disproportion between them and the posterior roots as in the cervical nerves. 
 The roots of these nerves have a vertical direction, and are of considerable length, 
 more especially the lower ones, since the spinal cord does not extend beyond the 
 first lumbar vertebra. The roots become joined in the intervertebral foramina, and 
 the nerves so formed divide at their exit into two divisions, posterior and anterior. 
 
 The Posterior Divisions of the Lumbar Nerves (Rami Posteriores) (Fig. 646). 
 
 The posterior divisions of the lumbar nerves diminish in size from above down- 
 ward; they pass backward between the transverse processes, and divide into 
 internal and external branches. 
 
998 
 
 THE NERVOUS SYSTEM 
 
 The Internal Branches {rami mediales). — The internal branches, the smaller, 
 pass inward close to the articular processes of the vertebrae, and supply the 
 Multifidus spinae and Interspinales muscles. 
 
 The External Branches {rami laterales). — ^The external branches supply the 
 Erector spinae and Intertransverse muscles. From the three upper branches 
 cutaneous nerves are derived M^hich pierce the aponeurosis of the Latissimus dorsi 
 muscle and descend over the back part of the crest of the ilium, to be distributed 
 to the integument of the gluteal region, some of the filaments passing as far as the 
 trochanter major (Fig. 652). 
 
 The posterior division of the fifth lumbar nerve usually sends a branch which 
 forms a loop with the posterior division of the first sacral nerve. 
 
 The Anterior Divisions of the Lumbar Nerves (Rami Anteriores). 
 
 The anterior divisions of the lumbar nerves increase in size from above down- 
 ward. At their origin they communicate with the lumbax ganglia of the sym- 
 pathetic by long, slender filaments, which accompany the lumbar arteries around 
 the sides of the bodies of the vertebrae, beneath the Psoas muscle. The nerves pass 
 obliquely outward behind the Psoas magnus or between its fasciculi, distributing 
 filaments to it and the Quadratus lumborum. The anterior divisions of the five 
 lumbar, five sacral, and first coccygeal nerve constitute the lumbo-sacral plexus 
 {plexus lumhosacralis). This is subdivided into the lumbar plexus, the sacral 
 plexus, and the pudendal plexus. The anterior divisions of the four upper nerves 
 are connected together in this situation by anastomotic loops, and form the lumbar 
 plexus. The anterior division of the fifth lumbar, joined with a branch from the 
 fourth, descends across the base of the sacrum to join the anterior division of the 
 first sacral nerve and assist in the formation of the sacral plexus. The cord result- 
 ing from the union- of the fifth lumbar and the branch from the fourth is called 
 the lumbo-sacral cord {truncus lumhosacralis) (Figs. 648 and 655) . 
 
 The Lumbar Plexus (Plexus Lumbalis) (Figs. 647, 648). 
 
 The lumbar plexus is formed by the loops of communication between the ante- 
 rior divisions of the four upper lumbar nerves. The plexus is narrow above, and 
 often connected with the last dorsal nerve by a slender branch, the dorsi-lumbar 
 nerve. The plexus is broad below, where it is joined to the sacral plexus by the 
 lumbo-sacral cord. The lumbar plexus is situated in the substance of the Psoas 
 muscle near its posterior part, in front of the transverse processes of the lumbar 
 vertebrae. 
 
 The mode in which the plexus is arranged varies in different subjects. It differs 
 from the brachial plexus in not forming an intricate interlacement, but the several 
 nerves of distribution arise from one or more of the spinal nerves in the following 
 manner: The first lumbar nerve receives a branch from the last dorsal, and gives 
 off a larger branch, which subdivides into the ilio-hypogastric and ilio-inguinal 
 nerves; the first lumbar also gives off a communicating branch which passes down 
 to the second lumbar nerve, and a third branch which unites with a branch of the 
 second lumbar, to form the genito-crural nerve. The second, third, and fourth 
 lumbar nerves divide into anterior and posterior divisions. The anterior division 
 of the second divides into two branches, one of which joins with the above- 
 mentioned branch of the first nerve to form the genito-crural; the other unites 
 with the anterior division of the third nerve, and a part of the anterior division 
 of the fourth nerve to form the obturator nerve. The remainder of the anterior 
 division of the fourth nerve passes down to communicate with the fifth lumbar 
 nerve. The posterior divisions of the second and third nerves divide into two 
 
THE LUMBAR PLEXUS 
 
 999 
 
 C. with nthl 
 
 branches, a smaller branch from each uniting to form the external cutaneous nerve, 
 and a larger branch from each, which join with the whole of the posterior division 
 of the fourth lumbar nerve to form the anterior crural. The accessory obturator, 
 when it exists, is formed by the union of two small branches given off from the 
 third and fourth nerves. 
 
 From this arrangement it follows that the ilio-hypogastric and ilio-inguinal 
 are derived entirely from the first lumbar nerve; the genito-crural from the first 
 and second nerves; the external cutaneous from the second and third; the anterior 
 crural and obturator by fibres derived from the second, third, and fourth; and the 
 accessory obturator, when it exists, from the third and fourth. 
 
 Branches (Figs. 647 and 648). — The branches of the lumbar plexus are — the 
 
 Ilio-hypogastric. Obturator. 
 
 Ilio-inguinal. Accessory obturator. 
 
 Genito-crural. Anterior crural. 
 External cutaneous. 
 
 The Ilio-h3rpogastric Nerve (n. iliohypogastricus) (Figs. 647 and 648). — The 
 ilio-hypogastric nerve arises from the first lumbar nerve. It emerges from the 
 outer border of the Psoas muscle at its 
 upper part, and crosses obliquely in front 
 of the Quadratus lumborum to the crest 
 of the ilium. It then perforates the Trans- 
 versalis muscle at its posterior part near the 
 crest of the ilium. It gives off muscular 
 branches {rami musculares) to the abdom- 
 inal wall, and divides between the trans- 
 versalis and the Internal oblique into two 
 cutaneous branches, iliac and hypogastric. 
 
 The Iliac Branch (ramus cutaneus lateralis) 
 pierces the Internal and External oblique 
 muscles immediately above the crest of the 
 ilium, and is distributed to the integument 
 of the gluteal region, behind the lateral 
 cutaneous branch of the last dorsal nerve 
 (Figs. 652 and 656). The size of this nerve 
 bears an inverse proportion to that of the 
 cutaneous branch of the last dorsal nerve. 
 
 The Hypogastric Branch (ramus cutaneus 
 anterior) (Fig. 649) continues onward be- 
 tween the Internal oblique and Trans- 
 versalis muscles. It then pierces the In- 
 ternal oblique, and becomes cutaneous by 
 perforating the aponeurosis of the External 
 oblique, about an inch above and a little to 
 the outer side of the external abdominal 
 ring, and is distributed to the integument of the hypogastric region. The ilio- 
 hypogastric nerve communicates with the last dorsal and ilio-inguinal nerves. 
 
 The Ilio-inguinal Nerve (n. ilioinguinalis) (Figs. 647, 648, and 649). — The ilio- 
 inguinal nerve, smaller than the preceding, arises with it from the first lumbar 
 nerve. It emerges from the outer border of the Psoas muscle just below the ilio- 
 hypogastric nerve, and, passing obliquely across the Quadratus lumborum and 
 Iliacus muscles, perforates the Transversalis near the forepart of the crest of the 
 ilium, and communicates with the ilio-hypogastric nerve between that muscle 
 and the Internal oblique. The nerve then pierces the Internal oblique, distribu- 
 
 FiG. 647. — Plan of the lumbar plexus. 
 
1000 
 
 THE NERVOUS SYSTEM 
 
 ting muscular branches {rami musculares) to it, and, accompanying the spermatic 
 cord through the external abdominal ring, is distributed to the integument of the 
 upper and inner part of the thigh, and to the scrotum in the male (nn. scrotales 
 anteriores) (Fig. 651) , and to the labium majus in the female (nn. labiales anteriores). 
 The size of this nerve is in inverse proportion to that of the ilio-hypogastric. 
 Occasionally it is very small, and ends by joining the ilio-hypogastric; in such 
 cases a branch from the ilio-hypogastric takes the place of the ilio-inguinal, or 
 the ilio-inguinal nerve may be altogether absent. 
 
 The Genito-crural Nerve (?i. genitofemoralis) (Figs. 647 and 648) arises from 
 the first and second lumbar nerves. It passes obliquely through the substance 
 
 Fig. 648. — The lumbar plexus and its branches. 
 
 of the Psoas muscle, and emerges from its inner border at a level corresponding 
 to the intervertebral substance between the third and fourth lumbar vertebrae; 
 it then descends on the surface of the Psoas muscle, under cover of the peri- 
 toneum, and divides into a genital and a crural branch. 
 
 The Genital Branch (n. spermaticus externus) passes outward on the Psoas 
 raagnus, and pierces the fascia transversalis, or passes through the internal abdom- 
 inal ring; in the male it then descends along the back part of the spermatic cord to 
 the scrotum, and supplies the Cremaster muscle. In the female it accompanies 
 the round ligament, and is lost upon it. 
 
 The Crural Branch (n. lumhoinguinalis) (Fig. 649) descends on the external iliac 
 artery, sending a few filaments around it, and, passing beneath Poupart's ligament 
 
THE LUMBAR PLEXUS 
 
 1001 
 
 V 
 
 ^ ^\^ ^/'oiju'l- 
 
 A 
 
 External 
 saphe7ious. 
 
 External ))) 
 cutaneous. 
 
 Anterior crural. 
 
 -Anterior tibial. 
 
 .Anterior division 
 of obturator. 
 Internal 
 cutaneotis. 
 
 Internal 
 'saphenous. 
 
 Fig. 649.— Cutaneous nerves of lower 
 extremity. Front view. 
 
 Fig. 650. — Nerves of the lower extremity. 
 Front view. 
 
1002 
 
 THE NERVOUS SYSTEM 
 
 to the thigh, enters the sheath of the femoral vessels, lying superficial and a little 
 external to the femoral artery. It pierces the anterior layer of the sheath of the 
 vessels, and, becoming superficial by passing through the fascia lata, it supplies the 
 skin of the anterior aspect of the thigh as far as midway between the pelvis and 
 
 DORSAL DIVI- 
 SIONS OF 
 SACRAL 
 NERVES , 
 
 PERFORATING 
 CUTANEOUS 
 OF FOURTH 
 SACRAL 
 
 
 . :» :h| 
 
 EXTERNAL SAPHENOUS I. II. S.. 
 ANTERIOR TIBIAL IV. V. L. I. S. 
 EXTERNAL PLANTAR- 
 INTERNAL PLANTAR IV. V. L.- 
 
 FiG. 651. — Areas of distribution of the cutaneous 
 nerves of the front of the lower limb. (W. Keiller, 
 after Testut, in Gerrish's Text-book of Anatomy.) 
 
 MUSCULOCUTANEOUS 
 V. V. L. I. S. 
 
 INTERNAL 
 
 CALCANEAN 
 
 I. M. S. 
 
 Fig. 652. — Areas of distribution of the cutane- 
 ous nerves of the back of the lower limb. (W. 
 Keiller, after Testut, in Gerrish's Text-book of 
 Anatomy.) 
 
 knee (Fig. 651) . On the front of the thigh it communicates with the outer branch 
 of the middle cutaneous nerve, derived from the anterior crural. 
 
 A few filaments from this nerve may be traced on to the femoral artery; they 
 are derived from the nerve as it passes beneath Poupart's ligament. 
 
THE LUMBAR PLEXUS 1003 
 
 The External Cutaneous Nerve (n. cutaneus femoris lateralis) (Figs. 647, 648, 
 649, and 650). — The external cutaneous nerve arises from the second and third 
 lumbar nerves. It emerges from the outer border of the Psoas muscle about its 
 middle, and crosses the Iliacus muscle obliquely, toward the anterior superior 
 spine of the ilium. It then passes under Poupart's ligament and over the Sartorius 
 muscle into the thigh, where it divides into two branches, anterior and posterior. 
 
 The Anterior Branch descends in an aponeurotic canal formed in the fascia lata, 
 becomes superficial about four inches below Poupart's hgament, and divides into 
 branches which are distributed to the integument along the anterior and outer 
 part of the thigh, as far down as the knee (Fig. 651) . This nerve occasionally com- 
 municates with a branch of the long saphenous nerve in front of the knee-joint. 
 
 The Posterior Branch pierces the fascia lata, and subdivides into branches which 
 pass backward across the outer and posterior surface of the thigh, supplying the 
 integument from the crest of the ilium as far as the middle of the thigh (Fig. 652). 
 
 The Obturator Nerve (n. ohturatoriiis) (Figs. 647, 648, and 650).— The obturator 
 nerve supphes the Obturator externus and Adductor muscles of the thigh, the 
 articulations of the hip and knee, and occasionally the integument of the thigh 
 and leg. It arises by three branches — from the second, the third, and the fourth 
 lumbar nerves. Of these, the branch from the third is the largest, while that 
 from the second is often very small. It descends through the inner fibres of the 
 Psoas muscle, and emerges from its inner border near the brim of the pelvis; it then 
 runs along the lateral wall of the pelvis, above the obturator vessels, to the upper 
 part of the obturator foramen, where it enters the thigh, and divides into an 
 anterior and a posterior branch, separated by some of the fibres of the Obturator 
 externus muscle, and lower down by the Adductor brevis muscle. 
 
 The Anterior Branch (ramus anterior) (Fig. 650) passes down in front of the 
 Adductor brevis, being covered by the Pectineus and Adductor longus, and at the 
 lower border of the latter muscle communicates with the internal cutaneous and 
 internal saphenous nerves, forming a kind of plexus. It then descends upon the 
 femoral artery, upon which it is finally distributed. The nerve, near the obturator 
 foramen, gives off an articular branch to the hip-joint. Behind the Pectineus it 
 distributes muscular branches to the Adductor longus and Gracilis, and usually 
 to the Adductor brevis, and in rare cases to the Pectineus, and receives a com- 
 municating branch from the accessory obturator nerve. 
 
 Occasionally the communicating branch to the internal cutaneous and internal 
 saphenous nerves is continued down, as a cutaneous branch (ramus cutaneus), to the 
 thigh and leg. When this is so, this occasional cutaneous branch emerges from 
 beneath the lower border of the Adductor longus, descends along the posterior 
 margin of the Sartorius to the inner side of the knee, where it pierces the deep 
 fascia, communicates with the long saphenous nerve, and is distributed to the 
 integument of the inner side of the leg as low down as its middle. When this 
 communicating branch is small its place is supplied by the internal cutaneous 
 nerve. 
 
 The Posterior Branch (ramu^ posterior) pierces the Obturator externus, sending 
 branches to supply it, and passes behind the Adductor brevis on the front of the 
 Adductor magnus, where it divides into numerous muscular branches, which 
 supply the Adductor magnus, and the Adductor brevis when the latter does not 
 receive a branch from the anterior division of the nerve. One of the branches 
 gives oft' a filament to the knee-joint. 
 
 The Articular Branch for the Knee-joint is sometimes absent; it perforates the 
 lower part of the Adductor magnus, and enters the popliteal space; it then descends 
 upon the popliteal artery, as far as the back part of the knee-joint, where it per- 
 forates the posterior ligament, and is distributed to the synovial membrane. It 
 gives filaments to the popliteal artery in its course. 
 
1004 THE NERVOUS SYSTEM 
 
 The Accessory Obturator Nerve or the Accessory Anterior Crural Nerve of Winslow 
 {n. ohturatorius accessorius (Fig. 648). — The accessory obturator nerve is not con- 
 stantly present. It is of small size, and arises by separate filaments from the 
 third and fourth lumbar nerves. It descends along the inner border of the Psoas 
 muscle, crosses the ascending ramus of the os pubis, and passes under the outer 
 border of the Pectineus muscle, where it divides into numerous branches. One 
 of these supplies the Pectineus, penetrating its under surface; another is dis- 
 tributed to the hip-joint; while a third communicates with the anterior branch of 
 the obturator nerve. When this nerve is absent the hip-joint receives two branches 
 from the obturator nerve. Occasionally the articular branch is very small, and 
 becomes lost in the capsule of the hip-joint. 
 
 The Anterior Crural Nerve (n. femoralis) (Figs. 647, 648, and 650). — The anterior 
 crural nerve is the largest branch of the lumbar plexus. It supplies muscular 
 branches to the Iliacus, Pectineus, and all the muscles on the front of the thigh, 
 excepting the Tensor fasciae femoris; cutaneous filaments to the front and inner 
 side of the thigh, and to the leg and foot (Figs. 651 and 652) ; and articular 
 branches to the hip and knee. It arises from the second, third, and fourth 
 lumbar nerves. It descends through the fibres of the Psoas muscle, emerging 
 from muscle at the lower part of its outer border, and passes down between it 
 and the Iliacus muscle, and beneath Poupart's ligament, into the thigh, where 
 it becomes somewhat flattened, and divides into an anterior and a posterior part. 
 Under Poupart's ligament it is separated from the femoral artery by a portion of 
 the Psoas muscle, and lies beneath the iliac fascia. 
 
 Within the abdomen the anterior crural nerve gives off from its outer side some 
 small muscular branches to the Iliacus, and a branch to the femoral artery which 
 is distributed upon the upper part of that vessel. The origin of this branch varies; 
 it occasionally arises higher than usual, or it may arise lower down in the thigh. 
 
 External to the pelvis the following branches are given off: 
 
 From the Anterior Division. From the Posterior Division. 
 jNIiddle cutaneous. I^ong saphenous. 
 
 Internal cutaneous. Muscular. 
 
 Muscular. Articular. 
 
 The middle and internal cutaneous branches of the anterior crural nerve are 
 the rami cutanei anteriores n. femoralis of the new nomenclature. 
 
 The Middle Cutaneous Nerve (Figs. 649 and 650) pierces the fascia lata (generally 
 the Sartorius muscle also) about three inches below Poupart's ligament, and 
 divides into two branches (Fig. 649) , which descend in immediate proximity along 
 the forepart of the thigh, to supply the integument as low as the front of the knee 
 (Fig. 651), where it communicates with the internal cutaneous nerve and the 
 patellar branch of the internal saphenous nerve, to form the patellar plexus. In 
 the upper part of the thigh the outer division of the middle cutaneous nerve com- 
 municates with the crural branch of the genito-crural nerve. 
 
 The Internal Cutaneous Nerve (Fig. 649) passes obliquely across the upper part 
 of the sheath of the femoral artery, and divides in front or at the inner side of that 
 vessel into two branches, anterior and posterior or internal. 
 
 The anterior branch runs downward on the Sartorius, perforates the fascia lata 
 at the lower third of the thigh, and divides into two branches, one of which sup- 
 plies the integument as low dowji as the inner side of the knee; the other crosses 
 to the outer side of the patella, communicating in its course with the nervus 
 cutaneus patellae, a branch of the internal saphenous nerve. 
 
 The posterior or internal branch descends along the inner border of the Sartorius 
 muscle to the knee, where it pierces the fascia lata, communicates with the long 
 saphenous nerve, and gives off several cutaneous branches. The nerve then 
 
THE LUMBAR PLEXUS 1C05 
 
 passes down the inner side of the leg, to the integument of which it is distributed. 
 This nerve, beneath the fascia lata, at the lower border of the Adductor longus, 
 joins in a plexiform network by uniting with branches of the long saphenous and 
 obturator nerves (Fig. 650). VYhen the communicating branch from the obturator 
 nerve is large and continued to the integument of the leg, the inner branch of the 
 internal cutaneous is small and terminates at the plexus, occasionally giving off 
 a few cutaneous filaments. 
 
 The internal cutaneous nerve, before dividing, gives off a few filaments, which 
 pierce the fascia lata, to supply the integument of the inner side of the thigh (Figs. 
 651 and 652). One of these filaments passes through the saphenous opening; 
 a second becomes subcutaneous about the middle of the thigh (Fig. 649) ; and a 
 third pierces the fascia at its lower third (Fig. 649). 
 
 The Muscular Branches of the Anterior Division {rami musculares). — ^The nerve 
 to the Pectineus is often duplicated ; it arises from the anterior crural immediately 
 below Poupart's ligament, and passes inward behind the femoral sheath to enter 
 the anterior surface of the muscle. The nerve to the Sartorius arises in common 
 with the middle cutaneous. 
 
 The Long or Internal Saphenous Nerve (n. saphenus) (Figs. 649 and 650) is 
 the largest of the cutaneous branches of the anterior crural. It approaches the 
 femoral artery where this vessel passes beneath the Sartorius, and lies in front of it, 
 beneath the aponeurotic covering of Hunter's canal, as far as the opening in the 
 lower part of the Abductor magnus. It then leaves the artery, and descends 
 vertically along the inner side of the knee, beneath the Sartorius muscle, pierces 
 the fascia lata opposite the interval between the tendons of the Sartorius and 
 Gracilis muscles, and becomes subcutaneous. The nerve then passes along the 
 inner side of the leg (Fig. 649), accompanied by the internal saphenous vein, 
 descends behind the internal border of the tibia, and, at the lower third of the leg 
 divides into two branches: one continues its course along the margin of the tibia, 
 terminating at the inner ankle; the other passes in front of the ankle, and is 
 distributed to the integument along the inner side of the foot, as far as the great 
 toe, communicating with the internal branch of the musculo-cutaneous nerve. 
 
 The long saphenous nerve about the middle of the thigh gives off a communicating 
 branch which joins the plexus formed by the obturator and internal cutaneous 
 nerves. 
 
 At the inner side of the knee it gives off a large patellar branch, the nervus 
 cutaneus patellae (ramus infrapatellaris) , which pierces the Sartorius and fascia 
 lata, and is distributed to the integument in front of the patella. This nerve com- 
 municates above the knee with the anterior branch of the internal cutaneous and 
 with the middle cutaneous; below the knee, with other branches of the long 
 saphenous; and on the outer side of the joint, with branches of the external cuta- 
 neous nerve, forming a plexiform network, the patella plexus (plexus patellae). 
 The cutaneous nerve of the patella is occasionally small, and terminates by join- 
 ing the internal cutaneous, which supplies its place in front of the knee. 
 
 Below the knee the branches of the long saphenous nerves are distributed to 
 the integument of the front and inner side of the leg (Figs. 651 and 652), com- 
 municating with the cutaneous branches from the internal cutaneous or from the 
 obturator nerve. The nerve also sends filaments to the ankle-joint. 
 
 The Muscular Branches of the Posterior Division. — The muscular branches of the 
 posterior division supply the four parts of the Quadriceps extensor muscle. 
 
 The branch to the Rectus muscle enters its under sui-face high up, sending off a 
 small filament to the hip-joint. 
 
 The branch to the Vastus extemus muscle, of large size, follows the course of 
 the descending branch of the external circumflex artery to the lower part of the 
 muscle. It gives off an articular filament to the knee-joint. 
 
1006 THE I^EBVOUS SYSTEM 
 
 The branch to the Vastus internus muscle is a long branch which runs down on 
 the outer side of the femoral vessels in company with the internal saphenous 
 nerve for its upper part. It enters the muscle about its middle, and gives off a 
 filament which can usually be traced downward on the surface of the muscle to 
 the knee-joint. 
 
 The branch to the Crureus muscle enters the muscle on its anterior surface 
 about the middle of the thigh, and sends a filament through the muscle to the 
 Subcrureus and the knee-joint. 
 
 The articular branch to the hip-joint is derived from the nerve to the Rectus 
 muscle. 
 
 The articular branches to the knee-joint are three in number. One, a long, slender 
 filament, is derived from the nerve to the Vastus externus muscle; it penetrates the 
 capsular ligament of the joint on its anterior aspect. Another is derived from 
 the nerve to the Vastus internus muscle. It can usually be traced downward 
 on the surface of this muscle to near the joint; it then penetrates the muscle 
 and accompanies the deep branch of the anastomotica magna artery, pierces the 
 capsular ligament of the joint on its inner side, and supplies the synovial 
 membrane. The third branch is derived from the nerve to the Crureus. 
 
 THE SACRAL AND COCCYGEAL NERVES (NN. SACRALES ET COCCYGEUS). 
 
 The sacral nerves are five in number on each side. The four upper ones pass 
 from the sacral canal through the sacral foramina; the fifth through the foramen 
 between the sacrum and coccyx. 
 
 The Roots of the Upper Sacral Nerves. 
 
 The roots of the upper sacral nerves are the largest of all the spinal nerves; 
 while those of the lowest sacral and the coccygeal nerve are the smallest. They are 
 longer than those of any of the other spinal nerves, on account of the spinal cord 
 not extending beyond the first lumbar vertebra. From their great length, and the 
 appearance they present in connection with their attachment to the spinal cord, 
 the roots of origin of these nerves are called collectively the cauda equina. 
 
 Each sacral and coccygeal nerve separates into two divisions, posterior and 
 .anterior. 
 
 The Posterior Divisions of the Sacral Nerves (Rami Posteriores) (Fig. 653). 
 
 The posterior divisions of the sacral nerves are small, diminish in size from 
 .above downward, and emerge, except the last, from the sacral canal by the posterior 
 •sacral foramina. 
 
 The Upper Sacral Nerves. — Each of the three upper ones is covered, at its 
 exit from the sacral canal, by the Multifidus spinae muscle, and divides into an 
 internal branch (ramus medialis) and an external branch {ramus lateralis). 
 
 The Internal Branches. — The internal branches are small, and supply the Mul- 
 tifidus spinae muscle. 
 
 The External Branches. — The external branches join with one another, and with 
 the last lumbar and fourth sacral nerves, in the form of loops on the posterior 
 surface of the sacrum, constituting the posterior sacral plexus. From these loops 
 branches pass to the outer surface of the great sacro-sciatic ligament, where they 
 form a second series of loops beneath the Gluteus maximus muscle. Cutaneous 
 branches from this second series of loops, usually two or three in number, pierce 
 the Gluteus maximus muscle along a line drawn from the posterior superior spine 
 
THE ANTERIOR DIVISIONS OF THE SACRAL NERVES 1007 
 
 of the ilium to the tip of the coccyx. They supply the integument over the 
 posterior part of the gluteal region (Fig. 652). 
 
 The Lower Sacral Nerves. — The posterior divisions of the two lower sacral 
 nerves are situated below the Multifidus spinae muscle. They are of small size, 
 and do not divide into internal and external branches, but join with each other, 
 
 Fig. 653 — The posterior sacral nerves. 
 
 and with the posterior division of the coccygeal nerve to form the posterior sacro- 
 coccygeal nerve, which passes through the sacro-sciatic ligament, and forms loops 
 on the back of the sacrum, filaments from which supply the Extensor coccygeus 
 and the integument over the coccyx (Fig. 652). 
 
 The Anterior Divisions of the Sacral Nerves (Rami Anteriores) (Fig. 655). 
 
 The anterior divisions of the sacral nerves diminish in size from above down- 
 ward. The four upper ones emerge from the anterior sacral foramina; the ante- 
 rior division of the fifth, after emerging from the spinal canal through its terminal 
 opening, curves forward between the sacrum and the coccyx. All the anterior sacral 
 nerves at their exit from the sacral foramina communicate with the sacral ganglia of 
 the sympathetic. The first nerve (Fig. 654) , of large size, unites with the lumbo-sacral 
 cord (trtmcus lumbosacralis) , formed by the fifth lumbar, and a branch from the 
 fourth lumliar (n. furcalis). The second (Fig. 654), equal in size to the preceding, 
 and the third (n. higeminus) (Fig. 654), about one-fourth the size of the second, 
 unite with this trunk, and form, with a small fasciculus from the fourth, the sacral 
 plexus, a visceral branch being given off from the third nerve to the bladder 
 (Fig. 655). 
 
 The Fourth Anterior Sacral Nerve sends a branch to join the sacral plexus. The 
 remaining portion of the nerve divides into visceral and muscular branches, and a 
 communicating filament descends to join the fifth sacral nerve. 
 
1008 
 
 THE NERVOUS SYSTEM 
 
 The visceral branches are distributed to the viscera of the pelvis, communicating 
 with the sympathetic nerve. These branches ascend upon the rectum and bladder, 
 and in the female upon the vagina, communicating with branches of the sym- 
 pathetic from the pelvic plexus. The visceral branches of the third and fourth 
 sacral do not join the gangliated cord. 
 
 The muscular branches are distributed to the Levator ani, Coccygeus, and 
 Sphincter ani. The branch to the Sphincter ani pierces the levator ani, so as to 
 reach the ischio-rectal fossa, where it is found lying in front of the coccyx. Cuta- 
 neous filaments arise from the latter branch, which supply the integument between 
 the anus and coccyx. Another cutaneous branch is frequently given off from this 
 
 Femoral m tei y 
 
 Coccygeal. 
 ^Br. to' I Br. to 
 
 LEVATOR ANI. SPHINCTER ANI. 
 
 Fig. 664. — Side view of pelvis, showing sacral nerves. 
 
 nerve, though sometimes from the pudic (Schwalbe). It perforates the great 
 sacro-sciatic ligament, and, winding around the lower border of the Gluteus 
 maximus, supplies the skin over the lower and inner part of this muscle. 
 
 The Fifth Anterior Sacral Nerve, after passing from the lower end of the sacral 
 canal, curves forward through the fifth sacral foramen, formed between the lower 
 part of the sacrum and the transverse process of the first piece of the coccyx. It 
 pierces the Coccygeus muscle, and descends upon its anterior surface to near the 
 tip of the coccyx, where it again perforates the muscle, to be distributed to the 
 integument over the back part and side of the coccyx. This nerve communicates 
 above with the fourth sacral and below with the coccygeal nerve, and supplies the 
 Coccygeus muscle. 
 
 The Posterior Division of the Coccygeal Nerve. 
 
 The coccygeal nerve divides into its anterior and posterior divisions in the 
 spinal canal. The posterior division is the smaller. It does not divide, but 
 
THE SACRAL OB SCIATIC PLEXUS 
 
 1009 
 
 receives, as already mentioned, a communicating branch from the last sacral, 
 and is lost in the integument over the back of the coccyx. 
 
 The Anterior Division of the Coccygeal Nerve. 
 
 The anterior.division of the coccygeal nerve is a delicate filament which escapes 
 at the termination of the sacral canal; it passes downward behind the rudimentary 
 transverse process of the first piece of the coccyx, and curves forward through 
 the notch between the first and second pieces, piercing the Coccygeus muscle, and 
 descending on its anterior surface to near the tip of the coccyx, where it again 
 pierces the muscle, to be distributed to the integument over the back part and side 
 of the coccyx. It is joined by a branch from the fifth anterior sacral as it descends 
 on the surface of the Coccygeus muscle. 
 
 The Pudendal Plexus (plexus pudendus). — The pudendal plexus is formed by 
 fibres obtained from the anterior divisions of the first three sacral nerves and by 
 the anterior divisions of the two lower sacral nerves and the coccygeal nerve. It 
 is, so to speak, interpolated in the sacral plexus and is considered as a portion of it. 
 
 The Sacral or Sciatic Plexus (Plexus Sacralis) and the Pudic or Pudendal 
 Plexus (Plexus Pudendalis) (Fig. 655). 
 
 The sacral plexus is formed by the lum bo-sacral cord, the anterior divisions 
 of the three upper sacral nerves and a branch from the fourth. The pudic or 
 pudendal plexus is considered with the sacral plexus. It is usually composed of 
 
 / FOURTH LUMBAR 
 
 FIFTH LUMBAR 
 
 RST SACRAL 
 
 SECOND SACRAL 
 
 THIRD SACRAL 
 
 FOURTH SACRAL 
 
 FIFTH SACRAL 
 '^/ ■' '/hr'-'ft — N.TO COCCYQEUS 
 
 -T^ vi8oeraDv'>'-;^.' COCCYGEAL 
 
 Fig. 656.- -Plan of sacral plexus with the pudendal plexus. (Gerrish.) 
 
 the anterior divisions of the second, third, fourth, and fifth sacral nerves and the 
 coccygeal nerve. It is irregular in composition. Prof. Cunningham says: "There 
 is no distinct point of separation between the two plexuses. On the contrary, there 
 is considerable overlapping, so that two and sometimes three of the principal nerves 
 derived from the pudendal plexus have their origin in common with nerves of the 
 
 64 
 
1010 THE NERVOUS SYSTEM 
 
 sacral plexus." The nerves of these two plexuses proceed in different directions: 
 the upper ones obliquely downward and outward, the lower ones nearly horizontally 
 outward, and they all unite into two cords; an upper and larger cord, which is formed 
 by the lumbo-sacral cord with the first, second, and the greater part of the third 
 sacral nerves; and a lower and smaller cord, formed by the remainder of the third, 
 with a portion of the fourth sacral nerve. The upper cord is prolonged into the 
 great sciatic nerve and the lower into the pudic. Frequently a small filament is 
 given off from the second sacral nerve to join the lower cord. 
 
 Each of the nerves which form the plexus joins the sympathetic by gray rami 
 communicantes. White rami communicantes join the third sacral and sometimes 
 also the second and fourth sacrals to the s^nnpathetic. 
 
 The sacro-pudendal plexus is triangular in form, its base corresponding with 
 the exit of the nerves from the sacrum, its apex with the lower part of the great 
 sacro-sciatic foramen. It rests upon the anterior surface of the Pyriformis, and is 
 covered in front by the pelvic fascia, which separates it from the sciatic and pudic 
 branches of the internal iliac artery and from the viscera of the pelvis. The sacral 
 plexus proper sends branches to the lower extremity; the pudendal plexus proper 
 is largely limited to supplying the perineum. 
 
 Branches. — The branches of the sacro-pudendal plexus are divided into col- 
 lateral and terminal branches. 
 
 Muscular. 
 
 Collateral branches 
 
 Terminal branches 
 
 Superior gluteal. 
 
 Inferior gluteal. 
 
 Small sciatic 
 
 Perforating cutaneous. 
 ] Pudic. 
 1 Great sciatic. 
 
 The Muscular Branches {rami musculares). — The muscular branches supply the 
 Pyriformis, Obturator internus, the two Gemelli, and the Quadratus femoris. 
 The branch to the Pyriformis muscle arises from the upper two sacral nerves 
 before they enter the plexus; the branch to the Obturator internus muscle arises 
 at the jimction of the lumbo-sacral and first sacral nerves; it passes out of the 
 pelvis through the great sacro-sciatic foramen below the Pyriformis, crosses the 
 spine of the ischium, and re-enters the pelvis through the lesser sacro-sciatic 
 foramen to enter the inner surface of the Obturator internus; the branch to the 
 Gemellus superior muscle arises in common with the nerve to the Obturator 
 internus muscle; it enters the muscle at the upper part of its posterior surface; 
 the small branch to the Gemellus inferior and Quadratus femoris muscles also 
 arises from the upper part of the plexus; it passes through the great sacro-sciatic 
 foramen below the Pyriformis, and courses down beneath the great sciatic nerve, 
 the Gemelli and tendon of the Obturator internus, supplies the muscles on their 
 deep or anterior surface and gives off an articular branch to the hip-joint. A second 
 articular branch is occasionally derived from the upper part of the sacral plexus. 
 
 The Superior Gluteal Nerve {n. glutaeus superior) (Figs. 655 and 657). — The 
 superior gluteal nerve arises from the back part of the lumbo-sacral cord, with 
 some filaments from the first sacral nerve; it passes from the pelvis through the 
 great sacro-sciatic foramen above the Pyriformis muscle, accompanied by the 
 gluteal vessels, and divides into a superior and an inferior branch. 
 
 The Superior Branch follows the line of origin of the Gluteus minimus, and 
 supplies the Gluteus medius muscle. 
 
 The Inferior Branch crosses obliquely between the Gluteus minimus and medius, 
 distributing filaments to both these muscles, and terminates in the Tensor fasciae 
 femoris muscle, extending nearly to its lower end. 
 
THE SACRAL OB SCIATIC PLEXUS 1011 
 
 The Inferior Gluteal Nerve {n. glutaeus inferior) (Fig. 655).— The inferior gluteal 
 nerve arises from the lumbo-sacral cord and first and second sacral nerves, and is 
 intimately connected with the small sciatic at its origin. It passes out of the pelvis 
 through the great sciatic notch, beneath the Pyriformis muscle, and, dividing into 
 a number of branches, enters the Gluteus maxiraus muscle on its under surface. 
 
 The Small Sciatic Nerve (n. cutanetis femoris posterior) (Figs. 655, 656, and 657). 
 — The small sciatic nerve supplies the integument of the perineum and back part 
 of the thigh and leg. It is usually formed by the union of two branches, which 
 arise from the second and third nerves of the sacral plexus. It issues from the 
 pelvis through the great sacro-sciatic foramen below the Pyriformis muscle, 
 descends beneath the Gluteus maximus with the sciatic artery, and at the 
 lower border of that muscle passes along the back part of the thigh, beneath the 
 fascia lata and over the long head of the Biceps, to the lower part of the popliteal 
 region, where it pierces the fascia and becomes cutaneous. It then accompanies 
 the external saphenous vein to about the middle of the leg, its terminal filaments 
 communicating with the external saphenous nerve. 
 
 The Branches of the small sciatic nerve are all cutaneous, and are grouped as 
 follows: gluteal, perineal, and femoral. 
 
 The Gluteal Cutaneous Branches {nn. clunium injeriores [laterales\) consist of two 
 or thiee ascending filaments, which turn upward around the lower border of the 
 Gluteus maximus to supply the integument covering the lower and outer part 
 of that muscle (Fig. 652). 
 
 The Perineal Cutaneous Branches {rami perineales) are distributed to the skin 
 at the upper and inner side of the thigh, on its posterior aspect. One branch, 
 longer than the rest, the inferior pudendal or long scrotal nerve (Fig. 657), curves 
 forward below the tuber ischii, pierces the fascia lata, and passes forward beneath 
 the superficial fascia of the perineum to be distributed to the integument of the 
 scrotum in the male (Fig. 652) and the labium in the female, communicating with 
 the supcficial perineal and inferior hemorrhoidal nerves. 
 
 The Femoral Cutaneous Branches are numerous descending filaments, derived 
 from both sides of the nerves, which are distributed to the back, inner, and outer 
 sides of the thigh, to the skin covering the popliteal space, and to the upper part 
 of the leg (Fig. 652). 
 
 The Perforating Cutaneous Nerve (n. clunium inferior medialis) (Fig. 655). — The 
 perforating cutaneous nerve usually arises from the second and third sacral 
 nerves, and is of small size. It is continued backward through the great sacro- 
 sciatic ligament, and, winding around the lower border of the Gluteus maximus, 
 supplies the integument covering the inner and lower part of that muscle. 
 
 The Pudic Nerve (n. pudendus) (Figs. 655 and 657). — ^The pudic nerve is the 
 direct continuation of the lower cord of the sacral plexus, and derives its fibres 
 from the third and fourth sacral nerves, and frequently from the second also. 
 It leaves the pelvis through the great sacro-sciatic foramen, below the Pyriformis. 
 It then crosses the spine of the ischium, and re-enters the pelvis through the 
 lesser sacro-sciatic foramen. It accompanies the pudic vessels upward and for- 
 ward along the outer wall of the ischio-rectal fossa, being contained in a sheath 
 of the obturator fascia, termed Alcock's canal, and divides into two terminal 
 branches, the perineal nerve and the dorsal nerve of the penis or clitoris. Before 
 its division it gives oft" the inferior hemorrhoidal nerve. 
 
 The Inferior Haemorrhoidal Nerve (n. haemorrhoidalis inferior) is occasionally 
 derived separately from the sacral plexus. It passes across the ischio-rectal fossa, 
 with its accompanying vessels, toward the lower end of the rectum, and is dis- 
 tributed to the Sphincter ani externus and to the integument around the anus. 
 Branches of this nerve communicate with the inferior pudendal and superficial 
 perineal nerves at the forepart of the perineum. 
 
1012 
 
 THE NERVOUS SYSTEM 
 
 *y. 
 
 /■I 
 
 Superior f _<^ 
 gluteal. V^ 
 
 Pudic.^ .^, 
 
 Nerve to 
 
 obturator internus. a. 
 
 ^M sciatic 
 
 Fig. 656. — Cutaneous nerves of lower 
 extremity. Posterior view. 
 
 External 
 
 popliteal, or 
 
 peroneal. 
 
 Communicant 
 ptronei. 
 
 Fig. 657. 
 
 -Nerves of the lower extremity.* 
 Posterior view. 
 
 ' N. B. — In this diaKram the external saphenous and communicans peronei are not in their normal position. 
 They have been displaced by the removal of the superficial muscles. 
 
THE SACBAL OR SCIATIC PLEXUS 1013 
 
 The Perineal Nerve (w. perinei), the inferior and larger of the two terminal 
 branches of the pudic, is situated below the pudic artery. It accompanies the 
 superficial perineal artery in the perineum, dividing into cutaneous and muscular 
 branches. 
 
 The cutaneous branches (superficial perineal) are two in number, posterior and 
 anterior. The posterior or external branch pierces the base of the triangular liga- 
 ment of the urethra, and passes forward along the outer side of the urethral 
 triangle in company with the superficial perineal artery; it is distributed to the 
 skin of the scrotum (nn. scrotales posteriores) . It communicates with the inferior 
 haemorrhoidal, the inferior pudendal, and the other superficial perineal nerve. 
 The anterior or internal branch also pierces the base of the triangular ligament, and 
 passes forward nearer to the middle line, to be distributed to the inner and back 
 part of the scrotinn. Both these nerves supply the labia majora in the female. 
 
 The muscular branches are distributed to the Transversus perinaei. Accelerator 
 urinae. Erector penis, and Compressor urethrae. A distant branch is given off 
 from the nerve to the Accelerator urinae, which pierces this muscle, and supplies 
 the corpus spongiosum, ending in the mucous membrane of the urethra. This 
 is the nerve to the bulb. 
 
 The Dorsal Nerve of the Penis {n. dorsalis penis) is the deepest division of the 
 pudic nerve; it accompanies the pudic artery along the ramus of the ischium; it 
 then runs forward along the inner margin of the ramus of the os pubis, between 
 the superficial and deep layers of the triangular ligament. Piercing the superficial 
 layer it gives a branch to the corpus cavernosum, and passes forward, in company 
 with the dorsal artery of the penis, between the layers of the suspensory ligament, 
 on to the dorsum of the penis, along which it is carried as far as the glans, to which 
 it is distributed. 
 
 In the female the dorsal nerve is very small, and supplies the clitoris (n. dorsalis 
 clitoridis). 
 
 The Great Sciatic Nerve (/?. ischiadicus) (Figs. 655 and 657). — ^The great sciatic 
 nerve supplies nearly the whole of the integument of the leg, the muscles of the 
 back of the thigh, and those of the leg and foot. It is the largest nervous cord in the 
 body, measuring three-quarters of an inch in breadth, and is the direct continuation 
 of the upper division of the sacral plexus. It passes out of the pelvis through the 
 great sacro-sciatic foramen, below the Pyriformis muscle. It descends between 
 the trochanter major and tuberosity of the ischium, along the back part of the 
 thigh, to about its lower third, where it divides into two large branches, the internal 
 and external popliteal nerves (Fig. 657). 
 
 This division may take place at any point between the sacral plexus and the 
 lower third of the thigh. When the division occurs at the plexus, the two nerves 
 descend together side by side; or they may be separated, at their commencement, 
 by the interposition of part or the whole of the Pyriformis muscle. As the nerve 
 descends along the back of the thigh, it rests upon the posterior surface of the 
 ischium, the nerve of the Quadratus femoris, and the External rotator muscles, in 
 company with the small sciatic nerve and artery, being covered by the Gluteus 
 maxim us; lower down, it lies upon the Adductor magnus, and is covered by the 
 long head of the Biceps. The great sciatic even when apparently a single nerve 
 is really two nerves appearing as one. 
 
 Branches. — The branches of the nerve, before its division, are articular and muscular. 
 
 The Articular Branches {rami articulares) arise from the upper part of the nerve ; 
 they supply the hip-joint, perforating the posterior part of its fibrous capsule. 
 These branches are sometimes derived from the sacral plexus. 
 
 The Muscular Branches {rami musculares) are distributed to the flexors of the leg — 
 viz., the Biceps, Semitendinosus, and Semimembranosus, and a branch goes to the 
 Adductor magnus. These branches are given off beneath the Biceps muscle. 
 
1014 THE NERVOUS SYSTEM 
 
 The Internal Popliteal or Tibial Nerve (n. tibialis) (Figs. 655 and 657), in reality, 
 arises from the fourth and fifth lumbar nerves and the first three sacral nerves, and 
 becomes a part of the trunk of the great sciatic in the buttock, to emerge from it 
 again at the bifurcation of the sciatic. It is the larger of the two terminal branches 
 of the great sciatic, descends along the back part of the thigh, through the middle of 
 the popliteal space, to the lower part of the Popliteus muscle, where it passes with 
 the artery beneath the arch of the Soleus and becomes the posterior tibial. It is over- 
 lapped by the hamstring muscles above, and then becomes more superficial, and 
 lies to the outer side of, and some distance from, the popliteal vessels; opposite 
 the knee-joint it is in close relation with the vessels, and crosses to the inner side of 
 the artery. Below, it is overlapped by the Gastrocnemius muscle. 
 
 The branches of this nerve are — articular, muscular, and a cutaneous branch, the 
 communicating tibial nerve. 
 
 The articular branches (rami articulares), usually three in number, supply the 
 knee-joint; two of these branches accompany the superior and inferior internal 
 articular arteries, and a third, the azygos articular artery. 
 
 The muscular branches {rami musculares) , four or five in number, arise from the 
 nerve as it lies between the two heads of the Gastrocnemius muscle; they supply 
 that muscle, and the Plantaris, Soleus, and Popliteus. The filaments which 
 supply the Popliteus turn around its lower border and are distributed to its deep 
 surface. 
 
 The tibial communicating nerve (n. cutaneus surae medialis) is the cutaneous 
 branch. It descends between the two heads of the Gastrocnemius muscle, and 
 about the middle of the back of the leg pierces the deep fascia, and joins the 
 peroneal or fibular communicating nerve (ramus anastomoticus peronaeus) from the 
 external popliteal nerve to form the external or short saphenous (n. surahs) (Fig. 
 657). The external saphenous nerve, formed by the communicating branches of 
 the internal and external popliteal nerves, passes downward and outward near 
 the outer margin of the tendo Achillis, lying close to the external saphenous vein, 
 to the interval between the external malleolus and the os calcis. It divides in 
 two branches, the posteror of which breaks up into external calcaneal branches 
 (rami calcanei laterales). The anterior branch (n. cutaneus dorsalis lateralis) winds 
 around the outer malleolus, and is distributed to the integument along the outer 
 side of the foot and little toe, communicating on the dorsum of the foot with the 
 musculo-cutaneous nerve. In the leg its branches communicate with those of the 
 small sciatic. The cutaneous area supplied by the external saphenous nerve is 
 indicated in Figs. 651, 652, and 659. 
 
 The Posterior Tibial Nerve (Fig. 657) is the terminal portion of the internal 
 popliteal nerve. It commences at the lower border of the Popliteus muscle, and 
 passes along the back part of the leg with the posterior tibial vessels to the interval 
 between the inner malleolus and the heel, where it divides into the external and 
 internal plantar nerves. It lies upon the deep muscles of the leg, and is covered in 
 the upper part by the muscles of the calf, lower down by the skin and fascia. In 
 the upper part of its course it lies to the inner side of the posterior tibial artery, but 
 it soon crosses that vessel, and lies to its outer side as far as the ankle. In the lower 
 third of the leg it is placed parallel with the inner margin of the tendo Achillis. 
 
 The branches of the posterior tibial nerve are muscular, internal calcaneal or 
 calcaneo-plantar, and articular. 
 
 The muscular branches {rami musculares) arise either separately or by a common 
 trunk from the upper part of the nerve. They supply the Soleus, Tibialis posticus, 
 Flexor longus digitorum, and Flexor longus hallucis muscles; the branch to the 
 latter muscle accompanying the peroneal artery. The branch to the Soleus enters 
 its deep surface, while the branch which this muscle receives from the internal 
 popliteal enters its superficial aspect. 
 
THE SACRAL OB SCIATIC PLEXUS 
 
 1015 
 
 The internal calcaneal or calcaneo-plantar branches {rami calcanei mediales) per- 
 forate the internal annular ligament, and supply the integument of the heel and 
 inner side of the foot (Fig. 059). 
 
 The articular branch (ramus articularis ad articulationem talocruralem) is given 
 off just above the bifurcation of the nerve and supplies the ankle-joint. 
 
 The Internal Plantar Nerve (^i. 'plantaris medialis) (Fig. 658), the larger of the 
 two terminal branches of the posterior tibial, accompanies the internal plantar 
 artery along the inner side of the foot. From its origin at the inner ankle it passes 
 beneath the Abductor hallucis, and divides into the common plantar digital nerves 
 {nn. digitales plantares communes), which pass forward between the Abductor 
 hallucis and the Flexor brevis digitorum, divides opposite the bases of the meta- 
 tarsal bones into four collateral plantar digital branches, and communicates with the 
 external plantar nerve. 
 
 In its course the internal plantar nerve gives off cutaneous branches, which pierce 
 the plantar fascia and supply the integument of the sole of the foot (Fig. 659) ; muscu- 
 lar branches, which supply the Abductor hallucis 
 and Flexor brevis digitorum; articular branches, 
 to the articulations of the tarsus and meta- 
 tarsus; and four collateral plantar digital branches 
 (nn. digitales plantares proprii) . The th ree outer 
 branches pass between the divisions of the 
 plantar fascia in the clefts between the toes ; the 
 first (innermost) branch becomes cutaneous 
 farther back between the Adductor hallucis 
 
 Deep 
 branch. 
 
 Internal 
 plantar.' 
 
 Exteiiml 
 plantar. 
 
 Fig. 658. — The plantar nerves. 
 
 Fig. 659.— Areas of distribution of the cutaneous nerves of the 
 sole. (W. Keiller, in Gerrish's Text-book of Anatomy.) 
 
 and Flexor brevis digitorum. They are distributed in the following manner: 
 The first supplies the inner border of the great toe, and sends a filament to the 
 Flexor brevis hallucis muscle; the second bifurcates, to supply the adjacent sides 
 of the great and second toes, sending a filament to the First lumbrical muscle; the 
 third supplies the adjacent sides of the second and third toes; the fourth supplies 
 the corresponding sides of the third and fourth toes, and receives a communicating 
 branch from the external plantar nerve (Fig. 659). Each digital nerve gives off 
 cutaneous and articular filaments; and opposite the last phalanx sends a dorsal 
 branch, which supplies the structures around the nail, the continuation of the nerve 
 
1016 THE NERVOUS SYSTEM 
 
 being distributed to the ball of the toe. It will be observed that the distribution 
 of these branches is precisely similar to that of the median nerve in the hand. 
 
 The External Plantar Nerve {n. plantaris lateralis) (Fig. 658) , the smaller of the 
 two, completes the nervous supply to the structures of the sole of the foot (Fig. 659) , 
 being distributed to the little toe, and one-half of the fourth, as well as to most of the 
 deep muscles, its distribution being similar to that of the ulnar in the hand. It 
 passes obliquely forward with the external plantar artery to the outer side of the 
 foot, lying between the Flexor brevis digitorum and Flexor accessorius, and in 
 the interval between the former muscle and Abductor minimi digiti divides into a 
 superficial and a deep branch. Before its division it supplies the Flexor accessorius 
 and Abductor minimi digiti. 
 
 The superficial branch (ramus superficialis) separates into two digital nerves. 
 Before division they are called common plantar digital nerves (nn. digitales plantares 
 communes), after division the collateral plantar digital nerves (nn. digitales plantares 
 proprii) : one, the external branch, the smaller of the two, supphes the outer side of 
 the little toe, the Flexor brevis minimi digiti, and the two Interosseous muscles 
 of the fourth metatarsal space; the other and larger digital branch supplies the 
 adjoining sides of the fourth and fifth toes, and communicates with, the internal 
 plantar nerve. 
 
 The deep or muscular branch (ramus profundus) accompanies the external 
 plantar artery into the deep part of the sole of the foot, beneath the tendons of 
 the Flexor muscles and Adductor obhquus hallucis, and supplies all the Interossei 
 (except those in the fourth metatarsal space), the three outer Lumbricales, the 
 Adductor obhquus hallucis, and the Adductor transversus hallucis. 
 
 The External Popliteal or Peroneal Nerve (n. peronaeus communis) (Figs. 655 and 
 657) in reality arises from the fourth and fifth lumbar and the first and second 
 sacral nerves. It is about one-half the size of the internal popliteal, descends 
 obliquely along the outer sides of the popliteal space to the head of the fibula, close 
 to the inner margin of the Biceps muscle. It is easily felt beneath the skin behind 
 the head of the fibula at the inner side of the tendon of the Biceps. It passes 
 between the tendon of the Biceps and outer head of the Gastrocnemius muscle, 
 winds around the neck of the fibula, between the Peroneus longus and the bone, 
 and divides beneath the muscle into the anterior tibial and musculo-cutaneous nerves. 
 
 The branches of the peroneal nerve, previous to its division, are articular and 
 cutaneous. 
 
 The articular branches (rami articulares) are three in number: two of these 
 accompany the superior and inferior external articular arteries to the outer side 
 of the knee. The upper one occasionally arises from the great sciatic nerve before 
 its bifurcation. The third (recurrent) articular nerve is given off at the point of 
 division of the peroneal nerve; it ascends with the anterior recurrent tibial artery 
 through the Tibialis anticus muscle to the front of the knee, which it supplies. 
 
 The Sural or Lateral Cutaneous Branch (n, cutaneu^ surae lateralis). — There may 
 be two or three of these branches. They supply the integument along the back 
 part and outer side of the leg (Fig. 652). The largest cutaneous branch of the 
 peroneal is the peroneal communicating (ramus anastomoticus peronaeus or commu- 
 nicans fibularis), arises near the head of the fibula, crosses the external head of 
 the Gastrocnemius to the middle of the leg, and joins with the communicans tibialis 
 to form the external saphenous. This nerve occasionally exists as a separate branch, 
 which is continued as far down as the heel. 
 
 The Anterior Tibial Nerve (n. peronaeus profundus) (Fig. 650) commences at the 
 bifurcation of the peroneal nerve, between the fibula and upper part of the Pero- 
 neus longus muscle, passes obliqiiely forward beneath the Extensor longus digi- 
 torum muscle to the forepart of the interosseous membrane, and gets into relation 
 with the anterior tibial artery above the middle of the leg; it then descends with 
 
THE SACBAL OB SCIATIC PLEXUS 1017 
 
 the artery to the front of the ankle-joint, where it divides into an external and an 
 internal branch. This nerve Hes at first on the outer side of the anterior tibial artery, 
 then in front of it, and again at its outer side at the ankle-joint. 
 
 The branches of the anterior tibial nerve in its course through the leg are tlie 
 muscular branches {rami musculares) to the Tibialis anticus, Extensor longus digi- 
 torum, Peronaeus tertius, and Extensor proprius hallucis muscles, and an articular 
 branch to the ankle-joint. 
 
 The external or tarsal branch of the anterior tibial passes outward across the 
 tarsus, beneath the Extensor brevis digitorum, and, having become enlarged, 
 like the posterior interosseous nerve at the wrist, supplies the Extensor brevis 
 digitorum muscle. From the enlargement three minute interosseous branches are 
 given off which supply the tarsal joints and the metatarso-phalangeal joints of the 
 second, third, and fourth toes. The first of these sends a filament to the second 
 dorsal interosseous muscle. 
 
 The internal branch, the continuation of the nerve, accompanies the dorsalis 
 pedis artery along the inner side of the dorsum of the foot, and at the first inter- 
 osseous space divides into two dorsal digital branches (nn. digitales dorsales hallucis 
 lateralis et digiti secundi medialis), which supply the adjacent sides of the great 
 and second toes (Fig. 651), communicating with the internal branch of the musculo- 
 cutaneous nerve. Before it divides it gives off an interosseous branch to the first 
 space, which supplies the metatarso-phalangeal joint of the great toe and sends a 
 filament to the First dorsal interosseous muscle. 
 
 The Musculo-cutaneous Nerve (n. peronaeus superficialis) (Fig. 650) supplies the 
 muscles on the fibular side of the leg and the integument of the dorsum of the foot 
 (Fig. 651) . It passes forward between the Peronei muscles and the Extensor longus 
 digitorum, pierces the deep fascia at the lower third of the leg on its front and outer 
 side, and divides into two branches. This nerve in its course between the muscles 
 gives off muscular branches (rami musculares) to the Peroneus longus and brevis, 
 and cutaneous filaments to the integument of the lower part of the leg (Fig. 651). 
 
 The internal branch (n. cidaneu^ dorsalis medialis) of the musculo-cutaneous 
 nerve passes in front of the ankle-joint, and divides into two dorsal digital branches 
 (nn. digitales dorsales pedis), one of which supplies the inner side of the great toe, 
 the other the adjacent sides of the second and third toes. It also supplies the 
 integument of the inner ankle and inner side of the foot, communicating with 
 the internal saphenous nerve, and joining with the anterior tibial nerve, between the 
 great and second toes. 
 
 The external branch (n. cutaneus dorsalis intermedius) , the smaller, passes along 
 the outer side of the dorsum of the foot, and divides into two dorsal digital branches, 
 the inner being distributed to the contiguous sides of the third and fourth toes, 
 the outer to the opposed sides of the fourth and fifth toes. It also supplies the 
 integument of the outer ankle and outer side of the foot, communicating with the 
 short saphenous nerve. 
 
 The branches of the musculo-cutaneous nerve supply all the toes excepting 
 the outer side of the little toe, which is supplied by the external saphenous nerve. 
 The adjoining sides of the great toe or second toe are also supplied by the 
 internal branch of the anterior tibial. It frequently happens that some of the 
 outer branches of the musculo-cutaneous are absent, their place being then taken 
 by branches of the external saphenous nerve. 
 
 Surgical Anatomy. — The lumbar plexus passes through the Psoas muscle, and, therefore, 
 in psoaa abscess any or all of its branches may be irritated, causing severe pain in the parts to 
 which the irritated nerves are distributed. The genifo-crural nerve is the one which is most 
 frequently implicated. This nerve is also of importance, as it is concerned in one of the 
 reflexes employed in the investigation of diseases of the spine. If the skin over the inner 
 side of the thigh just below Poupart's ligament, the part supplied by the crural branch of the 
 genito-crural nerve, be gently tickled in a male child, the testicle will be noticed to be drawn 
 
1018 THE NERVOUS SYSTEM 
 
 upward through the action of the Cremaster muscle, which is supplied by the genital branch of 
 the same nerve. The same result may sometimes be noticed in adults, and can almost always l)e 
 produced by severe stimulation. This reflex, when present, shows that the portion of the cord 
 from which the first and second lumbar nerves are derived is in a normal condition. 
 
 The anterior crural nerve is in danger of being injured in fractures of the true pelvis, since 
 the fracture most commonly takes place through the ascending ramus of the os pubis, at or 
 near the point where this nerve crosses the bone. It is also liable to be injured in fractures 
 and dislocations of the femur, and is likely to be pressed upon, and its functions impaired, 
 in some tumors growing in the pelvis. Moreover, on account of its superficial position, it is 
 exposed to injury in wounds and stabs in the groin. When this nerve is paralyzed, the patient 
 is unable to flex his hip completely, on account of the loss of motion in the Iliacus; or to extend 
 the knee on the thigh, on account of paralysis of the Quadriceps extensor cruris; there are com- 
 plete paralysis of the Sartorius and partial paralysis of the Pectineus. There is loss of sensation 
 down the front and inner side of the thigh, except in that part supplied by the crural branch of 
 the genito-crural nerve, and by the ilio-inguinal nerve. There is also loss of sensation down 
 the inner side of the leg and foot as far as the ball of the great toe. 
 
 The obturator nerve is of special surgical interest. It is rarely paralyzed alone, but occasionally 
 is paralyzed in association with the anterior crural. The principal interest attached to it is in 
 connection with its supply to the knee; pain in the knee being symptomatic of many diseases 
 in which the trunk of this nerve, or one of its branches, is irritated. Thus it is well known that 
 in the earlier stages of hip-joint disease the patient does not complain of pain in that articulation, 
 but on the inner side of the knee, or in the knee-joint itself, both these articulations being sup- 
 plied by the obturator nerve, the final distribution of the nerve being to the knee-joint. Again, 
 the same thing occurs in sacro-iliac disease: pain is complained of in the knee-joint or on its 
 inner side. The obturator nerve is in close relationship with the sacro-iliac articulation, passing 
 over it, and, according to some anatomists, distributing filaments to it. Again, in cancer of 
 the sigmoid flexure, and even in cases where masses of hardened faeces are impacted in this 
 portion of the gut, pain is complained of in the knee. Thfe left obturator nerve lies beneath the 
 sigmoid flexure, and is readily pressed upon and irritated when disease exists in this part of the 
 intestine. Finally, pain in the knee forms an important diagnostic sign in obturator hernia. 
 The hernial protrusion as it passes out through the opening in the obturator membrane presses 
 upon the nerve and causes pain in the parts supplied by its peripheial filaments. When the 
 obturator nerve is paralyzed, the patient is unable to press his knees together or to cross one 
 leg over the other, on account of paralysis of the Adductor muscles. Rotation outward of the 
 thigh is impaired from paralysis of the Obturator externus. Sometimes there is loss of sensation 
 in the upper half of the inner side of the thigh. 
 
 The great sciatic nerve is liable to be pressed upon by various pelvic tumors, giving rise to 
 pain along its trunk, to which the term sciatica is applied. Tumors growing from the pelvic 
 viscera, or bones, aneurisms of some of the branches of the internal iliac artery, calculus in the 
 bladder when of large size, accumulation of fajces in the rectum, may all cause pressure on the 
 nerve inside the pelvis, and give rise to sciatica. Outside the pelvis exposure to cold, violent 
 movements of the hip-joint, exostoses or other tumors growing from the margin of the sacro- 
 sciatic foramen, may also give rise to the same condition. When paralyzed there is loss of 
 motion in all the muscles below the knee, and loss of sensation in the same situation, except the 
 upper half of the back of the leg, supplied by the small sciatic and the upper half of the inner 
 side of the leg, when the communicating branch of the obturator is large. 
 
 The sciatic nerve has been frequently cut down upon and stretched, or has been acupunctured 
 for the relief of sciatica. The nerve has also been stretched in cases of locomotor ataxia, the 
 anaesthesia of leprosy, etc. In order to define it on the surface, a point is taken at the junction 
 of the middle and lower third of a line stretching from the posterior superior spine of the ilium 
 to the outer part of the tuber ischii, and a line is drawn from this point to the middle of the upper 
 part of the popliteal space. The line must be slightly curved with its convexity outward, and as 
 it passes downward to the lower border of the Gluteus maximus is slightly nearer the tuberosity 
 of the ischium than to the great trochanter, as it crosses a line drawn between these two points. 
 The operation of stretching the sciatic nerve is performed by making an incision over the course 
 of the nerve about the centre of the thigh. The skin, superficial structures, and deep fascia 
 having been divided, the interval between the inner and outer hamstrings is to be defined, and 
 these muscles respectively pulled inward and outward with retractors. The nerve will be found a 
 little to the inner side of the Biceps. It is to be separated from the surrounding structures, hooked 
 up with the finger, and stretched by steady and continuous traction for two or three minutes. 
 The sciatic nerve may also be stretched by what is known as the "dry" plan. The patient is 
 laid on his back, the foot is extended, the leg flexed on the thigh, and the thigh strongly flexed 
 on the abdomen. While the thigh is maintained in this position the leg is forcibly extended to 
 its full extent, and the foot as fully flexed on the leg. This last-named method is uncertain. 
 
 The position of the external popliteal nerve, close behind the tendon of the Biceps on the outer 
 side of the ham, should be remembered in subcutaneous division of the tendon. After it is divided, 
 
THE FIRST OB OLFACTORY NERVE 1019 
 
 a cord often rises up close beside it, which might be mistaken for a small undivided portion of 
 the tendon, and the surgeon might be tempted to reintroduce his knife and divide it. This must 
 never be done, as the cord is the external popliteal nerve, which becomes prominent as soon as 
 the tendon is divided. 
 
 THE CEREBRAL OR CRANIAL NERVES (NERVI CEREBRALES). 
 
 The cranial nerves arise from some part of the cerebro-spinal centre, and are 
 transmitted through foramina in the base of the cranium. They have been named 
 numerically, according to the order in which they pass through the dura mater 
 hning the base of the skull. Other names are also given to them, derived from 
 the parts to which they are distributed or from their functions. Taken in their 
 order, from before backward, they are as follows: 
 
 1st. Olfactory. 7th. Facial (Portio dura). 
 
 2d. Optic. 8th. Auditory (Portio mollis). 
 
 3d. Motor oculi. 9th. Glosso-pharyngeal. 
 
 4th. Trochlear (Pathetic). 10th. Pneumogastric (or Vagus). 
 
 5th. Trifacial (Trigeminus). 11th. Spinal accessory. 
 
 6th. Abducent. 12th. Hypoglossal. 
 
 All the cranial nerves are connected to some part of the surface of the brain. 
 This is termed their superficial or apparent origin. But their fibres may, in all 
 cases, be traced deeply into the substance of the brain and to some special centre of 
 gray matter, termed a nucleus. This is called their deep or real origin. The nerves, 
 after emerging from the brain at their apparent origin, pass through foramina or 
 tubular prolongations in the dura mater, leave the skull through foramina in its 
 base, and pass to their final distribution. 
 
 THE FIRST OR OLFACTORY NERVE (N. OLFACTORIUS) (Fig. 660). 
 
 The olfactory nerves are the special nerves of the sense of smell, and are 
 about twenty in number on each side. These filaments constitute the first or 
 olfactory nerves. They are given off from the under surface of the olfactory bulb, 
 an oval mass of a grayish color, which rests on the cribriform plate of the eth- 
 moid bone, and forms the anterior expanded extremity or a slender process of 
 brain-substance, named the olfactory tract. The olfactory tract and bulb have 
 already been described (p. 880). The olfactory tubercle {irigonum olfactorium) 
 is a small triangular mass of gray matter between the diverging roots of the optic 
 tract (p. 881). 
 
 Each nerve is surrounded by tubular prolongations from the dura mater and 
 pia mater, the former being lost on the periosteum lining the nose, the latter in 
 the neurilemma of the nerve. The nerves, as they enter the nares, are divisible 
 into two groups: an inner group, larger than those on the outer wall, spread out 
 over the upper third of the septum; and an outer set, which is distributed over 
 the superior turbinated bone, and the surface of the ethmoid in front of it. As 
 the filaments descend, they unite in a plexiform network, and are believed by 
 most observers to terminate by becoming continuous with the deep extremities 
 of the olfactory cells. 
 
 The olfactory nerves differ in structure from other nerves in being composed 
 exclusively of non-medullated fibres. They are deficient in the white substance 
 of Schwann, and consist of axis-cylinders, with a distinct nucleated sheath, 
 in which there are, however, fewer nuclei than in ordinary non-medullated 
 fibres. 
 
1020 
 
 THE NERVOUS SYSTEM 
 
 The Olfactory Path (Figs. 660 and 661). — Impressions from the upper portion 
 of the Schneiderian mucous membrane pass along the olfactory nerves, reach the 
 olfactory bulb, and traverse the olfactory tract to the cerebral hemisphere of 
 the same side. The cortical area of the sense of smell is in the uncus hip- 
 
 FiG. 660. — The olfactory bulb and tract. A, Schneiderian membrane in nose in which lies peripheral olfac- 
 tory neurone; B, glomerulus of olfactory bulb; C, mitral cells with dendrites in B and axones in D olfactory 
 lobe; E, granule cells; F, cells in olfactory lobe; H, G, fibres of olfactory tract. (Ramon y Cajal.) 
 
 pocampi. Impressions which are conveyed by the internal root pass to Broca's 
 area which is in front of the inner root of the olfactory tract, to the anterior 
 extremity of the gyrus fornicatus, the cingulum, and the uncinate fasciculus to 
 the cortical centre (Santee). Impressions travelling by the middle root reach 
 
 Fig. 661. — The olfactory system and tracts. Bol, olfactory bulb; Pol, olfactory tract; Rolp, deep olfactory 
 fibres; Roli, internal olfactory fibres; Role, external olfactory fibres. The deep fibres pass to the thalamus (Th) 
 and its nuclei; Tc, tuber cinereum; Tm, tuber mamillare; and to tsc, taenia semicircularis, and tth, taenia 
 thalami; also into the anterior commissure, coa. The internal olfactory fibres pass into the striae of Lancisi, 
 sL, and thus to the fasciola cinerea, Fc. The external olfactory fibres pass directly to the uncinate gyrus, U. Tg, 
 fornix from the carpus mamillare (Tm) to Ammon's horn (Cg); NA, nucleus amygdalae; Cing, cingulum; Cc, 
 corpus callosum; Fc, fasc. cinerea; FG, Gudden's fasciculus; FM, fasc. retroflexus of Meynert; Na, ant. nuc. of 
 thalamus; Gip, interpeduncular ganglion; Gh, ganglion; habenula; Qa, Qp, corp. quadrigemina; Po, pons; VA, 
 fascic. Vicq, d'Azyr. (Dejerine.) 
 
 the trigone and then pass to the cortical centre, as do those by way of the inter- 
 nal root, or they reach it by way of the anterior commissure (Santee). The outer 
 root conducts impulses directly to the cortical area. Fig. 661 shows the olfac- 
 tory path according to Dejerine. 
 
THE SECOND OB OPTIC NERVE 
 
 1021 
 
 Surgical Anatomy. — Destruction of the olfactory tract of one side causes loss of smell {anos- 
 mia) on the side of the injury, because the olfactory tract is uncrossed. In severe injuries to the 
 head the olfactory bulb may become separated from the olfactory nerves, thus producing loss 
 of the sense of smell, and with this a considerable loss in the sense of taste, as much of the per- 
 fection of the sense of taste is due to the sapid substances being also odorous and simultaneously 
 exciting the sense of smell. When the sense of smell is lost, an individual cannot distinguish 
 the pavor of food, but he can distinguish that a substance is salt, or sweet, or bitter, or acid. 
 The most usual cause of injury to the olfactory nerve is fracture of the base of the skull, the 
 line of fracture passing through the cribriform plate of the ethmoid bone, but a blow upon the 
 face, forehead, or back of the head, which does not produce fracture may injure the nerve. 
 
 THE SECOND OR OPTIC NERVE (N. OPTICUS) (Fig. 662). 
 
 The second or optic nerve, the special nerve of the sense of sight, is distributed 
 exclusively to the eyeball. It joins the eyeball about one-eighth of an inch to the 
 inner side of the axis of the globe, penetrates the fibrous coat and the vascular 
 tunic, and at the optic disk is expanded and forms part of the retina. The nerves 
 of opposite sides are connected together at the commissure, and from the back 
 of the commissure they may be traced to the 
 brain, under the name of the optic tracts. 
 
 The Optic Tract. — The optic tract, at its 
 connection with the brain, is divided into two 
 bands, external and internal. The external 
 band is the larger; it arises from the external 
 geniculate body and from the under part of the 
 pulvinar of the optic thalamus, and is partly 
 continuous with the brachium of the anterior 
 or upper quadrigeminal body. The internal 
 band curves around the crusta, and passes 
 beneath the internal geniculate body, with 
 which it is connected, and then appears to lose 
 itself in the brachium of the posterior or infe- 
 rior quadrigeminal body. The fibres by which 
 it is connected to the internal geniculate body 
 are merely commissural, forming part of Gud- 
 
 den's commissure. From this origin the tract 
 
 Fig. 
 
 662. — The left optic nerve and optic 
 tracts. 
 
 winds obliquely across the under surface of 
 the crus cerebri, in the form of a flattened band, and is attached to the crus by 
 its anterior margin. It then assumes a cylindrical form, and, as it passes for- 
 ward, *is connected with the tuber cinereum and lamina cinerea. It finally joins 
 with the tract of the opposite side to form the optic commissure. 
 
 The Optic Commissure (chiasma opticum) (P'igs. 662 and 663, and p. 882) 
 is somewhat quadrilateral in form, rests upon the olivary eminence and on the 
 
 anterior part of the diaphragma sellae, being bounded, 
 
 above, by the lamina cinerea ; behind by the tuber 
 
 cinerereum; on either side by the anterior perforated 
 
 space. Within the commissure, the optic nerves of 
 
 the two sides undergo a partial decussation (Figs. 663 
 
 and 664). The fibres which form the inner margin of 
 
 each tract and posterior part of the commissure have 
 
 no connection with the optic nerves. They simply 
 
 pass across the commissure from one hemisphere 
 
 of the brain to the other, and connect the internal geniculate bodies of the two 
 
 sides. They are known as the inter-cerebral fibres of the optic commissure or the 
 
 commissure of Gudden. The remainder and principal part of the optic com- 
 
 FiG. 663. — Course of the fibres 
 in the optic commissure. 
 
1022 THE NERVOUS SYSTEM 
 
 missure consists of two sets of fibres, crossed and uncrossed. The crossed fibres, 
 which are the more numerous, occupy the central part of the chiasma, and pass 
 from the optic tract of one side to the optic nerve of the other, decussating in 
 the commissure with similar fibres of the opposite tract. The uncrossed fibres 
 occupy the outer part of the chiasma, and pass from the tract of one side to the 
 nerve of the same side.* 
 
 The great majority of the fibres of the optic nerve consist of the afferent axones 
 of nerve-cells in the retina. Some few, however, are efferent fibres, and grow out 
 from the brain. The afferent fibres end in arborizations around the cells in the 
 external geniculate body, pulvinar, nucleus of the motor oculi nerve, and the 
 upper quadrigeminal body. The external geniculate body and pulvinar are some- 
 times termed the lower visual centres. From these nuclei other fibres are pro- 
 longed to the cortical half -visual centre, which, according to most observers, is 
 situated in the cuneus, and probably also, to a small extent, in the curved portion 
 of the occipital lobe (Fig. 664). 
 
 It should be stated that some fibres are detached from the optic tract, and pass 
 through the crus cerebri to the nucleus of the third nerve. These fibres are small, 
 and may be regarded as afferent branches for the sphincter pupillae and ciliary 
 muscles. Other fibres pass to the cerebellum through its superior peduncles, while 
 others, again, are lost in the pons. 
 
 The optic nerves arise from the forepart of the commissure, and, diverging 
 from one another, become rounded in form and firm in texture, and are enclosed in 
 a sheath derived from the pia mater and arachnoid. As each nerve passes through 
 the corresponding optic foramen it receives a sheath from the dura mater; and as 
 it enters the orbit this sheath subdivides into two layers, one of which becomes con- 
 tinuous with the periosteum of the orbit; the other forms the proper sheath of the 
 nerve and surrounds it as far as the sclerotic. The nerve passes forward and out- 
 ward through the cavity of the orbit, pierces the sclerotic and choroid coats at the 
 back part of the eyeball, about one-eighth of an inch to the nasal side of its centre, 
 and expands into the retina. A small artery, the arteria centralis retinae, per- 
 forates the optic nerve a little behind the globe, and runs along its interior in a 
 tubular canal of fibrous tissue. It supplies the inner surface of the retina, and is 
 accompanied by corresponding veins. 
 
 The Optic Path (Fig. 664). — Impulses of sight originate in the retina. From 
 the right half of each retina impulses pass by way of the optic nerves to the right 
 optic tract. From the left half of each retina impulses pass by way of the optic 
 nerves to the left optic tract. Impulses from the nasal half of each retina pass 
 by decussated fibres to the opposite optic tract. Impulses from the temporal 
 half of the retina pass by unflecussated fibres to the optic tract of the same side, 
 although a few fibres may cross farther back through the quadrigeminal bodies. 
 From the optic tract impulses pass to the external geniculate body, pulvinar, 
 upper quadrigeminal body, and nucleus of the motor oculi nerve. From the 
 external geniculate body and pulvinar impulses pass by way of the optic radiatus 
 through the posterior segment of the internal capsule to the half-vision centre in 
 the cuneus and the convexity of the occipital lobe. The superior quadrigeminal 
 body and the nucleus of the third nerve produce ocular reflexes and the pupil- 
 lary reflex. 
 
 Surgical Anatomy. — The optic nerve is peculiarly liable to become the seat of neuritis^ or 
 undergo atrophy in affections of the central nervous system, and, as a rule, the pathological 
 relationship between the two affections is exceedingly difficult to trace. There are, however, 
 certain points in connection with the anatomy of this nerve which tend to throw light upon the 
 frequent association of these affections with intracranial disease: (1) From its mode of develop- 
 
 ^ A specimen of congenital absence of the optic commissure is to be found in the Museum of the Westminster 
 Hospital. See also Henle, Nervenlehre, p. 393, ed 2. — Ed. of 15th English edition. 
 
THE SECOND OB OPTIC NERVE 
 
 1023 
 
 ment and from its structure the optic nerve must be regarded as a prolongation of the brain-sub- 
 stance, rather than as an ordinary cerebro-spinal nerve. (2) As it passes from the brain it receives 
 sheaths from the three cerebral membranes --a perineural sheath from the pia mater, an inter- 
 mediate sheath from the arachnoid, and an outer sheath from the dura mater, which is also con- 
 nected with the periosteum as it passes through the optic foramen. These sheaths are separated 
 from each other by spaces which communicate with the subdural and subarachnoid spaces 
 respectively. The innermost or perineural sheath sends a process around the arteria centralis 
 retinae into the interior of the nerve, and enters intimately into its structure. Thus inflammatory 
 affections of the meninges or of the brain may readily extend themselves along these spaces or 
 along the interstitial connective tissue in the nerve. 
 
 The course of the fibres in the optic commissure has an important pathological bearing, and 
 has been the subject of much controversy. Microscopic examination, experiments, and pathology 
 all seem to point to the fact that there is a partial decussation of the fibres, each tract supplying 
 
 
 
 [left eyeI 
 
 
 f RIGHT 1 
 1 EYE 1 
 
 /^^^MACOLA LUTEA 
 
 UNCROSSED FIBRES 
 
 FROM 
 
 LEFT HALf\ 
 
 Ov 
 
 yy'Xv 
 
 OF LEFT RETINA TO 
 
 LEFT 
 
 centres 
 
 ^B^ 
 
 ^ CHIASMA 
 
 CROSSED FIBRES FROM 
 
 LEFT 
 
 HALF^ A 
 
 #^ 
 
 JRE\C\S» 
 
 OF RIGHT i?ETINA TO 
 TRES 
 
 LEFT 
 
 ""T iS 
 
 ^r/G U D D E N 
 ^OMMISSl 
 
 Aanterioro) 
 
 laUADPl^ 
 
 ^GEMINA'^ 
 
 .INTERNAL GENICULATE BODY 
 AND ITS NERVE CELLS 
 
 -EXTERNAL GENICULATE BODY 
 AND ITS NERVE CELLS 
 
 POSTERIOR aUADRISEMINA^ 
 
 CONNECTING LEFT SIDE OF BRAIN 
 WITH LEFT HALF OF RETINA AND I 
 CONSEQUENTLY RIGHT HALF OF I 
 FIELD OF VISION J 
 
 loPTIC RADIATION 
 
 Fig. 664. — Diagram of the course of the optic fibres. (W. Keiller in Gerrish's Anatomy.) 
 
 the corresponding half of each eye, so that the right tract supplies the right half of each eye, 
 and the left tract the left half of each eye. At the same time, Charcot believes — and his view 
 has met with general acceptation- -that the fibres which do not decussate at the optic commis- 
 sure have already decussated in the corpora quadrigemina, so that lesion of the cerebral centre 
 of one side causes complete blindness of the opposite eye, because both sets of decussating fibres 
 are destroyed. Whereas should one tract — say the right —be destroyed by disease, there will be 
 blindness of the right half of both retinae. 
 
 An antero-posterior section through the commissure would divide the decussating filwes, 
 and would therefore produce blindness of the inner half of each eye; while a section at the mar- 
 gin of the side of the optic commissure would produce blindness of the external half of the retina . 
 of the same side. 
 
 The optic nerve may also be affected in injuries or diseases involving the orbit, in fractures 
 of the anterior fossa of the ba.se of the skull, in tumors of the orbit itself, or those invading this 
 cavity from neighboring parts. 
 
1024 
 
 THE NERVOUS SYSTEM 
 
 Infratrochlear 
 nerve. 
 
 THE THIRD OR MOTOR OCULI NERVE (N. OCULOMOTORIUS) 
 
 (Figs. 665, 666, 669). 
 
 The third or motor ocuH nerve supplies all the muscles of the orbit except the 
 Superior oblique and External rectus; it also supplies, through its connection 
 with the ciliary ganglion, the Sphincter muscle of the iris and the Ciliary muscle. 
 It is rather a large nerve, of rounded form and firm texture. 
 
 Its apparent origin is from the inner surface of the crus cerebri, immediately in 
 front of the pons Varolii. The deep origin may be traced through the substantia 
 nigra and tegmentum of the crus to a nucleus situated on either side of the median 
 line beneath the floor of the aqueduct of Sylvius (Fig. 613). The nucleus of the 
 third nerve also receives fibres from the sixth nerve of the opposite side. These 
 will be referred to again in the description of the latter nerve. The nucleus of 
 
 the third nerve, considered from a 
 physiological standpoint, can be 
 subdivided into several smaller 
 groups of cells, each group con- 
 trolling a particular muscle. The 
 nerves to the different muscles 
 appear to take their origin from 
 before backward, as follows: In- 
 ferior oblique. Inferior rectus, 
 Superior rectus and Levator pal- 
 pebrae, Internal rectus; while from 
 the anterior end of the nucleus the 
 fibres for accommodation and for 
 the Sphincter pupillae take their 
 origin. 
 
 On emerging from the brain, the 
 nerve is invested with a sheath of 
 pia mater, and enclosed in a pro- 
 longation from the arachnoid. It 
 passes between the superior cere- 
 bellar and posterior cerebral arte- 
 ries, and then pierces the dura 
 mater in front of and external to 
 the posterior clinoid process, pass- 
 ing between the two processes from 
 the free and attached borders of 
 the tentorium, which are prolonged 
 forward to be connected with the 
 anterior and posterior clinoid pro- 
 cesses of the sphenoid bone. It 
 passes along the outer wall of the 
 cavernous sinus (Figs. 454 and 455); above the other orbital nerves, receiving in 
 its course one or two filaments from the cavernous plexus of the sympathetic, and 
 a communicating branch from the first division of the fifth. It then divides 
 into two branches, which enter the orbit through the sphenoidal fissure, between 
 th^ two heads of the External rectus muscle (Fig. 665). On passing through 
 the fissure, the nerve is placed below the fourth and the frontal and lachrymal 
 branches of the ophthalmic nerve, and has passing between its two divisions the 
 nasal nerve (Fig. 675). 
 
 The Superior Division (ramus superior) (Fig. 666). — The superior division, the 
 smaller, passes inward over the optic nerve, and supplies the Superior rectus and 
 Levator palpebrae. 
 
 Fig. 665.- 
 
 Motor root. / W — Eeciirrent filament 
 Sensory root. to dura mater. 
 
 -Nerves of the orbit, seen from above. 
 
THE FOURTH OB TROCHLEAR NERVE 
 
 1025 
 
 The Inferior Division {ramus inferior) (Fig. 666) . — The inferior division, the larger, 
 divides into three branches. One passes beneath the optic nerve to the Internal 
 rectus; another, to the Inferior rectus; and the third, the longest of the three, 
 passes forward between the Inferior and External recti to the Inferior oblique. 
 From this latter a short, thick branch, radix brevis ganglii ciliaris, is given off 
 to the lower part of the lenticular ganglion and forms its short or motor root 
 
 LEVATOR PALPEBniE. 
 
 OBLIQUUS 
 INFERIOR. 
 
 Tig. 666. — Plan of the motor oculi nerve. (The lenticular ganglion is not shown in normal position. If it were 
 the short root would enter the inferior angle.) (After Flower.) 
 
 (Figs. 666, 669, and 670). It also gives off one or two filaments to the Inferior 
 rectus. All these branches enter the muscles on their ocular surface, except that 
 to the Inferior oblique, which enters its posterior border. 
 
 Surgical Anatomy. — Paralyse of the third nerve may be the result of many causes : as cere- 
 bral disease; conditions causing pressure on the cavernous sinus; periostitis of the bones entering 
 into the formation of the sphenoidal fissure; fracture of the orbit. It results, when complete, in 
 (1) ptosis, or drooping of the upper eyelid, in consequence of the Levator palpebrae being par- 
 alyzed; (2) external strabismus, on account of the unopposed action of the External rectus muscle, 
 which is not supplied by the third nerve, and is not therefore paralyzed ; (3) dilatation of the pupil, 
 because the sphincter fibres of the iris are paralyzed; (4) lo.ss of power of accommodation, as 
 the sphincter pupillae, the ciliary muscle, and the Internal rectus are paralyzed; (5) slight promi- 
 nence of the eyeball, owing to most of its muscles being relaxed. Occasionally paralysis may 
 affect only a part of the nerve; that is to say, there may be, for example, a dilated and fixed 
 pupil, with ptosis, but no other signs. Irritation of the nerve causes spasm of one or other of 
 the muscles supplied by it; thus, there may be internal strabismus from spasm of the Internal 
 rectus; accommodation for near objects only from spasm of the Ciliary muscle, or contraction of 
 the pupil (myosis), from irritation of the sphincter of the pupil. 
 
 THE FOURTH OR TROCHLEAR NERVE (N. TROCHLEARIS) (Figs. 665 and 669). 
 
 The fourth or trochlear nerve or Patheticus, the smallest of the cranial nerves, 
 supplies the Superior oblique muscle. 
 
 The apparent origin, at the base of the brain, is on the outer side of the crus 
 cerebri, just in front of the pons Varolii, but the fibres can be traced backward 
 behind the corpora quadrigemina to the valve of Vieussens, on the upper surface 
 of which the two nerves decussate, decussatio nervonun trochlearium. Its deep 
 origin may be traced to a nucleus in the floor of the aqueduct of Sylvius imme- 
 diately below that of the third nerve, with which it is continuous (Fig. 618). 
 
 Emerging from the upper end of the valve of Vieussens, the nerve is directed 
 outward across the superior peduncle of the cerebellum, and then winds forward 
 
 65 
 
1026 ' THE NERVOUS SYSTEM 
 
 around the outer side of the crus cerebri, immediately above the pons VaroHi, 
 pierces the dura mater in the free border of the tentorium cerebelH, just behind, 
 and external to, the posterior cHnoid process, and passes forward in the outer 
 wall of the cavernous sinus, between the third nerve and the ophthalmic division 
 of the fifth (Figs. 454 and 455). It crosses the third nerve and enters the orbit' 
 through the sphenoidal fissure (Fig. 675). It now becomes the highest of all 
 the nerves, lying at the inner extremity of the fissure internal to the frontal 
 nerve.- In the orbit it passes inward, above the origin of the Levator pal- 
 pebrae, and finally enters the orbital surface of the Superior oblique hiuscle. 
 In the outer wall of the cavernous sinus this nerve is not infrequently blended 
 with the ophthalmic division of the fifth. 
 
 Branches of Communication. — In the outer wall of the cavernous sinus it 
 receives some filaments from the cavernous plexus of the sympathetic. In the 
 sphenoidal fissure it occasionally gives off a branch to assist in the formation of 
 the lachrymal nerve. 
 
 Branches of Distribution. — It gives off a recurrent branch, which passes 
 backward between the layers of the tentorium, dividing into two or three 
 filaments which may be traced as far back as the wall of the lateral sinus. 
 
 Surgical Anatomy. — The fourth nerve when 'paralyzed causes loss of function in the Superior 
 obHque, so that the patient is unable to turn his eye downward and outward. Should the patient 
 attempt to do this, the eye on the affected side is twisted inward, producing diplopia or double 
 vision. Accordingly, it is said that the first symptom of this disease which presents itself is 
 giddiness when going down hill or in descending stairs, owing to the double vision induced by 
 the patient looking at his steps while descending. 
 
 THE FIFTH, TRIGEMINAL OR TRIFACIAL NERVE (N. TRIGEMINUS) 
 
 (Figs. 665, 667 668, 669, 670, 671, 672, 673, 674). 
 
 The fifth, trigeminal or trifacial nerve is the largest cranial nerve. It resembles 
 a spinal nerve (1) in arising by two roots; (2) in having a ganglion developed on 
 its posterior root; and (3) in its function, since it is a compound nerve. It is the 
 great sensory nerve of the head and face and the motor nerve of the muscles 
 of mastication. Its upper two divisions, portio major, are entirely sensory, the 
 third division, portio minor, is partly sensory and partly motor. It arises by two 
 roots: of these the anterior is the smaller, and is the motor root (Fig. 613); the 
 posterior, the larger and sensory root. Its superficial origin is from the side of 
 the pons Varolii, nearer to the upper than the lower border (Fig. 613). The 
 smaller root consists of three or four bundles ; the larger root consists of numer- 
 ous bundles of fibres, varying in number from seventy to a hundred. The two 
 roots are separated from one another by a few of the transverse fibres of the 
 pons. The deep origin of the larger or sensory root is chiefly from a long tract 
 in the medulla, the lower sensory nucleus, which is continuous below with the 
 substantia gelatinosa of Rolando (Fig. 607). The fibres from this nucleus form 
 the so-called ascending root of the fifth nerve (Fig. 607) ; they pass upward through 
 the pons and join with fibres from the locus caeruleus or upper sensory nucleus 
 (Fig. 613), which is situated to the outer side of the nucleus, from which the lower 
 part of the motor root takes origin. The deep origin of the smaller or motor 
 root is derived partly from a nucleus embedded in the gray matter of the upper 
 part of the floor of the fourth ventricle and partly from a collection of nerve- 
 cells situated at the side of the aqueduct of Sylvius, from which the fibres pass 
 downward under the name of the descending root of the fifth nerve (Fig. 613). 
 
 The two roots of the nerve pass forward below the tentorium cerebelli as it 
 bridges over the notch on the inner part of the superior border of the petrous por- 
 tion of the temporal bone (Fig. 668) ; they then run between the bone and the dura 
 
THE FIFTH, TRIGEMINAL OB TRIFACIAL NERVE 1027 
 
 mater to the apex of the petrous portion of the temporal bone, where the fibres of 
 the sensory root form the large semilunar or Gasserian ganglion (Figs. 667 and 668), 
 while the motor root passes beneath the ganglion without having any connection 
 with it, and joins outside the cranium with one of the trunks derived from it 
 (Figs. 667 and 668). 
 
 OCULOMOTOR TROCHLEAR ABDUCENS 
 NERVE NERVE NERVE 
 
 MOTOR PORTION 
 OF FIFTH NERVE 
 
 SENSORY PORTION 
 OF FIFTH NERVE 
 
 SEMILUNAR NERVE 
 
 (Gasserian ganglion) 
 
 SUPERIOR 
 
 MAXILLARY 
 
 NERVE 
 
 MANDIBULAR 
 NERVE 
 
 Fig. 667. — The right semilunar or Gasserian ganglion, viewed from the medial side. (Spalteholz.) 
 
 The Gasserian or Semilunar Ganglion^ {ganglion semilunare) (Figs. 667, 668, 
 669, 670, 671, 672, and 673). — The Gasserian or semilunar ganglion is lodged in an 
 osteo-fibrous space, the cavum Meckelii 
 (Figs. 545 and 668), near the apex 
 of the petrous portion of the temporal 
 bone. The ganglion is of somewhat 
 crescentic form, with its convexity 
 turned forward. Its upper surface 
 is intimately adherent to the dura 
 mater. Besides the small or motor 
 root, the large. superficial petrosal nerve 
 lies underneath the ganglion. 
 
 Branches of Communication. — This 
 ganglion receives on its inner side 
 filaments from the carotid plexus of 
 the sympathetic. 
 
 Branches of Distribution. — It gives 
 off minute branches to the ten- 
 torium cerebelli and the dura mater 
 in the middle fossa of the cranium. 
 From its anterior border, which is di- 
 rected forward and outward, three Fig. 668.— The course of the motor root of the fifth nerve. 
 
 ' (Poirier and Charpy.) 
 
 large branches proceed — the oph- 
 thalmic, superior maxillary, and inferior maxillary. The ophthalmic and superior 
 maxillary consist exclusively of fibres derived from the larger root and ganglion, 
 and are solely nerves of common sensation. The third division, or inferior 
 
 ' A Viennese anatomist, Raimund BaUhasar Hirsch (1765), was the first who recognized the ganglionic nature 
 of the swelling on the sensory root of the fifth nerve, and called it, in honor of his otherwise unknown teacher, 
 Jon. Laur. Gasser, the " Ganglion Gasseri." .Julius Casserius, whose name is giv«n to the musculo-cutaneous 
 nerve of the arm. was professor at Padua, 1545-1605. (See Hyrtl, Lehrbuch der Anatomic, p. 895 and p. 55.) — 
 Ed. of 15th English edition. 
 
 SENSORY ROOT. 
 DIVIDED 
 
 SUPERIOR 
 PETROSAL SINUS 
 
 SEVENTH AND 
 EIGHTH NERVES 
 
1028 
 
 THE NERVOUS SYSTEM 
 
 maxillary, is joined outside the cranium by the motor root. This, therefore, 
 strictly speaking, is the only portion of the fifth nerve which can be said to 
 resemble a spinal nerve. 
 
 Ophthalmic Nerve (n.ophthalmic^is) (Figs. 665, 667, 668, 669, 670, 671, 672, and 
 673). — The ophthalmic, or first division of the fifth, is a sensory nerve. It supplies 
 the eyeball, the lachrymal gland, the mucous lining of the eye and nasal fossae, and 
 the integument of the eyebrow, forehead, and nose (Fig. 674). It is the smallest 
 of the three divisions of the fifth, arising from the upper part of the Gasserian 
 ganglion. It is a short, flattened band, about an inch in length, which passes for- 
 ward along the outer wall of the cavernous sinus (Figs. 454 and 455) , below the other 
 nerves (Fig. 667), and just before entering the orbit, through the sphenoidal fissure, 
 divides into three branches — lachrymal, frontal, and nasal (Figs. 665, 669, 670, 671). 
 
 Branches of Communication. — The ophthalmic nerve gives off in the cavernous 
 sinus a branch to the dura mater {n. tentorii), is joined by filaments from the 
 cavernous plexus of the sympathetic, and gives off minute branches to communi- 
 cate with the third and sixth nerves, and not infrequently with the fourth. 
 
 Internal carotid artery 
 and carotid plexus. 
 
 Fig. 669. — Nerves of the orbit and ophthalmic ganglion, side view. 
 
 Branches of Distribution. — It gives off recurrent filaments which pass between 
 the layers of the tentorium, and then divide into — 
 
 Lachrymal. Frontal. Nasal. 
 
 The Lachrymal Nerve {n. lacrimalis) (Figs. 665, 669, 670, and 671).— The 
 lachrymal is the smallest of the three branches of the ophthalmic. It sometimes 
 receives a filament from the fourth nerve, but this is possibly derived from the 
 branch of communication which passes from the ophthalmic to the fourth. It 
 passes forward in a separate tube of dura mater, and enters the orbit through the 
 narrowest part of the sphenoidal fissure (Fig. 675) . In the orbit it runs along the 
 upper border of the External rectus muscle, with the lachrymal artery, and com- 
 municates with the temporo-malar branch of the superior maxillary nerve. It 
 enters the lachrymal gland and gives off several filaments, which supply the 
 gland and the conjunctiva. Finally, it pierces the superior palpebral ligament, 
 and terminates in the integument of the upper eyelid, joining with filaments of 
 the facial nerve. The lachrymal nerve is occasionally absent, when its place is 
 taken by the temporal branch of the superior maxillary. Sometimes the latter 
 branch is absent, and a continuation of the lachrymal is substituted for it. 
 
THE FIFTH, TRIGEMINAL OB TRIFACIAL NERVE' 1029 
 
 Fig. 670. — Plan of the fifth cranial nerve. (The lenticular ganglion is displaced from its normal position. 
 The portion where the short root enters is really the inferior angle; in the diagram it is the superior angle.) 
 (After Flower.) 
 
1030 THE NERVOUS SYSTEM 
 
 The Frontal Nerve (n. frontalis) (Figs. 665, 669, and 670). — The frontal is the 
 largest division of the ophthalmic, and may be regarded, both from its size and 
 direction, as the continuation of the nerve. It enters the orbit above the muscles, 
 through the sphenoidal fissure (Fig. 675) , and runs forward along the middle line, 
 between the Levator palpebrae and the periosteum. Midway between the apex and 
 the base of the orbit it divides into two branches, supratrochlear and supra-orbital. 
 
 The Supratrochlear Branch (n. supratrochlear is) (Figs. 665 and 670), the smaller 
 of the two, passes inward, above the pulley of the superior oblique muscle, and 
 gives off a descending filament, which joins with the infratrochlear branch of the 
 nasal nerve. It then escapes from the orbit between the pulley of the Superior 
 oblique and the supraorbital foramen, curves up on to the forehead close to the 
 bone, ascends beneath the Corrugator supercilii and Occipito-frontalis muscles, 
 and, dividing into branches which pierce these muscles, it supplies the integu- 
 ment of the lower part of the forehead on either side of the middle line and 
 sends filaments to the conjunctiva and skin of the upper lid. 
 
 The Supraorbital Branch (n. supraorbitalis) (Figs. 675 and 670) passes forward 
 through the supraorbital foramen, and gives off, in this situation, palpebral fila- 
 ments to the upper eyelid. It then ascends upon the forehead, and terminates in 
 cutaneous and pericranial branches. 
 
 The cutaneous branches, two in number, an inner and an outer, supply the integ- 
 ument of the cranium as far back as the vertex. They are at first situated beneath 
 the Occipito-frontalis, the inner branch perforating the frontal portion of the 
 muscle, the outer branch its tendinous aponeurosis. 
 
 The pericranial branches are distributed to the pericranium over the frontal and 
 parietal bones. 
 
 The Nasal Nerve (n. nasociliaris) (Figs. 665, 669, and 670). — The nasal nerve 
 is intermediate in size between the frontal and lachrymal, and more deeply placed 
 than the other branches of the ophthalmic. It enters the orbit by way of the 
 sphenoidal fissure (Fig. 675) between the two heads of the External rectus, 
 and passes obliquely inward across the optic nerve, beneath the Superior rectus 
 and Superior oblique muscles, to the inner wall of the orbit, where it passes 
 through the anterior ethmoidal foramen, and, entering the cavity of the cranium, 
 traverses a shallow groove on the front of the cribriform plate of the ethmoid 
 bone, and passes down, through the slit by the side of the crista galli, into the 
 nose (Fig. 672), where it divides into two branches, an internal and an external 
 branch. The internal branch {rami nasales mediates) supplies the mucous mem- 
 brane near the forepart of the septum of the nose. The external branch (rami 
 nasales laterales) descends in a groove on the inner surface of the nasal bone, and 
 supplies a few filaments to the mucous membrane covering the forepart of the 
 outer wall of the nares as far as the inferior spongy bone ; it then leaves the cavity 
 of the nose, between the lower border of the nasal bone and the upper lateral 
 cartilage of the nose, and, passing down beneath the Compressor nasi, supplies 
 the integument of the ala and the tip of the nose, joining with the facial nerve. 
 
 Branches. — The branches of the nasal nerve are the ganglionic, ciliary, and infra- 
 trochlear. 
 
 The Ganglionic Branch, or the long root of the ciliary ganglion (radix longa ganglii 
 ciliaris) (Figs. 666, 669, and 670), is a slender branch, about half an inch in 
 length, which usually arises from the nasal nerve, between the two heads of the 
 External rectus muscle. It passes forward on the outer side of the optic nerve, 
 and enters the postero-superior angle of the ciliary ganglion, forming its long 
 root. It is sometimes joined by a filament from the cavernous plexus of the 
 sympathetic or from the superior division of the third nerve. 
 
 The Long Ciliary Nerves (nn. ciliares longi) (Fig. 670), two or three in number, 
 are given off from the nasal as it crosses the optic nerve. They join the sliort 
 
THE FIFTH, TRIGEMINAL OB TRIFACIAL NERVE 1031 
 
 ciliary nerves (Figs. 666, 669, and 670) from the ciliary ganglion, pierce the pos- 
 terior part of the sclerotic, and, running forward between it and the choroid, are 
 distributed to the ciliary muscle, iris, and cornea. 
 
 The Infratrochleax Branch (n. injratrochlearis) (Figs. 665 and 670) "is given off 
 just before the nasal nerve passes through the anterior ethmoidal foramen. It 
 runs forward along the upper border of the Internal rectus muscle, and is joined, 
 beneath the pulley of the Superior oblique, by a filament from the supratrochlear 
 nerve. It then passes to the inner angle of the eye, and supplies the integument 
 of the eyelids and side of the nose, the conjunctiva, the lachrymal sac, and the 
 caruncula lacrimalis. 
 
 Connected with the three divisions of the fifth nerve are four small ganglia. 
 With the first division is connected the ophthalmic ganglion; with the second 
 division, the spheno-palatine or Meckel's ganglion; and with the third, the otic and 
 submaxillary ganglia. All the four receive sensory filaments from the fifth nerve, 
 and motor and sympathetic filaments from various sources; these filaments are 
 called the roots of the ganglia. 
 
 The Ophthalmic, Lenticular or Ciliary Ganglion {ganglion cUiare) (Figs. 666, 669, 
 and 670) is a small, quadrangular, flattened ganglion, of a reddish-gray color, and 
 about the size of a pin's head, situated at the back part of the orbit between the 
 optic nerve and the External rectus muscle, lying generally on the outer side of 
 the ophthalmic artery. It is enclosed in a quantity of loose fat, which makes its 
 exposure by dissection somewhat difficult. 
 
 Its branches of communication or roots are three, all of which enter its posterior 
 border. One, the long or sensory root {radix longa ganglii ciliaris), is derived 
 from the nasal branch of the ophthalmic and joins the superior angle of the 
 ganglion. The second, the short or motor root {radix hrevis ganglii ciliaris), is a 
 short, thick nerve, occasionally divided into two parts, which is derived from the 
 branch of the third nerve to the Inferior oblique muscle, and is connected with 
 the inferior angle of the ganglion. The third, the sympathetic root {radix sympa- 
 thetica ganglii ciliaris), is a slender filament from the cavernous plexus of the 
 sympathetic. This is frequently blended with the long root, though it some- 
 times passes to the ganglion separately. According to Tiedemann, this ganglion 
 receives a filament of communication from the spheno-palatine ganglion. 
 
 Its branches of distribution are the short ciliary nerves {nn. ciliares breves) (Figs. 
 666, 669, and 670) . These are delicate filaments, from six to ten in number, which 
 arise from the forepart of the ganglion in two bundles, connected with its superior 
 and inferior angles; the lower bundle is the larger. They run forward with the 
 ciliary arteries in a wavy course, one set above and the other below the optic 
 nerve, and are accompanied by the long ciliary nerves from the nasal nerve 
 They pierce the sclerotic at the back part of the globe, pass forward in delicate 
 grooves on its inner surface, and are distributed to the Ciliary muscle, iris, and 
 cornea. Tiedemann has described one small branch as penetrating the optic 
 nerve with the arteria centralis retinae. 
 
 The circular fibres of the iris are innervated by the third nerve; the radiating 
 fibres are innervated by the sympathetic. 
 
 The Superior Maxillary Nerve (n. maxillaris) (Figs. 667, 668, 669, 670, 671, 
 and 672). — The superior maxillary or second division of the fifth is a sensory nerve. 
 It is intermediate, both in position and size, between the ophthalmic and inferior 
 maxillary. It commences at the middle of the Gasserian ganglion as a flattened 
 plexiform band (Fig. 667), and, passing horizontally forward, it leaves the skull 
 through the foramen rotundum (Fig. 668), where it becomes more cylindrical in 
 form and firmer in texture. It then crosses the spheno-maxillary fossa (Fig. 67), 
 enters the orbit through the spheno-maxillary fissure, traverses the infraorbital 
 canal in the floor of the orbit, and appears upon the face of the infraorbital fora- 
 
1032 THE NERVOUS SYSTEM 
 
 men. After it enters the infraorbital canal the nerve is usually called the infra- 
 orbital (n. infraorbitalis), and the infraorbital nerve is the terminal branch of 
 the superior maxillary nerve (Fig. 671) . At its termination the nerve lies beneath 
 the Levator labii superioris muscle, and divides into a leash of branches, which 
 spread out upon the side of the nose, the lower eyelid, and upper lip, joining 
 with filaments of the facial nerve. 
 
 Branches of Distribution. — The branches of this nerve may be divided into four 
 groups: 1. Those given off in the cranium. 2. Those given off in the spheno- 
 maxillary fossa. 3. Those in the infraorbital canal. 4. Those on the face. 
 
 In the cranium . . . Meningeal. 
 
 {Orbital or temporo-malar. 
 Spheno-palatine. 
 Posterior superior dental. 
 
 T p 1 •, 1 1 f Middle superior dental. 
 
 Intraorbital canal > . . i a . • ^ • j^i 
 
 ( Anterior superior dental. 
 
 ( Palpebral. 
 
 On the face ^ Nasal. 
 
 I Labial. 
 
 The Meningeal Branch (ii. meningeus medius). — The meningeal branch is given 
 off by the superior maxillary nerve directly after its origin from the Gasserian 
 ganglion; it accompanies the middle meningeal artery and supplies the dura 
 mater of the middle fossa of the base of the skull. 
 
 The Orbital or Temporo-malar Branch (w. zygomaticus) (Figs. 669, 670, and 671). 
 — The orbital or temporo-malar branch arises in the spheno-maxillary fossa, 
 enters the orbit by the spheno-maxillary fissure, and divides at the back of that 
 cavity into two branches, temporal and malar. 
 
 The Temporal Branch {ramus zygomaticoiemporalis) runs in a groove along the 
 outer wall of the orbit (in the malar bone), receives a branch of communication 
 from the lachrymal, and, passing through a foramen in the malar bone, enters the 
 temporal fossa. It ascends between the bone and the substance of the Temporal 
 muscle, pierces this muscle and the temporal fascia about an inch above the 
 zygoma, and is distributed to the integument covering the temple and side of 
 the forehead, communicating with the facial and the auriculo-temporal branch of 
 the inferior maxillary nerve. As it pierces the temporal fascia it gives off a 
 slender twig, which runs between the two layers of the fascia to the outer angle 
 of the orbit. 
 
 The Malar Branch (ramus zygomatico facialis) passes along the external inferior 
 angle of the orbit, emerges upon the face through a foramen in the malar bone, 
 and, perforating the Orbicularis palpebrarum muscle, supplies the skin on the 
 prominence of the cheek, where it is named the subcutaneous malae. It joins with 
 the facial and the palpebral branches of the superior maxillary. 
 
 The Spheno-palatine Branches (nvi. sphenopalatini) (Figs. 670 and 671). — The 
 spheno-palatine branches, two in number, descend to the spheno-palatine 
 ganglion, of which ganglion they are the sensory or short roots. 
 
 The Posterior Superior Dental Branches (rami alveolares swperixires posteriores) 
 (Figs. 670 and 671). — The posterior superior dental branches arise from the trunk 
 of the nerve just as it is about to enter the infraorbital canal ; they are generally 
 two in number, but sometimes arise by a single trunk, and immediately divide 
 and pass downward on the tuberosity of the superior maxillary bone. They give 
 off several twigs to the gums and neighboring parts of the mucous membrane of 
 the cheek, superior gingival branches (rami gingivales superiores). They then 
 enter the posterior dental canals on the zygomatic surface of the superior maxil- 
 lary bone, and, passing from behind forward in the substance of the bone. 
 
THE FIFTH, TRIGEMINAL OB TRIFACIAL NERVE 1033 
 
 communicate with the middle dental nerve by a plexus formation, and give off 
 branches to the lining membrane of the antrum and three twigs to each of the 
 molar teeth. These twigs enter the foramina at the apices of the fangs and 
 supply the pulp. 
 
 The Middle Superior Dental Branch {ramus alveolaris superior medius) (Fig. 
 670). — The middle superior dental branch is given off from the superior maxil- 
 lary nerve in the back part of the infraorbital canal, and runs downward and 
 forward in a special canal in the outer wall of the antrum to supply the two 
 bicuspid teeth. It communicates with the posterior and anterior dental branches 
 by a plexus formation. At its point of communication with the posterior 
 branch, above the root of the second bicuspid tooth, is a slight thickening which 
 has received the name of the ganglion of Valentin ; and at its point of commu- 
 nication with the anterior branch is a second enlargement, which is called the 
 ganglion of Bochdalek. Neither of these is probably a true ganglion. 
 
 Sensory root 
 Motor root. 
 
 Auriculo- temporal J 
 nerve. 
 
 Fig. 671. — Distribution of the second and third divisions of the fifth nerve and submaxillary ganglion. 
 
 The Anterior Superior Dental Branch (ramus alveolaris superior anteriores) (Fig. 
 670). — The anterior superior dental branch, of large size, is given oft' from the 
 superior maxillary nerve just before its exit from the infraorbital foramen; it 
 enters a special canal in the anterior wall of the antrum, and divides into a series 
 of branches which supply the incisor and canine teeth. It communicates with 
 the middle dental nerve by a plexus, and gives off a nasal branch, which passes 
 through a minute canal into the nasal fossa, and supplies the mucous membrane 
 of the forepart of the inferior meatus and the floor of the cavity, communi- 
 cating with the nasal branches from Meckel's ganglion. 
 
 The superior dental plexus (plexus dentalis superior) is formed by twigs of the 
 three superior dental nerves. From the plexus come the nerves which supply the 
 
1034 THE NERVOUS SYSTEM 
 
 teeth of the upper jaw {rami dentales superiores) and the gums (rami gingivales 
 super lores). 
 
 The branches upon the face are known as the rami n. infraorbitalis (Fig. 671). 
 There are three sets of them. 
 
 The Palpebral Branches (rami palpehrales inferiores). — The palpebral branches 
 pass upward beneath the Orbicularis palpebrarum muscle. They supply the 
 integument and conjunctiva of the lower eyelid, with sensation, joining at 
 the outer angle of the orbit with the facial nerve and the malar branch of the 
 orbital. 
 
 The Nasal Branches (rami nasales interni). — The nasal branches pass inward; 
 they supply the integument of the side of the nose and join with the nasal branch 
 of the ophthalmic. 
 
 The Labial Branches (rami labiales superiores). — The labial branches, the 
 largest and most numerous, descend beneath the Levator labii superioris muscle, 
 and are distributed to the integument of the upper lip, the mucous membrane 
 of the mouth, and the labial glands. 
 
 All these branches are joined, immediately beneath the orbit, by filaments from 
 the facial nerve, forming an intricate plexus, the infraorbital plexus. 
 
 The Spheno-palatine or Meckel's Ganglion (ganglion sphenopalatinum) (Figs. 
 670 and 672). — The spheno-palatine ganglion, the largest of the cranial ganglia, 
 is deeply placed in the spheno-maxillary fossa, close to the spheno-palatine fora- 
 men. It is triangular or heart-shaped, of a reddish-gray color, and is situated just 
 below the superior maxillary nerve as it crosses the fossa. 
 
 Branches of Commiinication. — Like the other ganglia of the fifth nerve, it pos- 
 sesses a motor, a sensory, and a sympathetic root. Its sensory root is derived 
 from the superior maxillary nerve through its two spheno-palatine branches 
 (p. 1032). These branches of the nerve are given off in the spheno-maxillary fossa 
 and descend to the ganglion. Their fibres, for the most part, pass in front of the 
 ganglion, as they proceed to their destination, in the palate and nasal fossa, and 
 are not incorporated in the ganglionic mass ; some few of the fibres, however, enter 
 the ganglion, constituting its sensory root. Its motor root is derived from the facial 
 nerve through the large superficial petrosal nerve, and its sympathetic root from 
 the carotid plexus, through the large deep petrosal nerve. These two nerves join 
 together before their entrance into the ganglion to form a single nerve, the Vidian. 
 
 The Large or Great Superficial Petrosal Branch (n. petrosus superficialis major) 
 (Fig. 676) is given off from the geniculate ganglion of the facial nerve in the 
 aquaeductus Fallopii ; it passes through the hiatus Fallopii ; enters the cranial 
 cavity, and runs forward, being contained in a groove on the anterior surface 
 of the petrous portion of the temporal bone and lying beneath the dura mater. 
 It then enters the cartilaginous substance which fills in the foramen lacerum 
 medium basis cranii, and, joining with the large deep petrosal branch, forms the 
 Vidian nerve. 
 
 The Large or Great Deep Petrosal Branch (n. petrosus profundus) (Fig. 677) is 
 given off from the carotid plexus of the sympathetic upon the internal carotid 
 artery, and runs through the carotid canal on the outer side of the internal carotid 
 artery. It then enters the cartilaginous substance which fills in the foramen 
 lacerum medium basis cranii, and joins with the large superficial petrosal nerve 
 to form the Vidian. 
 
 The Vidian Nerve (n. canalis pterygoidei) (Figs. 670 and 672), formed in the 
 cartilaginous substance which fills in the middle lacerated foramen by the junc- 
 tion of the two preceding nerves, passes forward, through the Vidian canal, with 
 the artery of the same name, and is joined by a small ascending nervous branch, 
 the sphenoidal branch, from the otic ganglion. Finally, it enters the spheno-maxil- 
 lary fossa, and joins the posterior angle of Meckel's ganglion. 
 
 J 
 
THE FIFTH, TRIGEMINAL OB TRIFACIAL NERVE 1035 
 
 Branches of Distribution of the Spheno -palatine Ganglion. — Its branches of distri- 
 bution are divisible into four groups: ascending, which pass to the orbit; descend- 
 ing, to the palate; internal, to the nose; and posterior branches, to the pharynx and 
 nasal fossae. 
 
 The Ascending Branches (rami orbitales) are two or three delicate filaments, which 
 enter the orbit by the spheno-maxillary fissure, and supply the periosteum. Accord- 
 ing to Luschka, some filaments pass through foramina in the suture between the 
 OS planum of the ethmoid and frontal bones to supply the mucous membrane of 
 the posterior ethmoidal and sphenoidal sinuses. 
 
 The Descending or Palatine Branches (nn. palatini) (Figs. 670 and 672) are dis- 
 tributed to the roof of the mouth, the soft palate, tonsil, and lining membrane of 
 the nose. They are almosta direct continuation of the spheno-palatine branches 
 of the superior maxillary nerve, and are three in number — anterior, middle, and 
 posterior. 
 
 Termination o, 
 
 naso-palatine 
 
 nerve 
 
 Fig. 672. — The spheno-palatine or Meckel's ganglion and its branches. 
 
 The anterior or large palatine nerve (n. palatinus anterior) descends through 
 the large posterior palatine canal, emerges upon the hard palate at the posterior 
 palatine foramen, and passes forward through a groove in the hard palate nearly 
 as far as the incisor teeth. It supplies the gums, the mucous membrane and glands 
 of the hard palate, and communicates in front with the termination of the naso- 
 palatine nerve (p. 1036) . While in the posterior palatine canal it gives off inferior 
 nasal branches (rami nasales posteriores injeriores), which enter the nose through 
 openings in the palate bone, and ramify over the inferior turbinated bone, the 
 middle and the inferior meatus ; and at its exit from the canal a palatine branch 
 is distributed to both surfaces of the soft palate. 
 
 The middle or external palatine nerve (n. palatinus Tnedius) descends through 
 one of the accessory palatine canals, distributing branches to the uvula, tonsil, 
 and soft palate. It is occasionally wanting. 
 
 The posterior or small palatine nerve (n. palatinus posterior) descends with a 
 minute artery through the small posterior palatine canal, emerging by a separate 
 
1036 'I'HE NERVOUS SYSTEM 
 
 opening behind the posterior palatine foramen. It supphes the Levator palati 
 and Azygos uvulae muscles/ the soft palate, tonsil, and uvula. T.'he middle and 
 posterior palatine join with the tonsillar branches of the glosso-pharyngeal to form 
 the plexus around the tonsil, the circulus tonsillaris. 
 
 The Internal Branches are distributed to the septum and outer wall of the nasal 
 fossae. They are the posterior superior nasal and the naso-palatine. 
 
 The posterior superior nasal branches {rami nasales posteriores superiores), three 
 in number, enter the back part of the nasal fossa by the spheno-palatine foramen. 
 They supply the mucous membrane covering the superior and middle spongy bones, 
 and that lining the posterior ethmoidal cells, a few being prolonged to the upper 
 and back part of the septum. 
 
 The naso-palatine nerve (n. nasopalatinus) has been called the nerve of Scarpa 
 and also the nerve of Cotunnius. It enters the nasal fossa through the spheno- 
 palatine foramen, and passes inward across the roof of the nose, below the orifice 
 of the sphenoidal sinus, to reach the septum ; it then runs obliquely downward and 
 forward along the lower part of the septum, to the anterior palatine foramen, 
 lying between the periosteum and mucous membrane. It descends to the roof of 
 the mouth through the anterior palatine canal (Fig. 672). The two nerves are here 
 contained in separate and distinct canals, situated in the intermaxillary suture, and 
 termed the foramina of Scarpa, the left nerve being usually anterior to the right 
 one. In the mouth they become united, supply the mucous membrane behind 
 the incisor teeth, and join with the anterior palatine nerve. The naso-palatine 
 nerve furnishes a few small filaments to the mucous membrane of the septum. 
 
 The Posterior Branches are the pharyngeal or pterygo -palatine and the upper 
 posterior nasal branches. 
 
 The pharyngeal or pterygo-palatine nerve (Figs. 670 and 672) is a small branch 
 arising from the back part of the spheno-palatine ganglion, being generally blended 
 with the Vidian nerve. It passes through the pterygo-palatine canal with the 
 pterygo-palatine artery, and is distributed to the mucous membrane of the upper 
 part of^ the pharynx, behind the Eustachian tube. 
 
 The upper posterior nasal branches are a few twigs given off from the posterior 
 part of the spheno-palatine ganglion, which run backward in the sheath of the 
 Vidian nerve to the mucous membrane at the back part of the roof, septum, and 
 superior meatus of the nose and that covering the end of the Eustachian tube. 
 
 The Mandibular or Inferior Maxillary Nerve (n. mandibular is) (Figs. 667, 
 669, 670, and 671). — The inferior maxillary or third division of the fifth nerve dis- 
 tributes branches to the teeth and gums of the lower jaw, the integument of the 
 temple and external ear, the lower part of the face and lower lip, and the muscles 
 of mastication ; it also supplies the tongue with a large branch. It is the largest of 
 the three divisions of the fifth, and is made up of two roots : a large or sensory root, 
 proceeding from the inferior angle of the Gasserian ganglion ; and a small or motor 
 root, which passes beneath the ganglion and unites with the sensory root just after 
 its exit from the skull through the foramen ovale (Figs. 667, 668, 670, and 671). 
 Immediately beneath the base of the skull this nerve divides into two trunks, 
 anterior and posterior. Previous to its division the primary trunk gives off from 
 its inner side a recurrent branch and the nerve to the Internal pterygoid muscle. 
 
 The Recurrent or Meningeal Branch (w. spinosus). — The recurrent or meningeal 
 branch is given off directly after the exit of the mandibular nerve from the foramen 
 ovale. It passes backward into the skull through the foramen spinosum with the 
 middle meningeal artery. It divides into two branches, anterior and posterior, which 
 accompany the main divisions of the artery and supply the dura mater. The pos- 
 
 ] It is probable that this is not the true motor supply to these muscles, but that they are supplied by the 
 spinal accessory through the pharyngeal plexus. — Ed. of 15th English edition. 
 
 I 
 
THE FIFTH, TRIGEMINAL OR TRIFACIAL NERVE 1037 
 
 terior branch also supplies the mucous lining of the mastoid cells. The anterior 
 branch communicates with the meningeal branch of the superior maxillary nerve. 
 
 The Internal Pterygoid Nerve (w. pterygoideus internus) (Fig. 670) . — The internal 
 pterygoid nerve, given off from the inferior maxillary previous to its division, is 
 intimately connected at its origin with the otic ganglion. It is a long and slender 
 branch, which passes inward to enter the deep surface of the Internal pterygoid 
 muscle. 
 
 The anterior and smaller division of the inferior maxillary nerve, which receives 
 nearly the whole of the motor root of the fifth nerve, divides into branches which 
 supply the muscles of mastication. They are the masseteric, deep temporal, buccal, 
 and external pterygoid branches (Figs. 670 and 671). 
 
 The Masseteric Branch [n. massetericus) passes outward, above the External 
 pterygoid muscle, in front of the temporo-mandibular articulation and behind the 
 tendon of the temporal muscle; it crosses the sigmoid notch with the masseteric 
 artery, to the deep surface of the Masseter muscle, in which it ramifies nearly as 
 far as its anterior border. It occasionally gives a branch to the Temporal muscle, 
 and a filament to the articulation of the jaw. 
 
 The Deep Temporal Branches {nn. temporales profundi), two in number, anterior 
 and posterior, supply the deep surface of the Temporal muscle. The posterior 
 branch (n. temporalis profundus posterior), of small size, is placed at the back of 
 the temporal fossa. It is sometimes joined with the masseteric branch. The 
 anterior branch (n. temporalis profundus anterior) is frequently given off from the 
 buccal nerve; it is reflected upward, at the pterygoid ridge of the sphenoid, to the 
 front of the temporal fossa. Sometimes there are three deep temporal branches, 
 and if this maintains the third branch, the middle deep temporal, passes outward 
 above the External pterygoid muscle, and runs upward on the bone to enter the 
 deep surface of the Temporal muscle. 
 
 The Buccal or Buccinator Branch (n. huccinatorius) passes forward between the 
 two heafls of the External pterygoid, and downward beneath the inner surface of 
 the coronoid processes of the lower jaw, or through the fibres of the Temporal 
 muscle, to reach the surface of the Buccinator muscle, upon which it divides into 
 a superior and an inferior branch. It gives a branch to the External pterygoid 
 during its passage through that muscle, and a few ascending filaments to the 
 Temporal muscle, one of which occasionally joins with the anterior branch of the 
 deep temporal nerve. The superior or upper branch supplies the integument and 
 upper part of the Buccinator muscle, joining with the facial nerve around the 
 facial vein. The inferior or lower branch passes forward to the angle of the mouth ; 
 it supplies the integument and Buccinator muscle, as well as the mucous membrane 
 lining the inner surface of that muscle, and joins the facial nerve.^ 
 
 The External Pterygoid Nerve (n. pterygoideus externus) is most frequently 
 derived from the buccal, but it may be given off separately from the anterior 
 trunk of the mandibular nerve. It enters the muscle on its inner surface. 
 
 The posterior and larger division of the inferior maxillary nerve is for the most part 
 sensory, but receives a few filaments from the motor root. It divides into three 
 branches: auriculo -temporal, lingual (gustatory), and inferior dental (Figs. 670, 671). 
 
 The Auriculo-temporal Nerve {n. auriculotemporalis) (Fig. 673) generally arises 
 by two roots, between which the middle meningeal artery passes. It runs back- 
 ward beneath the External pterygoid muscle to the inner side of the neck of the 
 lower jaw. It then turns upward with the temporal artery, between the external 
 ear and the condyle of the jaw, under cover of the parotid gland, and, escaping 
 from beneath this structure, ascends over the zygoma and divides into two tem- 
 poral branches. 
 
 'There seems to be no reason to doubt that the branch supplying the Buccinator muscle is entirely a nerve of 
 ordinary sensation, and that the true motor supply of this muscle is from the facial. — Ed. of 15th English edition. 
 
1038 THE NERVOUS SYSTEM 
 
 The branches of communication are with the facial and with the otic ganglion. 
 The branches of communication with the facial {rami anastomotici cum n. faciali), 
 usually two in number, pass forward from behind the neck of the condyle of the 
 jaw, to join this nerve at the posterior border of the Masseter muscle. They 
 form one of the principal branches of communication between the facial and the 
 fifth nerve. The filaments of communication with the otic ganglion are derived 
 from the commencement of the auriculo-temporal nerve. 
 
 The branches of distribution are — 
 
 Anterior auricular. Articular. 
 
 Branches to the meatus auditorius. Parotid. 
 
 Superficial temporal. 
 
 The anterior auricular branches (nn. auriculares anteriores) are usually two in 
 number. They supply the front of the upper'part of the pinna, being distributed 
 principally to the skin covering the front of the helix and tragus. 
 
 Branch to the external auditory meatus (w. meatus auditorii externi) divides into 
 two. The two nerves enter the canal between the bony and cartilaginous portion 
 of the meatus. They supply the skin lining the meatus; the upper one sending 
 a filament to the membrana tympani {ramus memhranae tijvipani). 
 
 A branch to the temporo-mandibular articulation, the articular branch, is usually 
 derived from the auriculo-temporal nerve. 
 
 The parotid branches {rami parotidei) supply the parotid gland. 
 
 The superficial temporal branches {rami temporales super fi dales) accompany the 
 temporal artery to the vertex of the skull, and supplies the integument of the tem- 
 poral region, communicating with the facial nerve, and with the temporal branch 
 of the temporo-malar, from the superior maxillary. 
 
 The Lingual Nerve or Gustatory Nerve (n. lingualis) (Figs. 670 and 671). — The 
 lingual or gustatory nerve supplies the papillae and mucous membrane of the 
 anterior two-thirds of the tongue. It is deeply placed throughout the whole of its 
 course. It lies at first beneath the External pterygoid muscle, together with the 
 inferior dental nerve, being placed to the inner side of this nerve, and is occasion- 
 ally joined to it by a branch which may cross the internal maxillary artery. The 
 chorda tympani nerve also joins it at an acute angle in this situation. The nerve 
 then passes between the Internal pterygoid muscle and the inner side of the 
 ramus of the jaw, and crosses obliquely to the side of the tongue over the Superior 
 constrictor of the pharynx and the Stylo-glossus muscles, and then between the 
 Hyo-glossus muscle and the deep part of the submaxillary gland; the nerve finally 
 runs across Wharton's duct, and along the side of the tongue to its apex, lying 
 immediately beneath the mucous membrane. 
 
 The branches of communication are with the facial through the chorda tympani, 
 with the inferior dental and hypoglossal nerves, and the submaxillary ganglion. The 
 chorda tympani branch of the facial joins the lingual nerve under the external 
 pterygoid muscle and is distributed with the lingual to the tongue. The hypo- 
 glossal nerve and the lingual nerve lie near together, over the Hyo-glossus muscle, 
 and the two nerves are joined by loops {rami anastomotici cum n. hypoglosso). 
 The branches to the submaxillary ganglion are two or three in number; those 
 connected with the hypoglossal nerve form a plexus at the anterior margin of the 
 Hyo-glossus muscle. 
 
 The branches of distribution supply the mucous membrane of the mouth, the 
 gums, the sublingual gland, the filiform and fungiform papillae and mucous mem- 
 brane of the tongue; the terminal filaments communicate, at the tip of the tongue, 
 with the hypoglossal nerve. The lingual fibres are fibres of common sensation. 
 The chorda tympani fibres which join the lingual nerve are probably taste- 
 fibres. 
 
THE FIFTH, TRIGEMINAL OB TRIFACIAL NERVE 1039 
 
 The Inferior Dental Nerve (n. alveolaris inferior) (Figs. 670 and 671). — The 
 inferior dental is the largest of the branches of the inferior maxillary nerve. It 
 passes downward with the inferior dental artery, at first beneath the External 
 pterygoid muscle, and then between the internal lateral ligament and the ramus 
 of the jaw to the dental foramen. It then passes forward in the dental canal of the 
 inferior maxillary bone, lying beneath the teeth, as far as the mental foramen, 
 where it divides into two terminal branches, incisor and mental. 
 
 The Branches of the inferior dental are: the mylo-hyoid, dental, incisor, and 
 mental. 
 
 The Mylo-hyoid (n. mylohyoidetis) is derived from the inferior dental just as that 
 nerve is about to enter the dental foramen. It descends in a groove on the inner 
 surface of the ramus of the jaw, in which it is retained by a process of fibrous mem- 
 brane. It reaches the under surface of the Mylo-hyoid muscle, and supplies it and 
 the anterior belly of the Digastric. 
 
 The Dental Branches supply the molar and bicuspid teeth. They correspond 
 in number to tiie fangs of those teeth : each nerve entering the orifice at the point 
 of the fang and supplying the pulp of the tooth. 
 
 The Incisor Branch is continued onward within the bene to the middle line, and 
 supplies the canine and incisor teeth. 
 
 The dental branches and the incisor branch form a plexus (plexus dentalis infe- 
 rior), and from this plexus come the branches to the teeth (rami dentales inferiores) 
 and to the gums (rami gingivales inferiores). 
 
 The Mental Branch (n. mentalis) emerges from the bone at the mental foramen, 
 and divides beneath the Depressor anguli oris muscle into two or three branches; 
 one descends to supply the skin of the chin, and another (sometimes two) ascends 
 to supply the skin and mucous membrane of the lower lip. These branches com- 
 municate freely with the facial nerve. 
 
 Two small ganglia are connected with the inferior maxillary nerve — the otic 
 with the trunk of the nerve, and the submaxillary with its lingual branch. 
 
 Otic or Arnold's Ganglion (ganglion oticum) (Figs. 670 and 673). — The otic or 
 Arnold's ganglion is a small, oval-shaped, flattened ganglion of a reddish-gray 
 color, situated immediately below the foramen ovale, on the inner surface of the 
 inferior maxillary nerve, and round the origin of the internal pterygoid nerve. It 
 is in relation, externally, with the trunk of the inferior maxillary nerve, at the 
 point where the motor root joins the sensory portion; internally, with the car- 
 tilaginous part of the Eustachian tube, and the origin of the Tensor palati muscle; 
 behind, it lies in the middle meningeal artery. 
 
 Branches of Communication. — This ganglion is connected with the internal 
 pterygoid branch of the inferior maxillary nerve by two or three short delicate 
 filaments. From this nerve the ganglion may obtain a motor root, and possibly 
 also a sensory root, as these filaments from the nerve to the Internal pterygoid 
 perhaps contain sensory fibres. The otic ganglion communicates with the glosso- 
 pharyngeal and facial nerves through the small superficial petrosal nerve (Figs. 673 
 and 676) continued from the tympanic plexus, and through this communication 
 it probably receives its sensory root from the glosso -pharyngeal and its motor root 
 from the facial ; its communication with the sympathetic is effected by a filament 
 from the plexus surrounding the middle meningeal artery. The ganglion also 
 communicates with the auriculo-temporal nerve (ramus' anastomoticus cum n. 
 auricidotemporali). This communicating filament is probably a branch from the 
 glosso-pharyngeal which passes to the ganglion, and through it and the auriculo- 
 temporal nerve to the parotid gland. A slender filament, the sphenoidal, ascends 
 from it to the Vidian nerve. 
 
 Branches of Distribution. — Its branches of distribution are a filament to the 
 Tensor tympani (n. tensoris tympani) and one to the Tensor palati (n. tensoris veil 
 
1040 
 
 THE NEBVOUS SYSTEM 
 
 palatini). The former passes backward on the outer side of the Eustachian tube; 
 the latter arises from the ganghon, near the origin of the internal pterygoid nerve, 
 and passes forward. The fibres of these nerves are, however, mainly derived 
 from the nerve to the Internal pterygoid muscle. It also gives off a small com- 
 municating branch to the chorda tympani {ramus anastomoticus cum n. chorda 
 tymyani). 
 
 The Submaxillaxy Ganglion {ganglion submaxillare) (Figs. 670 and 671). — The 
 submaxillary ganglion is of small size, fusiform in shape, and situated above the 
 deep portion of the submaxillary gland, near the posterior border of the Mylo-hyoid 
 muscle, being connected by filaments with the lower border of the lingual or 
 gustatory nerve. 
 
 Branches of Communication. — This ganglion is connected with the lingual nerve 
 by a few filaments {rami communicantes cum n. linguxili), which join it separately 
 at its fore and back part. It also receives a branch from the chorda tympani, by 
 which it communicates with the facial, and communicates with the sympathetic 
 by filaments from the sympathetic plexus around the facial artery. 
 
 Fig. 673. — The otic ganglion and its branches. 
 
 Branches of Distribution. — These are five or six in number; they arise from the 
 lower part of the ganglion, and supply the mucous membrane of the mouth and 
 Wharton's duct, some being lost in the submaxillary gland {rami submaxillares). 
 The branch of communication from the lingual nerve to the forepart of the gan- 
 glion is by some regarded as a branch of distribution, by which filaments of the 
 chorda tympani pass from the ganglion to the lingual nerve, and by it are con- 
 veyed to the sublingual gland and the tongue. 
 
 Summary of the Distribution and Connections of the Fifth Nerve. — It is the chief 
 sensory nerve of the face, the anterior half of the scalp, the mouth, nasal cavity, 
 lips, teeth, anterior two-thirds of the tongue, orbit, and eyeball. The clearly 
 defined cutaneous distributions of the branches are shown in Fig. 674. The 
 motor portion of the nerve supplies the muscles of mast'cation, the mylo-hyoid, 
 and the anterior belly of the digastric. By way of branches from the otic 
 ganglion it supplies the Tensor tympani and Tensor palati muscles, and by 
 way of branches from the spheno-palatine ganglion perhaps supplies the Levator 
 palati and Azygos uvulae muscles, although it is more probable that these muscles 
 
THE FIFTH, TRIGEMINAL OB TRIFACIAL NERVE 1041 
 
 receive their motor influence by the spinal accessory through the pharyngeal 
 plexus. The ganglia associated with the nerve create communications with the 
 sympathetic, the motor oculi, the facial, and the glosso-pharyngeal, and through 
 these ganglia, as Prof, Cunningham says, " important organs, areas, and muscles " 
 are innervated. The trigeminal communicates many times with the facial, and 
 thus gives sensory fibres to the " muscles of expression supplied by the facial 
 nerve."^ 
 
 LACHRYMAL N. 
 
 SUPRATROCHLEAR N 
 SUPRAORBITAL N. 
 
 INFRATROCHLEAR N 
 
 NASAL NERVE 
 
 BUCCAL NERVE 
 
 MENTAL NERVE- 
 
 TEMPORAL BR. 
 OF TEMPORO-MALAR 
 
 MALAR BR. OF 
 TEMPORO-MALAR 
 
 AURICULO-TEMPORAL 
 NERVE 
 
 Fig. 674. — Sensory areas of the head, showing the general distribution of the three divisions of the fifth 
 nerve. Gerrish's Anatomy. (Modified from Testut.) 
 
 Surface Marking. — It will be seen from the above description that the three terminal branches 
 of the three divisions of the fifth nerve emerge from foramina in the bones of the skull and pass 
 on to the face: the terminal branch of the first division emerging through the supraorbital 
 foramen ; that of the second through the infraorbital foramen ; and the third through the mental 
 foramen. The supraorbital foramen is situated at the junction of the internal and middle 
 third of the supraorbital arch. If a straight line is drawn from this point to the lower border 
 of the inferior maxillary bone, so that it passes between the two bicuspid teeth of the lower jaw, 
 it will pass over the infraorbital and mental foramina, the former being situated about one 
 centimetre (two-fifths of an inch) below the margin of the orbit, and the latter varying in posi- 
 tion according to the age of the individual. In the adult it is midway between the upper and 
 lower borders of the inferior maxillary bone; in the child it is nearer the lower border; and in the 
 edentulous jaw of old age it is close to the upper margin. 
 
 Surgical Anatomy. — In fracture of the hose of the skulL the fifth nerve or one of its branches 
 may be injured. It seems certain that occasionally, though seldom, the fifth nerve may be 
 actually divided by such an injury. The fifth nerve may be affected in its entirety, or its sensory 
 or motor root may be affected, or one of its primary main divisions. In injury to the sensory root 
 there is anaesthesia of the half of the face on the side of the lesion, with the exception of the skin 
 over the parotid gland; insensibility of the conjunctiva, followed, if the eye is not temporarily 
 protected with a watch-glass, by destructive inflammation of the cornea, partly, it is held, from 
 loss of trophic influence, and partly, it is certain, from the irritation produced by the presence 
 of foreign bodies on it, which are not perceived by the patient, and therefore not expelled by 
 the act of winking; dryness of the nose, loss to a considerable extent of the sense of taste, and 
 diminished secretion of the lachrymal and salivary glands. In injury to the motor root there is 
 impaired action of the lower jaw from paralysis of the muscles of mastication on the affected side. 
 
 The fifth nerve is often the seat of neuralgia, and each of the three divisions has been divided 
 or a portion of the nerve excised for this affection. The supraorbital nerve may be exposed 
 
 1 Cunningham's Text-book of Anatomy. 
 66 
 
1042 THE NERVOUS SYSTEM 
 
 by making an incision an inch and a half in length along the supraorbital margin below the 
 eyebrow, which is to be drawn upward, the centre of the incision corresponding to the supra- 
 orbital notch. The skin and Orbicularis palpebrarum having been divided, the nerve can be 
 easily found emerging from the notch and lying in some loose cellular tissue. It should be drawn 
 up by a blunt hook and divided, or, what is better, a portion of it should be removed. The 
 infraorbital nerve has been divided at its exit by an incision on the cheek; or the floor of the 
 orbit has been exposed, the infraorbital canal opened up, and the anterior part of the nerve 
 resected; or the whole nerve, together with Meckel's ganglion as far back as the foramen rotun- 
 dum, has been removed. This latter operation, though undoubtedly a severe proceeding, appears 
 to have been followed by better results than has nerve resection. The operation is performed 
 as follows: The superior maxillary bone is first exposed by a T-shaped incision, one limb of 
 the incision passing along the lower margin of the orbit, the other from the centre of the first 
 cut vertically down the cheek toward the angle of the mouth. The nerve is then found, is divided, 
 and a piece of silk is tied to it as a guide. A small trephine (one-half inch) is then applied 
 to the bone below, but including the infraorbital foramen, and the antrum opened. The 
 trephine is now applied to the posterior wall of the antrum, and the spheno-maxillary fossa 
 exposed. The infraorbital canal is now opened up from below by fine cutting-pliers or a 
 chisel, and the nerve drawn down into the trephine hole, it being held on the stretch by 
 means of the piece of silk; it is severed with fine curved scissors as near the foramen rotundura 
 as possible, any branches coming off from the ganglion being also divided.' The mental 
 branch of the inferior dental nerve may be divided at its exit from the foramen through an 
 incision made through the mucous membrane where it is reflected from the alveolar process on 
 to the lower lip ; or a portion of the trunk of the inferior dental nerve may be resected through 
 an incision on the cheek through the Masseter muscle, exposing the outer surface of the ramus of 
 the jaw. A trephine is then applied over the position of the inferior dental foramen and the 
 outer table removed, so as to expose the inferior dental canal. The nerve is dissected out of 
 the portion of the canal exposed, and, having been divided after its exit from the mental foramen, 
 it is by traction on the end exposed in the trephine-hole, drawn out entire, and cut off as high up 
 as possible.^ The inferior dental nerve has also been divided through an incision within the mouth, 
 the bony point guarding the inferior dental foramen forming the guide to the nerve. The buccal 
 nerve may be divided by an incision through the mucous membrane of the mouth and the Buc- 
 cinator muscle just in front of the anterior border of the ramus of the lower jaw (Stimson). 
 
 In inveterate neuralgia of one or two of the branches of the fifth nerve a peripheral opera- 
 tion may cure the case, but seldom does. It often gives relief, perhaps for months. In neuralgia 
 of the second division or third division, or of the second division and third division. Abbe, of 
 New York, opens the skull and divides the nerve or nerves by an intracranial operation, 
 removes a piece of nerve so as the foramen of exit is empty, and covers the foramen with rubber 
 tissue, to hinder regrowth of the nerve. Other operators, after removing a piece from each 
 nerve, have plugged the foramina of the exit with dentists' cement or silver-foil. 
 
 Rose's method of neurectomy is very valuable for neuralgia of the second division. It is a 
 modification of the Braun-Lossen method. The infraorbital nerve is exposed, a ligature is 
 tied about it, the roof of the infraorbital canal is chiselled open, and the nerve is freed as far 
 back as possible. An incision is made from below the external angular process outward along 
 the zygoma to in front of the lobule of the ear, downward to just above the angle of the jaw, 
 and forward for two inches. The flap is raised and the zygoma is exposed. The root of the 
 zygoma is drilled at two points, and the zygomatic process of the temporal bone is drilled at two 
 points. The bone is sawed in two places between the drill-holes. The freed arch is lifted down 
 and back, the tendon of the temporal muscle is drawn backward, and the pterygo-maxillary 
 fossa is thus exposed. The internal maxillary artery is divided between two ligatures. The 
 External pterygoid muscle is separated from the greater wing of the sphenoid and from the root 
 of the external pterygoid process. The superior maxillary nerve is grasped and twisted off as 
 near the ganglion as possible. The entire nerve is then drawn back from the infraorbital foramen 
 and removed. The wound is then closed. If the third division is also haunted by neuralgia, 
 it too should be removed a ew weeks after the performance of Rose's operation. 
 
 If a peripheral operation fails, or if all the branches of the fifth are involved, the Gasserian 
 ganglion must be removed or the sensory root of the fifth must be divided, as suggested by 
 Frazier and Spiller. 
 
 Removal of the Gasserian ganglion was suggested by J. Ewing Mears in 1884, and was first 
 carried out by Rose in 1890. 
 
 The method chiefly in vogue was devised by Hartley, and was first performed by him in 1891. 
 An osteoplastic flap is made in front of the ear, the dura is exposed and lifted. Following Krause's 
 advice, the third division is exposed and clamped. The second division is exposed and damped. 
 The nerves are loosened from their beds and then are rolled about the clamps. This twisting 
 
 ^ Carnochan, American Journal of the Medical Sciences, 1858, p. 136. 
 
 ^ Mears, Transactions of the American Surgical Association, vol. ii. p. 469, 
 
THE SIXTH OB ABDUCENT NERVE IO43 
 
 pulls out the ganglion intact along with the motor root, and also the sensory root from the 
 pons. 
 
 A difficulty in the Hartley operation is the danger of division of the meningeal artery. If 
 this happens, the surgeon may be able to arrest bleeding and proceed with the operation. If 
 the vessel is torn off at the foramen spinosum, it will be necessary to pack the wound and post- 
 pone any further operative manipulation for forty-eight hours. 
 
 Dr. Harvey Gushing has modified Hartley's operation by trephining the wall of the temporal 
 fossa very low down. He opens the skull below the arch of the meningeal vessels, and thus avoids 
 the meningeal at the foramen spinosum, and also the sulcus arteriosus of the parietal bone. 
 
 After the removal of the ganglion. Professor Keen, in order to prevent undue inflammation of 
 the eye, sews the eyelids of the affected side together, leaving a space open at each angle, and 
 covers the eye with a watch-crystal. Boracic acid solution is flushed into the opening at the external 
 angle at frequent intervals. The stitches are removed from the lid in from eight to ten days. 
 
 The lingual (gustatory) nerve is occasionally divided with the view of relieving the pain in 
 cancerous disease of the tongue. This may be done in that part of its course where it lies below 
 and behind the last molar tooth. If a line is drawn from the middle of the crown of the last 
 molar tooth to the angle of the jaw, it will cross the nerve, which lies about half an inch behind 
 the tooth, parallel to the bulging alveolar ridge on the inner side of the body of the bone. If 
 the knife is entered three-quarters of an inch behind and below the last mokr tooth and carried 
 down to the bone, the nerve will be divided. Hilton divided it opposite the second molar tooth, 
 where it is covered only by the mucous membrane, and Lucas pulls the tongue forward and over 
 to the opposite side, when the nerve can be seen standing out as a firm cord under the mucous 
 membrane by the side of the tongue and can be easily seized with a sharp hook and divided or 
 a portion excised. This is a simple enough operation on the cadaver, but when the disease is 
 extensive and has extended to the floor of the mouth, as is generally the case when division of 
 the nerve is thought of, the operation is not practicable. 
 
 THE SIXTH OR ABDUCENT NERVE (N. ABDUCENS) (Fig. 669). 
 
 The sixth or abducent nerve suppHes the External rectus muscle. Its super- 
 ficial origin is by several filaments from the constricted part of the pyramid, close 
 to the pons, or from the lower border of the pons itself, in the groove between this 
 body and the medulla. Its deep origin is from the upper part of the floor of the 
 fourth ventricle, close to the median line, beneath the eminentia teres (Fig. 613.) 
 
 From the nucleus of the sixth nerve fibres pass through the posterior longitudinal 
 bundle to the oculo-motor nucleus of the opposite side and into the third nerve, 
 along which they are carried to the Internal rectus muscle. The External rectus 
 of one eye and the Internal rectus of the other may therefore be said to receive 
 their nerves from the same nucleus — a factor of great importance in connection 
 with the conjugate movements of the eyeball, and one that may explain certain 
 paralytic phenomena of the Recti muscles, which are often associated with lesions 
 in the pons. 
 
 The nerve pierces the dura mater on the basilar surface of the sphenoid bone, 
 runs through a notch immediately below the posterior clinoid process, and enters 
 the cavernous sinus. It passes forward through the sinus, lying on the outer side 
 of the internal carotid artery (Fig. 454). It enters the orbit through the sphenoid 
 fissure, and lies above the ophthalmic vein, from which it is separated by a lamina 
 of dura mater (Fig. 675) . It then passes between the two heads of the External 
 rectus muscle, and is distributed to that muscle on its ocular surface. 
 
 Branches of Communication. — It is joined by several filaments from the 
 carotid and cavernous plexuses, and by one from the ophthalmic nerve. 
 
 Relations to Each Other of the Third, Fourth, Ophthalmic Division of the Fifth and 
 Sixth Nerves as They Pass to the Orbit. — The third, the fourth, the ophthalmic 
 division of the fifth, and the sixth nerves, as they pass to the orbit, bear a certain 
 relation to each other in the cavernous sinus, at the sphenoidal fissure, and in the 
 cavity of the orbit, which will now be described. 
 
 In the Cavernous Sinus (Figs. 454 and 455) the third, fourth, and ophthalmic 
 division of the fifth are placed on the outer wall of the sinus, in their numerical 
 
1044 
 
 THE NERVOUS SYSTEM 
 
 Frontal. 
 
 order, both from above downward and from within outward. The sixth nerve 
 lies at the outer side of the internal carotid artery. As these nerves pass for- 
 ward to the sphenoidal fissure, the third and fifth nerves become divided into 
 branches, and the sixth nerve approaches the rest, so that their relative position 
 becomes considerably changed. 
 
 In the Sphenoidal Fissure (Fig. 675) the fourth nerve and the frontal and 
 lachrymal branches of the ophthalmic division of the fifth lie upon the same 
 plane, the former being most internal, the latter external, and they enter the cavity 
 of the orbit above the muscles. The remaining nerves enter the orbit between 
 the two heads of the External rectus muscle. The superior division of the third 
 
 nerve is the highest of these; beneath 
 Lachrymal. this Hes the nasal branch of the 
 
 ophthalmic nerve; then the inferior 
 division of the third nerve; and the 
 sixth nerve lowest of all. 
 
 In the Orbit (Figs. 665 and 669) 
 the fourth nerve and the frontal and 
 lachrymal divisions of the ophthalmic 
 nerve lie on the same plane immedi- 
 ately beneath the periosteum, the 
 fourth nerve being internal and rest- 
 ing on the Superior oblique muscle, 
 the frontal nerve resting on the Le- 
 vator palpebrae muscle, and the lach- 
 rymal nerve on the External rectus 
 muscle. Next in order comes the superior division of the third nerve, lying 
 immediately beneath the Superior rectus muscle, and then the nasal branch of 
 the ophthalmic nerve, crossing the optic nerve from the outer to the inner side 
 of the orbit. Beneath these is found the optic nerve, surrounded in front by the 
 ciliary nerves, and having the lenticular ganglion on its outer side, between it and 
 the External rectus muscle. Below the optic nerve is the inferior division of the 
 third nerve and the sixth nerve, which lies on the outer side of the orbit. 
 
 Fia. 675.- 
 
 '' Superior division of Sd, 
 Nasal. 
 Inferior division of Sd. 
 6th. 
 Ophthalmic vein. 
 
 -Relations of structures passing through 
 the sphenoidal fissure. 
 
 Surgical Anatomy. — It is often stated that the sixth nerve is more frequently involved in 
 fractures of the base of the skull than any other of the cranial nerves. As a matter of fact, however, 
 it is injured in only about 2 per cent, of cases of fracture of the skull (Putscher). Cases have been 
 reported in which the nerve was actually ruptured. The nerve may be injured by traction, 
 pressure of a blood clot, of a tumor, or of an arterio-venous aneurism. The result of paralysis of 
 this nerve is internal or convergent squint. When injured so that its function is destroyed, there 
 is, in addition to the paralysis of the External rectus muscle, often a certain amount of contrac- 
 tion of the pupil, because some of the sympathetic fibres to the radiating muscle of the iris pass 
 along with this nerve. 
 
 THE SEVENTH OR FACIAL NERVE (N. FACIALIS) (Figs. 676, 677, 678). 
 
 The seventh or facial nerve or Portio Dura is the motor nerve of all the muscles 
 of expression in the face, and of the Platysma and Buccinator; the muscles of 
 the External ear; the posterior belly of the Digastric, and the Stylo-hyoid. Its 
 chorda tympani branch is the nerve of taste for the anterior two-thirds of the 
 tongue and the vaso-dilator nerve of the submaxillary and sublingual glands; its 
 tympanic branch supplies the Stapedius. 
 
 Its superficial origin is from the upper end of the medulla oblongata, in the 
 groove between the olivary and restiform bodies. Its deep origin is from a nucleus 
 situated in the floor of the fourth ventricle, beneath the superior fovea (Fig. 613). 
 
THE SEVENTH OB FACIAL NEBVE 1045 
 
 The facial nucleus is deeply placed in the reticular formation of the lower part of 
 the pons, a little external and ventral to the nucleus of the sixth nerve. From this 
 origin the fibres pursue a curved course in the substance of the pons. They first 
 pass backward and inward, and then turn upward and forward, forming the fas- 
 ciculus teres, which produces an eminence, the eminentia teres, on the floor of the 
 fourth ventricle, and finally bend sharply downward and outward around the upper 
 end of the nucleus of origin of the sixth nerve, to reach their superficial origin 
 between the olivary and restiform bodies. From the nucleus of the third nerve 
 some fibres arise which descend in the posterior longitudinal bundle and join the 
 facial just before it leaves the pons; these fibres are said to supply the anterior 
 belly of the Occipito-frontalis, 
 the Orbicularis palpebrarum, and 
 the Corrugator supercilii, as these External petrosal.. 
 
 muscles have been observed to f^^l^^^l^^ffZlir 
 
 escape paralysis in lesions of the Intumescentia ganglio/ormis 
 
 nucleus of the facial nerve. 
 
 The auditory nerve {portio mol- 
 lis) lies to the outer side of the 
 
 facial nerve ; and between the two ^'^- 676.-The course^and^onnecUon^of the facial nerve 
 
 is a small fasciculus, the pars in- 
 termedia of Wrisberg (n. intermedius), which arises from the medulla and joins 
 the facial nerve in the internal auditory meatus. The deep origin of the pars 
 intermedia is from the upper end of the nucleus of the glosso-pharyngeal nerve, 
 and at its emergence it is frequently connected with both nerves. 
 
 The pars intermedia may be regarded as the sensory root of the facial nerve, 
 analogous to the sensory root of the fifth, and its real nucleus of origin would then 
 consist of the geniculate ganglion. 
 
 The facial nerve, firmer, rounder, and smaller than the auditory, passes forward 
 and outward upon the middle peduncle of the cerebellum, and enters the internal 
 auditory meatus with the auditory nerve. Within the meatus the facial nerve 
 lies in a groove along the upper and anterior part of the auditory nerve and the 
 pars intermedia is placed between the two, and joins the inner angle of the geni- 
 culate ganglion. Occasionally a few of its fibres pass into the auditory nerve. 
 Beyond the ganglion its fibres are generally regarded as forming the chorda 
 tympani. 
 
 At the bottom of the meatus the facial nerve enters the aquaeductus Fallopii, 
 and follows the course of that canal through the petrous portion of the temporal 
 bone, from its commencement at the internal meatus to its termination at the stylo- 
 mastoid foramen (Figs. 49 and 676). It is at first directed outward between the 
 cochlea and vestibule toward the inner wall of the tympanum; it then bends sud- 
 denly backward and arches downward behind the tympanum to the stylo-mastoid 
 foramen. At the point in the aqueduct of Fallopius where the nerve changes its 
 direction (geniculum n. facialis), it presents a reddish gangliform swelling, the genic- 
 ulate ganglion {ganglion geniculi), which is also called the intumescentia ganglio- 
 formis (Fig. 676). The geniculate ganglion receives a branch from the vestibular 
 division of the auditory nerve, which probably carries fibres of the pars intermedia. 
 On emerging from the stylo-mastoid foramen the facial nerve runs forward in the 
 substance of the parotid gland, crosses the external carotid artery, and divides 
 behind the ramus of the lower jaw into two primary branches, temporo-facial 
 and cervico-facial, from which numerous offsets are distributed over the side of 
 the head, face, and upper part of the neck, supplying the superficial muscles 
 in these regions. As the primary branches and their offsets diverge from each 
 other, they present somewhat the appearance of a bird's claw; hence the name of pes 
 anserinus is given to the divisions of the facial nerve in and near the parotid gland. 
 
1046 
 
 THE NERVOUS SYSTEM 
 
 In the internal auditory meatus 
 
 Branches of Communication (Fig. 677). — The communications of the facial 
 nerve may be thus arranged: 
 
 ' With the auditory nerve. The pars 
 intermedia, which is between the 
 facial and auditory, gives branches 
 to both. The branch given to the 
 auditory accompanies it for a certain 
 distance, and then departs from it to 
 join the geniculate ganglion. 
 
 With the auditory as explained above. 
 
 With Meckel's ganglion by the large 
 superficial petrosal nerve. 
 
 With the otic ganglion by the small 
 superficial petrosal nerve. 
 
 With the sympathetic on the middle 
 meningeal artery by the external 
 superficial petrosal nerve. 
 
 With the auricular branch of the pneu- 
 mogastric. 
 
 With the glosso-pharyngeal. 
 
 With the pneumogastric. 
 
 With the auricularis magnus. 
 
 With the auriculo-temporal. 
 
 With the small occipital. 
 
 With the three divisions of the fifth. 
 
 With the superficial cervical. 
 
 From the geniculate ganglion 
 
 In the Fallopian aqueduct . 
 
 At its exit from the stylo-mastoid 
 foramen . . . . . 
 
 Behind the ear . . . . 
 
 On the face . . . . 
 
 In the neck . . . . 
 
 In the internal auditory meatus some minute filaments pass between the facial 
 and auditory nerves. 
 
 Opposite the hiatus Fallopii, the gangliform enlargement on the facial nerve 
 communicates with Meckel's ganglion by means of the large superficial petrosal 
 nerve, which forms its motor root; with the otic ganglion, by the small superficial 
 petrosal nerve; and with the sympathetic filaments accompanying the middle 
 meningeal artery, by the external petrosal nerve (Bidder). From the gangliform 
 enlargement, according to Arnold, a twig is sent back to the auditory nerve. Just 
 before the facial nerve emerges from the stylo-mastoid foramen it generally receives 
 a twig of communication from the auricular branch of the pneumogastric. 
 
 After its exit from the stylo-mastoid foramen, it sends a twig to the glosso- 
 pharyngeal, another to the pneumogastric nerve, and communicates with the great 
 auricular branch of the cervical plexus, with the auriculo-temporal branch of the 
 inferior maxillary nerve in the parotid gland, with the small occipital nerve 
 behind the ear, on the face with the terminal branches of the three divisions of 
 the fifth, and in the neck with the transverse cervical. 
 
 Branches of Distribution (Fig. 677). — ^The branches of distribution of the 
 facial nerves may be thus arranged : 
 
 f Tympanic, to the Stapedius muscle. 
 •- Chorda tympani. 
 Posterior Auricular. 
 
 Within the aquaeductus Fallopii 
 
 At its exit from the stylo-mastoid 
 foramen . . . . . 
 
 On the face 
 
 Digastric. 
 
 Stylo-hyoid. 
 
 f Temporal. 
 f Temporo-facial j Malar. 
 J I Infraorbital. 
 
 f Buccal. 
 Supram axillary. 
 Inframaxillarv. 
 
THE SEVENTH OB FACIAL NERVE 
 
 1047 
 
 The branches of the two terminal divisions form the parotid plexus {^plexus paro- 
 iideus) . 
 
 The Tympanic Branch (n. 5topec?fM5) (Fig. 677). — The tympanic brancli arises 
 from the nerve opposite the pyramid; it passes through a small canal in the 
 pyramid and supplies the Stapedius muscle. 
 
 The Chorda Tympani (Figs. 671, 676, and 677). — The chorda tympani is given 
 off from the facial as it passes vertically downward at the back of the tympanum, 
 about a quarter of an inch before its exit from the stylo-mastoid foramen. It 
 passes from below upward and forward in a distinct canal, and enters the cavity 
 of the tympanum through an aperture {iter chordae posterius) on its posterior wall 
 between the opening of the mastoid cells and the attachment of the membrana 
 tympani, and becomes invested with mucous membrane. It passes forward through 
 the cavity of the tympanum, between the fibrous and mucous layers of the mem- 
 brana tympani, and over the handle of the malleus, emerging from that cavity 
 
 To Auditory 
 
 Vidinn, 
 Large Deep Petromxl 
 
 Digastric 
 Stylo-hyoid' 
 
 Supramaxillary 
 Inframaxillary 
 
 Fig. 677. — Plan of the facial nerve. 
 
 through a foramen at the inner end of the Glaserian fissure, which is called the 
 canal of Hugmer {iter chordae anterius). It then descends between the two 
 Pterygoid muscles, meets the lingual nerve at an acute angle, and accompanies 
 it to the submaxillary gland ; part of it then joins the submaxillary ganglion ; the 
 rest is continued onward through the muscular substance of the tongue to the 
 mucous membrane covering its anterior two-thirds. A few of its fibres probably 
 pass through the submaxillary ganglion to the sublingual gland. Before joining 
 the lingual nerve it receives a small communicating branch from the otic ganglion. 
 As already stated, the chorda tympani nerve is by many regarded as the con- 
 tinuation of the pars intermedia of Wrisberg. 
 
 The Posterior Auricular Nerve {n. auricularis posterior) (Figs. 634, 677, and 678) . — 
 The posterior auricular nerve arises close to the stylo-mastoid foramen, and passes 
 upward in front of the mastoid process and between the mastoid process and the 
 external ear, where it is joined by a filament from the auricular branch of the 
 pneumogastric (Fig. 684), and communicates with the mastoid branch of the great 
 
1048 
 
 THE NERVOUS SYSTEM 
 
 auricular and with the small occipital. As it ascends between the external auditory 
 meatus and the mastoid process it divides into two branches, the auricular and 
 the occipital branches. 
 
 The Auricular Branch supplies the Retrahens auriculam and the small muscles 
 on the cranial surface of the pinna. 
 
 The Occipital Branch {ramus occipitalis), the larger, passes backward along the 
 superior curved line of the occipital bone, and supplies the occipital portion of the 
 Occipito-frontalis. 
 
 The Digastric Branch of the Facial Nerve (ramus digastricus) . — The digastric 
 branch usually arises by a common trunk with the Stylo-hyoid branch; it divides 
 into several filaments, which supply the posterior belly of the Digastric; one of 
 these perforates that muscle to join the glosso-pharyngeal nerve {ramus anasto- 
 unoticus cum n. glossopharyngeo) . 
 
 Tenninationa 
 of supratrochlear. 
 
 of infratrochlear 
 of nasal. 
 
 Fig. 678. — The nerves of the scalp, face, and side of the neck. 
 
 The Stylo-hyoid Branch (ramus stylohyoideus). — The stylo-hyoid branch is a 
 long, slender branch, which passes inward, entering the Stylo-hyoid muscle about 
 its middle. 
 
 The Temporo-facial Division (Figs. 677 and 678). — The temporo-facial, the larger 
 of the two terminal branches of the facial, passes upward and forward through 
 
THE SEVENTH OR FACIAL NERVE 1049 
 
 the parotid gland, crosses the external carotid artery and temporo-maxillary vein, 
 and passes over the neck of the condyle of the jaw, being connected in this situation 
 with the auriculo-temporal branch of the inferior maxillary nerve, and divides 
 into branches which are distributed over the temple and upper part of the face; 
 these are divided into three sets — temporal, malax, and infraorbital. 
 
 The Temporal Branches {rami temporales) cross the zygoma to the temporal 
 region, supplying the Attrahens and Attollens auriculam muscles, and join with 
 the temporal branch of the temporo-malar division of the superior maxillary, 
 and with the auriculo-temporal branch of the inferior maxillary. The more ante- 
 rior branches supply the frontal portion of the Occipito-frontalis, the Orbicularis 
 palpebrarum, and Corrugator supercilii muscles, joining with the supraorbital 
 an(l lachrymal branches of the ophthalmic. 
 
 The Malar Branches (rami zygomatici) pass across the malar bone to the outer 
 angle of the orbit. Where they supply the Orbicularis palpebrarum muscle, join- 
 ing with filaments from the lachrymal nerve; others supply the lower eyelid, 
 joining with filaments of the malar branch (subcutaneous malae) of the superior 
 maxillary nerve. 
 
 The Infraorbital Branches (rami huccales) , of larger size than the rest of the malar 
 branches, pass horizontally forward to be distributed between the lower margin of 
 the orbit and the mouth. The superficial branches run beneath the skin and 
 above the superficial muscles of the face, which they supply; some branches are 
 distributed to the Pyramidalis nasi, joining at the inner angle of the orbit with the 
 infratrochlear and nasal branches of the ophthalmic. The deep branches pass 
 beneath the Zygomatici and the Levator labii superioris, supplying the Levator 
 anguli oris, the Levator labii superioris alaeque nasi and the small muscles of the 
 nose, and form a plexus, infraorbital plexus, by joining with the branches of the 
 infraorbital branch of the superior maxillary nerve and the buccal branches of 
 the cervico-facial. 
 
 The Cervico-facial Division. — The cervico-facial division of the facial nerve 
 passes obliquely downward and forward through the parotid gland, crossing the 
 external carotid artery. In this situation it is joined by branches from the great 
 auricular nerve. Opposite the angle of the lower jaw it divides into branches 
 which are distributed on the lower half of the face and upper part of the neck. 
 These may be divided into three sets — buccal, supramaxillary, and inframaxillary. 
 
 The Buccal Branches (rami huccales) cross the Masseter muscle. They supply 
 the Buccinator and Orbicularis oris, and join with the infraorbital branches of 
 the temporo-facial division of the nerve, and with filaments of the buccal branch 
 of the inferior maxillary nerve. 
 
 The Supramaxillary or Supramandibular Branch (ramus marginalis mandibulae) 
 passes forward beneath the Platysma and Depressor anguli oris, supplying the 
 muscles of the lower lip and chin, and communicating with the mental branch of 
 the inferior dental nerve. 
 
 The Inframaxillary, Inframandibular or Cervical Branch (ramu^ colli) runs for- 
 ward beneath the Platysma, and forms a series of arches across the side of the 
 neck over the suprahyoid region. A branch descends vertically to join with the 
 superficial cervical nerve from the cervical plexus; others supply the Platysma. 
 
 Surgical Anatomy. — The facial nerve is more frequently paralyzed than any of the other 
 of the cranial nerves. The paralysis may depend either upon (1) central causes — i. e., blood-clots 
 or intracranial tumors pressing on the nerve before its entrance into the internal auditory meatus. 
 It is also one of the nerves involved in bulbar paralysis. Or (2) it may be paralyzed in its pass- 
 age through the petrous bone by damage due to middle-ear disease or by fractures of the base. 
 Or (3) it may be affected at or after its exit from the stylo-mastoid foramen. This is commonly 
 known as BelVs paralysis. It may be due to exposure to cold or to injury of the nerve, either 
 from accidental wounds of the face or during some surgical operation, as removal of parotid 
 tumors, opening of abscesses, or operations on the lower jaw. 
 
1050 ^^^ NERVOUS SYSTEM 
 
 When the cause is central, the sixth nerve is usually paralyzed as well, and there is also hemi- 
 plegia on the opposite side. In these cases the electric reactions are the same as in health; 
 whereas, when the paralysis is due to a lesion in the course of the nerve, the reactions of degenera- 
 tion develop, \^'hen the nerve is paralyzed in the petrous bone, in addition to the paralysis of the 
 muscles of expression, there is loss of taste in the anterior part of the tongue, and the patient is 
 unable to recognize the difference between bitters and sweets, acids and salines, from involvement 
 of the chorda tympani. The mouth is dry, because the salivary glands are not secreting; the sense 
 of hearing is affected from paralysis of the Stapedius, but there is not hemiplegia. When the 
 cause of the paralysis is from fracture of the base of the skull, the auditory nerve and the petrosal 
 nerves, which are connected with the intumescentia ganglioformis, are also involved. When the 
 injury to the nerve is after its exit from the stylo-mastoid foramen, all the muscles of expression, 
 except the Levator palpebrae, together with the posterior belly of the Digastric and Stylo-hyoid, 
 are paralyzed. There is smoothness of the forehead, and the patient is unable to frown; the 
 eyelids cannot be closed, and the lower lid droops, so that the punctum is no longer in contact 
 with the globe, and the tears run down the cheek; there is smoothness of the cheek and loss of 
 the naso-labial furrow; the nostril of the paralyzed side cannot be dilated; the mouth is drawn 
 to the sound side, and there is inability to whistle; food collects between the cheek and gum 
 from paralysis of the Buccinator. 
 
 The facial nerve is at fault in cases of so-called histrionic spasm, which consists in an almost 
 constant and uncontrollable twitching of the muscles of the face. This twitching is sometimes 
 so severe as to cause great discomfort and annoyance to the patient and to interfere with sleep, 
 and for its relief the facial nerve has been stretched. The operation is performed by making 
 an incision behind the ear from the root of the mastoid process to the angle of the jaw. The 
 parotid is turned forward, and the dissection carried along the anterior border of the Sterno- 
 mastoid muscle and mastoid process until the upper border of the posterior belly of the Digas- 
 tric is found. The nerve is parallel to this on about a level with the middle of the mastoid process. 
 When found, the nerve may be stretched by passing a blunt hook beneath it and pulling it 
 forward and outward. Too great force must not be used, for fear of permanent injury to the 
 nerve. In facial palsy of extracerebral origin it may be advisable to expose the nerve, cut it 
 across, and anastomose the distal end of the paralyzed nerve to the spinal accessory, or, better, 
 to the hypoglossal nerve (facio-accessory anastomosis or facio-hypoglossal anastomosis). The 
 idea was first proposed by Ballance, and has been put in practice by Ballance and Stewart, 
 Keen, Gushing, Faure, Kennedy and others. 
 
 THE EIGHTH OR AUDITORY NERVE (N. AOUSTIOUS) (Fig. 679). 
 
 The eighth or auditory nerve or Portio Mollis is the special nerve of the sense 
 of hearing, being distributed exclusively to the internal ear. It is soft in texture; 
 hence the name, fortio mollis, and is destitute of neurilemma. 
 
 The Origin of the Eighth Nerve. — The eighth nerve consists of two sets of 
 fibres, which, although differing in their central connections, are both concerned in 
 the transmission of afferent impulses from the internal ear to the medulla and pons, 
 and from there, by means of new fibres which arise from collections of gray matter 
 in these structures, to the cerebrum and cerebellum. One set of fibres forms the 
 vestibular root, another set forms the cochlear root of the nerve. At its con- 
 nection with the brain the eighth nerve occupies the groove between the pons 
 and medulla, where it is situated between the restiform body, which is behind, 
 and the seventh nerve, which is in front. 
 
 Vestibular, Nexal or Ventral Root (radix vestibularis) (Fig. 613). — The fibres of this 
 root enter the medulla to the inner side of those of the cochlear root, and pass 
 between the restiform body, which is to their outer side, and the inferior root of the 
 fifth, which lies to their inner side. They then divide into an ascending and a 
 descending set. The fibres of the latter end by arborizing around the cells of the 
 internal nucleus, which is situated in the trigonum acustici in the floor of 
 the fourth ventricle. The ascending fibres either end in the same manner or in the 
 external nucleus, which is situated to the outer side of the trigonum acustici and 
 farther from the ventricular floor. It is described as consisting of two parts, an 
 inner, the nucleus of Deiters, and an outer, the nucleus of Bechterew. Some of the 
 axones of the cells of the external nucleus, and possibly also of the internal nucleus, 
 are continued upward through the restiform body to the roof nuclei of the opposite 
 
THE EIGHTH OB AUDITORY NERVE 
 
 1051 
 
 side of the cerebellum, to which also are prolonged other fibres of the vestibular 
 root without undergoing a relay in the nuclei of the medulla. A second set of 
 fibres from the internal and external nuclei end partly in the tegmentum, while 
 the remainder ascend in the posterior longitudinal bundle to arborize around the 
 nuclei of the oculo-motor nerve. 
 
 Cochleax, Dorsal or Lateral Root {radix cochlearis) (Fig. 613). — This part of the 
 nerve is placed externally to the vestibular root. Its fibres end in two nuclei, 
 one of which, the accessory nucleus, lies immediately in front of the restiform 
 body; the other, the tuberculum acusticum, somewhat to its outer side. 
 
 The striae acusticae or medullary striae are the axones of the cells of the tuber- 
 culum acusticum. They pass backward and inward over the restiform body, and 
 across the floor of the fourth ventricle toward the middle line. Here they dip into 
 the substance of the pons, to end around the cells of the superior olive of the same 
 or opposite side. There are, however, other fibres, and these are both direct and 
 crossed, which do not arborize around the tegmental nuclei, but pass into the lat- 
 
 FiG. 679. — Distribution of the auditory nerve. (Semidiagrammatic.) (Testut.) 
 
 eral fillet. The cells of the accessory nucleus give origin to fibres which pass trans- 
 versely in the pons and constitute the trapezium. The description given as to the 
 mode of ending of the striae acusticae is applicable to that of the trapezoid fibres — 
 viz., around the cells of the superior olive or of the trapezoid nucleus (which lies 
 ventral to the olive) of the same or opposite side, while others, crossed or uncrossed, 
 pass directly into the lateral fillet. 
 
 If the further connections of the cochlear nerve of one side, say the left, are 
 considered, it is found that they lie to the outer side of the main sensory tract, the 
 fillet, and are therefore termed the lateral fillet. The fibres comprising the left 
 lateral fillet arise in the superior olive or trapezoid nucleus of the same or opposite 
 side, while others are the uninterrupted fibres already alluded to, and these are 
 either crossed or uncrossed, the former being the axones of the cells of the right 
 accessory nucleus or of the cells of the right tuberculum acusticum, while the latter 
 are derived from the same cells of the left side. In the upper part of the fillet 
 there is a collection of nerve-cells, the nucleus of the fillet (fila anastomotica) , around 
 
1052 
 
 THE NEBVOUS SYSTEM 
 
 the cells of which some of the fibres arborize, and from the cells of which axones 
 originate to continue upward the tract of the lateral fillet. The ultimate ending 
 of the left lateral fillet is partly in the quadrigeminal bodies of the same or opposite 
 
 SchlX. 
 
 Fig. 680. — Diagram of the central auditory tract (direct or root-fibre system): N.c, cochlear nerve; F.a., 
 acoustic tubercle; v.K., ventral nucleus; c.t., trapezoid body; o.O., o.O., superior olives; R., raph6; Schl.K., 
 nucleus of the lemniscus; o.V.. pregeminum; Ri., cortex, (Rauber, after Held.) 
 
 Fig. 681. — Diagram of the central auditory tract (system of the second order): A''.c., cochlear nerve; v.K., 
 ventral nucleus; c.t., trapezoid body; R., raph(?; T.K., trapezoid nucleus; o.O., superior olive; T.a., acoustic 
 tubercle; S<.a., acoustic striae; /.<S.K., nucleus of the lateral lemniscus; Ba., prepeduncle; Bat., decussation of 
 the prepeduncle; o.V., pregeminum; n.V., post-geminum; Ri., cortex; Rb., cortical tract. (Rauber, after Held.) 
 
 I 
 
THE EIGHTH OB AUDITORY NERVE 
 
 1053 
 
 side, while the remainder of the fibres ascend in the posterior Hmb of the internal 
 capsule to reach the first and perhaps the second left temporal convolution. 
 
 The auditory nerve contains a few afferent fibres which arise in the quadrigem- 
 inal bodies, the nucleus of the lateral fillet, trapezoid nucleus, and superior olive. 
 
 The auditory nerve after leaving the medulla passes forward across the poste- 
 rior border of the middle peduncle of the cerebellum, in company with the facial 
 nerve, from which it is partly separated by a small artery, the auditory. It then 
 enters the internal auditory meatus with the facial nerve. In the meatus it divides 
 into its two branches, the inferior or cochlear trunk (n. cochleae) and the superior or 
 vestibular trunk (w. vestihuli). The cochlear trunk is a continuation of the cochlear 
 root, gives branches to the macula acustica of the saccule, and to the ampulla of 
 the posterior semicircular canal, and then passes through the lamina cribrosa 
 to the labyrinth. The cochlear nerve is distributed to the modiolus and osseous 
 spiral lamina, and is finally distributed to the organ of Corti. The vestibular 
 
 mmm "^ 
 
 TJL. 
 
 Fig. 682. — Diagram of the central auditory tract (recurrent system'): v.K., ventral nucleus; c.t., trapezoid 
 body; R., rapW; TK., trapezoid nucleus; o.O., superior olive; Ta., acoustic tubercle; Sia., acoustic striae; S.K., 
 nucleus of the lemniscus; o. V., pregeminum; n. F., post-geminum; fli., coterx. (Rauber, after Held.) 
 
 trunk is a continuation of the vestibular root. In the internal meatus it receives 
 fibres of the pars intermedia and gives a branch to the geniculate ganglion of 
 the facial nerve (Cunningham^ It divides into three branches, which pass 
 through the lamina cribrosa and are distributed, one to the macula acustica of 
 the utricle and the ampulla, one to the superior semicircular canal, and one to 
 the external semicircular canal. There is a ganglion on the vestibular nerve 
 called the vestibular ganglion (ganglion vestihulare) , and a ganglion on the cochlear 
 nerve, the ganglion of Corti (ganglion spirale). The fibres of the auditory nerve 
 proper arise in these ganglia; the vestibular fibres in the ganglion vestibulare; 
 the cochlear fibres in the ganglion spirale. 
 
 The Auditory Paths (Figs. 680, 681, and 682).— There are two auditory 
 paths, the cochlear or central auditory path and the vestibular path. 
 
 The Cochlear Path. — ^The cochlear path conducts impulses of hearing. Such 
 impulses pass from the organ of Corti to the ganglion of Corti (ganglion spirale) 
 and then by the cochlear fibres to the cochlear nucleus in the medulla. The 
 path from the nucleus to the cortical auditory centre is described as follows 
 
1054 THE NERVOUS SYSTEM 
 
 by Santee.^ Impulses from the cochlear nucleus "run either lateral and dorsal 
 to the restiform body and cross to the opposite side through the acustic striae 
 and trapezium, or they run medial to the restiform body and enter at once into 
 the trapezium. By either course they reach the lateral fillet, and chiefly the oppo- 
 site one. The lateral fillets conduct the impulses to the inferior quadrigeminal 
 bodies; the inferior brachia to the internal geniculate bodies, and the acustic radia- 
 tion to the third and fourth fifths of the superior temporal and to the transverse 
 temporal gyri of the cerebrum." 
 
 The Vestibular Path. — The vestibular path conducts impulses of equilibrium. 
 Impulses from the semicircular canals, utricle and saccule pass by way of the 
 vestibular nerve to the vestibular nuclei in the floor of the fourth ventricle and a 
 spinal nucleus of undetermined situation. From these nuclei impulses pass to the 
 nuclei in the opposite side of the cerebellum by one of two routes. Either by the 
 opposite medial fillet and fibres of the systems of Flechsig or through the acustico- 
 cerebellar tract and fibres of the vestibular nerve in the restiform body to the 
 opposite cerebellum (nucleus fastigii, nucleus globosus, corpus dentatum, and 
 cerebellar cortex).^ From the cerebellum impulses pass along the superior 
 peduncle to "the red nucleus and optic thalamus of both sides and thence to the 
 cortex. They may excite in the cerebellum impulses of equilibration, which 
 descend to the motor nuclei of spinal nerves in the anterior horns of gray matter 
 by way of the antero-lateral descending cerebellar tracts" (Santee). 
 
 Surgical Anatomy. — The auditory nerve is frequently injured, together with the facial nerve, 
 in fractures of the middle fossa of the base of the skull implicating the internal auditory meatus. 
 The nerve may be either torn across, producing permanent deafness, it may be bruised or it may 
 be pressed upon by extra vasated blood or inflammatory exudation, when the deafness will in all 
 probability be temporary. The nerve may also be injured by violent blows on the head without 
 fracture, and deafness may follow loud explosions of dynamite, etc., probably from some lesion 
 of this nerve, which is more liable to be injured than the other cranial nerves on account of 
 its structure. The test that the nerve is destroyed and that the deafness is not due to some 
 lesion of the auditory apparatus is obtained by placing a vibrating tuning-fork on the head. 
 The vibrations will be heard in cases where the auditory apparatus is at fault, but not in cases 
 of destruction of the auditory nerve. 
 
 THE NINTH OR GLOSSO-PHARYNGEAL NERVE (N. GLOSSOPHARYNGEUS) 
 
 (Figs. 683, 684, 685). 
 
 The ninth or glosso-pharyngeal nerve is distributed, as its name implies, to 
 the tongue and pharynx, being the nerve of ordinary sensation to the mucous 
 
 membrane of the pharynx, fauces, and tonsil ; and the 
 juffuiaraan^. ncrvc of taste to all parts of the tongue to which it is 
 
 distributed. 
 
 Its superficial origin is by three or four filaments, 
 closely connected together, from the upper part of the 
 medulla oblongata, in the groove between the olivary 
 and restiform body (Fig. 683). Its deep origin (Fig. 
 613) may be traced through the fasciculi of the lateral 
 tract to three different sources: (1) some of the fibres 
 may be traced to a nucleus of gray matter at the lower 
 Fig. 683— Origin, ganRiia, and part of the floor of the fourth vcntriclc beneath the 
 
 communicationof the ninth, tenth, • i? • p /r.\ ,^ i j^ 11 1 • j. 
 
 and eleventh cranial nerves. mtcrior lovea; (2) othcrs may DC traced downward mto 
 
 the funiculus solitarius, a rounded bundle of fibres in the 
 lower part of the medulla, commencing immediately above the decussation of the 
 pyramids (these fibres have not been distinctly traced to cells); (3) a third set of 
 
 1 Anatomy of the Brain and Spinal Cord. * Sante3, loc. cit. 
 
THE NINTH OR GL08SO- PHARYNGEAL NERVE 
 
 1055 
 
 Fig. 684. — Plan of the glosso-pharyngeal, pneumogastric, and spinal accessory nerves. (After Flower.) 
 
1056 THE NERVOUS SYSTEM 
 
 fibres takes origin from the cells of the nucleus ambiguus. This nucleus is 
 situated Sv^me distance from the floor of the fourth ventricle and lies slightly 
 internal to the inferior fovea. It gives origin to the motor branches of the glosso- 
 pharyngeal and vagus, and to the bulbar part of the spinal accessory. The real 
 origin of the sensory fibres of the glosso-pharyngeal must be looked for in the 
 jugular and petrosal ganglia which are developed from the neural crest. 
 
 From its superficial origin it passes outward across the flocculus, and leaves the 
 skull at the central part of the jugular foramen, in a separate sheath of the dura 
 mater, external to and in front of the pneumogastric and spinal accessory nerves 
 (Fig. 685). In its passage through the jugular foramen it grooves the lower 
 border of the petrous portion of the temporal bone, and at its exit from the skull 
 passes forward between the jugular vein and internal carotid artery, and descends 
 in front of the latter vessel, and beneath the styloid process of the temporal bone 
 and the muscles connected with it, to the lower border of the Stylo-pharyngeus 
 muscle. The nerve now curves inward, forming an arch on the side of the neck, 
 and lying upon the Stylo-pharyngeus muscle and the Middle constrictor of the 
 pharynx. It then passes beneath the Hyoglossus muscle, and is finally distributed 
 to the mucous membrane of the fauces and base of the tongue, and the mucous 
 glands of the mouth and tonsil. 
 
 In passing through the jugular foramen the nerve presents, in succession, two 
 gangliform enlargements. The superior and smaller is called the jugular ganglion ; 
 the inferior and larger, the- petrous ganglion or the ganglion of Andersch. 
 
 The Superior or Jugular Ganglion (Ganglion Superius n. Glossopharsmgei) 
 
 (Fig. 684). 
 
 The superior or jugular ganglion is situated in the upper part of the groove in 
 which the nerve is lodged during its passage through the jugular foramen. It is 
 of very small size, and involves only the lower part of the trunk of the nerve. 
 It is usually regarded as a segmentation from the lower ganglion. 
 
 The Inferior or Petrous Ganglion (Ganglion Petrosum n. Glossopharjmgei) 
 
 (Figs. 683 and 684). 
 
 The inferior or petrous ganglion is situated in a depression in the lower border 
 of the petrous portion of the temporal bone; it is larger than the superior ganglion 
 and involves the whole of the fibres of the nerve. From this ganglion arise 
 those filaments which connect the glosso-pharyngeal with the pneumogastric and 
 sympathetic nerves. 
 
 Branches of Communication (Fig. 684). — The branches of communication 
 are with the pneumogastric, sympathetic, and facial. 
 
 The branches to the pneumogastric are two filaments, arising from the petrous 
 ganglion, one of which passes to the auricular branch of the pneumogastric, and 
 one to the upper ganglion of the pneumogastric. 
 
 The branch to the sympathetic, also arising from the petrous ganglion, is con- 
 nected with the superior cervical ganglion. 
 
 The branch of communication with the facial perforates the posterior belly of 
 the Digastric muscle. It arises from the trunk of the nerve below the petrous 
 ganglion, and joins the facial just after its exit from the stylo-mastoid foramen. 
 
 Branches of Distribution (Fig. 684).— The branches of distribution are the 
 tympanic, carotid, pharyngeal, muscular, tonsillar, and lingual. 
 
 The Tympanic Branch or Jacobson's Nerve (n.tympanicus). — The tympanic branch 
 or Jacobson's nerve arises from the petrous ganglion, and enters a small bony 
 canal in the lower surface of the petrous portion of the temporal bone, the lower 
 
THE TENTH OB PNEUMOGASTBIC NEBVE 1057 
 
 opening of which is situated on the bony ridge which separates the carotid canal 
 from the jugular fossa. It ascends to the tympanum, enters that cavity by an 
 aperture in its floor close to the inner wall, and divides into branches which are 
 contained in grooves upon the surface of the promontory. These branches form 
 a tympanic plexus (plexus tympanicus). This plexus gives off (1) the greater 
 part of the small superficial petrosal nerve (Fig. 677) ; (2) a branch to join the 
 great superficial petrosal nerve; and (3) branches to the tympanic cavity, all of 
 which will be described in connection with the anatomy of the ear. 
 
 The Carotid Branches (n. caroticotympanicus superior and n. caroticotympanicus 
 inferior). — The carotid branches descend along the trunk of the internal carotid 
 artery as far as its commencement, communicating with the pharyngeal branch 
 of the pneumogastric and with branches of the sympathetic. 
 
 The Pharyngeal Branches (rami pharyngei)(F[g.684). — The pharyngeal branches 
 are three or four filaments which unite opposite the Middle constrictor of the 
 pharynx with the pharyngeal branches of the pneumogastric and sympathetic 
 nerves to form the pharjmgeal plexus, branches from which perforate the muscular 
 coat of the pharynx to supply the muscles and mucous membrane. 
 
 The Muscular Branch (ramu^ stylopharyngeus). — The muscular branch is dis- 
 tributed to the Stylo-pharyngeus muscle. 
 
 The Tonsillar Branches (rami tonsillares). — The tonsillar branches supply the 
 tonsil, forming a plexus (circulus tonsillaris) around this body, from which 
 branches are distributed to the soft palate and fauces, where they communicate 
 with the palatine nerves. 
 
 The Lingual Branches (rami linguales). — The lingual branches are two in num- 
 ber: one supplies the circumvallate papillae and the mucous membrane covering 
 the surface of the base of the tongue; the other perforates its substance, and 
 supplies the mucous membrane and follicular glands of the posterior one-third 
 of the tongue and communicates with the lingual nerve. 
 
 The Gustatory Path. — The impressions of taste reach the glosso-pharyngeal 
 nucleus in the medulla in two ways. From the posterior one-third of the tongue 
 and from the palate they reach the nucleus by the ninth nerve. From the anterior 
 two-thirds of the tongue impulses of taste are conveyed by the chorda tympani 
 and pars intermedia. From the glosso-pharyngeal nucleus gustatory impressions 
 pass by way of the medial fillet to the optic thalamus of the opposite side, and 
 from the optic thalamus through the inferior lamina of the internal capsule to the 
 gyrus hippocampi, where the cortical gustatory centre is situated. 
 
 Surgical Anatomy. — Injury may produce hemorrhage about the roots of the nerve. Bergmann 
 reported such a case. The patient died from oedema of the glottis after presenting evidences 
 of disorder of speech and difficulty in swallowing. 
 
 THE TENTH OR PNEUMOGASTRIC NERVE (N. VAGUS) (Figs. 683,684, 685). 
 
 The tenth or pneumogastric nerve has a more extensive distribution than any 
 of the other crainal nerves, passing through the neck and thorax to the upper part 
 of the abdomen. It is composed of both motor and sensory fibres. It supplies 
 the organs of voice and respiration with motor and sensory fibres, and the pharynx, 
 oesophagus, stomach, and heart with motor fibres. Its superficial origin (Fig. 683) 
 is by eight or ten filaments from the groove between the olivary and the restiform 
 body below the glosso-pharyngeal; its deep origin (Fig. 613) may be traced through 
 the fasciculi of the medulla to a nucleus of gray matter, the nucleus vagi, at the lower 
 part of the floor of the fourth ventricle beneath the ala cinerea below and continu- 
 ous with the nucleus of origin of the glosso-pharyngeal. In addition to this a few 
 fibres pass into the funiculus solitarius, and others into the nucleus ambiguus or 
 
 67 
 
1058 
 
 THE NERVOUS SYSTEM 
 
 Qlosso-phaiynaeal. v 
 
 Pneumogastric. ~-~, 
 
 Spinal accessory. 
 
 accessory vagal nucleus. The real origin of the sensory fibres of the vagus is to be 
 found in the cells of the ganglia on the nerve — viz., the ganglion of the root and 
 
 the ganglion of the trunk. The 
 filaments become united and 
 form a flat cord, which passes 
 outward beneath the flocculus 
 to the jugular foramen, through 
 which it emerges from the cran- 
 ium (Fig. 685). In passing 
 through this opening the pneu- 
 mogastric accompanies the spi- 
 nal accessory, being contained in 
 the same sheath of dura mater 
 with it, a membranous septum 
 separating them from the glosso- 
 pharyngeal, which lies in front 
 (Fig. 685). The nerve in this 
 situation presents a well-marked 
 ganglionic enlargement, which 
 is called the superior ganglion, 
 jugular ganglion, or the ganglion 
 of the pneumogastric; to it the 
 accessory part of the spinal ac- 
 cessory nerve is connected by 
 one or two filaments. After the 
 exit of the nerve from the jugular 
 foramen the nerve is joined by 
 the accessory portion of the 
 spinal accessory, and enlarges 
 into a second gangliform swell- 
 ing, called the inferior ganglion 
 or the ganglion of the trunk of 
 the nerve, through which the 
 fibres of the spinal accessory 
 pass unchanged, being prin- 
 cipally distributed to the pha- 
 ryngeal and superior laryngeal 
 branches of the vagus; but some 
 of the filaments from it are con- 
 tinued into the trunk of the 
 vagus below the ganglion, to be 
 distributed with the recurrent 
 laryngeal nerve, and probably 
 also with the cardiac nerves. 
 The vagus nerve passes verti- 
 cally down the neck within the 
 sheath of the carotid vessels lying 
 between the internal carotid 
 artery and the internal jugular 
 vein as far as the thyroid cartil- 
 age, and then between the same 
 vein and the common carotid to the root of the neck (Fig. 685). From here 
 the course of the nerve differs on the two sides of the body. 
 
 On the right side (Fig. 685) the nerve passes across the subclavian artery between 
 
 Fig. 685. — Course and distribution of the ninth, tenth, and 
 eleventh nerves. 
 
THE TENTH OB PNEUMOGASTBIC NERVE 1059 
 
 it and the right innominate vein, and descends by the side of the trachea to the hack 
 part of the root of the hing, where it spreads out in a plexiform network, the pos- 
 terior pulmonary plexus (plexus pulmonalis posterior), from the lower part of which 
 two corfls descend upon the oesophagus, on which tube they divide, forming, with 
 branches from the opposite nerve, the oesophageal plexus (p/exM5 gulae) ; below, these 
 branches are collected into a single cord, which runs along the back part of the 
 oesophagus, enters the abdomen, and is distributed to the posterior surface of 
 the stomach, joining the left side of the solar plexus, and sending filaments to the 
 splenic plexus and a considerable branch to the coeliac plexus. 
 
 On the left side the pneumogastric nerve enters the chest between the left carotid 
 and subclavian arteries, behind the left innominate vein. It crosses the arch of 
 the aorta and descends behind the root of the left lung, forming the anterior pul- 
 monary plexus {plexus pulvfionalis anterior), and along the anterior surface of the 
 oesophagus, where it unites with the nerve of the right side in forming the plexus 
 gulae. It passes to the stomach, distributing branches over the anterior surface of 
 that viscus, some extending over the great cul-de-sac, and others along the lesser 
 curvature. Filaments from these branches enter the gastro-hepatic omentum and 
 join the hepatic plexus. 
 
 The Ganglion of the Root of the Pneumogastric Nerve (Ganglion Jugulare) 
 
 (Fig. 684). 
 
 The ganglion of the root or the jugular ganglion is of a grayish color, circular 
 in form, about two lines in diameter, and resembles the ganglion on the large, 
 root of the fifth nerve. 
 
 Connecting Branches. — To this ganglion the accessory portion of the spinal 
 accessory nerve is connected by several delicate filaments; it also has a communi- 
 cating twig with the petrous ganglion of the glosso-pharyngeal, with the facial 
 nerve by means of its (the ganglion's) auricular branch, and with the sympa- 
 thetic by means of an ascending filament from the superior cervical ganglion. 
 
 The Ganglion of the Trunk of the Pneumogastric Nerve (Ganglion Nodosum) 
 
 (Fig. 684). 
 
 The ganglion of the trunk or the inferior ganglion is a plexiform cord, cylindrical 
 in form, of a reddish color, and about an inch in length; it involves the whole of 
 the fibres of the nerve, and passing through it is the accessory portion of the spinal 
 accessory nerve, which blends with the pneumogastric below the ganglion, and is 
 then principally continued into its pharyngeal and superior laryngeal branches. 
 
 Connecting Branches (Fig. 684).— This ganglion is connected with the hypo- 
 glossal, the superior cervical ganglion of the sympathetic, and the loop between 
 the first and second cervical nerves. 
 
 The branches of the pneumogastric are — 
 
 T .1 • 1 r i Meningeal. 
 
 In the lugular lossa . • 1 a • i 
 
 In the neck 
 
 In the thorax 
 
 •^ Auricular. 
 Pharyngeal. 
 Superior laryngeal. 
 Recurrent laryngeal. 
 Cervical cardiac. 
 Thoracic cardiac. 
 Anterior pulmonary. 
 Posterior pulmonary. 
 . Oesophageal. 
 In the abdomen . . . Gastric. 
 
 The Meningeal Branch {ramus meningeus). — The meningeal branch is a recurrent 
 filament given off from the ganglion of the root in the jugular foramen. It passes 
 
1060 THE NERVOUS SYSTEM 
 
 backward, and is distributed to the dura mater lining the posterior fossa of the 
 base of the skull. 
 
 The Auricular Branch or Arnold's Nerve {ramus auricularis) (Fig. 684). — The 
 auricular branch or Arnold's nerve arises from the ganglion of the root, and is 
 joined soon after its origin by a filament from the petrous ganglion of the glosso- 
 pharyngeal; it passes outward behind the jugular vein, and enters a small canal 
 on the outer wall of the jugular fossa. Traversing the substance of the tem- 
 poral bone, it crosses the aquaeductus Fallopii about two lines above its termina- 
 tion at the stylo-mastoid foramen; here it gives off an ascending branch, which 
 joins the facial; the continuation of the nerve reaches the surface by passing 
 through the auricular fissure between the mastoid process and the external audi- 
 tory meatus, and divides into two branches, one of which communicates with the 
 posterior auricular nerve, while the other supplies the integument at the back 
 part of the pinna and the posterior part of the external auditory meatus. 
 
 The Pharyngeal Branch {ramus pharyngeus). — The pharyngeal branch, the prin- 
 cipal motor nerve of the pharynx, arises from the upper part of the ganglion of the 
 trunk of the pneumogastric. It consists principally of filaments from the accessory 
 portion of the spinal accessory; it passes across the internal carotid artery to the 
 upper border of the Middle constrictor of the pharynx, where it divides into 
 numerous filaments which join with those from the glosso-pharyngeal, the supe- 
 rior laryngeal (its external branch), and sympathetic, to form the pharyngeal plexus 
 {plexus pharyngeus), from which branches are distributed to the muscles and 
 mucous membrane of the pharynx and the muscles of the soft palate. From the 
 pharyngeal plexus a minute filament is given off, which descends and joins the 
 hypoglossal nerve as it winds around the occipital artery. 
 
 The Superior Laryngeal Nerve {n. laryngeus superior) (Figs. 683, 684, and 685). — 
 It is larger than the preceding, and arises from the middle of the ganglion of the 
 trunk of the pneumogastric. It consists principally of filaments from the accessory 
 portion of the spinal accessory. In its course it receives a branch from the supe- 
 rior cervical ganglion of the sympathetic. It descends by the side of the pharynx 
 behind the internal carotid artery, where it divides into two branches, the external 
 and internal laryngeal. This nerve is the nerve of sensation of the larynx, and 
 also supplies the crico-thyroid muscle. Exner has pointed out that the superior 
 laryngeal nerve innervates to some extent the muscles supplied by the inferior 
 laryngeal, and this fact explains why division of the inferior laryngeal nerve is not 
 of necessity followed by complete paralysis of the muscles it supplies. 
 
 The External Laryngeal Branch of the Superior Larjmgeal {ramus externum) (Fig. 
 685) , the smaller, descends by the side of the larynx, beneath the Sterno-thyroid, 
 to supply the Crico-thyroid muscle. It gives branches to the pharyngeal plexus 
 and the Inferior constrictor, and communicates with the superior cardiac nerve, 
 behind the common carotid. 
 
 The Internal Larjmgeal Branch of the Superior Larjmgeal {ramus internus) 
 descends to the opening in the thyro-hyoid membrane, through which it passes 
 with the superior laryngeal artery, and is distributed to the mucous membrane of 
 the larynx. A small branch communicates with the recurrent laryngeal nerve. 
 The branches to the mucous membrane are distributed, some in front to the epi- 
 glottis, the base of the tongue, and the epiglottidean glands; while others pass 
 backward, in the aryteno-epiglottidean fold, to supply the mucous membrane 
 surrounding the superior orifice of the larynx, as well as the membrane which 
 lines the cavity of the larynx as low down as the vocal cord. The filament which 
 joins with the recurrent laryngeal descends beneath the mucous membrane on the 
 inner surface of the thyroid cartilage, where the two nerves become united. 
 
 The Inferior or Recurrent Laryngeal Branch of the Pneumogastric {n. laryngeus 
 inferior) (Figs. 684 and 685). — The inferior or recurrent laryngeal branch, so 
 called from its reflected course, is the motor nerve of the larvnx. It arises on 
 
 I 
 
THE TENTH OR PNEUMOGASTBIC NERVE 1061 
 
 the right side, in front of the subclavian artery; winds from before backward 
 around that vessel, and ascends obliquely to the side of the trachea, behind 
 the common carotid artery and behind or in front of the inferior thyroid artery. 
 On the left side it arises in front of the arch of the aorta, and winds from 
 before backward around the aorta at the point where the remains of the ductus 
 arteriosus are connected with it, and then ascends to the side of the trachea. 
 The nerve on each side ascends in the groove between the trachea and oesophagus, 
 and, passing under the lower border of the Inferior constrictor muscle, enters the 
 larynx behind the articulation of the inferior cornu of the thyroid cartilage with 
 the cricoid, being distributed to all the muscles of the larynx except the Crico- 
 thyroid. It communicates with the superior laryngeal nerve and gives off a few 
 filaments to the mucous membrane of the lower part of the larynx. 
 
 The recurrent laryngeal, as it winds around the subclavian artery and aorta, 
 gives off several cardiac filaments, which unite with the cardiac branches from 
 the pneumogastric and sympathetic. As it ascends in the neck it gives off oesoph- 
 ageal branches, more numerous on the left than on the right side, which supply 
 the mucous membrane and muscular coat of the oesophagus; tracheal branches to 
 the mucous membrane and muscular fibres of the trachea; and some pharyngeal 
 filaments to the Inferior constrictor of the pharynx. 
 
 The Cervical Cardiac Branches {rami cardiaci superiores) (Fig. 684). — The cer- 
 vical cardiac branches, two or three in number, arise from the pneumogastric, at 
 the upper and lower part of the neck. 
 
 The Superior Branches are small, and communicate with the cardiac branches 
 of the sympathetic. They can be traced to the great or deep cardiac plexus. 
 
 The Inferior Branches, one on each side, arise at the lower part of the neck, 
 
 just above the first rib. On the right side this branch passes in front or by the 
 
 'side of the arteria innominata, and communicates with one of the cardiac nerves 
 
 proceeding to the great or deep cardiac plexus. On the left side it passes in front 
 
 of the arch of the aorta and joins the superficial cardiac plexus. 
 
 The Thoracic Cardiac Branches (rami cardiaci inferiores) (Fig. 684) . — The thoracic 
 
 [cardiac branches, on the right side, arise from the trunk of the pneumogastric 
 
 as it lies by the side of the trachea, and from its recurrent laryngeal branch, but 
 
 on the left side from the recurrent nerve only; passing inward, they terminate 
 
 in the deep cardiac plexus. 
 
 The Anterior Pulmonary Branches (Fig. 684). — The anterior pulmonary branches, 
 two or three in number, and of small size, are distributed on the anterior aspect 
 of the root of the lungs. They join with filaments from the sympathetic, and form 
 the anterior pulmonary plexus (plexus pulmonalis anterior). 
 
 The Posterior Pulmonary Branches(Fig. 684). — The posterior pulmonary branches, 
 more numerous and larger than the anterior, are distributed on the posterior aspect 
 of the root of the lung; they are joined by filaments from the third and fourth 
 (sometimes also from the first and second) thoracic ganglia of the sympathetic, 
 and form the posterior pulmonary plexus (plexus pulmonalis posterior). Branches 
 from both plexuses accompany the ramification of the air-tubes through the sub- 
 stance of the lungs (rami bronchiales anteriores and rami bronchiales posteriores). 
 
 The Oesophageal Branches (rami oesophagei). — The oesophageal branches are 
 given off from the pneumogastric both above and below the pulmonary branches. 
 The lower are more numerous and larger than the upper. They form, together 
 with branches from the opposite nerve, the oesophageal plexus (plexus gulae). 
 From this plexus branches are distributed to the back of the pericardium. 
 
 The Gastric Branches (rami gastrici) (Figs. 684 and 685. — The gastric branches 
 are the terminal filaments of the pneumogastric nerve. The nerve on the right 
 side is distributed to the posterior surface of the stomach. The right pneumo- 
 gastric sends branches to the coeliac plexus (rami coeliaci), to the splenic plexus 
 (rami lienales), and to the renal plexus (rami renales). The nerve on the left 
 
1062 THE NEBVOUS SYSTEM 
 
 side is distributed over the anterior surface of the stomach, some filaments {rami 
 hepatici) passing across the great cul-de-sac, and others along the lesser curva- 
 ture. They unite with branches of the right nerve and with the sympathetic, 
 some filaments passing through the lesser omentum to the hepatic plexus. 
 
 Surgical Anatomy. — The laryngeal nerves are of considerable importance in considering 
 some of the morbid conditions of the larynx. When the peripheral terminations of the superior 
 laryngeal nerve are irritated by some foreign body passing over them, reflex .spasm of the glottis 
 is the result. When the trunk of the same nerve is pressed upon by, for instance, a goitre or 
 an aneurism of the upper part of the carotid, we have a peculiar dry, brassy cough. When the 
 nerve is paralyzed, we have anaesthesia of the mucous membrane of the larynx, so that foreign 
 bodies can readily enter the cavity, and, in consequence of its supplying the crico-thyroid muscle, 
 the vocal cords cannot be made tense, and the voice is deep and hoarse. Paralysis of the supe- 
 rior laryngeal nerves may be the result of bulbar paralysis, may be a sequel to diphtheria, when 
 both nerves are usually involved, or it may, though less commonly, be caused by the pressure 
 of tumors or aneurisms, when the paralysis is generally unilateral. Irritation of the inferior 
 laryngeal nerves produces spasm of the muscles of the larynx. When both the recurrent 
 nerves are paralyzed, the vocal cords are motionless in the so-called cadaveric position^that 
 is to say, in the position in which they are found in ordinary tranquil respiration — neither closed 
 as in phonation, nor open as in deep inspiratory effort. When one recurrent nerve is paralyzed, 
 the cord of the same side is motionless, while the opposite cord crosses the middle line to accom- 
 modate itself to the affected one ; hence phonation is present, but the voice is altered and weak 
 in timbre. The recurrent laryngeal nerves may be paralyzed in bulbar paralysis or after diph- 
 theria, when the paralysis usually affects both sides; or they may be affected by the pressure 
 of aneurisms of the aorta, innominate or subclavian arteries; by mediastinal tumors; by bron- 
 chocele; or by cancer of the upper part of the oesophagus, when the paralysis is often unilat- 
 eral. The nerve may be accidentally divided during the operation for goitre. 
 
 It is a well-recognized fact that disease or injury of the vagus may induce serious symptoms. 
 Bruising may cause such symptoms; so may injury of the nerve by a stab, a bullet, or during 
 surgical operations. Either accidental ligation or crushing with clamp forceps is particularly 
 dangerous. Michaux accidentally ligated the vagus, and the patient became comatose and 
 ceased to breathe, but was restored on removing the ligature. Tillmanns, while removing a 
 cancer, accidentally caught and crushed a portion of the nerve in a clamp, and both pulse and 
 respiration ceased. The clamp was removed, the patient was restored with difficulty, and the 
 nerve was sutured. Recovery followed. It thus becomes evident that division of the vagus on 
 one side is not, as was so long taught, a necessarily fatal accident; in fact, it is sometimes under- 
 taken deliberately in removing tumors adherent to the nerve. Division of a nerve which has 
 been long compressed is probably not so dangerous as division of a healthy nerve, as in the former 
 case the opposite vagus has probably assumed some of its colleague's duties. A number of cases 
 of deliberate division have been reported. Twenty-three cases are referred to in the system of 
 surgery by von Bergmann and Mikulicz, and twelve of them died, but in none of the deaths was 
 the removal of the vagus the apparent cause of the fatality. The editor of this American edition 
 of "Gray" has seen three cases: One was operated upon by Dr. W. Joseph Hearn, one by Dr. 
 Melvin Franklin, and one by the editor. All three recovered, and not one presented any 
 serious disturbance, although each had hoarseness and weakness of voice. 
 
 One would assume that after division of the pneumogastric below the superior laryngeal nerve i 
 and above the recurrent laryngeal nerve (the region usually attacked) that there would be 
 paralysis of all the muscles of one side of the larynx, except the crico-thyroid, and wide- 
 spread aberration evinced by disturbances of the heart, stomach, and lungs. As a matter of fact,^ * 
 this has not been the case. It might be and probably would be the case, were a healthy nerve 
 divided; but the surgeon who deliberately divides the nerve does so during the removal of a 
 tumor which has long made pressure. In jnost cases there is no change in the pulse orj 
 respiration. In some cases dysphagia and pneumonia arise, but they may be due to other causes 
 than pneumogastric injury (the formidable nature and the duration of the operation — ^thej 
 ligation of vessels of large size — the age of the subject). 
 
 Laryngeal symptoms, to a greater or less degree, are always noted. The difference in the] 
 degree of the palsy is explainable when we recall Exner's statement that the muscles supplied] 
 by the recurrent laryngeal also receive some innervation from the superior laryngeal. In fact,] 
 Mills points out that a portion of the recurrent laryngeal has been resected without completely 
 paralyzing the muscles supposed to be supplied solely by the recurrent laryngeal. The laryngeal ] 
 symptoms result from unilateral laryngeal paralysis, in which there is paralysis of the muscles 1 
 which open the glottis. The voice may be lost or may be hoarse. Usually, after a time, this is, 
 to a great extent, compensated for by the opposite vocal cord, although the voice may alway] 
 remain weak, and the patient will tire easily on talking. If both pneumogastrics were to bej 
 divided death would ensue. 
 
THE ELEVENTH OR SPINAL ACCESSORY NERVE 1063 
 
 THE ELEVENTH OR SPINAL ACCESSORY NERVE (N. ACCESSORIUS) 
 
 (Figs. 683, 684, 685). 
 
 The eleventh or spinal accessory nerve consists of two parts: one the accessory 
 part to the vagus, and the other the spinal portion. 
 
 The Bulbar or Accessory Part of the Spinal Accessory Nerve. 
 
 The bulbar or accessory part is the smaller of the two. It is accessory to the 
 vagus. Its superficial origin (Fig. 683) is by four or five delicate filaments from 
 the side of the medulla, below the roots of the vagus. Its deep origin (Fig. 613) 
 may be traced to a nucleus of gray matter at the back of the medulla, dorso-lateral 
 to the hypo-glossal nucleus, and extending as far down as the intermedio-lateral 
 tract of the spinal cord. It passes outward to the jugular foramen, where it inter- 
 changes fibres with the spinal portion or becomes united to it for a short distance; 
 it is also connected, in the foramen, with the upper ganglion of the vagus by one 
 or two filaments. It then passes through the foramen (Fig. 685) , and becoming 
 again separated from the spinal portion it is continued over the surface of the 
 ganglion of the trunk of the vagus, being adherent to its surface, and is distributed 
 principally to the pharyngeal and superior laryngeal branches of the pneumogastric 
 (Fig. 684) . Through the pharyngeal branch it probably supplies the muscles of 
 the soft palate. Some few filaments from it are continued into the trunk of the 
 vagus below the ganglion, to be distributed with the recurrent laryngeal nerve, 
 and probably also with the cardiac nerves. 
 
 The Spinal Portion of the Spinal Accessory Nerve. 
 
 The spinal portion is firm in texture. Its superficial origin (Fig. 683) is by 
 several filaments or rootlets from the lateral tract of the cord, as low down as 
 the sixth cervical nerve. Its deep origin (Fig. 613) may be traced to the inter- 
 medio-lateral tract of the gray matter of the cord. The rootlets of origin join and 
 form a trunk which ascends in the subdural space between the ligamentum den- 
 ticulatum and the posterior roots of the spinal nerves, enters the skull through the 
 foramen magnum, and is then directed outward to the jugular foramen, through 
 which it passes, lying in the same sheath as the pneumogastric, but separated from 
 it by a fold of the arachnoid. In the jugular foramen it receives one or two 
 filaments from the accessory portion. At its exit from the jugular foramen it 
 passes into the neck and becomes the external branch {ramus externum) (Figs. 634, 
 684, and 685). It passes backward, either in front of- or behind the internal 
 jugular vein, and descends obliquely behind the Digastric and Stylo-hyoid muscles 
 to the upper part of the Sterno-mastoid muscle. It pierces that muscle, and 
 passes obliquely across the posterior triangle, to terminate in the deep surface of 
 the Trapezius muscle. This nerve gives several branches to the Sterno-mastoid 
 muscle during its passage through it, and joins in its substance with branches 
 from the second cervical, which supply the muscle. In the posterior triangle it 
 joins with the second and third cervical nerves, while beneath the Trapezius it 
 forms a sort of plexus with the third and fourth cervical nerves, and from this 
 plexus fibres are distributed to the muscle. 
 
 Surgical Anatomy. — Division of the external branch of the spinal accessory nerve causes 
 paralysis of the Sterno-cleido-mastoid and Trapezius muscles; not absolute paralysis, for these 
 muscles also receive nerves from the cervical plexus. In cases of spasmodic torticollis in which 
 all palliative treatment has failed, division or excision of a portion of the external branch of the 
 spinal accessory nerve has been suggested by Keen. This may be done either along the anterior or 
 posterior border of the Sterno-mastoid muscle. The former operation is performed by making 
 
1064 
 
 THE NERVOUS SYSTEM 
 
 an incision from the apex of the mastoid process, three inches in length, along the anterior border 
 of the Sterno-mastoid muscle. The anterior border of the muscle is defined and pulled back- 
 ward, so as to stretch the nerve, which is then to be sought for beneath the Digastric muscle, 
 about two inches below the apex of the mastoid process. The other operation consists in 
 making an incision along the posterior border of the muscle, so that the centre of the incision 
 corresponds to the middle of this border of the muscle. The superficial structures having been 
 divided and the border of the muscle defined, the nerve is to be sought for as it emerges from 
 the muscle to cross the occipital triangle. When found, it is to be traced upward through the 
 muscle, and a portion of it is excised above the point where it gives off its branches to the Sterno- 
 mastoid. In this operation one of the descending branches of the superficial cervical plexus is 
 liable to be mistaken for the nerve. 
 
 THE TWELFTH OR HYPOGLOSSAL NERVE (N. HYPOGLOSSUS^ 
 
 (Figs. 686, 687). 
 
 The twelfth or hypoglossal nerve is the motor nerve of the tongue. Its super^ 
 ficial origin is by several filaments, from ten to fifteen in number, from the groove 
 
 To Dura-mater 
 
 • To Ganglion on Trunk of Vagua 
 
 To Anterior Belly of Omo-hyoid 
 
 To Stemo-hyoid 
 To Stemo-thyrotd 
 To posterior EclUj of Omo-hyoid 
 
 Fig. 686. — Plan of the hypoglossal nerve. 
 
 between the pyramidal and olivary bodies of the medulla, in a continuous line 
 with the anterior roots of the spinal nerves. Its deep origin can be traced to a 
 nucleus of gray matter (trigonum hypoglossi) on the floor of the fourth ventricle 
 (Fig. 613). 
 
 The filaments of this nerve are collected into two bundles, which perforate the 
 dura mater separately, opposite the anterior condyloid foramen, and unite together 
 after their passage through it. In those cases in which the anterior condyloid 
 
THE TWELFTH OB HYPOGLOSSAL NERVE 
 
 1065 
 
 foramen in the occipital bone is double, these two portions of the nerve are sepa- 
 rated by the small piece of bone which divides the foramen. The nerve descends 
 almost vertically to a point corresponding with the angle of the jaw. It is at first 
 deeply seated beneath the internal carotid artery and internal jugular vein, and is 
 intimately connected with the pneumogastric nerve (Fig. 687) ; it then passes for- 
 ward between the vein and artery, and lower down in the neck becomes superficial 
 below the Digastric muscle. The nerve then loops around the occipital artery, 
 and crosses the external carotid and its lingual branch below the tendon of the 
 Digastric muscle. It passes beneath the tendon of the Digastric, the Stylo-hyoid, 
 and the Mylo-hyoid muscles, lying between the last-named muscle and the Hyo- 
 
 FiG. 687. — Hypoglossal nerve, cervical plexus, and their branches. 
 
 glossus (Fig. 687) , and communicates at the anterior border of the Hyo-glossus 
 with the lingual or gustatory nerve (Fig. 686) ; it is then continued forward in the 
 fibres of the Genio-hyoglossus muscle as far as the tip of the tongue, distributing 
 branches to its muscular substance. 
 
 Branches of Communication (Fig. 686). — The branches of communication are 
 — with the 
 
 Pneumogastric. 
 Sympathetic. 
 
 First and Second Cervical Nerves. 
 Lingual (gustatory). 
 
 The first mentioned takes place close to the exit of the nerve from the skull, 
 numerous filaments passing between the hypoglossal and the ganglion of the trunk 
 
1066 THE NERVOUS SYSTEM 
 
 of the pneuraogastric through the mass of connective tissue which here unites the 
 two nerves. It also communicates with the pharyngeal plexus by a minute filament 
 as it winds around the occipital artery. 
 
 The communication with the sympathetic takes place opposite the atlas vertebra 
 by branches derived from the superior cervical ganglion, and in the same situa- 
 tion the nerve is joined by filaments derived from the loop connecting the first 
 two cervical nerves. 
 
 The communication with the lingual (gustatory) takes place near the anterior 
 border of the Hyo-glossus muscle by numerous filaments which ascend upon it. 
 
 Branches of Distribution (Fig. 686). — The branches of distribution are — the 
 
 Meningeal. Thyro-hyoid. 
 
 Descendens hypoglossi. Muscular. 
 
 Meningeal Branches (Fig. 686). — As the hypoglossal nerve passes through the 
 anterior condyloid foramen it gives off, according to Luschka, several filaments to 
 the dura mater in the posterior fossa of the base of the skull ; these filaments are 
 probably derived from a branch which passes from the first cervical nerve to the 
 hypoglossal nerve. 
 
 The Descendens Hypoglossi (ramus descendens) (Figs. 686 and 687). — The 
 descendens hypoglossi, long called the descendens noni, is a long slender branch, 
 which quits the hypo-glossal where it turns around the occipital artery. It con- 
 sists mainly of fibres which pass to the hypoglossal from the first and second 
 cervical nerves in the above-mentioned communication. It descends in front of 
 or within the sheath of the common carotid artery, giving off a branch to the 
 anterior belly of the Omo-hyoid, and then joins the communicating branches 
 from the second and third cervical nerves, just below the middle of the neck, to 
 form a loop, the ansa hypo-glossi. From the convexity of this loop branches pass 
 to supply the Sterno-hyoid, Sterno-thyroid, and the posterior belly of the Omo- 
 hyoid. According to Arnold, another filament descends in front of the vessels into 
 the chest, and joins the cardiac and phrenic nerves. 
 
 The Thyro-hyoid Branch (ramus thyreohyoideus) (Fig, 686). — The thyro-hyoid 
 is a small branch arising from the hypoglossal near the posterior border of the 
 Hyo-glossus; it passes obliquely across the great cornu of the hyoid bone and 
 supplies the Thyro-hyoid muscle. 
 
 The Muscular Branches (Fig. 686). — The muscular branches are distributed to 
 the Stylo-glossus, Hyo-glossus, Genio-hyoid, and Genio-hyo-glossus muscles. At 
 the under surface of the tongue numerous slender branches (rami linguales) pass 
 upward into the substance of the organ to supply its intrinsic muscles. 
 
 Surgical Anatomy. — A wound in the submaxillary region may injure the hypoglossal nerve 
 and result in motor paralysis of the corresponding half of the tongue. The hypoglossal nerve is 
 an important guide in the operation of ligation of the lingual artery (see page 604i It runs forward 
 on the Hyo-glossus muscle just above the great cornu of the hyoid hone, and forms the upper 
 boundary of the triangular space in which the artery is to be sought for by cutting through the 
 fibres of the Hyo-glossus muscle. 
 
 THE SYMPATHETIC NERVE (SYMPATHICUS) (Fig. 688). 
 
 The sympathetic nervous system consists of (1) a series of ganglia (ganglia trunci 
 sympathici) connected together by a great ganglionic cord, the gangliated cord 
 (truncus sympathicus) , extending from the base of the skull to the coccyx, one 
 gangliated cord on each side of the middle line of the body, partly in front and 
 partly on each side of the vertebral column ; (2) of three great gangliated plexuses 
 (plexus sympathici) or aggregations of nerves and ganglia, situated in front of 
 
THE SYMPATHETIC NERVE 
 
 1067 
 
 the spine in the thoracic, abdominal, 
 and pelvic cavities respectively; (3) of 
 smaller or terminal ganglia, situated in 
 relation with the abdominal viscera ; 
 and (4) of numerous nerve-fibres. These 
 latter are of two kinds : communicating, 
 by which the ganglia communicate with 
 each other and with the cerebro-spinal 
 nerves ; and distributory, supplying the 
 internal viscera and the coats of the 
 blood-vessels. 
 
 Each gangliated cord may be traced 
 upward from the base of the skull 
 into the cranial cavity by an ascending 
 branch, which passes through the caro- 
 tid canal, forms a plexus on the internal 
 carotid artery and in the cavernous 
 sinus (Fig. 692), and communicates 
 with certain cranial nerves (p. 1073). 
 According to some anatomists, the two 
 cords are joined, at their cephalic ex- 
 tremities, by these ascending branches 
 communicating in a small ganglion, 
 the ganglion of Ribes, situated upon the 
 anterior communicating artery. Upon 
 the gangliated cord are ganglia dis- 
 tinguished as cervical, dorsal, lumbar, 
 and sacral, and except in the neck they 
 
 Fig. 688. — The sympathetic ners'e, reduced in size 
 from Byron Robinson's life-size drawing of a dissection 
 made by himself. 
 
 l.-VIII., cervical nerves; 2 a, 2 h,\ c, \ d, brachial 
 plexus; 1, spinal accessory nerve (XI. nerve); 2, hypo- 
 glossal nerve (XII. nerve); 3, vagus nerve (X. nerve); 
 4, descendens nomi nerve; 5, laryngeal nerve; 6, supe- 
 rior cervical ganglion; 7, middle cervical ganglion; 8, 9, 
 inferior cervical ganglion; 10, two superior cardiac 
 nerves; 11, two middle cardiac nerves; 12, two ganglia 
 on 10 and 11; 13, branch connecting the inferior cervi- 
 cal ganglion to phrenic nerve; 14, I. dorsal nerve; 15, 
 left subclavian artery; 16, carotid artery; 17, right sub- 
 clavian artery; 18, Wrisberg's ganglion; 19, a, sym- 
 pathetic branches to the heart; 19, three inferior car- 
 diac nerves. The phrenic nerve in this subject arose 
 from the III., IV., and V. cervical nerves; 20 to 39, 
 lateral chain of sympathetic ganglia; 40, left recurrent 
 laryngeal nerve; 41, superior splanchnic nerve; 42, mid- 
 dle splanchnic nerve; 43, inferior splanchnic nerve; 44, 
 45, aortic branches from the lateral chain of ganglia; 45 
 to 56, intercostal nerve; 57, diaphragmatic ganglion; 
 58, right vagus nerve; 59, left vagus nerve; 60, nerve 
 joining the vagi; 61, coeliac axis; 62, phrenic artery sur- 
 rounded by the phrenic plexus, which is connected 
 with the phrenic ganglion (57); 63. 64, abdominal 
 brain (ganglion coeliacum); 65, renal ganglion, I. L. , 
 ILL., III. L., IV. L., V.L., lumbar nerves; 66, right 
 superior splanchnic nerve; 67, seven nerves passing 
 to the adrenal; 68, rich me.«hwork of nerves surround- 
 ing left renal artery; 69, right renal ganglion; 70, 71, 
 ovarian ganglion; 72, aortic plexus; 73, inferior mesen- 
 teric ganglion; 74, hypogastric plexus; 75, 76, 77, pel- 
 vic brain (cervico-vaginal ganglion). At 75 branches 
 from the pelvis brain are emitted to rectum, vagina, 
 and bladder. At 76 the branches from the II., III., 
 and IV. sacral nerves join the pelvic brain. At 77 the 
 uterine nerves are emitted to supply the uterus; 78, 
 oviducal nerves; 79, uterine nerves; 80, bladder; 81 , 
 vagina; 82, 83, rectum; I. S., II. S., III. S., IV. S., sacral 
 nerves; 84, arteria uterina ovarica. The right lumbar 
 lateral chain is not numbered; 85, nerves to levator ani; 
 //. and Hy., ileo-hypogastric; /?'., ileo-inguinal; Ec, 
 external cutaneous; .4c., anterior crural; Obi., Obtura- 
 tor; G. C, genito-crural; G. S., great sciatic. 
 
1068 THE NERVOUS SYSTEM 
 
 correspond pretty nearly in number to the vertebrae against which they lie. 
 They may be thus arranged: 
 
 Cervical portion .... 3 pairs of ganglia. 
 
 Dorsal " . . . .12 
 
 Lumbar " . . . .4 
 
 Sacral '* . . . 4 or 5 
 
 In the neck they are situated in front of the transverse processes of the verte- 
 brae; in the dorsal region, in front of the heads of the ribs; in the lumbar region, 
 on the sides of the bodies of the vertebrae; and in the sacral region, in front of the 
 sacrum. As the two cords pass into the pelvis they converge and unite together 
 in a single ganglion, the coccygeal ganglion or ganglion impar (ganglion coccygeum 
 impar) placed in front of the coccyx. Each ganglion may be regarded as a dis- 
 tinct centre, and, in addition to its branches of distribution, possesses also branches 
 of communication which communicate with other ganglia and with the cerebro- 
 spinal nerves. 
 
 The branches of communication between the ganglia (Figs. 689 and 690) are 
 composed of gray nerve-fibres (gray rami comm,unicantes) and white nerve-fibres 
 (white rami communicantes) , the latter being continuous with those fibres of the 
 spinal nerves which pass to the ganglia. 
 
 The three great gangliated plexuses (collateral ganglia) are situated in front of 
 the spine in the thoracic, abdominal, and pelvic regions, and are named, respec- 
 tively, the cardiac, the solar or epigastric, and the hsrpogastric plexus. They consist 
 •of collections of nerves and ganglia, the nerves being derived from the gangliated 
 cords and from the cerebro-spinal nerves. They distribute branches to the 
 viscera. 
 
 Smaller or Terminal ganglia are also found lying amidst the nerves, some of them 
 of microscopic size, in certain viscera — as, for instance, in the heart, the stomach, 
 .and the uterus. They serve as additional centres for the origin of nerve-fibres. 
 There are numerous special ganglia connected with the cranial nerves. 
 
 These ganglia have been described in a previous section (see ophthalmic 
 ^ganglion, otic ganglion, spheno-palatine ganglion, and submaxillary ganglion). 
 
 The branches of distribution derived from the gangliated cords, from the pre- 
 vertebral plexuses, and also from the smaller ganglia, are principally destined 
 for the blood-vessels and thoracic and abdominal viscera, supplying the involun- 
 tary muscular fibre of the coats of the vessels and the hollow viscera, and the 
 secreting cells, as well as the muscular coats of the vessels in the glandular viscera. 
 
 Structure of the Sympathetic System.— The svm pathetic system is not, as 
 was so long taught, an independent system. It receives fibres from the cerebro- 
 spinal system and arranges them for distribution to the splanchnic blood-vessels 
 and the viscera. It receives fibres from the viscera and transmits them to the 
 ■cerebro-spinal system, and it transmits fibres by way of the spinal nerves to 
 unstriped muscles, to vessels, and to glands. It is simply an arrangement of spinal 
 nerves to permit of the re-arrangement and transmission of impulses. In order 
 to effect this, the spinal nerves are connected with a series of ganglia, which possess 
 a certain power of government or automatic action. In the sympathetic system 
 non-medullated fibres predominate. The individual nerve-fibres are smaller in 
 diameter than those of the cerebro-spinal system, and the fibres are interrupted 
 by nerve-cells contained in a ganglia chain, known as the gangliated cord, and are 
 also sometimes interrupted in gangliated plexuses and in terminal ganglia. The 
 sympathetic nerves have a notable disposition to form plexuses. It is important to 
 note that not all of the visceral branches of the spinal nerves join the gangliated 
 cord — for instance, the visceral branches of the third and fourth sacral do not. 
 The majority, but not all, of the sympathetic fibres are non-medullated (fibres of 
 
THE SYMPATHETIC NERVE 1069 
 
 Remak), but in the adult true non-medullated fibres are found only in the sym- 
 pathetic system. These fibres are of smaller diameter than spinal nerve-fibres, and 
 are prolongations of axones of sympathetic ganglia cells. Each fibre is surrounded 
 by connective-tissue structure which resembles the neurilemma, which contains 
 numerous nuclei, and which is a prolongation of the capsule of a sympathetic cell 
 capsule. 
 
 A sympathetic nerve consists of numerous non-medullated and some medullated 
 fibres. The connective tissue which separates the nerve-bundles carries blood- 
 vessels and nervi nervorum, but no lymph vessels. 
 
 The sympathetic ganglia contain multipolar cells which are smaller than those 
 of the spinal ganglia. Each cell contains two nuclei, and is surrounded by a deli- 
 cate capsule of connective tissue. The cell gives off one axone and several short 
 
 POSTERIOR ROOT 
 
 POSTERIOR PRIMARY 
 DIVISION 
 
 NTERIOR ROOT\ 
 
 SPLANCHNIC EFFERENT FIBRESi 
 SYMPATHETIC GANGLION 
 
 ANTERIOR PRIMARY 
 DIVISION 
 
 ^SPLANCHNIC AFFERENT FIBRES 
 
 "Fio. 689. — The white ramus communicans (schematic). (After Cunningham.) 
 
 dendrites. The axone is non-medullated when it begins and may remain so or 
 may become medullated. Fibres which take origin from sympathetic axones, 
 the commissural fibre, may pass to an adjacent ganglion cell, may pass toward the 
 centre central fibre or gray ramus commimicans, or may pass toward the periphery, 
 peripheral fibre, and reach certain glands, or to unstriped muscle of blood-vessels, 
 intestines, iris, etc. The fibres passing to glands are called secretory fibres. 
 
 The dendrites of a sympathetic ganglion cell form arborizations about other 
 ganglion cells. The sympathetic ganglia contain fibres, as well as cells. Some of 
 the fibres are medullated and some are non-medullated, the latter taking origin 
 from the sympathetic ganglion cells, the former being motor and sensory cere- 
 brospinal fibres which have reached the sympathetic by the rami communi- 
 cantes.^ 
 
 ' Histology and Microscopic Anatomy, by Szymonowicz. Translated and edited by John Bruce MacCallura. 
 
1070 
 
 THE NERVOUS SYSTEM 
 
 The medullated fibres, the white rami communicantes or the visceral branches of 
 the spinal nerves (Figs. 689 and 690) originate from the anterior divisions of certain 
 spinal nerves. Two groups of them can be recognized, one group coming from 
 the nerves from the first or second dorsal to the second or third lumbar nerves; 
 another group from the second or third lumbar to the third or fourth sacral. The 
 
 COMMISSURAL 
 FIBRE 
 
 aftNSLION CCIXS 
 OU^ AND AX0N3 
 
 Fio. 690. — Scheme of the constitution and connections of the gangliated cord of the sympathetic. The 
 gangliated cord is indicated on the right with the arrangement of the fibres arising from the ganglion cells. _ On 
 the left the roots and trunks of spinal nerves are shown, with the arrangement of the white ramus communicans 
 above and the gray ramus below. (Cunningham.) 
 
 visceral branches of the third and fourth sacral do not join the gangliated cord ; the 
 other visceral branches do join it. The fibres of the visceral branches of the spinal 
 nerves are derived from both the anterior and the posterior nerve-roots, but more 
 largely from the anterior than from the posterior. The visceral fibres of the anterior 
 roots are axones of nerve-cells of the spinal cord, and by way of the white rami enter 
 into the sympathetic ganglia. Some of them end and form networks about the 
 
THE CEBVICAL PORTION OF THE GANGLIATED COBD 1071 
 
 ganglia cells. Others pass up or down and end in an adjacent ganglion. Others 
 pass through a ganglion of the gangliated cord and end in a peripheral ganglion 
 with non-medullated fibres, which take origin from ganglia of the gangliated cord. 
 The fibres of the white ramus which pass through the ganglion and go to the 
 periphery are known as the splanchnic efferent fibres, and constitute the secretory 
 fibres of the splanchnic glands and the motor fibres of the muscular tissue of 
 splanchnic blood-vessels and viscera. The visceral fibres of the posterior nerve- 
 roots aid in the formation of the white rami and arise as axones of nerve-cells in 
 the spinal ganglia on the posterior roots, pass through the ganglia of the sympa- 
 thetic cord, but do not terminate in them, and leave the ganglion directly to pass 
 through a peripheral ganglion to be distributed to the periphery or ascend or 
 descend to an adjacent ganglion and pass through this to a collateral ganglion, and 
 from that to the periphery. They constitute the splanchnic afferent fibres, the 
 sensory fibres of the viscera. 
 
 The non-medullated fibres take origin from the cells of the sympathetic gan- 
 glia and are axones of these cells. Some help to form the commissure, which 
 joins a ganglion to adjacent ganglia and end as networks about the cells of an 
 adjacent ganglion. Others run to the periphery and help to form the splanchnic 
 efferent branches. Some pass from the ganglia to the spinal nerve-roots and to 
 the anterior and posterior divisions of the nerves. The latter are the gray rami 
 communicantes (Fig. 690), largely composed of non-medullated but containing 
 some medullated fibres. They give branches to the somatic part of the nerves 
 and not the visceral, and furnish secretory fibres and fibres to unstriated muscle 
 and minute branches to the membranes which enwrap the nerve-roots. The 
 commissures of the gangliated cord are composed of white and gray fibres. 
 The former consist of both splanchnic efferent and splanchnic afferent fibres. The 
 latter are axones from sympathetic ganglion cells, and some of these are truly com- 
 missural, but others pass up or down the cord and through a ganglion and become 
 branches which go to the periphery. 
 
 From the above it becomes evident that the peripheral branches of the sym- 
 pathetic contain white fibres, which are composed of splanchnic efferent and 
 splanchnic afferent branches and also contain splanchnic efferent gray fibres. 
 Fig. 690, from Cunningham's Text-hook of Anatomy, exhibits the constitution 
 and connections of the gangliated cord of the sympathetic. 
 
 THE GANGLIATED CORD (TRUNCUS SYMPATHICUS). 
 
 The Cervical Portion (Pars Cervicalis) of the Gangliated Cord. 
 
 The cervical portion of the gangliated cord is to be regarded as a prolongation 
 upward of the primitive sympathetic along the great vessels of the neck (Prof. 
 Cunningham). It is not connected to the cervical spinal nerves by white rami 
 communicantes. It obtains its spinal fibres from the upper dorsal nerves. These 
 fibres ascend in the commissure of the gangliated cord and join the cells of the 
 cervical ganglia. From the cervical ganglia come fibres to the unstriped muscle 
 (veins and arteries of the head, neck, and limbs, and to the skin of the head and 
 neck, secretory fibres to the salivary glands and fibres to the heart). The fibres 
 to the vessels are called vasomotor nerves, and the fibres to the heart are called 
 cardio-motor nerves. In the neck the gangliated cord is situated behind the carotid 
 vessels and upon the muscles in front of the vertebrae, and runs from the root 
 of the neck to the base of the skull, being continuous below with the thoracic 
 gangliated cord and ending above in the carotid plexus. There are usually three 
 ganglia on each side, each of which is distinguished, according to its position, as 
 the superior, middle and inferior cervical ganglion. 
 
1072 
 
 THE NERVOUS SYSTEM 
 
 The Superior Cervical Ganglion {ganglion cervicale superius) (Figs. 691, 692, 
 and 693) . — ^^Fhe superior cervical ganglion, the largest of the three, is about three- 
 
 Superior cervical ganglion. 
 
 Middle cervical ganglion. 
 
 Inferior cerdccd ganglion 
 
 Pharyngeal branches. 
 
 Cardiac branches. 
 
 Deep cardiac plexus. 
 
 Superficial cardiac plexus. 
 
 Solar plexus. 
 
 Aortic plexus. 
 
 Hypogastnc plexus. 
 
 Sacral ganglia. 
 
 Ganglion impar 
 
 Fig. 691. — The sympathetic nerve. 
 
THE CERVICAL PORTION OF THE QANGLIATED CORD 1073 
 
 quarters of an inch in length. It is placed opposite the second and third cervical 
 vertebrae. It is of a reddish-gray color, is usually fusiform in shape, is sometimes 
 broad and flattened, and is occasionally constricted at intervals, so as to give rise to 
 the opinion that it consists of the coalescence of several smaller ganglia; and it is 
 usually believed that it is formed by the coalescence of the four ganglia correspond- 
 ing to the four upper cervical nerves. It is in relation, in front, with the sheath 
 of the internal carotid artery and internal jugular vein; behind, it lies on the 
 Rectus capitis anticus major muscle. It is connected to the middle cervical gan- 
 glion by the commissure of the gangliated cord. 
 
 Branches (Fig. 693). — The branches of the superior cervical ganglion are central 
 and peripheral. 
 
 Central or Communicating Branches. — 1. Gray rami communicantes arise in the 
 ganglion and pass to the first, second, third, and fourth cervical nerves. 2. Branches 
 are given off to certain cranial nerves in the neck (Figs. 692 and 693) . What is 
 known as the jugular nerve {n. jugularis) (Fig. 693) passes to the ganglion on the 
 trunk of the vagus, a branch from the ganglion passes to the ganglia on the root of 
 the pneumogastric (Fig. 693) and to the petrosal ganglion of the glosso-pharyngeal 
 (F'ig. 693), and a branch goes to the hypoglossal (Fig. 693). 
 
 Peripheral Branches. — These branches may be divided into superior, internal 
 and anterior. 
 
 The Superior Branch of the Superior Cervical Ganglion or the Internal Carotid 
 Branch (n. caroticus internus) (Fig. 692) appears to be a direct prolongation of the 
 ganglion. It is soft in texture and of a reddish color. It ascends by the side of 
 the internal carotid artery, and, entering the carotid canal in the temporal bone, 
 divides into two branches, which lie, one on the outer, and the other on the inner, 
 side of that vessel. 
 
 The outer branch, the larger of the two, distributes filaments to the internal 
 carotid artery and forms the internal carotid plexus. 
 
 The inner branch also distributes filaments to the internal carotid, and, con- 
 tinuing onward, forms the cavernous plexus. 
 
 The Internal Carotid Plexus (plexus caroticus internus) (Figs. 691, 692, 
 and 693) . — The carotid plexus is situated on the outer side of the internal carotid 
 artery. Filaments from this plexus occasionally form a small gangliform swelling 
 on the under surface of the artery, which is called the carotid ganglion. The internal 
 carotid plexus communicates with the Gasserian ganglion, with the sixth nerve, 
 and the spheno-palatine ganglion, and distributes filaments to the wall of the 
 carotid artery and to the dura mater (Valentin), while in the carotid canal it 
 communicates with Jacobson's nerve, which is the tympanic branch of the glosso- 
 pharyngeal. 
 
 The communicating branches with the sixth nerve (Fig. 693) consist of one or 
 two filaments which join that nerve as it lies upon the outer side of the internal 
 carotid. Other filaments are also connected with the Gasserian ganglion. The 
 communication with the spheno-palatine ganglion is effected by a branch, the 
 large deep petrosal nerve (Fig. 677), which is given off from the plexus on 
 the outer side of the artery, ancl which passes through the cartilage filling up the 
 foramen lacerum medium, and joins the large superficial petrosal from the facial 
 to form the Vidian nerve (Figs. 670, 672, and 677) . The Vidian nerve then pro- 
 ceeds along the pterygoid or Vidian canal to the spheno-palatine ganglion. The 
 commimication with Jacobson's nerve is effected by two branches, one of which 
 is called the deep petrosal nerve, and the other the carotico-tympanic nerve; the 
 latter may consist of two or three delicate filaments. 
 
 The Cavernous Plexus (plexus cavernosus) (Figs. 692 and 693). — The cavern- 
 ous plexus is situated below and internal to that part of the internal carotid which is 
 placed by the side of the sella turcica in the cavernous sinus, and is formed chiefiy 
 
 68 
 
1074 
 
 THE NERVOUS SYSTEM 
 
 by the internal division of the ascending branch from the superior cervical ganglion. 
 It communicates with the third, the fourth, the ophthalmic division of the fifth, 
 and the sixth nerves, and with the ophthalmic ganghon, and distributes filaments 
 to the wall of the internal carotid and to the pituitary body. The branch of com- 
 munication with the third nerve (Fig. 693) joins it at its point of division; the 
 branch to the fourth nerve (Fig. 693) joins it as it lies on the outer wall of the 
 cavernous sinus; other filaments are connected with the under surface of the trunk 
 of the ophthalmic nerve; and a second filament of communication joins the sixth 
 nerve (Fig. 693). 
 
 The filament of connection with the ophthalmic ganglion (Figs. 666 and 693) 
 arises from the anterior part of the cavernous plexus; it accompanies the nasal 
 nerve or continues forward as a separate branch. 
 
 EXTERNAL 
 RECTUS 
 
 MUSCLE 
 
 OPHTHALMIC 
 GANGLION 
 
 SENSORY ROOT 
 
 OF OPHTHALMIC 
 
 GANGLION 
 
 OPHTHALMIC 
 
 GASSERIAN 
 GANGLION 
 
 [turned forward) 
 
 GREAT DEEP 
 PETROSAL 
 
 TEMPORO- 
 
 MAXILLARY 
 
 ARTICULATION 
 
 SMALL DEEP 
 PETROSAL 
 
 MOTOR ROOT OF 
 
 OPHTHALMIC GANGLION 
 
 UPPER BRANCH 
 
 OF THIRD 
 
 LOWER BRANCH 
 
 OF THIRD 
 
 SYMPATHETIC ROOT OF 
 OPHTHALMIC GANGLION 
 THIRD NERVE 
 
 OPHTHALMIC 
 ARTERY 
 
 PITUITARY 
 f BODY 
 
 CAVERNOUS 
 PLEXUS 
 
 SIXTH NERVE 
 
 COMMUNICATING 
 BRANCH TO SIXTH 
 
 INFERIOR INTERNAL 
 COROTICOTYMPANIC CAROTID 
 
 ARTERY 
 
 INTERNAL 
 CAROTID PLEXUS 
 NTERNAL 
 CAROTID BRANCH 
 OF SUPERIOR 
 CERVICAL GANGLION 
 SUPERIOR 
 CERVICAL 
 GANGLION 
 
 Fig. 692. — The cephalic portion of the sympathetic nervous system, seen obliquely from above and behind. 
 
 (Toldt.) 
 
 Terminal Branches of the Carotid and Cavernous Plexuses. — The terminal 
 filaments from the carotid and cavernous plexuses are prolonged along the internal 
 carotid, forming plexuses which entwine around the cerebral and ophthalmic 
 arteries; along the former vessels they may be traced on to the pia mater; along 
 the latter, into the orbit, where they accompany each of the subdivisions of the 
 vessel, a separate plexus passing, with the arteria centralis retinae, into the interior 
 of the eyeball. The filaments prolonged on to the anterior communicating artery 
 form a small ganglion, the ganglion of Ribes,* which serves, as mentioned above, 
 to connect the sympathetic nerves of the right and left sides. 
 
 The so-called Inferior or Descending Branch of the Superior Cervical Ganglion 
 communicates with the middle cervical ganglion. It is the commissure of the 
 gangliated cord. 
 
 ^ The existence of this ganglion is doubted by some observers. — Ed. of 15th English edition. 
 
THE CERVICAL PORTION OF THE GANGLIATED CORD 1075 
 
 Fig. 693. — Plan of the cervical portion of the sympathetic. (After Flower.) 
 
1076 
 
 THE NERVOUS SYSTEM 
 
 The Internal Branches of the Superior Cervical Ganglion are three in number — the 
 pharyngeal, laryngeal and superior cardiac nerve. 
 
 The pharyngeal branches (rami pharyngei) (Figs. 691 and 693) pass inward to the 
 side of the pharynx, where they join with branches from the glosso-pharyngeal, 
 pneumogastric, and external laryngeal nerves to form the pharjmgeal plexus 
 (plexus pharyngeuLs). 
 The laryngeal branches unite with the superior laryngeal nerve and its branches. 
 The superior cardiac nerve or the nervus superficialis cordis {n. cardiacus supe- 
 rior) (Figs. 691 and 693) arises by two or more branches from the superior cervical 
 ganglion, and occasionally receives a filament from the cord of communication 
 between the first and second cervical ganglia. It runs down the neck behind the 
 common carotid artery, lying upon the Longus colli muscle, and crosses in front of 
 the inferior thyroid artery and recurrent laryngeal nerve. The right superior cardiac 
 nerve, at the root of the neck, passes either in front of or behind the subclavian 
 artery, and along the arteria innominata, to the back part of the arch of the aorta, 
 where it joins the deep cardiac plexus. This nerve, in its course, is connected with 
 other branches of the sympathetic; about the middle of the neck it receives fila- 
 ments from the external laryngeal nerve; lower down it obtains one or two twigs 
 from the pneumogastric; and as it enters the thorax it is joined by a filament 
 from the recurrent laryngeal. L'ilaments from thig nerve communicate with the 
 thyroid branches from the middle cervical ganglion. The left superior cardiac 
 nerve, in the chest, runs by the side of the left common carotid artery and in 
 front of the arch of the aorta to the superficial cardiac plexus, but occasionally it 
 passes behind the aorta and terminates in the deep cardiac plexus. 
 
 The Anterior Branches of the Superior Cervical Ganglion {nn. carotid extcrni) 
 (Fig. 693) ramify upon the external carotid artery and its branches, forming around 
 each a delicate plexus, on the nerves composing which small ganglia are occasion- 
 ally found. The plexuses accompanying some of these arteries have important 
 communications with other nerves. That suiTounding the external carotid artery 
 {plexus caroticus eodernus) is connected with the branch of the facial nerve to the 
 
 Stylo-hyoid muscle ; that surrounding the 
 facial artery communicates with the sub- 
 maxillary ganglion by one or two filaments; 
 and that accompanying the middle menin- 
 geal artery sends offsets which pass to the 
 otic ganglion and to the geniculate gan- 
 glion of the facial nerve and constitute the 
 external superficial petrosal nerve (Fig. 677). 
 The Middle Cervical or Thyroid Gan- 
 glion {ganglion cervical medium) (Figs. 391 
 and 693). — The middle cervical or thyroid 
 ganglion is the smallest of the three cervical 
 ganglia, and is occasionally altogether want- 
 ing. It varies somewhat in position, but in 
 most individuals is placed opposite the sixth cervical vertebra, usually upon, or 
 close to, the inferior thyroid artery; hence the name, thyroid ganglion, assigned to 
 it by Haller. It is probably formed by the coalescence of two ganglia corre- 
 sponding to the fifth and sixth cervical nerves. 
 
 It communicates above with the superior cervical ganglion and below with 
 the inferior cervical ganglion by means of the commissure of the gangliated cord. 
 The Central Communicating Branches (Fig. 693). — The central communicating 
 branches are: 1. Gray rami communicantes passing from the ganglion to the 
 anterior divisions of the fifth and sixth cervical nerves. 2. The subclavian loop or 
 the ansa of Vieussens {ansa suhclavia) (Fig. 694) arises from the ganglion, passes 
 
 MIDDLE CERVICAL GANGLION 
 
 SUBCLAVIAN LOOP 
 
 INFERIOR CERVICAL 
 GANGLION 
 
 Fig. 694. — The subclavian loop passing from the 
 middle to the inferior cervical ganglia. 
 
THE CERVICAL PORTION OF THE GANGLIATED CORD 1077 
 
 down over the front and under the subclavian artery and runs back to join the 
 inferior cervical ganglion. It gives branches to the artery. In some cases this 
 nerve takes origin from the sympathetic trunk below the ganglion. 
 
 The Peripheral Branches. — The peripheral branches are the thyroid and the 
 middle cardiac nerve. 
 
 I'he Thyroid Branches (Fig. 693) are small filaments which accompany the in- 
 ferior thyroid artery to the thyroid gland, forming the inferior thyroid plexus 
 {plexus thyreoideus mferior) ; they communicate, on the artesy, with the superior 
 cardiac nerve, and, in the gland, with branches from the recurrent and external 
 laryngeal nerves. 
 
 The Middle or Great Cardiac Nerve (n. cardiacus niedius) (Figs. 691 and 693), the 
 largest of the three cardiac nerves, arises from the middle cervical ganglion or from 
 the cord between the middle and inferior ganglia. On the right side it descends 
 behind the common carotid artery, and at the root of the neck passes either in 
 front of or behind the subclavian artery; it then descends on the trachea, receives 
 a few filaments from the recurrent laryngeal nerve, and joins the right side of the 
 deep cardiac plexus. In the neck it communicates with the superior cardiac and 
 recurrent laryngeal nerves. On the left side the middle cardiac nerve enters the 
 chest between the left carotid and subclavian arteries, and joins the left side of 
 the deep cardiac plexus. If the middle cervical ganglion is absent, the above- 
 named branches arise from the gangliated cord. 
 
 The Inferior Cervical Ganglion (ganglion cervicale inferius)(Figs. 691 and 693). 
 — The inferior cervical ganglion is situated between the base of the transvetse pro- 
 cess of the last cervical vertebra and the neck of the first rib on the inner side 
 of the superior intercostal artery. Its form is irregular; it is larger in size than the 
 preceding, and is frequently joined with the first thoracic ganglion. It is prob- 
 ably formed by the coalescence of two ganglia which correspond to the two last 
 cervical nerves. It joins the middle ganglion above and the first thoracic ganglion 
 below by the commissural cord, and is usually also joined to the middle ganglion 
 by the subclavian loop. 
 
 The Central Communicating Branches. — Its central communicating branches are: 
 1. Gray rami communicantes passing to the anterior divisions of the seventh and 
 eighth cervical nerves (Fig. 693) . 2. The subclavian loop (Fig. 694) , which has 
 been previously described and which passes under and in front of the subclavian 
 artery to reach the middle cervical ganglion or the commissural cord. 
 
 The Peripheral Branches. — The peripheral branches are: 1. Vascular. The 
 vertebral plexus (plexus vertebralis) (Fig. 693) lies upon the vertebral artery and its 
 branches in the neck and in the cranial cavity. The subclavian plexus (plexus 
 subclavius) (Fig. 693) arises from the subclavian loop, which may be regarded as 
 a branch of the inferior or of the middle ganglion. 2. Cardiac. The inferior or 
 minor cardiac nerve (n. cardiacus inferior) (Fig. 693) arises from the inferior cervical 
 or first thoracic ganglion. It passes down behind the subclavian artery and along 
 the front of the trachea to join the deep cardiac plexus. It communicates freely 
 behind the subclavian artery with the recurrent laryngeal and middle cardiac nerves. 
 
 Surgical Anatomy. — The situation of the cervical sympathetic makes wounds of it rare. 
 Thirteen cases of sympathetic traumatic injury were collected by Seeligmiiller. In ten cases 
 paralysis existed; in three, irritation. Tumors of the neck may cause irritation or paralysis. In 
 irritation of the sympathetic the corresponding side of the face becomes pale, the pupil dilates, 
 the palpebral fissure widens, and the eyeball protrudes. In many cases there is acceleration 
 of the heart beats. In paralysis of the sympathetic the pupil contracts, the palpebral fissure is 
 narrowed by partial ptosis, the corresponding side of the face reddens, there is an increase in 
 the flow of tears, and recession of the eyeball. 
 
 The surgeon occasionally resects the sympathetic. Jonnesco recommends bilateral removal 
 of the superior cervical ganglia for glaucoma, and bilateral removal of all the cervical sympa- 
 thetic ganglia for epilepsy and for exophthalmic goitre. 
 
1078 
 
 THE NERVOUS SYSTEM 
 
 The Thoracic Portion (Pars Thoracalis) of the Gangliated Cord (Fig. 695). 
 
 The thoracic portion of the ganghated cord consists of a series of gangha 
 which usually correspond in number to that of the vertebrae, but, from the occa- 
 sional coalescence of two, their number is uncertain. These ganglia are placed 
 on each side of the spine, resting against the heads of the ribs, and are covered by 
 
 THORACIC NERVES. 
 RAMI COMMUNICANTES' 
 
 INFERIOR CER- 
 VICAL GANGLION 
 
 VISCERAL 
 BRANCHES 
 
 SPLANCHNIC 
 
 GANGLION 
 
 GREAT 
 
 SPLANCHNIC 
 
 SMALL 
 SPLANCHNIC 
 
 RIGHT PNEU- 
 MOGASTRIC 
 
 SMALL 
 SPLANCHNIC 
 
 BRANCH OF PNEUMOaASTRIO 
 TO SEMILUNAR GANGLION 
 
 CELIAC AXIS 
 
 SEMILUNAR GANGLION 
 SUPERIOR MESENTERIC 
 ARTERY AND PLEXUS 
 
 LAR PLEXUS 
 
 QUADRATUS, 
 LUMBORUM 
 
 RENAL PLEXUS 
 
 Fig. 695. — Plan of the right sympathetic cord and splanchnic nerves. (Testut.) 
 
 the pleura costalis; the last two ganglia are, however, anterior to the rest, being 
 placed on the side of the bodies of the eleventh and twelfth dorsal vertebrae. The 
 ganglia are small in size and of a grayish color. The first ganglion, larger than 
 the rest, is of an elongated form and is frequently blended with the last cervical 
 ganglion. They are connected together by cord-like prolongations from the sub- 
 stance. In the thorax each thoracic or dorsal spinal nerve, with occasionally the 
 exception of the first, sends a visceral branch or white ramus communicans to the 
 thoracic gangliated cord (Figs. 693 and 695) . As Prof. Cunningham points out, 
 
THE LUMBAR PORTION OF THE GANGLIATED CORD 1079 
 
 the white rami "separate into two main streams in relation to the sympathetic 
 cord. Those of the upper five nerves are, for the most part, directed upward in 
 the ganghated cord to be distributed through the cervical part of the sympathetic 
 in the manner already described. The white rami of the lower thoracic nerves 
 are, for the most part, directed downward in the lower part of the sympathetic 
 cord, and its branches, to be distributed to the abdomen; at the same time some 
 of their fibres are directly associated with the supply of certain thoracic viscera — 
 lungs, aorta, oesophagus.'" The white rami are composed of splanchnic afferent 
 fibres and somatic and splanchnic efferent fibres. 
 
 Central Communicating Branches. — 1. White rami communicantes (see above). 
 
 2. Gray rami commmiicantes arise from each one of the thoracic ganglia, pass back- 
 ward with the white rami, and enter into the anterior divisions of the thoracic nerves. 
 
 Peripheral Branches (Fig. 693). — 1. Aortic Branches (Fig. 693) come off from the 
 first five or six upper ganglia. They send filaments to the aorta and its branches, 
 to the vertebral bodies, and to the vertebral ligaments. The aortic branches help 
 to form the thoracic aortic plexus (plexus aorticus thoracalis) . This plexus is com- 
 pleted by branches from the cardiac plexus. 
 
 2. Pulmonary Branches (Fig. 693) come off from the third and fourth and some- 
 times from the first and second ganglia. 
 
 3. The Splanchnic Nerves (Figs. 688, 691, and 695). — From the six or seven lower 
 ganglia and from the commissural cord a number of large white branches arise. 
 They give filaments to the aorta and unite to form the three splanchnic nerves on 
 each side. These are namefl the great, the lesser, and the smallest or renal splanchnic. 
 
 The superior or great splanchnic nerve (n. splanchnicus major) is of a white 
 color, firm in texture, and presents a marked contrast to the ganglionic nerves. 
 It is formed by branches from the thoracic ganglia between the fifth or sixth 
 and the ninth or tenth, but the fibres in the higher roots may be traced upward 
 in the sympathetic cord as far as the first or second thoracic ganglion. These 
 roots unite to form a large round cord of considerable size. It descends obliquely 
 inward in front of the bodies of the vertebrae along the posterior mediastinum, 
 perforates the crus of the Diaphragm, and terminates in the semilunar ganglion of 
 the solar plexus (Fig. 695), distributing filaments to the renal and suprarenal plexus. 
 
 The middle, lesser or small splanchnic nerve (n. splanchnicus minor) is formed 
 by filaments from the tenth and eleventh ganglia, and from the cord betweer^ them. 
 It pierces the Diaphragm with the preceding nerve, and joins the solar plexus 
 (Fig. 695). It communicates in the chest with the great splanchnic nerve, and 
 occasionally sends filaments to the renal plexus. 
 
 The inferior, smallest, least or renal splanchnic nerve (n. splanchnicus imus) arises 
 from the last thoracic ganglion, and, piercing the Diaphragm, terminates in the 
 renal plexus and lower part of the solar plexus. It occasionally communicates with 
 the preceding nerve (Fig. 688). 
 
 A striking analogy appears to exist between the splanchnic and the cardiac 
 nerves. The cardiac nerves are three in number; they arise from the three cer- 
 vical ganglia, and are distributed to a large and important organ in the thoracic 
 cavity. The splanchnic nerves, also three in number, are connected probably 
 with all the dorsal ganglia, and are distributed to important organs in the abdom- 
 inal cavity. 
 
 The Lumbar Portion (Pars Lumbalis) of the Gangliated Cord (Figs. 688, 691). 
 
 The lumbar portion of the gangliated cord is situated in front of the vertebral 
 column along the inner margin of the Psoas muscle. It consists usually of hnr 
 
 ' Text-book of Anatomy. 
 
X080 ^^^ NERVOUS SYSTEM 
 
 ganglia, but there may be as many as eight, connected together by intergangHonic 
 cords. The gangha are of small size, of a grayish color, shaped like a barleycorn, 
 and placed much nearer the median line than the thoracic ganglia. Sometimes 
 several ganglia are fused together. 
 
 It is connected with the thoracic portion by a thin commissure, which passes 
 back of or through the Diaphragm. It is connected with the sacral portion by 
 a commissure which is under the connnon iliac artery. 
 
 The upper lumbar ganglia or the upper portion of the gangliated cord receives 
 white rami communicantes from the first two or three lumbar spinal nerves. 
 
 Central Communicating Branches. — Gray rami communicantes pass irregularly from 
 the gangliated cord to the anterior divisions of the lumbar spinal nerves, the gray 
 rami accompanying the white rami. 
 
 From the situation of the lumbar ganglia these branches are longer than in the 
 other regions. They are usually two in number from each ganglion, but their 
 connection with the spinal nerves is not so uniform as in other regions. They 
 accompany the lumbar arteries around the sides of the bodies of the vertebrae, 
 passing beneath the fibrous arches from which some of the fibres of the Psoas 
 muscle arise. 
 
 Peripheral Branches. — Some branches pass inward, in front of the aorta, and 
 help to form the abdominal aortic plexus {plexus aorticus ahdominalis) (Fig. 691), 
 which plexus is, however, developed chiefly by filaments from the coeliac plexus. 
 Other branches descend in front of the common iliac arteries, and join over the 
 promontory of the sacrum, helping to form the h3rpogastric plexus {'plexus hypo- 
 gastricus) (Fig. 691). Numerous delicate filaments are also distributed to the 
 bodies of the vertebrae and the ligaments connecting them. 
 
 Pelvic or Sacral Portion (Pars Sacralis) of the Gangliated Cord (Figs. 688, 691). 
 
 The pelvic portion of the gangliated cord is situated in front of the sacrum 
 along the inner side of the anterior sacral foramina. It consists of four or five 
 small ganglia on each side, connected together by interganglionic cords. Below,, 
 these cords converge and unite on the front of the coccyx by means of a small 
 ganglion, the coccygeal ganglion or ganglion impar {ganglion coccygeum impar} 
 (Fig. 691) . The commissural cord joins the pelvic portion to the lumbar portion 
 of the gangliated cord. Like the cervical portion and the lower lumbar portion 
 the sacral portion receives no white rami communicantes. 
 
 The visceral branches of the third sacral, and usually of the second and fourth 
 sacral spinal nerves, are not connected with the ganglionic cord. 
 
 Central Communicating Branches. — Gray rami communicantes, which arise in the 
 sacral ganglia and pass to the anterior divisions of the sacral and coccygeal nerves. 
 
 Peripheral Branches. — 1. Visceral branches arise from the upper portion of the 
 gangliated cord and pass to the pelvic plexus. • 
 
 2. Parietal branches communicate, on the front of the sacrum, with the correspond- 
 ing branches from the opposite side; some, from the first two ganglia, pass to join 
 the pelvic plexus, and others form a plexus which a,ccompanies the middle sacral 
 artery and sends filaments to the coccygeal gland. 
 
 THE GREAT PLEXUSES OF THE SYMPATHETIC (Fig. 688). 
 
 The great plexuses of the sympathetic are the large aggregations of nerves, 
 and ganglia, previously alluded to, situated in the thoracic, abdominal, and pelvic 
 cavities respectively. From them are derived the branches which supply the 
 viscera. 
 
THE PULMONARY PLEXUS 1081 
 
 The Cardiac Plexus (Plexus Cardiacus) (Figs. 688, 691). 
 
 The cardiac plexus is situated at the base of the heart, and is divided into a 
 superficial paxt, which Kes in the concavity of the arch of the aorta, and a deep 
 paxt, which lies between the trachea and aorta. The two plexuses are, however, 
 closely connected. 
 
 The Great or Deep Cardiac Plexus. — The great or deep cardiac plexus, 
 the plexus magnus profundus of Scarpa, is situated in front of the trachea at its 
 bifurcation, above the point of division of the pulmonary artery and behind the 
 arch of the aorta. It is formed by the cardiac nerves derived from the cervical 
 ganglia of the sympathetic and the cardiac branches of the recurrent laryngeal 
 and pneumogastric. The only cardiac nerves which do not enter into the forma- 
 tion of this plexus are the left superior cardiac nerve and the inferior cervical 
 cardiac branch from the left pneumogastric. 
 
 The branches from the right side of this plexus pass, some in front of, and 
 others behind, the right pulmonary artery; the former, the more numerous, trans- 
 mit a few filaments to the anterior pulmonary plexus, and are then continued 
 onward to form part of the left or anterior coronary plexus ; those behind the pul- 
 monary artery distribute a few filaments to the right auricle, and are then con- 
 tinued onward to form a part of the right or posterior coronary plexus. 
 
 The branches from the left side of the deep cardiac plexus distribute a few 
 filaments to the superficial cardiac plexus, to the left auricle of the heart, and to 
 the anterior pulmonary plexus, and then pass on to form the greater part of the 
 posterior coronary plexus. 
 
 The Anterior or Left Coronary Plexus {plexus coronarius cordis anterior).— The 
 anterior or left coronary plexus is formed chiefly from the superficial cardiac 
 plexus, but receives filaments from the deep cardiac plexus. Passing forward 
 between the aorta and pulmonary artery, it accompanies the left coronary artery 
 on the anterior surface of the heart. 
 
 The Posterior or Right Coronary Plexus (plexus coronarius cordis posterior). — 
 The posterior or right coronary plexus is chiefly formed by filaments prolonged 
 from the left side of the deep cardiac plexus, and by a few from the right side. 
 It surrounds the branches of the coronary artery at the back of the heart, and 
 its filaments are distributed with those vessels to the muscular substance of the 
 ventricles. 
 
 The Superficial or AnteriorCardiac Plexus. — The superficial or anterior cardiac 
 plexus lies beneath the arch of the aorta, in front of the right pulmonary artery. It 
 is formed by the left superior cardiac nerve, the left (and occasionally also the right) 
 inferior cervical cardiac branches of the pneumogastric, and filaments from the 
 deep cardiac plexus. A small ganglion, the cardias ganglion of Wrisberg (ganglion 
 cardiacum [Wrishergi]) is occasionally foimd connected with these nerves at their 
 point of junction. This ganglion, when present, is situated immediately beneath 
 the arch of the aorta, on the right side of the ductus arteriosus. The superficial 
 cardiac plexus forms the chief part of the anterior coronary plexus, and several 
 filaments pass along the pulmonary artery to the left anterior pulmonary plexus. 
 
 Valentin has described nervous filaments ramifying under the endocardium; 
 and Remak has found, in several mammalia, numerous small ganglia on the car- 
 diac nerves, both on the surface of the heart and in its muscular substance. 
 
 The Pulmonary Plexus (Plexus Pulmonalis). 
 
 The larger posterior pulmonary plexus is situated back of the root of the lung. 
 It is formed by the pneumogastric nerve and branches from the second, third, and 
 fourth thoracic sympathetic ganglia. It sends branches along the bronchi and 
 
1082 
 
 2HE NERVOUS SYSTEM 
 
 blood-vessels into the lung and some fibres pass to the front of the root of the 
 lung to form the anterior pulmonary plexus. 1'he smaller anterior pulmonaxy 
 plexus is in front of and above the root of the lung. It is formed on each side by 
 the fibres from the posterior pulmonary plexus. '^I'he left plexus receives branches 
 from the superficial cardiac plexus. The anterior plexus supplies the structures 
 of the root of the lung. 
 
 The Oesophageal Plexus (Plexus Oesophageus). 
 
 The oesophageal plexus is in the posterior mediastiimm and surrounds the 
 oesophagus. It is formed by the pneumogastric nerves which have come from 
 
 SOLAR LEFT 
 PLEXUS PNEUMOGASTRIC 
 
 HEPATIC 
 PLEXUS 
 
 COMMON 
 BILE-DUCT 
 
 SUPERIOR 
 
 MESENTERIC 
 
 PLEXUS 
 
 ABDOMINAL 
 
 AORTIC 
 
 PLEXUS 
 
 SUPRARENAL 
 PLEXUS 
 
 GREAT 
 SPLANCHNIC 
 
 SEMILUNAR 
 GANGLION 
 
 SUPERIOR 
 
 MESENTERIC 
 
 GANGLION 
 
 SPERMATIC 
 PLEXUS 
 
 LUMBAR 
 GANGLIA 
 
 INFERIOR 
 
 MESENTERIC 
 
 PLEXUS 
 
 Fig. 
 
 The semilunar ganglia with the sympathetic plexuses of the abdominal viscera radiating from 
 the ganglia. (Toldt.) 
 
 the posterior pulmonary plexuses, and by fibres from the great splanchnic nerve 
 and ganglion. The oesophageal plexus is usually considered as a portion of the 
 pneumogastric nerve (p. 1061). 
 
THE EPIGASTRIC OB SOLAR PLEXUS 
 
 1083 
 
 The Epigastric or Solar Plexus (Plexus Coeliacum) (Figs. 688, 691, 696, 697). 
 
 The epigastric or solar plexus supplies all the viscera in the abdominal cavity. 
 It consists of a great network of nerves and ganglia, situated behind the pancreas 
 
 Diaphragmatic ganglion 
 Suprarenal capsule. 
 
 Great 
 
 splanchni 
 nerve. 
 
 Right 
 semilunar 
 ganglion. 
 
 Renal ganglion 
 Small splanchnic nerve. 
 
 Hepatic 
 
 Renal artery. 
 Gangliaied cord. 
 
 Communicating branch. 
 
 ■Left semilunar ganglion. 
 Superior mesenteric artery. 
 Great splanchnic nerve. 
 Small splanchnic nerve. 
 
 Renal ganglion. 
 
 Renal artery. 
 Supenor mesenteric ganglion. 
 
 Branch to aortic plexus. 
 
 Branch to aortic plexus. — 
 
 Gangliated cord of 
 sympathetic. 
 
 Inferior mesenteric artery. 
 
 Inferior myenteric ganglion. 
 
 Sacra-vertebral angle. 
 Common iliac vein. 
 Common iliac artery. 
 
 Fig. 697. — Lumbar portion of the gangliated cord, with the solar and hypogastric plexuses. (After Henle.) 
 
1084 THE NERVOUS SYSTEM 
 
 and the lesser peritoneal cavity and in front of the aorta and crura of the Dia- 
 phragm. It surrounds the coeliac axis and root of the superior mesenteric artery, 
 extending downward as low as the pancreas and outward to the suprarenal cap- 
 sules. This plexus, and the ganglia connected with it, receive the great, the small 
 and the least splanchnic nerves of both sides, and some filaments from the right 
 pneumogastric nerve. It distributes filaments which accompany, under the name 
 of plexuses, all the branches from the front of the abdominal aorta. 
 
 Of the ganglia of which the solar plexus is partly composed the principal are 
 the two semilunar ganglia {ganglia coeliaca) (Figs. 688, 696, and 697), which are 
 situated one on each side of the plexus, and are the largest ganglia in the body. 
 They are large, irregular, gangliform masses formed by the aggregation of smaller 
 ganglia, having interspaces between them. They are situated in front of the 
 crura of the Diaphragm, close to the suprarenal capsules: the one on the right 
 side lies beneath the inferior vena cava; the upper part of each ganglion is joined 
 by the greater splanchnic nerve, and to the inner side of each the branches of the 
 solar plexus are connected. 
 
 From the epigastric or solar plexus are derived the following: 
 
 Phrenic or Diaphragmatic plexus. C Gastric plexus. 
 
 Suprarenal plexus. Cceliac plexus < Splenic plexus. 
 
 Renal plexus. ( Hepatic plexus. 
 
 Spermatic plexus. Superior mesenteric plexus. 
 
 Aortic plexus. 
 
 The Phrenic Plexus (plexus phrenicus) (Fig. 696). — The phrenic plexus accom- 
 panies the phrenic artery to the Diaphragm, which it supplies, some filaments 
 passing to the suprarenal capsule. It arises from the upper part of the semilunar 
 ganglion, and is larger on the right than on the left side. It receives one or two 
 branches from the phrenic nerve. In connection with this plexus, on the right 
 side, at its point of junction with the phrenic nerve, is a small ganglion, the 
 diaphragmatic or phrenic ganglion (ganglion phrenicum) (Fig. 697) . This ganglion 
 is placed on the under surface of the Diaphragm, near the right suprarenal capsule. 
 Its branches are distributed to the inferior vena cava, suprarenal capsule, and 
 hepatic plexus. There is no ganglion on the left side. 
 
 The Suprarenal Plexus (plexus suprarenalis) (Fig. 696) . — The suprarenal plexus 
 is formed by branches from the solar plexus, from the semilunar ganglion, and 
 from the phrenic and great splanchnic nerves, a ganglion being formed at the 
 point of junction of the latter nerve. It supplies the suprarenal capsule. The 
 branches of this plexus are remarkable for their large size in comparison with 
 the size of the organ they supply. 
 
 The Renal Plexus (plexus renalis) (Figs. 696 and 697). — The renal plexus is 
 formed by filaments from the solar plexus, the outer part of the semilunar 
 ganglion, and the aortic plexus. It is also joined by filaments from the lesser and 
 smallest splanchnic nerves. The nerves from these sources, fifteen or twenty in num- 
 ber, have numerous ganglia developed upon them. They accompany the branches 
 of the renal artery into the kidney, some filamentson the right side being distributed 
 to the inferior vena cava, and others, on both sides, to the spermatic plexuses. 
 
 The Spermatic Plexus (plexus spermaticus) (Fig. 696). — ^The spermatic plexus 
 is derived from the renal plexus, receiving branches from the aortic plexus. It 
 accompanies the spermatic vessels to the testes. 
 
 The Ovarian Plexus ('plexus arteriae ovaricae). — In the female the ovarian plexus 
 is distributed to the ovaries and fundus of the uterus. 
 
 The Coeliac Plexus (plexus coeliacus). — The coeliac plexus, of large size, is a 
 direct continuation frorn the solar plexus; it surrounds the coeliac axis and sub- 
 divides into the gastric, hepatic, and splenic plexuses. It receives branches from 
 
THE HYPOGASTRIC PLEXUS 1085 
 
 the lesser splanchnic nerves, and, on the left side, a filament from the right pneu- 
 mogastric. 
 
 The Gastric or Coronary Plexus (plexus gastricus superior) (Fig. 696) accompanies 
 the gastric artery along the lesser curvature of the stomach, and joins with branches 
 from the left pneumogastric nerve. It is distributed to the stomach. 
 
 The Splenic Plexus (plexus lienalis) (Fig. 696) is formed by branches from the 
 coeliac plexus, the left semilunar ganglion, and from the right pneumogastric 
 nerve. It accompanies the splenic artery and its branches to the substance of 
 the spleen, giving off, in its course, filaments to the pancreas, the pancreatic plexus, 
 and the left gastro-epiploic plexus, which accompanies the gastio-epiploica sinistra 
 artery along the convex border of the stomach. 
 
 The Hepatic Plexus (plexus hepaticus) (Fig. 696), the largest offset from the 
 coeliac plexus, receives filaments from the left pneumogastric and right phrenic 
 nerves. It accompanies the hepatic artery, ramifying in the substance of the liver 
 upon its branches and upon those of the vena portae. 
 
 Branches from this plexus accompany all the divisions of the hepatic artery. 
 Thus there is a pyloric plexus accompanying the pyloric branch of the hepatic, 
 which joins with the gastric plexus and pneumogastric nerves. There is also a 
 gastro-duodenal plexus, which subdivides into the pancreatico-duodendal plexus, 
 which accompanies the pancreatico-duodenal artery, to supply the pancreas and 
 duodenum, joining with branches from the mesenteric plexus. The gastro-epi- 
 ploic plexus, which accompanies the right gastro-epiploic artery along the greater 
 curvature of the stomach, and which is said to anastomose with branches from 
 the splenic plexus, is in reality derived from the splenic plexus. A cystic plexus, 
 which supplies the gall-bladder, also arises from the hepatic plexus near the liver. 
 
 The Superior Mesenteric Plexus (plexus rnesentericv^ superior) (Fig. 696) . — The 
 superior mesenteric plexus is a continuation of the lower part of the great solar 
 plexus, receiving a branch from the junction of the right pneumogastric nerve with 
 the coeliac plexus. It surrounds the superior mesenteric artery, which it accom- 
 panies into the mesentery, and divides into a number of secondary plexuses, which 
 are distributed to all the parts supplied by the artery — viz., pancreatic branches to 
 the pancreas; intestinal branches, which supply the whole of the small intestine; 
 and ileo-colic, right colic, and middle colic branches, which supply the corresponding 
 partsof the large intestine. The nerves composing this plexus are white in color and 
 firm in texture, and have numerous ganglia developed upon them near their origin. 
 
 The Abdominal Aortic Plexus (plexus aorticus abdomiualis) (Figs. 691, 696, and 
 697). — The abdominal aortic plexus is formed by branches derived, on each side, 
 from the solar plexus and the semilunar ganglia, receiving filaments from some 
 of the lumbar ganglia. It is situated upon the sides and front of the aorta, 
 between the origins of the superior and inferior mesenteric arteries. From this 
 plexus arise part of the spermatic, the inferior mesenteric, and the hypogastric 
 plexuses; and it distributes filaments to the inferior vena cava. 
 
 The Inferior Mesenteric Plexus (plexus mesentericus inferior) (Fig. 696) is derived 
 chiefly from the left side of the aortic plexus. It surrounds the inferior mesenteric 
 artery, and divides into a number of secondary plexuses, which are distributed to 
 all the parts supplied by the artery — viz., the left colic and sigmoid plexuses, which 
 supply the descending and sigmoid flexure of the colon; and the superior haem- 
 orrhoidal plexus (plexus haemorrhoidalis superior), which supplies the upper part 
 of the rectum and joins in the pelvis with branches from the pelvic plexus. 
 
 The Hypogastric Plexus (Plexus Hypogastricus) (Figs. 688, 691, 697). 
 
 The hypogastric plexus supplies the viscera of the pelvic cavity. It is situated 
 in front of the promontory of the sacrum, between the two common iliac arteries, 
 
1086 THE NERVOUS SYSTEM 
 
 and is formed by the union of numerous filaments, which descend on each side 
 from the abdominal aortic plexus and from the lumbar ganglia. This plexus con- 
 tains no evident ganglia; it bifurcates, below, into two lateral portions, which 
 form the pelvic plexuses. 
 
 The Pelvic or Sacral Plexus (Plexus Sacralis). 
 
 The pelvic plexus, sometimes called the inferior hjrpogastric, supplies the viscera 
 of the pelvic cavity, is situated at the side of the rectum in the male, and at the 
 side of the rectum and vagina in the female. It is formed by a continuation of the 
 hypogastric plexus, by branches from the second, third, and fourth sacral nerves, 
 and by a few filaments from the first two sacral ganglia. At the point of junction 
 of these nerves small ganglia are found. From this plexus numerous branches are 
 distributed to all the viscera of the pelvis. They accompany the branches of the 
 internal iliac artery. 
 
 The Inferior Haemorrhoidal Plexus {'plexus haemorrhoidalis inferior). — The infe- 
 rior haemorrhoidal plexus arises from the back part of the pelvic plexus. It 
 supplies the rectum, joining with branches of the superior haemorrhoidal 
 plexus. 
 
 The Vesical Plexus (plexus vesicalis). — The vesical plexus arises from the fore- 
 part of the pelvic plexus. The nerves composing it are numerous, and contain 
 a large proportion of spinal nerve-fibres. They accompany the vesical arteries, 
 and are distributed at the side and base of the bladder. Numerous filaments also 
 pass to the vesiculae seminales and vasa deferentia; those accompanying the vas 
 deferens join, on the spermatic cord, with branches from the spermatic plexus. 
 
 The Prostatic Plexus {'plexus prostaticus). — ^The prostatic plexus is continued 
 from the lower part of the pelvic plexus. The nerves composing it are of large 
 size. They are distributed to the prostate gland, vesiculae seminales, and erectile 
 structure of the penis. The nerves supplying the erectile structure of the penis 
 consist of two sets, the small and large cavernous nerves. They are slender fila- 
 ments, which arise from the forepart of the prostatic plexus, and, after joining 
 with branches from the internal pudic nerve, pass forward beneath the pubic 
 arch. 
 
 The Small Cavernous Nerve {n. cavernosus penis minor) perforates the fibrous 
 covering of the penis near its roots. 
 
 The Large Cavernous Nerve {n. cavernosus penis 'major) passes forward along the 
 dorsum of the penis, joins with the dorsal branch of the pudic nerve, and is dis- 
 tributed to the corpora cavernosa and corpus spongiosum. 
 
 The uterine and vaginal plexuses in reality constitute one plexus, the utero- 
 vaginal plexus -{plexus uterovaginalis). 
 
 The Vaginal Plexus arises from the lower part of the pelvic plexus. It is lost 
 on the walls of the vagina, being distributed to the erectile tissue at its anterior 
 part and to the mucous membrane. The nerves composing this plexus contain, 
 like the vesical nerves, a large proportion of spinal nerve-fibres. 
 
 The Uterine Plexus arises from the upper part of the pelvic plexus above the 
 point where the branches from the sacral nerves join the plexus. Its branches 
 accompany the uterine arteries to the sides of the organ between the layers of the 
 broad ligaments, and are distributed to the cervix and lower part of the body of 
 the uterus, penetrating its substance. 
 
 Other filaments pass separately to the body of the uterus and the Fallopian 
 tube. 
 
 Branches from the plexus accompany the uterine arteries into the substance 
 of the uterus. Upon these filaments ganglionic enlargements are found. 
 
THE OEGANS OF SPECIAL SENSE. 
 
 THE Organs of the Senses are five in number — viz., those of Taste, of Smell, 
 of Sight, of Heaxing, and of Touch. 
 
 THE TONGUE (LINGUA) (Fig. 698). 
 
 The tongue is a very mobile muscular organ, undergoing changes in length and 
 width at every contraction of its muscle. It is the organ of the special sense of 
 taste, and is also an organ of speech, mastication, and deglutition. It is situated 
 in the floor of the mouth, in the interval between the two lateral portions of the 
 body of the lower jaw, and when at rest is about three and one-half inches in 
 length. We describe the body, base, apex, dorsum, margin, and inferior surface. 
 
 The Body {corpus linguae).- — The body forms the great bulk of the organ 
 and is composed of striated muscle. 
 
 The Base or Root {radix linguae). — The base or root is directed backward, and 
 connected with the os hyoideum by the Hyo-glossi and Genio-hyo-glossi muscles 
 and the hyo-glossal membrane; with the epiglottis by three folds of mucous mem- 
 brane, the glosso-epiglottic folds; with the soft palate by means of the anterior 
 pillars of the fauces; and with the pharynx by the Superior constrictors and the 
 mucous membrane. 
 
 The Apex or Tip {apex linguae). — The apex or tip is thin and narrow, and is 
 directed forward against the inner surface of the lower incisor teeth. 
 
 The Dorsum of the Tongue {dorsum linguae). — The dorsum when the tongue 
 of a living person is at rest is markedly arched from before backward. On the 
 dorsum is a median longitudinal raph6 {sulcus medianu^ linguae). This slight 
 depression terminates posteriorly in the depression known as the foramen caecum 
 (foramen caecum linguae [Morgagni{\), from which a shallow-shaped groove, the 
 sulcus terminalis of His, runs outward and forward on each side to the lateral 
 margin of the tongue. The part of the dorsum of the tongue in front of this 
 groove, known as the anterior or oral part, forming about two-thirds of its upper 
 surface, is rough and covered with papillae; the posterior third of the dorsum 
 is back of the sulcus terminalis, is known as the posterior or pharyngeal portion, is 
 smoother, and contains numerous muciparous glands and lymphoid follicles. 
 
 The Margin of the Tongue (margo lateralis linguae). — ^The margin of the 
 tongue is free in front of the anterior arch of the palate. Just in front of the 
 arch are several vertical folds, the folia linguae. 
 
 The Under or Inferior Surface (fades inferior linguae). — The under or 
 inferior surface of the tongue is connected with the lower jaw by the Genio-hyo- 
 glossi muscles, from its sides the mucous membrane is reflected to the inner sur- 
 face of the gums; and from its under surface on to the floor of the mouth, where, 
 in the middle line, it is elevated into a distinct vertical fold, the fraenum linguae 
 (frenulum linguae). To each side of the fraenum is a slight fold of the mucous 
 membrane, the plica fimbriata, the free edge of which exhibits a series of fringe- 
 like processes. 
 
 The tip of the tongue, part of the under surface, its sides, and dorsum are free. 
 
 ( 1087 ) 
 
1088 
 
 THE ORGANS OF SPECIAL SENSE 
 
 Structure of the Tongue. — The tongue is partly invested by mucous mem- 
 brane and a submucous fibrous layer. It consists of symmetrical halves, sepa- 
 rated from each other, in the middle line, by a fibrous septum. Each half is com- 
 posed of muscular fibres arranged in various directions (page 398), containing 
 much interposed fat, and supplied by vessels and nerves. 
 
 The Mucous Membrane {tunica mucosa linguae). — The mucous membrane 
 invests the entire extent of the free surface of the tongue. On the dorsum it is 
 thicker behind than in front, and is continuous with the sheath of the muscles 
 attached to it, through the submucous fibrous layer. On the under surface of the 
 organ, where it is thin and smooth, it can be traced on each side of the fraenum 
 
 PHARYNX 
 
 —EPIGLOTTIS. 
 
 CIRCUM- 
 VALLATE 
 PAPILLyC. 
 
 Fig. 698. — Upper surface of the tongue. 
 
 through the ducts of the submaxillary and the sublingual glands. As it passes 
 over the borders of the organ it gradually assumes a papillary character. 
 
 Structure. — The structure of the mucous membrane of the tongue differs in 
 different parts. That covering the under surface of the organ is thin, smooth, 
 and identical in structure with that lining the rest of the oral cavity. The mucous 
 membrane covering the tongue behind the foramen caecum and sulcus terminalis 
 is thick and freely movable over the subjacent parts. It contains a large number 
 of lymphoid follicles (folliculi linguales), which together constitute what is some- 
 times termed the lingual tonsil (tonsilla lingualis). Each follicle forms a rounded 
 •eminence, the centre of which is perforated by a minute orifice leading into a 
 
THE TONGUE 
 
 1089 
 
 funnel-shaped cavity or recess; around this recess are grouped numerous oval or 
 rounded nodules of lymphoid tissue, each enveloped by a capsule derived from 
 the submucosa, while opening into the bottom of the recesses are also seen the 
 ducts of mucous glands {glandulae linguales). The mucous membrane on the 
 anterior part of the dorsum of the tongue is thin and intimately adherent to the 
 muscular tissue, and covered with minute eminences, the papillae of the tongue. 
 It consists of a layer of connective tissue, the corium or mucosa, supporting numer- 
 ous papillae, and covered, as well as the papillae, with epithelium. 
 
 The epithelium is of the scaly variety, like that of the epidermis. It covers the 
 free surface of the tongue, as maybe readily demonstrated by maceration or boiling, 
 when it can be easily detached entire ; it is much thinner than that of the skin ; the 
 intervals between the large papillae are not filled up by it, but each papilla has 
 a separate investment from root to summit. The deepest cells may sometimes be 
 detached as a separate layer, corresponding to the rete mucosum, but they never 
 contain coloring matter. 
 
 The Corium. — The corium consists of a dense feltwork of fibrous connective 
 tissue, with numerous elastic fibres, firmly connected with the fibrous tissue form- 
 ing the septa between the muscular bundles of the tongue. It contains the ramifi- 
 cations of the numerous vessels (Fig. 699) and nerves from which the papillae are 
 supplied, large plexuses of lymphatic vessels, and the glands of the tongue. 
 
 Filiform. 
 
 Fungiform. 
 
 Secondary 
 papillae. 
 
 Circumvallate. 
 
 Artery 
 Vein 
 
 Fig. 699. — Three kinds of papillae, magnified. 
 
 The Papillae of the Tongue (papillae linguales) (Figs. 698, 699, 700, and 701).— 
 These are papillary projections of the corium. They are thickly distributed over 
 the anterior two-thirds of the upper surface of the tongue, giving to it its char- 
 icteristic roughness. The varieties of papillae met with are — the papillae maximae 
 k circumvallate papillae, papillae mediae or fimgiforme papillae, papillae minimae, 
 )nical or filiforme papillae, and papillae simplices or simple papillae. 
 The Papillae Maximae or Circumvallate Papillae (papillae vallatae) (Figs. 698, 699, 
 ind 700) are of large size, and vary from eight to twelve in number. They are 
 Situated at the back part of the dorsum of the tongue, near its base, in front of 
 the foramen caecum and sulcus terminalis, forming a row on each side, which, 
 'running backward and inward, meet in the middle line, like the two lines of the 
 letter V inverted \. Each papilla consists of a projection of mucous membrane 
 from -Jjj. to ^ of an inch wide, attached to the bottom of a cup-shaped depression of 
 the mucous membrane ; the papilla is in shape like a truncated cone, the smaller 
 end being directed downward and attached to the tongue, the broader part or 
 base projecting on the surface and being studded with numerous small secondary 
 papillae (Fig. 699), which, however, are covered by a smooth layer of the epithe- 
 lium. The cup-shaped depression forms a kind of fossa around the papilla, 
 having a circular margin of about the same elevation covered with smaller papillae. 
 
 G9 
 
1090 
 
 THE ORGANS OF SPECIAL SENSE 
 
 Immediately behind the apex of the V is the foramen caecum, mentioned above. 
 This foramen, according to His, represents the remains of the invagination which 
 forms the median rudiment of the thyroid body, and which for a time opens by 
 a duct, the thyroglossal duct, on to the dorsum of the tongue. It may extend 
 downward toward the hyoid bone. Kanthack, however, disputes this view.^ 
 
 The Fungiform Papillae or Papillae Mediae (papillae fungiformes et papillae len- 
 ticulares) (Fig. 699) , more numerous than the preceding, are scattered irregularly 
 and sparingly over the dorsum of the tongue, but are found chiefly at its sides 
 and apex. They are easily recognized among the other papillae, by their large 
 size, rounded eminences, and deep-red color. They are narrow at their attach- 
 ment to the tongue, but broad and rounded at their free extremities, and are 
 covered with secondary papillae. Their epithelial investment is very thin. 
 
 The Conical or Filiform Papillae or Papillae Minimae {papillae conicae et papillae 
 filiformes) (Fig. 699) cover the anterior two-thirds of the dorsum of the tongue. 
 They are very minute, more or less conical or filiform in shape, and arranged in lines 
 corresponding in direction with the two rows of the papillae circumvallatae, except- 
 ing at the apex of the organ,where their direction is transverse. Projecting from their 
 apices are numerous filiform processes or secondary papillae; these are of a whitish 
 tint, owing to the thickness and density of the epithelium of which they are com- 
 posed, and which has here undergone a 
 peculiar modification, the cells having be- 
 come cornified and elongated into dense, 
 imbricated, brush-like processes. They 
 contain also a number of elastic fibres, which 
 render them firmer and more elastic than 
 the papillae of mucous membrane generally. 
 Simple Papillae, similar to those of the skin, 
 cover the whole of the mucous membrane of 
 the tongue, as well as the larger papillae. 
 They consist of closely set, microscopic ele- 
 vations of the corium, containing a capillary 
 loop, covered by a layer of epithelium. 
 
 Structure of the Papillae (Figs. 699 and 700). 
 — ^The papillae apparently resemble in struc- 
 ture the papillae of the cutis, consisting of a 
 cone-shaped projection of connective tissue, 
 covered with a thick layer of squamous epi- 
 thelium, and contain one or more capillary 
 loops, amongst which nerves are distributed 
 in great abundance. If the epithelium is 
 removed, it will be found, however, that they are not simple elevations like the 
 papillae of the skin, for the surface of each is studded with minute conical pro- 
 cesses of the mucous membrane, which form secondary papillae (Todd and Bow- 
 man). In the papillae circumvallatae the nerves are numerous and of large size; in 
 the papillae fungiformes they are also numerous, and terminate in a plexiform net- 
 work, from which brush-like branches proceed ; in the papillae filiformes their mode 
 of termination is uncertain. Buried in the epidermis of the papillae circumvallatae,. 
 and in some of the fungiformes, are certain peculiar bodies, called taste-buds^ (Fig. 
 701). Each is flask-like in shape, the broad base resting on the corium, and the 
 neck opening by an orifice, the gustatory pore, between the cells of the epithelium. 
 
 Fig. 700. — Circumvatlate papillae of tongue of 
 rabbit, showing position of taste-goblets. a. 
 Duct of gland, d. Serous gland, p. Taste-buds. 
 I. Primary septa, and I', secondary sepia, of 
 papillae, n. Medullated nerve. if. Muscular 
 fibres. (StiJhr.) 
 
 ' Journal of Anatomy and Physiology, 1891. 
 
 ' These bodies are also found in considerable numbers at the side of the base of the tongue, just in front of the- 
 anterior pillars of the fauces, and also on the posterior surface of the epiglottis and anterior surface of the soft 
 palate.— Ed. of 15th English edition. 
 
THE TONGUE 1091 
 
 They are formed by two kinds of cells, supporting cells and gustatory cells. The 
 supporting cells are mostly arranged like the staves of a cask, and form an outer 
 envelope for the bud. Some, however, are found in the interior of the bud between 
 the gustatory cells. The gustatory cells occupy the central portion of the bud; 
 they are spindle-shaped, and each possesses a large spherical nucleus near the 
 middle of the cell. Until recently the teaching was as follows: The peripheral 
 end of the cell terminates as the gustatory pore in a fine, hair-like filament, the 
 gustatory hair. The central process passes toward the deep extremity of the bud, 
 and there ends in a single or bifurcated varicose filament, which was formerly 
 supposed to be continuous with the terminal fibril of a nerve; the investigations 
 of Lenhossek and others would seem to prove, however, that this is not so, but 
 that the nerve-fibrils after losing their medullary sheaths enter the taste-bud, and 
 
 Gustatory hairs Taste pore 
 
 Epithelium 
 
 Taste bud 
 
 Tunica propria—^ 
 Fig. 701. — Taste-buds Irom the papilla foliaia of a rabbit, a sou. i .Szymonowicz.) 
 
 terminate in a fine extremity between the gustatory cells. Other nerve-fibrils 
 may be seen ramifying between the cortical cells and terminating in fine extrem- 
 ities; these, however, are believed to be nerves of ordinary sensation, and not 
 gustatory. It is now not believed that the epithelia of the taste-buds are directly 
 connected with the nerve-fibres by long processes. "The latest researches have 
 shown that dendrites of sensory neurones (sensory nerves) enter the taste-buds 
 and end free in telodendria. The latter surround the neuro-epithelial, and, to 
 some extent, the sustentacular cells, their relations depending on contact."^ 
 
 Glands of the Tongue. — The tongue is provided with mucous and serous glands. 
 The mucous glands are similar in structure to the labial and buccal glands. They 
 are found especially at the back part, behind the circumvallate papillae, but are 
 also present at the apex and marginal parts. In connection with these glands 
 special ones have been described by Blandin and Nuhn. They are known as the 
 glands of Nuhn and Blandin or apical glands (glandulae linguales anteriores of Nuhn 
 mid Blandin) (Fig. 702). They are situated near the apex of the tongue on either 
 side of the fraenum, and each is covered over by a fasciculus of muscular fibre 
 derived from the Stylo-glossus and Inferior lingualis muscles. Each gland is from 
 half an inch to nearlv an inch lonff and about the third of an inch broad. It has 
 from four to six ducts, which open on the under surface of the apex. 
 
 The Serous Glands or Glands of v. Ebner occur only at the back of the tongue in 
 the neighborhood of the taste-buds, their ducts opening for the most part into the 
 
 ' Text-book of Histology. By A. A. Bohm and M. von Davidoff. Edited by G. Carl Huber. 
 
1092 
 
 THE ORGANS OF SPECIAL SENSE 
 
 fossae of the papillae cireumvallatae. These glands are racemose, the duct branch- 
 ing into several minute ducts, which terminate in alveoli lined by a single layer 
 of more or less columnar epithelium. Their secretion is of a watery nature, and 
 probably assists in the distribution of the substance to be tasted over the taste- 
 area (Ebner). 
 
 The Hyo-glossal membrane is a strong fibrous lamina which is derived from the 
 septum of the tongue and which connects the under surface of the base of the 
 tongue to the body of the hyoid bone. This membrane receives, in front, some 
 of the posterior fibres of the Genio-hyo-glossi muscles. 
 
 The Vessels of the Tongue. — The arteries of the tongue are derived from the 
 lingual, the facial, and ascending pharyngeal. The veins of the tongue open into 
 the internal jugular. 
 
 The lingual artery (Fig. 704) on each side passes forward beneath the Hyo- 
 glossus muscle and courses to the apex of the tongue, between the Genio-glossus 
 and the Inferior lingual muscles, about one-eighth of an inch from the surface. 
 It divides into the ranine (Fig.702 ) and sublingual (Fig. 704). Near the apex a 
 branch is given off from the ranine artery, which penetrates the septum and joins 
 a like branch from the other side. The dorsalis linguae is a branch of the lingual 
 
 Bristles 
 in ducts 
 "N of glands. 
 
 Glands of 
 Blandin 
 or Niihn. 
 
 Lingual nerve. Ranine artery. 
 
 Fig. 702. — Under surface of tongue, showing position and relations of gland of Blandin or Nuhn. 
 a preparation in the Museum of the Royal College of Surgeons of England.) 
 
 (Prom 
 
 supplying the posterior part of the tongue, and rami from the tonsillar branch 
 of the facial go to the same region. A network of capillary vessels is placed 
 beneath the epithelium. 
 
 The ranine veins lie to the sides of the fraenum underneath the mucous mem- 
 brane. Each ranine vein runs backward, superficial to and upon the Hyo-glossus 
 muscle and near to the hypo-glossal nerve. The venae comites of the lingual artery 
 usually join the ranine vein, and the trunk opens into the internal jugular vein, 
 but the vessels may open separately into the jugular (Fig. 445). 
 
 The Muscles of the Tongue. — The muscular fibres of the tongue run in various 
 directions. These fibres are divided into two sets, Extrinsic and Intrinsic, which 
 have already been described (pp. 396, 397, 398, 399, and 400). 
 
THE TONGUE 
 
 1093 
 
 The Extrinsic come from the Stylo-glossus, Hyo-glossus, Genio-glossus, 
 Palato-glossus, and Chondro-glossus. The Intrinsic muscles are the Superior 
 lingualis (m. longitiulinalis superior), the Inferior lingualis (m. longitudinalis 
 inferior), the Transverse lingual (m. transversus linguae), and the Vertical lingual 
 (m. verticalis linguae). The outer or cortical portion of the tongue is composed 
 chiefly of longitudinal fibres. The central or medullary portion is composed chiefly 
 of vertical and transverse fibres and is divided into two parts by a vertical sep- 
 tum {septum, linguae), which is a fibrous structure, begiiming at the apex and 
 passing back. As it approaches the back it becomes narrower vertically and 
 broadens out transversely to form the hyo-glossal membrane. The fibrous septum 
 is well displayed by making a vertical section of the tongue. 
 
 The Lymphatic Vessels of the Tongue (Fig. 491). — The lymphatic vessels from 
 the anterior half of the tongue pass to the submaxillary lymph glands. 
 
 Lymph vessels from the posterior half of the tongue are connected with satellite 
 glands on the Hyo-glossus muscle and terminate in the deep cervical glands. The 
 last-named lymph- vessel accompanies the ranine vein. The lingual lymphatics 
 arise from a network beneath the epithelium. Across the anterior two-thirds 
 of the tongue there is little or no lymphatic connection between the two sides; 
 in the posterior one-third there is free connection. 
 
 SUPERIOR 
 
 LONGITUDINALIS 
 
 MUSCLE 
 
 VrRTICALIS, 
 LINGUiE MUSCLE 
 
 TRANSVERSUS 
 LINGU£ MUSCLE 
 
 INFERIOR 
 
 LONGITUDINALIS 
 
 MUSCLE 
 
 STYLOGLOSSUS 
 MUSCLE 
 
 DEEP LINGUAL 
 ARTERY 
 
 SUBLINGUAL 
 GLAND 
 
 GENIOGLOSSUS 
 MWSCLE 
 
 Fig. 703. — Frontal section through the body of the tongue of a new-born babe. X 3. (Spalteholz.) 
 
 The Nerves of the Tongue (Fig. 704). — The nerves of the tongue are five in num- 
 ber in each half; the lingual branch of the inferior maxillary division of the fifth, 
 which is distributed to the papillae at the forepart and sides of the tongue, and 
 forms the nerve of ordinary sensibility for its anterior two-thirds; the chorda 
 t3mipani, which runs in the sheath of the lingual, is generally regarded as the 
 nerve of taste for the same area; the lingual branch of the glosso-pharyngeal, which 
 is distributed to the mucous membrane at the base and sides of the tongue, and 
 to the papillae circumvallatae, and which supplies both sensory and gustatory 
 filaments to this region; the h3rpo-glossal nerve, which is the motor nerve to the 
 muscular substance of the tongue; and the internal laryngeal branch of the superior 
 laryngeal, which sends some fine branches to the root near to the epiglottis. 
 Sympathetic filaments also pass to the tongue from the nervi molles on the 
 lingual and other arteries supplying it. Some of the nerves end free between the 
 cells of epithelium; others terminate as end organs (Meissner's corpuscles and 
 the end-bulbs of Krause), and in taste-buds as sensory dendrites. 
 
 Surgical Anatomy. — The diseases to which the tongue is liable are numerous, and its .sur- 
 gical anatomy is of importance, since any or all the structures of which it is composed — muscles, 
 connective ti.ssue, mucous membrane, glands, vessels, nerves, and lymphatics — may be the .seat 
 of morbid changes. It is not often the seat of congenital defects, though a few cases of vertical 
 
1094 
 
 THE ORGANS OF SPECIAL SENSE 
 
 deft have been recorded, and it is occasionally, though much more rarely than is commonly sup- 
 posed, the seat of tongue-tie, from shortness of the fraenum. 
 
 There is, however, one condition which must be regarded as congenital, though not uncom- 
 monly it does not exhibit the significant changes until a year or two after birth. This is an 
 enlargement of the tongue which is due primarily to a dilatation of the lymph-channels and a 
 greatly increased development of the lymphatic tissue throughout the tongue {macrogloasia) . This 
 is often aggravated by inflammatory changes induced by injury or exposure, and the tongue may 
 assume enormous dimensions and hang out of the mouth, giving the child an imbecile expression. 
 The treatment consists in excising a V-shaped portion and bringing the cut surfaces together 
 with deeply placed silver sutures. Compression has been resorted to in some cases with occa- 
 sional success, but it is difficult to apply. Acute inflammation of the tongue (acute glossitis), 
 which may be caused by injury or the introduction of some septic or irritating matter, and it 
 is attended by great swelling from infiltration of the connective tissue of the tongue; this con- 
 nective tissue is present in considerable quantity. The great swelling renders the patient 
 incapable of swallowing or speaking, and may seriously impede respiration. The condition may 
 eventuate in suppuration and the formation of an acute abscess. Chronic abscess, which has 
 been mistaken for cancer, may also occur in the sul)stanfi' of the tongue. 
 
 f^uhlingual 
 artery. 
 
 Glosso-nharyn- 
 geal nerve. 
 
 Fig. 704.- 
 
 Internal laryngeal 
 
 branch of the 
 
 superior laryngeal 
 
 nerve. 
 
 -Under surface of tongue, showing the di-i i ibution of nerves to this organ, 
 in the Museum of the Royal (JoUege of Surgeons of tugland.) 
 
 (From a preparation 
 
 The mucous membrane of the tongue may become chronically inflamed, and presents different 
 appearances in different stages of the disease, to which the terms leucoplakia, psorias, and 
 ichthyosis have been given. 
 
 The tongue, being very vascular, is often the seat of naevoid growths, and these have a tendency 
 to grow rapidly. 
 
 The tongue is frequently the seat of ulceration, which may arise from many causes, as from 
 the irritation of jagged teeth, dyspepsia, tuberculosis, syphilis, and cancer. Of these the cancerous 
 ulcer is the most important, and probably also the most common. The variety is the squamous 
 epithelioma, which soon develops into an ulcer with an indurated base. It produces great pain, 
 which speedily extends to all parts supplied with sensation by the fifth nerve, especially to the 
 
THE NOSE 1095 
 
 region of the ear. The pain in these cases is conducted to the ear and temporal region by the 
 hngual nerve, and from this nerve pain radiates to the other branches of the inferior maxillary 
 nerve, especially the auriculo-temporal. Possibly pain in the ear itself may be due to implication 
 of the fibres of the glosso-pharyngeal nerve, which by its tympanic branch reaches the tympanic 
 plexus. Cancer of the tongue spreads through the organ very rapidly because of the almost 
 constant muscular movements. 
 
 Cancer of the tongue may necessitate removal of a part or the whole of the organ, and many 
 different methods have been adopted for its excision. It may be removed from the mouth by 
 the ecraseur or the scissors. The better method is by the scissors, usually known as Whitehead's 
 method. The mouth is widely opened with a gag the tongue is transfixed with a stout silk liga- 
 ture, by which to hold and make traction on it and the reflection of mucous membrane from 
 the tongue to the jaw, and the insertion of the Genio-hyo-glossi first divided with a pair of 
 curved blunt scissors. The Palato-glossi are aiso divided. The tongue can now be pulled well 
 out of the mouth. The base of the tongue is cut through by a series of short snips, each bleed- 
 ing vessel being dealt with as soon as divided, until the situation of the ranine artery is reached. 
 The remaining undivided portion of tissue is to be seized with a pair of Wells's forceps, the tongue 
 removed, and the vessel secured. In the event of the ranine artery being accidentally injured 
 early in the operation, hemorrhage can be at once controlled by passing two fingers over the 
 dorsum of the tongue as far as the epiglottis and dragging the root of the tongue forcibly forward. 
 
 In cases where the disease is confined to one side of the anterior portion of the tongue this 
 operation may be modified by splitting the tongue down the centre and removing only the affected 
 half. If the posterior portion of the tongue is attacked oy cancer the entire tongue must be 
 removed, even if but one side of the organ is apparently involved. The exchange of lymph 
 between the halves of the posterior portion of the tongue makes it certain that the opposite half 
 becomes involved soon after the origin of the disease. Whatever operation is performed for 
 cancer of the tongue, the glands must be removed ''rom both sides of the neck. This is to' be 
 done, even if but one side of the tongue is removed. Kocher, after performing a preliminary trache- 
 otomy, removes the tongue from the neck; by an incision taken ^rom near the lobule of the ear, 
 down the anterior border of the Sterno-mastoid to the level of the great cornu of the hyoid bone, 
 then forward to the body of the hyoid bone, and upward to near the symphysis of the jaw. The 
 lingual artery is now secured and by a careful dissection the submaxillary lymphatic glands 
 and the tongue removed. Regnol' advocated the removal of the tongue by a semilunar incision 
 in the submaxillary triangle along the )ine of the lower jaw, and a vertical incision from the 
 centre of the semilunar one backward to the hyoid bone. Care must be taken not to carry the 
 first incision too far backward, so as to wound the facial arteries. The tongue is thus reached 
 through the floor of the mouth pulled out through the external incision, and removed with the 
 knife. The great objection to this operation is that all the muscles which raise the hyoid 
 bone and larynx are divided, and that therefore the movements of deglutition and respiration are 
 interfered with. 
 
 Finally, where both sides of the floor of the mouth are involved in the disease, or where very 
 free access is required on account of the extension backward of the disease to the pillars of the 
 fauces and the tonsil, or where the lower jaw is involved, the operation recommended by Syme 
 must be performed. This is done by an incision through the central line of the lip- across the 
 chin, and down as far as the hyoid bone. The iower jaw is sawed through at the symphysis, and 
 the two halves of the bone forcibly separated from each other. The mucous membrane is sepa- 
 rated from the bone, and the Genio-hyo-glossi detached from the bone, and the Hyo-glossi 
 divided. The tongue is then drawn forward and removed close to its attachment to the hyoid 
 bone. Adjacent lymph glands can be removed, and if the bone is implicated in the dis- 
 ease, it can also be removed by freeing it from the soft parts externally and internally, and 
 making a second section with the saw beyond the diseased part. 
 
 Formerly many surgeons before removing the tongue performed a preliminary tracheotomy: 
 (1) to prevent blood entering the air-passages; and (2) to allow the patient to breathe through 
 the tube and not inspire air which had passed over a sloughy wound, and which was loaded with 
 septic organisms and ikely to induce septic pneumonia. By operating with the patient in the 
 Trendelenburg position, the blood is caused to flow away from the air-passages. By the judicious 
 use of iodoform the evil mentioned secondly may be obviated, and the preliminary tracheotomy is 
 now usually dispensed with. 
 
 THE NOSE. 
 
 The nose is the peripheral portion of the organ of smell (organon olfactus) : by 
 means of the peculiar properties of its nerves it protects the lungs from the inhala- 
 tion of deleterious gases and assists the organ of taste in discriminating the prop- 
 erties of food. The organ of smell consists of two parts; one external, the outer 
 nose; the other internal, the nasal fossae. 
 
1096 
 
 THE ORGANS OF SPECIAL SENSE 
 
 THE OUTER NOSE (NASUS EXTERNUS). 
 
 The outer nose is the more anterior and prominent part of the organ of smell. 
 Of a triangular form, it is directed downward, and projects from the centre of 
 the face, immediately above the upper lip. Its summit or root {radix nasi) is 
 connected directly with the forehead. Its inferior paxt or base (basis nasi) pre- 
 sents two elliptical orifices, the nostrils or anterior nares (nares), separated from 
 each other by an antero-posterior septum, the mobile septum or columna nasi 
 (septum mobile nasi). The margins of the nostrils are provided with a number 
 of stiff hairs or vibrissae, which arrest the passage of foreign substances carried 
 with the current of air intended for respiration. The point (apex nasi) is the free 
 extremity of the nose. The lateral surfaces of the nose form, by their union in 
 the middle line, the dorsum (dorsum nasi), the direction of which varies considerably 
 in different individuals. The portion of the dorsum over the nasal bones is the 
 bridge. Each lateral surface terminates below in a rounded eminence, the wing 
 or ala nasi, which, by its lower margin (margo nasi), forms the outer boundary 
 of the corresponding nostril. Above the ala is a depression, the alar sulcus. 
 
 Seen from below. 
 
 Side view. 
 
 Lower lateral cartilage. 
 
 Sesamoid cartilages. 
 
 Figs. 705 and 706. — Cartilages of the nose. 
 
 Structure. — The nose is composed of a framework of bones and cartilages, the 
 latter being slightly acted upon by certain muscles. It is covered externally by the 
 integument, internally by mucous membrane, and is supplied with vessels and nerves. 
 
 The Bony Framework. — The bony framework occupies the upper part of the 
 organ ; it consists of the nasal bones and the nasal processes of the superior maxillary 
 bones (pp. 104 and 109). 
 
 The Cartilaginous Framework (cartilagines nasi) (Figs. 705 and 706). — The car- 
 tilaginous framework consists of five pieces, the two upper and the two lower 
 lateral cartilages and the cartilage of the septum. 
 
 The Upper Lateral Cartilage (cartilago nasi lateralis) of each side is situated below 
 the free margin of the nasal bone. It is flattened and triangular in shape. Its ante- 
 rior margin is thicker than the posterior, and continuous with the cartilage of the 
 septum. Its posterior margin is attached to the nasal process of the superior 
 maxillary and nasal bones. Its inferior margin is connected by fibrous tissue with 
 the lower lateral cartilage; one surface is turned outward, the other inward toward 
 the nasal cavity. 
 
THE OUTER NOSE 1097 
 
 The Lower Lateral Cartilage, the Cartilage of the Aperture or the Greater Alar Car- 
 tilage (cartilago alaris major) of each side consists of two thin, flexible plates situated 
 immediately below the preceding, and bent upon themselves in such a manner as 
 to form the inner and outer walls of the orifice of the nostril. The portion which 
 forms the inner wall {crus mediale), thicker than the rest, is loosely connected with 
 the corresponding portion of the opposite cartilage, and forms a small part of the 
 columna. Its inferior border, free, rounded, and projecting, forms, with the thick- 
 ened integument and subjacent tissue and the corresponding parts of the opposite 
 side, the mobile septum. The part of the cartilage which forms the outer wall {crus 
 later ale) is curved to correspond with the ala of the nose; it is oval and flattened, 
 narrow behind, where it is connected with the nasal process of the superior maxilla 
 by a tough fibrous membrane, in which are found three or four small cartilaginous 
 plates, the sesamoid, accessory quadrate or lesser alar cartilages {cartilagines alares 
 minores). Above, it is connected by fibrous tissue to the upper lateral cartilage 
 and front part of the cartilage of the septum; below, it falls short of the margin 
 of the nostril; the ala being formed by dense cellular tissue covered by skin. In 
 front the lower lateral cartilages are separated by a notch which corresponds 
 with the point of the nose. 
 
 The Triangular Cartilage of the Septum {cartilago septi nasi) (Figs. 705 and 707) 
 is somewhat quadrilateral in form, thicker at its margins than at its centre, and 
 completes the separation between the 
 nasal fossae in front. Its anterior 
 margin, thickest above, is connected 
 with the nasal bones, and is continuous 
 with the anterior margins of the two 
 upper lateral cartilages. Below, it is 
 connected to the inner portions of the 
 lower lateral cartilages by fibrous 
 tissue. Its posterior margin is con- 
 nected with the perpendicular lamella 
 of the ethmoid ; its inferior margin with 
 the vomer and the palate processes of 
 the superior maxillary bones (Fig. 103). 
 
 It may be prolonged backward 
 (especially in children) for some dis- 
 tance between the vomer and perpen- 
 dicular plate of the ethmoid, forming ^'''- 707.-Bones and^cartUa^es^of septum of the nose. 
 
 what is termed the sphenoidal process 
 
 {processus sphenoidalis septi cartilaginei) . The septal cartilage does not reach 
 as far as the lowest part of the nasal septum. This is formed by the inner 
 portions of the lower lateral cartilages and by the skin ; it is freely movable, and 
 hence is termed the mobile septum {septum mobile nasi). 
 
 Along the lower margin of the anterior half of the cartilage of the septum is 
 another cartilage which is attached to the vomer and is known as the vomerine 
 cartilage or cartilage of Jacobson {cartilago vomeronasalis) . 
 
 These various cartilages are connected to each other and to the bones by a tough 
 fibrous membrane, which allows the utmost facility of movement between them. 
 
 The Muscles of the Nose. — The muscles of the nose are situated beneath the 
 integument; they are (on each side) the Pyramidalis nasi, the Levator iabii supe- 
 riores alaeque nasi, the Dilatator naris, anterior and posterior, the Compressor 
 nasi, the Compressor narium minor, and the Depressor alae nasi. They have been 
 previously described (p. 375). 
 
 The Integument covering the dorsum and sides of the nose is thin, and loosely 
 connected with the subjacent parts; but the integument of the tip and the alae of 
 
1098 
 
 THE ORGANS OF SPECIAL SENSE 
 
 the nose is thicker and more firmly adherent, and is furnished with a large number 
 of sebaceous follicles, the orifices of which are usually very distinct. 
 
 The Mucous Membrane lining the interior of the nose is continuous with the 
 skin externally and with the mucous membrane which lines the nasal fossae within. 
 
 The Arteries of the Outer Nose. — The arteries of the nose are the lateralis nasi from 
 the facial, and the inferior artery of the septum from the superior coronary, which 
 supply the alae and septum, the sides and dorsum being supplied from the nasal 
 branch of the ophthalmic and the infraorbital. 
 
 The Veins of the Outer Nose. — The veins of the nose terminate in the facial and 
 ophthalmic. 
 
 The Lymphatics of the Outer Nose. — These vessels are shown in Figs. 487, 489, 
 and 490. They empty chiefly into the submaxillary lymph glands. 
 
 The Nerves of the Outer Nose. — The nerves for the muscles of the nose are derived 
 from the facial, while the skin receives its branches from the infraorbital, infra- 
 trochlear, and nasal branches of the ophthalmic. 
 
 THE NASAL FOSSAE (CAVUM NASI). 
 
 The nasal fossae are two irregular cavities situated in the middle of the face, 
 one on each side of the middle line, and extending from before backward. They 
 open in front, when the soft parts are in place, by the two nostrils or anterior nares, 
 and terminate, behind, in the naso-pharynx by the posterior nares. 
 
 OPENINGS OF POSTERIOR 
 ETHMOIDAL CELLS 
 
 SPHENOIDAL 
 SINUS 
 
 Fio. 708. — External wall of right nasal fossa, parts of the turbinates having been cut away to show the 
 orifices of the sinuses which open into the meatuses. (Testut.) 
 
 The Anterior Nares {nares). — The anterior nares are somewhat pear-shaped' 
 apertures, each measuring about one inch antero-posteriorly and half an inch 
 transversely at their widest part. The nasal fossae in the dry skull open in front 
 by the anterior nasal aperture (apertura pyriformis). 
 
 The Posterior Nares (choanae). — The posterior nares are two oval openings, 
 which are smaller in the living or recent subject than in the skeleton, because they 
 
THE NASAL FOSSAE 
 
 1099 
 
 are narrowed by the mucous membrane. Each measures an inch in the vertical 
 and half an inch in the transverse direction in a well-developed adult skull. 
 
 For the description of the bony boundaries of the nasal fossae see section on 
 Osteology (p. 143). 
 
 Inside the aperture of the nostril is a slight dilatation, the vestibule (vestibulum 
 nasi), which extends as a small pouch, the ventricle, toward the point of the nose. 
 Above and behind the vestibule is surrounded by a prominence (limen nasi). 
 Below the prominence the vestibule is lined with skin; above and behind it the 
 fossa is lined with mucous membrane. The fossa, above and behind the vestibule, 
 has been divided into two parts: an olfactory portion (regio olfactoria), a slit-like 
 cavity, comprising the upper and central part of the septum and probably the 
 superior turbinated bone, and a respiratory portion (regio respiratoria) , which com- 
 prises the rest of the fossa. 
 
 Eye-ball 
 
 Oroove (hiatus semilunaris) 
 leading to injunditndum 
 Middle turbinated bone 
 
 Middle meatus 
 Antrum of Highmore 
 Inferior meatus 
 
 Inferior turbinated bone 
 
 ( Buccal cavity 
 
 Space between cheek and gum 
 Molar tooth, upper jaw 
 
 Hoot of molar tooth 
 
 Fig. 
 
 Inferior dental Jierve 
 
 709. — Tran.sverse vertical section of the nasal fossae. The section is made anterior to the superior 
 turbinated bones. (Cryer.) 
 
 Outer Wall (Figs. 708, 709).— The superior, middle, and inferior meatus {meatus 
 nasi superior, medius and inferior) are described on pages 144 and 145. The 
 sphenoidal air sinus opens into the spheno-ethmoidal recess (recessu^ sphenoethmoid- 
 alis), a narrow recess above the superior turbinated bone (Fig. 708). The posterior 
 ethmoidal cells open into the front and upper part of the superior meatus (Fig. 708). 
 On raising or cutting away the middle turbinated bone the outer wall of the middle 
 meatus is fully exposed (Figs. 708 and 709) and presents (1) a rounded elevation, 
 termed the bulla ethmoidalis, opening on or immediately above which are the orifices 
 of the middle ethmoidal cells; (2) a deep, narrow, curved groove, in front of the bulla 
 ethmoidalis, termed the hiatus semilunaris, into which the anterior ethmoidal cells 
 
1100 THE ORGANS OF SPECIAL SENSE 
 
 and the antrum of Highmore {sinus maxillaris) open, the orifice of the latter being 
 placed near the level of its roof. The middle meatus is prolonged, above and in 
 front, into the infundibulum (infundibulum ethmoidale) , which leads into the frontal 
 sinus. The anterior extremity of the meatus is continued into a depressed area 
 which lies above the vestibule and is named the atrium (atrium meatus medii 
 nasi). The nasal duct opens into the anterior part of the inferior meatus, the 
 opening being frequently overlapped by a fold of mucous membrane, and from 
 the orifice of the duct a groove leads downward and forward. 
 
 The Inner Wall (Fig. 709). — The inner wall or septum is frequently more or less 
 deflected from the mesial plane (Figs. 101 and 709), thus limiting the size of one 
 fossa and increasing that of the other. Ridges or spurs of bone growing outward 
 from the septum are also sometimes present. Immediately over the incisive 
 foramen at the lower edge of the cartilage of the septum a depression, the naso- 
 palatine recess [recessus naso'palatinus) , may be seen. In the septum close to this 
 recess a minute orifice may be discerned ; it leads into a blind pouch, the rudi- 
 mentary organ of Jacobson (organon vomeronasale) , which is well developed in 
 some of the lower animals, but is rudimentary in man. The organ is supported 
 by a plate of cartilage, distinct from the cartilage of the septum, the cartilage of 
 Jacobson (p. 1097). The cartilage of Jacobson is to the outer side of the lower 
 edge of the cartilage of the septum. The diverticulum opens anteriorly near the 
 floor of the nose and close by Stenson's foramen. Just below the opening of 
 the blind pouch is an elevation, the eminence of Jacobson. 
 
 The Mucous Membrane (memhrana mucosa nasi), — The mucous membrane lining 
 the nasal fossae is called the pituitary, from the nature of its secretion; or Schneide- 
 rian, from Schneider, the first anatomist who showed that the secretion proceeded 
 from the mucous membrane, and not, as was formerly imagined, from the brain. 
 It is intimately adherent to the periosteum or perichondrium, over which it lies. 
 It is continuous externally with the skin through the anterior nares, and with the 
 mucous membrane of the naso-pharynx through the posterior nares. From the 
 nasal fossae its continuity may be traced with the conjunctiva through the nasal 
 duct and lachrymal canals; with the linmg membrane of the tympanum and mas- 
 toid cells through the Eustachian tube; and with the frontal, ethmoidal, and 
 sphenoidal sinuses, and the antrum of Highmore through the several openings in 
 the meatuses. The mucous membrane is thickest and most vascular over the 
 turbinated bones. It is also thick over the septum, but in the intervals between 
 the spongy bones and on the floor of the nasal fossae it is very thin. Where it 
 lines the various sinuses and the antrum of Highmore it is thin and pale. 
 
 Owing to the great thickness of this membrane, the nasal fossae are much, 
 narrower, and the turbinated bones, especially the lower ones, appear larger and 
 more prominent than in the skeleton. From the same circumstances also the 
 various apertures communicating with the meatuses are considerably narrowed 
 or completely closed. The vestibule is lined by modified skin, and contains hairs 
 (vibrissas) which guard the entrance of the nostril. 
 
 Structure of the Mucous Membrane (Fig. 710). — The epithelium covering the; 
 mucous membrane differs in its character according to the functions of the part of 
 the nose in which it is found. In the respiratory portion of the nasal cavity the 
 epithelium is columnar and ciliated. Interspersed among the columnar ciliated 
 cells are goblet or mucin cells, while between their bases are found smaller pyra- 
 midal cells. In this region, beneath the epithelium and its basement membrane, 
 is a fibrous layer infiltrated with lymph-corpuscles, so as to form in many parts 
 a diffuse adenoid tissue, which is particularly plentiful in children, and beneath 
 this a nearly continuous layer of smaller and larger glands, some mucous and some 
 serous, the ducts of which open upon the surface. In the respiratory portion of 
 the mucous membrane there is an extensive anastomosing plexus of veins, which 
 
THE NASAL FOSSAE 
 
 1101 
 
 in some regions forms a distinct cavernous tissue (plexus cavernosus concharum). 
 The cavernous tissue is particularly distinct over the inferior turbinated bones. 
 In the olfactory region the mucous membrane is yellowish in color and the epi- 
 thelial cells are columnar and non-ciliated ; they are of two kinds, supporting cells 
 and olfactory cells. 
 
 The Supporting Cells contain oval nuclei, situated in the deeper parts of the cells; 
 the free surface of each cell presents a sharp outline, and its deep extremity is 
 prolonged into a process which runs inward, branching to communicate with 
 similar processes from neighboring cells, so as to form a network in the deep part 
 of the mucous membrane. Lying between these central processes of the support- 
 ing cells are a large number of spindle-shaped cells, the olfactory cells, which con- 
 sist of a large spherical nucleus surrounded by a small amount of granular proto- 
 plasm, and possessing two processes, of which one runs outward between the 
 columnar epithelial cells, and projects on the surface of the mucous membrane 
 as a fine, hair-like process, the olfactory hair; the other or deep process runs inward, 
 is frequently beaded like a nerve-fibre, and is believed by most observers to be in 
 connection with one of the terminal filaments of the olfactory nerve. . Beneath the 
 
 Fig. 710. — Section of the olfactory mucous membrane; a, epithelium; b, glands of Bowman; c, nerve bundles. 
 
 (Cadiat.) 
 
 epithelium, extending through the thickness of the mucous membrane, is a layer 
 of tubular, often branched, glands, the glands of Bowman (glandulae olfactoriae), 
 identical in structure with serous glands. 
 
 The Arteries of the Nasal Fossae. — The arteries of the nasal fossae are the anterior 
 and posterior ethmoidal, from the ophthalmic, which supply the ethmoidal cells, 
 frontal sinuses, and roof of the nose; the spheno-palatine, from the internal maxil- 
 lary, which supplies the mucous membrane covering the spongy bones, the 
 meatuses, and septum; the inferior artery of the septum, from the superior 
 coronary of the facial; and the infraorbital and alveolar branches of the internal 
 maxillary^ which supply the lining membrane of the antrum. The ramifications 
 of these vessels form a close, plexiform network, beneath and in the substance of 
 the mucous membrane. 
 
 The Veins of the Nasal Fossae. — The veins of the nasal fossae form a close, cav- 
 ernous-like network beneath the mucous membrane. This cavernous appearance 
 is especially well marked over the lower part of the septum and over the middle 
 and inferior turbinated bones. Some of the veins pass, with those accompanying 
 the spheno-palatine artery, through the spheno-palatine foramen; and others, 
 through the alveolar branch, to join the facial vein; some accompany the eth- 
 
1102 
 
 THE ORGANS OF SPECIAL SENSE 
 
 Fig. 711. — Nerves of septum of nose. Right side. 
 
 moidal arteries, and terminate in the ophthalmic vein; and, lastly, a few com- 
 municate with the veins in the interior of the skull, through the foramina in the 
 cribriform plate of the ethmoid bone, and the foramen caecum. 
 
 The Lymphatics of the Nasal Fossae. — The lymphatics can be injected from the 
 subdural and subarachnoid spaces, and form a plexus in the superficial portion of 
 the mucous membrane. The lymph is drained partly into one or two glands which 
 
 lie near the great cornu of the hyoid 
 bone and partly into a gland situated in 
 front of the axis. 
 
 The Nerves of the Nasal Fossae (Fisr, 
 711). — ^The nerves are: the olfactory, 
 the nasal branch of the ophthalmic, fila- 
 ments from the anterior dental branch of 
 the superior maxillary, the Vidian, the 
 naso-palatine, descending anterior pala- 
 tine, and nasal branches of Meckel's 
 ganglion. The olfactory, the special 
 nerve of the sense of smell, is distributed 
 to the olfactory region, and has been 
 already referred to (p. 1019). The nasal 
 branch of the ophthalmic division of the 
 fifth nerve distributes filaments to the 
 forepart of the septum and outer wall 
 of the nasal fossae. Filaments from the 
 anterior dental branch of the superior maxillary supply the inferior meatus and 
 inferior turbinated bone. The Vidian nerve supplies the upper and back part of 
 the septum and superior spongy bone, and the upper anterior nasal branches 
 from the spheno -palatine ganglion have a similar distribution. The naso-palatine 
 nerve supplies the middle of the septum. The larger or anterior palatine nerve 
 supplies the lower nasal branches to the middle and lower spongy bones. 
 
 Surgical Anatomy. — Instances of congenital deformity of the nose are occasionally met with, 
 such as complete absence of the nose, an aperture only being present; or perfect development 
 on one side, and suppression or malformation on the other; or there may be imperfect apposi- 
 tion of the nasal bones, so that the nose presents a median cleft or furrow. Deformities which 
 have been acquired are much more common, such as flattening of the nose (saddle nose), the result 
 of syphilitic necrosis, imperfect development of the nasal bones in cases of congenital syphilis, or 
 a lateral deviation of the nose the result of fracture. 
 
 The skin over the alae and tip of the nose is thick and closely adherent to subjacent parts. 
 Inflammation of this part is therefore very painful, on account of the tension. The skin is largely 
 supplied with blood, and, the circulation here being terminal, vascular engorgement is liable to 
 occur, especially in women at the menopause and in both sexes from disorders of digestion, exposure 
 to cold, etc. The skin of the nose also contains a large number of sebaceous follicles, and these, as 
 a result of intemperance, are apt to become affected, and the nose becomes reddened, congested, 
 and irregularly swollen. To this condition the term grog-blossom is popularly applied. In some 
 of these cases there is enormous hypertrophy of the skin and subcutaneous tissues, producing 
 pendulous masses, termed lipomata nasi. Ordinary epithelioma and rodent ulcer may attack 
 the nose, the latter being the more common of the two. Lupus and syphilitic ulceration fre- 
 quently attack the nose, and may destroy the whole of the cartilaginous portion. In fact, lupus 
 vulgaris begins more frequently on the ala of the nose than in any other situation. 
 
 Cases of congenital occlusion of one or both nostrils, or adhesion between the ala and septum 
 may occur, and may require immediate operation, since the obstruction much interferes with 
 sucking. Bony closure of the posterior nares may also occur. 
 
 To examine the na^al cavities, the head should be thrown back and the nose drawn upward, 
 the parts being dilated by some form of speculum. They can also be examined with the little finger 
 or a probe, and in this way foreign bodies detected. A still more extensive examination can be 
 made by Roux's operation, which was introducerl for the cure of ozwna. This operation enables 
 the surgeon to remove any dead bone which may be present in this disease. The cartilaginous 
 framework of the nose is lifted up by an incision made inside the mouth, through the junction 
 
THE EYE 1103 
 
 of the upper lip with the bone; the septum nasi and the lateral cartilages are divided with strong 
 scissors till the anterior nares are completely exposed. The posterior nares can be explored by 
 the aid of reflected light from the mouth, by which the posterior nares can be illuminated. The 
 examination is very difficult to carry out, and, as a rule, sufficient information regarding the 
 presence of foreign bodies or tumors in the naso-pharynx can be obtained by the introduction 
 of the finger behind the soft palate through the mouth. The septum of the nose may be dis- 
 placed or deviate from the middle line: this may be the result of an injury or from some con- 
 genital defect in its development; in the latter case the deviation usually occurs along the line 
 of union of the vomer and mesethmoid, and rarely occurs before the seventh year. Sometimes 
 the deviation may be so great that the septum may come in contact with the outer wall of the 
 nasal fossa, and may even become adherent to it, thus producing complete obstruction. Per- 
 foration of the septum is not an uncommon affection and may arise from several causes: syphilitic 
 or tuberculous ulceration, blood-tumor or abscess of the septum, and especially in workmen 
 exposed to the vapor of bichromate of potash, from the irritating and corrosive action of fumes. 
 When small, the perforation may cause a peculiar whistling sound during respiration. When 
 large, it may lead to the falling in of the bridge of the nose. 
 
 Epistaxis is a very common affection in children. It is rarely of much consequence, and will 
 almost always subside, but in the more violent hemorrhages of later life it may be necessary 
 to plug the posterior nares. In performing this operation it is desirable to remember the size 
 of the posterior nares. A ready method of regulating the size of the plug to fit the opening 
 is to make it of the same size as the terminal phalanx of the thumb of the patient to be oper- 
 ated on. 
 
 Nasal polypus is a very common disease, and presents itself in three forms: the gelatinous, 
 the fibrous, and the malignant. The first is by far the most common. It grows from the mucous 
 membrane of the outer wall of the nasal fossa, where there is an abundant layer of highly vas- 
 cular submucous tissue; rarely from the septum, where the mucous membrane is closely adher- 
 ent to the cartilage and bone, without the intervention of much, if any, submucous tissue. The 
 most common seat of gelatinous polyps is probably the middle turbinated bone. The fibrous 
 polypus generally grows from the base of the skull behind the posterior nares or from the roof 
 of the nasal fossae. The malignant polypi, both sarcomatous and carcinomatous, may arise 
 in the nasal cavities and the naso-pharynx; or they may originate in the antrum, and protrude 
 through its inner wall into the nasal fossa. 
 
 Rhinoliths or nose-stones may sometimes be found in the nasal cavities. They arise from 
 the deposition of phosphate of lime upon either a foreign body or a piece of inspissated secretion. 
 
 The nasal passages furnish a secretion of their own and receive secretion from other parts 
 (tears and secretions of the accessory sinuses). The nasal cavities contain the ethmoidal laby- 
 rinths, the lateral masses of the ethmoid (which form the superior and middle turbinated bones), 
 and the inferior turbinated bones. The nasal cavity is surrounded by three pairs of pneumatic 
 spaces, the accessory sinuses. These are the maxillary sinuses, the frontal sinuses, and the 
 cells of the ethmoidal labyrinth. The lachrymal duct opens into the inferior meatus. Inflam- 
 mation of the air-cells may follow inflammation of the nasal mucous membrane or bone disease. 
 One set of cells or many may suffer. Suppuration may occur. Pus may be blocked up and 
 retained. Dead bone may form. The most serious conditions may follow (abscess of brain, 
 sinus thrombosis, septicaemia), and an operation is necessary to obtain relief. 
 
 THE EYE. 
 
 The eyeball or globe (hulhus oculi) (Figs. 712 and 716) is contained in the ante- 
 rior part of the cavity of the orbit. In this situation it is securely protected from 
 injury, whilst its position is such as to ensure the most extensive range of sight. 
 It is acted upon by numerous muscles, by which it is capable of being directed 
 to different parts; it is supplied by vessels and nerves, and is additionally pro- 
 tected in front by the orbital margins, eyelids, etc. 
 
 The eyeball is embedded in the fat of the orbit, but is partly surrounded by 
 a thin membranous sac, the capsule of T^non, which isolates it, so as to allow 
 of free movement. 
 
 The Fascia or Capsule of T^non (fascia hulhi [Tenon%\) (Figs. 712 and 
 713). — The fascia or capsule of Tenon consists of a thin membrane which 
 envelops the eyeball from the optic nerve to the ciliary region, separating it from 
 the orbital fat and forming a socket in which it plays. Its inner surface is smooth, 
 and is in contact with the outer surface of the sclerotic, the perisclerotic or supra- 
 
1104 
 
 THE ORGANS OF SPECIAL SENSE 
 
 scleral lymph-space only intervening. This lymph-space is continuous with the 
 subdural and subarachnoid spaces, and is traversed by delicate bands of con- 
 
 OPTIC NERVE 
 
 CAPSULE 
 OF TENON 
 
 Fig. 712. — The right eye in sagittal section, showing the capsule of Tenon (seniidiagrammatic). (Testut.) 
 
 nective tissue which extend between 
 the capsule and the sclerotic. This 
 lymph-space forms a flexible pocket, 
 in which the globe rotates. The cap- 
 sule of Tenon, with the globe, forms 
 a ball-and-socket joint (Deaver). 
 The capsule is perforated behind by 
 d the ciliary vessels and nerves and by 
 the optic nerve, being continuous with 
 the sheath of the latter. In front it 
 blends with the ocular conjunctiva, 
 and with it is attached to the ciliary 
 region of the eyeball. It is perforated 
 by the muscles which move the eye- 
 ball and on to each muscle it sends 
 a tubular sheath. The sheath of the 
 Superior oblique is carried as far as 
 
 Fig. 713^ -The capsule of T^non. The aponeurosis is the fibrOUS DulleV of that mUSclc; that 
 
 seen trom behind forward on the posterior hemisphere of , . „ ^^ ^ ,. , » 
 
 theglobe: a, cellulo-fibrous intermuscular laminae; 6, deep On the interior ObliqUC reaCheS aS tar 
 
 leaf of the sheath incised at the point where it leaves the .i a j? .i u"i i. U" U U 
 
 muscle to fold itself on the posterior hemisphere when aS the tlOOr Ot the OrDlt, tO WhlCh it 
 
 it forms the posterior capsule; d, partly incised; c, serous ',,^„ ^(s „ ^K^ T^U^ oU^o+Uc nn i\\a 
 
 membrane. (Poirier and Charpy.) glVCS OIT a Slip. i he ShCathS OU thC 
 
 recti are gradually lost in the peri- 
 mysium, but they give off important expansions. The expansion from the 
 Superior rectus blends with the tendon of the Levator palpebrae; that of the 
 
THE EYE 
 
 1105 
 
 Inferior rectus is attached to the inferior tarsal plate. These two recti, therefore, 
 will exercise some influence on the movements of the eyelids. The expansions 
 from the sheaths of the Internal and External recti are strong, especially the one 
 from the latter muscle, and are attached to the lachrymal and malar bones respec- 
 tively. As they probably check the action of these two recti, they have been 
 named the internal and external check ligaments. 
 
 Lockwood has also described a thickening of the lower part of the capsule of 
 Tenon, which he has named the suspensory ligament of the eye. It is slung like a 
 hammock below the eyeball, being expanded in the centre and narrow at its 
 extremities, which are attached to the malar and lachrymal bones respectively.^ 
 
 The anterior one-third of the globe is covered by the conjunctiva, or mucous 
 membrane, reflected from the inner surfaces of the lids (Fig. 715). A lateral view 
 
 
 VISUAL 
 
 OPTIC 
 
 
 
 
 AXIS 
 
 AXIS 
 
 
 
 POSTERIOR CHAMBER 
 
 /^>^ 
 
 -^SlT^v. 
 
 
 
 OF EYE . 
 
 X^NT. c\h 
 
 AM B E R^V 
 
 \ 
 
 OCULAR 
 CONJUNCTIVA 
 
 CILIARY -"^^^ ^ji^K^ 
 
 ''^ OF the! 
 
 EYE ^ 
 
 ^ 
 
 "N;;^^/ 
 
 p R o c E s s ■~>7<r^ra\'^ 
 
 t^A 
 
 N S ^^^ 
 
 5^ \^X CILIARY 
 ^^g--^i^-r-M U SC LE 
 
 
 
 J^ 
 
 
 "**^^^^^\ PARS CILIARI8 
 
 
 \ 
 
 y^ 
 
 
 ^5^. ^ RETINAE 
 
 ZONULE „J--J^'^ 
 
 
 ^^^^^,y^ 
 
 
 ^^\ 
 
 OF ZINN [ff 
 
 
 — 
 
 
 % .\— ORA SERRATA 
 
 EQUATORIAL 
 
 V ITR EOUS 
 
 DIAMETER 
 
 BODY" 
 
 PARS OPTICA 
 RETIN/E 
 
 SCLEROTIC 
 
 OPTIC, 
 
 papilla' 
 
 OPTIC 
 EXCAVATION 
 
 ^YELLOW 
 SPOT 
 
 EXTERNAL 
 AXIS 
 
 Fig. 714. — The right eye in horizontal section. (Toldt.) 
 
 of the globe shows that it is composed of segments of two spheres of different sizes 
 (Figs. 712, 714, 715, and 716). The anterior segment is one of a small sphere, and 
 forms about one-sixth of the eyeball. It is more prominent than the posterior seg- 
 ment, which is one of a much larger sphere, and forms about five-sixths of the globe. 
 The segment of the larger sphere is opaque, and formed by the sclerotic, the tunic 
 of protection to the eyeball ; the smaller sphere is transparent, and formed by the 
 cornea. Between the small, anterior or corneal segment, and the large, posterior 
 or scleral segment, is a shallow and narrow groove, the scleral sulcus {sulcus sclerae). 
 The anterior pole is the centre of the anterior portion of the cornea. The posterior 
 pole is the centre of the posterior portion of the sclerotic. A straight line joining 
 
 * See a paper by C. B. Lockwood, Journal of Anatomy and Physiology, vol. xx., part i. p. 1. — Ed. of 15th 
 English edition. 
 
 70 
 
1106 
 
 THE ORGANS OF SPECIAL SENSE 
 
 these two poles is the sagittal or optic axis {axis optica) (Fig. 714). A line drawn 
 around the eyeball equally distant at all points from the two poles is called the 
 equatorial diameter or the equator (Fig. 714). The plane of the equator divides 
 the globe in an anterior and a posterior hemisphere. Meridians may be drawn from 
 one pole to the other at right angles to the equator. The visual axis (linea visus) 
 (Fig. 714) passes in a straight line from the first nodal point on the cornea to the 
 fovea centralis of the yellow spot on the retina. A nodal point is the point of inter- 
 section of convergent rays with the visual axis. The first nodal point is 6.9685 mm. 
 
 POSTERIOR CH,^MBER 
 
 Fig. 715.- 
 
 -Diagram of a horizontal section of the right eye, showing the upper surface of the lower 
 segment. (Testut.) 
 
 behind the summit of the cornea. The axes of the eyeballs are nearly parallel, 
 and therefore do not correspond to the axes of the orbits, which are directed 
 outward. The optic nerves follow the direction of the axes of the orbits, and 
 are therefore not parallel; each nerve enters its eyeball about 1 mm. below and 
 3 mm. to the inner or nasal side of the posterior pole (Fig. 714). The eyeball 
 measures rather more in its transverse and antero-posteror diameters than in its 
 vertical diameter, the former amounting to nearly an inch, the latter to about 
 nine-tenths of an inch. The diameters in the female are somewhat less than 
 in the male. 
 The eyeball is composed of three investing tunics and of three refracting media. 
 
THE SCLERA 
 
 1107 
 
 THE TUNICS OF THE EYE. 
 
 From without inward the three tunics are: 
 
 I. Sclerotic Coat and Cornea. 
 II. Choroid, CiUary Body, and Iris. 
 III. Retina. 
 
 I. The Fibrous or External Coat: The Sclerotic and Cornea 
 (Tunica Fibrosa Oculi). 
 
 The sclerotic and cornea (Figs. 714, 715, and 716) form the external tunic of 
 the eyeball; they are essentially fibrous in structure, the sclerotic being opaque, 
 and forming the posterior five-sixths of the globe; the cornea, which forms the 
 remaining sixth, being transparent. 
 
 The Sclera or Sclerotic Coat {axXrjpoc:, hard).— The sclera or sclerotic coat 
 has received its name from its extreme density and hardness; it is a firm, unyield- 
 ing, opaque, fibrous membrane, forming the posterior five-sixths of the outer coat 
 
 Canal of Schlemm. 
 
 Posterior 
 chamber. 
 
 Ciliary 
 
 body. 
 
 Retina. \ 
 
 Choroid 
 coat. 
 
 Ciliary 
 processes. 
 
 Canal of 
 Petit. 
 
 rectus 
 musde. 
 
 and serving to maintain the form of the globe. It is much thicker behind than in 
 front. Its external surface is of a white color, and is in contact with the inner 
 surface of the capsule of Tdnon, a lymph-space intervening; it is quite smooth, 
 except one-quarter of an inch back of the sclero-corneal junction, at the points 
 where the Recti and Obliqui muscles are inserted into it, and its anterior part is 
 covered by the conjunctival membrane (Fig. 744) ; hence the whiteness and bril- 
 liancy of the front of the eyeball. Its inner surface is stained a brown color, marked 
 by grooves, in which are lodged the ciliary nerves and vessels (Figs. 719, 724, and 
 725) ; the inner surface of the sclera is loosely connected by three layers of exceed- 
 
1108 ^'^^ ORGANS OF SPECIAL SENSE 
 
 ingly fine cellular pigmented tissue {lamina fusca) with the outer surface of the 
 choroid, an extensive lymph-space, the perichoroidal space (spatium perichorioideale) 
 (Figs. 727and 744) intervening between the sclerotic and choroid. Behind the sclera 
 is pierced by the optic nerve (n. opticus) , and is continuous with the fibrous sheath 
 of the nerve, which is derived from the dura mater (Fig. 721). At the point where 
 the optic nerve passes through the sclerotic, the lamina fusca is represented by an 
 arrangement of the fibrous tissue which forms a thin network, the cribriform lamina 
 {lamina cribrosa sclerae) (Fig. 731) ; the minute orifices in this network serve for the 
 transmission of separate bundles of nervous filaments, and the fibrous septa divifl- 
 ing them from one another are continuous with the membranous processes which 
 separate the bundles of nerve-fibres. One of these openings {porus opticus), larger 
 than the rest, occupies the centre of the lamella; it transmits the arteria centralis 
 retinae to the interior of the eyeball (Fig. 731). Around the cribriform lamella are 
 numerous small apertures for the transmission of the ciliary nerves and the short 
 ciliary arteries, and about midway between the margin of the cornea and the entrance 
 of the optic nerve are four or five large apertures, for the transmission of veins {venae 
 vorticosae) (Fig. 721) . In front, the fibrous tissue of the sclerotic is continuous with 
 the substantia proporia, the cornea by direct continuity of tissue (Fig, 744) , but the 
 opaque sclerotic slightly overlaps the outer surface of the transparent cornea. In 
 the depths of the line of junction between the cornea and the sclera there is a circular 
 canal, the canal of Schlemm {sinu^ venosus sclerae) (Figs. 716, 723, 727, and 744). 
 This canal receives the sclera veins (Fig. 723) and communicates internally by num- 
 erous minute openings in the pectineal ligament of the iris (Fig. 744) with the ante- 
 rior chamber of the eyeball. These openings are the spaces of Fontana (Fig. 727). 
 
 Structure. — The sclerotic is formed of white fibrous tissue intermixed with fine 
 elastic fibres, and of flattened connective-tissue corpuscles, some of which are pig- 
 mented, contained in cell-spaces between the fibres (Figs. 720 and 731). These 
 fibres are aggregated into bundles, some of which are arranged in layers having an 
 equatorial direction, but most of which are arranged in layers lying in meridian lines. 
 The sclera is joined to the choroid by three thin layers of loose connective tissue con- 
 taining pigment cells, the lamina fusca {lamina fasciae sclerae) (Fig. 724) . Where 
 the optic nerve passes through the sclera there is very thin network to represent the 
 lamina fusca. This network is the lamina cribrosa (Fig. 731). The muscles of 
 the eyeball are attached to the sclera (Figs. 715, 716, and 744), and their tendons 
 enter among the bundles of fibrous connective tissue. The conjunctiva covers the 
 anterior portion of the sclera and is attached to it by submucous tissue (Figs. 715 
 and 727) . The sclera yields gelatin on boiling. Its vessels (Figs. 721 and 723) are not 
 numerous, the capillaries being of small size and uniting at long and wide intervals. 
 It obtains arterial blood from the short posterior ciliary and the anterior ciliary 
 arteries. The venous blood is removed by the venae vorticosae and the anterior ciliary 
 veins. There are lymph-spaces between the cells which empty into the periscleral 
 (Fig. 712 and p. 1104) and perichoroidal lymph-spaces (Fig. 727). Its nerves are 
 derived from the ciliary nerves (Fig. 719). They lose their medullary sheaths and 
 enter among the bundles of fibrous tissue, but it is not known how they terminate. 
 
 The Cornea (Figs. 712, 715, and 721). — The cornea is the projecting transparent 
 part of the external tunic of the eyeball, and forms the anterior sixth of the globe. It 
 is almost, but not quite, circular in shape, occasionally a little broader in the transverse 
 than in the vertical direction. It is convex anteriorly, and projects forward from 
 the sclerotic in the same manner that a watch-glass does from the case. Its degree 
 of curvature varies in different individuals, and in the same individual at different 
 periods of life, it being more prominent in youth than in advanced life, when it 
 becomes flattened. Usually the curvature is slightly greater in the vertical plane 
 than in the horizontal plane; at its centre than at its periphery, and at its temporal 
 than at its nasal side. The cornea is dense and of uniform thickness throughout; 
 
THE CORNEA 
 
 1109 
 
 its posterior surface is perfectly circular in outline, and exceeds the anterior sur- 
 face slightly in extent, from the latter being overlapped by the sclerotic. The 
 anterior surface is covered with conjunctiva (Fig. 727). 
 
 Structure (Fig. 717). — The cornea consists of five layers — namely: (1) the anterior 
 or epithelial layer; (2) the anterior elastic layer; (3) the substantia propria; (4) 
 the posterior elastic layer; (5) 'the posterior or endothelial layer. 
 
 Anterior 
 epithelium 
 
 Anterior 
 
 ■""^-w. I ■>! elastic 
 
 membrane 
 
 -j 
 
 L. 
 
 ^ J V Substantia 
 ~^"^, f propria 
 
 mmmm 
 
 FiQ. 717. — Vertical section through the cornea of a newborn child. X 200. 
 
 Posterior 
 epithelium 
 (Saymonowicz.) 
 
 (1) The Anterior Layer (epithelium corneae) is composed of stratified epithelium 
 and is continuous with the cells of the conjunctiva at the borders of the cornea. 
 There are from five to eight strata of nucleated cells in the anterior layer. The 
 deepest cells are columnar. Above the columnar cells are several layers of 
 polygonal cells, most of which have finger-like processes and are called prickle 
 cells. At the surface the cells and nuclei become flat. The anterior epithelial 
 layer prevents the absorption of the fluid of the tears. 
 
 (2) The Anterior Elastic or Anterior Limiting Layer or Bowman's Membrane (lamina 
 elastica anterior) is less than half the thickness of the layer of stratified epithelium. 
 
1110 
 
 THE ORGANS OF SPECIAL SENSE 
 
 It differs in some essential respects from true elastic tissue. It shows evidences 
 of fibrillary structure, and does not have a tendency to curl inward or to undergo 
 fracture when detached from the other layers of the cornea. It consists of ex- 
 tremely close interwoven fibrils, similar to those found in the rest of the cornea 
 proper, but contains no corneal corpuscles. It ought, therefore, to be regarded 
 as a part of the proper tissue of the cornea. 
 
 (3) The Substantia Propria or proper substance of the cornea forms the main 
 thickness of that structure. It is fibrous, tough, unyielding, perfectly transparent, 
 and continuous with the sclerotic. It is composed of about sixty flattened lamellae, 
 superimposed one on another. These lamellae are made up of bundles of modified 
 connective tissue, the fibres of which are directly continuous with the fibres of the 
 sclerotic. The fibres of each lamella are for the most part parallel with each 
 other; those of alternating lamellae at right angles to each other. Fibres, however, 
 frequently pass obliquely from one lamella to the next {fihrae arcuatae). 
 
 The lamellae are connected with each other by an interstitial cement-substance, 
 in which are spaces, the corneal spaces, cell spaces or lacunae (Fig. 718). The 
 spaces are stellate in shape, and have numerous offsets or canaliculi (Fig. 718), 
 by which they communicate with each other. Each space contains a cell, the 
 corneal corpuscle (Fig. 718), which resembles in form the space in which it is 
 
 Lymph eannUculi 
 
 Corneal cell in 
 lymph sjyace 
 
 Fig. 718. — From a horizontal section of an ox's cornea. Positive picture of the canal system demonstrated 
 by the gold chloride method. X 450. (Szymonowicz.) 
 
 lodged, but it does not entirely fill it, the remainder of the space containing 
 lymph. In the aged the margin of the cornea becomes opaque gray. This rim 
 is called the arcus senilis, and is due to fat deposit in the lamellae and corneal 
 corpuscles. 
 
 (4) The Posterior Elastic Lamina, the Membrane of Descemet, or the Membrane 
 of Demours {lamina elastica 'posterior), which covers the proper structure of the 
 cornea behind, presents no structure recognizable under the microscope. It 
 consists of an elastic, and perfectly transparent homogeneous membrane, of 
 extreme thinness, which is not rendered opaque by either water, alcohol, or acids. 
 It is very brittle, but its most remarkr.ble property is its extreme elasticity, and 
 the tendency which it presents to curl up, or roll upon itself, with the attached 
 surface innermost, when separated from the proper substance of the cornea. Its 
 use appears to be (as suggested by Dr. Jacob) "to preserve the requisite perma- 
 nent correct curvature of the flaccid cornea proper." 
 
 At the margin of the cornea this posterior elastic membrane breaks up into fibres 
 to form a reticular structure at the outer angle of the anterior chamber, the intervals 
 between the fibres forming small cavernous spaces, the spaces of Fontana (spatia 
 
THE CHOROID 1111 
 
 anguli iridis) (Fig. 727). These little recesses communicate with a circular canal 
 in the deeper parts of the corneo-scleral junction. This is the canal of Schlemm 
 (sinus venosus sclerae) (Figs. 716, 723, and 727) ; it communicates internally with 
 the anterior chamber through the spaces of Fontana, and externally with the 
 scleral veins. Some of the fibres of this reticulated structure are continued into 
 the front of the iris, forming the ligamentum pectinatum iridis; while others are 
 connected with the forepart of the sclerotic and choroid. 
 
 (5) The Posterior Layer or the Corneal Endothelium (endothelium camerae ante- 
 rioris) lines the aqueous chamber and prevents the absorption of the aqueous 
 humor. It covers the posterior surface of the elastic lamina, is reflected on to 
 the front of the iris, and also lines the spaces of Fontana. It consists of a single 
 layer of polygonal flattened transparent nucleated cells, similar to those lining 
 other serous cavities. 
 
 Arteries and Nerves. — The foetal cornea contains blood-vessels which pass from 
 the margin almost to the centre. The adult cornea contains no blood-vessels, 
 except at its margin. The capillaries from the sclera and conjunctiva form loops 
 at the corneal margin, and many of these loops enter the cornea for a distance of 
 1 mm. (Fig. 723). The balance of the cornea is non-vascular and obtains its 
 nourishment from the lymph in the lacunae and canaliculi. Lymphatic vessels 
 have not as yet been demonstrated in it, but are represented by the channels in 
 which the bundles of nerves run; these channels are lined by endothelium and are 
 continuous with the cell-spaces. The nerves are numerous, twenty-four to thirty- 
 six in number (Kolliker), forty to forty-five (Waldeyer and Siimisch); they are 
 derived from the ciliary nerves; they form the annular plexus (plexus annularis), 
 at the corneal margin, and enter the laminated tissue of the cornea, lose their 
 medullary sheaths, and ramify throughout the substantia propria as the funda- 
 mental plexus or the plexus of the stroma. From this deep plexus come perforating 
 fibres (fibrae perforantes) , which pass through the anterior elastic lamina and form 
 the subepithelial plexus, and from it fibrils are given off which ramify between 
 the epithelial cells, forming a network which is termed the intra-epithelial plexus. 
 Nerve-fibres from the annular plexus and from the plexus of the stroma come 
 into close relation with the corneal corpuscles. 
 
 Dissection. — In order to separate the sclerotic and cornea, so as to expose the second tunic, 
 the eyeball should be immersed in a small vessel of water and held between the finger and thumb. 
 The sclerotic is then carefully incised, in the equator of the globe, till the choroid is exposed. 
 One blade of a pair of probe-pointed scissors is now introduced through the opening thus made, 
 and the sclerotic divided around its entire circumference, and removed in separate portions. 
 The front segment being then drawn forward, the handle cf the scalpel should be pressed gently 
 against it at its connection with the iris, and, these being separated, a quantity of perfectly trans- 
 parent fluid will escape; this is the aqueous humor. In the course of the dissection the ciliary 
 nerves (Fig. 719) may be seen lying in the loose cellular tissue between the choroid and sclerotic 
 or continued in delicate grooves on the inner surface of the latter membrane. 
 
 II. The Choroid, Ciliary Body, and Iris, the Tunica Media, the Uveal Tract 
 (Tunica Vasculosa Oculi) (Figs. 714, 716, 719, 724, 744). 
 
 The second or middle tunic of the eye is formed from behind forward by the 
 choroid, the ciliary body, and the iris. 
 
 The choroid is the vascular and pigmentary tunic of the eyeball, investing the 
 posterior five-sixths of the globe, and extending as far forward as the ora serrata 
 of the retina; the ciliary body connects the choroid to the circumference of the 
 iris. The iris is the circular muscular septum, which hangs vertically behind the 
 cornea, presenting in its centre a large rounded aperture, the pupil. 
 
 The Choroid (chorioidea). — The choroid is a thin, highly vascular membrane, 
 of a dark-brown or chocolate color, which invests the posterior five-sixths of the 
 
1112 
 
 THE ORGANS OF SPECIAL SENSE 
 
 globe, and is pierced behind by the optic nerve, and in this situation is firmly 
 adherent to the sclerotic. It is thicker behind than in front. Externally, it is 
 
 loosely connected by the lamina 
 fusca with the inner surface of the 
 sclerotic (p. 1108). Its inner sur- 
 face is attached to the retina. 
 
 Structure (Fig. 720).— The choroid 
 consists of a dense capillary plexus 
 and of small arteries and veins, 
 carrying the blood to and returning 
 it from this plexus (Fig. 723), and of 
 branched and pigmented cells which 
 lie in connective tissue. There are 
 three layers in the choroid. Named 
 from without inward, they are the 
 lamina suprachorioidea, the choroid 
 proper, and lamina basalis (Fig. 720) . 
 (1) The Lamina Suprachorioidea 
 is on the external surface, that is, 
 the surface next to the sclerotic. 
 
 It resembles the lamina fusca of 
 
 the sclerotic. It is composed of 
 
 delicate non-vascular lamellae, each 
 
 lamella consisting of a network of 
 
 fine elastic fibres, among which are 
 
 branched pigment-cells. The spaces 
 
 between the lamellae are lined by 
 
 endothelium, and open freely into the perichoroidal lymph-space, which, in its 
 
 turn, communicates with the periscleral space by the perforations in the sclerotic 
 
 through which the vessels and nerves are transmitted. 
 
 (2) The Choroid Proper is internal to the lamina suprachorioidea. In consequence 
 of the small arteries and veins of the choroid proper being arranged on the outer 
 surface of the capillary network, it is customary to describe this as consisting of 
 two layers: the outermost (lamina vasculosa), composed of small arteries and 
 
 Pigment layer 
 of retina 
 
 Fig. 719. — The choroid and iris. (Enlarged.) 
 
 Lamina supra- 
 chorioidea 
 
 Part of the 
 sclera 
 
 Fig. 720. — Vertical section through the chorioidea and a part of the sclera of an ape. X 440. (Szymonowicz.) 
 
 veins, with pigment-cells interspersed between them, and the inner (lamina 
 choriocapillaris) , consisting of a capillary plexus. The external layer of the choroid 
 proper or the lamina vasculosa consists, in part, of the larger branches of the short 
 
THE CHOROID 
 
 1113 
 
 posterior ciliaxy arteries (Figs. 721, 723, and 725), which run forward between the 
 veins, before they bend inward to terminate in the capillaries; but this layer is 
 
 VENA 
 VORTICOSA 
 
 SCLEROTIC 
 
 CILIARY ARTERY 
 
 POSTERIOR 
 CILIARY 
 ARTERIES 
 
 Fig. 721. — Vessels and nerves of the choroid and iris, seen from above, 
 been largely removed. (Testut.) 
 
 The sclerotic and cornea have 
 
 formed principally of veins, which have a whirl-like arrangement and empty into 
 four or five large equidistant trunks, the venae vorticosae (Figs. 721, 722, and 723), 
 which pierce the sclerotic midway 
 between the margin of the cornea 
 and the entrance of the optic 
 nerve. Around the veins are 
 l3nnph-spaces. Interspersed be- 
 tween the vessels are dark star- 
 shaped pigment-cells, the offsets 
 from which, communicating with 
 similar branchings from neigh- 
 boring cells, form a delicate net- 
 work or stroma, which toward 
 the inner surface of the choroid 
 lo.ses its pigmentary chraacter. 
 The internal layer of the choroid 
 proper consists of an exceedingly 
 fine capillary plexus, formed by 
 the short ciliary vessels (Fig.723), 
 and is known as the tunic of 
 Ruysch (lamina choriocapillaris) . 
 The network is close, and finer at the hinder part of the choroid than in front. 
 About half an inch behind the cornea its meshes become larger, and are continuous 
 
 Fig. 722. — The veins of the choroid. (Enlarged.) 
 
1114 
 
 THE ORGANS OF SPECIAL SENSE 
 
 with those of the ciUary processes. These two laminae are connected by an interme- 
 diate stratum, which is destitute of pigment-cells and consists of fine elastic fibres. 
 On the inner surface of the lamina choriocapillaris is a very thin, structureless, 
 or, according to Kolliker, faintly fibrous membrane, called the lamina basalis 
 or membrane of Bruch; it is closely connected with the stroma of the choroid, and 
 separates it from the pigmentary layer of the retina. 
 
 hff, 
 
 Cornea 
 
 Fig. 723. — Diagram of the blood-vessels of the eye, as seen in a horizontal section. (Leber, after StShr.) 
 
 Course of vasa centralia retinae: n, arteria, a\ vena centralis retinae; p, anastomosis with vessels of outer 
 coats; y, anastomosis with branches of short posterior ciliary arteries; (], anastomosis with chorioideal vessels. 
 
 Course of vasa cihar. postic. brev. : I, arteriae, and Ij, venae ciliar. postic. brev.; II, episcleral artery; 
 II], episcleral vein; III, capillaries of lamina choriocapillaris. 
 
 Course of vasa ciliar. postic. long.: 1, a. ciliar. post, longa; 2, circulus iridis major cut across; 3, branches to 
 ciliary body; 4, branches to iris. 
 
 Course of vasa ciUar. ant.: a, arteria, a\, vena ciliar. ant.; b, junction with the circulus iridis major; c, junc- 
 tion with lamina choriocapill.; d, arterial, and dj, venous episcleral branches; e, arterial, and Cj, venous branches 
 to conjunctiva sclerae; /, arterial, and/i, venous branches to corneal border; V, vena vorticosa; S, transverse 
 section of sinus venosus sclerae. 
 
 Tapetum (lucidum). — This name is applied to the iridescent appearance which 
 is seen in the outer and posterior parts of the choroid of many animals, but not 
 in man. 
 
 The ciliary body should now be examined. It may be exposed, either by detaching the iris 
 from its connection with the Ciliary muscle, or by making a transverse section of the globe, and 
 examining it from behind. 
 
THE CILIARY BODY 1115 
 
 The Ciliary Body (corpus ciliare) (Fig. 716). — The ciliary body or cyclon joins 
 the choroid to the margin of the iris. It is in reahty a process of the choroid 
 or uveal tract and comprises the orbiculus ciliaris, the ciliary processes, and the 
 Ciliary muscle. 
 
 The Orbiculus Ciliaris or Annulus Ciliaris (Figs. 724, 726, and 742).— The 
 orbiculus ciliaris is a zone of about one-sixth of an inch in width, directly con- 
 tinuous with the anterior part of the choroid. The lamina basalis presents 
 numerous ridges arranged in a radial manner. The depressions between the 
 ridges are filled with retinal pigment epithelium (Szymonowicz). The orbiculus 
 contains no lamina choriocapillaris. 
 
 The Ciliary Processes (processus ciliares) (Figs. 714, 716, 726, and 744). — The 
 ciliary processes are formed by the plaiting and folding inward of the various 
 layers of the choroid — i. e., the choroid proper and the lamina basalis — at its 
 anterior margin, and are received between corresponding foldings of the suspen- 
 sory ligament of the lens, thus establishing a connection between the choroid and 
 inner tunic of the eye. They are arranged in a circle, and form a sort of plaited 
 frill, the corona ciliaris, behind the iris, 
 round the margin of the lens (Figs. 726 
 
 and 744). They vary between sixty and ""*\%\\ .cm a r is* 
 
 eighty in number, lie side by side, and ciliary Jpl!^^^^/ .orbiculus 
 
 may be divided into large and small; -li^s^samn^ — .^^ciliaris 
 
 the latter, consisting of about one-third 
 of the entire number, are situated in the l^^BBilli l™"''W1liiHE^^*^^°lVJ'J°" 
 
 ' *t^«^^^^BB»lHi\. liiJll^^m.^S^ SMOOTH 
 
 spaces between the former, but without ^S^BK^mlimlMUS^^^ portion 
 
 '- I 1 r^^^ 1 ^^f^^^^aMHHHHi^rX O^ CHOROID 
 
 regular alternation, i he larger processes 
 are each about one-tenth of an inch in 
 length, and are attached by their per- 
 iphery to three or four of the ridges of 
 the orbiculus ciliaris, and are continu- cornea (pos 
 
 ous with the layers of the choroid; the terior surface)" 
 
 Opposite margin is free, and rests upon Fig. 724.— The middle or vascular coat of the eyeball 
 
 the circumference of the lens. Their IKlnd^b^f^^^'^ffoidu' '^'' ^"'^ °'"'^"*'^" '"■°" 
 anterior surface is turned toward the 
 
 back of the iris, with the circumference of which they are continuous. The 
 posterior surface is connected with the suspensory ligament of the lens. 
 
 Structure. — The ciliary processes are similar in structure to the choroid, but the 
 vessels are larger, and have chiefly a longitudinal direction. They are the most 
 vascular portion of the eyeball. The processes are covered on their inner surface 
 by two strata of black pigment-cells, which are continued forward from the retina, 
 and are named the pars ciliaris retinae (Figs. 720 and 727) . In the stroma of the 
 ciliary processes there are also stellate pigment-cells, which, however, are not so 
 numerous as in the choroid itself. 
 
 The Ciliary Muscle or Bowman's Muscle (m. ciliaris) (Figs. 719, 721, 725, 
 727, 728, and 729). — The ciliary muscle consists of unstriped fibres; it forms 
 a grayish, semitransparent, circular band, about one-eighth of an inch broad, 
 on the outer surface of the forepart of the choroid, between the choroid and 
 the iris and back of the sclero-corneal junction. It is thickest in front and 
 gradually becomes thinner behind. It consists of two sets of fibres, radiating and 
 circular. 
 
 The Radiating Fibres (fibrae meridianales [Bruckei]) (Figs. 727 and 744) , much 
 the more numerous, arise at the point of junction of the cornea and sclerotic, and 
 partly also from the ligamentum pectinatum iridis, and, passing backward, are 
 attached to the choroid opposite to the ciliary processes. One bundle, according 
 to Waldeyer, is continued backward to be inserted into the sclerotic. 
 
1116 
 
 THE ORGANS OF SPECIAL SENSE 
 
 The Circular Fibres (fibrae circulares [Mulleri]) (Figs. 727 and 744) are internal to 
 the radiating ones and to some extent unconnected with them, and have a circular 
 course around the attachment of the iris. They are sometimes called the "ring 
 muscle" of Muller, and were formerly described as the ciliary ligament. They are 
 well developed in hypermetropic, but are rudimentary or absent in myopic eyes. 
 
 Anterior ciliary artery. 
 
 Short ciliary arteri 
 
 ior ciliary artery. 
 
 Fig. 725. — The arteries of the choroid and iris. The .sclerotic has been mostly removed. (Enlarged.) 
 
 The Ciliary muscle is admitted to be the chief agent in accommodation — i. e., in 
 adjusting the eye to the vision of near objects. Bowman believed that this was 
 effected by its compressing the vitreous body, and so causing the lens to advance. 
 At the present time all agree that the chief element in accommodation is altered 
 curvature of the lens, but there is diversity of opinion as to the manner in which 
 
 ORBICULARIS 
 CILIARIS 
 
 CILIARY 
 PROCESSES 
 
 s (poste- 
 lor surface) 
 
 EQUATOR 
 OF LENS 
 
 Fig. 726. — -A portion of the corona ciliaris magnified. The ciliary processes and the ciliary folds. (Toldt.) 
 
 this is accomplished. The view which now prevails is that of Helmholtz. He 
 maintained that in an unaccommodated eye the capsule and suspensory ligament 
 of the lens are tense, and their pressure flattens the anterior surface of the lens, 
 and parallel rays (and rays from objects far off are practically parallel) "are 
 focused on the retina without any sense of effort."^ 
 
 "In accommodation for a near object the meridional or antero-posterior fibres 
 
 ' Stewart, Manual of Physiology. 
 
THE IRIS 
 
 1117 
 
 of the ciliary muscle by their contraction pull forward the choroid and relax the 
 suspensory ligament. The elasticity of the lens at once causes it to bulge forward 
 till it is again checked by the tension of the capsule."* The pupil is at the same 
 time slightly contracted. 
 
 The Iris {iris, a rainbow) (Figs. 716, 719, 721, 723, 724, 727, 728, 729, 730, and 
 744). — The iris has received its name from its various colors in different individ- 
 uals. It is a thin, circular-shaped, contractile curtain, suspended in the aqueous 
 humor behind the cornea, and in front of the lens, being perforated a little to the 
 nasal side of its centre by a circular aperture, the pupil (pupilla) (Fig. 730) , for 
 the transmission of light. The pupil of a living person varies in size under the 
 influence of light and in efforts at accommodation. In looking at a near object the 
 pupil is small ; in looking at a distant object it is large. In light the pupil contracts, 
 in darkness it dilates; hence the pupil is a window which permits light to pass into 
 the interior of the eye. The size of this window depends on the contraction or 
 relaxation of the iris. The iris divides the aqueous chamber (the space between 
 
 Circ. fibres 
 of sclerotic. 
 
 Circ. fibres / 
 of Ciliary mttscle. 
 
 Radiating 
 
 fibres of 
 
 Ciliary muscle. 
 
 ( Pars ciliaris 
 \ retinae. 
 
 Fig. 727. — Section of the eye, showing the relations of the cornea, sclerotic, and iris, together with the Ciliary- 
 muscle and the cavernous spaces near the angle of the anterior chamber. (Waldeyer.) 
 
 the cornea and lens) into an anterior chamber and a posterior chamber which com- 
 municate through the pupil (Figs. 714 and 716). By its circumference or ciliary mar- 
 gin (marge ciliaris) (Figs. 727 and 728) the iris is continuous with the ciliary body, 
 and it is also connected with the posterior elastic lamina of the cornea by means of 
 the pectinate ligament (ligamentum 'pectinatum iriclis) (Fig. 744). The pectinate 
 ligament of the iris is derived from the posterior elastic layer of the cornea. This 
 layer divides into numerous fibrillae and some of them reach the iris, and bridge 
 the angle between the cornea and base of the iris (Deaver). The fibrillae which 
 reach the iris constitute the ligament. In this ligament are numerous lymph- 
 spaces, the spaces of Fontana (spatia anguli iridis \Fontanae\) (Fig. 727), and 
 they join the canal of Schlemm to the anterior chamber of the eye. The inner or 
 free edge of the iris forms the margin of the pupil, and is called the pupillary 
 margin (margo pupillaris) (Fig. 728). The surfaces of the iris are flattened, and 
 
 * Stewart, Manual of Physiology. 
 
1118 
 
 THE ORGANS OF SPECIAL SENSE 
 
 look forward and backward, the anterior toward the cornea, the posterior toward 
 the ciHary processes and lens. The iris is pigmented and the color of an individual's 
 eyes depends upon this pigment. The anterior surface (fades anterior) (Figs. 728 
 and 744) of the iris is variously colored in different individuals, and is marked by 
 lines which converge toward the pupil. The posterior surface (fades posterior) (Figs. 
 726 and 744) is of a deep-purple tint, from being covered by two layers of pig- 
 mented, columnar epithelium, which layers are continuous posteriorly with the 
 pars ciliaris retinae. This pigmented epithelium is termed the pars iridica retinae, 
 though it is sometimes named uvea, from its resemblance in color to a ripe grape. 
 Structure. — The iris is composed of the following structures: 
 
 1. In front is a layer of flattened endothelial cells placed on a delicate hyaline 
 basement-membrane. This layer is continuous with the endothelial layer covering 
 the membrane of Descemet, and in men with dark-colored irides the cells contain 
 pigment-granules. 
 
 2. Stroma (stroma iridis). — The stroma consists of fibres and cells. The former 
 are made of fine, delicate bundles of fibrous tissue, of which some few fibres have 
 
 CILIARY GANGLIATED 
 PLEXUS 
 
 
 CILIARY MARGIN 
 OF IRIS 
 
 ^'\1/?^i ATTACHED 
 
 CILIARY ZONE 
 OF IRIS 
 
 REMNANT OF 
 
 CORNEAL 
 
 MARGIN 
 
 CIRCULUS 
 MINOR' 
 
 PUPILLARY ZONE 
 OF IRIS 
 
 CONTRACTINQ 
 FOLDS OF IRIS 
 
 VASCULAR 
 EMINENCES 
 
 LARGE 
 PIGMENT-CELL 
 
 FREE BORDER 
 "OF PIGMENTARY 
 LAYER 
 
 Fig. 728. — Section of the iris. Anterior surface magnified. (Toldt.) 
 
 PUPILLARY 
 MARGIN 
 
 a circular direction at the circumference of the iris, but the chief mass consists of 
 fibres radiating toward the pupil. They form, by their interlacement, a delicate 
 mesh, in which the vessels and nerves are contained. Interspersed between the 
 bundles of connective tissue are numerous branched cells with fine processes. 
 Many of them in dark eyes contain pigment-granules, but in blue eyes and the 
 pink eyes of albinos they are unpigmented. 
 
 3. The Muscular Fibre is involuntary and consists of circular and radiating 
 fibres. The circular fibres (m. sphincter pupillae) surround the margin of the pupil 
 on the posterior surface of the iris, like a sphincter, forming a narrow band about 
 one-thirtieth of an inch in width, those near the free margin being closely aggre- 
 gated; those more external somewhat separated, and forming less complete circles. 
 The radiating fibres (m. dilator pupillae) converge from the circumference toward 
 the centre, and blend with the circular fibres near the margin of the pupil. These 
 fibres are regarded by some as elastic, not muscular, but Grunnert positively 
 demonstrated them.^ The fibres are very small and are placed between the 
 stroma and the posterior layer of endothelium. 
 
 ' Von Graefe's Arch. f. Ophthal., Bd. xlvii. 
 
THE IBIS 
 
 1119 
 
 4. Pigment. — The situation of the pigment-cells differs in different irides. In 
 the various shades of blue eyes the only pigment-cells are several layers of small 
 round or polyhedral cells filled with dark pigment, situated on the posterior surface 
 
 CILIARY 
 GANGLIATED 
 
 ADICLE8 
 THE 
 VEINS 
 
 Fig. 729. — The ciliary gangliated plexus and the ciliary nerves entering the plexus. Outer surface of the 
 middle or vascular coat of the eyeball. (Toldt.) 
 
 of the iris and continuous with the pigmentary lining of the ciliary processes. The 
 color of the eye in these individuals is due to this coloring-matter showing more 
 or less through the texture of the iris. In the albino even this pigment is absent. 
 
 ANTERIOR CILIARY ARTERIES 
 
 LONG CILIARY 
 ARTERY 
 
 ANTERIOR CILIARY ARTERIES 
 
 Fig. 730. — Iris, front view. (Testut.) 
 
 In the gray, brown, and black eye there are, as mentioned above, pigment-granules 
 to be found in the cells of the stroma and in the endothelial layers on the front of 
 the iris; to these the dark color of the eye is due. • 
 
1120 THE ORGANS OF SPECIAL SENSE 
 
 The Arteries of the Iris (Figs. 723, 725, 727, and 739).— The arteries of the iris are 
 derived from the long posterior ciliary and anterior ciliary and f ron) the vessels of the 
 ciliary processes (see p. 1 1 15). The long posterior ciliaxy arteries (Figs. 721 and 723) , 
 two in number, pass through the sclera, one on the inner and one on the outer side 
 of the optic nerve, and pass forward between the sclera and choroid, and, having 
 reached the attached margin of the iris (Figs. 721 and 730), divide into an upper and 
 a lower branch, and, encircling the iris, anastomose with corresponding branches 
 from the opposite side ; into this vascular zone {circulus arteriosus major) (Fig. 744) 
 the anterior ciliary arteries (Fig. 744) , from the lachr3mial and anterior ciliary from the 
 muscular branches of the ophthalmic, pour their blood. From this zone vessels con- 
 verge to the free margin of the iris, and these communicate by branches from one 
 to another and thus form a second zone {circulus arteriosus minor) in this situation. 
 The veins pass toward the ciliary margin and communicate with the veins of the 
 ciliary processes and of the canal of Schlemm (Figs. 721 and 723). 
 
 The Nerves of the Choroid and Iris (Figs. 719, 721, and 729). — The nerves of the 
 choroid and iris are the short ciliary, the ciliary branches of the lenticular ganglion, 
 and the long ciliary from the nasal branch of the opthalmic division of the fifth. They 
 pierce the sclerotic around the entrance of the optic nerve, and run forward in the 
 perichoroidal lymph-space in which they form a plexus, from which plexus filaments 
 pass to supply the blood-vessels of the choroid. After reaching the iris they form 
 a plexus around its attached margin ; from this are derived non-medullated fibres 
 which terminate in the circular and radiating muscular fibres. Their exact mode 
 of termination has not been ascertained. Other fibres from the plexus terminate 
 in a network on the anterior surface of the iris. The fibres derived from the motor 
 root of the lenticular ganglion (third nerve) supply the circular fibres, while those 
 derived from the sympathetic supply the radiating fibres. 
 
 Membrana Pupillaris. — In the foetus the pupil is closed by a delicate transparent 
 vascular membrane, the membrana pupillaris, which divides the space into which 
 the iris is suspended into two distinct chambers. This membrane contains numer- 
 ous minute vessels, continued from the margin of the iris to those on the front part 
 of the capsule of the lens. These vessels have a looped arrangement, and converge 
 toward each other without anastomosing. Between the seventh and eighth months 
 the membrane begins to disappear, by gradual absorption from the centre toward 
 the circumference, and at birth only a few fragments remain. It is said some- 
 times to remain permanent and produce blindness. 
 
 III. The Tunica Interna or Retina (Figs. 723, 731, 733). 
 The retina is a delicate nervous membrane, in which the fibres of the optic nerve 
 are spread out and upon the surface of which the images of external objects are 
 received. Its outer surface is in contact with the choroid ; its inner with the vitreous 
 body. Behind, it is continuous with the optic nerve; it gradually diminishes in 
 thickness from behind forward; and, in front, extends nearly as far as the ciliary 
 body, where it appears to terminate in a jagged margin, the ora serrata (Figs. 723, 
 742, and 744) . Here the nervous tissues of the retina end, but a thin prolongation 
 of the membrane extends forward over the back of the ciliary processes and iris, 
 forming the para ciliaris retinae and pars iridica retinae already referred to (Figs. 727 
 and 744) . This forward prolongation consists of the pigmentary layer of the retina, 
 together with a stratum of columnar epithelium. The portion back of the ora 
 serrata is called the physiological retina {jpars optica retinae) (Fig. 744) . The retina 
 is soft, semitransparent, and of a purple tint in the fresh state, owing t( the presence 
 of a coloring-material named rhodopsin or visual purple; but it soon becomes 
 clouded, opaque, and bleached when exposed to sunlight. Exactly in the centre 
 of the front surface of the posterior part of the retina, corresponding to the visual 
 axis, and at a point in which the sense of vision is most perfect, is an oval yellowish 
 
THE TUNICA INTERNA OB RETINA 
 
 1121 
 
 spot, called, after its discoverer, the yellow spot of Sbminerring (macula lutea) (Figs. 
 714 and 733), having a central depression, the fovea centralis. The retina in the 
 situation of the fovea centralis is exceedingly thin, and the dark color of the choroid 
 is distinctly seen through it; so that it presents more the appearance of a foramen, 
 and hence the name foramen of Sommerring at first given to it. It exists only in 
 man, the quadrumana, and some saurian reptiles. About one-eighth of an inch (3 
 mm.) to the nasal side of the yellow spot and one-twenty-fourth of an inch below 
 it, is the point of entrance of the optic nerve, the optic disk (porus opticus) (Figs. 
 731 and 733). The circumference of the optic disk is slightly raised so as to form 
 an eminence, the optic papilla (colliculus nervi optici); the central portion is 
 depressed and is called the optic cup (excavatio papillae nervi optici). The arteria 
 centralis retinae pierces its centre. This is the only part of the surface of the retina 
 from which the power of vision is absent, and is termed the blind spot. 
 
 OPTIC 
 LAMINA CRIBROSR PAPILLA 
 
 POSTERIOR 
 SHORT CILIARY ^ 
 ARTERY AND 
 VEIN 
 
 PIAL 
 SHEATH 
 
 DURAL 
 SHEATH 
 ARACHNOID 
 SHEATH' 
 
 INTERVAGINAL 
 SPACES 
 
 eUNDLCS OF CENTRAL ARTERY AND 
 
 OPTIC NERVE VEIN OF RETINA 
 
 IIG. 731. — The terminal portion of the optic nerve and its entrance into the eyeball, in horizontal section. (Toldt.) 
 Structure. — The optical portion of the retina is an exceedingly complex structure, 
 nd, when examined microscopically by means of sections made perpendicularly 
 E) its surface, is found to consist of many layers of nervous structure. These ner- 
 ous structures are bound together and supported by the sustentacular fibres. 
 ?here are three layers: a middle or neuro-epitiielial layer, an inner layer, and an 
 outer or pigmentary layer. The neuro-epithelial layer is subdivided into four and 
 the middle layer into six layers; hence the retina consists of eleven layers. The 
 layers from within outward are as follows (Figs. 732, 734, 735, and 736) : 
 
 1. Membrana limitans interna. 
 
 2. Layer of nerve-fibres (stratum opticum). 
 
 3. Ganglionic layer, consisting of nerve-cells. 
 
 4. Inner molecular, or plexiform, layer. 
 
 5. Inner nuclear layer, or layer of inner granules. 
 
 6. Outer molecular, or plexiform, layer. 
 
 7. Henle's fibre-layer. 
 
 8. Outer nuclear layer, or layer of outer granules. 
 
 9. Membrana limitans externa. 
 
 10. Jacob's membrane (layer of rods and cones). 
 
 11. Pigmentary layer (tapetum nigrum). 
 71 
 
 1. Inner layer 
 
 2. Neuro-epithelial layer 
 
 3. Outer laver 
 
1122 
 
 THE ORGANS OF SPECIAL SENSE 
 
 1. The Membrana Limitans Interna (Figs. 732, 734, and 735), is the most internal 
 layer of the retina, and is in contact with the hyaloid membrane of the vitreous 
 
 Fibre of Muller.- 
 
 Pigmentary layer.- 
 
 Jacob's membrane. 
 
 Membrana limitans extei^na. 
 
 Outer nuclear layer. 
 
 Outer molecular layer. 
 
 Inner nuclear layer. 
 
 Inner molecular layer. 
 
 Ganglionic layer. 
 Layer of nerve-fibres. 
 
 Membrana limitans interna. 
 
 Fig. 732. — The layers of the retina with the exception of Henle's fibre-layer. (Diagrammatic.) (After Schultze.) 
 
 humor. It is derived from the sup- 
 porting framework of the retina, with 
 which tissue it will be described. 
 
 2. The Layer of Nerve-fibres (Figs. 
 732, 734, and 735) is formed by 
 the expansion of the optic nerve. 
 This nerve passes through all the 
 other layers of the retina, except 
 the membrana limitans interna, to 
 reach its destination. As the nerve 
 passes through the lamina cribrosa of 
 the sclerotic coat, the fibres of which 
 it is composed lose their medullary 
 sheaths and are continued onward, 
 through the choroid and retina, as 
 simple axis-cylinders. When these 
 
 ^"SL7LYf^o?tfe\yTbaii"bTntrttA^^^^^^ non-medulkted fibres reach the in 
 
 ternal surface of the retina, they radi 
 ate from their point of entrance over the surface of the retina, become grouped in 
 bundles, and in many places, according to Michel, arranged in plexuses. Most 
 of the fibres in this layer are centripetal, and are the direct continuations of the 
 
THE TUNICA INTERNA OB RETINA 
 
 1123 
 
 axis-cylinder processes of the cells of the next layer, A few of the fibres are 
 centrifugal, which are axis-cylinders of ganglion-cells within the brain. The cen- 
 trifugal fibres in the layer of nerve-fibres pass through it and the next succeeding 
 layer to ramify in the inner molecular and inner nuclear layers, where they termi- 
 nate in enlarged extremities. The layer is thickest at the optic nerve entrance, 
 and gradually diminishes in thickness toward the ora serrata. 
 
 3. The Ganglionic Layer or the Inner Ganglionic Layer (Figs. 732, 734, and 735) 
 consists of a single layer of large ganglion-cells; except in the macula lutea, 
 where there are several strata. The cells are somewhat flask-shaped, the rounded 
 internal margin of each cell resting on the preceding layer and sending off an axone 
 which is prolonged as a nerve-fibre into the fibrous layer. From the opposite 
 extremity numerous thicker processes (dendrites) extend into the inner molecular 
 layer, where they branch out into flattened arborizations at different levels. The 
 ganglion-cells vary much in size, and the dendrites of the smaller ones, as a rule. 
 
 r 
 
 TTI 
 
 ■¥ 
 
 P 
 
 Figs. 734 and 735. — Vertical sections of the human retina. Fig. 734, half an inch from the entrance of the 
 optic nerve. Fig. 735, close to the latter. 1. Layer of rods and cones, Jacob's membrane, bounded underneath 
 by the membrana limitans externa. • 2. Outernuclear layer. 3. Outer molecular layer. 4. Inner nuclear layer. 
 5. Inner molecular layer. 6. Ganglionic layer. 7. Layer of nerve fibres. 8. Sustentacular fibres of MUller. 
 9. Their attachment to the membrana limitans interna. 
 
 arborize in the inner molecular layer as soon as they enter it ; while the processes 
 of the larger cells ramify close to the inner nuclear layer. 
 
 4. The Inner Molecular, the Plexiform or the Inner Reticular Layer (Fig. 732, 734, 
 and 735) is made up of a dense reticulum of minute fibrils, formed by the inter- 
 lacement of the dendrites of the ganglion-cells with those of the cells contained in 
 the next layer, immediately to be described. Within the reticulum formed by 
 these fibrils a few branched spongioblasts are sometimes embedded. 
 
 5. The Inner Nuclear or Inner Granular Layer (Figs. 732, 734, and 735) is made up 
 of a number of closely packed cells, of which there are three different kinds. (1) A 
 large number of oval cells, which are commonly regarded as bipolar nerve-cells, and 
 are much more numerous than either of the other kind. They each consist of a 
 large oval body placed vertically to the surface, and containing a distinct nucleus. 
 The protoplasm is prolonged into two processes ; one of these passes inward into the 
 inner molecular layer, is varicose in appearance, and ends in a terminal ramification, 
 which is often in close proximity to the ganglion-cells (Fig. 736, i, c). The outer 
 process passes outward into the outer molecular layer, and there breaks up into a 
 
1 
 
 THE ORGANS OF SPECIAL SENSE 
 
 1 
 
THE TUNICA INTERNA OB BETINA . 1125 
 
 number of branches. According to Cajal, there are two varieties of these pipolar 
 cells : one in which the outer process arborizes around the knobbed ends of the 
 rod-fibres, and the inner around the cells of the ganglionic layer; these he calls rod- 
 bipolars (Fig. 736, i) ; the others are those in which the outer process breaks up in 
 a horizontal ramification, in contact with the end of a cone-fibre ; these are the 
 cone-bipolaxs, and their inner process breaks up into its terminal ramifications in 
 the inner molecular layer (Fig. 736, i). (2) At the innermost part of this inner 
 nuclear layer is a stratum of cells, which are named Cajal amacrine cells, from the 
 fact that they have no axis-cylinder process, but they give a number of short proto- 
 plasmic processes which extend into the inner molecular layer and there ramify 
 (Fig. 736, i). There are also at the outermost part of this layer some cells, the 
 processes of which extend into and ramify in the outer molecular layer. These 
 are the horizontal cells of Cajal. (3) Some few cells are also found in this layer, 
 connected with the fibres of Miiller and will be described with those structures. 
 
 6. The Outer Molecular or Outer Reticular Layer or the Plexiform Layer (Figs. 
 732, 734, and 735) is much thinner than the inner molecular layer; but, like it, 
 consists of a dense network of minute fibrils, derived from the processes of the 
 horizontal cells of the preceding layer and the outer processes of the bipolar cells, 
 which ramify in it, forming arborizations around the ends of the rod-fibres and 
 with the branched foot-plates of the cone-fibres. 
 
 7. Henle's Fibre Layer is a non-granular layer in the neighborhood of the macula 
 lutea, and is produced by elongations from the inner segments of rod-fibres and 
 cone-fibres. 
 
 8. The Outer Nuclear or Outer Granular Layer (Figs. 732, 734, and 735), like the 
 inner nuclear layer, contains several strata of clear oval nuclear bodies ; they are 
 of two kinds, and on account of their being respectively connected with the rods 
 and cones of Jacob's membrane (rod-fibres and cone-fibres) are named rod- 
 granules and cone-granules. 
 
 The rod-granules are much the more numerous, and are placed at different levels 
 throughout the layer. Their nuclei present a peculiar cross-striped appearance, 
 and prolonged from either extremity of the granule is a fine process; the outer 
 process is continuous with a single rod of Jacob's membrane; the inner passes 
 inward toward the outer molecular layer and terminates in an enlarged extremity. 
 
 DESCRIPTION OF FIG. 736. 
 
 I. Section of the dog's retina, a. Cone-fibre, b. Rod-fibre and nucleus, e, d. Bipolar cells (inner granules) 
 with vertical ramification of outer processes destined to receive the enlarged ends of rod-fibres. 
 e. Bipolar.s with flattened ramification for ends of cone-fibres. /. Giant bipolar with flattened raniifica- 
 tion. fir. Cell sending a neurone or nerve-fibre process to the outer molecular layer, h. Amacrine cell 
 with diffuse arborization in inner molecular layer, i. Nerve-fibrils passing to outer molecular layer. 
 j. Centrifugal fibres passing from nerve-fibre layer to inner molecular layer, m. Nervts-fibril passing 
 into inner molecular layer, n. Ganglionic cells. 
 
 II. Horizontal or basal cells of the outer molecular layer of the dog's retina. A. Small cell with dense arbori- 
 zation. B. Large cell, lying in inner nuclear layer, but with its processes branching in the outer 
 molecular, a. Its horizontal neurone. C. Medium-sized cell of the same character. 
 
 III. Cells from the retina of the ox. a. Rod-bipolars with vertical arborizations. 6, c, d, e. Cone-bipolars with 
 
 horizontal ramification of outer process, h. Cell lying on the outer surface of the outer molecular 
 layer, and ramifying within it. i,3,in,. Amacrine cells within the substance of the inner molecular 
 layer. 
 
 IV. Neurones or axis-cylinder processes belonging to horizontal cells of the outer molecular layer, one of them, 
 
 6, ending in a close ramification at a. 
 
 V. Nervous elements connected with the inner molecular layer of the ox's retina. A. Amacrine cell, with 
 
 long processes ramifying in the outermost stratum. B. Large amacrine with thick processes ramifying 
 in second stratum. C. Flattened amacrine with long and fine processes ramifying mainly in the first 
 and fifth strata. D. Amacrine with radiating tuft of fibrils destined for third stratum. E. Large 
 amacrine, with processes ramifying in fifth stratum. F. Small amacrine, branching into second 
 stratum. G, h. Other amacrines destined for fourth stratum, a. Small ganglion-cell sending its pro- 
 cesses to fourth stratum, b. A small ganglion-cell with ramifications in three strat.^. C. A small cell 
 ramifying ultimately in first stratum, d. A medium-sized ganglion-cell ramifying in fourth stratum. 
 e. Giant-cell, branching in third stratum. /. A bistratified ceil ramifying in second and fourth strata. 
 
 VI. Amacrines and ganglion-cells from the dog. A. Amacrine with radiating tuft. B. Large amacrine passing 
 
 to third stratum, c and G. Small amacrines with radiations in second stratum. F. Small amacrine 
 passing to third .stratum. D. Amacrine with diffuse arborization. E. Amacrine belonging to fourth 
 .stratum, a, d, e, g. Small ganglion-cells ramifying in various strata. b,f. Large ganglion-cells show- 
 ing two different characters of arborization, i. Bistratified cell. 
 VII. Amacrines and ganglion-cells from the dog. A, B, C. Small amacrines ramifying in middle of molecular 
 layer, b, d, g, h, i. Small ganglion-cells showing various kinds of arborization. /. A larger cell, similar 
 in character to g, but with longer branch, a, t^. e. Giant-cells with thick branches ramifying in the 
 first, second, and third layers. L, L. Ends of bipolars branching over ganglion-cells. 
 
1126 
 
 THE ORGANS OF SPECIAL SENSE 
 
 and is embedded in the tuft into which the outer process of the rod-bipolars break 
 up. In its course it presents numerous varicosities. 
 
 The cone-granules, fewer in number than the rod-granules, are placed close to the 
 membrana limitans externa, through which they are continuous with the cones of 
 Jacob's membrane. They do not present any cross-striping, but contain a pyri- 
 form nucleus which almost completely fills the cell. From their inner extremity a 
 thick process passes inward to the outer molecular layer, upon which it rests by a 
 somewhat pyramidal enlargement, from which are given off numerous fine fibrils, 
 
 A B 
 
 External 
 segment' 
 
 Intermediary 
 
 disc 
 Elliptoid- 
 
 I 
 
 EQy. 
 I l()i«. 
 
 Myoid- 
 Nucletis — 
 
 Fig. 737.— The cells of the rods of the 
 retina in the frog. A, red rod; JS, green 
 rod. (Poirier and Charpy.) 
 
 which enter the outer molecular 
 layer, where they come in con- 
 tact with the outer processes of 
 the cone-bipolars. 
 
 9. The Membrana Limitans 
 Externa (Figs. 732, 734, and 735) , 
 like the membrana limitans in- 
 terna, is derived from the fibres 
 of Miiller, with which structures 
 it will be described. 
 
 10. Jacob's Membrane or the 
 Layer of Rods and Cones (Figs. 
 732, 734, and 735) consists of 
 visual cells, and the elements 
 which compose it are of two 
 kinds, rod-cells and cone-cells, 
 the former being much more 
 numerous than the latter. 
 
 The rod-cells (Fig. 737) are of nearly uniform size, and arranged perpen- 
 dicularly to the surface. A rod-cell consists of a rod and a rod-fibre, and the 
 fibre contains the nucleus. The rods are cylindrical and each consists of two por- 
 tions, an outer segment and an inner segment, which are of about equal length. 
 The segments differ from each other as regards refraction and in their behavior 
 with coloring reagents, the inner portion becoming stained by carmine, iodine, etc., 
 the outer portion remaining unstained with these reagents, but staining yellowish- 
 brown with osmic acid . The outer portion of each rod is marked by transverse striae, 
 and is made up of a number of thin disks superimposed on one another. It also 
 
 Fig. 738. — Cones in the different regions of the retina. /, near 
 the ora serrata; //, at 3 mm. from the ora serrata; ///, at an 
 equal distance from the ora serrata and the papilla; IV, at the 
 periphery of the fovea centralis; V, in the fovea centralis; Vf, at 
 the centre of the fovea centralis; E, length of the external seg- 
 ment; /, length of internal segment; D, diameter of the internal 
 segment. (Poirier and Charpy.) 
 
THE TUNICA INTERNA OR RETINA 1127 
 
 exhibits faint longitudinal markings. The inner portion of each rod, at its deeper 
 part where it is joined to the outer process of the rod-granule, is indistinctly gran- 
 ular; its more superficial part presents a longitudinal striation, being composed of 
 fine, bright, highly refracting fibres. In most vertebrates the outer portion of the 
 inner segment contains a fibrous body, the ellipsoid of Krause. The visual purple, or 
 rhodopsin, is found only in the outer segments of the rods. At its inner end each rod 
 is prolonged into a very fine fibre, the rod-fibre, which contains a nucleus, and which 
 terminates in the outer nuclear layer, being somewhat enlarged at its termination. 
 
 The cone-cells (Fig. 738) are conical or flask-shaped, their broad ends resting 
 upon the membrana limitans externa, the narrow pointed extremity being turned 
 to the choroid. Each cone-cell consists of two parts, the cone and the cone-fibre. 
 
 The cones are shorter than the rods and exhibit an outer and an inner segment. 
 
 The outer segment is a short conical process, which, like the outer segment of a 
 rod, presents transverse striae. The inner segment resembles the inner portion 
 of the rods in structure, presenting a superficial striated and deeper granular part; 
 but differs from it in size, being bulged out laterally and presenting a flask shape. 
 
 The inner segment of the cone, as does the rod, contains an ellipsoid of Krause. 
 Each cone is prolonged into a cone-fibre, and at the junction of the cone with the 
 fibre is the nucleus of the cone-cell. The cone-fibre passes to the outer nuclear 
 layer, and terminates as an expansion from which very minute fibrils are given off. 
 The chemical and optical characters of the rod-cells and cone-cells are identical. 
 
 1 1 . The Pigmentary Layer or Tapetum Nigrum (Fig. 732) . — The most external layer 
 of the retina, formerly regarded as a part of the choroid, consists of a single layer 
 of hexagonal epithelial cells, loaded with pigment-granules. Each cell contains a 
 flattened nucleus in the outer portion of the cell which is free from pigment at this 
 point. These cells are smooth externally, where they are in contact with the 
 choroid, but internally they are prolonged into fine, straight processes, which 
 extend between the rods, this being especially the case when the eye is exposed to 
 light. The pigment changes its position under the influence of light, and is dis- 
 tributed through the entire cell. In the eyes of albinos, the cells of the pigmentary 
 layer are present, but they contain no coloring-matter. In the eyes of many 
 mammals also, as in the horse, and many of the carnivora, there is no pigment 
 in the cells of this layer, and the choroid possesses a beautiful iridescent lustre, 
 which is termed the tapetum lucidum. 
 
 Supporting Framework of the Retina. — Almost all these layers of the retina are 
 connected together by a supporting framework, formed by the supporting cells or 
 supporting fibres of Miiller or radiating fibres, from which the membrana limitans 
 interna et externa are derived. These fibres are found stretched between the two 
 limiting layers (Fig. 732), "like columns between a floor and a roof," and they 
 Dass through all the nervous layers except Jacob's membrane. Each commences 
 on the inner surface of the retina by a conical hollow base, which sometimes 
 contains a spheroidal body which stains deeply with hsematoxylin, the edges of 
 the bases of adjoining fibres being united and thus forming a boundary line, which 
 is the membrana limitans interna. As they pass through the nerve-fibre and gan- 
 glionic layers they give off few lateral branches ; in the inner nuclear layer they give 
 off numerous lateral processes for the support of the inner granules, while in the 
 outer nuclear layer they form a network, the fibre-baskets, around the rod and 
 cone-fibrils, and unite to form the external limiting membrane at the bases of 
 the rods and cones. In the inner nuclear layer each fibre of Miiller presents a clear 
 oval nucleus, which is sometimes situated at the side of, sometimes altogether 
 within, the fibre. The supporting framework of the retina contains neuroglia cells. 
 
 The Path of Light Stimuli. — The stimulus is first received by the rod and cone- 
 cells (the visual cells), and is transmitted to the bipolar cells of the inner nuclear 
 layer and then to the cells of the ganglionic layer, which send fibres by way of the 
 optic nerve to the brain. 
 
1128 THE ORGANS OF SPECIAL SENSE 
 
 Macula Lutea and Fovea Centralis. — The structure of the retina at the yellow 
 spot presents some modifications. In the macula lutea (1) the nerve-fibres are 
 wanting as a continuous layer; (2) the ganglionic layer consists of several strata 
 of cells, instead of a single layer; (3) in Jacob's membrane there are no rods, but 
 only cones, and these are longer and narrower than in other parts; and (4) in the 
 outer nuclear layer there are only cone-fibres, which are very long and arranged 
 in curved lines. At the fovea centralis the only parts which exist are the cones 
 of Jacob's membrane, the outer nuclear layer, the cone-fibres of which are almost 
 horizontal in direction, and an exceedingly thin inner granular layer, the pigment- 
 ary layer, which is thicker and its pigment more pronounced than elsewhere. The 
 color of the macula seems to imbue all the layers except Jacob's membrane; it is 
 of a rich yellow, deepest toward the centre, and does not appear to consist of 
 pigment-cells, but simply a staining of the constituent parts. 
 
 At the Ora Serrata (Fig. 723) the nervous layers of the retina terminate abruptly, 
 and the retina is continued onward as a single layer of elongated colunmar cells 
 covered by the pigmentary layer. This prolongation is known as the pars ciliaris 
 retinae (Fig. 727) , and can be traced forward from the ciliary processes on to the 
 back of the iris, where it is termed the pars iridica retinae or uvea. 
 
 From the description given of the nervous elements of the retina it will be 
 seen that there is no direct continuity between the structures which form its differ- 
 ent layers except between the ganglionic and nerve-fibre layers, the majority 
 of the nerve-fibres being formed of the axones of the ganglionic cells. In the 
 inner molecular layer the dendrites of the ganglionic layer interlace with those 
 
 of the cells of the inner nuclear layer, while in the 
 outer molecular layer a like synapsis occurs between 
 the processes of the inner granules and the rod and 
 cone elements. 
 
 The Arteria Centralis Retinae (Figs. 723 and 731) 
 and its accompanying vein, vena centralis retinae, 
 pierce the optic nerve, and enter the globe of the eye 
 through the porus opticus. It immediately bifurcates 
 into an upper and a lower branch, and each of these 
 mo^ve'd STh^eVin'thrfresh'^state". ^g^i" dividcs iuto an inner or nasal, and an outer or 
 with the saucer-shaped hollow in which temporal, brauch, which at first run between the 
 
 the lens lies. Seen obliquely from the , /^ . , , 
 
 side and before. (Toidt.) hyaloid membrane and the nervous layer; but they 
 
 soon enter the latter, and pass forward, dividing 
 dichotomously. From these branches a minute capillary plexus is given off, which 
 does not extend beyond the inner nuclear layer. The macula receives small twigs 
 from the temporal branches and others directly from the central artery; these do 
 not, however, reach as far as the fovea centralis, which has no blood-vessels. The 
 branches of the arteria centralis retinae do not anastomose with each other — in other 
 words, they are "terminal arteries." In the foetus, a small vessel passes forward, 
 through the hyaloid canal in the vitreous body, to the posterior surface of the cap- 
 sule of the lens (Fig. 715) . 
 
 THE REFRACTING MEDIA. 
 
 The Refracting media are three, viz.: 
 
 Aqueous humor. Vitreous body. Crystalline lens. 
 
 I. The Aqueous Humor (Humor Aqueus). 
 
 The aqueous humor completely fills the lymph space known as the aqueous 
 chamber, the space which is bounded in front by the cornea and behind by the lens 
 and its suspensory ligament and the ciliary body (Fig. 744) . The aqueous chamber 
 
 FOSSA 
 PATELLARIS 
 
 VITREOUS 
 BODY 
 
THE VITREOUS BODY 1129 
 
 is partly divided by the iris into two communicating parts, the anterior and posterior 
 chambers (Figs. 714, 715, and 744.) The posterior chamber (cumera oculi posterior) 
 is only a narrow chink between the peripheral part of the iris, the suspensory 
 ligament of the lens, and the ciliary processes. The anterior chamber (cumera oculi 
 anterior is bounded in front by the cornea and behind by the iris. The external 
 angle of the anterior chamber is bounded by the periphery of the cornea and of 
 the iris. It is called the angle or sinus of the anterior chamber or the filtration angle 
 (angulus iridic) . It is by way of the filtration angle that any excess of aqueous 
 humor passes by way of the spaces of Fontana and the canal of Schlemm (Fig. 
 727) to the anterior ciliary veins and relieves tension. The aqueous humor is 
 small in quantity (scarcely exceeding, according to Petit, four or five grains in 
 weight), has an alkaline reaction, in composition is little more than water, less 
 than one-fiftieth of its weight being solid matter, chiefly chloride of sodium. 
 
 In the adult, these two chambers communicate through the pupil; but in the 
 foetus of the seventh month, when the pupil is closed by the membrana pupillaris, 
 the two chambers are quite separate. 
 
 II. The Vitreous Body (Corpus Vitreum) (Figs. 712, 715, 739). 
 
 The vitreous body forms about four-fifths of the entire globe. It is composed of 
 a jelly-like tissue containing 98 per cent, water, some salts, and a little albumin, 
 and called the vitreous humor (humor vitreum), connective-tissue fibres, and 
 connective-tissue cells. It fills the concavity of the retina, and is hollowed in 
 front, forming a deep concavity, the fossa patellaris (fossa hyaloidea) (Fig. 739), 
 for the reception of the lens. It is perfectly transparent, of the consistence 
 of thin jelly, and is composed of an albuminous fluid enclosed in a delicate 
 transparent membrane, the hyaloid membrane (membrana hyaloidea), the outside 
 of which is in contact with the membrana limitans interna of the retina. It 
 has been supposed by Hannover, that from its inner surface numerous thin 
 lamellae (stroma vitreum) are prolonged inward in a radiating manner, forming 
 spaces in which the fluid is contained. In the adult, these lamellae cannot be 
 detected even after careful microscopic examination in the fresh state, but in prep- 
 arations hardened in weak chromic acid it is possible to make out a distinct 
 lamellation at the periphery of the body; and in the foetus a peculiar fibrous 
 texture pervades the mass, the fibres joining at the numerous points, and pre- 
 senting minute nuclear granules at their point of junction. In the centre of 
 the vitreous humor, running from the entrance of the optic nerve to the posterior 
 surface of the lens, is a canal, filled with fluid and lined by a prolongation of the 
 hyaloid membrane. This is the canal of Stilling, the hyaloid canal, or the canal of 
 Cloquet (canalis hyaloideus) (Fig. 715), which in the embryonic vitreous humor 
 conveyed the minute vessel from the central artery of the retina to the back of 
 the lens. 
 
 The hyaloid membrane encloses the whole of the vitreous humor. In front of 
 the ora serrata it is thickened by the accession of radial fibres and is termed the 
 zonule of Zinn (zonula ciliaris) (Figs. 742 and 744). It presents a series of radially 
 arranged furrows, in which the ciliary processes are accommodated and to which 
 they are adherent, as evidenced by the fact that when removed some of their pig- 
 ment remains attached to the zonule. The zonule of Zinn splits into two layers, one 
 of which is thin and lines the fossa patellaris; the other is named the suspensory 
 ligament of the lens ; it is thicker, and passes over the ciliary body to be attached 
 to the capsule of the lens a short distance in front of its equator. Scattered and 
 delicate fibres are also attached to the region of the equator itself. This ligament 
 retains the lens in position, and is relaxed by the contraction of the radial fibres 
 of the Ciliary muscle, so that the lens is allowed to become more convex. Behind 
 
1130 
 
 THE ORGANS OF SPECIAL SENSE 
 
 the suspensory ligament there is a sacculated canal, the canal of Petit (spaiia 
 zonularia); which encircles the margin of the lens and which can be easily inflated 
 through a fine blow-pipe inserted through the suspensory ligament. It is bounded 
 in front by the anterior layer of the suspensory ligament of the lens, behind by the 
 hyaloidea membrana, and internally by the capsule of the lens. The canal of 
 Petit is a lymph-space. All the spaces of the canal of Petit communicate with the 
 posterior chamber of the eye. 
 
 In the foetus, the centre of the vitreous humor presents the hyaloid canal or 
 canal of Stilling, already referred to, which transmits a minute artery, the 
 hyaloid artery, to the capsule of the lens. In the adult, no vessels penetrate its 
 substance, although a lymph channel remains ; so that its nutrition must be car- 
 ried on by the vessels of the retina and ciliary processes, situated upon its exterior. 
 
 III. The Crystalline Lens (Lens Crystallina) (Figs.716,723,740,741,742,743,744). 
 
 The crystalline lens, enclosed in its capsule, is situated immediately behind the 
 pupil, in front of the vitreous body, and is encircled by the ciliary processes, which 
 slightly overlap its margin. 
 
 The capsule of the lens (capsula lentis) (Fig. 744) is a transparent, highly elastic, 
 and brittle membrane, which closely surrounds the lens, and is composed in part of 
 
 Fig. 740. — The crystalline lens, hardened 
 and divided. (Enlarged.) 
 
 ANTERIOR 
 SURFACE 
 
 ANTERIOR 
 POLE 
 
 POSTERIOR 
 SURFACE 
 
 ^POSTERIOR 
 A POLE 
 
 AXIS OF 
 LENS 
 
 Fig. 741. — The term.s used in the orientation of the lens. (Toldt.) 
 
 cuticular and in part of connective tissue. It is not white fibrous tissue, and is not 
 true elastic tissue (Szymonowicz). Its outer surface is composed of lamella and 
 possesses transverse striations. It rests, behind, in the fossa patellaris in the fore- 
 part of the vitreous body (Fig. 739) ; in jront, it is in contact with the free border 
 of the iris, this latter receding from it at the circumference, thus forming the 
 posterior chamber of the eye (Fig. 744) ; and it is retained in its position chiefly by 
 the suspensory ligament of the lens, already described (Fig, 744). The capsule is 
 much thicker in front than behind, and when ruptured the edges roll up with the 
 outer surface innermost, like the elastic lamina of the cornea. 
 
 The substance of the lens {substantia lentis) is an epithelial structure and takes 
 origin from the ectoderm. It consists early in development of transparent 
 cylindrical cells, which at a later period become higher at the posterior surface 
 of the lens. Eventually very long cells form; they are known as lens-fibres (fibrae 
 lentis), and are joined by a cement substance. The adult lens consists of lens- 
 fibres, the anterior surface being covered by one layer of cubical epithelial cells, 
 known as lens epithelium (epithelium lentis). This layer extends to the margin of 
 the lens, at which point the cells gain in height and form lens-fibres. The lens- 
 fibres at the margin are nucleated, the others are not. The lens-fibres run as 
 meridians from the anterior surface backward. There is no epithelium on the 
 posterior surface. 
 
THE CRYSTALLINE LENS 
 
 1131 
 
 In the foetus, a small branch from the arteria centralis retinae runs forward, 
 as already mentioned, through the vitreous humor to the posterior part of the 
 capsule of the lens, where its branches radiate and form a plexiform network, 
 which covers its surface, and they are continuous around the margin of the capsule 
 with the vessels of the pupillary membrane and with those of the iris. In the adult 
 no vessels enter its substance. 
 
 Structure. — The lens is a transparent, biconvex body, the convexity being greater 
 on the posterior than on the anterior surface (Fig. 741). The central points of its 
 
 CORONA 
 CILIARIS 
 
 ORBICULARIS 
 CILIARIS 
 
 Fig. 742. — The zonule of Zinn or the suspensory ligament of the lens viewed from behind in connection 
 with the lens and the ciliary body. (Toldt.) 
 
 anterior and posterior surfaces are known as its anterior and posterior poles (polus 
 anterior leniis et polus posterior lentis) (Fig. 741). It measures from 9 to 10 mm. 
 in the transverse diameter, and about 4 mm. in the antero-posterior. It consists 
 of concentric layers (Fig. 740) of which the external in the fresh state are soft and 
 easily detached {substantia corticalis) (Fig. 744) ; those beneath are firmer, the cen- 
 tral ones forming a hardened nucleus (nucleus lentis) (Fig. 740), These laminae 
 are best demonstrated by boiling or immersion in alcohol, and consist of minute 
 parallel fibres, which are hexagonal prisms, the edges being dentated, and the 
 
 Fig. 743. — Diagram to show the direction and arrangement of the radiating lines on the front and back of 
 the foetal lens. A, from the front; B, from the back. 
 
 dentations fitting accurately into each other; their breadth is about g ^q q - of an 
 inch. Faint lines radiate from the anterior and posterior poles to the circumference 
 of the lens. In the adult there may be six or more of these, but in the foetus they are 
 only three in number and diverge from each other at angles of 120° (Fig. 743). On 
 the anterior surface one line ascends vertically and the other two diverge down- 
 ward and outward. On the posterior surface one ray descends vertically and 
 the other two diverge upward. They correspond with the free edges of an equal 
 number of septa in the lens, along which the ends of the lens-fibres come into 
 
1132 
 
 THE OBGANS OF SPECIAL SENSE 
 
 apposition and are joined together by transparent amorphous substance. The 
 fibres run in a curved manner from the septa on the anteror surface to those on 
 the posterior surface. No fibres pass from pole to pole, but they are arranged 
 in such a way that fibres which commence near the pole on the one aspect of 
 the lens terminate near the peripheral extremity of the plane on the other, and 
 vice versa. Each fibre of the outer layers of the lens contains a nucleus, and 
 these nuclei form a layer, the nuclear layer on the surface of the lens. The nuclear 
 layer is most distinct toward the circumference of the lens. 
 
 INSERTION OF 
 
 TENDON OF SUPERIOR. 
 
 RECTUS MUSCLE 
 
 PARS OPTICA 
 RETIN>E 
 ORA SERRATA 
 PARS CILIARIS RETIN/E 
 
 CONJUNCTIVA 
 EPISCLERAL 
 CONNECTIVE 
 TISSU 
 LIGAMENTUM 
 PECTINATUM 
 IRIDIS 
 RIMA 
 CORNEALIS! 
 
 EDGE OF 
 CORNEA m 
 
 IRIS (ante- y| ' 
 rior surface) 
 
 POSTERIOR 
 SURFACE 
 OF CORNEA 
 EPITHELIUM — 
 OF CORNEA 
 ANTERIOR- 
 ELASTIC 
 LAMINA 
 
 EPITHELIUM OF 
 S CAPSULE 
 CAPSULE 
 OF LENS 
 
 CORTICAL SUB8TANCC 
 OF LENS 
 
 NUCLEUS 
 OF LENS 
 
 POSTERIOR ELASTIC 
 LAMINA 
 
 STROMA OF IRIS 
 SPHINCTER PIGMENTARY 
 OF PUPIL LAYERS OF IRIS 
 
 Fig. 744. — The upper half of a sagittal section through the front of the eyeball. (Toldt.) 
 
 The changes 'produced in the lens by age are the following: 
 
 In the foetus its form is nearly spherical, its color of a slightly reddish tint, it 
 is not perfectly transparent, and is so soft as to break down readily on the slightest 
 pressure. 
 
 In the adult the posterior surface is more convex than the anterior; it is color- 
 less, transparent, and firm in texture. 
 
 In old age it becomes flattened on both surfaces, slightly opaque, of an amber 
 tint, and increases in density. 
 
 Arteries of the Globe of the Eye. — The arteries of the globe of the eye are the short 
 posterior ciliary, long posterior ciliary, and anterior ciliary arteries, and the arteria 
 centralis retinae. 
 
THE CRYSTALLINE LENS 1133 
 
 The short posterior ciliary arteries {aa. ciliares posterior es breves) (Figs. 721, 723, 
 and 725) are from eight to sixteen in number. They arise from the ophthalmic 
 branch of the internal carotid, pass through the sclerotic coat near the optic 
 nerve, and are distributed to the choroid. 
 
 There are two long posterior ciliary arteries (aa. ciliares posteriores longae) (Figs. 
 721, 723, and 730) , one on each side of the optic nerve. They are branches of the 
 ophthalmic. They pass through the sclerotic external to the short ciliary arteries, 
 and extend forward in the choroid. In the ciliary body they form an anastomosis 
 with the anterior ciliary arteries. The anastomosis is known as the circulum iridis 
 major (Figs. 723 and 744). Branches from this circle pass to the iris, and at the 
 periphery of the sphincter of the iris form the circulum iridis minor. The muscular 
 branches and the lachrymal branch of the ophthalmic give off the anterior ciliary 
 arteries {aa. ciliares anieriores) , six or eight in number. They pass along tendons 
 of the muscles of the eyeball, reach the sclera, and pass upon the sclera to the 
 corneal margin (Fig. 730). Branches are given off which pass backward to supply 
 the anterior half of the sclera, and which are known as episcleral arteries {aa. 
 episclerales) (Fig. 723). Two branches are given off which pass forward to the 
 conjunctiva bulbi, which are known as the anterior conjunctival arteries {aa. con- 
 junctivales anieriores), which anastomose with the posterior conjunctival branches 
 from the palpebral arteries, and which give branches to the delicate vascular net- 
 work of the corneal margin which is in the annulus conjunctivae (Spalteholz). 
 Eight or even more branches form the anterior ciliary arteries. They pass through 
 the sclerotic near the sclero-corneal junction, and participate in the formation of the 
 circulum iridis major. 
 
 The Veins of the Globe of the Eye (Figs. 721, 722, and 723).— The veins are seen 
 on the outer surface of the choroid. They have a whorl-like formation and empty 
 into four or five large veins, the venae vorticosae. These four, five, or six equidistant 
 venae vorticosae pierce the sclerotic midway between the margin of the cornea 
 and the entrance of the optic nerve, and empty into the ophthalmic vein. Another 
 set of veins accompany the anterior ciliary arteries, and are known as the anterior 
 ciliary veins {vv. ciliares anieriores). They are derivatives of the venous sinus of 
 the sclera in the canal of Schlemm. They form a circular plexus. They receive 
 vessels, the ciliary muscle, and pass through the sclera close to the corneal margin. 
 Posterior ciliary veins {vv. ciliares posieriores) receive vessels which gather venous 
 blood from the outer surface of the sclera near the optic nerve. The posterior 
 ciliary veins join anteriorly with the venae vorticosae. After emerging from the 
 sclera they receive anterior conjunctival branches, and by means of episcleral 
 veins communicate Avith the venae vorticosae. 
 
 The Lymphatic Passages of the Eyeball. — The conjunctiva contains lymph- 
 vessels. The eyeball contains lymph-spaces, but no lymph- vessels 
 
 There are two sets of lymph-spaces in the eyeball, the anterior and posterior. 
 
 The anterior lymph-spaces are the spaces of the cornea, of the iris, of the 
 anterior chamber, and of the posterior chamber. 
 
 The lymph from the intralamellar lymph-spaces of the cornea enters the con- 
 junctival lymphatics at the margin of the cornea. 
 
 The lymph-spaces of the iris open into the anterior chamber by the crypts of 
 the iris and at the margin of the iris join the spaces of Fontana. 
 
 The aqueous humor fills the anterior and posterior chambers, but is furnished 
 by the vessels in the posterior chamber; in part by the vessels of the ciliary body, 
 and in part by the vessels of the posterior surface of the iris. The lymph thus 
 secreted passes by way of the pupil into the anterior chamber, and then is taken 
 up by the spaces of Fontana, the canal of Schlemm, and the anterior ciliary veins .^ 
 
 ' Deaver's Anatomy. 
 
1134 THE ORGANS OF SPECIAL SENSE 
 
 The posterior lymph -spaces are the hyaloid canal, the perichoroidal lymph- 
 space, the space of Tenon, the intervaginal space of the optic nerve, and the supra- 
 vaginal space (Deaver). 
 
 The hyaloid canal (Figs. 712 and 715) passes between the posterior surface of 
 the lens and the optic disk. In the embryo the canal holds an artery, the hyaloid 
 artery. During development the artery disappears, but a lymph channel remains. 
 The hyaloid canal opens into the intervaginal space of the optic nerve. Between 
 the sclerotic and the choroid is the perichoroidal lymph-space (Fig. 744). It is 
 around the choroid vessels and the venae vorticosae, and empties into Tenon's 
 space by means of openings through the sclera about the venae vorticosae. 
 
 Tenon's space (Figs. 712 and 713) is between the sclera and the capsule of Tenon. 
 It receives lymph from the perichoroidal space, and empties into the supra- 
 vaginal space. 
 
 The optic nerve (Fig. 731) has a sheath of dura and a sheath of pia, and 
 between these sheaths is the intervaginal lymph-space. It is divided by a pro- 
 longation of the cerebral arachnoid into a subdm:al space and a subarachnoid 
 space, which empty into the corresponding spaces of the membranes of the brain. 
 
 The supravaginal space is between the dural portion of the sheath of the optic 
 nerve and a posterior prolongation of Tenon's capsule.^ 
 
 The Nerves of the Globe of the Eye. — ^The long ciliary nerves (nn. ciliaris longi), 
 two in number, are derived from the nasal branch of the ophthalmic and the 
 short ciliary nerves {nn. ciliares breves) , twelve to fifteen in number, are derived 
 from the ciliary or ophthalmic ganglion. Both the long and short ciliary nerves 
 perforate the sclera in the neighborhood of the optic nerve (Fig. 721). They pass 
 along the perichoroidal lymph-space, forming a plexus, and send filaments to the 
 choroid vessels. In front of the Ciliary muscle they form a second plexus, and 
 from it come branches which go to the Ciliary muscle and the muscular fibres and 
 vessels of the iris, sclera, choroid, ciliary body, and iris (Fig. 729). The ciliary 
 nerves supply the cornea. The circular fibres of the iris are innervated by the 
 third nerve and the radiating fibres by the sjonpathetic. 
 
 Surgical Anatomy. — From a surgical point of view the cornea may be regarded as consist- 
 ing of three layers: (1) of an external epithelial layer, developed from the epiblast, and continu- 
 ous with the external epithelial covering of the rest of the body, and therefore in its lesions resem- 
 bling those of the epidermis ; (2) of the cornea proper, derived from the mesoblast, and associated 
 in its diseases with the fibro- vascular structures of the body; and (3) the posterior elastic layer 
 with its endothelium, also derived from the mesoblast and having the characters of a serous 
 membrane, so that inflammation of it resembles inflammation of the other serous and synovial 
 membranes of the body. 
 
 The cornea contains no blood-vessels, except at its periphery, where numerous delicate loops, 
 derived from the anterior ciliary arteries, may be demonstrated on the anterior surface of the 
 cornea. The rest of the cornea is nourished by lymph, which gains access to the proper sub- 
 stance of the cornea and the posterior layer through the spaces of Fontana. This lack of a direct 
 blood-supply renders the cornea very apt to inflame in the cachectic and ill-nourished. In spite 
 of the absence of blood-vessels, wounds of the cornea usually heal rapidly. A wound which pene- 
 trates the cornea opens the anterior chamber, and aqueous humor escapes. An ulcer may also 
 open the anterior chamber. Through a wound or a perforated ulcer the pupillary margin of the 
 iris may prolapse. A trivial injury of the cornea is repaired by transparent tissue. A severe 
 injury is repaired by fibrous tissue, and opacity results. A slight opacity resembling a cloud of 
 gray smoke is called nebula; a more marked white opacity is called leucoma. 
 
 In abscess of the cornea pus gravitates between the layers to the lower part of the cornea and 
 the purulent collection assumes a crescentic shape (onyx). 
 
 The arcus senilis, seen in the aged, is a condition of haziness or opacity at the corneal margin 
 due to fatty degeneration of the tissue of the cornea. It signifies interference with the blood- 
 supply, because of senile degeneration of adjacent vessels. In cases of granular lids there is a 
 pecuHar affection of the cornea, called pannus, in which the anterior layers of the cornea become 
 vascularized, and a rich network of blood-vessels may be seen on the cornea; and in interstitial 
 keratitis new vessels extend into the cornea, giving it a pinkish hue, to which the term salmon 
 patch is applied. The cornea is richly supplied with nerves, derived from the ciliary nerves, which 
 
 1 For the lymphatic channels of the eyeball see Deaver's Surgical Anatomy, vol. ii. p. 392. 
 
THE CRYSTALLINE LENS 1135 
 
 enter the cornea through the forepart of the sclerotic and form plexuses in the stroma, terminating 
 between the epithelial cells by free ends or in corpuscles. In cases of glaucoma the ciliary nerves 
 may be pressed upon as they course between the choroid and sclerotic (Fig. 719), and in conse- 
 quence of the [pressure upon them, the cornea, to which they are distributed, becomes anaes- 
 thetic. When a scar forms on the cornea and the iris becomes adherent, the scar and the iris, 
 and sometimes even the lens, may bulge forward from intraocular tension. This condition 
 is staphyloma of the cornea. In conditions of impaired nutrition the cornea may be bulged for- 
 ward by intraocular pressure. The line of least resistance is a little below the centre of the 
 cornea, and it is bulged forward and strongly curved. This condition is known as conical cornea. 
 The sclerotic has very few blood-vessels and nerves. The blood-vessels are derived from the 
 anterior ciliary, and form an open plexus in its substance. As they approach the corneal margin 
 this arrangement is peculiar. Some branches pass through the sclerotic to the ciliary body; others 
 become superficial and lie in the episcleral tissue, and form arches, by anastomosing with each 
 other, some little distance behind the corneal margin. From these arches numerous straight 
 vessels are given off, which run forward to the cornea, forming its marginal plexus. In inflamma- 
 tion of the sclerotic and episcleral tissue these vessels become conspicuous, and form a pinkish 
 zone of straight vessels radiating from the corneal margin, commonly known as the zone of ciliary 
 injection. In inflammation of the iris and ciliary body this zone is present, since the sclerotic 
 speedily becomes involved when these structures are inflamed. But in inflammation of 'the cornea 
 the sclerotic is seldom much affected, though the cornea and sclerotic are structurally continuous. 
 This would appear to be due to the fact that the nutrition of the cornea is derived from a different 
 source from that of the sclerotic. The sclerotic may be ruptured subcutaneously without any 
 laceration of the conjunctiva, and the rupture usually occurs near the corneal margin, where 
 the tunic is thinnest. It may be complicated with lesions of adjacent parts — laceration of the 
 choroid, retina, iris, or suspensory ligament of the lens — and is then often attended with hemor- 
 rhage into the anterior chamber, which masks the nature of the injury. In some cases the lens 
 has escaped through the rent in the sclerotic, and has been found under the conjunctiva. Wounds 
 of the sclerotic, if they do not perforate, usually heal readily. If they extend through the sclerotic 
 they cause diminished tension, are always dangerous, and are often followed by inflammation, 
 suppuration, and by sympathetic ophthalmia. The sclerotic may be weakened by injury, inflam- 
 mation, etc., and the weakened portion may bulge from intraocular pressure, and even a healthy 
 sclera may bulge from excessive intraocular pressure. According to its situation the lesion is 
 known as ciliary staphyloma, equatorial staphyloma, or posterior staphyloma. 
 
 One of the functions of the choroid is to provide nutrition for the retina and to convey ves- 
 sels and nerves to the ciliary body and iris. Inflammation of the choroid is therefore followed 
 by grave disturbance in the nutrition of the retina, and is attended with early interference with 
 vision. Purulent choroiditis is not confined to the choroid; the retina, the vitreous, and the entire 
 uveal tract become involved, and even other structures may suffer. In its diseases it bears a con- 
 siderable analogy to those which affect the skin, and, like it, is one of the places from which 
 melanotic sarcomata may grow. These tumors contain a large amount of pigment in their cells, 
 and grow only from those parts where pigment is naturally present. The choroid may be ruptured 
 without injury to the other tunics, as well as participating in general injuries of the eyeball. In 
 cases of uncomplicated rupture the injury is usually at its posterior part, and is the result of a 
 blow on the front of the eye. It is attended by considerable hemorrhage, which for a time may 
 obscure vision, but in most cases this is restored as soon as the blood is absorbed. 
 
 The iris is the seat of a malformation, termed coloboma, which consists in a deficiency or 
 cleft, which in a great number of cases is clearly due to an arrest in development. In these cases 
 it is found at the lower aspect, extending directly downward from the pupil, and the gap fre- 
 quently extends through the choroid to the entrance of the optic nerve. In some rarer cases the 
 gap is found in other parts of the iris, and is then not associated with any deficiency of the choroid. 
 The iris is abundantly supplied with blood-vessels and nerves, and is therefore very prone to 
 become inflamed. And when inflamed, in consequence of the fact that the iris and ciliary body are 
 continuous, and that their vessels communicate, iritis is usually associated with cyclitis, the dis- 
 ease being called irido-cyclitis. And, in addition, inflammation of adjacent structures, the cornea 
 and sclerotic, is apt to spread into the iris. The iris is covered with endothelium, and partakes of 
 the character of a serous membrane, and, like these structures, is liable to pour out a plastic exuda- 
 tion when inflamed, and contract adhesions, either to the cornea in front (synechia anterior), or 
 to the capsule of the lens behind (synechia posterior). In iritis the lens may become involved, 
 and the condition known as secondary cataract may be set up. Tumors occasionally commence in 
 the iris; of these, cysts, which are usually congenital and sarcomatous tumors, are the most common 
 and require removal. Gummata are not unfrequently found in this situation. In some forms 
 of injury of the eyeball, as the impact of a spent shot, the rebound of a twig, or a blow with a 
 whip, the iris may be detached from the Ciliary muscle, the amount of detachment varying from 
 the slightest degree to the separation of the whole iris from its ciliary connection. 
 
 The Argyll-Robertson pupil shows no reaction to light, but retains reaction to accommodation 
 and vision remains good. 
 
1136 
 
 THE ORGANS OF SPECIAL SENSE 
 
 The retina, with the exception of its pigment-layer and its vessels, is perfectly transparent, 
 and is invisible when examined by the ophthalmoscope, so that its diseased conditions are 
 recognized by its loss of transparency. In retinitis, for instance, there is more or less dense and 
 extensive opacity of its structure, and not unfrequently extravasations of blood into its sub- 
 stance. Hemorrhages may also take place into the retina from rupture of a blood-vessel without 
 inflammation. 
 
 In o-ptic neuritis, pajnllitis, or choked disk, the ophthalmoscope shows increase in vascularity, 
 and swelling and opacity of the nerve, which extend beyond the disk margins. Optic atrophy 
 is apt to follow. (Fig. 745 shows a normal optic disk.) 
 
 The retina may become displaced from effusion of serum between it and the choroid or by 
 blows on the eyeball, or may occur without apparent cause in progressive myopia, and in this 
 case the ophthalmoscope shows an opaque, tremulous cloud. Glioma, a form of sarcoma, and 
 essentially a disease of early life, is occasionally met with in connection with the retina. 
 
 The lens has no blood-vessels, nerves, or connective tissue in its structure, and therefore is 
 not subject to those morbid changes to which tissues containing these structures are liable. It 
 does, however, present certain morbid or abnormal conditions of various kinds. Thus, variations 
 in shape, absence of the whole or a part of the lens, and displacements are amongst its congenital 
 dejects. Opacities may occur from injury, senile changes, malnutrition, or errors in growth or 
 development. An opacity of the capsule, of the lens, or of both, is known as a cataract. Senile 
 changes may take place in the lens, impairing its elasticity and rendering it harder than in youth. 
 
 Fig. 745. — Ophthalmoscopic appearances of healthy 
 fundus in a person of very fair complexion. Scleral 
 ring well marked. Left eye, inverted image. (Wecker 
 and Jaeger.) 
 
 Fig. 746. — Ophthalmoscopic appearance of severe 
 recent papillitis. Several elongated patches of blood 
 near border of disk. (After Hughlings Jackson.) 
 
 so that its curvature can only be altered to a limited extent by the Ciliary muscle. And, finally, 
 the lens may be dislocated or displaced by blows upon the eyeball, and its relations to surround- 
 ing structures altered by adhesions or the pressure of new growths. 
 
 There are two particular regions of the eye which require special notice : one of these is known 
 as the " filtration area," and the other as the " dangerous area." The filtration area is the circum- 
 corneal zone immediately in front of the iris. Here are situated the cavernous spaces of 
 Fontana, which communicate with the canal of Schlemm, through which the chief transudation 
 of fluid from the eye is now believed to take place. The dangerous area of the eye is the region 
 in the neighborhood of the ciliary body, and wounds or injuries in this situation are peculiarly 
 dangerous; for inflammation of the ciliary body is liable to spread to many of the other structures 
 of the eye, especially to the iris and choroid, which are intimately connected by nervous and 
 vascular supplies. Moreover, wounds which involve the ciliary region are especially liable to be 
 followed by sympathetic ophthalmia, in which destructive inflammation of one eye is excited by 
 some irritation in the other. 
 
 Emmetropia is normal vision. In normal vision the practically parallel light rays from distant 
 objects focus on the retina without effort; divergent rays from near objects are focused on the 
 retina by an effort of accommodation. 
 
 Hyperopia or hypermetropia is far-sightedness. In this condition the retina is in front of the 
 principal focus when the eye is at rest. The patient endeavors to correct the failure by constant 
 and tiresome efforts at accommodation. The condition is usually due to inordinate shortness of 
 the axis of the eye, but may be due to loss of the lens, decreased convexity of the refractive sur- 
 faces, or lessened refractive power in the refractive media of the eye. It is corrected by the use 
 of convex glasses. 
 
THE EYELID II37 
 
 Myopia is near-sightedness. In this condition the rays of light come to a focus in front of the 
 retina, and the patient is subjected to continued eye-strain. It is usually due to too great length 
 of the axis of the eye, but may result from increase in refractive power of refractive media. It is 
 corrected by concave glasses. Sometimes, as a person with hyperopia begins to age, an increased 
 refractive power of the lens causes myopia. The occurrence of myopia in a hyperopic eye is 
 called second sight, and it enables the individual to cease wearing convex glasses. 
 
 Exenteration of the contents of the orbit means removal of all the contents except those at the 
 orbital apex. Even the periosteum is taken away. It is performed for malignant disease. 
 
 Evisceration of the eyeball is performed by making a circular incision at the corneal margin and 
 removing the internal and middle coats and the contents of the globe. The sclera is not removed. 
 A glass ball is inserted into the scleral sheath, and the sclera is closed over the ball by vertical 
 stitches, and the conjunctiva is closed over it by transverse stitches. The operation is performed 
 for leucoma or staphyloma of the cornea. An artificial eye (a shell) is placed over the stump 
 when healing is complete. 
 
 Enucleation, or excision of the eyeball, differs from exenteration of the orbital contents in the 
 fact that only the eyeball is removed. A circular incision through the ocular conjunctiva 
 is carried around and near to the corneal margin. The conjunctiva and capsule of T^non are 
 pushed back and the Rectus muscles are clamped and divided back of the clamp. Traction 
 is made upon the glol)e in a forward and inward direction, and the optic nerve and adjacent 
 structures are cut with scissors from the outer aspect of the globe. The eye is then pulled out of 
 the orbit, antl all structures which tend to retain it are divided. The stumps of the Recti muscles 
 are sewed together. 
 
 THE APPENDAGES OF THE EYE (TUTAMINA OOULI). 
 
 The appendages of the eye include the eyebrows, the eyelids, the conjunctiva, 
 and the lachrymal apparatus — viz., the lachrymal gland, the lachrymal sac, and the 
 nasal duct. 
 
 The Eyebrow (Supercilium) . 
 
 The eyebrows are two arched eminences of integument which surmount the 
 upper circumference of the orbit on each side, and support numerous short, thick 
 hairs, directed obhquely on the surface. The hairs may entangle foreign bodies 
 and lessen somewhat the force of blows. In structure the eyebrows consist of 
 thickened integument, connected beneath with the Orbicularis palpebrarum, 
 Corrugator supercilii, and Occipito-frontalis muscles. These muscles serve, by 
 their action on this part, to control to a certain extent the amount of light 
 admitted into the eye. 
 
 The Eyelid (Palpebra) (Figs. 747, 748). 
 
 The eyelids are two thin, movable folds placed in front of the eye, and by closure 
 protecting the eye from injury. The eyelids are composed of skin, superficial 
 fascia, and alveolar tissue, fibres of the Orbicularis palpebrarum muscle, palpebral 
 and orbito-tarsal ligaments, tarsal cartilages, and conjunctiva. The upper lid 
 also contains the Levator labii superioris muscle. In the lids are blood-vessels, 
 lym])h-vessels, nerves, and Meibomian glands. There are two lids, the upper 
 (palpebra superior) and the lower (palpebra inferior). The upper lid is the larger 
 and the more movable of the two, and is furnished with a separate elevator 
 muscle, the Levator palpebrae superioris. Each lid consists of two portions. The 
 part near the orbital margin, "whose groundwork is formed merely by the thin 
 palpebral fascia (septum orhitale),"^ is called the orbital portion (pars orbitalis). 
 The part in which the tarsus lies is called the tarsal portion (pars tarsalis) . Between 
 the two portions in each lid is a sulcus, called, in the upper lid, the superior orbito- 
 palpebral sulcus (sulcus orbitopalpehralis superior), and, in the lower lid, the inferior 
 orbito -palpebral sulcus (sulcus orbitopalpebralis inferior). When the eyelids are 
 
 • An Atlas of Human Anatomy. By Carl Toldt, assisted by A. D. Rosa. Translated by M. Eden Paul. 
 
 72 
 
1138 
 
 THE ORGANS OF SPECIAL SENSE 
 
 opened an elliptical space, the interpalpebral slit {jissura palpebrarum), is left 
 between their margins, the angles of which correspond to the junction of the upper 
 and lower lids, and are called canthi. 
 
 The Canthi. — The outer canthus {angulus oculi lateralis) is more acute than the 
 inner, and the lids here lie in close contact with the globe; but the inner canthus 
 (angulus oculi medialis) is prolonged for a short distance inward toward the nose. 
 The two lids are separated at the inner canthus by a triangular space, the lacus 
 lacrimalis. At the commencement of the lacus lacrimalis, on the margin of each 
 eyelid, is a small conical elevation, the lachrymal papilla, the apex of which is 
 pierced by a small orifice, the punctum lacrimale (Fig. 751), the commencement of 
 the lachrymal canal (Fig. 750) . When the lids are closed a space remains between 
 them and the globe to permit of the flow of tears inward (rivus lacrimalis). 
 
 The Eyelashes (cilia) (Fig. 748). — The eyelashes are attached to the free edges of 
 the eyelids; they are short, thick, curved hairs, arranged in a double or triple row 
 at the margin of the lids; those of the upper lid, more numerous and longer than 
 the lower, curve upward; those of the lower lid curve downward. Because of this 
 arrangement the two sets do not interlace in closing the lids. Near the attachment 
 of the eyelashes are the openings of sebaceous glands {glandulae sebaceae) (Fig. 748) 
 and of a number of glands, glands of Moll {glandulae ciliares [Molli]) (Fig. 748), 
 arranged in several rows close to the free margin of the lid. They are regarded as 
 enlarged and modified sweat-glands. On the inner surface are the Meibomian 
 glands (glandulae tarsales \_Meibomi\) (Fig. 750). Internal to the openings of the 
 lachrymal canaliculi there are neither lashes nor Meibomian glands. 
 
 LACHRYMAL ARTERY. 
 AND NERVE 
 
 EXTERNAL LATERALr 
 LIGAMENT 
 
 i SUPRAORBITAL VES- 
 SELS AND NERVE 
 
 LACHRYMAL SAC 
 
 NTERNAL LATE- 
 RAL LIGAMENT 
 
 Fig, 747. — The tarsi and their ligaments. Right eye, front view. (Testut.) 
 
 Structure of the Eyelids (Fig. 748) . — The eyelids are composed of the following 
 structures, taken in their order from without inward: 
 
 Integument, areolar tissue, fibres of the Orbicularis muscle, tarsal plate, and 
 its ligament. Meibomian glands, and conjunctiva. The upper lid has, in addition, 
 the aponeurosis of the Levator palpebrse. 
 
 The integument is extremely thin, and continuous at the margin of the lids with 
 the conjunctiva. 
 
 The subcutaneous areolar tissue is very lax and delicate, seldom contains any 
 fat, and is extremely liable to serous infiltration. 
 
 The fibres of the Orbicularis muscle, where they cover the palpebrae (m. ciliaris 
 [Riolani]), are thin, pale in color, and possess an involuntary action. 
 
THE EYELID 
 
 1139 
 
 The tarsal plates are two thin elongated plates of dense connective tissue about 
 an inch in length. They are placed one in each lid, contributing to their form 
 and support. 
 
 The superior tarsal plate, superior tarsus or superior tarsal body {tarsus superior) 
 (Fig. 747) , the larger, is of a semilunar form, about one-third of an inch in 
 breadth at the centre, and becoming gradually narrowed at each extremity. To 
 the anterior surface of this plate the aponeurosis of the Levator palpebrae is 
 attached. 
 
 The inferior tarsal plate, inferior tarsus or inferior tarsal body (tarsus inferior) 
 (Fig. 747), the smaller of the two, is thinner and of an elliptical form. 
 
 The free or ciliary margin of these plates is thick, and presents a perfectly 
 straight edge. The attached or orbital margin is connected to the circumference of 
 the orbit by the fibrous membrane of the 
 lids, with which it is continuous. The 
 outer angle of each plate is attached to 
 the malar bone by the external tarsal or 
 external lateral ligament, or the external 
 palpebral ligament or raph^ (ligamentum 
 pilpe'ralis lateralis) (Fig. 747). The inner 
 angles of the two plates terminate at the 
 commencement of the lacus lacrimalis; 
 they are attached to the nasal process 
 of the superior maxilla by the internal 
 tarsal or internal lateral or internal palpe- 
 bral ligament or the tendo oculi (ligamen- 
 tum palpebrals mediale) (Fig. 747). 
 
 The fibrous membrane of the lids con- 
 stitutes the orbito-tarsal ligaments or the 
 palpebral fasciae. In reality these so-called 
 ligaments are fascial expansions situated 
 one in each lid, and are attached margin- 
 ally to the edge of the orbit, where they 
 are continuous with the periosteum. The 
 superior ligament blends with the tendon 
 of the Levator palpebrae, the inferior with 
 the inferior tarsal plate. Externally the 
 superior and inferior ligaments fuse to 
 form the external tarsal ligament or raph6 
 just referred to ; internally they are much 
 thinner, and, becoming separated from 
 the internal tarsal ligament, are fixed to 
 the lachrymal bone immediately behind 
 the lachrymal sac. Together the liga- 
 ments form an incomplete septum, the Fig. 748. — Vertical section through the upper eye- 
 
 , .. , ^ , , 7 •, 7 \ 1 • 1 • lid. a. Skin. b. Orbicularis palpebrarum. 6'. Mar- 
 
 Orbltal septum (septum Orbltale), which is ginal fasciculus of orbicularis (ciliary bundle). C. 
 
 J!, 11.1 1 1 I'l Levator palpebrae. d. Conjunctiva, e. Tarsal plate. 
 
 perforated by the vessels and nerves which /. Meibomian gland, g. Sebaceous gland, h. Eye- 
 pass from the orbital cavity to the face 'K^!irior\!A^.^ir\M^^^ '' 
 and scalp. 
 
 The Meibomian or Tarsal Glands (glandulae tarsales [Meibomi]) (Figs. 748 and 
 750). — The Meibomian or tarsal glands are situated upon the inner surface of the 
 eyelids between the tarsal plates and conjunctiva, and may be distinctly seen 
 through the mucous membrane on everting the eyelids, presenting the appearance 
 of parallel strings of pearls. They are about thirty in number in the upper eyelid, 
 and somewhat fewer in the lower. They are embedded in grooves in the inner 
 
1140 THE ORGANS OF SPECIAL SENSE 
 
 surface of the tarsal plates, and correspond in length with the breadth of each plate; 
 they are, consequently, longer in the upper than in the lower eyelid. Their ducts 
 open on the free margin of the lids by minute foramina, which correspond in num- 
 ber to the follicles. The use of their secretion is to prevent adhesions of the lids. 
 Structure of the Meibomian Glands. — These glands are a variety of the cutaneous 
 sebaceous glands, each consisting of a single straight tube or follicle, having a 
 csecal termination, and with numerous small secondary follicles opening into it. 
 The tubes consist of basement-membrane, lined at the mouths of the tubes by 
 stratified epithelium; the deeper parts of the tubes and the secondary follicles are 
 lined by a layer of polyhedral cells. They are thus identical in structure with the 
 sebaceous glands. 
 
 The Conjunctiva (Figs. 714, 715, 727, 749). 
 
 The conjunctiva is the mucous membrane of the eye. It lines the inner surface 
 of the eyelids, is reflected over the forepart of the sclerotic and cornea, and joins 
 the lids to the eyeball. In each of these situations its structure presents some 
 peculiarities. 
 
 The Palpebral Portion {tunica conjunctiva palpebrarum) (Fig. 750) . — The palpe- 
 bral portion of the conjunctiva lines the posterior surface of the lids. It is thick, 
 opaque, highly vascular, and covered with numerous papillae, its deeper parts 
 presenting a considerable amount of lymphoid tissue. At the margin of the lids 
 it becomes continuous with the lining membrane of the ducts of the Meibomian 
 glands, and, through the lachrymal canals, with the lining membrane of the 
 lachrymal sac and nasal duct. At the outer angle of the upper lid the lachrymal 
 ducts open on its free surface; and at the inner angle of the eye it forms a semi- 
 lunar fold, the plica semilunaris {plica semilunaris conjunctivae) (Fig. 751). The 
 folds formed by the reflection of the conjunctiva from the lids on to the eye are 
 called the superior and inferior palpebral folds, the former being the deeper of the 
 two. These folds form the superior and inferior conjunctival fornix (Fig. 749). 
 
 The Bulbar Portion {tunica conjunctiva hulhi). — Upon the sclerotic the conjunc- 
 tiva is loosely connected to the globe; it becomes thinner, loses its papillary struc- 
 ture, is transparent, and only slightly vascular in health. Upon the cornea the con- 
 junctiva consists only of epithelium, constituting the ante- 
 rior layer of the cornea (conjunctival epithelium) already 
 described (p. 1109). Lymphatics arise in the conjunc- 
 tiva in a delicate zone around the cornea, from which the 
 vessels run to the ocular conjunctiva. 
 
 Fornix of Conjunctiva. — At the point of reflection of 
 each fold of the conjunctiva from the lid on to the globe 
 of the eye a pocket or arch is formed. These arches are 
 INFERIOR FORNIX temicd the fornix conjunctivae (Fig. 749). 
 Fig. 749.— Sagittal section Glauds of Conjunctiva. — In the conjunctiva there are a 
 
 of eye, showing superior and iii-i i ij.i 
 
 inferior fornices of the con- numbcr of mucous glauds which are much convoluted. 
 They are chiefly found in the upper lid. Other glands, 
 analogous to lymphoid follicles, and called by Henle trachoma glands, are found 
 in the conjunctiva, and, according to Stromeyer, are chiefly situated near the 
 inner canthus of the eye. They were first described by Brush, in his description 
 of Peyer's patches of the small intestines, as " identical structures existing in the 
 under eyelid of the ox." 
 
 The Nerves of the Conjunctiva. — ^The nerves in the conjunctiva are numerous and 
 form rich plexuses. According to Krause, they terminate in a peculiar form of 
 tactile corpuscle, which he terms the terminal bulb. 
 
 The OarunculaLacrimalis. — The caruncula lacrimalis is a small, reddish, conical- 
 shaped body, situated at the inner canthus of the eye, and filling up the small 
 
 SUPERIOR FORNIX 
 
THE LACHRYMAL APPARATUS 
 
 1141 
 
 triangular space in this situation, the lacus lacrimalis. It consists of an island 
 of skin containing sebaceous and sweat-glands, and is the source of the whitish 
 secretion which constantly collects at the inner angle of the eye. A few slender 
 hairs are attached to its surface. On the outer side of the caruncula is a slight 
 semilunar fold of conjunctiva, the concavity of which is directed toward the 
 cornea; it is called the plica semilunaris (Fig. 751). Miiller found smooth mus- 
 cular fibres in this fold, and in some of the domesticated animals a thin plate of 
 cartilage has been discovered. This structure is considered to be the rudiment 
 of the third eyelid in birds, the membrana nictitans. 
 
 The Lachrymal Apparatus (Apparatus Lacrimalis) (Figs. 750, 751). 
 
 The lachrymal apparatus consists of the lachrymal gland, which secretes the 
 tears, and its excretory ducts, which convey the fluid to the surface of the eye. 
 This fluid is carried away by the lachrymal canals into the lachrymal sac, and along 
 the nasal duct into the cavity of the nose. 
 
 The Lachrymal Glands (glandula lacrimalis). — The lachrymal gland is lodged 
 in a depression at the outer angle of the orbit, on the inner side of the external 
 
 Puncta lachrymalia. 
 
 Fig. 750. — The Meibomian glands, etc., seen from the inner surface of the eyelids. 
 
 angular process of the frontal bone. It is of an oval form, about the size and 
 shape of an almond. Its upper convex surface is in contact with the periosteum 
 of the orbit, to which it is connected by a few fibrous bands. Its under concave 
 surface rests upon the convexity of the eyeball and upon the Superior and External 
 recti muscles. Its vessels and nerves enter its posterior border, whilst its anterior 
 margin is closely adherent to the back part of the upper eyelid, where it is covered 
 to a slight extent by the reflection of the conjunctiva. The forepart of the gland 
 is separated from the rest by a fibrous septum; hence it is sometimes described as 
 a separate lobe, called the inferior lachrymal gland, palpebral portion of the gland, 
 or the accessory gland of Rosenmuller (glandula lacrimalis inferior), the back part 
 of the gland then being called the superior lachrymal gland (glandula lacrimalis 
 superior). The ducts of the lachrymal gland, from six to twelve in number, 
 run obliquely beneath the mucous membrane for a short distance, and, separating 
 from each other, open by a series of minute orifices on the upper and outer half of 
 the conjunctiva near its reflection on to the globe. These orifices are arranged in 
 a row, so as to disperse the secretion over the surface of the membrane. 
 
 Structure of the Lachrymal Gland. — In structure and general appearance the 
 lachrymal resembles the serous salivary glands. In the recent state the cells are so 
 
1142 
 
 THE ORGANS OF SPECIAL SENSE 
 
 Fig. 751. — The lachrymal apparatus. Right side. 
 
 crowded with granules that their Hmits can hardly be defined. Each cell contains 
 an oval nucleus, and the cell-protoplasm is finely fibrillated. 
 
 The Lachrymal Canaliculi or Canals (Fig. 751) commence at the minute orifices, 
 puncta lacrimalia, on the summit of a small conical elevation, the lachrymal papilla 
 or caruncle {carunculus lacrimalis), seen on the margin of the lids at the outer ex- 
 tremity of the lacus lacrimalis. The superior canal (ductus lacrimalis superior), the 
 smaller and shorter of the two, at first ascends, and then bends at an acute angle, 
 and passes inward and downward to the ampulla. The inferior canal (ductus 
 
 lacrimalis inferior) at first descends, 
 and then, abruptly changing its course, 
 passes almost horizontally inward to 
 the ampulla. These canals are dense 
 and elastic in structure and somewhat 
 dilated at their angle. The rtiucous 
 membrane is covered with scaly epi- 
 thelium. The two canals join in a 
 dilatation, the ampulla (ampulla ductus 
 lacrimalis), which empties into the 
 lachrymal sac. 
 
 The Lachrymal Sac (saccus lacri- 
 malis) (Fig. 751). — The lachrymal sac is 
 the upper dilated extremity of the nasal 
 duct, and is lodged in a deep groove 
 formed by the lachrymal bone and the 
 nasal process of the superior maxillary 
 bone. It is oval in form, its upper ex- 
 tremity being closed in and rounded, 
 whilst below it is continued into the nasal duct. It is covered by a fibrous 
 expansion derived from the tendo oculi, and on its deep surface it is crossed by 
 the Tensor tarsi muscle (Horner's muscle, p. 371), which is attached to the ridge 
 on the lachrymal bone. 
 
 Structure. — It consists of a fibrous elastic coat, lined internally by mucous mem- 
 brane, the latter being continuous, through the ampulla and lachrymal canals, 
 with the mucous lining of the conjunctiva, and, through the nasal duct, with the 
 pituitary membrane of the nose. 
 
 The Nasal Duct (ductus nasolacrimalis) (Fig. 751). — The nasal duct is a 
 membranous canal, about three-quarters of an inch in length, which extends from 
 the lower part of the lachrymal sac to the inferior meatus of the nose, where it 
 terminates by a somewhat expanded orifice, provided with an imperfect valve, the 
 valve of Hasner (plica lacrimalis [Hasneri]), formed by the mucous membrane. It 
 is contained in an osseous canal formed by the superior maxillary, the lachrymal, 
 and the inferior turbinated bones, is narrower in the middle than at each extrem- 
 ity, and takes a direction downward, backward, and a little outward. It is lined 
 by mucous membrane, which is continuous below with the pituitary lining of 
 the nose. The membrane in the lachrymal sac and nasal duct is covered with 
 columnar epithelium, as in the nose. This epithelium is in places ciliated. 
 
 Surface Form. — The palpebral fissure, or opening between the eyelids, is elliptical in shape, 
 and differs in size in different individuals and in different races of mankind. In the Mongolian 
 races, for instance, the opening is very small, merely a narrow fissure, and this makes the eye- 
 ball appear small in these races, whereas the size of the eye is relatively very constant. The 
 normal direction of the fissure is slightly oblique, in a direction upward and outward, so that the 
 outer angle is on a slightly higher level than the inner. This is especially noticeable in the Mon- 
 golian races, in whom, owing to the upward projection of the malar bone and the shortness of 
 the external angular process of the frontal bone, "the tarsal plate of the upper lid is raised at its 
 outer part and gives an oblique direction to the palpebral fissure. 
 
THE LACHRYMAL APPARATUS 1143 
 
 When the eyes are directed forward, as in ordinary vision, the upper part of the cornea is 
 covered by the upper hd, and the lower margin of the cornea corresponds to the level of the 
 lower lid, so that about the lower three-fourths of the cornea is exposed under ordinary circum- 
 stances. On the margins of the lids, about a quarter of an inch from the inner canthus, are two 
 small openings, the puncta lacrimalia, the commencement of the lachrymal canals. They are 
 best seen by everting the eyelids. In the natural condition they are in contact w^ith the con- 
 junctiva of the eyeball, and are maintained in this position by the Tensor tarsi muscle, so that 
 the tears running over the surface of the globe easily find their way into the lachrymal canals. 
 The position of the lachrymal sac into which the canals open is indicated by a little tubercle, 
 which is plainly to be felt on the lower margin of the orbit. The lachrymal sac lies immediately 
 above and to the inner side of this tubercle, and a knife passed through the skin in this 
 situation would open the cavity. The position of the lachrymal sac may also be indicated by 
 the tendo oculi or internal tarsal ligament. If both lids be drawn outward, so as to tense the 
 skin at the inner angle, a prominent cord will be seen beneath the tightened skin. This is the 
 tendo oculi, which lies immediately over the lachrymal sac, bisecting it, and thus forming a useful 
 guide to its situation. A knife entered immediately beneath the tense cord would open the 
 lower part of the sac. A probe introduced through this opening can be readily passed down- 
 ward through the duct into the inferior meatus of the nose. The direction of the duct is down- 
 ward, outward, and backward, and this course should be borne in mind in passing the probe, 
 otherwise the point may be driven through the thin bony walls of the canal. A convenient 
 plan is to direct the probe in such a manner that if it were pushed onward it would strike 
 the first molar tooth of the lower jaw on the same side of the body. In other words, the 
 surgeon standing in front of his patient should carry in his mind the position of the first 
 molar tooth, and should push his probe onward in such a way as if he desired to reach this 
 structure. 
 
 Beneath the internal angular process of the frontal bone the pulley of the Superior oblique 
 viuscle of the eye can be plainly felt by pushing the finger backward between the upper and inner 
 angle of the eye and the roof of the orbit; passing backward and outward from this pulley, the 
 tendon can be felt for a short distance. 
 
 Surgical Anatomy. — The eyelids are composed of various tissues, and consequently are liable 
 to a variety of diseases. The skin which covers them is exceedingly thin and delicate, and is 
 supported on a quantity of loose and lax subcutaneous tissue which contains no fat. In conse- 
 quence of this it is very freely movable, and is liable to be drawn down by the contraction of 
 neighboring cicatrices. Such contractions may produce an eversion of the lid known as ectropion. 
 Inversion of the lids (entropion) from spasm of the Orbicularis palpebrarum or from chronic 
 inflammation of the palpebral conjunctiva may also occur. In some individuals there is an extra 
 row of eyelashes on the inner margin of the lid, directed toward the cornea (distichiasis). Trich- 
 iasis is a condition in which the lashes are directed toward the eye, but there is not inversion of 
 the lid. The eyelids are richly supplied with blood, and are often the seat of vascular gro\yths, 
 such as ncpvi. Rodent ulcer also frequently commences in this situation. The loose cellular tissue 
 beneath the skin is liable to become extensively infiltrated either with blood or inflammatory 
 products, producing very great swelling. Even from very slight injuries to this tissue the extrava- 
 sation of blood may be so great as to produce considerable swelling of the lids and complete 
 closure of the eye, and the same is the case when inflammatory products are poured out. The 
 follicles are liable to become inflamed, constituting the disease known as marginal blepharitis, 
 blepharitis ciliaris, or '' blear-ei/e." Irregular or disorderly growth of the eyelashes not unfre- 
 quently occurs, some of them being turned toward the eyeball and producing inflammation and 
 follicles of the eyelashes or the sebaceous glands associated with these follicles may be the seat of 
 inflammation, constituting the ordinary hordeolum or "siij." The Meibomian glands are affected 
 in the so-called " tarsal tumor;" the tumor, according to some, being caused by the retained secre- 
 tion of these glands ; by others it is believed to be a neoplasm connected with the gland. The Orbic- 
 ularis palpebrarum may be the seat of spasm (blepharospasm), either in the form of slight quiv- 
 ering of the lids or repeated twitchings, most commonly due to errors of refraction in children, 
 or more continuous spasm, due to some irritation of the fifth or seventh cranial nerves. The 
 Orbicularis may be paralyzed, generally associated with paralysis of the other facial muscles. 
 Under these circumstances the patient is unable to close the lids, and if he attempts to do so, 
 rolls the eyeball upward under the upper lid. The tears overflow from displacement of the lower 
 lid, and the conjunctiva and cornea, being constantly exposed and the patient being unable to 
 wink, become irritated from dust and foreign bodies. As a result there may be ulceration of 
 the cornea, and possibly eventually complete destruction of the eye. In paralysis of the Levator 
 palpebrae superioris there is drooping of the upper eyelid (ptosis) and other symptoms of impli- 
 cation of the third nerve. The eyelids may be the seat of bruises, wounds, or bums. After 
 wounds or burns adhesions of the margins of the lids to each other or adhesion of the lids to 
 the globe may take place. The eyelids are sometimes the seat of emphysema after fracture of 
 some of the thin bones forming the inner wall of the orbit. If shortly after such an injury the 
 patient blows his nose, air is forced from the nostrils through the lacerated structure into the 
 
1144 THE ORGANS OF SPECIAL SENSE 
 
 connective tissue of the eyelids, which suddenly swell up and present the peculiar crackling on 
 pressure which is characteristic of this affection. 
 
 Foreign bodies frequently get into the conjunctival sac and cause great pain, especially if 
 they come in contact with the corneal surface, during the movements of the lid and the eye on 
 each other. The conjunctiva is frequently involved in severe injuries of the eyeball, but is seldom 
 ruptured alone; the most common form of injury to the conjunctiva alone is from a burn, either 
 from fire, strong acids, or lime. In these cases union is liable to take place between the eyelid 
 and the eyeball. The conjunctiva is often the seat of inflammatio7i arising from many different 
 causes, and the arrangement of the conjunctival vessels should be remembered as affording a 
 means of diagnosis between this condition and injection of the sclerotic, which is present in 
 inflammation of the deeper structures of the globe. The inflamed conjunctiva is bright red; the 
 vessels are large and tortuous, and greatest at the circumference, shading off toward the corneal 
 margin; they anastomose freely and form a dense network, and they can be emptied by gentle 
 pressure. 
 
 The lachrymal gland is occasionally, though rarely, the seat of inflammaiion (dacryoadenitis), 
 either acute or chronic; it is also sometimes the seat of tumors, benign or malignant, and for these 
 may require removal. This may be done by an incision through the skin just below the eyebrow; 
 and the gland, being invested with a special capsule of its own, may be isolated and removed 
 without opening the general cavity of the orbit. The canaliculi may be obstructed, either as a 
 congenital defect or by some foreign body, as an eyelash or a dacryolith, causing the tears to run 
 over the cheek. The canaliculi may also become occluded as the result of burns or injury; over- 
 flow of tears may in addition result from deviation of the puncta or from chronic inflammation 
 of the lachrymal sac. When there is failure of the lachrymal tubes to drain off the tears and 
 the fluid gathers beneath and flows over the lids, the condition is known as epiphora or stilli- 
 cidium. This latter condition is set up by some obstruction to the nasal duct frequently occurring 
 in tuberculous subjects. In consequence of this the tears and mucus accumulate in the lachrymal 
 sac, distending it. Suppuration in the lachrymal sac (dacryocystitis) is sometimes met with; 
 this may be the sequel of a chronic inflammation ; or may occur after some of the eruptive fevers 
 in cases where the lachrymal passages were previously quite healthy. It may lead to lachrymal 
 fistula. 
 
 THE EAR (ORGANON AUDITUS). 
 
 The organ of hearing is divisible into three parts — the external eax, the middle 
 eax or tympanum, and the internal ear or labyrinth. 
 
 THE EXTERNAL EAR (AURIS EXTERNA). 
 
 The external ear consists of an expanded portion named pinna or am'icle, and 
 the auditory canal or meatus. The former serves to collect the vibrations of the air 
 by which sound is produced; the latter conducts those vibrations to the tympanum. 
 
 The Pinna or Auricle (Auricula) (Fig. 752). 
 
 The pinna or auricle is attached to the side of the head midway between the 
 forehead and occiput. "Its level is indicated by horizontal lines extending back- 
 ward from the eyebrows above and from the tip of the nose below."^ It is of an 
 ovoid form, with its larger end directed upward. Its outer surface is irregularly 
 concave, directed slightly forward. The angle which it bears to the head is called 
 the cephalo -auricular angle. In some cases this angle is almost absent. In others 
 it is nearly a right angle. The pinna of one side may vary in size, shape, and 
 angle from the pinna of the other side. The pinna of a woman is apt to be smaller 
 than that of a man, and is less often deformed. The outer surface of the pinna 
 presents numerous eminences and depressions which result from the foldings of its 
 fibro-cartilaginous element. To each of these, names have been assigned. Thus 
 the external prominent rim of the auricle is called the helix. Another curved prom- 
 inence, parallel with and in front of the helix, is called the antihelix; this bifurcates 
 above and forms the crura, which encloses a triangular depression, the fossa of the 
 antihelix (fossae triangularis [auriculae]). The narrow curved depression between 
 
 ' Arthur Hensman in Henry Morris' Human Anatomy. 
 
THE PINNA OB AUBICLE 
 
 1145 
 
 the helix and antihelix is called the fossa of the helix or the scaphoid fossa (scapha) ; 
 the antihelix describes a curve around a deep, capacious cavity, the concha auriculae, 
 
 darwinian 
 tubercle: 
 
 FOSSA 
 TRIANGULARIS 
 
 CRURA OF 
 ANTIHELIX 
 
 SCAPHOID 
 
 FOSSA -. '' I 
 
 POSTERIOR 
 
 AURICULAR 
 
 SULCUS 
 
 INCISURA 
 ANTERIOR 
 
 TUBERCULUM 
 SUPRATRAGICUM 
 
 EXTERNAL 
 AUDITORY 
 MEATUS 
 
 INCISURA 
 INTERTRAGICA 
 
 CAVUM CONCHAE 
 
 Fig. 752. — The right pinna or auricle, \'iewed from without. 
 
 (Spalteholz.) 
 
 INSERTION 
 
 OF SUPERIOR 
 
 AURICULAR 
 
 MUSCLE 
 
 INSERTION 
 
 OF ANTERIOR 
 
 AURICULAR 
 
 MUSCLE 
 
 OBLIQUE 
 
 AURICULAR 
 
 MUSCLE 
 
 which is partially divided into two parts by the cms of the helix, or the commence- 
 ment of the helix; the upper part is termed the cymba conchae, the lower part the 
 cavum conchae. In front of the 
 concha, and projecting backward 
 over the meatus, is a small pointed 
 eminence, the tragus, so called from 
 its being generally covered on its 
 under surface with a tuft of hair 
 resembling a goat's beard. Oppo- 
 site the tragus, and separated from 
 it by a deep notch (incisuria inter- 
 tragica) is a small tubercle, the 
 antitragus. Below this is the lobule 
 (lohulus auriculae), composed of 
 tough areolar and adipose tissue, 
 wanting the firmness and elasticity 
 of the rest of the pinna. Some- 
 times the lobule does not hang 
 freely, but is adherent. Where 
 the helix turns downward a small 
 tubercle, the tubercle of Darwin {tuherculum auriculae [Darwini]), is frequently seen. 
 This tubercle is very evident about the sixth month of fcetal life; at this stage 
 the human pinna has a close resemblance to that of some of the adult monkeys. 
 
 INSERTION OF 
 
 POSTERIOR 
 
 AURICULAR 
 
 MUSCLE 
 
 TRANSVERSE 
 
 AURICULAR 
 
 MUSCLE 
 
 CARTILAGE 
 
 OF EXTERNAL 
 
 AUDITORY 
 
 MEATUS 
 
 Fig. 753. — The cartilages of the right auricle, isolated, with 
 the muscles, viewed from the inside. (Spalteholz.) 
 
1146 
 
 THE ORGANS OF SPECIAL SENSE 
 
 The cranial surface of the pinna presents elevations which correspond to the 
 depressions on its outer surface and after which they are named, e. g., eminentia 
 conchae, eminentia fossae triangularis, etc. 
 
 The eminentia conchae and the fossae triangularis are separated by a furrow 
 (sulcus antihelicis transversus) , which corresponds to the inferior crus of the anti- 
 heUx, or groove (sulcus cruris helicis), and upon the eminence there is a vertical 
 ridge, the ponticulus, which indicates the point of insertion of the Retrahens 
 auriculam muscle. 
 
 Structure of the Pinna. — The pinna is composed of a thin plate of yellow 
 fibro-cartilage, covered with integument, and connected to the surrounding parts 
 by the extrinsic ligaments and muscles, and to the commencement of the external 
 auditory canal by fibrous tissue. 
 
 The Integument. — The integument is thin, closely adherent to the cartilage, and 
 covered with hairs furnished with sebaceous glands, which are most numerous in 
 the concha and scaphoid fossa. The hairs are most numerous and largest on the 
 tragus and antitragus. 
 
 The Cartilage of the Pinna (cartilago auriculae) (Fig. 754).— The cartilage of the 
 pinna consists of one single piece; it gives form to this part of the ear, and upon its 
 
 surface are found all the eminences 
 and depressions above described. 
 It does not enter into the construc- 
 tion of all parts of the auricle ; thus 
 it does not form a constituent part 
 of the lobule; it is deficient also 
 between the lamina of the tragus 
 and beginning of the crus helix, the 
 notch between (incisura terminalis 
 awm)them being filled up V)y dense 
 fibrous tissue. At the front part of 
 the pinna,where the helix bends up- 
 ward, is a small projection of car- 
 tilage, called the spine of the helix 
 (spina helicis), while the lower part 
 of the helix is prolonged downward 
 as a tail-like process, the cauda 
 helicis; this is separated from the 
 antihelix by a fissure, the fissura antitragohelicina. The fissures of Santorini are 
 usually two in number: one in- the substance of the tragus, which partially separates 
 the different parts, and one in the cartilage of the meatus. The fissure of the helix 
 is a short vertical slit, situated at the forepart of the pinna. Another fissure, the 
 fissure of the tragus, is seen upon the anterior surface of the tragus. Anteriorly 
 and inferiorly the cartilage of the pinna is continuous with the cartilage of the 
 external auditory meatus by a cartilaginous isthmus (isthmus cartilaginis auris). 
 Some authors regard the tragus as part of the cartilage of the meatus. The 
 cartilage of the pinna is very pliable, elastic, of a yellowish color and belongs to 
 that form of cartilage which is known under the name of yellow fibro-cartilage. 
 The Ligaments of the Tinna. (ligamenti auricularia [Valsalvae]). — The ligaments 
 of the pinna consist of two sets: 1. The extrinsic set, or those connecting it to the 
 side of the head. 2. The intrinsic set, or those connecting the various parts of its 
 cartilage together. 
 
 The Extrinsic Ligaments, the most important, are three in number: superior, 
 anterior, and posterior. The superior ligament (ligamentum auriculare superius) 
 extends from the suprameatal spine to the spine of the helix. The anterior ligament 
 (ligamentum auriculare anterius) extends from the spina helicis and tragus to the 
 
 FISSURA 
 
 ANTirnAGICO- 
 
 HELICINA 
 
 CAUDA 
 HE 
 
 TRIANGULAR 
 FOSSA 
 
 SPINE OF 
 HELIX 
 
 RUS OF 
 ELIX 
 
 LAMINA 
 
 TRAGI 
 
 INCISURA 
 
 TERMINALIS 
 
 AURIS 
 
 ANTITRAGUS 
 
 Fig. 754.— The right ear cartilages, isolated, viewed from 
 without. (Spalteholz.) 
 
THE PINNA OB AURICLE 
 
 1147 
 
 root of the zygoma. The posterior ligament (ligamentum auriculare posterius) 
 passes from the posterior surface of the concha to the outer surface of the mastoid 
 process of the temporal bone. 
 
 The chief Intrinsic Ligaments are: (1) a strong fibrous band, stretching across 
 from the tragus to the commencement of the heHx, completing the meatus in front, 
 and partly encircling the boundary of the concha; and (2) a band which extends 
 between the antihelix and the cauda helicis. Other less important bands are 
 found on the cranial surface of the pinna. 
 
 The Muscles of the Pinna (Figs. 753 and 755). — The muscles of the pinna consist 
 of two sets : 1. The extrinsic, which connect it with the side of the head, moving the 
 pinna as a whole — viz., the Attollens, Attrahens, and Retrahens auriculam (p. 369). 
 2. The intrinsic, which extend from one part of the auricle to another, viz. : 
 
 Helicis major. 
 Helicis minor. 
 Tragicus. 
 
 Antitragicus. 
 Transversus auriculae. 
 Obliquus auriculae. 
 
 vertical band of muscular 
 It arises, below, from the 
 
 The Helicis Major (m. helicis major) is a narrow 
 fibres, situated upon the anterior margin of the helix 
 Cauda helicis, and is inserted into 
 the anterior border of the helix, just 
 where it is about to curve backward. 
 It is pretty constant in its existence. 
 
 The Helicis Minor (m. helicis minor) 
 is an oblique fasciculus which covers 
 the crus helicis. 
 
 The Tragicus (m. tragicus) is a 
 short, flattened band of muscular 
 fibres situated upon the outer surface 
 of the tragus, the direction of its 
 fibres being vertical. 
 
 The Antitragicus (m. antitragicus) 
 arises from the outer part of the anti- 
 tragus; its fibres are inserted into the 
 cauda helicis and antihelix. This 
 muscle is usually very distinct. 
 
 The Transversus Auriculae (m. 
 transversus auriculae) is placed on 
 the cranial surface of the pinna. It 
 consists of scattered fibres, partly 
 tendinous and partly muscular, ex- 
 tending from the convexity of the 
 concha to the prominence corre- 
 sponding with the groove of the helix. 
 
 The Obliquus Auriculae (Tod) (m. 
 obliquus auriculae) consists of a few 
 
 fibres extending from the upper and back part of the concha to the convexity 
 immediately above it. 
 
 The Arteries of the Pinna. — The arteries of the pinna are the posterior auricular 
 from the external carotid, the anterior auricular from the temporal and an auric- 
 ular branch from the occipital artery. 
 
 The Veins of the Pinna. — The veins of the pinna accompany the corresponding 
 arteries. 
 
 The Lymphatics of the Pinna. — The lymphatics enter into the pre-auricular glands 
 and the glands upon the Sterno-mastoid muscle at its insertion. 
 
 Fig. 755. — The muscles of the pinna. 
 
1148 
 
 THE ORGANS OF SPECIAL SENSE 
 
 The Nerves of the Pinna. — The nerves of the pinna are: the auricularis magnus, 
 from the cervical plexus ; the auricular branch of the pneumogastric ; the auriculo- 
 temporal branch of the inferior maxillary nerve; the occipitalis minor from the 
 cervical plexus, and the occipitalis major or internal branch of the posterior 
 division of the second cervical nerve. The muscles of the pinna are supplied by 
 the facial nerv^e. 
 
 The External Auditory or External Acoustic Canal or External Auditory 
 
 Meatus (Meatus Acusticus Externus or Meatus 
 
 Auditorius Externus). 
 
 The external auditory or acoustic canal or meatus extends from the bottom 
 of the concha to the membrana tympani (Figs. 752, 756, and 757). It is about 
 an inch and a half in length if measured from the tragus; from the bottom of 
 the concha its length is about an inch. It forms a sort of S-shaped curve, and is 
 directed at first inward, forvi'ard, and slightly upward {"pars externa); it then 
 passes inward and backward {'pars media), and lastly is carried inward, forward, 
 and slightly downward {pars interna). It forms an oval cylindrical canal, the 
 greatest diameter being in the vertical direction at the external orifice, but in the 
 
 Cartilage of 
 the pinna ' 
 
 Promont. 
 
 Int. carot. a. \ '•» ;' / ;7?S>_: 
 
 Membrana / ' ;5 Ifi'Ast^ 
 tympani / ^' '"'■". %i'3jl\ 
 
 Cartilage of the ext. a!j -flMJ 
 auditory meatus 
 
 Fig. 756. — Transverse section of external auditory meatus and tympanum. Left side. (Gegenbauer.) 
 
 transverse direction at the tympanic end. It presents two constrictions, one 
 near the inner end of the cartilaginous portion, and another, the isthmus, in the 
 osseous portion, about three-quarters of an inch from the bottom of the concha. 
 The membrana tympani (Figs. 756 and 757), which occupies the termination of the 
 meatus, is directed obliquely, in consequence of which the floor of the canal is 
 longer than the roof, and the anterior wall longer than the posterior. The auditory 
 canal is formed partly by cartilage and membrane, partly by bone, and is lined by 
 perichondrium and periosteum, which is covered with skin. 
 
 The Cartilaginous Portion {meatus acusticus externum cartilagineus) . — The car- 
 tilaginous portion is about one-third of an inch (8 mm.) in length; it is formed 
 by the cartilage of the pinna, prolonged inward, and firmly attached to a greater 
 portion of the circumference of the auditory process of the temporal bone. The 
 cartilage is deficient at its upper and back part, its place being supplied by fibrous 
 membrane. This part of the canal is rendered extremely movable by two or 
 three deep fissures, the fissures of Santorini {incisurae cartilaginis meatus acu^stici 
 externi [Santorini^ , v/hich extend through the cartilage in a vertical direction. 
 It is firmly attached at its lower and front part to the posterior root of the zygoma 
 and to the lateral edge of the tympanic portion of the temporal bone. 
 
THE EXTERNAL AUDITORY MEATUS 
 
 1149 
 
 The Osseous Portion {meatus acusticus extemus osseus). — The osseous por- 
 tion is about two-thirds of an inch (16 mm.) in length, and narrower than the 
 cartilaginous portion. It is directed inward and a little forward, forming a slight 
 curve in its course, the convexity of which is upward and backward. Its inner 
 end, which communicates, in the dry bone, with the cavity of the tympanum, is 
 smaller than the outer and sloped, the anterior wall projecting beyond the poste- 
 rior about two lines; it is marked, except at its upper part, by a narrow groove, 
 the tympanic sulcus (.sulcus tympanicus), for the insertion of the membrana tym- 
 pani. Its outer edge is dilated and rough in the greater part of its circumference, 
 for the attachment of the cartilage of the pinna. Its vertical transverse section 
 is oval, the greatest diameter being from above downward. The front and lower 
 parts of this canal are formed by a curved plate of bone, which, in the fcetus, 
 exists as a separate ring {annulus tympanicus), incomplete at its upper part. (See 
 Section on Osteology.) 
 
 FENESTRA OVALIS 
 LOSEO BY STAPES 
 
 Fig. 757. 
 
 -Vertical section through the external auditory meatus and tympanum, passing in front of the 
 fenestra ovalis. (Testut.) 
 
 The Skin of the Meatus. — The skin lining the meatus is a prolongation of the 
 external skin; it is thin, adheres closely to the cartilaginous and osseous portions 
 of the tube, and covers the surface of the membrana tympani, forming a very 
 thin outer layer. After maceration the thin pouch of epidermis, when withdrawn, 
 preserves the form of the meatus. In the thick subcutaneous tissue of the cartil- 
 aginous part of the meatus are numerous ceruminous glands (glandulae ceruminosae) 
 which secrete the ear-wax. They resemble in structure sweat-glands, and their 
 ducts open on the surface of the skin. 
 
 Relations of the Meatus. — In front of the osseous part is the glenoid fossa, which 
 receives the condyle of the mandible (Fig. 759), which, however, is separated from 
 the cartilaginous part by the retromandibular part of the parotid gland. The 
 movements of the jaw influence to some extent the lumen of the cartilaginous 
 portion. Behind the osseous part are the mastoid air-cells, separated from it 
 by a thin layer of bone (Fig. 46). 
 
 The Arteries of the External Meatus. — The arteries supplying the external meatus 
 are branches from the posterior auricular, internal maxillary, and superficial 
 temporal. 
 
1150 THE ORGANS OF SPECIAL SENSE 
 
 The Veins of the External Meatus. — Veins accompany the corresponding arteries 
 and pass to the internal maxillary, temporal, and posterior auricular veins. 
 
 The Lymphatics of the External Meatus. — The lymphatics accompany the veins 
 and enter the parotid and posterior auricular lymph-glands. 
 
 The Nerves of the External Meatus. — The nerves are derived from the auriculo- 
 temporal branch of the inferior maxillary nerve, the auricularis magnus, and the 
 auricular branch of the pneumogastric. 
 
 Surface Form. — The point of junction of the osseous and cartilaginous portions of the tube 
 is an obtuse angle, which projects into the canal at its antero-inferior wall. This produces a 
 sort of constriction in this situation, and renders it the narrowest portion of the canal — an impor- 
 tant point to be borne in mind in connection with the presence of foreign bodies in the ear. 
 The cartilaginous is connected to the bony part by fibrous tissue, which renders the outer part 
 of the tube very movable, and therefore by drawing the pinna upward and backward the canal 
 is rendered almost straight. At the external orifice are a few short, crisp hairs which serve to 
 prevent the entrance of small particles of dust, flies or other insects. In the external auditory 
 meatus the secretion of the ceruminous glands serves to catch any small particles which may 
 find their way into the canal, and prevent their reaching the membrana tympani, where their 
 presence might excite irritation. In young children the meatus is short, the osseous part 
 being very deficient, and consisting merely of a bony ring (annulus tympanicus), which supports 
 the membrana tympani. In the fcetus the osseous part is entirely absent. The shortness of the 
 canal in children should be borne in mind in introducing the aural speculum, so that it shall not 
 be pushed in too far, at the risk of injuring the membrana tympani; indeed, even in the adult the 
 speculum should never be introduced beyond the constriction which marks the junction of the 
 osseous and cartilaginous portions. In using this instrument it is advisable that the pinna 
 should be drawn upward, backward, and a little outward, so as to render the canal as straight as 
 possible, and thus assist the operator in obtaining, by the aid of reflected light, a good view of 
 the membrana tympani. Just in front of the membrane is a well-marked depression, situated 
 on the floor of the canal and bounded by a somewhat prominent ridge; in this foreign bodies 
 may become lodged. By aid of the speculum, combined with traction of the auricle upward 
 and backward, the whole of the membrana tympani is rendered visible. It is a pearly-gray mem- 
 brane, slightly glistening in the adult, placed obliquely, so as to form with the floor of the meatus 
 a very acute angle (about 55 degrees), while with the roof it forms an obtuse angle. At birth it 
 is more horizontal — being situated in almost the same plane as the base of the skull. About 
 midway between the anterior and posterior margins of the membrane, and extending from the 
 centre obliquely upward, is a reddish-yellow streak; this is the handle of the malleus, which is 
 inserted into the membrane (Fig. 760). At the upper part of this streak, close to the roof of the 
 meatus, a little white rounded prominence is plainly to be seen; this is the processus brevis of 
 the malleus, projecting against the membrane. The membrana tympani does not present a 
 plane surface; on the contrary, its centre is drawn inward, on account of its connection with the 
 handle of the malleus, and thus the external surface is rendered concave. 
 
 THE MIDDLE EAR, DRUM OR TYMPANUM (AURIS MEDIA) 
 
 (Figs. 756, 757, 758, 762). 
 
 The middle ear or tympanum is an irregular cavity, compressed from without 
 inward, and is situated within the petrous portion of the temporal bone. It is 
 placed above the jugular fossa; the carotid canal lying in front, the mastoid cells^ 
 behind, the external auditory meatus externally, and the labyrinth internally. It is 
 lined with mucous membrane, is filled with air, and communicates with the mas- 
 toid cells, and with the naso-pharynx by the Eustachian tube. The tympanum is 
 traversed by a chain of movable bones, which connect the membrana tympani 
 with the labyrinth, and serve to convey the vibrations communicated to the mem- 
 brana tympani across the cavity of the tympanum to the external ear. In shape 
 it is roughly biconcave, the concave surfaces being placed vertically and forming 
 the external and internal walls. The cavity forms an angle of 45 degrees with the 
 median plane (Spalteholz). 
 
 The Tympanic Cavity (cavum tympani) (Figs. 762 and 763) . — The tympanic 
 cavity consists of two parts: the atrium or tympanic cavity proper (Fig. 763), 
 opposite the tympanic membrane, and the attic or epitympanic recess or aditus 
 ad antrum {recessus epitympanicus) (Figs. 761 and 762), above the level of the 
 
THE MIDDLE EAR, DRUM OR TYMPANUM 
 
 1151 
 
 upper part of the membrane; the latter contains the upper half of the malleus 
 and the greater part of the incus. The diameter of the tympanic cavity, 
 including the attic, measures about f inch (15 mm.) vertically and trans- 
 versely. From without inward it measures about \ inch (6 mm.) above and \ 
 inch (4 mm.) below; opposite the centre of the tympanic membrane it is only 
 about -^ inch (2 mm.). It is bounded externally by the membrana tympani and 
 meatus; internally, by the outer surface of the internal ear; and communicates 
 behind with the mastoid antrum and through it with the mastoid cells; and in 
 front with the Eustachian tube and canal for the Tensor tympani. Its roof and 
 floor are formed by thin osseous laminae, the one forming the roof being a thin 
 plate situated on the anterior surface of the petrous portion of the temporal bone, 
 close to its angle of junction with the squamous portion of the same bone. 
 
 The Roof of the Tympanum (paries tegmentalis). — The roof of the tympanum 
 is broad, flattened, and formed of a thin plate of bone (tegmen tympani) (Fig. 
 762), which separates the cranial and tympanic cavities. It is prolonged back- 
 ward so as to roof in the mastoid antrum; it is also carried forward to cover in 
 the canal for the Tensor tympani muscle. 
 
 The Floor (paries jugularis) (Fig. 762). — The floor is narrow, and is separated 
 by a thin plate of bone (Jundus tympani) from the jugular fossa. It frequently 
 
 Chorda tympani 
 
 Fig. 758. — View of the inner wall of the tympanum (enlarged). 
 
 presents numerous small notches in the bone (cellulae tympanicae). There is one 
 small aperture in the floor. It is near the inner wall and is the opening of the 
 canaliculus tympanicus, for the transmission of Jacobson's nerve (n. tympanicus). 
 On the floor near the posterior wall there is often to be found a slight bony 
 projection (prominentia styloideae). 
 
 The Outer Wall (Fig. 757). — The outer wall is formed mainly by the membrana 
 tympani, partly by the ring of bone into which this membrane is inserted. The 
 part formed by the membrana tympanum is called the paries membranaceus. This 
 ring of bone is incomplete at its upper part, forming a notch, the notch of Rivinus 
 (incisura tympanica [Rivini]) (Fig. 760). The anterior edge of the notch is 
 known as the spina tympanica major, the posterior edge as the spina tympanica 
 minor. The groove for the reception of the membrana tympani is the sulcus 
 tympanicus. Close to the notch are three small apertures: the iter chordae pos- 
 terius, the Glaserian fissure, and the iter chordae anterius. 
 
 The iter chordae posterius or the tympanic aperture (canaliculus chordae tympani) 
 (Fig. 761) is in the angle of junction between the posterior and external walls of 
 the tympanum, immediately behind the membrana tympani and on a level with the 
 upper end of the handle of the malleus; it leads into a minute canal, which descends 
 
1152 THE ORGANS OF SPECIAL SENSE 
 
 in front of the aquaeductus Fallopii, and terminates in the aqueduct near the 
 stylomastoid foramen. Through it the chorda tympani nerve enters the tym- 
 panum. 
 
 The Glaserian or petro-tympanic fissure (fissura petrotympanica [Glaseri]) (Fig. 
 761) opens just above and in front of the ring of bone into which the membrana 
 tympani is inserted; in this situation it is a mere sHt about a hne in length. It 
 lodges the long process and anterior ligament of the malleus, and gives passage 
 to the tympanic branch of the internal maxillary artery. 
 
 The iter chordae anterius (Fig. 761) is seen at the inner end of the preceding 
 fissure; it leads into a canal, the canal of Huguier, which runs parallel with the 
 Glaserian fissure. Through it the chorda tympani nerve leaves the tympanum. 
 
 The outer wall bounds the epitym panic recess externally. 
 
 The Internal Wall of the Tympanum (paries lahyrinthica) (Figs. 758 and 762). — 
 The internal wall of the tympanum is adjacent to the labyrinth, is vertical in direc- 
 tion, and looks directly outward. It presents for examination the following parts: 
 
 Fenestra ovalis. Promontory. 
 
 Fenestra rotunda. Ridge of the aquaeductus Fallopii. 
 
 Prominence of the external semicircular canal. 
 
 The Fenestra Ovalis, the Oval or the Vestibular Window {fenestra vestibuli) (Fig. 
 758) is a reniform opening leading from the tympanum into the vestibule. It 
 is situated in the depths of a fossa (fossula fenestrae vestibuli). Its long diameter 
 is directed horizontally, and its convex border is upward. The opening in the 
 recent state is occupied by the base of the stapes (Figs. 757 and 763), which is 
 connected to the margin of the foramen by an annular ligament. 
 
 The Fenestra Rotunda, the Round or Cochlear Window (fenestra cochleae) (Fig. 
 758) is an aperture placed at the bottom of a funnel-shaped depression (fossula 
 fenestrae cochleae) leading into the cochlea. It is situated below and rather 
 behind the fenestra ovalis, from which it is separated by a rounded elevation, the 
 promontory; at its border is a narrow ridge of bone (crista fenestrae cochleae), and 
 it is closed in the recent state by a membrane, the membrane of Scarpa or the 
 secondary ear-drum membrane (membrana tympani secundaria). This membrane 
 is concave toward the tympanum, convex toward the cochlea. It consists of 
 three layers: the external or mucous, derived from the mucous lining of the 
 tympanum; the internal, from the lining membrane of the cochlea; and an inter- 
 mediate or fibrous layer. 
 
 The Promontory (promontorium) (Fig. 762) is a rounded hollow prominence, 
 formed by the projection outward of the first turn of the cochlea; it is placed 
 between the fenestrae, and is furrowed on its surface (sulcus promontorii) for the 
 lodgement of the tympanic plexus. A minute spicule of bone frequently connects 
 the promontory to the pyramid. 
 
 The Rounded Eminence of the Aquaeductus Fallopii (prominentia canalis facialis) 
 (Fig. 762) , the prominence of the bony canal in which the facial nerve is contained, 
 traverses the inner wall of the tympanum above the fenestra ovalis, and behind 
 that opening curves nearly vertically downward along the posterior wall. 
 
 Just above the eminence of the aquaeductus Fallopii the wall is bulged by the 
 external semicircular canal (prominentia canalis semicircularis lateralis). 
 
 The Posterior Wall of the Tympanum (paries mastoidea) (Fig. 762). — The pos- 
 terior wall of the tympanum is wider above than below, and the lower portion of 
 the posterior wall contains many tympanic cells. The posterior wall presents for 
 examination the — 
 
 Opening of the antrum. Prominentia styloideae. 
 
 Fossa incudis. Pyramid. 
 
 Apertura tympanica canaliculi chordae. 
 
THE MIDDLE EAR, DRUM OB TYMPANUM 1153 
 
 The Opening of the Antrum is a large irregular aperture, which extends back- 
 ward from the epitympanic recess and leads into a considerable air space, the 
 mastoid antrum {antrum tympanicum) , which is the entrance to the mastoid cells 
 (p. 87). The antrum communicates with large irregular cavities contained 
 in the interior of the mastoid process, the mastoid air-cells. These cavities vary 
 considerably in number, size, and form; they are lined by mucous membrane 
 continuous with that lining the cavity of the tympanum. 
 
 The Fossa Incudis (Fig. 762) is placed in the posterior and inferior part of the 
 epitympanic recess. It lodges the short process of the incus. 
 
 The Prominentia Styloideae is sometimes seen below the apertura tympanica 
 canaliculi chordae. It is a prominence produced by a prolongation of the styloid 
 process. 
 
 The Pyramid (eminentia pyramidalis) (Fig. 758) is a conical eminence situated 
 immediately behind the fenestra ovalis, and in front of the vertical portion of the 
 eminence above described ; it is hollow in the interior, and contains the Stapedius 
 muscle; its summit projects forward toward the fenestra ovalis, and presents a 
 small aperture which transmits the tendon of the muscle. The cavity in the 
 pyramid is prolonged into a minute canal, which communicates with the aquae- 
 ductus Fallopii and transmits the nerve which supplies the Stapedius. 
 
 The Apertura Tympanica Canaliculi Chordae is just back of the posterior edge of the 
 tympanic membrane, nearly level with the superior end of the manubrium mallei. 
 
 The Anterior Wall of the Tympanum (paries carotica). — ^The anterior wall of 
 the tympanum is bony on its lower portion. Its upper part is the tympanic 
 opening of the Eustachian tube. The long anterior wall contains tympanic 
 cells. The anterior wall is wider above than below; it corresponds with the 
 carotid canal, from which it is separated by a thin plate of bone (Fig. 762), per- 
 forated by the canaliculi caroticotympanici, which transmit the tympanic branch 
 of the internal carotid artery and the carotico-tympanic nerves. It presents for 
 examination the — 
 
 Canal for the Tensor tympani. Orifice of the Eustachian tube. 
 
 The processus cochleariformis. 
 
 The orifice of the canal for the Tensor tympani and the orifice of the Eustachian 
 tube are situated at the upper part of the anterior wall, being incompletely sepa- 
 rated from each other by a thin, delicate, horizontal plate of bone, the processus 
 cochleariformis (septum canalis musculotubarii) (Figs. 49 and 758). The canalis 
 musculotubarius is divided by this long process into the canal for the Tensor 
 tympani and the canal for the Eustachian tube. These canals run from the 
 tympanum forward, inward, and a little downward, to the retiring angle between 
 the squamous and petrous portions of the temporal bone. 
 
 The Canal for the Tensor Tympani (semicanalis m. tensoris tympani) (Figs. 49, 
 758, and 762) is the superior and the smaller of the two; it is rounded and lies 
 beneath the forward prolongation of the tegmen tympani. It extends on to the 
 inner wall of the tympanum and ends immediately above the fenestra ovalis. The 
 processus cochleariformis passes backward below this part of the canal, forming 
 its outer wall and floor; it expands above the anterior extremity of the fenestra 
 ovalis and terminates by curving outward so as to form a pulley over which the 
 tendon passes. The bony wall of this canal is incomplete, and the osseous vacancy 
 is filled by tough connective tissue. 
 
 The Eustachian Tube or Ear Trumpet (tuba auditiva [Eustachii]) (Figs. 49, 
 758, and 759) is the channel through which the tympanum communicates with 
 the pharynx. Its length is an inch and a half (36 mm.), and its direction 
 downward, inward, and forward, forming an angle of about 45 degrees with 
 the sagittal plane and one of from 30 to 40 degrees with the horizontal plane. 
 
 73 
 
1154 
 
 THE ORGANS OF SPECIAL SENSE 
 
 The canal for the Eustachian tube (semicanalis tuhae auditivae) (Fig. 759) is formed 
 partly of bone, partly of cartilage and fibrous tissue. 
 
 The Osseous Portion {"pars ossea tuhae auditivae or semicanalis tuhae auditivae) 
 is about half an inch in length. It is the outer portion of the tube. It commences 
 in the anterior wall of the tympanum, below the processus cochleariformis {ostium 
 tympanicum tuhae auditivae), and, gradually narrowing, terminates at the angle 
 of junction of the petrous and squamous portions of the temporal bone, its 
 extremity presenting a jagged margin which serves for the attachment of the 
 cartilaginous portion. The roof of the osseous portion is the tegmen tympani. 
 The inner wall is formed in part by the inner wall of the tympanum and in part 
 by the canal for the Tensor tympani muscle. The outer wall is the tympanic 
 portion of the temporal bone. The floor is a groove which near the tympanum 
 contains the openings of air-cells {ceUulae pneuviatici tubarii). 
 
 MEMBRANA 
 TYMPANI 
 
 PHARYNGEAL OPEN- 
 ING OF TUBE 
 
 Fig. 759. — Eustachian tube, laid open by a cut in its long axis. (Testut.) 
 
 The Cartilaginous Portion (pars cartilaginea tuhae auditivae), about an inch in 
 length, is formed of a triangular plate of elastic fibro-cartilage (cartilago tuhae 
 auditivae), the apex of which is attached to the margin of the inner extremity of 
 the osseous canal, while its base lies directly under the mucous membrane of 
 the naso-pharynx, where it forms an elevation or cushion above and behind the 
 pharyngeal orifice of the tube. The upper edge of the cartilage is curled upon 
 itself, being bent outward so as to present on transverse section the appearance of 
 a hook (lamina lateralis) ; a groove or furrow is thus produced, which opens below 
 and externally, and this part of the canal is completed by fibrous membrane. On 
 transverse section the cartilage exhibits the laminae which above are continuous 
 with each other: the hard, thick lamina medialis and the thin and hooked lamina 
 lateralis. The cartilage of the Eustachian tube, with a hood plate of cartilage, 
 forms the posterior portion of the inner wall (the lamina medialis). The cartilage 
 is fixed to the base of the skull, and lies in a groove (sulcus tuhae auditivae) 
 between the petrous-temporal and the greater wing of the sphenoid; this groove 
 ends opposite the middle of the internal pterygoid plate, in a projection, the 
 
THE MIDDLE EAR, DRUM OB TYMPANUM 
 
 1155 
 
 processus tubarius. At the pharyngeal orifice the entire wall of the tube is cartil- 
 aginous, hut the breadth of the cartilage progressively lessens as the isthmus is 
 approached. Here and there the cartilage is deficient or pieces lie separate from 
 the rest, the spaces between the islands being occupied by fibrous tissue. The Ten- 
 sor palati muscle is placed to the outer side of the tube. The fibres of the muscle 
 which take origin from the lamina lateralis are known as the dilator tubae muscle of 
 Rudinger. The Tensor palati muscle and the mucous membrane of the pharynx lie to 
 the inner side of the tube. The under and outer portion of the canal is completed 
 by the membranous part {lamina membranacea) , which is a strong fibrous mem- 
 brane, passing between the two margins of the cartilage. It is thin above, but thick 
 below, and the thick portion is called the fascia salpingopharyngea of Trbltsch, 
 and from it arise some fibres of the Tensor palati (m. salpingopharyngeus). The 
 cartilaginous and bony portions of the tube are not in the same plane, the former 
 
 POSTERIOR TYMPANO- 
 MALLEOLAR FOLD 
 
 FLACCID PORTION OF 
 MEMBRANA TYMPANI 
 
 POSTERIOR 
 
 TYMPANIC. 
 
 SPINC 
 
 EXTERNAL 
 AUDITORY- 
 MEATUS 
 
 MARGIN OF 
 MEMBRANA 
 
 TYMPANI ' 
 OR LIMBUS 
 
 MALLEOLAR 
 PROMINENCE. 
 
 NOTCH OF 
 RIVINUS 
 
 ANTERIOR 
 TYMPANO- 
 MALLEOLAR 
 FOLD 
 
 HANDLE OF 
 MALLEOLUS 
 SEEN THROUGH 
 MEMBRANE 
 
 TENSE PORTION 
 OF MEMBRANA 
 TYMPANI 
 
 I Fig. 760. — The right membrana tympani, viewed from the outside, from in front, and from below. (Spalteholz.) 
 
 ^■inclining downward a little more than the latter. They join each other at a large 
 ^■obtuse angle, open below. The diameter of the canal is not uniform throughout, 
 ^^being greatest at the pharyngeal orifice and least at the junction of the bony and 
 cartilaginous portions, where it is named the isthmus (isthmus tubae audiiivae) ; 
 it again expands somewhat as it approaches the tympanic cavity. The 
 position and relations of the pharyngeal orifice (ostium pharyngeum tubae 
 aiuliticae) are described with the anatomy of the naso-pharynx. Through this 
 canal the mucous membrane of the pharynx is continuous with that which lines 
 the tympanum. The mucous membrane is covered with ciliated epithelium and 
 is thin in the osseous portion, while in the cartilaginous portion it contains many 
 mucous glands and near the pharyngeal orifice a considerable amount of adenoid 
 tissue, which has been named by Gerlach the tube-tonsil. The tube is opened 
 during deglutition by the Salpingo-pharyngeus and Dilator tubae muscles. 
 
 The Drumhead or Membrana Tympani (Figs. 757, 759, 760, and 761).— The 
 membrana tympani or drumhead separates the cavity of the tympanum from 
 
1156 
 
 THE ORGANS OF SPECIAL SENSE 
 
 the bottom of the external meatus. It is a thin, semi-transparent membrane, 
 nearly oval in form, somewhat broader above than below, and directed very 
 obliquely downward and inward, so as to form an angle of about 55 degrees 
 with the floor of the meatus (Fig. 757) . The antero-inferior portion is, there- 
 fore, placed at the greatest distance from the external orifice of the meatus. It 
 is asserted that in musicians the membrana tympani is placed more nearly per- 
 pendicular, and that in deaf-mutes and cretins it is placed more obliquely than 
 the usual 55 degrees. In a newborn child the membrana tympani is almost hori- 
 zontal. The greatest diameter of the membrana tympani is from 9 to 10 mm.; 
 its least diameter is from 8 to 9 mm.^ The greater part of its circumference (limhus 
 membranae tympanae) is thickened to form an annular ring (annulus fibrocartil- 
 agineus), which is fixed in a groove, the sulcus tympanicus, at the inner extremity 
 
 SUPERIOR LIGAMENT 
 OF MALLEOLUS 
 
 EPITYMPANIC 
 RECESS 
 
 ANTERIOR LIGAMENT 
 
 AND ANTERIOR 
 
 PROCESS OF 
 
 MALLEOLUS 
 
 INSERTION 
 OF TENSOR 
 TYMPAN 
 MUSCL 
 
 GLASSCrtlAN 
 FISSURE 
 
 NCCK OF 
 
 MALLEUSV ,f 
 
 ARTICULAR SURFACE 
 TOR BODY OF INCUS 
 
 FLACCID PORTION OF 
 MEMBRANA TYMPANI 
 
 POSTERIOR 
 
 TYMPANIC 
 
 SPINE 
 
 TYMPANIC 
 ORIFICE 
 OF CANAL 
 FOR CHORDA 
 TYMPANI 
 NERVE 
 
 EUSTACHIAN 
 TUBE 
 
 TENSE PORTION OF 
 MEMBRANA TYMPANI 
 
 Fig. 761. — The right membrana tympani with the hammer and the chorda tympani, viewed from within, 
 from behind, and from above. (Spalteholz.) 
 
 of the external meatus. This sulcus is deficient superiorly at the incisure or notch 
 of Rivinus (incisura tym'panica \Rivini\) (Fig. 760) . From the extremities of the 
 notch (spinae tympanicae) two folds pass and converge to the short process of the 
 malleus (Fig. 760) . One is known as the anterior tympanomalleolar fold or ligament 
 (plica membrana tyrnpani anterior). The other is known as the posterior tympano- 
 malleolar fold or ligament (plica membrana tympani posterior). These are not to 
 be confused with the anterior and posterior malleolar folds (p. 1162). The small, 
 somewhat triangular part of the membrane situated above these folds is lax and 
 thin, and is named the flaccid portion or the membrana flaccida of Shrapnell (Figs. 
 760 and 761). In it a small orifice is sometimes seen, which is of artificial and 
 pathological formation. The larger lower portion of the drum membrane is 
 stretched tightly, and is called the tense portion or pars tensa (Figs. 760 and 761). 
 
 ' Prof. Cunningham's Text-book of Anatomy. 
 
THE MIDDLE EAR, DRUM OB TYMPANUM 
 
 1157 
 
 The handle of the malleus is firmly attached to the inner aspect of the mem- 
 brana tympani as far as its centre (Fig. 761). It draws the central part of the 
 membrane inward and makes its outer aspect concave. The most depressed part 
 of the concavity is called the umbo or navel {umbo membranae tymj)anae)(Fig. 760). 
 The walls of the umbo are convex outward. 
 
 On the outer surface of the drum membrane a light stripe (stria malleolaris) is 
 seen. It runs from in front and above downward and backward, and is produced 
 by the handle of the malleus, showing through the membrane (Fig. 760). 
 
 Structure. — This membrane is composed of three layers: an external (cw^icw/ar), 
 a middle {fibrous), and an internal (mucous). The cuticular lining (stratum cuia- 
 neum) is derived from the integument lining the meatus. The fibrous or 
 middle layer (membrana propria) consists of two strata: an external, of radiating 
 fibres (stratum radiatum), which diverge from the handle of the malleus, and an 
 
 JUNCTION BETWEEN MAS- 
 ^===_ TOID ANTRUM AND 
 
 ePITYMPANIC RECESS 
 TEGMEN 
 TYMPANI 
 
 EPITYMPANIC 
 RECESS 
 
 PROMINENCE OF EXTERNAL 
 SEMICIRCULAR CANAL 
 
 PROMINENCE OF AQUEDUCT 
 OF FALLOPIUS 
 
 TENDON OF 
 STAP.EDIUS MUSCLE 
 PLICA 
 STAPEDIUS 
 
 PROCESSUS 
 
 'm'iff^m'g^mm^ / cochleariformis 
 
 W'^^Wf^^^L / / ^^ TENSOR TYMPANI 
 
 ^mmmoi. l / ^ muscle (cut through) 
 
 WALL OF 
 LABYRINTH 
 
 posterior 
 sinus 
 
 pyramidal 
 eminence 
 
 tympanic 
 
 SINUS 
 
 Fig. 762. 
 
 "it"iiiii'Mr"'^i""~~iii '"" ' / I \ ==^ 
 
 FOSSULA OF JUGULAR TYMPANIC 
 
 FENESTRA ROTUNDA WALL PLEXUS 
 
 -The medial wall and part of the posterior and anterior walls of the right tympanic cavity, lateral 
 view. (Spalteholz.) 
 
 internal, of circular fibres (stratum circulare), which are plentiful around the cir- 
 cumference, but sparse and scattered near the centre of the membrane. Branched 
 or dendritic fibres, as pointed out by Griiber, are also present, especially in the 
 posterior half of the membrane. Both muscular layers are connected to the 
 annulus fibrocartilagineus, and both are absent in the pars flaccida. The inner 
 or epithelial layer is mucous membrane (stratum mucosum), which is a portion 
 of the mucous membrane of the drum cavity. 
 
 The Arteries are derived from the deep auricular branch of the internal maxil- 
 lary, which ramifies beneath the cuticular layer and from the stylo-mastoid branch 
 of the posterior auricular and tympanic branch of the internal maxillary, which 
 are distributed on the mucous surface. The arteries of the cutaneous set anas- 
 tomose with the arteries of the mucous set by minute branches which penetrate 
 the drum membrane near its margin. The superficial veins open into the external 
 jugular; those on the mucous surface drain themselves partly into the lateral 
 sinus and veins of the dura mater and partly into a plexus on the Eustachian tube. 
 
1158 
 
 THE OBGANS OF SPECIAL SENSE 
 
 The outer surface of the drum membrane receives its nervous supply from the 
 auriculo-temporal branch of the inferior maxillary and the auricular branch of 
 the vagus. The inner surface is supplied by the tympanic branch of the glosso- 
 pharyngeal. 
 
 There are two sets of lymphatics, the cutaneous and mucous, which freely 
 communicate. The spaces between the dendritic fibres of Griiber are lymph- 
 spaces (Kessel). 
 
 The Ossicles of the Tympanum (Ossicula Auditus) (Fig. 763). 
 
 The tympanum contains in its upper part a chain of movable bones, three in 
 number, the malleus, incus, and stapes. The first is attached to the membrana 
 
 tympani, the last to the fenestra ovalis. The 
 incus is placed between the two, and is con- 
 nected to both by delicate articulations. 
 
 The Malleus or Hammer (Fig. 764).— The 
 malleus or hammer, so named from its fancied 
 resemblance to a hammer, is placed farthest in 
 front and outward. It consists of a head, neck, 
 and three processes — the handle or manubrium, 
 the processus gracilis, and the processus brevis. 
 The Head (capitulum mallei). — The head is 
 the large upper extremity of the bone, and is 
 situated in the epitympanic recess (Fig. 761). 
 It is oval in shape, and articulates posteriorly 
 with the incus, being free in the rest of its ex- 
 tent. The facet for articulation with the incus 
 is covered with cartilage, is constricted near 
 the middle, and is divided by a ridge into an 
 upper, larger, and a lower, lesser part, which 
 form nearly a right angle with each other. Op- 
 posite the constriction the lower margin of the 
 facet projects in the form of a process, the 
 cog-tooth or spur of the malleus. On the back 
 of the head below the spur is a crest (crista 
 mallei), to which the posterior ligament of the malleus is attached. 
 
 The Neck (collum mallei). — The neck is the narrow contracted part just beneath 
 the head; and below this is a prominence, to which the various processes are 
 attached. The outer surface of the neck faces the membrana flaccida. The 
 chorda tympani nerve crosses the inner surface' (Fig. 761). 
 
 The Handle or Manubrium (manubrium mallei).— The manubrium is a vertical 
 process of bone, which is connected by its outer margin with the fibrous layer of 
 the membrana tympani, its entire length being fastened to the fibrous layer of 
 the drum membrane by its own periosteum and by a layer of cartilage (Griiber) 
 (Figs. 761 and 763). It is directed downward, inward, and backward; it decreases 
 in size toward its extremity, where it is curved slightly forward, and is flattened 
 from within outward, The handle forms a variable angle with the head of the 
 hammer. It averages about 130 degrees, but is always greater in the right ear 
 than in the left. It forms an angle with the horizontal, averaging on the right 
 side 50 degrees and on the left side 45 degrees (Spalteholz). Internally the 
 handle is covered by the mucous membrane of the tympanum. On the inner 
 side, near its upper end, is a slight projection, into which the tendon of the 
 Tensor tympani is inserted (Fig. 761). 
 
 The Processus Gracilis or Long Process (processus anterior [Folii]). — The pro- 
 cessus gracilis is a long and very delicate process, which passes from the front of 
 
 Fig. 763. — Chain of ossicles and their liga^ 
 ments, seen from the front in a vertical, tranS' 
 verse section of the tympanum. (Testut.) 
 
THE OSSICLES OF THE TYMPANUM 
 
 1159 
 
 the neck forward and outward to the Glaserian fissure, to which it is connected 
 by hgamentous fibres. In the foetus this is the longest process of the malleus, and 
 is in direct continuity with the cartilage of Meckel. 
 
 The Processus Brevis {processus lateralis). — The processus brevis is a slight 
 conical projection, which springs from the root of the manubrium ; it is directed 
 outward, and is attached to the upper part of the tympanic membrane by cartilage 
 and to the margins of the notch of Rivinus by the two malleolar folds. 
 
 
 j^HfM AURICULAR 
 
 
 ■PH_ SURFACE 
 
 ^^^^3m 
 
 ^Kfl FOR BODY 
 
 ^^^^ 
 
 ^^Jg OF INCUS 
 
 TOOTH^^ 
 
 :Migea 
 
 OR COG \^k 
 
 WgL INSERTION OF 
 
 
 ^BV EXTERNAL 
 
 NECK^H 
 
 ^^f LIGAMENT 
 
 
 HL OF MALLEUS 
 
 INSERTION 1^ 
 
 ^^^^^^ 
 
 OF TENSOR L -g 
 
 ^^^^^B 
 
 TYMPANI J^ ^ 
 
 ^^^PP'^ 
 
 MUSCLEjf^^ 
 
 l^^^l 
 
 
 ^SHOHT 
 
 
 PROCESS 
 
 ^^MANUBRIUM 
 
 Fig. 764. — The right malleus: a, viewed from in front; b, viewed from behind. (Spaltehols.) 
 
 The Incus or Anvil (Fig. 765). — The incus or anvil has received its name from 
 its supposed resemblance to an anvil, but it is more like a bicuspid tooth with two 
 roots, which differ in length, and are widely separated from each other. It con- 
 sists of a body and two processes. The body and the short process are placed in 
 the epitympanic recess (Fig. 763) . 
 
 The Body {corpus incudis). — The body is somewhat quadrilateral, but compressed 
 laterally. On its anterior surface is a deeply concavo-convex facet, which articu- 
 lates with the head of the malleus, and the lower part is hollowed for the spur of the 
 malleus. In the fresh state the articular surface is covered with cartilage and the 
 joint is lined with synovial membrane. 
 
 ARTICULAR SURFACE 
 FOR HEAD OF MALLEUS 
 
 ARTICULAR 
 SURFACE FOR 
 HEAD OF 
 MALLEUS 
 
 LENTICULAR 
 PROCESS 
 
 Fig. 765. — The right incus: a, lateral view; h, medial and front view. (Spalteholz.) 
 
 Processes. — The two processes diverge from one another at an angle of from 
 90 to 100 degrees. 
 
 The Short Process {cms breve), somewhat conical in shape, projects neai-ly 
 horizontally backward, and articulates with a depression, the incus fossa {fossa 
 incudis), in the lower and back part of the epitympanic recess. 
 
 The Long Process {crus longum), longer and more slender than the preceding, 
 descends nearly vertically behind and parallel to the handle of the malleus, and, 
 
1160 THE ORGANS OF SPECIAL SENSE 
 
 bending inward, terminates in a rounded globular projection, the os orbiculare or 
 lenticular process {processus lenticularis) , which is tipped with cartilage, and articu- 
 lates with the head of the stapes. In the foetus the os orbiculare exists as a separate 
 bone. 
 
 The Stapes or Stirrup (Fig. 766). — The stapes or stirrup, so called from its 
 close resemblance to a stirrup, consists of a head, neck, two crura, and a base. 
 
 The Head (capitulum stapedis). — The head presents a depression, tipped with 
 cartilage, which articulates with the os orbiculare. 
 
 The Neck. — ^The neck, the constricted part of the bone succeeding the head, 
 receives the insertion of the Stapedius muscle. 
 
 The Crura. — ^The two crura {crus anterius and crus posterius) diverge from the 
 neck and are connected at their extremities by a flattened, oval-shaped plate, the 
 foot-plate or base (basis stapedis), which forms the foot-plate of the stirrup and 
 is fixed to the margin of the fenestra ovalis by ligamentous fibres. The foot- 
 plate almost fills the oval window (Fig. 757. Of the two crura, the anterior is 
 shorter and less curved than the posterior. In a recent specimen a membrane will 
 
 be observed filling the space between the 
 crura and the foot-plate. This mem- 
 brane is connective tissue and is called 
 
 GROOVE FOR ^Yyq membrana obturatoria stapedis. The 
 
 OBTURATOR 
 
 OP s^^'yy^^ ^^^^^© stirrup lies practically horizontal. 
 *'*^"Rus^f ^J POSTERIOR I " Articulations of the Ossicles of the Tym- 
 
 DA«r or panum (articulationes ossiculorum audi- 
 tus) (Fig. 763). — These small bones are 
 BASE OF STAPES couuccted with each other and with the 
 
 Fig. 766. — The right stirrup: o, viewed from above; 11 i> i ^ 1 !• 1 
 
 b, medial vein. (Spaitehoiz.) walls oi the tympanum by ligaments, and 
 
 are moved by small muscles. There is an 
 articulation between the head of the hammer and the body of the anvil ; one 
 between the os orbiculare of the anvil and the head of the stirrup; and there is a 
 syndesmosis between the margins of the oval window and the base of the stirrup. 
 The bones are fastened in the tympanum, the handle of the hammer being 
 fastened in the drum membrane and the base of the stirrup to the oval window. 
 The articular surfaces of the malleus and incus and the orbicular process of the 
 incus and head of the stapes are covered with cartilage, connected together by 
 delicate capsular ligaments and lined by synovial membrane. 
 
 Ligaments Connecting the Ossicula with the Walls of the Tympanum (ligamenta 
 ossiculorum auditus). — The malleus is fastened to the wall of the tympanum by 
 three ligaments: the anterior, superior, and external ligaments. 
 
 The Anterior Ligament of the Malleus (ligamentum mallei anterius) consists of 
 two parts, the band of Meckel and the anterior ligament of Helmholtz. 
 
 The band of Meckel is attached to the base of the processus gracilis and passes 
 through the Glaserian fissure to reach the spine of the sphenoid. It was formerly 
 described by Sommering as a muscle, and it was called the laxator tympani 
 muscle. It is now, however, believed by most observers to consist of ligamentous 
 fibres only. 
 
 The anterior ligament of Helmholtz extends from the anterior margin of the 
 notch of Rivinus to the anterior portion of the malleus, just above the processus 
 gracilis. 
 
 The Superior Ligament of the Malleus (ligamentum mallei superius) is a delicate 
 round bundle of fibres which descends perpendicularly from the roof of the epi- 
 tympanic recess to the head of the malleus. It is sometimes called the suspensory 
 ligament. 
 
 The External Ligament of the Malleus (ligamentum mallei laterale) is a triangular 
 plane of fibres passing from the posterior part of the notch in the tympanic ring 
 
THE OSSICLES OF THE TYMPANUM ngi 
 
 (incisura Rivini) to the crest of the malleus. The posterior portion of the external 
 ligament is sometimes called the posterior ligament of Helmholtz (ligamentum 
 mallei posterius [Hehnholtzi]). The malleus rotates around an axis composed of 
 the external and anterior ligaments, hence these two ligaments constitute what 
 Helmholtz called the axis ligament of the malleus. 
 
 The incus is fastened to the wall of the tympanum by two ligaments, the poste- 
 rior and the superior. 
 
 The Posterior Ligament of the Incus (ligamentum incudis posterius) is a short, 
 thick, ligamentous band which connects the extremity of the short process of the 
 incus to the posterior and lower part of the epitympanic recess, near the margin 
 of the opening of the mastoid cells. 
 
 A Superior Ligament of the Incus (ligamentum incudis superius) has been 
 described by Arnold, but it is little more than a fold of mucous membrane. 
 
 The inner surface and the circumference of the base of the stapes are covered with 
 hyaline cartilage, and the annular ligament of the stapes (ligamentum annulare haseos 
 stapedis) connects the circumference of the base to the margin of the fenestra ovalis. 
 
 The Muscles of the Tympanum (m. ossiculorum auditus). — The muscles of the 
 tympanum are two: 
 
 Tensor tympani. Stapedius. 
 
 The Tensor Tympani (m. tensor tympani) (Fig. 762) , the larger, is contained in 
 the bony canal above the osseous portion of the Eustachian tube, from which it 
 is separated by the processus cochleariformis. It arises from the under surface of 
 the petrous bone, from the cartilaginous portion of the Eustachian tube, and from 
 the osseous canal in which it is contained. Passing backward through the canal, 
 it terminates in a slender tendon which enters the tympanum and makes a sharp 
 bend outward around the extremity of the processus cochleariformis, and is 
 inserted into the handle of the malleus near its root. Its nerve-supply is from 
 the motor root of the fifth cranial nerve by way of the otic ganglion. 
 
 The Stapedius {m. stapedius) (Fig. 762) arises from the side of a conical cavity 
 hollowed out of the interior of the pyramid; its tendon emerges from the orifice 
 at the apex of the pyramid, and, passing forward, is inserted into the neck of the 
 stapes. Its surface is aponeurotic, its interior fleshy, and its tendon occasionally 
 contains a slender bony spine, which is constant in some mammalia. It is 
 supplied by the tympanic branch of the facial nerve. 
 
 Actions. — The Tensor tympani draws the handle of the malleus inward and 
 thus heightens the tension of the drum membrane. It also causes slight rotation 
 of the bone around its long axis. When the Stapedius contracts it draws the 
 head of the stirrup backward, and in consequence the anterior end of the foot- 
 plate passes outward toward the tympanum, and the posterior end inward toward 
 the vestibule, and the annular ligament is made tense. 
 
 Movements of the Ossicles of the Tympanum. — The chain of bones is a lever-like 
 arrangement, by means of which the vibrations of the membrana tympani are 
 transferred to the membrane covering the oval window, and from this to the peri- 
 lymph in the labyrinth. When the drum membrane moves inward, the handle 
 of the malleus moves with it. The movement of the malleus moves the incus, and 
 the movement of the incus drives the foot of the stapes toward the labyrinth. 
 When the handle of the malleus moves inward, the spur on the head becomes 
 locked with the body of the incus. During outward movement it is unlocked. 
 The ordinary outward movement of the drum membrane causes the above- 
 described movements to be reversed. When there is overforcible outward move- 
 ment the incus does not go outward quite as far as the malleus, but slides at the 
 joint between the malleus and incus. This reluctance of the incus saves the foot 
 of the stapes from being pulled away from the oval window. 
 
IIQ2 THE 0BGAN8 OF SPECIAL SENSE 
 
 The Mucous Membrane of the Tympanum {tunica mucosa tympanica). — The 
 mucous membrane of the tympanum is continuous with the mucous membrane 
 of the naso-pharynx through the Eustachian tube, and is firmly united to the 
 periosteum. It invests the ossicula, and the muscles and nerves contained in the 
 tympanic cavity; forms the internal layer of the membrana tympani, and the outer 
 layer of the membrana tympani secundaria, and is reflected into the mastoid 
 antrum and air-cells, which it lines throughout. It forms several vascular folds 
 (plicae), which extend from the walls of the tympanum to the ossicles. In these 
 folds the ossicles are enveloped. 
 
 The anterior malleolar fold (plica malleolaris anterior) comes off from the mem- 
 brana tympani between the anterior edge of the notch of Rivinis and the handle 
 of the malleus, envelops the processus gracilis of the malleus, the anterior liga- 
 ment of the malleus, and the anterior portion of the chorda tympani nerve, and 
 terminates in a free concave edge (Spalteholz). The posterior malleolar fold (plica 
 malleolaris posterior) is the larger of the two. It comes off from the margin of the 
 notch of Rivinis, envelops the external ligament of the malleus, the posterior part 
 of the chorda tympani nerve, is attached to the handle of the malleus, and ends 
 in a free concave margin (Spalteholz). The fold of the incus (plica incudis) takes 
 origin from the roof of the epitympanic recess and passes to the body and short 
 process of the incus; and a similar fold passes from the head of the malleus to the 
 anterior wall of the epitympanic recess. The entire stapes, with its obturator 
 membrane, is enwrapped by the fold of the stapes (plica stapedis). This fold also 
 ensheaths the tendon of the stapedius muscle and often reaches to the posterior 
 wall of the cavity of the tympanum. The mucous membrane over the round 
 window forms the membrana tympani secundaria. These folds separate off pouch- 
 like cavities, and give the interior of the tympanum a somewhat honey-comb 
 appearance. One of these pouches is well marked — viz., the pouch of Prussak, 
 which lies between the neck of the malleus and the membrana flaccida. 
 
 The inferior external pouch of the tympanum or the pouch of Prussak (recessus 
 membranae tympani superior) is between the flaccid portion of the membrana 
 tympani, the external ligament of the malleus, and the neck of the mal- 
 leus. The anterior and posterior malleolar folds with the tympanic membrane 
 form two pouches. These are the anterior and posterior pouches or recesses of 
 Troltsch (recessus membranae tympani, anterior and posterior). The anterior pouch 
 is blind above and has a slit-like opening below. The posterior pouch is con- 
 tinued into the blind superior pouch of the drum membrane. In the tympanum 
 this membrane is pale, thin, slightly vascular, and covered for the most part with 
 columnar ciliated epithelium, but that covering the pyramid, ossicula, and mem- 
 brana tympani possesses a flattened, non-ciliated epithelium. In the antrum and 
 mastoid cells its epithelium is also non-ciliated. In the osseous portion of the 
 Eustachian tube the membrane is thin ; but in the cartilaginous portion it is very 
 thick, highly vascular, covered with ciliated epithelium, and provided with numer- 
 ous mucous glands. 
 
 The Arteries of the Tympanum. — The arteries supplying the tympanum are six 
 in number. Two of them are larger than the rest — viz., the tympanic branch of 
 the internal maxillary, which enters by way of the Glaserian fissure and supplies 
 the membrana tympani ; and the stylo-mastoid branch of the posterior auricular, 
 which passes through the stylo-mastoid foramen and the aqueduct of Fallopius, 
 and supplies the inner wall and floor of the tympanum, the mastoid cells, and 
 antrum and the Stapedius muscle. This vessel anastomoses around the drum 
 membrane with the tympanic. The middle meningeal sends a small branch to 
 the Tensor tympani muscle near its origin. The petrosal branch of the middle 
 meningeal enters the tympanum by way of the hiatus Fallopii. Minute branches 
 from the posterior branch of the middle meningeal pass through the petro- 
 
THE INTERNAL EAR OR LABYRINTH 1153 
 
 squamous fissure and are distributed to the antrum and epitympanie recess 
 (Cunningham). Two tympanic branches come off from the internal carotid 
 artery in its course through the carotid canal. A branch from the ascending 
 pharyngeal and another from the Vidian, accompany the Eustachian tube. The 
 two tympanic branches from the internal carotid are given off in the carotid canal 
 and perforate the thin anterior wall of the tympanum. 
 
 The Veins of the Tympanum. — The veins of the tympanum terminate in the 
 pterygoid plexus, the middle meningeal vein, and the superior petrosal sinus. 
 
 The Nerves of the Tympanum. — The nerves of the tympanum constitute the 
 tympanic plexus {'plexus tympanicus [Jacobsoni]) , which ramifies upon the surface 
 of the promontory (Fig. 7G2). The plexus is formed by (1) the tympanic branch of 
 the glosso-pharyngeal ; (2) the small deep petrosal nerve; (3) the small super- 
 ficial petrosal nerve; and (4) a branch which joins the great superficial petrosal. 
 
 The Tympanic Branch of the Glosso-pharyngeal or Jacobson's Nerve (n. tympan- 
 icus) enters the tympanum by an aperture in its floor close to the inner wall and 
 divides into branches, which ramify on the promontory and enter into the forma- 
 tion of the plexus. The small deep petrosal nerve {n. petrosus profundus), from 
 the carotid plexus of the sympathetic, passes through the wall of the carotid canal, 
 and joins the branches of Jacobson's nerve. The branch to the great superficial 
 petrosal passes through an opening on the inner wall of the tympanum in front 
 of the fenestra ovalis. The small superficial petrosal nerve (w. petrosus super- 
 ficialis minor), derived from the otic ganglion, passes through a foramen in the 
 middle fossa of the base of the skull (sometimes through the foramen ovale), 
 passes backward and enters the petrous bone through a small aperture, situ- 
 ated external to the hiatus Fallopii on the anterior surface of this bone; it then 
 courses downward through the bone, and, passing by the gangliform enlargement 
 of the facial nerve, receives a connecting filament from it (Fig. 676) and enters the 
 tympanic cavity, where it communicates with Jacobson's nerve, and assists in 
 forming the tympanic plexus. 
 
 The branches of distribution of the tympanic plexus are distributed to the 
 mucous membrane of the tympanum ; one special branch passing to the fenestra 
 ovalis, another to the fenestra rotunda, and a third to the Eustachian tube. The 
 small superficial petrosal may be looked upon as a branch from the plexus to the 
 otic ganglion. 
 
 In addition to the tympanic plexus there are the nerves supplying the muscles. 
 The Tensor tympani is supplied by a branch from the third division of the fifth 
 through the otic ganglion, and the Stapedius by the tympanic branch of the facial. 
 
 The chorda tympani (Figs. 758 and 761) crosses the tympanic cavity. It is given 
 off from the facial as it passes vertically downward at the back of the tympanum, 
 about a quarter of an inch before its exit from the stylo-mastoid foramen. It passes 
 from below upward and forward in a distinct canal, and enters the cavity of the 
 tympanum through an aperture, iter chordae posterius, already described (p. 1151), 
 and becomes invested with mucous membrane. It passes forward, through the 
 cavity of the tympanum, crossing internal to the membrana tympani and over 
 the handle of the malleus to the anterior inferior angle of the tympanum, and 
 emerges from that cavity through the iter chordae anterius or canal of Huguier 
 (p. 1152) . It is invested by the fold of mucous membrane already mentioned, and 
 therefore lies between the mucous and fibrous layers of the membrana tympani. 
 
 THE INTERNAL EAR OR LABYRINTH (AURIS INTERNA). 
 
 The internal ear is the essential part of the organ of hearing, receiving the 
 ultimate distribution of the auditory nerve. It is called the labyrinth, from the 
 
1164 
 
 THE ORGANS OF SPECIAL SENSE 
 
 complexity of its shape, and consists of two parts: the osseous labyrinth, a series 
 of cavities channelled out of the substance of the petrous bone, and the membranous 
 labyrinth, the latter being contained within the former. 
 
 The Osseous Labyrinth (Labyrinthus Osseus) (Fig. 767). 
 
 The osseous labyrinth consists of three parts: the vestibule, semicircular canals, 
 and cochlea. These are cavities hollowed out of the substance of the bone, and 
 lined by periosteum. A clear fluid is contained in the space between the osseous 
 labyrinth and the membranous labyrinth. The space is called the perilymph 
 space, and the fluid is called perilsntnph or liquor Cotunnii. 
 
 The Vestibule (vestibulum) (Figs. 763 and 767). — The vestibule is the common 
 central cavity of communication between the parts of the internal ear. It is situated 
 on the inner side of the tympanum, behind the cochlea, and in front of the semi- 
 circular canals. It is somewhat ovoidal in shape from before backward, flattened 
 from within outward, and measures about one-fifth of an inch from before back- 
 
 Opening of aqueductus vestibuli, 
 Bi^istle passed through foramen rotundum 
 
 Opening of aqueductus cochlex. 
 Fig. 767. — The osseous labyrinth laid open (enlarged). 
 
 ward, as well as from above downward, and about one-eighth of an inch from with- 
 out inward. On its outer or tympanic wall is the fenestra ovalis (fenestra vestibuli), 
 closed, in the recent state, by the base of the stapes, and its annular ligament. 
 On its inner wall, at the forepart, is a small circular depression, fovea hemi- 
 sphaerica or spherical recess (recessus sphaericus), in which the saccule is placed. 
 This recess is perforated, at its anterior and inferior part, by about a dozen minute 
 holes (macula cribrosa media), for the passage of filaments of the auditory nerve 
 to the saccule. Above and behind this depression is an oblique ridge, the crista 
 vestibuli. The anterior extremity of the crista vestibuli is the shape of a triangle, 
 and is called the P3n:amid (pyramis vestibuli). This ridge bifurcates posteriorly to 
 enclose a small depression, the recessus cochlearis of Reichert, which is perforated 
 by eight small holes for the passage of filaments of the auditory nerve which 
 supply the posterior end of the ductus cochlearis. An oval depression is placed 
 in the roof and inner wall of the vestibule above and behind the crista vestibuli. 
 It is called the fovea hemielliptica, elliptical recess or spherical recess (recessus 
 ellipticus), and receives the utricle. The pyramid and the adjacent elliptical 
 recess are perforated by numerous minute foramina (macula cribrosa superior), 
 
THE OSSEOUS LABYRINTH 1165 
 
 The openings in the pyramid transmit filaments from the vestibular nerve to the 
 utricle; the openings in the elliptical recess transmit filaments from the vestibular 
 nerve to the ampullae of the superior and external semicircular canals. Below and 
 behind the elliptical recess is a groove which deepens into a canal and is called 
 the aquaeductus vestibuli. This canal passes to the posterior surface of the petrous 
 portion of the temporal bone and opens as a mere crack between the internal 
 auditory meatus and the groove for the lateral sinus. It transmits a small vein, 
 and contains a tubular prolongation of the lining membrane of the vestibule, the 
 ductus endolymphaticus, which ends in a cul-de-sac between the layers of the dura 
 mater within the cranial cavity. Behind, the semicircular canals open into the 
 vestibule by five orifices. In front is an elliptical opening, which communicates 
 with the scala vestibuli of the cochlea by an orifice, apertura scalae vestibuli cochleae. 
 This opening is bounded below by a thin plate of bone (lamina spiralis ossea), 
 which takes origin from the vestibular floor external to the spherical recess and 
 in the cochlea forms the bony portion of the partition between the scala tympani 
 and the scala vestibuli. In the anterior portion of the vestibular floor is a fissure 
 (fissiira vestibuli), which passes into the bony part of the canal of the cochlea. 
 The external boundary of this fissure is a small, thin plate of bone (lamina spiralis 
 secundaria). 
 
 The Semicircular Canals (canales semicirculares ossei) (Fig. 767) .—The serai- 
 circular canals are three bony canals situated above and behind the vestibule. They 
 are of unequal length, compressed from side to side, and each describes the greater 
 part of a circle. They measure about one-twentieth of an inch in diameter, and 
 each presents a dilatation at one end, called the ampulla ossea, which measures 
 more than twice the diameter of the tube. These canals open into the vestibule 
 by five orifices, one of the apertures being common to two of the canals. 
 
 The Superior Semicircular Canal (canalis semicircularis superior). — The superior 
 semicircular canal is vertical in direction, and is placed transversely to the long 
 axis of the petrous portion of the temporal bone, on the anterior surface of which 
 its arch forms a round projection. It describes about two-thirds of a circle. Its 
 outer extremity, which is ampullated, communicates by a distinct orifice with the 
 upper part of the vestibule; the opposite end of the canal, which is not dilated, 
 joins with the corresponding part of the posterior canal to form the cnis commune, 
 which opens into the upper and inner part of the vestibule. 
 
 The Posterior Semicircular Canal (canalis semicircularis posterior). — ^The posterior 
 semicircular canal, also vertical in direction, is directed backward, nearly parallel 
 to the posterior surface of the petrous bone ; it is the longest of the three ; its ampul- 
 lated end commences at the lower and back part of the vestibule, its opposite end 
 joining to form the common canal already mentioned. In the wall of the ampulla 
 of the posterior canal are a number of small openings (macula cribrosa inferior) 
 for the entrance of nerves to the ampulla. 
 
 The External or Horizontal Canal (canalis semicircularis lateralis). — The external 
 or horizontal canal is the shortest of the three, its arch being directed outward and 
 backward; thus each semicircular canal stands at right angles to the other two. 
 Its ampullated end corresponds to the upper and outer angle of the vestibule, just 
 above the fenestra ovalis, where it opens close to the ampuUary end of the superior 
 canal ; its opposite end opens by a distinct orifice at the upper and back part of the 
 vestibule. 
 
 The Cochlea (Figs. 767,768,769, and 770). — The cochlea bears some resemblance 
 to acommon snail-shell ; it forms the anterior partof the labyrinth, is conical in form, 
 and placed almost horizontally in front of the vestibule; its apex is directed forward 
 and outward, with a slight inclination downward, toward the upper and front part 
 of the inner wall of the tympanum ; its base corresponds with the anterior depression 
 at the bottom of the internal auditory meatus, and is perforated by numerous 
 
1166 
 
 THE ORGANS OF SPECIAL SENSE 
 
 apertures for the passage of the cochlear divisions of the auditory nerve. It meas- 
 ures nearly a quarter of an inch (5 mm.) from base to apex, and its breadth across 
 
 Fig. 768. — Osseous cochlea in vertical section. The broken, white lines indicate the position of the basilar 
 membrane of the canal of the cochlea. Semidiagrammatic. (Testut.) 
 
 the base is somewhat greater (about 9 mm.). It consists of a conical-shaped 
 central axis, the modiolus or columella; of a canal, the bony canal of the cochlea, the 
 inner w^all of which is formed by the central axis, wound spirally around it for two 
 
 BASIS 
 MODIOLI 
 
 CANALIS CANALIS LON- 
 SPIRALIS GITUDINALIS 
 MODIOLI MODIOLI 
 
 COMPACT BONY 
 SUBSTANCE OF 
 
 CAPSULE OF SULCUS FOR LARGE SUPCR- 
 lAL PETROSAL NERVE 
 
 ALL SUPER- 
 L NERVE 
 
 TEGMCN 
 TYMPANI 
 
 SEMICANAL 
 
 FOR TENSOR 
 
 TYMPANI 
 
 MUSCLE 
 
 GLASSERIAN 
 
 FISSURE 
 
 EMICANAL OF 
 USTACHIAN 
 TUBE 
 
 LAMINA 
 
 SPIRALIS 
 
 OSSEA 
 
 LAMINA SPIRALIS 
 SECUNDARIA 
 
 Fig. 769. — Vertical section through the right cochlea, medial portion, viewed from the lateral side. (Spalteholz.) 
 
 turns and three-quarters, from the base to the apex, and of a delicate lamina, the 
 lamina spiralis ossea, which projects from the modiolus, and, following the windings 
 
THE OSSEOUS LABYRINTH 1167 
 
 of the canal, partially subdivides into two. In the recent state certain mem- 
 branous layers are attached to the free border of this lamina, which project into 
 the canal and completely separate it into two passages, which, however, com- 
 municate with each other at the apex of the modiolus by a small opening, named 
 the helicotrema. 
 
 The Modiolus (Figs. 769 and 770). — The modiolus or columella is the central axis 
 or pillar of the cochlea. It is conical in form, and extends from the base to the apex 
 of the cochlea. Its base (basis modioli) is broad, and appears at the bottom of the 
 internal auditory meatus, where it corresponds with the area cochleae. It is per- 
 forated by numerous orifices, which transmit filaments of the cochlear division 
 of the auditory nerve, the nerves for the first turn and a half being transmitted 
 through the foramina of the tractus spiralis foraminosus ; the fibres for the apical 
 turn passing up through the foramen centrale. The foramina of the tractus 
 spiralis foraminosus pass up through the modiolus and successively bend out- 
 ward to reach the attached margin of the lamina spiralis ossea. Here they become 
 enlarged, and by their apposition form a spiral canal (canalis spiralis modioli), 
 which follows the course of the attached margin of the lamina spiralis ossea and 
 lodges the ganglion of Corti (ganglion spirale cochleae). The foramen centrale is 
 continued as a canal up the middle of the modiolus to its apex, and from this canal 
 numerous minute foramina pass outward to the unattached edge of the lamina 
 spiralis. In the foramina are vessels and nerves. The axis diminishes rapidly 
 in size in the second and succeeding coil. 
 
 Fig. 770. — The cochlea laid open (enlarged). 
 
 The Bony Canal or the Spiral Canal of the Cochlea {canalis spiralis cochleae) (Fig. 
 770). — The bony canal of the cochlea takes two turns and three-quarters round the 
 modiolus. The first turn of the canal is called the basal coil, the second is called the 
 central coil, the third turn is called the apical coil. The promontory on the inner wall 
 of the tympanic cavity is caused by the basal coil. The bony canal of the cochlea is 
 a little over an inch in length (about 30 mm.), and diminishes gradually in size from 
 the base to the summit, where it terminates in a cul-de-sac, the cupola (cwpw/a), which 
 forms the apex of the cochlea. The commencement of this canal is about the 
 tenth of an inch in diameter; it diverges from the modiolus toward the tympanum 
 and vestibule, and presents three openings. One, the fenestra rotunda, commu- 
 nicates with the tympanum ; in the recent state this aperture is closed by a mem- 
 brane, the membrana t3anpani secundaria. Another aperture, of an elliptical form, 
 enters the vestibule. The third is the aperture of the aquaeductus cochleae, leading 
 to a minute funnel-shaped canal, which opens on the basilar surface of the petrous 
 bone internal to the jugular fossa, and transmits a small vein, and also forms 
 a communication between the subarachnoidean space of the skull and the peri- 
 lymph contained in the scala tympani. 
 
 The Lamina Spiralis Ossea. — The lamina spiralis ossea is a bony shelf or ledge 
 which projects outward from the modiolus into the interior of the spiral canal, 
 
1168 
 
 THE ORGANS OF SPECIAL SENSE 
 
 and, like the canal, takes two and three-quarter turns around the modiolus. It 
 reaches about half-way toward the outer wall of the spiral tube, and partially 
 divides its cavity into two passages or scalae, of which the upper is named the 
 scala vestibuli, while the lower is termed the scala tympani. Near the summit of 
 the cochlea the lamina terminates in a hook-shaped process, the hamulus (hamulus 
 laminae spiralis), which assists in forming the boundary of a small opening, the 
 helicotrema, by which the two scalae communicate with each other. From the 
 canalis spiralis modioli numerous foramina pass outward through the osseous 
 spiral lamina as far as its outer or free edge. In the lower part of the first turn 
 a second bony lamina (lamina spiralis secundaria) projects inward from the 
 outer wall of the bony tube; it does not, however, reach the primary osseous spiral 
 lamina, so that if viewed from the vestibule a narrow fissure, the fissura vestibuli, 
 is seen between them. 
 
 The membrana basilaris (Fig. 768) is stretched from the unattached edge of 
 the lamina spiralis ossea to the outer wall of the cochlea. The lamina spiralis 
 
 NERVE OF AMPULLA 
 OF SUPERIOR CANAL 
 
 AMPULLA OF SUPERIOR 
 MEMBRANOUS CANAL 
 
 SUPERIOR 
 
 TERMINAL 
 
 BRANCH OF 
 
 VESTIBULAR 
 
 NERVE 
 
 DUCTUS 
 COCHLEARIS 
 
 COCHLEAR 
 NERVE 
 
 ACOUSTIC 
 NERVE 
 
 VESTIBULAR 
 NERVE 
 
 VESTIBULAR 
 GANGLION 
 
 NERVE OF NERVE OF AMPULLA SACCULE AM PU LLA OF POSTE RIOR 
 
 SACCULE OF POSTERIOR CANAL MEMBRANOUS CANAL 
 
 Fig. 771. — The right membranous labyrinth of an adult, isolated, medial and posterior view. 
 
 DUCT OF 
 SUPERIOR 
 SEMICIRCULAR 
 CANAL 
 
 AMPULLA OF 
 EXTERNAL 
 MEMBRANOUS 
 CANAL 
 
 DUCT OF 
 EXTERNAL 
 SEMICIRCULAR 
 CANAL 
 
 CPUS 
 
 COMMUNE 
 
 DUCT OF 
 
 POSTERIOR 
 
 SEMICIRCULAR 
 
 CANAL 
 
 DUCTUS ENDO. 
 LYMPHATICUS 
 
 (Spalteholz.) 
 
 makes an incomplete septiun between the scala tympani and scala vestibuli; the 
 membrana basilaris completes the septum. Even with the perfected septum the 
 two scalae communicate at the apex of the cochlea by means of the helicotrema. 
 The Fundus of the Internal Auditory Meatus {fundus meatus acustici irdemi). — 
 This structure is the inner wall of the vestibule and the base of the modiolus. A 
 transverse ridge {crista transversa) maps it off into two parts, the fossula superior 
 and the fossula inferior. The facial area {area n. facialis) is in the anterior portion 
 of the fossula superior. The opening seen here is the beginning of the aqueduct 
 of Fallopius (canalis facialis) for the transmission of the facial nerve. The superior 
 area of the vestibule (area vestibularis superior) is the posterior portion of the fossula 
 superior. Here the nerves perforate which supply the utricle and the ampullae of 
 the superior and external semicircular canals (Cunningham), The area cochleae 
 is the anterior portion of the fossula inferior. In it is the canalis centralis for the 
 nerve-fibres to the apical turn of the cochlea; and the tractus spiralis foraminosa 
 for the transmission of nerves to the first turn and a half of the cochlea. The 
 
THE MEMBRANOUS LABYRINTH 
 
 1169 
 
 inferior area of the vestibule {area vestibularis inferior) is back of the area cochleae 
 and a ridge separates the two. It transmits nerves to the saccule. At the posterior 
 part of the fossula inferior is a solitary foramen, the foramen singulare, which 
 transmits nerves to the ampulla of the posterior semicircular canal. 
 
 The Membranous Labyrinth (Labyrinthus Membranaceus) (Figs. 771, 772). 
 
 The membranous labyrinth is contained within the bony cavities just described, 
 having the same general form as the cavities in which it is contained, though 
 considerably smaller, being separated from the bony walls by a quantity of fluid, 
 the perilymph or liquor Gotunnii (perihjmpha) . It does not, however, float loosely 
 in this fluid, but in places is fixed to the walls of the cavity. The membranous 
 sac contains fluid, the endolymph {endohjm'pha) , and on the sac the ramifications 
 of the auditory nerve are distributed. 
 
 Within the osseous vestibule the membranous labyrinth does not quite preserve 
 the form of the bony cavity, but presents two membranous sacs, the utricle and 
 the saccule. 
 
 Ampullae 
 
 Ductus 
 Endolymphaticus 
 
 Fio. 772. — The membranous labyrinth (enlarged). 
 
 The Utricle (utriculus). — The utricle is the larger of the two, of an oblong 
 form, compressed laterally, and occupies the upper and back part of the vestibule, 
 lying in contact with the fovea semi-elliptica and the part below it. The highest 
 portion of the utricle is called the recess {recessus utriculi); it is placed in the 
 elliptical recess, and opening into it are the ampulla of the superior and external 
 semicircular canals. The central portion of the recess of the utricle receives upon 
 the side the external semicircular canal. This opening has not an ampulla. The 
 superior sinus is a prolongation upward and backward from the central portion of 
 the utricle and in the superior sinus the crus commune and the superior and 
 posterior semicircular canals open. The lower and inner portion of the utricle 
 is the inferior sinus, and into it the ampulla of the posterior semicircular canal 
 opens. The floor and anterior wall of the recess of the utricle are much thicker 
 than elsewhere, and form the macula acustica utriculi, which receives the utricular 
 filaments of the auditory nerve and has attached to its internal surface a layer of 
 calcareous particles which are called otoliths. The cavity of the utricle communi- 
 cates behind with the membranous semicircular canals by five orifices. From 
 its anterior wall is given off a small canal (dvchis utriculosaccularis) , which joins 
 with a canal from the saccule, the ductus endolymphaticus. The utricle is joined 
 to the bony wall by numerous fibrous bands. 
 
 74 
 
1170 THE ORGANS OF SPECIAL SENSE 
 
 The Saccule (sacculus). — The saccule is the smaller of the two vesicular sacs; 
 it is globular in form, lies in the elliptical recess near the opening of the scala 
 vestibuli of the cochlea. Its anterior part exhibits an oval thickening, the macula 
 acustica sacculi, to which are distributed the saccular filaments of the auditory 
 nerve. Its cavity does not directly communicate with that of the utricle. From 
 the posterior wall is given off a canal, the ductus endolymphaticus. This duct 
 passes along the aquaeductus vestibuli and ends in a blind pouch on the posterior 
 surface of the petrous portion of the temporal bone, where it is in contact with 
 the dura mater. The upper extremity of the saccule looks upward and back- 
 ward and forms the sinus utricularis sacculi. This lies in contact with but is not 
 a part of the wall of the utricle. The vestibule contains the closed end of the 
 ductus cochlearis. This is known as the caecum vestibulare. The ductus coch- 
 learis lies below the saccule in what Reichert described as the recessus cochlearis, 
 and it enters the spiral canal. From the lower part of the saccule a short tube, 
 the canalis reunions of Hensen (ductus reuniens [Henseni]), passes downward 
 and outward to open into the ductus cochlearis. The saccule is held in posi- 
 tion by numerous fibrous bands which pass between the saccule and the bony 
 wall. 
 
 The Membranous Semicircular Canals (ductus semicirculares).— The mem- 
 branous semicircular canals are about one-third the diameter of the osseous canals, 
 but in number, shape, and general form they are precisely similar, and present 
 at one end within the osseous ampulla a membranous ampulla. These ampullae 
 are called ampullae membranaceae. The canals open by five orifices into the utricle, 
 one opening being common to two canals. In the ampullae the wall is thickened, 
 and projects into the cavity as a fiddle-shaped, transversely placed elevation, the 
 septum transversum, in which the nerves end. 
 
 The membranous canals are attached here and there to the bone by numerous 
 fibrous bands, the so-called ligaments (ligamenta lahyrinthi canaliculorum). 
 
 Structure. — ^The walls of the utricle, saccule, and membranous semicircular 
 canals consist of three layers. The outer layer is a loose and flocculent struc- 
 ture, apparently composed of ordinary fibrous tissue, containing blood-vessels 
 and pigment-cells analogous to those in the pigment coat of the retina. The 
 middle layer, thicker and more transparent, bears some resemblance to the 
 hyaloid membrane, but it presents on its internal surface, especially in the semi- 
 circular canals, numerous papilliform projections, and, on the addition of acetic 
 acid, presents an appearance of longitudinal fibrillation and elongated nuclei. 
 The inner layer is formed of polygonal nucleated epithelial cells. The raphe of 
 each semicircular canal is a line upon the concave side of the canal. Along the 
 raph^ the height of the epithelial cells is distinctly increased. In the ampullae 
 adjacent to the cristae acusticae the cells are cylindrical and constitute the 
 plana semilunata. In the maculae of the utricle and saccule, and in the trans- 
 verse septa of the ampullae of the canals, the middle coat is thickened and the 
 epithelium is columnar, is increased in height, and passes into the neuro-epithe- 
 lium. The neuro -epithelium consists of supporting cells and hair-cells. 
 
 1. The supporting cells are long, wider at the ends than in the centre, contain an 
 oval nucleus, and the lower end of the cell is fissured. 
 
 2. The hair-cells are columnar, with bulged lower ends and free upper ends. 
 The bulged lower ends, each of which contains a spherical nucleus, do not reach 
 higher than the middle of the epithelial layer. Each free upper end is surmounted 
 by a long, tapering filament. These filaments constitute auditory hair, and they 
 project into the cavity. The filaments of the auditory nerve enter these parts, 
 and, having pierced the outer and thickened middle layer, they lose their medul- 
 lary sheath, and their axis-cylinders divide into three or four branches at the 
 larger and deeper ends of the hair-cells. These branches form a horizontal plexus 
 
THE MEMBRANOUS LABYRINTH 
 
 1171 
 
 {stratum plexiforme). "These surround the hair-cells like the calyx of a flower, 
 and give off ascending branches, which, however, do not reach the surface. In 
 this way one branch usually comes in contact with many hair-cells."^ 
 
 Fig. 773. — Floor of scala media, showing the organ of C!orti, etc. 
 
 Numerous small prismatic bodies termed statoliths, otokonien crystals or otoliths, 
 and consisting of a mass of minute crystalline grains of carbonate of lime, held 
 
 COCHLEAR NCRVE 
 AND GANGLION 
 
 Fig. 774. — Cochlea in transverse section. Observe especially the canal of the cochlea, which is a part of 
 the membranous labyrinth. (Testut.) 
 
 together in a mesh of delicate fibrous tissue, are contained in the walls of the 
 utricle and saccule opposite the distribution of the nerves. The membrane is 
 
 ' Histology and Microscopic Anatomy. By Dr. Ladislaus Szymonowicz. Translated and edited bv John 
 Biuce MacCallum, M.D. ■^ """" 
 
]172 THE ORGANS OF SPECIAL SENSE 
 
 called the otolith membrane. A calcareous material is also, according to Bowman, 
 sparingly scattered in the cells lining the ampullae of the semicircular canals. The 
 conical thickening in the ampulla corresponds to the otohth membrane and is 
 called the cupola. 
 
 The Membranous Cochlea Ductus Cochlearis or Scala Media consists of a spirally 
 arranged tube enclosed in the bony canal of the cochlea and lying along its outer 
 wall. It begins as a blind end in the recessus cochlearis of the vestibule. This 
 beginning is the caecum vestibulare. It ascends inside the bony cochlea and termi- 
 nates at the apex of the cochlea by a blind end, the lagena {caecum cwpulare). The 
 manner in which it is formed will now be described. 
 
 The osseous spiral lamina, as above stated, extends only part of the distance be- 
 tween the modiolus and the outer bony wall of the cochlea. A membrane, the basilar 
 membrane (membrana basilaris) (Fig. 773), stretches from its free edge to the outer 
 wall of the cochlea,and completes the roof of the scala tympani. A second and more 
 delicate membrane, the membrane of Reissner {membrana vestibularis [Reissneri]) 
 (Fig. 773), extends from the thickened periosteum covering the lamina spiralis ossea 
 to the outer wall of the cochlea, to which it is attached at some little distance above 
 the membrana basilaris. A canal is thus shut off between the scala tympani below 
 and the scala vestibuli above; this is the membranous canal of the cochlea {ductus 
 cochlearis or scala media) (Fig. 774). It is triangular on transverse section, its roof 
 being formed by the membrane of Reissner, its outer wall by the periosteum which 
 lines the bony canal, and its floor by the membrana basilaris, and the outer part 
 of the lamina spiralis ossea, on the former of which is placed the organ of Corti. 
 Reissner's membrane is thin and homogeneous, and is covered on its upper and 
 under surfaces by a layer of epithelium. The periosteum, which forms the outer 
 
 wall of the ductus cochlearis, is greatly 
 NERVE-FIBRES PASSING OUT thickcncd aud altered in character, 
 
 GANGLION SPIRAL BETWEEN TH E TWO LAYERS OF _ 1 • 11 1 1 
 
 spiRALE FIBRES LAMINA SPIRALIS OSSEA ^^^^ formmg what iscallcd the spiral liga- 
 ment of the cochlea {ligamentum spirals 
 cochleae) (Fig.773) . It projects inward 
 below as a triangular prominence, the 
 crista basilaris, which gives attach- 
 ment to the outer edge of the mem- 
 brana basilaris, and immediately above 
 which is a concavity, the sulcus spiralis 
 extemus (Fig. 773) . The upper por- 
 ,.,, .^, tion of the ligamentum spirale con- 
 
 FiG. 775. — Part of the cochlear nerve, highly magnified. . ^ .,, '^■, •, 
 
 (Henie.) tauis numcrous capillary loops and 
 
 small blood-vessels, and forms what 
 is termed the stria vascularis. The stria is limited below by a prominence {promi- 
 nentia spiralis), in which a blood-vessel {vas prominens) is distinctly visible. 
 
 The lamina spiralis ossea (Fig. 774) consists of two plates of bone extending 
 outward; between these are the canals for the transmission of the filaments of the 
 auditory nerve. On the upper plate of that part of the osseous spiral lamina 
 which is outside Reissner's toembrane the periosteum is thickened to form the 
 limbus laminae spiralis, and this terminates externally in a concavity, the sulcus 
 spiralis intemus, which presents, on section, the form of the letter C; the upper 
 part of the letter, formed by the overhanging extremity of the limbus, is named 
 the labium vestibulare ; the lower part, prolonged and tapering, is called the labium 
 tympanicum, and is perforated by 4000 foramina {foramina nervosa) for the pass- 
 age of the cochlear nerves. Externally, the labium tympanicum is continuous 
 with the membrana basilaris. The upper surface of the labium vestibulare is 
 intersected at right angles by a number of furrows, between which are numerous 
 elevations; these present the appearance of teeth along the free margin of the 
 
THE MEMBRANOUS LABYRINTH 
 
 1173 
 
 labium, and have been named by Huschke the auditory teeth. There are 7000 
 auditory teeth. The basilar membrane may be divided into two areas, inner and 
 outer. The inner is thin, and is named the zona arcuata or zona tecta (Fig. 773) ; it 
 supports the organ of Corti. The outer is thicker and striated, and is termed 
 the zona pectinata. The under surface of the membrane is covered by a layer of 
 
 Outer hair cells. 
 Membrana tectoria. 
 
 Limbus. 
 
 Cells of Deiters. 
 Outer rod. 
 Basilar membrane. 
 Fig. 776. — Section through the organ of Corti. Magnified. (G. Retzius.) 
 
 - - -= SVo = 000 „'=i'o o o »<> 
 
 Nerve fibres. 
 
 vascular connective tissue. One of these vessels is somew^hat larger than the rest, 
 and is named the vas spirale (Fig. 776) ; it lies below^ Corti's tunnel. 
 
 Organ of Corti^ (organon spirale [Cortii]) (Figs. 773, 774, 776, and 777). — The 
 inner part of the membrana basilaris — that is, the part directed toward the canal 
 of the ductus cochiearis — is covered with epithelium, which is largely neuro-epithe- 
 
 INTERNAL AUDI-_ 
 TORY CELLS 
 
 BASILAR MEMBRANE 
 
 Fig. 777. — Organ of Corti. Diagrammatic view of a small portion. (Testut.) 
 
 Hum. It forms the organ of Corti. In this lie the terminations of the cochlear 
 nerve. It appears at first sight as a papilla, winding spirally throughout the 
 whole length of the ductus cochiearis, from which circumstance it has been desig- 
 nated the papilla spiralis. More accurately viewed, it is seen to be composed 
 of a remarkable arrangement of cells, which may be likened to the keyboard of a 
 
 ' Corti's original paper is in the Zeitschrift f. Wissen. Zool., iii., 109. 
 
1174 
 
 THE ORGANS OF SPECIAL SENSE 
 
 pianoforte. The organ of Corti consists of an inner 'part and an outer part. Each 
 part contains auditory cells and supporting cells. Of these cells, the two central 
 ones are rod-like bodies and are called the inner and outer rods of Corti. They are 
 placed on the basilar membrane, at some little distance from each other, but are 
 inclined toward each other, so as to meet at their opposite extremities, and form 
 a series of arches roofing over a minute tunnel, the canal or tunnel of Corti, 
 between them and the basilar membrane, which ascends spirally through the 
 whole length of the cochlea. 
 
 The inner rods (Fig. 776), some 6000 in number, are more numerous than the 
 outer ones, and rest on the basilar membrane, close to the labium tympanicum; 
 they project obliquely upward and outward, and terminate above in expanded 
 extremities which resemble in shape the upper end of the ulna, with its sigmoid 
 cavity, coronoid and olecranon processes. On the outer side of the rod, in the 
 angle formed between it and the basilar membrane, is a nucleated mass of proto- 
 plasm; while on the inner side is a row of epithelial cells, inner hair-cells (Fig. 
 776), surmounted by a brush of fine, stiff, hair-like processes. On the inner side 
 of these cells are two or three rows of columnar supporting cells, which are 
 continuous with the cubical cells lining the sulcus spiralis internus. 
 
 Fig. 778. — Longitudinal section of the cochlea, showing the relations of the scalae, the ganglion spirale, etc. 
 S. v., Scala vestibuli. S. T., Scala tympani. S. M., Scala media. L. S., Ligamentum spirale. G. S., Ganglion 
 spirale. 
 
 The outer rods (Fig. 776) , numbering about 4000, also rest by a broad foot on 
 the basilar membrane; they incline upward and inward, and their upper extremity 
 resembles the head and bill of a swan ; the back of the head fitting into the con- 
 cavity — the analogue of the sigmoid cavity — of one or more of the internal rods, 
 and the bill projecting outward as a phalangeal process of the membrana reticu- 
 laris, presently to be described. 
 
 In the head of these outer rods is an oval portion, where the fibres of which 
 the rod appears to be composed are deficient, and which stains more deeply with 
 carmine than the rest of the rod. At the base of the rod, on its internal side — 
 that is to say, in the angle formed by the rod with the basilar membrane — is a 
 similar protoplasmic mass to that found on the outer side of the base of the inner 
 rod ; these masses of protoplasm are probably the undifferentiated portions of the 
 cells from which the rods are developed. External to the outer rod are three or 
 four successive rows of epithelial cells, more elongated than those found on the 
 
THE MEMBRANOUS LABYRINTH 1175 
 
 internal side of the inner rod, but, like them, furnished with minute hairs or cilia. 
 These are termed the outer hair-cells, in contradistinction to the inner hair-cells 
 above referred to. There are about 12,000 outer hair-cells, and about 3500 inner 
 hair-cells. 
 
 The hair-cells are somewhat oval in shape; their free extremities are on a 
 level with the heads of Corti's rods, and from each some twenty fine hairlets 
 project and are arranged in the form of a crescent, the concavity of which opens 
 inward. The deep ends of the cells are rounded and contain large nuclei; they 
 reach only as far as the middle of Corti's rods, and are in contact with the rami- 
 fications of the nervous filaments. Between the rows of the outer hair-cells 
 are rows of supporting cells, called the cells of Deiters; their expanded bases are 
 planted on the basilar membrane, while their opposite ends present a clubbed 
 extremity or phalangeal process. Immediately to the outer side of Deiters's cells 
 are some five or six rows of columnar cells, the supporting cells of Hensen. Their 
 bases are narrow, while their upper parts are expanded and form a rounded 
 elevation on the floor of the ductus cochlearis. The columnar cells lying outside 
 Hensen's cells are termed the cells of Claudius. A space is seen between the 
 outer rods of Corti and the adjacent hair-cells; this is called the space of Nuel. 
 
 The lamina reticularis or membrane of Kblliker is a delicate framework per- 
 forated by rounded holes. It extends from the inner rods of Corti to the external 
 row of the outer hair-cells, and is formed by several rows of "minute fiddle- 
 shaped cuticular structures" called phalanges, between which are circular 
 apertures containing the free ends of the hair-cells. The innermost row of phal- 
 anges consists of the phalangeal processes of the outer rods of Corti; the outer 
 pows are formed by the modified free ends of Deiters's cells. 
 
 Covering over these structures, but not touching them, is the membrana tectoria 
 or membrane of Corti (Figs. 773 and 776), which is attached to the vestibular sur- 
 face of the lamina spiralis close tp the attachment of the membrane of Reissner. 
 It is thin near its inner margin, and overlies the auditory teeth of Huschke. Its 
 outer half is thick, and along its lower edge, opposite the inner hair-cells, is a 
 clear band, named Hensen's stripe. Externally, the membrane becomes much 
 thinner, and is attached to the outer row of Deiters's cells (Retzius). 
 
 The fibres from the cochlear nerve enter the organ of Corti as axis-cylinders, 
 which pass directly to the deepest portions of the inner and outer hair-cells by 
 way of the canal of Corti or by the space of Nuel. The terminations arborize 
 about the lower portions of the hair-cells and end on the surfaces of the hair-cells. 
 
 The inner surface of the osseous labjrrinth is lined by an exceedingly thin fibro- 
 serous membrane, analogous to a periosteum, from its close adhesion to the 
 inner surfaces of these cavities, and performing the office of a serous membrane by 
 its free surface. It lines the vestibule, and from this cavity is continued into the 
 semicircular canals and the scala vestibuli of the cochlea, and through the helico- 
 trema into the scala tympani. A delicate tubular process is prolonged along the 
 aqueduct of the vestibule to the inner surface of the dura mater. This membrane 
 is continued across the fenestra ovalis and fenestra rotunda, and consequently has 
 no communication with the lining membrane of the tympanum. Its attached 
 surface is rough and fibrous, and closely adherent to the bone; its free surface is 
 smooth and pale, covered with a layer of epithelium, and secretes a thin, limpid 
 fluid, the aqua labyrinth!, liquor Cotunnii or perilymph (Blainville). 
 
 The scala media is closed above and below. The upper blind extremity is 
 termed the lagena, and is attached to the cupola at the upper part of the helico- 
 trema; the lower end is lodged in the recessus cochlearis of the vestibule. Near 
 this blind extremity, the scala media receives the canalis reunions of Hensen (Fig. 
 772), a very delicate canal, by which the ductus cochlearis is brought into con- 
 tinuity with the saccule. 
 
1176 THE ORGANS OF SPECIAL SENSE 
 
 The Arteries of the Labyrinth. — The arteries of the labyrinth are the internal 
 auditory, from the basilar, and the stylo-mastoid, from the posterior auricular. 
 The internal auditory divides at the bottom of the internal auditory meatus 
 into two branches, cochlear and vestibular. 
 
 The cochlear artery divides into numerous minute branches, which enter 
 foramina in the tractus spiralis foraminosa and course in the lamina spiralis ossea 
 to reach the membranous structures. The largest of the cochlear branches is in 
 the canalis centralis. 
 
 The vestibular branches accompany the nerves, and supply the membranous 
 structures in the vestibule and semicircular canals. Two arteries go to each 
 canal. The two vessels enter opposite extremities of the canal, and anastomose 
 at the summit of the canal. The vestibular vessels form a minute capillary net- 
 work in the substance of each membranous labyrinth. 
 
 The Veins of the Labyrinth. — The veins of the vestibule and semicircular canals, 
 the auditory veins, accompany the arteries, and receive those of the cochlea at the 
 base of the modiolus, to form the internal auditory vein {vv. auditivae internae), 
 which opens into the posterior part of the inferior petrosal sinus or into the lateral 
 sinus. 
 
 The Nerves of the Labyrinth. — The auditory nerve (n. acusticus),i\\e special nerve 
 of the sense of hearing, divides, at the bottom of the internal auditory meatus, 
 into two branches, the cochlear and vestibular. 
 
 The Vestibular Nerve {n. vestibularis), the posterior of the two, presents, as it lies 
 in the internal auditory meatus, a ganglion, the vestibular ganglion or the ganglion 
 of Scarpa {ganglion vestihulare) ; the nerve divides into three branches which pass 
 through minute openings at the upper and back part of the bottom of the meatus 
 {area vestibular ^posterior), and, entering the vestibule, are distributed to the utricle 
 and to the ampulla of the external and superior semicircular canals. 
 
 The nervous filaments enter the ampullary enlargements opposite the septum 
 transversum, and arborize around the hair-cells. In the utricle and saccule the 
 nerve-fibres pierce the membrana propria of the maculae, and end in arborizations 
 around the hair-cells. 
 
 The Cochlear Nerve {n. cochlearis) gives off the branch to the saccule, the fila- 
 ments of which are transmitted from the internal auditory meatus through the 
 foramina of the area vestibularis inferior, which lies at the lower and back part 
 of the floor of the meatus. It also gives off the branch for the ampulla of the 
 posterior semicircular canal, which leaves the meatus through the foramen singulare. 
 
 The rest of the cochlear nerve divides into numerous filaments at the base 
 of the modiolus; those for the basal and middle coils pass through the foramina 
 in the tractus foraminosus, those for the apical coil through the canalis centralis, 
 and the nerves bend outward to pass between the lamellae of the osseous spiral 
 lamina. Occupying the spiral canal of the modiolus is the spiral ganglion or gan- 
 glion of Corti {ganglion spirale), consisting of bipolar nerve-cells, which really con- 
 stitute the true cells of origin of this nerve, one pole being prolonged centrally to 
 the brain and the other peripherally to the hair-cells of Corti's organ. Reaching the 
 outer edge of the osseous spiral lamina, the nerve fibres pass through the foramina 
 in the labium tympanicum, where they lose their axis-cylinders. They enter the 
 organ of Corti and pass directly to the deep portions iDf the inner and outer hair-cells 
 by way of the canal of Corti and the space of Nuel. The terminations arborize 
 about the lower portions of the hair-cells and end in the surfaces of the cells. 
 
 Surgical Anatomy. — Malformations, such as imperfect development of the external parts, 
 absence of the meatus, or supernumerary auricles, are occasionally met with. Or the pinna may 
 present a congenital fistula, which is due to defective closure of the first visceral cleft, or rather 
 of that portion of it which is not concerned in the formation of the Eustachian tube, tympanum, 
 and meatus. In some cases the cephalo-auricular angle is almost absent; in others it is nearly 
 
THE MEMBRANOUS LABYRINTH 1177 
 
 a right angle. Projecting ears and long ears are said by some observers to be more common 
 among degenerates, criminals, and the insane than among the normal, the non-criminal, and 
 the sane. The skin of the auricle is thin and richly supplied with blood, but in spite of this it 
 is frequently the seat of frost-bite, due to the fact that it is much exposed to cold, and lacks the 
 usual underlying subcutaneous fat found in most other parts of the body. A collection of blood 
 is sometimes found between the cartilage and perichondrium {haematoma auris), usually the 
 result of traumatism, but not necessarily due to this cause. It is said to occur most frequently 
 in the ears of the insane. Keloid sometimes grows in the auricle around the puncture made for 
 ear-rings, and epithelioma occasionally affects this part. Deposits of urate of soda are often met 
 with in the pinna in gouty subjects. 
 
 The external auditory meatus can be most satisfactorily examined by light reflected down a 
 funnel-shaped speculum; by gently moving the latter in different directions the whole of the 
 canal and membrana tympani can be brought into view. The points to be noted are: the pres- 
 ence of wax or foreign bodies, the size of the canal, and the condition of the membrana tympani. 
 The accumulation of wax is often the. cause of deafness, and may give rise to very serious conse- 
 quences, causing ulceration of the membrane and even absorption of the bony wall of the canal. 
 Foreign bodies are not infrequently introduced into the ear by children, and, when situated in 
 the first portion of the canal, may be removed with tolerable facility by means of a minute hook 
 or loop of fine wire, the parts being illuminated with reflected light; but when they have slipped 
 beyond the narrow middle part of the meatus, their removal is in nowise easy, and attempts to effect 
 it, in inexperienced hands, may be followed by destruction of the membrana tympani and possibly 
 injury of the contents of the tympanum. The calibre of the external auditory canal may be nar- 
 rowed by inflammation of its lining membrane, running on to suppuration; by periostitis; hy polypi, 
 sebaceous tumors, und exostoses. The membrana tympani, when seen in a healthy ear, "reflects 
 light strongly, and, owing to its peculiar curvature, presents a bright spot of triangular shape at its 
 lower and anterior portion." From the apex of this, proceeding upward and slightly forward, is 
 a white streak formed by the handle of the malleus, while near the upper part of the membrane 
 may be seen a slight projection, caused by the short process of the malleus. In disease alterations 
 in color, lustre, curvature or inclination, and perforation must be noted. Such perforations may 
 be caused by a blow, a loud report, a wound, or as the result of suppuration in the middle ear. 
 
 The upper wall of the meatus is separated from the cranial cavity by a thin plate of bone; 
 the anterior wall is separated from the temporo-mandibular joint and parotid gland by the bone 
 forming the glenoid fossa; and the posterior wall is in relation with the mastoid cells; hence 
 inflammation of the external auditory meatus may readily extend to the membranes of the brain, 
 to the temporo-mandibular joint, or to the mastoid cells; and, in addition to this, blows on the 
 chin may cause fracture of the wall of the meatus. 
 
 The nerves supplying the meatus are the auricular branch of the pneumogastric, the auriculo- 
 temporal, and the auricularis magnus. The connections of these nerves explain the fact of the 
 occurrence, in cases of any irritation of the meatus, of constant coughing and sneezing from 
 implication of the pneumogastric, or of yawning from implication of the auriculo-temporal. No 
 doubt also the association of earache with toothache in cancer of the tongue is due to implication 
 of the same nerve, a branch of the fifth, which supplies also the teeth and the tongue. The 
 vessels of the meatus and membrana tympani are derived from the posterior auricular, temporal, 
 and internal maxillary arteries. The upper half of the membrana tympani is much more richly 
 supplied with blood than the lower half. For this reason, and also to avoid the chorda tympani 
 nerve and ossicles, incisions through the membrane should be made at the lower and posterior 
 part. 
 
 The principal point in connection with the surgical anatomy of the tympanum is its relations 
 to other parts. Its roof is formed by a thin plate of bone, which, with the dura mater, is all that 
 separates it from the temporal lobe of the brain. Its floor is immediately above the jugular 
 fossa and the carotid canal, the fossa being behind and the canal in front. Its posterior wall pre- 
 sents the openings of the mastoid cells. On its anterior wall is the opening of the Eustachian 
 tube. Thus it follows that in disease of the middle ear we may get subdural abscess, septic 
 meningitis, or abscess of the cerebrum or cerebellum from extension of the inflammation through 
 the bony roof; thrombosis of the lateral sinus, with or without pyaemia, by extension through the 
 floor; or mastoid abscess by extension backward. In addition to this, we may get fatal hemorrhage 
 from the internal carotid in destructive changes of the middle ear; and in throat disease we may 
 get the inflammation extending up the Eustachian tube to the middle ear. The Eustachian tube 
 is accessible from the nose. If the nose and mouth be closed and an attempt made to expire air, a 
 sense of pressure with dulness of hearing is produced in both ears, from the air finding its way up 
 the Eustachian tube and bulging out the membrana tympani. During the act of swallowing, the 
 pharyngeal orifice of the tube, which is normally closed, is opened, probably by the action of 
 the Dilator tubea muscle. This fact was employed by Politzer in devising an easy method of 
 inflating the tube. The nozzle of an india-rubber syringe is inserted into the nostril ; the patient 
 takes a mouthful of water and holds it in his mouth, both nostrils are closed with the finger and 
 thumb to prevent the escape of air, and the patient is then requested to swallow ; as he does so the 
 
1178 
 
 THE ORGANS OF SPECIAL SENSE 
 
 surgeon squeezes the bulb and the air is forced out of the syringe into his nose, and is driven into 
 the Eustachian tube, which is now open. The impact of the air against the membrana tympani 
 can be heard by the surgeon, if the membrane is intact, sound being conveyed by means of a 
 piece of india-rubber tubing, one end of which is inserted into the meatus of the patient's ear, the 
 other into that of the surgeon. The direct examination of the Eustachian tube is made by the 
 Eustachian catheter. This is passed along the floor of the nostril, close to the septum, with 
 the point touching the floor, to the posterior wall of the pharynx. When this is felt, the catheter 
 is to be withdrawn about half an inch, and the point rotated outward through a quarter of a 
 circle, and pushed again slightly backward, when it will enter the orifice of the tube, and will 
 be found to be caught, and air forced into the catheter will be heard impinging on the tympanic 
 membrane if the ears of the patient and surgeon are connected by an india-rubber tube. 
 
 THE SKIN (INTEGUMENTUM COMMUNE). 
 
 The skin covers the body surface and is continuous with the mucous membrane 
 at the origin and termination of the ahmentary canal and at the openings of other 
 canals. The skin is a protective coat, a regulator of body-temperature, contains 
 multitudes of the terminations of sensory nerves, and is the seat of the organ of 
 touch (organon tactus). These nerve-terminations are connected with nerve-fibres of 
 temperature, pressure, and pain. Connected with the skin are sweat-glands which 
 have important excretory functions and sebaceous glands. From its superficial part 
 come appendages, the hairs, and nails. The skin is elastic and varies in thickness 
 from 0.5 mm. to 4 mm. It is thinnest in the eyelids and prepuce, and thickest over 
 the back of the neck, back of the shoulders, palms of the hands, and soles of the 
 feet. Its color depends in part on the blood within it, and in part upon pigment. 
 The deepest hue is about the anus, in the genital region, in the axillae, over the 
 mammary glands, and in the parts exposed to air, light, and varied temperatures. 
 The color varies with age, being pinkish in extreme youth and becoming yellow 
 in old age. It varies with exposure and with climate, being deepest in those who 
 brave all weathers and temperatures and in those who dwell beneath a tropical sun. 
 
 It also varies with race, and this is 
 so well recognized that races are class- 
 ified by the color of the skin into the 
 Black,White,Yellow, and Brown races. 
 The color of the skin is also affected 
 in certain diseases; being extremely 
 pale in anaemia, brown in Addison's 
 disease, yellow in jaundice, etc. 
 
 In most situations the skin is mova- 
 ble, but in some it is attached closely 
 to underlying structures, and is con- 
 sequently immovable on the scalp, 
 the palms of the hands, the soles of 
 the feet, and the outer portion of the 
 pinna of the ear. The skin is fairly 
 smooth, but close examination dis- 
 closes multitudes of openings, creases, 
 furrows, depressions, folds, and hairs. 
 Hair-follicles open upon the surface, 
 and the ducts of sebaceous glands 
 and of sweat-glands perforate the skin. 
 About the joints are folds of skin (retinacula cutis), and temporary folds or 
 wrinkles are created by the contraction of superficial muscles. The facial wrinkles 
 of advancing years are due to habitual expression and loss of skin elasticity. A 
 dimple is a permanent pit or depression due to adhesion of the surface to parts 
 beneath. The ridges and furrows on the palms, soles, and flexor aspects of the 
 
 LONGITUDINAL 
 FURROWS 
 
 RIDGES OF SKIN 
 
 INTERRUPTED BY 
 
 LONGITUDINAL 
 
 FURROWS 
 
 FURROWS 
 OF SKIN 
 
 FLEXION FURROWS 
 OPPOSITE THE 
 FLEXURE OF 
 THE JOINT 
 
 Fig. 779. — The furrows and ridges of the surface of the 
 skin from the palm or surface of the middle finger. (Toldt.) 
 
THE SKIN 
 
 1179 
 
 digits are permanent, and over the palmar surface of the digits they are arranged 
 in definite forms which endure through life and are so distinctive that they have 
 been utilized by police officials in determining the identity of individuals. These 
 folds are due to the papillae of the skin being arranged in rows; some of the papillae 
 proliferate, and linear depressions occur in the horny layer (Philippson). 
 
 Fig. 780. — Anterior surface. Fig. 781. — Posterior surface. 
 
 The general course of the connective-tissue bundles of the corium, determined by the direction assumed by the 
 
 linear clefts made in the skin when it is punctured by a round awl. (Langer.) 
 
 Fig. 779 shows skin ridges (cristae cutis), skin furrows (sulci cutis), furrows 
 opposite joints due to acts of flexion, and called flexure furrows, and longitudinal 
 furrows. 
 
 When the skin is punctured by a round awl it tends to split in a definite 
 direction, which direction varies with the region stabbed. These clefts are known 
 
1180 
 
 THE ORGANS OF SPECIAL SENSE 
 
 as the lines of cleavage of Langer (Figs. 780 and 781), and depend upon the 
 arrangement of the connective-tissue bundles of the corium. These connective- 
 tissue bundles certainly influence the formation of folds and furrows. In many 
 portions of the body the cutaneous surface is divided by linear furrows into irregu- 
 larly shaped areas (Fig. 782). The skin consists of two layers: a superficial layer, 
 the epidermis, and a deep layer, the corium or dermis. 
 
 The Corium, Cutis Vera, Dermis or True Skin (Figs. 783, 784, and 786) is a 
 connective-tissue structure which arises from the mesoderm. It consists espe- 
 cially of connective tissue and elastic fibres; it contributes elasticity to the skin, 
 and is the seat of the sensitive layer. The corium is composed of two layers, 
 the reticular and the papillary. 
 
 MOUTH OF ^^c 
 HAIR-FOLLICLES'-*..^/' 
 
 -..FURROW 
 
 ""of skin 
 
 Fig. 782. — The furrows of the skin and the areas which these furrows delimit, reproduced from an impression of 
 
 the dorsal surface of the wrist. (Toldt.) 
 
 The Deep or Reticular Layer or Tunica Propria {stratum reticulare) rests upon 
 the subcutaneous tissue. It passes superficially into the papillary layer, and at 
 most places into the subcutaneous tissue without a sharp line of differentiation. 
 At some places, for instance in the nipple, the deep layer of the corium rests 
 upon a layer of muscular fibre. In the face this muscle-fibre is striated and sends 
 
 FURROWS.OF SKIN 
 
 RIDGES OF SKIN 
 
 / STRATUM 
 IDERMIS'j STRATUM 
 
 ORIUM I 
 
 TOUCH CORPUSCLEv 
 
 STRATUM CORNEUS f 
 
 LUCIDUM 
 RETE MUCOSUM 
 
 STRATUM PAPILLARE 
 
 STRATUM RETICULARE 
 
 SUBCUTANEOUS 
 AREOLAR tissue' 
 
 ORIFICE OF 
 
 SUDORIFEROUS 
 
 DUCT 
 
 SUDORIFEROUS 
 
 DUCT 
 
 CAPILLARY 
 LOOP OF 
 PAPILLA 
 
 BLOODVESSELS 
 OF CORIUM 
 
 BODY OF 
 
 SUDORIFEROUS 
 
 GLAND 
 
 Fig. 783. — Vertical section through the skin of the finger-tip. The layers of the epidermis and of the corium. 
 The subcutaneous areolar tissue. The sudoriferous or sweat-gland. (Toldt.) 
 
 prolongations to the papillary layer; in the nipple and scrotum it is non-striated. 
 The reticular layer is composed of bundles of white fibrous tissue, arranged in a 
 network. In the meshes of the network are fat, blood-vessels, lymphatics, seba- 
 ceous glands, sweat-glands, and hair-follicles. 
 
 The Subcutaneous Areolar Tissue or Tela Subcutanea (panniculus adiposus) con- 
 nects, the skin to the parts beneath ; it is composed of bundles of connective tissue 
 
THE SKIN 
 
 1181 
 
 ARRECTOR 
 PIL> MUSCLE 
 
 CORIUM EPIDERMIS 
 
 which cross repeatedly and form spaces. In almost all regions the spaces contain fat, 
 but in the scrotum and external ear they do not contain fat. When the connective- 
 tissue fibres of the panniculus adiposus are long and nearly parallel to the skin- 
 surface the skin becomes wrinkled; when they are short and nearly at right angles 
 to the surface, the skin cannot wrinkle. 
 
 The Superficial or Papillaxy Layer or Corpus Papillare of the Corium (stratum papil- 
 lare) lies just beneath the epidermis, contains the papillae, and is composed of a 
 network of fine bundles of fibrous tissue. The papillae are composed of fine 
 strands of connective tissue and elastic 
 tissue. They project from the corium 
 beneath the epidermis and enter into 
 depressions of the epidermis. They vary 
 greatly in size, averaging y^ of an inch 
 in height and 2-5-0" of ^^i i'^ch in width at 
 the base. In the face, especially in the 
 eyelids, they are insignificant. On the 
 glans penis, the palms of the hands, and 
 the soles of the feet, and in the nipples, 
 they are large. In the palmar surfaces 
 of the hands and fingers and the plantar 
 surfaces of the feet and toes they pro- 
 duce permanent ridges (Fig.785). A ridge 
 is composed of two or more rows of 
 
 papillae, and the ducts of sweat-glands Fig. 784.— vertical section through the skin of the 
 
 „. v.A.„, „„„,„ ^e »^„„CU„„ ^^A trunk in the region of the arch of the ribs. One of 
 
 emerge between rows Ot papillae, and the small hairs is seen in longitudinal section. (Toldt.) 
 
 open on the curved surface ridges (Fig. 
 
 785). Most of the papillae contain loops of capillaries, and are called vascular 
 papillae. Some contain nerve-terminations and are called nervous papillae. Be- 
 tween the papillary layer of the corium and the epidermis is a very thin and 
 structureless membrane called the basal membrane. 
 
 SUDORIFEROUS SUBCUTANEOUS 
 GLANDS AREOLAR TISSUE 
 
 PAPILL>E 
 CORIUM 
 
 SUDORIFEROUS 
 DUCTS 
 
 Fig. 785. — The furrows and ridges of true skin on the palmar surface of one of the fingers, the epidermis 
 
 having been removed. (Toldt.) 
 
 The Cuticle, Scarf Skin or Epidermis (Figs. 783, 784, 786, and 787).— The 
 cuticle, scarf skin or epidermis is composed of layers of epithelium and is 
 derived from the ectoderm. The epithelium is stratified, and there are no 
 blood-vessels. Two layers can be readily made out, the superficial or homy 
 layer and the deeper or Malpighian layer. 
 
 The Homy Layer {stratum corneum). — I'he horny layer is formed by several 
 layers of non-nucleated scaly cells. The cells consist of keratin. The surface 
 cells of the horny layers are being constantly rubbed oft', and are being replaced 
 by cells from the Malpighian layer, which are converted into keratin as they near 
 the surface. 
 
1182 
 
 THE OBGANS OF SPECIAL SENSE 
 
 The Malpighian Layer. — The Malpighian layer of the epidermis is divided into 
 four layers, named, from without inward, the stratum lucidum, the stratum granu- 
 losum, the stratum mucosum, and the stratum germinativum. 
 
 The Stratum Lucidum is not classified by all writers as part of the Malpighian 
 layer. Some anatomists classify it as a separate layer. It is here regarded as the 
 most superficial part of the Malpighian layer. It consists of several layers of flat 
 cells, the nuclei of which are beginning to disappear. The cells contain eleidin 
 granules. In regions where the epidermis is thin the stratum lucidum is absent. 
 
 The Stratum Granulosum consists of several layers of nucleated flat cells, con- 
 taining kerato hyaline granules. These granules are probably formed from the 
 disintegrating nucleus, and in the stratum lucidum are converted into eleidin. 
 
 Fibrous 
 tissue 
 
 Sebaceous 
 Olands 
 
 Sweat-Olands 
 
 Nutrient Artery 
 
 Fig. 786. — A sectional view of the skin (magnified). 
 
 The Mucous Layer, the Stratum Spinosum or the Stratum Mucosum consists of 
 numerous layers of nucleated, polygonal, spine-shaped cells known as prickle cells 
 or finger cells. Between the cells of the stratum mucosum are spaces containing 
 pigment granules and leukocytes. Processes from the prickle-cells join adjacent 
 cells. This layer contains numerous connective-tissue fibres arranged in a net- 
 work, and known as epidermic fibrils. 
 
 The Stratum Cylindricum or Stratum Germinativum is composed of cylindrical or 
 prickle-cells, the points of which are directed downward. Fine fibrils pass up 
 from the corium between the cells, and there is cement-substance as well between 
 them. 
 
 Pigmentation of the Skin. — As previously stated, in certain regions the skin of the 
 white race is brown because of pigmentation (areolae, nipples, around the anus, 
 axillae, scrotum, labia majora). This is due to pigment within the epithelial and 
 
THE SKIN 
 
 1183 
 
 connective-tissue cells of the papillary layer of the corium, and in the basal cells 
 of the epidermis. There are few or none of these pigmented cells in the stratum 
 corneum of one of the Caucasian race. 
 
 Stratum corneum. -l 
 
 Stratum lucidumA 
 Stratum grannlosum. f 
 
 Stratum mucosum 
 Malpighii. ' 
 
 Stratum germinativum. 
 
 -Nerve-fibrU$. 
 
 Fig. 787. — Section of epidermis. (Ranvier.) 
 
 "In negroes and other colored races the deep pigmentation is due to a similar 
 distribution of the pigment granules in the entire epidermis; but even here the 
 pigmentation decreases toward the surface, although the uppermost cells of the 
 
 Fig. 788. — Microscopic section of skin, showing the epidermis and derma ; a hair in its follicle ; 
 the Erector pili muscle ; sebaceous and sudoriferous glands. 
 
 stratum corneum always contain some pigment. The nuclei of the cells are always 
 free from coloring matter. The question as to the origin of the pigment is as yet 
 unsolved."^ 
 
 A Text-book of Histology. By A. A. BiJhm and M. von Davidoff. Translated and edited by G. Carl Huber. 
 
1184 
 
 THE ORGANS OF SPECIAL SENSE 
 
 The Arteries and Veins of the Skin (Fig. 789). — The arteries supplying the skin 
 vary in number, and vary much in size, being largest in regions exposed to 
 pressure, as the skin of the palms, soles, and buttocks. The arteries enter the 
 skin from a network in the subcutaneous tissue, and by an anastomosis in the 
 deepest part of the corium form a network {rete arteriosum cutaneum). The vessels 
 send branches to the fat and to the sweat-glands. Branches from the network just 
 described ascend and form a second network in the corium beneath the papillae. 
 This is called the subpapillary network {rete arteriosum suhpapillare). From this net- 
 work fine capillary vessels pass into the papillae, forming, in the smaller papillae, 
 a single capillary loop, but in the larger a more or less convoluted vessel. From 
 this network branches go to the hair-follicles and sebaceous glands. The blood 
 from the papillae passes into a plexus (rete venosum) beneath the papillae. This 
 communicates with another plexus {rete venosum), between the corium and sub- 
 
 RETE 
 VENOSUM 
 
 SUBPAPILLARY 
 NETWORK 
 
 EPIDERMIS 
 — PAPILLARY LAYER" 
 
 RETE 
 VENOSUM 
 
 RETE ARTERIOSUM 
 CUTANEUM 
 
 SUBCUTANEOUS 
 TISSUE 
 
 RETE 
 VENOSUM 
 
 Fig. 789. — The distribution of the blood-vessels in the skin of the sole of the foot. (Spalteholz.) 
 
 cutaneous tissue. In some regions one or more retia are interposed between these 
 two. The veins from the sweat-glands, sebaceous glands, superficial fat, and hair- 
 follicles are received by the retia venosa. From the deepest rete veins pass to the 
 subcutaneous tissue, and these veins enter the large subcutaneous veins. 
 
 The Lymphatics of the Skin. — There are numerous lymphatics supplied to the 
 skin which form two networks, superficial and deep, communicating with each 
 other and with the lymphatics of the subcutaneous tissue by oblique branches. 
 They originate in the cell-spaces of the tissue. 
 
 The Nerves of the Skin. — The nerves of the skin terminate partly in the epidermis 
 (Figs. 783 and 787) and partly in the cutis vera (Fig. 783) . The former are pro- 
 longed into the epidermis from a dense plexus in the superficial layer of the corium 
 and terminate between the cells in bulbous extremities; or, according to some 
 observers, in the deep epithelial cells themselves. The latter terminate in end- 
 bulbs,- touch-corpuscles, or Pacinian bodies (Fig. 783), in the manner already 
 described; and, in addition to these, a considerable number of fibrils are distrib- 
 uted to the hair-follicles, which are said to entwine about the follicle in a circular 
 
THE NAILS 
 
 1185 
 
 manner. Other nerve-fibres are supplied to the plain muscular fibres of the hair- 
 follicles (arrectores pili) and to the muscular coat of the blood-vessels. These are 
 probably non-medullated fibres. 
 
 The Appendages of the Skin. 
 
 The appendages of the skin are the nails, the hairs, the sudoriferous and seba- 
 ceous glands, and their ducts. 
 
 The nails and hairs are peculiar modifications of the epidermis, consisting 
 essentially of the same cellular structure as that tissue. 
 
 Eponychium, 
 
 Nail. 
 
 Stratum 
 
 MalpighiiJ 
 
 Stratum corneum 
 
 of the nail 
 
 groove. 
 
 Fig. 790. 
 
 -Longitudinal section through human nail and its nail groove (sulcus). 
 Davidoff's Histology. 
 
 Stratum 
 corneum. 
 
 '--'Iratuin 
 granulosum. 
 
 Corium. 
 
 Blood-vessel. 
 
 (From Bohm and 
 
 The Nails (ungues) (Figs. 790, 791, 792, 793, 794, and 795).— The nails are flat- 
 tened, elastic structures of a horny texture, placed upon the dorsal surface of the 
 terminal phalanges of the fingers and toes. Each nail is convex on its outer sur- 
 face, concave within. Its chief mass, called the body (corpus unguis), lies upon 
 the nail-bed. The free edge is called the margo liber. Each lateral margin (margo 
 lateralis), like the proximal short edge of the nail (margo occultus), lies in a groove 
 of the cutis, the ungual fold (sulcus matricis unguis). The ungual wall (vallum 
 unguis) overlies the lateral and posterior edges. The nail is implanted by means 
 of a portion, called the root (radix unguis), into a groove in the skin. The root is 
 beneath the ungual wall and is composed of cells which have not yet become 
 
 Nail 
 
 Stratum Malpighii. 
 
 Nail wail. 
 
 Nail groove. 
 
 'num. 
 Blood- vessel. 
 
 Fig. 791. — Transverse section through human nail and its sulcus. (From Biihm and Davidoff's Histology.) 
 
 horny. It is white in color. The nail has a very firm adhesion to the cutis vera, 
 being accurately moulded upon the surface of the true skin, as the epidermis is in 
 other parts. The part of the cutis beneath the body and root of the nail is called 
 the matrix (matrix unguis), because it is the part from which the nail is produced. 
 Corresponding to the body of the nail, the matrix is thick, and raised into a series 
 of longitudinal ridges (cristae matricis unguis), which are very vascular, and the 
 color is seen through the transparent tissue. Behind this, near the root of the 
 nail, the papillae are small, less vascular, and have no regular arrangement, and 
 here the tissue of the nail is somewhat more opaque; hence this portion is of a 
 whiter color, and is called the lunula on account of its crescentic shape. 
 
1186 
 
 THE ORGANS OF SPECIAL SENSE 
 
 The cuticle, as it passes forward on the dorsal surface of the finger or toe, is 
 attached to the surface of the nail, a little in advance of the nail root; at the 
 extremity of the finger it is connected with the under surface of the nail a little 
 behind its free edge. The cuticle and the horny substance of the nail (both epi- 
 dermic structures) are thus directly continuous with each other. The nails con- 
 sist of a greatly thickened stratum lucidum, the stratum corneum forming merely 
 
 SULCUS OF 
 MATRIX 
 
 LATERAL 
 MARGIN 
 
 THIRD^, 
 
 phalanx' 
 
 PERIOSTEU 
 
 OF FINOrP 
 
 Fig. 792. — Transverse section through the nail and the terminal portion of the ring finger. (Toldt.) 
 
 the thin cuticular fold (eponychium) which overlaps the lunula. The cells have 
 a laminated arrangement, and are essentially similar to those composing the 
 epidermis. The deepest layer of cells, which lie in contact with the papillae 
 of the matrix, are columnar in form and arranged perpendicularly to the surface; 
 those which succeed them are of a rounded or polygonal form, the more superficial 
 ones becoming broad, thin, and flattened, and so closely compacted as to make the 
 
 matrix of nail 
 
 FREE EDGE 
 
 ridges of 
 matrix 
 
 SULCUS OF 
 MATRIX 
 
 NAIL FOLD 
 
 CONCEALED MARGIN 
 
 Fig. 793. — The finger nail com- 
 pletely isolated, seen from the con- 
 vex side. (Toldt.) 
 
 NAIL WALL 
 
 Fig 794.— The matrix of 
 the nail or nail-bed, with the 
 nail-fold and nail-walls dis- 
 played by the removal of the 
 epidermic portion of the nail 
 or nail proper and the sur- 
 rounding epidermis. (Toldt.) 
 
 SULCUS OF 
 MATRIX 
 
 Fig. 795. — Matrix of the 
 nail with partly opened mar- 
 ginal groove of the nail-bed. 
 (Toldt.) 
 
 limits of each cell very indistinct. It is by the successive growth of new cells at 
 the root and under surface of the body of the nail that it advances forward and 
 maintains a due thickness, while, at the same time, the growth of the nail in the 
 proper direction is secured. As these cells in their turn become displaced by 
 the growth of new ones, they assume a flattened form, and finally become closely 
 compacted together into a firm, dense, horny texture. In chemical composition the 
 
THE HAIRS 
 
 1187 
 
 NECK OF 
 HAIR-FOLLICLE 
 
 INNE 
 ROOT-SHEATH 
 
 OUTER 
 ROOT-SHEATH 
 
 SEBACEOUS 
 GLAND 
 
 nails resemble the upper layers of the epidermis, containing, however, a some- 
 what larger proportion of carbon and sulphur (Mulder). 
 
 The Hairs (pi7i)(Figs. 784, 786, 788, 796, 797, and 798).— The hairs are peculiar 
 modifications of the epidermis, and consist essentially of the same structure as 
 that membrane. They are found on nearly every part of the surface of the body, 
 excepting the palms of the hands, soles of the feet, the vermilion borders of the 
 lips, the dorsal surfaces of the phalanges, the nipples, the inner surface of the 
 prepuce, and the glans penis. Hairs include hairs of the head (ca'pilla) ; of the eye- 
 brows (supercilia) ; of the beard (barba) ; of the ears (tragi) ; of the nostrils (vibrissae) ; 
 the oyelashes (cilia) ; hairs of the axilla (hirci) ; pubes (pubes) ; and the small hairs 
 of the skin or woolly hairs (lanugo). 
 They vary much in length, thick- 
 ness, and color in different parts of 
 the body and in different races of 
 mankind. In some parts, as in the 
 skin of the eyelids, they are so short 
 as not to project beyond the follicles 
 containing them; in others, as upon 
 the scalp, they are of considerable 
 length; again, in other parts, as the 
 eyelashes, the hairs of the pubic re- 
 gion, and the whiskers and beard, 
 they are remarkable for their thick- 
 ness. Straight hairs are stronger 
 than curly hairs, and present on 
 transverse section a cylindrical or 
 oval outline; curly hairs, on the 
 other hand, are flattened. The hairs 
 are usually oblique to the surface 
 from which they arise (Fig. 784). 
 Their direction depends upon the 
 region from which they spring, being 
 fairly regular in certain regions. 
 Thus are formed hair-streams (flu- 
 mina pilonim) and hair-whirlpools 
 (vortices pilorum). 
 
 A hair consists of the root, the 
 part implanted in the skin; the shaft 
 or stem, the portion projecting from 
 its surface; and the point. 
 
 The Root of the Hair (radix pili) 
 
 nrp'^pnts nt it« pvfrpmi+v a KiilKr^iic Fig. 796.— A hair of the head still in the course of growth, 
 presents ai us exiremiiy a DUIDOUS with hair-bulb in longitudinal section (Toldt.) 
 
 enlargement, the hair-bulb (bulbus 
 
 pili) (Figs.786 and 796) , which is whiter in color and softer in texture than the shaft, 
 and is lodged in a follicular involution of the epidermis called the hair-follicle (folli- 
 culus pili) (Figs. 784 and 788). When the hair is of considerable length the follicle 
 extends into the subcutaneous cellular tissue (Fig. 786). The hair-follicle com- 
 mences on the surface of the skin with a funnel-shaped opening, and passes inward 
 in an oblique or curved direction — the latter in curly hair — to become dilated at 
 its deep extremity or fundus (fundus folliculi pili), where it corresponds with the 
 bulbous condition of the hair which it contains. It has opening into it, near its 
 free extremity, the orifices of the ducts of one or more sebaceous glands (Figs. 
 786, 788, 796, and 797). At the bottom of each hair-follicle is a small conical, 
 vascular eminence or papilla, the hair-papilla (papilla pili) (Figs. 796 and 797), 
 
 OUTER 
 FIBROUS LAYER 
 
 INNER 
 FIBROUS LAYER 
 
 FUNDU 
 I-IAIR-FOLLI 
 
1188 
 
 THE ORGANS OF SPECIAL SENSE 
 
 similar in every respect to the papillae found upon the surface of the skin ; it is 
 continuous with the dermic layer of the follicle, is highly vascular, and is prob- 
 ably supplied with nervous fibrils. In structure the hair-follicle consists of two 
 coats— an outer or dermic, and an inner or epidermic (Figs. 796 and 798). 
 
 The Outer or Dermic Coat is formed mainly of fibrous tissue; it is continuous 
 with the corium, is highly vascular, and is supplied by numerous minute nervous 
 filaments. It consists of three layers. The most internal, the cuticular lining 
 of the follicle, consists of a hyaline basement-membrane, the hyaline layer, having 
 a glassy, transparent appearance, which is well marked in the larger hair-follicles,. 
 but is not very distinct in the folUcles of minute hairs. It is continuous with the 
 basement-membrane of the surface of the corium. External to this is the inner 
 fibrous layer, a compact layer of fibres and spindle-shaped cells arranged circularly 
 around the follicle. This layer extends from the bottom of the follicle as high as 
 the entrance of the ducts of the sebaceous glands. Externally is the outer fibrous 
 layer, a thick layer of connective tissue, arranged in longitudinal bundles, forming 
 a more open texture and corresponding to the reticular part of the corium. In this 
 are contained the blood-vessels and nerves. 
 
 CPIOERMIS.— ' 
 
 CORIUM- % 
 
 SUBCUTANEOUS '^' 
 AREOLAR TISSUE 
 
 RETINACULA 
 OF SKIN 
 
 OCC I PITO- FRONTAL 
 APONEUROSIS 
 
 ARRECTOR 
 PILI MUSCLE 
 
 SEBACEOUS 
 
 GLAND 
 
 i^ SUDORIFEROUS 
 GLAND 
 
 — HAIR-FOLLICLE 
 
 ROOT 
 
 HAIR-KNOB 
 ; HAIR-BULB 
 
 p; PAPILLA 
 OF HAIR 
 
 Fig. 797. — Vertical section through the skin of the head. The hair.s of the head in longitudinal section. (Toldt.) 
 
 The Inner or Epidermic Layer is closely adherent to the root of the hair, so that 
 when the hair is plucked from its follicle this layer most commonly adheres 
 to it and forms what is called the root-sheath. It consists of two strata, named 
 respectively the outer and inner root-sheaths; the former of these corresponds with 
 the Malpighian layer of the epidermis, and resembles it in the rounded form and 
 soft character of its cells; at the bottom of the hair-follicle these cells become con- 
 tinuous with those of the root of the hair. The inner root-sheath consists of a 
 delicate cuticle next the hair, composed of a thin layer of imbricated scales having 
 a downward direction, so that they fit accurately over the upwardly directed 
 imbricated scales of the hair itself; then of one or two layers of horny, flattened 
 nucleated cells, known as Huxley's layer; and finally of a single layer of horny 
 oblong cells without visible nuclei, called Henle's layer. 
 
 The hair-follicle contains the root of the hair, which terminates in a bulbous 
 extremity, and is excavated so as to exactly fit the papilla from which it grows. 
 The bulb is composed of polyhedral epithelial cells, which as they pass upward 
 into the root of the hair become elongated and spindle-shaped, except some in the 
 centre which remain polyhedral. Some of these latter cells contain pigment- 
 
THE HAIRS 
 
 1189 
 
 granules, which give rise to the color of the hair. It occasionally happens that 
 these pigment-granules completely fill the cells of the medullary substance in 
 the centre of the bulb, which gives rise to the dark tract of pigment often found, 
 of greater or less length, in the axis of the hair. 
 
 The Stem or Shaft of the Hair (scapus pill) (Fig. 796), consists of a central pith or 
 medulla, the fibrous part of the hair, and the true cuticle externally. The medulla 
 (substantia medullaris pili) occupies the centre of the shaft and ceases toward the 
 point of the hair. It is usually wanting in the fine hairs covering the surface of 
 the body, and commonly in those of the head. It is found in the shafts of all thick 
 hairs and in the deeper parts of the root of most hairs. It is more opaque and 
 deeper colored when viewed by transmitted light than the fibrous part; but when 
 viewed by reflectefl light it is white. It is composed of rows of polyhedral cells, 
 which contain granules of eleidin and frecjuently air-bubbles. The fibrous portion 
 or cortical substance of the hair (substantia corticalis pili) constitutes the chief part 
 of the shaft; its cells are elongated and unite to form flattened fusiform fibres. 
 Between the fibres are found minute spaces which contain either pigment-granules 
 in dark hair or minute air-bubbles in white hair. In addition to this there is also a 
 
 CUTICLE OF 
 ROOT SHEATH '^ 
 
 INNER 
 FIBROUS -«^' 1 
 
 OUTER / 
 
 FIBROUS ■ 
 
 LAYER h 
 
 OOT-SHEATH 
 
 CR 
 ROOT-SHCATH 
 
 ^ MEDULLARY 
 SUBSTANCE 
 
 x FIBROUS 
 SUBSTANCE 
 
 Fig. 798 — \ moustache hair with its hair-follicle in transver«e section. (Toldt.) 
 
 diffused pigment contained in the fibres. The cells which form the outer hair mem- 
 brane or true cuticle (cuticula pili) consist of a single layer which surrounds those of 
 the fibrous part; they are converted into thin, flat scales, having an imbricated 
 arrangement. 
 
 Connected with the hair-follicles are minute bundles of involuntary muscular 
 fibres, termed arrectores pili (mm. arredores pilorum) (Figs. 784 and 796). They 
 arise from the superficial layer of the corium, and are inserted into the outer 
 surface of the hair-follicle, below the entrance of the duct of the sebaceous gland. 
 They are placed on the side toward which the hair slopes, and by their action 
 elevate the hair.* When the hair is elevated a depression forms over the seat of 
 origin of the muscle, and the parts about the hair are elevated. This condition is 
 known as goose-skin. It is probable that the contraction of these muscles aids in 
 emptying sebaceous glands. 
 
 Blood-vessels and Nerves (Fig. 786). — A hair-follicle possesses a rich network of 
 capillaries about the hyaline membrane, and capillary loops pass to the papilla. 
 
 ' Arthur Thomson suggests that the contraction of these muscles on follicles which contain weak, flat hairs 
 will tend to produce a permanent curve in the follicle, and this curve will Be impressed on the hair which is 
 moulded within it, so that the hair, on emerging through the skin, will be curled. Curved hair-follicles are 
 characteristic of the scalp of the Bushman. — I'^d. of loth English edition. 
 
1190 THE ORGANS OF SPECIAL SENSE 
 
 We have little knowledge as to nerve-terminations of the human hair. "In other 
 mammals the nerves end below the sebaceous glands. Medullated fibres lose 
 their medullary sheaths, divide, and penetrate to the hyaline membrane. Here 
 some of the branches encircle the hair, while others end freely on the hyaline 
 membrane as naked axis-cylinders. These branch regularly and run parallel to 
 the long axis of the hair."^ 
 
 The Sudoriferous or Sweat-glands {glandulae siidoriferae) (Figs. 783, 7S4, 786, 
 788, and 797). — The sudoriferous or sweat-glands are the organs by which a large 
 portion of the aqueous and gaseous materials is excreted by the skin. They are 
 found in almost every part of this structure, being absent on the red border of the 
 lips, the glans penis, and inner surface of the prepuce. On the eyelids they are some- 
 what modified, and are called ciliary glands {glandulae ciliares [Molli]) ; about the 
 anus they are extremely large, and are called circumanal glands (glandulae circum- 
 anales). The sweat-glands are situated in small pits below the under surface of the 
 corium, or, more frequently, in the subcutaneous areolar tissue, surrounded by a 
 quantity of adipose tissue. They are small, lobular, reddish bodies, consisting of 
 a single convoluted tube, from which the efferent duct {ductus sudor if eru.'i) proceeds 
 upward through the corium and cuticle. The duct in the corium has true walls; in 
 the epidermis it has not individual walls, but is simply an epidermic tube. It 
 becomes somewhat dilated at its extremity, and opens on the surface of the cuticle by 
 an oblique valve-like aperture (poru^ sudorijerus). The duct, as it passes through 
 the epidermis, presents a spiral arrangement, being twisted like a corkscrew, in 
 those parts where the epidermis is thick; where, however, the epidermis is thin, the 
 spiral arrangement does not exist. In the superficial layers of the corium the duct 
 is straight, but in the deeper layers it is convoluted or even twisted. The spiral 
 course of these ducts is especially distinct in the thick cuticle of the palm of the 
 hand and sole of the foot. The size of the glands varies. They are especially 
 large in those regions where the flow of perspiration is copious, as in the 
 axillae, where they form a thin, mamillated layer of a reddish color, which 
 corresponds exactly to the situation of the hair in this region ; they are large also in 
 the groin. Their number varies. They are most numerous on the palm of the hand, 
 presenting, according to Krause, 2800 orifices on a square inch of the integument, 
 and are rather less numerous on the sole of the foot. In both of these situations 
 the orifices of the ducts are exceedingly regular, and open on the curved surface 
 ridges. In other situations they are more irregularly scattered, but the number 
 in a given extent of surface presents a fairly uniform average. In the neck and 
 back they are least numerous, their number amounting to 417 on the square inch 
 (Krause). Their total number is estimated by the same writer at 2,381,248, and, 
 supposing the aperture of each gland to represent a surface of ^ of a line in 
 diameter, he calculates that the whole of these glands would present an evap- 
 orating surface of about eight square inches. Each gland consists of a single 
 tube intricately convoluted, terminating at one end by a blind extremity, and 
 opening at the other end upon the surface of the skin. 
 
 The wall of the tubercle of the secreting coil is lined with cubical epithelial 
 cells, external to these is a layer of smooth muscle-cells, and more externally a 
 layer of connective tissue, the membrana propria. The duct in the corium, in 
 contrast to the secreting coil, has no layer of muscle-cells, but instead a second 
 layer of epithelial cells covered by connective tissue. As previously stated, the 
 duct becomes spiral in the epidermis, its own wall disappears, and the channel 
 is bounded by epidermic cells. 
 
 Blood-vessels and Nerves. — The blood-vessels are branches from the subcuta- 
 neous vessels and the arterial plexus of the deep part of the corium. Numerous 
 
 ' Histology and Microscopic Anatomy. By Dr. Ladislaus Szymonowicz. Translated and edited by John 
 Bruce MacCallum, M.D. 
 
THE SEBACEOUS GLANDS 1191 
 
 non-medullated nerve-fibres lie upon the membrana propria of a sweat-gland. 
 From them fibrils pass inward and terminate by end-bulbs upon the cells of the 
 gland. 
 
 The Sebaceous Glands (glandulae sebaceae). — The sebaceous glands are small, 
 sacculated, glandular organs, lodged in the substance of the corium. They are 
 found in most parts of the skin, and are usually connected with hair-follicles. 
 This connection is so common that they are sometimes called hair-follicle glands. 
 They are found in some regions which are devoid of hairs — the vermilion borders 
 of the lips, the labia minora, the glans penis, and prepuce. These glands are espe- 
 cially abundant in the scalp and face; they are also very numerous around the 
 apertures of the anus, nose, mouth, and external ear; but are wanting in the palms 
 of the hands and soles of the feet. Each gland consists of a single duct, more or 
 less capacious, which terminates in a cluster of small secreting pouches or saccules. 
 The sacculi connected with each duct vary, in number, as a rule, from two to five, 
 but in some instances may be as many as twenty. They are composed of a trans- 
 parent, colorless membrane, enclosing a number of epithelial cells. Those of 
 the outer or marginal layer are small and polyhedral, and are continuous with 
 the lining cells of the duct. The remainder of the sac is filled with larger cells, 
 containing fat, except in the centre, where the cells have become broken up, leav- 
 ing a cavity containing their debris and a mass of fatty matter, which constitutes 
 the sebaceous secretion. The orifices of the ducts open most frequently into the 
 hair-follicles, but occasionally upon the general surface, as in the labia minora and 
 the free margins of the lips. On the nose and face the glands are of large size, 
 distinctly lobulated, and often become much enlarged from the accumulation of 
 pent-up secretion. The largest sebaceous glands are those found in the eyelids — 
 the Meibomian glands. 
 
THE ORGANS OF DIGESTION. 
 
 THE Apparatus for the Digestion of the Food (apparatus digestorius) consists 
 of the alimentary canal and of certain accessory organs. 
 
 THE ALIMENTARY CANAL. 
 
 The alimentary canal is a musculo-membranous tube, about thirty feet in 
 length, extending from the mouth to the anus, and lined throughout its entire 
 extent by mucous membrane. It has received different names in the various parts 
 of its course; at its commencement, the mouth, we find provision made for the 
 mechanical division of the food {mastication), and for its admixture with a fluid 
 secreted by the salivary glands (in salivation) ; beyond this are the pharynx and 
 the oesophagus, the organs which convey the food (deglutition) into that part of 
 the alimentary canal, the stomach, in which the principal chemical changes occur, 
 and in which the reduction and solution of the food take place; in the small intes- 
 tines the nutritive principles of the food, the chyle, are separated, by its admixture 
 with the bile, pancreatic and intestinal fluids, from that portion which passes into 
 ihe large intestine, most of which is expelled from the system. 
 
 
 Alimentary Canal. 
 
 Duodenum, 
 
 Mouth. 
 
 Small intestine 
 
 ' Jejunum. 
 
 Pharynx. 
 
 Oesophagus. 
 
 Stomach. 
 
 Large intestine 
 
 I Ileum. 
 
 Caecum. 
 ' Colon. 
 , Rectum. 
 
 Teeth. 
 
 Accessory Organs. 
 
 
 
 ( Parotid. 
 
 Liver. 
 
 Salivary glands 
 
 ' Submaxillary. 
 , Sublingual. 
 
 Pancreas. 
 Spleen. 
 
 THE MOUTH, ORAL OR BUCCAL CAVITY (CAVUM ORIS). 
 
 The mouth is placed at the commencement of the alimentary canal; it is a 
 nearly oval-shaped cavity, in which the mastication and insalivation of the food 
 take place (Figs. 799, 818, and 824). 
 
 The aperture of the mouth (rima oris) is bounded by the lips. The angle of the 
 mouth (angulus oris) is formed on each side by the meeting of the upper and 
 lower lips (commissura labiorum). When at rest with the lips in contact, the rima 
 is a slightly curved line. Every movement which the lips make alters the shape 
 of the rima. When the mouth is closed the floor and roof are usually in contact 
 and its sides are approximated to the dental arches. The mouth consists of two 
 
 (1193) 
 
1194 
 
 THE ORGANS OF DIGESTION 
 
 SALtVARY 
 GLANDS 
 
 PHARYNX 
 
 STOMACH 
 
 PANCREAS 
 
 parts: an outer, smaller portion, the vestibule, and an inner, larger part, the cavity 
 
 proper of the mouth. 
 
 The Vestibule (vestibulum oris). — The vestibule is a slit-like space, bounded 
 
 in front and laterally by the Hps and cheeks; behind and internally by the gums 
 
 and teeth. Above and below it is limited 
 by the reflection of the mucous membrane 
 from the lips and cheeks to the gum cover- 
 ing the upper and lower alveolar arch re- 
 spectively. It receives the secretion from the 
 parotid glands, and communicates, when the 
 jaws are closed, with the cavum oris by an 
 aperture on each side behind the wisdom 
 teeth. 
 
 The Cavity of the Mouth Proper (cavum 
 oris 'propriu7n). — The cavity of the mouth 
 proper is bounded laterally and in front 
 by the alveolar arches with their contained 
 teeth ; behind it communicates with the 
 pharynx by a constricted aperture termed 
 the isthmus faucium. It is roofed in by the 
 hard and soft palate. The greater part of the 
 floor is formed by the tongue, the remainder 
 being completed by the reflection of the mu- 
 cous membrane from the sides and under 
 surface of the tongue to the gum lining the 
 inner aspect of the mandible. It receives 
 the secretion from the submaxillary and 
 sublingual glands. 
 
 The Mucous Membrane. — The mucous 
 membrane lining the mouth is continuous 
 with the integument at the free margin of 
 the lips and with the mucous lining of the 
 pharynx behind; it is of a rose-pink tinge 
 
 during life, and very thick where it covers the hard parts bounding the cavity. 
 
 It is covered by stratified epithelium. 
 
 SM-ALL 
 INTESTINE 
 
 _ ANUS 
 Fig. 799. — Diagram of the alimentary tube and 
 its appendages. (Testut.) 
 
 The Lips (Labia Oris). 
 
 The lips are two fleshy folds which surround the orifice of the mouth, formed 
 externally by integument and internally by mucous membrane, between which are 
 found the Orbicularis oris muscle (Fig. 263) , the coronary vessels (Fig. 395) , some 
 nerves (Fig. 395), areolar tissue, and fat, and numerous small labial glands. 
 The upper Up is called the labium superius; the lower lip is called the labium 
 inferius. The inner surface of each lip is connected in the middle line to the gum 
 of the corresponding jaw by a fold of mucous membrane, the frenulum (frenulum 
 labii swperioris and frenulum labii inferioris). The frenulum labii superioris is 
 the larger of the two. On each side, external to the angle of the mouth, the lips 
 become continuovis (commissura lahiorum). 
 
 The Labial Glands (glandulae lahiales) (Fig. 395). — The labial glands are situated 
 between the mucous membrane and the Orbicularis oris muscle around the orifice 
 of the mouth. They are rounded in form, about the size of small peas, and their 
 ducts open by minute orifices upon the mucous membrane. In structure they 
 resemble the salivary glands. 
 
THE TEETH 1195 
 
 The Cheeks (Buccae). 
 
 The cheeks form the sides of the face and are continuous in front with the Hps. 
 They are composed externally of integument, internally of mucous membrane, 
 and between the two of a muscular stratum, besides a large quantity of fat, areolar 
 tissue, vessels, nerves, and buccal glands. 
 
 The Mucous Membrane. — ^The mucous membrane lining the cheek is reflected 
 above and below upon the gums, where its color becom-es lighter; it is continuous 
 behind with the lining membrane of the soft palate. Opposite the second molar 
 tooth of the upper jaw is a papilla, the summit of which presents the aperture of 
 the duct of the parotid gland {ductus parotideus [Sienonis]) (Fig. 824.) The prin- 
 cipal muscle of the cheek is the Buccinator, but numerous other muscles enter into 
 its formation — viz., the Zygomatici, Risorius Santorini, and Platysma myoides. 
 
 The Buccal Glands (glandulae huccales). — The buccal glands are placed in the 
 submucous tissue between the mucous membrane and Buccinator muscle; they 
 are similar in structure to the labial glands, but smaller. Four or five glands of 
 larger size than the previously mentioned glands are placed beneath the mucous 
 membrane in the neighborhood of the last molar tooth. They are called the 
 molar glands (glandidae molar es). Their ducts open into the mouth opposite the 
 last molar tooth. 
 
 The Gums (Gingiva). 
 
 The gums are composed of a dense fibrous tissue closely connected to the 
 periosteum of the alveolar processes and surrounding the necks of the teeth. They 
 are covered by smooth and vascular mucous membrane, which is remarkable for 
 its limited sensibility. Around the necks of the teeth this membrane presents 
 numerous fine papillae; and from this point it is reflected into the alveolus, where 
 it is continuous with the periosteal membrane lining that cavity. 
 
 The Teeth (Dentes). 
 
 The human subject is provided with two sets of teeth, which make their appear- 
 ance at different periods of life. The first set appear in childhood, and are called 
 the temporary, deciduous or milk teeth. The second set are named permanent. 
 
 The temporary teeth are twenty in number — four incisors, two canine, and four 
 molars in each jaw (Figs. 800 and 817). 
 
 The permanent teeth are thirty-two in number — four incisors (two central and two 
 lateral), two canines, four bicuspids, and six molars in each jaw (Figs. 802 and 806). 
 
 General Characters (Fig. 807). — Each tooth consists of three portions; the 
 crown or body {corona dentis), projecting above the gum; the root or fang {radix 
 dentis), entirely concealed within the alveolus; and the neck (collum dentis), the 
 constricted portion, between the root and crown. 
 
 Surfaces. — The surfaces of a tooth are named thus: that which comes in con- 
 tact with the teeth of the opposite jaw is the grinding or masticating surface {fades 
 masticatoria) ; that which touches the next tooth in the same row is the contact 
 surface {fades contactus). That surface which is toward its predecessor is called 
 the proximal surface (in incisors and canines, fades iiiedialis; in molars and pre- 
 molars, fades anterior). That surface which is toward its successor is called the 
 distal surface (in incisors and canines, fades lateralis; in molars and premolars, 
 fades 'posterior). That which looks toward the lips and cheek is the labial or 
 buccal surface {fades labialis). That toward the tongue is the lingual surface 
 {fades lingualis). In part this method of designation applies to the roots as well 
 as to the crowns of teeth. 
 
1196 
 
 THE ORGANS OF DIGESTION 
 
 The Roots of the Teeth.— The roots of the teeth are firmly implanted within the 
 sockets or alveoli of the jaws {alveoli deniales) (see pp. 109 and 124). These depres- 
 sions are lined with periosteum, called the pericementum, which is reflected on to the 
 tooth at the point of the root and covers it as far as the neck. This is the root 
 membrane {'periosteum alveolar e). At the margin of the alveolus the periosteum 
 becomes continuous with the fibrous structure of the gums. 
 
 Right upper. 
 
 Fia. 800. — Deciduous teetli. Left side. 
 
 Fig. 801. — Deciduous teeth. Lingual view. 
 
 Temporary, Deciduous or Milk Teeth {denies decidui) (Figs. 800, 801, and 817). 
 — The temporary or milk teeth are smaller, but resemble in form those of the per- 
 manent set. The neck is more marked, owing to the greater degree of convexity 
 of the labial and lingual surfaces of the crown. The hinder of the two temporary 
 molars is the largest of all the deciduous teeth, and is succeeded by the second 
 bicuspid. The first upper molar has only three cusps — two labial, one lingual; the 
 second upper molar has four cusps. The first lower molar has four cusps; the 
 second lower molar has five. The roots of the temporary molar teeth are smaller 
 and more diverging than those of the permanent set, but in other respects bear a 
 strong resemblance to them. 
 
 Fig. 802. — Permanent teeth, right side. (Burchard.) 
 
 Permanent Teeth {denies permanentes) (Figs. 802, 803, 804, and 806). The 
 Incisors {denies incisivi). — The incisors or cutting teeth are so named from their 
 presenting a sharp cutting edge, adapted for incising the food. They are eight in 
 number, and comprise the four front teeth in each jaw. 
 
 The crown is directed almost vertically and is spade-like in form ; it has the form 
 of a truncated cone whose top has been compressed into a sharp horizontal cutting 
 
THE TEETH 
 
 1197 
 
 edge. Before being subjected to attrition this edge presents three small elevations. 
 The labial surface is convex, and marked by free longitudinal ridges extending 
 from the edge tubercles toward the neck of the tooth. The lingual surface is con- 
 cave, and is marked by two marginal ridges extending from an encircling ridge 
 at the neck to the angles of the cutting edge of the tooth. The ridge at the neck 
 is termed the cingulum or basal ridge. The mesial and distal surfaces are triangular, 
 the apex of the triangle being at the cutting edge. The neck of the tooth is 
 constricted. The root is long, single, and has the form of a transversely flattened 
 cone, thicker before than behind. The root may be curved. 
 
 The Incisors of the Upper Jaw are altogether larger and stronger than those of 
 the lower jaw, the central incisors being larger and flatter than the lateral incisors. 
 They are directed obliquely downward and forward. 
 
 The Incisors of the Lower Jaw are smaller and flatter than the upper, and the 
 elevations upon their lingual faces are not marked. The two central are smaller 
 than the two lateral incisors, being the smallest of all the teeth. The roots of these 
 teeth are flattened laterally. 
 
 I 
 
 Fig. 803. — Right half of upper jaw (from below), 
 with the corresponding teeth. The letters and numbers 
 point to the classes of teeth and the numbers in 
 classes. 
 
 Fig. 804. — Right half of lower jaw, with the cor- 
 responding teeth. The letter and numbers point to 
 the various cusps or their modifications on the dif- 
 ferent teeth. (Burchard.) 
 
 The Canine Teeth or Cuspidati {denies canini). — The canine teeth are four in 
 number, two in the upper, two in the lower jaw — one being placed distal to each 
 lateral incisor. They are larger and stronger than the incisors, especially in the 
 roots, which are deeply implanted and each causes a well-marked prominence 
 of the process at the place of insertion. 
 
 The crown is large, of spear-head form, and its very convex labial surface is 
 marked by three longitudinal ridges. The concave lingual surface is also marked 
 by three ridges which unite at a basal ridge. The point or cusp is longer than in 
 the other teeth, and is the point of division between a short mesial and a long 
 distal cutting edge. These two edges form an obtuse angle with each other. 
 
 The root is single, oval, or elliptical on transverse section, and is longer and more 
 prominent than the roots of the incisors. 
 
 The Upper Canines or cuspids, vulgarly called the eye teeth, are larger and longer 
 than the two lower, and in occlusion are distal to them to the extent of half the 
 width of the crown. 
 
 The Lower Canines, vulgarly called the stomach teeth, have the general form of 
 the upper cuspids, but their lingual surfaces are much more flattened, owing to 
 
1198 THE ORGANS OF DIGESTION 
 
 the absence of the elevations marking the upper. Their roots are more flattened 
 and may be bifid at their apices. 
 
 The Bicuspid Teeth or the Premolars {denies fremolares). — The bicuspid teeth 
 are eight in number, four in each jaw; they are placed distal to the cuspid teeth, 
 two upon each side of the jaw. They are double cuspids in form. 
 
 The crown is surmounted by two cusps, one buccal and one lingual, separated 
 by a groove, the buccal being more prominent and larger than the lingual. The 
 lower bicuspids are not truly bicuspid, the first having but a primitive lingual cusp, 
 the second having the lingual cusp divided into two sections— t. e., it is usually 
 tricuspid. The necks of the teeth are oval; the roots are single and laterally com- 
 pressed, that of the first upper bicuspid being frequently bifid. The first upper 
 bicuspid is usually the largest of the series. The roots of the lower bicuspids are 
 less compressed and more rounded. 
 
 The Molar Teeth, the Multicuspidati or Grinders (denies molares). — The molar 
 teeth are the largest and strongest teeth of the denture. They are adapted by 
 their forms for the crushing and grinding of the food. They are twelve in number, 
 six in each jaw, three being placed posterior to each second bicuspid. 
 
 The crowns are cuboidal in form, are convex buccally and lingually; they are 
 flattened mesially and distally. They are formed by the fusion of three primitive 
 cuspids in the upper and four in the lower. To these are added in the first and 
 second upper molars a disto-lingual tubercle, and in the first and third molars of 
 the lower jaw a disto-buccal tubercle. The unions of the primitive forms are 
 marked by sulci. The necks of these teeth are large and rhomboidal in form. 
 The roots of the upper molars are three in number — one large lingual or palatal 
 root, and two smaller buccal roots. In the lower molars, two roots are found, a 
 mesial and a distal, each of which is much flattened from before backward. 
 
 The First Molar Teeth are the largest of the dental series; they have four cusps 
 on the upper and five in the lower — three buccal and two lingual. 
 
 The Second Molars are smaller; the crowns of the upper are compressed until the 
 disto-lingual cusp is reduced. The crowns of the lower are almost rectangular, 
 with a cusp at each angle. 
 
 The Third Molars are called the wisdom teeth or dentes sapientae {denies seroiini), 
 from their late eruption; they have three cusps upon the upper and five upon the 
 lower. The three roots of the upper are frequently fused together, forming a 
 grooved cone, which is usually curved backward. The roots of the lower, two 
 in number, are compressed together, and curve backward. 
 
 Arrangement of the Teeth.^ — The human teeth are arranged in two parabolic 
 arches, the upper row or arch {arcus dentalis superior) being larger, its teeth over- 
 lapping the lower row or arch {arcus dentalis inferior). The average distance 
 between the centres of the condyles of the inferior maxillary bones is about four 
 inches, which is also the distance from either of these points to the line of junction 
 between the lower incisor teeth. Whether the jaw be large or small, the equilateral 
 triangle indicated is included in it; the range of size is between three and one-half 
 and four and one-half inches. 
 
 Owing to the smaller sizes of the lower incisors, the teeth of the lower jaw are 
 each one-half a tooth in advance of its upper fellow, so that each tooth of the dental 
 series has two antagonists, with the exception of the lower central incisors and 
 upper third molars (Figs. 805 and 806). 
 
 The grinding faces of the upper bicuspids and molars curve progressively upward 
 and point outward, the first molar being at the lowest point of the curve, the third 
 molar at the highest. The curve of the lower dental arch is the reverse, the first 
 molar at its deepest part, the third molar at its extremity. The greater the depth 
 
 • After Dr. W. G. A. Bonwill. 
 
THE TEETH 
 
 1199 
 
 to which the upper incisors overlap the lower, the more marked this curve and 
 the more pointed are the cusps of the grinding teeth. 
 
 Fig. 805. — View of teeth in situ, with the external plates of the alveolar processe.s removed. (Cryer.) 
 
 Fig. 806.— Front and side views of the teeth and jaws. (Cryer.) 
 
 The movement of the human mandible is forward and downward, the resultant 
 of these directions being an oblique line, upon an average of 35 degrees from 
 the horizontal plane/ When the lower jaw is advanced until the cutting edges of 
 
 ' W. E. Walker, Dental Cosmos, 1896. 
 
1200 
 
 THE ORGANS OF DIGESTION 
 
 the incisors are in contact, the jaws are separated, but at the highest point of the 
 lower arch its third molar advances, and meets and rests upon a high point, the 
 second molar of the upper arch, and thus undue strain upon the incisors is obviated. 
 In the lateral movements of the mandible but one side is in effective action at 
 one time; the oblique positions of the cusps of the opposite teeth are such that 
 
 Fig. 807. — Vertical section of a molar tooth. 
 
 when either side is in action the other 
 is balanced at two or more points. 
 
 There is an anatomical correspond- 
 ence between the forms and arrange- 
 ment of the teeth, the form of the con- 
 dyle of the mandible, and the muscular 
 arrangement. Individuals who have 
 teeth with long cusps have the head of 
 the bone much rounded from before 
 backward, and have a preponderance 
 of the direct over the oblique muscles 
 of mastication, and vice versa; teeth 
 with short or no cusps are associated 
 with a flattened condyle and strong 
 oblique muscles. 
 
 Very great aberrations in the dental 
 arrangement are frequently followed by 
 accommodative changes in the heads of 
 the mandible. 
 
 Structure of the Teeth. The Dental 
 Pulp (pulpa dentis). — A longitudinal 
 section of a tooth will show the pres- 
 ence of a central chamber having the 
 general form of the crown of the tooth. 
 Processes of the chamber pass from its 
 body, one for each root and down each 
 root, and open at the apex by a minute 
 orifice. This cavity is known as the pulp-chamber or pulp-cavity (cavum dentis) 
 (Figs. 807 and 808) . The minute canal in each root is called the pulp-canal or root- 
 canal (canalis radicis dentis). The foramen at the apex of the root is the apical 
 foramen (foramen apicis dentis). The cavity contains a soft, vascular, and sensitive 
 organ called the dental pulp [pulpa dentis) . It is made up of fibrous cellular con- 
 nective tissue, the fibres of which are extremely fine, and contains numerous blood- 
 vessels and nerves, which enter by way of the apical foramina. It has not been 
 proved that there are lymphatics in the dental pulp, although some authors assert 
 that they exist (Wangermann and others). It seems to have been proved that the 
 spaces between the fibres of the pulp communicate with the lymphatic system. The 
 periphery of the pulp is bounded by a layer of cells arranged like columnar epithe- 
 lium, each cell sending one or more branched processes through the basic substance 
 
 Fig. 808. — Vertical section of a tooth in situ (15 
 diameters). C is placed in the pulp-cavity, opposite 
 the cervi.x or neck of the tooth ; the part above is tho 
 crown, that below is the root (fang). 1. Enamel with 
 radial and concentric markings. 2. Dentine with 
 tubules and incremental lines. 3. Cement or crusta 
 jietrosa, with bone corpuscles. 4. Dental periosteum. 
 5. Bone of lower jaw. 
 
THE TEETH 
 
 1201 
 
 of the dentine. These processes constitute the dentine fibres. Other processes come 
 off from the cells which pass in the direction of the pulp and surround it. The 
 cells at the periphery of the pulp are the 
 dentine -forming cells, the odontoblasts of Wal- 
 deyer. The blood-vessels break up into in- 
 numerable capillary loops which lie beneath 
 the layer of odontoblasts. The nerve-fibrils 
 break up into numberless non-medullary fila- 
 ments, which spread out beneath the odonto- 
 blasts, and probably send terminal filaments 
 to the extreme periphery of the pulp outside 
 the odontoblasts. 
 
 The matrix cells and their processes are 
 irregularly arranged in the body of the pulp, 
 but in the canal portion the fibrillae are in the 
 direction of the axis of the root. 
 
 The Solid Portion of the Tooth.— The sec- 
 tion will exhibit three hard tissues in a tooth : 
 one, the proper dental substance, forming the 
 greater mass of the tooth; hence its name tt onn i? a *• *u u 
 
 o \ Fig. 809. — From a ground-section through 
 
 dentine or ivory. The dentine upon the ex- the parts of a dentine, near the pulp, of a 
 
 , • 1 1 I 1 1 II 1 human canine tooth which has been impreg- 
 
 pOSed crown is sheathed by a layer called nated with pigment. The dental canallcuU are 
 
 7i , ,1 1 ,• !• .1 , • cut acro.ss and are joined together by side 
 
 the enamel ; the dentine or the root is en- branches, x 4oo. 
 
 closed in a distinct tissue, the cementum or 
 
 crusta petrosa ; both cementum and enamel are thinnest at the neck and thickest 
 
 upon their distal portions. 
 
 ~ i-A^/f^J^ 
 
 Fig. 810. — Longitudinal ground-section through the apex of a canine tooth from a three-and-a-half-year-okl 
 boy. The entrance of the dental canaliculi between the enamel prisms and the course taken by the latter are 
 shown. X 135. (Szymonowicz.) 
 
 76 
 
1202 
 
 THE OBGANS OF DIGESTION 
 
 The Ivory or Dentine (suhstantiae eburnea) (Figs. 808, 809, 810, and 811) forms 
 the principal mass of a tooth; in its central part is the cavity enclosing the pulp. It 
 is a modification of osseous tissue, from which it differs, however, in the fact that 
 it does not contain cells placed in cavities, but the cells lie in the periphery of the 
 pulp, against but not in the dentine. The dentine contains the processes of the 
 cells,' which are known as dental or dentinal fibres. On microscopic examination 
 it is' seen to consist of a number of minute wavy and branching tubes having 
 distinct parietes. They are called the dentinal tubuli or dental canals, and are 
 embedded in a dense homogeneous substance, the intertubular tissue. 
 
 The dentinal tubuli (canaliculi dentales) (Fig. 811) are placed parallel with one 
 another, and open at their inner ends into the pulp-cavity. In their course to the 
 periphery they present two or three curves, and are twisted on themselves in a spiral 
 direction. The direction of these tubes varies; they are vertical in the upper por- 
 tion of the crown, oblique in the 
 neck and upper part of the root, 
 and toward the lower part of the 
 root they are inclined downward. 
 The tubuli, at their commence- 
 ment, are about -^-^-^ of an inch in 
 diameter; in their course they di- 
 vide and subdivide dichotomously, 
 so as to give to the cut surface of 
 the dentine a striated appearance. 
 From the sides of the tubes, espe- 
 cially in the root, ramifications of 
 extreme minuteness are given off, 
 which join together in loops in the 
 intertubular substance, or termin- 
 ate in small dilatations, from which 
 branches are given off. Near the 
 pulp the lateral branches are few 
 and are almost at right angles to 
 the canals. Nearer the periphery 
 the lateral branches are more nu- 
 merous, and they come off at 
 acute angles. The terminations of 
 the chief canals at the periphery 
 vary. In the crown they break up 
 into branches like fingers just be- 
 neath the enamel. Some of these 
 finger-like branches leave the den- 
 tine and enter the cement substance between enamel prisms. The majority of 
 the chief canals end in blind extremities at the margin of the enamel and do not 
 enter this structure. In the lower portion of the tooth the chief canals do not 
 emerge from the dentine, but end at the margin of the cement in blind extremities. 
 They may reach the spaces of the granular sheath. Near the periphery of the 
 dentine of the crown the finer ramifications of the tubuli pass through a layer of 
 irregular branched spaces which communicate with each other. These are called 
 the interglobular spaces of Gzermak (spatia interglohularia) (Fig. 811, /). These 
 spaces are gaps in the dentine due to failure of calcification and are filled with 
 uncalcified dentine. The outer part of the dentine in the lower portion of the 
 tooth contains a layer of interglobular spaces known as the granular layer or 
 granular sheath of Tomes. The dentinal tubuli have comparatively thick walls, 
 and contain slender cylindrical prolongations from the processes of the cells of 
 
 Fig. 811. — Ground-section through the root of a human 
 premolar. D, dentine ; K, cement corpusebs ; 0, osteoblasts ; 
 Ep., remains of Hertwig's epithelial sheath, 200 diameters ; 
 J, interglobular spaces. (Riise.) 
 
THE TEETH 
 
 1203 
 
 the pulp-tissue already mentioned, and first described by Mr. Tomes and named 
 Tomes's fibres or dentinal fibres. These dentinal fibres are analogous to the soft 
 contents of the canaliculi of bone. Between Tomes's fibres and the ivory around 
 the canals there is a tissue which is markedly resistant to the action of acids — the 
 dentinal sheath of Neumann. 
 
 The intertubular substance or tissue is translucent and contains the chief part 
 of the earthy matter of the dentine. After the earthy matter has been removed 
 by steeping a tooth in weak acid the animal basis remaining may be torn into 
 laminae which run parallel with the pulp-cavity across the direction of the tubules. 
 These laminae show the method of growth to be by deposition of successive strata 
 of dentine. Fibrils have been found in tho matrix of the intertubular substance, 
 and are probably continuous with the dentinal fibres of Tomes. In a dry tooth a 
 section of dentine often displays a series of lines — the incremental lines of Salter — 
 which are parallel with the laminae above mentioned. These lines are caused by 
 two facts: (1) The imperfect calcification of the dentinal laminae immediately 
 adjacent to the line. (2) The drying process, which reveals these defects in the 
 calcification. These lines are wide or narrow according to the number of laminae 
 involved, and along their course, in consequence of the imperfection in the calci- 
 fying process, little irregular cavities are left, which are the interglobular spaces 
 already referred to. They have received their name from the fact that they are 
 surrounded by minute nodules or globules of dentine. Other curved lines may 
 be seen parallel to the surface. These are the concentric lines of Schreger, and are 
 due to the optical effect of simultaneous curvature of the dentinal tubules. 
 
 Fig. 812. — Enamel prisms (350 diameters). A, fragments and single fibres of the enamel isolated by the action 
 of hydrochloric acid, li, surface of a small fragment of enamel, showing the hexagonal ends of the fibres. 
 
 Chemical Composition. — According to Berzelius and Bibra, dentine consists 
 of twenty-eight parts of animal and seventy-two of earthy matter. The animal 
 matter is resolvable by boiling into gelatin. The earthy matter consists of phos- 
 phate and carbonate of calcium, with a trace of fluoride of calcium, phosphate of 
 magnesia, and other salts. 
 
 The Enamel (substantia adamantina) (Figs. 808, 810, and 812) is the hardest and 
 most compact part of a tooth, and forms a thin crust over the exposed part of 
 the crown as far as the commencement of the root. It is thickest on the grind- 
 ing surface of the crown until worn away by attrition, and becomes thinner toward 
 the neck. It consists of a congeries of minute hexagonal rods, columns, or prisms 
 known as enamel fibres or enamel prisms (prismata adamantina) (Fig. 812). In 
 general, they lie parallel with one another, resting by one extremity upon the 
 dentine, which presents a number of minute depressions for their reception, and 
 
1204 THE ORGANS OF DIGESTION 
 
 forming the free surface of the crown by the other extremity. There are occa- 
 sional collections of prisms which run diagonally. The prisms are directed 
 vertically on the summit of the crown, horizontally at the sides; they are about 
 the ysVo" of ^^ ^'^^'^^ ^" diameter, and pursue a more or less wavy course. By 
 reflected light radial striations are visible. These are Schreger's lines, and are 
 due to the fact that the prisms take an undulatory course and those of two layers 
 may have opposite directions. Another series of lines, having a brown appear- 
 ance from pigmentation, and denominated the parallel striae or brown striae of 
 Retzius or the colored lines, are seen on a section of the enamel. These lines 
 are concentric and cross the enamel rods. They are caused by the mode of 
 enamel deposition. Inasmuch as the enamel columns, when near the dentine, 
 cross each other and only become parallel farther away, a series of radial mark- 
 ings, light and dark alternately, is obtained (Fig. 808). The enamel prisms are 
 themselves calcified and are fixed to each other by a very small amoimt of cement 
 substance. Numerous minute interstices intervene between the enamel-fibres 
 near their dentinal surface. It is noted that some of the dentinal canals at the 
 crown penetrate a certain distance between the rods of the enamel (Fig. 810). No 
 nutritive canals exist in the enamel, except the very few dentinal canals which at 
 the crown penetrate a short distance, and these are found only in a small area. 
 
 Chemical Composition. — According to Bibra, enamel consists of 96.5 per cent, 
 of earthy matter and 3.5 per cent, of animal matter. The earthy matter consists 
 of the phosphate and the carbonate of calcium, with traces of fluoride of calcium, 
 phosphate of magnesia, and other salts. 
 
 The enamel of a recently erupted tooth is covered by a membrane, the thick- 
 ness of which is ^Vfo" ^^ ^^ inch. It is known as enamel cuticle or Nasmyth's mem- 
 brane (cuticula dentis). It is probably the most recent, and hence an uncalcified, 
 or partly calcified enamel layer. Some believe it to be a product of the outer layer 
 of the cells of the enamel organ. 
 
 The Cortical Substance, Cementum or Crusta Petrosa (substantia ossea) (Figs. 808 
 and 81 1) is disposed as a thin layer on the roots and neck of a tooth, from the termi- 
 nation of the enamel as far as the apex of the root, where it is usually very thick. At 
 the neck it overlays a slight margin of enamel. In structure and chemical com- 
 position it is true bone. It contains, sparingly, the lacunae and canaliculi which 
 characterize true bone; the lacunae placed near the surface have the canaliculi radi- 
 ating from the side of the lacunae toward the periodontal membrane or dental 
 periosteum, and those more deeply placed join with adjacent dentinal tubuli. The 
 teeth of the young usually contain Haversian systems in the thicker portions of 
 the cementum. The neck of the tooth does not contain lacunae. The cementum 
 is occasionally laminated. Sharpey's fibres (p. 37) are very numerous. Some of 
 the lacunae of the cementum receive dentinal tubes from the dentine. 
 
 As age advances the cement increases in thickness, and gives rise to those bony growths, or 
 exostoses, so common in the teeth of the aged; the pulp-cavity becomes also partially filled up 
 by a hard substance intermediate in structure between dentine and bone (the osteo-dentine of 
 Owen; the secondary dentine of Tomes). It is formed by the odontoblasts, the dental pulp 
 lessening in volume. 
 
 Development of the Teeth (Figs. 813, 814, 815, and 816).— The teeth are an 
 evolution from the dermoid system, and not of the bony skeleton; they are devel- 
 oped from two of the blastodermic layers, the epiblast and mesoblast. From the 
 former the enamel is developed; from the latter the dentinal pulp, dentine, cemen- 
 tum, and pericementum. It is customary to view the development of the per- 
 manent and temporary teeth as separate studies. 
 
 The earliest evidence of tooth-formation in the human embryo is observed 
 about the seventh week. The mucous membrane covering the embryonic jaws is 
 seen to rise as a longitudinal ridge along the summit of each jaw. This ridge is 
 
THE TEETH 
 
 1205 
 
 the maxillary rampart of Kblliker and Waldeyer. A transverse section through the 
 jaw will show the elevation to be due to a linear and outlined activity of the 
 germinal epithelial layer; a corresponding epithelial growth is seen to sink as a 
 band into the mesoblastic tissue beneath. This band is called the dental lamina 
 or dental band. The local cell-activity continues, and in its descent the band 
 appears to meet with a resistance which causes a flattening of its extremity into a 
 continuous lamina. From the inner (toward the tongue) edge of the lamina 
 epithelial cords are given off, ten in number, one for each temporary tooth. 
 
 Fig. 813. — Diagram of method of development of the teeth. 1. Early stage. 4. Later stage. 2, 3. Inter- 
 mediate stages. «. Common dental germ. o. Special dental germ (milk). &. Special dental germ (permanent), 
 p. Papilla, e. Dental furrow. (Gegenbauer.) 
 
 The growth of each cord continues, and each expands into a flask-like form, the 
 walls covered by a layer of germinal cells, its interior by swollen mature cells. 
 The ingrowing bulb is now seen to flatten upon its lower surface, as though it had 
 met with an outlined resistance from the mesoblastic tissue beneath. The epithelial 
 ingrowth assumes the general form of the several teeth; it is the enamel-organ of 
 the tooth (Fig. 813). The cellular tissue of the jaw beneath the cap of the enamel- 
 organ grows and projects into the cap. This projection is the dentine papilla 
 (papilla dentis). At this period the mesoblastic tissue around each enamel-organ 
 is seen to become differentiated into fibrous tissue surrounding the enamel-organs, 
 
 Dental furrow 
 
 Remains of ' ' neck ' ' of 
 enamel organ, or of the 
 common dental germ 
 
 Permanent special 
 
 dental germ 
 
 Meckel's cartilage. 
 
 Internal enamel layer, 
 or adamantoblasts 
 
 Dental sac 
 
 Enamel pulp 
 External enamel 
 layer 
 Papilla 
 
 Lower jaw. 
 
 Fig. 814. — Vertical section of the inferior maxilla of an early human foetus. (Magnified 25 diameters.) 
 
 but at some distance from them. Islets of bone are also seen to be forming the 
 beginning of the bony maxillae. 
 
 The indentation of the base of the enamel-organ continues until it assumes 
 the form of the future teeth. The cells bounding the organ assumes a cylindrical 
 form ; the cells of the interior become much expanded, and irregular in size and 
 form. 
 
 The mesoblastic tissue underlying the enamel-organ is much condensed; evi- 
 dences of cellular differentiation and a vascular system appear. Bone continues to 
 
1206 
 
 THE ORGANS OF DIGESTION 
 
 develop until all of the tooth-follicles are embraced in a gutter of bone. From the 
 lingual side of the cords of the temporary teeth epithelial buds are given off, which 
 sink into the raesoblastic tissue and form the enamel-organs of the permanent 
 teeth. The condensation of fibrous tissue continues until each embryonic tooth is 
 enveloped in a sac, the dental sac (Fig. 814) ; this, together with all of its contents, 
 is called the dental follicle. 
 
 The tooth which is undergoing development with its enamel-organ and dentine 
 papilla is known as the tooth germ. This tooth germ is encompassed and shut off 
 from surrounding structures by the bag of membranous structure known as the 
 dental sac. 
 
 The cells of the enamel-organ now undergo a series of differentiations: the 
 inner layer, arranged as columnar epithelium, are the enamel cells, or ameloblasts. 
 The layer is called the ameloblastic or enamel-forming layer (Figs. 814 and 815). 
 The cells of the outer wall remain cuboidal; the cells which lie between become 
 much distended, and on account of their appearance when seen in section this 
 portion of the organ is called the enamel jelly or the stellate reticulum. The layer of 
 cells immediately contiguous to the ameloblasts form a layer called the stratum 
 intermedium (Fig. 815 A, D). 
 
 Dentine. 
 
 Enamel. 
 
 Fig. 815. — A. Section through tooth-follicle — human canine seven and one-half months. A. Follicular wall. 
 B. Outer epithelial coat. C. Stellate reticulum. D. Stratum intermedium. E. Ameloblasts. F. Odonto- 
 blasts. O. Pulp. 
 
 B. Diagram after Williams (Dental Cosmos, 1896), mode of enamel deposition. A. Blood-supply to B, secret- 
 ing papillae. C. Layer of ameloblasts containing enamel globules and droplets of calcoglobulin. D. Enamel- 
 globules dep'osited. E. Formed dentine. F. Forming dentine. O. Layer of odontoblasts. H. Blood-supply 
 to odontoblastic layer. 
 
 The enclosed mesoblastic papilla (the future dental jmlp) has its peripheral cells, 
 which are called odontoblasts, differentiated into columnar bodies disposed as a 
 layer, each cell having a large nucleus. The vascular supply of the pulp is now 
 well marked. A section of a follicle at this period will exhibit the follicular wall 
 springing from the base of the dental papilla and having a well-marked blood- 
 supply. The bony alveolar walls are well outlined, and evidences of a periosteum 
 appear (Figs. 814 and 815). 
 
 Development of Enamel (Fig. 815 B).— In point of time, the deposition .of den- 
 tine actually begins before that of enamel, so that the first-formed layer of enamel 
 is deposited against a layer of immature dentine. The enamel is built up of two 
 distinct substances — globules of uniform size which are formed by the amelo- 
 blasts, and a cementing substance, probably an albuminate of calcium (calco- 
 globulin), the basis of all the calcified tissues. At the ends of the ameloblasts. 
 
THE TEETH 1207 
 
 next to the dentine, the secretion of calco-globulin is deposited, and into the 
 plastic mass the enamel-globules are extruded, each globule remaining con- 
 nected with the ameloblasts by plasmic strings, which also join the globules 
 laterally.^ 
 
 The first deposit of enamel begins in the tips of the cusps, and is quickly fol- 
 lowed by a disappearance of the stellate reticulum at that point; the stellate retic- 
 ulum appears to atrophy, so that the vascular follicular wall is brought into 
 direct apposition with the stratum intermedium, which becomes differentiated into 
 a glandular (secreting) tissue which elaborates the calcic albuminous basis of the 
 enamel. The secretion passes from the cells of the stratum intermedium through a 
 membrane into the ameloblasts, where it is in part combined with the cellular 
 globules, and irregular masses of it are extruded as cementing substance. The 
 deposition continues until the enamel-cap has its typical form. The deposition 
 of the layers of globules is indicated by parallel lines transverse to the axes of the 
 enamel-rods. At the completion of amelification the ameloblasts ai£ partially 
 calcified and form the enamel cuticle or Nasmyth's membrane {cuticula dentis). 
 
 Formation of Dentine. — The layer of columnar cells bounding the periphery of 
 the pulp, the odontoblasts, are in apposition with a plexus of capillary vessels 
 (Fig. 816). Each cell is a secreting body which selects the material for dentine- 
 building. Against the layer of ameloblasts 
 covering the dental papilla the odontoblasts 
 deposit globules, of the calcium albuminate, 
 and receding as the deposits are made, leave 
 one or more protoplasmic processes in the 
 calcic deposit. These are known as Tomes 's 
 fibres. The process continues until the normal 
 dentine thickness is formed. The deposit is 
 laid down in a scaffolding of finely fibrillated 
 tissue. The layer of formative cells remains p,^ gie.-Part of section of' developing 
 constant. The remains of the dentine papilla tooth of young rat showing the mode of 
 
 , , ^ '^ . deposition of the dentine (highly magnified). 
 
 constitute the pulp and lie in the pulp-cavity «• Outer layer of fully-calcified dentine. 
 
 , ., oAn\ ^ *^ "^ 0. Uncalcified matrix with a few nodules of 
 
 (p. 12UU). calcareous matter. c. Odontoblasts with 
 
 ■a J.- e n a. TT x • ± processes extending into the dentine, d. Pulp. 
 
 Formation of CementUm. nertWlg asserts The section is stained with carmine, which 
 
 that the epithelial edge of the enamel organ co^ors^he, uncalcified matrix, but not the cai- 
 
 formed by the inner and outer epithelial layers 
 
 of the organ grows downward, or rather the developing tooth grows upward until 
 
 the future root-form of the tooth is outlined by a double layer of epithelial cells, 
 
 constituting the root-sheath of Hertwig. The growth of the alveolar process is 
 
 synchronous. 
 
 Upon the pulp side of the sheath a layer of odontoblasts is developed; upon 
 the outer side the fibrous encasement becomes closely attached to the sheath and a 
 layer of osteogenetic cells is differentiated. These cells are called cementoblasts. 
 The growth of the dentine of the root is exactly similar to the growth of that of 
 the crown. The epithelial sheath undergoes atrophic changes, leaving the epithe- 
 lial whorls which remain in the pericementum. The cementum is developed as 
 subperiosteal bone. The cementum over the apex of the root is not formed until 
 after the eruption of the tooth. 
 
 Formation of Alveoli. — By the time the crowns of the teeth have formed, each 
 is enclo.sed in a loculus of bone Avhich has developed around it and at some distance 
 from it; the loculus is open at the top toward the gums, where it is closed by 
 fibrous tissue; the developing permanent tooth is contained in the same loculus, 
 but is later separated from the temporary tooth by a growth of bone. The alveolar 
 
 ' J. L. Williams, Dental Cosmos, 1896. 
 
1208 THE ORGANS OF DIGESTION 
 
 process is not completed until after the eruption of the teeth. During eruption 
 that portion of the process overlying the crown undergoes absorption, and as soon 
 as the immature tooth has erupted the alveolar process is developed about the root, 
 whose formation is also completed after eruption. 
 
 Development of the Permanent Teeth. — The permanent teeth as regards their 
 development may be divided into two sets: (1) those which replace the temporary 
 teeth, and which, like them, are ten in number; these are the successional perma- 
 nent teeth; and (2) those which have no temporary predecessors, but are super- 
 added at the back of the dental series. These are three in number on either side 
 in each jaw, and are termed the superadded permanent teeth. They are the three 
 molars of the permanent set, the molars of the temporary set being replaced by 
 the premolars or bicuspids of the permanent set. 
 
 The Development of the Successional Permanent Teeth — the ten anterior ones 
 in either jaw — will be first considered. As already stated, the germ of each 
 milk tooth is a special thickening of the "free" edge of the common dental germ 
 or dental lamina. In like manner is formed the special dental germ of each of 
 the successional permanent teeth. But these thickenings are not at the "free" 
 edge of the dental lamina, but occur behind and lateral to each of the milk-tooth 
 germs (Fig. 813). There are ten of these, and they appear in order, about the 
 sixteenth week, on each side, the central incisor germs being the first. 
 
 These special dental germs now go through the same transformations as 
 were described in connection with those of the milk teeth, and the changes also 
 eventuate in the germs becoming enamel organs; that is, they recede into the 
 substance of the gum behind the germs of the temporary teeth. As they recede 
 they become flask-shaped, form an expansion of their distal extremity, and finally 
 meet a papilla, which has been formed in the mesoblast, just in the same 
 manner as was the case in the temporary teeth. The apex of the papilla inden- 
 tates the dental germ, which encloses it, and forming a cap for it, undergoes 
 analogous changes to those described in the development of the milk teeth, and 
 becomes converted into the enamel, whilst the papilla forms the dentine of the 
 permanent tooth. In its development it becomes enclosed in a dentinal sac which 
 adheres to the hack of the sac of the temporary tooth. The sac of each perma- 
 nent tooth is also connected with the fibrous tissue of the gum by a slender band 
 of the gubernaculum, which passes to the margin of the jaw behind the correspond- 
 ing milk tooth (see above). 
 
 The Superadded Permanent Teeth — three on each side in each jaw — arise from 
 successive extensions backward — i. e., along the line of the jaw — of the common 
 dental germ from the back part of the special dental germ of the immediately 
 preceding tooth. During the fourth month or seventeenth week, in that portion 
 of the common dental germ which lies behind — i. e., lateral to the special dental 
 germ of the last temporary molar tooth, and which has hitherto remained imal- 
 tered — there is developed the special dental germ of the first permanent molar 
 into which a papilla projects. In a similar manner, about the fourth month after 
 birth the second molar is formed, and about the third year the third molar. 
 
 Eruption. — When the calcification of the different tissues of the milk tooth 
 is sufficiently advanced to enable it to bear the pressure to which it will be after- 
 ward subjected, its eruption takes place, the tooth making its way through the 
 gum. The gum is absorbed by the pressure of the crown of the tooth against it, 
 which is itself pressed up by the increasing size of the fang. At the same time 
 the septa between the dentinal sacs, at first fibrous in structure, ossify and thus 
 form the loculi or alveoli ; these firmly embrace the necks of the teeth and afford 
 them a solid basis. 
 
 Previous to the permanent teeth penetrating the gum, the bony partitions 
 which separate their sacs from the deciduous teeth are absorbed, the roots of 
 
THE TEETH 
 
 1209 
 
 the temporary teeth disappear by absorption through the agency of particular 
 mukinucleated cells, called odontoclasts, which are developed at the time in the 
 neighborhood of the root, and the permanent teeth become placed under the 
 loose crown of the deciduous teeth; the latter finally become detached, and the 
 permanent teeth take their place in the mouth (Fig. 817). 
 
 Fig. 817. — The milk-teeth in a child of about four years. The permanent leeii; .iio . ci ii in their alveoli. (Cryer.) 
 
 Calcification of the permanent teeth proceeds in the following order: First 
 molar, soon after birth; the central incisor, lateral incisor, and cuspid, about six 
 months after birth; the bicuspids, at the second year or later; second molar, end 
 of second year; third molar, about the twelfth year. 
 
 The Eruption of the Temporary Teeth commences at the seventh month, and is 
 complete about the end of the second year. 
 
 The periods for the eruption of the temporary set are (C. S. Tomes) — 
 
 Lower central incisors 
 
 Upper incisors ..... 
 
 Lower lateral incisors and first molars 
 Canines ...... 
 
 Second molars ..... 
 
 6 to 9 months. 
 8 to 10 '■ 
 
 15 to 21 " 
 
 16 to 20 " 
 20 to 24 " 
 
 The Eruption of the Permanent Teeth takes place at the following periods, the 
 teeth of the lower jaw preceding those of the upper by a short interval : 
 
 C^ years, first molars. 
 7th year, two middle incisors. 
 8th year, two lateral incisors. 
 9th year, first bicuspid. 
 
 10th year, second biscuspid. 
 11th to 12th year, canine, 
 12th to 13th year, second molars. 
 17th to 21st year, third molars. 
 
1210 
 
 THE OBGANS OF DIGESTION 
 
 The Palate (Palatum). 
 
 The palate forms the roof of the mouth; it consists of two portions, the hard 
 palate in front, the soft palate behind. 
 
 The Hard Palate {^palatum durum) (Figs. 818 and 819). — The hard palate is 
 bounded in front and at the sides by the upper alveolar arches and gums. In 
 front and to the sides it is continuous with the gums; behind, it is continuous 
 with the soft palate. It is formed by the palate processes of the superior maxil- 
 lary bones and the palate processes of the palate bones (Fig. 72) , It is covered by a 
 dense structure formed by the periosteum and mucous membrane of the mouth, 
 which are intimately adherent, particularly to the front and sides, by means of 
 
 ANTERIOR 
 PILLAR 
 
 POSTERIOR 
 PILLAR 
 
 Fig. 818. 
 
 -Antero-inferior surface of the soft palate. The tongue has been removed, so that the pharyngeal 
 isthmus is distinctly seen. (Luschka.) 
 
 a layer of fibrous tissue. Along the middle line is a linear ridge or raphe (raphe 
 palati), which terminates anteriorly in a small papilla, the incisive papilla (papilla 
 incisiva), corresponding with the inferior opening of the anterior palatine fossa. 
 This papilla receives filaments from the naso-palatine and anterior palatine 
 nerves. The incisive papilla in a recently born child is continuous with the 
 gum and the frenulum of the upper lip. On either side and in front of the raphe 
 the mucous membrane is thick, pale in color, and corrugated; these corruga- 
 tions, which are composed of fibrous tissue, are the palatine rugae (plicae pala- 
 tinae transversae) . In very young children the rugae are distinct and definite. 
 In the aged they are indistinct. Behind, it is thin, smooth, and of a deeper 
 color; it is covered with squamous epithelium, and the fibrous tissue beneath it 
 
THE PALATE 
 
 1211 
 
 contains many mucous glands, the palatine glands (glandulae palatinae) . The 
 palatine vessels and nerves lie in the fibrous tissue beneath the mucous membrane. 
 The Soft Palate or Velum Pendulum Palati (palatum molle) (Figs. 818, 819, 
 and 824). — The soft palate is a movable fold suspended from the posterior border 
 of the hard palate, and forming an incomplete septum between the mouth and 
 pharynx. It consists of a fold of mucous membrane enclosing muscular fibres, 
 an aponeurosis, vessels, nerves, adenoid tissue, and mucous glands. When 
 occupying its usual position it is relaxed and pendent and its oral surface is 
 concave, continuous with the roof of the mouth, and marked by a median ridge 
 or raphe, which indicates its original separation into two lateral halves. Its 
 pharyngeal surface is convex, and continuous with the mucous membrane cover- 
 
 ANTERIOR 
 PALATINE CANAL 
 
 i PALATINE 
 
 ANDS 
 
 DESCENDING 
 
 PALATINE 
 
 ARTERV 
 
 Fig. 819. — The palatine vault on the right side of the mucous membrane has been removed. The left side shows 
 the mucous membrane and the glandular layer. (Poirier and Charpy ) 
 
 ing the floor of the posterior nares. Its anterior or upper border is attached to 
 the posterior margin of the hard palate, and its sides are blended with the 
 pharynx. Its posterior or lower border is free. The posterior portion of the 
 soft palate is known as the vail of the palate (velum palatinum) and terminates 
 posteriorly and externally on each side in a free margin, the posterior arch of 
 the palate. 
 
 Hanging from the middle of its lower border is a small, conical-shaped, pen- 
 dulous process, the uvula (uvula palatina). The uvula varies greatly in length in 
 different individuals. It is composed of glands and connective tissue, contains a 
 prolongation of the Azygos uvulae muscle and is covered with mucous membrane, 
 and arching outward and downward from the base of the uvula on each side are 
 two curved folds of mucous membrane, containing muscular fibres, called the 
 arches or pillars of the soft palate or pillars of the fauces (arcus palatini). 
 
1212 THE ORGANS OF DIGESTION 
 
 The Anterior Pillax {arcus glossopalatinus) (Figs. 818 and 824). — The anterior 
 pillar on each side runs downward, outward, and forward to the side of the base 
 of the tongue. These pillars are formed by the projection of the Palato-glossi 
 muscles, covered by mucous membrane. 
 
 The Posterior Pillax (arcus pharijngopalatinus) (Figs. 818 and 824). — The pos- 
 terior pillar on each side is nearer to its opposite arch than is the anterior pillar to its 
 opposite. These pillars are larger than the anterior; they run downward, outward, 
 and backward to the sides of the pharynx, and are formed by the projection of the 
 Palato-pharyngei muscles, covered by mucous membrane. The anterior and pos- 
 terior pillars are separated below by a triangular interval in which the tonsil is lodged. 
 
 The space left between the arches of the palate on the two sides is called the 
 isthmus of the fauces {isthmus faucium). It is bounded, above, by the free margin 
 of the soft palate; below, by the back of the tongue; and on each side by the 
 pillars of the fauces and the tonsils. Through this isthmus the mouth com- 
 municates with the pharynx. 
 
 The Mucous Membrane of the Soft Palate. — The mucous membrane of the soft 
 palate is thin, and covered with squamous epithehum on both surfaces, excepting 
 near the orifice of the Eustachian tube, where its epithelium is columnar and 
 ciliated.^ Beneath the mucous membrane on the oral surface of the soft palate 
 is a considerable amount of adenoid tissue. The palatine glands form a con- 
 tinuous layer on the pharyngeal surface and around the uvula. 
 
 The Aponeurosis of the Soft Palate. — The aponeurosis of the soft palate is a thin 
 but firm fibrous layer attached above to the posterior border of the hard palate, 
 and becoming thinner toward the free margin of the velum. Laterally, it is con- 
 tinuous with the pharyngeal aponeurosis. It forms the framework of the soft 
 palate, and is joined by the tendons of the Tensor palati muscles. 
 
 The Muscles of the Soft Palate. — The muscles of the soft palate are six on each 
 side: the Levator palati, Tensor palati, Azygos uvulae, Palato-glossus, Palato- 
 pharyngeus and Salpingo-pharjmgeus (see pp. 403, 404, 405, and 406). The follow- 
 ing is the relative position of these structures in a dissection of the soft palate 
 from the posterior or naso-pharyngeal to the anterior or oral surface: Imme- 
 diately beneath the pharyngeal mucous membrane is a thin stratum of mus- 
 cular fibres, the posterior fasciculus of the Palato-pharyngeus muscle, joining 
 with its fellow of the opposite side in the middle line. This posterior fasciculus 
 is joined by the Salpingo-pharyngeus muscle. Beneath this are the Azygos uvulae 
 and Salpingo-pharsmgeus muscles, consisting of two rounded fleshy fasciculi, 
 placed side by side in the median line of the soft palate. Next comes the aponeu- 
 rosis of the Levator palati, joining with the muscle of the opposite side in the mid- 
 dle line. Fourthly, the anterior fasciculus of the Palato-pharyngeus, thicker than 
 the posterior, and separating the Levator palati from the next muscle, the Tensor 
 palati. This muscle terminates in a tendon which, after winding around the hamu- 
 lar process of the internal pterygoid plate of the sphenoid bone, expands into a 
 broad aponeurosis in the soft palate, anterior to the other muscles, which have 
 been enumerated. Finally, we have a thin muscular stratum, the Palato-glossus 
 muscle, placed in front of the aponeurosis of the Tensor palati, and separated from 
 the oral mucous membrane by adenoid tissue. 
 
 The Blood-vessels of the Palate (Fig. 819) . — The palate is supplied with blood by 
 branches of the posterior or descending palatine branch of the internal maxillary artery 
 (a. 'palatina descendens) and of the ascending or anterior palatine branch of the facial 
 artery (a. j>alatina ascendens). The posterior palatine artery divides into the great 
 and small palatine arteries {aa. falatinae major et minor), which run through the 
 
 ' According to Klein, the mucous membrane on the nasal surface of the soft palate in the foetus is covered 
 throughout by columnar ciliated epithelium, which subsequently becomes squamous ; and some anatomists 
 state that it is covered with columnar ciliated epithelium, except at its free margin, throughout life. — Ed. of 
 15th English edition. 
 
THE TONSIL 1213 
 
 palatine canals and after emerging give off branches. Branches from the small 
 palatine go to the soft palate, the large branch passes forward on the hard palate 
 near the alveolar margin. The ascending palatine branch of the facial lies upon 
 the medial surface of the Tensor palati muscle and is distributed to the soft palate 
 and pharynx. A palatine vein corresponding to the descending palatine artery 
 opens into the anterior facial vein. The pharyngeal veins also receive palatine veins. 
 
 The Nerves of the Palate. — The large posterior palatine nerve emerges from the 
 posterior palatine canal and accompanies the posterior palatine artery. The naso- 
 palatine nerve emerges from the foramen of Scarpa and is distributed to the anterior 
 portion of the hard palate. The soft palate is supplied by the small posterior 
 palatine and the accessory palatine nerves. 
 
 The Tonsil or Amygdala {tonsilla palatina) (Figs. 818 and 824).— The tonsils 
 or amygdalae are two prominent bodies situated one on each side of the fauces, 
 between the anterior and posterior pillars of the soft palate. They are of a 
 rounded form, and vary considerably in size in different individuals. A recess, 
 the supra-tonsillar fossa (fossa supratonsillaris) , may be seen, directed upward 
 and backward above the tonsil. His regards this as the remains of the lower part 
 of the second visceral cleft. The recess is covered by a fold of mucous mem- 
 brane termed the plica triangularis. Externally the tonsil is covered with a fibrous 
 capsule which joins the aponeurosis of the pharynx. The outer surface of the 
 capsule is in relation with the inner surface of the Superior constrictor muscle 
 of the pharynx, to the outer side of which is the Internal pterygoid muscle. The 
 ascending palatine artery is close to the outer surface of the tonsil, the Superior 
 constrictor muscle of the pharynx and the tonsillar capsule intervening. The 
 tonsillar artery, which is sometimes a branch of the ascending palatine, is also 
 close to the outer surface of the tonsil. The internal carotid artery lies behind 
 and to the outer side of the tonsil, and nearly an inch (20 to 25 mm.) distant from 
 it. It corresponds to the angle of the lower jaw. The surface of the tonsil 
 which looks toward the pharynx presents from twelve to fifteen orifices, each 
 leading into a small recess or crypt (fossula tonsillaris). From the crypts 
 numerous follicles branch out into the substance of the tonsil by means of very 
 irregular channels. The crypts are lined with stratified pavement epithelium. 
 The epithelium of the crypts exhibits marked degenerative changes. The 
 degeneration causes the formation of numerous communicating spaces, which 
 contain leukocytes and lymphocytes. The crypts are surrounded with lymphoid 
 tissue. In this are numerous lymphoid follicles (noduli lymphatici), which are 
 placed in the submucous tissue. These follicles are analogous to those of 
 Peyer's glands and consist of adenoid tissue. No openings from the capsules 
 into the follicles can be recognized. They contain a thick grayish secretion. 
 
 The Blood-vessels of the Tonsil. — The arteries supplying the tonsils are the 
 dorsalis linguae from the lingual, the ascending palatine and tonsillar from the 
 facial, the ascending pharyngeal from the external carotid, the descending palatine 
 branch of the internal maxillary, and a twig from the small meningeal. The veins 
 terminate in the tonsillar plexus, on the outer side of the tonsil, and the tonsillar 
 plexus joins the pharyngeal plexus, which communicates with the pterygoid plexus 
 of the internal jugular or facial vein. 
 
 L3rmphatics of the Tonsil. — Surrounding each follicle is a close plexus of lym- 
 phatic vessels. From these plexuses the lymphatic vessels pass to the submaxillary 
 lymph glands below the angle of the jaw. From the submaxilliary glands lymph 
 passes to the deep cervical glands. 
 
 The Nerves of the Tonsil. — A branch from the glosso -pharyngeal nerve by uniting 
 with branches of the pharyngeal plexus forms the tonsillar plexus. The pharyn- 
 geal plexus is formed by the pharyngeal branches of the glosso-pharyngeal and 
 superior cervical ganglions and the pharyngeal branch of the vagus. 
 
1214 
 
 THE ORGANS OF DIGESTION 
 
 The Salivary Glands (Fig. 820). 
 
 Numerous glands exist in the lips, cheeks, palate, and tongue, but by the term 
 salivary glands are usually understood the three chief glandular masses on each 
 side of the face. These are the principal salivary glands. They communicate 
 with the mouth, pour their secretion into its cavity, and are named respectively 
 the parotid, submaxillary, and sublingual. 
 
 The Parotid Gland (glandulae parotis) (Fig. 646). — The parotid gland, so 
 called from being placed near the ear (napd, near; o2>c, ciroc, the ear), is the 
 largest of the three salivary glands, varying in weight from half an ounce to an 
 ounce. It lies upon the side of the face immediately below and in front of the 
 external ear. It is limited above by the zygoma; below, by the angle of the jaw 
 and by a line drawn between the angle and the mastoid process: anteriorly, it 
 
 Fig. 820. — The salivary glands. 
 
 extends to a variable extent over the Masseter muscle ; posteriorly, it is bounded 
 by the external meatus, the mastoid process, and the Sterno-mastoid and Digastric 
 muscles, slightly overlapping the two muscles. 
 
 Its anterior surface is grooved to embrace the posterior margin of the ramus of 
 the lower jaw, and advances forward beneath the ramus, between the two Ptery- 
 goid muscles and superficial to the ramus over the Masseter muscle. Its outer 
 surface is triangular and convex, slightly lobulated, is covered by the integument 
 and parotid fascia, and has one or two lymphatic glands resting on it. Its inner 
 surface (processus retromandihularis) extends deeply into the neck by means of 
 two large processes, one of which dips behind the styloid process and projects 
 beneath the mastoid process and the Sterno-mastoid muscle; the other is situated 
 in front of the styloid process, and passes into the back part of the glenoid 
 fossa, behind the articulation of the lower jaw. The structures passing through 
 the parotid gland are — the external carotid artery, giving off its three terminal 
 
THE SALIVARY GLANDS 1215 
 
 branches : the posterior auricular artery emerges from the gland behind ; the super- 
 ficial temporal artery above; the transverse facial, a branch of the temporal, in front; 
 and the internal maxillary winds through it as it passes inward, behind the neck 
 of the jaw. Superficial to the external carotid is the trunk formed by the union 
 of the temporal and internal maxillary veins; a branch, connecting this trunk 
 with the internal jugular, also passes through the gland. The gland is also 
 traversed by the facial nerve and its branches, which emerge at its anterior 
 border; branches of the great auricular nerve pierce the gland to join the facial, 
 and the auriculo -temporal branch of the inferior maxillary nerve emerges from the 
 upper part of the gland. The internal carotid artery and internal jugular vein lie 
 close to its deep surface. The triangular space occupied by the greater part of 
 the gland is bounded in front by the posterior margin of the ramus of the jaw 
 and the internal pterygoid muscle, and behind by the anterior edge of the Sterno- 
 cleido-mastoid muscle, the tympanic portion of the temporal bone and the car- 
 tilaginous portion of the external auditory meatus. Its floor is formed by the 
 anterior and posterior walls of the space which meet about the styloid process. 
 These walls are composed of fascia derived from the deep cervical fascia. The 
 remaining side of the space is external and is formed by fascia, derived from the 
 deep cervical fascia and called the parotid fascia. This space is called the parotid 
 recess. Sir Frederick Treves^ denies that the fascial covering of the space is 
 complete. He says it is deficient above between the anterior edge of the styloid 
 process and the posterior border of the external pterygoid muscle. A portion 
 of the gland does not occupy the space, but projects forward over the Masseter 
 muscle. This projecting portion is the facial process. 
 
 Lymph-glands, known as the parotid lymph-glands, are in and about the parotid 
 gland, some being embedded in the outer surface of the parotid fascia, others 
 being in the inner surface of the fascia, others in the gland itself, particularly 
 along the temporo-maxillary vein and external carotid artery. They receive 
 lymph from the anterior and lateral portions of the scalp, both eyelids, a portion 
 of the cheek, the root of the nose, the outer portion of the external ear, the soft 
 palate, the posterior nares, and the external auditory meatus. The vessels from 
 them empty into the superficial cervical glands and the superior deep cervical 
 glands. Between the parotid gland and the pharynx are the subparotid glands. 
 They receive lymph from the nasal fossae, naso-pharynx and Eustachian tube, and 
 vessels from the glands take lymph to the deep cervical glands.^ 
 
 The Duct of the Parotid Gland, called the Parotid Duct or Stenson's Duct (ductus 
 farotideus [Stenonis]) (Fig, 820). — The duct of the parotid gland is about two 
 inches and a half in length. It commences by numerous branches from the ante- 
 rior part of the gland, crosses the Masseter muscle, and at its anterior border dips 
 down into the substance of the Buccinator muscle, which it pierces; it then runs 
 for a short distance obliquely forward between the Buccinator muscle and the 
 mucous membrane of the mouth, and opens upon the inner surface of the cheek 
 by a small orifice opposite the second molar tooth of the upper jaw (Fig. 824). 
 Upon the beginning of Stenson's duct there is often an accessory parotid gland 
 (glandulae parotis accessor ia), which is often called the socia parotidis. It is a 
 portion of the facial process'. It is a detached portion of gland, and has a duct 
 which opens into Stenson's duct. This accessory gland occasionally exists as a 
 separate lobe, just beneath the zygomatic arch. In this position it has the trans- 
 verse facial artery above it and some branches of the facial nerve below it. 
 
 Surface Form. — The direction of the duct corresponds to a line drawn across the face about 
 a finger's breadth below the zygoma; that is, from the lower margin of the concha to midway 
 between the free margin of the upper lip and the ala of the nose. 
 
 1 Applied Anatomy. ^ Poirier and Cun^o, Human Anatomy. 
 
1216 THE ORGANS OF DIGESTION 
 
 Structure of the Parotid Duct.— The parotid duct is dense, it is of considerable 
 thickness, and its canal is about the size of a crowquill; but at vis orifice on the 
 inner aspect of the cheek its lumen is greatly reduced in size. The duct consists 
 of an external or fibrous coat, of considerable density, containing contractile 
 fibres, and of an internal or mucous coat lined with short columnar epithelium. 
 
 Vessels and Nerves. — The arteries supplying the parotid gland are derived from 
 the external carotid, and from the branches given off by that vessel in or near its 
 substance. The veins empty themselves into the external jugular through some 
 of its tributaries. The lymphatics terminate in the superficial cervical and the 
 deep cervical glands, passing in their course through several lymphatic glands 
 placed on the surface and in the substance of the parotid. The nerves are 
 derived from the plexus of the sympathetic on the external carotid artery, the 
 facial, the auriculo -temporal, and great auricular nerves. It is probable that the 
 branch from the auriculo-temporal nerve is derived from the glosso-pharyngeal 
 through the otic ganglion. At all events, in some of the lower animals this has 
 been proved experimentally to be the case. 
 
 The Parotid Capsule. — The parotid gland is enclosed by two layers of the parotid 
 fascia {fascia parotideomasseterica) , which almost completely encompass the 
 gland. The sheath is incomplete at one area toward the pharyngeal wall (see 
 p. 1215). 
 
 The parotid fascia comes from the deep cervical fascia. The external layer 
 covers the gland. The internal layer lines the parotid recess. The external layer 
 is the structure usually spoken of as the parotid fascia. Anteriorly it joins 
 the fascia of the masseter; below it is continuous v/ith the deep cervical fascia; 
 above it is attached to the zygoma; behind it is adherent to the external auditory 
 meatus and sheath of the Sternomastoid. The deep layer is adherent above to the 
 external auditory meatus and back of the glenoid fossa; internally to the styloid 
 process; below it is continuous with the deep cervical fascia. The stylomaxillary 
 or stylomandibular ligament comes off from the parotid fascia. 
 
 The Submaxillary Gland (glandula submaxillar is) (Fig. 820). — The submax- 
 illary gland is situated below the jaw, in the anterior part of the submaxillary 
 triangle of the neck. It is irregular in form and weighs about two drachms 
 (8 to 10 grammes). It is covered by the integument, Platysma, deep cervical 
 fascia, and the body of the lower jaw, corresponding to a depression on the 
 inner surface of the body of the mandible, and lies upon the Mylo-hyoid, Hyo- 
 glossus, and Stylo-glossus muscles, a portion of the gland passing beneath the 
 posterior border of the Mylo-hyoid. In front of it is the anterior belly of the 
 Digastric muscle; behind, it is separated from the parotid gland by the stylo- 
 maxillary ligament, and from the sublingual gland in front by the Mylo-hyoid 
 muscle. The facial artery lies embedded in a groove in its posterior and upper 
 border. A process is given off from the deep surface of the anterior portion of 
 the gland. This is the deep process (Cunningham), and it passes with the duct 
 beneath the Mylo-hyoid muscle. 
 
 The Duct of the Submaxillary Gland or Wharton's Duct (ductus suhmaxillaris 
 \Whartoni\). — The duct of the submaxillary gland is about two inches in length, 
 and its walls are much thinner than those of the parotid duct. It commences by 
 numerous branches from the deep portion of the gland which lies on the upper 
 surface of the Mylo-hyoid muscle, and passes forward and inward between the 
 Mylo-hyoid and the Hyo-glossus and Genio-hyo-glossus muscles, then between the 
 sublingual gland and the Genio-hyo-glossus muscle, and opens by a narrow orifice 
 on the summit of a small papilla (caruncula sublingualis) at the side of the fraenum 
 linguae. On the Hyo-glossus muscle it lies between the lingual and hypoglossal 
 nerves, but at the anterior border of the muscle it crosses under the lingual nerve, 
 and is then placed above it. 
 
THE SALIVARY GLANDS 
 
 1217 
 
 Vessels and Nerves. — The arteries supplying the submaxillary gland are branches 
 of the facial and lingual. Its veins follow the course of the arteries. The lymph- 
 .atics drain into the submaxillary lymph -glands. There are no lymphatic glands 
 in this salivary gland. The nerves are derived from the submaxillary ganglion, 
 through which it receives filaments from the chorda tympani of the facial and 
 from the lingual branch of the inferior maxillary, sometimes from the mylo-hyoid 
 branch of the inferior dental, and from the sympathetic. 
 
 The Sublingual Gland {glandula sublingualis) (Fig. 820). — The sublingual 
 gland is the smallest of the salivary glands. It is situated beneath the mucous 
 membrane of the floor of the mouth, at the side of the fraenum linguae, in contact 
 with the inner surface of the lower jaw, close to the symphysis. It is narrow, 
 flattened, in shape somewhat like an almond, and weighs about a drachm. It 
 is in relation, above, with the mucous membrane; below, with the Mylo-hyoid 
 muscle; in front, with the depression on the side of the symphysis of the lower 
 jaw, and with its fellow of the opposite side; behind, with the deep part of the 
 submaxillary gland; and internally, with the Genio-hyo-glossus, from which it 
 is separated by the lingual nerve and Wharton's duct. Its excretory ducts or 
 ducts of Rivinus (ductus sublingualis minores) are from eight to twenty in number. 
 
 Crescent of Gianuzsi. 
 
 /^olivary duct. 
 
 Fig. 821. — A highly magnified section of the submaxillary giand of the dog, stained with carmine. (Kolliker.) 
 
 They open separately into the mouth back of Wharton's duct and upon a fold 
 of mucous membrane known as the plica sublingualis. The plica sublingualis is 
 an elevated crest of mucous membrane caused by the projection of the gland on 
 either side of the fraenum linguae. One or more ducts sometimes join to form 
 a tube which opens into the Whartonian duct or remains independent, opening 
 close to Wharton's duct on the sublingual papilla. This single duct is called 
 the duct of Bartholin (ductus sublingualis major). 
 
 Vessels and Nerves. — The sublingual gland is supplied with blood from the 
 sublingual and submental arteries. Its nerves are derived from the lingual. 
 
 Structure of Salivary Glands (Fig. 821). — The salivary glands are compound 
 racemose glands, consisting of numerous lobes, which are made up of smaller 
 lobules connected together by dense areolar tissue, vessels, and ducts. Each 
 lobule consists of the ramifications of a single duct, dividing frequently like the 
 branches of a tree, the branches terminating in dilated ends or alveoli, on which 
 the capillaries are distributed. These alveoli, however, as Pfliiger points out, 
 are not necessarily spherical, though sometimes they assume that form; some- 
 times they are perfectly cylindrical, and very often they are mutually com- 
 pressed. The alveoli are enclosed by a basement membrane which is continuous 
 with the membrana propria of the duct. It presents a peculiar reticulated 
 
 77 
 
1218 THE ORGANS OF DIGESTION 
 
 structure, having the appearance of a basket with open meshes, and consisting 
 of a network of branched and flattened nucleated cells. 
 
 The alveoli of the salivary glands are of two kinds, which differ both in the 
 appearance of their secreting cells, in their size, and in the nature of their secre- 
 tion. The one variety secretes a ropy fluid which contains mucin, and such 
 alveoli have therefore been named the mucous alveoli, whilst the other secretes a 
 thinner and more watery fluid, which contains serum-albumin, and alveoli of 
 this variety have been named serous or albuminous alveoli. The sublingual gland 
 may be regarded as an example of the former variety, the parotid of the latter. 
 The submaxillary is of the mixed variety, containing both mucous and serous 
 alveoli, the latter, however, preponderating. 
 
 Both varieties of alveoli are lined by cells, and it is by the character of these 
 cells that the nature of the gland is chiefly to be determined. In addition, how- 
 ever, the alveoli of the serous glands are smaller than those of the mucous ones. 
 
 The Mucous Alveoli. — The cells in the mucous alveoli are spheroidal in shape, 
 glassy, transparent, and dimly striated in appearance. The nucleus is usually 
 situated in the part of the cell which is next the basement membrane, against 
 which it is sometimes flattened. The most remarkable peculiarity presented by 
 these cells is, that they give off an extremely fine process which is curved in a 
 direction parallel to the surface of the alveolus, lies in contact with the membrana 
 propria, and overlaps the process of neighboring cells. The cells contain a quan- 
 tity of mucin, to which their clear, transparent appearance is due. 
 
 Here and there in the alveoli are seen peculiar half-moon-shaped bodies lying 
 between the cells and the membrana propria of the alveolus. They are termed 
 the crescents of Gianuzzi or the demilunes of Heidenhain (Fig. 821), and are com- 
 posed of polyhedral granular cells, which Heidenhain regards as young epithelial 
 cells destined to supply the place of those salivary cells which have undergone 
 disintegration. This view, however, is not accepted by Klein. 
 
 Serous Alveoli. — In the serous alveoli the cells almost completely fill the cavity, 
 so that there is hardly any lumen perceptible. Instead of presenting the clear, 
 transparent appearance of the cells of the mucous alveoli, they present a granular 
 appearance, due to distinct granules of an albuminous nature embedded in a closely 
 reticulated protoplasm. The ducts which originate from the alveoli are lined at 
 their commencement by epithelium which differs little from the pavement type. 
 As the ducts enlarge, the epithelial cells change to the columnar type, and the part 
 of the cells next the basement-membrane is finely striated. The lobules of the 
 salivary glands are richly supplied with blood-vessels which form a dense network 
 in the interalveolar spaces. Fine plexuses of nerves are also found in the inter- 
 lobular tissue. The nerve-fibrils pierce the basement-membrane of the alveoli, 
 and end in branched varicose filaments between the secreting cells. There is no 
 doubt that ganglia are to be found in some salivary glands in connection with the 
 nerve-plexuses in the interlobular tissue; they are to be found in the submaxillary, 
 but not in the parotid. 
 
 In the submaxillary and sublingual glands the lobes are larger and more loosely 
 united than in the parotid. 
 
 Mucous Glands. — Besides the salivary glands proper, numerous other glands 
 are found in the mouth. They appear to secrete mucus only, which serves to keep 
 the mouth moist during the intervals of the salivary secretion, and which is mixed 
 with that secretion in swallowing. Many of these glands are found at the posterior 
 part of the dorsum of the tongue, behind the circumvallate papillae, and also along 
 its margins as far forward as the apex.^ Others lie around and in the tonsil 
 
 ' It has been shown by Ebner that many of these glands open into the trenches around the circumvallate 
 papillae, and that their secretion is more watery than that of ordinary mucou's glands. He supposes that they 
 assist in the more rapid distribution of the substance to be tasted over the region where the special apparatus of 
 the sense of taste is situated. — Ed. of 15th English edition. 
 
THE SALIVARY GLANDS 1219 
 
 between its crypts, and a large number are present in the soft palate. These 
 glands are of the ordinary compound racemose type. Behind the tip of the 
 tongue on each side, external to the anterior extremity of the genio-glossus muscle, 
 is a mucous gland, the gland of Nuhn and Blandin {glandula lingualis anterior). 
 Its lower surface is partly covered by muscular fibres from the inferior lingualis 
 and styloglossus muscles, and it opens by several ducts. 
 
 Surface Form. — The orifice of the mouth is bounded by the lips, two thick, fleshv folds 
 covered externally by integument and internally by mucous membrane, and consisting of 
 muscles, vessels, nerves, areolar tissue, and numerous small glands. The size of the orifice of 
 the mouth varies considerably in different individuals, but seems to bear a close relation to the 
 size and prominence of the teeth. Its corners correspond pretty accurately to the outer border 
 of the canine teeth. In the Ethiopian tribes the front teeth are large and inclined for- 
 ward, the mouth is large; and this, combined with the thick and everted lips which appear to 
 be associated with prominent teeth, gives to the negro's face much of the peculiarity by which 
 it is characterized. The smaller teeth and the slighter prominence of the alveolar arch of the 
 more highly civilized races render the orifice of the mouth much smaller, and thus a small 
 mouth is an indication of intelligence, and is regarded as an evidence of the higher civilization 
 of the individual. 
 
 Upon looking into the mouth, the first thing we may note is the tongue, the upper surface 
 of which will be seen occupying the floor of the cavity. This surface is convex, and is marked 
 along the middle line by a raphe which divides it into two symmetrical portions. The anterior 
 two-thirds is rough and studded with papillae; the posterior third smooth and tuberculated, 
 and covered by numerous glands which project from the surface. Upon raising the tongue 
 the mucous membrane which invests the upper surface may be traced covering the sides of the 
 under surface, and then reflected over the floor of the mouth on to the inner surface of the 
 lower jaw, a part of which it covers. As it passes over the borders of the tongue it changes its 
 character, becoming thin and smooth and losing the papillae which are to be seen on the upper 
 surface. In the middle line the mucous membrane on the under surface of the tip of the tongue 
 forms a distinct fold, the jraenum linguae, by which this organ is connected to the symphysis 
 of the jaw. Occasionally it is found that this fraenum is rather shorter than natural, and, 
 acting as a bridle, prevents the complete protrusion of the tongue. When this condition exists 
 and an attempt is made to protrude the organ, the tip will be seen to remain buried in the 
 floor of the mouth, and the dorsum of the tongue is rendered very convex, and more or less 
 extruded from the mouth; at the same time a deep furrow will be noticed to appear in the 
 middle line of the anterior part of the dorsum. Sometimes, a little external to the fraenum, 
 the ranine vein may be seen immediately beneath the mucous membrane. The corresponding 
 artery, being more deeply placed, does not come into view, nor can its pulsation be felt with the 
 finger. On either side of the fraenum, in the floor of the mouth, is a longitudinally elevation or 
 ridge, produced by the projection of the sublingual gland, which lies immediately beneath the 
 mucous membrane. And close to the attachment of the fraenum to the tip of the tongue may 
 be seen on either side the slit-like orifices of Wharton's ducts, into which a fine probe may be 
 passed without much diflUculty. By everting the lips the smooth mucous membrane lining them 
 may be examined, and may be traced from them on to the outer surface of the alveolar arch. 
 In the middle line, both of the upper and lower lip, a small fold of mucous membrane passes 
 from the lip to the bone, constituting the fraena; these are not so large as the fraenum linguae. 
 By pulling outward the angle of the mouth, the mucous membrane lining the cheeks can be 
 seen, and on it may be perceived a little papilla which marks the position of the orifice of Sten- 
 son's duct — the duct of the parotid gland. The exact position of the orifice of the duct will be 
 found to be opposite the second molar tooth of the upper jaw. The introduction of a probe 
 into this duct is attended with considerable difficulty. The teeth are the next objects which 
 claim our attention upon looking into the mouth. These are, as stated above, ten in either jaw 
 in the temporary set, and sixteen in the permanent set. The gums, in which they are implanted, 
 are dense, firm, and vascular. 
 
 At the back of the mouth is seen the isthmus of the fauces, or, as it is popularly called, " the 
 throat:" this is the space between the pillars of the fauces on either side, and is the means 
 by which the mouth communicates with the pharynx. Above, it is bounded by the soft palate, 
 the anterior surface of which is concave and covered with mucous membrane, which is con- 
 tinuous with that lining the roof of the mouth. Projecting downward from the middle of 
 its lower border is a conical-shaped projection, the uvula. On either side of the isthmus of the 
 fauces are the anterior and posterior pillars, formed by the Palato-glossus and Palato-pharyn- 
 geus muscles respectively, covered over by mucous membrane. Between the two pillars on either 
 side is situated the tonsil. The extirpation of this body is not unattended with danger of 
 hemorrhage. Dr. Weir has stated that he believes that when hemorrhage occurs after their 
 removal it arises from one of the palatine arteries having been wounded. These vessels are 
 
1220 THE ORGANS OF DIGESTION 
 
 large: they lie in the muscular tissue of the palate, and when wounded are constantly exposed 
 to disturbance from the contraction of the palatine muscles. The vessels of the tonsil, Dr. Weir 
 states, are small and lie in the soft tissue, and readily contract when wounded. 
 
 When the mouth is wide open a prominent tense fold of mucous membrane may be seen and 
 felt, extending upward and backward from the position of the fang of the last molar tooth 
 to the posterior part of the hard palate. This is caused by the pterycjo-maxillary ligament, 
 which is attached by one extremity to the apex of the internal pterygoid plate, and by the other 
 to the posterior extremity of the mylo-hyoid ridge of the lower jaw. It connects the Buccinator 
 with the Superior constrictor of the pharynx. The fang of the last molar tooth indicates the 
 position of the lingual (gustatory) nerve where it is easily accessible, and can with readiness 
 be divided in cases of cancer of the tongue (see page 1043). On the inner side of the last molar 
 tooth we can feel the hamular process of the internal pterygoid plate of the sphenoid bone, 
 around which the tendon of the Tensor palati plays. The exact position of this process is of 
 importance in performing the operation of staphylorrhaphij. About one-third of an inch in 
 front of the hamular process, and the same distance directly inward from the last molar tooth, 
 is the situation of the opening of the posterior palatine canal, through which emerges the pos- 
 terior or descending palatine branch of the internal maxillary artery and one of the descending 
 palatine nerves from Meckel's ganglion. The exact position of the opening on the subject may 
 be ascertained by driving a needle through the tissues of the palate in this situation, when it 
 will be at once felt to enter the canal. The artery emerging from the opening runs forward in a 
 groove in the bone just internal to the alveolar border of the hard palate, and may be wounded 
 in the operation for the cure of cleft palate. Under these circumstances the palatine canal may 
 require plugging. By introducing the finger into the mouth the anterior border of the coronoid 
 process of the jaw can be felt, and it is especially prominent when the jaw is dislocated. By 
 throwing the head well back a considerable portion of the posterior wall of the pharynx may be 
 seen through the isthmus faucium, and on introducing the finger the anterior surface of the 
 bodies of the upper cervical vertebrae may be felt immediately beneath the thin muscular 
 stratum forming the wall of the pharynx. The finger can be hooked around the posterior 
 border of the soft palate, and by turning it forward the posterior nares, separated by the 
 septum, can be felt, or the presence of any adenoid or other growths in the naso-pharynx can 
 be ascertained. 
 
 THE PHARYNX (Figs. 818, 824, 825). 
 
 The pharynx (from (fdf)irf^, the throat) is that part of the ahmentary canal 
 which is placed behind and communicates with the nose, mouth, and larynx. It 
 is a musculo-membranous tube, somewhat conical in form, with the base upward 
 and the apex downward, extending from the under surface of the skull to the level 
 of the cricoid cartilage in front and that of the intervertebral disk between the fifth 
 and sixth cervical vertebrae behind. 
 
 The pharynx is about four inches and a half in length, and broader in the trans- 
 verse than in the antero-posterior diameter. Its greatest breadth is opposite the 
 cornua of the hyoid bone; its narrowest point, at its termination in the oesophagus. 
 It is attached, above, to the periosteum of the petrous portion of the temporal 
 bone and of the basilar process of the occipital bone. To the pharyngeal tubercle 
 of the basilar process of the occipital bone the raphe of the Constrictor muscles is 
 attached. It is bounded above by the body of the sphenoid as well as by the basilar 
 process of the occipital; below, \i is continuous with the oesophagus; 'posteriorly, it 
 is connected by. loose areolar tissue with the cervical portion of the vertebral 
 column and the Longi colli and Recti capitis antici muscles; this areolar tissue is 
 contained in what is called the retro-pharyngeal space (spatia retropharyngeus) ; 
 anteriorly, it is incomplete, the gap being occupied by the cavities of the nose, 
 mouth, and larynx. Anteriorly, it is attached in succession to the Eustachian tube, 
 the internal pterygoid plate, the pterygo-maxillary ligament, the posterior termi- 
 nation of the mylo-hyoid ridge of the lower jaw, the mucous membrane of the 
 mouth, the base of the tongue, hyoid bone, the thyroid and cricoid cartilages; 
 laterally, it is connected to the styloid processes and their muscles, and is in con- 
 tact with the common and internal carotid arteries, the internal jugular veins, 
 and the glosso-pharyngeal, pneumogastric, hypoglossal, and sympathetic nerves, 
 and above with a small part of the Internal pterygoid muscles. When the pharynx 
 
THE PHARYNX 
 
 1221 
 
 is at rest the anterior and posterior walls are near together. Above the larynx 
 they do not come in contact, but leave a channel for air; below the larynx they 
 lie in contact, but open for the passage of food. It has seven openings com- 
 municating with it — the two posterior nares, the two Eustachian tubes, the 
 mouth, larynx, and oesophagus. The pharynx may be subdivided from above 
 downward into three parts, nasal, oral, and laryngeal. 
 
 The Nasal Part {pars nasalis pharyngis) (Fig. 824) . — The nasal part of the 
 pharynx or naso-phar3mx lies behind the nose and above the level of the soft palate; 
 it differs from the two lower parts of the tube in that its cavity always remains 
 patent. In front it communicates through the posterior nares (choanae) (Fig. 825) 
 with the nasal fossae. On its lateral wall is the pharyngeal orifice of the Eustachian 
 tube (ostium pharyngeum tubae auditivae) (Figs. 822 and 823) , which presents the 
 appearance of a vertical or triangular cleft bounded above and behind by a firm 
 prominence. The anterior portion of the prominence (/a6 mm anterius)\s the smaller 
 portion. The posterior portion {labium posterius) is large and thick, is called the 
 Eustachian cushion {torus tubarius), and is caused by the inner extremity of the caf*- 
 tilage of the tube impinging on the deep surface of the mucous membrane (Fig.823). 
 A vertical fold of mucous membrane, the salpingo-pharyngeal fold {plica salpingo- 
 
 ORIFICE OF 
 EUSTACHIAN 
 
 I TUBE 
 
 § PHARYNGEAL 
 
 SALPINGO- 
 
 NASAL FOLD 
 
 EUSTACHIAN 
 
 CUSHION 
 
 SALPINGO-. 
 PALATINE FOLD 
 
 Fig. 822. — Pharyngeal tonsil in an adult. 
 (Escat.) 
 
 Fig. 823. 
 
 SALPINGO-PHARYN- 
 GEAL FOLD 
 
 -The posterior lateral cavity of the naso- 
 pharynx. (Escat). 
 
 pharyngea) (Fig. 823), stretches from the lower part of the cushion to the pharynx; 
 it contains the Salpingo-pharyngeus muscle. A second and smaller mucous fold 
 may be seen stretching from the upper part of the cushion to the palate, the 
 salpingo-palatine fold (plica salpingopalatina) (Fig. 823) . Behind the orifice of the 
 Eustachian tube is a deep recess, the lateral recess or fossa of Rosenmiiller (recessus 
 pharyngeus) (Fig. 823), which represents the remains of the upper part of the sec- 
 ond branchial cleft. The posterior wall of the naso-pharynx is directed upward and 
 forward, and it meets the superior wall at an angle. This rounded area of meet- 
 ing is the vault of the pharynx (fornix pharyngis). On the posterior wall, at the 
 level and above the level of the orifices of the Eustachian tubes, there is a col- 
 lection of lymphoid tissue. This is particularly marked in children, and almost 
 or quite disappears in the aged. Over it the mucous membrane is thick and 
 in folds. This collection of lymphoid tissue is the pharyngeal tonsil {tonsilla 
 pharyngea) (Fig. 822) . The naso-pharynx communicates with the oral pharynx 
 through an aperture between the soft palate and the posterior pharyngeal wall. 
 This aperture is the isthmus of the pharynx (isthmus pharyngonasalis). 
 
 The Oral Part (pars oralis pharyngis). — The oral part of the pharynx reaches 
 from the soft palate to the level of the hyoid bone. It opens anteriorly, through 
 the isthmus faucium, into the mouth, while in its lateral wall, between the two 
 
1222 
 
 THE ORGANS OF DIGESTION 
 
 pillars of the fauces, is the tonsil. A triangular area on the lateral wall is known as 
 the sinus tonsillaris (Fig. 824). It is bounded anteriorly by the anterior palatine 
 arch, posteriorly by the posterior palatine arch, and below by the side of the 
 pharyngeal portion of the tongue. 
 
 The LarjOlgeal Part {'pars laryngea pharyngis). — The laryngeal part of the 
 pharynx is that division which lies behind the larynx ; it is wide above where it is con- 
 tinuous with the oral portion while below at the lower border of the cricoid cartilage 
 it becomes continuous with the oesophagus. In front it presents the triangular 
 aperture of the larynx, the base of which is directed forward and is formed by the 
 epiglottis, while its lateral boundaries are constituted by the aryteno-epiglottidean 
 folds. On either side of the laryngeal orifice is a recess, termed the sinus pyri- 
 
 OPENING OF 
 
 8TENSON-S 
 
 DUCT 
 
 GCNIO- 
 HYOGLOSSUS 
 
 MUSCLE 
 
 PHARYNGEAL 
 BURSA 
 
 ORIFICE OF 
 EUSTACHIAN TUBE 
 
 PHARYNGEAL 
 TONSIL 
 
 SOFT PALATE 
 NASOPHARYNX 
 
 ANTERIOR PALA- 
 TINE ARCH 
 POSTERIOR PALA- 
 TINE ARCH 
 TONSIL 
 CAVITY OF 
 PHARYNX 
 TONSILLAR 
 SINUS 
 
 POSTERIOR PALA.' 
 TINE ARCH 
 
 EPIGLOTTIS 
 
 SINUS 
 
 PYRIFORMIS. 
 
 ARYTENO- 
 
 EPIGLOTTIC 
 
 FOLD 
 
 CUNEIFORMI 
 
 CARTILAGE 
 
 ARYTENOID- 
 CARTILAGE 
 
 OESOPHAGUS 
 
 RING OF 
 TRACHEA 
 
 Fig. 824. — Sagittal median section of the head and neck. The head i.s thrown backward into complete extension, 
 which explains the relations between the lower jaw and the hyoid bone as seen in the figure. (Luschka.) 
 
 formis (recessus piriformis) (Fig. 824) ; it is bounded internally by the aryteno- 
 epiglottidean fold, externally by the thyroid cartilage and thyro-hyoid membrane. 
 In the anterior part of the sinus pyriformis is a fold (plica nervi laryngei), which 
 passes downward and inward. Extending outward from the epiglottis on each 
 side is a fold, the pharjmgo-epiglottic fold (plica pharyngoepigloitica). This ascends 
 in the lateral wall of the pharynx, nearly to the posterior arch of the fauces. 
 
 Structure. — The constrictors of the pharynx (see p. 400) are surrounded by 
 a sheath of thin fascia, the bucco-pharyngeal fascia (Cunningham). Forward pro- 
 
THE PHARYNX 
 
 1223 
 
 longations of this fascia overlay the Buccinator muscles. The connective tissue of 
 the retro-pharyngeal space joins the bucco-pharyngeal fascia to the prevertebral 
 fascia, and it is attached by areolar tissue to the other structures to which the 
 pharynx is in contact (Cunningham). The pharynx is composed of three coats 
 — fibrous, mucous and muscular. 
 
 The Pharyngeal Aponeurosis or Fibrous Coat is situated between the mucous 
 and muscular layers. It is thick above, where the muscular fibres are wanting, and 
 is firmly connected to the periosteum of the basilar process of the occipital and 
 petrous portion of the temporal bones. It is united to the Eustachian tube, pos- 
 terior nares, and other points which the pharynx joins. It is thicker above than 
 below, and above the sinuses of Alorgagni there is no muscular coat, and the wall 
 
 Fig. 825. — The anterior suilacu m i ue i^hiirynx. (Sappcy.) 
 
 of the pharynx is composed of aponeurosis and mucous membrane. As it descends 
 it diminishes in thickness, and is gradually lost. It is strengthened posteriorly by 
 a strong fibrous band which is attached above to the pharyngeal spine on the under 
 surface of the basilar portion of the occipital bone, and passes downward, forming 
 a median raphe, which gives attachment to the Constrictor muscles of the pharynx. 
 The Mucous Coat {tunica mucosa).— The mucous coat is continuous with that 
 lining the Eustachian tubes, the nares, the mouth, and the larynx. In the naso- 
 pharynx it is covered by columnar ciliated epithelium ; in the buccal and laryngeal 
 portions the epithelium is of the s(|uamous variety. Beneath the mucous membrane 
 are found racemose mucous glands (glandulae pharyngeae); they are especially 
 numerous at the upper part of the pharynx around the orifices of the Eustachian 
 tubes. Throughout the pharynx are also numerous crypts or recesses, the walls 
 
1224 THE ORGANS OF DIGESTION 
 
 of which are surrounded by lymphoid tissue similar to that found in the tonsils. 
 Across the back part of the pharyngeal cavity, between the two Eustachian tubes, 
 a considerable mass of this tissue exists, and has been named the pharyngeal tonsil 
 (Fig. 822). Above, this in the middle line is an irregular, flask-shaped depres- 
 sion of the mucous membrane, extending up as far as the basilar process of the 
 occipital bone. It is known as the pharjmgeal bursa (bursa pharyngea) , and was 
 regarded by Luschka as the remains of the diverticulum, which is concerned in 
 the development of the anterior lobe of the pituitary body. Other anatomists 
 believe that it is connected with the formation of the pharyngeal tonsils. The 
 muscular coat (tunica muscularis fharyngis) has been already described (p. 400). 
 The sinuses of Morgagni, referred to on a previous page (p. 402 and Fig. 277), 
 are intervals between the Superior constrictor muscles and the basilar process 
 of the occipital bone. 
 
 The Lymphatic Pharyngeal Ring. — This name was applied by Waldeyer to the 
 lymphatic structure gathered into a sort of ring about the pharynx. There are 
 three chief collections of this tissue on each side. The first is known as the lingual 
 tonsil (p. 1088); the second as the palatine tonsil (p. 1212); and the third as the 
 pharyngeal tonsil (p. 1221). 
 
 Surgical Anatomy of the Mouth, Cheeks, Lips, Gums, Tonsils, Palate, Salivary Glands, 
 and Pharynx. — The duct of a salivary gland may be blocked by a calculus, and the condition 
 is often productive of severe pain. 
 
 A wound of Stenson's duct or of the parotid gland may be followed by a salivary -fistula. 
 
 The parotid recess is completely lined by fascia, excej)t above. "Between the anterior edge 
 of the styloid process and the posterior border of the external pterygoid muscle there is a gap 
 in the fascia, through which the parotid space communicates with the connective tissue about 
 the pharynx."' 
 
 This explains why there is frequently swelling of the parotid region in post-pharyngeal abscess. 
 A parotid abscess rarely bursts through the skin; it may pass into the temporal fossa, may 
 enter the zygomatic fossa, may advance toward the mouth, pharynx, or neck. Because of the 
 situation of thi gland, a parotid abscess may cause inflammation of the temporo-mandibular 
 joint or periostitis of the bone about the meatus, and may even burst into the external auditory 
 meatus (Treves). 
 
 The facial nerve passes through the gland, and inflammation or tuberculosis of the gland 
 may cause facial palsy. Some enlargements of the parotid region are due to inflammation of 
 the parotid lymph-glands, and these glands may become tuberculous. 
 
 Mumps is characterized by acute inflammation of the parotid gland. 
 
 Various tumors occur in the parotid (fibroma, sarcoma, carcinoma, enchondroma, etc.). 
 Most parotid tumors contain more or less cartilage. Complete extirpation of the parotid gland 
 surgically is certainly extremely difficult, and Treves and others maintain that it is impossible. 
 
 Ranula is a salivary cyst of the floor of the mouth, due to occlusion of ducts of the sublingual 
 gland or the duct of the submaxillary gland. Mucous cysts occur in the mouth. A mucous cyst 
 of the gland of Nuhn and Blandin is on the under surface of the tongue near the apex. A 
 dermoid cyst of the base of the tongue is occasionally encountered. It is of congenital origin. 
 
 What is known as the sublingual bursa is an epithelial-lined space, said to exist between 
 the mucous membrane of the floor of the mouth and the Genio-hyo-glossus muscle. When 
 acutely inflamed, it produces rapidly a marked swelling called acute ranula. Incomplete 
 closure of the oral end of the thyro-glossal duct causes thyro-glossal fistula. If the oral end closes, 
 but a portion of the duct below remains unobliterated, a thyro-glossal cyst forms. Such a cyst 
 or fistula is always in the median line. The reader will remember that this duct runs from the 
 foramen caecum to the isthmus of the thyroid gland. 
 
 Hare-lip is considered on pp. 110 and 111. 
 
 The lower lip, more commonly than any other structure, gives origin to cancer. The upper 
 lip is not nearly so often affected. Blocking of mucous glands of the lips causes mucous cysts. 
 A scar of the lip or about the lip disturbs this structure and pulls it far out of place. Thus 
 great deformity is produced. Burns particularly induce hideous cicatricial contraction. 
 
 Plastic operations in this region are often successful, because of the great vascularity of the 
 parts, and because adjacent parts admit of being stretched and pulled in. 
 
 Cleft palate is a by no means rare congenital deformity. The cleft is in the middle line. 
 It may be a mere cleft of the uvula, it may be limited to the soft palate, or it may involve 
 
 ' Applied Anatomy. By Sir Frederick Treves. 
 
THE OESOPHAGUS 1225 
 
 the hard palate to but not including the alveolus. It may pass through the alveolus, but if it 
 does so it ceases to be median at this point, and follows the line of suture between the incisive 
 bone and the superior maxillary (pp. 110 and 111). In a complete cleft palate there is apt 
 to be hare-lip at the end of the palate cleft. This cleft in the lip is not median, but is at the 
 termination of the palate cleft. If the cleft of a cleft palate runs along each side of the 
 incisive bone, the bone is isolated from the superior maxillary. In such a case double hare-lip 
 results. 
 
 When a tonsil enlarges it projects inward. The deafness which so often attends hypertrophy 
 of the tonsil is not due to blocking of the Eustachian orifice by the tonsil, but is due to thicken- 
 ing of the mucous membrane lining the tube itself. The profuse bleeding which sometimes 
 follows an operation for the removal of the tonsil is very seldom due to injury of the internal 
 carotid artery, but is due to injury of the ascending pharyngeal artery (p. 621) or one of the 
 palatine arteries. 
 
 The internal carotid artery is in close relation with the pharynx, so that its pulsations can 
 be felt through the mouth. It has been occasionally wounded by sharp-pointed instruments 
 introduced into the mouth and thrust through the wall of the pharynx. In aneurism of this 
 vessel in the neck the tumor necessarily bulges into the pharynx, as this is the direction in 
 which it meets with the least resistance, nothing lying between the vessel and the mucous 
 membrane except the thin Constrictor muscle, whereas on the outer side there is the dense 
 cervical fascia, the muscles descending from the styloid process, and the margin of the Sterno- 
 mastoid muscle. 
 
 The mucous membrane of the pharynx is very vascular, and is often the seat of inflamma- 
 tion, frequently of a septic character, and dangerous on account of its tendency to spread to the 
 larynx. On account of the tissue which surrounds the pharyngeal wall being loose and lax, the 
 inflammation is liable to spread through it far and wide, extending downward into the posterior 
 inediastinum along the oesophagus. Abscess may form in the connective tissue behind the 
 pharynx, between it and the vertebral column, constituting what is known as retro-pharyngeal 
 abscess. This is most commonly due to caries of the cervical vertebrae, but may also be caused 
 by suppuration of a lymphatic gland which is situated in this position opposite the axis, and 
 which receives lymphatics from the nares, or by gumma or by acute pharyngitis. In these 
 cases the pus may be easily evacuated by an incision, with a guarded bistoury, through the 
 mouth, but, for aseptic reasons, it is desirable that the abscess should be opened from the neck. 
 In some instances this is perfectly easy; the abscess can be felt bulging at the side of the neck 
 and merely requires an incision for its relief; but this is not always so, and then an incision 
 should be made along the posterior border of the Sterno-mastoid and the deep fascia should 
 be divided. A director is now to be inserted into the wound, the forefinger of the left hand 
 being introduced into the mouth and pressure made upon the swelling. This acts as a guide, 
 and the director is to be pushed onward until pus appears in the groove. A pair of sinus forceps 
 are now inserted along the director and the opening into the cavity dilated. 
 
 Foreign bodies not infrequently become lodged in the pharynx and most usually at its termi- 
 nation at about the level of the cricoid cartilage, just beyond the reach of the finger, as the 
 distance from the arch of the teeth to the commencement of the oesophagus is about six inches. 
 
 Hypertrophy of the adenoid tissue of the naso-pharynx produces groups of hypertrophic 
 masses known as adenoids. A child with adenoids has a cough, and when awake or asleep, 
 breathes noisily and with the mouth open. The voice is muffled, the hearing is impaired, the 
 expression is vacant, the mind is dull, and the tonsils are enlarged. 
 
 THE OESOPHAGUS (Figs. 826, 827, 828, 829). 
 
 The oesophagus (ouo, ocom, I carry; (fayelh, to eat) or gullet is a muscular 
 canal, averaging about nine or ten inches in length, extending from the pharynx 
 to the stomach. It commences at the upper border of the cricoid cartilage, oppo- 
 site the intervertebral disk between the fifth and sixth cervical vertebrae descends, 
 along the front of the spine through the posterior mediastinum, passes through 
 the Diaphragm, and, entering the abdomen, terminates in the stomach wall at the 
 point known as the cardia opposite the tenth dorsal vertebra or possibly opposite 
 the intervertebral disk between the tenth and eleventh dorsal vertebrae. The 
 general direction of the oesophagus is vertical, but it presents two or three slight 
 curves in its course. At its commencement it is placed in the median line, but 
 it inclines to the left side as far as the root of the neck, gradually passes to the 
 middle line again, and finally again deviates to the left as it passes forward to 
 
1226 
 
 THE ORGANS OF DIGESTION 
 
 the oesophageal opening of the Diaphragm {hiatus oesophageus) . The oesophagus 
 also presents an antero-posterior flexure, corresponding to the curvature of the 
 cervical and thoracic portions of the spine. It is the narrowest part of the alimen- 
 tary canal, being most contracted at its commencement and at the point where 
 it passes through the Diaphragm. 
 
 The diameter of the largest portion of the oesophagus where it is contracted is 
 about half an inch; when it is fully dilated, an inch or even more. 
 
 In the neck the oesophagus, when at rest, is flattened, the anterior and posterior 
 walls approaching each other. The canal in the neck is round or oval, and the 
 lumen is stellate (Cunningham). The oesophagus is somewhat constricted at three 
 points. One constriction is at the very beginning of the tube; another is where 
 the left bronchus crosses it; another is at the point where the oesophagus passes 
 through the Diaphragm. The tube at each constricted point is distinctly flattened. 
 The diameter of each of these constricted parts is slightly under one-half inch, 
 the diameter of the rest of the tube when contracted is one-half inch, but when 
 dilated may reach or exceed one inch. The average distance from the upper 
 
 AZYGOS VeiN 
 
 ^ ARTERY 
 
 BRONCHUS 
 
 PULMONARY 
 
 'CESOPHAGUS 
 
 Fig. 826. — Pleural cul-de-sac of the posterior mediastinum. 
 
 incisor teeth to the beginning of the gullet is about six inches; the average dis- 
 tance from the incisor teeth to the cardiac opening of the stomach is fifteen or 
 sixteen inches. The portion of the oesophagus which is in the neck is called 
 the cervical portion (pars cervicalis) ; the portion in the thorax, the thoracic portion 
 (pars thoracalis), and the portion which lies in the oesophageal opening of the 
 Diaphragm, the diaphragmatic portion. The margin of the oesophageal orifice is 
 narrow in front, thicker behind and to the sides. Behind and to the sides the 
 diaphragmatic portion of the oesophagus is about half an inch in length. In 
 front there is only a thin edge of Diaphragm in contact with the gullet. The 
 oesophagus is connected to the margins of the diaphragmatic orifice by connec- 
 tive tissue. The so-called abdominal portion of the oesophagus (pars ahdominalis) 
 is not over half an inch in length, and is limited to the small portion of the ante- 
 rior and left lateral surface observed when a stomach which is completely 
 empty is drawn downward with considerable force. The abdominal portion of 
 the oesophagus is covered with peritoneum; the corresponding portions of the 
 right lateral and posterior walls are not covered by peritoneum. This uncov- 
 ered portion of the oesophagus runs downward and to the left and lies directly 
 
THE OESOPHAGUS 
 
 1227 
 
 behind the oesophageal groove on the posterior surface of the left lobe of the 
 liver, but does not actually touch the groove, which in reality holds the thick, 
 right edge of the oesophageal opening of the Diaphragm. When the stomach is 
 distended the abdominal portion of the gullet ceases to exist and becomes part 
 of the stomach wall. 
 
 Relations. — In the neck the oesophagus is in relation, in front, with the trachea, 
 and it is connected to the posterior wall of the trachea by areolar tissue. At the 
 lower part of the neck, where it projects to the left 
 side, it is in relation in front with the thyroid gland 
 and thoracic duct; behind, it rests upon the vertebral 
 column and Longi colli muscles; on each side, it is in 
 relation with the common carotid artery (especially the 
 left, as the gullet inclines to that side) and part of the 
 lateral lobes of the thyroid gland; the recurrent laryn- 
 ijeal nerves ascend between it and the trachea. 
 
 In the thorax, it is at first situated a little to the left 
 of the median line; it then passes behind the aortic 
 arch, being separated from it by the trachea, and de- 
 scends in the posterior mediastinum, along the right 
 side of the aorta, nearly to the Diaphragm, where it 
 passes in front and a little to the left of the artery, 
 previous to entering the abdomen. It is in relation, 
 in front, with the trachea, the arch of the aorta, the 
 left common carotid and left subclavian arteries, which 
 incline toward its left side, the left bronchus, the 
 pericardium, and the Diaphragm; behind, it rests 
 upon the vertebral column, the Longi colli muscles, 
 the right intercostal arteries, and the vena azygos 
 minor; and below, near the Diaphragm, upon the front 
 of the aorta; laterally, it comes in contact with both 
 pleurae, especially with the left pleura above and the 
 right pleura below; it overlaps the vena azygos major, 
 which lies on its right side, while the descending aorta 
 is placed on its left side. The pneumogastric nerves 
 descend in close contact with it, the right nerve pass- 
 ing down behind, and the left nerve in front of it, each 
 nerve spreading out into a plexus, the oesophageal 
 plexus, around the tube. The two jjlexuses are joined 
 to each other. The right nerve forms the posterior 
 oesophageal plexus (plexus oesophageus poterior) ; 
 the left nerve the anterior oesophageal plexus (plexus 
 oesophageus anterior). 
 
 In the lower part of the posterior mediastinum the 
 thoracic duct lies to the right side of the oesophagus ; higher up, it is placed 
 behind it, and, crossing about the level of the fourth dorsal vertebra, is continued 
 upward on its left side. 
 
 Above the aortic arch and the arch of the great azygos vein above the root 
 of the right lung, the pleurae are close to but not in actual contact with the 
 oesophagus. 
 
 Below the arch of the great azygos vein the right side of the oesophagus is 
 covered with pleura nearly to the diaphragmatic opening. The posterior surface 
 of the gullet also may be covered with pleura. Below the arch of the aorta on 
 the left side the pleura covers only a small portion of the oesophagus, that is, a 
 portion of the left wall, a little above the diaphragmatic opening. 
 
 Fig. 827. — The supports of the 
 oesophagus at the aorta in an in- 
 fant. (Poirier and Charpy.) 
 
122S 
 
 THE ORGANS OF DIGESTION 
 
 Anomalies. — There may be openings of the oesophagus into the trachea. A 
 diverticulum or pressure pouch may exist. Such a pouch is usually placed upon 
 the posterior wall near the pharynx. There may be congenital constriction, tubular 
 or annular. 
 
 Structure. — The oesophagus is fastened to adjacent structures by connective 
 tissue called the tunica adventitia. The tube has three coats — an external or 
 muscular, a middle or areolar, and an internal or mucous coat. 
 
 The Muscular Coat {tunica muscularis). — The muscular coat is composed of two 
 planes of fibres of considerable thickness, an external plane of longitudinal and 
 an internal plane of circular fibres. 
 
 LEFT 
 
 PULMONARY 
 
 ARTERY 
 
 LEFT LUNG 
 LEFT BRONCHI 
 
 THORACIC CANAL 
 
 VAGUS NERVE 
 PLEURA 
 
 AZYGOS VEIN 
 
 PHARYNX 
 
 SUPERIOR LARYN- 
 mij GEAL NERVE 
 
 INTERNAL 
 JUGULAR VEIN 
 TRACHEA 
 INFERIOR 
 THYROID ARTERY 
 
 RECURRENT 
 
 NERVE 
 
 SUBCLAVICULAR 
 
 ARTERY 
 
 RIGHT CEPHALIC 
 
 TRUNK 
 
 ESOPHAGUS 
 
 VAGUS NERVC 
 
 —AZYGOS VEIN 
 
 BRONCHIAL 
 i-ARTERY 
 
 RIGHT PUL- 
 MONARY VEIN 
 
 T-RIGHT LUNG 
 
 INFERIOR 
 VENA CAVA 
 
 DIAPHRAGM 
 
 Fig. 828. — The position and relation of the oesophagus in the cervical reRion and in the posterior mediastinum. 
 
 Seen from behind. (Poirier and Charpy.) 
 
 The Longitudinal Fibres are arranged, at the commencement of the tube, in three 
 fasciculi: one in front, which is attached to the vertical ridge on the posterior 
 surface of the cricoid cartilage; and one at each side, which is continuous with 
 the fibres of the Inferior constrictor of the pharynx ; as they descend they 
 blend together and form a uniform layer, which covers the outer surface of the 
 tube. 
 
 Accessory slips of muscular fibres are described by Cunningham as passing 
 between the oesophagus and the left pleura (m. pleurooesophageus), where it covers 
 the thoracic aorta, or between the oesophagus and the root of the left bronchus 
 (m. bronchooesophageus), or the back of the pericardium, as well as other still more 
 
THE OESOPHAGUS 
 
 1229 
 
 rare accessory fibres. In Fig. 829, taken from a dissection in the Museum of the 
 Royal College of Surgeons of England, several of these accessory slips may be seen 
 passing from the oesophagus to the pleura, and two slips passing to the back of 
 the trachea just above its bifurcation. These slips of muscular fibres which pass 
 to adjacent structures give suppoit to the oesophagus. Below, the longitudinal 
 fibres of the oesophagus are continued into the longitudinal fibres of the stomach. 
 
 The Circular Fibres are continuous above with the Inferior constrictor of the 
 pharynx; their direction is transverse at the upper and lower parts of the tube, 
 but oblique in the central part. Below, the circular fibres pass into the circular 
 and oblicpie fibres of the stomach. 
 
 The muscular fibres in the upper part of the oesophagus are of a red color, and 
 consist chiefly of the striped variety, but below they consist for the most part of 
 involuntary muscular fibre. At the cardia they act 
 as a sphincter to solid food. Some maintain that 
 this sphincter is closed tonically, others that it opens 
 and closes rhythmically during gastric digestion. 
 
 The Submucous or Areolar Coat {tela suhmucosa). — 
 The submucous or areolar coat connects loosely the 
 mucous and muscular coats. It consists of dense 
 connective tissue and contains blood-vessels, nerves, 
 and oesophageal glands {glandulae oesophageae) . The 
 glands are mucous glands and are found through- 
 out the length of the gullet. The ducts of the glands 
 pass through the muscularis mucosae. These ducts 
 are surrounded by adenoid tissue. 
 
 The Mucous Coat (tunica mucosa). — The mucous 
 coat is thick, of a reddish color above and pale 
 below. It is disposed in longitudinal folds, which 
 disappear on distention of the tube. Its surface is 
 studded with minute papillae, and is covered through- 
 out with a thick layer of stratified pavement epithe- 
 Hum. The mucous coat contains glands which differ 
 from the mucous glands of the submucous tissue. 
 They are branched and tubular (Hewlett) and are 
 called the superficial glands. There are two chief 
 groups of superficial glands; one near the beginning, 
 and the other near the termination of the oesophagus. 
 The ducts of the superficial glands are not sur- 
 rounded by lymphoid tissue (Hewlett). Beneath the 
 mucous membrane, between it and the submucous 
 coat, is a layer of longitudinally arranged non-striped 
 muscular fibres. This is the muscularis mucosae 
 (lamina muscularis mucosae) . At the commencement 
 
 • . • I . 1 J. 1 u f J. , 1 of the Royal College of teurgeons of 
 
 it is absent, or only represented by a tew scattered England.) 
 bundles; lower down it forms a considerable stratum. 
 
 Vessels of the Oesophagus. — The larger vessels are in the submucosa and send 
 branches to the mucosa and muscularis. The arteries supplying the oesophagus 
 are derived from the inferior th3n:oid branch of the thyroid axis of the subclavian, 
 from the descending thoracic aorta and the bronchial arteries, and from the gastric 
 branch of the cceliac axiss and from the left inferior phrenic of the abdominal aorta. 
 They have for the most part a longitudinal direction. The veins are gathered into 
 a plexus on the outer surface of the oesophagus. This plexus receives the venous 
 blood from the walls of the tube. From the lower portion of the plexus branches 
 go to the coronary vein of the stomach. Higher up branches go to the azygos veins 
 
 Fig. 829. — Accessorj' muscular 
 fibres between the oesophagus and 
 pleura, and oesophagus and trachea. 
 (From a preparation in the Museum 
 
1230 THE ORGANS OF DIGESTION 
 
 and thyroid veins. In this manner a communication is opened between the portal 
 veins and the systemic veins. 
 
 Lymphatics of the Oesophagus. — ^The lymphatics drain into the inferior deep 
 cervical glands and the glands of the posterior mediastinum. 
 
 Nerves of the Oesophagus. — The nerves are derived from the pneumogastric and 
 from the sympathetic; they form a plexus in which are groups of ganglion-cells 
 between the two layers of the muscular coats. From this fibres pass to supply 
 the muscle, and others go to the submucous tissue to form a secondary plexus. 
 It is usual to regard the plexus as consisting of two parts, an anterior oesophageal 
 plexus, derived from the left pneumogastric, and a posterior oesophageal plexus, 
 derived from the right pneumogastric. These two plexuses are in the posterior 
 mediastinum; they communicate with each other and contain sympathetic fibres. 
 
 Movements and Innervation of the Oesophagus. 
 
 Movements. — When liquid is swallowed it is, as pointed out by Kronecker and Meltzer, 
 suddenly forced into the gullet by the contraction of the Mylo-hyoid muscle, the tube playing 
 a prr.ctically passive part.' In the passage of solid and semisolid food the oesophagus con- 
 tracts. It does not contract, as was once thought, in sections, but there is a peristaltic wave. 
 'The wave at a given point lasts in the neck region about 3.5 seconds, and from five 
 to nine seconds in the thoracic region.^ The lower end of the oesophagus or cardia has a 
 sphincter, the cardiac sphincter. It is usually taught that this sphincter is tonically contracted. 
 When a mouthful of food is swallowed it rests above the sphincter for a moment and is then 
 forced through by muscular contractions (Kronecker and Meltzer). If several acts of swallow- 
 ing follow each other rapidly the sphincter relaxes so that there is no resistance to the passage 
 of food. In cats Dr. Walter B. Cannon^ has demonstrated "rhythmical relaxations of the 
 cardia, so that fluid food streams from the stomach into the oesophagus even above the level 
 of the heart, then is pressed into the stomach again by a peristaltic wave, only to be released 
 a moment later to pour into the oesophagus anew." 
 
 Innervation. — There is in the oesophagus a local reflex, but peristalsis is dominated by the 
 central nervous system. "It seems probable that the peristaltic contractions of the oesophagus, 
 to be efficient, must be supported by nervous influences from outside. In this respect the 
 oesophagus is different from the remainder of the alimentary canal."* 
 
 Surgical Anatomy. — The relations of the oesophagus are of considerable practical interest 
 to the surgeon, as he is frequently required, in cases of stricture of this tube, to dilate the canal 
 by a bougie, when it is of importance that the direction of the oesophagus and its relations 
 to surrounding parts should be remembered. In cases of malignant disease of the oesophagus, 
 where its tissues have become softened from infiltration of the morbid deposit, the greatest 
 care is requisite in directing the bougie through the strictured part, as a false passage may easily 
 be made, and the instrument may pass into the mediastinum, or into one or the other pleural 
 cavity, or even into the pericardium. ^ 
 
 The student should also remember that obstruction of the oesophagus, and consequent 
 symptoms of stricture, are occasionally produced by aneurism of some part of the aorta press- 
 ing upon the tube. In such a case the passage of a bougie could only hasten the fatal issue. 
 
 In passing a bougie the left forefinger should be introduced into the mouth and the epiglottis 
 felt for, care being taken not to throw the head too far backward. The bougie is then to be 
 passed beyond the finger until it touches the posterior wall of the pharynx. The patient is 
 now asked to swallow, and at the moment of swallowing the bougie is passed gently down- 
 ward, all violence being carefully avoided. 
 
 It occasionally happens that a foreign body becomes impacted in the oesophagus and can 
 neither be brought upward nor moved downward. When all ordinary means for its removal 
 have failed, and the body is lodged above the lower one-third of the gullet, external oesopha- 
 gotomy is performed. If the foreign body is lodged in the lower one-third of the gullet the 
 stomach is opened {gaslrotomy) and the foreign body is extracted. If the foreign body is 
 allowed to remain lodged in the oesophagus, extensive inflammation and ulceration may 
 ensue. In one case the foreign body ultimately penetrated the intervertebral substance, and 
 destroyed life by inflammation of the membranes and substance of the cord. 
 
 The operation of oesophagotomy is thus performed: The patient being placed upon his 
 back, with the head and shoulders slightly elevated, an incision, about four inches in length, 
 
 ^ Recent Advances in the Knowledt^e of the Movements and Innervation of the Alimentary Canal. By Walter 
 li. Cannon, M.D., in Medical News, May 20, 1905. 
 
 • Ibid. 3 Ibid. * Ibid. 
 
THE ABDOMEN 1231 
 
 should be made on the left side of the trachea, from the thyroid cartilage downward, dividing 
 the skin, Platysma, and deep fascia. The edges of the wound being separated, the Omo-hyoid 
 muscle should, if necessary, be divided, and the fibres of the Sterno-hyoid and Sterno-thyroid 
 muscles drawn inward; the sheath of the carotid vessels, being exposed, must be drawn out- 
 ward, and retained in that position by retractors: the oesophagus will now be exposed, and 
 should be divided over the foreign body, which can then be removed. Great care is necessary 
 to avoid wounding the thyroid vessels, the thyroid gland, and the laryngeal nerves. 
 
 The oesophagus may be obstructed not only by foreign bodies, but also by changes in its 
 coats, producing stricture, or by pressure on it from without of new-growths or aneurism, etc. 
 
 The different forms of stricture are: (1) the spasmodic, occurring in neurotic individuals, and 
 intermittent in character, so that the dysphagia is not constant. Spasmodic stricture of the 
 oesophagus sometimes occurs in cases of cancer of the stomach and cancer of the liver; 
 (2) fibrous, due to cicatrization after injuries, such as swallowing corrosive fluids or boiling 
 water; and (3) malignant, usually epitheliomatous, in its nature. Cancer is most common 
 either at the upper end of the tube, opposite to the cricoid cartilage, or at its lower end at the 
 cardiac orifice. Cicatricial stricture may be treated by gradual dilatation. If a stricture is 
 impassible from above, the stomach may be opened, an instrument passed from below, and a 
 string used to divide the stricture. 
 
 The operation of oesophagostomy has occasionally been performed in cases where the stric- 
 ture in the oesophagus is at the upper part, with a view to making a permanent opening below 
 the stricture through which to feed the patient, but the operation has been far from a suc- 
 cessful one, and the risk of setting up diffuse inflammation in the loose planes of connective 
 tissue deep in the neck is so great that it would appear to be better, if any operative interference 
 is undertaken, with the idea of forming a mouth to introduce food, to perform gastrostomy. 
 The operation of oesophagostomy is performed in the same manner as ocsophagotomy, but the 
 edges of the opening in the oesophagus are stitched to the skin incision. Gastrostomy is 
 the only operation to be thought of in malignant stricture. 
 
 THE ABDOMEN. 
 
 The abdomen (from ahdo, I put away or hide, or possibly from adeps, fat) is 
 the largest cavity in the body. It is of an oval form, the extremities of the oval 
 being directed upward and downward; the upper one being formed by the under 
 surface of the Diaphragm, the lower by the upper concave surface of the Levator 
 ani muscles. In order to facilitate description, it is artificially divided into two 
 parts: an upper and larger part, the abdomen proper; and a lower and smaller 
 part, the pelvis. These two cavities are not separated from each other, but the 
 limit between them is marked by the brim of the true pelvis. The space is wider 
 above than below, and measures more in the vertical than in the transverse 
 diameter. 
 
 The abdomen proper differs from the other great cavities of the body in being 
 bounded for the most part by muscles and fasciae, so that it can vary in capacity 
 and shape according to the condition of the viscera which it contains; but, in 
 addition to this, the abdomen varies in form and extent with age and sex (Fig. 
 831). In the adult male, with moderate distention of the viscera, it is oval or 
 barrel-shaped, but at the same time flattened from before backward. In the adult 
 female, with a fully developed pelvis, it is conical with the apex above, and in 
 young children it is conical with the apex below. 
 
 Boundaries. — The boundary between the thorax and abdomen is the Dia- 
 phragm. This muscle forms a dome over the abdomen, and the cavity extends 
 high into the bony thorax, reaching to the level of the junction of the fourth costal 
 cartilages with the sternum. The lower end of the abdomen is limited by the 
 structures which clothe the inner surface of the bony pelvis, principally the Leva- 
 tores ani and Coccygei muscles on either side. These muscles are sometimes 
 termed the Diaphragm of the pelvis. The abdomen proper is bounded in front and 
 at the sides by the lower ribs, the abdominal muscles, and the venter ilii; behind, 
 by the vertebral column and the Psoas and Quadratus lumborum muscles; above, 
 by the Diaphragm; below, by the brim of the pelvis. The muscles forming the 
 
1232 
 
 THE ORGANS OF DIGESTION 
 
 boundaries of the cavity are lined upon their inner surface by a layer of fascia, 
 differently named, according to the part which it covers. 
 
 Fig. 830. — Topography of thoracic and abdominal viscera. 
 
THE ABDOMEN 1233 
 
 The abdomen contains (Fig. 830) the greater part of the alimentary canal; 
 some of the accessory organs to digestion — viz., the liver and pancreas, the spleen, 
 the kidneys, and suprarenal capsules. Most of these structures, as well as the 
 wall of the cavity in which they are contained, are covered by an extensive and 
 complicated serous membrane, the peritoneum (Fig. 853.) 
 
 The Apertures in the Walls of the Abdomen. — The apertures found in the walls of 
 the abdomen, for the transmission of structures to or from it, are the umbilicus, for 
 the transmission (in the foetus) of the umbilical vessels; the caval opening in the 
 Diaphragm, for the transmission of the inferior vena cava; the aortic opening, for 
 the passage of the aorta, vena azygos major, and thoracic duct; and the oesophageal 
 opening, for the oesophagus and pneumogastric nerves. Below, there are two 
 apertures on each side: one for the passage of the femoral vessels, and the other 
 for the transmission of the spermatic cord in the male, and the round ligament in 
 the female. 
 
 Male Type 
 
 Infantile Type 
 
 Female Type 
 
 A B C 
 
 Fig. 831. — Schematic outlines of the abdomen. 
 
 Regions (Fig. 832). — For convenience of description of the viscera, as well as 
 of reference to the morbid conditions of the contained parts, the abdomen is arti- 
 ficially divided into nine regions. Thus, if two circular lines are drawn around 
 the body, the one through the extremities of the ninth ribs where they join their 
 costal cartilages, and the other through the highest points of the crests of the ilia, 
 the abdominal cavity is divided into three zones^an upper, a middle, and a 
 lower. If two parallel lines are drawn perpendicularly upward from the centre of 
 Poupart's ligament, each of these zones is subdivided into three parts — a middle 
 and two lateral.* 
 
 The middle region of the upper zone is called the epigastric {liz't, over; yaaxrjpy 
 the stomach); and the two lateral regions, the right and left hypochondriac {biio^ 
 under; -j^oi^dtioi, the cartilages). The central region of the middle zone is the 
 mesogastric or umbilical; and the two lateral regions, the right and left lumbar. The 
 middle region of the lower zone is the hypogastric or pubic region ; and the lateral 
 regions are the right and left inguinal or iliac. The viscera contained in these 
 different regions are the following (Fig. 832) : 
 
 ' Anatomists are far from agreed as to the best method of subdividing the abdominal cavity. Cunningham 
 suggests that the lower line should encircle the body on a level with the highest point of the iliac crest, as seen 
 from the front — a point corresponding with a prominent tubercle on the outer lip of the iliac crest about two 
 inches behind the anterior superior spine. Addison (Journal of Anatomy and Physiology, vols, xxxiv. and 
 x.\xv.), in a careful analysis of the abdominal viscera in forty subjects, adopts the following line? : (1) a 
 median, from the symphysis pubis to the ensiform cartilage; (2) two lateral lines drawn vertically through a point 
 midway between the anterior superior iliac spine and the symphysis jjubis ; (3) an upper transverse line half-way 
 between the symphysis pubis and the suprasternal notch; and (4) a lower transverse line midway between the 
 last and the upper border of the symphysis pubis. — Ed. of 15th English edition. 
 
 .Joessel draws a line through the cartilaginous ends of the tenth ribs: a line through the two anterior superior 
 spines of the ilia. On each side he carries a per|)endicular line from the iliopectineal eminence to the hori- 
 zontal line connecting the tenth ribs. By this plan the highest plane is subcostal. 
 
 78 
 
1234 
 
 THE ORGANS OF DIGESTION 
 
 Right Hypochondriac. 
 
 The greater part of the 
 right lobe of the Hver, 
 the hepatic flexure of the 
 colon, and part of the 
 right kidney. 
 
 Right Lumbar. 
 
 Ascending colon, part 
 of the right kidney, and 
 some convolutions of the 
 small intestines. 
 
 Right Inguinal or Iliac. 
 
 The caecum and ver- 
 miform appendix and a 
 portion of the ascending 
 colon. 
 
 Epigastric Region. 
 
 The greater part of the 
 stomach, including both 
 cardiac and pyloric ori- 
 fices, the left lobe and 
 part of the right lobe of 
 the Hver and the gall- 
 bladder, the pancreas, the 
 duodenum, the supra- 
 renal capsules, and parts 
 of the kidneys. 
 
 Umbilical Region. 
 
 The transverse colon, 
 part of the great omentum 
 and mesentery, transverse 
 part of the duodenum, 
 and some convolutions of 
 the jejunum and ileum, 
 and part of both kidneys. 
 
 Hypogastric Region. 
 
 Convolutions of the 
 small intestines, the blad- 
 der in children, and in 
 adults if distended, and 
 the uterus during preg- 
 nancy. 
 
 Left Hypochondriac. 
 
 The fundus of the 
 stomach, the spleen, the 
 extremity of the pancreas, 
 the splenic flexure of the 
 colon, and part of the 
 left kidney. 
 
 Left Lumbar. 
 
 Descending colon, part 
 of the omentum, part of 
 the left kidney, and some 
 convolutions of the small 
 intestines. 
 
 Left Inguinal or Iliac. 
 
 Sigmoid flexure of the 
 colon and a portion of 
 the descending colon. 
 
 If the anterior abdominal wall is reflected in the form of four triangular flaps 
 by means of vertical and transverse incisions — the former from the ensiform car- 
 tilage to the symphysis pubis, the latter from flank to flank at the level of the 
 umbilicus — the abdominal or peritoneal cavity is freely opened into and the 
 contained viscera are in part exposed.^ 
 
 Above and to the right side is the liver, situated chiefly under the shelter of 
 the right ribs and their cartilages, but extending across the middle line, and reach- 
 ing for some distance below the level of the ensiform cartilage. Below and to the 
 left of the liver is the stomach, from the lower border of which an apron-like fold 
 of peritoneum, the great omentum, descends for a varying distance, and obscures, 
 to a greater or lesser extent, the other viscera (Fig. 861). Below it, however, some 
 of the coils of the small intestine can generally be seen, while in the right and left 
 iliac regions respectively the caecum and the sigmoid flexm-eof thecolon are exposed. 
 The bladder occupies the anterior part of the pelvis, and, if distended, will project 
 above the symphysis pubis; the rectum lies in the concavity of the sacrum, but 
 is usually obscured by the coils of the small intestine. 
 
 If the stomach is followed from left to right it will be found to be continuous 
 with the first part of the small intestine, or duodenum, the point of continuity being 
 marked by a thickened ring which indicates the position of the pyloric valve. 
 The duodenum passes toward the under surface of the liver, and then, curving 
 downward, is lost to sight. If, however, the great omentum be thrown upward 
 
 'It must be borne in mind that, although the term abdominal cavity is used, there is, under normal con- 
 ditions, only a potential cavity or lymph-space, since the viscera are everywhere in contact with the parietes. — 
 Ed. of 15th English edition. 
 
THE ABDOMEN 
 
 1235 
 
 over the chest, the terminal part of the duodenum will be observed passing across 
 the spine toward the left side, where it becomes continuous with the coils of the 
 small intestine. These measure some twenty feet in length, and if followed down- 
 ward will be seen to end in the right iliac fossa by opening into the caecum, the 
 commencement of the large intestine. From the caecum the large intestine takes 
 an arched course, passing at first upward on the right side, then across the middle 
 line and downward on the left side, and forming respectively the ascending, trans- 
 verse, and descending parts of the colon. In the left iliac region it makes still 
 another bend, the sigmoid flexure, and then follows the curve of the sacrum as 
 far as the lectum. 
 
 Limit of 
 
 Fig. 832. — The regions of the abdomen and their contents. Edge of costal cartilages in dotted outline. 
 
 The spleen lies behind the stomach in the left hypochondriac region, and may 
 be in part expo.sed by pulling the stomach over toward the right side. 
 
 The glistening appearance of the deep surface of the abdominal wall and of 
 the exposed viscera is due to the fact that the former is lined and the latter more 
 or less completely covered by a serous membrane, the peritoneum. 
 
 Development of the Alimentary Canal, Viscera and Peritoneum. — When 
 the paraxial mesoblast of the embryo has developed a series of transverse seg- 
 mentations it becomes converted into a row of dark, square segments known as 
 the proto vertebrae or the mesoblastic somites, which are separated by clear, trans- 
 verse intervals. They appear first in the region that is to become the neck, and 
 from there extend back along the entire length of the trunk. These bodies are 
 not solely the representatives of the future permanent vertebrae, but differentiate 
 partly into muscles and true skin. 
 
 On each side of the protovertebrae the lateral mesoblast splits into two layers. 
 
1236 THE ORGANS OF DIGESTION 
 
 The upper layer is applied to the epiblast, and forms with it the somatopleure or 
 body-wall. The lower layer becomes adherent to the hypoblast, and forms the 
 splanchnopleure or wall of the alimentary canal. The space between these two 
 layers is the caelum or the pleuroperitoneal cavity. This body-cavity is of large 
 size in the early stages of the development of the embryo. 
 
 Anteriorly — or, if the body is in the erect posture, superiorly — there is developed 
 a comparatively large space called the pericardiothoracic cavity; and a transverse 
 fold develops, which marks off this cavity from the future abdominal cavity. This 
 fold, with many veins of large size, develops into the primary Diaphragm, although 
 its dorsal part remains incomplete. The dorsal part is completed at a later period, 
 constituting the Diaphragm as we see it in the adult. As Dr. Frederick J. Brock- 
 way expresses it : "The Diaphragm is thus made up of a ventral, younger part, and 
 a dorsal, older part. When this posterior part fails to develop, there is opportunity 
 for a congenital diaphragmatic hernia to be present." 
 
 The pericardiothoracic cavity becomes divided into three cavities, and the two 
 lateral ones are for a time contirmous with the abdominal cavity. This continuation 
 is, however, but temporary, and they are afterward separated. In this manner, 
 four large serous sacs are formed. The two lateral thoracic sacs are known as 
 
 Fig. 833. — Diagrammatic outline of a longitudinal vertical section of the chick on the fourth day. ep. Epi- 
 blast. »m. Somatic me.soblast. hti. Hypoblast, vm. Visceral mesoblast. o/. Cephalic fold. pf. Caudal fold. 
 am. Cavity of true amnion, ys. Yolk-sac. i. Intestine. «. Fore-gut. a. Future anus, still closed, m. The 
 mouth, vie. The mesentery, al. The allantoic vesicle, pp. Space between inner and outer folds of amnion. 
 (From Quain's Anatomy, Allen Thomson.) 
 
 the pleural sacs, and are lined with the pleura; the median thoracic sac is the 
 pericardial sac, and is lined with the pericardium ; and the abdominal sac forms the 
 abdominal cavity, and is lined with the peritoneum. 
 
 The primitive alimentary canal, which was formed early by the closure within 
 the embryo of a portion of the blastodermic vesicle, consists of three parts : first, 
 the fore-gut, within the cephalic flexure, dorsal to the heart; second, the mid-gut, 
 opening freely into the yolk-sac; and third, the hind-gut, within the caudal flexure. 
 In the fore-gut are developed the back portion of the mouth, the tongue, the 
 pharynx, the oesophagus, the stomach, the larger part of the duodenum, and the 
 organs that have grown out from these structures. The hind-gut forms a portion 
 of the colon and the rectum, with the exception of the latter's anal end ; and the 
 mid-gut gives rise to the remainder of the digestive tube. 
 
 Development of the Alimentary Canal. — The fore-gut and hind-gut end 
 blindly, there being at first neither mouth nor anus (Figs. 833 and 834). The upper 
 part of the fore-gut becomes dilated to form the pharynx, in relation to which the 
 branchial arches are developed (Fig. 836); the succeeding part remains tubular, 
 and with the descent of the stomach is elongated to form the oesophagus. Soon 
 a fusiform dilatation, the future stomach, makes its appearance, and beyond 
 this the mid-gut opens freely into the yolk-sac (Figs. 836 and 837). 
 
 This opening is at first wide, but, as the body-walls close in around the umbilicus, 
 it is gradually narrowed into a tubular stalk, the yolk-stalk or vitello-intestinal duct. 
 
THE ABDOMEN 
 
 1237 
 
 At this stage, therefore, the aHmentary canal forms a nearly straight tul)e in front 
 of the notochord and primitive aorta (Fig. 834). From the stomach to the rectum 
 
 Amnion 
 
 V'.'-'v: • .>'.'-';V<^/.";. 
 
 'Allantoia 
 Hind-gut 
 
 Fore-gut / Heart 
 
 Chorda Dorsalis 
 
 Fig. 834. — Diagram of a longitudinal section of a mannmalian embryo. Very early. (After Quain.) 
 
 it is attached to the notochord by a band of mesoblast, from which the common 
 mesentery of the gut is subsequently developed. The stomach undergoes a further 
 dilatation, and its two curvatures can be recognized (Figs. 838 and 841), the 
 greater directed toward the verte- 
 bral column and the lesser toward 
 the anterior wall of the abdomen, 
 while of its two surfaces one looks 
 to the right and the other to the left. 
 The mid-gut also undergoes great 
 elongation, and forms a V-shaped 
 loop which projects downward and 
 forward ; from the bend or angle of 
 the loop the vitello-intestinal duct 
 passes to the umbilicus (Fig. 841). 
 For a time a part of the loop ex- 
 tends beyond the abdominal cavity 
 into the umbilical cord, but by 
 the end of the third month this 
 is withdrawn. With the length- 
 ening of the tube, the mesoblast, 
 which attaches it to the future ver- 
 tebral column and which carries the 
 blood-vessels for the supply of the 
 gut, is thinned and drawn out to 
 form the primitive or common me- 
 sentery. The portion of this mesentery which is attached to the greater curva- 
 ture of the stomach is named the mesogastrium, and the parts which suspend 
 
 Fig. 
 
 In A 
 
 835. — Early form of the alimentary canal, 
 front view and in B an antero-posterior section are repre- 
 sented, a. Four pharyngeal or visceral plates, b. The 
 pharynx, c, c. The commencing lungs. d. The stomach. 
 /, /. The diverticula connected with the formation of the 
 liver, g. The yolk-sac into which the middle intestinal groove 
 opens, h. The posterior part of the intestine. (From Kiilliker, 
 after Bischoff.) 
 
1238 
 
 THE ORGANS OF DIGESTION 
 
 the colon and rectum are respectively termed the mesocolon and mesorectum 
 (Fig. 841). About the sixth week a lateral diverticulum makes its appear- 
 ance a short distance beyond the vitello-intestinal duct, and indicates the future 
 caecum or boundary between the small and the large intestine. This caecal divertic- 
 ulum has at first a uniform calibre, but its blind extremity remains rudimentary 
 and forms the vermiform appendix (Figs. 841 and 842). Changes also take place 
 in the position and direction of the stomach. It falls over on to its right sur- 
 face, which henceforth is directed backward, while its original left surface looks 
 forward; further, its greater curvature is drawn downward and to the left, away 
 from the vertebral column, while its lesser curvature is directed upward, and the 
 commencement of the duodenum is pushed over to the right side of the middle 
 line. The mesogastrium, being attached to the greater curvature, must necessarily 
 follow its movements, and hence it becomes greatly elongated and drawn outward 
 
 Midbrain. 
 
 Cerebellum 
 
 Pharyngeal septum.-. 
 
 Pharynx.- 
 
 Auditory pit: 
 
 Aortic bulb: 
 Stomach.'- 
 
 /Optic vesicle. 
 
 Stomodseum. 
 Ventricle. 
 
 Cloacal dilatation- 
 of hind-gut. 
 
 Allantoic stalk 
 Umbilical vein 
 
 Liver, 
 
 ,Mid-gut and yolk 
 stalk. 
 
 Hiad-gut. 
 
 Allantois. 
 Umbilical artery. 
 
 Fig. 836. — Human embryo, about fifteen days old. Brain and heart represented from right side ; 
 alimentary canal and yolk-sac in mesial section. (After His.) 
 
 from the vertebral column, and, like the stomach, what was originally its right 
 surface is now directed backward and its left forward. In this way a pouch, the 
 bursa omentalis, is formed behind the stomach; this pouch is the future lesser sac 
 of the peritoneum, and it increases in size as the alimentary tube undergoes further 
 development; the entrance to the pouch constitutes the future foramen of Winslow 
 (Figs. 838, 842, and 845). The remainder of the mid-gut becomes greatly 
 increased in length, so that the tube is coiled on itself, and this increase in length 
 demands a corresponding increase in the width of the intestinal attachment of 
 the mesentery, so that it becomes plaited or folded. 
 
 At this stage the small and the large intestines are attached to the vertebral 
 column by a common mesentery, the coils of the small intestine falling to the right 
 of the middle line, while the large intestine lies on the left side.^ 
 
 ' Sometimes this condition persists throughout life, and it is then found that the duodenum does not cros» 
 from the right to the left side of the vertebral column, but lies entirely on the right side of the mesial plane, 
 where it is continued into the jejunum ; the arteries to the small intestine (rami intestiui tenuis) also arise from 
 the right instead of the left side of the superior mesenteric artery. 
 
THE ABDOMEN 
 
 1239 
 
 The gut now becomes rotated upon itself, so that the large intestine is carried 
 over in front of the small intestine, and the caecum is placed immediately below 
 
 Rathke's pouch 
 Notochord. {pituitary involution). 
 
 Lunfi diver-. - 
 ticulum. 
 
 Stomach | 
 
 Liver. - 
 
 Opening into, 
 yolk sac. 
 
 Allantois- 
 
 Blind portion of 
 hind-gut. 
 
 an duct. 
 
 Lung diverticuluni 
 (Esophagus 
 
 Omphalo- 
 mesenteric 
 duct. 
 
 Allantois. 
 
 Median rudiment of 
 I thyroid gland. 
 I /Mandibular arch. 
 Notochord. 
 
 Rathke's 
 
 ~ ~ pouch 
 (pituitary 
 involution). 
 
 Blind portion of 
 "hind-gut. 
 
 Wolffian duct. 
 
 Fio. 837. — Sketches in profile of two stages in the development of the human alimentary canal. 
 Fig. A X 30. Fig. B X 20. (His.) 
 
 the liver; about the sixth month the caecum descends into the right iliac fossa, 
 and the large intestine now forms an arch consisting of the ascending, transverse, 
 and descending portions of the colon — the transverse portion crossing in front 
 
1240 
 
 THE ORGANS OF DIGESTION 
 
 of the duodenum and lying just below the greater curvature of the stomach; 
 within this arch the coils of the small intestine are disposed (Fig. 842). Some- 
 times the downward progress of the caecum is arrested, so that in the adult it 
 may be found lying immediately below the liver instead of in the right iliac region. 
 
 Trachea.--^ 
 (Esophagus. 
 
 Stomach. -- 
 Bile duct 
 
 ^-shaped loop 
 of mid-gut.' 
 
 Vitello-intesti)ial duct.- 
 Cloaca.- 
 
 -Lung. 
 
 -Trachea. 
 
 -Pancreas. 
 
 -Lung. 
 — CEsophagus, 
 
 -Stomach. 
 
 Fig. 838.— Front view of two successive stages in the development of the alim3ntary canal. (His.) 
 
 Further changes take place in the bursa omentalis and in the common mesen- 
 tery, and give rise to the peritoneal relations seen in the adult. The bursa omen- 
 talis, which at first reaches only as far as the greater curvature of the stomach, 
 grows downward to form the great omentum, 
 and this downward extension lies in front of 
 the transverse colon and the coils of the small 
 intestine. The anterior layer of the transverse * ;«.-x „ .. 
 
 1 ' , n •!••<. 1 * ' i:^mi^K Right 
 
 mesocolon is at nrst quite distinct from the poste- / j^m^^iupmrenai 
 
 rior wall of the bursa omentalis, but ultimately ' " ^^■^ '"ps«e 
 
 Liver 
 
 Lesser ''^j™ 
 
 Stomach 
 
 Right 
 nprarenal 
 vapsute 
 
 L^ft 
 
 suprarenal 
 
 capsule 
 
 Liver 
 
 Fig. 839. — Schematic and enlarged cross-section through 
 the body of a human embryo in the region of the mesogas- 
 trium. Beginning of third month. (Toldt.) 
 
 Fig. 840. — Same section as in Fig. 661 at end 
 of third month. (Toldt.) 
 
 the two blend, and hence the great omentum appears as if attached to the trans- 
 verse colon (Figs. 845, 846, and 847). The mesentery of the duodenum, in which 
 
THE ABDOMEN 
 
 1241 
 
 the rudiment of the pancreas is enclosed, disappears, and so this part of the gut 
 becomes fixed to the posterior abdominal wall, and the pancreas lies entirely 
 behind the peritoneal membrane. The mesenteries of the ascending and descend- 
 
 Anterior part of mesogastrium.- 
 
 "Aorta. 
 
 •Spleen. 
 "Mesogastrium. 
 Cieliac axis. 
 
 I'liiicreas. 
 
 Superior mesenteric 
 - artery. 
 
 --,- —yj— Mesentery. 
 
 mesenteric artery. 
 
 Jlind-gut. 
 
 Fig. 841. — Abdominal part of alimentary canal anil its attachment to the primitive or common mesentery. 
 Human embryo of six weeks. (After Toldt.) (From Kollmann's ILntwickelungsgeschichte.) 
 
 ing parts of the colon disappear in the majority of cases, while that of the small 
 intestine assumes the oblique attachment characteristic of its adult condition. 
 
 The small omentum is formed by a thinning of the mesoblast or anterior primitive 
 mesentery, which attaches the lesser curvature of the stomach to the anterior 
 abdominal wall. By the subsequent growth of the liver this leaf of mesoblast is 
 
 Duodenum. 
 
 Small 
 intestine. 
 
 Yolk-stalk.: 
 
 Rectum. 
 
 Yolk-stalk. 
 
 —Rectum. 
 
 Fig. 842. — Illustrating two stages in the development of the human alimentary canal and its mesentery. 
 The arrow indicates the entrance to the bursa omentalis. 
 
 divided into two parts — viz., the small omentum between the stomach and liver, 
 and the falciform ligament between the liver and the abdominal wall and Dia- 
 phragm (Fig. 844). 
 
1242 
 
 THE ORGANS OF DIGESTION 
 
 The anus is developed as a slight invagination of the epiblast a short distance 
 in front of the posterior end of the hind-gut. This invagination is termed the 
 proctodaeum, the mesoblast between it and the hypoblastic hning of the hind- 
 gut is thinned, and ultimately the septum breaks down and disappears, and the 
 hind-gut opens on the surface; into this part of the hind-gut the urinary and 
 generative organs open for a time, and so constitutes a common cloaca. The 
 small portion of the hind-gut behind the orifice of the anus is named the c&udal 
 or post-anal gut; it communicates with the neural tube by means of a canal, the 
 
 neurenteric canal, already referred to. Ultimately the 
 post-anal gut becomes obliterated, and it, together with 
 the neurenteric canal, finally disappears. 
 
 The peritoneal cavity is the space left between the 
 visceral and parietal layers of the mesoblast, and the 
 serous membrane is develped from these layers. 
 
 The tongue originates from the floor of the pharynx. 
 The anterior or papillary portion first appears as a 
 rounded elevation, the tuberculum impar, between the ven- 
 tral ends of the mandibular and hyoid arches (Fig. 848). 
 Between the third and fourth arches a second larger 
 elevation arises, in the centre of which is a median groove 
 or furrow. This second elevation is termed the furcula, 
 and from it the epiglottis is developed, while the median 
 furrow becomes the entrance to the larynx (Fig. 849). 
 The tuberculum impar and the furcula are at first in 
 apposition, but are soon separated by a ridge produced 
 by the forward growth of the second and third arches. 
 This ridge gives rise to the posterior part of the tongue 
 and extends forward in the form of a V, so as to em- 
 brace between its two limbs the tuberculum impar. At 
 T? oA-> J?- , J- ■.• the apex of the V there is a pit-like invagination to form 
 
 Fig. 843. — Final disposition •ini -i t ii-i 
 
 of the intestines and their vas- the middle thvroid rudimcut, and this depression persists 
 
 cular relations. A. Aorta. H. ,i p "^ f xV. j Ix T'U ' if xU 
 
 Hepatic artery, s. Splenic art- as the lorameu caccum of the adult. ine union ot the 
 
 ery. A/., Co/. Branches of supe- . ± e j1 i • • i* ^ i • xi i Ij. 
 
 rior mesenteric artery, m, m'. tWO partS Ot the tOUgUC IS indicated CVCU in the adult 
 
 ar'te^^'^cjonnisct) '"^^«'^*«"'' by a V-shapcd dcpressiou, the apex of which is at the 
 
 f^eptam fransversum. 
 
 Aorta. 
 
 Liver 
 
 tnum 
 (anterior part) 
 
 Umbilical vein. 
 
 Umbilical cord 
 
 Mesogastrium 
 {posterior part). 
 
 Stomach. 
 
 Intestinal 
 
 y/shaped loop. 
 Mesentery. 
 
 Colon. 
 
 Fig. 844. — The primitive mesentery of a six weeks' human embryo, half schematic. (Kollmann.) 
 
 foramen caecum, while the two limbs run outward and forward parallel to but 
 a little behind the circumvallate papillae, which are therefore developed from 
 
THE ABDOMEN 
 
 1243 
 
 the tuberculum impar (Figs. 848, 849, and 850). The tonsils are developed from 
 the second branchial cleft, and make their appearance between the fourth and 
 fifth months. 
 
 The liver arises in the form of two diverticula or hollow outgrowths from the 
 ventral surface of that portion of the fore-gut which afterward becomes the 
 
 Mesoaastrhm 
 anterius. 
 
 Umbilical vein . 
 
 Border of the anterior 
 mesogastritan. 
 
 Storaach 
 
 ■ Bursa omeHtalis. 
 
 Pancreas. 
 
 Mesogastrium 
 posterius. 
 
 Duodenum. 
 
 f Great omentum. 
 
 Transverse 
 mesocolon. 
 
 Transverse colon. 
 
 Fig. 845. — Schematic figure of the bursa omentalis etc Human embryo of eight weeks. (Kollmann.; 
 
 duodenum (Figs. 836 and 837). The outgrowths, which represent the right and 
 the left lobes, respectively, of the adult liver, give off solid buds of cells, which grow 
 into columns or cylinders; these unite with one another in every direction to form 
 a close network, in the meshes of which are contained the capillar^ blood-vessels. 
 
 stomach 
 
 Oreaier curvature 
 Anterior lamella of greater omentum 
 Posterior lamella oj greater omentum 
 
 Transvase colon 
 
 Greater omentum 
 
 Diaphragm 
 
 Liver 
 
 Lesser omentum 
 
 Pancreas 
 
 Transverse mesocolon 
 Duodenum 
 
 Mesentery 
 
 Small intestine 
 
 Fig. 846. — Illustrating the development of the bursa omentalis, cavity of the great omentum or lesser sac. 
 Foetal stage. * Lesser sac. (Hertwig.) 
 
 Some of these columns become hollowed out and form the bile-ducts, while the 
 remainder constitute the secreting structure. The minute ducts thus produced 
 unite to form the right and left hepatic ducts; while the common bile-duct is devel- 
 oped as a protrusion from the duodenal wall, and as it grows the liver becomes 
 shifted away from the duodenum. The gall-bladder and cystic duct are formed by 
 
1244 
 
 THE ORGANS OF DIGESTION 
 
 a hollow evagination from the wall of the common bile-duct. About the third 
 month the liver almost fills the abdominal cavity. From this period the relative 
 
 stomach 
 
 Oreater curvature 
 
 Posterior lamella of greater omentum- 
 
 Transverse colon 
 
 Oreater omentuvi 
 
 Diaphragm 
 Liver 
 
 Lesser omentum 
 
 Pancreas 
 
 Part of omentum enclosing pancreas 
 
 Transverse mesocolon 
 
 Duodenum 
 
 Mesentery 
 
 Small intestine 
 
 Fig. 847.— Development of bursa omentalis. Infantile .stage. Great omentum covers the intestine.? and has 
 fused with the transverse mesocolon. Pancreas is free from peritoneum posteriorly. (Hertwig.) 
 
 development of the liver is less active, more especially that of the left lobe, which 
 now becomes smaller than the right; but up to the end of foetal life the liver 
 remains relatively larger than in the adult. 
 
 Mandibular arch. 
 Hyoid arch. 
 
 Third arch. 
 Fourth arch. 
 
 Fig. 848.^ — The floor of the pharynx of a human embryo about fifteen days old. X 50. (From His.) 
 
 The pancreas is also an early formation, being far advanced in the second 
 month. It originates as a hollow projection from the hypoblast of the dorsal wall 
 of the duodenum (Figs. 837 and 838), opposite the hepatic diverticula, which, as 
 
 Tuberculum impar 
 {papillary part of tongue). 
 
 Posterior part of tongue. 
 
 i 
 I 
 
 Furcula. 
 
 Entrance to larynx.. ^-^^-L^ 
 
 Mandibular arch. 
 
 •Hyoid arch. 
 
 Third arch. 
 Fourth arch. 
 
 • - Lung. 
 Fig. 849. — The floor of the pharynx of a human embryo about twenty-three days old. X 30. (From His.) 
 
 we have already seen, spring from its ventral wall. This hollow process grows 
 between the two layers of the dorsal mesentery and sends out offshoots, which 
 
THE PERITONEUM 
 
 1245 
 
 branch abundantly and form a complicated tubular gland. As torsion of the 
 stomach takes place, the pancreas assumes a transverse position and becomes fixed 
 across the dorsal wall of the abdomen, the posterior layer of its mesentery under- 
 going absorption. Its duct ultimately opens into the duodenum together with the 
 common bile-duct. 
 
 The spleen, on the other hand, is of mesoblastic origin, for there is never any 
 connection between the intestinal cavity and the substance of this organ. It 
 originates in the mesenteric fold which connects the stomach to the vertebral 
 column (mesogastrium) (Fig. 841). 
 
 Papillary portion of tongue. 
 
 •"i— Mandibular arch. 
 
 'Hyoid arch. 
 
 Foramen csecum. Posterior part third arch, 
 of tongue. 
 Fig. 850. — Floor of mouth of an embryo slightly older than that shown in Fig. 849. X 16. (From His.) 
 
 THE PERITONEUM (TUNICA SEROSA). 
 
 During life and in the uncut corpse the peritoneal cavity (cavum peritonaei) is 
 air-tight. It is not a real cavity, as muscular tension and atmospheric pressure 
 permit no vacant space to form. When the surgeon or anatomist opens the 
 abdomen, the peritoneal cavity is at that moment produced. 
 
 The peritoneum (from Tiefu, abovt, and rtcuto, I stretch) is the largest serous 
 membrane in the body, and consists, in the male, of a closed sac, a pait of which 
 is applied against the abdominal parietes, while the remainder is reflected over 
 the contained viscera. In the female the peritoneum is not a closed sac, since the 
 free extremities of the Fallopian tubes open directly into the peritoneal cavity. 
 The portion of the peritoneum applied against the abdominal parietes consti- 
 tutes the parietal peritoneum; the portion reflected over the viscera, the visceral 
 peritoneum. The free surface of the membrane is smooth, covered by a layer of 
 flattened endothelium, and lubricated by a small cavity of serous fluid. Hence 
 the viscera can glide freely against the wall of the cavity or upon one another with 
 the least possible amount of friction. Its attached surface is rough, being con- 
 nected to the viscera and inner surface of the parietes by means of areolar tissue 
 termed the subserous areolar tissue (tela subserosa). The parietal portion is loosely 
 connected with the fascia lining the abdomen and pelvis, but more closely to the 
 under surface of the Diaphragm and also in the middle line of the abdomen. 
 
 The peritoneum differs from the other serous membranes of the body in pre- 
 senting a much more complex arrangement — an arrangement which can only 
 be clearly understood by following the changes which take place in the alimentary 
 canal during its development; and therefore the student is advi.sed to preface his 
 study of the peritoneum by reviewing the remarks on Embryology. 
 
 Structure of the Peritoneum.— It is a thin, glistening serous membrane and 
 consists of a connective-tissue layer and one layer of flat endothelial cells upon the 
 free surface of the membrane. The connective-tissue layer consists of bundles of 
 connective tissue which contain many connective-tissue cells and ela.stic fibres. 
 It contains a multitude of lymph-spaces, lymph-vessels, and lymph-capillaries. 
 
1246 
 
 THE ORGANS OF DIGESTION 
 
 Beneath the peritoneum is a layer of lax and spongy connective tissue which serves 
 to bind the serous membrane to parts beneath. This layer is called the subserous 
 connective tissue. In some regions it is plentiful; in others, as over the liver and 
 intestine, it is very scantily developed. The endothelial cells are flat and polyg- 
 onal. Some hold that they are joined together by cement-substance. Byron 
 Robinson asserts that there is no cement-substance, but rather an organized con- 
 nection between the protoplasmic processes of adjacent cells. 
 
 On the surface of the endothelium between the cells numerous apertures or 
 interruptions are to be seen. Some of these, the stomata, are surrounded by a 
 ring of cubical endothelium (Fig. 851), and communicate with lymphatic capil- 
 laries ; others, the stigmata or 
 pseudostomata, are mere interrup- 
 tions in the endothelial layer, and 
 are occupied by processes of the 
 branched connective-tissue cor- 
 puscle of the subjacent tissue. 
 Stomata are particularly numer- 
 ous in the region of the Dia- 
 phragm and are relatively scanty 
 in the region of the pelvis. 
 
 The amount of fluid contained 
 in the closed sac is, in most 
 cases, only sufficient to moisten 
 the surface, but not to furnish any 
 appreciable quantity of liquid. 
 When a small quantity can be 
 collected, it is found to resemble 
 lymph, and, like that fluid, coagu- 
 lates spontaneously; but when 
 secreted in large quantities, as 
 in dropsy, it is a more watery 
 fluid, but still contains a con- 
 siderable amount of proteid which is coagulated on boiling. 
 
 The peritoneum is a Ijnnph-sac and its walls contain a great quantity of lym- 
 phatic structures. In the subserous tissue the numerous lymph-spaces obtain 
 fluid from the peritoneal cavity by way of the stomata of the endothelial coat, 
 and from these lymph-spaces lymph-vessels take origin. Byron Robinson points 
 out that the lymphatic system of the peritoneum consists of: 1. Interstitial 
 lymph-spaces. 2. Non-valved capillaries. 3. Valved lymphatic channels. The 
 subendothelial interstitial lymph-spaces intercommunicate and can take up an 
 immense quantity of fluid from the peritoneal cavity. Normally the spaces contain 
 both nutrient material and waste products. Through these spaces blood capil- 
 laries pass, and from these spaces lymph-capillaries come. Lymphatics are par- 
 ticularly plentiful in — 1, the tendinous portion of the Diaphragm; 2, the ligamenta 
 lata; 3, the omentum; 4, the ventral surface of the small intestine; 5, the liver and 
 spleen.^ 
 
 The lymph from this region reaches the mediastinal or diaphragmatic glands. 
 The serous surface of the Diaphragm is the region chiefly efficient in absorption 
 from the peritoneum, and there is a current in the peritoneal cavity directed toward 
 the Diaphragm.^ Absorption is very rapid from the peritoneal cavity. Fluid equalling 
 from 3 to 8 per cent, of the body-weight can be absorbed in one hour. There are a 
 multitude of nerves in the peritoneum, and it seems probable that each endothelial 
 
 Fig. 851. — Part of peritoneal surface of the central tendon of 
 Diaphragm of rabbit, prepared with nitrate of silver, s. Stomata. 
 I. Lymph-channels, t. Tendon-bundles. The stomata are sur- 
 rounded by germinating endothelial cells. (From Handbook for 
 the Physiological Laboratory, Klein.) 
 
 ' Tlie Peritoneum. By Byron Robinson. 
 
 2 Ibid. 
 
THE PERITONEUM 1247 
 
 cell receives a nerve ending. The minute arteries of the peritoneum are surrounded 
 by nerve-plexuses. According to Byron Robinson/ the nerves of the peritoneum are : 
 1. Medullated. 2. Non-medullated. 3. Fibres of Remak. 4. The Vater-Pacinian 
 corpuscles and other varieties of nerve endings. 5. Nerve-cells. The visceral 
 peritoneum contains many more nerves than the parietal peritoneum. 
 
 The parietal peritoneum (peritonaeum parietale) lines the wall of the abdominal 
 cavity. The visceral peritoneum (peritonaeum viscerate) covers the viscera. Back 
 of the parietal peritoneum is a space, the retro -peritoneal space (spatium retro- 
 peritonaeale) , which contains the great vessels and nerves, the suprarenal cap- 
 sules, the kidney, and ureters (Figs. 853, 854, 855, 856, and 857). 
 
 We describe the peritoneum as consisting of two sacs, a greater sac and a lesser sac 
 (Fig. 853) . The larger part of the abdominal cavity is lined by the greater sac, as most 
 of the viscera are covered h\ it. The lesser sac is placed largely behind the stomach. 
 These two sacs are not two distinct cavities which communicate. They constitute 
 one cavity, a portion of which has been formed into a diverticulum or recess by a 
 process of constriction, the result of changes produced in the position of adjacent 
 viscera by development. Prof. Birmingham says: " If the great sac be compared 
 to a bag, the lesser sac might be represented as a pocket lying behind, and open- 
 ing into it by a narrow orifice, the foramen of Winslow, on its posterior wall."' 
 The greater sac lines the walls of the abdominal cavity and covers the viscera 
 which are invested by peritoneum, except the posterior portion of the stomach, 
 the suprarenal capsule of the left side, the superior surface of the pancreas, the 
 Spigelian lobe and the caudate lobes of the liver, and portions of the spleen, left 
 kidney, and transverse colon, which are covered by peritoneum of the lesser sac' 
 
 To trace the continuity of the membrane from one viscus to another, and from 
 the viscera to the parietes, it is necessary to follow its reflections in the vertical 
 and horizontal directions, and in doing so it matters little where a start is made. 
 
 If the stomach is drawn downward, a fold of peritoneum will be seen stretching 
 from its lesser curvature to the transverse fissure of the liver (Figs. 853 and 859). 
 This is the gastro-hepatic or lesser omentum (omentum minus), and consists of two 
 layers; these, on being traced downward, split to envelop the stomach, covering 
 respectively its anterior and posterior surfaces. At the greater curvature of the 
 stomach they again come into contact and are continued downward in front of 
 the transverse colon, forming the anterior two layers of the great or gastro-colic 
 omentum (omentum majus) (Figs. 853 and 861). Reaching the free edge of this fold 
 they are reflected upward as its two posterior layers, and thus the great omentum 
 consists of four layers of peritoneum. Followed upward the two posterior layers 
 separate so as to enclose the transverse colon, above which they once more come into 
 contact and pass backward to the abdominal wall as the transverse mesocolon 
 (mesocolon transversum) (Fig. 853) . Reaching the abdominal wall about the level of 
 the transverse part of the duodenum, the two layers of the transverse mesocolon 
 become separated from each other and take different directions; the upper or ante- 
 rior layer, known as the ascending layer of the transverse mesocolon, ascends in front 
 of the pancreas, and its further course will be followed presently (Fig. 853) . The 
 lower or posterior layer is carried downward, as the anterior layer of the mesentery, 
 by the superior mesenteric vessels to the small intestine, around which it may be 
 followed and subsequently traced upward as the posterior layer of the mesentery to 
 the abdominal wall. From the posterior abdominal wall it sweeps downward over 
 the aorta into the pelvis, where it invests the first part of the rectum and attaches it 
 to the front of the sacrum by a fold termed the mesorectum (Fig. 863, p. 1259). 
 Leaving first the sides and then the front of the second part of the rectum it is 
 reflected on to the back of the bladder, and, after covering the posterior and 
 
 ' The Peritoneum. By Byron Robinson. - Prof. Cunningham's Text-book of Human Anatomy. 
 
 ^ Ibid. 
 
1248 THE ORGANS OF DIGESTION 
 
 upper aspects of this viscus, is carried by the urachus and obliterated hypogastric 
 arteries as folds, on to the posterior surface of the anterior abdominal wall (Fig. 
 852). The fold upon the urachus is the plica urachi i'plica umhilicalis media); 
 the fold on each obliterated hypogastric artery is the plica hypogastrica (plica 
 umbilicalis lateralift). Between the rectum and bladder it forms a pouch, the 
 recto-vesical pouch (excavatio rectovesicalis) , bounded on the sides by two cres- 
 centic or semilunar folds {'plicae rectovesicales) , which pass from the posterior 
 surface of the bladder to the sides of the rectum; the bottom of this pouch is 
 about on a level with the middle of the vesiculae seminales — i. e., three inches or 
 so from the orifice of the anus. When the bladder is distended the peritoneum 
 is carried up with the expanded viscus, so that a considerable part of the anterior 
 surface of the latter lies directly against the abdominal wall without the inter- 
 vention of the peritoneal membrane. When the bladder is empty the peri- 
 toneum forms a transverse fold over its upper surface (plica vesicalis transversa) . 
 
 In the female the peritoneum is reflected from the rectum on to the upper part 
 of the posterior vaginal wall, forming the recto-vaginal pouch or pouch of Douglas 
 (excavatio rectouterina) (Fig. 853). In the pouch of Douglas are two folds of peri- 
 toneum (plica rectouterinae) , which begin at the posterior surface of the cervix, 
 extend back to the sides of the rectum, and bound above the deepest portion of the 
 pouch. The pouch is then carried over the posterior aspect and fundus of the uterus 
 on to its anterior surface, which it covers as far as the junction of the body and 
 cervix uteri, forming here a second but shallower depression, the utero-vesical 
 pouch (excavatio vesicouterina) . It is also reflected from the sides of the uterus to 
 the lateral wall of the pelvis on each side as an expanded fold, the broad ligament of 
 the uterus (ligamenum latum uteri), in the free margin of each broad ligament can 
 be felt a thickened cord-like structure, the Fallopian tube (tuba uterina [Fallopii]). 
 
 When the peritoneum lining the anterior abdominal wall is examined from 
 behind, it is noticed that certain structures which lie in front of it form five peri- 
 toneal ridges (Fig. 852). The structure in the middle line is the urachus, which is 
 the remains of the foetal allantois. In the adult it is a fibrous cord which passes from 
 the umbilicus to the summit of the bladder. This cord is slender above, but broader 
 below. External to the urachus are the fibrous cords which resulted from oblit- 
 eration of the hypogastric arteries (arteriae umbilicales). These cords become more 
 slender as they ascend toward the sides of the urachus and pass to the umbilicus. 
 More external still are the folds formed by the deep epigastric arteries. The fold 
 over each epigastric artery is the plica epigastrica; the fold over each obliterated 
 hypogastric artery is the plica umbilicalis lateralis; the fold over the obliterated 
 urachus is the plica umbilicalis media. 
 
 The five peritoneal ridges formed by the above-named structures create three 
 peritoneal fossae on each side, called the inguinal fossae or pouches (fovea inguinales) . 
 The external inguinal fossa (fovea inguinalis lateralis) is external to the deep epi- 
 gastric artery and corresponds to the internal abdominal ring. There is a funnel- 
 shaped depression in its floor marking the point at which the inguinal process 
 passed down. This depression, if marked, predisposes to oblique inguinal hernia. 
 The middle inguinal fossa (fovea inguinalis medialis) is placed between the deep 
 epigastric arteries and the obliterated hypogastric vessels. The internal inguinal 
 fossa or the supravesical fossa (fovea supravesicalis) is between the obliterated 
 hypogastric artery and the urachus. Just beneath the inner termination of Pou- 
 part's ligament there is another fossa, the femoral or crural fossa (fovea femoralis), 
 which corresponds to the situation of the femoral ring. The obliterated hypo- 
 gastric artery is to the inner side of this fossa. 
 
 On following the parietal peritoneum upward on the back of the anterior 
 abdominal wall it is seen to be reflected around a fibrous band, the ligamentum 
 teres or obliterated umbilical vein (Figs. 855, 856, and 857), which reaches from the 
 
THE PEBITONEUM 
 
 1249 
 
 umbilicus to the under surface of the liver. Here the membrane forms a somewhat 
 triangular fold , the falciform or suspensory ligament of the liver (ligamenhim falciforme 
 hepatis), which attaches the upper and anterior surfaces of that organ to the Dia- 
 phragm and abdominal wall. With the exception of the line of attachment of this 
 ligament the peritoneum covers the under surface of the anterior part of the Dia- 
 phragm and is reflected from it on to the upper surface of the liver as the anterior or 
 superior layer of the coronary ligament {ligamenhim coronarium hepatic anterior). 
 Covering the upper and anterior surfaces of the liver it is reflected around its sharp 
 margin on to its under surface as far as the transverse fissure, where it is continuous 
 
 Plica umhilicalis 
 lateralis 
 
 Plica umhilicalis 
 media 
 
 Peritoneu 
 
 Vas 
 deferens 
 
 Middle 
 inguinal 
 fossa 
 Deep 
 inguinal 
 fossa 
 Superior 
 vesical 
 artery 
 
 Fig. 852. — Posterior view of the abdominal wall in its lower half. The peritoneum is in place and the 
 various cords are shining through. (Joessel.) 
 
 with the anterior layer of the small omentum from which a start was made (Fig. 853) . 
 The posterior layer of this omentum is carried backward from the transverse fissure 
 over the under surface and Spigelian lobe of the liver, and is then reflected, as the 
 posterior or inferior layer of the coronary ligament (ligamentum coronarium hepatis 
 posterior), on to the Diaphragm and is prolonged downward over the pancreas to 
 become continuous with the ascending layer of the transverse mesocolon (Fig. 853). 
 Between the two layers of the coronary ligament there is a triangular surface of the 
 liver which is devoid of peritoneum ; it is named the bare area of the liver, and is 
 attached to the Diaphragm by connective tissue. If, however, the two layers of the 
 
 79 
 
1250 THE ORGANS OF DIGESTION 
 
 coronary ligaments are traced toward the right and left margins of the liver, they 
 approach each other, and, ultimately fusing, they form the right and left lateral 
 ligaments of the liver and attach its right and left lobes respectively to the Dia- 
 phragm. 
 
 If the small omentum is followed toward the right side it is seen to form a 
 distinct free edge around which its anterior and posterior layers are continuous 
 with each other and between which are situated the portal vein, hepatic artery, and 
 bile-duct. If the finger is introduced behind this free edge, it passes through a 
 somewhat constricted ring, the foramen of Winslow {foramen epiploicum [Wins- 
 lowi]) (Figs. 853, 855, and 858). This is the communication between what are 
 termed the greater and lesser sacs of the peritoneum and has the following bound- 
 aries: in front, the free edge of the gastro-hepatic omentum. This free edge is 
 called the ligamentum hepatoduodenale. The gastro-hepatic omentum has the 
 portal vein, hepatic artery, and bile-duct between its two layers (Fig. 859) ; behind 
 the foramen of Winslow is the vena cava inferior; above, are the Spigelian and 
 caudate lobes of the liver; below, the duodenum and the hepatic artery, as the latter 
 passes forward and upward from the coeliac axis. 
 
 The lesser peritoneal cavity or the lesser sac of the peritoneum (bursa omentalis) 
 (Figs. 853, 855, and 858), therefore, lies behind the small omentum and has the 
 following dimensions: above, it is limited by the portion of the liver w^hich lies 
 behind the transverse fissure; below, it extends downward into the great omentum, 
 reaching, in the foetus, as far as its free edge (Fig. 846) ; in the adult, however, its 
 vertical extent is limited by adhesions between the layers of the omentum. In front, 
 it is bounded by the small omentum, stomach, and anterior two layers of the great 
 omentum; behind, by the two posterior layers of the great omentum, the transverse 
 colon, and ascending layer of the transverse mesocolon which passes upward in front 
 of the pancreas as far as the posterior surface of the liver. Laterally the lesser 
 sac reaches from the foramen of Winslow on the right side as far as the spleen on 
 the left (recessus lienalis) (Fig. 860), where it is limited by the lieno-renal liga- 
 ment. The extent of the lesser sac and its relations to surrounding parts can be 
 definitely made out by tearing through the small omentum and inserting the 
 hand through the opening thus made. A passage (vestibulum bursae omentalis) 
 leads out from the foramen of Winslow over the head of the pancreas to the left as 
 far as the median vascular gastro-pancreatic fold (plica gastropancreatica) (Fig. 858) . 
 This fold carries the gastric artery and the coronary vein. From the vestibule 
 there is a narrow and upward prolongation behind the lesser omentum and cau- 
 date lobe of the liver and in front of the lumbar portion of the Diaphragm. 
 This prolongation is the superior omental recess {recessus superior omentalis). 
 The chief part of the lesser peritoneal cavity extends downward from the gastro- 
 pancreatic fold and is called the inferior omental recess {recessus omentalis infe- 
 rior). The constriction which separates the two recesses is due to the passage 
 around the lesser sac and to the front of the gastric and hepatic arteries. "The 
 former winds around its left side, the latter around its right, and each raises up a 
 fold of peritoneum which projects strongly into the sac and partially divides it 
 into two. "I A small projection of the lesser sac passes to the right side behind 
 the beginning of the duodenum. The splenic artery in its course to the spleen 
 lies back of the posterior layer of the lesser sac. 
 
 It should be stated that during a considerable part of foetal life the transverse 
 colon is suspended from the posterior abdominal wall by a mesentery of its own — 
 the two posterior layers of the great omentum passing, at this stage, in front of and 
 above the colon (Fig. 846). This condition sometimes persists throughout adult 
 life, but as a rule adhesion occurs between the mesentery of the transverse colon 
 
 ' Prof. Cunningham's Text-book of Human Anatomy. 
 
THE PERITONEUM 
 
 1251 
 
 and the posterior layer of the great omentum, with the result that the colon 
 appears to receive its peritoneal covering by the splitting of the two posterior 
 layers of the latter fold. 
 
 In addition to tracing the peritoneum vertically, it is necessary to trace it hori- 
 zontally (Figs. 854, 855, 856, and 857). If this is done below the transverse colon, 
 the circle is extremely simple, as it includes only the greater sac of the peri- 
 toneum (Fig. 854). Above the level of the transverse colon the arrangement is 
 more complicated, on account of the existence of the two sacs. • 
 
 Starting from the linea alba, below the level of the transverse colon, and tracing 
 the continuity in a horizontal direction to the right, the peritoneum covers the 
 internal surface of the abdominal wall almost as far as the anterior border of 
 the Quadratus lumborum muscle; it encloses the caecum, and is reflected over the 
 
 LESSER 
 OMENTUM 
 
 STOMACH 
 
 TRANSVERSE 
 
 MESOCOLON 
 
 GREAT 
 
 OMENTUM 
 
 SMALL 
 INTESTINE 
 
 SMALL SAC 
 
 FORAMEN OFWINSLOW, 
 WITH ARROW PASSED 
 THROUGH IT 
 
 PANCREAS 
 
 THIRD PART OF 
 DUODENUM 
 TRANSVERSE 
 COLON 
 
 MESENTERY 
 
 POUCH OF 
 DOUGLAS 
 
 Fig. 853. — Diagrammatic mesial section of the female body, to show the peritoneum on vertical tracing. The 
 great sac of the peritoneum is black and is rejjresented as being much larger than in nature; the small sac is very 
 darkly shaded; the peritoneum on section is shown as a white Une, and a white arrow is passed through the fora- 
 men of Winslow from the great into the small sac. (Cunningham.) 
 
 sides and anterior surface of the ascending colon, fixing it to the abdominal wall, 
 from which it can be traced over the kidney to the front of the bodies of the ver- 
 tebrae. It then passes along the mesenteric vessels to invest the small intestine, 
 and back again to the spine, forming the mesentery, between the layers of which 
 are contained the mesenteric blood-vessels, nerves, lacteals, and glands. Lastly, 
 it passes over the left kidney to the sides and anterior surface of the descending 
 colon, and, reaching the abdominal wall, is continued along it to the middle line 
 of the abdomen. 
 
 Above the transverse colon (Fig. 855) the peritoneum can be traced, forming 
 the greater and lesser cavities, and their communication through the foramen of 
 Winslow can be demonstrated. Commencing in the middle line of the abdomen, 
 the membrane may be traced lining its anterior wall, and sending a process back- 
 
1252 
 
 THE ORGANS OF DIGESTION 
 
 ward to encircle the obliterated umbilical vein (the round ligament of the liver), 
 forming the falciform or longitudinal ligament of the liver. Continuing its course 
 
 Sfcfrntrnj Aorta 
 
 Small Lymphatic Vena cava Ascending 
 intestine node inferior colon 
 
 Peritoneum 
 
 Mesocolon 
 {imperfect) 
 
 Psoas 
 
 Right 
 kidney 
 
 Left kidney 
 
 Fig. 854. — Peritoneal reflection in a transverse section of a lumbar region below the transverse colon. 
 Seen from above. Schematic. (Tillaux.) 
 
 to the right, it is reflected over the front of the upper part of the right kidney, 
 across the vena cava inferior and aorta, and over the left kidney to the hilum of 
 
 Vessels in lesser 
 omentum 
 
 Liq. teres 
 
 Aorta 
 
 inferior 
 
 Fio. 855. — Transverse section of peritoneum above the transverse colon. The arrow points to the lesser 
 sac and passes through the foramen of Vi'inslow. 
 
 the spleen, forming the anterior layer of the lieno-renal ligament, the posterior 
 layer being formed by the termination of the cul-de-sac of the greater cavity 
 
THE PERITONEUM 
 
 1253 
 
 between the kidney and spleen. From the hilum of the spleen it is reflected to the 
 stomach, forming the posterior layer of the gastro -splenic omentum (ligamentum 
 
 lAg. teres 
 
 Vensrls in tesser 
 omentum 
 
 Fig. 856. — Horizontal section through the abdomen at the level of the foramen of Winslow. 
 (Modified from Godlee.) 
 
 gastrolienale) . It covers the posterior surface of the stomach, and from its lesser 
 curvature it passes around the portal vein, hepatic artery, and bile-duct, and back 
 
 Lesser omentnm. 
 
 ROUND LIGAMENT OF LIVER. 
 
 Hepatic artery, portal 
 I vein, and hepatic duct. 
 
 Gastro-splenic 
 omentum 
 
 LiENO-RENAL LIGAMENT. AMominnl aorto Vena cava. 
 
 Fig. 857. — Transverse section of peritoneum. 
 
 again to the stomach, as the lesser omentum, and thus it forms the anterior boun- 
 dary of the foramen of Winslow. It now covers the front of the stomach, and 
 
1254 
 
 THE ORGANS OF DIGESTION 
 
 upon reaching the cardiac extremity it passes to the hilum of the spleen, form- 
 ing the anterior layer of the gastro-splenic omentum. From the hilum of the 
 spleen it can be traced over the surface of this organ, to which it gives a serous 
 covering; it is then reflected from the posterior border of the hilum on to the left 
 kidney, forming the posterior layer of the lieno-renal ligament. 
 
 Numerous folds, formed by the peritoneum, extend between the various organs or 
 connect them to the parietes. These serve to hold the organs in position, and at the 
 same time enclose the vessels and nerves proceeding to each part. Some of these 
 folds are called ligaments, such as the ligaments of the liver and the false ligaments 
 of the bladder. Others, which connect certain parts of the intestine with the 
 abdominal wall, constitute the mesenteries; and lastly, those which proceed from 
 the stomach to certain viscera in its neighborhood are called omenta. 
 
 PapiU4iry tiihercle 
 
 Cut edge of peritoneum 
 
 Spleen covered 
 by peritoneum 
 
 Descending, 
 duodenum 
 
 Cut edge of peritoneum 
 
 Fig. 858. — Bursa omentalis, opened from the front by an incision through the gastro-coHc omentum. A probe 
 passes through the foramen of Winslow and rests on the gastro-pancreatic fold. (Henle.) 
 
 The Ligaments of the Peritoneum. — The ligaments, formed by folds of the peri- 
 toneum, include those of the Uver, spleen, bladder, and uterus. They will be 
 found described with their respective organs. 
 
 The Omenta. — The omenta are: the lesser omentum, the great omentum, and the 
 gastro-splenic omentum. 
 
 The Lesser or Gastro-hepatic Omentum (omentum minus) (Figs. 853 and 858) is the 
 duplicature which extends between the transverse fissure of the liver and the right 
 side of the abdominal portion of the oesophagus, the lesser curvature of the stomach, 
 and the upper portion of the superior surface of the duodenum. The portion going 
 to the oesophagus and stomach is called the hepato-gastric ligament (ligamentum 
 hepatogastricum). The division of the ligament which goes to the oesophagus is 
 strong and dense; the division which goes to the lesser curvature of the stomach 
 is thin and relaxed. The portion of the lesser omentum which goes to the 
 duodenum is continuous with the first-named portion. It is called the hepato- 
 
THE PERITONEUM 
 
 1255 
 
 duodenal ligament (ligamentum hepatoduodenale) . The right margin of this liga- 
 ment is free and concave. The hepato-colic ligament {ligamentum hepatocoli- 
 cum) is not invariably present. It is a fold of the hepato-duodenal ligament and 
 
 HEPATIC 
 DUCT 
 
 ROUND OMENTAL 
 
 LIGAMENT TUBEBOSITY GASTRIC 
 
 IMPRESSION 
 
 POSTERIOR LAYER 
 OF LESSER 
 OMENTUM 
 
 OESOPHAGUS 
 
 CYSTIC DUCT 
 
 DUODENAL 
 IMPRESSION' 
 
 FREE EDGE 
 OF LESSER 
 OMENTUM 
 
 PORTAL 
 VEIN 
 
 COMMON 
 BILE-DUCT 
 
 PANCREATIC DUCT 
 
 PYLORUS 
 
 RIGHT GASTRO- 
 EPIPLOIC ARTERY 
 SUPERIOR PANCREATICO- 
 DUODENAL ARTERY 
 
 Fig. 859.- 
 
 -Structure between the layers of the lesser omentum. The liver has been raised up, and the 
 anterior layer of the omentum removed. Semidiagrammatic. (Cunningham.) 
 
 runs from the posterior surface of the gall-bladder to the descending portion of 
 the duodenum or possibly to the transverse colon. From the free margin of the 
 termination of the hepato-duodenal ligament a fold often passes to the front 
 
 RENAL SURFACE 
 
 POUCH OF GREATER SAC 
 
 — LlENO-RENAL LIGAMENT 
 
 PHRENIC SURFACE 
 
 GASTRO-SPLENIC 
 
 OMENTUM 
 
 POUCH OF GREATER SAC 
 
 GASTRIC SURFACE 
 
 Fig. 860.- 
 
 -Horizontal section through the stomach, pancreas, spleen, and the left kidney to .show peritoneal 
 reflections at the hilum of the spleen. (G. S. H.) 
 
 of the right kidney. It is known as the duodeno-renal ligament (ligamentum 
 duodenorenale) . The lesser omentum is extremely thin, and consists of two layers 
 of peritoneum; that is, the two layers covering respectively the anterior and 
 
1256 THE ORGANS OF DIGESTION 
 
 posterior surfaces of the stomach. The posterior layer is part of the wall of the 
 lesser peritoneal cavity; the anterior layer, of the greater peritoneal cavity. When 
 the two layers reach the lesser curvature of the stomach, they join together and 
 ascend as the double fold to the transverse fissure of the liver; to the left of this 
 fissure the double fold is attached to the fissure of the ductus venosus as far as 
 the Diaphragm, where the two layers separate to embrace the end of the oesoph- 
 agus. At the right border the lesser omentum is free, and the two layers of 
 which it is composed are continuous. The anterior layer, which belongs to the 
 greater sac, turns around the hepatic vessels to become continuous with the poste- 
 rior layer belonging to the lesser one. They here form a free, rounded margin, 
 which contains between its layers the hepatic axtery, the common bile-duct, the 
 portal vein, lymphatics, and the hepatic plexus of nerves (Fig. 859) — all these struc- 
 tures being enclosed in loose areolar tissue, called Glisson's capsule. Between the 
 layers where they are attached to the stomach lie the gastric artery and the pyloric 
 branch of the hepatic artery, anastomosing with it. From the left side of the 
 greater curvature of the stomach a fold passes to the gastric surface of the spleen, 
 covers the spleen, and passes from the renal surface of the spleen around the 
 left kidney to the Diaphragm.^ The fold passing to the spleen is known as the 
 gastro-splenic ligament or the gastro-splenic omentum (ligamentum gastrolienale) 
 (Fig. 860). The portion passing to the Diaphragm is known as the spleno- 
 phrenic ligament {ligamentum phrenicolienale) . The gastric veins or vasa brevia 
 pass from the left side of the greater curvature of the stomach toward the 
 spleen in the gastro-splenic omentum. 
 
 The Great or Gastro-colic Omentum {omentum majus) (Figs. 853 and 861) is the 
 largest peritoneal fold. It consists of four layers of peritoneum, two of which 
 descend from the stomach, one from its anterior, the other from its posterior 
 surface, and, uniting at its lower border, descend in front of the small intestines, 
 sometimes as low down as the pelvis; they then turn upon themselves, and ascend 
 again as far as the transverse colon, where they separate and enclose that part 
 of the intestine. These separate layers may be easily demonstrated in the young 
 subject, but in the adult they are more or less inseparably blended. At the free 
 margins the two outer layers and the two inner layers become continuous. The 
 left border of the great omentum is continuous with the gastro-splenic omentum; 
 its right border extends as far only as the duodenum. The great omentum is 
 usually thin, presents a cribriform appearance, and always contains some adipose 
 tissue, which in fat subjects accumulates in considerable quantity. Between its 
 two anterior layers is the anastomosis between the right and left gastro-epiploic 
 arteries. In opening the abdomen the great omentum is rarely found spread out 
 evenly over the intestines. It often projects between intestinal coils, or is largely 
 gathered in some one region, or is pushed in front of the stomach by distention 
 of the colon. 
 
 The lower portion of the lesser sac of the peritoneum continues for a distance 
 between the ascending and descending layers of the great omentum (Fig. 853). 
 The portion of the lesser peritoneal cavity within the great omentum is more or 
 less obliterated in the adult by adhesion between its opposing layers. At birth 
 the omentum is very short and barely reaches the umbilicus. In adults its length 
 varies greatly. In some individuals it is very short; in others it passes into the 
 pelvis. Mr. Lockwood points out that in persons under forty-five years of age 
 the omentum can rarely be pulled down below the level of the pubic spine; in 
 older persons it generally can. 
 
 The Gastro-splenic Omentum is the fold which connects the margins of the 
 hilum of the spleen to the cul-de-sac of the stomach, being continuous by its lower 
 
 ' Spalteholz, Hand Atlas of Human Anatomy. Translated and edited by Prof. Lewellys F. Barker. 
 
THE PERITONEUM 
 
 1257 
 
 border with the great omentum. It was described as the gastro-splenic liga- 
 ment (Fig. 860). 
 
 The Mesenteries. — The mesenteries are: the mesentery proper, the transverse 
 mesocolon, the sigmoid mesocolon, the mesorectum (p. 1259), and the mesentery of 
 the vermiform appendix. In addition to these there are sometimes present an 
 ascending and a descending mesocolon. 
 
 The Mesentery (mesenterium) (/.tiaoii ivvspou) (Figs. 853, 862, and 863), so called 
 from being connected to the middle of the cylinder of the small intestine, is the 
 broad fold of peritoneum which connects the convolutions of the jejunum and 
 ileum with the posterior wall of the abdomen. It consists of a layer of connec- 
 tive tissue, each side of which is covered with peritoneum. In the connective 
 
 Fig. 861. — The great omentum as seen from the front. (Testut.) 
 
 tissue there are fatty masses. Its root (radix mesenterii), the part connected with 
 the vertebral column, is narrow, about six inches in length, and directed obliquely 
 from the left side of the second lumbar vertebra to the right sacro-iliac symphysis 
 (Fig. 863). Its intestinal border is vastly broader (measures about twenty feet); 
 and here its two layers separate so as to enclose the intestine, and form its peri- 
 toneal coat. Its breadth, between its vertebral and intestinal border, is about 
 eight inches. Its upper border is continuous with the under surface of the trans- 
 verse mesocolon; its lower border, with the peritoneum covering the caecum and 
 
1258 
 
 THE ORGANS OF DIGESTION 
 
 ascending colon. The origin of the mesentery above is just beyond the termina- 
 tion of the duodenum, and it terminates below in the angle formed by the junction 
 of the ileum and the colon. It serves to retain the small intestines in their position, 
 and contains between its layers the mesenteric vessels and nerves, the lymphatic 
 vessels and mesenteric glands. These glands number from 50 to 150. Occa- 
 sionally congenital mesenteric openings exist. In stout individuals the mesentery 
 contains much fat. If there is much fat the mesentery is not translucent; if 
 there is little fat it is translucent. It may be actually transparent above and 
 translucent or opaque below. The thinnest part of the mesentery is above. As 
 we descend it becomes thicker, because of the presence of fat, fibrous ligament, 
 and muscular tissue.^ 
 
 Mesentery 
 {Itft leaf) ' 
 
 Root of mesen- 
 tery 
 
 Ileum 
 
 Sigmoid flexure 
 Csscum- 
 
 Duodenum 
 
 Fig 862 —Mesentery 
 
 Small intestine pushed to the light and abrne 
 
 CliUaux ) 
 
 In most cases the peritoneum covers only the front and sides of the ascending 
 and descending parts of the colon. Sometimes, however, these are surrounded by 
 the serous membrane and attached to the posterior abdominal wall by an ascending 
 mesocolon (mesocolon ascendens) and a descending mesocolon (mesocolon descendens) 
 
 ' Intestinal Localization. By Geo. H. Monks, Annals of Surgery, October, 1903. 
 
THE PERITONEUM 
 
 1259 
 
 respectively. At the place where the transverse colon turns downward to form the 
 descending colon, a fold of peritoneum is continued to the under surface of the 
 Diaphragm opposite the tenth and eleventh ribs. This is the phreno-colic ligament 
 (ligamentum phrenicocolicum) ; it passes below the spleen, and serves to support 
 this organ, and therefore it has received the secontl name of sustentaculum lienis. 
 The Transverse Mesocolon (mesocolon transversum) (Fig. 863) is a broad fold, 
 which connects the transverse colon to the posterior wall of the abdomen. It is 
 formed by the two ascending or posterior layers of the great omentum, which, after 
 
 Right lateral 
 ligament of liver. 
 
 Falciform ligament 
 of liver. 
 
 Left lateral 
 ligament of liver. 
 
 Tena cava inferior 
 
 (Esophagtu 
 Right phrenic artery 
 
 Coronary artery -< 
 
 Hepatic artery 
 
 Splenic artery 
 
 Pancreas — 
 
 Inf. pane. -duo. artery 
 
 Colica medta 
 
 Superior mesenteric 
 
 Duodenum (3rd part) 
 
 Ao ta 
 
 Duodenum (2nd pat t) 
 
 Bight and left kidneys 
 
 Superior mesenteric 
 
 Aorta 
 
 Colica sinistra 
 
 Colica dextra. 
 
 Vasa intestini. \ 
 
 Sigmoid artery. 
 Sup. hemorrhoidal artery. 
 
 Common iliac artery.'" " 
 
 Internal iliac artery.— — 
 
 External iliac artery. " 
 
 Epigastric artery. — 
 Bladder. " 
 
 Peritoneum. 
 Extraperitoneal HsnM* 
 
 ^ Diaphragmatic end of 
 (f astro- hepatic omentum, 
 istro'phrenic ligament. 
 
 G astro-splenic omentum* 
 Foramen of Winslow. 
 Duodenum (fst part).. 
 
 Costo-colic ligament. 
 Dot between two anterior 
 layers of great omentum. 
 Transverse meso-colon. 
 
 Bare surface for descend^ 
 ing colon. 
 
 The two layers of the 
 mesentery proper. 
 
 Bare surface for oACtnd* 
 ing colon. 
 
 Sigmoid meso-colon. 
 
 Bare surface for ccecum. 
 .Veso-rectum. 
 
 5 Bare surface for 2nd part 
 i of rectum. 
 I Left lateral false liga- 
 i ment of bladder. 
 
 Fio. 863. 
 
 -Diagram devised by Dr. Del^pine to show the lines along which the peritoneum leaves the wall 
 of the abdomen to invest the viscera. 
 
 separating to surround the transverse colon, join behind it, and are continued 
 backward to the spine, where they diverge in front of the duodenum. This fold 
 contains between its layers the vessels which supply the transverse colon. 
 
 The Sigmoid Mesocolon {mesocolon sigmoideum) (Fig. 863) is the fold of peri- 
 toneum which retains the sigmoid flexure in connection with the left iliac fossa. 
 This portion of intestine remains always freely movable. 
 
 The Mesorectum is really only the lower portion of the sigmoid mesocolon. It 
 is the name formerly given to the narrow fold which, according to the old defini- 
 
1260 
 
 THE ORGANS OF DIGESTION 
 
 tion of the rectum, connects the upper part of the rectum with the front of the 
 sacrum. It contains the superior hemorrhoidal vessels. 
 
 The Mesoappendix or Mesentery of the Vermiform Appendix (mesenteriolum pro- 
 cessus vermiformis) (Fig.867)is a double fold of peritoneum which usually completely 
 surrounds the vermiform appendix. It is usually described as a triangular fold, 
 and at a glance it appears so, but Jonnesco points out that it has four borders: a 
 superior or mesenteric border; a right or csecal; a left or free, and an inferior 
 or appsndicular. One of the borders is often extremely short. The upper sur- 
 face of the mesoappendix is continuous with the lower surface of the mesentery 
 proper and with the left or internal fold of the peritoneum covering the caecum. 
 The lower surface of the mesoappendix is continuous with the right or external 
 fold of peritoneum covering the caecum. As a rule, the entire appendix is covered 
 with peritoneum; sometimes a portion of the base is uncovered, and this portion of 
 the diverticulum is then extraperitoneal. The tip is never extraperitoneal. The 
 mesoappendix may be attached to the entire length of the appendix, but, as a 
 rule, the tip is free. In fact, one-third, one-half, or two-thirds may be free and 
 occasionally the mesoappendix is a mere vestige. Between the two peritoneal 
 layers of the mesoappendix there is connective tissue, and often fat. In the 
 connective tissue are the appendicular blood-vessels, lymph-vessels, and nerves. 
 
 The Appendices Epiploicae are small pouches of the peritoneum filled with fat 
 and situated along the colon and upper part of the rectum. They are chiefly 
 appended to the transverse colon. 
 
 INFERIOR 
 
 MESENTERIC 
 
 VEIN 
 
 SUPERIOR 
 DUODENAL 
 FOLD 
 
 SUPERIOR 
 DUODENAL 
 FOLD 
 
 INFERIOR 
 
 DUODENAL 
 
 FOLD 
 
 INFERIOR 
 
 DUODENAL 
 
 FOLD 
 
 ARTERIA 
 
 COLICA 
 
 SINESTRA 
 
 Fig. 864. — Superior and inferior duodenal fossa. (Poirier and Charpy.; 
 
 Retro-peritoneal Fossae.— In certain parts of the abdominal cavity there are 
 recesses of peritoneum forming culs-de-sac or pouches, which are of surgical inter- 
 est in connection with the possibility of the occurrence of retro-peritoneal hernia. 
 One of these, which was previously described, is the lesser sac of the peritoneum 
 (Figs. 853 and 855), which may be regarded as a recess of peritoneum through the 
 foramen of Winslow, in which a hernia may take place, but there are several 
 others, of smaller size, which require mention. 
 
 These recesses of fossae may be divided into three groups, viz.: (1) the duodenal 
 fossae; (2) pericaecal fossae; and (3) the intersigmoid fossa. 
 
 1. Duodenal Folds and Fossae.— Moynihan has described no less than nine fossae 
 as occurring in the neighborhood of the duodenum. Three of these are fairly 
 constant. Five of the fossae are here considered, (a) The inferior duodenal 
 fossa or fossa of Treitz (Fig. 864) is the most constant of all the peritoneal fossae 
 in this region, being present in from 70 to 75 per cent, of cases. It is situated 
 
THE PERITONEUM 
 
 1261 
 
 opposite the third lumbar vertebra on the left side of the ascending portion of the 
 duodenum. The opening into the fossa is directed upward, and is bounded by a 
 thin, sharp fold of peritoneum with a concave free upper margin. This fold of 
 peritoneum is called the inferior duodenal fold (plica duodenomesocolica) . The 
 tip of the index finger introduced into the fossa under the fold passes some little 
 distance up behind the ascending or fourth portion of the duodenum. One margin 
 of the fold is attached to the ascending portion of the duodenum; another margin 
 is attached to the parietal peritoneum. (/>) The superior duodenal fossa (Fig. 864) 
 is the next most constant pouch or recess, being present in from 40 to 50 per cent, 
 of cases. It often coexists with the inferior one, and its orifice looks downward, 
 in the opposite direction to the preceding fossa. It lies to the left of the ascend- 
 ing portion of the duodenum. It is bounded in front by the superior duodenal fold 
 (plica duodenojejunalis), which is triangular and has a free semilunar base; to the 
 
 RIGHT RETHO- 
 
 OUODENAL 
 
 WALL 
 
 INFERIOR 
 
 DUODENAL 
 
 ANGLE 
 
 INFERIOR 
 
 MESENTERIC 
 
 VEIN 
 
 PARIETAL FOLD 
 OF DUODENUM 
 
 LEFT COLIC 
 ARTERY 
 
 INFERIOR MESEN- 
 TERIC ARTERY 
 
 ^ 
 
 Fig. 865. — Retro-duodenal fossa. (Poirier and Charpy.) 
 
 right it is blended with the peritoneum covering the ascending duodenum, and to 
 the left with the peritoneum covering the perirenal tissues. The fossa is bounded 
 in front by the superior duodenal fold; behind by the second lumbar vertebra; to 
 the right by the duodenum. Its depth is 2 cm., and it terminates in the angle 
 formed by the left renal vein crossing the aorta. This fossa is of importance, as 
 it is in relation with the inferior mesenteric vein; that is to say, the vein almost 
 always corresponds to the line of union of the superior duodenal fold with the 
 posterior parietal peritoneum, (c) The duodeno-jejunal fossa or mesocolic fossa 
 (recessus duodenojejunalis) is formed where the duodeno-jejunal angle enters the 
 root of the transverse mesocolon. There are two forms: (1) a single fossa and (2) 
 a double fossa. It can be seen by pulling the jejunum downward and to the right, 
 after the transverse colon has been pulled upward. It will appear as an almost 
 circular opening, looking downward and to the right, and bounded by two free 
 borders or folds of peritoneum, the duodeno-mesocolic ligaments. The opening 
 admits the little finger into the fossa to the depth of from 2 to 3 cm. The fossa 
 
1262 
 
 THE ORGANS OF DIGESTION 
 
 is bounded above by the pancreas, to the right by the aorta, and to the left by the 
 kidney; beneath is the left renal vein. The fossa exists in from 15 to 20 per 
 cent, of cases, and has never yet been found in conjunction with any other form 
 of duodenal fossa, {d) Paraduodenal fossa or the fossa of Landzert {recessus diio- 
 denojejunalis) is most distinct in the infant, and is to the left of the ascending 
 portion of the duodenum. The fold of peritoneum to its outer side and above is 
 
 ANTERIOR 
 ILCOOCCAL 
 
 ANTERIOR 
 
 ILEOCiECAL 
 
 FOSSA 
 
 INFERIOR 
 
 ILEOCiECAL 
 
 FOLD 
 
 Fig. 866.— Anterior, sometimes called superior, ileo-csecal fossa. (Poirier and Charpy.) 
 
 produced by the inferior mesenteric vein. Its lower limit is a fold called the 
 mesenterico-mesocolic fold, (e) The retroduodenal fossa (Fig. 865) was described 
 in 1893 by Jonnesco. It is a peritoneal cul-de-sac, sometimes found behind the 
 horizontal and ascending portions of the duodeimm. 
 
 2. Pericsecal Folds and Fos'ae. — There are at least three pouches or recesses to be 
 found in the neighborhood of the caecum, which are termed pericsecal fossae. (1) 
 
 I LEO- APPENDICULAR 
 FOSSA 
 
 W" MESENTERY 
 
 APPENDICULAR 
 ARTERY 
 
 ILEO-APPENDICULAR 
 ARTERY 
 
 MESO-APPENDIX 
 
 Fig. 867. — Ileo-appendicular or inferior ileo-cfecal fossa. The caecum and ascending colon have been 
 drawn outward and downward, the ileum upward and backward, and the apoendix downward (Poirier 
 and Charpy.) 
 
 The ileo-colic fossa or superior ileo-csecal (recessus ileocaecalis superior) (Fig. 866) 
 is formed by a fold of peritoneum, the ileo-colic fold, arching over a branch of 
 the ileo-colic artery, which supplies the ileo-colic junction, and appears to be the 
 direct continuation of the artery. The fossa is a narrow chink situated between 
 the ileo-colic fold in front, and the mesentery of the small intestine, the ileum, 
 
THE PERITONEUM 
 
 1263 
 
 and a small portion of the caecum behind. (2) The ileo-csecal, inferior ileo-csecal 
 or ileo-appendicular fossa (recessus ileocaecalis inferior) (Fig. 867) is situated behind 
 the angle of junction of the ileum and caecum. It is formed by a fold of peritoneum, 
 the ileo-caecal fold {plica ileocaecalis), which Treves called the "bloodless fold." 
 Tuffier denies its non-vascularity, and Lockwood and RoUeston state that it con- 
 tains fat, muscular fibres, and arteries and veins derived from the appendicular ves- 
 sels and the anterior and posterior ileo-csecal vessels.^ The upper border of the fold 
 is attached to the ileum, opposite its mesenteric attachment, and the lower border, 
 passing over the ileo-cfecal junction, joins the mesentery of the appendix, and 
 sometimes the appendix itself; hence this fold is sometimes called the ileo-appen- 
 dicular fold. Between the ileo-cfecal fold and the mesentery of the vermiform 
 appendix is the ileo-caecal fossa. It is bounded above by the posterior surface of 
 the ileum and the mesentery; in front and below by the ileo-cfecal fold, and behind 
 by the upper part of the mesentery of the appendix. (3) The retro-caecal or retro-colic 
 
 ILEO-APPENDICULAR 
 
 ILEO-APPENDICULAR 
 FOSSA 
 
 MESO-APPENOIX 
 
 NFERIOR 
 CiECAL FOLD 
 
 RETRO-OECAL 
 FOSSA 
 
 Fig. 868. — The retro-cscal fossa. The ileum and cwcum are drawn backward and upward. (Souligoux.) 
 
 fossae {recessus retrocae sails) (Fig. 868) are situated behind the caecum and ascend- 
 ing colon. There may be no fossa present. There may be one fossa; there are 
 usually two (external and internal retrocolic fossae) ; occasionally there are more 
 than two.^ The fossae are brought into view by raising the caecum. According to 
 Berry, one or other of the fossa is present in 30 per cent, of cases. Treves thinks 
 the retrocolic fossae are extremely rare. There may be one fossa (20 per cent, of 
 cases) or two fossae (10 per cent, of cases). If there is but one fossa it is the 
 internal that exists three times as often as the external. The retro-colic space, 
 if present, varies nuich in size and extent. In some cases it is sufficiently large 
 to admit the index finger and extends upward behind the ascending colon in 
 the direction of the kidney; in others it is merely a shallow depression. The 
 external retro-colic fossa is bounded and formed by two folds: one, the external 
 parieto-colic fold or the superior csecal fold, which is the outer layer of the ascend- 
 ing mesocolon, and is attached by one edge to the abdominal wall from the 
 lower border of the kidney to the iliac fossa and by the other to the postero- 
 
 The Ccecal Folds and Fossae. By Richard J. k. Berry. 
 
 2 Ibid. 
 
1264 THE ORGANS OF DIGESTION 
 
 external aspect of the colon; and the other, the internal paxieto-colic fold or inferior 
 caecal fold, which is the inner layer of the ascending mesocolon. The internal 
 retrocolic fossa is bounded externally by the internal parieto-colic fold, and is 
 bounded internally by the mesenterico-parietal fold, which is the insertion of the 
 mesentery into the iliac fossa. 
 
 3. The Intersigmoid Fossa {recessus intersigmoideus) . — The intersigmoid fossa 
 is constant in the foetus and common during infancy, but disappears in a large 
 percentage of cases as age advances. Upon drawing the sigmoid flexure upward, 
 the left surface of the sigmoid mesocolon is exposed, and on it will be seen a 
 funnel-shaped recess of the peritoneum, lying on the external iliac vessels, in the 
 interspace between the Psoas and Iliacus muscles. This is the orifice leading to 
 the fossa intersigmoidea, which lies behind the sigmoid mesocolon, and in front of 
 the parietal peritoneum. This fossa is produced by the incomplete fusion in the 
 foetus of the descending mesocolon with the parietal peritoneum. The fossa varies 
 in size; in some instances it is a mere dimple, whereas in others it will admit the 
 whole of the index finger. 
 
 Any of these fossae may be the site of a retro -peritoneal hernia. The pericecal 
 fossae are of especial interest, because hernia of the vermiform appendix frequently 
 takes place into one of them, and may there become strangulated. The presence 
 of these pouches also explains the course which pus has been known to take in 
 cases of perforation of the appendix, where it travels upward behind the ascending 
 colon as far as the Diaphragm.^ 
 
 Surgical Anatomy. — Study of the lymphatics of the peritoneum by Byron Robinson and 
 others shows that absorption takes place most rapidly from the region of the Diaphragm, less 
 rapidly but still very actively from the region of the small intestine, slowly from the pelvic 
 region. Clinically we know that pelvic peritonitis is not nearly so dangerous as peritonitis 
 in the small intestine or Diaphragm areas, and that peritonitis in the region of the Diaphragm 
 is the most fatal form of the infection. After abdominal operations in infected cases, it is 
 well to elevate the head of the bed {Fowler's position), so as to obtain the aid of gravity in 
 draining septic fluids away from the dangerous region and toward the safer region.^ In areas 
 in which absorption is rapid, protective exudation is not apt to form. In areas in which 
 absorption is slow, inflammatory exudation is apt to circumscribe the area and prevent dift'u- 
 sion. After an operation in a non-infected case, if salt solution has been left in the abdominal 
 cavity because of shock or hemorrhage, raising the foot of the bed will aid rapid absorption 
 of the fluid by favoring the natural current toward the Diaphragm and hurrying the fluid to a 
 region in which absorption is rapid. 
 
 The great omentum stores up fat, and, being movable, it is able to pass to different parts 
 of the peritoneal cavity. Dr. Byron Robinson, in his work on the Peritoneum, describes its 
 functions as follows: ''The omentum is the great protector against peritoneal infectious 
 invasions. It builds barriers of exudates to check infection. It is like a man-of-war, 
 ready at a moment's notice to move to invaded parts. It circumscribes abscesses; it repairs 
 visceral wounds, and prevents adhesions of mobile viscera to the anterior abdominal wall. 
 It resists infectious invasions by typical peritoneal exudates, and not by succumbing to absorbed 
 sepsis. It is a director of peritoneal fluids, a peritoneal drain." 
 
 In abdominal wounds the omentum often protrudes: This structure frequently constitutes 
 or is part of a hernia, and is almost invariably present in umbilical hernia. As a result of 
 inflammation, it may become adherent to adjacent structures. Adhesions may be of service by 
 matting together the intestines and circumscribing infections. They may be harmful by 
 constricting the bowels and producing obstruction. A portion of the omentum may become 
 adherent to some other part and form a band, and under this band the gut may be caught and 
 strangulated. Omentum may adhere to and plug a perforation in a hollow viscus, and the sur- 
 geon may utilize it for the same purpose, or to cover a raw surface or overlie a suture line. The 
 omentum may be in the surgeon's way while operating. If it is, the patient is placed in the 
 Trendelenburg position (pelvis elevated). 
 
 Any tear or opening found by the surgeon in the great omentum must be closed with sutures, 
 because of the danger that intestine might enter and be caught in such an opening. A tumor 
 cut off from its proper blood-supply, for instance, an ovarian cyst with a twisted pedicle, may 
 continue to receive nourishment from adherent omentum, and gangrene may thus be prevented. 
 
 ' On the anatomy of these fossae, see the Arris and Gale Lectures by Moynihan, 1899. 
 - George R. Fowler, in Medical Record, April 14, 1900. 
 
THE PERITONEUM 
 
 1265 
 
 The lax character and shifting tendency of the subserous tissue explains the occurrence of 
 ptosis of the abdominal viscera and kidneys. 
 
 The vast number of nerves in the peritoneum accounts for the profound shock which follows 
 a wound, attends an intraperitoneal calamity, or which develops from infection. An infective 
 process of any portion of the peritoneum produces pain and reflex symptoms (vomiting, 
 abdominal rigidity, intestinal paresis, etc.). 
 
 The parietal peritoneum is very sensitive to pain, but not to touch; hence, after injecting a 
 local anaesthetic and opening the abdomen, a fairly satisfactory exploration can be made with 
 the finger. 
 
 The intestine, the mesentery, the stomach, the anterior margin of the liver, and the gall-bladder 
 are insensitive, and may be cut or even burned without pain.' 
 
 Viscera which obtain their innervation purely from visceral nerves are insensitive; those which 
 receive branches from somatic nerves are sensitive (Lennander). 
 
 The oblique origin of the mesentery causes this structure to form a sort of shelf. A hemor- 
 rhage or extravasation into the abdomen, to the right of the mesentery, tends to flow into the 
 right iliac fossa; one occurring on the left side flows into the pelvis. Monks points out that in 
 flushing the abdominal cavity the tube should not be aimlessly introduced, but should utilize 
 the mesentery on each side of an intestinal loop, to '' conduct the tip of the irrigating tube to the 
 bottom of the two fossae."^ Monks also shows how the mesentery can be utilized to determine 
 the direction of an intestinal loop: 
 
 "Now, let us suppose that the surgeon has between his fingers a loop of bowel, and wishes 
 to determine its direction. He knows that one side of the loop is the left side of the intestine, 
 and that the corresponding side of the mesentery, if closely followed down to the mesenteric 
 root, will conduct him into the left fossa; he also knows that the other side of the bowel is its 
 right side, and that the mesentery on that side will conduct him into the right fossa. Now, 
 
 Fig. 869. — A loop of intestine, the middle of which is exactly three feet from the end of the duodenum. The 
 gut is of large size. The mesenteric loops are primary, and the vasa recta large, long, and regular in distribu- 
 tion. The translucent spaces (lunettes) between the ves.sels are extensive. Below, the mesentery is streaked 
 with fat. The veins, which had a distribution similar to the arteries, are for simplicity omitted from this and 
 from the subsequent drawings. (The subject from which the specimen was taken was a male aged forty years, 
 with rather less than the usual amount of fat. The entire length of the intestine was twenty-three feet. 
 (Monks.) 
 
 if his finger goes into the great fossa on the left side of the abdomen, after having closely fol- 
 lowed the mesentery down to its root and arranged his loop to be parallel with that root, he then 
 knows that the left and right sides of the intestine face to the left and right sides of the abdomen 
 respectively, and that the end of the loop which points downward is the end nearest the ileo- 
 csecal valve. He can determine the direction of the gut in a similar way in case his finger enters 
 the right fossa. All this would seem very simple were it not for the twists in mesentery and 
 intestine, which tend to mislead one. A little practice will usually enable one to recognize a twist 
 in the mesentery. This should be untwisted by rotation of the gut, after which the direction is 
 determined by another palpation of the mesenteric root."^ 
 
 ' Dr. K. E L. Lennander, in Mittheilungen aus dem Grenzgebrieten der Medecin und Chirurgie, 1902, Band x. 
 Heft 1. 2. 
 
 2 Intestinal Localization, by George H. Monks, Annals of Surgery, October 1903. 
 ^ Annals of Surgery, October, 1903. 
 
 80 
 
1266 
 
 THE ORGANS OF DIGESTION 
 
 The studies made of the arrangement and variations of the loops of the mesenteric vessels by 
 Dr. Thomas Dwight' have been utilized and expanded by Dr. George H. Monks in laying down 
 
 Fig. 870. — A loop of intestine at six feet. As compared with Fig. 869 the gut is somewhat smaller. The 
 vascularity of the intestine and mesentery is less. Secondary loops are a prominent feature. The vasa recta 
 are smaller. The lunettes are also present, but are not so large as in Fig. 869. (The subject was a male aged 
 about thirty-five years, with an average amount of fat. The entire length of the intestine was twenty feet. 
 (Monks.) 
 
 rules for the determination of the exact portion of small intestine which may be in the surgeon's 
 hand.^ His views are as follows: 
 
 " General Vascularity of the Mesentery near the Bowel. — Opposite the upper part of the bowel the 
 mesenteric vessels are distinctly larger than opposite any other part of it. These vessels grow 
 
 Fig. 871. — A loop of intestine at nine feet. The secondary loops are large; the vasa recta are somewhat 
 irregular and show branches. No lunettes are present, and the mesentery is streaked with fat, and is, therefore, 
 somewhat opaque. (The specimen was taken from the same subject which furnished Fig. 869. (Monks.) 
 
 smaller and smaller as we pass downward until the lower third of the gut is reached, where they 
 remain about the saTne size as far as the ileo-csecal valve. The arrangement of the mesenteric 
 
 ' Reports of the Meeting of American Anatomists, 1897. 
 
 Annals of Surgery, 1903. 
 
THE PERITONEUM 
 
 1267 
 
 vessels has some features which intimately concern the subject in hand, and which I shall describe 
 with some detail. Diagrammatically speaking, the main branches of the superior mesenteric 
 artery unite with each other by means of loops, which are called for convenience 'primary loops;' 
 in some parts of the tube, ' secondary loops,' and even, occasionally, ' tertiary loops' are super- 
 
 Fro. 872.— A loop of intestine at twelve feet. The vessels are smaller. The primary loops are lost in the f^f 
 rrL^nerim'.^^^'' ^?" *^'"J.'^''-^ loops are visible. ^ The va.sa recta are shorte^.'^ScTrf frregS ar and branchi^' 
 (Ihe specimen came from the same subject which furnished Figs. 869 and 871.) (Monks ) orancning. 
 
 imposed upon the.se. From the.se loops little straight vessels— the vasa recta already referred to 
 ^vf^u lu ^ T'' "R?." ^^^""^ ^^""^ r^mxl^, alternating, as a rule, as to the side of the intestine 
 
 which they supply. The mesenteric veins are arranged in a manner somewhat similar to the 
 arteries. 
 
 Fig. 873. — .\ loop of intestine at seventeen feet. The mesentery is ooaaue and small f qK= r^t f„f \. :„ i 
 
 appear along the mesenteric border of the gut. The vesWls are reoresPnteH hV ^t.^whof v . §"* ^? 
 
 " The Loops of the Mesenteric Vessels (Figs. 869,870, 871, 872, and 873).— Opposite the upper 
 part of the bowel there are only primary loops. Occasionally a secondary loop appears but it 
 IS small and insignificant as compared with the primary loops, which are large and quite regular 
 As we proceed down the bowel secondary loops becom'e more numerous, larger, and approach 
 
1268 THE ORGANS OF DIGESTION 
 
 nearer to the bowel than the primary loops in the upper part. As a rule, secondary loops 
 become a prominent feature at about the fourth foot. As we continue farther downward, the 
 secondary loops (and, possibly, tertiary loops) become still more numerous and the primary 
 loops smaller, the loops all the time getting nearer and nearer to the gut. Opposite the lower 
 part of the gut the loops generally lose their characteristic appearance, and are represented by 
 a complicated network. 
 
 " The Vasa Recta. — Opposite the upper part of the intestine the vasa recta are from three to 
 five centimetres long, when the loop of small intestine to which they run is lifted up so as to 
 put them gently on the stretch. They are straight, large, and regular, and rarely give off branches 
 in the mesentery. In the lower third they are very short, being generally less than one centimetre 
 in length. Here they are less straight, smaller, less regular, and have frequent branches in the 
 mesentery." 
 
 Fig. 874. — A loop of intestine at twenty feet. The gut appears to be thick and large. The mesentery is 
 quite fat and opaque, and large and numerous fat-tabs are present. The vessels, which are complicated, are 
 seen with difficulty, and are represented by mere grooves in the fat. (The subject was a stout woman, and the 
 entire length of the gut was twenty-one feet.) (Monks.) 
 
 The translucency of the mesentery varies greatly; in some parts it may be almost transparent, 
 in others almost or quite opaque. Its thinnest part is above. It is thickened below by fat, fibrous 
 tissue, and muscular tissue. In very fat subjects it may be impossible to see the vessels (Monks). 
 According to Monks, if a loop is raised and looked at against the light close to the gut '' little 
 transparent spaces" are seen between the vasa recta, and even in the thickest mesentery; some 
 of these ''lunettes" exist along the upper portion of the intestine. As we descend in our exam- 
 ination, they grow smaller and become fatty, and disappear about the eighth foot of the intes- 
 tine.' The same author shows that the mesentery of the lower third of the intestine, except in 
 the thinnest individuals, contains little collections of fat on the border of the mesentery, which 
 project toward the bowel and may even extend upon it. 
 
 THE STOMACH (VENTRICULUS) (Figs. 861, 875, 876, 878, 879). 
 
 The stomach is the principal organ of digestion. It is the most dilated part of 
 the aUmentary canal, and is situated between the termination of the oesophagus 
 (cardia) and the commencement of the small intestine. Its form varies because 
 of varied conditions, but, as a rule, it is somewhat pyriform. It is placed, in 
 part, immediately behind the anterior wall of the abdomen and beneath the 
 Diaphragm. Viewing the stomach from in front it appears that the right margin 
 of the oesophagus is continued downward as the upper two-thirds of the lesser 
 curvature of the stomach, the remaining third of this border bending sharply 
 
 ' Annals of Surgery, October, 1903. 
 
THE STOMACH 1269 
 
 backward and to the right, to complete the smaller curvature (Fig. 875). The 
 greater curvature begins at the left border of the termination of the oesophagus in 
 a somewhat acute angle; it then passes upward and to the left to the under surface 
 of the Diaphragm, with which it lies in contact for some distance, and then sweeps 
 downward with a convexity to the left, and, continued across the middle line of the 
 body, finally turns upward and backward, to terminate at the commencement of 
 the small intestine. It will thus be seen that the stomach may be divided into a 
 fundus (fundus ventriculi) and a middle portion or body (corpus ventriculi). The 
 portion of the body adjacent to the cardia being known as the cardiac portion (pars 
 cardiaca), the long axis of which is directed downward with a slight inclination 
 forward and to the right; and the portion adjacent to the pylorus being known 
 as the pyloric portion (pars pylorica), the long axis of which is horizontal with 
 an inclination backward. Of the two openings, the cardiac orifice, by which it 
 communicates with the oesophagus, is situated slightly to the left of the middle 
 line of the body to the right of the fundus, or dilated upper extremity of the 
 stomach, and is directed downward ; the other, 
 
 the pyloric orifice, by which it communicates Fundus 
 
 with the small intestine, is on a lower plane, 
 close to the right of the mid-line, and looks Cardiac onfice^ 
 directly backward. 
 
 Relations of the Stomach. — The stomach Lesser curvature^ 
 
 lies in a space or chamber called the stomach 
 
 chamber (Fig. 861) . When distended the viscus 
 
 completely fills the space. When the stomach 
 
 is empty it lies upon the floor of the chamber, 
 
 and the portion it has vacated is occupied by Antrum 
 
 the transverse colon, which ascends in front of pylori 
 
 the stomach and finally gets above it. The Fi«. 875.-Diagrammatic outline of the 
 
 anterior wall of the stomach chamber is formed 
 
 by the anterior abdominal wall. The roof is formed by the under surface of the 
 Diaphragm and the under surface of the left lobe of the liver. The floor is formed 
 by the left suprarenal capsule and the summit of the left kidney, the gastric face 
 of the spleen, the upper surface of the pancreas, the transverse mesocolon, and 
 the colon .^ 
 
 Surfaces. — The stomach has two surfaces, called anterior and posterior surfaces, 
 and two borders, termed the greater and lesser curvatures. 
 
 In regard to the so-called anterior and posterior surfaces of the stomach, it 
 must be borne in mind that these names are not strictly correct, as the anterior 
 surface has a certain amount of inclination upward and the posterior downward. 
 
 The Anterior, Upper or Parietal Surface (paries anterior). — The anterior surface 
 is directed forward and to the right side. It has a somewhat flattened appearance 
 when the stomach is empty, but when it is full the surface becomes convex. It is 
 in relation with the Diaphragm; the thoracic wall formed by the anterior parts of 
 the seventh, eighth, and ninth ribs of the left side; the left lobe of the liver; and 
 the anterior abdominal wall. Between the part covered by the liver and that 
 covered by the left ribs there is a triangular segment of the anterior wall of the 
 stomach, which is in contact with the abdominal wall and is the only part of the 
 stomach which is visible when the abdominal wall is removed and the viscera 
 allowed to remain in situ. Its area is about 40 sq. cm., and it is of great impor- 
 tance to the surgeon, as the stomach can readily be reached in this situation. 
 Occasionally the transverse colon may be, found lying in front of the lower part 
 of the anterior surface of the stomach. The whole of this surface of the stomach 
 is covered by peritoneum. 
 
 ' Prof. Birmingham in Prof. Cunningham's Text-book of Anatomy. 
 
1270 '^HE OBGANS OF DIGESTION 
 
 The Posterior, Lower or Visceral Surface {'paries 'posterior). — The posterior sur- 
 face of the stomach is directed backward and to the left. It is in relation with 
 the Diaphragm, the gastric surface of the spleen, the left suprarenal capsule, the 
 upper part of the left kidney, the anterior surface of the pancreas, the splenic 
 flexure of the colon, and the ascending layer of the transverse mesocolon. These 
 structures form a shallow concavity or bed, on which this surface of the stomach 
 rests. The transverse mesocolon intervenes between the stomach and the duodeno- 
 jejunal junction and commencement of the ileum. Its greater curvature is in 
 relation with the transverse colon and has attached to it the anterior two layers 
 of the great omentum. Almost the whole of this surface is covered with peri- 
 toneum, but behind the cardiac orifice there is a small portion of the stomach 
 which is uncovered by peritoneum and is in contact with the Diaphragm and fre- 
 quently with the upper portion of the left suprarenal capsule. 
 
 The Lesser Curvature {curvatura ventriculi Tninor). — The lesser curvature of the 
 stomach extends between the cardiac and pyloric orifices along the right border 
 of the organ. It descends in front of the left crus of the Diaphragm, along the left 
 side of the eleventh and twelfth dorsal vertebrae, and then turning to the right it 
 crosses the first lumbar vertebra and ascends to the pylorus. It gives attachment 
 to the two layers of the gastro-hepatic omentum, between which blood-vessels and 
 lymphatics pass to reach the organ. 
 
 The Greater Curvature {curvatura ventriculi major). — The greater curvature of 
 the stomach is directed to the left, and is four or five times as long as the lesser 
 curvature. Starting from the cardiac orifice, it forms an arch to the left with its 
 convexity upward, the highest point of which is on a level with the costal cartilage 
 of the sixth rib of the left side. It then passes nearly straight downward, with a 
 slight convexity to the left, as low as the costal cartilage of the ninth rib, and then 
 turns to the right to end at the pylorus. As it crosses the median line the lowest 
 edge of the greater curvature is about two fingers' breadth above the umbilicus. 
 The lower part of the greater curvature gives attachment to the two anterior 
 layers of the great omentum, between which layers vessels and lymphatics pass 
 to the organ. 
 
 The Gardia (Fig. 876) . — ^The cardia is the point at which the oesophagus enters 
 the stomach wall. The opening is called the cardiac orifice or the oesophageal 
 opening. At the cardia the circular muscular fibres constitute a sphincter. 
 
 The Cardiac Orifice (Fig. 876) . — The cardiac orifice is the opening by which the 
 oesophagus communicates .with the stomach. It is therefore sometimes termed 
 the oesophageal opening. It is the most fixed part of the stomach, and is situated 
 about two inches below the highest part of the fundus on a level with the body 
 of the tenth or eleventh dorsal vertebra to the left and a little in front of the aorta. 
 This would correspond on the anterior surface of the body to the articulation of 
 the seventh left costal cartilage to the sternum. It is placed far oif from the surface 
 and is at least four inches back of the seventh left chondro-sternal articulation. 
 
 The Pylorus (Fig. 876). — The pylorus is the point at which the stomach passes 
 into the duodenum. The opening of communication is called the pyloric orifice. 
 At the pylorus the muscular fibres constitute a sphincter. 
 
 The Pyloric Orifice (Fig. 876) . — The pyloric orifice communicates with the duo- 
 denum, the aperture being guarded by a valve (Fig. 877). Its position varies with 
 the movements of the stomach. When the stomach is empty the pylorus is situ- 
 ated just to the right of the median line of the body, on a level with the upper 
 border of the first lumbar vertebra. On the anterior surface of the body its posi- 
 tion would be indicated by a point one inch below the tip of the ensiform cartilage 
 and a little to the right. As the stomach becomes distended the pylorus moves to 
 the right, and in a fully distended stomach may be situated two or three inches 
 to the right of the median line. The direction of the pylorus is upward and to 
 
THE STOMACH 
 
 1271 
 
 the right, which position prevents "the weight of the gastric contents bearing 
 directly on the sphincter apparatus."^ The pylorus is on a somewhat higher level 
 than the lowest point of the stomach. Near the pylorus the stomach frequently 
 exhibits a slight dilatation, which is named the antrum of the pylorus {antrum 
 pyloricum). The pylorus is indicated by a constriction, the direction of which 
 is circular. The pylorus lies upon the neck of the pancreas behind. Above it 
 and in front of it is the liver. 
 
 The size of the stomach varies considerably in different subjects. When mod- 
 erately distended its greatest length, from the top of the fundus to the lowest part 
 of the greater curvature, is from ten to twelve inches and its diameter at the 
 widest part from four to five inches. The distance between the two orifices is three 
 to six inches, and the measurement from the anterior to the posterior wall three 
 and a half inches. Its weight, according to Clendinning, is about four ounces and 
 a half, and its capacity in the adult male is five to eight pints. The stomach of a 
 newborn child holds about one ounce. 
 
 Cystic duct. 
 
 Fig. 876. — The mucous membrane of the stomach and duodenum with the bile-ducts. 
 
 Alterations in Position. — There is no organ in the body the position and connections of which 
 present such frequent alterations as the stomach. When empty, it lies at the back part of the 
 abdomen, some distance from the surface, and is in the left hypochondriac region and the left 
 portion of the epigastric region. Its fundus is directed upward and backward toward the Dia- 
 phragm. The long axis of the viscus is nearly horizontal. Its pyloric end is directed upward 
 and backward, is situated close to or very slightly to the right of the middle line, covered in front 
 by the left lobe of the liver, and being on a level with the first lumbar vertebra. When empty, 
 the stomach assumes a more or less cylindrical form, especially noticeable at its pyloric end. The 
 entire viscus is small and contracted, and the pyloric region resembles the intestine. When the 
 stomach is distended, its surfaces, which are flattened when the organ is empty, become convex 
 and the shape becomes pyriform. The viscus becomes very oblique and approaches the vertical, 
 
 ' W. J. Mayo, Medical Record. June 11, 1904. 
 
1272 
 
 THE ORGANS OF DIGESTION 
 
 its long axis being downward, forward, and to the right. The greater curvature is elevated and 
 carried forward, so that the anterior surface is turned more or less upward and the posterior 
 surface downward, and the stomach is brought well against the anterior wall of the abdomen. Its 
 fundus expands and rises considerably above the level of the cardiac orifice; in doing this the 
 Diaphragm is forced upward, contracting the cavity of the chest; hence the dyspnoea complained 
 of, from inspiration being impeded. The apex of the heart is also tilted upward; hence the 
 oppression in this region and the palpitation experienced in extreme distention of the stomach. 
 The left lobe of the liver is pushed to the right side. When the stomach becomes distended 
 the change in the position of the pylorus is very considerable; it is shifted to the right, some 
 two or three inches from the median line, and lies under cover of the liver, near the neck of the 
 gall-bladder. In consequence of the distention of the stomach the lesser cul-de-sac bulges over 
 the pylorus, concealing it from view, and causing it to undergo a rotation, so that its orifice is 
 directed backward. When the stomach is greatly distended its lower border may enter the 
 umbilical and the left lumbar regions. During inspiration the stomach is displaced downward 
 by the descent of the Diaphragm, and it is elevated by the pressure of the abdominal muscles dur- 
 ing expiration. Pressure from without, as from tight lacing, pushes the stomach down toward the 
 pelvis. In fact, in the female, because of tight lacing, the stomach may be to the left side of the 
 vertebral column and nearly vertical in direction, the lower portion being sharply angled upward 
 toward the pylorus, which lies underneath the liver. Besides the angulation, the lower end, the 
 stomach may have a median constriction, and there may even be an hour-glass stomach. The 
 descent of the stomach from tight lacing may cause the pancreas to become nearly vertical. In 
 disease the position and connection of the stomach may be greatly changed, from the accumula- 
 tion of fluid in the chest or abdomen, or from alteration in size of any of the surrounding viscera. 
 Variations according to Age. — In an early period of development the stomach is vertical, and in 
 the newborn child it is more vertical than later on in life, as owing to the large size of the liver 
 it is more pushed over to the left side of the abdomen, and the whole of the anterior surface is 
 covered by the left lobe of this organ. 
 
 Fig. 877. — Diafi:rammatic view 
 of the coats of the stomach, duo- 
 denum, and pylorus. The ridge is 
 the pyloric valve. (Allan Thom- 
 son.) 
 
 On looking into the pyloric end of the stomach, the mucous membrane is found 
 projecting inward in the form of a circular fold, the pyloric valve (Fig. 877), leaving 
 
 a narrow circular aperture, about half an inch in 
 diameter, by which the stomach communicates with 
 the duodenum. 
 
 The Pyloric Valve (valvula pylori) (Fig. 877) . — The 
 pyloric valve is formed by a reduplication of the mucous 
 membrane of the stomach,containing numerous circular 
 fibres, which are aggregated into a thick circular ring, 
 the pyloric sphincter (ni. sphincter pylori) ; the longitu- 
 dinal fibres and serous membrane being continued 
 over the fold without assisting in its formation (Fig. 877) . 
 The pylorus is normally kept closed by the action of 
 this aggregation of circular fibres which constitutes the 
 Sphincter muscle. During the early stage of digestion 
 it remains closed, but after a time opens now and then. The opening becomes 
 more frequent and the period of patency is prolonged as digestion advances. 
 
 The diameter of the pylorus is uncertain. It is usually said to be half an inch. 
 But it is closed when the pylorus is at rest, and it can certainly dilate even in 
 a child to at least an inch and let bodies of this size pass through. 
 
 The Peritoneum. — The great omentum comes off from the greater curvature of 
 the stomach and passes to the transverse colon. The lesser omentum comes off 
 from the lesser curvature and passes to the liver. The gastro -splenic ligament or 
 omentum passes from the under surface of the stomach just below the greater 
 curvature to the spleen. A fold of peritoneum passes up from the stomach along 
 the left side of the oesophagus to the Diaphragm. This is the gastro -phrenic 
 ligament. 
 
 Supports of the Stomach. — The stomach lies on the bed of the stomach cham- 
 ber, which was described on p. 1269. The great omentum gives no support to 
 the stomach, neither does the gastro-splenic ligament, because of the movability 
 of the spleen. The lesser omentum does give support to the stomach and so do 
 
THE STOMACH 
 
 1273 
 
 the gastro -phrenic ligament and the hepato -duodenal ligament. The two chief 
 points of support are the attachment of the oesophagus to the Diaphragm and 
 the fixation of the duodenum to the front of the vertebral column. 
 
 Structure. — The wall of the stomach consists of four coats: serous, muscular, 
 areolar, and mucous, together with vessels and nerves. 
 
 The Peritoneal or Serous Coat {tunica serosa).— Th& peritoneal or serous coat 
 covers the entire surface of the organ, excepting along the greater and lesser 
 curvatures, at the points of attachment of the greater and lesser omenta; at 
 each curvature the two layers of peritoneum leave a small triangular space, to 
 which the peritoneum is not attached, although it is attached in front of it and 
 back of it. Along these spaces the nutrient vessels and nerves pass. On the 
 posterior surface of the stomach, close to the cardiac orifice and below and to 
 the left of it, there is a smaller triangular area uncovered by peritoneum, where 
 the organ is in contact with the under surface of the Diaphragm, and it may be 
 
 Fig. 878. — The superficial muscular layer of the stomach, viewed from above and in front. (Spalteholz.) 
 
 with the left suprarenal body and the summit of the left kidney. When the 
 stomach is moderately distended this uncovered area measures about one and a 
 half inches from above downward, and about two inches from before backward. 
 At the left angle of this uncovered area the insertion of the great omentum 
 begins. At the right angle the gastric artery reaches the stomach. 
 
 The Muscular Coat {tunica muscularis) (Figs. 878 and 879). — The muscular coat 
 is situated immediately beneath the serous covering, to which it is closely connected. 
 It consists of three sets of fibres — longitudinal, circular, and oblique. 
 
 The Longitudinal Fibres {stratum longitudinale) are most superficial; they are 
 continuous with the longitudinal fibres of the oesophagus, radiating in a stellate 
 
1274 
 
 THE ORGANS OF DIGESTION 
 
 manner from the cardiac orifice. They are most distinct along the curvatures, 
 especially the lesser, but are very thinly distributed over the surfaces. At the 
 pyloric end they are more thickly distributed, and continuous with the longitudinal 
 fibres of the small intestine. The bundles of longitudinal muscle-fibre on the upper 
 and lower surfaces of the pylorus are particularly firm and distinct, and are called 
 the pyloric ligaments (ligamenta pylori). 
 
 The Circular Fibres (stratum circulare) form a uniform layer over the whole 
 extent of the stomach, except the fundus, beneath the longitudinal fibres. At the 
 pylorus they are most abundant, and are aggregated into a circular ring or sphinc- 
 ter (w. sphincter pylori), which projects into the cavity, and forms, with the fold 
 of mucous membrane covering its surface, the pyloric valve {valvula pylori) (Fig. 
 877). They are continuous with the circular fibres of the oesophagus. 
 
 Fig. 879.- — The middle and deep muscular layer of the stomach, viewed from above and in front. (Spalteholz.) 
 
 The Oblique Fibres {fibrae ohliquae) arise at the left side of the cardia from the 
 circular fibres of the oesophagus. The fibres pass down in the anterior and pos- 
 terior walls. Those of the anterior wall are parallel to the lesser curvature and 
 almost reach the pylorus. Those of the posterior wall are more nearly transverse 
 to the long axis of the stomach (Spalteholz). These fibres gradually assume the 
 direction of the circular fibres and terminate in them. The layer of oblique fibres 
 is beneath the circular layer. Certain oblique muscular fibres encircle the fundus 
 of the stomach in a series of rings. 
 
 The Areolar or Submucous Coat {tela submucosa). — The areolar or submucous 
 coat consists of loose, filamentous, areolar tissue, connecting the mucous and 
 muscular layers. It supports the blood-vessels previous to their distribution to 
 the mucous membrane; hence it is sometimes called the vascular coat. 
 
THE STOMACH 
 
 1275 
 
 The Mucous Membrane {tunica mucosa) (Figs. 880, 881, and 882). — The 
 mucous membrane is thick; its surface smooth, soft, and velvety. In the fresh 
 state it is of a pinkish tinge at the pyloric end, and of a red or reddish-brown 
 
 Gastric Areas. Rugce. 
 
 i"iG. 880. — Mucous membrane of the stomach, from the pars pylorica, viewed from the surface. X 5. (Spalteholz.) 
 
 color over the rest of the surface. In in- 
 fancy it is of a brighter hue, the vascular 
 redness being more marked. It is thin at 
 the cardiac extremity, but thicker toward 
 the pylorus. During the contracted state 
 of the organ it is thrown into numerous 
 plaits or rugae {'plicae mucosae) (Figs. 880 
 and 882 A), which for the most part have a 
 longitudinal direction, and are most marked 
 toward the lesser end of the stomach and 
 along the greater curvature, and which 
 contain also submucous tissue. These 
 folds are entirely obliterated when the 
 organ becomes distended. A constant fold 
 exists at the pylorus (Fig. 877). It is called 
 the pyloric valve, and is produced by the 
 presence beneath it of the Sphincter muscle. 
 Besides the large folds or rugae and the 
 pyloric valve, there are numerous small 
 elevations of mucous membrane known as 
 gastric areas {areas gastricae), which are 
 partly separated from each other by furrows 
 and which vary greatly in shape (Fig. 880) . 
 According to Spalteholz, each one of these 
 elevations has an area of several square 
 millimetres. 
 
 Ridges between the alveoli. 
 K 
 
 Gastric alveoli. 
 
 Fig. 881. — Mucous membrane of the stomach, 
 from the pars pylorica, viewed from the surface. X 16. 
 (Spalteholz.) 
 
1276 
 
 THE ORGANS OF DIGESTION 
 
 Structure of the Mucous Membrane. — When examined with a lens the 
 inner surface of the mucous membrane presents a pecuHar honeycomb appear- 
 
 MAMMILUE V.S 
 
 MOUTHS or GASTRIC 
 
 GLANDS, WITH GLAND 
 
 TUBES AT BOTTOM 
 
 DEPRESSION BETWEEN 
 TWO MAMMILUE 
 
 MOUTH OF 
 GASTRIC GLAND 
 
 Fig. 882. — The mucous membrane of the stomach. A, natural size; B, magnified 25 diameters. In ^ the 
 rugae and the mammillated surface are shown. In B the gland mouths (foveolae gastricae), with the gland tubes 
 leading from some of them, and the ridges separating the mouths (plica villosae) are seen. (Cunningham.) 
 
 Fig. 883.— Pyloric gland. 
 
 Fig. 884. — Peptic gastric gland. 
 
 ance, from being covered with small shallow depressions or alveoli {foveolae 
 gastricae) (Figs. 881 and 882, B) of a polygonal or hexagonal form, which vary 
 
THE STOMACH 1277 
 
 from -j^-Q to 2-5T of an inch in diameter, and are separated by slightly elevated 
 ridges {plicae villosae). The ridges are most distinct at the pylorus. These 
 foveolae are within the areae gastricae. The ridges on section resemble villi. In 
 the bottom of the alveola are seen the orifices of minute tubes, the gastric glands 
 (Fig. 882 B), which are placed perpendicularly side by side throughout the 
 entire substance of the mucous membrane. The surface of the mucous membrane 
 of the stomach is covered by a single layer of columnar epithelium; it lines the 
 alveoli, and also for a certain distance the mouths of the gastric glands. This 
 epithelium commences very abruptly at the cardiac orifice, where the cells sud- 
 denly change in character from the stratified epithelium of the oesophagus. The 
 cells are elongated, and consist of two parts, the inner or attached portions 
 being granular, and the outer or free parts being clear and occupied by a muco- 
 albuminous substance. 
 
 The Gastric Glands. — ^The gastric glands are of three kinds: the true gastric 
 glands, the pyloric glands, and the cardiac glands. 
 
 The True Gastric Glands (Fig. 884) are called also the oxyntic glands, the fundus 
 glands, and the peptic glands (glandulae gastricae propriae). They are distributed 
 throughout the entire fundus and body, and maybe found even at the pylorus. They 
 are tubular in character, and are formed of a delicate basement-membrane, lined 
 with epithelium. The basement-membrane consists of flattened transparent endo- 
 thelial cells, with processes which extend between and support the epithelium. Into 
 the crypt of a true gastric gland three or more caecal tubes, branched or unbranched, 
 empty. The duct, however, in these glands is shorter than in the other variety, 
 sometimes not amounting to more than one-sixth of the whole length of the gland; 
 it is lined throughout by columnar epithelium. At the point where the terminal 
 tubes open into the duct, and which is termed the neck, the epithelium alters, and 
 consists of short columnar or polyhedral, granular cells, which almost fill the tube, 
 so that the lumen becomes suddenly constricted, and is continued down as a very 
 fine channel. They are known as the chief or the peptic or the central cells of the 
 glands, and furnish pepsin. Between these cells and the basement-membrane are 
 found other darker granular-looking cells, studded throughout the tubes at inter- 
 vals, and giving it a beaded or varicose appearance. These are known as the 
 parietal or oxyntic cells. Some of the parietal cells empty directly into the lumen 
 of the gland by secretory capillaries; others empty by a duct which divides into 
 secretory capillaries. The parietal cells secrete the acid of the gastric juice. 
 Between the glands the mucous membrane consists of a connective-tissue frame- 
 work with lymphoid tissue. In places this latter tissue, especially in early life, is 
 collected into little masses, which to a certain extent resemble the solitary glands 
 of the intestine, and are by some termed the lenticular glands of the stomach. They 
 are not, however, so distinctly circumscribed as the solitary glands. 
 
 The Pyloric Glands {glandulae pyloricae) (Fig. 883) are the branched tubular 
 glands, and secrete mucus. 
 
 They are placed most plentifully about the pylorus, but between the fundus and 
 pylorus, in the region known as the transitional or intermediate zone, both true 
 gastric glands and pyloric glands are found. Each pyloric gland consists of two 
 or three short, closed tubes opening into a common duct, the external orifice of 
 which is situated at the bottom of an alveolus. The caecal tubes are wavy, and 
 are of about equal length with the duct. The tubes and duct are lined through- 
 out with epithelium, the duct being lined by columnar cells continuous with the 
 epithelium lining the surface of the mucous membrane of the stomach, the tubes 
 with shorter and more cubical cells, which are finely granular. The pyloric 
 glands branch more frequently, are more curved in direction, and open into 
 deeper foveolae than the true gastric glands (Szymonowicz). They contain only 
 chief or peptic cells and do not possess parietal cells. 
 
1278 
 
 THE ORGANS OF DIGESTION 
 
 PLEXUS 
 
 BENEATH THE 
 EPITHELIUM 
 
 CLANDULAR 
 PLEXUS 
 
 The Cardiac Glands are found about the oesophageal orifice. They resemble 
 
 the pyloric glands. 
 
 Beneath the mucous membrane, and between it and the submucous coat, is a 
 
 thin stratum of involuntary muscular fibre {muscularis mucosae), which in some 
 
 parts consists only of a single longitudinal layer; in others, of two layers, an inner 
 
 circular, and an outer longitudinal. 
 
 Vessels and Nerves, — The arteries supplying the stomach are — the gastric or 
 
 coronary, the pyloric and the right gastro -epiploic branch of the gastro-duodendal, the 
 
 left gastro -epiploic and vasa brevia from 
 the splenic. The gastric artery passes to the 
 lesser curvature just below the cardia. It 
 gives off the oesophageal branch, and passes 
 from left to right along the lesser curva- 
 ture of the stomach beneath the perito- 
 neimi between the two layers of the lesser 
 omentum and upon the wall of the stomach. 
 It may in this course be a single vessel, or 
 may divide into two branches, which run 
 along each side of the lesser curvature (Fig. 
 886). If there is a single artery it gives off 
 six or seven descending branches to the an- 
 terior wall and about the same number to 
 
 Fig. SSS.-TerminationsTTthe blood-vessels in the pOStCHOr Wall of the stoiuach. It alsO 
 
 andcharpy.r*'™^'"^"^"^^''^ ^*'°'"^*'^" ^^'''"^'' g^^cs branches to the lesser omentum. If 
 
 two vascular arches form, one gives branches 
 to the anterior wall of the stomach, the other to the posterior wall, and both to 
 the lesser omentum. The termination of the gastric anastomoses with the 
 pyloric branch or two rami of the pyloric branch of the hepatic artery. From 
 each arch six or seven descending branches come off to the anterior and posterior 
 
 ARTERIOLE 
 
 PLEXUS OF 
 
 BLOODVESSELS 
 
 IN SUBMUCOUS 
 
 TISSUE 
 
 SPLENIC 
 ARTERY 
 
 GASTRO- DUODENAL 
 ARTERY 
 
 RIGHT GASTRO- 
 EPIPLOIC ARTERY 
 
 LEFT GASTRO- 
 EPIPLOIC ARTERY 
 
 Fig. 886. — The arteries of the anterior surface of the stomach. (Poirier and Charpy.) 
 
 walls of the stomach. The gastro -duodenal artery is given off by the hepatic. 
 From the gastro-duodenal comes the right gastro-epiploic. The left gastro- 
 epiploic comes from the splenic. The right gastro-epiploic artery passes from 
 right to left in the gastro-colic omentum below the greater curvature of the 
 
THE STOMACH 1279 
 
 stomach. The left gastro-epiploic artery passes forward in the gastro-splenic 
 ligament to below the greater curvature of the stomach, and passes from left to 
 right along that curvature in the gastro-colic omentum, and joins the right gastro- 
 epiploic artery. The gastro-epiploic arteries are not upon but are distinctly 
 below the stomach wall. From them numerous gastric branches are sent to the 
 anterior and posterior walls of the stomach, and they anastomose with branches 
 of the gastric and pyloric. Vasa brevia, four or five in number, arise from the 
 splenic, pass forward in the gastro-splenic ligament, and supply the fundus. 
 The arteries of the stomach lie first beneath the peritoneum, but soon enter the 
 muscular coat, supply it, pierce it, ramify in the submucous coat, and are finally 
 distributed to the mucous membrane. The arrangement of the vessels in the 
 mucous membrane is somewhat peculiar (Fig. 885). The arteries break up at 
 the base of the gastric tubules into a plexus of fine capillaries which run upward 
 between the tubules, anastomosing with each other, and ending in a plexus of 
 larger capillaries, which surround the mouths of the tubes and also form hexagonal 
 meshes around the alveoli. 
 
 The capillary networks about the glands give origin to the veins. The various 
 small veins unite and form a plexus in the submucous tissue (Fig. 885). From this 
 plexus come branches which pass through the muscular coat and terminate in the 
 right gastro-epiploic branch of the superior mesenteric, the left gastro-epiploic branch 
 of the splenic, the veins to the splenic which correspond to the vasa brevia arteries, 
 and the gastric or coronary branch of the portal. 
 
 The lymphatics (Figs. 507 and 508) arise in the mucous membrane and terminate 
 in a network in the submucous tissue. From this network trunks arise which 
 perforate the muscular coat in the regions of the curvatures and terminate in the 
 sero-muscular collecting trunks.^ 
 
 According to Cuneo, there are three groups of these collectors. Those from the 
 lesser curvature pass to the point where the gastric artery reaches the stomach and 
 enter the glands along the gastric artery. Those from the greater curvature pass 
 from left to right and enter the sub-pyloric glands. Those from the fundus pass 
 from right to left and end in the splenic glands. Cuneo further pointed out that 
 the region drained by the collectors of the lesser curvature is divided from the 
 others by the line shown in Fig. 507. This division exists on both surfaces of 
 the stomach. The limit between the collectors which drain into the splenic 
 glands and those which drain into the sub-pyloric glands is also shown in 
 Fig. 507. Along the lesser curvature the lymph-glands are few in number and 
 are limited to the pyloric region, and the lymph- vessels are placed directly upon 
 the stomach wall. The lymph-glands and vessels are not upon but are distinctly 
 below the greater curvature. 
 
 The subserous and submucous lymphatic networks of the stomach communi- 
 cate with the corresponding networks of the oesophagus, but in all probability do 
 not communicate with the networks of the duodenum. 
 
 The nerves of the stomach come from the right and left pneumogastrics and from 
 the solar plexus of the sympathetic. The left pneumogastric passes to the front 
 of the stomach, and the right nerve passes to the back, and they unite with the 
 fibres of the sympathetic. The fibres thus formed are mostly non-meduUated. 
 They form Auerbach's plexus in the muscular coat between the circular and lon- 
 gitudinal fibres and Meissner's plexus in the submucous coat, the latter plexus 
 being formed by fibres from the former. Fibres from Meissner's plexus ramify 
 in the submucous coat and terminate in the muscularis mucosae and the mucous 
 membrane, branches passing to the gastric glands and to just beneath the 
 epithelium. 
 
 * The Lymphatics. By Poirier. Cuneo, and Delamare. Translated and edited by Cecil H. Leaf. 
 
1280 THE ORGANS OF DIGESTION 
 
 Movements and Innervation of the Stomach. 
 
 Movements. — It has apparently been demonstrated that the stomach "consists of two parts 
 physiologically distinct."' The cardiac portion of the stomach is a food reservoir in which 
 salivary digestion continues; the pyloric portion is the seat of active digestion. Cannon affirms 
 that there are no peristaltic waves in the cardiac portion, but that as the food passes from the 
 pyloric portion into the intestines, tonic contraction of the muscles of the fundus squeezes the 
 contents of the pyloric portion. Moritz, Levan, and Cannon assert that muscular activity is 
 chiefly manifested in the pyloric portion. In this portion during digestion there is a succes- 
 sion of peristaltic waves, which waves in the human being pass at the rate of three per minute 
 (Moritz). Cannon points out that the efficiency of peristalsis in mixing the food depends 
 upon the contraction of the pyloric sphincter. So long as the sphincter holds, each constric- 
 tion-ring coursing from the middle to the end of the stomach presses the food into a blind pouch; 
 the food, unable to escape through the pyloric opening, has as its only outlet the opening in 
 the advancing ring. This is an admirable device for bringing the food under the influence of 
 the glandular secretions of the pyloric region. For, as a constriction occurs, the secreting sur- 
 face enclosed by the narrowed muscular ring is pressed close around the food within the ring. 
 As the constriction advances it continually presses inward fresh glandular tissue, and further- 
 more, as the constriction advances, a thin stream of food is continuously forced back through 
 the ring and thus past the mouths of the glands. The old view that the pyloric sphincter only 
 opens after several hours' continuance of the process of digestion and that then the stomach 
 empties at once is incorrect. It is emptied in small amounts which escape at frequent intervals 
 because of the intermittent opening of the pylorus. When the pylorus is open a wave of peri- 
 stalsis forces some of the material from the stomach into the duodenum (Cannon). 
 
 Cannon is of the opinion that the pyloric sphincter is caused to relax by the presence of free 
 hydrochloric acid in the pyloric portion of the stomach. When the pylorus is open acid chyme 
 passes into the duodenum and acid in the duodenum causes the pylorus to close. The acid 
 in the duodenum causes a flow of alkaline pancreatic juice and the acid is neutralized. "As 
 the neutralizing proceeds the stimulus closing the pylorus is weakened until the acid in the 
 stomach again opens the sphincter."^ 
 
 Innervation. — The stomach, as previously shown, has nervous plexuses in its walls and is 
 connected to the brain, spinal cord, and sympathetic system. It is probable that gastric peri- 
 stalsis is due to a local reflex from Auerbach's plexus (Magnus), the local reflex being inaugu- 
 rated by local stimulation, which stimulation, in the words of Bayliss and Starling, "produces 
 excitation above and inhibition below the excited spot."* Reversed peristalsis cannot occur 
 if "the reflex mechanism is intact" (Cannon). Cannon in the previously quoted article states 
 that cutting the vagus or splanchnic nerves does not destroy the reflex mechanism of the pylorus, 
 but, nevertheless, it is markedly affected by the central nervous system. 
 
 Surface Form (see p. 1271). — The cardiac orifice corresponds to the articulation of the 
 seventh left costal cartilage with the sternum. The pyloric orifice of the empty stomach is in 
 a vertical line drawn from the right border of the sternum, two and a half or three inches below 
 the level of the sterno-xiphoid articulation. According to Braune, when the stomach is dis- 
 tended, the pylorus moves considerably to the right, as much sometimes as three inches. The 
 fundus of the stomach reaches, on the left side, as high as the level of the sixth costal cartilage 
 of the left side, being a little below and behind the apex of the heart. The portion of the distended 
 stomach which is in contact with the abdominal walls, and is therefore accessible for opening in 
 the operations of gastrotomy and gastrostomy, is represented by a triangular space, the base of 
 which is formed by a line drawn from the tip of the tenth costal cartilage on the left side to the 
 tip of the ninth costal cartilage on the right, and the sides by two lines drawn from the extremity 
 of the eighth costal cartilage on the left side to the ends of the base line. 
 
 Surgical Anatomy. — Operations on the stomach are frequently performed, ulcers are excised, 
 malignant growths are removed with the associated lymphatic involvement, the entire stomach 
 may be removed for cancer, etc. By '' gastrotomy" is meant an incision into the stomach for the 
 removal of a foreign body, or the arrest of hemorrhage or for exploration, the opening being 
 immediately afterward closed — in contradistinction to " gastrostomy" the making of a more or 
 less permanent fistulous opening. Gastrotomy is probably best performed by an incision in the 
 linea alba, especially if the foreign body is large. The cut may reach from the ensiform car- 
 tilage to the umbilicus. The incision may be made over the body itself, where this can be felt, 
 or by one of the incisions for gastrostomy, to be mentioned shortly. The peritoneal cavity 
 is opened, and the point at which the stomach is to be incised decided upon. This portion is 
 then brought out of the abdominal wound and sponges carefully packed around. The stomach 
 is now opened by a transverse incision and the foreign body extracted. The wound in the 
 stomach is then closed by Lembert sutures — i. e., by sutures passed through the peritoneal, 
 
 1 Walter B. Cannon, Medical News, May 20, 1905, 2 Ibid. * Ibid. 
 
MOVEMENTS AND INNERVATION OF THE STOMACH 1281 
 
 muscular and submucous coats in such a way that the peritoneal surfaces on each side of the 
 wound are brought into apposition. Gastrostomy was formerly done in two stages by the direct 
 method. The first stage consisted in opening the abdomen, drawing up the stomach into the 
 external wound, and fixing it there; and the second stage, performed from two to four days 
 afterward, consisted in opening the stomach. The operation is now done by a valvular method. 
 The following plan is known as the Ssabanejew-Frank operation. An incision is commenced 
 opposite the .eighth intercostal space, two inches to the left of the median line, and carried 
 downward for three inches. By this incision the fibres of the Rectus muscle are exposed and 
 these are separated from each other in the same line. The posterior layer of the sheath, the 
 transversalis fascia and the peritoneum, are then divided, and the peritoneal cavity is opened. 
 Instead of the above incision, the curved incision of Fenger can be made at the margin of the 
 left costal cartilages. The anterior wall of the stomach is now seized and drawn out of the 
 wound and a silk suture passed through its submucous, muscular, and serous coats at the point 
 selected for opening the viscus. This is held by an assistant so that a long conical divertic- 
 ulum of the stomach protrudes from the external wound, and the parietal peritoneum and 
 the posterior layer of the sheath of the rectus are sutured to the base of the cone. A second 
 incision is made through the skin, over the margin of the costal cartilage, above and a little to the 
 outer side of the first incision. If Fenger's incision were used, the second incision should be 
 above the margin of the cartilages. With a pair of dressing forceps a track is made under the 
 skin through the subcutaneous tissue from the one opening to the other and the diverticulum of 
 the stomach is drawn along this track by means of the suture inserted into it ; so that its apex 
 appears at the second opening. A small perforation is now made into the stomach through 
 this protruding apex and its margin carefully and accurately sutured to the margin of the 
 external wound. The remainder of this incision and the whole of the first incision are then 
 closed in the ordinary way and the wound dressed. 
 
 In cases of (jastric ulcer, perforation sometimes takes place, and this was formerly regarded 
 as an almost fatal complication. In the present day, by opening the abdomen and closing 
 the perforation, which is generally situated on the anterior surface of the stomach, a consider- 
 able percentage of cases are cured, provided the operation is undertaken within twelve to fifteen 
 hours after the perforation has taken place. The opening is best closed by bringing the peri- 
 toneal surfaces on either side into apposition by means of Lembert sutures. 
 
 Pylorectomy or excision of the pylorus is performed, particularly for early cancer, but is also 
 done for cicatricial stricture and for ulcer. The mortality after operation for cancer was, until 
 recently, very great, but of late years it has been notably reduced, though it is still much higher 
 than that which follows operation for any non-malignant condition. 
 
 In operating for cancer, bear in mind Cun^o's study of the lymphatics (page 806). These 
 observations indicate that the fundus and two-thirds of the greater curvature are free from 
 lymphatic involvement in pyloric cancer.' In every operable case of cancer of the pylorus the 
 entire lesser curvature must be removed up to the gastric artery (Mikulicz's point), and the 
 greater curvature must be removed to the left of the involved glands (Hartmann's rule). 
 
 Gastro-enterostomy is an operation which establishes a fistulous communication between the 
 stomach and jejunum. The operation is often called gastro-jejunostomy. The opening may be 
 made upon either the anterior or the posterior wall of the stomach, between the cardia and the 
 seat of pyloric disease. The operation is employed for stricture of the pylorus (benign or 
 malignant), and occasionally for ulcer of the stomach. 
 
 Loreta's operation is digital divulsion of the pylorus for cicatricial stricture, the stomach being 
 incised transversely near the pylorus to admit the finger, and the wound in the stomach being 
 sutured after division has been effected. The operation has been abandoned, because contraction 
 recurs. 
 
 Pyloroplasty, or the Heineke-Mikulicz operation, displaced Loreta's operation. In this pro- 
 cedure an incision is made through the stricture in the direction of the long axis of the stomach 
 and bowel. By making traction on each side of the incision, the longitudinal wound assumes a 
 vertical direction, and sutures are inserted so as to close the wound in a vertical line. The method 
 of pyloroplasty devised by Finney, of Baltimore, makes a large permanent opening at the 
 most dependent part of the stomach, and is the most satisfactory method of which we are 
 possessed.^ 
 
 Total gastrectomy is the removal of the entire stomach. It is only used for cancer. It was first 
 performed by Conner, of Cincinnati. The first successful operation was done by Schlatter, of 
 Zurich, in 1898. A number of successes have been reported. It is a justifiable operation only in 
 a case in which almost the entire stomach is cancerous, in which the viscus is movable, in which 
 there are no secondary deposits, and no irremovable diseased glands. 
 
 Gastro-gastrostomy is an operation employed in hour-glass stomach. In this operation an 
 anastomosis is made between the pyloric and cardiac ends of the stomach. 
 
 ' William J. Mayo, Annals of Surgery, March, 1904. 
 * Johns Hopkins Hospital Bulletin, July, 1902. 
 
 81 
 
1282 THE ORGANS OF DIGESTION 
 
 Gastroplication is the operation of suturing the stomach wall into folds or reefs, in order to 
 lessen its size. It is employed in some cases of gastric dilatation. 
 
 Gastroptosis is a condition in which the stomach is displaced downward. In some of these 
 cases the greater curvature almost reaches the level of the symphysis pubis, and the lesser curva- 
 ture is midway between the umbilicus and ensiform cartilage. The condition is usually associated 
 with enteroptosis and movable kidney (nephroptosis). In this condition the gastro-hepatic 
 omentum and the gastro-phrenic ligament are pulled upon and lengthened. The best operation 
 for gastroptosis was devised by Beyea. He applies sutures so as to make folds in and thus shorten 
 the stretched ligament and omentum. Thus the stomach is elevated to its proper position, and 
 its mobility is not lessened, as it is in other operations which suture it to the abdominal wall. 
 
 THE SMALL INTESTINE (INTESTINUM TENUE). 
 
 The small intestine is a convoluted tube, extending from the pylorus to the 
 ileo-caecal valve, where it terminates in the large intestine. It fills up the greater 
 part of the abdominal cavity and of the pelvic cavity. It is about twenty feet in 
 length/ and gradually diminishes in size from its commencement to its termina- 
 tion. The diameter of the duodenum is almost two inches; the diameter of the 
 lower portion of the small intestine is little more than one inch. It is contained 
 in the central and lower part of the abdominal cavity, and is surrounded above 
 and at the sides by the large intestine; a portion of it extends below the brim of 
 the pelvis and lies in front of the rectum; it is in relation, in front, with the great 
 omentum and abdominal parietes; and connected to the spine by a fold of peri- 
 toneum, the mesentery (p. 1257) . The small intestine is divisible into three portions 
 — the duodenum, the jejunum, and ileum. 
 
 The Duodenum (Figs. 887, 892, 893, 894, 895). 
 
 The duodenum has received its name from being about equal in length to the 
 breadth of twelve fingers (ten inches). It is the shortest, the widest, and the most 
 fixed part of the small intestine, being closely and firmly attached to the posterior 
 abdominal wall. It does not possess a mesentery. Somewhat more than the 
 upper half of the duodenum is placed in the epigastric region; the remainder is in 
 the umbilical region. The duodenum, with the exception of the ascending portion, 
 is to the right of the median line. Its course presents a remarkable curve, which 
 in the adult, as regards the greater part of its extent, is horseshoe-shaped, though 
 sometimes, in consequence of the transverse portion being very short or alto- 
 gether wanting, it partakes more of the character of the letter V. The opening 
 of the horseshoe being directed upward and to the left. In children up to 
 the age of about seven the duodenum is annular. The two extremities of 
 the duodenum are nearly on the same level, the exit being slightly lower than the 
 entrance. The two ends are about two inches apart; and between them it 
 describes a regular curve embracing the head of the pancreas, the neck of which 
 lies between the two extremities of the ring. 
 
 In the adult the course of the duodenum is as follows: commencing at the 
 pylorus the direction of the first portion depends upon the amount of distention 
 of the stomach and therefore upon the position of the pylorus. When the stomach 
 is empty and the pylorus is situated at the right of the upper border of the first 
 lumbar vertebra, it is nearly horizontal and transverse; but where the stomach is 
 distended, in consequence of the alteration of the position of the pylorus to the 
 right the proximal end of the duodenum also becomes altered in position, while the 
 
 I Treves states that in one hundred cases the average length of the small intestine in the adult male was 22 
 feet 6 inches, and in the adult female 23 feet 4 inches ; but that it varies very much, the extremes in the male 
 being 31 feet 10 inches in one case and 15 feet 6 inches in another, a difference of over 15 feet. He states that 
 he has convinced himself that the length of the bowel is independent, in the adult, of age, height, and weight. — 
 liiD. of 15th English edition. 
 
THE DUODENUM 
 
 1283 
 
 distal end remains fixed and the direction of this portion of the bowel is now 
 antero-posterior. Whether directed transversely or antero-posteriorly, it reaches 
 
 Tributary to vena cava. 
 
 Hepatic artei-y, portal 
 vein, and bile duct 
 
 Supra- renal 
 capsule 
 
 ■a of Diaphragm. 
 Gastric artery. 
 
 Bight 
 
 renal 
 
 vessels 
 
 enic 
 artery. 
 
 ilenic 
 vein. 
 
 Fto 887 —Relations of duodenum, pancreas, and spleen. (From a cast by Professor Birmingham.') 
 ' The dotted line represents the hne of attachment of the transverse mesocolon. 
 
 the under surface of the liver, where it takes a sharp curve and descends along the 
 right side of the vertebral column, for a variable distance, generally to the body of 
 
 1 In the subject from which the cast was taken the left kidney was lower than normal. 
 
1284 
 
 THE ORGANS OF DIGESTION 
 
 the fourth lumbar vertebra. It now takes a second bend, and passes across the 
 front of the vertebral cohimn from right to left and finally ascends on the left side 
 of the vertebi-ai column and aorta to the level of the upper border of the second 
 lumbar vertebra and there terminates in the jejunum. As it unites with the 
 jejunum it often turns abruptly forward, forming the duodeno-jejunal angle. Prof. 
 
 Omentum Minus 
 
 Lesser Sac 
 
 <» 
 
 of .Tl■*.'!'s^ 
 
 '':f^. 
 
 —Hepatic 
 
 Artery 
 
 Portal 
 Vein 
 
 •• '^ y ■' Greater \ ^^^ 
 
 Omentum 'l ' 
 Majlis Transverse Mesocolon 
 Fig. 888. — Diagram of cross-section of the first 
 part of the duodenum, to show its peritoneal 
 relations. 
 
 Fig. 889. — Diagram of cross-section of the second part 
 of the duodenum, to show its peritoneal relations. 
 (Gerrish.) 
 
 Birmingham points out that the incomplete ring formed by the duodenum does 
 not lie throughout in the same plane. " Its greater part is placed in a transverse 
 vertical plane; the middle portion bends strongly backward, around the right side 
 of the vena cava, and lies almost in a sagittal plane."^ From the above descriotion 
 
 eRY 
 
 AUSi-N"? 
 
 AORTA, VENA CAVA. 
 AND RIGHT CRUS 
 
 Fig. 890.— Diagram of the third part of the 
 duodenum, to show its peritoneal relations. 
 (Gerrish.) 
 
 Fig. 891. — Diagram of the fourth part of the duodenum, 
 to show its peritoneal relations. (Gerri.sh.) 
 
 it will be seen that the duodenum may be divided for purposes of description 
 into four portions — superior, descending, transverse and ascending. 
 
 The First or Superior Portion (pars superior) (Figs. 887, 892, and 894) is 
 very variable in length, but is usually estimated as being about two inches. 
 Beginning at the pylorus, it ends at the level of the neck of the gall-bladder. 
 
 1 Prof. Cunningham's Text-book of Anatomy. 
 
THE DUODENUM 1285 
 
 When the stomach is empty this portion of the duodenum is horizontal and 
 transverse; when the stomach is distended it extends from before backward. It 
 is the most movable of the four portions. It is almost completely covered by peri- 
 toneum derived from the two layers of the lesser omentum. A small part of its 
 posterior surface is not completely covered by peritoneum (Fig. 888). The first 
 inch of the superior portion of the duodenum is completely covered by perito- 
 neum ; the lesser omentum is attached above and the greater omentum below (Fig. 
 888). The other portion has only its anterior wall covered by peritoneum. The 
 'posterior and lateral surfaces are uncovered by peritoneum and are near the neck 
 of the gall-bladder and the inferior vena cava. The first portion of the duo- 
 denum is in such close relation with the gall-bladder that it is usually found to 
 be stained by bile after death, especially on its anterior surface. It is in relation 
 above and in front with the quadrate lobe of the liver, lying in a slight con- 
 cavity, the impressio duodenalis. It is also in relation above in part with the 
 gall-bladder; behind with the gastro-duodenal artery, the common bile-duct, and 
 the vena porta; and below with the head of the pancreas. The superior portion 
 of the duodenum crosses the transverse fissure of the liver, and by means of 
 the superior flexure of the duodenum (flexura duodeni superior) passes into the 
 second or descending portion beneath the caudate lobe. 
 
 The Second or Descending Portion {j)ars descendens) (Figs. 887, 892, and 894) 
 is between three and four inches in length, and extends from the neck of the gall- 
 bladder on a level with the first lumbar vertebra along the right side of the verte- 
 bral column as low as the body of the fourth lumbar vertebra. It is crossed in 
 its middle third by the transverse colon, the posterior surface of which is uncovered 
 by peritoneum and is connected to the duodenum by a small quantity of connective 
 tissue. The portions of the descending part of the duodenum above and below 
 this interspace are named the supracolic and infracolic portions, and are covered 
 in front by peritoneum (Fig. 889). The right side of the supracolic portion is 
 covered by peritoneum derived from the anterior surface of the right kidney, the 
 left side of the same portion being covered by the peritoneum forming the lesser 
 sac. The infracolic part is covered by the right leaf of the mesentery. Pos- 
 teriorly the descending portion of the duodenum is uncovered by peritoneum. 
 The descending portion of the duodenum is in relation, in front, with the trans- 
 verse colon, and above this with the right lobe of the liver, where it lies in the 
 impressio duodenalis for the second part of the duodenum; behind with the front of 
 the right kidney, to which it is connected by loose areolar tissue, the renal vessels 
 and the vena cava inferior; at its inner side is the head of the pancreas, and the 
 ductus communis choledochus; to its outer side is the hepatic flexure of the colon. 
 The common bile-duct passes downward behind the first portion of the duodenum, 
 descends to the inner side of the second portion, is joined by the pancreatic duct, 
 and the two ducts perforate the inner side of this portion of the intestine obliquely, 
 and empty into the duodenum by a common opening or by two openings at the 
 summit of a papilla, some three or four inches below the pylorus. The relations 
 of the second part of the duodenum to the right kidney present considerable 
 variations. The descending portion passes into the transverse portion by means 
 of the flexura duodeni inferior. 
 
 The Third, Pre-aortic, Horizontal or Transverse Portion {pars horizontalis 
 inferior) (Figs. 887, 892, and 894) varies much in length; when the duodenum 
 assumes the ordinary horseshoe form, it measures from two to three inches; but 
 when it presents the rarer V-shaped form, it is practically wanting or very much 
 reduced in length. The transverse portion is described as the horizontal part of 
 the ascending or last portion by those author ; who divide the duodenum into three 
 parts instead of four. It commences at the right side of the fourth lumbar vertebra 
 and passes from right to left, with a slight inclination upward, in front of the great 
 
1286 
 
 THE ORGANS OF DIGESTION 
 
 vessels and crura of the Diaphragm, and ends in the fourth portion in front of or 
 just to the left of the abdominal aorta. It is crossed by the superior mesenteric 
 vessels and mesentery. The 'posterior surface rests upon the aorta, the vena cava 
 inferior, and the crura of the Diaphragm. By its upper surface this portion of 
 the duodenum is in relation with the head of the pancreas. The front of the 
 third portion of the duodenum is covered by peritoneum except where the mesen- 
 teric vessels and root of the mesentery cross it (Fig. 890). The left side of the 
 termination of the ascending portion is also covered by peritoneum, and in this 
 region the duodenal fossae are found (p. 1260). 
 
 The Fourth or Ascending Portion of the Duodenum (pars ascendens) (Figs. 
 887, 892, and 894) is about two inches long. It ascends on the left side of the 
 vertebral column and aorta, as far as the level of the upper border of the second 
 lumbar vertebra, where it turns abruptly to the right and forward to become the 
 jejunum, forming the duodeno-jejunal angle or flexure (flexura duodenojejunalis) 
 
 CELLULAR MEMBRANE 
 
 CONNECTING THE PARTS 
 
 OFTHE DUODENAL RING 
 
 BEHIND THE PANCREAS 
 
 DIAPHRAGM 
 
 CCELIAC AXIS 
 
 GANGLION OF 
 CCELIAC PLEXUS 
 SUPERIOR MESEN- 
 TERIC ARTERY 
 
 SUSPENSORY 
 MUSCLE OF 
 DUODENUM 
 
 Fig. 892. — Suspensory muscle of the duodenum or muscle of Treitz. (Poirier and Charpy.) 
 
 (Fig. 892). It is covered entirely in front and partly at the sides by peritoneum, 
 derived from the left portion of the mesentery (Fig. 891). The superior mesen- 
 teric artery and vein are in front of it. It touches the left kidney, slightly over- 
 lapping its inner margin, and rests upon the left crus of the Diaphragm. 
 
 The first part of the duodenum, as stated above, is somewhat movable, but the 
 rest is practically fixed and is bound down to neighboring viscera and the posterior 
 abdominal wall by the peritoneum. In addition to this, the fourth part of the 
 duodenum and the duodeno-jejunal flexure is further bound down and fixed by a 
 structure called the Suspensory muscle of the duodenum or the suspensory ligament of 
 Treitz (to. suspensorius duodeni) (Fig. 892). This structure commences in the con- 
 nective tissue around the coeliac axis and left crus of the Diaphragm, and passes 
 downward to be inserted into the superior border of the duodeno-jejunal curve and 
 a part of the ascending duodenum, and from this it is continued into the mesentery. 
 It possesses, according to Treitz, some few plain muscular fibres mixed with the 
 
THE DUODENUM 
 
 1287 
 
 fibrous tissue, of which it is principally made up. It is of little importance as a 
 muscle, but acts as a suspensory ligament. 
 
 VALVU 
 CONNIVEN 
 
 CARUNCULA 
 MAJOR 
 
 SOUND IN DUG 
 TUS CHOLEDOCHUS 
 
 CARUNCULA MINOR 
 OF SANTORINI 
 
 SOUND IN 
 DUCTUS CHOLEDOCHUS 
 
 lio. 893. — The interior of the duodenum. (Spalteholz.) 
 
 SOUND IN 
 ACCESSORY 
 PANCREATIC 
 DUCT OF 
 SANTORINI 
 
 LONGITUDINAL 
 FOLD 
 
 VALVULAE 
 CONNIVENTE8 
 
 Portal vein 
 Hepatic duct 
 Cystic duct 
 
 Hepatic artery — -V^ - 
 Hight svprnrenal, _^m 
 capsule 
 
 Pyloric orifice- 
 Right gastro-epipluic 
 artery 
 
 Superior mesenteric 
 
 vein fM 
 
 Spermatic itb&ds \ Spermatic vessels 
 
 Inferior mesenteric artery 
 
 Fig. 894. — The duodenum, its four parts marked n, b, c, d. The liver is lifted up ; the greater art of the 
 stomach is removed, broken lines indicating its former position. (Testut.) 
 
128S 
 
 THE ORGANS OF DIGESTION 
 
 Interior of the Duodenum (Fig. 893). — In the beginning of the duodenum valvulae 
 conniventes are absent. They begin to appear in the lower half of the first portion, 
 being at first trivial elevations irregularly placed. They become higher, regular, 
 and more numerous lower down, and near the termination of the duodenum are 
 strongly marked and closely placed transverse or spiral folds (Fig. 893 and 
 p. 1291). In the descending portion (Fig. 893) to the side and rear is a longi- 
 tudinal fold {flica longitudinalis duodeni), which is formed by the projection of 
 the bile-duct and pancreatic duct beneath the mucous membrane. 
 
 The caxuncula major of Santorini or the bile papilla is a projection or tit in the 
 lower part of the longitudinal fold. At the summit of this papilla are seen two 
 openings, if the bile-duct and pancreatic duct have not united, or one common 
 opening for both of them, if they have united. One inch above and half an inch 
 or more in front of the bile papilla is a much smaller papilla, the caruncula minor 
 of Santorini (papilla duodeni [Santorini^), on the summit of which the accessory 
 pancreatic duct of Santorini opens. 
 
 Structure of the Duodenum. — The peritoneal coat {tunica serosa) has been de- 
 scribed. The muscular coat (tunica muscidaris) is practically identical with the 
 muscular coat of the balance of the intestine. The bile-duct and pancreatic duct 
 
 FIRST 
 
 GASTRO- 
 
 GASTRO- 
 
 
 INFERIOR 
 
 PART OF 
 
 DUOOENAL 
 
 DUODENAL 
 
 CCELIAC 
 
 PANCREATICO 
 
 DUODENUM 
 
 \ 
 
 ARTERY 
 
 \ ^ 
 
 VEI^ 
 
 AXIS 
 
 DUODENAL 
 VEIN 
 
 PANCREATICO- 
 DUODENAL 
 SUPERIOR 
 ARTERY 
 
 DUCTUS 
 CHOLEDOCHUS 
 
 ANASTOMOSIS OF THE 
 TWO PANCREATICO- 
 DUODENAL ARTERIES 
 
 Fig. 835. — The blood-vessels of the duodenum. (Poirier and Charpy.) 
 
 pass through it. The submucous coat {tela suhmucosa) contains lymph-nodes and 
 glands of Brunner (glandulae duodenales). These glands are particularly plenti- 
 ful in the first half of the duodenum (p. 1295). The mucous membrane is 
 thicker in the duodenum than in the rest of the small intestine, is covered with 
 villi, and from the lower half of the first portion down is formed into circular 
 folds or valvulae conniventes. In the descending part it exhibits the previously 
 described longitudinal fold. 
 
 Vessels and Nerves. — The arteries (Fig. 895) supplving the duodenum are the 
 pyloric and pancreatico -duodenal branches of the hepatic, and the inferior pancreatico- 
 duodenal branch of the superior mesenteric. The veins (Fig. 895) correspond to 
 the arteries. The superior duodenal vein passes into the superior mesenteric, and 
 the inferior duodenal vein passes into the portal. The lymphatics pass along with 
 the pancreatico-duodenal arteries, glands being present here and there, and 
 terminate in the glands about the coehac axis. The duodenal fossae are described 
 on p. 1260. The nerves are derived from the solar plexus. 
 
THE JEJUNUM AND ILEUM 1289 
 
 The Jejunum and Ileum (Figs. 862, 864, 865, 867, 892). 
 
 The remainder of the small intestine from the termination of the duodenum 
 comprises the jejunum and ileum; the former name being given to the upper two- 
 fifths and the latter to the remaining three-fifths. Spalteholz and others call all of 
 the small intestine below the duodenum the intestinum tenue mesenteriale. There 
 is no morphological line of distinction between the jejunum and ileum, and the 
 division is arbitrary; but at the same time it must be noted that the character of 
 the intestine gradually undergoes a change from the commencement of the jeju- 
 num to the termination of the ileum, so that a portion of the bowel taken from 
 these two situations would present characteristic and marked differences. These 
 are briefly as follows: 
 
 Differences between the Jejunum and Ileum. — If the jejunum high up is con- 
 trasted with the ileum low down, it is noted that the former is thicker, of greater 
 diameter, contains more blood-vessels, and hence is more distinctly red, has well- 
 marked valvulae conniventes, but a few small-sized Peyer's patches, and the villi 
 are short and broad. In the ileum large Peyer's patches are present in numbers, 
 and the villi are thin (Prof. Birmingham). 
 
 The Jejunum {intestinum jejunum). — The jejunum, which derives its name 
 from the Latin word jejunus (empty), because it was formerly supposed to be 
 empty after death, is wider, its diameter being about one inch and a half, and is 
 thicker, more vascular, and of a deeper color than the ileum, so that a given length 
 weighs more. Its valvulae conniventes are large and thickly set and its villi are 
 larger than in the ileum. The glands of Peyer are almost absent in the upper part 
 of the jejunum, and in the lower part are less frequently found than in the ileum, 
 and are smaller and tend to assume a circular form. Brunner's glands are only 
 found in the upper part of the jejunum. By grasping the jejunum between the 
 finger and thumb the valvulae conniventes can be felt through the walls of the 
 gut; these being absent in the lower part of the ileum, it is possible in this way 
 to distinguish the upper from the lower part of the small intestine. 
 
 The Ileum {intestinum ileum). — The ileum (so called from the Greek w^ord 
 ttktiv, to twist, on account of its numerous coils and convolutions) is placed 
 below and to the right of the jejunum. It is narrower, its diameter being one inch 
 and a quarter, and its coats are thinner and less vascular than those of the jejunum. 
 It possesses but few valvulae conniventes, and they are small and disappear entirely 
 toward its lower end, but Peyer's patches are larger and more numerous. The 
 jejunum for the most part occupies the umbilical and left iliac regions, while the 
 ileum occupies chiefly the umbilical, hypogastric, right iliac, and pelvic regions, 
 and terminates in the right iliac fossa by opening into the inner side of the com- 
 mencement of the large intestine. The upper portion of the jejunum passes to 
 the left of the duodeno-jejunal flexure, and is in relation with the under surface 
 of the pancreas and the transverse mesocolon. The lower portion of the ileum is 
 in the pelvis and rises from above the brim, passing upward, backward, and to the 
 right to reach the ileo-caecal opening. Treves points out that another portion of 
 the small intestine may be in the pelvis, viz., the portion with the longest mesentery. 
 This is a portion somewhere between a point six feet from the duodenum and a 
 point eleven feet from the duodenum. The jejunum and ileum are attached to the 
 posterior abdominal wall by an extensive fold of peritoneum, the mesentery (p. 1257), 
 which allows the freest motion, so that each coil can accommodate itself to changes 
 in form and position. The mesentery is fan-shaped; its posterior border, about 
 six inches in length, is attached to the abdominal wall from the left side of the 
 second lumbar vertebra to the right iliac fossa (Fig. 862). Its length is about eight 
 inches from its commencement to its termination at the intestine, and it is rather 
 longer about its centre than at either end of the bowel. According to Lockwood, 
 
1290 THE 0RGAN8 OF DIGESTION 
 
 it tends to increase in length as age advances. Between the two layers of which 
 it is composed are contained blood-vessels, nerves, lacteals, and lymphatic glands, 
 together with a variable amount of fat. 
 
 Meckel's Diverticulum {diverticulum ilei). — Occasionally there may be found 
 connected with the lower part of the ileum, on an average about three feet from 
 its termination, a blind diverticulum or tube, varying in length, but averaging 
 about two inches, and being of about the same diameter as the piece of intestine of 
 which it is a part. Sometimes only a portion of the proximal end is open and 
 the balance of the structure is obliterated and shrunk to a fibrous cord. In other 
 cases the diverticulum is actually of greater diameter than the intestine. It 
 usually is at a right angle to the intestine, but may take almost any direction. 
 In most cases it has a mesentery. It is attached to and communicates with the 
 lumen of the bowel by one extremity, and by the other is unattached or may be 
 connected with the abdominal wall or with some other portion of the intestine 
 by a fibrous band. This is Meckel's diverticulum, and represents the remains of 
 the vitelline or omphalo-mesenteric duct, the duct of communication between the 
 umbilical vesicle and the alimentary canal in early foetal life. 
 
 Structure of the Small Intestine, including the Duodenum. — The wall of 
 the small intestine is composed of four coats — serous, muscular, axeolar or sub- 
 mucous, and mucous. 
 
 The Serous Coat {tunica serosa). — The relation of the peritoneum to the duod- 
 enum has been described. The remaining portion of the small intestine is sur- 
 rounded by the peritoneum, excepting along its attached or mesenteric border; 
 here a space is left for the vessels and nerves to pass to the gut. 
 
 The Muscular Coat {tunica muscularis). — The muscular coat consists of two 
 layers of fibres, an external or longitudinal layer and an internal or circular 
 lajer. 
 
 The Longitudinal Fibres {stratum longitudinale) are thinly scattered over the 
 surface of the intestine, and are more distinct along its free border. 
 
 The Circular Fibres {stratum circidare) form a thick, uniform layer; they sur- 
 round the cylinder of the intestine in the greater part of its circumference, and are 
 composed of plain muscle-cells of considerable length. The muscular coat is 
 thicker at the upper than at the lower part of the small intestine. 
 
 The Areolar or Submucous Coat {tela suhmucosa). — The areolar or submucous 
 coat connects together the mucous and muscular layers. It consists of loose, 
 filamentous areolar tissue, which forms a bed for the subdivision of the nutrient 
 vessels, previous to their distribution to the mucous surface. 
 
 The submucous coat contains lymph-nodules {noduli lymphatici). Each nodule 
 is pyramidal or pear-shaped, and the apex lies in the mucous membrane and forms 
 a rounded elevation. These rounded elevations mark the solitary glands and 
 Peyer's patches (Figs. 896, 898, and 905), and in nowise resemble villi. In the 
 duodenum the submucous tissue contains the duodenal glands. The submucous 
 tissue is prolonged into the valvulae conniventes. It contains blood-vessels, Meiss- 
 ner's plexus of nerves, and lymph-vessels. 
 
 The Mucous Membrane {tunica mucosa). — The mucous membrane is thick and 
 highly vascular at the upper part of the small intestine, but somewhat paler and 
 thinner below. It consists of the following; structures: next the areolar or sub- 
 mucous coat is a layer of unstriped muscular fibres, the muscularis mucosae ; internal 
 to this is a quantity of retiform tissue, enclosing in its meshes lymph-corpuscles, 
 and in which the blood-vessels and nerves ramify. Lastly, a basement-membrane, 
 supporting a single layer of epithelial cells, which throughout the intestines are 
 columnar in character. They are granular in appearance, and each possesses a 
 clear, oval nucleus. At their superficial or unattached end they present a distinct 
 layer of highly refracting material, marked by vertical striae, which were formerly 
 
THE JEJUNUM AND ILEUM 
 
 1291 
 
 believed to be minute channels by which the chyle was taken up into the interior 
 of the cell, and by them transferred to the lacteal vessels of the mucous membrane. 
 
 MOUTHS OF GLANDS SOLITARY GLAND 
 
 OF LIEBERKUHN 
 
 Fig. 896. — Free surface of the mucous membrane of the small intestine, showing villi, solitarj' glands, 
 and openings of the intestinal glands. Semidiagrammatic. (Testut.) 
 
 The mucous membrane presents for examination the following structures con- 
 tained within it or belonging to it: 
 
 Valvulae conniventes. 
 
 Villi. 
 
 Simple follicles. 
 
 Duodenal glands. 
 
 T I , • J 1 f Solitary glands. 
 Lymphatic nodules i „ / • , i i 
 
 '' ^ C i eyer s or agmmate glands. 
 
 The Valvulae Conniventes or the Valves of Kerkring {'plicae circulares [Kerkringi]) 
 (Fig. 897) are large folds or valvular flaps projecting into the lumen of the bowel. 
 They are composed of reduplications or folds of the mucous membrane, the two 
 layers of the fold being bound together by submucous tissue; they contain no 
 muscular fibres, and, unlike the folds in 
 the stomach, they are permanent, and 
 are not obliterated when the intestine is 
 distended. The majority extend trans- 
 versely across the cylinder of the intestine 
 for about one-half or two-thirds of its 
 circumference, but some form complete 
 circles, and others have a spiral direc- 
 tion; the latter usually extend a little 
 more than once around the bowel, but 
 occasionally two or three times. The 
 spiral arrangement is the characteristic 
 one of the shark family of fishes. The 
 larger folds are about one-third of an 
 inch in depth at their broadest part; but 
 the greater number are of smaller size. 
 The larger and smaller folds alternate 
 with each other. They are not found at the commencement of the duodenum, 
 but begin to appear about one or two inches beyond the pylorus. In the lower 
 part of the descending portion, below the point where the bile and pancreatic 
 ducts enter the intestine, they are very large and closely approximated. In 
 the transverse portion of the duodenum and upper half of the jejunum they 
 
 Fig. 897. — Valvulae conniventes in the upper part 
 of the small intestine. (Poirier and Charpy.) 
 
1292 
 
 THE ORGANS OF DIGESTION 
 
 are large and numerous; and from this point, down to the middle of the ileum, 
 they diminish considerably in size. In the lower part of the ileum they almost 
 entirely disappear; hence the comparative thinness of this portion of the intes- 
 tine as compared with the duodenum and jejunum. The valvulae conniventes 
 retard the passage of the food along the intestine, and afford a more extensive 
 surface for absorption. 
 
 The Vim {villi intestinales) (Figs. 896, 898, 899, 900, and 905) are minute, highly 
 vascular processes, never larger than one millimetre, projecting from the mucous 
 membrane of the small intestine throughout its whole extent, and giving to its 
 surface a velvety appearance. They spring from the valvulae conniventes and also 
 from the spaces between them. In shape, according to Rauber, they are short 
 and leaf-shaped in the duodenum, tongue-shaped in the jejunum, and filiform 
 
 MUCOUS CO/^T 
 
 PLANE OF MU- 
 COUS SURFACE 
 
 Fig. 898. — Mucosa of small intestine in ideal vertical cross-section. (Testut, after Heitzmann.) 
 
 in the ileum. They are largest and most numerous in the duodenum and 
 jejunum, and become fewer and smaller in the ileum. Krause estimates their 
 number in the upper part of the small intestine at from fifty to ninety in a square 
 line; and in the lower part from forty to seventy, the total number for the whole 
 length of the intestine being about four millions. 
 
 Structure of the Villi (Figs. 899 and 900). — The structure of the villi has 
 been studied by many eminent anatomists. We shall here follow the description 
 of Watney,^ whose researches have a most important bearing on the physiology of 
 that which is the peculiar function of this part of the intestine, the absorption of fat. 
 
 The essential parts of a villus are— the lacteal vessel, the blood-vessels, the 
 epithelium, the basement-membrane and muscular tissue of the mucosa, these 
 structures being supported and held together by retiform lymphoid tissue. 
 
 Phil. Trans., vol. clxv. part ii. 
 
THE JEJUNUM AND ILEUM 
 
 1293 
 
 Fig. 899. — Diagrammatic section of a villus, ep. Epithelium only partially shaded in. I. Central chyle- 
 vessel ; the cells forming the vessel have been less shaded to distinguish them from the cells of the parenchyma 
 of the villus, m. Muscle-fibres running up by the side of the chyle-ves.sel. It will be noticed that each muscle- 
 fibre is surrounded by the reticulum, and by this reticulum the muscles are attached to the cells forming the 
 membrana propria, as at e', or to the reticulum of the villus. Ic. Lymph-corpuscles, marked by a spherical 
 nucleus and a clear zone of protoplasm. /'. Upper limit of the chyle-vessel, e, e, e'. Cells forming the mem- 
 brana propria. It will be seen that there is hardly any difference between the cells of the parenchyma, the endo- 
 thelium of the upper part of the chyle-vessel, and the cells of the membrana propria. V. Blood-vessels, z. Dark 
 line at base of the epithelium formed by the reticulum. It will be seen that the reticulum penetrates between 
 all the other elements of the villus. The reticulum contains thickenings or " nodal points." The diagram shows 
 that the cells of the upiser part of the villus are larger and contain a larger zone of protoplasm than those of the 
 lower part. The cells of the upper part of the chyle-vessel differ somewhat from those of the lower part in that 
 they more nearly resemble the cells of the parenchyma. (Watney.) 
 
 Lymph trunk 
 
 Lymph trunk. 
 
 - - Capillaries. 
 
 Small artery. ' Lymphatic plexus. 
 
 Fig. 900.— Villi of small intestine. (Cadiat.) 
 
1294 
 
 THE ORGANS OF DIGESTION 
 
 These structures are arranged in the following manner: situated in the centre 
 of the villus is the lacteal, terminating near the summit in a blind extremity; 
 running along this vessel are unstriped muscular fibres; surrounding it is a plexus 
 of capillary vessels, the whole being enclosed by a basement-membrane, and cov- 
 ered by columnar epithelium. Those structures which are contained within the 
 basement-membrane — namely, the lacteal, the muscular tissue, and the blood- 
 vessels — are surrounded and enclosed by a delicate reticulum which forms the 
 matrix of the villus, and in the meshes of which are found large, flattened cells 
 with oval nuclei, and, in smaller numbers, lymph-corpuscles. These latter are 
 to be distinguished from the larger cells of the villus by their behavior with 
 reagents, by their size, and by the shape of the nucleus, which is spherical. 
 Transitional forms, however, of all kinds are met with between the lymph-cor- 
 puscles and the proper cells of the villus. Nerve-fibres are contained within the 
 villi; they form ramifications throughout the reticulum. 
 
 The lacteals are in some cases double, and in some animals multiple. Situated 
 in the axis of the villi, they commence by dilated caecal extremities near to, but 
 not quite at, the summit of the villus. The walls are composed of a single layer 
 of endothelial cells, the interstitial substance between the cells being continuous 
 with the reticulum of the matrix. 
 
 CALCIFORM 
 CELL 
 
 GLANDULAR 
 CELL 
 
 Fig. 901. — Section of a gland of Lieberkiihn in the mouse. 
 (Paneth.) 
 
 Fio. 902. — Transverse section of crypts of 
 Lieberkiihn. (Klein and Noble Smith.) 
 
 The muscular fibres are derived from the muscularis mucosae, and are arranged 
 in bundles around the lacteal vessel, extending from the base to the summit of the 
 villus, and giving off laterally individual muscle-cells, which are enclosed by the 
 reticulum, and by it are attached to the basement-membrane. 
 
 The blood-vessels form a plexus between the lacteal and the basement-mem- 
 brane, and are enclosed in the reticular tissue; in the interstices of the capillary 
 plexus, which they form, are contained the cells of the villus. 
 
 These structures are surrounded by the basement-membrane, which is made 
 up of a stratum of endothelial cells, and upon which is placed a layer of columnar 
 epithelium. The reticulum of the matrix is continuous through the basement- 
 membrane (that is, through the interstitial substance between the individual 
 endothelial cells) with the interstitial cement substance of the columnar epithelial 
 cells on the surface of the villus. Thus we are enabled to trace a direct continuity 
 between the interior of the lacteal and the surface of the villus by means of the 
 reticular tissue, and it is along this path that the chyle passes in the process of 
 absorption by the villi; that is to say, it passes first of all into the columnar 
 
THE JEJUNUM AND ILEUM 
 
 1295 
 
 epithelial cells, and, escaping from them, is carried into the reticulum of the villus, 
 and thence into the central lacteal. 
 
 The Simple Follicles, Intestinal Glands, Crypts or Glands of Lieberkiihn (glandulae 
 intestinales [Lieberkuhrii]) (Figs. 901, 902, and 905) are found in considerable 
 numbers over every part of the mucous membrane of the small intestine. They 
 consist of minute tubular depressions of the mucous membrane, arranged per- 
 pendicularly to the surface, upon which they open by small circular apertures. 
 They may be seen with the aid of a lens, their orifices appearing as minute dots 
 scattered between the villi (Fig. 896). Their walls are thin, consisting of a base- 
 ment-membrane lined by columnar epithelium, and covered on their exterior by 
 capillary vessels. 
 
 The Duodenal or Brunner's Glands (glandulae duodenales [Brunneri]) are limited 
 to the duodenum and commencement of the jejunum. They are small, flattened, 
 granular bodies embedded in the submucous areolar tissue, and open upon the 
 surface of the mucous membrane by minute excretory ducts. They are most 
 numerous and largest near the pylorus. They are small, compound, acino-tubular 
 glands, and much resemble the small glands which are found in the mucous mem- 
 
 ,JU 
 
 Capillary network. 
 
 Fi». 903. — Transverse section through the equatorial plane 
 of three of Peyer's follicles from the rabbit. 
 
 Fig. 904. — Patch of Peyer's glands, 
 lower part of the ileum. 
 
 From the 
 
 brane of the mouth. They are believed by Watney to be direct continuations of 
 the pyloric glands of the stomach. They consist of a number of tubular alveoli, 
 lined by epithelium, and opening by a single duct on the inner surface of the 
 intestine. 
 
 The Lymph Nodules (noduli lymphatici) are small pyriform structures. The 
 bodies of the nodes are in the submucous coat; the apices are in the mucous mem- 
 brane, which is thrown by them into rounded elevations. They are divided into 
 solitary glands and Peyer's glands. 
 
 The solitary glands (noduli lymphatici solitarii) (Figs. 896 and 898) are found 
 scattered throughout the mucous membrane of the small intestine and the large 
 intestine. In the small intestine they are most numerous in the lower part of the 
 ileum, upon and between the valvulae conniventes. They are small, round, whitish 
 bodies, from one-twenty-fourth of an inch to one-quarter of an inch in diameter. 
 Their free surface is covered with villi, and each gland is surrounded by the 
 
1296 THE OBGANS OF DIGESTION 
 
 openings of the follicles of Lieberkiihn. They are now recognized as lymph- 
 nodules. They consist of a dense interlacing retiform tissue closely packed with 
 lymph-corpuscles and permeated with an abundant capillary network. The inter- 
 spaces of the retiform tissue are continuous with larger lymph-spaces at the base 
 of the gland, through which they communicate with the lacteal system. They 
 are situated partly in the submucous tissue, partly in the mucous membrane, 
 whence they form slight projections of its epithelial layer, after having pene- 
 trated the muscularis mucosae. The villi situated on them are generally absent 
 from the very summit (or "cupola," as Frey calls it) of the gland. 
 
 Peyer's glands, Peyer's patches, the agminated glands or the tonsillae intestinales 
 (noduli lymphatici aggregati [Peyeri]) (Figs. 903, 904, and 905) may be regarded as 
 aggregations of solitary glands, forming circular or oval patches from twenty-five 
 to forty in number, and varying in length from half an inch to four inches. They 
 are largest and most numerous in the ileum. In the lower part of the jejunum 
 they are small, of a circular form, and few in number. They are occasionally seen 
 in the duodenum. They are placed lengthwise in the intestine, and are situated 
 
 INTESTINAL VILLUS 
 
 GLAND OF LIEBERKUHN 
 
 CHYLI FERGUS 
 DUCT 
 
 SUMMIT OF 
 FOLLICLE 
 
 MIDDLE FOLLICULAR 
 ZONE 
 
 PERIFOLLICULAR 
 LYMPHATIC ZONE 
 
 INFERIOR LYM- 
 PHATIC PLEXUS 
 
 Fig. 905. — Vertical cell of a Peyer's patch in a man with the lymphatic vessels injected. (Frey.) 
 
 in the portion of the tube most distant from the attachment of the mesentery. 
 Each patch is formed of a group of the above-described solitary glands covered 
 with mucous membrane, and in almost every respect are similar in structure to 
 them. They do not, however, as a rule, possess villi on their free surface. Each 
 patch is surrounded by a circle of the crypts of Lieberkiihn. They are best marked 
 in the young subject, becoming indistinct in middle age, and sometimes altogether 
 disappearing in advanced life. They are largely supplied with blood-vessels, 
 which form an abundant plexus around each follicle and give off fine branches 
 which permeate the lymphoid tissue in the interior of the follicle. The lacteal 
 plexuses which are found throughout the small intestine are especially abundant 
 around these patches; here they form rich plexuses with sinuses around the glands 
 (Fig. 905), In typhoid fever there is ulceration of Peyer's patches. 
 
 Vessels and Nerves. — The arteries {vasa intestini tenuis) are branches of the 
 superior mesenteric (Fig. 420) and ascend within the mesentery, forming single, 
 double, or even tertiary loops (Figs. 869, 870, 871, 872, 873, 874, and 906). The 
 terminal branches reach the intestine, and each branch divides into two, one going 
 to each side of the intestine and passing transversely around it. At first they are 
 
THE JEJUNUM AND ILEUM 
 
 1297 
 
 directly beneath the peritoneum, but after a time they pass to the submucosa 
 and form a plexus, from which branches go to the mucous membrane. Some 
 of these enter the villi; others form plexuses about the glands of Lieberkiihn 
 (Birmingham). 
 
 Fig. 906. — A loop of small intestine, showing the mode of distribution of the arteries. (Testut.) 
 
 Dr. George H. Monks* points out that opposite the upper portion of the bowel 
 the mesenteric vessels form only primary loops; as we pass down secondary loops 
 appear, become larger and more and more numerous, and actually prominent 
 features about the fourth foot. As we descend the secondary 
 loops become larger and more numerous and the primary 
 become smaller. All the time the loops get nearer and 
 nearer to the bowel. Tertiary loops may appear. Opposite 
 the lower part of the ileum the loops cease to be character- 
 istic and they form a network. (Monks's views are fully 
 set forth on pp. 1266, 1267, and 1268.) In the upper part 
 of the gut the vasa recta are from 3 to 5 cm. long, when the 
 loop of small intestine to which they run is lifted up so as 
 to put them gently on the stretch. They are straight, large, 
 and regular, and rarely give off branches in the mesentery. 
 In the lower third they are very short, being generally less 
 than 1 cm. in length. Here they are less straight, smaller, 
 less regular, and have frequent branches in the mesentery. 
 
 The veins correspond to the arteries, and the venous 
 blood passes to the superior mesenteric vein, which, it will be 
 remembered, unites with the splenic vein to form the portal 
 vein. The mesenteric veins are devoid of valves. 
 
 The lacteals are lymphatics (Figs. 898, 899, 900, and 
 905) which arise in the villi. Lymphatics also begin in 
 sinuses at the base of the solitary glands and as lymph- 
 nodes in the submucous coat. Peyer's patches are aggre- 
 gations of lymph-nodes. There is an extensive lymphatic 
 
 1 • .1 I , ,1 • ,1 1,1" i"c vim oi I lie small in- 
 
 plexus m the submucous coat, another in the muscular coat, testineof arabbit. (Muiier.) 
 another under the peritoneum. The submucous plexus 
 
 is formed by lymphatics from the villi and mucous membrane. This plexus 
 is joined by lymphatics from the bases of the solitary glands, and the lymph 
 passes by vessels to larger vessels at the mesenteric border of the gut. The 
 muscular lymphatics are placed between the two muscular layers. They 
 
 I ' 'i<<7 . .N(>r\ (■ ciiilings 
 in the villi of the small in- 
 
 1 Annals of Surgery, May, 1903. 
 82 
 
1298 
 
 THE ORGANS OF DIGESTION 
 
 form a plexus and communicate freely with the lymphatics from the mucous 
 membrane, and empty themselves in the same manner into the commencement 
 
 Fig. 908. — Meissner's plexus. 
 
 Multipolar ganglion- cells. 
 
 Single ganglion-cell. 
 
 Fig. 909.— Meissner's plexus. (Klein and Noble Smith.) 
 
THE LARGE INTESTINE 
 
 1299 
 
 of the lacteal vessels at the attached border of the gut. The vessels from all 
 sources of lymphatic supply pass up between the two layers of the mesentery, 
 being connected with the mesenteric glands (Fig. 509) , and unite to form a trunk, 
 the intestinal Ijrmphatic trunk, which opens into the receptaculum chyli, or the 
 vessels unite to form several trunks, which open separately into the receptaculum 
 chyli. 
 
 The nerves of the small intestine (Figs. 907, 908, and 909) are derived from the 
 coeliac plexus about the superior mesenteric artery, which is one of the divisions 
 of the solar plexus. They pass along within the mesentery with the superior mesen- 
 teric artery and reach the intestine. They pass to the plexus of nerves and ganglia 
 situated between the circular and longitudinal muscular fibres (Auerbach's plexus), 
 from which the nervous branches are distributed to the muscular coats of the 
 intestine. From this plexus a secondary plexus is derived (Meissner's plexus). 
 It is formed by branches which have perforated the circular muscular fibres 
 (Fig. 909). This plexus lies between the muscular and mucous coats of the intes- 
 tine. It is -also gangliated, and from it the ultimate fibres pass to the muscularis 
 mucosae, to the villi, and to the mucous membrane. The nerves of the intestine 
 are non-medullated, and some of the fibres are derived from the pneumogastric. 
 
 THE LARGE INTESTINE (INTESTINUM CRASSUM) (Figs. 799, 861, 865, 910, 911). 
 
 The large intestine extends from the termination of the ileum to the anus. It 
 is about five feet or more in length, being one-fifth of the whole extent of the 
 
 SACCULATIONS 
 
 APPENDICES CPIPLOICAE 
 
 Fig. 910. — Large intestine. A piece of transverse colon from a child two years old. The three chief charac- 
 teristics of the large intestine — sacculation, taeniae and appendices epiploicae — are shown. (Cunningham.) 
 
 MUSCULAR BAND 
 
 intestinal canal. It is largest at its com- 
 mencement at the caecum, and gradually 
 diminishes as far as the rectum, where 
 there is a dilatation of considerable size 
 just above the anus. The diameter of the 
 distended caecum is usually about three 
 inches; the diameter of the descending 
 colon is about one and a half inches. 
 The large intestine differs from the small 
 intestine in its greater size, its more 
 fixed position, its sacculated form (Figs. 
 910 and 911), and in possessing certain ap- 
 pendagesto its external coat, the appendices 
 epiploicae (Fig. 910). The appendices 
 epiploicae are peritoneal pouches con- 
 taining fat, unless the subject is greatly 
 
 wasted; they protrude here and there from the peritoneal coat of the entire large 
 bowel, except the rectum, and are particularly frequent along the anterior longi- 
 
 MUSCULAR 
 BAND 
 
 MUSCULAR 
 BAND 
 
 Fig. 911. — Segment of large intestine, showing the 
 characteristic features of its structure. (Testut.) 
 
1300 
 
 THE ORGANS OF DIGESTION 
 
 tudinal band. Further, the longitudinal muscular fibres of the large intestine do 
 not form a continuous layer around the gut, but are arranged in three longitudinal 
 bands or taeniae {taeniae coli) (Fig. 91 1) . The large intestine, in its course, describes 
 an arch, which surrounds the convolutions of the small intestine. It commences 
 in the right inguinal region, in a dilated part, the caecum. It ascends through the 
 right lumbar and right hypochondriac regions to the under surface of the liver; 
 it here takes a bend to the left, the hepatic flexure, and passes transversely across 
 the abdomen on the confines of the epigastric and umbilical regions, to the left 
 hypochondriac region; it then bends again, the splenic flexure, and descends 
 through the left lumbar region to the left iliac fossa, where it becomes convoluted, 
 and forms the sigmoid flexure ; finally it enters the pelvis, and descends along its 
 posterior wall to the anus. The large intestine is divided into the caecum, colon, 
 and rectum. 
 
 The Caecum (Intestinum Caecum) (Figs. 912, 913). 
 
 The caecum, the commencement of the large intestine, is the large blind pouch, 
 or cul-de-sac, situated below the ileo-caecal valve. Its name is derived from 
 caecus, blind. Its blind end or fundus is directed downward, and its open end 
 
 upward, communicating directly with the 
 colon, of which this blind pouch appears to 
 be the beginning or head, and hence the old 
 name caput caecum coli was applied to it. 
 An incomplete groove marks the upper limit 
 of the caecum. This groove is at the level 
 of the opening of the ileum. When the 
 caecum is contracted it bends on this groove 
 as on a hinge and forms an angle with the 
 ascending colon. In the contracted caecum 
 sacculations are but slightly evident; in the 
 distended caecum they are definite. Its size 
 is variously estimated by different authors, 
 but on an average it may be said to be two 
 and a half inches in length and three in 
 breadth. In 435 careful autopsies, Byron 
 Robinson found the caecum and appendix 
 congenitally absent in one case.^ The same 
 author says that excessively large caeca are 
 found in a little less than one-third of all 
 autopsies. A large caecum may be four 
 inches in width, entirely surrounded by peri- 
 toneum and usually is excessively mobile. 
 Sometimes an excessively small caecum is 
 encountered. According to Byron Robinson, this results from diminution of the 
 blood-supply during the axial rotation and caecal descent of development. An 
 adult caecum may be only one inch in width and one-half an inch in length, and it 
 is usually devoid of mobility. It is situated in the right iliac fossa, above the outer 
 half of Poupart's ligament, usually rests on the Ilio-psoas muscle, the iliac fascia 
 intervening, and lies immediately behind the abdominal wall. The right side of 
 the caecum is in contact with the outer wall of the abdomen, and the outer aspect 
 of the anterior wall of the caecum is in contact with the anterior abdominal wall 
 (Spalteholz). When the caecum is full the small intestine lies in front of the left 
 
 Fig. 912. — The caecum and colon laid open 
 to show the ileo-caecal valve. 
 
 1 St. Louis Courier of Medicine, October-December, 1902. 
 
k 
 
 THE CAECUM 1301 
 
 side and lower portion of the anterior caecal wall. If the caecum is empty the 
 small intestine lies in front of its anterior wall, and the lower end is on a higher 
 level than when this portion of the gut is full. In 15 per cent, of cases the caecum 
 is covered by the omentum (Byron Robinson). Byron Robinson describes four 
 positions of the caecum: 1. On the Psoas muscle. 2. To the right of the Psoas 
 muscle. 3. In the pelvis. 4. The potential position, in which it lies free in the 
 abdominal cavity. It may be found in various positions in the abdomen, 
 because of elongation of the fixation apparatus. The commonest position is on the 
 Psoas muscle, and this position is even more common in men than in women. It 
 is twice as often in the pelvis in women as in men — 20 per cent, of cases in the 
 former; 10 per cent, in the latter. As a rule, it is entirely enveloped on all sides 
 by peritoneum, but in a certain number of cases (6 per cent., according to Berry) 
 the peritoneal covering is not complete, so that a small portion of the upper end 
 of the posterior surface is uncovered and connected to the iliac fascia by connec- 
 tive tissue. As a matter of fact, there is no real mesocaecum — meaning by the term 
 a peritoneal fold which holds the caecum to the dorsal wall of the abdomen — except 
 when there is failure in development. The normal caecum is completely invested 
 by peritoneum from the beginning. Originally the caecum receives its blood along 
 a single peritoneal fold, the ileo-caecal fold, which is a simple mesentery. As 
 development advances, this simple mesentery becomes a double fold and prac- 
 tically bloodless, and is replaced by two vascular folds, the meso appendix to 
 the left and the mesenterico-colicum to the right. The mobility of the caecum 
 varies. Very small caeca are fixed. In most cases the caecum lies quite free in the 
 abdominal cavity and enjoys a considerable amount of movement. Sometimes 
 it is excessively mobile, and in such cases is usually also of large size. Such 
 mobility is due to a stretched fixation apparatus. A very large and mobile 
 caecum may be made to come in contact with any abdominal viscus and may 
 enter any hernial sac on either side. As a rule, when the caecum is large and mobile, 
 it is found in the pelvis or in the middle of the abdomen (Byron Robinson). It 
 is to be remembered that a mobile caecum carrying with it the appendix may 
 pass to almost any region of the abdomen. Sometimes the caecum fails to descend 
 or only descends a part of the way during development, the axial rotation of the 
 intestinal tract having been arrested. In such a case it may terminate at the 
 level of the gall-bladder, and the ascending colon is absent. In 310 adult males 
 Byron Robinson found 8 per cent, with undescended caecum and appendix. 
 Non-descent is found in less than 4 per cent, of adult females. A partbj descended 
 caecum usually lies upon the right kidney. 
 
 The caecum varies in shape, but, according to Treves, in man it may be classified 
 under one of four types (Fig. 913). In early foetal life it is short, conical, and 
 broad at the base, with its apex turned upward and inward toward the ileo-caecal 
 junction. It then resembles the caecum of some of the monkey tribe, e. g., Man- 
 gabey monkey. As the foetus grows the caecum increases in length more than in 
 breadth, so that it forms a longer tube than in the primitive form and without the 
 broad base, but with the same inclination inward of the apex toward the ileo- 
 caecal junction. This form is seen in others of the monkey tribe, e. g., the spider 
 monkey. As development goes on, the lower part of the tube ceases to grow and 
 the upper part becomes greatly increased, so that at birth there is a narrow tube, 
 the vermiform appendix, hanging from a conical projection, the caecum. This is 
 the infantile form, and as it persists throughout life, in about 2 per cent, of 
 cases, it is regarded by Treves as the first of his four types of human caeca. The 
 caecum is conical and the appendix rises from its apex. The three longitudinal 
 bands start from the appendix and are equidistant from each other. In the second 
 type, the conical caecum has become quadrate by the growing out of a saccule on 
 either side of the anterior longitudinal band. These saccules are of equal size, 
 
1302 
 
 THE ORGANS OF DIGESTION 
 
 and the appendix arises from between them, instead of from the apex of a cone. 
 This type is found in about 3 per cent, of cases. The third type is the normal type 
 of man. Here the two saccules, which in the second type were uniform, have 
 grown at unequal rates: the right with greater rapidity than the left. In conse- 
 quence of this an apparently new apex has been formed by the growing downward 
 of the right saccule, and the original apex, with the appendix attached, is pushed 
 over to the left toward the ileo-caecal junction. The three longitudinal bands still 
 start from the base of the appendix, but they are now no longer equidistant from 
 each other, because the right saccule has grown between the anterior and postero- 
 external bands, pushing them over to the left. This type occurs in about 90 per 
 cent, of cases. The fourth type is merely an exaggerated condition of the third; 
 
 Fig. 913. — The four types of caecum. 
 
 the right saccule is still larger, and at the same time the left saccule has been 
 atrophied, so that the original apex of the caecum, with the appendix, is close to 
 the ileo-caecal junction, and the anterior band courses inward to the same situa- 
 tion. This type is present in about 4 per cent, of cases. 
 
 Supports of the Caecum. — According to Byron Robinson,^ the caecum is main- 
 tained in position by the mesocolon and a peritoneal fold, the right phrenico -colic 
 ligament, which arises from the hepato-duodenal and hepato-renal ligaments. It 
 receives support from the connective tissue about vessels and nerves, and 
 inconstantly from folds which fixes it in the iliac fossa and in the region of the 
 vena cava. 
 
 1 St. Louis Courier of Medicine, October- December, 1902. 
 
THE CAECUM 1303 
 
 The Interior of the Caecum. — In the interior of the caecum are seen depressions 
 which correspond to the surface haustra, and semilunar folds (plicae semilunares 
 coli) (Fig. 912), which correspond to the transverse surface constrictions. There 
 are three openings in the caecum: that into the colon; that into the ileum, which 
 is guarded by the ileo-caecal valve (p. 1308) ; and that into the appendix, which 
 may be guarded by the valve of Gerlach. 
 
 Pericaecal Folds and Fossae. — See p. 1262, and Figs. 866, 867, and 868. 
 
 The Vermiform Appendix {processus vermiformis) (Figs. 866, 867, 868, 913, 914, 
 915, 916, and 918) . — The vermiform appendix is found only in man, the higher 
 apes, and the wombat, although in certain rodents a somewhat similar arrangement 
 exists. In carnivorous animals the caecum is very slightly developed; in her- 
 bivorous animals (with a simple stomach) it is, as a rule, extremely large. It has 
 been suggested that the vermiform process in man is the degenerated remains of the 
 herbivorous caecum, which has been replaced by the carnivorous form.^ The 
 vermiform appendix is a long, narrow, worm-shaped, musculo-membranous tube, 
 which starts from what was originally the apex of the caecum. After development 
 has advanced the vermiform appendix comes off, as a rule, from the inner side of 
 the posterior wall of the caecum that is below and behind the termination of the 
 ileum. This origin usually corresponds to McBumey's point, which is in the 
 abdominal wall, midway between the umbilicus and the anterior superior iliac 
 spine and which is the usual seat of the greatest tenderness in appendicitis. The 
 origin of the appendix varies with the type of caecum present. These variations 
 are shown in Fig. 913. In the foetal or infantile type of appendix it arises from 
 the apex of the caecum; in the second type of caecum it arises between the two 
 caecal sacculi ; in the third type it arises between a large outer and a small inner sac- 
 culus; and on the posterior wall of the caecum, the excessive growth of the anterior 
 wall having caused the appendix to originate posteriorly; in the fourth type there is 
 no internal sacculus, and the appendix arises from the posterior caecal wall behind 
 the ileo-caecal junction (p. 1302). The movable portion of the appendix may be 
 met with in different situations. "It may pass upward and in front of the caecum 
 and colon, upward and behind the caecum, and even behind the colon between the 
 two layers of the mesocolon ; upward and to the inner side, or upward and to the outer 
 side of the caecum and colon. It may pass to the left under the ileum and mesentery, 
 upward and to the left or downward and to the left into the true pelvis. It may pass 
 directly downward under the caecum. It may pass to the right in front of or back 
 of the caecum. It may occupy any one of the caecal fossae (p. 1262) , but most often 
 enters the ileo-caecal fossa. In unusual cases the appendix is found in the inguinal 
 canal as a portion of or the sole contents of a hernia; adherent to the parietal peri- 
 toneum in front of or to the side of the caecum, or "behind the peritoneum, below 
 the caecum, adherent to the under surface of the caecum and in contact with its 
 muscular wall and covered by its peritoneal coat."^ When the caecum is mobile 
 the appendix may be found almost anywhere within the abdomen. When the 
 caecum is undescended the appendix, of course, shares in the failure to descend, 
 and may be below the gall-bladrler or in front of the right kidney, and may pass 
 in several directions: upward behind the caecum; to the left behind the ileum and 
 mesentery; or downward and inward into the true pelvis. It varies from one-half 
 an inch to nine inches in length, its average being about three inches. Its diameter 
 is from one-eighth inch to one-quarter inch. The operating surgeon may occa- 
 sionally fail to find an appendix buried in one of the caecal fossae, and may con- 
 clude that the diverticulum is absent. As a matter of fact, unless the colon is also 
 absent, it seems doubtful if the appendix is ever absent, except as a result of dis- 
 
 1 Cunningham's Text-book of Anatomy. 
 * Deaver's Surgical Anatomy. 
 
1304 THE ORGANS OF DIGESTION 
 
 ease. This view is maintained by Lockwood and RoUeston/ by Kelynack,^ and 
 others. It is asserted by some that the appendix is absent five times out of 10,000 
 autopsies. It is retained in position by a fold of peritoneum derived from the left 
 leaf of the mesentery, which forms a mesentery for it, and is called the meso- 
 appendix (p. 1260, and Figs. 866, 867, and 868). In color the healthy appendix is 
 yellowish-pink, is soft and smooth to the touch, and the "subperitoneal vessels 
 are barely visible."' The canal of the appendix is small and extends throughout 
 the whole length of the tube. The walls of the healthy diverticulum are thick, 
 and the diameter of the lumen is usually trivial as compared with the diameter of 
 the appendix itself. The lumen of the appendix communicates with the caecum 
 by an orifice which is placed Vjelow and behind the ileo-caecal opening (Fig. 919). 
 It is sometimes guarded above and to the left side by a semilunar fold of mucous 
 membrane, the valve of Gerlach (valvula processus vermiformis) . The valve is 
 inconstant, and is never perfect. It is stated that the appendix tends to undergo 
 obliteration as an involution change in a functionless organ. The lumen rarely 
 contains foreign bodies after death, but often contains fecal concretions. Certain 
 it is that in 25 per cent, of necropsies upon adults or elderly people the lumen 
 is found to be partially or completely occluded. 
 
 LEOCOLIC ARTERY 
 
 ANTERIOR ILEO- 
 CAECAL ARTERY 
 
 ANTERIOR CAECAL 
 ARTERY 
 
 APPENDICULAR 
 ARTERY 
 
 APPENDIX 
 VERMIFORMIS 
 
 Fig. 914. — Arteries of the caecum and of the appendix vermiformis and of the terminal portion of the ileum. 
 
 (Poirier and Charpy.) 
 
 Structure of the Appendix (Fig. 917). — The coats of the appendix correspond to 
 the coats of the bowel: serous, muscular (the outer layer of longitudinal, the inner 
 of circular fibres), submucous, and mucous. In the deepest portion of the mucous 
 coat, against the submucous coat, are the unstriated fibres constituting the mus- 
 cularis mucosae. The muscularis mucosae is often present in some regions and 
 absent in others. It may not be present at all. 
 
 The Outer or Serous Coat usually completely covers the appendix and has a 
 definite mesentery, the mesoappendix (p. 1260). Occasionally the base of the 
 appendix is not surrounded by peritoneum, but is extraperitoneal, lying in the 
 retroperitoneal tissue. The appendiculo -ovarian ligament of Clado is occasionally 
 present in females. It is a prolongation of the mesoappendix which passes into 
 the broad ligament, and is extremely thin, and its fine connective-tissue fibres 
 send prolongations into the longitudinal muscle-fibres of the appendix. Ix)ck- 
 wood points out that the subperitoneal tissue of the meso-appendix and ''the 
 blood-vessels, nerves, and lymphatics which it contains are very intimately con- 
 nected with the submucosa. This union takes place at certain large gaps in the 
 muscular coats. These gaps serve for the transmission of blood-vessels, nerves, 
 
 1 Journal of Anatomy and PhysioloKv, 1891. vol. xxvi. 
 
 " A Contribution to the Pathology of the Vermiform Appendix. 
 
 " Lockwood on Appendicitis. 
 
THE CAECUM 
 
 1305 
 
 and lymphatics from the mesoappendix to the mucous coat. They are situated 
 at the junction of the mesoappendix with the appendix."^ 
 
 The Longitudinal Muscular Layer is thin and irregularly distributed, and in certain 
 regions may be excessively thin or actually absent, and between the fibres are the 
 blood-vessels, nerves, and lymphatics passing from the subperitoneal tissue to the 
 mucous coat. 
 
 The Circular Fibres are much better developed than the longitudinal fibres, and, 
 according to Lockwood, the layer is 1 mm. thick. Ijarge gaps are found here and 
 there for the passage of vessels, lymphatics, and nerves to and from the meso- 
 appendix and the mucous membrane, and a few vessels pierce the fibres at 
 other points (Lockwood). 
 
 The Submucous Coat varies greatly in thickness. It contains blood-vessels, 
 nerves, and lymphatics, and some lymphoid follicles. 
 
 The Mucous Membrane (Fig. 915) is covered by columnar 
 epithelial cells and contains numerous solitary lymph- 
 follicles, some glands of Lieberkiihn, surrounded by 
 lymphoid tissue, blood-vessels, lymphatics, and nerves. 
 
 The muscularis mucosae may be absent, may be scanty 
 or may be distinct. The lymphoid follicles are visible to 
 the naked eye (Fig. 915). Some of them are in the sub- 
 mucosa, some of them chiefly in the mucosa, the bases of 
 the latter, however, being in the submucosa. Lockwood 
 estimates that an appendix three and a half inches in 
 length contains from 150 to 200 follicles. 
 
 Blood-vessels of the Caecum and Appendix (Figs. 914, 916, 
 932, and 933). — The ileo-colic artery in the ileo-colic angle 
 gives off the anterior and posterior ileo-caecal arteries. The 
 anterior ileo-caecal runs down over the front of the ileum 
 and supplies the ileum, and sends off a terminal branch, 
 the anterior caecal artery, which supplies the anterior surface 
 of the caecum and of a portion of the ascending colon, and 
 to the upper and lower margins of the ileo-caecal valve. It 
 sends no branch to the appendix. The arteries of the ap- 
 pendix come from the posterior ileo-caecal artery. This 
 vessel, after arising from the ileo-colic artery, passes back 
 
 of the termination of the ileum and gives branches to the face'of the~vermiform"appen- 
 lower end of the ileum back of a portion of the ascending ^^'^^ (B«°'*'»y ^^^ ^'^^^-^ 
 colon and to the lower margin of the ileo-caecal valve, 
 
 where they anastomose with the valvular branches from the anterior ileo-caecal 
 (Lockwood). From the posterior ileo-caecal comes the posterior caecal branch, 
 which passes over the posterior and inner portion of the caecum near the base 
 of the appendix and sends one or two branches to the appendix. The chief blood- 
 supply of the appendix is the appendicular artery, which comes off the beginning 
 of the posterior ileo-caecal or, occasionally, from the termination of the ileo-colic. 
 If there is a distinct mesoappendix the largest branch of the artery passes along 
 its free edge. If the mesoappendix is absent or rudimentary the artery usually 
 lies upon the appendix from base to tip beneath the peritoneum. 
 
 Lockwood points out that the appendicular artery as it enters the mesoappen- 
 dix divides into three branches. The largest branch runs along the free edge, 
 and from this the tip of the appendix obtains its blood-supply; "the other two 
 reach the appendix at intervals of half an inch."^ When the branches reach 
 the appendix they divide and pass around it in the subperitoneal coat and send 
 
 * Appendicitis, its Pathology and Surgery. By Charles Barrett Lockwood. 
 
 2 Ibid. 
 
1306 
 
 THE ORGANS OF DIGESTION 
 
 branches through the muscular gaps to enter and pass through the submucous 
 coat. 
 
 In females there is occasionally some additional blood-supply through a branch 
 of the ovarian artery in the appendiculo-ovarian ligament. 
 
 The veins of the appendix are numerous, thin walled, and large. Veins from 
 the submucous plexus pass through the muscular gaps and enter the subperi- 
 
 ILEOCOLIC ARTERY 
 AND VEIN 
 
 POSTERIOR 
 
 ILEOCAECAL 
 
 ARTERY 
 
 AND VEIN 
 
 ILEAC BRANCH 
 
 APPENDICULAR 
 
 ARTERY AND 
 
 VEIN 
 
 ASCENDINQ 
 COLON 
 
 Fig. 916. — Arteries and veins of the caecum and vermiform appendix seen from behind. (Poirier and Charpy.) 
 
 toneal plexus. Veins from the subperitoneal plexus pass into veins in the meso- 
 appendix which correspond to but do not really accompany the arteries (liOck- 
 wood). Most of the veins of the mesoappendix pass to the posterior ileo-caecal 
 vein, though some pass directly to the caecal vein. These veins are radicles of 
 the portal system. 
 
 EPITHELIUM 
 
 Fig. 917. — Transverse section of the vermiform appendix of man. (Kolliker.) 
 
 Lymphatic System of the Caecum and Appendix (Fig. 918). — Surrounding the base 
 of each lymph-foUicle in the submucous tissue of the appendix is a lymph-space, 
 which Lockwood calls the follicular or basilar lymph-sinus. This sinus communi- 
 cates with the lymphatics of the submucous coat, "which again communicate 
 freely through the hiatus muscularis with those of the peritoneum and of the 
 mesoappendix."^ The collecting trunks from the caecum and appendix follow the 
 
 ^ Appendicitis, its Patholoey and Surgery. By Charles Barrett Lockwood. 
 
THE CAECUM 
 
 1307 
 
 blood-vessels (Fig. 918). The anterior collecting trunks of the caecum pass 
 through several small glands in the anterior ileo-caecal fold, and terminate in 
 
 ILEOCAECAL 
 
 ANTERIOR 
 
 LYMPHATICS 
 
 OFCAECUM 
 
 GLAND OF 
 APPENDIX 
 
 Fig. 918. — Lymphatics of the caecum and appendix, anterior view. (Poirier and Charpy.) 
 
 glands along the ileo-colic artery (Fig. 918). The posterior collecting trunks 
 pass through some small glands and terminate in glands along the ileo-colic 
 artery. The appendicular collecting trunks enter the mesoappendix. There are 
 usually four of them, sometimes five. Some 
 of them traverse a gland constantly present 
 at the ileo-caecal angle (Clado). Another gland 
 is constant. It is situated beneath the ileo- 
 colic fossa (Lockwood and RoUeston). The 
 
 ORIFICE or\ 
 
 APPENDIX 
 
 Fig. 919. 
 
 -Ileo-caecal valve of the circular type. 
 (Poirier.) 
 
 Fig. 920. — Vertical section through the caecum 
 and ileo-caecal valve. (Gegenbauer.) 
 
 editor subscribes to Lockwood's statement that in appendicitis there is often a 
 chain of inflamed glands along the inner side of the ascending colon behind the 
 
1308 
 
 THE ORGANS OF DIGESTION 
 
 ascending mesocolon. Hence this is one road taken by the lymphatics of the 
 appendix. The others pass to the mesenteric glands. 
 
 The Ileo-caeeal Valve or the Valve of Bauhin (valvula coli) (Figs. 919, 920, 
 921, and 922). — The lower end of the ileum terminates by opening into the inner 
 and back part of the large intestine, at the point of junction of the caecum with the 
 • colon. The opening is guarded by a valve, consisting of two semilunar segments, 
 an upper or colic segment {labium superius) and a lower or caecal segment (labimn 
 inferius), which project into the lumen of the large intestine. The upper one, 
 nearly horizontal in direction, is attached by its convex border to the point of 
 junction of the ileum with the colon; the lower segment, which is more concave 
 and longer, is attached to the point of junction of the ileum with the caecum. 
 At each end of the aperture the two segments of the valve coalesce, and are con- 
 tinued as a narrow membranous ridge around the canal for a short distance. Each 
 ridge is known as the retinaculum or frenulum of the valve {frenulum valvulae coli). 
 The left or anterior end of the aperture is rounded ; the right or posterior is narrow 
 
 Fig. 921. — Caecum and vermiform appendix. 1, 
 ileum ; 2, orifice of valve ; 3, inferior segment ; 
 4, superior segment ; 5, long muscular fibres from 
 ileum ; 6, cul-de-sac of caecum ; 7, appendix ; 8, 
 posterior taenia ; 9, internal taenia ; 10, anterior 
 taenia; 11, sacculus. (Sappey.) 
 
 Fig. 922. — Ileo-caecal valve. 1, edge of caecum ; 2, 
 orifice of valve ; 3, inferior segment ; 4, superior seg- 
 ment ; 5 and 6, fraena ; 7, appendix ; 8, mouth ; 9, 
 semilunar fold ; 10, posterior taenia ; 11, 12, 12, ante- 
 rior taenia ; 13, internal taenia. (Sappey.) 
 
 and pointed. In the formation of the valve the termination of the small intestine 
 invaginates for a short distance into the lumen of the large intestine (Fig. 920), 
 the invaginated portion of the wall of the small intestine uniting with a corre- 
 sponding portion of the wall of the large intestine. 
 
 Each segment of the valve is formed by a reduplication of the mucous mem- 
 brane and of the circular muscular fibres of the intestine, the longitudinal fibres 
 and peritoneum being continued uninterruptedly across from one portion of the 
 intestine to the other. When the longitudinal fibres and peritoneum are divided 
 or removed, the ileum may be drawn outward, and all traces of the valve will 
 be lost, the ileum appearing to open into the large intestine by a funnel-shaped 
 orifice of large size. 
 
 The surface of each segment of the valve directed toward the ileum possesses 
 villi, and presents the characteristic structure of the mucous membrane of the 
 small intestine; while that turned toward the large intestine is destitute of villi, 
 and marked with the orifices of the numerous tubular glands peculiar to the 
 mucous membrane of the large intestine. These differences in structure continue 
 
THE COLON 1309 
 
 as far as the free margins of the valve. When the caecum is distended it is sup- 
 posed that the margins of the opening are approximated so as to prevent reflux 
 into the ileum. It is known, however, that a very large enema which distends 
 the caecum and colon may in part enter the ileum, being driven there by waves 
 of reversed peristalsis. The valve resists, but a certain amount of pressure over- 
 comes it. Some believe that the so-called ileo-caecal valve is not a valve, but a 
 distinct sphincter. This has been demonstrated to be true in cats and dogs, but 
 lacks demonstration in man (p. 1323). 
 
 The Colon. 
 
 The colon is divided into four parts — the ascending, transverse and descending 
 colon, and the sigmoid flexure. 
 
 The Ascending Colon {colon ascendens). — The ascending colon is smaller than 
 the caecum, with which it is continuous. It passes upward, from its commence- 
 ment at the frenula of the caecum, opposite the ileo-caecal valve, to the under sur- 
 face of the right lobe of the liver, on the right of the gall-bladder, where it is lodged 
 in a shallow depression on the liver, the impressio colica; here it bends abruptly 
 inward to the left, forming the hepatic flexure {flexura coli dextra). It is retained 
 in contact with the posterior wall of the abdomen by the peritoneum, which covers 
 its anterior surface and sides, its posterior surface being connected by loose areolar 
 tissue with the Quadratus lumborum and Transversalis muscles, and with the 
 front of the lower and outer part of the right kidney (Fig. 923). Sometimes the 
 peritoneum almost completely invests it, and forms a distinct but short meso- 
 colon* (p. 1259). It is in relation, in front, with the convolutions of the ileum and 
 the abdominal parietes. 
 
 The Transverse Colon (colon transversum) (Fig. 858). — The transverse colon, 
 the longest part of the large intestine, passes transversely from right to left across 
 the abdomen, opposite the confines of the epigastric and umbilical zones, into the 
 left hypochondriac region, where it curves downward beneath the lower end of 
 the spleen, forming the splenic flexure (flexura coli sinistra). In its course the 
 transverse colon describes an arch, the concavity of which is directed backward 
 toward the vertebral column and a little upward; hence the name transverse arch 
 of the colon. This is the most movable part of the colon, being almost completely 
 invested by peritoneum, and connected to the spine behind by a large and wide 
 duplicature of that membrane, the transverse mesocolon (Fig. 863). The trans- 
 verse colon is in relation, by its upper surface with the liver and gall-bladder, the 
 great curvature of the stomach, and the lower end of the spleen; by its under sur- 
 face, with the small intestines; by its anterior surface, with the anterior layers 
 of the great omentum and the abdominal parietes; its posterior surface on the 
 right side is in relation with the second portion of the duodenum, and on the left 
 side is in contact with some of the convolutions of the jejunum and ileum. 
 
 The Descending Colon (colon descendens). — The descending colon passes 
 downward through the left hypochondriac and lumbar regions along the outer 
 border of the left kidney. At the lower end of the kidney it turns inward toward 
 the outer border of the Psoas muscle, along which it descends to the crest of the 
 ilium, where it terminates in the sigmoid flexure. At its commencement it is con- 
 nected with the Diaphragm by a fold of peritoneum, the phreno-colic ligament 
 (see p. 1259). It is retained in position by the peritoneum, which covers its 
 
 ' Treves states that after a careful examination of one hundred subjects, he found that in fifty-two there wa» 
 neither an ascending nor a descending mesocolon. In twenty-two there was a descending mesocolon, but no 
 trace of a corresponding fold on the other side. In fourteen sub.iects there was a mesocolon to both the ascend- 
 ing and the descending segments of the bowel ; while in the remaining twelve there was an ascending mesocolon, 
 but no corresponding fold on the left side. It follows, therefore, that in performing lumbar colostomy a meso- 
 colon may be expected on the left side in 36 per cent, of all ca.ses, and on the right in 26 per cent. (The Anat- 
 omy of the Intestinal Canal and Peritoneum in Man, 1885, p. 55.) — Ed. of 15th English edition. 
 
1310 
 
 THE ORGANS OF DIGESTION 
 
 anterior surface and sides, its posterior surface being connected by areolar tissue 
 with the outer border of the left kidney, and the Quadratus lumborum and 
 
 Posterior 
 
 Middle lamella of 
 
 lamella of lumbai fascia 
 
 . , . lumbal / 
 
 Antenor f^^^^^ /_ 
 lamella of 
 lumbar fascia. 
 
 QUADRATUS LUMBORUM. 
 
 LATISSIMUS 
 DORSI. 
 
 Fig. 923. — Diagram of the relations of the large intestine and kidneys, from behind. 
 
 Transversalis muscles (Fig. 863). It is smaller in calibre and more deeply placed 
 than the ascending colon, and is more frequently covered with peritoneum on its 
 posterior surface than the ascending colon (Treves). 
 
THE COLON 
 
 1311 
 
 DESCENDING COLON 
 
 The Sigmoid Flexure, Pelvic Colon or Sigmoid Colon {colon sigmoideum) 
 (Figs, 924, 925, 926, and 927) is the narrowest part of the colon; it is situated in 
 the left iliac fossa, commencing from the termina- , , 
 
 tion of the descending colon, at the margin of the 
 crest of the ilium, and then forming a loop, which 
 varies in length and position, and which terminates 
 in the rectum at the level of the attachment of the 
 mesentery upon the front of the third sacral verte- 
 bra. It passes downward about two inches parallel 
 to the outer border of the Psoas muscle, then taking 
 a transverse direction enters the cavity of the pelvis, 
 crosses this cavity from left to right and a little 
 upward to the lower margin of the right iliac fossa; 
 "from this point it passes downward, backward, 
 and inward along the anterior surface of the sacrum 
 to its junction with the rectum."^ It is surrounded 
 with the peritoneum and is attached to the poste- ^'''semiiTagr^riTcl^^cSst^^^ 
 
 Fig. 925. — Sigmoid colon and rectum, front view. The broken lines indicate the situation of the concealed part 
 of the sigmoid colon. The small intestine is drawn away, and the anus is turned forward. (Testut.) 
 
 rior abdominal wall by the mesosigmoid, a continuation of the mesocolon, but 
 which greatly exceeds the latter in length, hence the sigmoid is the most mobile 
 
 ^ Tuttle, Diseases of the Anus, Rectum, and Pehdc Colon. 
 
1312 
 
 THE ORGANS OF DIGESTION 
 
 portion of the large intestine. Tuttle divides the sigmoid into four portions. The 
 first or vertical portion; the second or transverse portion; the third portion, which is a 
 loop and is concave upward if the sigmoid occupies the pelvis, and is concave down- 
 ward if it occupies the abdomen; the fourth portion, which is curved irregularly in 
 the hollow of the sacrum, and which joins the rectum as often from the right as 
 from the left. When the sigmoid is lifted up and to the right and the mesosigmoid 
 is put slightly upon the stretch, an opening is seen at the parietal border of the left 
 layer of the mesosigmoid. This opening leads into a cul-de-sac, the intersigmoid 
 fossa. When the sigmoid is empty most of it falls into the recto-vesical or recto- 
 vaginal space (Fig. 925). When distended it mounts up into the abdomen, reaching 
 to or even above the umbilicus. The sigmoid flexure is in relation in front with 
 the small intestine and abdominal parietes. The sigmoid mesocolon is attached 
 to a line running downward and inward from the crest of the ilium, across the 
 Psoas muscle (Fig. 863). 
 
 The Rectum (Intestinum Rectum) (Figs. 924, 925, 926, 927, 928, 929). 
 
 The rectum is the terminal part of the large intestine, and extends from the 
 termination of the sigmoid flexure to the level of the semilunar valves of Mor- 
 
 URETHRA 
 
 PROSTATE 
 
 GLAND 
 
 TRANSVERSE 
 
 PERrN>EI 
 
 MUSCLE 
 
 EXTERNAL 
 
 SPHINCTER 
 
 MUSCLE 
 
 Fig. 926. — Sagittal section in the median line of the pelvis. (Poirier and Charpy.) 
 
 gagni. The sigmoid flexure terminates at the level of the attachment of the 
 mesentery in front of the third sacral vertebra. This definition is practical and 
 useful. It was suggested by Sir Frederick Treves. " It gives to the organ 
 definite limits; it separates the mobile from the immobile portion of the gut; it 
 marks the line where the course of the blood -supply changes; it indicates the 
 
THE RECTUM 
 
 1313 
 
 point where the three longitudinal muscular bands of the colon spread out and 
 become more or less equally distributed around the gut; and, finally, it marks a 
 point at which there is always a decided narrowing in cahbre, indicating the 
 juncture of the rectum with the pelvic colon."^ The old division added to this 
 the so-called first part of the rectum, which we consider as part of the sigmoid colon. 
 The rectum is divided into two portions, a superior and an inferior. The supe- 
 rior or sacrococcygeal portion of the rectum (flexura sacralis) curves downward 
 with the concavity forward and upward in front of the sacrum and coccyx, and 
 is continued as far as the apex of the prostate gland, about an inch in front of 
 the tip of the coccyx. The inferior or prostatic portion (flexura perinealis) begins 
 at this point. The bowel is directed downward and backward, being convex in 
 front, and terminates at the beginning of the anus at the level of the semilunar 
 valves of Morgagni. The inferior or prostatic portion of the rectum is described 
 by Symington as the anal canal. 
 
 RECTAL FOLD 
 
 CUL-DE-SAC_^ 
 OF DOUGLAS W\ 
 
 RECTO- 
 VAGINAL 
 SEPTUM 
 
 ,/ VESICO-UTEHINE 
 CUL-DE-SAC 
 
 Fig. 927.— -Median sagittal section of tlie female pelvis. (Luschka.) 
 
 Curves of the Rectum. — It will be seen, therefore, that the rectum presents two 
 antero-posterior curves: the first, with its convexity backward, is due to the con- 
 formation of the sacro-coccygeal column, and represents the arc of a circle, the 
 centre of which is opposite the third sacral vertebra. The lower one has its 
 convexity forward, and is angular. Its centre corresponds to a line drawn 
 between the anterior parts of the ischial tuberosities. Two lateral curves are also 
 described: the one to the right, opposite the junction of the third and fourth sacral 
 vertebrae; the other to the left, opposite the sacro-coccygeal articulation. They 
 are of little importance. 
 
 The adult rectum as here described has a length of from four to six inches in men, 
 and from three and five-eighths to five and one-eighth inches in women. Accord- 
 ing to Tuttle the length of the rectum depends to some degree on the size of the 
 
 1 A Treatise on Diseases of the Anus, Rectum, and Pelvic Colon. By James P. Tuttle. 
 
 83 
 
1314 
 
 THE 0BGAN8 OF DIGESTION 
 
 Fig. 928. — Diagram of rectum, showing Hous- 
 ton's valves in the interior. (Cunningham.) 
 
 subject, and is somewhat greater in the old than in the young. The prostatic portion 
 is the narrowest portion of the rectum. The widest part of the rectum is the ampulla 
 recti just above the anal canal (Figs. 926 and 927). The prostatic portion has no 
 peritoneal investment whatever and includes the lower two inches of the superior 
 portion of the rectum. When the rectum is empty it is a mere slit, the anterior and 
 posterior walls being in contact. When distended it is "irregularly cylindrical" 
 (Tuttle). At and above the level of the third sacral vertebra the gut is entirely sur- 
 rounded by peritoneum, and there is a mesosigmoid. This is the mesorectum of 
 those who describe the lower pelvic colon as the first part of the rectum. At the level 
 
 of the third sacral vertebra the true rectum 
 begins, and the true rectum has no meso- 
 rectum. The rectum is covered in front and 
 laterally by peritoneum at its upper part ; 
 gradually the peritoneum leaves its sides, 
 and about an inch above the prostate is re- 
 flected from the anterior surface of the bowel 
 on to the posterior wall of the bladder in 
 the male, and the upper fifth of the posterior 
 wall of the vagina in the female, forming 
 the recto-vesical or recto-vaginal pouche {ex- 
 cavatio reciovesicalis and excavatio rectoute- 
 rina), as the case may be (Fig. 853). The 
 balance of the rectum has no peritoneal cov- 
 ering. The level at which the peritoneum 
 leaves the anterior wall of the rectum to be 
 reflected on to the viscus in front of it is of 
 considerable importance from a surgical 
 point of view, in con1i,ection with removal of the lower part of the rectum. It is 
 higher in the male than in the female. In the former the height of the recto- 
 vesical pouch is about three inches; that is to say, the height to which an ordinary 
 index finger can reach from the anus. In the female the height of the recto- 
 vaginal pouch is about two and a quarter inches from the anal orifice. 
 
 The upper or sacro-coccygeal portion of the rectum is in relation, in front, in 
 the male, with the recto-vesical pouch, the triangular portion of the base of the 
 bladder, the vesiculae seminales, and vasa deferentia, and more anteriorly with 
 the under surface of the prostate. In the female, with the posterior wall of the 
 vagina below, and the recto-vaginal pouch above, in which are some convolutions 
 of the small intestine (Fig. 927). To the sides below the peritoneal reflections, 
 the rectum is surrounded by cellular tissue in which on each side lie the lateral 
 sacral artery and the bifurcated hypogastric plexus. This portion of the rectum is 
 separated from the sacrum and coccyx by an interval, the retro-rectal space, which 
 is filled with cellular tissue. The superior portion of the distended rectum is in con- 
 tact posteriorly and on each side with the sacral plexus, ganglia of the sympathetic, 
 and the fascial origin of the pyramidalis muscle (Tuttle). The lower or prostatic 
 portion in men is in relation anteriorly with the prostate gland and the membranous 
 urethra; in women with the posterior wall of the vagina. The lower end of the 
 rectum takes a backward turn, and the uro-genital organs turn forward; the inter- 
 vening space is called the perineum. In the female, the fibro-fatty and muscular 
 tissue which occupies this space is called the perineal body. The prostatic portion 
 of the rectum is invested by the Internal sphincter, supported by the Levatores 
 ani muscles, and surrounded at its termination by the External sphincter; in the 
 empty condition it presents the appearance of a longitudinal slit. Posteriorly 
 the lower part of the rectum is in contact with cellular tissue, which separates it 
 from the coccygeal gland and the coccyx. 
 
THE RECTUM 
 
 1315 
 
 Supports of the Rectum. — The rectum as it has been described in these pages is a 
 fixed tube. The upper portion of the rectum is supported by "the inferior mesen- 
 teric arteries and the fibrous sheaths which surround them" (Tuttle); by the peri- 
 toneal folds which attach it to the sacrum ; and by the peritoneal folds which pass 
 in front to the bladder (plicae redovesicales) , or to the uterus (plicae rectouterinae) , 
 and laterally to the pelvis. The middle of the rectum receives some support 
 from the lateral sacral arteries and their fibrous sheaths. The lower portion of the 
 rectum is supported by the Levator ani, External sphincter, and Recto-coccygeus 
 muscles. 
 
 Blood-vessels and Lymphatics of Rectum. — See pp. 1320 and 1322. 
 
 Nerves of Rectum. — See p. 1322. 
 
 Structure of Rectum. — See p. 1316. 
 
 RECTAL VALVES 
 
 A B 
 
 Fig. 929. — The anal canal and lower part of the rectum in the foetus. A, aged four to five months ; B, six 
 months ; C, nine months. In each the anal canal is distinctly marked off from the rectum proper ; the columns 
 of Morgagni and the rectal valves are distinct. (Cunningham.) 
 
 The Common Anal Canal (pars analis recti) (Figs. 929 and 930). — The anal 
 canal is the third portion of the rectum of the older descriptions. It begins 
 where the true rectum ends. This canal is the portion of the intestinal tract which 
 
 LONGITUDINAL 
 
 FIBRES OF 
 
 RECTUM 
 
 PART OF 
 
 LEVATOR AN. 
 
 INTERNAL 
 
 SPHINCTER 
 
 ANAL CANAL 
 
 RUG>e OF 
 MUCOUS 
 MEMBRANE 
 
 COLUMNS OF 
 MORGAGNI 
 
 ANAL VALVES 
 
 Fig. 930 — The interior of the anal canal and lower part of the rectum, showing the columns of Morgagni and 
 the anal valves between their lower ends. The columns were more numerous in the specimen than usual. 
 (Cunningham.) 
 
 is below the distribution of genuine mucous membrane, and is just posterior to 
 the middle of a line drawn from one tuberosity to the other. It lies between the 
 true skin and the upper borders of the semilunar valves of Morgagni. When at 
 rest it is a mere slit placed antero-posteriorly. The external opening of the anal 
 canal is the anus. The skin about the anus is pigmented, is thrown into radi- 
 ating folds by the contraction of the External sphincter muscle, and contains 
 hairs, sebaceous glands, and sudoriparous glands (glandulae circumanales). 
 Ascending into the canal, it alters its character and becomes muco-outaneous, 
 
1316 THE ORGANS OF DIGESTION 
 
 and true mucous membrane appears at the rectum proper. Back of the anus is 
 a median cutaneous fold passing posterior to the coccyx and called the anal raphe. 
 In front of the anus is a median fold which, in the female, passes forward and 
 merges with the labia major and in the male continues into the raph^ of the 
 scrotum. This is called the perineal raph6. The length of the anal canal is three- 
 quarters to one inch. "Its circumference varies from 3 cm. (one and three- 
 sixteenths inches) in normal condition to 15 cm. (five and five-sixteenths inches) 
 in disease, following injury or vicious practices. The average anus will admit a 
 cylinder of 65 mm. in circumference without rupturing the mucous membrane."^ 
 Relations of the Anil Canal. — It is surrounded by the external and internal 
 sphincter muscles, and above by the Levatores ani. To each side is the ischio- 
 rectal fossa containing fat. Between the anal canal and the coccyx is a collec- 
 tion of muscular fibres and connective tissue, the ano-coccygeal body of Symington. 
 In front, in the male, is the bulb of the urethra and the base of the triangular 
 ligament ; in the female, is the perineal body, which separates the anus from 
 the vagina. There are three layers in the wall of the anal canal: 
 
 1. The muco-cutaneous layer, which contains glands, blood-vessels, and numer- 
 erous nerve-endings. The lower portion is covered with pavement-epithelium, 
 but gradually there is a transition, and at the beginning of the rectum proper the 
 epithelium is entirely columnar. The valves of Morgagni, the anal valves or the semi- 
 lunar valves (Figs. 930 and 931) are in the upper portion of the anal canal between 
 the lower ends of the columns of Morgagni (Figs. 930 and 931). Above the valves 
 the canal is lined by transitional mucous membrane, below them by modified skin. 
 
 The ano-rectal line is not straight, but is irregularly dentated by trivial eleva- 
 tions, each of which is papilliform at its summit. According to Tuttle, these 
 elevations number from five to eight. About one-fifth of an inch below the ano- 
 rectal line is the depression known as Hilton's white line (annulus haemorrhoidalis) 
 (Fig. 931). This line is somewhat indistinct to sight, but can always be felt with 
 the finger. It marks the junction of the External with the Internal sphincter. 
 Above Hilton's line are some mucous crypts and also dilatations produced by the 
 internal haemorrhoidal plexus of veins (Fig. 931). 
 
 2. The fibro-cellular layer is beneath the mucous membrane. Above Hilton's 
 line it is composed of cellular tissue; below it is a thin fascia-like layer which joins 
 the superficial fascia. 
 
 The anal canal is surrounded by longitudinal fibres from the rectum, fibres from 
 the licvator ani, the lower portion of the Internal sphincter, and particularly by 
 the External sphincter. 
 
 Blood-vessels, Lymphatics, and Nerves of Anus. — See pp. 1321 and 1322. 
 
 Structure of Large Intestine (including the Rectum and Anal Canal). — The 
 large intestine has four coats — serous, muscular, areolar or submucous and mucous. 
 
 The Serous Coat (tunica serosa). — The serous coat is derived from the peritoneum, 
 and invests the different portions of the large intestine to a variable extent. The 
 caecum is completely covered by the serous membrane, except in a small percent- 
 age of cases (5 or 6 per cent.), where a small portion of the upper end of the pos- 
 terior surface is uncovered. The ascending and descending colon are usually 
 covered only in front and at the sides; a variable amount of the posterior surface 
 is uncovered. The transverse colon is almost completely invested, the parts corre- 
 sponding to the attachment of the great omentum and transverse mesocolon being 
 alone excepted. The sigmoid flexure is completely surrounded, except along the 
 line to which the sigmoid mesocolon is attached. The upper two-thirds of the 
 rectum is covered in front and laterally by the peritoneum, but not posteriorly, 
 between the two posterior folds of peritoneum, the so-called mesorectum; later 
 
 1 Diseases of the Anus, Rectum, and Pelvic Colon. By James P. Tuttle. 
 
THE RECTUM 1317 
 
 it is covered only on its anterior surface; and the lower portion is entirely 
 devoid of any serous covering. In the course of the colon the peritoneal coat is 
 thrown into a number of small pouches filled with fat, called appendices epiploicse. 
 They are chiefly appended to the transverse colon, and are particularly numerous 
 along the anterior band. 
 
 The Muscular Coat {tunica muscularis). — The muscular coat consists of an 
 external longitudinal and an internal circular layer of muscular fibres. 
 
 The Longitudinal Fibres, although found to a certain extent all around the 
 intestine, do not form a uniform layer over the whole surface of the large 
 intestine. In the caecum and colon they are especially collected into three flat 
 longitudinal bands or taeniae {taeniae coli) (Figs. 910 and 911), each being about 
 half an inch in width. These bands commence at the base of the vermiform 
 appendix, which structure is surrounded by a uniform layer of longitudinal 
 muscular fibres. The bands pass from the base of the appendix to the rectum. 
 At this point they broaden, fuse, and surround the rectum. On the ascend- 
 ing, descending, and sigmoid colon the mesocolic band {taenia mesocolica) is 
 posterior and internal; the omental band {taenia omentalis) is posterior and 
 external; the free band {taenia libera) is anterior. On the transverse colon the 
 taenia libera is inferior; the taenia mesocolica is posterior; the taenia omentalis 
 is anterior and superior. These bands are one-sixth shorter than the other coats 
 of the intestine to which they are applied, and serve to produce the sacculi (Fig. 
 911), which are characteristic of the caecum and colon; accordingly, when they 
 are dissected off, the tube can be lengthened, and its sacculated character becomes 
 lost. The sacculations are called haustra coli. There are three rows of the sac- 
 culations separated from each other by the longitudinal bands. These pouches 
 are also subdivided by transverse furrows which correspond to concave folds of 
 mucous membrane, called semilunar folds {plicae semilunares coli) . In the sig- 
 moid flexure the longitudinal fibres become more scattered; but upon its lower 
 part, and around the rectum, they spread out and form a layer which completely 
 encircles this portion of the gut, but is thicker on the anterior and posterior 
 surfaces, where two accentuations exist, than on the lateral surfaces. In the 
 rectum the external fibres of the longitudinal layer descend and are inserted into 
 the fascia covering the Levator ani muscle. The middle fibres are mingled with 
 descending fibres of the Levator ani and terminate by attachment to the rectal 
 wall. The internal fibres descend between the External and Internal sphincter 
 muscles and are inserted into the superficial fascia around the anal margin. 
 The lower part of the rectum is surrounded by the Levator ani muscle (p. 451). 
 In addition to the muscular fibres of the bowels, two bands of plain muscular 
 tissue are to be noted. They arise from the front of the second and third coccy- 
 geal vertebrae, and pass downward and forward to blend with the longitudinal 
 muscular fibres on the posterior wall of the rectum. Each is known as the recto- 
 coccygeal muscle (m. rectococcygeus) . 
 
 The Circular Fibres form a thin layer over the caecum and colon, being especially 
 accumulated in the intervals between the sacculi. In the rectum the circular fibres 
 constitute a thick coat at some portions of the circumference and a thinner coat 
 at others. The circular fibres are thickened at every flexure. The thickenings 
 only partly surround the gut, and hence are not to be considered as additional 
 sphincters. Tuttle calls them the semicircular muscles of the rectum. These semi- 
 circular muscles are opposite the insertion of Houston's valves. At the lower end 
 of the rectum the circular fibres become very numerous and constitute the Internal 
 sphincter muscle (m. sphincter ani internus) (Fig. 930). Tuttle describes it as fol- 
 lows: "This muscle, composed of an aggregation of circular fibres, begins about 
 4 cm. above the anal margin, and gradually increases in thickness until it reaches 
 the ano-rectal line, after which it thins out again and disappears about the middle 
 
1318 
 
 THE ORGANS OF DIGESTION 
 
 of the anal canal. Its width from above downward averages 1 to 3 cm. (three-fifths 
 of an inch to one and one-fifth inches). Its thickness is so variable that no accurate 
 measurement can be given. Its lower fibres are below and within the grasp of the 
 External sphincter, from which it is separated by a narrow zone of connective 
 tissue. A depressed zone, not always perceptible to the eye, but appreciable 
 by digital touch, marks the line of division between these two muscles."^ The 
 Internal sphincter is an involuntary muscle. The external sphincter muscle is 
 not a portion of the wall of the bowel. It is described on pages 450 and 451. 
 
 The Areolax Coat or Submucous Coat {tela suhmucosa). — The areolar or sub- 
 mucous coat connects the muscular and mucous layers closely together. This coat 
 is thicker, looser, and more elastic in the rectum than elsewhere. In this coat are 
 the blood-vessels, nerves, and lymphatics. 
 
 The Mucous Membrane {tunica mucosa). — The mucous membrane, in the caecum 
 and colon, is pale, smooth, destitute of villi, and raised into numerous crescentic 
 folds which correspond to the intervals between the sacculi. In the rectum it is 
 thicker, of a darker color, more vascular, and connected loosely to the muscular 
 coat, as in the oesophagus. 
 
 The rectum contains certain horizontal folds. Most of them disappear when 
 the gut is distended, but some of them do not disappear, but remain as distinct 
 
 MUCOUS 
 MEMBRANE 
 
 DILATATION 
 
 OF VEINS~ 
 
 COLUMNS OF. 
 
 MORGAGNI 
 
 VALVE OF 
 
 MORGAGN 
 
 HILTON'S 
 WHITE LINE 
 
 MUSCULAR WALL 
 OF RECTUM 
 
 INTERNAL HEMOR- 
 RHOIDAL PLEXUS 
 
 DILATATION 
 OF VEIN 
 
 COMMUNICATION BE- 
 TWEEN INTERNALANB 
 EXTERNAL HEMOR- 
 RHOIDAL PLEXUS 
 INTERNAL 
 SPHINCTER 
 
 EXTERNAL 
 SPHINCTER 
 
 LONGITUDINAL 
 TENDINOUS FIBRES 
 
 SUBCUTANEOUS 
 CELLULAR TISSUE 
 
 Fig. 931.— -Inner wall of the lower end of the rectum and anus. On the right the mucous membrane has 
 been removed to show the dilatation of the veins and how they pass through the muscular wall to anastomose 
 with the external haemorrhoidal plexus. (Luschka.) 
 
 folds with free crescentic edges. These permanent folds were first described by 
 Houston, of Dublin, and are known as rectal valves or Houston's valves {'plicae 
 iransversales recti) (Figs. 928 and 929). Each fold surrounds more than one- 
 third of the gut, and is composed of mucous membrane, submucous tissue, and 
 a layer from the circular muscular layer of the gut. There may be three, four, or 
 five of these folds. Three of them are constant. One is on the right rectal wall, 
 about the point of peritoneal reflection; another is on the left side, about one 
 inch above the margin of the anal canal. A third is on the rectal wall, either 
 toward the right or left, at the point where the rectum joins the front of the 
 sigmoid. These shelf-like valves are not perfectly flat, for on the superior surface 
 of each is a depression. 
 
 The borders of a valve are thinner than its base and are very flexible. These 
 valves support the mass of faces as it descends, and give to it a rotary motion 
 
 1 Diseases of the Anus, Rectum, and Pelvic Colon. By James P. Tuttle. 
 
THE RECTUM I3I9 
 
 (Tuttle). In the lower end of the rectum the mucous membrane forms longi- 
 tudinal folds known as the columns of Morgagni or the rectal columns (columnae 
 redales [Morgagni]) (Figs. 930 and 931). There are from five to ten of these 
 folds, each of which is about one-half an inch long, and they contain longitudinal 
 muscle-fibres. They are most prominent when the sphincter contracts. The base 
 of each column helps to form the upper margin of the anal canal. The outer angle 
 of each column below passes into a semilunar valve. The grooves between the 
 columns are shallow above and deeper below, and end in the semilunar valves. 
 The semilunar valves, valves of Morgagni or anal valves (Figs. 930 and 931) are folds 
 which stretch from the base of one column to another, and form the anal pockets 
 or crypts of Morgagni {sinus redales). These pockets are about 5 mm. in depth. 
 They are most marked posteriorly (Ball), but none exists in either the anterior 
 or posterior commissure (Tuttle). Below the sinuses is the white line of Hilton 
 {annulus haemorrhoidalis) (Fig. 931), which reaches to the region where hair and 
 sebaceous glands appear. 
 
 Fig. 932. — The arterial circulation in the dorsal pcsterior surface of the caecum and appendix. A, ileo-colic 
 artery; B and F, posterior caecal artery; C, appendicular artery; E, appendicular artery for free end; H , artery 
 for basal end of api>endix; 1, ascending or right colon; 2, external sacculus of the caecum; 3, appendix; 6, ileum; 
 D, arteries on the dorsal surface of the ileum. (Byron Robinson.) 
 
 As in the small intestine, the raucous membrane consists of a muscular layer, the 
 muscularis mucosae (Fig. 935) ; of a quantity of retiform tissue in which the vessels 
 ramify; of a basement-membrane and epithelium, which is of the columnar variety, 
 and exactly resembles the epithelium found in the small intestine. In the rectum 
 the epithelial cells are columnar; at the lower end of the tube, however, they begin 
 to change into stratified polyhedrons and prisms. The mucous membrane of the 
 large intestine presents for examination simple follicles and solitary glands. 
 
 The simple Follicles, Intestinal Glands, Crypts or Glands of Lieberkiihn (glandulae 
 iniestinales [Lieberkuhni]) (Fig. 935) are minute tubular prolongations of the 
 mucous membrane arranged perpendicularly, side by side, over its entire sur- 
 face; they are longer, more numerous, and are placed in much closer apposition 
 than those of the small intestine; and they open by minute rounded orifices upon 
 the surface, giving it a cribriform appearance. 
 
1320 
 
 THE ORGANS OF DIGESTION 
 
 The Solitary Glands {iioduli lymphatici solitarii) (Fig. 935) in the large intes- 
 tine are most abundant in the caecum and vermiform appendix, but are irregu- 
 larly scattered also over the rest of the intestine. They are similar to those of the 
 small intestine. 
 
 Vessels of the Large Intestine. — The arteries supplying the large intestine give 
 off large branches, which ramify between the muscular coats supplying them, 
 and, after dividing into small vessels in the submucous tissue, pass to the 
 mucous membrane. The caecum, the appendix, and the ileo-caecal valve are sup- 
 plied by the branches from the anastomotic loops between the right colic and ileo- 
 
 FiG. 933. — The arterial blood-supply of the anterior (ventral) surface of the caecum and appendix. A, ileo- 
 colic artery; B, caecal-appendicular artery; D, anterior caecal artery; F and G, appendicular artery. Note that 
 the caecal and appendicular arteries anastomose by fine capillaries, both ventral and dorsally; C, iliac artery; 
 1, right colon; 2, external sacculus of caecum (to right of taenium coh); 3, appendix; 4, Iliac, and 5, Psoas muscles. 
 (Byron Robinson.) 
 
 colic branches of the superior mesenteric artery (Figs. 932 and 933). In males the 
 sole blood-supply of the appendix is by the appendicular artery from the posterior 
 ileo-caecal branch of the ileo-caecal artery (Fig. 933). In the female the appendix 
 occasionally receives an additional vessel along the appendiculo-ovarian ligament 
 from the ovarian artery. The ascending colon is supplied by the right colic, and the 
 transverse colon by the middle colic branch of the superior mesenteric. The 
 descending colon is supplied by the left colic branch of the inferior mesenteric, 
 and the sigmoid flexure by the sigmoid branches of the inferior mesenteric. The 
 rectum (Fig. 934) is supplied mainly by the superior haemorrhoidal branch of the 
 inferior mesenteric, but also at its lower end by the middle haemorrhoidal from 
 the internal iliac, and the inferior haemorrhoidal from the pudic artery. The supe- 
 
THE RECTUM 
 
 1321 
 
 SUPERIOR 
 
 EMORRHOIDAL 
 EIN 
 
 SUPERIOR 
 
 HEMORRHOIDAL 
 
 ARTERY 
 
 rior haemorrhoidal, the continuation of the superior mesenteric, divides into two 
 branches, which run down either side of the rectum to within about five inches 
 of the anus; they here spHt up into about six branches, which pierce the 
 muscular coat and descend between it and the mucous membrane in a longi- 
 tudinal direction, parallel with each other as far as the Internal sphincter, where 
 they anastomose with the other haemorrhoidal arteries and form a series of loops 
 around the anus. The veins of the large intestine correspond to the arteries and 
 join the superior and inferior mesenteric veins which join the portal vein. The veins 
 of the rectum (Fig. 934) coi»mence in a plexus of vessels which surrounds the lower 
 extremity of the intestinal canal. In the vessels forming this plexus are small 
 saccular dilatations just within the margin of the anus (Figs. 931 and 934); 
 from it about six vessels of considerable size are given off. These ascend between 
 the muscular and mucous 
 coats for about five inches, 
 running parallel to each 
 other ; they then pierce the 
 muscular coat, and, by their 
 union, form a single trunk, 
 the superior haemorrhoidal 
 vein, which empties into the 
 inferior mesenteric branch of 
 the portal vein. This arrange- 
 ment is termed the haemor- 
 rhoidal plexus (Fig. 473); it 
 communicates with the tribu- 
 taries of the middle and infe- 
 rior haemorrhoidal veins at its 
 commencement, and thus a 
 communication is established 
 between the systemic and 
 portal circulations. The in- 
 ferior haemorrhoidal veins 
 empty into the internal pudic 
 veins, and the middle haemor- 
 rhoidal veins empty into the 
 internal iliac veins. 
 
 The Lymphatics of the Large 
 Intestine . — The lymphatics 
 of the large intestine begin 
 in the mucous membrane and 
 form an extensive plexus in 
 the submucosa. There are 
 also lymphatics more deeply 
 seated, beneath the simple 
 follicles. Those from the 
 ascending colon and trans- 
 verse colon open into the 
 
 glands Wnthin the mesocolon _ Fig. 934.— The blood-vessels of the rectum and anus, showing the 
 1 1 , . , .1 I , distribution and anastomosis on the posterior surface near the termi- 
 
 and benmci the colon (meSO- nation of the gut. (Poirier and Charpy.) 
 
 colic glands), from which 
 
 glands trunks pass to the superior mesenteric glands. The lymphatics from the 
 transverse colon join with lymph-vessels of the great omentum, and hence com- 
 municate with the lymphatics of the greater curvature of the stomach. The lymph 
 from the descending colon, from the sigmoid and from the pelvic colon passes to 
 
 MIDDLE 
 
 HEMORRHOIDAL 
 
 ARTERY 
 
 NFERIOR 
 HEMORRHOIDAL 
 ARTERY 
 
1322 
 
 THE ORGANS OF DIGESTION 
 
 the glands along the inferior mesenteric artery. The lymphatics of the rectum 
 pass first to the rectal glands, which lie on the muscular coat of the rectum, next to 
 the glands which lie back of the rectum along the superior haemorrhoidal artery, 
 and finally to the sacral glands. Lymphatics from the skin of the anus pass 
 with the lymphatics of the skin to the superficial inguinal glands. Lymphatics 
 from the anus between the skin margin and Hilton's white line pass to the hypo- 
 gastric glands. 
 
 The Nerves of the Anus and Rectum. — The nerves of the anus and rectum are 
 derived from both the sympathetic and cerebro-spin^ system. The chief supply 
 of the rectum is from the mesenteric, sacral, and hypogastric plexuses of the sympa- 
 thetic. It also obtains small branches from the third, fourth, and fifth sacral nerves. 
 The lower part of the rectum is much more sensitive than the upper part. 
 The muscles of the anus and rectum are supplied " from the intricate plexuses 
 formed by the second, third, fourth, and fifth sacral nerves" (Tuttle). The 
 External sphincter is supplied by nerves which contain motor, sensory, and 
 
 Surface of mucous membrane, 
 u-iih openings of Lieberkuhn's 
 follicles. 
 
 Lieberkiihn's follicles. 
 
 Sri Muscularis mucosae (two layers). 
 
 ^ ^1 Submucous conjieclive tissue. 
 
 Solitary gland. 
 
 Fig. 935. — Minute structure of large intestine. 
 
 sympathetic fibres. These nerves come from three sources. "Two filaments 
 from the branches formed by the third, fourth, and fifth sacral nerves extend 
 transversely across the ischio-rectal fossa and distribute themselves to the middle 
 portion of the muscle and to the peri-anal cutaneous surface; a filament which 
 comes off from the internal pudic just before its division into terminal branches 
 supplies the anterior portion of the muscle, and is called the anterior sphincterian 
 nerve ; while a filament coming off from the fifth and sixth sacral nerves passes 
 down into the hollow of the sacrum, between the I^evator ani muscle and the recto- 
 coccygeus ligament, and finally reaches the posterior superficial surface of the 
 External sphincter."* The spinal centre for the nerves of the anus and rectum is 
 opposite the first lumbar vertebra, and is in practically the same region as the 
 centre for the genito-urinary organs. 
 
 Movements and Innervation of the Intestines. 
 
 Movements. — As the small intestine is devoid of any sphincter arrangement peristalsis cannot 
 mix the food as it does in the pyloric portion of the stomach. The process by which the food is 
 mixed with the secretions and is brought against the intestinal v.all for absorption is called 
 by Cannon "rhythmic segmentation." Rhythmic motions, according to Cannon, "mix the 
 
 1 Diseases of the Anus, Rectum, and Pelvic Colon. By James P. Tuttle 
 
MOVEMENTS AND INNERVATION OF THE INTESTINES 1323 
 
 food and expose it to the mucosa without advancing it appreciaiely along the canal."' In this 
 process constrictions occur in the circular fibres, with the result that a collection of stationary 
 food is divided into a number of segments. In the middle of each segment constrictions ap})ear 
 and the earlier constrictions relax. Then the later constrictions relax and the earlier reappear 
 and so on until the food is thoroughly mixed with digestive secretions. Finally the food is 
 driven on by peristalsis coming again to rest and being again subjected to " rhythmic segmenta- 
 tion."^ Cannon says that in the duodenum "rhythmic segmentation" lasts for several minutes, 
 but in other parts of the intestine it may continue for half an hour or more, the food which is 
 being subjected to it scarcely moving along the canal. Cannon infers that in man there are 
 from seven to eight segmentations per minute in a given area. It is probable that there is a 
 sphincter action at the ileo-caecal opening. 
 
 Cannon divides the large intestine into two parts: a distal part, in which the material is hard 
 and lumpy and is "advanced by rings of tonic contraction," and a proximal part, in which 
 the material is soft. In this part "the common movements are waves of constriction running 
 backward toward the caecum."^ The resistance of the valve or sphincter enables reversed 
 peristalsis or antiperistalsis to mix the food. When more food enters from the small intestine, 
 antiperistalsis ceases, tonic contraction of the caecum and proximal portion of the colon occurs, 
 some of the food is merged into the transverse colon, and antiperistalsis again begins to act 
 on what remains.* The above facts have been observed in animals and are probably true in 
 man. 
 
 Innervation. — The pneumogastric fibres of the small intestine seem to excite contraction of 
 the circular fibres after a brief preliminary period of inhibition.* Some observers maintain 
 that the splanchnic fibres are inhibitory, but others claim that they are also motor. The local 
 reflex of the small intestine is in Auerbach's plexus. Cannon quotes Bayliss and Starling to 
 the effect that the pelvic visceral nerves to the large intestine, "arising like the vagus from the 
 central nervous system, are augmentary nerves, whereas the supply from the sympathetic sys- 
 tem is purely inhibitory in its action."** It is further contended that the pelvic visceral nerves 
 are distributed to the distal colon only. "The region of antiperistalsis does not, therefore, 
 receive motor impulses from the pelvic nerves."' 
 
 Surface Form. — The coils of the small intestine occupy the front of the abdomen below the 
 transverse colon, and are covered more or less completely by the great omentum. For the most 
 part the coils of the jejunum occupy the left side of the abdominal cavity — i. e., the left lumbar 
 and inguinal regions and the left half of the umbilical region — whilst the coils of the ileum are 
 situated to the right, in the right lumbar and inguinal regions, in the right half of the umbilical 
 region, and also in the hypogastric region. The caecum is situated in the right inguinal region. 
 Its position varies slightly, but the mid-point of a line drawn from the anterior superior spinous 
 process of the ilium to the symphysis pubis will about mark the middle of its lower border. It is 
 comparatively superficial. From it the ascending colon passes upward through the right lumbar 
 and hypochondriac regions, and becomes more deeply situated as it ascends to the hepatic flexure, 
 which is deeply placed under cover of the liver. The transverse colon crosses the belly trans- 
 versely on the confines of the umbilical and epigastric regions, its lower border being on a level 
 slightly above the umbilicus, its upper border just below the greater curvature of the stomach. 
 The splenic flexure of the colon is situated behind the stomach in the left hypochondrium, and 
 is on a higher level than the hepatic flexure. The descending colon is deeply seated, passing 
 down through the left hypochondriac and lumbar regions to the sigmoid flexure, which is situ- 
 ated in the left inguinaf region, and which can be felt in thin persons, with relaxed abdominal 
 walls, rolling under the fingers when empty, and when distended forming a distinct bulge. The 
 position of the base of the vermiform appendix is indicated by a point two inches from the 
 anterior superior spinous process of the ilium, on a line drawn from this process to the umbilicus. 
 This is known as McBurney's point. Another mode of defining the position of the base of the 
 appendix is to draw a line between the anterior superior spines of the ilia and marking the point 
 where this line intersects the right semilunar line. 
 
 Upon introducing the finger into the rectum, the membranous portion of the urethra can 
 be felt, if an instrument has been introduced into the bladder, exactly in the middle line; behind 
 this the prostate gland can be recognized by its shape and hardness and any enlargement detected; 
 behind the prostate the fluctuating wall of the bladder when full can be felt, and if thought 
 desirable it can be tapped in this situation; on either side and behind the prostate the vesiculae 
 seminales can be readily felt, especially if enlarged by tuberculous disease. Behind, the coccyx 
 is to be felt, and on the mucous membrane one or two of Houston's folds. The ischio-rectal 
 fossae can be explored on either side, with a view to ascertaining the presence of deep-seated 
 collections of pus. Finally, it will be noted that the finger is firmly gripped by the sphincter for 
 about an inch up the bowel. By gradual dilatation of the sphincter, the whole hand can be 
 
 ' Medical News, May 20, 1905. - Walter B. Cannon, in Medical News, May 20, 1305. 
 
 » Medical News, May 20, 1905. ■• Ibid. 
 
 * Bayliss and Starling, Journal of Physiology, 1899. 
 
 6 Medical News, May 20, 1905. Walter B. Caunon, Medical News, May 20, 1905. 
 
1324 THE ORGANS OF DIGESTION 
 
 introduced into the rectum so as to reach the descending colon. This method of exploration is 
 not at the present day employed for diagnostic purposes. 
 
 Surgical Anatomy. — The small intestine is much exposed to injury, but, in consequence 
 of its elasticity and the ease with which one fold glides over another, it is not so frequently rup- 
 tured as would otherwise be the case. Any part of the small intestine may be ruptured, bui 
 probably the most common situation is the transverse duodenum, on account of its being more 
 fixed than other portions of the bowel, and because it is situated in front of the bodies of the 
 vertebrae, so that if this portion of the intestine is struck a sharp blow, as from the kick of a 
 horse, it is unable to glide out of the way, but is compressed against the bone and lacerated. 
 Wounds of the intestine sometimes occur. If the wound is a small puncture, under, it is said, 
 three lines in length, there may be no extravasation of the contents of the bowel. The mucous 
 membrane becomes everted and perhaps plugs the little opening. The bowels, therefore, may be 
 punctured with a fine capillary trocar, in cases of excessive distention of the intestine with gas, with- 
 out much danger of extravasation. A longitudinal wound gapes more than a transverse wound, 
 owing to the greater thickness of the circular muscular coat. In closing a wound of the intestine, 
 use Lembert's inversion sutures, which bring the peritoneal surfaces in contact. Halsted showed 
 us that these sutures must include the tough submucous coat. The portions of intestine which lie 
 in the pelvis are inflamed in pelvic peritonitis and become embedded in adhesions. The portions 
 of intestine which may be present are the termination of the ileum, the portion of small intestine 
 with the largest mesentery (Treves), the rectum, and the pelvic colon. The small intestine, and 
 most frequendy the ileum, may become strangulated by internal bands, or through apertures, 
 normal or abnormal. The bands may be formed in several different ways: they may be old peri- 
 toneal adhesions from previous attacks of peritonitis; or adherent omentum from the same 
 cause; or the band may be formed by Meckel's diverticulum, which has contracted adhesions at 
 its distal extremity; or the band may be the result of the abnormal attachment of some normal 
 structure, as the adhesion of two appendices epiploicae, or an adherent vermiform appendix or 
 Fallopian tube. Iniussusception or invagination of the small intestine may take place in any part 
 of the jejunum and ileum, but the most frequent situation is at the ileo-caecal valve, the valve 
 forming the apex of the entering tube. This form may attain great size, and it is not uncom- 
 mon in these cases to find the valve projecting from the anus. Stricture, the impaction of 
 foreign bodies, and twisting of the gut (volvulus) may lead to intestinal obstruction. Volvulus is 
 most common in the sigmoid flexure. Meckel's diverticulum may itself become twisted and 
 strangulated. 
 
 Resection of a portion of the intestine may be required in cases of gangrenous gut; in cases- 
 of intussusception; for the removal of new growth in the bowel; in dealing with artificial anus^ 
 and in cases of rupture. The operation is termed enterectomy, and is performed as follows: the 
 abdomen having been opened and the amount of bowel requiring removal having been deter- 
 mined upon, the gut must be clamped on either side of this portion in order to prevent the escape 
 of any of the contents of the bowel during the operation. The portion of bowel is then separated 
 above and below by means of scissors. If the portion removed is small, it may be simply removed 
 from the mesentery at its attachment and the bleeding vessels tied; but if it is large, it will be 
 necessary to remove also a triangular piece of the mesentery, and having secured the vessels, 
 suture the cut edges of this structure together. The surgeon then proceeds to unite the cut 
 ends of the bowel together. He may do it by the operation termed end-to-end anastomosis. 
 There are many ways of doing this, which may be divided into two classes: one, where the anas- 
 tomosis is made by means of some mechanical appliance, such as Murphy's button, or one of 
 the forms of decalcified bone bobbins; and the other, where the operation is performed by 
 simply suturing the ends of the bowel in such a manner that the peritoneum covering the free 
 divided ends of the bowel is brought into contact, so that speedy union may ensue. 
 
 In some cases after resection each open end of the gut is closed, the side of the terminal portion 
 is sutured to the side of the initial portion, a fistula is made in each, and the suturing is com- 
 pleted so as to cause the two fistulae to correspond. A permanent side-to-side opening is 
 thus made. Lateral anastomosis without resection may be practised between two pieces of 
 intestine, in order to side-track an intervening portion, which is the seat of malignant disease or 
 of an artificial anus. Complete exclusion of a portion of intestine is performed for irremovable 
 tumors or persistent fsecal fistulae of the large intestine. The intestine is cut through above and 
 below the diseased area and the ends of the healthy gut are united to each other, or the larger 
 end is closed, an opening is made into the side of the larger end and the smaller end is implanted 
 in it {lateral implantation). The two ends of the excluded portion are fastened to the skin and 
 are left open. 
 
 In ascites resulting from cirrhosis of the liver benefit occasionally follows the performance of 
 Talma's operation (epiplopexy) . The abdomen is opened and the omentum is sutured to the 
 anterior abdominal wall or in the abdominal wound in the hope of establishing a more free 
 communication between the portal and systemic circulations, thus lowering portal pressure. 
 
 External hernia is considered on page 1325. 
 
 By the term internal hernia, we mean hernia into the foramen of Winslow, into the retro- 
 
MOVEMENTS AND INNERVATION OF THE INTESTINES 1325 
 
 duodenal fossa, into the retro-caecal fossa, or into the intersigmoid fossa. Such a hernia produces 
 the symptoms of acute strangulation of the intestine. 
 
 In fyphoid fever there is ulceration of Peyer's patches. One of these ulcers may perforate. 
 The only chance for life is immediate laparotomy and closure of the perforation. This saves 
 one-fifth, or possibly one-third, of the cases. The incision is made to expose the lower ileum, as 
 in the vast majority of cases the perforation is in this portion of the gut. 
 
 Ulcer of the duodenum is more common than used to be thought. The portion of the duo- 
 denum between the pylorus and the bile papilla is about four inches in length, and is called by 
 the Mayo brothers the veMibule of the duodenum. Here the acid gastric juice enters and may pro- 
 duce an ulcer. The portion of the duodenum below the vestibule is not liable to ulcer, because 
 it is protected by the alkaline bile and pancreatic juice. 
 
 A duodenal ulcer may perforate a large duodenal vessel and cause death from hemorrhage, 
 or may perforate the intestine and produce septic peritonitis. A perforated ulcer is treated 
 by laparotomy and closure of the perforation. Occasionally ulceration of the duodenal glands 
 (Curling's ulcer) may occur in cases of burns, but is not a very common complication. 
 
 The vermiform api)endix is very liable to become inflamed, the condition being known as 
 appendicitis. This condition may be set up by a catarrhal inflammation arising in the appen- 
 dix or derived from the colon. It may remain catarrhal and then subside. It may become 
 purulent or may be purulent from the beginning. Anything which lessens vital resistance 
 makes the appendix a ready prey to bacteria. Among causes which lessen resistance are faecal 
 concretions, twists of the mesoappendix cutting off the blood-suj>ply, bruises inflicted by the Psoas 
 muscle (Byron Robinson), blocking of the outlet of the appendix by catarrhal exudate, concre- 
 tions, proliferated lymphoid tissue, or adhesions. Appendicitis may arise by the appendix becom- 
 ing twisted, owing to the shortness of its mesentery, in consequence of distention of the caecum. 
 As the result of inflammation, its blood-supply, which is mainly through one large artery running 
 in the mesoappendix, becomes interfered with. Again, in rarer cases, the inflammation is set 
 up by the impaction of a solid mass of faeces or a foreign body in the appendix. The inflammation 
 may result in ulceration and perforation, or in gangrene of the appendix the appendix may be 
 blocked and full of pus, or abscess may form outside of it (appendicular abscess). These con- 
 ditions require prompt operative interference, and in cases of recurrent attacks of appendicitis it 
 is advisable to remove this diverticulum between the attacks. In external hernia the ileum 
 is the portion of bowel most frequently herniated. When a part of the large intestine is 
 involved, it is usually the caecum, and this may occur even on the left side. In some few cases 
 the vermiform appendix has been the part implicated in cases of strangulated hernia, and has 
 given rise to serious symptoms of obstruction. The diameter of the large intestine gradually 
 diminishes from the caecum, which has the greatest diameter of any part of the bowel, to the 
 point of junction of the sigmoid flexure with the rectum, at or a little below which point stricture 
 most commonly occurs and diminishes in frequency as one proceeds upward to the caecum. 
 When distended by some obstruction low down, the outline of the large intestine can be defined 
 throughout nearly the whole of its course — all, in fact, except the hepatic and splenic flexures, 
 which are more deeply placed ; the distention is most obvious in the two flanks and on the front 
 of the abdomen just above the umbilicus. The caecum, however, is that portion of the bowel 
 which is, of all, most distended. It sometimes assumes enormous dimensions, and has been 
 known to give way from the distention, causing fatal peritonitis. The hepatic flexure and the right 
 extremity of the transverse colon are in close relationship with the liver, and abscess of this viscus 
 sometimes bursts into the gut in this situation. The gall-bladder may become adherent to the 
 colon, and gall-stones may find their way through into the gut, where they may become impacted 
 or may be discharged per anum. The mobility of the sigmoid flexure renders it more liable to 
 become the seat of a volvulus or twist than any other part of the intestine. It generally occurs 
 in patients who have been the subjects of habitual constipation, and in whom, therefore, the 
 mesosigmoid is elongated. The gut at this part being loaded with faeces, from its weight falls 
 over the gut below, and so gives rise to the twist. 
 
 The surgical anatomy of the rectum is of considerable importance. There may be congenital 
 malformation due to arrest or imperfect development. Thus, there may be no invagination of 
 the epiblast, and consequently a complete absence of the anus; or the hind-gut may be imper- 
 fectly developed, and there may be an absence of the rectum, though the anus is developed; 
 or the invagination of the epiblast may not communicate with the termination of the hind-gut 
 from want of solution of continuity in the septum which in early foetal life exists between the 
 two. The mucous membrane is thick and but loosely connected to the muscular coat beneath 
 and thus favors prolapse, especially in children The vessels of the rectum are arranged as 
 mentioned above, longitudinally, and are contained in the loose cellular tissue between the 
 mucous and muscular coats, and receive no support from surrounding tissues, and this favors 
 varicosity. Moreover, the veins, after running upward in a longitudinal direction for about five 
 inches in the submucous tissue, pierce the muscular coats, and are liable to become constricted 
 at this point by the contraction of the muscular wall of the gut. In addition to this there are no 
 valves in the superior hemorrhoidal veins, and the vessels of the rectum are placed in a depen- 
 
1326 THE ORGANS OF DIGESTION 
 
 dent position, and are liable to be pressed upon and obstructed by hardened faeces. The anatom- 
 ical arrangement, therefore, of the hemorrhoidal vessels explains the great tendency to the 
 occurrence of piles. The presence of the Sphincter ani is of surgical importance, since it is the 
 constant contraction of this muscle which prevents an ischio-rectal abscess from healing and 
 tends to cause a fistula. Also, the reflex contraction of this muscle is the cause of the severe pain 
 complained of in fissure of (he anus. The relations of the peritoneum to the rectum are of 
 importance in connection with the operation of removal of the lower end of the rectum for 
 malignant disease. The membrane gradually leaves the rectum as it descends into the pelvis; 
 first leaving its posterior surface, then the sides, and then the anterior surface to become 
 reflected in the male on to the posterior wall of the bladder, forming the recto-vesical pouch, and 
 in the female on to the posterior wall of the vagina, forming Douglas's pouch. The recto-vesical 
 pouch of peritoneum extends to within three inches from the anus, so that it is not desirable 
 to remove more than two and a half inches of the entire circumference of the bowel, for fear 
 of the risk of opening the peritoneum. When, however, the disease is confined to the poste- 
 rior surface of the rectum, or extends farther in this direction, a greater amount of the poste- 
 rior wall of the gut may be removed, as the peritoneum does not extend on this surface to a 
 lower level than five inches from the margin of the anus. The recto-vaginal or Douglas's pouch 
 in the female extends somewhat lower than the recto-vesical pouch of the male, and therefore 
 it is advisable to remove a less length of the tube in this sex. Of recent years, however, much 
 more extensive operations have been done for the removal of cancer of the rectum, and in these 
 the peritoneal cavity has necessarily been opened. If, in these cases, the opening is plugged 
 with iodoform gauze until the operation is completed and then the edges of the wound in the 
 peritoneum is accurately brought together with sutures, no evil result appears to follow. For 
 cases of cancer of the rectum which are too low to be reached by abdominal section, and too 
 high to be removed by the ordinary operation from below, Kraske has devised an operation 
 which goes by his name. The patient is placed on his right side and an incision is made from 
 the second sacral spine to the anus. The soft parts are now separated from the back of the 
 left side of the sacrum as far as its left margin, and the greater and lesser sacro-sciatic liga- 
 ments are divided. A portion of the lateral mass of the sacrum, commencing on the left border 
 at the level of the third posterior sacral foramen, and running downward and inward through 
 the fourth foramen to the cornu, is now cut away with a chisel. The left side of the wound 
 being now forcibly drawn outward, the whole of the rectum is brought into view, and the dis- 
 eased portion can be removed, leaving the anal portions of the gut, if healthy. The two divided 
 ends of the gut can perhaps then be approximated and sutured together. Kraske's operation is 
 in many cases preceded by the performance of iliac colostomy. In cancer high up in the 
 rectum removal of the growth through the abdomen is sometimes practised, the divided lower 
 end of the rectum being sutured to the divided upper end (Weir's operation). 
 
 The colon frequently requires opening in cases of intestinal obstruction, and by some sur- 
 geons this operation is performed in cases of cancer of the rectum, as soon as the disease is 
 recognized, in the hope that the rate of growth may be retarded by removing the irritation pro- 
 duced by the passage of fecal matter over the diseased surface. The operation of colostomy may 
 be performed either in the inguinal or lumbar region; but inguinal colostomy (Maydl's opera- 
 tion) has at the present day superseded the lumbar operation. The main reason for preferring 
 this operation is that a spur-shaped process can be formed which prevents any fecal matter find- 
 ing its way past the artificial anus and becoming lodged on the diseased structures below. The 
 sigmoid flexure being surrounded by peritoneum, a coil can be drawn out of the wound, and 
 when it is opened transversely a spur is formed, and this prevents any fecal matter finding its 
 way from the gut above the opening into that below. The operation is performed by making an 
 incision two or three inches in length from a point one inch internal to the anterior superior 
 spinous process of the ilium, parallel to Poupart's ligament. The various layers of abdominal 
 muscles are cut through, and the peritoneum opened and sewed to the external skin. The sigmoid 
 flexure is now sought for, and pulled out of the wound and fixed by pushing a glass bar through 
 a slit in the mesocolon. The two parts of the loop are sutured together. The intestine is now 
 sutured to the parietal peritoneum. The wound is dressed, and either immediately or between 
 the second to the fourth day, according to the requirements of the case, the protruded coil of 
 intestine is opened. It is opened transversely with the Paquelin cautery. 
 
 THE LIVER (HEPAR) (Figs. 936, 937, 938, 939). 
 
 The liver is the largest gland in the body, and is situated in the upper and 
 right part of the abdominal cavity, occupying almost the whole of the right hypo- 
 chondrium, the greater part of the epigastrium, and extending into the left hypo- 
 chondrium as far as the mammary hne. In the male it weighs from fifty to sixty 
 
THE LIVER 1327 
 
 ounces; in the female, from forty to fifty. It is relatively much larger in the foetus 
 than in the adult, constituting, in the former, about one-eighteenth, and in the 
 latter, about one-thirty-sixth of the entire body-weight. Its greatest transverse 
 measurement is from eight to nine inches. Vertically, near its lateral or right 
 surface, it measures about six or seven inches, while its greatest antero-posterior 
 diameter is on a level with the upper end of the right kidney and is from four to 
 five inches. Opposite the vertebral column its measurement from before backward 
 is reduced to about three inches. Its consistence is that of a soft solid; it is, 
 however, friable and easily lacerated; its color is a dark reddish-brown, and its 
 specific gravity is 1.05. 
 
 To obtain a correct idea of its shape, it must be hardened in situ, and it will 
 then be seen to present the appearance of a wedge, the base of which is directed 
 to the right and the thin edge toward the left. Symington describes its shape as 
 that "of a right-angled triangular prism with the right angles rounded off." It 
 possesses five surfaces, viz., a superior, inferior, anterior, posterior, and a right lateral 
 surface. 
 
 Gall-bladder. 
 
 RIGHT LATERAL 
 
 LIGAMENT. 
 
 LEFT LATERAL ( 
 LIGAMtNT. 
 
 Fig. 936. — The liver. Upper surface. (Drawn from His's models.) 
 
 The superior and anterior surfaces are separated from each other by a thick 
 rounded border, and are attached to the Diaphragm and anterior abdominal wall 
 by a triangular or falciform fold of peritoneum, the suspensory or falciform liga- 
 ment, which divides the liver into two unequal parts, termed the right and left 
 lobes (Figs. 936, 940, and 941). Except along the line of attachment of this liga- 
 ment to the liver, the superior and anterior surfaces are covered by peritoneum. 
 
 The Superior Area or Surface (fades superior) (Fig. 936). — The superior 
 area or surface comprises a part of both lobes. Spalteholz considers as parts of 
 the superior surface the right surface and the anterior surface. The superior sur- 
 face is convex, and fits under the vault of the Diaphragm ; its central part, however, 
 presents a shallow depression, the cardiac depression (impressio cardiaca), which 
 corresponds with the position of the heart on the upper surface of the Diaphragm. 
 It is separated from the anterior, posterior, and lateral surfaces by thick, rounded 
 borders. Its left extremity is continued into the under surface by a prominent 
 sharp margin. 
 
 The Anterior Area or Surface. — The anterior area or surface is large and 
 triangular in shape, comprising also a part of both lobes. It is directed forward. 
 
1328 
 
 THE ORGANS OF DIGESTION 
 
 and the greater part of it is in contact with the Diaphragm, which separates it 
 from the right lower ribs and their cartilages. In the middle line it lies behind 
 
 Gi'eat splanchnic 
 
 nerve piercing 
 
 crua. 
 
 Rcceptdculum 
 chyli 
 
 Semilunar 
 ganglion. 
 
 (heat iplanchmc 
 
 neiu piercing 
 
 uus 
 
 'Semilunar 
 ganglion 
 
 Fig. 937. — The relations of the viscera and large vessels of the abdomen. (Seen from behind, 
 the last dorsal vertebra being well raised.) 
 
 the ensiform cartilage, to the left of which it is protected by the seventh and 
 eighth left costal cartilages. In the angle between the diverging rib cartilages 
 of opposite sides the anterior surface is in contact with the abdominal wall. It 
 
THE LIVER 1329 
 
 is continuous with the inferior surface by a sharp margin, and with the superior 
 and lateral surfaces by thick rounded borders. 
 
 The Lateral or Right Area or Surface (Figs. 936 and 938).— The lateral or 
 right area or surface is convex from before backward and slightly so from 
 above downward. It is directed toward the right side, forming the base of the 
 wedge, and lies against the lateral portion of the Diaphragm, which separates 
 it from the lower part of the left pleura and lung, outside which are the right 
 costal arches from the seventh to the eleventh inclusive. 
 
 The Under or Visceral Area or Surface {jades inferior) (Figs. 938 and 939). — 
 The under or visceral area or surface is uneven, concave, directed downward and 
 backward and to the left, and is in relation with the stomach and duodenum, the 
 hepatic flexure of the colon, and the right kidney. The surface is divided by a 
 longitudinal fissure into a right and a left lobe, and is almost completely invested 
 by peritoneum; the only parts where this covering is absent are where the gall- 
 bladder is attached to the liver and at the transverse fissure, where the two layers 
 of the lesser omentum are separated from each other by the blood-vessels and 
 duct of the viscus. The under surface of the left lobe presents to the right and 
 near the centre a rounded eminence, the omental tuberosity {tuher omentale) (Fig. 
 938), which is in contact with the lesser omentum. It is surrounded by a broad 
 depression, the gastric surface or impression (impressio gastrica), with which the 
 stomach is in contact. Between the gall-bladder and the left lobe is the quad- 
 rate lobe. The quadrate lobe is bounded to the left by the umbilical fissure or the 
 fissure of the umbilical vein (fossa venae umbilicalis) , which is the anterior portion 
 of the longitudinal fissure and lodges the round ligament (ligamentum teres) . The 
 under surface of the right lobe is divided into two unequal portions by a fossa, 
 which lodges the gall-bladder and is called the fossa vesicalis (fossa vesicae felleae) ; 
 the portion to the left, the smaller of the two, is somewhat oblong in shape, its 
 antero-posterior diameter being greater than its transverse. It is known as the 
 quadrate lobe (lobus quadratus), and is in relation with the pyloric end of the 
 stomach (impressio pylorica) and the first portion of the duodenum. The portion 
 of the under surface of the right lobe to the right of the fossa vesicalis presents 
 two shallow concave impressions, one situated behind the other, the two being 
 separated by a ridge. The anterior of these two impressions, the colic impression 
 (impressio colica), is produced by the hepatic flexure of the colon; the posterior, 
 the renal impression (impressio renalis), is occupied by the upper end of the 
 right kidney (Fig. 938). To the inner side of the latter impression is a third 
 and slightly marked impression, lying between it and the neck of the gall- 
 bladder. This is caused by the second portion of the duodenum, and is known 
 as the duodenal impression (impressio duodenalis). Just in front of the vena cava 
 is a narrow strip of liver tissue, the caudate lobe, which connects the right infe- 
 rior angle of the Spigelian lobe to the under surface of the right lobe. Imme- 
 diately below it is the foramen of Winslow. 
 
 The Posterior Area or Surface (fades posterior) (Figs. 937 and 939). — The 
 posterior area or surface is rounded and broad behind the right lobe, but narrow 
 on the left. Over a large part of its extent it is not covered by peritoneum ; this 
 uncovered area (Fig. 938) is about three inches broad, and is in direct contact with 
 the Diaphragm, being united to it by areolar tissue. In this tissue are numerous 
 small veins which join the portal circulation to the systemic circulation. The 
 uncovered area is marked off from the upper surface by the line of reflection of 
 the upper or anterior layer of the coronary ligament. It is in the same way 
 marked off from the under surface of the liver by the line of reflection of the lower 
 layer of the coronary ligament (Fig. 940). In its centre the posterior surface is deeply 
 notched for the vertebral column and crura of the Diaphragm, and to the right 
 of this it is indented for the inferior vena cava (fossa venae cavae), which is often 
 
 84 
 
1330 
 
 THE ORGANS OF DIGESTION 
 
 partly embedded in its substance. Close to the right of this indentation and 
 immediately above the renal impression is a small triangular depressed area, the 
 suprarenal impression (impressio suprarenalis) (Fig. 938), the greater part of which 
 is devoid of peritoneum ; it lodges the right suprarenal capsule, which is inserted 
 between the liver and Diaphragm. To the left of the fossa for the inferior vena 
 cava is the Spigelian lobe, which lies between the fissure for the vena cava and the 
 fissure for the ductus venosus. Below and in front it projects and forms part of the 
 posterior boundary of the transverse fissure. Here, to the right, it is connected 
 with the under surface of the right lobe of the liver by the caudate lobe, and to 
 the left it presents a tubercle, the tuberculum papillare (Fig. 938). It is opposite 
 the tenth and eleventh dorsal vertebrae, and rests upon the aorta and crura of the 
 Diaphragm, being covered by the peritoneum of the lesser sac. The lobe is 
 nearly vertical in position, and is directed backward; it is longer from above 
 downward than from side to side, and is somewhat concave in the transverse 
 direction. On the posterior surface to the left of the Spigelian lobe is a groove^ 
 the oesophageal groove (impressio oesophagea), indicating the position of the 
 abdominal portion of the oesophagus (Fig. 938). 
 
 Suprarenal 
 impression 
 {non-peritoneal), 
 
 Suprarenal 
 impression 
 (peritoneal). 
 Tuberculum 
 cav datum. 
 
 Tuberculum 
 papillare. 
 
 Umbilical fissure. Transverse fissure. 
 
 Fig. 938. — The liver. Posterior and inferior surfaces. (Drawn from His's models.) 
 
 Prof. Cunningham divides the liver into two surfaces, a visceral and a parietal, 
 and subdivides the parietal surface into a posterior area and superior area, an ante- 
 rior area and a right area. The parietal surface is separated from the visceral 
 surface by the inferior border or margin. 
 
 The inferior border or margin (margo inferioris) , posteriorly, is rather ill defined. 
 It is the lower margin of the posterior surface; it follows the line of rib and is in 
 contact with the right kidney. At the right side the lower margin is thick and 
 distinct, and, as a rule, projects slightly below the thorax. The front of the 
 inferior margin is called the anterior margin (margo anterior). It is a sharp edge 
 which, on inspiration, corresponds to an oblique line on the abdominal wall 
 drawn from "a point half an inch below the margin of the ribs (tip of tenth 
 costal cartilage), on the right side, to a point an inch below the nipple on the 
 left, and extending down in the middle line to a point half-way between the 
 gladiolus and the umbilicus."^ 
 
 In men the anterior margin of the liver often corresponds to the lower margin 
 of the ribs, but in women and children it is usually below the ribs in the line 
 
 ' Ambrose Birmingham, in Cunningham's Text-book of Anatomy. 
 
THE LIVER 
 
 1331 
 
 indicated above. Opposite the attachment of the falciform Hgament the anterior 
 border often exhibits a deep notch, the umbilical notch (incisura umhilicalis), 
 which is the anterior end of the fossa venae umbihcahs. Another notch, some- 
 times present, corresponds to the fundus of the gall-bladder, and is known as the 
 notch of the gall-bladder {incisura vesicae jelleae). 
 
 The left extremity of the inferior margin of the liver is thin and flattened from 
 above downward. The margin passes posteriorly around the free end of the left 
 lobe and terminates posteriorly at the oesophageal groove. 
 
 Fissures. — Five fissures are seen upon the under and posterior surfaces of the 
 liver, which serve to divide it into five lobes. They are: the umbilical fissure, 
 the fissure of the ductus venosus, the transverse fissure, the fissure for the gall-bladder, 
 and the fissure for the inferior vena cava. They are arranged in the form of the 
 letter H. The left limb of the H is known as the longitudinal fissure. The 
 right limb is formed in front by the fissure for the gall-bladder, and behind 
 by the fissure for the inferior vena cava; these two fissures are separated from 
 each other by the caudate lobe. The connecting bar of the H is the transverse or 
 portal fissure. It separates the quadrate lobe in front from the caudate and 
 Spigelian lobes behind. 
 
 (Esophageal groove. Portal vein. Suprarenal impression. 
 
 ,^{<0VE.RED By RIGHT LATERAL 
 
 LIGAMENTUM 
 TERES. 
 
 Hepatic artery. 
 
 Common bile-dtict. 
 Fig. 939. — Posterior and under surfaces of the liver. (From Ellis.) 
 
 The Longitudinal Fossa or Fissure (fossa longitudinalis sinistra). — The longi- 
 tudinal fissure is a deep groove, which extends from the notch on the anterior 
 margin of the liver to the upper border of the posterior surface of the organ. It 
 separates the right and left lobes; the Transverse Fissure (Fig. 938) joins it, at 
 right angles, and divides it into two parts. The anterior part is called the um- 
 bilical fossa or fissTure (fossa venae umhilicalis) (Fig. 938) ; it is deeper than the 
 posterior, and lodges the umbilical vein in the foetus, and its remains (the round 
 ligament) in the adult; the posterior part contains the ductus venosus, and is 
 known as the fissure of the ductus venosus. This fissure lies between the quadrate 
 lobe and the left lobe of the liver, and is often partially bridged over by a 
 prolongation of the hepatic substance, the pons hepatis. 
 
 The Fissure or Fossa of the Ductus Venosus (fossa ductus venosi) (Fig. 938) is 
 the back part of the longitudinal fissure, and is situated mainly on the posterior 
 surface of the liver. It lies between the left lobe and the lobe of Spigelius. It 
 
1332 THE ORGANS OF DIGESTION 
 
 lodges in the foetus the ductus venosus, and in the adult a slender fibrous cord, 
 the obliterated remains of that vessel. 
 
 The Transverse or Portal Fissure {"porta hepatis) (Fig. 938). — The transverse or 
 portal fissure is a short but deep fissure, about two inches in length, extending 
 transversely across the under surface of the left portion of the right lobe, nearer to 
 its posterior surface than its anterior border. It joins, nearly at right angles, with 
 the longitudinal fissure, and separates the quadrate lobe in front from the cau- 
 date and Spigelian lobes behind. By the older anatomists this fissure was con- 
 sidered the gateway (porta) of the liver; hence the large vein which enters at this 
 fissure was called the portal vein (Fig. 939). Besides this vein, the fissure trans- 
 mits the hepatic artery and nerves, and the hepatic duct and lymphatics. At 
 their entrance into the fissure, the hepatic duct lies in front and to the right, 
 the hepatic artery to the left, and the portal vein behind and between the duct 
 and artery. 
 
 The Fossa or Fissure for the Gall-bladder (fossa vesicae felleae). — The fossa or 
 fissure for the gall-bladder is a shallow, oblong fossa, placed on the under surface 
 of the right lobe, parallel with the longitudinal fissure. It extends from the 
 anterior free margin of the liver, which is notched for its reception, to the right 
 extremity of the transverse fissure. 
 
 The Fissure or Fossa for the Inferior Vena Cava (fossa venae cavae) (Fig. 938).— 
 The fissure or fossa for the inferior vena cava is a short, deep fissure, in some cases 
 a complete canal, in consequence of the substance of the liver occasionally sur- 
 rounding the vena cava. It extends obliquely upward from the lobus caudatus, 
 which separates it from the transverse fissure, on the posterior surface of the liver, 
 and separates the Spigelian from the right lobe. On slitting open the inferior 
 vena cava the orifices of the hepatic veins will be seen opening into this vessel at 
 its upper part, after perforating the floor of this fissure. 
 
 Lobes. — The lobes of the liver, like the ligaments and fissures, are five in 
 number — the right lobe, the left lobe, the lobus quadratus, the lobus Spigelii, and 
 the lobus caudatus, the last three being merely parts of the right lobe. 
 
 The Right Lobe (lobus hepatis dexter) (Figs. 936 and 938) . — The right lobe is 
 much larger than the left; the proportion between them being as six to one. It 
 occupies the right hypochondrium, and is separated from the left lobe, on its upper 
 and anterior surfaces by the falciform ligament; on its under and posterior surfaces 
 by the longitudinal fissure; and in front by the umbilical notch. It is of a some- 
 what quadrilateral form, its under and posterior surfaces being marked by three 
 fissures — the transverse fissure, the fissure for the gall-bladder, and the fissure for 
 the inferior vena cava, which separate its left part into three smaller lobes — the 
 lobus Spigelii, lobus quadratus, and lobus caudatus. On it are seen four shallow 
 impressions: one in front, for the hepatic flexure of the colon; a second behind, 
 for the right kidney; a third internal, between the last-named and the gall-bladder, 
 for the second part of the duodenum; and a fourth on its posterior surface, for the 
 suprarenal capsule. 
 
 The Lobus Quadratus or Square Lobe (Figs. 938 and 939) is situated on the 
 under surface of the right lobe, is bounded in front by the inferior margin of the 
 liver; behind, by the transverse fissure; on the right, by the fissure of the gall- 
 bladder; on the left, by the umbilical fissure. 
 
 The Lobus Spigelii (lobus caudatus [Spigeli]) (Figs. 938 and 939) is situated 
 upon the posterior surface of the right lobe of the liver. It looks directly back- 
 ward, and is nearly vertical in direction. It is bounded, above, by the upper layer 
 of the coronary ligament; below, by the transverse fissure; on the right, by the 
 fissure for the vena cava; and on the left, by the fissure for the ductus venosus. 
 Its left upper angle forms part of the groove for the oesophagus. What is here 
 called the lobus Spigelii, Spalteholz calls the lobus caudatus of Spigelius. 
 
THE LIVER 1333 
 
 The Lobus Caudatus or Tuberculum Caudatum (processus caudatus) (Fig. 938), or 
 tailed lobe, is a small elevation of the hepatic substance extending obliquely out- 
 ward, from the lower extremity of the Spigelian lobe to the under surface of the 
 right lobe. It is situated behind the transverse fissure, and separates the fissure 
 for the gall-bladder from the commencement of the fissure for the inferior vena 
 cava. What is here called the lobus caudatus, Spalteholz calls the processus 
 caudatus of the lobus caudatus of Spigelius. 
 
 The Left Lobe (lobus hepatis sinister) (Figs. 936 and 938). — The left lobe is 
 smaller and more flattened than the right. It is situated in the epigastric and 
 left hypochondriac regions. Its upper surface is slightly convex; its under sur- 
 face is concave, and presents a shallow depression for the stomach, the gastric 
 impression. This is situated in front of the groove for the oesophagus, and is 
 separated from the longitudinal fissure by the omental tuberosity, which lies against 
 the small omentum and lesser curvature of the stomach. The posterior end of 
 the left lobe frequently exhibits a flat projection, composed of connective tissue, 
 and called the appendix fibrosa hepatis. In the adult, portions only of bile-ducts 
 are present in it. In the newborn it is a definite portion of secreting liver substance, 
 which later undergoes connective-tissue transformation. 
 
 Ligaments. — The liver is connected to the under surface of the Diaphragm 
 and the anterior walls of the abdomen and the inferior vena cava by six ligaments, 
 four of which are peritoneal folds; the other two, which are the round ligament 
 and the ligament of the ductus venosus, are fibrous cords, resulting from the 
 obliteration of foetal vessels. These ligaments are the falciform, two lateral, 
 coronary, round, and the ligament of the ductus venosus. It is also attached to the 
 lesser curvature of the stomach by the gastro-hepatic or small omentum. 
 
 CORONARY ^ ii^fg^ , SPIGELIAN LEFT 
 
 LI<.AMENT^><C^ «ss^=SJ«^ffl!s'm_ tO,BE ""^LATERAL 
 
 LIGAMENT 
 
 RIGHT 
 LATERAL. 
 LIGAMENT 
 
 FALCIFORM 
 LIGAMENT 
 
 Fig. 940. — The peritoneal ligaments of the liver. (Schematic.) (Poirier and Charpy.) 
 
 The Falciform, Broad or Suspensory Ligament (ligamentum falciforme hepatis) 
 (Figs. 936, 940, and 941). — The falciform or suspensory Hgament is a broad and 
 thin antero-posterior peritoneal fold, falciform in shape, its base being directed 
 downward and backward, its apex upward and backward. It is attached by one 
 margin to the under surface of the Diaphram, and the posterior surface of the 
 sheath of the right Rectus muscle to within one inch of the umbilicus; by its 
 hepatic margin it extends from the notch on the anterior margin of the liver, as 
 far back as its posterior surface. 
 
 The free edge or base of the falciform ligament reaches from a little above and to 
 the right of the umbilicus to the umbilical fissure on the anterior margin of the liver. 
 This free edge contains between its folds the round ligament of the liver. On the 
 posterior surface of the liver the two peritoneal folds which constitute the falci- 
 form ligament separate, the right fold passing into the upper fold of the coronary 
 ligament, the left fold passing into the upper fold of the left lateral ligament. 
 
1334 
 
 THE ORGANS OF DIGESTION 
 
 The Lateral Ligaments (Figs. 936 and 940). — The lateral ligaments are two in 
 number, and are called the right and left lateral ligaments. 
 
 The Right Lateral Ligament (liganientum triancjulare dexirum) (Figs. 936 and 
 940) is in reality the right extremity of the coronary ligament. This ligament is 
 triangular in form, runs from the liver to the Diaphragm, and is formed by the 
 apposition of the upper and lower layers of the coronary ligament. It is 
 attached to the liver between its lateral and inferior surfaces. 
 
 The Left Lateral Ligament (ligamentum trlangulare sinistrum) (Figs. 936 and 
 940) is also formed by apposition of the upper and lower layers of the coronary 
 
 ligament. It is triangular in form. 
 
 runs 
 
 Fig. 941. — Diagram to show the relations o/ the falci- 
 form or suspensory and round ligaments to the liver and 
 the abdominal wall. (Gerrish.) 
 
 from the liver to the Dia- 
 phragm, and is longer than the right 
 lateral ligament. It is attached to 
 the upper surface of the left lobe, 
 where it lies, in front of the oesopha- 
 geal opening in the Diaphragm. 
 
 The Coronary Ligament {ligamentum 
 coronarium hepatis) (Figs. 936 and 
 940). — The coronary ligament con- 
 nects the posterior surface of the liver 
 to the Diaphragm. It is formed by 
 the reflection of the peritoneum from 
 the Diaphragm on to the upper and 
 lower margins of the posterior sur- 
 face of the liver. The coronary liga- 
 ment consists of two layers, which 
 are continuous on each side with the 
 lateral ligaments, and, in front, with 
 the falciform ligament. Between the layers a large triangular area is left un- 
 covered by peritoneum, and is connected to the Diaphragm by firm areolar tissue. 
 The Round Ligament {ligamentmn teres hepatis) (Figs. 939 and 941). — The 
 round hgament is a fibrous cord resulting from the obliteration of the foetal umbil- 
 ical vein. It ascends from the umbilicus, in the free margin of the falciform 
 ligament, to the notch in the anterior border of the liver, from which it may be 
 traced along the umbilical fissure on the under surface of the liver, to the left 
 branch of the portal vein. 
 
 The Ligament of the Ductus Venosus {ligamentum venosum [.4ranfi{]) is com- 
 posed of slender bundles of fibrous tissue, and results from the obliteration of the 
 ductus venosus of the foetus. It arises from the left branch of the portal vein, 
 almost opposite the insertion of the round ligament, passes backward in the fissure 
 of the ductus venosus, and, as it emerges from the liver, is attached to the vena cava. 
 Support and Movability of the Liver. — The liver is movable within certain 
 narrow limits. It moves with respiration. On inspiration it moves down with 
 the Diaphragm to distinctly below the costal arch in the right nipple line. 
 Much discussion has taken place as to what supports the liver in place. Syming- 
 ton asserted that the ligaments do not give support, because they lie relaxed. 
 Other observers (Graham, Steele) apparently demonstrate that the peritoneal 
 ligaments do give some support to the liver. The connective tissue which unites 
 the uncovered area of the right lobe of the liver to the Diaphragm and the hepatic 
 veins which join the vena cava (Faure) do give distinct support. The chief factor 
 in the support of the liver is the intra-abdominal pressure resulting from the 
 tonic contraction of the abdominal muscles. When abdominal tension is normal 
 the intestines are driven up and become a bed for the Uver. Intrahepatic vascular 
 tension aids in supporting the liver (Glenard). 
 
THE LIVER 
 
 1335 
 
 Abnormalities of the Liver. — The liver may be divided into many lobules, and 
 such lobulation is most evident on the parietal surface of the right lobe. I^obula- 
 tion is probably a pathological change. Occasionally the right lobe is small and 
 the left large. 
 
 The editor, in performing an abdominal operation, encountered a liver the 
 left lobe of which was so large and the right so small as to suggest transposition 
 or rotation of the organ. Such a change may result from abnormality of the 
 foetal circulation or from syphilitic disease of the right lobe, producing cicatricial 
 contraction.^ The left lobe may be very small; sometimes it is rudimentary. 
 When the left lobe is very small an unusual amount of stomach is visible, and the 
 entire gall-bladder can be seen from the front. In such a case the gall-bladder is 
 usually displaced and it may actually "lie with its long axis in the transverse axis 
 of the body."^' 
 
 DIAPHRAGMATIC 
 GROOVE 
 
 Fig. 942. — Deformed female liver. (Poirier and Charpy.) 
 
 Atrophy of the left lobe is usually a congenital defect, but may result from 
 syphilis. Small accessory lobes, about one inch in length, are not uncommon, and 
 they are most often met with on the visceral surface of the right lobe. "When 
 markedly pedunculated, they may form accessory livers. The Spigelian lobe is 
 sometimes curiously pedunculated."^ 
 
 Accessory livers are fragments of hepatic tissue or rests, which are entirely 
 separated from the liver. They are seldom met with. When they do exist their 
 mo.st common situation is in the suspensory ligament, but they have been found 
 in the great omentum, in the peritoneum, wall of the gall-bladder, and in other 
 situations. They may be congenital or may be due to atrophy of the pedicle of an 
 accessory lobe or of a pedunculated lobe. Tight lacing alters the shape and posi- 
 tion of the liver (Fig. 942). It may flatten the dome and increase the length of 
 the anterior surface, this change being especially obvious in the right lobe, and a 
 costal groove may be formed by the pressure of a rib. "When the elongated 
 right lobe passes over the right kidney, there is atrophy of the hepatic substance 
 
 1 H. D. RoUeston on Diseases of the Liver. 
 
 2 Ibid. 
 
 8 Ibid. 
 
1336 THE ORGANS OF DIGESTION 
 
 and thickening of the capsule, which is opaque and forms a hinge-Hke Hgament 
 between the main part of the right lobe above and the constricted lower portion. 
 This lobe is variously termed partial hepatoptosis, constriction lobe, or the sus- 
 tentacula! formation of the right lobe (Hertz). The constriction furrow is pro- 
 duced by the pressure of the corset in front and the resistance of the kidney 
 behind. The constriction lobe tapers to a point, so that the shape of the liver, as 
 seen from the front, is that of a right-angled triangle, with the apex downward."^ 
 The condition resembles Riedel's lobe. The left lobe may also project down, 
 but not so markedly. Tight lacing may cause the entire organ to occupy a level 
 higher than normal. Such a liver is thick and excessively convex above and 
 thin below, and reaches to or laps over the spleen. In severe cases the superior 
 surface is thrown into antero-posterior creases or folds. Linguiform or tongue-like 
 lobe, Riedel's lobe or floating lobe (Fig. 942), may be congenital, may be due to tight 
 lacing, or may arise in cholelithiasis or cholecystitis from the traction of adhesions. 
 Such a lobe comes off from the right lobe. It may be a tapering mass of liver 
 tissue, it may have a thin pedicle of liver tissue, or its pedicle may be merely a 
 double fold of peritoneum. The gall-bladder may lie upon its under surface, or 
 may be placed to the left of it. 
 
 Vessels. — ^The blood-vessels connected with the liver are the hepatic artery, the 
 portal vein and the hepatic veins. 
 
 Fig. 943. — Schematic section of the liver. The fibron tunic shown in black and tne capsule of Glisson in red. 
 
 The Hepatic Artery and Portal Vein (Figs. 418, 419, 489, and 944), accompanied 
 by numerous lymphatics and nerves, ascend to the transverse fissure between the 
 layers of the gastro-hepatic omentum, and in front of the foramen of Winslow. 
 The hepatic duct, lying in company with them, descends from the transverse fissure 
 between the layers of the same omentum. The relative position of the three 
 structures in the lesser omentum (Fig. 859) is as follows : the hepatic duct lies to 
 the right, the hepatic artery to the left, and the portal vein behind and between 
 the other two. They enter the transverse fissure in the above-described order, but 
 in that fissure undergo rearrangement, the duct being in front, the artery in the 
 middle, and the vein behind. The artery, the vein, and the duct divide into a 
 right and left branch and several smaller branches, and within the organ the 
 vessels from the three sources accompany each other and divide at the same 
 points; so each branch of the portal vein is accompanied by a branch of the 
 hepatic artery and of the duct. They are enveloped in a loose areolar tissue, the 
 capsule of Glisson (Fig. 943) , which accompanies the vessels in their course through 
 the 'portal canals in the interior of the organ. 
 
 The Hepatic Veins (Fig. 421).— The hepatic veins convey the blood from the liver. 
 They commence in the substance of the Hver, in the capillary terminations of the por- 
 tal vein and hepatic artery; these tributaries, gradually uniting, usually form three 
 
 1 Rolleston, on Diseases of the Liver. 
 
THE LIVER 
 
 1337 
 
 veins, which converge toward the posterior surface of the liver and open into the 
 portion of the inferior vena cava situated in the groove at the back part of 
 this organ. Of these three veins, one from the right and another from the left 
 lobe open obliquely into the vena cava; that from the middle of the organ and 
 lobus Spigelii having a straight course. 
 
 The hepatic veins have very little cellular investment; what there is binds their 
 parietes closely to the walls of the canals through which they run; so that, on 
 section of the organ, these veins remain widely open and solitary (Fig. 946), 
 and may be easily distinguished from the branches of the portal vein (Fig. 947), 
 which are more or less collapsed, and always accompanied by an artery and duct. 
 The hepatic veins are destitute of valves. 
 
 Structure. — The substance of the liver is composed of lobules held together by 
 extremely fine areolar tissue, and of the ramifications of the portal vein, hepatic 
 duct, hepatic artery, hepatic veins, lymphatics, and nerves, the whole being 
 invested by a serous and a fibrous coat. 
 
 COMMON DUCT 
 
 FORAMEN OF 
 WINSLOW 
 
 DUODENUM 
 
 Fig. 944. — The relations of the vessels as they pass into the transverse fissure of the liver. (Poirier and Charpy.) 
 
 The Serous Coat {tunica serosa). — The serous coat is derived from the perito- 
 neum, and invests the greater part of the surface of the organ. It is intimately 
 adherent to the fibrous coat. 
 
 The Areolar or Fibrous Coat {capsula fibrosa [Glissoni]). — The areolar or fibrous 
 coat lies beneath the serous investment and covers the entire surface of the organ. 
 It is difficult of demonstration, excepting where the serous coat is deficient. At 
 the transverse fissure it is thick and evident, is known as the capsule of Glisson, 
 and envelops the vessels which enter the liver and passes with them along the 
 portal canals. The areolar tissue which surrounds and binds together the liver 
 lobules is continuous with the areolar coat. 
 
 The Lobules (lobuli hepatis) (Fig. 049). — The lobules form the chief mass of 
 the hepatic substance ; they may be seen either on the surface of the organ or by 
 making a section through the gland. They are small granular bodies about the size 
 of a millet-seed, measuring from one-twentieth to one-tenth of an inch in diameter. 
 In the human subject their outline is very irregular, but in some of the lower 
 
1338 
 
 THE OBGANS OF DIGESTION 
 
 animals (for example, the pig) they are well defined, and when divided transversely 
 have a polygonal outline. If divided longitudinally they are more or less foliated 
 or oblong. The bases of the lobules are clustered around the smallest radicles 
 of the hepatic veins (sublobular veins), to which each is connected by means of a 
 small branch which issues from the centre of the lobule (intralobular vein). The 
 remaining part of the surface of each lobule is imperfectly isolated from the sur- 
 rounding lobules by a thin stratum of areolar tissue in which are ducts and a plexus 
 of vessels, the interlobular plexus (Figs. 948 and 949) . In some animals, as the 
 pig, the lobules are completely isolated one from another by this interlobular areolar 
 tissue. 
 
 If one of the sublobular veins be laid open, the bases of the lobules may be 
 seen through the thin wall of the vein on which they rest, arranged in the form 
 of a tessellated pavement, the centre of each polygonal space presenting a minute 
 aperture, the mouth of an intralobular vein (Fig. 946). 
 
 Microscopic Appearance. — Each lobule is composed of a mass of cells, hepatic 
 cells (Fig. 945) , surrounded by a dense capillary plexus, composed of vessels which 
 
 ABC C 
 
 Fig. 945. — The hepatic cells at different stages of digestion. (Heidenhain.) 
 
 penetrate from the circumference to the centre of the lobule, and terminate in a 
 single straight central vein, which runs through its centre, to open at its base into 
 one of the radicles of the hepatic vein. Between the cells are also the minute com- 
 mencements of the bile-ducts. Therefore in the lobule we have all the essentials of 
 a secreting gland; that is to say: (1) cells, by which the secretion is formed; (2) 
 blood-vessels, in close relation with the cells, containing the blood from which 
 the secretion is derived; and (3) ducts, by which the secretion, when formed, is 
 carried away. Each of these structures will have to be further considered. 
 
 (1) The Hepatic Cells are epithelial in nature and of more or less spheroidal form, 
 but may be rounded, flattened, or many-sided from mutual compression. They 
 vary in size from the ywot ^^ ^^e yoVo" ^^ ^^ ^^^^ ^^ diameter. They consist of a 
 honeycomb network (Klein) without any cell-wall, and contain one or sometimes 
 two distinct nuclei. In the nucleus is a highly refracting nucleolus with granules. 
 Embedded in the honeycomb network are numerous yellow particles, the coloring 
 matter of the bile, and oil-globules. The cells adhere together by their surfaces so 
 as to form rows, which radiate from the centre to the circumference of the lobules.* 
 As stated above, they are the chief agents in the secretion of the bile. 
 
 (2) The Blood-vessels. — ^The blood in the capillary plexus around the liver-cells 
 is brought to the liver principally by the portal vein, but also to a certain extent 
 by the hepatic artery. For the sake of clearness the distribution of the blood 
 derived from the hepatic artery may be considered first. 
 
 The Hepatic Artery, entering the liver at the transverse fissure with the portal 
 vein and hepatic duct, ramifies with these vessels through the portal canals. It 
 gives off vaginal branches which ramify in the capsule of Glisson, and appear to 
 be destined chiefly for the nutrition of the coats of the large vessels, the ducts, 
 
 ' Del6pine states that there are evidences of the arrangement of these cells in the form of columns, which 
 form tubes with narrow lumina branching from terminal bile-ducts. This branching is evidenced by a diverg- 
 ence of the columns from lines extending between adjacent portal vessels. The columns of cells group around 
 terminal bile-ducts, and not around the so-called intralobular veins. (Lancet, 1895, vol. i. p. 1254.) — Ed. of 15tn 
 English edition. 
 
THE LIVER 
 
 1339 
 
 and the investing membranes of the Hver. It also gives off capsular branches 
 which reach the surface of the organ, terminating in the fibrous coat in stellate 
 plexuses. Finally it gives off interlobular branches {rami arteriosi interlohulares) 
 which form a plexus on the outer side of each lobule, to supply its wall and the 
 accompanying bile-ducts. From this plexus lobular branches enter the lobule 
 
 Hepatic 
 
 Portal vein. 
 
 Orifices of intralohidar reins. 
 
 Fig. 946. — Longitudinal section of an hepatic 
 vein. (After Kiernan.) 
 
 Portion of 
 
 canal from 
 
 which vein 
 
 has been 
 
 removed- 
 
 Fig. 947. — Longitudinal section of a small portal 
 vein and canal. (After Kiernan.) 
 
 and end in the capillary network between the cells. Some anatomists, however, 
 doubt whether it transmits any blood directly to the capillary network. 
 
 The Portal Vein also enters at the transverse fissure and runs through the 
 portal canals, enclosed in Glisson's capsule, dividing into branches in its course. 
 
 Intralobular vein. 
 
 Trunk of intralobulctr 
 vein. 
 
 Fig. 948. — Horizontal section of liver (dog.) 
 
 which finally break up into a plexus, the interlobular plexus, in the interlobular 
 spaces. In their course these branches receive the vaginal and capsular veins, 
 corresponding to the vaginal and capsular branches of the hepatic artery (Fig. 
 947). Thus it will be seen that all the blood carried to the liver by the portal vein 
 and hepatic artery, except perhaps that derived from the interlobular branches of 
 
1340 
 
 THE ORGANS OF DIGESTION 
 
 the hepatic artery, directly or indirectly finds its way into the interlobular plexus. 
 From this plexus the blood is carried into the lobule by fine branches which pierce 
 its wall and then converge from the circumference to the centre of the lobule, form- 
 
 FiQ. 949. — Horizontal section of a liver lobule. 1, central vein ; 2, converging vessels ; 3, interlobular plexus. 
 
 (Poirier and Charpy.) 
 
 ing a number of converging vessels which are connected by transverse branches 
 (Figs. 948 and 949). In the interstices of the network of vessels thus formed are 
 situated, as before said, the liver-cells : and here it is that the blood is brought into 
 
 Fig. 950. — X-ray picture of the bile-ducts and the pancreatic ducts. (Byron Robinson.) 
 
 intimate connection with the liver-cells and the bile is secreted. Arrived at the 
 centre of a lobule, all these minute vessels empty themselves into one vein, of 
 considerable size, which runs down the centre of the lobule from apex to base 
 and is called the intralobulax or central vein {vena interlobularis) (Fig. 949) . At the 
 
THE LIVER 
 
 1341 
 
 base of the lobule this vein opens directly into the sublobulax vein, with which the 
 lobule is connected, and which, as before mentioned, is a radicle of the hepatic vein. 
 The sublobular veins, uniting into larger and larger trunks, end at last in the hepatic 
 veins, which do not receive any intralobular veins. Finally, the hepatic veins, as 
 mentioned on page 767, converge to form three large trunks which open into the 
 inferior vena cava, while that vessel is situated in the fissure appropriated to it 
 at the back of the liver. 
 
 (3) The Ducts. — Having shown how the blood is brought into intimate relation 
 with the hepatic cells in order that the bile may be secreted, it remains now only 
 to consider the way in which the secretion, having been formed, is carried away. 
 Several views have prevailed as to the mode of origin of the hepatic ducts; it 
 seems, however, to be clear that they commence by little passages which are 
 formed between the cells, and which have been termed intercellular biliary pass- 
 ages, bile-capillaries or bile-canaliculi {ductus biliferi). These passages are merely 
 little channels or spaces left between the contiguous surfaces of two cells or in the 
 
 Biliary 
 duct. 
 
 Hepatic 
 cells. 
 
 Capillary. 
 
 Fio. 951. — Section of liver. 
 
 Bili 
 
 Fig. 952. — A transverse section of a small portal canal 
 and its vessels. 1, portal vein ; 2, interlobular branches; 
 3, vaginal branches ; 4, hepatic duct ; 5, hepatic artery. 
 (After Kiernan.) 
 
 angle where three or more liver-cells meet (Fig. 951), and it seems doubtful 
 whether there is any delicate membrane forming the wall of the channel. 
 Heidenhain, however, thinks they have coats. The channels thus formed radi- 
 ate to the circumference of the lobule, and, piercing its wall, form a plexus 
 (interlobular) between the lobules. From this plexus interlobular ducts (ductus 
 interlobular es) are derived which pass into the portal canals, become enclosed in 
 Glisson's capsule, and, accompanying the portal vein and hepatic artery (Fig. 
 952), join with other ducts to form two main trunks, the right and left branches of 
 the hepatic duct, which leave the liver at the transverse fissure, and by their union 
 form the hepatic duct. 
 
 Structure. — The coats of the smallest biliary ducts, which He in the inter- 
 lobular spaces, are a connective-tissue coat, in which are muscle-cells, arranged 
 both circularly and longitudinally, and an epithelial layer, consisting of short 
 columnar cells. In the larger ducts, which lie in the portal canals, there are a 
 number of orifices disposed in two longitudinal rows, which were formerly regarded 
 as the openings of mucous glands, but which are merely the orifices of tubular 
 recesses. They occasionally anastomose, and from the sides of them saccular 
 dilatations are given off. 
 
 Lsrmphatics of the Liver (Fig. 506) . — The lymphatics in the substance of the liver 
 commence in lymphatic spaces around the capillaries of the lobules ; they accompany 
 
1342 THE ORGANS OF DIGESTION 
 
 the vessels of the interlobular plexus, often enclosing and surrounding thera. 
 These unite and form larger vessels, which run in the portal canals, enclosed in 
 Glisson's capsule, and emerge at the portal fissure to be distributed in the manner 
 described. Other superficial lymphatics arise from the superficial lobules, pass 
 under the peritoneum, and form a close plexus, where this membrane covers 
 the liver. The first-named group of lymphatics give origin to the deep collecting 
 trunks, the second to the superficial collecting trunks. According to Poirier, 
 Cuneo and Delamare,^ one group of deep collecting trunks accompanies the portal 
 vein, there being fifteen to eighteen of them emerging from the transverse fissure. 
 They empty into the glands of the hilum. Another group accompanies the hepatic 
 veins. There are five or six trunks which pass through the Diaphragm and ter- 
 minate in the glands about the vena cava {intrathoracic glands). According to the 
 above-cited authorities, the superficial trunks of the superior surface are divided 
 into posterior, anterior, and superior trunks. Some of the posterior trunks ter- 
 minate in the glands about the coeliac axis, others in the glands about the lower 
 portion of the vena cava in the thorax; others in the glands about the abdominal 
 portion of the oesophagus. The anterior trunks which are limited to the right 
 lobe pass to the glands of the hilum. The superior trunks ascend in the suspen- 
 sory ligament. Some pass to the glands about the vena cava, just above the 
 Diaphragm; others to the hepatic glands. The balance unite to form a very large 
 trunk, which passes through the Diaphragm and divides into branches which enter 
 the glands back of the base of the ensiform cartilage. 
 
 Nerves of the Liver. — The nerves of the liver are derived from the left pneumo- 
 gastric and the solar plexus of the sympathetic. The branches of the pneumo- 
 gastric ascend from in front of the stomach within the lesser omentum. The 
 sympathetic nerves pass along the hepatic artery from the coeliac plexus. The 
 nerves enter the liver at the transverse fissure and accompany the vessels and 
 ducts to the interlobular spaces. Here, according to Korolkow, the medullated 
 fibres are distributed almost exclusively to the coats of the blood-vessels; while 
 the non-medullated fibres enter the lobules and ramify between the cells. 
 
 The Excretory Apparatus of the Liver. 
 
 The excretory apparatus of the liver consists of (1) the hepatic duct, which, 
 as we have seen, is formed by the junction of the two main ducts, which pass 
 out of the liver at the transverse fissure, and are formed by the union of the bile- 
 capillaries; (2) the gall-bladder, which serves as a reservoir for the bile; (3) the 
 cystic duct, which is the duct of the gall-bladder; and (4) the common bile-duct, 
 formed by the junction of the hepatic and cystic ducts. 
 
 The Hepatic Duct (ductus hepaticus) (Figs. 953, 954, and 956). — Two main 
 trunks of nearly equal size issue from the liver at the transverse fissure, one from 
 the right, the other from the left lobe ; these unite to form the hepatic duct, which 
 then passes downward and to the right for about an inch and a half or two 
 inches, between the layers of the lesser omentum, where it is joined at an acute 
 angle by the cystic duct, and so forms the ductus communis choledochus. The 
 hepatic duct, as it descends from the transverse fissure of the liver, between the 
 two layers of the lesser omentum, lies in company with the hepatic artery and 
 portal vein (Fig. 944). 
 
 The Gall-bladder (vesica fellea) (Figs. 859, 861, 938, 944, and 953).— The 
 gall-bladder is the reservoir for the bile; it is a conical or pear-shaped musculo- 
 membranous sac, lodged in a fossa on the under surface of the right lobe of the 
 liver, and fixed in it by connective tissue, and extending from near the right 
 extremity of the transverse fissure to the anterior border of the organ. It is 
 
 1 The Lymphatics. Translated and edited by Cecil H. Leaf. 
 
THE EXCRETORY APPARATUS OF THE LIVER 
 
 1343 
 
 about four inches in length, one inch in breadth at its widest part, and holds from 
 eight to ten drachms. It is divided into a fundus, body, and neck. The fundus 
 {fundus vesicae felleae), or broad extremity, is 
 directed downward, forward, and to the right, 
 and projects beyond the anterior border of the 
 liver; the body (corpus vesicae felleae) and neck 
 (collum vesicae felleae) are directed upward and 
 backward to the left. The neck of the gall- 
 bladder is on a slightly higher level than the 
 lowest point of the gall-bladder; thus the weight 
 of the bile is away from rather than toward 
 the outlet. The upper surface of the gall- 
 bladder is attached to the liver by connective 
 tissue and vessels. The under surface is 
 covered by peritoneum, which is reflected on to 
 it from the surface of the liver. Occasionally 
 the whole of the organ is invested by the ser- 
 ous membrane, and is then connected to the 
 liver by a kind of mesentery. 
 
 Relations. — The body of the gall-bladder is 
 in relation, by its upper surface, with the 
 liver, to which it is connected by areolar tissue 
 and vessels ; by its under surface, with the 
 commencement of the transverse colon ; and 
 farther back, with the upper end of the de- 
 scending portion of the duodenum or some- 
 times with the pyloric end of the stomach or 
 the first portion of the duodenum. The fundus 
 is completely invested by peritoneum ; it is in 
 relation, in front, with the abdominal parietes, 
 immediately below the ninth costal cartilage; Fig. 953.— The gaii-biadder and bUe-ducts, 
 
 , , . , .^% ., . 1 p ,1 1 cut through. (Spalteholz.) 
 
 behmd, witn the transverse arch 01 the colon. 
 
 The neck is narrow, and curves upon itself like the letter S; at its point of 
 
 connection with the cystic duct it presents a well-marked constriction. 
 
 When the gall-bladder is distended with bile or filled with calculi, the fundus may be felt 
 through the abdominal parietes, especially in an emaciated subject; the relations of this sac will 
 also serve to explain the occasional occurrence of abdominal biliary fistulae, through which biliary 
 calculi may pass out, and of the passage of calculi from the gall-bladder into the stomach, duod- 
 enum, or colon, which occasionally happens. 
 
 Structure. — The gall-bladder consists of three coats — serous, fibrous and mus- 
 cular, and mucous. 
 
 The External or Serous Coat (tunica serosa vesicae felleae) is derived from the peri- 
 toneum; it completely invests the fundus, but covers the body and neck only on 
 their under surfaces. 
 
 The Fibro -muscular Coat (tunica muscularis vesicae felleae) is a thin but strong 
 layer which forms the framework of the sac, consisting of dense fibrous tissue which 
 interlaces in all directions and is mixed with plain muscular fibres which are dis- 
 posed chiefly in a longitudinal direction, a few running transversely. 
 
 The Internal or Mucous Coat (tunica mucosa vesicae felleae) is loosely connected 
 with the fibrous layer. It is generally tinged with a yellowish-brown color, and 
 is everywhere elevated into minute rugae, by the union of which numerous meshes 
 are formed, the depressed intervening spaces having a polygonal outline. The 
 meshes are smaller at the fundus and neck, being most developed about the centre 
 
 k 
 
1344 
 
 THE ORGANS OF DIGESTION 
 
 of the sac. Opposite the neck of the gall-bladder the mucous membrane projects 
 inward in the form of oblique ridges or folds, forming a sort of screw-like or s'pirul 
 valve (Fig. 953). 
 
 The mucous membrane is covered with columnar epithelium, and secretes an 
 abundance of thick viscid mucus; it is continuous through the hepatic duct with 
 the mucous membrane lining the ducts of the liver, and through the ductus com- 
 munis choledochus with the mucous membrane of the duodenum. 
 
 The Cystic Duct (ductus cysticus). — The cystic duct, the smallest of the three 
 biliary ducts, is about an inch and a half in length. It passes obliquely downward 
 and to the left from the neck of the gall-bladder, and joins the hepatic duct to form 
 the common bile-duct. It lies in the gastro-hepatic omentum in front of the portal 
 
 HEPATIC 
 DUCT 
 
 DUCT OF 
 WIRSUNG 
 
 SPHINCTER OF 
 DUCT OF WIRSUNG 
 
 COMMON 
 DUCT 
 
 SPHINCTER OF 
 COMMON DUCT 
 
 Fig. 955. 
 
 -The sphincter of the common bile-duct. 
 (Poirier and Charpy.) 
 
 PANCREATIC 
 OUCT 
 
 AMPULLA 
 OF VATER 
 
 WALL OF 
 DUODENUM 
 
 vein, the hepatic artery lying to its left 
 side. The mucous membrane lining its in- 
 terior is thrown into a series of crescentic 
 folds, from five to twelve in number, similar 
 to those found in the neck of the gall-blad- 
 der. They project into the duct in regular 
 succession, and are directed obliquely round 
 the tube, presenting much the appearance 
 of a continuous spiral valve {valvula spiralis 
 [Heisteri]) (Fig. 953). When the duct is 
 distended, the spaces between the folds 
 are dilated, so as to give to its exterior 
 a sacculated appearance. 
 
 The Ductus Communis Choledochus or 
 Common Bile-duct (ductus choledochus) 
 Figs. 953 and 954) , the largest of the three, 
 is the common excretory duct of the liver and gall-bladder. It is about three 
 inches in length, is of the diameter of a goose-quill, and is formed by the junction 
 of the cystic and hepatic ducts. 
 
 It descends within the two layers and along the right border of the lesser omen- 
 tum behind the first portion the duodenum, in front of the portal vein, and to the 
 right of the hepatic artery (Fig. 859) ; then passes either between the pancreas 
 and descending portion of the duodenum, or through the head of the pancreas. 
 In fifty-eight dissections Prof. Biingner found that it passed through the pan- 
 creas fifty-five times and over the head only three times. Even when it passes 
 through the pancreas it almost always joins the pancreatic duct outside of the 
 gland. It descends by the right side of the pancreatic duct and passes with it 
 obliquely through the wall of the descending portion of the duodenum between 
 the mucous and muscular coats in the submucous tissue for one-half to three- 
 
 FiG. 954. — The biliary ducts. Schematic. 
 (Poirier and Charpy.) 
 
THE EXCRETORY APPARATUS OF THE LIVER 1345 
 
 quarters of an inch. The two ducts usually unite just before opening into the 
 duodenum (Figs. 954, 955, and 957), but may remain independent throughout. 
 The ampulla of Vater (Fig. 954) is the cavity formed by the fusion of the two 
 ducts, and is much larger than the opening on the bile-papilla. The two ducts 
 open by a common orifice, or by two separate orifices, upon the summit of a papilla, 
 situated at the inner side of the descending portion of the duodenum, a little 
 below its middle and about three or four inches below the pylorus. The muscle 
 of the common duct has a certain amount of sphincter power (Fig. 955), which 
 serves to prevent the entrance of duodenal contents through the small aperture, 
 but is not sufficiently powerful to prevent the flow of bile and pancreatic juice. 
 Structure. — The coats of the large biliary ducts are an external or fibrous and 
 an?intemal or mucous. The fibrous coat is composed of strong fibro-areolar tissues, 
 
 CIRCULAR 
 MUSCULAR 
 FIBRES 
 MUCOUS 
 COAT 
 
 LONGITUDINAL 
 MUSCULAR FIBRES 
 
 ACCESSORY 
 
 PANCREATIC 
 
 DUCTS 
 
 BILE-DUCT 
 
 PANCREATIC 
 DUCT 
 
 Fig. 957. — Diagram showing the bile and 
 pancreatic ducts piercing the wall of the 
 duodenum obliquely. (Cunningham.) 
 
 with a certain amount of mus- 
 cular tissue arranged, for the 
 most part, in a circular manner 
 around the duct. The mucous 
 coat is continuous with the lin- 
 ing membrane of the hepatic 
 ducts and gall-bladder, and 
 also with that of the duodenum ; 
 and, like the mucous membrane 
 of these structures, its epithe- 
 lium is of the columnar variety. 
 It is provided with numerous 
 mucous glands, which are lobu- 
 lated and open by minute orifices scattered irregularly in the larger ducts. It is 
 questionable if the smallest biUary ducts, which lie in the interlobular spaces, have 
 any coats. Heidenhain thinks they have a connective-tissue coat, in which are 
 muscle-cells arranged both circularly and longitudinally, and an epithelial layer, 
 consisting of short columnar cells. 
 
 Dimensions of the Bile-ducts. — ^The hepatic duct is about two inches in length, 
 and its lumen is one-sixth of an inch in diameter. The cystic duct is about one 
 and one-half inches in length, and its lumen one-twelfth of an inch in diameter. 
 The common duct is about three inches in length, and its lumen is one-quarter of 
 an inch in diameter. The duodenal opening is smaller than the common duct. 
 The ducts are capable of considerable distention, but the duodenal opening can- 
 not be dilated (HyrtH. 
 
 85 
 
 Fig. 956. — Part of the bile-duct and the pancreatic ducts. C 
 and B, calculi; Sa, Santorini's duct; P, pancreatic duct; III and 
 I V, ducts from the right and left lobes of the liver; //, cystic duct; 
 C, gall-bladder; .,4, common duct. (Byron Robinson.) 
 
1346 
 
 THE ORGANS OF DIGESTION 
 
 Blood-vessels, Lymphatics and Nerves of the Gall-bladder and Bile-ducts. — The cystic 
 artery (Fig. 418), a branch from the right division of the hepatic, supphes the gall- 
 bladder and cystic duct with blood. It passes along the cystic duct, and on reach- 
 ing the gall-bladder divides into an upper branch and a lower branch. The upper 
 branch lies between the gall-bladder and the liver and sends branches to each. 
 The lower branch is between the peritoneum and the wall of the gall-bladder. 
 The cystic veins empty into the portal vein. The common duct receives branches 
 from the superior pancreatico -duodenal artery. There is a submucous lymphatic net- 
 work and a muscular lymphatic network. The lymphatics are much less numer- 
 ous at the fundus of the gall-bladder than at the neck or in the extra-hepatic ducts. 
 The collecting trunks (Fig. 506) end in glands along the cystic and common ducts, 
 and these glands are in communication with the duodenal lymphatics and the 
 lymphatics from the head of the pancreas. The nerves of the gall-bladder and 
 bile-ducts come from the coeliac plexus of the sympathetic. The adjacent peri- 
 toneum is plentifully supplied with nerves (Byron Robinson). 
 
 The Bile {]el) . — The bile is a reddish-brown or greenish fluid. It contains pig- 
 ments (bilirubin and biliverdin), fats and soaps, cholesterin, sodium salts of glyco- 
 cholic and taurochohc acid, lecithin, and nucleo-albumin furnished by the mucous 
 membrane. There are also present COg; chlorides, carbonates, phosphates, and 
 sulphates of the alkalies and of calcium, and iron. The amount normally 
 secreted is from one pint to one and one-half pints in the twenty-four hours. 
 
 Siuface Relations. — The liver is situated in the right hypochondriac and the epigastric 
 regions, and is moulded to the arch of the Diaphragm. In the greater part of its extent it lies 
 under cover of the lower ribs and their cartilages, but in the epigastric region it comes in con- 
 tact with the abdominal wall, in the subcostal angle. The upper limit of the right lobe of the 
 liver may be defined in the middle line by the junction of the mesosternum with the ensiform 
 cartilage; on the right side the line must be carried upward as far as the fifth rib cartilage 
 in the line of the nipple and then downward to reach the seventh rib at the side of the chest. 
 The upper limit of the left lobe may be defined by continuing this line to the left with an inclina- 
 tion downward to a point about two inches to the left of the sternum on a level with the sixth 
 left costal cartilage. The lower limit of the liver may be indicated by a line drawn half an inch 
 below the lower border of the thorax on the right side as far as the ninth right costal cartilage, 
 and thence obliquely upward across the subcostal angle to the eighth left costal cartilage. A 
 slight curved line with its convexity to the left from this point — i. e., the eighth left costal 
 cartilage — to the termination of the line indicating the upper limit will denote the left margin of 
 the liver. The fundus of the gall-bladder approaches the surface behind the anterior extremity 
 of the ninth costal cartilage, close to the outer margin of the Right rectus muscle. 
 
 It must be remembered that the liver is subject to considerable alterations in position, and 
 the student should make himself acquainted with the different circumstances. under which this 
 occurs, as they are of importance in determining the existence of enlargement or other diseases 
 of the organ. 
 
 Its position varies according to the posture of the body. In the erect position in the adult 
 male the edge of the liver projects about half an inch below the lower edge of the right costal 
 cartilages, and its anterior border can be often felt in this situation if the abdominal wall is thin. 
 In the supine position the Hver gravitates backward and recedes above the lower margin of the 
 ribs, and cannot then be detected by the finger. In the prone position it falls forward, and can 
 then generally be felt in a patient with loose and lax abdominal walls. Its position varies also 
 with the ascent or descent of the Diaphragm. In a deep inspiration the liver descends below 
 the ribs; in expiration it is raised behind them. Again, in emphysema, where the lungs are 
 distended and the Diaphragm descends very low, the liver is pushed down; in some other dis- 
 eases, as phthisis, where the Diaphragm is much arched, the liver rises very high up. Pressure 
 from without, as in tight lacing, by compressing the lower part of the chest, displaces the liver 
 considerably, its anterior edge often extending as low as the crest of the ilium; and its convex 
 surface is often at the same time deeply indented from the pressure of the ribs. Again, its posi- 
 tion varies greatly according to the greater or less distention of the stomach and intestines. 
 When the intestines are empty the liver descends in the abdomen, but when they are distended 
 it is pushed upward. Its relations to surrounding organs may also be changed by the growth of 
 tumors or by collections of fluid in the thoracic or abdominal cavities. 
 
 Surgical Anatomy. — Movable liver or hepatopfosis is a rare condition, in which the liver 
 moves or can be moved from its normal position. It is due to lessened tone of the abdominal 
 
THE EXCRETORY APPARATUS OF THE LIVER 1347 
 
 muscles and relaxation of the liver supports. In movable liver the organ may be rotated on its 
 vertical axis or on its transverse axis. Tongue-like lobes have been referred to. On account of 
 its large size, its fixed position, and its friability, the liver is more frequently ruptured than 
 any of the abdominal viscera. The rupture may vary considerably in extent, from a slight 
 scratch to an extensive laceration completely through its substance, dividing it into two parts. 
 Sometimes an internal rupture without laceration of the peritoneal covering takes place, and 
 such injuries are most susceptible of repair; but small tears of the surface may also heal; when, 
 however, the laceration is extensive, death usually takes place from hemorrhage, on account 
 of the fact that the hepatic veins are contained in rigid canals in the liver-substance and are 
 unable to contract, and are moreover unprovided with valves. The liver may also be torn 
 by the end of a broken rib perforating the Diaphragm. The liver may be injured by stabs 
 or other punctured wounds, and when these are inflicted through the chest-wall both pleural 
 and peritoneal cavities may be opened up and both lung and liver be wounded. In cases of 
 wound of the liver from the front, jirotrusion of a part of this viscus may take place, but can gen- 
 erally easily be replaced. In cases of laceration of the liver, when there is evidence that bleeding 
 is going on, the abdomen must be opened, the laceration sought for, and the bleeding arrested. 
 This may be done temporarily by introducing the forefinger into the foramen of Winslow and 
 placing the thumb on the gastro-hepatic omentum and compressing the hepatic artery and portal 
 vein between the two. Any bleeding points can then be seen. Bleeding is, if possible, arrested 
 by suture ligatures. The edges of a small laceration are simply brought together and sutured by 
 means of a blunt, curved, round needle passed from one side of the wound to the other. All sutures 
 must be passed before any are tied, and this must be done with the greatest gentleness, as the liver 
 substance is very friable. If suture fails the actual cautery may succeed. When the laceration is ex- 
 tensive, the liver is sutured to the abdominal wall to hold it firm when pressure is applied, and then 
 the laceration is packed with a piece of iodoform gauze, the end of which is allowed to hang out 
 of the external wound. Abscess of the liver is of not infrequent occurrence, and may open in many 
 different ways on account of the relations of this viscus to other organs. Thus it may burst into 
 the lung, the pus being coughed up, or into the stomach; the pus perhaps being vomited, it may 
 burst into the colon or into the duodenum, or, by perforating the Diaphragm, it may empty 
 itself into the pleural cavity. Frequently it makes its way forward, and points on the anterior 
 abdominal wall, and finally it may burst into the peritoneal or pericardiac cavity. Abscesses 
 of the liver require opening, and this must be done by an incision in the abdominal wall, in the 
 thoracic wall, or in the lumbar region, according to the direction in which the abscess is tracking. 
 The incision through the abdominal wall is to be preferred when possible. The abdominal wall 
 is incised over the swelling, and unless the peritoneum is adherent, gauze is packed all around 
 the exposed liver surface and the abscess opened, if deeply seated, preferably by the thermo- 
 cautery. Hydatid cysts are more often found in the liver than in any other of the viscera. The 
 reason of this is not far to seek. The embryo of the egg of the taenia echinococcus being liberated 
 in the stomach by the disintegration of its shell, bores its way through the gastric walls and 
 usually enters a blood-vessel, and is carried by the blood-stream to the hepatic capillaries, where 
 its onward course is arrested, and where it undergoes development into the fully formed hydatid. 
 Tumors of the liver have recently been subjected to surgical treatment by removal of a portion 
 of the organ. The abdomen is opened and the diseased portion of liver exposed; the circulation 
 is controlled by compressing the portal vein and the hepatic artery in the gastro-hepatic omen- 
 tum and a wedge-shaped portion of liver containing the tumor removed; the divided vessels 
 are ligated and the cut surfaces brought together and sutured in the manner directed above. 
 
 when the r/all-bladder or one of its main ducts is ruptured, which may occur independently 
 of laceration of the liver, death usually occurs from peritonitis. If the symptoms have led to 
 the performance of a laparotomy and a small rent is found, it should be sutured; if an exten- 
 sive opening is found the gall-bladder should be removed. If the cystic duct is torn, its intes- 
 tinal end must be closed and the gall-bladder removed. In rupture of either of the other 
 ducts, sim]ily provide for free drainage. 
 
 The gall-bladder may become distended with bile in cases of obstruction of its duct or of the 
 common bile-duct, or it may become distended from a collection of gall-stones within its interior, 
 thus forming a large tumor. The swelling due to distention with bile is pear-shaped, and pro- 
 jects downward and forward to the umbilicus. It moves with respiration, since it is attached to 
 the liver. To relieve a ]>atient of gall-stones, the gall-bladder must be opened and the gall-stones 
 removed. The operation is performed by an incision two or three inches long in the right semi- 
 lunar line, commencing at the costal margin. The peritoneal cavity is opened, and, the tumor 
 having been found, gauze pads are packed around it to protect the peritoneal cavity, and it is 
 aspirated. When the contained fluid has been evacuated the flaccid bladder is drawn out of 
 the abdominal wound and its wall incised to the extent of an inch; any gall-stones in the 
 bladder are now removed and the interior of the sac sponged dry. If the case is one of 
 obstruction of the duct, an attempt must be made to dislodge the stone by manipulation through 
 the wall of the duct; or it may be crushed from without by the fingers or carefully padded for- 
 ceps. If this does not succeed, the safest plan is to incise the duct, extract the stone, close 
 
1348 
 
 THE ORGANS OF DIGESTION 
 
 the incision in the duct by fine sutures in two layers and employ drainage. After all obstruction 
 has been removed, four courses are open to the surgeon: 1. The wound in the gall-bladder 
 may be at once sewed up, the organ returned into the abdominal cavity, and the external incision 
 closed. 2. The edges of the incision in the gall-bladder may be sutured to the fascia of the ex- 
 ternal wound, and a fistulous communication established between the gall-bladder and the exte- 
 rior; this fistulous opening usually closes in the course of a few weeks. 3. The gall-bladder may 
 be connected with the intestinal canal, preferably the duodenum, by means of a lateral anasto- 
 mosis; this is known as cholecystenterostomy. 4. The gall-bladder may be completely removed 
 (cholecystectomy). Plan 2 is usually followed. Plan 4 is employed when the coats of the 
 gall-bladder are seriously diseased. Plan 2 is employed in obstruction of the common duct by 
 malignant disease. 
 
 If a stone blocks the diverticulum of Vater and if the common bile-duct and the pancreatic 
 duct empty into the diverticulum, it is evident that both ducts will be blocked. It has been 
 demonstrated that in such a case the pressure urging the bile onward is sufficient to overcome 
 the pressure in the pancreatic duct and drive bile into the ducts of the pancreas, the result, 
 perhaps, being disastrous inflammation of the pancreas. 
 
 Septic trouble arises more rapidly when a stone is blocked in the duct than when stones merely 
 block the gall-bladder, because the first-named part is richer in lymphatics (Murphy). 
 
 THE PANCREAS (Figs. 958, 959, 960, 961). 
 
 Dissection. — The pancreas may be exposed for dissection in three diflFerent ways: 1. By 
 raising the liver, drawing down the stomach, and tearing through the gastro-hepatic omentum 
 and the ascending layer of the transverse mesocolon. 2. By raising the stomach, the arch of 
 the colon, and great omentum, and then dividing the inferior layer of the transverse mesocolon 
 and raising its ascending layer. 3. By dividing the two layers of peritoneum, which descend 
 from the great curvature of the stomach to form the great omentum; turning the stomach 
 upward, and then cutting through the ascending layer of the transverse mesocolon (see Fig. 853). 
 
 The Pancreas {Tiav-xfjsa^, all flesh) is a compound racemose gland, analo- 
 gous in its structure to the saUvary glands, though softer and less compactly 
 arranged than those organs. It is long and irregularly prismatic in shape, and 
 has been compared to a human or a dog's tongue ; it is of reddish-white color. 
 Its right extremity being broad, is called the head. The right half of the head 
 above is continuous with the neck, which connects the head to the main portion 
 of the organ, the body. The neck is a slight constriction or thin part of the gland, 
 placed in front of the portal vein, and connecting the head to the body. The left 
 half of the head is separated from the neck by a notch, the incisura pancreaticus. 
 The body of the gland gradually tapers into an extremity directed to the left, and 
 called the tail. The pancreas is placed transversely across the posterior wall of 
 the abdomen, at the back of the epigastric and left hypochondriac regions. Its 
 length varies from five to six inches, its breadth is an inch and a half, and its thick- 
 ness from half an inch to an inch, being greater at its right extremity and along 
 its upper border. Its weight varies from two to three and a half ounces, but it 
 may reach six ounces. 
 
 The Right Extremity or Head of the Pancreas (caput pancreatis) (Fig. 958) 
 is shaped like the head of a hammer, being elongated both above and below; it 
 is flattened from before backward, and conforms to the whole concavity of the 
 duodenum, which is slightly overlapped by it. The anterior surface near its left 
 border exhibits a notch, the incisura pancreatis, which contains the superior mesen- 
 teric vessels. The notch marks the separation of the inferior portion of the head, 
 which is known as the uncinate process of Winslow {processus uncinaius \Winslowi\), 
 which rests, below, upon the inferior portion of the duodenum, and, above, is 
 pushed up back of the upper portion. The lower end of the head is crossed by 
 the transverse colon and its mesocolon. Behind, the head of the pancreas is in 
 relation with the inferior vena cava, the left renal vein, the right crus of the 
 Diaphragm, and the aorta. The common bile-duct descends behind, between 
 the duodenum and pancreas, or in the substance of the gland; and the pan- 
 
THE PANCREAS 
 
 1349 
 
 creatico-duodenal artery descends in front between the same parts. The head of 
 the pancreas is closely adherent to the duodenum. 
 
 Fig. 958. — The pancreas and its relations. 
 Gastric artery. ^^aU^ W>i Lower end of oesophagus. 
 
 Inferior mesenteric 
 artery. 
 
 -:ij_j.j,_iinr mesenteric 
 artery. 
 
 Spermatic vessels. 
 
 Fig. 959. — The duodenum and pancreas. The Uver has been Hfted up and the greater part of the stomach 
 removed: a, portal vein; 6, hepatic duct; c, cystic duct; d, hepatic artery; e, right sui)rarenal capsule; 
 /, pyloric orifice ; g, right gastro-epiploic artery ; h, superior mesenteric vein ; i, left crus of diaphragm ; j, left 
 suprarenal capsule ; k, splenic vein ; I, splenic artery; m, duodeno-jejunal junction ; a, b, c, d, the four portions 
 of the duodenum. (Testut.) 
 
1350 
 
 THE ORGANS OF DIGESTION 
 
 The Neck of the Pancreas is about an inch long, and passes upward and for- 
 ward to the left, having the first part of the duodenum above it, and the ter- 
 mination of the fourth portion below. It lies in front of the commencement of 
 the portal vein, and is grooved on the right by the gastro-duodenal and superior 
 pancreatico-duodenal arteries. The pylorus hes just above it. 
 
 The Body (corpus pancreatis) and Tail (cauda pancreatis) of the Pancreas are 
 somewhat prismatic in shape, and have three surfaces: anterior, posterior, and 
 inferior. 
 
 The Anterior Surface (fades anterior). — The anterior surface is somewhat con- 
 cave, and is covered by the posterior surface of the stomach which rests upon it, 
 the two organs being separated by the lesser sac of the peritoneum. At its right 
 extremity there is a well-marked prominence, called by His the omental tuberosity 
 (tuber omentale). 
 
 The Posterior Surface (fades posterior). — The posterior surface is separated from 
 the vertebral column by the aorta, the splenic vein, the left kidney and its vessels, 
 the left suprarenal capsule, the pillars of the Diaphragm, and the origin of the 
 superior mesenteric artery. 
 
 The Inferior Surface (fades inferior) (Fig, 959). — The inferior surface is narrow, 
 and lies upon the duodeno-jejunal flexure and on some coils of the jejunum; its left 
 extremity rests on the splenic flexure of the colon, 
 
 ^„„^ FIRST FOLD 
 
 ^ \,t-=;^^^^OF DUODENUM 
 
 ACCESSORY 
 PANCREATIC 
 DUCT 
 
 COMMON 
 BILE-DUCT 
 
 HEAD OF^^^ ^^^^BRANCH OF 
 
 PANCREAS ^^teKia^^ai^ ACCESSORY 
 DUCT 
 
 Fig. 960. — The pancreas and duodenum from behind, with the pancreatic duct exposed. The superior 
 mesenteric vessels are also shown in section, passing forward, surrounded by the recurved portion of the head of 
 the pancreas. (Cunningham.) 
 
 The Superior Border (margo superior) (Fig. 959). — The superior border of the 
 body is blunt and flat to the right; narrow and sharp to the left, near the tail. It 
 commences to the right in the omental tuberosity, and is in relation with the 
 coeliac axis, from which the hepatic artery courses to the right just above the gland, , 
 while the splenic branch runs in a groove along this border to the left. 
 
 The Anterior Border (margo anterior). — The anterior border is the position where 
 the two layers of the transverse mesocolon separate; the one passing upward in 
 front of the anterior surface, the other backward below the inferior surface 
 (Fig, 853), 
 
 The lesser end or tail of the pancreas is narrow; it extends to the left as far as 
 the lower part of the inner aspect of the spleen, and its end is directed upward and 
 to the left (Fig. 959), 
 
 Birmingham describes the body of the pancreas as projecting forward as a 
 prominent ridge into the abdominal cavity and forming a sort of shelf on which the 
 stomach hes. He says: "The portion of the pancreas to the left of the middle line 
 has a very considerable antero-posterior thickness; as a result the anterior surface 
 is of considerable extent, it looks strongly upward, and forms a large and important 
 part of the shelf. As the pancreas extends to the left toward the spleen it crosses 
 the upper part of the kidney, and is so moulded on to it that the top of the kidney 
 
THE PANCBEA8 
 
 1351 
 
 forms an extension inward and backward of the upper surface of the pancreas and 
 extends the bed in this direction. On the other hand, the extremity of the pan- 
 creas comes in contact with the spleen in such a way that the plane of its upper 
 surface runs with little interruption upward and backward into the concave gastric 
 surface of the spleen, which completes the bed behind and to the left, and, running 
 upward, forms a partial cap for the wide end of the stomach."^ An occasional 
 anomaly is a pancreas prolonged in front of the duodenum or actually embracing 
 it (annular pancreas). 
 
 Peritoneal Relations (Fig. 853). — The transverse mesocolon is attached to the 
 anterior border of the pancreas, from the tail to the neck of the gland, and the two 
 layers of the mesocolon separate. The anterior layer which comes from the lesser 
 peritoneum covers part of the anterior surface and the superior surface ; the poste- 
 rior layer, which comes from the greater omentum, covers the rest of the anterior 
 surface and the inferior surface. The posterior surface is devoid of peritoneum. 
 
 RECTUS MUSCLE. 
 
 8th Costal Cartilage. 
 
 7th Costal Cartilage. 
 
 Rib. 
 
 ..'Sth, Rib. 
 
 ■9th Rib. 
 
 10th Rib. 
 
 Abdominal Aorta. 
 
 12th Rib. nth Rib. 
 
 Fig. 961. 
 
 -Transverse section through the middle of the first lumbar vertebra, showing the relations 
 of the pancreas. (Braune.) 
 
 There is in front of the head and at the anterior margin a narrow strip of pancreas, 
 which remains uncovered by peritoneum and which corresponds to the cellular 
 tissue of the mesocolon. 
 
 The principal excretory duct of the pancreas, called the pancreatic duct or canal 
 of Wirsung {ductus 'pancreaticus [Wirsungi]) (Figs. 956, 958, and 960), from its 
 discoverer, extends transversely from left to right through the substance of the 
 pancreas. In order to expose it, the superficial portion of the gland must be 
 removed. It commences by the junction of the small ducts of the lobules situated 
 in the tail of the pancreas, and, running from left to right through the body, it con- 
 stantly receives the ducts of the various lobules composing the gland. Consider- 
 ably augmented in size, it reaches the neck, and turning obliquely downward, back- 
 ward, and to the right, it comes into relation with the common bile-duct, lying to 
 
 1 Journal of Anatomy and Physiology, vol. xxxi. part i. p. 102. 
 
1352 "IHE ORGANS OF DIGESTION 
 
 its left side; leaving the head of the gland, it passes very obliquely through the 
 mucous and muscular coats of the duodenum, and usually terminates by an orifice 
 common to it and the ductus communis choledochus upon the summit of an ele- 
 vated papilla, situated at the inner side of the descending portion of the duodenum, 
 three or four inches below the pylorus (Figs. 954, 955, and 957). 
 
 Sometimes the pancreatic duct and ductus communis choledochus open sepa- 
 rately into the duodenum (Fig. 893) . In about one-fifth of the subjects there is an 
 accessory duct, which is given off from the canal of Wirsung in the neck of the pan- 
 creas and passes horizontally to the right to open into the duodenum about an 
 inch above the orifice of the main duct. This is known as the duct of Santorini 
 (ductus pancreaiicus accessorius \Santorini\) (Figs. 956, 957, and 960). 
 
 The pancreatic duct, near the duodenum, is about the size of an ordinary quill; 
 its walls are thin, consisting of two coats, an external fibrous and an internal 
 mucous ; the latter is smooth, and furnished near its termination with a few scat- 
 tered follicles. 
 
 Structure. — In structure, the pancreas resembles the salivary glands. It differs 
 from them, however, in certain particulars, and is looser and softer in its texture. 
 It is not enclosed in a distinct capsule, but is surrounded by areolar tissue, which 
 dips into its interior, and connects together the various lobules of which it is com- 
 posed. Each lobule, like the lobules of the salivary glands, consists of one of the 
 ultimate ramifications of the main duct, terminating in a number of caecal pouches 
 or alveoli, which are tubular and somewhat convoluted. The minute ducts con- 
 nected with the alveoli are narrow and lined with flattened cells. They are the 
 secreting end tubules. The narrow ducts which come from the end tubules are 
 lined with flat epithelial cells. The alveoli are almost completely filled with secret- 
 ing cells, so that scarcely any lumen is visible. In the centre of the end tubules 
 flat cells are frequently found. They are continuations into the tubules of the 
 duct epithelium. These cells are known as the centro-acinar cells of Langerhans. 
 The true secreting cells which line the wall of the alveolus are very characteristic. 
 They are columnar or rounded in shape and present two zones: an outer one 
 clear and finely striated next the basement-membrane, and an inner granular 
 one next the lumen. The highly refracting granules are known as zymogen 
 granules. During digestion the granules gradually disappear and the cells become 
 clear. During fasting the granular zone occupies more than one-half of the cell 
 (Szymonowicz). In some secreting cells of the pancreas is a spherical mass, 
 staining more easily than the rest of the cells; this is termed the paranucleus, and 
 is believed to be an extension from the nucleus. The connective tissue among the 
 gland tubules and alveoli presents in certain parts collections of cells, which are 
 termed inter-alveolar cell-islets, intertubular cell-masses or islands of Langerhans. 
 Opie points out that they are most common in the splenic end of the pancreas. 
 The cells of the islands are smaller than the secreting cells of the alveoli, and 
 are arranged in layers with intervening spaces. The islands are surrounded by 
 fine connective tissue. The spaces in the islands contain capillaries. There 
 are no ducts in the islands of Langerhans. Their function is to furnish the 
 internal secretion of the pancreas. 
 
 Blood-vessels, Lymphatics, and Nerves. — The arteries of the pancreas come from 
 the superior pancreatico -duodenal branch of the gastro -duodenal; the inferior pan- 
 creatico-duodenal branch of the superior mesenteric; the inferior pancreatic branch of 
 the superior mesenteric; pancreatic branches of the hepatic and pancreatic branches 
 of the splenic. In a few cases a large artery, the pancreatica magna, accompanies 
 the pancreatic duct. In most cases there is no such vessel. The veins are the 
 anterior pancreatico -duodenal branch of the superior mesenteric; the posterior pancre- 
 atico -duodenal branch and other pancreatic branches of the portal; and pancreatic 
 branches of the splenic. The lymphatics arise in a network about the lobules. 
 
THE SPLEEN I353 
 
 Numerous collecting trunks pass to the surface of the pancreas, anastomose with 
 each other, and enter into glands about the pancreas. The splenic glands receive 
 most of the trunks. Others are received by glands along the aorta (Sappey), 
 glands at the origin of the superior mesenteric artery, and glands along the pan- 
 creatico-duodenal vessels.^ The nerves come from the coeliac, superior mesenteric, 
 and splenic plexuses. 
 
 The Pancreatic Juice. — The pancreatic juice is a clear, somewhat viscid alkaline 
 liquid. Its specific gravity is about 1030. The solid matter consists chiefly of 
 proteids, and amounts to about 10 per cent, of a sample of the juice.^ The juice 
 contains a ferment which breaks up fat, a ferment which converts starch into 
 sugar, a ferment which curdles milk, and a ferment which digests proteid material. 
 
 Surface Form.— The pancreas lies in front of the second lumbar vertebra, and can some- 
 times be felt, in emaciated subjects, when the stomach and colon are empty, by making deep 
 pressure in the middle line about three inches above the umbilicus. 
 
 Surgical Anatomy. — Of late years our knowledge of the structure, functions, and diseases 
 of the pancreas has been notably increased, and surgeons have begun to operate for certain 
 pancreatic diseases. It is occasionally the seat of cancer, which usually affects the head or 
 duodenal end, and therefore often speedily involves the common bile-duct, leading to persistent 
 jaundice. Cancer of the pancreas may be primary or secondary. Primary sarcoma is very 
 unusual; secondary sarcoma is more common, but cancer is far commoner than either form of 
 sarcoma. Adenoma may also occur. Cases are on record of the successful removal of tumors of 
 the pancreas, but the operations are very dangerous, are extremely difficult, and are seldom 
 attempted. The pancreas may be ihe seat of sy^philitic or tuberculous disease. As a result of 
 pancreatic injury, there may be elusion into the lesser peritoneal cavity. The lesser cavity 
 becomes distended, and the fluid of this pseudo-cyst may contain pancreatic juice (Jordan Lloyd). 
 True cysts of the pancreas are occasionally found. Pancreatic cysts may result from blocking 
 of the duct, from epithelial proliferation, from traumatism and hemorrhage, or from hydatid dis- 
 ease. Congenital cysts may occur, and cystic carcinoma is sometimes encountered. Cysts of the 
 pancreas may present in the epigastric region above and to the right of the umbilicus. The 
 fluid in these cysts contains some of the pancreatic secretion. A pancreatic cyst is best treated 
 by opening the abdomen, suturing the cyst to the skin, opening the cyst and providing for drainage. 
 Complete extirpation of the cyst is invariably difficult and is usually impossible. It has been 
 said that the pancreas is the only abdominal viscus which has never been found in a hernial pro- 
 trusion; but even this organ has been found, in company with other viscera, in rare cases of 
 diaphragmatic hernia. The pancreas has been known to become invaginated into the intestine, 
 and portions of tue organ have sloughed ofi". In cases of excision of the pylorus great care must 
 be exercised to avoid wounding the pancreas, as the escape of the pancreatic fluid may be attended 
 with serious and even with fatal results, peritonitis and fat necrosis, and gangrene being caused. 
 
 Rupture of the pancreas as a solitary result of traumatism is very unusual, but is more common 
 in violent injuries which rupture the liver and spleen as well. An injury which lacerates the 
 pancreas and permits blood and pancreatic juice to flow into the lesser peritoneal cavity is usually 
 rapidly fatal, but may not be. The foramen of Winslow may be occluded by inflammation, and 
 a pseudo-cyst may form. In severe laceration of the pancreas alone, it would be proper to open 
 the abdomen, ligature bleeding vessels, suture the pancreas, and drain the lesser peritoneal cavity 
 posteriorly. A gun-shot wound of the pancreas requires posterior drainage. Every eftort must 
 be made in a pancreatic wound to rapidly get rid of pancreatic fluid by drainage from the 
 wound area, as this fluid is extremely irritant and may cause gangrene. 
 
 Inflammation of the pancreas is due to infection. Occasionally it seems to follow the entrance 
 of bile into the pancreatic duct, because of plugging of the ampulla with a calculus (Halsted, 
 Opie). Hemorrhage into the pancreas is frequent in acute pancreatitis, and fat necrosis is common 
 in the fat of the mesentery, subperitoneal tissue, omentum, and other parts. Acute pancreatitis 
 may be recovered from if the abdomen is opened, the pancreas incised, and drainage employed. 
 
 In chronic interstitial pancreatitis of the head of the pancreas the gall-duct is apt to become 
 blocked, and the disease is frequently mistaken for cancer. Cure may follow opening and drain- 
 age of the gall-bladder. 
 
 THE SPLEEN (LIEN) (Figs. 958. 959, 961). 
 
 The spleen belongs to that class of bodies which are known as ductless glands. 
 It is probably related to the blood-vascular system, but in consequence of its 
 
 1 Poirier, Cun(5o, and Delamare on the Lymphatics. Edited and translated by Cecil H. Leaf. 
 * Robson and Moyniham on Disease.s of the Pancreas. 
 
1354 
 
 THE ORGANS OF DIGESTION 
 
 anatomical relationship to the stomach and its physiological relationship to the 
 liver it is convenient to describe it in this section. It is situated principally in the 
 posterior portion of the left hypoohondriac region, its upper and inner extremity 
 extending into the epigastric region; lying between the fundus of the stomach 
 and the Diaphragm. If the abdomen is opened a spleen of ordinary size is not 
 visible from the front, as it is placed between the left kidney. Diaphragm, and 
 stomach. It moves with the respiratory movements and with the movements of 
 the stomach. It is the largest of the so-called ductless glands, and varies greatly 
 in size. Usually it measures some five inches in length. It is of an oblong, 
 flattened form, soft, of very brittle consistence, highly vascular, and of a dark- 
 purplish color. 
 
 Surfaces. The External or Phrenic Surface (fades diaphragmatica). — The exter- 
 nal or phrenic surface is convex, smooth, and is directed upward, backward, and 
 to the left, except at its upper end, where it is directed slightly inward. It is in 
 relation with the under surface of the Diaphragm, which separates it from the 
 eighth, ninth, tenth, and eleventh ribs of the left side, and in part from the lower 
 
 border of the left lung and pleura. It is 
 to be remembered that not only are the 
 peritoneum and the Diaphragm between 
 the spleen and the ribs, but also the cavity 
 of the left pleura and a portion of the left 
 lung. 
 
 The Internal Surface. — The internal sur- 
 face is concave, and divided by a ridge 
 into an anterior or larger, and a posterior or 
 smaller portion. 
 
 The Anterior Portion of the internal sur- 
 face or the gastric surface (fades gastrica), 
 which is directed forward and inward, is 
 broad and concave, and is in contact with 
 the posterior wall of the great end of the 
 stomach; and below this with the tail of 
 the pancreas. It presents near its inner 
 border a long fissure, termed the hilum 
 (hilus lienis). This is pierced by several 
 irregular apertures, for the entrance and 
 exit of vessels and nerves. 
 
 The Posterior Portion of the internal 
 
 surface or the renal surface (fades renalis) 
 
 is directed inward and downward. It is 
 
 somewhat flattened, does not reach as high 
 
 as the gastric surface, is considerably narrower than the latter, and is in relation 
 
 with the upper part of the outer surface of the left kidney and occasionally with 
 
 the left suprarenal capsule. 
 
 The upper end of the spleen (extremitas superior) is directed inward, toward the 
 vertebral column, where it lies on a level with the eleventh dorsal vertebra. The 
 lower end (extremitas inferior), sometimes termed the basal surface, is flat, triangular 
 in shape, and rests upon the splenic flexure of the colon and the phreno-colic liga- 
 ment, and is generally in contact with the tail of the pancreas. The anterior border 
 (margo anterior) is free, sharp, and thin, and is often notched, especially below. It 
 separates the phrenic surface from the gastric surface. The posterior border (margo 
 posterior) is more rounded and blunter than the anterior. It separates the renal 
 portion of the internal surface from the phrenic surface. It corresponds to the 
 lower border of the eleventh rib and lies between the Diaphragm and left kidney. 
 
 Fig. 962. — The spleen, showing its gastric and 
 renal surfaces. (Testut.) 
 
THE SPLEEN 
 
 1355 
 
 The internal border is the name sometimes given to the ridge which separates the 
 renal and gastric portions of the internal surface. 
 
 The spleen is surrounded by peritoneum, except at the hilum and the serous 
 membrane, is firmly adherent to its capsule, and is held in position by two folds 
 of this membrane: one, the lieno-renal ligament (ligamentum phrenicolienale) (Figs. 
 857 and 860), is derived from the layers of peritoneum forming the greater and 
 lesser sacs, where they come into contact between the left kidney and the spleen. 
 Between its two layers the splenic vessels pass; the second, the gastro -splenic 
 omentum (ligamentum gastrolienale), also formed of two layers, derived from the 
 greater and lesser sacs, respectively, where they meet between the spleen and 
 stomach (Fig. 860). Between these two layers run the vasa brevia of the 
 splenic artery and vein. The spleen is also supported by the phreno-colic ligament 
 (ligamentum phrenicocolicum), upon which its lower end rests. 
 
 The size and weight of the spleen are liable to very extreme variations at dif- 
 ferent periods of life, in different individuals, and in the same individual under 
 different conditions. In the adult, in whom it attains its greatest size, it is usually 
 
 Fig. 963. — Transverse section of the spleen, showing the trabecular tissue and the splenic vein and 
 
 its tributaries. 
 
 about five inches in length, three inches in breadth, and an inch or an inch and a 
 half in thickness, and weighs about seven ounces. At birth, its weight, in propor- 
 tion to the entire body, is almost equal to what is observed in the adult, being as 
 1 to 350; while in the adult it varies from 1 to 320 to 1 to 400. In old age, the organ 
 not only decreases in weight, but decreases considerably in proportion to the 
 entire body, being as 1 to 700. The size of the spleen is increased during and 
 after digestion, and varies considerably according to the state of nutrition of the 
 body, being large in highly fed, and small in starved animals. In intermittent 
 and other fevers it becomes much enlarged, weighing occasionally from eighteen 
 to twenty pounds. 
 
 Frequently in the neighborhood of the spleen, and especially in the gastro- 
 splenic and great omenta, small nodules of splenic tissue may be found, either 
 isolated, or connected to the spleen by thin bands of splenic tissue. Every such 
 nodule is known as a supernumerary or accessory spleen (lien accessorius). Accessory 
 spleens vary in size from that of a pea to that of a plum. 
 
1356 '^HE ORGANS OF DIGESTION 
 
 Support and Movability of the Spleen. — The spleen is normally movable 
 within certain narrow limits. It moves with respiration and with stomach move- 
 ments. It is supported by ligaments (p. 1355). An unduly movable spleen is 
 called a movable spleen. In order that a spleen shall become unduly movable, 
 the ligaments must stretch, and this stretching is often effected when the organ 
 is greatly enlarged, but even an apparently normal spleen may become movable. 
 Movable spleen is usually associated with movable left kidney. 
 
 Stnicture. — The spleen is invested by two coats — an external serous and an 
 internal fibro-elastic coat. 
 
 The External or Serous Coat {tunica serosa). — The external or serous coat is 
 derived from the peritoneum; it is thin, smooth, and in the human subject is inti- 
 mately adherent to the fibro-elastic coat. It invests the entire organ, except at 
 the places of its reflection on to the stomach and Diaphragm and at the hilum. 
 
 The Fibro-elastic Coat {tunica albuginea). — The fibro-elastic coat forms the 
 framework of the spleen. It is composed of connective tissue containing muscle- 
 cells and elastic fibres, and it invests the organ as a capsule, and at the hilum is 
 reflected inward upon the vessels in the form of sheaths. From these sheaths, as 
 well as from the inner surface of the fibro-elastic coat, numerous small fibrous 
 bands, trabeculae {trabeculae lienis) (Figs. 963 and 964), are given off in all direc- 
 tions; these uniting, constitute the framework of the spleen. This framework 
 resembles a sponge-like material, consisting of a number of small spaces or 
 areolae formed by the trabeculae, which are given off from the inner surface of the 
 capsule, or from the sheaths prolonged inwardly on the blood-vessels. The spaces 
 or areolae contain the adenoid material known as splenic pulp {pulpa lienis). 
 
 The proper coat, the sheaths of the vessels and the trabeculae, consist of a 
 dense mesh of white and yellow elastic fibrous tissues, the latter decidedly pre- 
 dominating. It is owing to the presence of this tissue that the spleen possesses 
 a considerable amount of elasticity, which allows of the very great variations in 
 size that it presents under certain circumstances. In addition to these con- 
 stituents of this tunic, there is found in man a small amount of non-striped mus- 
 cular fibre, and in some mammalia {e. g., dog, pig, and cat) a very considerable 
 amount, so that the trabeculae appear to consist chiefly of muscular tissue. It is 
 probably because of this muscular structure that the spleen exhibits, when acted 
 upon by the galvanic current, faint traces of contractility. 
 
 The proper substance of the spleen or splenic-pulp is a soft mass of a dark 
 reddish-brown color, resembling gruraous blood. When a thin section is exam- 
 ined under a microscope, it is found to consist of a number of branching 
 cells and an intercellular substance. The cells are connective-tissue corpuscles, 
 and have been named the sustentacular or supporting cells of the pulp. The 
 processes of these branching cells communicate with each other, thus forming a 
 delicate reticulated tissue in the interior of the areolae formed by the trabeculae of 
 the capsule; so that each primary space may be considered to be divided into a 
 number of smaller spaces by the junction of these processes of the branching 
 corpuscles. These secondary spaces contain blood, in which, however, the white 
 corpuscles are found to be in larger proportions than in ordinary blood. The 
 sustentacular cells are either small uni-nucleated or larger multi-nucleated cells; 
 they do not stain deeply with carmine, like the cells of the Malpighian 
 bodies, presently to be described (W. Miiller), but like them they possess amoe- 
 boid movements (Cohnheim). In many of them may be seen deep red or 
 reddish-yellow granules of various sizes which present the characters of the 
 hsematin of the blood. Sometimes, also, unchanged blood-disks are seen included 
 in these cells, but more frequently blood-disks are found which are altered both 
 in form and color. In fact, blood-corpuscles in all stages of disintegration may 
 be noticed to occur within them. Klein has recently pointed out that sometimes 
 
THE SPLEEN 
 
 1357 
 
 these cells in the young spleen contain a proliferating nucleus; that is to say, 
 the nucleus is of large size, and presents a number of knob-like projections, 
 as if small nuclei were budding from it by a process of gemmation. This obser- 
 vation is of importance, as it may explain one possible source of the colorless 
 blood-corpuscles. 
 
 The interspaces or areolae formed by the framework of the spleen are thus filled 
 by a delicate reticulum of branched connective-tissue corpuscles, the interstices of 
 which are occupied by blood, and in which the blood-vessels terminate in the 
 manner now to be described. 
 
 Blood-vessels of the Spleen. — The splenic artery (Fig. 961) is remarkable for its 
 large size in proportion to the size of the organs, and also for its tortuous course. 
 It divides into six or more branches, which enter the hilum of the spleen and 
 ramify throughout its substance, receiving sheaths from the involution of the 
 external fibrous tissue. Similar sheaths also invest the nerves and veins. 
 
 Each branch runs in the transverse axis of the organ from within outward, 
 diminishing in size during its transit, and giving off in its passage smaller branches, 
 some of which pass to the anterior, others to the posterior part. These ultimately 
 
 Fig. 964. — Transverse section of the human spleen, showing the distribution of the splenic artery 
 
 and its branches. 
 
 leave the trabecular sheaths, and terminate in the proper substance of the spleen 
 in small tufts or pencils of minute arterioles, which open into the interstices 
 of the reticulum formed by the branched sustentacular cells (Figs. 964, 965, and 
 966). Each of the larger branches of the artery supplies chiefly that region of the 
 organ in which the branch ramifies, having no anastomosis with the majority 
 of the other branches. 
 
 The arterioles (Fig. 966), supported by the minute trabeculae, traverse the pulp 
 in all directions in bundles or pencilli of straight vessels. Their external coat, on 
 leaving the trabecular sheaths, consists of ordinary connective tissue, but it grad- 
 ually undergoes a transformation, becomes much thickened, and is converted into 
 a lymphoid material.^ This change is effected by the conversion of the con- 
 nective tissue into a lymphoid tissue, the bundles of connective tissue becoming 
 looser and laxer, their fibrils more delicate, and containing in their interstices 
 an abundance of lymph-corpuscles (W. Miiller). This lymphoid material is sup- 
 plied with blood by minute vessels derived from the artery with which they are 
 
 1 According to Klein, it is the sheath of the small vessel which undergoes this transformation, and forms a 
 ^' solid mass of adenoid tissue which surrounds the vessel like a cylindrical sheath." (Atlas of Histology, p. 424.) 
 
1358 
 
 THE ORGANS OF DIGESTION 
 
 in contact, and which terminates by breaking up into a network of capillary 
 vessels. 
 
 The altered coat of the arterioles, consisting of lymphoid tissue (Fig. 966), pre- 
 sents here and there thickenings of a spheroidal shape, the Malpighian bodies of the 
 spleen (noduli lymphatici lienales [Malpighii]) (Fig. 965) . These bodies vary in size 
 from about the y^^ of an inch to the yj- of an inch in diameter. They are merely 
 local expansions or hyperplasiae of the lymphoid tissue of which the external coat of 
 the smaller arteries of the spleen is formed. They are most frequently found sur- 
 rounding the arteriole, which thus seems to tunnel them, but occasionally they grow 
 from one side of the vessel only, and present the appearance of a sessile bud grow- 
 ing from the arterial wall. Klein, however, denies this, and says it is incorrect to 
 describe the Malpighian bodies as isolated masses of adenoid tissue, but that they 
 are always formed around an artery, though there is generally a greater amount on 
 one side than on the other, and that, therefore, in transverse sections the artery in 
 the majority of cases is found in an eccentric position. These bodies are visible to 
 the naked eye on the surface of a fresh section of the organ, appearing as minute 
 
 dots of semi-opaque whitish color in the dark 
 substance of the pulp. In minute structure they 
 resemble the adenoid tissue of lymphatic glands, 
 consisting of a delicate reticulum in the meshes 
 of which lie ordinary lymphoid cells. 
 
 The reticulum of the tissue is made up of ex- 
 tremely delicate fibrils, and is comparatively 
 open in the centre of the corpuscle, becoming 
 closer at the periphery of the body. The cells 
 which it encloses, like the supporting cells of the 
 pulp, are possessed of amoeboid movements, but 
 when treated with carmine become deeply 
 stained, and can thus easily be recognized from 
 those of the pulp. 
 
 The arterioles terminate in capillaries, which 
 traverse the pulp in all directions; their walls 
 become much attenuated, lose their tubular 
 character, and the cells of the lymphoid tissue 
 of which they are composed become altered; presenting a branched appearance 
 and acquiring processes which are directly connected with the processes of the 
 sustentacular cells of the pulp (Fig. 966). In this manner the capillary vessels 
 terminate, and the blood flowing through them finds its way into the interstices 
 of the reticulated tissue formed by the branched connective-tissue corpuscles of 
 the splenic pulp. Thus the blood passing through the spleen is brought into 
 intimate relation with the elements of the pulp, and no doubt undergoes important 
 changes. 
 
 After these changes have taken place the blood is collected from the interstices 
 of the tissue by the rootlets of the veins (Fig. 963) , which commence much in the 
 same way as the arteries terminate. Where a vein is about to originate the con- 
 nective-tissue corpuscles of the pulp arrange themselves in rows in such a way as to 
 form an elongated space or sinus. They become changed in shape, being elongated 
 and spindle-shaped, and overlap each other at their extremities. They thus form 
 a sort of endothelial lining of the path or sinus, which is the radicle of a vein. 
 On the outer surface of these cells are seen delicate transverse lines or markings 
 vvhich are due to minute elastic fibrillae arranged in a circular manner around the 
 smus. Thus the channel obtains a continuous external investment, and grad- 
 ually becomes converted into a small vein, which after a time presents a coat of 
 ordinary connective tissue, lined by a layer of fusiform endothelial cells which are 
 
 Fig. 965. — Part of a Malpighian body 
 of the spleen of man. a, arterial branch 
 in longitudinal section ; b, adenoid tissue, 
 still containing the lymph-corpuscles ; only 
 their nuclei are shown ; r, adenoid reticu- 
 lum, the lymph-corpuscles accidentally re- 
 moved. (Klein and Noble Smith.) 
 
THE SPLEEN 
 
 1359 
 
 continuous with the supporting cells of the pulp. The smaller veins unite to form 
 larger ones which do not accompany the arteries, but soon enter the trabecular 
 sheaths of the capsule, and by their junction form from six or more branches which 
 emerge from the hilum and, uniting, form the splenic vein, the largest radicle of 
 the portal vein (Figs. 958 and 962). 
 
 The veins are remarkable for their numerous anastomoses, while the arteries 
 hardly anastomose at all. 
 
 The lymphatics originate in two ways — i .e., from the sheaths of the arteries 
 and in the trabecula?. The former trunks are the deep collecting trunks, and 
 
 Supporting cell. 
 
 Vessel undergoing lymphoid change. 
 
 Vessel continuous 
 with processes of 
 supporting cells. 
 
 Supporting cell. 
 
 Fig. 966. — Section of spleen, showing the termination of the small blood-vessels. 
 
 accompany the blood-vessels ; the latter pass to the superficial lymphatic plexus, 
 which may be seen on the surface of the organ. The two sets communicate in 
 the interior of the organ. The deep trunks at the hilum number from five to 
 ten, and terminate in the splenic glands. The superficial trunks also pass to the 
 hilum and terminate in the splenic glands. 
 
 The nerves are derived from the splenic plexus, which is part of or connected 
 with the solar plexus. The nerves enter the spleen with the vessels. 
 
 Surface Form. — ^The spleen is situated under cover of the ribs of the left side, being sepa- 
 rated from them by the Diaphragm, and above by a small portion of the lower margin of the 
 left lung and pleura. Its position corresponds to the eighth, ninth, tenth, and eleventh ribs. 
 It is placed very obliquely. " It is oblique in two directions — viz., from above downward and 
 outward, and also from above downward and forward" (Cunningham). " Its highest and 
 lowest points are on a level respectively with the ninth dorsal and first lumbar spines; its inner 
 end is distant about an inch and a half from the median plane of the body, and its outer end 
 about reaches the mid-axillary line" (Quain). 
 
 Surgical Anatomy. — Injury of the spleen is less common than that of the liver, on account 
 of its protected situation and connections. It may be ruptured by direct or indirect violence, 
 torn by a broken rib, or injured by a punctured or gunshot wound. When the organ is enlarged 
 the chance of rupture is increased. The great risk is hemorrhage, owing to the extreme vascu- 
 larity of the organ, and the absence of a proper system of capillaries. The injury is not, how- 
 ever, necessarily fatal, and this would appear to be due in a great measure to the contractile 
 power of its capsule, which narrows the wound and thus antagonizes the escape of blood. In 
 cases in which the symptoms suggest such an injury and indicate danger to life, laparotomy must 
 be performed ; and if the hemorrhage cannot be arrested by ordinary surgical methods the spleen 
 must be removed. The spleen may become displaced, producing great pain from stretching of 
 the vessels and nerves, and this dislocation may render necessary removal of the organ. The 
 spleen may become enormously enlarged in certain diseased conditions, such as ague, leukaemia, 
 syphilis, valvular disease of the heart, or without any obtainable history of previous disease. 
 It may also become enlarged in lymphadenoma as a part of a general blood disease. In these 
 cases the mass may fill the abdomen and extend into the pelvis, and may be mistaken for 
 ovarian or uterine disease. 
 
1360 THE ORGANS OF DIGESTION 
 
 The spleen is sometimes the seat of cystic tumors, especially hydatids, and of abscess. These 
 cases require treatment by incision and drainage; and in abscess great care must be taken if 
 there are no adhesions between the spleen and abdominal cavity, to prevent the escape of any 
 of the pus into the peritoneal cavity. If possible, the operation should be performed in two 
 stages. Sarcoma and carcinoma are occasionally found in the spleen, but very rarely as a primary 
 disease. In movable spleen, if the organ is normal, follow the advice of Ilydygier and loosen 
 the parietal peritoneum to make a pocket, place the spleen in the pocket, and pass sutures through 
 the parietal peritoneum and the splenic ligaments. A movable diseased spleen should be removed. 
 
 Extirpation of the spleen has been performed for wounds or injuries, floating spleen, simple 
 hypertrophy, and leukismic enlargement; but in the latter case the operation is now regarded 
 as unjustifiable, as it is practically certain to terminate fatally. The incision is best made in 
 the left semilunar line: the spleen is isolated from its surroundings, and the pedicle transfixed 
 and ligatured in two portions, before the tumor is turned out of the abdominal cavity, if this is 
 possible, so as to avoid any traction on the pedicle, which may cause tearing of the splenic vein and 
 which inevitably induces grave shock. In applying the ligatures the surgeon must not include 
 the tail of the pancreas, and in lifting out the organ care must be taken to avoid rupturing the 
 capsule. 
 
THE ORGANS OF VOICE AND RESPIMTION. 
 
 THE LARYNX. 
 
 ^F^HE Larynx is the organ of voice, placed at the upper part of the air-passage. 
 JL It is situated between the trachea and base of the tongue, at the upper and 
 forepart of the neck, where it forms a considerable projection in the middle line. 
 On either side of it lie the great vessels of the neck; behind, it forms part of the 
 boundary of the pharynx, and is covered by the mucous membrane lining that 
 cavity. Its vertical extent corresponds to the fourth, fifth, and sixth cervical ver- 
 tebrae, but it is placed somewhat higher in the female and also during childhood. 
 In infants between six and twelve months of age Symington found that the tip of 
 
 Fig. 967. — Sagittal section of a man twenty-one years of age. (After W. Braune.) 
 
 the epiglottis was a little above the level of the cartilage between the odontoid 
 process and body of the axis, and that between infancy and adult life the larynx 
 descends for a distance equal to two vertebral bodies and two intervertebral disks. 
 The movements of the head affect the position of the larynx. When the head is 
 drawn back, the larynx is lifted, and when the chin approaches the chest the 
 larynx is depressed. During swallowing the larynx moves distinctly; during sing- 
 ing it moves slightly. The larynx is suspended by the stylo-hyoid ligament, the 
 
 86 ( 1361 ) 
 
1362 'J'HE ORGANS OF VOICE AND BESPIBATION 
 
 muscles of the upper border of the hyoid bone, the Stylo-pharyngeus and Palato- 
 pharyngeus muscles. According to Sappey, the average measurements of the adult 
 larynx are as follows: 
 
 In males. In females. 
 
 Vertical diameter . . . .44 mm. 36 mm. 
 
 Transverse diameter . . . 43 " 41 " 
 
 Antero-posterior diameter . . 36 " 26 " 
 
 Circumference . . . . 136 *' 112 " 
 
 Until puberty there is no marked difference between the larynx of the male 
 and that of the female. In the latter its further increase in size is only slight, 
 whereas in the former it is great; all the cartilages are enlarged, and the thyroid 
 becomes prominent as the pomum Adami in the middle line of the neck, while 
 the length of the glottis is nearly doubled. 
 
 The larynx is broad above, where it presents the form of a triangular box, 
 flattened behind and at the sides, and bounded in front by a prominent vertical 
 ridge. Below, it is narrow and cylindrical. It is composed of cartilages, which 
 are connected together by ligaments and moved by numerous muscles. It is lined 
 by mucous membrane, which is continuous above with that lining the pharynx and 
 below with that of the trachea. 
 
 In the median line of the neck the larynx has in front of it the skin and cer- 
 vical fascia. There is often a bursa between the skin and fascia over the most 
 prominent part of the larynx. It is called the bursa subcutanea prominentiae 
 larsmgeae. It is present particularly in men, and is seldom found in the 
 young or in women. The larynx is covered to each side by the thyroid gland, 
 and the Sterno-hyoid, Sterno-thyroid, Thyro-hyoid, and Omo-hyoid muscles, and 
 the Inferior constrictors of the pharynx. Posterior is the laryngeal portion of the 
 pharynx. 
 
 The Cartilages of the Larynx {cartilagines lanjngis). — The cartilages of the 
 larynx are nine in number, three single, and three pairs: 
 
 Thyroid. Two Arytenoid. 
 
 Cricoid. Two Cornicula Laryngis. 
 
 Epiglottis. Two Cuneiform. 
 
 The Thyroid Cartilage (cartilago thyreoidea) (Figs. 968 and 969) . — The thyroid 
 cartilage (from dvpeo^, a shield) is hyaline cartilage and is the largest cartilage 
 of the larynx. It is at the anterior and upper portion of the larynx. It con- 
 sists of two lateral lamellae or alae, united at an acute angle in front, forming a 
 vertical projection in the middle line, which is prominent above and called the 
 pomum Adami (prominentia laryngea). This projection is subcutaneous, is more 
 distinct in the male than in the female, and is often separated from the integu- 
 ment by a bursa, the bursa subcutanea prominentiae laryngeae. 
 
 Each lamella is quadrilateral in form. Its outer surface (Fig. 968) presents 
 an oblique ridge (linea ohliqua), which passes downward and forward from a 
 tubercle situated near the root of the superior cornu, the superior tubercle (tuber- 
 culum thyreoideum superius), to a small tubercle near the anterior part of the 
 lower border, the inferior tubercle (tuherculum thyreoideum inferius). This ridge 
 gives attachment to the Sterno-thyroid and Thyro-hyoid muscles, and the portion 
 of cartilage included between it and the posterior border gives attachment to 
 part of the Inferior constrictor muscle. Just below each superior tubercle there 
 is often an opening, the thyroid foramen (foramen thyreoideum). 
 
 The anterior borders of the alae of the thyroid cartilage which are continuous 
 below are separated above by a V-shaped notch, the thsrroid notch (incisura thy- 
 reoidea [superior] ) . 
 
THE LABYNX 
 
 1363 
 
 The Inner Surface (Fig. 969) of each ala is smooth, slightly concave, and 
 covered by mucous membrane above and behind; but in front, in the receding 
 angle formed by their junction, are attached the epiglottis, the true and false 
 vocal cords, the Thyro-arytenoid and Thyro-epiglottidean muscles, and the 
 thyro-epiglottidean ligament. 
 
 The Upper Border or Margin of the Thyroid Cartilage (Fig. 969) is sinuously curved, 
 being concave at its posterior part, just in front of the superior cornu, then rising 
 into a convex outline, which dips in front to form the sides of the thyroid notch, 
 in the middle line, immediately above the pomum 
 Adami. This border gives attachment through- 
 out its whole extent to the th3nro-hyoid or hyo- 
 thyroid membrane (membrana hyothyreoidea) . 
 
 The Lower Border or Margin (Fig. 969) is nearly 
 straight in front, but behind, close to the cornu, 
 it is concave. It is connected to the cricoid cartil- 
 age, in and near the median line, by the middle 
 portion of the crico-thyroid membrane (membrana 
 cricothyreoidea) ; and, on either side, by the 
 Crico-thyroid muscle. 
 
 The Posterior Borders (Fig. 969) are thick and 
 rounded, and each terminates above, in a superior 
 cornu {cornu swperius), and below, in an inferior 
 cornu {cornu injerius). The two superior cornua 
 are long and narrow, directed upward, backward, 
 and inward, and terminate in conical extremities, 
 which give attachment to the lateral thyro-hyoid 
 ligaments. The two inferior cornua are short 
 and thick; they pass downward, with a slight in- 
 clination forward and inward, and each presents 
 on its inner surfaces a small oval articular facet 
 for articulation with the side of the cricoid cartil- 
 age (Fig. 968) . The posterior border receives the 
 insertion of the Stylo-pharyngeus and Palato-pharyngeus muscles on each side. 
 
 During infancy the alae of the thyroid cartilage are joined to each other by a 
 narrow, lozenge-shaped strip, named the intrath3n:oid cartilage. This strip extends 
 from the upper to the lower border of the thyroid cartilage in the middle line, 
 and is distinguished from the alae by being more transparent and more flexible. 
 
 The Cricoid Cartilage {cartilago cricoidea) (Figs. 968, 969, and 971). — The cri- 
 coid cartilage is so called from its resemblance to a signet ring {xpixo(;, a ring). 
 It is smaller, but thicker and stronger * than the thyroicl cartilage, and forms the 
 lower and back part of the cavity of the larynx. It is hyaline cartilage and con- 
 sists of two parts: a quadrate portion, situated behind, and a narrow ring or 
 arch, one-fourth or one-fifth the depth of the posterior part, situated in front. 
 The posterior square portion rapidly narrows at the sides of the cartilage, at the 
 expense of the upper border, into the anterior portion. 
 
 Its Posterior Portion or Lamina {lamina cartilaginis cricoideae) is very deep and 
 broad, and measures from above downward about an inch {2 to 3 cm.) ; it presents, 
 on its posterior surface, in the middle line, a vertical ridge for the attachment of 
 the longitudinal fibres of the oesophagus; and on either side a broad depression 
 for the Crico-arytenoideus posticus muscle. 
 
 Its Anterior Portion or Arcus {arcus cartilaginis cricoideae) is narrow and convex, 
 and measures vertically about one-fourth or one-fifth of an inch (5 to 7 cm.); 
 it affords attachment externally in front and at the sides to the Crico-thyroid 
 muscles, and, behind, to part of the Inferior constrictor. 
 
 Fig. 968 
 
 Side view of the thyroid 
 and cricoid cartilages. 
 
1364 
 
 THE ORGANS OF VOICE AND RESPIRATION 
 
 Epiglottis. 
 
 At the point of junction of the posterior quadrate portion with the rest of the 
 cartilage is a small round elevation, for articulation with the inferior cornu of the 
 thyroid cartilage. 
 
 The Lower Border of the cricoid cartilage is horizontal, and connected to the 
 upper ring of the trachea by fibrous membrane (Figs. 968 and 970). 
 
 Its Upper Border is directed obliquely upward and backward, owing to the 
 great depth of the posterior surface. It gives attachment, in front, to the middle 
 
 portion of the crico-thyroid mem- 
 brane ; at the sides, to the lateral 
 portion of the same membrane 
 and to the lateral Crico-arj'tenoid 
 muscle; behind, it presents, in the 
 middle, a shallow notch, and on 
 each side of this is a smooth, oval 
 surface, directed upward and out- 
 ward, for articulation with the 
 arytenoid cartilage. 
 
 The Inner Surface of the cricoid 
 cartilage is smooth, and lined with 
 mucous membrane. 
 
 The ArTtenoid Cartilages (cartil- 
 agines arytaenoideae) (Figs. 969, 
 972, and 976).— The arytenoid 
 cartilages are so called from the 
 resemblance they bear, when ap- 
 proximated, to the mouth of a 
 pitcher {a.i>bxmva, a pitcher). They 
 are two in number, and situated 
 at the upper border of the cricoid 
 cartilage, at the back of the larynx 
 in the interval between the poste- 
 rior borders of the alae of the thy- 
 roid cartilages. Each cartilage is 
 in form a three-sided pyramid, and 
 presents for examination three sur- 
 faces, a base, and an apex. 
 
 The Posterior Surface is trian- 
 gular, smooth, concave, and gives 
 attachment to the transverse por- 
 tion of the Arytenoid muscle. 
 
 The Anterior or External Surface 
 is somewhat convex and rough. It 
 presents, near its apex, a small 
 elevation, the colliculus ; from this a 
 ridge (crista arcuata) passes back- 
 ward and then forward and down- 
 ward into a sharp-pointed process, the vocal process. This ridge separates a 
 deep depression above, the fovea triangularis, from a broader and shallower depres- 
 sion below, the fovea oblonga. A short distance above the base a small tubercle 
 gives origin to the ligament of the false vocal cord, the superior thyro-arytenoid 
 ligament. To the outer part of the ridge, as well as the surface above and below, 
 is attached the Thyro-arytenoid muscle. 
 
 The Internal Surface is narrow, smooth, and flattened, covered by mucous 
 membrane, and forms the lateral boundary of the respiratory part of the glottis. 
 
 Posterior 
 surface. 
 
 Thyroid. 
 
 Cornicula laryngis. 
 Cuneiform cartilage. -^^^ ^ « 
 
 f J^ ^ 
 
 Arytenoid, l^ji^ 
 
 Insertion of 
 
 CRICO-ARYTENOIDEUS 
 POSTICUS ET LATERALIS 
 
 Cricoid. 
 Articular facet for 
 arytenoid cartilage. 
 
 Articular facet for 
 inferior cornu of 
 thyroid cartilage. 
 
 Fig. 969. — The cartilages of the larynx. Posterior view. 
 
 Arytenoid cartilages, base. 
 
THE LARYNX 1365 
 
 The Base (basis) of each cartilage is broad, and presents a concave smooth sur- 
 face, for articulation with the cricoid cartilage. Two of its angles require special 
 mention: the external angle, which is short, rounded, and prominent, projects 
 backward and outwartl, and is termed the muscular process (processus muscularis), 
 from receiving the insertion of the Posterior and Lateral crico-arytenoid muscles. 
 The anterior angle, also prominent, but more pointed, projects horizontally forward, 
 and gives attachment to the inferior thy ro- arytenoid ligament, the supporting liga- 
 ment of the true vocal cord. This angle is called the vocal process (proce^^ws vocalis). 
 
 The Apex of each cartilage is pointed, curved backward and inward, and sur- 
 mounted by a small conical, cartilaginous-nodule, the comiculum laryngis, articu- 
 lated with or united to the arytenoid cartilage. 
 
 The Comicula Laryngis or Cartilages of Santorini (cartilagines corniculatae) (Figs. 
 969 and 975) . — The cornicula laryngis are two small conical nodules, consisting of 
 white fibro-cartilage, which articulate with the summit of the arytenoid cartilages 
 and serve to prolong them backward and inward. To them are attached the aryteno- 
 epiglottidean folds. They are sometimes united to the arytenoid cartilages. 
 
 The Cuneiform Cartilages or Cartilages of Wrisberg (cartilagines cuneiformes) 
 (Figs, 969 and 971). — The cuneiform cartilages are two small, elongated, cartil- 
 aginous bodies, placed one on each side, in the fold of mucous membrane which 
 extends from the apex of the arytenoid cartilage to the side of the epiglottis, and is 
 called the aryteno-epiglottidean fold (plica aryepiglottica) (Fig. 971) ; they give 
 rise to small whitish elevations on the inner surface of the mucous membrane, 
 just in front of the arytenoid cartilages. 
 
 The Epiglottis or the Cartilage of the Epiglottis (cartilago epiglottica) (Figs. 967, 969^, 
 970, 971, 972, and 975). — The epiglottis is a thin, flexible lamella of fibro-cartilage, 
 of a yellowish color, shaped like a leaf, and placed behind the tongue in front of 
 the superior opening of the larynx. Its free extremity, which is directed upward, 
 is broad and rounded, and often notched; its attached part (petiolus epiglottidis) 
 is long, narrow, and connected to the receding angle between the alae of the 
 thyroid cartilage, just below the median notch, by a long, narrow ligamentous 
 band, the thjrro-epiglottic ligament (ligamentum thyreoepiglotticum) (Fig. 972). It 
 is also connected to the posterior surface of the body of the hyoid bone by an 
 elastic ligamentous band, the hyo -epiglottic ligament (ligamentum hyoepiglotticum) . 
 
 Its Anterior or Lingual Surface is curved forward, toward the tongue, and cov- 
 ered at its upper, free part by mucous membrane, which is reflected on to the 
 sides and base of the organ, forming a median and two lateral folds, the glcsso- 
 epiglottidean folds (plicae glossoepiglotticae) (Fig. 971). The median glosso-epiglot- 
 tidean fold (plica glossoepiglottica mediana) contains the elastic glosso-epiglottic 
 ligament (ligamentum glossoepiglotticum) . Each lateral glosso-epiglottidean fold 
 (plica glossoepiglottica lateralis) runs from the front and side of the base of the 
 epiglottis to the side of the tongue. The depression between the epiglottis and 
 the base of the tongue on each side of the median fold is named the vallecula 
 epiglottica. The lower part of the anterior surface of the epiglottis lies behind the 
 hyoid bone, the thyro-hyoid membrane, and upper part of the thyroid cartilage, 
 but is separated from these structures by a mass of fatty tissue. 
 
 Its Posterior or Laryngeal Surface is smooth, concave from side to side, concavo- 
 convex from above downward; its lower part projects backward as an elevation, 
 the tubercle or cushion (tuberculum epiglotticum) (Fig. 970) ; when the mucous mem- 
 brane is removed, the surface of the cartilage is seen to be studded with a number 
 of small mucous glands, which are lodged in little pits upon its surface. To its 
 sides the aryteno-epiglottidean folds (plicae aryepiglotticae) are attached (Fig. 971). 
 
 Structure. — The cuneiform cartilages, the epiglottis, and the apices of the 
 arytenoids are composed of yellow elastic cartilage, which shows little tendency to 
 calcification; on the other hand, the thyroid, cricoid, and the greater part of the 
 
1366 THE ORGANS OF VOICE AND BESPIBATION 
 
 arytenoids consist of hyaline cartilage, and become more or less ossified as age 
 advances. Ossification commences about the twenty-fifth year in the thyroid car- 
 tilage, somewhat later in the cricoid and arytenoids; by the sixty-fifth year these 
 cartilages may be completely converted into bone. The cornicula laryngis consist 
 of white fibro-cartilage, which becomes osseous about the seventieth year. 
 
 Ligaments, Joints, and Membranes of the Larjmx. — The ligaments of the larynx 
 are extrinsic — i. e., those connecting the thyroid cartilage and epiglottis with the 
 hyoid bone, and the cricoid cartilage with the trachea; and intrinsic, those which 
 connect the several cartilages of the larynx to each other. 
 
 The ligaments connecting the thyroid cartilage with the hyoid bone are three 
 in number — the thyro-hyoid membrane, and the two lateral thyro-hyoid ligaments. 
 
 The Thyro-hyoid or Hyo-th3n:oid Membrane or Ligament {riiemhrana hyothyreoidea) 
 (Fig. 972) is a broad, fibro-elastic, membranous layer, attached below to the 
 upper border of the thyroid cartilage, and above to the posterior border of the 
 body and greater cornua of the hyoid bone, passing behind the postero-inferior 
 surface of the hyoid, and being separated from this surface by a synovial bursa 
 (bursa m. sternohyoidei) , which facilitates the upward movement of the larynx 
 during deglutition. The membrane is thicker in the middle line than at either 
 side. This thickening is due to elastic fibres, and constitutes the middle thjrro- 
 hyoid ligament (ligamentum hyothyreoideum medium). On each side the posterior 
 extremity of the membrane is thickened by elastic fibres, constituting the lateral 
 thjnro-hyoid ligament {ligamentum hyothyreoideum laterale). The thyro-hyoid 
 membrane is pierced on each side by the superior laryngeal vessels and the 
 internal laryngeal nerve. The anterior surface of the thyro-hyoid membrane is 
 in relation with the Thyro-hyoid, Sterno-hyoid, and Omo-hyoid muscles and with 
 the body of the hyoid bone. The two lateral ligaments are rounded, elastic cords, 
 which pass between the superior cornua of the thyroid cartilage and the extremi- 
 ties of the greater cornua of the hyoid bone. A small cartilaginous nodule {car- 
 tilago triticea), sometimes bony, is frequently found in each. 
 
 The Membrana Quadrangularis is an elastic membrane containing numerous 
 glands. The fibres of the membrane run in part downward and in part down- 
 ward and backward. The membrane on each side arises in front and above at 
 the lateral margin of the cartilage of the epiglottis, below at the posterior surface 
 of the angle of the thyroid cartilage and becomes attached behind to the cornicula 
 laryngis and to the inner margins of the arytenoid cartilages.^ The membranes 
 converge below and medianward. The ligamentum ventriculare is the superior 
 end of the membrane (Spalteholz) . The fibres constituting the ligamentum ven- 
 triculare are given off at the thyroid cartilage above the ligamentum vocale and 
 pass horizontally backward to the medial margin of the fovea triangularis of the 
 arytenoid cartilage.^ The epiglottis is connected to the tongue by the three 
 glosso-epiglottidean folds of mucous membrane, which may also be considered 
 as extrinsic ligaments of the epiglottis. 
 
 The Glosso-epiglottidean Folds or Ligaments (plicae epiglotticae) (Fig. 971) num- 
 ber three. The middle glosso-epiglottidean fold (plica glossoepigloitica mediana) 
 passes from the middle of the anterior free surface of the epiglottis to the base 
 of the tongue. It contains the glosso -epiglottic ligament. The lateral glosso- 
 epiglottidean or the phar3mgo-epiglottidean fold (plica glossoepigloitica lateralis) 
 on each side passes from the side of the epiglottis to the side of the base of the 
 tongue and to the pharyngeal wall. On each side between the median and lateral 
 folds is a depression, the vallecula epiglottica. 
 
 The Hyo-epiglottic Ligament ((ligamentum hyoepiglotticum) is an elastic band, 
 which extends from the anterior surface of the epiglottis, near its apex, to the 
 
 I l^*?*^ Atlas of Human Anatomy. By Werner Soalteholz. Translated and edited by Lewellys F. Barker. 
 bpalteholz s Hand Atlas of Human Anatomy. Translated and edited by Lewellys F. Barker. 
 
THE LARYNX 
 
 1367 
 
 upper border of the body of the hyoid bone. The epiglottis is attached to the 
 thyroid cartilage, below and behind the superior thyroid notch, by the strong 
 and elastic thyro-epiglottic ligament (ligamentum thyreoepiglotticum) (Fig. 972). 
 Between the epiglottis, the hyo-epiglottic ligament and the thyro-hyoid membrane 
 is a triangular space containing fat on each side of the median line. 
 
 The ligaments connecting the thyroid cartilage to the cricoid are also three in 
 number — the crico-thjnroid membrane and the capsular ligaments. 
 
 The Crico-th3n:oid Membrane (conii^ elasticus) (Figs.968 and 975) is an elastic mem- 
 brane which passes radially from the posterior surface of the angle of the thyroid 
 cartilage to the upper margin of the arch of the cricoid cartilage and to the vocal 
 processes of the arytenoid cartilages. It is composed mainly of yellow elastic 
 tissue. It consists of three parts, a central triangular portion and two lateral 
 portions. The central part {ligamentum cricothyreoideum medium) is thick and 
 strong, narrow above and broadening out below. It connects together the con- 
 tiguous margins of the thyroid and cricoid cartilages. It is convex, concealed on 
 each side by the Crico-thyroid muscle, but subcutaneous in the middle line; it is 
 crossed horizontally by a small anastomotic arterial arch, formed by the junction 
 of the two crico-thyroid arteries. The lateral portions are thinner and lie close 
 under the mucous membrane of the larynx. They extend from the superior 
 border of the cricoid cartilage to the inferior margin of the true vocal cords with 
 which they are continuous. On each side are the uppermost fibres from the 
 inferior thyro-arytenoi^ ligament (ligamentum vocale). 
 
 The lateral portions are lined internally by mucous membrane, and are sepa- 
 rated from the thyroid cartilage by the lateral Crico-arytenoid and Thyro-aryte- 
 noid muscles. This membrane 
 and the muscles just men- 
 tioned reduce greatly the inte- 
 rior of the larynx. The crico- 
 thyroid membrane with the 
 membrana quadrangularis con- 
 stitute the membrana elastica 
 laryngis. 
 
 The Crico-th37roid Articulation 
 (articulatio cricothyreoidea) (Fig. 
 968) , on each side of the inferior 
 cornu of the thyroid, with the 
 cricoid cartilage on each side. 
 A loose synovial membrane (cap- 
 sula articularis cricothyreoidea) 
 encloses the articulation. 
 
 The synovial capsule is 
 strengthened by the ligamenta 
 ceratocricoidea,which pass from 
 the lesser cornu of the thyroid 
 to the lamina of the cricoid 
 cartilage. 
 
 The Crico-arytenoid Articula- 
 tion (articulatio cricoarytae- 
 
 noidea) (Fig. 969) on each side is between the articular surface of the arytenoid 
 cartilage and the arytenoid articular surface of the cricoid cartilage. 
 
 The ligaments connecting the arytenoid cartilages to the cricoid are on each 
 side a capsular ligament (capsula articularis cricoarytaenoidea) and a posterior 
 crico-arytenoid ligament (ligamentum cricoarytaenoideum posterius). The capsular 
 ligaments are thin and loose capsules attached to the margin of the articular 
 
 ARYTENO- 
 EPIGLOTTIDEUS 
 
 CRIC 
 THYREOIDEI 
 
 LARYNGEAL 
 SACCULE 
 
 NFERIOR 
 VOCAL CORD 
 
 Fig. 970. — Coronal section of larynx, rear view of front half. 
 (Testut.) 
 
1368 THE ORGANS OF VOICE AND BESPIBATION 
 
 surfaces ; they are lined internally by synovial membrane. The posterior crico- 
 arytenoid ligaments extend from the cricoid to the inner and back part of the base 
 of the arytenoid cartilage. 
 
 The Orico-tracheal Ligament (ligamentum cricotracheale) connects the cricoid 
 cartilage with the first ring of the trachea. It resembles the fibrous membrane 
 which connects the cartilaginous rings of the trachea to each side. 
 
 There is on each side an articulation between the arytenoid cartilage and the 
 cartilage of Santorini {synchondrosis arycorniculala). The cartilage of Santorini is 
 somewhat movable and is fixefl to the arytenoid by lax connective tissue. From 
 each cartilage of Santorini a band of connective tissue runs down to the lamina 
 of the cricoid cartilage and to the pharyngeal mucous membrane. Beneath the 
 arytenoid muscles the ligaments from the two sides join and pass down together. 
 Thus is formed a Y-shaped ligament called the ligamentum comiculopharyngeum. 
 The portion between the cricoid cartilage and the mucous membrane of the 
 pharynx is sometimes called the ligamentum cricopharjmgeum. 
 
 Interior of the Larynx (Figs. 970, 971, and 972).— The cavity of the larynx 
 (cavum laryngis) extends from the superior aperture of the larynx to the lower 
 border of the cricoid cartilage. It is divided into two parts by the projection 
 inward of the true vocal cords, between which is a narrow triangular fissure or 
 chink, the rima glottidis. It is further subdivided by the false vocal cords. So 
 we consider the larynx as divided into a portion above the false cords, a por- 
 tion between the false and true vocal cords, and a portion below the true cords. 
 The entrance of the first compartment is the superior aperture of the larynx. 
 
 The Superior Aperture of the Larjmx {aditus laryngis). — The superior aperture 
 of the larynx (Figs. 970 and 971) is a triangular or cordiform opening, wide in front, 
 narrow behind, and sloping obliquely downward and backward. It is bounded, 
 in front, by the epiglottis; behind, by the apices of the arytenoid cartilages and 
 the cornicula laryngis ; and laterally, by a fold of mucous membrane, enclosing 
 ligamentous and muscular fibres, stretched between the sides of the epiglottis 
 and the apices of the arytenoid cartilages; these are the aryteno-epiglottidean 
 folds (Figs. 971 and 972), on the margins of which the cuneiform cartilages form 
 more or less distinct whitish prominences. 
 
 The small gap between the cartilages of Santorini is called the incisura inter- 
 arytaenoidea. On the pharynx, on either side of the posterior portion of the superior 
 aperture of the larynx, is a recess, called the sinus pyriformis. 
 
 Upper Compartment or Vestibule of the Laryngeal Ca,witj(vestibulum laryngis) (Figs. 
 970 and 972) . — The vestibule is the portion between the superior opening and the 
 false vocal cords. It is much narrower below than above. It is bounded anteriorly 
 by the mucous membrane-covered epiglottis. The lower part of the epiglottis 
 exhibits a prominence called the cushion or tubercle {tvberculum epiglotticum) (Fig. 
 970) . The lateral wall of the vestibule on each side is the aryteno-epiglottidean fold 
 (plica aryepiglottica) (Fig. 972), which extends from the summit of the arytenoid 
 cartilage forward, upward, and outward to the margin of the epiglottis, and which 
 contains fibres of the Thyro-epiglottideus and Arytenoideus muscles (muscidus 
 arytaenoepiglottidean). Near the posterior end of the fold are two trivial elevations : 
 the anterior elevation is caused by the prominence of the cuneiform cartilage, and 
 is called the cuneiform tubercle of Wrisberg (tuberculum cuneiforme [Wrisbergi]) ; the 
 posterior elevation is caused by the anterior margin of the arytenoid cartilage and 
 the cartilage of Santorini, and is called the comical tubercle of Santorini {tuberculum 
 corniculatum [Santorini]). Between these elevations is a groove, the filtrum ven- 
 triculi of Merkel, which passes into the space between the false and true vocal cords. 
 The anterior elevation passes into the false vocal cord, the posterior elevation 
 into the true vocal cord. The posterior portion of the laryngeal vestibule is the 
 narrow space between the upper portions of the arytenoid cartilages. 
 
THE LARYNX 
 
 1369 
 
 The Middle Compaxtment of the Larynx (Figs. 970 and 972) . — This lies between the 
 false vocal cords above and the true vocal cords below. It is the smallest of the laryn- 
 geal compartments. It opens into the vestibule by the way of the gap between the 
 false vocal cords, which is called the false glottis ; it opens into the lower compart- 
 ment of the larynx by way of the space between the true vocal cords, the true glottis. 
 
 The True Glottis. — The true glottis is the apparatus for producing tone and is 
 formed by the true vocal cords. 
 
 The Chink of the Glottis {rima glottidis) (Figs. 970 and 971).— The chink of the 
 glottis is the elongated fissure or chink between the inferior or true vocal cords in 
 front, and between the bases and vocal processes of the arytenoid cartilages behind. 
 It is therefore frequently subdivided into an anterior, interligamentous or vocal por- 
 tion, the glottis vocalis ('pars intermemhranacea) , and a posterior, intercartilaginous 
 or respiratory portion, the glottis respiratoria {jpars intercartilaginea). Posteriorly it is 
 limited by the mucous membrane passing between the arytenoid cartilages. The 
 vocal portion averages about three-fifths of the length of the entire aperture. It 
 is the narrowest part of the cavity of the larynx, and its level corresponds to the 
 
 APEX OF SUP. HORN OF 
 THYROID CARTILAGE 
 
 LUM 
 S 
 El FORM 
 RTILAGE 
 TENO-EPIGLOT- 
 
 OIAN FOLD 
 PEX OF GREAT 
 ORN OF HVOlO 
 
 LATERAL GLOSSO- MIDDLE GLOSSO- 
 
 CPIGLOTTIDIAN FOLD EPIGLOTTIDIAN FOLD 
 
 Fig. 971. — Larynx, viewed from above. 
 
 (Testut.) 
 
 bases of the arytenoid cartilages. Its length, in the male, measures rather less 
 than an inch (20 to 25 mm.); in the female it is shorter by 5 or 6 mm., or three 
 lines. The width and shape of the rima glottidis vary with the movements of the 
 vocal cords and arytenoid cartilages during respiration and phonation. In the 
 condition of rest — i. e., when these structures are uninfluenced by muscular action, 
 as in quiet respiration, the glottis vocalis is triangular, with its apex in front and 
 its base behind, the latter being represented by a line about 8 mm. long, connect- 
 ing the anterior extremities of the vocal processes, while the inner surfaces of the 
 arytenoids are parallel to each other, and hence the glottis respiratoria is rectan- 
 gular. During extreme adduction of the cords, as in the emission of a high note, 
 the glottis vocalis is reduced to a linear slit by the apposition of the cords, while 
 the glottis respiratoria is triangular, its apex corresponding to the anterior extrem- 
 ities of the vocal processes of the arytenoids, which are approximated by the 
 inward rotation of the cartilages. Conversely in extreme abduction of the cords, 
 as in forced inspiration, the arytenoids and their vocal processes are rotated out- 
 ward, and the glottis respiratoria is triangular in shape, but with its apex directed 
 backward. In this condition the entire glottis is somewhat lozenge-shaped, the 
 sides of the glottis vocalis diverging from before backward, those of the glottis 
 
1370 
 
 THE ORGANS OF VOICE AND RESPIRATION 
 
 respiratoria diverging from behind forward, the widest part of the aperture corre- 
 sponding with the attachment of the cords to the vocal processes/ 
 
 The Superior or False Vocal Cords(p/?cae ventriculares) (Figs, 970, 971, and 972), so 
 called because they are not directly concerned in the production of the voice. Each 
 is a thick fold of mucous membrane, enclosing a narrow band of fibrous tissue, the 
 superior thyro-ar3rtenoid ligament {ligamentum ventriculare) , which is attached in 
 front to the angle of the thyroid cartilage immediately below the attachment of the 
 epiglottis, and behind to the anterior surface of the arytenoid cartilage. The lower 
 border of this ligament, enclosed in mucous membrane, forms a free crescentic 
 margin, which constitutes the upper boundary of the ventricle of the larynx. The 
 false vocal cord contains the lower part of the membrana quadrangularis with 
 the ligamentum ventriculare, the muscle ventricularis and laryngeal glands. 
 
 The Inferior or True Vocal Cords (plicae vocales) (Figs. 970, 971, 972, and 976), so 
 called from their being concerned in the production of sound. Each is a strong 
 
 \ 
 
 
 VJ\\ EPIQl-OTTIO 
 ^^1 CARTILAGE 
 
 •"HYRO-HYO 
 
 THYRO-EPIGLOT 
 TIC LIGAMENT 
 
 ARYTENO-EPI- 
 GLOTTIDIAN FOLD 
 
 Fig. 972.— Sagittal section of larynx, right half. (Testut.) 
 
 band, the inferior thyro-arytenoid ligament (Zijamen/ww voca/e) , covered on its sur- 
 face by a thin layer of mucous membrane. Each ligament consists of a band of 
 yellow elastic tissue, attached in front to the depression between the alae of the 
 thyroid cartilage, and behind to the anterior angle of the base of the arytenoid. 
 This angle is called the vocal process. Its lower border is continuous with the 
 thin lateral part of the crico-thyroid membrane. Its upper bortler forms the lower 
 boundary of the ventricle of the larynx. Externally, the Thyro-arytenoideus 
 muscle lies parallel with it. It is covered internally by mucous membrane, which is 
 extremely pale, thin, and closely adherent to its surface. The upper margin of 
 the true vocal cord is covered with mucous membrane, and is the lower boundary 
 of the ventricle of the larynx. Over the vocal process it is yellowish {macula 
 flava). The true vocal cord contains the upper part of the crico-thyroid mem- 
 brane with the ligamentum vocale and the muscle vocalis. 
 
 ^ On the shape of the rima glottidis, in the various conditions of breathing and speaking, see Czermak, On the 
 Laryngoscope, translated for the New Sydenham Society. — Ed. of 15th English edition. 
 
THE LARYNX 
 
 1371 
 
 The Ventricle of the Larynx or Laryngeal Sinus (ventricidus laryngis [Morgagnii]) 
 (Figs. 970 and 972) is an oblong fossa, situated between the superior and inferior 
 vocal cords on each side, and extending nearly their entire length. This fossa is 
 bounded, above, by the free crescentic edge of the superior vocal cord; below, by 
 the straight margin of the inferior vocal cord; externally, by the mucous mem- 
 brane covering the corresponding Thyro-arytenoideus muscle. The anterior part 
 of the ventricle leads up by a narrow opening into a caecal pouch of mucous 
 membrane of variable size, called the lar3mgeal pouch. 
 
 The Laryngeal Saccule or Pouch (appendix ventriculi) (Fig. 970), or laryngeal 
 pouch, is a membranous sac, placed between the superior vocal cord and the inner 
 surface of the thyroid cartilage, occasionally extending as far as its upper border 
 or even higher; it is conical in form, and curved slightly backward. On the surface 
 of its mucous membrane are the openings of sixty or seventy mucous glands, which 
 are lodged in the submucous areolar tissue. This sac is enclosed in a fibrous cap- 
 sule, continuous below with the superior thyro-arytenoid ligament; its laryngeal 
 surface is covered by the Aryteno-epiglottideus inferior muscle (compressor sacculi 
 laryngis of Hilton) ; while its exterior is covered by the Thyro-arytenoideus and 
 Thyro-epiglottideus muscles. These muscles compress the sacculus laryngis, and 
 discharge the secretion it contains upon the vocal cords, the surfaces of which it is 
 intended to lubricate. 
 
 STCRNO- 
 
 THYREOtDEUS 
 
 Fig. 973. — Muscles of larynx, front view. The sterno- 
 thyroids and right thyro-hyoid have been removed. 
 (Testut.) 
 
 Fig. 974. — Muscles of larynx, from behind. 
 
 (Testut.) 
 
 The Lower Compartment of the Larynx (Figs. 970 and 972) . — This space is just 
 beneath the true vocal cords and leads into the trachea. It is called the additus glot- 
 tidis inferior. Above, on cross-section, it is oval; below, it is round. It is bounded 
 by the inner surface of the crico-thyroid membrane and the cricoid cartilage. 
 
 Muscles of the Larynx (muscuH laryngis). — We do not consider all muscles 
 which are attached to laryngeal cartilages as laryngeal muscles. Some muscles 
 so attached in reality belong to other regions, for instance, the Inferior constric- 
 tor, the Stylo-pharyngeus, the Sterno-thyroid, the Thyro-hyoid, and the Palato- 
 pharyngeus. The muscles which really belong to the larynx are called intrinsic. 
 
 Four muscles of the vocal cords and rima glottidis are paired and one is single. 
 
1372 
 
 THE ORGANS OF VOICE AND RESPIRATION 
 
 The paired muscles are the crico-thyroid, the posterior crico-arytenoid, the 
 lateral crico-arytenoid, and the thyro-arytenoid. The single muscle is the aryte- 
 noideus. 
 
 A Crico-thyroid (w. cricothyreoideus) (Figs. 968, 970, and 973) is placed on each 
 side. It is triangular in form, and situated at the forepart and side of the cricoid 
 cartilage. It arises from the front and lateral part of the cricoid cartilage; its 
 fibres diverge, passing obliquely upward and outward to be inserted into the lower 
 border of the thyroid cartilage and into the anterior border of the lower cornu. 
 
 The inner borders of these two muscles are separated in the middle line by a 
 triangular interval occupied by the central part of the crico-thyroid membrane. 
 The Posterior Crico-arytenoid (m. cricoarytaenoideus posterior) {Figs. 974, 975, and 
 
 976), a paired muscle, arises from the 
 broad depression occupying each lat- 
 eral half of the posterior surface of the 
 cricoid cartilage; its fibres pass up- 
 ward and outward, converging to be 
 inserted into the outer angle (muscu- 
 
 FiG. 975. 
 
 -Muscles of larynx. Side view. Right ala 
 of thyroid cartilage removed. 
 
 Fig. 976. 
 
 -Interior of the larynx, seen from above. 
 (Enlarged.) 
 
 lar process) of the base of the arytenoid cartilage. The upper fibres are nearly 
 horizontal, the middle oblique, and the lower almost vertical.^ 
 
 The Ar3rtenoideus (Figs. 972, 974, 975, and 976) is a single muscle filling up the 
 posterior concave surface of the arytenoid cartilages. It arises from the posterior 
 surface and outer border of one arytenoid cartilage, and is inserted into the corre- 
 sponding parts of the opposite cartilage. It consists of three planes of fibres, two 
 oblique and one transverse. The oblique fibres (m. arytaenoideus obliquus), the 
 most superficial, form two fasciculi, which pass from the base of one cartilage to 
 the apex of the opposite one. The transverse fibres (m. arytaenoideus transversus) , 
 the deepest and most numerous, pass transversely across between the two cartil- 
 ages; hence the Arytenoideus was formerly considered as three muscles, the trans- 
 
 ' Merkel, of Leipzig, has described a muscular slip which occasionally extends between the outer border of the 
 posterior surface of the cricoid cartilage and the posterior margin of the inferior cornu of the thyroid ; this he 
 calls the " Musculus kerato-cricoideus." It is not found in every larynx, and when present exists usually only 
 on one side, but is occasionally found on both .sides. Sir William Turner (Edinburgh Medical Journal, February, 
 1860) states that it is found in about one case in five. Its action is to fix the lower horn of the thyroid cartilage 
 backward and downward, opposing in some measure the part of the Crico-thyroid muscle, which is connected to 
 the anterior margin of the horn. — Ed. of 15th English edition. 
 
THE LARYNX 1373 
 
 verse and the two oblique. A few of the oblique fibres are around the outer margin 
 of the cartilage, and blend with the Thyro-arytenoid in the aryteno-epiglottidean 
 fold, and are called the Aryteno-epiglottideus muscles. 
 
 In order to expose the rest of the muscles of the larynx the thyroid cartilage 
 of one side must be removed. Begin by taking away the crico-thyroid muscle, 
 then dividing the lateral thyro-hyoid ligament; disarticulate the inferior cornu of 
 the thyroid cartilage from the cricoid cartilage, then carefully cut through the 
 thyroid cartilage a short distance from its union with its twin. The following 
 muscles will then be exposed after a little cleaning: the Lateral crico-thyroid, 
 the Thyro-arytenoid, the Thyro-epiglottideus. 
 
 The Lateral Crico-arytenoid {m. cricoarytenoideus lateralis) (Figs. 975 and 976), 
 a paired muscle, is smaller than the preceding, and of an oblong form. It arises 
 from the upper border of the side of the cricoid cartilage, and, passing obliquely 
 upward and backward, is inserted into the muscular process of the arytenoid 
 cartilage in front of the posterior Crico-arytenoid muscle. 
 
 The Thyro-arytenoid (m. thyroarytaenoideus) (Figs. 975 and 976), a paired muscle, 
 is broad and flat. It lies parallel with the outer side of the true vocal cord. It 
 arises in front from the lower half of the receding angle of the thyroid cartilage, 
 and from the crico-thyroid membrane. Its fibres pass backward and outward, to 
 be inserted into the base and anterior surface of the arytenoid cartilage. This 
 muscle consists of two fasciculi.^ The inner or inferior fasciculus (m. vocalis), the 
 thicker, is prismatic in shape and is inserted into the vocal process of the aryte- 
 noid cartilage, and into the adjacent portion of its anterior surface; it lies parallel 
 with the true vocal cord, to which it is adherent. This fasciculus on its deeper 
 surface gives off some fibres which are attached to the true vocal cord. These 
 are called the ary-vocalis (Ludwig). The outer or superior fasciculus, the thinner, 
 is inserted into the anterior surface and outer border of the arytenoid cartilage 
 above the preceding fibres; it lies on the outer side of the sacculus laryngis, imme- 
 diately beneath the mucous membrane.^ 
 
 The muscles of the epiglottis are the — 
 
 Thyro-epiglottideus. Aryteno-epiglottideus superior. 
 
 Aryteno-epiglottideus inferior. 
 
 The Thyro-epiglottideus (w. thyroeyiglotticus) is a delicate fasciculus, which 
 arises from the inner surface of the thyroid cartilage, just external to the origin of 
 the Thyro-arytenoid muscle, of which it is sometimes described as a part, and 
 spreads over the outer surface of the sacculus laryngis; some of its fibres are lost 
 in the aryteno-epiglottidean fold, while the others are continued forward to the 
 margin of the epiglottis. 
 
 The Aryteno-epiglottideus (Figs. 970 and 975) is properly divided into two 
 muscles, a superior and an inferior. 
 
 The Ar3rteno-epiglottideus superior consists of a few delicate muscular fasciculi, 
 which arise from the apex of the arytenoid cartilages, and become lost in the 
 fold of mucous membrane, the aryteno-epiglottidean fold, extending between the 
 arytenoid cartilage and the side of the epiglottis. 
 
 The Aryteno-epiglottideus inferior, the Compressor sacculi laryngis of Hilton, arises 
 from the arytenoid cartilage, just above the attachment of the superior vocal cord ; 
 passing forward and upward, it spreads out upon the anterior surface of the epiglot- 
 tis. This muscle is separated from the preceding by an indistinct areolar interval.^ 
 
 ' Henle describes these two portions as separate muscles, under the names of the External and Internal thyro- 
 arytenoid. — Ed. of 15th English edition. 
 
 * Luschka has described a small but fairly constant muscle as the Arytenoideus rectus. It is attached below 
 to the po.sterior concave surface of the arytenf)id cartilage, beneath the Arytenoideus muscle, and, passing 
 upward, emerges at the upper border of this mu.scle, and is inserted into the posterior surface of the cartilage of 
 Santorini (Anatomy, by Hyrtl, p. 718). — En. of 15th English edition. 
 
 ^ MuscuLUS TRiTiCEO-OLOSsus. Bochdalek, .Ir. (Prager Vierteljahrsschrift, 1866, 2d part) describes a muscle 
 hitherto entirely overlooked, except by Henle, who makes a brief statement in his Anatomy, which arises from 
 the nodule of cartilage (corpus triticeum) in the posterior thyro-hyoid ligament, and passes forward and upward 
 to enter the tongue along with. the Hyo-glos.sus muscle. He met with this muscle eight times in twenty-two sub- 
 jects. It occurred in both sexes, sometimes on both sides, at others on one only. — Ed. of 15th English edition. 
 
1374 THE ORGANS OF VOICE AND RESPIRATION 
 
 Actions. — In considering the action of the muscles of the larynx, they may 
 be conveniently divided into two groups, viz.: 1. Those which open and close 
 the glottis. 2. Those which regulate the degree of tension of the vocal cords. 
 
 1. The muscles which open the glottis are the two Posterior crico-arytenoids; 
 and those which close it are the Arytenoideus and the two Lateral crico-arytenoids. 
 2. The muscles which regulate the tension of the vocal cords are the two Crico- 
 thyroids, which tense and elongate them, and the two Thyro-arytenoids, which 
 relax and shorten them. The Thyro-epiglottideus is a depressor of the epiglottis, 
 and the Aryteno-epiglottideus, superior and inferior, constrict the superior aper- 
 ture of the larynx. 
 
 The Posterior crico-arytenoids separate the chordae vocales, and consequently open the glottis, 
 by rotating the arytenoid cartilages outward around a vertical axis passing through the crico- 
 arytenoid joints, so that their vocal processes and the vocal cords attached to them become widely 
 separated. 
 
 The Lateral crico-arytenoids close the glottis by rotating the arytenoid cartilages inward so 
 as to approximate their vocal processes. 
 
 The Arytenoideus muscle approximates the arytenoid cartilages, and thus closes the opening 
 of the glottis, especially at its back part. 
 
 The Crico-thyroid muscles produce tension and elongation of the vocal cords. This is eflfected 
 as follows: the thyroid cartilage is fixed by its extrinsic muscles; then the Crico-thyroid muscles, 
 when they act, draw upward the front of the cricoid cartilage, and so depress the posterior por- 
 tion, which carries with it the arytenoid cartilages, and thus elongate the vocal cords. 
 
 The Thyro-arytenoid muscles, consisting of two parts having different attachments and 
 different directions, are rather complicated as regards their action. Their main use is to draw 
 the arytenoid cartilages forward toward the thyroid, and thus shorten and relax the vocal cords. 
 But, owing to the connection of the inner portion with the vocal cord, this part, if acting sepa- 
 rately, is supposed to modify its elasticity and tension, and the outer portion, being inserted 
 into the outer part of the anterior surface of the arytenoid cartilage, may rotate it inward, and 
 thus narrow the rima glottidis by bringing the two cords together. 
 
 The Thyro-epiglottidei may depress the epiglottis; they assist in compressing the sacculi 
 laryngis. The Aryteno-epiglottideus superior constricts the superior aperture of the larynx, 
 when it is drawn upward, during deglutition. The aryteno-epiglottideus inferior, together with, 
 some fibres of the Thyro-arytenoidei, compress the sacculus laryngis. 
 
 The Mucous Membrane of the Laxynx is continuous above with that lining the 
 mouth and pharynx, and it is prolonged through the trachea and bronchi into the 
 lungs. It lines the posterior surface and the anterior part of the upper surface of 
 the epiglottis, to which it is closely adherent. In the rest of the larynx, above the 
 true vocal cords, it is lax and rests upon a considerable submucous layer. The 
 mucous membrane, with the submucous coat, ligamentous and muscular fibres,, 
 forms the aryteno-epiglottidean folds, which folds are the lateral boundaries of the 
 superior aperture of the larynx. It lines the whole of the cavity of the larynx; 
 forms by its reduplication the chief part of the superior or false vocal cord ; and, 
 from the ventricle, is continued into the sacculus laryngis. It is then reflected 
 over the true vocal cords, where it is thin and very intimately adherent; covers 
 the inner surface of the crico-thyroid membrane and cricoid cartilage; and is 
 ultimately continuous with the lining membrane of the trachea. The forepart of 
 the anterior surface and the upper half of the posterior surface of the epiglottis, 
 the upper part of the aryteno-epiglottidean folds, and the true vocal cords are 
 covered by stratified squamous epithelium; the rest of the laryngeal mucous 
 membrane is covered by columnar ciliated cells. 
 
 The mucous membrane above the rima glottidis is extremely sensitive, and 
 during life the lightest touch of a foreign body produces cough. 
 
 Glands. — The mucous membrane of the larynx is furnished with numerous 
 muciparous glands, the orifices of which are found in nearly every part; they 
 are very numerous upon the epiglottis, being lodged in little pits in its substance; 
 they are also found in large numbers along the posterior margin of the aryteno- 
 epiglottidean fold, in front of the arytenoid cartilages, where they are termed the 
 
THE LARYNX 
 
 1375 
 
 arjrtenoid glands. They exist also in large numbers upon the inner surface of the 
 sacculus laryngis. None are found on the surface of the true vocal cords. 
 
 Vessels and Nerves. — The arteries of the larjmx (Fig. 977) are the larj^ngeal 
 branches derived from the superior and inferior thyroid. The superior laryngeal artery 
 from the superior th3a"oid courses along by the internal laryngeal nerve; the inferior 
 laryngeal artery from the inferior thyroid courses along with the recurrent laryngeal 
 nerve. The veins accompany the arteries; those accompanying the superior laryn- 
 geal artery join the superior thyroid vein which opens into the internal jugular 
 vein; while those accompanying the inferior laryngeal artery join the inferior 
 thyroid vein which opens into the innominate vein. The laryngeal lymphatics arise 
 from a network in the mucous membrane. This network is divisible into two 
 portions, a superior and an inferior, which are to be regarded as almost inde- 
 pendent areas. The superior region includes all of the "laryngeal mucous 
 membrane above the glottis, epiglottis, aryteno-epiglottidean folds, interarytenoid 
 region, and superior vocal cords."^ The inferior area is the laryngeal mucous 
 
 Superior 
 
 thyroid 
 
 artery. 
 
 Superior 
 
 —laryngeal 
 
 artery. 
 
 Fig. 977. — The origin and distribution of the arteriey of the larynx. (Luschka.) 
 
 membrane below the glottis. The lymphatics of one-half of the larynx do uut 
 communicate with those of the other half in the median line in front, but do 
 in the median iine behind. The eiferent vessels from the superior network 
 accompany the superior laryngeal artery, pierce the thyro-hyoid membrane, 
 and divide into three sets. One or two lymphatic vessels pass upward and 
 terminate in a gland slightly below the posterior belly of the Digastric muscle. 
 A group of vessels passes horizontally outward to terminate in the glands 
 situated on the internal jugular vein on a level with the bifurcation of the 
 common carotid artery. Another group descends and empties into the internal 
 jugular group of glands at a lower level than the horizontal vessels. Trunks from 
 the inferior network of the laryngeal mucous membrane form two groups. The 
 anterior or supracricoid group consists of three trunks which pass through the crico- 
 thyroid membrane, to empty into the pre-laryngeal glands, the pre-tracheal gland, 
 and the middle and lower 'deep cervical glands.^ The posterior group consists 
 
 1 Philio R. W. De Santi in the Lancet, June 18, 1904. 
 
 2 Poirier, Cun<So, Most, De Santi. 
 
1376 THE ORGANS OF VOICE AND BESPIBATION 
 
 of "from three to five trunks, which pass over the crico-tracheal fascia at the 
 junction of the lateral and posterior aspects of the trachea,"^ and terminate in 
 the recurrent glands about the recurrent laryngeal nerve. The nerves are derived 
 from the internal and external laryngeal branches of the superior laryngeal nerve, 
 from the inferior or recurrent lar3mgeal, and from the sympathetic. The internal 
 larvngeal nerve is almost entirely sensory, but some motor filaments are said to be 
 carried by it to the Arytenoideus muscle. It divides into a branch which is dis- 
 tributed to both surfaces of the epiglottis, a second to the aryteno-epiglottidean 
 folds, and a third, the largest, which supplies the mucous membrane over the 
 back of the larynx and communicates with the recurrent laryngeal. The external 
 laryngeal nerve supplies the Crico-thyroid muscle. The recurrent laryngeal 
 passes upward under the lower border of the Inferior constrictor, and enters the 
 larynx between the cricoid and thyroid cartilages. It supplies all the muscles of 
 the larynx except the Crico-thyroid and part of the Arytenoideus. The sensory 
 branches of the laryngeal nerves form subepithelial plexuses, from which fibres 
 ascend to end between the cells covering the mucous membrane. 
 
 Over the posterior surface of the epiglottis, in the aryteno-epiglottidean folds, 
 and less regularly in some other parts, taste-buds, similar to those in the tongue, 
 are found. 
 
 THE TRACHEA AND BRONCHI (Fig. 978). 
 
 The trachea or windpipe is a cartilaginous membranous, elastic, cylindrical 
 tube, flattened posteriorly, which extends from the lower part of the larynx, on a 
 level with the sixth cervical vertebra, to opposite the body of the fourth, or some- 
 times of the fifth, dorsal vertebra, where it divides (bifurcatio tracheae) into two 
 bronchi, one for each lung. This point is at the level of the spine of the fourth 
 dorsal vertebra. The trachea is found to be more deeply placed the lower down 
 it is examined. It is in the median line, deviating below a very little to the right 
 side. When a cross-section is made of the trachea it is seen that its anterior and 
 lateral walls are rounded, but its posterior wall is flat (Fig. 982). The largest 
 diameter of the tube is the middle; from this point the diameter diminishes toward 
 the bronchi and toward the laryngeal end. The trachea measures about four 
 inches and a half in length; its diameter from side to side is from three-quarters 
 of an inch to an inch, being always greater in the male than in the female. 
 
 Relations. — The anterior surface of the trachea is convex, and covered in the 
 neck, from above downward, by the isthmus of the thyroid gland, the inferior 
 thyroid veins, the arteria thyroidea ima (when that vessel exists), the Sterno-hyoid 
 and Sterno-thyroid muscles, the cervical fascia, and more superficially, by the 
 anastomosing branches between the anterior jugular veins: in the thorax it is 
 covered from before backward by the first piece of the sternum, the remains of the 
 thymus gland, the left innominate vein, the arch of the aorta, the innominate and 
 left common carotid arteries, and the deep cardiac plexus. Posteriorly, it is in 
 relation with the oesophagus ; laterally, in the neck, it is in relation with the com- 
 mon carotid arteries, the lateral lobes of the thyroid gland, the inferior thyroid 
 arteries, and recurrent laryngeal nerves; and, in the thorax, it lies in the upper 
 part of the interpleural space, that is, in the superior mediastinum, and is in relation 
 on the right to the pleura and right vagus, and near the root of the neck to the 
 innominate artery; on its left side are the recurrent laryngeal nerve, the aortic 
 arch, the left common carotid and subclavian arteries. 
 
 The Right Bronchus (bronchus dexter). — The unbranched portion of the right 
 bronchus, wider, shorter, and more vertical in direction than the left, is about 
 an inch in length, and enters the hilum of the right lung opposite the fifth dorsal 
 
 1 De Santi, in the Lancet, June 18, 1904. 
 
THE TRACHEA AND BRONCHI 
 
 1377 
 
 vertebra. It forms an angle to the median plane of about 29 degrees. The vena 
 azygos major arches over it from l^ehind ; and the right pulmonary artery lies below 
 and then in front of it. About three-quarters of an inch from its commencement 
 it gives off a branch to the upper lobe of the right lung. This is termed the 
 eparterial branch {ramus hronchialis eparterialis) , because it is given off above 
 the right pulmonary artery. The bronchus now passes below the artery, and is 
 
 Superior^ 
 Cornu. ' 
 
 Fig. 978.- 
 
 - Front view of cartilages of larynx; the trachea and bronchi (the right bronchus is not shown as 
 steep as it really is. 
 
 known as the hyparterial branch {ramus branchialis hyparterialis) . It divides 
 into two branches for the middle and lower lobs. 
 
 If a transverse section of the trachea is made a short distance above its point 
 of bifurcation, and a bird's-eye view taken of its interior (Fig. 982), the septum 
 placed at the bottom of the trachea and separating the two bronchi will be seen 
 to occupy the left of the median line, and the right bronchus appears to be a 
 more direct continuation than the left, so that any solid body dropping into the 
 trachea would naturally be directed toward the right bronchus. This tendency is 
 aided by the larger size of the right tube as compared with its fellow. This fact 
 
 87 
 
1378 
 
 THE ORGANS OF VOICE AND RESPIRATION 
 
 serves to explain why a foreign body in the trachea more frequently falls into the 
 right bronchus than into the left/ 
 
 The Left Bronchus (bronchus sinister). — The left bronchus is smaller and 
 longer than the right, being nearly two inches in length. It forms an angle to the 
 
 median plane of about 46 degrees. It is slightly 
 curved and enters the root of the left lung, oppo- 
 site the sixth dorsal vertebra, about an inch 
 lower than the right bronchus. It passes l^e- 
 neath the arch of the aorta, crosses in front of 
 the oesophagus, the thoracic duct, and the de- 
 scending aorta, and has the left pulmonary artery 
 lying at first above, and then in front of it. The 
 left bronchus has no branch corresponding to 
 the eparterial branch of the right bronchus, and 
 therefore it has been supposed by some that 
 there is no upper lobe to the left lung, but that 
 the so-called upper lobe corresponds to the 
 middle lobe of the right lung. The left bron- 
 chus does have an hyparterial branch. 
 
 When the main or stem bronchus enters the 
 lung on each side it appears to divide into nearly 
 equal branches at the root of the lung, but a 
 somewhat similar arrangement to what is found 
 in many animals may be made out where each 
 main bronchus passes downward and backward 
 toward the extremity of the lower lobe, and ends 
 near the posterior surface of the base of the lung, 
 a portion of pulmonary substance which is be- 
 tween the Diaphragm and the wall of the chest. 
 It gives off four branches, or lateral bronchi 
 {rami hronchiales) , at intervals in two directions, dorsally and ventrally, and, in 
 addition, accessory branches, which arise from the front of the bronchus and 
 pass mesially and dorsally into the inferior lobe. In the right bronchus the 
 first ventral branch supplies the middle lobe, the other three and all the dorsal 
 going to the lower lobe; in the left bronchus, the first ventral branch sup- 
 plies the middle lobe, the other three and all the dorsal going to the lower 
 lobe; in the left bronchus, the first central supplies the superior lobe, and all the 
 others, both ventral and dorsal, go to the lower lobe. The dorsal and ventral 
 branches divide into smaller branches, and these again into smaller branches or 
 bronchioles (Fig. 981). Each bronchiolus divides into minute branches (bronchioli 
 respiratorii) (Fig. 981), the walls of which show numerous areas of bulging called 
 alveoli (Fig. 981). From the bronchioli respiratorii come the terminal branches 
 of the bronchi. These terminal branches are the alveolar ducts (ductuli alveolares), 
 and they are bulged by numerous alveoli (Fig. 981). They connect by openings 
 at their termination with several cavities of irregular form, which are called atria. 
 Each atrium is connected with several or many larger cavities, known as sacculi 
 alveolares, air-cells, or air-sacs (infundihula). The entire surface of the air-sacs is 
 filled with small cavities, the pulmonary alveoli (alveoli pulmonis). An alveolar 
 duct with its branches forms a pulmonary lobule (lobulv^ pulmonis) (Fig. 980). 
 
 Structure of the Trachea. — The trachea is composed of imperfect cartilagin- 
 ous rings, fibrous membrane, muscular fibres, mucous membrane, and glands. 
 
 The Cartilages. — The cartilages vary from sixteen to twenty in number; each 
 forms an imperfect ring, which surrounds about two-thirds of the cylinder of the 
 
 Fio. 979.- 
 
 -Internal surface of the bronchi. 
 (Poirier and Charpy.) 
 
 ^ Reigel asserts that the entrance of a foreizn body into the left bronchus is bv no means so infrequent as ia 
 generally supposed. See also Med.-Chir. Transactions, vol. Ixxi. p. 121. ^Ed. oi 15th English edition. 
 
THE TRACHEA AND BRONCHI 
 
 1379 
 
 trachea, being imperfect behind, where the tube is completed by fibrous mem- 
 brane. The cartilages are placed horizontally above each other, separated by 
 narrow membranous intervals. They measure about two lines in depth, and half 
 a line in thickness. Their outer surfaces are flattened, but internally they are 
 convex, from being thicker in the middle than at the margins. Two or more of 
 the cartilages often unite, partially or completely, and are sometimes bifurcated 
 at their extremities. They are highly elastic, but sometimes become calcified in 
 advanced life. In the right bronchus the cartilages vary in number from six to 
 
 eight; in the left, from nine to twelve. They 
 are shorter and narrower than those of the 
 trachea. The peculiar cartilages are the first 
 and the last. 
 
 The First Cartilage is broader than the rest, 
 and sometimes divided at one end; it is con- 
 nected by fibrous membrane with the lower 
 
 NTERLOBULAR 
 
 ALVEOLI 
 DUCT 
 
 BRONCHIOLE 
 
 RESPIRATORY 
 BRONCHIOLE 
 
 Fig. 980. — A pulmonary lobule. (Poirier and 
 
 Charpy.) 
 
 Fig. 981. — The terminal bronchial tubes. The respiratory 
 bronchiole and alveoli. (Poirier and Charpy.) 
 
 Right. 
 
 border of the cricoid cartilage, with which or with the succeeding cartilage it is 
 sometimes blended. 
 
 The Last Cartilage is thick and broad in the middle, in consequence of its lower 
 border being prolonged into a triangular hook-shaped process which curves down- 
 ward and backward between the two bronchi. It terminates on each side in an 
 
 imperfect ring which encloses the com- 
 mencement of the bronchi. The cartil- 
 age above the last is somewhat broader 
 than the rest at its centre. 
 
 The Fibrous Membrane. — The cartil- 
 ages are enclosed in an elastic fibrous 
 membrane which forms a double layer, 
 one layer, the thicker of the two, passing 
 over the outer surface of the ring, the 
 other over the inner surface; at the 
 upper and lower margins of the cartilages 
 these two layers blend together to form a 
 single membrane, which connects the rings one with another. They are thus, as 
 it were, embedded in the membrane. In the space behind, between the extremi- 
 ties of the rings, the membrane forms a single distinct layer. 
 
 The Muscular Fibres. — The muscular fibres are disposed in two layers, longi- 
 tudinal and transverse 
 
 Fig. 982. — Transverse section of the trachea, just 
 above its bifurcation, with a bird's-eye view of the 
 interior. 
 
1380 THE ORGANS OF VOICE AND BE8PIBATI0N 
 
 The Longitudinal Fibres are the most external, and consist merely of a few scat- 
 tered longitudinal bundles of fibres. 
 
 The Transverse Fibres constitute the Trachealis muscle of Todd and Bowman. The 
 most internal form a thin layer which extends transversely between the ends of 
 the cartilages and the intervals between them at the posterior part of the trachea. 
 The muscular fibres are of the unstriped variety. 
 
 The Mucous Membrane. — The mucous membrane is continuous above with that 
 of the larynx, and below with that of the bronchi. Microscopically, it consists of 
 areolar and lymphoid tissue, and presents a well-marked basement-membrane, 
 supporting a layer of columnar, ciliated epithelium, between the deeper ends of 
 which are smaller triangular cells, the bases of which, often branched, are attached 
 to the basement-membrane. These triangular cells are mucus-secreting, and may 
 be seen as goblet-cells or chalice-cells when their contents have been discharged. 
 In the deepest part of the mucous membrane, and especially between the mucous 
 and submucous layers, longitudinally arranged fibres are very abundant and form 
 a distinct layer. 
 
 The Tracheal Glands (glandulae tracheales). — The tracheal glands are found in 
 great abundance at the posterior part of the trachea. They are racemose glands, 
 and consist of a basement-membrane lined by columnar mucus-secreting cells. 
 They are situated at the back of the trachea, outside the layer of muscular tissue, 
 between it and the outer fibrous layer. Their excretory ducts pierce the muscular 
 and inner fibrous layers, and pass through the submucous and mucous layers to 
 open on the surface of the mucous membrane. Some glands of smaller size are 
 also found at the sides of the trachea, between the layers of fibrous tissue con- 
 necting the rings, and others immediately beneath the mucous coat. The secre- 
 tion from these glands serves to lubricate the inner surface of the trachea. 
 
 Vessels and Nerves. — The trachea is supplied with blood by the inferior thy- 
 roid arteries. The veins terminate in the thyroid venous plexus. The nerves 
 are derived from the pneumogastric and its recurrent branches and from the 
 sympathetic. 
 
 Lymphatic Glands. — The trachea is surrounded by lax connective tissue which 
 contains numerous lymph glands, known as the peritracheo-bronchial glands. They 
 are divided into four groups (Bar^ty). A group to the right side, in the angle 
 between the trachea and right bronchus and ascending to the region of the sub- 
 clavian vessels. A group to the left side, in the angle formed by the trachea and 
 left bronchus, and ascending to about the arch of the aorta and the recurrent 
 laryngeal nerve. The two groups just described are usually called tracheal glands 
 (lymphoglandulae tracheales). A third group is in the angle formed by the bifur- 
 cation of the trachea. These constitute the bronchial glands (lymphoglandulae 
 bronchiales). They number ten or twelve (Cuneo). A fourth group, the inter- 
 bronchial glands, are found in angles of bifurcation of the larger bronchi in the 
 lung parenchyma. Very early in life the peritracheo-bronchial glands become 
 dark or even black from the deposition of carbonaceous substance brought by 
 the leukocytes from the bronchial tubes. This condition is called anthracosis. 
 
 Surface Form. — In the middle line of the neck some of the cartilages of the larynx can readily 
 be distinguished. In the receding angle below the chin the hyoid bone can easily be made 
 out, and a finger's breadth below it is the pomum Adami, the prominence between the upper 
 borders of the two alae of the thyroid cartilage. About an inch below this, in the middle line, is 
 a depression corresponding to the crico-thyroid space, in which the operation of laryngotomy is 
 performed. This depression is bounded below by a prominent arch, the anterior ring of the 
 cricoid cartilage, below which the trachea can be felt, though it is only in the emaciated adult 
 that the separate rings can be distinguished. The lower part of the trachea is not easily made 
 out, for as it descends in the neck it takes a deeper position, and is farther removed from the 
 surface. The level of the vocal cords corresponds to the middle of the anterior margin of the 
 thyroid cartilage. 
 
I 
 
 THE TRACHEA AND BRONCHI 1381 
 
 With the laryngoscope, the following structures can be seen: The base of the tongue and 
 the upper surface of the epiglottis, with the glosso-epiglottic ligaments; the superior aperture of 
 the larynx, bounded on either side by the aryteno-epiglottidean folds, in which may be seen two 
 rounded eminences corresponding to the cornicula and cuneiform cartilages. Beneath these, the 
 true and false vocal cords, with the ventricle between them. Still deeper, the cricoid cartilage 
 and some of the anterior parts of the rings of the trachea, and sometimes, in deep inspiration, the 
 bifurcation of the trachea. 
 
 Surgical Anatomy. — Foreign bodies often find their way into the air-passages. These may 
 be either large soft substances, as a piece of meat, which may become lodged in the upper aper- 
 ture of the larynx or in the rima glottidis, and cause speedy suffocation unless rapidly got rid of, 
 or unless an opening is made into the air-passages below, so as to enable the patient to breathe. 
 Smaller bodies, frequently of a hard nature, such as cherry- or plum-stones, small pieces of bone, 
 buttons, etc., may find their way through the rima glottidis into the trachea or bronchus, or may 
 become lodged in the ventricle of the larynx. The dangers then depend not so much upon the 
 mechanical obstruction as upon the spasm of the glottis which they excite from reflex irritation. 
 When lodged in the ventricle of the larynx, they may jiroduce very few symptoms beyond sudden 
 loss of voice or alteration in the voice sounds, immediately following the inhalation of the foreign 
 body. When, however, they are situated in the trachea, they are constantly striking against 
 the vocal cords during expiratory efforts, and produce attacks of dyspntra from spasm of the 
 glottis. When lodged in the bronchus, they usually become fixed there, and, occluding the 
 lumen of the tube, cause a loss of the respiratory murmur on the affected side, which is, as stated 
 above, more often the right. 
 
 Beneath the mucous membrane of the upper part of the air-passages there is a considerable 
 amount of submucous tissue which is liable to become much swollen from effusion in inflamma- 
 tory affections, constituting the disease known as " oedema of the glottis." This effusion does 
 not extend below the level of the true vocal cords, on account of the fact that the mucous mem- 
 brane is closely adherent to these structures, without the intervention of any submucous tissue. 
 So that, in cases of this disease in which it is necessary to open the air-passages to prevent suffo- 
 cation, the operation of laryngotomy is sufficient. 
 
 Chronic laryngitis is an inflammation of the mucous glands of the larynx, which occurs in 
 those who speak much in public, and is known as " clergyvian's sore throat." It is due to the 
 dryness induced by the large amount of cold air drawn into the air-passages during prolonged 
 speaking, which incites increased activity in the mucous glands to keep the parts moist, and 
 this eventually terminates in inflammation of these structures. 
 
 Ulceration of the larynx may occur from syphilis, either as a superficial ulceration, or from 
 the softening of a gumma; from tuberculous disease (laryngeal phthisis), or from malignant 
 disease (epithelioma). 
 
 The air-passages may be opened surgically in two different situations: through the crico- 
 thyroid membrane (laryngotomy), or in some part of the trachea (tracheotomy); and to these 
 some surgeons have added a third method, by opening the crico-thyroid membrane and 
 dividing the cartilage with the upper ring of the trachea (laryngo-tracheotomy). 
 
 Laryngotomy is anatomically the more simple operation: it can readily be performed, and 
 should be employed in those cases where the air-passages require opening in an emergency for 
 the relief of some sudden obstruction to respiration. The crico-thyroid membrane is very 
 superficial, being covered only in the middle line by the skin, superficial fascia, and the deep 
 fascia. On each side of the middle line it is also covered by the Sterno-hyoid and Sterno-thyroid 
 muscles, which diverge from each other at their upper parts, leaving a slight interval between 
 them. On these muscles rest the anterior jugular veins. The only vessel of any importance 
 in connection with this operation is the crico-thyroid artery, which crosses the crico-thyroid 
 membrane, and which may be wounded, but rarely gives rise to any trouble. The operation 
 is performed thus: the head being thrown back and steadied by an assistant, the finger is passed 
 over the front of the neck, and the crico-thyroid depression felt for. A vertical incision is then 
 made through the skin, in the middle line over this spot, and carried down through the fascia 
 until the crico-thyroid membrane is exposed. A cross-cut is then made through the membrane, 
 close to the upper border of the cricoid cartilage, so as to avoid, if possible, the crico-thyroid 
 artery, and a tracheotomy tube is introduced. It has been recommended, as a more rapid way 
 of performing the operation, to make a transverse instead of a longitudinal cut, through both the 
 superficial and deep structures, and thus to open at once the air-passages. It will be seen, however, 
 that in opening in this way the anterior jugular veins would be in danger of being wounded. 
 
 Tracheotomy may be performed either above or below the isthmus of the thyroid body, or 
 this structure may be divided and the trachea opened behind it. 
 
 The isthmus of the thyroid gland usually crosses the second and third rings of the trachea; 
 along its upper border is frequently to be found a large transverse communicating branch between 
 the superior thyroid veins; and the isthmus itself is covered by a venous plexus formed between 
 the thyroid veins of the opposite sides. Theoretically, therefore, it is advisable to avoid dividing 
 this structure in opening the trachea. 
 
1382 THE OBGANS OF VOICE AND RESPIRATION 
 
 Above the isthmus the trachea is comparatively superficial, being covered by the skin, super- 
 ficial fascia, deep fascia, Sterno-hyoid and Sterno-thyroid muscles, and a second layer of the 
 deep fascia, which, attached above to the lower border of the hyoid bone, descends beneath the 
 muscles to the thyroid body, where it divides into two layers and enclose the isthmus. 
 
 Below the isthmus the trachea lies much more deeply, and is covered by the Sterno-hyoid 
 and the Sterno-thyroid muscles and a quantity of loose areolar tissue in which is a plexus of 
 veins, some of them of large size; they converge to two trunks, the inferior thyroid veins, which 
 descend on either side of the median line on the front of the trachea and open into the innomi- 
 nate veins. In the infant the thymus gland ascends a variable distance along the front of the 
 trachea, and opposite the episternal notch the windpipe is crossed by the left innominate vein. 
 Occasionally, also, in young subjects, the innominate artery crosses the tube obliquely above 
 the level of the sternum. The thyroidea ima artery, when that vessel exists, passes from below 
 upward along the front of the trachea. 
 
 From these observations it must be evident that the trachea can be more readily opened 
 above than below the isthmus of the thyroid body. 
 
 Tracheotomy above the isthmus is performed thus; the patient should, if possible, be laid 
 on his back on a table in a good light. A pillow is to be placed under the shoulders and the 
 head thrown back and steadied by an assistant. The surgeon standing on the right side of his 
 patient makes an incision from an inch and a half to two inches in length in the median line of 
 the neck from the top of the cricoid cartilage. The incision must be made exactly in the middle 
 line, so as to avoid the anterior jugular veins, and after the superficial structures have been 
 divided the interval between the Sterno-hyoid muscles must be found, the raphe divided, and 
 the muscles drawn apart. The lower border of the cricoid cartilage must now be felt for, and 
 the upper part of the trachea exposed from this point downward in the middle line. Bose has 
 recommended that the layer of fascia in front of the trachea should be divided transversely at 
 the level of the lower border of the cricoid cartilage, and, having been seized with a pair of 
 forceps, pressed downward with the handle of the scalpel. By this means the isthmus of the 
 thyroid gland is depressed, and is saved from all danger of being wounded, and the trachea is 
 cleanly exposed. The trachea is now transfixed with a sharp hook and drawn forward in order 
 to steady it, and is then opened by inserting the knife into it and dividing the two or three upper 
 rings from below upward. If the trachea is to be opened below the isthmus, the incision to 
 expose it must be made from a little below the cricoid cartilage to the top of the sternum. 
 
 In the child the trachea is smaller, more deeply placed, and more movable than in the adult. 
 In fat or short-necked people, or in those in whom the muscles of the jieck are prominently 
 developed, the trachea is more deeply placed than in others. 
 
 A portion of the larynx or the whole of it has been removed or malignant disease, laryn- 
 gectomy. 
 
 Some surgeons do preliminary tracheotomy, insert a Trendelenburg cannula to prevent the 
 flow of blood downward into the lungs, and then remove the larynx. Other surgeons do not 
 employ preliminary tracheotomy. 
 
 Perier's method of laryngectomy is as follows: Make a vertical incision in the median line 
 from the level of the hyoid bone to below the level of the cricoid cartilage. Make a transverse 
 incision at each end of the vertical incision. This makes an I-shaped wound. 
 
 Separate the soft parts from the larynx and upper part of the trachea, and separate these two 
 structures from the oesophagus. After arresting bleeding, divide the trachea below the cricoid 
 cartilage, introduce a special cinnula, complete the removal of the larynx, suture the opening of 
 the trachea to the lower r.ngleof the wound, and close the rest of the wound after securing drainage. 
 In malignant disease of the larynx the associated lymphatic glands must be removed. 
 
 Partial laryngectomy, according to Sir F. Semon, is the removal of not less than one wing of 
 the thyroid cartilage. Removal of a lesser piece of the thyroid or of a bit of the arytenoid or 
 cricoid he considers with the operation of thyrotomy. 
 
 THE PLEURAE (Figs. 983, 984, 985, 986, 987). 
 
 Each lung is invested, upon its external surface, by an exceedingly delicate 
 serous membrane, the pleura, which encloses the organ as far as its root, and is 
 then reflected upon the inner surface of the thorax. The portion of the serous 
 membrane investing the surface of the lung and dipping into the fissures between 
 its lobes is called the pulmonary pleura or the visceral layer of the pleura (pleura 
 pulmonalis) (Fig. 983), while that which lines the inner surface of the chest is called 
 the parietal layer of the pleura (pleura parietalis) (Fig. 983). The two layers join at 
 the hilum of the lung. The space between these two layers is called the cavity of the 
 
THE PLEURAE 
 
 1383 
 
 pleura (cavum pleurae), and contains a very little clear fluid. It must be borne 
 in mind that in the healthy condition the two layers are in contact, and there 
 
 TRfANGULARIS STERNI 
 
 Internal Mammary Vessels 
 
 L^t Phrenic Nerve 
 
 Pleura Pulmonalis. 
 
 Pleura Costalis. 
 
 ^^'^-^--{'•''"mLS 
 
 Diicf. 
 
 Vena Azygos Major) p^^^^^,.^^ 
 eumnaas'tric rtervex > 
 
 Pneumnaa. 
 
 Fig. 983. — A transverse section of the thorax, showing the relative position of the viscera and the 
 
 reflections of the pleurae. 
 
 is no real cavity until the lung becomes collapsed and separates from the wall 
 of the chest. Each pleura is therefore a shut sac, one occupying the right, the 
 other the left half of the thorax, and they are perfectly separate from each other. 
 
 SCALENUS 
 MINIMUS 
 
 SYMPATHETIC 
 GANGLION 
 
 Fig. 984. — The dome of the pleura. (Poirier and Charpy.) 
 
 The two pleurae do not meet in the middle line of the chest, excepting anteriorly 
 opposite the second and third pieces of the sternum — a space being left between 
 
1384 
 
 THE ORGANS OF VOICE AND RESPIRATION 
 
 them, which contains all the viscera of the thorax excepting the lungs; this is the 
 mediastinum. 
 
 Reflections of the Pleurae (Fig. 983). The Pleura Pulmonalis (Fig. 983). -The 
 pleura pulmonalis is closely attached to the surface of the lung and enters into the 
 
 costapleural 
 ligament' 
 
 SCALENUS 
 MINIMUS 
 MUSCLE 
 
 Fig. 985. — The supports of the pleural dome. The oesophagus, trachea and arteries have been cut and pulled 
 aside to show the pleural reinforcements. (Poirier and Charpy.) 
 
 SYMPATHETIC 
 GANGLION 
 
 FIRST 
 
 THORACIC 
 
 NERVC 
 
 LONGUS COLLI 
 MUSCLE 
 
 SIBSON-S 
 APONEUROSIS 
 
 Fig. 987. — Section of the wall of the 
 Fig. 986. — The supports of the pleural dome. (Poirier and thorax, showing the phrenico-costal sinus. 
 
 Charpy.) (Poirier and Charpy.) 
 
 depths of the interlobar fissures. It leaves the lung surface at the hilum, covers the 
 root of the lung for a little way (Figs. 990 and 991), and then passes into the medi- 
 
THE PLEURAE 1385 
 
 astinal pleura. Between the hilum and the mediastinal pleura there is a thickened 
 pleural fold, triangular in outline, and called the ligamentum pulmonale or the 
 ligamentum latum pulmonis (Figs. 990 and 991). It is formed by the two layers of 
 the pulmonary pleura coming in contact below the root of the lung. This fold 
 passes from the lower part of the inner pulmonary surface to the pericardium, 
 and the lower border is free or attached to the diaphragmatic pleura. In the 
 right lung the origin of this ligament is in front of the groove for the azygos 
 vein; in the left lung it is in front of the groove for the thoracic aorta. 
 
 The Pleura Parietalis. — The pleura parietalis is a continuous membrane, but 
 for convenience is divided into the cervical pleura, costal pleura, mediastinal pleura, 
 and diaphragmatic pleura. 
 
 The Cervical Pleura or Dome of the Pleura or Cupola (cupula pleurae) (Fig. 986) is 
 the dome-shaped roof of the cavity of the pleura. It projects above the apex of the 
 lung to the neck of the first rib. As the first rib is placed obliquely, the dome of the 
 pleura reaches from one inch to two inches above the anterior extremity of the first 
 rib, and from one-half an inch to one and one-half inches above the clavicle. On the 
 outer side of the cervical pleura are the Scalenus anticus and medius muscles. Just 
 below the apex, on the anterior and inner surface, is a groove for the subclavian 
 artery, which vessel passes over it in an arch (Fig. 984) . A little below the groove 
 for the subclavian artery is a broader and shallower groove for the innominate and 
 subclavian veins. Above the subclavian artery and in front and above the cervical 
 pleura are the cords of origin of the brachial plexus and the inferior cervical gan- 
 glion (Fig. 984) . The dome is strengthened and kept in place by Sibson's aponeurosis 
 or the vertebro-pleural ligament (Figs. 985 and 986) . This comes from a little piece 
 of muscle, the Scalenus minimus muscle, which originates from the transverse pro- 
 cess of the seventh cervical vertebra, broadens and becomes aponeurotic as it de- 
 scends, and is inserted into the inner margin of the first rib (Figs. 984 and 985). It 
 is also strengthened by the costa-pleural ligament (Fig. 985), from the inner surface 
 of the neck of the first rib to the pleura, and by fibrous bands which pass to the 
 tissue about the subclavian sheath, trachea, and oesophagus (Fig. 985). 
 
 The Costal Pleura (pleura costalis) (Fig. 983) is the shortest portion of the 
 pleura and is connected to the parts it covers by the endothoracic fascia {fascia 
 endothoracica) , a layer of connective tissue which is much thicker back of the rib 
 cartilages than it is posteriorly. The costal pleura covers the inner surface of part 
 of the sternum, the costal cartilages, ribs, and Intercostal muscles, and the sides 
 of the bodies of the dorsal vertebrae. This layer is loosely attached except as it 
 passes from the heads of the ribs to the vertebrae, where it is firmly adherent. 
 
 The Mediastinal Pleura (pleura mediasiinalis) (Fig. 985) covers the septum of the 
 mediastiinnn, which intervenes between the two pleural cavities. The mediastinal 
 pleura extends from the inner surface of the anterior wall of the thorax to the 
 vertebrae. It is continuous in front and back with the costal pleura of the same 
 side, the lines of junction being known, respectively, as the anterior line of pleural 
 reflection and the posterior line of pleural reflection. Below the mediastinal pleura 
 passes into the diaphragmatic pleura of the same side. The portion of the medi- 
 astinal pleura which fuses with the parietal layer of the pericardium is called the 
 pericardial pleura (pleura pericardiaca). 
 
 Above the root of the lung the mediastinal pleura passes back directly to the 
 vertebrae. " In this region the left mediastinal pleura is applied to the arch of the 
 aorta and the phrenic and vagus nerves; to the left innominate vein, the left 
 superior intercostal vein, and the left common carotid, and left subclavian arteries; 
 to the oesophagus and the thoracic duct. The right mediastinal pleura, on the other 
 hand, is applied, above the level of the root of the lung, to the upper part of the 
 vena cava and right innominate vein; to the right innominate artery; to the vena 
 azygos major, as it hooks forward above the bronchus; to the vagus and phrenic 
 
1386 THE ORGANS OF VOICE AND BESPIBATION 
 
 nerves; and to the right side of the trachea."^ Upon the pericardium the phrenic 
 nerve is covered by the pleura. Back of the root of the lung and the pulmonary 
 ligament, the right mediastinal pleura passes back to the vertebrae to the left of the 
 oesophagus; the left mediastinal pleura passes back over the descending aorta, 
 and just above the Diaphragm and in front of the aorta over the lower end of the 
 oesophagus. 
 
 The Diaphragmatic Pleura {pleura diaphragmatica) (Figs. 987 and 988) covers 
 the upper surface of the Diaphragm outside of the base of the pericardium, but 
 does not completely cover it; for it does not pass into the interval between the 
 wall of the thorax and Diaphragm, and before this point is reached becomes 
 continuous with the costal pleura. 
 
 The reflection to the costal pleura begins by the sternum, at the lower margin of 
 the sixth rib; takes place at the junction of the cartilage of the rib with the seventh 
 rib; posteriorly, it takes place at the lower margin of the twelfth dorsal vertebra. 
 
 In the front of the chest, where the parietal layer of the pleura is reflected back- 
 ward to the pericardium, the two pleural sacs are in contact for a considerable 
 extent. At the upper part of the chest, behind the manubrium, they are not in 
 contact; the point of reflection being represented by a line drawn from the sterno- 
 clavicular articulation to the mid-point of the junction of the manubrium to the 
 body of the sternum. From this point the two pleurae descend in close contact to 
 the level of the fourth costal cartilages Here the line of reflection on the right side 
 is continued downward in nearly a straight line to the lower end of the gladiolus and 
 then turns outward behind the costal cartilage of the sixth rib, continuing to 
 descend and to run outward, it passes behind the descending part of the seventh 
 costal cartilage, and mests the axillary line at the junction of the eighth rib with 
 the cartilage. The line of reflection continues to descend till it reaches its lowest 
 point at the tenth rib. This point is in the axillary line, while on the left side 
 the line of reflection diverges outward, so that opposite the seventh cartilage it is 
 about three-quarters of an inch from the left border of the sternum. It, how- 
 ever, always extends considerably farther over the pericardium than the corre- 
 sponding lung. From this joint the reflections of the two sides are practically 
 the same. The lower limit of the pleura is on a considerably lower level than 
 the lower limit of the lung, but does not extend to the attachment of the Dia- 
 phragm, so that below the line of reflection of the pleura from the chest wall 
 on to the Diaphragm the latter is in direct contact with the rib cartilages and 
 the Internal intercostal muscles. In ordinary inspiration the thin margin of the 
 base of the lung does not extend as low as the line of pleural reflection, with the 
 result that the costal and diaphragmatic pleura are here in contact, the narrow 
 slit between the two being termed the phrenico-costal sinus {sinus phrenicocos- 
 talis) (Fig. 987) . A similar condition exists behind the sternum and rib cartilages, 
 where the anterior thin margin of the lung falls short of the line of pleural reflec- 
 tion, and where the slit-like cavity between the two layers of pleura forms what is 
 sometimes called the costo-mediastinal sinus {sinus costomediastinalis). 
 
 Along the line of reflection of the diaphragmatic pleura a dense fascia passes 
 from the costal cartilages and the uncovered portion of the Diaphragm to the 
 costal pleura. This serves to hold it in place. It is named by Cunningham the 
 phrenico-pleural fascia. 
 
 The inner surface of the pleura is smooth, polished, and moistened by a serous 
 fluid; its outer surface is intimately adherent to the surface of the lung, and to the 
 pulmonary vessels as they emerge from the pericardium; it is also adherent to the 
 upper surface of the Diaphragm; throughout the rest of its extent it is somewhat 
 thicker, and may be separated from the adjacent parts with extreme facility. 
 
 1 Cunningham's Text-book of Anatomv. 
 
THE MEDIASTINAL SPACE OB MEDIASTINUM 1387 
 
 The right pleural sac is shorter, wider, and reaches higher in the neck than 
 the left. 
 
 Structure of the Pleura. — The pleura is composed of connective tissue con- 
 taining much elastic tissue, its free surface being covered with flat endothelial cells. 
 It is fastened to adjacent structures by subserous areolar tissue. The subserous 
 tissue of the visceral pleura is continuous with the areolar tissue of the lung. 
 
 Vessels and Nerves. — The arteries of the pleura are derived from the intercostal, 
 the internal mammary, the musculo-phrenic, thymic, pericardiac, and bronchial. 
 The veins correspond to the arteries. The lymphatics are very numerous in the 
 pleura antl subserous tissue. Many of them are in direct communication with the 
 pleural cavity by stomata between the endothelial cells. Stomata are absent in 
 the mediastinal pleura and over the ribs (Dyskowsky). The lymphatics of the 
 visceral layer empty into the superficial pulmonary trunks; the lymphatics of the 
 costal pleura empty into the intercostal trunks; of the diaphragmatic pleura, into 
 the diaphragmatic trunks; of the mediastinal pleura, into the posterior mediastinal 
 glands.^ The nerves are derived from the phrenic and sjrmpathetic (Luschka). 
 KoUiker states that nerves accompany the ramification of the bronchial arteries 
 in the pleural pulmonalis. 
 
 Surgical Anatomy.^ — In operations upon the kidney it must be borne in mind that the pleura 
 may sometimes extend below the level of the last rib, and may therefore be opened in these 
 operations, especially when the last rib is removed, in order to give more room. It is best to 
 keep the incision at least one inch below the last rib, enlarging the wound afterward, when the 
 finger can be introduced as a guide. 
 
 In wounds of the Diaphragm the pleura may be injured. In operations about the root of 
 the neck, especially in the removal of glands and the ligation of the first part of the subclavian 
 artery, the pleura may be injured. 
 
 Punctured wounds of the root of the neck are apt to reach the pleura. 
 
 Empyema is a surgical disease. In acute empyema the treatment is drainage. A portion of 
 the fifth or sixth rib in the axillary line is removed by subperiosteal resection, the pleura is 
 opened, and a tube is introduced. In chronic empyema the lung is contracted and adherent and 
 cannot expand; hence drainage will not cure it. It is necessary to perform multiple rib resec- 
 tion in order to permit the chest-wall to sink in and obliterate the cavity, which, as the lung 
 is unable to expand, it cannot do. The necessary operation may be the operation of Estlander, 
 or the operation of Schede, or the operation of Fowler (page 166). 
 
 If a large wound admits suddenly a quantity of air into the pleura, dangerous or fatal pneumo- 
 thorax arises, and the lung collapses. This is best met during operations by using the Fell- 
 O'Dwyer apparatus for artificial respiration as advised by Matas.'^ This apparatus keeps the 
 lung expanded, in spite of the entrance of air into the pleural sac. In surgical pneumothorax 
 the lung may be sutured to the chest-wall, so as to block the opening. Sometimes, in order to 
 arrest dangerous pulmonary bleeding, a surgeon dehberately induces pneumothorax, in hope that 
 the collapse of the lung will arrest bleeding. 
 
 When an abscess of the liver is posterior and on the dorsum, transpleural hepatotomy is per- 
 formed. A portion of the tenth and eleventh ribs below the angle of the scapula is removed. 
 As a rule, the pleura is found obliterated at this point. If it is opened, it is at once sutured or 
 closed with gauze packing. The exposed Diaphragm is incised, and, as it is usually adherent 
 to the liver, the abscess cavity is entered. If it is not adherent, the liver is exposed and the 
 abscess sought for with an aspirating-needle. 
 
 THE MEDIASTINAL SPACE, INTERPLEURAL SPACE OR 
 MEDIASTINUM. 
 
 The mediastinum is the space left in the median portion of the chest by the non- 
 approximation of the two pleurae. It extends from the sternum in front to the 
 spine behind. Within it are the contents of the thorax excepting the lungs. The 
 mediastinum may be divided for purposes of description into two parts — an 
 upper portion, above the upper level of the pericardium, which is named the 
 
 1 Poirier, Cun<5o, and Delamare on the Lymphatics. Translated and edited by Cecil H. Leaf. 
 '^ Annals of Surgery, April, 1899. 
 
1388 
 
 THE ORGANS OF VOICE AND RESPIRATION 
 
 superior mediastinum (Struthers); and a lower portion, below the upper level of 
 the pericardium. This lower portion is again subdivided into three — that part 
 which contains the pericardium and its contents, the middle mediastinum; that 
 part which is in front of the pericardium, the anterior mediastinum; and that part 
 which is behind the pericardium, the posterior mediastinum. 
 
 Fig. 988. — The posterior mediastinum. 
 
 The Superior Mediastinum (Fig. 989) .—The superior mediastinum is that por- 
 tion of the interpleural space which lies above the upper level of the pericardium, 
 between the manubrium sterni in front and the upper dorsal vertebrae behind. It is 
 bounded below by a plane passing backward from the junction of the manubrium 
 and gladiolus sterni to the lower part of the body of the fourth dorsal vertebra, 
 
THE MEDIASTINAL SPACE OR MEDIASTINUM 
 
 1389 
 
 and laterally by the lungs and pleurae. It contains the origins of the Sterno-hyoid 
 and Stern o-thyroid muscles and the lower ends of the Longus colli muscles; the 
 arch of the aorta; the innominate, the thoracic portion of the left carotid and sub- 
 clavian arteries; the upper half of the superior vena cava and the innominate 
 veins, and the left superior intercostal vein; the pneumogastric, cardiac, phrenic, 
 and left recurrent laryngeal nerves; the trachea, oesophagus, and thoracic duct; 
 the remains of the thymus gland and some lymphatic glands. 
 
 The Anterior Mediastinum (Fig. 983). — The anterior mediastinum is bounded 
 in front by the sternum, on each side by the pleura, and behind by the pericardium. 
 It is narrow above, but widens out a little below, and, owing to the oblique course 
 taken by the left pleura, it is directed from above obliquely downward and to the 
 left. Its anterior wall is formed by the left Triangularis sterni muscle and the 
 fifth, sixth, and seventh left costal cartilages. It contains a quantity of loose 
 areolar tissue, some lymphatic vessels which ascend from the convex surface of the 
 liver, two or three lymphatic glands (anterior mediastinal glands), and the small 
 mediastinal branches of the internal mammary artery. 
 
 Left Inom- Left Carotid Thymus Pneumogastric 
 inate Vem. Artery. Gland. Nerve. 
 
 Pneumoqastric 
 Nerve. 
 
 Vertebral 
 
 Artery 
 
 Left Stiblcavian_ 
 Artery. 
 
 Oesophagus.' — 
 
 Internal Mammary 
 Artery. 
 
 Right Innom- 
 inate Vein. 
 
 Trachea. 
 
 2nd Rih. 
 
 oi d Rib. 
 Fig. 989. — Transverse section through the second dorsal vertebra. (Braune.) 
 
 The Middle Mediastinum (Fig. 983). — The middle mediastinum is the 
 broadest part of the interpleural space. It contains the heart enclosed in the 
 pericardium, the ascending aorta, the lower half of the superior vena cava, with 
 the vena azygos major opening into it, the bifurcation of the trachea and the two 
 bronchi, the pulmonary artery dividing into its two branches and the right and 
 left pulmonary veins, the phrenic nerves, and some bronchial lymphatic glands. 
 
 The Posterior Mediastinum (Figs. 983 and 987). — The posterior mediastinum 
 is an irregular triangular space running parallel with the vertebral column; it is 
 bounded in front by the pericardium and roots of the lungs, behind by the verte- 
 bral column from the lower border of the fourth dorsal vertebra, and on either 
 side by the pleura. It contains the descending thoracic aorta, the greater and 
 lesser azygos veins, the pneumogastric and splanchnic nerves, the oesophagus, 
 thoracic duct, and some lymphatic glands. 
 
1390 
 
 THE ORGANS OF VOICE AND BESPIBATION 
 
 Blood-vessels. — The areolar tissue of the anterior mediastinum receives numer- 
 ous mediastinal branches from the internal mammary artery. The areolar tissue 
 of the posterior mediastinum receives mediastinal branches from the descending 
 thoracic aorta. The lowest mediastinal vessels lie upon the Diaphragm and are 
 called superior phrenic arteries. The vena cava and internal mammary veins 
 receive mediastinal branches. 
 
 The anterior mediastinal lymphatic glands are in the upper portion of the anterior 
 mediastinum. They are five or six in number and are placed in front of the trans- 
 verse arch of the aorta. Chains of glands run up from them to the root of the 
 neck. On the right side glands are in front of the right innominate vein, between 
 the artery and vein and behind the artery. On the left side they are around the 
 left common carotid and left subclavian arteries.^ 
 
 The posterior mediastinal glands are around the oesophagus, particularly in front 
 of it. The peritracheo -bronchial glands have been described. 
 
 THE LUNGS (PULMONES) (Figs. 983, 990, 991, 992, 993, 994, 995). 
 
 The lungs are the essential organs of respiration; they are two in number, 
 placed one on each side of the chest, separated from each other by the heart and 
 other contents of the mediastinum. A healthy lung hangs free within the pleural 
 
 LIGAMENTUM 
 LATUM PULMONIS 
 
 Fig. 990. — The right lung. The inner or mediastinal surface, with the hilum laid bare by the removal of the 
 structures forming the root of the lung. (Toldt.) 
 
 cavity. It is suspended by the root and by the ligamentum pulmonis. In many 
 cases examined the lung does not hang free, but, as a result of former pleurisy, 
 an area of the pulmonary pleura is adherent to the parietal pleura. Each lung is 
 conical in shape, and presents for examination an apex, a base, two borders, and 
 two surfaces. 
 
 The Apex {ajpex 'pulmonis). — The apex forms a tapering cone which extends 
 into the root of the neck about an inch to two inches above the level of the anterior 
 
 1 Poirier, Cun6o, and Delamare on the Lymphatics. Translated and edited by Cecil H. Leaf. 
 
THE LUNGS 
 
 1391 
 
 extremity of the first rib. The brachial plexus is in close proximity to this por- 
 tion of the lung. 
 
 The Base (basis pulmonis). — The base is broad, concave, and rests, by its 
 diaphragmatic surface {fades diaphragmatica), upon the convex surface of the 
 Diaphragm, which separates the right lung from the upper surface of the right 
 lobe of the liver and the left lung from the upper surface of the left lobe of the 
 liver, the fundus of the stomach, and spleen; its circumference is thin, and 
 projects for some distance into the phrenico-costal sinus of the pleura, between 
 the lower ribs and the costal attachment of the Diaphragm, extending lower 
 down externally and behind than in front. 
 
 Surfaces. The External, Costal or Thoracic Surface (fades costalis) (Figs. 994 
 and 995). — The external, costal, or thoracic surface is smooth, convex, of con- 
 siderable extent, and corresponds to the form of the cavity of the chest, being 
 deeper behind than in front. In a hardened specimen this surface has grooves 
 and bulgings on it, corresponding to the ribs and intercostal spaces. 
 
 ROOT OF 
 LUNG 
 
 SUBCLAVIAN 
 GROOVE 
 
 PULMONARY 
 ARTERY 
 
 BRONCHUS 
 
 PULMONARY 
 VEINS 
 
 IRONCHIAL 
 ARTERIES 
 
 BRONCHIAL 
 
 LYMPHATIC 
 
 GLAND 
 
 LIGAMENTUM 
 
 LATUM 
 
 PULMONIS 
 
 CARDIAC 
 DEPRESSION 
 
 INFERIOR 
 BORDER 
 
 Fig. 991.— The left lung. The inner or mediastinal surface, with the root of the lung cut across. (Toldt.) 
 
 The Inner or Mediastinal Surface (fades mediastinalis) (Figs. 990 and 991). — The 
 inner or mediastinal surface is concave. It presents in front a depression corre- 
 sponding to the convex surface of the pericardium, and behind a deep fissure, the 
 hilum (hilus pidmonalis) . In the hilum lie the bronchi, vessels, nerves, and 
 lymph-nodes, which together constitute the root of the lung. On the inner and 
 anterior surface, a little below the apex, is a groove, the subclavian groove (sulcus 
 subclavius), for the subclavian artery. A little lower is a broader and shallower 
 groove for the innominate and subclavian veins. The pleura lies between the 
 lungs and these vessels. In front of the hilum and below it is a depression for 
 the heart (impressio cardiaca). It is deeper on the left than on the right side. 
 On the right side it passes into the groove from the superior vena cava and the 
 vena azygos major. On the left side, behind the hilum, is a groove for the 
 thoracic aorta; on the right side a groove for the oesophagus. 
 
1392 
 
 THE ORGANS OF VOICE AND RESPIRATION 
 
 Borders. The Inferior Border (margo inferior). — The inferior border is the line 
 of junction of the costal and diaphragmatic surfaces. Posteriorly, it is rounded 
 and broad, and is received into the deep concavity on either side of the spinal 
 column (Fig. 996). It is much longer than the anterior border, and projects, 
 below, into the phrenico-costal sinus. 
 
 Fig. 992. — Front \ iew of the heart and lungs. 
 
 The Anterior Border (margo anterior). — The anterior border is thin and sharp, 
 overlaps the front of the pericardium, and is projected into the costo-medi- 
 astinal sinus of the pleura. The anterior border of the right lung is almost 
 vertical; that of the left presents, below, an angular notch, the incisura cardiaca, 
 into which the heart and pericardium are receivefl. A projection from the 
 upper lobe omes forward beneath the cardiac notch; it is called the lingula 
 pulmonis. 
 
 The Lobes of the Lungs (Figs. 994 and 995).— Each lung is divided into two 
 lobes, an upper (lohus superior) and a lower (lobus inferior), by a long and deep 
 fissure (incisura interlobaris) , which extends from the upper part of the posterior 
 border of the organ about three inches from its apex, downward and forward to 
 the lowest part of the lung just external to its anterior border. This fissure pene- 
 trates nearly to the root. The upper lobe is the smaller; the lower lobe is the 
 larger. In the right lung the upper lobe is partially subdivided by a second and 
 shorter fissure, which extends almost horizontally forward from the middle of 
 the preceding to the anterior margin of the organ, marking off a small triangular 
 portion, the middle lobe (lohus medium). 
 
 The right lung is the larger and heavier; it is broader than the left, owing to 
 the inclination of the heart to the left side; it is also shorter by an inch, in 
 
THE LUNGS 
 
 1393 
 
 consequence of the Diaphragm rising higher on the right side to accommodate 
 the Hver. 
 
 ENTRANCE OF 
 VENA AZYGOS 
 BRANCH OF PUL- 
 MONARY ARTERY 
 
 Fig. 993. — Pulmonary veins, seen in a dorsal view of the heart and lungs. The lungs have been pulled 
 away from the median line, and a part of the right lung has been cut away to display the air-ducts and blood- 
 vessels. (Testut.) 
 
 Fio. 994. — The right lung. The outer or costal 
 surface. (Toldt.) 
 
 Fig. 995. — The left lung. The outer or costal 
 surface. (Toldt.) 
 
 The Root of the Lung (radix pulmonis) (Figs. 990, 991, 992, and 993).— A 
 little above the middle of the inner surface of each lung, and nearer its posterior 
 
 88 
 
1394 THE ORGANS OF VOICE AND BESPIBATION 
 
 than its anterior border, is its root, by which the lung is connected to the heart 
 and the trachea. The root is formed by the bronchial tube, the pulmonary 
 artery, the pulmonary veins, the bronchial arteries and veins, the pulmonary 
 plexus of nerves, lymphatics, bronchial glands, and areolar tissue, all of which 
 are enclosed by a reflection of the pleura. The root of the right lung lies behind 
 the superior vena cava and ascending portion of the aorta, and below the vena 
 azygos major. The root of the left lung passes beneath the arch of the aorta 
 and in front of the descending aorta; the phrenic nerve and the anterior pulmo- 
 nary plexus lie in front of each, and the pneumogastric and posterior pulmonary 
 plexus behind each. 
 
 The chief structures composing the root of each lung are arranged in a similar 
 manner from before backward on both sides — viz., the two pulmonary veins in front ; 
 the pulmonary artery in the middle; and the bronchus, together with the bronchial 
 vessels, behind. From above downward, on the two sides, their arrangernent differs, 
 thus: On the right side their position is — bronchus, pulmonary artery, pulmonary 
 veins; but on the left side their position is — pulmonary artery, bronchus, pulmo- 
 nary veins. It should be noted that the entire right bronchus does not lie above 
 the right pulmonary artery, but only its eparterial branch (see p. 1377), which 
 passes to the upper lobe of the right lung; the divisions of the bronchus for the 
 middle and lower lobes lie below the artery. 
 
 The true weight of the human lungs as ascertained in the bodies of criminals 
 executed by electricity, in which the mode of death is attended by a nearly bloodless 
 condition of the lungs, is 215 grams (7^ ounces) for the left lung and 240 grams 
 (8^ ounces) for the right lung (E. A. Spitzka, Amer. Jour, of Anat., iii., 1, p. v.). 
 Ordinarily, with the vascular channels more or less filled with blood and serum, 
 the two lungs together weigh about 42 ounces, the right lung being 2 ounces 
 heavier than the left, but much variation is met with according to the amount of 
 blood or serous fluid they may contain. The lungs are heavier in the male than 
 in the female. The specific gravity of the lung-tissue varies from 0.345 to 0.746. 
 
 The color of the lungs at birth is a pinkish-white; in adult life a dark slate- 
 color, mottled in patches; and as age advances this mottling assumes a black 
 color. The coloring matter consists of granules of a carbonaceous substance 
 deposited in the areolar tissue near the surface of the organ. It increases in 
 quantity as age advances, and is more abundant in males than in females. The 
 posterior surface of the lung is usually darker than the anterior. 
 
 The surface of the lung is smooth, shining, and marked out into numerous 
 polyhedral spaces, indicating the lobules of the organ; the area of each of these 
 spaces is crossed by numerous lighter lines. 
 
 The substance of the lung is of a light, porous, spongy texture; it floats in 
 water and crepitates when handled, owing to the presence of air in the tissue; it 
 is also highly elastic; hence the collapsed state of these organs when they are 
 removed from the closed cavity of the thorax. 
 
 The Fcetal Lung. — After respiration has been established, the lung fills the 
 pleural cavity. In the foetus, as the lung has never been distended with air 
 and has never received a large amount of blood, it is gathered into a small mass 
 at the back of the thorax. It will sink in water and feels solid to the touch. 
 
 Structure. — The structure of the lung is such that the blood brought by the 
 pulmonary artery comes into close relation with the air which enters from the 
 bronchioles. The blood gives materials to the air, and the air gives elements to 
 the blood, and the process of respiration causes the dark blood brought from the 
 heart by the pulmonary artery to return to the heart as red blood in the pulmonary 
 vein. The lungs are composed of an external serous coat, a subserous areolar tissue, 
 and the pulmonary substance or parenchyma. 
 
 The Serous Coat. — The serous coat is thin, transparent, and invests the entire 
 organ as far as the root. It is known as the pulmonary pleura (p. 1384). 
 
THE LUNGS I395 
 
 The Subserous Areolar Tissue. — The subserous areolar tissue contains a large 
 proportion of elastic fibres; it invests the entire surface of the lung, and extends 
 inward between the lobules, and at the hilum forms the pulmonary scaffold or 
 framework. 
 
 The Paxenchyma. — The parenchyma is composed of lobules which, although 
 closely connected together by an interlobular areolar tissue, are quite distinct from 
 one another, and may be teased asunder without much difficulty in the foetus. 
 The lobules vary in size; those on the surface are large, of pyramidal form, with 
 the bases turned toward the surface; those in the interior are smaller and of various 
 forms. Each lobule is composed of one of the ramifications of a bronchial tube 
 and its terminal air-cells, and of the ramifications of the pulmonary and bronchial 
 vessels, lymphatics, and nerves, all of these structures being connected together by 
 areolar tissue. 
 
 The Bronchus (pp. 1377 and 1378) (Figs. 980, 981, and 982).— The bronchus, 
 upon entering the substance of the lung, divides and subdivides bipinnately, 
 throughout the entire organ. Sometimes three branches arise together, and occa- 
 sionally small lateral branches are given off from the sides of a main trunk. Each 
 of the smaller subdivisions of the bronchi enters a pulmonary lobule, and is termed 
 a lobular bronchial tube or bronchiole (bronchioli). Each bronchiole divides into 
 minute branches {bronchioli respiratorii) , the walls of which now begin to present 
 irregular dilatations, bronchial alveoli. These are present at first sparingly and on 
 one side of the tube only, but as it proceeds onward these dilatations become more 
 numerous and surround the tube on all sides, so that it loses its cylindrical char- 
 acter. The terminal branches come from the bronchioli respiratorii. These 
 terminal branches are called the alveolar ducts or alveolar passages {ducivli alveo- 
 lares). The alveolar ducts show numerous alveoli (Fig. 981) ar.d join with cav- 
 ities called atria. Each atrium joins several larger cavities, the air-cells or air-sacs 
 (infundibula) . The numerous small cavities on the surface of the air-sacs are 
 the pulmonary alveoli (alveoli pulmonis) . The bronchiole now becomes widened 
 out and terminates in an irregular cul-de-sac, the air cell, air sac alveolus or infun- 
 dibulum. The walls of the infundibulum are closely beset in all directions by pul- 
 monary alveoli or pulmonary air cells. Professor Gerrish remarks that the first of 
 the alveoli seen on the bronchioles before the coreal ends are formed would seem 
 an effort on the part of nature to form an infundibulum before all the necessary 
 conditions are favorable. 
 
 Changes in the Structure of the Bronchi in the Lungs. ^Within the lungs the 
 bronchial tubes are circular, not flattened (Fig. 982), and present certain pecu- 
 liarities of structure. 
 
 In the Lobes of the Lungs. — In the lobes of the lungs the following changes 
 take place: The cartilages are not imperfect rings, but consist of thin laminae, 
 of varied form and size, scattered irregularly along the sides of the tube, being 
 most distinct at the points of division of the bronchi. They may be traced into 
 tubes, the diameter of each of which is only one-fourth of a line. Beyond this 
 point the tubes are wholly membranous. The fibrous coat is continued into the 
 smallest ramifications of the bronchi. The muscular coat is disposed in the form 
 of a continuous layer of annular fibres, which may be traced upon the smallest 
 bronchial tubes, and consists of the unstriped variety of muscular tissue. The 
 mucous membrane lines the bronchi and their ramifications throughout, and is 
 covered with columnar ciliated epithelium. 
 
 In the Lobules of the Lung. — In the lobular bronchial tubes and in the infun- 
 dibula the following changes take place: The muscular tissue begins to disap- 
 pear, so that in the infundibula there is scarcely a trace of it. The fibrous coat 
 becomes thinner, and degenerates into areolar tissue. The epithelium becomes 
 non-ciliated and flattened. This occurs gradually; thus, in the lobular bronchioles 
 
1396 THE ORGANS OF VOICE AND RESPIRATION 
 
 patches of non-ciliated flattened epithelium may be found scattered among the 
 columnar ciliated epithelium; then these patches of non-ciliated flattened epithe- 
 lium become more and more numerous, until in the infundibula and air-cells all 
 the epithelium is of the non-ciliated pavement variety. In addition to these flat- 
 tened cells, there are small polygonal granular cells in the air-sacs, in clusters of 
 two or three, between the others. 
 
 The air-cells are small, polyhedral recesses composed of a fibrillated connec- 
 tive tissue and surrounded by a few involuntary muscular and elastic fibres. Free 
 in their cavity are to be seen under the microscope granular, rounded, amoeboid 
 cells (eosinophile leukocytes), often containing carbonaceous particles. The air- 
 cells are well seen on the surface of the lung, and vary from -^^ to y^ of an 
 inch in diameter, being largest on the surface at the thin borders and at the apex, 
 and smallest in the interior. 
 
 Mucous Glands. — In the larger bronchi the mucous membrane contains goblet 
 cells. When the tubes diminish to 1 mm. in diameter the glands grow fewer. 
 In the smaller bronchi there are no mucous glands. 
 
 Vessels of the Lungs. — The pulmonary artery (Figs. 992 and 993) conveys the 
 venous blood to the lungs; it divides into branches which accompany the bronchial 
 tulles, and terminates in a dense capillary network upon the walls of the inter- 
 cellular passages and air-cells. In the lung the branches of the pulmonary artery 
 are usually above and in front of a bronchial tube, the vein below. 
 
 The pulmonary capillaries form plexuses which lie immediately beneath the 
 mucous membrane in the walls and septa of the air-cells and of the infundibula. 
 In the septa between the air-cells the capillary network forms a single layer. The 
 capillaries form a very minute network, the meshes of which are smaller than the 
 vessels themselves;^ their walls are also exceedingly thin. The arteries of neigh- 
 boring lobules are independent of each other, but the veins freely anastomose 
 together. 
 
 The pulmonary veins commence in the pulmonary capillaries, the radicles 
 coalescing into larger branches, which run along through the substance of the 
 lung, independently from the minute arteries and bronchi. After freely commu- 
 nicating with other branches they form large vessels, which ultimately come into 
 relation with the arteries and bronchial tubes, and accompany them to the hilum 
 of the organ. Finally they open into the left auricle of the heart, conveying 
 oxygenated blood to be eventually distributed to all parts of the body by the aorta. 
 
 The bronchial arteries supply blood for the nutrition of the lung. The thoracic 
 aorta usually gives off two left bronchial arteries. The single right bronchial 
 artery usually arises from the first right aortic intercostal, but sometimes from 
 the superior left bronchial artery, or from the aorta. In the root of the lung 
 they are posterior to the bronchus, they accompany the bronchial tubes, supply 
 the tubes and pulmonary tissue, and give branches to the walls of the larger 
 pulmonary vessels, the oesophagus, pericardium, and bronchial glands. Those 
 supplying the bronchial tubes form a capillary plexus in the muscular coat, from 
 which branches are given off to form a second plexus in the mucous coat. This 
 plexus communicates with branches of the pulmonary artery, and empties itself 
 into the pulmonary vein. Others are distributed in the interlobular areolar tissue, 
 and terminate partly in the deep, partly in the superficial, bronchial veins. Lastly, 
 some ramify upon the surface of the lung beneath the pleura, where they form a 
 capillary network. There may be but one bronchial artery; there may be three 
 or four. 
 
 The bronchial veins are not found in the walls of the very small bronchi. The 
 small bronchial veins run along by the front and back of the median sized and 
 
 1 The meshes are only 0.002'" to 0.008'" in width, while the vessels are 0.003'" to 0.005'" (KSlliker, Human 
 Microscopic Anatomy). — Ed. of 15th English edition. 
 
THE LUNGS I397 
 
 larger tubes, and from two trunks at the root of each lung. These vessels termi- 
 nate on the right side in the vena azygos major, and on the left side in the superior 
 intercostal or left upper azygos vein. Tracheal and posterior mediastinal veins 
 open into the bronchial veins. The venous blood from the smaller tubes passes 
 to the pulmonary veins. 
 
 The lymphatics begin in networks about the lobules and form networks about 
 the bronchi and beneath the bronchial mucous membrane. The superficial col- 
 lecting trunks arise about the lobules and beneath the pleura. According to 
 Sappey, the superficial trunks from the upper lobe begin on the costal surface; 
 one set passes around the anterior border, another set around the posterior 
 border, and a third into the incisura interlobaris. The same observer says that the 
 superficial trunks from the middle lobe unites with the trunks from the upper and 
 lower lobes; and the superficial trunks from the lower lobe, like those of the upper 
 lobe, are in three sets. One set passes around the posterior margin, one around the 
 anterior margin, and one into the incisura interlobaris. All of the superficial trunks 
 convey lymph to the glands of the hilum. Some of the deep collecting trunlcs begin 
 by the sides of the small bronchi; others course along by the pulmonary veins 
 or pulmonary arteries. All of them pass to the glands of the hilum. The glands 
 of the hilum are in communication with the peritracheo-bronchial glands.^ 
 
 Nerves. — The lungs are supplied from the anterior and posterior pulmonary 
 plexuses, formed chiefly by branches from the sympathetic and pneumogastiic. 
 The filaments from these plexuses accompany the bronchial tubes, and are lost 
 upon them. Small ganglia are found upon these nerves. 
 
 Surface Form. — The apex of the lung is situated in the neck, behind the interval between the 
 two heads of origin of the Sterno-mastoid muscle. The height to which it rises above the clavicle 
 varies very considerably, but is generally about one inch. It may, however, extend as much as 
 an inch and a half or an inch and three-quarters, or, on the other hand, it may scarcely project 
 above the level of this bone. In order to mark out the anterior margin of the lung, a line is 
 to be drawn from the apex-point, one inch above the level of the clavicle, and rather nearer the 
 posterior than the anterior border of the Sterno-mastoid muscle, downward and inward across 
 the sterno-clavicular articulation and first piece of the sternum until it meets, or almost meets, 
 its fellow of the other side opposite the articulation of the manubrium and gladiolus. From this 
 point the two lines are to be drawn downward, one on either side of the mesial line and close to 
 it, as far as the level of the articulation of the fourth costal cartilages to the sternum. From 
 here the two lines diverge; the left is to be drawn at first passing outward with a slight inclina- 
 tion downward, and then taking a bend downward with a slight inclination outward to the apex 
 of the heart, and thence to the sixth costo-chondral articulation. The direction of the anterior 
 border of this part of the left lung is denoted with sufficient accuracy by a curved line with its 
 convexity directed upward and outward from the articulation of the fourth right costal cartilage 
 of the sternum to the fifth intercostal space, an inch and a half below and three-quarters of an 
 inch internal to the left nipple. The continuation of the anterior border of the right lung is 
 marked by a prolongation of its line from the level of the fourth costal cartilages vertically 
 downward as far as the sixth, when it slopes off along the line of the sixth costal cartilage to its 
 articulation with the rib. 
 
 The lower border of the lung is marked out by a slightly curved line with its convexity down- 
 ward from the articulation of the sixth costal cartilage to its rib to the spinous process of the 
 tenth dorsal vertebra. If vertical lines are drawn downward from the nipple, the mid-axillary 
 line, and the apex of the scapula, while the arms are raised from the sides, they should intersect 
 this convex line, the first at the sixth, the second at the eighth, and the third at the tenth rib. 
 It will thus be seen that the pleura extends farther down than the lung, so that it may be 
 wounded, and a wound may pass through its cavity into the Diaphragm, and the abdominal 
 viscera may be injured without the lung being involved. 
 
 The posterior border of the lung is indicated by a line drawn from the level of the spinous 
 process of the seventh cervical vertebra, down either side of the spine, corresponding to the 
 costo-vertebral joints as low as the spinous process of the tenth dorsal vertebra. The trachea 
 bifurcates opposite the spinous process of the fourth dorsal vertebra, and from this point the two 
 bronchi are directed outward. 
 
 "The position of the great fissure of the lungs may be indicated by a line drawn from the third 
 
 1 The Lymphatics, by Poirier, Cun6o, and Delamare. Translated and edited by Cecil H. Leaf. 
 
1398 
 
 THE ORGANS OF VOICE AND RESPIRATION 
 
 dorsal spine obliquely downward in such a manner as to reach the sixth rib close to the mid- 
 clavicular line. The interlobar fissure between the upper and middle lobes of the right lung 
 corresponds to a line drawn from the apex of the axilla almost horizontally to the sternum, 
 reaching the latter at about the level of the fourth costal cartilage" (Erendrath). 
 
 Recur, 
 lar. nen 
 
 Epart. 
 hronchtis 
 
 Pulm. 
 veins 
 
 1 1)1 iiiiu n Ju) 
 oesophagus 
 
 Fig. 996. — Thoracic contents seen from behind. (Joessel.) 
 
 Surgical Anatomy. — The lungs may be wounded or torn in three ways: (1) By compres- 
 sion of the chest, without any injury to the ribs. (2) By a fractured rib penetrating the lung. 
 (3) By stabs, gunshot wounds, etc. 
 
THE LUNGS 1399 
 
 The first form, where the lung is ruptured by external compression without any fracture of 
 the ribs, is very rare, and usually occurs in young children, and affects the root of the lung — 
 i. e., the most fixed part — and thus, implicating the great vessels, is frequently fatal. It would 
 seem to be a most unusual injury, and the exact mode of its causation is difficult to understand. 
 The probable explanation is that immediately before the compression is applied a deep inspira- 
 tion is taken and the lungs are fully inflated ; owing then to spasm of the glottis at the moment 
 of compression, the air is unable to escape from the lung, the lung is not able to recede, and 
 consequently gives way. 
 
 In the second variety, when the wound in the lung is produced by the penetration of a broken 
 rib, both the pleura costalis and the pleura pulmonalis must necessarily be injured, and conse- 
 quently the air taken into the wounded air-cells may find its way through these wounds into the 
 cellular tissue of the parietes of the chest. This it may do without collecting in the pleural cavity; 
 the two layers of the pleura are so intimately in contact that the air may pass straight through 
 from the wounded lung into the subcutaneous tissue. Emphysema constitutes, therefore, an 
 important sign of injury to the lung in cases of fracture of the ribs. Pneumothorax, or air in the 
 pleural cavity, is much more likely to occur in injuries to the lung of the third variety; that is 
 to say, from external wounds, from stabs and gunshot injuries, in which cases air passes either 
 from the wound of the lung or from an external wound into the cavity of the pleura dur- 
 ing the respiratory movements. In these cases there is generally no emphysema of the sub- 
 cutaneous tissue unless the external wound is small and valvular, so that the air drawn into the 
 wound during inspiration is then forced into the cellular tissue around during expiration because 
 it cannot escape from the external wound. Occasionally in wounds of the parietes of the chest 
 no air finds its way into the cavity of the pleura, because the lung at the time of the accident 
 protrudes through the wound and blocks the opening. This occurs where the wound is large, 
 and constitutes a so-called hernia of the lung. True hernia of the lung occurs, though very 
 rarely, after wounds of the chest-wall, when the wound has healed and the cicatrix sub- 
 sequently yields from the pressure of the viscus behind. It forms a globular, elastic, crepi- 
 tating swelling, which enlarges during expiratory efforts, falls during inspiration, and disappears 
 on holding the breath. Wounds of the lung may produce dangerous or fatal hemorrhage into 
 the pleural sac. In many cases the bleeding is spontaneously arrested; in others the surgeon 
 must interfere to save life. In some cases air has been admitted by intercostal incision and the 
 insertion of a tube, and pulmonary collapse has arrested bleeding. In other cases it is necessary 
 to resect portions of several ribs, and stop bleeding by ligatures or suture ligatures. In one 
 <;ase of a furious secondary hemorrhage following a gunshot wound, the editor resected several 
 ribs, packed the pleural cavity about the lung with sterile gauze, to obtain a base of support, and 
 then arrested the bleeding by packing iodoform gauze against the firmly supported lung. This 
 patient recovered. 
 
 Incision of the lung (pneumotomy) is performed for pulmonary abscess (either tuberculous or 
 pyogenic), pulmonary gangrene, hydatid cysts, and bronchiectasis. In pulmonary abscess, 
 locate the area by physical signs and the a^-ray, resect a portion of a rib over it, and note if the 
 pleura is adherent. If it is adherent, continue the operation. If it is not adherent, insert stitches 
 of catgut through the two layers of pleura and the superficial part of the lung, so as to encircle 
 a considerable area, and then wait several days for adhesions to form. Adhesions protect the 
 pleura from infection, and, by keeping air from the pleural sac, prevent pneumothorax. When 
 ready to continue the operation, locate the abscess with an aspirating-needle and syringe, open 
 it with a cautery at a dull-red heat, and drain by means of a tube. 
 
 Pneumotomy is very unsatisfactory in tuberculous cavities and bronchiectasis. In tubercu- 
 losis, excision of the diseased area (pneumectomy) has been employed, but it is not to be advised. 
 
THE DUCTLESS GLANDS. 
 
 THESE glands do not possess excretory ducts. They furnish materials which 
 are added to the blood or lymph as it passes through them. The material 
 from each gland is known as an internal secretion. Some of these secretions are 
 powerful materials and influence profoundly the body nutrition. The ductless 
 glanfls are usually given as follows: the spleen, the lymphatic glands, the pineal 
 gland, the pituitary body, the suprarenal capsules, the thyroid gland, the para-thyroids, 
 the thymus, the carotid body, and the coccygeal body. The lymphatic glands were 
 described in a special section (p. 772). The lymphatic glands are not con- 
 sidered to be really glands, but, nevertheless, as lymph passes through the lymph 
 glands, it receives a product of the glands, namely, lymphocytes. There is no 
 evidence that the spleen furnishes an active internal secretion, and this organ 
 has been studied with the abdominal viscera. The pineal gland (p. 905) and 
 pituitary body (p. 882) were considered with the brain. The suprarenal capsules 
 (p. 1428) are described with the kidneys. Some glands, for instance, the liver, 
 pancreas and testicle, have an external secretion and also an internal secretion. 
 
 THE THYROID BODY OR GLAND (GLANDULA THYREOIDEA) 
 
 (Fig. 997). 
 
 The thyroid gland is an extremely vascular body, situated at the front and 
 sides of the neck, and extending upward upon each side of the larynx. It is a 
 single gland, varying greatly in size in different individuals. It is larger relatively 
 in females and in children than in men. It is frequently asymmetrical. In early 
 embryonal life the gland has a duct, the thyro-glossal duct (ductus thyreoglossus) , 
 which passes from the isthmus of the thyroid to the foramen caecum of the dorsum 
 of the tongue. The lumen of this duct is obliterated early and becomes a cord of 
 epithelium. The lower portion of the duct often remains open for a little way. 
 The upper portion remains as the foramen caecum. The situation of this obliter- 
 ated foetal duct may be marked by the third or middle lobe of the thyroid gland. 
 The thyroid surrounds the upper portion of the trachea like a horseshoe. It con- 
 sists of two lateral lobes connected across the middle line by a narrow transverse 
 portion, the isthmus. 
 
 The weight of the gland is somewhat variable, but is usually about one ounce. 
 It is somewhat heavier in the female, in whom it becomes enlarged during men- 
 struation and pregnancy. As age advances the weight of the thyroid diminishes. 
 
 The color of the thyroid, as seen from the surface, is reddish-blue. The gland is 
 surrounded by a closely adherent thin connective-tissue capsule of the pre-tracheal 
 layer of deep cervical fascia. From the inner surface of the capsule come delicate 
 septa, which enter into the thyroid body and separate it into lobes and also sepa- 
 rate the lobes into lobules. The blood-vessels lie beneath the capsule. The ante- 
 rior and lateral portions of the gland are covered by the capsule. " Passing around 
 the side of the gland to its posterior surface, this capsule then splits into two por- 
 tions. One remains in contact with the glanfl and invests its posterior surface. 
 The other, the thicker of the two, passes to the posterior surface of the pharynx 
 
 ( 1401 ) 
 
1402 
 
 THE DUCTLESS GLANDS 
 
 and oesophagus, thus enclosing them with the larynx, trachea, and thyroid gland, 
 in a common sheath."^ 
 
 The lateral lobes are conical in shape, the apex of each being directed upward 
 and outward as far as the junction of the middle with the lower third of the thy- 
 roid cartilage; the base looks downward, and is on a level with the fifth or sixth 
 tracheal ring. The summit of the lateral lobe not unusually is pointed and reaches 
 to the level of the oblique line upon the ala of the thyroid cartilage or even higher. 
 The right is, as a rule, somewhat larger than the left lobe. The lower portion of 
 
 the gland, when the head is extended, is about 
 one inch above the upper margin of the ster- 
 num; when the head is flexed, it is at the level 
 of the upper border of the sternum or even 
 below and behind it. The portion of the 
 lateral lobe above the level of the superior 
 border of the isthmus is called the upper horn, 
 the portion below the level of the inferior mar- 
 gin of the isthmus is called the lower horn. The 
 lower horn "is usually much smaller than the 
 upper horn ; frequently it is altogether absent."^ 
 At the inner and posterior part of each lateral 
 lobe is the hilum. At the hilum the inferior 
 thyroid artery passes into the gland. "Here 
 the recurrent laryngeal nerve comes into close 
 contact with the gland, lying in the space be- 
 tween it and the trachea and oesophagus."' 
 
 The external or superficial surface is convex, 
 and covered by the skin, the superficial fascia, 
 the deep fascia, the Sterno-mastoid, the anterior 
 belly of the Omo-hyoid, the Sterno-hyoid and 
 Sterno-thyroid muscles, and beneath the last- 
 named muscles by the pre-tracheal layer of the 
 deep fascia, which forms a capsule for the 
 gland. 
 
 The deep or internal surface is moulded 
 over the underlying structures — viz., the thy- 
 roid and cricoid cartilages, the trachea, the 
 inferior constrictor and posterior part of the 
 Crico-thyroid muscles, the oesophagus (par- 
 ticularly on the left side of the neck), the supe- 
 rior and inferior thyroid arteries, and the recurrent laryngeal nerves. 
 
 The deep surface of each lobe is fixed by bands of fibrous tissue passing from 
 the capsule of the isthmus and lateral lobes to the sides of the cricoid cartilage and 
 the posterior fascia of the trachea. These bands are called the lateral or suspen- 
 sory ligaments. Because of this fixation to the larynx and trachea by the capsule 
 and by the lateral ligaments, the thyroid gland moves with the trachea and ascends 
 during the act of swallowing. The recurrent laryngeal nerve on each side is in 
 contact with the outer and posterior surface of the suspensory ligament. 
 
 The anterior border is thin, and inclines obliquely from above downward and 
 inward toward the middle line of the neck, while the posterior border is thick and 
 overlaps the common carotid artery. Each lobe is about two inches in length, its 
 greatest width is about one inch and a quarter, and its thickness about three- 
 quarters of an inch. The posterior border is over the common carotid artery and 
 
 Fig. 997.— The thyroid gland. (Spalteholz.) 
 
 1 Diseases of the Thyroid Gland. By James Berry. 
 
 « Ibid. 
 
 8 Ibid. 
 
THE THYROID BODY OB GLAND 1403 
 
 touches the oesophagus and pharynx. The carotid artery usually makes a groove 
 upon the gland. 
 
 The Isthmus (isthmus glandulae thyreoidea), — The isthmus connects the lower 
 third of the two lateral lobes; it measures about half an inch in breadth and the 
 same in depth, and usually covers the second and third rings of the trachea, but 
 sometimes also the first and fourth rings. Its situation presents, however, many 
 variations, a point of importance in the operation of tracheotomy. In the middle 
 line of the neck it is covered by the skin and fascia, and close to the middle line, 
 on either side, by the Sterno-hyoid muscle. Across its upper border run branches 
 of the superior thyroid artery and vein; at its lower border is a branch of the 
 inferior thyroid veins. Sometimes the isthmus is altogether wanting, the two 
 lateral lobes being completely separate. 
 
 The third, pjnramidal or middle lobe is called the pyramid of Lalouette. It is not 
 constant, but is frequently found. Occasionally it arises from the upper part of 
 the isthmus, or from the adjacent portion of either lobe, but most commonly from 
 the left lobe, and ascends in front of the thyroid cartilage in the direction of the 
 middle of the hyoid bone. It may reach the bone or may not reach it. If it 
 reaches the bone it is attached to it. If it does not reach the bone, fibrous tissue, 
 which often contains muscle, is prolonged from the tip of the pyramid to the 
 back of the bone or to the thyro-hyoid membrane. The pyramid is occasionally 
 quite detached, or divided into two or more parts, or altogether wanting, 
 
 A few muscular bands, derived from the Thyro-hyoid muscles, are occasionally 
 found attached, above, to the body of the hyoid bone, and below to the isthmus 
 of the gland or its pyramidal process. These form a muscle, which was named 
 by Soemmerring the Levator glandulae thyreoidae. 
 
 Accessory Thyroids {glandulae thyreoideae accessoriae). — Frequently small 
 isolated masses of thyroid tissue exist. They are found particularly about the 
 lateral lobes of the thyroid gland in the sides of the neck or just above the hyoid 
 bone, and are called accessory thyroids. Accessory thyroids may also exist by the 
 side of the pyramidal lobe or upon the trachea, as low even as the level of the arch 
 of the aorta. These isolated portions of gland tissue represent isolated portions 
 of the median thyroid rudiment. Sometimes accessory thyroid tissue is found 
 in the root of the tongue or in the interior of the larynx. Berry points out that a 
 distinction must be made between true congenital accessory thyroids and masses 
 of encapsuled thyroid tissue which "have been extruded from the gland." 
 
 Structure of the Th3n:oid (Fig. 998). — The thyroid body is invested by a thin 
 capsule of connective tissue which projects into its substance as a framework and 
 imperfectly divides it into masses of irregular form and size, known as lobules. 
 More slender septa separate the secretory alveoli from one another. When the 
 organ is cut into, it is of a brownish-red color, and is seen to be made up of a 
 number of closed vesicles or alveoli containing a yellow glairy fluid and separated 
 from each other by intermediate connective tissue. 
 
 According to Baber, who has published some important observations on the 
 minute structure of the thyroid,^ the vesicles of the thyroid of the adult animal 
 are generally closed cavities; but in some young animals {e.g., young dogs) the 
 vesicles are more or less tubular and branched. This appearance he supposes 
 to be due to the mode of growth of the gland, and merely indicating that an 
 increase in the number of vesicles is taking place. Each vesicle is lined by a single 
 layer of epithelium, the cells of which are cubical or cylindrical. Between the 
 epithelial cells exists a delicate reticulum. The vesicles are of various sizes and 
 shapes, and contain as a normal product a viscid, homogeneous, semi-fluid, 
 slightly yellowish material which frequently contains blood, the red corpuscles of 
 
 1 Researches on the Minute Structure of the Thyroid Glands, Phil. Trans., part iii., 1881, 
 
 k 
 
1404 
 
 THE DUCTLESS GLANDS 
 
 which are found in it in various stages of disintegration and decolorization, the 
 yellow tinge being probably due to the hoemoglobin, which is thus set free from 
 the colored corpuscles. This normal product is known as colloid material, and it 
 is secreted by the epithelium. What part if any the colloid plays in the formation 
 of the internal secretion of the gland is not known. It is cjuite possible that the 
 colloid corresponds to the external secretion of glands with ducts and that the 
 true internal secretion passes directly into the capillaries which form a network 
 about the alveoli (Szymonowicz), or passes into the lymphatics. In the thyroid 
 gland of the dog, Baber has found large round cells, parenchymatous cells, each 
 provided with a single oval-shaped nucleus, which migrate into the interior 
 of the gland-vesicles. Between the thyroid vesicles in the human being are col- 
 lections of romid cells. They are, in reality, miniature vesicles, and are much 
 more numerous in youth than in old age. 
 
 The capillary blood-vessels form a dense plexus in the connective tissue around 
 the vesicles, between the epithelium of the vesicles and the endothelium of the 
 lymph-spaces, which latter surround a greater or smaller part of the circumference 
 
 Vesicle. 
 
 Lymphatic vessel. 
 
 Wall of gland-vesicle 
 
 Fig. 998. — Minute structure of the thyroid. From a transverse section of the thyroid of a dog. 
 
 diagrammatic. (Baber.) 
 
 Semi- 
 
 of the vesicles. These lymph-spaces empty themselves into Isrmphatic vessels 
 which run in the interlobular connective tissue, not uncommonly surrounding the 
 arteries which they accompany, and communicate with a network in the capsule 
 of the gland. Small glands may be connected with this network. Baber has 
 found in the lymphatics of the thyroid a viscid material which is morphologically 
 identical with the normal constituent of the vesicle. 
 
 Vessels and Nerves.—The arteries (Figs. 392 and 393; see also p. 602) supply- 
 ing the thyroid are the superior thyroid from the external carotid, and the inferior 
 thyroid from the thyroid axis of the first part of the subclavian. Sometimes there 
 is an additional vessel, the thyroidea media or ima, usually arising from the 
 innominate artery, but sometimes from the arch of the aorta or the common caro- 
 tid. It ascends upon the front of the trachea. The superior thyroid artery reaches 
 the summit of the upper horn of the gland, and usually at this point gives off a 
 vessel which courses down the posterior surface of the gland. The main trunk 
 passes downward and inward at the junction of the inner and anterior border of 
 the upper horn, giving branches to adjacent structures and sending branches over 
 
THE THYROID BODY OR GLAND 1405 
 
 the anterior surface of the thyroid gland. It reaches the isthmus and crosses 
 the isthmus at its upper border to anastomose with the artery from the other side. 
 The inferior thyroid artery, which is usually larger than the superior, after it 
 has passed posterior to the sheath of the carotid and the sympathetic nerve, reaches 
 the posterior surface of the gland. At this point branches are given off; some pass 
 into the hilum; the others go to the posterior surface of the gland. The relation 
 of the artery to the recurrent laryngeal nerve is very important to the surgeon. 
 "Usually the main trunk of the artery passes behind the nerve; sometimes the 
 artery breaks up before reaching the nerve ; in this case one or more of the branches 
 may pass in front of it. Much less commonly the main trunk or all its branches 
 will be found to lie in front of the nerve. "^ If the thyroidea ima is present it goes 
 to the lower part of the gland. The larger branches of the thyroid arteries are 
 beneath the capsule and upon the surface of the gland; smaller branches pass to 
 the interior of the gland (Berry). The arteries are remarkable for their large 
 size and frequent anastomoses. 
 
 The thyroid veins (Figs. 447 and 448; see also p. 731) form a plexus upon the 
 surface of the gland and beneath the capsule. Here and there veins pass through 
 the capsule and go to adjacent venous trunks. Berry, accepting Kocher's descrip- 
 tion, notes the following veins: The superior thyroid vein runs with the superior 
 thyroid artery and passes to the internal jugular vein. A transverse vein of the 
 upper border of the isthmus joins the two superior thyroid veins. A single vein, 
 the middle thyroid, sometimes emerges from the side of the gland and passes to 
 the internal jugular. Usually, however, instead of this single vein there are two 
 veins, the superior and inferior accessory thj^rroids. The superior accessory thyroid 
 emerges from the outer side of the upper horn, below the apex, and passes to the 
 internal jugular. The inferior accessory thjrroid emerges from the posterior and 
 inferior portion of the gland and passes to the internal jugular. The veins from the 
 lower border of the gland vary greatly. A vein passes vertically down on each side 
 in front of the trachea from the isthmus and from the inner side of the inferior horn. 
 It is called by Kocher the thyroidea ima. The vein of the left side passes to the left 
 innominate; the vein of the right side passes to the right innominate or left innom- 
 inate. As Berry points out, the vein of one side may be small or may be absent, 
 or the two veins may unite and form one vein which enters the left innominate. 
 An inferior thyroid vein is often present. It is of small size, emerges at the inferior 
 and external part of the gland, and passes to the corresponding innominate vein.^ 
 
 The lymphatics are numerous and of large size. Collecting trunks arise from a 
 network within the capsule. Some trunks ascend from the upper margin of the 
 isthmus and reach the gland in front of the larynx ; others ascend along the superior 
 thyroid artery and reach the glands at the bifurcation of the carotid. Descending 
 trunks from the lower margin of the isthmus reach the glands in front of the 
 trachea; trunks from the side of the gland descend to the glands about the recur- 
 rent laryngeal nerve .^ 
 
 The nerves are derived from the middle and inferior cervical ganglia of the sym- 
 pathetic, and from the inferior lar3nigeal nerves. Probably there is also a branch 
 from each superior laryngeal nerve. 
 
 Surgical Anatomy. — The thyroid gland may be congenitally absent, and when it is the indi- 
 vidual suffers from the worst form of cretinism. One lobe may he congenitally absent, but 
 this will provoke no trouble unless the other lobe undergoes atrophy. 
 
 Complete removal of the thyroid and parathyroids will produce operative myxoedema (cachexia 
 strumi'priva) , unless accessory thyroids enlarge and perform the functions of the thyroid. 
 
 The thyroid gland may be congenitally enlarged. The gland tends to atrophy in old age. 
 It is atrophied in myxoedema and cretinisin. Some forms of thyroid enlargement are called 
 goitre. 
 
 1 Diseases of the Thyroid Gland. By James Berry. -Ibid. 
 
 ^ The Lymphatics. By Poirier, Cun6o, and Delamare. Translated and edited by Cecil H. Leaf. 
 
1406 
 
 THE DUCTLESS GLANDS 
 
 When all parts of the gland enlarge the condition is known as 'parenchymatous goitre. 
 
 Adenomatous goitre consists of an adenoma or of adenomata. In cystic goitre there is one 
 or more cysts due to cystic degeneration of adenomata or to fusion of adjacent follicles. 
 
 A pulsating goitre is one which receives impulses from the carotid pulsations. In a fibroid 
 goitre there is increase of interstitial connective tissue. A goitre which passes back of the sternum 
 IS known as substernal or intrathoracic. A goitre may extend back of the trachea or back of 
 the oesophagus. 
 
 Exophthalmic goitre, Graves's disease or Basedow's disease, is a remarkable disease. Its three 
 chief symptoms are enlargement of the thyroid, or goitre ; prominence of the eyeballs, or exoph- 
 thalmos, and very rapid pulse, or tachycardia. Dyspnoea, tremor, and various other symptoms 
 are usually found. The thyroid gland may be the seat of a carcinoma or sarcoma {malignant 
 goitre), syphilitic or tuberculous disease, ordinary inflammation, suppuration, or hydatid disease; 
 For the relief of ordinary goitre various methods have been employed. Tapping, injection of 
 astringents, simple incision, and the seton are obsolete. Ligature of the thyroid arteries is rarely 
 performed as a curative measure. The superior and inferior thyroids of one side have been tied 
 in some cases; all four thyroids in other cases. Jaboulay has performed exothyropexy. In this 
 operation the gland is dislocated from its bed, brought out of the wound, and left exposed, in 
 hope that it will atrophy 
 
 Division of the isthmus is occasionally practised to relieve dyspnoea. The operation some- 
 times succeeds, but often fails. 
 
 Extirpation of one-half or two-thirds of the gland is a very successful operation. Removal of 
 the entire gland with the parathyroids will be followed by operative myxoedema. 
 
 In extirpating a lobe of the thyroid great care must be taken to avoid tearing the capsules, as if 
 this happens the gland-tissue bleeds profusely. The thyroid arteries should be ligatured on the 
 diseased side before an attempt is made to remove the mass, and in ligaturing the inferior thy- 
 roid the position of the recurrent laryngeal nerve must be borne in mind, so as not to include 
 it in the ligature. 
 
 A cystic or solid tumor of the thyroid may be removed by intra glandular enucleation. If 
 operation becomes necessary in exophthalmic goitre, partial extirpation is usually preferred. 
 
 Bilateral extirpation of the cervical ganglia of the sympa- 
 thetic (sympathectomy or Jonnesco's operation) has been 
 practised by some surgeons for exophthalmic goitre. The 
 value of the procedure is uncertain. 
 
 Parathyroids (Fig. 999).— If the thyroid gland 
 has been carefully detached, two round bodies 
 of small size may be found embedded upon the 
 trachea or upon the surface of the lateral lobe of 
 the gland, between the terminal branches of the 
 inferior thyroid artery. "These are the para- 
 thyroids, about the size of orange-seeds, and 
 brownish-red in color."^ These masses are con- 
 stant in man and are more distinct in infants 
 than in adults. Although the parathyroids lie 
 on or in the thyroid, they are always completely 
 separated from it by capsules of connective 
 tissue. The parathyroids are divided from their 
 situation into external and internal. The former, 
 usually two in number, are situated, one on each 
 side, in relation to the postero-internal surface 
 of the lateral lobe; sometimes they are duplicated. 
 The latter, also usually two in number, are placed 
 one in or on each lateral lobe, generally near its 
 mesial surface. 
 
 Structure. — The structure of the parathyroids 
 
 is different from that of the thyroid. They are 
 
 composed of solid masses of epithelial cells arranged in a more or less columnar 
 
 fashion with numerous intervening capillaries. The columns of the para- 
 
 FiG. 999.— The position of the parathy- 
 roid glands. View from behind. (Zucker- 
 kandl.) 
 
 * Practical Anatomy. By Prof. Alfred W. Hughes. 
 
THE THYMUS GLAND 
 
 1407 
 
 thyroids anastomose. There is much lymphoid tissue connected with the 
 columns. Some regard the parathyroids as embryonic portions of the thyroid. 
 This view seems to gain probabihty from the statement that after complete 
 thyroidectomy, the parathyroids having been left, these structures increase in 
 size, and apparently prevent operative myxoedema. If they are also removed, 
 myxoedema arises. Nevertheless, MacCallum says "there is no histological proof 
 that parathyroid tissue can ever become converted into thyroid tissue." Most 
 observers regard the parathyroids as distinct glands possessed of a special func- 
 tion. Certain it is, as Gley and others have shown, removal of the parathyroids 
 from herbivora leaving the thyroid intact is followed by spasms, tetany, etc., just 
 as complete thyroidectomy is followed by such symptoms in carnivora.^ 
 
 THE THYMUS GLAND (Fig. 1000). 
 
 The thymus gland is a temporary organ, attaining its full size at the end of the 
 second year, when it ceases to grow and remains practically stationary until 
 puberty, at which period it rapidly degenerates. It does not entirely disappear, 
 for the shrunken and degenerated mass, even later in life, maintains a likeness to 
 the original form and retains within its substance small portions of thymus tissue 
 (Waldeyer). If examined when its growth is most active, it will be found to con- 
 
 FiG. 1000. — The thymus gland in an infant two months old. (Poiricr and Charpy.) 
 
 sist of two lateral lobes placed in close contact along the middle line, situated 
 partly in the superior mediastinum, partly in the neck, and extending from the 
 level of the fourth costal cartilage upward as high as the lower border of the 
 thvroid gland. It is covered by the sternum and by the origins of the Sterno- 
 hyoid and Sterno-thyroid muscles. Below, it rests upon the pericardium, being 
 
 1 Internal Secretions. By William Hanna Thom.«on. New York Medical Journal, November 19, 1904. 
 
1408 
 
 THE DUCTLESS GLANDS 
 
 separated from the arch of the aorta and great vessels by a layer of fascia. In the 
 neck it lies on the front and sides of the trachea, behind the Sterno-hyoid and 
 Sterno-thyroid muscles. The two lobes generally differ in size; they are occa- 
 sionally united so as to form a single mass, and are sometimes separated by an 
 intermediate lobe. The thymus is of a pinkish-gray color, is soft and is lobu- 
 lated on its surfaces. It is about two inches in length, one and a half inches 
 in breadth below, and about three or four lines in thickness. At birth it weighs 
 about half an ounce. 
 
 Structure (Figs. 1001 and 1002) . — Each lateral lobe is composed of numerous 
 lobules held together by delicate areolar tissue, the entire gland being enclosed in 
 an investing capsule of a similar but denser structure. The primary lobules vary 
 in size from a pin's head to a small pea, and are made up of a number of small 
 nodules or follicles which are irregular in shape and are more or less fused 
 together, especially toward the interior of the gland. Each follicle consists of a 
 medullary and cortical portion,which differ in many essential particulars from each 
 other. The cortical portion is mainly composed of lymphoid cells supported by a 
 
 delicate reticulum. In addition to this reticulum, of 
 which traces only are found in the medullary portion, 
 there is also a network of finely branched cells which 
 is continuous with a similar network in the medul- 
 lary portion. This network forms an adventitia to 
 the blood-vessels. In the medullary portion there 
 are but few lymphoid cells, but there are, especially 
 toward the centre, granular cells and concentric 
 corpuscles. The granular cells are rounded or 
 flask-shaped masses attached (often by fibrillated 
 extremities) to blood-vessels and to newly formed 
 coimective tissue. The concentric corpuscles are 
 composed of a central mass consisting of one or 
 more granular cells, and of a capsule which is 
 formed of epithelioid cells which are continuous 
 with the branched cells forming the network men- 
 tioned above. 
 
 Each follicle is surrounded by a capillary plexus 
 
 from which vessels pass into the interior and radiate 
 
 Fig. 1001.— Minute structure of thy- ^^om the periphery toward the centre, and form a 
 
 Ty.ntt-S^l'lpW'in length! ^^^^nd zouc just withiu the margin of the medullary 
 
 portion. In the centre of the medulla there are very 
 few vessels, and they are of minute size. 
 
 Watney has made the important observation that 
 haemoglobin is found in the thymus either in cysts 
 or in cells situated near to or forming part of the 
 concentric corpuscles. This haemoglobin varies 
 from granules to masses exactly resembling colored blood -corpuscles, oval in the 
 bird, reptile, and fish; circular in all mammals except in the camel. Dr. Watney 
 has also discovered in the lymph issuing from the thymus similar cells to those 
 found in the gland, and, like them, containing haemoglobin either in the form of 
 granules or masses. From these facts he arrives at the physiological conclusion 
 that the thymus is one source of the colored blood-corpuscles. 
 
 Vessels and Nerves. — The arteries supplying the thymus are derived from 
 the internal mammary and from the superior and inferior th3n'oid. The veins 
 terminate in the two innominate veins, and in the internal mammary and the 
 thyroid veins. The lymphatics are of large size, arise in the substance of the 
 gland, and are said to terminate in the internal jugular vein. The nerves are 
 
 showing the bud-Uke lobuH and gland 
 ular elements. 2, cells of the thymu;-, 
 mostly from a man ; a, free nuclei ; 
 h, small cells ; c, larger ; d, larger, with 
 oil-globules, from the ox ; e, i, cells 
 completely filled with fat, at / without 
 a nucleus ; g, h, concentric bodies ; a, 
 an encapsulated nucleated cell ; h, a 
 composite structure of a similar nature. 
 
THE CAROTID GLAND OB CAROTID BODY 
 
 1409 
 
 exceedingly minute; they are derived from the pneumogastxic and sympathetic. 
 Branches from the descendens hypoglossi and phrenic reach the investing cap- 
 sule, but do not penetrate into the substance of the gland. 
 
 Artery. 
 
 Artery 
 
 Fig. 1002. — Minute structure of the thymus gland. Follicle of injected thymus from a calf, four days old, 
 slightly diagramniatic, magnified about .50 diameters. The large vessels are dispo.sed in two rings, one of which 
 surrounds the follicle, the other lies just within the margin of the medulla. A and B, from thymus of camel, 
 examined without addition of any reagent. Magnified about 400 diameters. A, large colorless cell containing 
 small oval masses of haemoglobin. Similar cells are found in the lymph-glands, spleen, and medulla of bone ; 
 B, colored blood-corpuscles. (Watney.) 
 
 THE CAROTID GLAND OR CAROTID BODY (GLOMUS CAROTICUM). 
 
 This body, when present, lies in the carotid bifurcation, to the inner side of the 
 common carotid below the bifurcation, or on the posterior surface of the internal or 
 of the external carotid. It is often absent. It lies in fatty tissue and is surrounded 
 by a fibrous capsule which is attached to the carotid sheath. The carotid gland 
 is about the size of a grain of corn; it is oval in shape and reddish-brown in color. 
 The capsule of the gland sends septa inward. The septa divide the organ into 
 follicles or cell-balls. These cell-balls are composed of endothelial cells and are 
 associated with blood capillaries. A branch (or branches) from the carotid artery 
 enters the carotid gland, and the gland is closely connected with the carotid 
 plexus of the ssrmpathetic. (This structure has been recently studied by John 
 Funke,^ Reclus and Chevasson,^ Paltauf, Kartschenko, and Marchand.) 
 
 Surgical Anatomy. — Tumors may arise from this structure. Such a tumor is apt to be 
 above the level of the upper margin of the thyroid cartilage and in most cases it moves with 
 each arterial beat. 
 
 ' American Medicine, vol. viii., No. 3. 
 
 8 Bull, et mem. de la Soc. de chir. de Paris, 1903, No. 18. 
 
 89 
 
1410 THE DUCTLESS GLANDS 
 
 THE COCCYGEAL GLAND OR COCCYGEAL BODY OR LUSCHKA'S 
 GLAND (GLOMUS COCCYGEUM). 
 
 Lying near the tip df the coccyx in a small tendinous interval formed by the 
 union of the Levator ani muscles and just above the coccygeal attachment of 
 the Sphincter ani, is a small conglobate body about as large as a lentil or a pea, 
 first described by Luschka,' and named by him the coccygeal gland. Its most 
 obvious connections are with the arteries of the part. It is similar in structure 
 to the carotid body. 
 
 Structure. — It consists of a congeries of small arteries with little aneurismal 
 dilatations derived from the middle sacral and freely communicating with each 
 other. These vessels are enclosed in one or more layers of polyhedral granular 
 cells, and the whole structure is invested in a capsule of connective tissue which 
 sends in trabeculae, dividing the interior into a number of spaces in which the 
 vessels and cells are contained. Nerves pass into this little body from the sympa- 
 thetic, but their mode of termination is unknown. Macalister believes the glom- 
 erulus of vessels "consists of the condensed and convoluted metameric dorsal 
 arteries of the caudal segments embedded in tissue which is possibly a small per- 
 sisting fragment of the neurenteric canal." It resembles the carotid gland in 
 structure, and is probably one of the ductless glands. 
 
 1 Der Hirnanhang und die Steissdriise des Menschen, Berlin, 1860; Anatomic des Menschen, Tubingen, 1864, 
 vol. ii. pt. 2, p. 187. 
 
THE UUIMRY OEGANS. 
 
 THE KIDNEYS (RENES) (Figs. 1003, 1004, 1005). 
 
 THE Kidneys are large glands. They are two in number, and are situated 
 in the back part of the abdomen, near the spinal column. Their function is 
 to separate from the blood certain materials which, when dissolved in a quantity 
 of water, also separated from the blood by the kidneys, constitute the urine. 
 
 They are placed in the loins, one on each side of the vertebral column, behind 
 the peritoneum, and are surrounded by a mass of fat and loose areolar tissue, which 
 
 TERMINAL 
 
 PART OF 
 
 PROSTATE 
 
 VEIN 
 
 ORIGIN OF 
 
 DUCTUS YMy. 
 CHOLEOOCHUS flV' 
 
 FIBROUS 
 
 CAPSULE 
 
 PELVIS OF 
 
 KIDNEY 
 
 RIGHT 
 
 SPERMATIC 
 
 VEIN 
 
 LEFT 
 
 SPERMATIC 
 ARTERY 
 AND VEIN 
 
 FIBROUS 
 
 SUBPERITONEAL 
 
 LAMINA 
 
 Fig. 1003. — The situation, direction, forms, and supports of the kidney. (Sappey.) 
 
 constitutes the fatty capsule (capsula adi/posa) (Figs. 1008 and 1009). There are 
 two distinct layers in this fatty capsule. The superficial fatty layer is the pararenal 
 fat.^ Keen calls this layer the transversalis layer of fat, because it is derived from the 
 transversalis fascia.^ The deeper and thicker perirenal layer is the fxue perinephric 
 fat (Fig. 1009). The deeper layer of fat completely surrounds the kidney, and is 
 somewhat adherent to the fibrous renal capsule. The fat about the kidney does 
 
 1 See Gerota, Arch. f. Anatomic. Leipzic, 1895; Zuckerkandl, Medizinische Jahrbiicher, Vienna, 1883. 
 * W. W. Keen, in American Medicine, January 31, 1903. 
 
 (1411) 
 
1412 
 
 THE UBINABY OBQANS 
 
 not look like fat in other regions, but is soft, delicate, and of a canary yellow 
 color. These two layers are separated by a layer of connective tissue, which is 
 the posterior layer of the perirenal fascia, and is called by Zuckerkandl the retro-renal 
 fascia {jascia retrorenalis) {Y\g. 1008). The true capsule of the kidney [tunica 
 fibrosa) is thin, smooth, and glistening. The inner part of this capsule {tunica 
 muscularis) contains unstriated muscle fibres. The true capsule can be easily 
 separated from the underlying glandular structure. The upper extremity of the 
 kidney is on a level with the upper border of the twelfth dorsal vertebra, the lower 
 extremity on a level with the third lumbar vertebra (Fig. 1006). The right kidney 
 is usually on a slightly lower level than the left, probably on account of the vicinity 
 of the liver. In the female the kidneys are a little lower than in the male. 
 
 Each kidney is about four and a half inches in length, two to two and a half in 
 breadth, and rather more than one inch in thickness. The left is somewhat longer, 
 though narrower, than the right. The weight of the kidney in the adult male varies 
 from 4^ ounces to 6 ounces; in the adult female, from 4 ounces to b\ ounces. The 
 combined weight of the two kidneys in proportion to the body is about 1 in 240. 
 
 Fig. 1004. — Anterior surface of the kidney. 
 (Bourgery.) 
 
 Fig. 1005. 
 
 -Posterior surface of the kidney. 
 (Bourgery.) 
 
 The kidney has the characteristic form of a "flattened bean" (Spalteholz). It 
 is flattened on its sides and presents at one part of its circumference a hollow. 
 It is larger at its upper than at its lower extremity. The kidney presents for exam- 
 ination two surfaces, two borders, and an upper and lower extremity. 
 
 Surfaces. The Anterior Surface {jades anterior) (Figs. 1003 and 1004).— Its ante- 
 rior surface is convex, looks forward and outward, and is partially covered by peri- 
 toneum. The right kidney in its upper three-fourths is in contact with the pos- 
 terior part of the under surface of the right lobe of the liver. This area of the right 
 kidney is flattened {impressio hepatica). Toward its inner border it is covered by 
 the second part of the duodenum, while its lower and outer part is in relation with 
 the hepatic flexure of the colon. The relation of the second part of the duodenum 
 to the front of the right kidney is a varying one. The left kidney is covered above 
 by the posterior surface of the stomach, below the stomach by the pancreas, behind 
 which are the splenic vessels. The region in contact with the stomach is markedly 
 depressed {impressio gastrica). Its lower half is in contact with some of the coils 
 
THE KIDNEYS 
 
 1413 
 
 of the small intestine and sometimes with the third part of the duodenum. Near 
 its outer border the anterior surface lies behind the spleen and the splenic flexure 
 of the colon. 
 
 Fig. 1006. — Posterior surface of the kidneys. (Poirier and Cliarpy.) 
 
 Fig. 1007. — Relation of the kidney to the vertebral column, ribs, muscles, and lumbo-costal ligaments. 
 
 CPoirier and Charpy.) 
 
1414 
 
 THE U BINARY ORGANS 
 
 The kidneys are partly covered in front by peritoneum and partly uncovered. 
 On the right kidney, the hepatic area, that is to say that portion of the kidney 
 which produces the renal impression on the liver, is covered by peritoneum, which 
 therefore separates the kidney from the liver; the duodenal and colic areas are not 
 peritoneal, and these structures are connected to the kidney by loose connective 
 tissue; at the lower and inner extremity is a small area, the mesocolic area, which 
 is covered by a layer of peritoneum of the greater sac and by the colic vessels. 
 On the left kidney the gastric area is covered by the peritoneum of the lesser sac; 
 the pancreatic and colic areas are non-peritoneal ; while, as on the right side, at the 
 lower and inner extremity, is an area, mesocolic area, which is covered by the 
 peritoneum of the greater sac and by the colic vessels. 
 
 The Posterior Surface {jades 'posterior) (Fig. 1005) . — The posterior surface of the 
 kidney is flatter than the anterior and is directed backward and inward. It is 
 
 ELEVENTH 
 RIB 
 
 TWELFTH 
 RIB 
 
 POSTERIOR 
 
 LAMELLA OF 
 
 PERIRENAL 
 
 FASCIA 
 
 FAT BEHIND 
 PERIRENAL 
 
 FASCIA /' I 
 
 PERITONEUM 
 
 VESSELS OF 
 HILUM OF 
 KIDNEY 
 
 «/' SECTION 
 OF COLON 
 
 ANTERIOR 
 LAMELLA O 
 PERIRENAt 
 FASCIA 
 
 PERITONEUM 
 
 TRUE 
 
 PERINEPHRITIC 
 
 FAT 
 
 Fig. 1008. — Longitudinal section, showing the 
 arrangement of the capsule of the kidney. 
 (After Gerota.) 
 
 __ QUADRATUS LUM- 
 
 "SACRO-LUM BALIS BORUM MUSCLE 
 GROUP 
 
 Fig. 1009. — ^Transverse section, showing the relations 
 of the capsule of the kidney and the two layers of fat. 
 (After Gerota.) 
 
 entirely devoid of peritoneal covering, being embedded in areolar and fatty tissue. 
 It lies upon the Diaphragm, the anterior layer of the lumbar aponeurosis, the 
 external and internal arcuate ligaments, the Psoas and Transversalis muscles, 
 one or two of the upper lumbar arteries, the last dorsal, ilio-hypogastric, and 
 ilio-iiiguinal nerves. The lumbo-costal ligaments overlie the posterior surface of 
 the kidney (Fig. 1007). The right kidney rests upon the twelfth rib (Fig. 1007), 
 the left usually on the eleventh and twelfth ribs. The Diaphragm separates the 
 kirlney from the pleura as the pleura dips down to form the phrenico -costal sinus 
 (Fig. 987), but frequently the muscular fibres of the Diaphragm are defective or 
 absent over a triangular area immediately above the external arcuate ligament, 
 and when this is the case the perirenal areolar tissue is in immediate apposition 
 with the diaphragmatic pleura. In the lower part of the posterior surface of the 
 kidney is an impression produced by the Quadratus lumborum muscle and called 
 
THE KIDNEYS 1415 
 
 the impressio musculaxis. A little internal to this a flattening, caused by the Psoas 
 muscle, is often recognizable. At the upper part of the posterior surface is a sulcus 
 produced by contact with the Diaphragm. 
 
 Borders. The External Border (margo lateralis) (Figs. 1004 and 1005). — The 
 external border is convex, and is directed outward and backward, toward the 
 postero-lateral wall of the abdomen. On the left side it is in contact, at its upper 
 part, with the spleen (Fig. 1003). 
 
 The Internal Border (margo medialis) (Figs. 1004 and 1005). — The internal bor- 
 der is concave, and is directed forward, inward, and a little downward. It presents 
 a deep longitudinal fissure, bounded by a prominent overhanging anterior and 
 posterior lip. This fissure is named the hilum (Jiilus renalis) (Fig. 1010), and 
 allows of the passage of the vessels, nerves, and ureter into and out of the kidney. 
 
 Extremities. The Superior Extremity (extremitas superior) (Figs. 1004 and 1005. 
 — The superior extremity, directly slightly inward as well as upward, is thick and 
 rounded, and is surmounted by the suprarenal capsule (Fig. 1010), which covers 
 also a small portion of the anterior surface. 
 
 The Inferior Extremity (extremitas inferior) (Figs. 1004 and 1005). — The inferior 
 extremity, directed a little outward as well as downward, is smaller and thinner 
 than the superior. It extends to within two inches of the crest of the ilium. 
 
 At the hilum of the kidney the relative position of the main structures passing 
 into and out of the kidney is as follows: the vein is in front, the artery in the 
 middle, and the duct or ureter behind and toward the lower part (Fig. 1005). By 
 a knowledge of these relations the student may distinguish between the right and 
 left kidney. The kidney is to be laid on the table before the student on its 
 posterior surface, with its lower extremity toward the observer — that is to say, 
 with the ureter behind and below the other vessels; the hilum will then be directed 
 to the side to which the kidney belongs. 
 
 General Structure of the Kidney. — The kidney is surrounded by a distinct 
 investment of fibrous tissue (tunica fibrosa), which forms the firm, smooth, true 
 capsule covering the entire organ. The capsule passes over the margins of the 
 hilum, enters the interior of the kidney, and covers the wall of the sinus. The 
 true capsule is closely and firmly adherent to the renal pelvis where it is attached 
 to the sinus. It closely invests it, but can be easily stripped off, in doing which, 
 however, numerous fine processes of connective tissue which pass to the intrarenal 
 connective tissue and numerous small blood-vessels are torn through. Beneath 
 this fibrous layer a thin wide-meshed network of unstriped muscular fibre forms 
 an incomplete covering to the organ. When the true capsule is stripped off, the 
 surface of the kidney is found to be smooth, even, and of a deep-red color. 
 
 In infants fissures extending for some depth may be seen on the surface of the 
 organ, a remnant of the lobular construction of the gland (Fig. 1027). The kid- 
 ney is dense in texture, but is easily lacerable by mechanical force. In order to 
 obtain a knowledge of the structure of the gland, a vertical section must be made 
 from its convex to its concave border, and the loose tissue and fat removed 
 around the vessels and the excretory duct (Fig. 1010). It will be then seen that 
 the kidney consists of a central cavity surrounded at all parts but one by the 
 proper kidney-substance. This central cavity is called the sinus (sinus renalis), 
 and is lined by a prolongation of the fibrous coat of the kidney, which enters 
 through a longitudinal fissure, the hilum (hilus renalis) (Fig. 1010), which is 
 situated at that part of the cavity which is not surrounded by kidney structure. 
 Through this fissure the blood-vessels of the kidney and its excretory duct pass, 
 and therefore these structures, upon entering the kidney, are contained within the 
 sinus (Fig. 1004). The excretory duct or ureter, after entering, dilates into a wide, 
 funnel-shaped sac named the pelvis (pelvis renalis) (Figs. 1010 and 1011). This 
 divides into two or three tubular divisions, which subdivide into several short, 
 
1416 
 
 THE URINARY ORGANS 
 
 truncated branches named calices or infundibula {calyces renales), all of which 
 are contained in the central cavity of the kidney (Figs. 1010 and 1011). The 
 blood-vessels of the kidney, after passing through the hilum, are contained in 
 the sinus or central cavity, lying between its lining membrane and the excretory 
 apparatus, before entering the kidney-substance (Fig. 1011). 
 
 This central cavity, as before mentioned, is surrounded on all sides except at 
 the hilum by the substance of the kidney, which is at once seen to consist of two 
 parts — viz., of an external granular investing part, which is called the cortical 
 portion {substantia corticalis) ; and of an internal part, the medullary portion {sub- 
 stantia medullaris) , made up of a number of dark-colored pyramids, with their 
 bases resting on the cortical part and their apices converging toward the centre, 
 where they form prominent papillae, the renal papillae {papillae renales), which 
 project into the interior of the calices (Fig. 1010). 
 
 SUPERIOR 
 EXTREMITY 
 
 CUT SURFACE 
 OF KIDNEY 
 
 Fig. 1010.— Vertical section of kidney. 
 
 INFERIOR 
 EXTREMITY 
 
 Fig. 1011. — The right kidney with its pelvis exposed, viewed 
 from behind. (Spalteholz.) 
 
 The cortical substance (Figs. 1010 and 1017) is of a bright reddish-brown color, 
 soft, granular, and easily lacerable. It is found everywhere immediately beneath 
 the capsule, and is seen to extend in an arched form over the base of each medul- 
 lary pyramid. Prolongations of the cortical substance pass between the pyramids 
 toward the renal sinus. These prolongations are the cortical columns or the columns 
 of Bertin {columnae renales) (Fig. 1010, B B). The columns contain blood-vessels, 
 nerves, and lymphatics. The base of each pyramid (basis pyramidis) is known 
 as the intermediate zone. That portion of the cortical substance which stretches 
 from one cortical column to the next, and intervenes between the base of the 
 pyramid and the capsule (marked by the dotted line extending from A to A' in Fig. 
 1010), is called a cortical arch, the depth of which varies from a third to half an inch. 
 
 The medullary substance (Figs. 1010 and 1017), as before stated, is seen to con- 
 sist of red-colored, striated, conical masses, the pyramids of Malpighi {pyramides 
 
THE KIDNEYS 
 
 1417 
 
 
 renales) (Fig. 1010), the number of which, varying from eight to eighteen, corre- 
 sponds to the number of lobes of which the organ in the foetal state is composed. 
 The pyramids are composed of straight tubes which pass between the apices of 
 the papillae and the cortical margin. They enter the cortex in masses called the 
 pyramids of Ferrein (see below). The sides of the pyramids of Malpighi are con- 
 tiguous with the cortical columns, while the apices, known as the papillae of the 
 kidney (papillae renales) (Figs. 1010 and 1014), project into the calices of the 
 ureter, each calyx receiving two or three papillae. Radiating from the bases of 
 the pyramids of Malpighi are ridges of cortical substance with distinct depres- 
 sions between them. These ridges are the medullary rays (pars radiate) or P3n:a- 
 mids of Ferrein (Figs. 1013 and 1017). The labyrinth of the cortex (Fig. 1013) is 
 constituted by the kiflney substance between the rays. The pyramids of Ferrein 
 
 look like direct continuations of the medullary sub- 
 
 stance, but, in reality, they are in the cortex, and are 
 formed by the straight tubes extending in masses into 
 the cortex. The pyramids of Ferrein are much smaller 
 than the pyramids of Malpighi. In the columns of 
 Bertin blood-vessels, nerves, and lymphatics pass to and 
 emerge from the sinus by way of small foramina. The 
 summit of a papilla contains a number of orifices of 
 papillary ducts. Such an area is called an area cribrosa 
 (Fig. 1014). 
 
 These two parts, cortical and medullary, so dissimilar 
 in appearance, are very similar in structure, being 
 made up of urinary tubes and blood-vessels united and 
 bound together by a connecting matrix or stroma. 
 
 Minute Anatomy. — The uriniferous tubes, urinary canals 
 or tubuli urinif eri {tvbuli renales) (Figs. 1012 and 1017), 
 of which the kidney is for the most part made up, 
 commence in the cortical portion of the kidney. Each 
 tubule begins between the medullary rays (Fig. 1013) 
 in a sac, Bowman's capsule or the Malpighian capsule 
 (see below) . The tubules, as a rule, after pursuing 
 a very circuitous course through the cortical and medul- 
 lary parts of the kidney, finally terminate at the apices 
 of the Malpighian pyramids by open mouths, so that 
 the fluid which they contain is emptied into the 
 dilated extremity of the ureter contained in the sinus 
 of the kidney. " If the surface of one of the papillae 
 is examined with a lens, it will be seen to be studded 
 over with a number of small depressions (foramiria 
 papillaria), from sixteen to twenty in number, and in 
 a fresh kidney, upon pressure being made, fluid will 
 be seen to exude from these depressions. They are the orifices of the tubuli 
 uriniferi, which terminate in this situation. The tubuli uriniferi begin in the cortex 
 as the Malpighian bodies or corpuscles (corpuscula renis) (Figs. 1012, 1013, 1015, 
 1016, and 1018), which are smaU rounded masses, varying in size, but average 
 about yfg- of an inch in diameter. They are of a deep-red color, and are found 
 only in the cortical portion of the kidney. Each of these little bodies is composed 
 of two parts — a central glomerulus of vessels, called a Malpighian tuft, and a mem- 
 branous envelope, the Malpighian capsule or capsule of Bowman (capsida glomeruli), 
 which latter is a small pouch-like commencement of a uriniferous tubule. 
 
 The Malpighian Tuft or Vascular Glomerulus (Figs. 1015, 1016, 1017, 1022, and 
 1023) is a network of convoluted capillary blood-vessels held together by scanty 
 
 Fig. 1012. — Plan of uriniferous 
 tubes. A A , Malpighian bodies ; 
 B B, margin of medullary struc- 
 ture ; C, C. C, loop.s of Henle ; 
 
 D, D, D, straight tubes cut off ; 
 
 E, commencing straight tubes ; 
 
 F, termination of straight tube or 
 the excretory tube. 
 
1418 
 
 THE URINARY ORGANS 
 
 connective tissue and grouped into from two to five lobules. This capillary net- 
 work is derived from a small arterial twig, the afferent vessel, which pierces the wall 
 of the capsule, generally at a point opposite that at which the latter is connected 
 with the tube; and the resulting efferent vessel emerges from the capsule at the same 
 
 TUNICA.. 
 ALBUGINEA 
 
 LABYBINTH 
 OF CORTEX 
 
 MEDULLARY .. 
 RAYS 
 
 INTERLOBULA 
 VEIN 
 
 f-jL, CONVOLUTED 
 
 ^_ MALPIGHIAN 
 JZ'^ CORPUSCLES 
 
 interlobular 
 --''artery 
 
 AREA CRIBROSA 
 
 EXCRETORY 
 TUBULES 
 
 Fig. 1013. — Part of a section through the cortex of the kidney in the direction of the straight tubules. (Toldt.) 
 
 point. The afferent vessel is usually the larger of the two (Fig. 1015). The Mal- 
 pighian or Bowman's capsule (capsula glomeruli) (Figs. 1015, 1016, and 1017), which 
 surrounds the glomerulus, is formed of a hyaline membrane supported by a small 
 amount of connective tissue which is continuous with the connective tissue of the 
 
 tube. It is lined on its inner surface 
 with a layer of squamous epithelial 
 cells which are reflected from the 
 lining membrane on to the glomerulus 
 at the point of entrance or exit of the 
 afferent and efferent vessels. The 
 whole surface of the glomerulus is 
 covered with a continuous layer of 
 the same cells on a delicate support- 
 ing membrane, which with the cells 
 dips in between the lobules of the 
 glomerulus, closely surrounding them 
 (Fig. 1016). Thus, between the 
 glomerulus and the capsule a space 
 is left, forming a cavity lined by a 
 continuous layer of cells, which 
 varies in size according to the state 
 of secretion and the amount of fluid 
 present in it. The cells, as above 
 stated, are squamous in the adult, 
 but in the foetus and young subject they are polyhedral or even columnar. 
 
 The Tubuli Uriniferi, commencing in the Malpighian bodies, in their course 
 present many changes in shape and direction (tubuli renales contorti), and are 
 
 WALL OF RENAL CALYX 
 
 Fig. 1014. — Area cribrosa of renal papilla. (Toldt.) 
 
THE KIDNEYS 
 
 1419 
 
 contained partly in the medullary and partly in the cortical portions of the organ. 
 At the junction of a tubule with the Malpighian capsule there is a somewhat 
 constricted portion which is termed the neck (Fig. 1018). Beyond this the tubule 
 becomes convoluted, and pursues a considerable course in the cortical structure, 
 constituting the proximal or first convoluted tubule (Figs. 1017 and 1018). After a 
 time the convolutions disappear, and the tubule approaches the medullary portion 
 of the kidney in a more or less spiral manner. This section of the tubule has 
 been called the spiral tube of Schachowa (Fig. 1018). Throughout this portion 
 of their course the tubuli uriniferi have been contained entirely in the cortical 
 structure, and have presented a pretty uniform calibre. They now enter the 
 medullary portion, and suddenly become much smaller, quite straight in direc- 
 tion (tubidi renales recti), and each tubule dips down for a variable depth into 
 the pyramids, constituting the descending limb of Henle's loop (Figs. 1017 and 
 1018). Bending on itself, it forms a kind of loop near the apex of the pyramid, 
 the loop of Henle, and, reascending, becomes suddenly enlarged and again spiral 
 in direction, forming the ascending limb of Henle's loop (Figs. 1017 and 1018), 
 
 Fig. 1015. — Minute structure of kidney. 
 
 Bowman'i 
 capsule. 
 
 -.-) Vascular 
 glomerulus. 
 
 Fig. 1016. — Malpighian body. 
 
 and re-enters the cortical structure. This portion of the tubule does not present 
 a uniform calibre, but })ecomes narrower as it ascends and irregular or somewhat 
 spiral in outline (Fig. 1018). As a narrow tube it enters the cortex and ascends 
 for a short distance, when it again becomes dilated, irregular, and angular. This 
 section is termed the irregular tubule (Fig. 1018); it terminates in a convoluted 
 tubule which exactly resembles the proximal convoluted tubule; and is called the 
 distal or second convoluted tubule (Figs. 1017 and 1018). This again terminates 
 in a narrow curved or junctional tubule, which enters the straight or collecting 
 tube. 
 
 Each straight collecting or receiving tube (Figs. 1012, 1017, and 1018) com- 
 mences by a small orifice on the summit of a papilla, thus opening and discharg- 
 ing its contents into the interior of one of the calices. Traced into the substance 
 of the pyramid, these tubes are found to run from apex to base, dividing 
 dichotomously in their course and slightly diverging from each other. Thus 
 dividing and subdividing, they reach the base of the pyramid, and enter the 
 cortical structure greatly increased in number. Upon entering the cortical por- 
 tion they continue a straight course for a variable distance, and are arranged in 
 groups, several of these groups corresponding to a single pyramid. The tubes in 
 the centre of the group are the longest, and reach almost to che surface of the kid- 
 ney, while the external ones are shorter, and advance only a short distance into 
 the cortex. In consequence of this arrangement the cortical portion presents a 
 number of conical masses, the apices of which reach the periphery of the organ, 
 
1420 
 
 THE URINARY ORGANS 
 
 and the bases are applied to the medullary portion. These are termed the medul- 
 laxy rays or the pjrramids of Ferrein (Fig. 1013; also p. 1417). As they run through 
 the cortical portion the straight tubes receive on either side the curved extremity 
 of the convoluted tubes, which, as stated above, commence at the Malpighian 
 bodies. Each collecting tube receives a number of tubules, and several collecting 
 tubes unite together to form a papillary duct (Fig. 1017) and open by a foramen 
 (Fig. 1014) at the surface of the papilla. 
 
 Cortex 
 
 Medullary 
 
 Medulla 
 
 terlob- 
 ularis 
 
 Fig. 1017. — Diagrammatic representation of the course of the urinary canals (left) and the kidney vessels 
 (right). The arteries are red, the veins blue; capsules of Bowman, convoluted tubules I. order and loops of 
 Henle are black; convoluted tubules II. order and collecting tubules gray. I.. II., III., IV., four kidney 
 lobules: a, vas afferens; e, vas efferens. 1, Bowman's capsule; 2, convoluted tubule I. order; 3, descending 
 limb of loop of Henle; 4, ascending limb of loop of Henle; 5, convoluted tubule II. order; 6, 7, collecting 
 tubules; 8, papillary duct. (Szymonowicz.) 
 
 It will be seen from the above description that there is a continuous series 
 of tubes from their commencement in the Malpighian bodies to their termina- 
 tion at the orifices on the apices of the pyramids of Malpighi, and that the urine. 
 
THE KIDNEYS 
 
 1421 
 
 1^0^ Junctional 
 
 conyo- tubaie. 
 
 luted t 
 tubule. 
 
 the secretion of which commences in the capsule, finds its way through these 
 tubes into the caHces of the kidney, and so into the ureter. To recapitulate: 
 the tube first presents a con- 
 stricted portion, (1) the neck. 
 2. It forms a wide convoluted 
 tube, the proximal convoluted 
 tube. 3. It becomes spiral, the 
 spiral tubule of Schachowa. 4. It 
 enters the medullary structure 
 as a narrow, straight tube, the 
 descending limb of Henle's loop. 
 
 5. Forming a loop and becom- 
 ing dilated, it ascends somewhat 
 spirally, and, gradually dimin- 
 ishing in calibre, again enters 
 the cortical structure, the as- 
 cending limb of Henle's loop. 
 
 6. It now becomes irregular 
 and angular in outline, the 
 irregular tubule. 7. It then be- 
 comes convoluted, the distal 
 convoluted tubule. 8. Diminish- 
 ing in size, it forms a curve, the 
 curved or junctional tubule. 9. 
 Finally, it joins a straight tube, 
 the straight collecting tube, which 
 is continued downward through 
 the medullary substance and 
 joins other straight tubes to 
 form a papillary duct, which 
 
 opens in a foramen at the apex Fig. lOlS.— Uriniferous tube. For the sake of clearness the 
 /-kf Q r»A7ramirl epithelial cells have been represented more highly magnified than 
 
 a pyramiQ.* the tubes in which they are contained. 
 
 Descending limb \ 
 of Henle's loop. J 
 
 Fig. 1019.'— Longitu- Fio. 1020.— Longitu- 
 dinal section of Henle's dinal section of straight 
 descending limb: a, tube: i, cylindrical or 
 membrana propria ; b, cubical epithelium ; b, 
 epithelium. membrana propria. 
 
 Fig. 1021. — Transverse section of pyramidal substance of 
 kidney of pig, the blood-vessels of which are injected: n, large 
 collecting tube cut across, lined with cylindrical epithelium; 
 h, branch of collecting tube cut across, lined with epithelium 
 with shorter cylinders; c and rf. Henle's loops cut across ; e, 
 blood-vessels cut across ; D, connective-tissue ground-sub- 
 stance. 
 
 The Tubuli Uriniferi: their Structure (Figs. 1019, 1020, and 1021. — 
 The tubuli uriniferi consist of basement-membrane lined with epithelium. The 
 
 1 From Handbook for the Physiological Laboratory. 
 
1422 
 
 THE URINARY ORGANS 
 
 epithelium varies considerably in different sections of the uriniferous tubes. In 
 the neck the epithelium is continuous with that lining the Malpighian capsule, 
 and, like it, consists of flattened cells with an oval nucleus (Fig. 1016). The cells 
 are, however, very indistinct and difficult to trace, and the tube has here the 
 appearance of a simple basement-membrane unlined with epithelium. In the 
 proximal convoluted tubule and the spiral tubule of Schachowa the epithelium is 
 polyhedral in shape, the sides of the cells not being straight, but fitting into 
 each other, and in some animals so fused together that it is impossible to make 
 out the lines of junction. In the human kidney the cells often present an angular 
 projection of the surface next the basement-membrane. These cells are made 
 up of more or less rod-like fibres, which rest by one extremity on the basement- 
 membrane, whilst the other projects toward the lumen of the tube. This gives 
 to the cells the appearance of distinct striation. In the descending limb of Henle's 
 loop the epithelium resembles that found in the Malpighian capsule and the 
 commencement of the tube, consisting of flat transparent epithelial plates with 
 an oval nucleus (Fig. 1019). In the ascending limb, on the other hand, the 
 cells partake more of the character of those described as existing in the prox- 
 imal convoluted tubule, being polyhedral in shape and presenting the same 
 
 appearance of striation. The 
 6 B c _6 
 
 nucleus, however, is not situ- 
 ated in the centre of the cell, 
 but near the lumen (Fig. 
 1021). After the ascending 
 limb of Henle's loop becomes 
 narrower upon entering the 
 cortical structure, the stria- 
 tion appears to be confined 
 to the outer part of the cell; 
 at all events, it is much more 
 distinct in this situation, the 
 nucleus, which appears flat- 
 tened and angular, being still 
 situated near the lumen. In 
 the irregular tubule the cells 
 undergo a still further change, 
 becoming very angular, and 
 presenting thick bright rods 
 or markings, which render the 
 striation much more distinct 
 
 a A 
 
 Fig. 1022. — Diagrammatic 
 sketch of the blood- ves.sels of 
 the kidney. 
 
 Fig. 1023.— a portion of Fig. 1022 
 
 enlarged. (The references are the 
 
 same.) 
 
 A, a, interlobar artery and vein, the former giving off the renal , . , j.' e 
 
 afferents, the latter receiving the renal efferents ; b, b, interlobular than lU any Othcr SCCtlOU OI 
 
 artery and vein, the latter commencing from the stellate veins, and ,i • ■ i i y ii 
 
 receiving branches from the plexus around the tubuli contorti, the tnC UriUary lUDUlCS. in lUe 
 
 former giving off renal afferents ; c, straight tube, surrounded by j:qJ.„1 r>nnvnliit<^fJ tnhlllp tliA 
 
 tubuh contorti, with which it communicates, as more fully .shown in liioiai ».,«jii vi^nutou iiiuuic nio 
 
 Fig. 1023 ; n, margin of meduUarv substance ; e, e, e, receiving tubes oniflitiliiiin •ir»rkf»ar«! in Kf» 
 
 cut off; F, /, arteriolae et venae rectae, the latter arising from (G) the epiiuetiuiii cippcdis lu uc 
 
 plexus at the medullary apex; X, vascular glomerulus; w, the arcuate somewhat similar tO that 
 
 artery and vein. . mi 
 
 which has been described as 
 existing in the proximal convoluted tubule, but presents a peculiar refractive 
 appearance. In the curved tubule, just before its entrance into the straight 
 collecting tube, the epithelium varies greatly as regards the shape of the cells, 
 some being angular with short processes, others spindle-shaped, others poly- 
 hedral. 
 
 In the straight tubes the epithelium is more or less columnar; in its papillary 
 portion the cells are distinctly columnar and transparent (Fig. 1020), but as the 
 tube approaches the cortex the cells are less uniform in shape; some are poly- 
 hedral, and others angular with short processes. 
 
THE KIDNEYS 
 
 1423 
 
 The Renal Blood-vessels. — The kidney is plentifully supplied with blood by 
 the renal artery (Figs. 422, 423, 1005, and 1011), a large offset of the abdominal 
 aorta. Previously to entering the kidney, each artery divides into four or five 
 branches, which are distributed to its substance. At the hilum these branches 
 lie between the renal vein and ureter, the vein being in front, the ureter behind. 
 Each vessel gives off a small branch to the suprarenal capsules, the ureter, and 
 the surrounding cellular tissue and muscles. It has been pointed out by Hyrtl 
 (p. 679) that the renal artery gives off a branch which divides and supplies the 
 dorsal portion of the kidney and a branch which divides and supplies the ventral 
 portion of the kidney (Figs. 422 and 423). Between these two vascular systems 
 is a non-vascular zone, called by Byron Robinson the exsanguinated renal 
 zone of Hyrtl (Figs. 422 and 423). It " is one-half inch dorsal to the lateral 
 longitudinal renal border."^ Frequently there is a second renal artery, which is 
 given off' from the abdominal aorta at a lower level, and supplies the lower por- 
 tion of the kidney. It is termed the inferior renal artery. The branches of the 
 renal arteries pass to the kidney substance between the pyramids and are 
 known as interlobar arteries (arteriae interlobares renis) (Figs. 1013, 1017, 1024, 
 and 1025). At the junction of the cortical and medullary portions these vessels 
 turn and for a short distance pursue a course parallel to the kidney surface. 
 There are thus formed a series of incomplete vascular arches across the bases 
 of the pyramids, the arcuate arteries (arteriae arciforvies) (Figs. 1017, 1022, and 
 1023). From these arches two sets of vessels come. The vessels of one set go 
 to the periphery and enter the labyrinth, those of the other set pass toward the 
 c?ntre and enter the intermediate zone of the medulla. These last vessels are 
 the arteriolae recti (Figs. 1017, 1022, and 1023). 
 Bfcause of these vessels the kidney exhibits stria- 
 tions on section. Each of the arteriolae recti 
 in the medulla divides into numerous small 
 branches which are nearly parallel to each other 
 
 Figs. 1024 and 1025. — Lobar circulation. Interlobar 
 circulation. (Poirier and Charpy.) 
 
 Fig. 1026. — Diagrammatic representation 
 of the blood-vessels in the substance of the 
 cortex of the kidney: m, region of the 
 medullary ray ; b, region of the tortuous 
 portion of the tubules ; ai, interlobular 
 artery; rt, interlobular vein; ?o, vas affer- 
 ens ; gl, glomerulus ; ve, vas efferens ; vz, 
 venous twig of the interlobularis. (From 
 Ludwig, in Strieker's Handbook.) 
 
 and supply the tubules of this region. The arteries which arise from the arches 
 and pass to the periphery are the interlobular arteries {arteriae inierlobidares) 
 (Figs. 1017, 1022, 1023, and 1026). They traverse the labyrinth and pass toward 
 the surface of the kidney. A number of short branches, the vasa afferentia, are 
 given off by the interlobular arteries (Figs. 1017, 1022, 1023, and 1026). Each 
 afferent vessel passes to a capsule of Bowman. On reaching the capsule the 
 vessel forms a capillarv mass, the glomerulus, which is within the invaginated 
 capsule (Figs. 1016, 1017, 1023, and 1026) . 
 
 1 Byron Robinson, p. 679. 
 
1424 
 
 THE URINARY ORGANS 
 
 Emerging from each glomerulus is a small vessel, the vas efEerens (Figj. 1015, 
 1016, 1017, 1023, and 1026). This vessel divides into capillaries which are dis- 
 tributed to the tubules of the labyrinth and medullary rays. Blood is gathered 
 from the capillaries about the tubules by veins which correspond to the inter- 
 lobular arteries and arteriolae recti. These veins form a set of arches across 
 the bases of the pyramids. From the arches veins arise and pass between the 
 pyramids to the sinus of the kidney, where they unite and form branches of 
 the renal vein. 
 
 Nerves of the Kidney. — The nerves of the kidney, although small, are about 
 fifteen in number. They have small ganglia developed upon them, and are derived 
 from the renal plexus, which is formed by branches from the solar plexus, the 
 lower and outer part of the semilunar ganglion and aortic plexus, and from the 
 lesser and smallest splanchnic nerves. They communicate with the spermatic 
 plexus, a circumstance which may explain the occurrence of pain in the testicle in 
 affections of the kidney. So far as they have been traced, they seem to accompany 
 the renal artery and its branches, but their exact mode of termination is not 
 known. 
 
 The Lymphatics. — The lymphatics consist of a superficial and deep set. 
 The superficial lymphatics are just beneath the capsule. From them come two 
 sets of collecting trunks (Sappey). One set joins the deep collectors by entering 
 
 the kidney substance or passing to the hilum. Another 
 set pass into the lymphatics of the fatty capsule. 
 
 The deep collectors emerge from the hilum and lie 
 about the renal artery and vein. From the right kidney 
 some of the trunks pass to the glands about the vena 
 cava and possibly also in the glands in front of the 
 aorta. Others end in the glands back of the vena cava 
 (Stahr). 
 
 From the left kidney the trunks pass to the glands 
 which lie along the left side of the abdominal aorta.^ 
 The lymphatics of the fatty capsule of the kidney pass 
 to the same glands as do the deep collectors of the 
 kidney (Stahr). 
 
 Connective Tissue or Intertubular Stroma. — Although 
 the tubules and vessels are closely packed, a certain 
 small amount of connective tissue, continuous with the 
 capsule, binds them firmly together. This tissue was 
 first described by Goodsir, and subsequently by Bow- 
 man. Ludwig and Zawarykin have observed distinct fibres passing around the 
 Malpighian bodies, and Henle has seen them between the straight tubes com- 
 posing the medullary structure. 
 
 Variations and Abnormalities. — Congenital absence of the kidney has been 
 observed. Not unusually one kidney is considerably larger than the other; occa- 
 sionally one is very large and the other is very small, from atrophy, the large 
 organ having become large in response to a functional need, which causes it to 
 compensate for the insufficiency of the small kidney. If a kidney is removed 
 surgically, the other kidney enlarges. As previously stated, the kidneys of the 
 foetus and of the young child show distinct fissures which makes each organ 
 lobulated (Fig. 1027). The adult kidneys frequently exhibit remains of these 
 fissures. A horseshoe kidney is a condition in which the lower poles of the two 
 kidneys are united by kidney structure, the bond of union crossing the middle line. 
 The strip of kidney tissue which effects the junction may be slight in amount, 
 
 riG.1027. — Foetal kidney, showing 
 lobes. (Testut.) 
 
 1 The Lymphatics. By Poirier, Cun^o, and Delamare. Translated and edited by Cecil H. Leaf. 
 
THE KIDNEYS 1425 
 
 considerable, or extensive. Sometimes the two kidneys are completely fused 
 together into one large organ with two ureters. 
 
 Surface Form. — The kidneys, being situated at the back part of the abdominal cavity and 
 deeply placed, cannot be felt unless enlarged or misplaced. They are situated on the confines 
 of the epigastric and umbilical regions internally, with the hypochondriac and lumbar regions 
 externally. The left is somewhat higher than the right. According to Morris, the position of 
 the kidney may be thus defined: Anteriorly: "1. A horizontal line through the umbilicus is 
 below the lower edge of each kidney. 2. A vertical line carried upward to the costal arch from 
 the middle of Poupart's ligament has one-third of the kidney to its outer side and two-thirds to 
 its inner side — i. e., between this line and the median line of the body." In adopting these lines 
 it must be borne in mind that the axes of the kidneys are not vertical, but oblique, and if con- 
 tinued upward would meet about the ninth dorsal vertebra. Posteriorly: The upper end of the 
 left kidney would be defined by a line drawn horizontally outward from the spinous process of the 
 eleventh dorsal vertebra, and its lower end by a point two inches above the iliac crest. The right 
 kidney would be half to three-quarters of an inch below. Morris lays down the following rules 
 for indicating the position of the kidney on the posterior surface of the body: " 1. A line parallel 
 with, and one inch from, the spine, between the lower edge of the tip of the spinous process 
 of the eleventh dorsal vertebra and the lower edge of the spinous process of the third lumbar 
 vertebra. 2. A line from the top of this first line outward at right angles to it for two and three- 
 quarter inches. 3. A line from the lower end of the first transversely outward for two and three- 
 quarter inches. 4. A line parallel to the first and connecting the outer extremities of the second 
 and third lines just described." 
 
 The hilum of the kidney lies about two inches from the middle line of the back, at the level 
 of the spinous process of the first lumbar vertebra. 
 
 Surgical Anatomy. — Cases of congenital absence of a kidney, of atrophy of a kidney, and 
 of horseshoe kidney are of great importance, and must be duly taken into account, when neph- 
 rectomy is contemplated. A more common malformation is where the two kidneys are jused 
 together. They may be only joined together at their lower ends by means of a thick mass of 
 renal tissue, so as to form a horseshoe-shaped body, or they may be completely united, forming 
 a disk-like kidney, from which two ureters descend into the bladder. These fused kidneys are 
 generally situated in the middle line of the abdomen, but may be misplaced as well. 
 
 One or both kidneys may be misplaced as a congenital condition, and remain fixed in this 
 abnormal position. They are then very often misshapen. They may be situated higher or lower 
 than normal or removed farther from the spine than usual or they may be displaced into the 
 iliac fossa, over the sacro-iliac joint, on to the promontory of the sacrum, or into the pelvis 
 between the rectum and bladder or by the side of the uterus. In these latter cases they may 
 give rise to very serious trouble. The kidney may also be misplaced as a congenital condition, 
 but may not be fixed. It is then known as a floating kidney. It is believed to be due to the 
 fact that the kidney is completely enveloped by peritoneum, which then passes backward to the 
 spine as a double layer, forming a mesonephron, which permits of movement taking place. The 
 kidney may also be misplaced as an acquired condition; in these cases the kidney is mobile in 
 the tissues by which it is surrounded, either moving in or moving with its fatty capsule. This 
 condition is known as movable kidney (nephroptosis), and is more common in the female than 
 in the male, and on the right than the left side. If a displaced kidney becomes fixed in an 
 abnormal position, it is said to be dislocated. Movable kidney cannot be distinguished from 
 floating kidney until the kidney is exposed by incision. Other malformations are the persist- 
 ence of the foetal lobulation; the presence of two pelves or two ureters to the one kidney. In 
 some rare instances a third kidney may be present. 
 
 The kidney is embedded in a large quantity of loose fatty tissue, and is but partially covered 
 by peritoneum; hence, rupture of this organ is not nearly so serious an accident as rupture of 
 the liver or spleen, since the extravasation of blood and urine which follows is, in the majority 
 of cases, outside the peritoneal cavity. Occasionally the kidney may be bruised by blows in the 
 loin or by being compressed between the lower ribs and the ilium when the body is violently 
 bent forward. This is followed by a little transient hwmatvria, which, however, speedily passes 
 off. Occasionally, when rupture involves the pelvis of the kidney or the commencement of the 
 ureter, this duct may become blocked, and hydronephrosis follows. 
 
 The loose cellular tissue around the kidney may be the seat of suppuration, constituting 
 perinephritic abscess. This may be due to injury, to disease of the kidney itself, or to 'extension 
 of inflammation from neighboring parts. The abscess may burst into the pleura, causing 
 empyema; into the colon or bladder; or may point externally in the groin or loin. Tumors of the 
 kidney, of which, perhaps, sarcoma in children is the most common, may be recognized by their 
 position and fixity; by the resonant colon lying in front of it; by their not moving with respira- 
 tion; and by their rounded outline, not presenting a notched anterior margin like the spleen, with 
 which they are most likely to be confounded. The examination of the kidney should be bimanual ; 
 that is to say, one hand' should be placed in the flank and firm pressure made forward, v.hib 
 
 90 
 
1426 THE URINARY ORGANS 
 
 the other hand is buried in the abdominal wall, over the situation of the organ. Manipulation 
 of the kidney frequently produces a peculiar sickening sensation and some faintness. 
 
 The kidney has, of late years, been frequently attacked surgically. It may be exposed and 
 opened for exploration or the evacuation of pus {nephrotomy); it may be incised for the removal 
 of stone (nephro-lithotomy); it may be sutured when wounded (nephrorrhaphy); it may be fixed 
 in place by sutures (nephropexy) or gauze pads when movable or floating; or it may be removed 
 (nephrectomy). 
 
 The kidney may be exposed either by a lumbar or abdominal incision. The operation is 
 best performed by a lumbar incision, except in a case of very large tumor or of wandering kid- 
 ney with a loose mesonephron, on account of the advantages which it possesses of not opening 
 the peritoneum and of affording admirable drainage. It may be performed either by an oblique 
 a vertical, or a transverse incision. A common incision for exposing the kidney begins an inch 
 below the twelfth rib at the margin of the Erector spinae muscle and passes obliquely down- 
 ward and forward, exposing the anterior border of the Latissimus dorsi and the posterior border 
 of the Internal oblique. The surgeon divides the posterior leaflet of the lumbar fascia, draws aside 
 or incises the Quadratus lumbonim, and cuts the anterior leaflet of the lumbar fascia and also the 
 transversalis fascia. He opens the fatty capsule down to the kidney and strips it from the true 
 capsule, bringing the kidney outside of the body for inspection. The vertical incision at the 
 edge of the Erector spinae muscle is frequently used. A gridiron or muscle-splitting operation 
 is used by some in order to avoid the division of nerves, vessels, and muscular fibre. 
 
 The abdominal operation is best performed by an incision in the linea semilunaris on the 
 side of the kidney to be removed, as recommended by Langenbuch; the kidney is then reached 
 from the outer side of the colon, ascending or descending, as the case may be, and the vessels 
 of the colon are not interfered with. If the incision were made in the linea alba, the kidney 
 would be reached from the inner side of the colon, and the vessels running to supply the colon 
 would necessarily be interfered with. The incision is made of varying length according to the 
 size of the kidney, and commences just below the costal arch. The abdominal cavity is opened. 
 The intestines are held aside, and the outer layer of the mesocolon incised, sO that the fingers 
 can be introduced behind the peritoneum and the renal vessels are sought for. These vessels 
 are then to be ligatured: if tied separately, care must be taken to ligature the artery first. The 
 kidney must now be enucleated, and the vessels and the ureter divided, and the latter disinfected 
 and tied, and, if it is thought necessary, stitched to the edge of the wound. 
 
 THE URETER (Figs. 1004, 1005, 1006, 1011, 1028, 1029). 
 
 The ureters are the two tubes which conduct the urine from the kidneys into 
 the bladder. The ureter commences within the sinus of the kidney by a number 
 of short truncated branches, the calices or infundibula, which unite either directly 
 or indirectly to form a dilated pouch, the pelvis (Fig. 1010), from which the ureter, 
 after passing through the hilum of the kidney, descends to the bladder. The calices 
 are cup-like tubes encircling the apices of the Malpighian pyramids ; but inasmuch 
 as one calyx may include two or even more papillae, their number is generally 
 less than the pyramids themselves. The calices vary in number from eight to 
 eighteen. These calices converge into two or three tubular divisions which by 
 their junction form the pelvis or dilated portion of the ureter. The portion last 
 mentioned, where the pelvis merges into the ureter proper, is found opposite 
 the spinous process of the first lumbar vertebra, in which situation it is accessible 
 behind the peritoneum (Fig. 1006). 
 
 The Ureter Proper. — The ureter proper is a cylindrical membranous tube, 
 about sixteen inches in length and of the diameter of a goosequill, extending from 
 the pelvis of the kidney to the bladder. Its course is obliquely downward and 
 inward through the lumbar region (pars abdominalis) (Fig. 1029), into the cavity of 
 the pelvis (pars pe/yma) (Fig. 1029), where it passes downward, forward, and inward 
 across that cavity to the base of the bladder, into which it then opens by a con- 
 stricted orifice (orificium ureteris) (Fig. 1045), after having passed obliquely for 
 nearly an inch between its muscular and mucous coats (Fig. 1028) . The lower 
 part of the abdominal portion of the ureter exhibits a spindle-shaped dilatation. 
 
 Relations (Fig. 1029). — In its course it rests upon the Psoas muscle, being 
 covered by the peritoneum, and crossed obliquely, from within outward, by the 
 
THE URETER 
 
 1427 
 
 spermatic vessels ; the right ureter is crossed by the branches of the mesenteric 
 arteries, which are distributed to the ascending colon, and the left ureter by those 
 for the descending colon; the right ureter lying close to the outer side of the infe- 
 rior vena cava. Opposite the first piece of the sacrum it crosses either the common 
 or external iliac artery and vein, lying behind the 
 ileum on the ricjht side and behind the sigmoid 
 flexure of the colon on the le]t side. In the pelvis 
 it enters the posterior false ligament of the bladder, 
 below the obliterated hypogastric artery, the vas 
 deferens in the male passing between it and the 
 bladder. In the female the ureter is to the inner 
 side of the uterine artery at the wall of the pelvis, 
 it passes forward and inward below the posterior 
 layer of the broad ligament running through the 
 parametrium, passing along the side of the neck 
 of the uterus and upper part of the vagina, 
 being in contact with the anterior and lateral 
 vaginal walls and being crossed anteriorly by 
 the uterine artery (Fig. 1099). At the base of the 
 
 bladder the ureter is situated about two inches from its fellow: lying, in the male, 
 about an inch and a half from the vesical orifice of the urethra, at one of the 
 posterior angles of the trigone (Fig. 1045). 
 
 Structure. — The ureter is composed of three coats — fibrous, muscular, and 
 
 Fig. 1028. — Diagram showing method 
 of entrance of the ureter into the blad- 
 der. (F. H. Gerrish.) 
 
 mucous. 
 
 RIGHT URETER PSOAS MUSCLE 
 
 LEFT URETER 
 
 ASCENDING 
 COLON 
 
 APPENDIX (drawn 
 up under) 
 
 SUPERIOR 
 
 HEMORRHOIDAL 
 
 ARTERY 
 
 
 U^ 
 
 ARTERY TO 
 
 SIGMOID 
 
 FLEXURE 
 
 Fig. 1029. — The relations of the pelvic mesocolon with the wall, the iliac sigmoid and superior hemorrhoidal 
 arteries and the ureter. (Poirier and Charpy.) 
 
 The Fibrous Coat (tunica adventitia). — The fibrous coat is the same throughout 
 the entire length of the duct, being continuous at one end with the fibrous capsule 
 of the kidney at the floor of the sinus, while at the other it is lost in the fibrous 
 structure of the bladder. 
 
1428 
 
 THE UBINABY OBGANS 
 
 The Muscular Coat {tunica muscularis). — In the pelvis of the kidney the mus- 
 cular coat consists of two layers, longitudinal and circular: the longitudinal fibres 
 become lost upon the sides of the papillae at the extremities of the calices; the 
 circular fibres may be traced surrounding the medullary structure in the same 
 situation. In the ureter proper the muscular fibres are very distinct, and are 
 arranged in three layers — an external longitudinal {stratum externum), a middle 
 circular {stratum medium), and an internal layer {stratum internum), less distinct 
 than the other two, but having a general longitudinal direction. According to 
 Kolliker, this internal layer is only found in the neighborhood of the bladder. 
 
 The Mucous Coat {tunica mucosa). — The mucous coat is smooth, and presents a 
 few longitudinal folds which become effaced by distention. It is continuous with 
 the mucous membrane of the bladder below,whilst it is prolonged over the papillae 
 of the kidney above. Its epithelium is of a peculiar character, and resembles that 
 found in the bladder. It is known by the name of transitional epithelium. It con- 
 sists of several layers of cells, of which the innermost — that is to say, the cells in 
 contact with the urine — are quadrilateral in shape, with concave margins on their 
 outer surface, into which fit the rounded ends of the cells of the second layer. 
 These, the intermediate cells, more or less resemble columnar epithelium, and are 
 pear-shaped, with a rounded internal extremity which fits into the concavity of 
 the cells of the first layer, and a narrow external extremity which is wedged in 
 between the cells of the third layer. The external or third layer consists of conical 
 or oval cells varying in number in different parts, and presenting processes which 
 extend down into the basement-membrane. 
 
 Vessels and Nerves. — The arteries supplying the ureter are branches from the 
 renal, spermatic, internal iliac, and inferior vesical. 
 
 The nerves are derived from the inferior mesenteric, spermatic, and pelvic plexuses. 
 
 Surgical Anatomy. — Subcutaneous rupture of the ureter is not a common accident, but occa- 
 sionally occurs from a sharp, direct blow on the abdomen, as from the kick of a horse. The ureter 
 may be either torn completely across, or only partially divided, and, as a rule, the peritoneum 
 escapes injury. If torn completely across the urine collects in the retroperitoneal tissues; if it 
 is not completely divided, the lumen of the tube may become obstructed and hydro-nephrosis or 
 pyo-nephrosis results. The ureter may be accidentally xvounded in some abdominal operations; 
 if this should happen, the divided ends must be sutured together, or, failing to accomplish this, 
 the upper end must be implanted into the bladder or the intestine. 
 
 THE SUPRARENAL CAPSULE OR GLAND (6LANDULA 
 SUPRARENALIS) (Figs. 1010, 1030, 1031). 
 
 The suprarenal capsules belong to the class of ductless glands. They are two 
 small flattened bodies, of a yellowish color, situated at the back part of the abdo- 
 men, behind the peritoneum, and immediately above and in front of the upper 
 end of each kidney; hence their name. The right one (Fig. 1030) is somewhat 
 triangular in shape, bearing a resemblance to a cocked hat; the left (Fig. 1031) is 
 more semilunar, usually larger and placed at a higher level than the right. They 
 vary in size in different individuals, being sometimes so small as to be scarcely 
 detected; their usual size is from an inch and a quarter to nearly two inches in 
 length, rather less in width, and from two to three lines in thickness. Their 
 average weight is from one to one and a half drachms each. 
 
 Relations. — The relations of the suprarenal capsules differ on the two sides of 
 the body. 
 
 The Right Suprarenal (Fig. 1030). — The right suprarenal is roughly triangular in 
 shape, its angles pointing upward, downward, and outward. It presents two sur- 
 faces for examination, an anterior and a posterior. The anterior surface {fades 
 
THE SUPRARENAL CAPSULE OR GLAND 
 
 1429 
 
 anterior) presents two areas, separated by a furrow, the hilum {hilus glandulae 
 suprarenalis) : one area occupying about one-third of the whole surface, is situ- 
 ated above and internally; it is depressed, uncovered by peritoneum, and is in 
 contact in front with the posterior surface of the right lobe of the liver, and along 
 its inner border with the inferior vena cava; the remaining area is elevated, and 
 is divided into a non-peritoneal portion, in contact with the hepatic flexure of 
 the duodenum, and a portion covered by peritoneum forming the hepato-renal 
 fold. The posterior siirface (fades posterior) is slightly convex, and rests upon 
 the Diaphragm. The base (basis glandulae suprarenalis) is concave, and is in 
 contact with the upper end and the adjacent part of the anterior surface of the 
 kidney. 
 
 The Left Suprarenal (Fig. 1031). — The left suprarenal is crescentic in shape, its 
 concavity being adapted to the upper end of the left kidney. It presents an inner 
 
 ANTERIOR 
 SURFACE 
 
 SUPRARENAL 
 VEIN 
 
 SUPRARENAL 
 
 VEIN 
 
 SUPRARENAL 
 ARTERY 
 
 SUPRARENAL 
 ARTERY 
 
 Fig. 1030. — The right suprarenal gland. 
 (Spalteholz.) 
 
 Fig. 1031. — The left suprarenal gland. 
 (Spalteholz.) 
 
 border which is convex, and an outer which is concave ; its upper border is narrow, 
 and its lower rounded. Its anterior surface (fades anterior) presents two areas: an 
 upper one, covered by the peritoneum forming the lesser sac, which separates it 
 from the cardiac end of the stomach and to a small extent from the superior 
 extremity of the spleen; and a lower one, which is in contact with the pancreas 
 and splenic artery, and is therefore not covered by the peritoneum. A hilum is 
 present, as in the right suprarenal. Its posterior surface (fades posterior) presents 
 a vertical ridge, which divides it into two areas. The ridge lies in the sulcus 
 between the kidney and crus of the Diaphragm, while the area on either side of 
 it lies on these parts respectively; the outer area, which is thin, resting on the 
 kidney, and the inner and smaller area resting on the left crus of the Diaphragm. 
 The surface of the suprarenal gland is surrounded by areolar tissue containing 
 much fat, and closely invested by a thin fibrous coat, which is difficult to remove, 
 on account of numerous fibrous processes and vessels which enter the organ 
 through the furrows on its anterior surface and base. 
 
 Accessory Suprarenal Glands (glandulae suprarenales accessoriae). — Small 
 accessory suprarenals are often to be found in the connective tissue around the 
 suprarenals. The smaller of these, on section, show a uniform surface, but in 
 some of the larger a distinct medulla can be made out. 
 
 Structure (Figs. 1032, 1033, and 1034). — On making a perpendicular section 
 (Fig. 1032) , the suprarenal gland is seen to consist of two substances — external or 
 cortical and internal or medullary. The former, which constitutes the chief part of 
 the organ, is of a deep-yellow color. The medullary substance is soft, pulpy, 
 
1430 
 
 THE URINARY ORGANS 
 
 and of a dark-brown or black color, whence the name atxabiliary capsules formerly 
 given to these organs. In the centre is often seen a space, not natural, but 
 formed by breaking down after death of the medullary substance. 
 
 The Cortical Portion (substantia corticalis) (Fig. 1032). — The cortical substance 
 consists chiefly of narrow columnar masses placed perpendicularly to the surface. 
 This arrangement is due to the disposition of the capsule, which sends into the 
 interior of the gland processes passing in vertically and communicating with each 
 other by transverse bands so as to form spaces 
 which open into each other. These spaces are mM 
 
 of slight depth near the surface of the organ, ililliififli 
 
 so that there the section somewhat resembles a 
 net; this is termed the zona glomenilosa ; but 
 they become much deeper or longer farther in, 
 so as to resemble pipes or tubes placed endwise, 
 
 ^^Capsule. 
 
 Zona 
 glomerulosa. 
 
 Zona 
 fasdculata. 
 
 Connective 
 tissue. 
 
 Gland 
 llT cylinders. 
 
 Fig. 1033. — Minute structure of suprarenal 
 capsule. 
 
 FrameworTc. 
 
 
 Zona reticularis. 
 
 Medulla. 
 
 / --Nuclei. 
 
 Capillary. 
 
 Fig. 1032.- 
 
 - Vertical section of the suprarenal capsule. 
 Elberth, in Strieker's Manual.) 
 
 (From 
 
 Fig. 1034. — Minute structure of suprarenal 
 capsule. 
 
 the zona fasciculata. Still deeper down, near the medullary part, the spaces 
 become again of small extent; this is named the zona reticularis. These processes 
 or trabeculae, derived from the capsule and forming the framework of the spaces, 
 are composed of fibrous connective tissue with longitudinal bundles of unstriped 
 muscular fibres. Within the interior of the spaces are contained groups of poly- 
 hedral cells, which are finely granular in appearance, and contain a spherical 
 nucleus, and not infrequently fat-globules. These groups of cells do not entirely 
 fill the spaces in which they are contained, but between them and the trabeculae 
 of the framework is a channel which is believed to be a lymph-path or sinus, 
 and which communicates with certain passages between the cells composing the 
 
THE CAVITY OF THE PELVIS 1431 
 
 group. The lymph-path is supposed to open into a plexus of efferent lymphatic 
 vessels which are contained in the capsule. 
 
 The Medullary Portion (substantia medullaris) (Fig. 1032). — In the medullary 
 portion the fibrous stroma seems to be collected together into a much closer 
 arrangement, and forms bundles of connective tissue which are loosely applied 
 to the large plexus of veins of which this part of the organ mainly consists. In 
 the interstices lie a number of cells compared by Frey to those of columnar epithe- 
 lium. They are coarsely granular, do not contain any fat-molecules, and some 
 of them are branched. Luschka has affirmed that these branches are connected 
 with the nerve-fibres of a very intricate plexus which is found in the medulla; this 
 statement has not been verified by other observers, for the tissue of the medullary 
 substance is less easy to make out than tliat of the cortical, owing to its rapid 
 decomposition. 
 
 Vessels and Nerves. — The numerous arteries which enter the suprarenal bodies 
 from the sources mentioned below penetrate the cortical part of the gland, where 
 they break up into capillaries in the fibrous septa, and these converge to the very 
 numerous veins of the medullary portion, which are collected together into the 
 suprarenal vein, which usually emerge as a single vessel from the centre of the 
 gland. 
 
 The arteries supplying the suprarenal capsules are three in number and of large 
 size; they are derived from the aorta, the phrenic, and the renal; they subdivide 
 into numerous minute branches previous to entering the substance of the gland. 
 
 The suprarenal vein returns the blood from the medullary venous plexus, and 
 receives several branches from the cortical substance ; it emerges from the hilum 
 and opens on the right side into the inferior vena cava, on the left side into the 
 renal vein. 
 
 The lymphatics form several collections which are about the beginning of the 
 suprarenal vein. They terminate in the glands to the correspojiding side of the 
 aorta. 
 
 The nerves are exceedingly numerous, and are derived from the solar and 
 renal plexuses, and, according to Bergmann, from the phrenic and pneumo gastric 
 nerves. They enter the lower and inner part of the capsule, traverse the cortex, 
 and terminate about the cells of the medulla. They have numerous small ganglia 
 developed upon them, from which circumstance the organ has been conjectured 
 to have some function in connection with the sympathetic nervous system. 
 
 THE CAVITY OF THE PELVIS. 
 
 The cavity of the pelvis is that part of the general abdominal cavity which is 
 below the level of the ilio-pectineal lines and the promontory of the sacrum. 
 
 Boundaries. — It is bounded behind by the sacrum, the coccyx, the Pyriformis 
 muscles, and the great sacro-sciatic ligaments; in front and at the sides by the 
 portions of the innominate bones below the ilio-pectineal lines. In front and 
 to the sides the bony sides of the pelvic cavity are partly covered by the internal 
 Obturator muscles, and internal to these muscles by the parietal part of the 
 pelvic fascia. Above, it communicates with the cavity of the abdomen; and 
 below, the outlet is closed by the triangular ligament, the Levatores ani and 
 Coccygei muscles, and the visceral layer of the pelvic fascia, which is reflected 
 from the wall of the pelvis on to the viscera. 
 
 Contents. — The viscera contained in this cavity are — the urinary bladder, the 
 rectum, and some of the generative organs peculiar to each sex, and some convo- 
 lutions of the small intestines. The pelvic viscera are partially covered by the 
 peritoneum, and supplied with blood-vessels, lymphatics, and nerves. 
 
1432 
 
 THE URINARY ORGANS 
 
 THE URINARY BLADDER (VESICA URINARIA) (Figs. 1037, 1038, 1054, 1055). 
 
 The urinary bladder is the reservoir for the urine. It is a musculo-membranous 
 sac situated in the pelvis, behind the pubes, and in front of the rectum in the male, 
 the cervix uteri and vagina intervening between it and that intestine in the female. 
 The shape, position, and relations of the bladder are greatly influenced by age. 
 
 Fig. 1035. — The empty bladder. (Poirier and Charpy.) 
 
 Fig. 1036. — Modifications of form of the blad- 
 der during distention (Poirier and Charpy.) 
 
 '■!s ' ' [JlJ^pace of 
 
 ^Suspensory 
 ligament 
 
 \\ 
 
 Fossa navicularis.' 
 Fig. 1037. — Vertical section of bladder, penis, and urethra. 
 
 sex, and the degree of distention of the organ. During infancy it is conical in 
 shape, and projects above the symphysis pubis into the hypogastric region. In the 
 adult, when quite empty and contracted (Figs. 1035 and 1036), it is cup-shaped, 
 and on vertical median section its cavity, with the adjacent portion of the urethra, 
 presents a Y-shaped cleft, the stem of the Y corresponding to the urethra. It is 
 
THE URINARY BLADDER 
 
 1433 
 
 placed deeply in the pelvis, flattened from before backward, and reaches as high as 
 the upper border of the symphysis pubis. When slightly distended, it has a rounded 
 form, and is still contained within the pelvic cavity (Fig. 1036), and when greatly 
 distended (Figs. 1036 and 1037), it is ovoid in shape, rising into the abdominal 
 cavity, and often extending nearly as high as the umbilicus. It is larger in its verti- 
 cal diameter than from side to side, and its long axis is directed from above 
 obliquely downward and backward, in a line directed from some point between 
 the symphysis pubis and umbilicus (according to its distention) to the end of the 
 coccyx. The bladder, when distended, is slightly curved forward toward the 
 
 Peritoneur], 
 
 Vesicula seminalis. 
 Symphysis pubis. 
 
 Dorsal vein of penis 
 
 Septum pectiniforme.'-'' "y/^. 
 Urethra. "'' 
 
 Jtecto-vesicai 
 \y/pouch. 
 
 Prostate 
 gland. 
 
 Sphincter ani. 
 
 Fig. 1038. — Vertical median section of the male pelvis. (Henle.) 
 
 anterior wall of the abdomen, so as to be more convex behind than in front. In 
 the fem.ale it is larger in the transverse than in the vertical diameter, and its 
 capacity is said to be greater than in the male.^ When moderately distended, it 
 measures about five inches in length, and three inches across, and the ordinary 
 amount which it can contain without serious discomfort is about a pint. 
 
 The bladder is divided for purposes of description into a superior, an antero- 
 inferior, and two lateral surfaces, a base or fundus, and a summit or apex. 
 
 Surfaces. The Superior or Abdominal Surface (Figs. 852, 1037, 1038, and 1055). 
 — The superior or abdominal surface is entirely free, and is covered throughout by 
 
 1 According to Henle, the bladder is considerably smaller in the female than in the male.- 
 English eciiticiii. 
 
 -En. of 15th 
 
1434 
 
 THE UBINARY ORGANS 
 
 peritoneum. It looks almost directly upward into the abdominal cavity, and extends 
 in an antero-posterior direction from the apex to the base of the bladder. It is in 
 relation with the small intestine and sometimes with the sigmoid flexure, and, in 
 the female, with the uterus. On each side, in the male, a portion of the vas 
 deferens is in contact with the hinder part of this surface, lying beneath the 
 peritoneum. 
 
 The Antero-inferior or Pubic Surface (Figs. 1037, 103S, and 1055). — The antero- 
 inferior or pubic surface looks downward and forward. In the undistended 
 condition it is uncovered by peritoneum, and is in relation with the Obturator 
 internus muscle on each side, with the recto-vesical fascia, and anterior true 
 ligaments of the bladder. It is separated from the body of the pubis by a tri- 
 angular interval, the space of Retzius, occupied by fatty tissue. As the bladder 
 
 Vermiform appendix. 
 
 External iliac 
 artery. 
 
 Anterior crural 
 nerve. 
 
 External oblique 
 muscle. 
 
 Profunda vessels, levator ani. Corpora Urethra. 
 
 cavernosa. 
 Fig. 1039. — Frontal section of the lower part of the abdomen. Viewed from in front. (Braune.) 
 
 ascends into the abdominal cavity during distention the distance between its apex 
 and the umbilicus is necessarily diminished, and the urachus (Fig. 852 and 1055) 
 is thus relaxed; so that, instead of passing directly upward to the umbilicus, it 
 descends first on the upper part of the anterior surface of the bladder, and then, 
 curving upward, ascends on the back of the abdominal wall. The peritoneum, 
 which follows the urachus, thus comes to form a pouch (plica vesicalis transversa) 
 of varying depth betv/een the anterior surface of the viscus and the abdominal 
 wall (Fig. 1038). The fold passes to the neighborhood of the internal abdom- 
 inal rings. Thus, when the bladder is distended, the upper part of its anterior 
 surface is in relation with the urachus and is covered by peritoneum. The lower 
 part of its anterior surface, a distance of about two inches above the symphysis 
 pubis, is devoid of peritoneum, and is in contact with the abdominal wall. 
 
THE URINARY BLADDER 1435 
 
 The Lateral Surfaces. — The lateral surfaces are covered behind and above by 
 peritoneum, which extends as low as the level of the obliterated hypogastric 
 artery; below and in front of this, these surfaces are uncovered by peritoneum, 
 and are separated from the Levatores ani muscles and walls of the pelvis by a 
 quantity of loose areolar tissue containing fat. In front this surface is connected 
 to the recto-vesical fascia by a broad expansion on either side, the lateral true 
 ligaments. The vas deferens crosses the hinder part of the lateral surface obliquely, 
 and passes between the ureter and the bladder. When the bladder is empty the 
 peritoneum descends on the pelvic wall as low as the lateral border of the bladder 
 and enters a groove known as the paravesical fossa. The lateral surfaces, the 
 pubic surface, and the abdominal surface together constitute the body of the 
 bladder (corpus vesicae). 
 
 The Fundus or Base (fundus vesicae) (Figs. 1038, 1052, and 1055). — The fundus 
 or base is directed downward and backward, and is partly covered by peritoneum 
 and is in part not covered by it. In the male the upper portion, to within about 
 an inch and a half of the prostate, is covered by the recto-vesical pouch of peri- 
 toneum (Fig. 855) . The lower part is in direct contact with the anterior wall of 
 the second part of the rectum and the vesiculae seminales and vasa deferentia 
 (Figs. 1052 and 1054). The ureters enter the bladder at the upper part of its 
 base, about an inch and a half above the base of the prostate gland (Fig. 1045). 
 The portion of the bladder in relation with the rectum corresponds to a trian- 
 gular space, bounded, below, by the prostate gland; above, by the recto-vesical 
 fold of the peritoneum; and on each side, by the vesicula seminalis and vas 
 deferens. It is separated from direct contact with the rectum by the recto- 
 vesical fascia. When the bladder is very full, the peritoneal fold is raised with 
 it, and the distance between its reflection and the anus is about four inches; but 
 this distance is much diminished when the bladder is empty and contracted. In 
 the female, the base of the bladder is connected to the anterior aspect of the cervix 
 uteri by areolar tissue, and is adherent to the anterior wall of the vagina (Fig. 
 853) . Its upper surface is separated from the anterior surface of the body of 
 the uterus by the utero-vesical pouch of the peritoneum (Fig. 853) . 
 
 The so-called neck or cervix of the bladder (collum vesicae) is the point of com- 
 mencement of the urethra; there is, however, no tapering part, which would 
 constitute a true neck, but the bladder suddenly contracts to the opening of the 
 urethra (Fig. 1038). In the male it is surrounded by the prostate gland and its 
 direction is oblique when the individual is in the erect posture (Figs. 1037 and 
 1038). In the female its direction is obliquely downward and forward. 
 
 The Summit or Apex (vertex vesicae). — The summit or apex is the portion 
 of the bladder which when that organ is empty or nearly empty is nearest to 
 the upper border of the symphysis. It is directed upward and forward. In a 
 distended bladder the apex is well above the pubes in the abdominal cavity. 
 
 The Urachus or Middle Umbilical Ligament (ligamentum umbilicale medium) 
 (Fig. 1055). — The urachus is a connective-tissue cord and is the obliterated 
 remains of the tubular canal of the allantois, which existed in the embryo, and 
 a portion of which expanded to form the bladder. It passes upward, from the 
 apex of the bladder, between the trans versalis fascia and peritoneum, to the 
 umbilicus, becoming thinner as it ascends. It is composed of fibrous tissue, 
 mixed with plain muscular fibres. The urachus causes the formation of a peri- 
 toneal fold, the plica umbilicalis media (Fig. 852). On each side of it is placed a 
 fibrous cord, the obliterated portion of the hypogastric artery, which, passing 
 upward from the side of the bladder, approaches the urachus above its summit. 
 Over each cord is the fold known as the plica umbilicalis lateralis (Fig. 852). In 
 the infant, at birth, the urachus is occasionally found pervious, so that the urine 
 escapes at the umbilicus, and calculi have been found in its canal. 
 
1436 
 
 THE URINARY ORGANS 
 
 Ligaments. — The bladder is retained in its place by ligaments, which are divided 
 into true and false. The true ligaments are five in number: two anterior, two 
 lateral, and the urachus. The false ligaments, also five in number, are formed by- 
 folds of the peritoneum. 
 
 The two anterior true ligaments, the pubo-prostatic or pubo-vesical ligaments {liga- 
 menta puboprostatica) extend from the back of the ossa pubis, one on each side of 
 the symphysis, to the front of the neck of the bladder, over the anterior surface of 
 the prostate gland. These ligaments are formed by the recto-vesical fascia, and 
 contain a few muscular fibres prolonged from the bladder. 
 
 The two lateral true ligaments, formed by expansions from the fascia lining the 
 lateral wall of the pelvis, are broader and thinner than the preceding. They 
 are attached to the lateral parts of the prostate gland and to the sides of the base of 
 the bladder. 
 
 Fig. 1040.— Fibres of the exteral 
 longitudinal layer. (Poirier and 
 Charpy.) 
 
 Fig. 1041. — Fibres of the middle 
 or circular layer. (Poirer and 
 Charpy.) 
 
 Fig. 1042.— Fibres of the inter- 
 nal longitudinal layer. (Poirier 
 and Charpy.) 
 
 The urachus or middle umbilical ligament is the fibro-muscular cord already men- 
 tioned, extending between the summit of the bladder and the umbilicus. It is broad 
 below, at its attachment to the bladder, and becomes narrower as it ascends. 
 
 The two posterior false ligaments pass forward, in the male, from the sides of 
 the rectum (plicae rectovesicales) ; in the female, from the sides of the uterus (plicae 
 rectouterinae) , to the posterior and lateral aspect of the bladder; they form in 
 the male the lateral boundaries of the recto-vesical pouch (excavatio rectovesicalis) 
 (Figs. 926 and 1038) ; they form in the female the lateral boundaries of the pouch or 
 cul-de-sac of Douglas (excavatio rectouterina [Douglasi]) (Figs. 853 and 927). The 
 posterior false ligaments contain the obliterated hypogastric arteries and the 
 ureters, together with vessels and nerves. In the base of each fold is smooth 
 muscle-fibre, the Recto-vesical muscle (m. rectovesicalis). 
 
 The two lateral false ligaments are reflections of the peritoneum, from the 
 iliac fossae and lateral walls of the pelvis to the sides of the bladder. Each 
 lateral false ligament (ligamentum umhilicale laterale) passes in front into the plica 
 umbilicalis lateralis over the corresponding hypogastric artery. The two lateral 
 reflections of peritoneum are continuous in front of the apex vesicae, at which 
 point the peritoneum passes upon the urachus. 
 
 The superior or anterior false ligament or the suspensory ligament (plica umhilicalis 
 media) is the prominent fold of peritoneum extending from the summit of the blad- 
 der to the umbilicus. It is carried off from the bladder by the urachus and the 
 
THE URINARY BLADDER I437 
 
 obliterated hypogastric arteries. The peritoneal fold over each obliterated hypo- 
 gastric artery is called the plica mnbilicalis lateralis (Fig. 852), and is the pro- 
 longation forward of the ligamentum umbilicale laterale. Besides the true and 
 false ligaments, the bladder receives support from the fibrous tissue and unstriated 
 muscle about the seminal vesicles, and terminations of the ureters and vasa defer- 
 entia. In the female the connection with the anterior vaginal wall supports the 
 base of the bladder. In both sexes the most solidly fixed part of the bladder is 
 about the orifice of the urethra. 
 
 Structure. — The bladder is composed of four coats — serous, muscular, sub- 
 mucous, and mucous. 
 
 The Serous Coat {tunica serosa). — The serous coat is partial, and derived from the 
 peritoneum. It invests the superior surface and the upper part of the lateral surfaces 
 and base, and is reflected from these parts on to the abdominal and pelvic walls. 
 
 The Muscular Coat {tunica muscularis) (Figs. 1040, 1041, and 1042). — The mus- 
 cular coat consists of three layers of unstriped muscular fibre: an external layer, 
 composed of fibres having for the most part a longitudinal arrangement; a middle 
 layer, in which the fibres are arranged, more or less, in a circular manner; and an 
 internal layer, in which the fibres have a general longitudinal arrangement. 
 
 The fibres of the external longitudinal layer {stratum externum) arise from the 
 posterior surface of the body of the os pubis in both sexes (m. pubovesicalis) , and 
 in the male aris? also from the adjacent part of the prostate gland and its capsule. 
 They pass, in a more or less longitudinal manner, up the anterior surface of the 
 bladder, over its apex, and then descend along its posterior surface to its base, 
 where they become attached to the prostate in the male and to the front of the vagina 
 in the female. At the sides of the bladder the fibres are arranged obliquely and 
 intersect one another. The external lorgitudinal layer has been named the 
 Detrusor urinae muscle. 
 
 The middle circular layers {stratum medium) are very thinly and irregularly 
 scattered on the body of the organ, and, though to some extent placed transversely 
 to the long axis of the bladder, are for the most part arranged obliquely. Toward 
 the lower part of the bladder, f round the neck and the commencement of the 
 urethra, they are disposed in a thick circular layer, forming the sphincter vesicae, 
 which is continuous with the muscular fibres of the prostate gland. 
 
 The internal longitudinal layer {stratum internum) is thin, and its fasciculi have 
 a reticular arrangement, but with a tendency to assume for the most part a longi- 
 tudinal direction. Two bands of oblique fibres, originating behind the orifices of 
 the ureters, converge to the back part of the prostate gland, and are inserted, by 
 means of a fibrous process, into the middle lobe of that organ. They are the 
 muscles of the ureters, described by Sir C. Bell, who supposed that during the con- 
 traction of the bladder they served to retain the oblique direction of the ureters, 
 and so prevent the reflux of the urine into them. 
 
 The Submucous Coat {tela suhmucosa). — The submiucous coat consists of a layer 
 of areolar tissue connecting together the muscular and mucous coats, and inti- 
 mately united to the latter. 
 
 The Mucous Coat {tunica mucosa). — The mucous coat is thin, smooth, and of a 
 pale rose color. It is continuous above through the ureters with the lining mem- 
 brane of the uriniferous tubes, and below with that of the urethra. Except at the 
 trigone, it is connected very loosely to the muscular coat by a layer of areolar tissue, 
 and is therefore thrown into folds or rugae when the bladder is empty (Fig. 
 1046). The mucous membrane over the trigone never presents rugae. The 
 epithelium covering it is of the transitional variety, consisting of a superficial 
 layer of polyhedral flattened cells, each with one, two, or three nuclei (Fig. 1043) ; 
 beneath these is a stratum of large club-shaped cells with the narrow extremity of 
 each cell directed downward and wedged in between smaller spindle-shaped cells, 
 
1438 
 
 THE UBINABY 0BGAN8 
 
 each an oval nucleus (Fig. 1044). There are no true glands in the mucous mem- 
 brane of the bladder, though certain mucous follicles which exist, especially near 
 the neck of the bladder, have been regarded as such. 
 
 Objects Seen on the Inner Surface. — Upon the inner surface of the bladder are 
 seen the mucous membrane, orifices of the ureters, the trigone, and the commencement 
 of the urethra. 
 
 Fig. 1043.— Superficial layer of the epithelium of 
 the bladder. Composed of polyhedral cells of vari- 
 ous sizes, each with one, two, or three nuclei. (Klein 
 and Noble Smith.) 
 
 Fig. 1044. — Deep layers of epithelium of bladder, 
 showing large club-shaped cells above, and smaller, 
 more spindle-shaped cells below, each with an oval 
 nucleus. (Klein and Noble Smith.) 
 
 The Mucous Membrane. — The mucous membrane of the empty bladder is thrown 
 into folds or rugae, except over the trigone, where it is firmly adherent to the 
 muscular coat and is smooth (Figs. 1045 and 1046). The folds disappear when 
 the bladder is distended. 
 
 The Orifices of the Ureters (Figs. 1045 and 1046) . — These are situated at the base 
 of the trigone, being distant from each other about two inches when the bladder is 
 
 RIDQC FORMtD BY 
 I— INTERURETERAL 
 MUSCLE 
 
 Fig. 1045. — The interior of the bladder, showing the vesical trigone. (Poirier and Charpy.) 
 
 moderately distended. Each orifice is about an inch and a half from the base of the 
 prostate and the commencement of the urethra in the moderately distended bladder. 
 The Vesical Trigone or the Trigonum Vesicae (Fig. 1045) is a triangular smooth 
 surface, with the apex directed forward, situated at the base of the bladder, imme- 
 diately behind the urethral orifice. It is paler in color than the rest of the 
 
THE UBINABY BLADDER 
 
 1439 
 
 interior, and never presents any rugae, even in the collapsed condition of the 
 organ, owing to the intimate adhesion of its mucous membrane to the subjacent 
 tissue. It is bounded at each posterior angle by the orifice of a ureter, and in 
 front by the orifice of the urethra. Projecting from the lower and anterior part of 
 the bladder, and reaching to the orifice of the urethra, is a slight elevation of 
 mucous membrane, particularly prominent in old persons, called the uvula vesicae. 
 It is formed by a thickening of the submucous tissue. 
 
 Stretching from one ureteral opening to the other is a smooth, slightly curved 
 ridge, the convexity of which is toward the urethra. It is produced by transverse 
 muscle-fibres beneath the mucous membrane. The outer prolongations of this 
 ridge beyond the ureteral orifices are called the ureteral folds {'plicae uretericae). 
 They are created by the ureters as they traverse the bladder wall. About the 
 ureteral orifice are slight radial folds of mucous membrane, which are continuous 
 with the longitudinal folds of the prostatic urethra. " In the empty bladder the 
 ureteral orifice and the openings of the two ureters lie at the angles of an approxi- 
 mately equilateral triangle, whose sides are about one inch in length. When the 
 bladder is distended the distance between the openings may be increased to one 
 and a half inches or more."^ 
 
 LONGITUDINAL 
 FIBRES 
 
 CIRCULAR 
 FIBRES 
 
 TRIGONE 
 
 TRANSVERSE 
 
 FIBRES OF 
 
 TRIGONE 
 
 LONGITUDINAL 
 
 FIBRES OF 
 
 TRIGONE 
 
 EJACULATORY 
 DUCT 
 
 Fia. 1046.— The internal surface of the bladder. (Poirier and Charpy), 
 
 The muscles of the ureters were referred to on p. 1437. 
 
 The internal urethral orifice {orificium urethrae internum) is sickle-shaped and 
 is surrounded by a circular prominence (annulus urethralis), which is most distinct 
 in the male. 
 
 Vessels and Nerves.— The arteries (Fig. 424) supplying the bladder are the 
 superior, middle, and inferior vesical in the male, with additional branches from 
 the uterine and vaginal in the female. They are all derived from the anterior 
 trunk of the internal iliac. The obturator and sciatic arteries also supply small 
 visceral branches to the bladder. The veins form a complicated plexus around the 
 neck, sides, and base of the bladder (Fig. 474). The veins communicate below 
 with the plexus about the prostate and terminate in the internal iliac vein. 
 
 The lymphatics form two plexuses, one in the muscular and another in the sub- 
 mucous coat. They accompany the blood-vessels. The mucous membrane of 
 the bladder contains no lymphatics whatever (Sappey). The must;ular tissue 
 contains a few lymphatics. The subperitoneal tissues contain the usual number. 
 
 1 Professor A. Francis Dixon, in Prof. D. J. Cunningham's Text-book of Anatomy. 
 
1440 THE URINARY ORGANS 
 
 The collecting trunks from the anterior surface terminate in the external iliac 
 glands. The trunks from the posterior surface terminate in the internal iliac 
 glands, the hypogastric glands and the glands in front of the sacral promontory. 
 
 The nerves are derived from the pelvic plexus of the sympathetic and from the 
 third and fourth sacral nerves ; the former supplying the upper part of the organ, 
 the latter its base and neck. According to F. Darwin, the sympathetic fibres have 
 ganglia connected with them, which send branches to the vessels and to the 
 muscular coat. 
 
 Surface Form. — The surface form of the bladder varies with its degree of distention and 
 under other circumstances. In the young child it is represented by a conical figure, the apex 
 of which, even when the viscus is empty, is situated in the hypogastric region, about an inch 
 above the level of the symphysis pubis. In the adult, when the bladder is empty, its apex does 
 not reach above the level of the upper border of the symphysis pubis, and the whole organ is 
 situated in the pelvis; the neck, in the male, corresponding to a line drawn horizontally backward 
 through the symphysis a little below its middle. As the bladder becomes distended, it gradually 
 rises out of the pelvis into the abdomen, and forms a swelling in the hypogastric region, which is 
 perceptible to the hand as well as to percussion. In extreme distention it reaches into the umbil- 
 ical region. Under these circumstances the lower part of its anterior surface, for a distance 
 of about two inches above the symphysis pubis, is closely applied to the abdominal wall, without 
 the intervention of peritoneum, so that it can be tapped by an opening in the middle line just 
 above the symphysis pubis, without any fear of wounding the serous membrane. When the 
 rectum is distended, the prostatic portion of the urethra is elongated and the bladder lifted out 
 of the pelvis and the peritoneum pushed upward. Advantage is taken of this by some surgeons 
 in performing the operation of suprapubic cystotomy. The rectum is distended by an India- 
 rubber bag, which is introduced into this cavity empty, and is then filled with ten or twelve ounces 
 of water. If now the bladder is injected with about half a pint of some antiseptic fluid, it will 
 appear above the pubes plainly perceptible to the sight and touch. The peritoneum will be 
 pushed out of the way, and an incision three inches long may be made in the linea alba, from 
 the symphysis pubis upward, without any great risk of wounding the peritoneum. Other sur- 
 geons object to the employment of this bag, as its use is not imattended with risk, and because 
 it causes pressure on the prostatic veins and hence produces congestion of the vessels over the 
 bladder and a good deal of venous hemorrhage. 
 
 When distended, the bladder can be felt in the male, from the rectum, behind the prostate, 
 and fluctuation can be perceived by a bimanual examination, one finger being introduced into the 
 rectum and the distended bladder being tapped on the front of the abdomen with the finger 
 of the other hand. This portion of the bladder — that is, the portion felt in the rectum by the 
 finger — is uncovered by peritoneum. 
 
 Surgical Anatomy. — A certain defect of development in which the bladder is implicated is 
 known under the name of extroversion of the bladder. In this condition the lower part of the 
 abdominal wall and the anterior wall of the bladder are wanting, so that the posterior surface 
 of the bladder presents on the abdominal surface, and is pushed forward by the pressure of the 
 viscera within the abdomen, forming a red, vascular protrusion, on which the openings of the 
 ureters are visible. The penis, except the glans, is rudimentary and is cleft on its dorsal sur- 
 face, exposing the floor of the urethra — a condition known as epispadias. The pelvic bones 
 are also arrested in development (see page 220). 
 
 The bladder may be ruptured by violence applied to the abdominal wall when the viscus is 
 distended without any injury to the bony pelvis, or it may be torn in case of fracture of the 
 pelvis. The rupture may be either intraperitoneal or extraperitoneal — that is, may implicate the 
 superior surface of the bladder in the former case, or one of the other surfaces in the latter. 
 Rupture of the antero-inferior surface alone is, however, very rare. Until recently intraperi- 
 toneal rupture was uniformly fatal, but now abdominal section and suturing the rent with Lem- 
 bert sutures often saves the patient. The sutures are inserted only through the peritoneal and 
 muscular coats in such a way as to bring the serous surfaces at the margins of the wound into 
 apposition, and one is also inserted just beyond each end of the wound. The bladder should be 
 tested as to whether it is water-tight before closing the external incision. 
 
 The muscular coat of the bladder undergoes hypertrophy in cases in which there is any per- 
 sistent obstruction to the flow of urine. Under these circumstances the bundles of which the 
 muscular coat consists become much increased in size, and, interlacing in all directions, give rise 
 to what is known as the fasciculated bladder. Between these bundles of muscular fibres the mucous 
 membrane may bulge out, forming sacculi, constituting the sacculated bladder, and in these 
 little pouches phosphatic concretions may collect, forming encysted calculi. The mucous mem- 
 brane is very loose and lax, except over the trigone, to allow of the distention of the viscus. 
 
 Various forms of tumors have been found springing from the wall of the bladder. The inno- 
 
THE MALE URETHRA 
 
 1441 
 
 cent tumors are the papilloma and the mucous polypus, arising from the mucous membrane; 
 the fibrous tumor, from the submucous tissue; and the myoma, originating in the muscular 
 tissue; and, very rarely, dermoid tumors, the exact origin of which it is difficult to explain. 
 Of the malignant tumors, epitheliomata are the most common, but sarcomata are occasionally 
 found in the bladders of children. 
 
 Puncture of the bladder is performed above the pubes without wounding the peritoneum. 
 Puncture by the rectum is not now performed, as a permanent fistula may be left from abscess 
 forming between the rectum and the bladder; or pelvic cellulitis maybe set up; moreover, it is 
 exceedingly inconvenient to keep a cannula in the rectum. In some cases in performing this 
 operation the recto-vesical pouch of peritoneum has been wounded, inducing fatal peritonitis. 
 The operation, therefore, has been abandoned. Suprapubic cystotomy is considered above under 
 the heading of Surface Form. This operation may be employed to permit of the removal of a 
 calculus and is then called suprapubic lithotomy. 
 
 THE MALE URETHRA (URETHRA VIRILIS) (Figs. 1047, 1048, 1049, 1050, 1054). 
 
 The urethra in the male extends from the neck of the bladder at the internal 
 orifice of the urethra (orificium urethrae internum) to the meatus urinarius, the 
 external orifice of the urethra (orificium urethrae 
 externum), at the end of the penis. The in- 
 ternal orifice has been described (p. 1439). The 
 urethra presents a double curve in the flaccid 
 state of the penis (Fig. 1054), but in the erect 
 state of this organ it forms only a single curve, 
 the concavity of which is directed upward. Its 
 length varies from eight to nine inches; and it 
 is divided into three portions, the prostatic, 
 membranous, and spongy, the structure and re- 
 lations of which are essentially different. Ex- 
 cept during the passage of the urine or semen, 
 the urethra is a mere cleft or slit, transverse, T- 
 shaped or crescentic (Fig. 1049), with its upper 
 and under surfaces in contact. At the meatus 
 urinarius the slit is vertical, and in the prostatic 
 portion somewhat arched (Fig. 1049). 
 
 The First or Prostatic Portion (pars pros- 
 iatica) (Figs. 1037, 1047, 1048, 1055, and 1056). 
 — The first or prostatic portion is the widest and Corpus 
 most dilatable part of the canal. It is between 
 the internal orifice of the urethra and the supe- 
 rior layer of the triangular ligament and is within 
 the pelvic cavity. It passes between the two 
 lateral lobes of the prostate gland, from the base 
 to the apex of the gland, lying nearer its ante- 
 rior than its posterior surface. The gland seems 
 to completely surround this portion of the 
 urethra (Fig. 1053), but the glandular matter of 
 the gland does not (Fig, 1051) . The gland is like 
 a buckle open in front, and the open part of the 
 buckle is closed by the prostatic muscle. The 
 prostatic urethra is about an inch and a quarter 
 in length; the form of the canal is spindle- 
 shaped, being wider in the middle than at either 
 
 extremity, and narrowest below, where it joins the membranous portion. Except 
 during the passage of fluid, the canal is in a collapsed state, the anterior wall resting 
 upon the posterior wall (Fig. 1049), and the mucous membrane exhibiting longitu- 
 
 91 
 
 Glans. 
 
 Fossa 
 tiavic. 
 
 MeatuLS. 
 
 Fig. 1047. — The male urethra, laid open on 
 its anterior (upper) surface. (Testut.) 
 
1442 
 
 THE UBINABY OBGANS 
 
 dinal folds. When distended, the largest portion of the prostatic urethra has a 
 diameter of about one-third of an inch. A transverse section of the canal as it 
 lies in the prostate is horseshoe-shape J, the convexity being directed forward 
 (Fios. 1049 and 1051). The direction of the canal is nearly vertical, there being 
 a slight curve, which is concave forward (Figs. 1037 and 1038j. 
 
 Upon the posterior wall or floor of the canal is a narrow longitudinal ridge, the 
 crest of the urethra {crista urethralis) , formed by an elevation of the mucous mem- 
 brane and its subjacent tissue (Fig. 1047). This crest begins at the uvula vesicae, 
 and passes through the prostatic portion and into the membranous portion of the 
 urethra (Fig.1056), and usually bifurcates at its distal end ; it contains, according to 
 Kobelt, muscular and erectile tissues. On this longitudinal ridge is an enlargement, 
 the verumontanum or caput gallinaginis (colliculus seminalis) (Figs. 1047 and 1056). 
 When distended, it may serve to prevent the passage of the semen backward into 
 the bladder. On each side of the verumontanum is a slightly depressed fossa, the 
 floor of which is perforated by numerous apertures, the orifices of the prostatic ducts 
 (Figs. 1047 and 1056), from the lateral lobes of the glands; the ducts of the middle 
 
 MUSCULAR WALL 
 OF BLADDER 
 
 PROSTATIC 
 SINUS 
 
 LONGITUDINAL MUS- 
 CLES OF URETHRA 
 
 Fig. 1048. — Proximal portion.^ of urethra with surrounding parts. (After Testut.) 
 
 lobe open behind the verumontanum. At the forepart of the verumontanum, in the 
 middle line, is a depression, the prostatic sinus, prostatic utricle, prostatic vesicle, 
 uterus masculinus or sinus pocularis {utriculus prostaticus) (Yigs.lOSS and 1056) ; and 
 upon or within its margins are the slit-like openings of the ejaculatory ducts (diwtus 
 ejaculatorii) (Fig. 1056). The sinus pocularis forms a cul-de-sac about a quarter of 
 an inch in length, which runs upward and backward in the substance of the pros- 
 tate behind the transverse band of prostatic tissue which joins the lateral lobes 
 behind the posterior wall of the urethra ; its prominent anterior wall partly forms 
 the verumontanum. Its walls are composed of fibrous tissue, muscular fibres, 
 and mucous membrane, and numerous small glands open on its inner surface. 
 It has been called by Weber, who discovered it, the uterus masculinus, from its 
 being developed from the united lower ends of the atrophied Miillerian ducts, 
 and therefore being homologous with the uterus and vagina in the female. 
 
 The Second, Muscular or Membranous Portion(par5 membranacea) (FigsA047, 
 1048, and 1056) extends downward and forward between the apex of the prostate 
 and the bulb of the corpus spongiosum. It is the narrowest part of the canal (except- 
 ing the meatus), and measures three-quarters of an inch along its upper, and half 
 an inch along its lower, surface, in consequence of the bulb projecting backward 
 
THE 3fALE UBETHBA 
 
 1443 
 
 •aS^J 
 
 beneath it. Its anterior concave surface is placed about an inch below and behind 
 the pubic arch, from which it is separated by the dorsal vessels and nerves of the 
 penis, and some muscular fibres. Its posterior convex surface is separated from 
 the rectum by a triangular space, which constitutes the perineum. The membra- 
 nous portion of the urethra lies chiefly between the inferior and superior layers of 
 the triangular ligament(Fig.309) . The termination of this part of the urethra is over- 
 lapped by the bulb, and is in front of the triangular ligament 
 (Fig. 309j. As it pierces the inferior layer, the fibres around 
 the opening are prolonged over the tube and fix the two struc- 
 tures firmly to each other. The membranous urethra is sur- 
 rounded by cavernous tissue and by the Compressor urethrae 
 muscle (m. sphincter urethrae membrc.naceae)[F\g.3lO) . On the 
 floor of the membranous urethra is the anterior extremity of 
 the crista urethralis. Behind this part of the urethra, on each 
 side of the middle line, are Cowper's glands (Figs. 308 and 1056). 
 The canal enters the bulb a little in front of the posterior 
 extremity, and the anterior wall or roof of the membranous 
 urethra is a little longer than the posterior wall or floor. The 
 backward projection of the bulb hangs over most of the floor 
 of the membranous urethra (Figs. 308, 309, 1047, 1056, and 
 1058). When the urethra is empty the mucous membrane of 
 the second part is thrown into longitudinal folds, which are 
 obliterated by distention. 
 
 The Third, Penile, Pendulous, Cavernous or Spongy 
 Portion (pars cavernosa) (Figs. 1037, 1047, 1048, and 1050) is 
 the longest part of the urethra, and is contained in the corpus 
 
 I 
 
 RIGHT LIP OF MEATUS 
 
 PREPUCE RETRACTED- 
 
 LATERAL LACUNA 
 UPPER WALL OF URETHRA- 
 
 SPONGY BODY — cot surfaea- 
 
 -SKIN 
 
 -SIDE OF URETHRA 
 
 -LARGE LACUNA 
 
 _SPONQY BODY — cut SUrfaCS 
 
 MEDIAN LACUN>C 
 
 CORPUS 
 
 SPONGIOSUM 
 
 Fig. 1050.- 
 
 -The distal portion of the male urethra, laid open on its posterior 
 (under) surface, showing the lacunae. (Testut.) 
 
 ^'i'^'^ni 
 
 
 xs 
 
 Fig. 1049. — Cross-sec- 
 tionsof the male urethra at 
 various distances from its 
 free end, showing marked 
 alterations of form. (Tes- 
 tut.) 
 
 spongiosum. It is about six inches in length, and extends from the termination 
 of the membranous portion to the meatus urinarius. It is surrounded throughout 
 its entire course by the erectile tissue of the corpus spongiosum and glans penis. 
 Its proximal end is fixed in position and unchangeable in direction. Its distal end 
 is movable and changeable in direction. Commencing just below the triangular 
 ligament it is first directed forward through the bulb; it then passes downward 
 and forward, the turn beginning at the seat of attachment of the suspensory 
 ligament of the penis (Fig. 1037) . The direction of the third portion of the urethra 
 is changed by alterations in the position of the penis. When the canal is closed the 
 anterior and posterior walls are in contact (roof and floor), except in the glans 
 
1444 THE URINARY ORGANS 
 
 penis, where the lateral walls come together. "Thus the first part of the canal 
 when empty is represented in cross-section by a transverse slit, and the terminal 
 part by a vertical slit "^ (Fig. 1049). The calibre of the spongy urethra varies in 
 different portions of the tube. It is of larger diameter in the bulb (bulbous por- 
 tion of urethra) and in the glans than between these two points. In the body of 
 the penis the canal is of uniform size, and is about one-quarter of an inch in 
 diameter. The fossa naviculaxis (fossa navicularis urethrae [Morgagni]) is an 
 oblong dilatation of the terminal portion of the penile urethra (Figs. 1037, 1047, 
 and 1060). In the front of the fossa navicularis there is a transverse fold of 
 mucous membrane, the valve of Guerin (valvulae fossae navicularis). It is part 
 of a distinct depression or pocket. The fossa navicularis opens anteriorly by 
 the meatus urinarius. 
 
 The meatus urinarius or external orifice of the urethra (orificium urethrae externum) 
 (Figs. 1047 and 1059) is the most contracted part of the urethra; it is a vertical slit 
 (Fig. 1049), about three lines in length,bounded on each side by a small lip or labium. 
 
 The inner surface of the lining membrane of the urethra, especially on the floor 
 of the spongy portion, presents the orifices of numerous mucous glands (Fig. 1050) 
 situated in the submucous tissue, and named the glands of Littx^ (glandulae ure- 
 thrales). A number of little recesses or follicles, called lacmiae (lacunae urethrales), 
 open into the penile urethra. Some of the glands of Littreopen into the lacunae; 
 some do not. They vary in size, and their orifices are directed forward, so that they 
 may easily intercept the point of a catheter in its passage along the canal. One 
 of these lacunae, larger than the rest, is situated in the upper surface of the fossa 
 navicularis, about half an inch from the orifice; it is called the lacuna magna (Fig. 
 1060) . Into the bulbous portion are found opening the ducts of Cowper's glands. 
 
 Structure. — The urethra is composed of a continuous mucous membrane, 
 supported by a submucous tissue which connects it with the various structures 
 through which it passes. 
 
 The Mucous Coat. — The mucous coat forms part of the genito-urinary mucous 
 membrane. It is continuous with the mucous membrane of the bladder, ureters, 
 and kidneys; externally with the integument covering the glans penis; and is pro- 
 longed into the ducts of the glands which open into the urethra — viz., Cowper's 
 glands and the prostate gland — into the vasa deferentia and the seminal vesicles 
 through the ejaculatory ducts. The mucous membrane is arranged in longitudinal 
 folds when the tube is empty. Small papillae are found upon it near the orifice, 
 and its epithelial lining is of the columnar variety, excepting near the meatus, 
 where it is squamous. 
 
 The Glands and Crypts of the Urethral Mucous Membrane (Fig. 1049). — There is a 
 pocket, the lacuna magna (Fig. 1060) , opening to the front in the upper wall of the 
 fossa navicularis. The fossa is bounded by the valve of Guerin (valvulae fossa 7iavic- 
 ularis) . The lacunae of Morgagni are in the spongy urethra back of the valve of 
 Guerin. The lacunae look forward. The largest of them is on the roof of the fossa 
 navicularis, one and one-half inches from the orifice (see above). Some of the 
 lacunae receive the secretion from the glands of Littre; others do not, because some 
 of the glands open on the free surface. The larger lacunae are one-third of an inch 
 deep and are placed in a longitudinal row upon the anterior wall. The smaller 
 lacunae are in longitudinal rows at the sides of the tube. The glands of Morgagni 
 are present throughout the urethra, except in its most anterior part. In the prostatic 
 urethra they are arranged in rows. In the membranous urethra they are scat- 
 tered irregularly. In the spongy portion they are most numerous on the anterior 
 wall and are more plentiful on the sides than on the floor. Besides the lacunae and 
 racemose glands, there are the opening of the prostatic glands, the ejaculatory 
 ducts, Cowper's glands, and the opening of the sinus pocularis. 
 
 1 Professor A. Francis Dixon, in Professor D. J. Cunningham's Text-book of Anatomy. 
 
 I 
 
THE MALE URETHRA I445 
 
 The Submucous Tissue. — The submucous tissue consists of a vascular erectile 
 layer. It contains the glands of Littre, especially in the posterior part. These 
 glands are lined with cylindrical epithelium and enter the submucous coat. 
 
 The Muscular Layer. — The muscular layer is continuous with the muscle of the 
 prostate and bladder. It is composed of non-striated muscle arranged in an 
 outer layer of circular fibres {stratum circulare) and an inner layer of longitudinal 
 fibres (stratum longitudinale). It is placed external to the submucous coat. In 
 the penile urethra there is only a thin layer of longitudinal fibres. In the mem- 
 branous urethra and the prostatic urethra there are two layers of muscle, an inner 
 thin layer of longitudinal fibres and a thicker layer of circular fibres. The longi- 
 tudinal fibres, when contracted, shorten the urethra and increase its diameter. 
 The circular fibres are in a state of tonic contraction and close the urethra. In 
 fact, they constitute the real sphincter (Zeissl, Zuckerkandl). The so-called 
 sphincter of the urethra, the Accelerator urinae, is a voluntary muscle and is not 
 the real sphincter. Outside of the muscular layer of the urethra is the tissue 
 of the corpus spongiosum. 
 
 Surgical Anatomy. — The urethra may be ruptured by the patient falling astride of any hard 
 substance and striking his perinseum, so that the urethra is crushed against the pubic arch. 
 Bleeding will at once take place from the urethra, and this, together with the bruising in the 
 perinseum and the history of the accident, will at once point to the nature of the injury. 
 
 Rupture of the urethra leads to exiravasation of urine. In rupture back of the superior layer 
 of the triangular ligament the urine usually follows the rectum and reaches the margin of the 
 anus. Rupture between the two layers of the triangular ligament liberates urine between the 
 two layers, where it remains until a path of exit is made by suppuration or the surgeon's knife. 
 In rupture in front of the anterior layer of the ligament the urine passes into the scrotum and 
 may mount up to the abdomen between the symphysis and the pubic spine, between which 
 points the deep layer of the superficial fascia is not attached. It cannot pass to the thigh nor 
 cross the mid-line, because the fascia is attached to the fascia lata and at the mid-line. 
 
 The surgical anatomy of the urethra is of considerable importance in connection with the 
 passage of instruments into the bladder. Otis was the first to point out that the urethra is 
 capable of great dilatation, so that, excepting through the external meatus, an instrument corre- 
 sponding to 18 English gauge (29 French) can usually be passed without damage. The orifice 
 of the urethra is not so dilatable, and therefore may require slitting, although the introduction 
 of the Oberlander dilator, which is expanded after introduction, renders slitting of the meatus 
 seldom necessary in cases of chronic gonorrhoea. A recognition of this dilatability caused Bige- 
 low to very considerably modify the operation of lithotrity and introduce that of litholapaxy. 
 In passing a fine catheter, the point of the instrument after it has passed the lacuna magna 
 should be kept as far as possible along the upper wall of the canal, as the point is otherwise 
 very liable to enter one of the lacunae. Stricture of the urethra is a disease of very common 
 occurrence, and is generally situated in the spongy portion of the urethra, most commonly in 
 the bulbous portion, just in front of the membranous urethra, but in a very considerable num- 
 ber of cases in the penile or ante-scrotal part of the canal. Even in a normal urethra, and very 
 markedly in an inflamed urethra, a bougie encounters resistance behind the bulb. This is 
 usually supposed to be due to spasm of the Compressor urethrae muscle. 
 
 In irrigation of the urethra by gravity fluid tends to block at the same point, especially if it is 
 thrown in suddenly or forcibly. If a reservoir is raised seven and one-half feet from the floor, 
 and if a patient sits on a chair or lies upon a bed, fluid can be readily made to pass by hydraulic 
 pressure from the meatus to the bladder. Spasm may temporarily prevent the inflow, but the 
 weight of the column of fluid soon tires out the muscle and causes it to relax. Relaxation 
 is favored by having the patient take slow, deep breaths and make efforts at urination 
 (Valentine). 
 
 Chronic gonorrhoea is frequently kept up by persistent inflammation of the ducts and follicles in 
 the mucous membrane. This condition is known as chrome glandular urethritis or para- 
 urethritis. In these crypts and glands gonococci may remain when gonorrhoea appears to have 
 passed away, and from time to time reinfection of the urethra may arise from such a source. 
 
 Median urethrotomy or perineal section is opening of the membranous urethra. Through such 
 an opening the bladder can be drained and explored, and the operation is sometimes called 
 median cystotomy. 
 
 In lateral lithotomy the knife enters the membranous urethra and strikes the groove of the 
 staff. Its edge is then turned toward the left ischial tuberosity and is carried along the groove 
 into the bladder, dividing the membranous urethra, the prostatic urethra, the posterior layer of 
 the triangular ligament, the Compressor urethrae muscle, anterior fibres of the Levator ani 
 muscle and the left lobe of the prostate gland. 
 
1446 THE UBINARY ORGANS 
 
 THE FEMALE URINARY BLADDER. 
 
 The female bladder is situated at the anterior part of the pelvis. It is in relation, in 
 front, with the symphysis pubis ; behind, with the utero-vesical pouch of peritoneum, 
 which separates it from the body of the uterus; its base lies in contact with the 
 connective tissue in front of the cervix and upper part of the vagina. Laterally, 
 is the recto-vesical fascia. The bladder is said by some anatomists to be larger in 
 the" female than in the male. At any rate, it does not rise above the symphysis 
 pubis till more distended than in the male, but this is perhaps owing to the more 
 capacious pelvis rather than to its being of actually larger size. It is described 
 in the section on the Bladder (p. 1431). 
 
 THE FEMALE URETHRA (URETHRA MULIEBRIS). 
 
 The female urethra is a narrow membranous canal, about an inch and a half in 
 length, extending from the internal urethral orifice (orificium urethrae internum) 
 at the neck of the bladder to the vestibule of the vagina, where it ends, being 
 called at its termination the external orifice of the urethra or the meatus urinarius 
 {orificium urethrae externum). The meatus is usually a vertical slit. Tiie 
 urathra is placed behind the symphysis pubis, embedded in the anterior wall 
 of the vagina; and its direction is obliquely downward and forward, its course 
 being slightly curved, the concavity directed forward and upward. Its diameter 
 when undilated is about a quarter of an inch. The urethra perforates both 
 layers of the triangular ligament, and its external orifice is situated directly in 
 front of the vaginal opening and about an inch behind the glans clitoridis. Except 
 above, the posterior wall of the urethra is firmly connected to the anterior wall 
 of the vagina. 
 
 Structure. — The urethra consists of three coats: muscular, erectile, and mucous. 
 
 The Muscular Coat (tunica muscularis) . — The muscular coat is continuous witli 
 that of the bladder; it extends the whole length of the tube, and consists of an 
 internal layer of non-striated longitudinal fibres {stratum longitudinale) and an 
 external layer of non-striated circular fibres {stratum circulare). Superficial to the 
 circular fibres "lies a layer of cross-striped muscle-fibres, which form a closed ring 
 near the bladder only."^ 
 
 The Submucous Coat {tunica submucosa). — Internal to the muscular coat is the 
 submucous coat, which contains a venous plexus, networks from which pass 
 between the muscular layers and impart to these layers an erectile or spongy 
 nature {corpus spongiosum urethrae). In addition to this, between the two layers 
 of the triangular ligament, the female urethra is surrounded by the Compressor 
 urethrae muscle, as in the male. 
 
 The Mucous Coat tunica mucosa). — The mucous coat is pale, continuous exter- 
 nally with that of the vulva, and internally with that of the bladder. It is thrown 
 into longitudinal folds, one of which, placed along the floor of the canal, extends 
 from the vesical trigone almost to the external orifice of the urethra. It is called 
 the crest {crista urethralis). The outline of the urethra is stellate when collapsed, 
 because of the formation of numerous longitudinal folds. It is lined by laminated 
 epithelium, which becomes transitional near the bladder. Many mucous glands 
 open into the urethra, and there are numerous lacunae. External to the external 
 orifice, on each side, a group of mucous glands opens by a common duct, the 
 ductus para-urethralis. 
 
 The urethra, because it is not surrounded by dense resisting structures, as in the male, admits 
 of great dilatation, which enables the surgeon to remove with considerable facility calculi or 
 other foreign bodies from the cavity of the bladder. 
 
 ' Hand Atlas of Human Anatomy. By Prof. Werner Spalteholz. Translated and edited by Prof. Lewellys F. 
 Barker. 
 
THE MALE OEGANS OF GENERATION. 
 
 PROSTATIC 
 MUSCLE 
 
 GLANDULAR 
 TISSUE 
 
 THE PROSTATE GLAND (PROSTATA) (Figs. 1048, 1051, 1052, 1053, 1054, 
 
 1055, 1056, 1057). 
 
 THE prostate gland {Ttimarrjiu, to stand before) is a structure accessory to the 
 true generative organs and furnishes a viscid, opalescent secretion in which 
 spermatozoids will live (W. G. Richardson). It is a pale, firm, partly glandular 
 and partly muscular body, which is 
 placed immediately below the neck of the 
 bladder and about the commencement of 
 the urethra in the male. The prostate 
 appears to completely surround the first 
 portion of the urethra (Figs. 1053 and 
 1057), but the glandular matter does not 
 in reality completely surround the tube 
 (Figs. 1051 and 1057). As Spalteholz 
 says, it partly surrounds it as a broad 
 clasp, o'pen in front. This opening in the 
 glandular tissue is closed, and a com- 
 plete ring is established about the urethra 
 by the prostatic muscle (m. prostaticus) 
 Figs. 1051 and 1057). This muscle below is composed of striated fibres and 
 is continuous with the Compressor urethrae {m. sphincter urethrae memhranacea) ; 
 
 UTBICLC 
 
 Fig. 1051. — Section of the prostate. 
 
 MUSCULAR 
 LAYER OF 
 URETHRA 
 URETHRA 
 
 EJACULATORV 
 DUCT 
 
 (Jarjavay.) 
 
 PROSTATIC 
 MUSCLE 
 
 COMPRESSOR 
 URETHRAE MUSCLE 
 
 SUPERFICIAL 
 TRANSVERSE 
 PERINEAL 
 MUSCLE 
 
 TRANSVERSE 
 PERINEAL LIGAMENT 
 
 Fig. 1052.— Side view of the position of the prostate. (Poirier and Charpy.) 
 
 above it is composed of non-striated muscle, and is continuous with the circular 
 muscular fibres of the bladder which surround the ii^ternal urethral orifice and 
 
 ^^ ( 1447 ) 
 
1448 
 
 THE MALE ORGANS OF GENERATION 
 
 constitute the Sphincter vesica? (Fig. 1052). The general course of the fibres is 
 transverse, with radiations into the gland substance. The apex of the gland for 
 about one-quarter of an inch is completely surrounded by the muscle (Fig. 1052). 
 
 VAS 
 DEFERENS 
 
 PROSTATE 
 
 Fig. 1053. — Prostate with seminal vesicles and seminal ducts, viewed from in front and above. 
 
 (Spalteholz.) 
 
 Ascending from the apex the fibres cover for a short distance only the front of the 
 gland and are attached at the sides to the fascia (Fig. 1052) . Higher up the muscle 
 
 AMPULLA 
 
 OF VAS 
 
 DEFERENS 
 
 VAS 
 DEFERENS 
 
 EJACULATORY 
 DUCT 
 PROSTATIC 
 UTRICLE 
 PROSTATE 
 GLAND 
 COWPER 
 GLAND 
 
 PERITONEUM 
 
 ! URETHRA 
 
 CORPUS 
 SPONGIOSUM 
 
 CORPUS 
 CAVERNOSUM 
 
 HYDATID OF 
 MORGAGNI 
 
 Fig. 1054. — Diagrammatic representation of the male reproduction organs and their relations to the bladder 
 and the urethra. Lateral view. (Toldt.) 
 
 passes between the sheath and the capsule and ascends to the base of the prostate, 
 uniting the sheath to the capsule along the mid-line in front. The prostate is placed 
 in the pelvic cavity, behind the lower part of the symphysis pubis, and above the 
 
THE PROSTATE GLAND 
 
 1449 
 
 deep layer of the triangular ligament, and rests upon the rectum, through which 
 it may be distinctly felt, especially when enlarged (Fig. 1055.) 
 
 The ejaculatory ducts (Figs. 1053, 1054, and 1056) enter the prostate at the margin 
 which separates the base from the posterior surface of the gland ; they pass down- 
 ward, inward, and forward through the prostate, and open into the prostatic 
 urethra. The prostate when surrounded by its sheath resembles a chestnut in 
 shape. When dissected out from its sheath and capsule and from the Prostatic 
 muscle, it resembles an "open clasp" or horseshoe. The sheath of the prostate 
 
 LEC^T COMMON 
 ILIAC VEIN 
 
 Fig. 1055. — Sagittal section of the lower part of a male trunk, the right segment. (Testut.) 
 
 is derived from the recto-vesical fascia. It is called the prostatic fascia (fascia pro- 
 statae), is distinct and dense, and covers the entire prostate, except at the apex and 
 at the attachment of the base of the prostate to the neck of the bladder. The pros- 
 tatic fascia is a distinct structure, though it is thin. The veins of the prostatic 
 plexus lie in the layers of the sheath, "and are everywhere separated from the 
 prostatic capsule proper by a layer of this sheath."^ In an enlarged prostate 
 the sheath is thick and fibrous. It is very difficult to shell out a normal prostate 
 from its sheath, but it is easy to shell out an enlarged prostate. Within the pros- 
 tatic sheath (which, be it remembered, carries the veins) is the true or proper capsule 
 
 1 J. W. Thomson Walker, in the British Medical Journal, July 9, 1904. 
 
1450 
 
 THE MALE ORGANS OF GENERATION 
 
 of the prostate. The true capsule is a continuous investment from the entrance 
 of the urethra above to the triangular hgament below. It is thin, but firm and 
 fibrous. It is not everywhere absolutely distinct from the sheath, but may be fused 
 
 EJACULATOBY 
 DUCT 
 
 MOUTH OF EJACU- 
 
 LATORY DUCT 
 VERUMONTANUM- — 
 
 PROSTATE — CUT SURFACE 
 OPENINGS OF 
 PROSTATIC DUCTS 
 
 MEMBRANOUS URETHRA 
 
 DUCT OF COWPERS 
 
 GLAND— LAID BARE 
 
 A RIDGE OF 
 
 MUCOSA 
 BULBOUS 
 URETHRA 
 
 CORPUS SPON- 
 GIOSUM — CUT SURFACE 
 
 Fig. 1056. — Proximal portion of the urethra, laid open by a median, anterior cut. (Testut.) 
 
 Fig. 1057. — Transverse section of normal prostate through the middle of the verumontanum, from a subject 
 aged nineteen years: a, longitudinal section of ducts leading from the lobules of the pro.static glands ; 6, veru- 
 montanum ; c, .sinus pocularis ; d, urethra ; e, ejaculatory ducts ; /", arteries, veins, and venous sinuses in sheath 
 of prostate ; (i, nerve trunks in sheath ; h, point of origin of fibro-muscular bands encircling urethra ; i, zone of 
 striated voluntary muscle on superior surface. (Drawn from Erdinger projection apparatus.) (Taylor.) 
 
THE PROSTATE GLAND 1451 
 
 with it here and there, and many bands of fibres run from the sheath to the capsule/ 
 The capsule is continuous with the stroma of the gland and cannot be stripped off as 
 can the kidney capsule. Any attempt to strip off the capsule tears away fragments 
 of gland. The capsule is composed of fibrous tissue and unstriated muscle-fibres. 
 From its deep surface the capsule is continuous with the stroma of the prostate (W. G. 
 Richardson). Sir Henry Thompson, half a century ago, pointed out the distinction 
 between true capsule and sheath, and suggested these names. The prostate is divided 
 for study into a base, apex, posterior surface, anterior surface, and lateral surfaces. 
 
 The Base {basis prostatae). — The base is directed upward, and is situated 
 immediately below the base of the bladder. It is in contact with and supports the 
 base of the bladder. The external longitudinal muscular layer of the bladder is 
 attached to the posterior portion of the base of the prostate, and some of the fibres 
 reach and adhere to the true capsule. The anterior portion of the base is called 
 the isthmus (isthmus prostatae) (Fig. 1053). 
 
 The Apex (apex prostatae). — The apex is directed downward and rests upon 
 the deep layer of the triangular ligament. The apex is fixed, except for the slight 
 mobility of the triangular ligament ; the rest of the gland is somewhat movable. 
 
 Surfaces. — The Posterior Surface (fades posterior). — The posterior surface is 
 flattened, marked by a slight longitudinal furrow, and rests on the second part of 
 the rectum, and is distant about one inch and a half from the anus. At the upper 
 and posterior border of the gland are the seminal vesicles. Their direction is 
 downward and inward; in fact, almost transverse. 
 
 The Anterior Surface (facies anterior). — The anterior surface is convex, and placed 
 about three-fourths of an inch behind the pubic symphysis, from which it is separated 
 by a plexus of veins and a quantity of loose fat. It is connected to the pubic bone 
 on either side by the pubo -pro static ligament. It is shorter than the posterior surface. 
 
 The Lateral Surfaces. — The lateral surfaces are prominent, and are covered by 
 the anterior portions of the Levatores ani muscles, which are, however, separated 
 from the gland by a plexus of veins. 
 
 The prostate measures about an inch and a half transversely at the base, an 
 inch in its antero-posterior diameter, and an inch and a quarter in its vertical 
 diameter. Its weight is about four and a half drachms. It is held in position 
 by the anterior ligaments of the bladder (ligamenta puboprostatica) ; by the deep 
 layer of the triangular ligament, which invests the commencement of the mem- 
 branous portion of the urethra and prostate gland ; and by the anterior portions of 
 the Levatores ani muscles, which pass backward from the os pubis and embrace 
 the sides of the prostate. These portions of the Levatores ani, from the support 
 they afford to the prostate, are named the Levator prostatae. 
 
 The prostate consists of two lateral lobes and a middle lobe. 
 
 The Lateral Lobes (lobus dexter et sinister). — The two lateral lobes are of 
 equal size, separated by a deep notch above, and by a furrow upon the anterior 
 and posterior surfaces of the gland, which indicates the bilobed condition of the 
 organ in some animals. At the upper and posterior portion of the prostate the 
 two lobes are united by two bands of gland-tissue. One of these bands is in front 
 of the ejaculatory ducts, the other is below them. "The upper limit of the gland 
 is thus in the form of a horseshoe, open in front. "^ Below the level of the prostatic 
 ducts the prostate and urethra are in relation, but are not closely connected. 
 Above this level the connection is intimate (J. W. Thomson Walker). 
 
 The So-called Middle Lobe (lobv^ medius). — The middle lobe is not in reality a 
 lobe, and the name is usually employed to describe an enlargement of the region of 
 the prostate on the posterior portion of the urethra in front of the ejaculatory ducts. 
 The so-called third or middle lobe is an abnormal condition. It is due to enlargement 
 of the transverse band of prostatic tissue which joins the lateral lobes beneath the 
 
 > W. G. Richardson on the Development and Anatomy of the Prostate Gland. 
 2 J. W. Thomson Walker, in the British Medical Journal, July 9, 1904. 
 
1452 THE MALE ORGANS OF GENERATION 
 
 base of the bladder, behind the posterior wall of the urethra and in front of the e jacu- 
 latory ducts. This mass of tissue is beneath the uvula vesicae. Walker points out 
 that frequently nodules of enlarged prostate protrude into the bladder^ being covered 
 only by bladder mucous membrane. This is accomplished by the enlarging pros- 
 tate forcing its way through the lumen of the vesical sphincter and dilating it, 
 and separating and passing between the strands of tiie internal longitudinal 
 muscle of the bladder. " The so-called middle lobe is formed by the protrusion of 
 a nodule between the two bands of muscle which pass into the trigone from the 
 ureters, and unite on the posterior wall of the prostatic urethra."^ 
 
 The urethra passes forward between the lateral lobes of the prostate. The 
 prostate is perforated by the ejaculatory ducts. The urethra usually lies on the 
 level of the junction of the anterior and middle thirds of a lateral lobe. The 
 ejaculatory ducts pass obliquely downward and forward through the posterior 
 part of the prostate, and open into the prostatic portion of the urethra. 
 
 Structure (Fig. 1057) . — As previously stated (p. 1449), the prostate is surrounded 
 by a sheath from the recto- vesical fascia, and possesses also a true capsule. 
 
 The glands of the prostate are of the branched tubular variety and number 
 forty or fifty. Many of the ducts join and form from fifteen to twenty-five smaller 
 ducts, which empty into the prostatic urethra, to the sides of the verumontanum 
 (Fig. 1056). The ducts and glands are lined with cubical epithelium. The 
 prostatic secretion or prostatic fluid (succus prostaticus) is a viscid, opalescent, 
 serous secretion, alkaline in reaction, containing a ferment, but no mucus. The 
 substance of the prostate is of a pale, reddish-gray color, of great density and 
 not easily torn. It consists of glandular substance and muscular tissue. 
 
 The muscular tissue, according to KoUiker, constitutes the proper stroma of 
 the prostate, the connective tissue being very scanty, and simply forming thin 
 trabeculae between the muscular fibres, in which the vessels and nerves of the 
 gland ramify. The true capsule is continuous with the stroma. The stroma lies 
 between the glandular substance and strands of stroma pass in convergent lines 
 toward the prostatic urethra, especially toward the dorsum of the urethra. These 
 strands or septa divide the prostate into small irregular subdivisions called lobules. 
 Next to the urethra, the stroma forms a thick layer. As age advances the inter- 
 stitial tissue of the prostate increases and the glandular substance shrinks. 
 
 Vessels and Nerves. — The arteries supplying the prostate are derived from the 
 internal pudic, inferior vesical, and middle haemorrhoidal. Branches of the vessels 
 enter the gland in the septa between the lobules and send off minute branches to the 
 lobules (Walker). The veins form a plexus around the sides and base of the gland 
 between layers of the fascial sheath; they receive in front the dorsal vein of the 
 penis, and terminate in the internal iliac vein. The lymphatics of the prostate 
 begin as networks about the acini of the gland, pass to beneath the capsule, and 
 form another network, and from this peripheral network collecting trunks arise. 
 Several trunks pass from the posterior portion of the gland. One trunk passes to 
 the external iliac glands, one to the internal iliac glands, and several end in the 
 lateral sacral glands, and the glands of the sacral promontory. An anterior trunk 
 is joined by lymphatics from the membranous urethra and prostatic urethra and 
 passes to a gland on the internal pudic artery.^ The nerves are derived from the 
 hypogastric plexus. 
 
 Surgical Anatomy. — The relation of the prostate to the rectum should be noted : by means of 
 the finger introduced into the gut the surgeon detects enlargement or other disease of the prostate; 
 he can feel the apex of the gland, which is the guide to Cock's operation for stricture; he is enabled 
 also by the same means to direct the point of a catheter when its introduction is attended with 
 difficulty either from injury or disease of the membranous or prostatic portions of the urethra. 
 When the finger is introduced into the bowel the surgeon may, in some cases, especially in boys, 
 
 1 J. W. Thomson Walker, in the British Medical Journal, July 9, 1904. 
 - Poirier and Charpy. Human Anatomy. 
 
THE PENIS 1453 
 
 learn the position, as well as the size and weight, of a calculus in the bladder. In the operation 
 for the removal of a calculus, if, as is not unfrequently the case, the stone should be lodged 
 behind an enlarged prostate, it may be displaced from its position by pressing upward the base 
 of the bladder from the rectum. The prostate gland is occasionally the seat of suppuration, either 
 due to injury, gonorrhoea, or tuberculous disease. The gland is enveloped in a dense unyield- 
 ing capsule, which determines the course of an abscess, and also explains the great pain which is 
 present in acute inflammation. The abscess most frequently bursts into the urethra, the direc- 
 tion in which there is least resistance, but may occasionally burst into the rectum, or more rarely 
 in the perinanun. In advanced life the prostate often becomes considerably enlarged, and may 
 project into the bladder so as to impede the passage of the urine. According to Dr. Messer's 
 researches, conducted at Greenwich Hospital, it would seem that such obstruction exists in 20 
 per cent, of all men over sixty years of age. The prostate may be enlarged by the growth of 
 innocent tumors, adenomata, fibromata, myomata, and myofibromata. The entire gland may 
 be hypertrophied. A tumor may be encapsulated, but often is surrounded by an area of hyper- 
 plasia of prostatic tissues, and usually the area of hyper[)lasia is much more extensive than the 
 tumor. A tumor may be beneath the mucous membrane, deep in the gland, or beneath the 
 sheath. The growth called the third lobe is submucous. In some cases the enlargement affects 
 principally the lateral lobes, which may undergo considerable enlargement without causing much 
 inconvenience. In other cases it would seem that the nodule forms the so-called middle lobe, 
 and even a small enlargement of this character may act injuriously, by forming a sort of valve 
 over the urethral orifice, preventing the passage of the urine, and the more the patient strains, 
 the more completely will it block the opening into the urethra. In consequence of the enlarge- 
 ment of the prostate a pouch is formed at the base of the bladder behind the projection, in which 
 urine collects and cannot entirely be expelled. The urine becomes decomposed and ammoniacal, 
 and leads to cystitis. If the prostate enlarges the urethra is lengthened, often dilated, altered 
 in shape, or distorted. 
 
 The relation of the enlarged prostate to the neck of the bladder is greatly altered from the 
 relation of the normal prostate. Normally, it is extra vesical ; when enlarged it may encapsule 
 "the neck of the bladder in a cuff-like manner, extending several inches upward on its wall," 
 and often it protrudes "into the vesical cavity, carrying on its surface the mucosa vesicae."^ In 
 many cases of prostatic enlargement the gland should be removed (prostatectomy). One method 
 is enucleation through a suprapubic incision; another method is enucleation through a perineal 
 incision; another method is carried out by both incisions (the combined method). 
 
 The Bottini operation is prostatotomy, effected by a special instrument for the purpose of 
 cauterizing the gland and thus causing shrinking. 
 
 In elderly individuals the gland tubules may form round, indurated, and sometimes calcified 
 masses, about 1 mm. in diameter, and called prostatic stones. 
 
 COWPER'S GLANDS (GLANDULAE BULBO-URETHRALES) 
 
 (Figs. 1056, 1063). 
 
 Cowper's glands are two small, rounded, and somewhat lobulated bodies of 
 a yellow color, about the size of peas, placed behind the forepart of the mem- 
 branous portion of the urethra, between the two layers of the triangular ligament. 
 They lie close above the bulb, and are enclosed by the transverse fibres of the 
 Compressor urethrae muscle. Their existence is said to be constant; they gradually 
 diminish in size as age advances. 
 
 Structure. — Each gland consists of several lobules held together by a fibrous 
 investment. Each lobule consists of a number of acini lined by columnar epithe- 
 lial cells, opening into one duct, which, joining with the ducts of other lobules 
 outside the gland, form a single excretory duct (ductus excretorius) . The excretory 
 duct of each gland, nearly an inch in length, passes obliquely forward beneath 
 the mucous membrane, and opens by a minute orifice on the floor of the bulbous 
 portion of the urethra. 
 
 THE PENIS (Figs. 1058, 1059, 1060, 1061, 1062, 1063). 
 
 The penis is a long body of prismatic shape placed below and in front of the 
 symphysis pubis. It surrounds the greatest length of the urethra. It consists 
 of a root, body, and extremity or glans penis. The root and the posterior portion 
 
 ' .John B. Murphy, in the Journal of the American Medical Association, May 28, 1904. 
 
1454 
 
 THE MALE ORGANS OF GENERATION 
 
 of the body lie beneath the scrotum and the integument of the perinseum (Fig. 
 
 1054), and are firmly fixed to the triangular ligament, the pubic bones, and the 
 
 symphysis; hence this portion of the organ 
 is called the fixed portion {'pars fxa) (Fig. 
 309). The balance of the organ is free 
 
 FOSSA OF __ MO 
 FRAENUM ~ 
 
 PREPUCE 
 RETRACTED 
 
 Fig. 1058. — The penis, proximal portion, seen 
 from below. (Testut.) 
 
 rMEDIAN GROOVE 
 
 ™ - FRAENUM 
 
 Fig. 1059. — Glans penis, tui.Ioi -urface. (Testut.) 
 
 'DISTAL PART OF SEP- 
 TUM PECTINIFORM 
 
 SSA NAVI 
 U LA R I S 
 
 - FRENUM 
 _VALVE OF LA- 
 CUNA MAGNA 
 
 —LEFT SIDE OF URETHRA 
 -FLOOR OF URETHRA 
 
 LACUNA MAGNA 
 
 and movable (Fig. 1054), and is called the mobile portion (pars mobilis). When 
 
 the penis is relaxed there is an angle between the fixed and mobile portions; 
 
 when the penis is erect, the angle disappears. 
 
 The Root (radix penis). — The root is firmly connected to the rami of the os 
 
 pubis and iscliium by two strong tapering, fibrous processes, the crura (Figs. 1058, 
 
 1062, and 1063), and to the front of the symphysis pubis by the suspensory liga- 
 ^^^^^jg ment (Fig. 1001), a strong band 
 
 of fibrous tissue which passes 
 downward from the front of 
 the symphysis pubis to the root 
 of the penis. 
 
 The extremity, acorn or 
 glans penis (Figs. 1059 and 
 1060j presents the form of an 
 obtuse cone, flattened from 
 above downward. At its sum- 
 mit is a vertical fissure, the ex- 
 ternal orifice of the urethra or 
 the meatus urinarius (orificium 
 ureihrae externum). The base 
 of the glans forms a rounded 
 projecting border, the corona 
 glandis, and behind the corona 
 is a deep constriction, the cer- 
 vix or neck (collum glandis). 
 Upon both the corona and neck 
 numerous small sebaceous 
 glands are found, the glandulae 
 
 Tysonii odoriferae.^ They secrete a sebaceous matter of very peculiar odor, which 
 
 probably contains caseine and becomes easily decomposed. 
 
 1 Stieda (Comptes-rendus du XII. Congres International de M^decine. Mo.<?cow. 1897) asserts that Tyson's 
 glands are never found on the corona glandis, and that what have hitherto been mistaken for glands are really 
 Jarge papillae.— Ed. of 15th English edition. 
 
 PREPUCE 
 RETRACTED 
 
 CAVERNOSUM CORPUS 
 
 SPONGIOSUM 
 
 Fig. 1060.- 
 
 -The penis, distal end, in sagittal section one-twelfth inch 
 at left of middle line. (Testut ) 
 
THE PENIS 
 
 1455 
 
 The Body of the Penis (corpus penis). — The body of the penis is the part 
 between the root and extremity. In the flaccid condition of the organ it is cyHn- 
 drical, but when erect it has a triangular prismatic form with rounded angles, the 
 broadest side being turned upward, and called the dorsum penisi. The lower sur- 
 face of the body of the penis is called the urethral surface {fades urethralis). The 
 body is covered by integument, and contains in its interior a large portion of the 
 urethra. The integument covering the penis is remarkable for its thinness, its 
 dark color, its looseness of connection with the deeper parts of the organ, and for 
 the absence of adipose tissue. At the root of the penis the integument is contin- 
 uous with that upon the pubes and scrotum, and at the neck of the glans it leaves 
 the surface and becomes folded upon itself to form the prepuce (praeputium) (Fig. 
 1059) . The internal layer of the prepuce is attached behind to the cervix or neck 
 (Fig. 1059), and approaches in character to a mucous membrane; from the cervix 
 it is reflected over the glans penis, and at the meatus urinarius is continuous with 
 the mucous lining of the urethra. 
 
 The integument covering the glans penis contains no sebaceous glands, but 
 projecting from its free surface are a number of small, highly sensitive papillae. 
 
 SUPERFICIAL 
 
 FIBRES OF 
 
 SUSPENSORY 
 
 LIGAMENT 
 
 DEEP FIBRES 
 
 OF SUSPENSORY 
 
 LIGAMENT 
 
 DORSAL VEIN 
 
 DORSAL ARTERY 
 
 DORSAL NERVE 
 
 PERITONEUM 
 
 ANTERIOR 
 LIGAMENT 
 OF BLADDER 
 
 SUBPUBIC 
 LIGAMENT 
 
 ERECTA PENIS 
 MUSCLE 
 
 Fig. 1061. — The suspensory ligament. (Poirier and Charpy.) 
 
 At the back part of the meatus urinarius a fold of mucous membrane passes 
 backward to the bottom of a depressed raph^, where it is continuous with the 
 prepuce; this fold is termed thefraenum {frenulum praeputii). The skin of the penis 
 covers the mobile parts of the organ. It is thin, extremely elastic, and contains very 
 few hairs. Beneath the skin of the penis is the dartos layer (Figs. 1061 and 1068), 
 continuous with the scrotal dartos, containing chiefly non-striated muscular fibres 
 arranged longitudinally. It passes forward to the orifice of the prepuce, and 
 then turns backward, growing thinner and thinner, and finally disappearing at 
 the cervix. Beneath the dartos and extending forward to the orifice of the pre- 
 puce is a sheath of areolar tissue. It is a lax sheath rich in elastic tissue and 
 containing almost no fat. The superficial vessels and nerves are in the areolar 
 sheath. Beneath the areolar sheath of € e penis, from the corona to the root, is 
 the fascia of the penis (fascia penis) (Fig. 1068). It covers the organ from the root 
 to the corona, and also covers the dorsal artery, veins, and nerves. It is continuous 
 behind with the superficial perineal fascia and suspensory ligament. It is com- 
 posed chiefly of elastic tissue. 
 
 Structure of the Penis. — The penis is composed of a mass of erectile tissue 
 enclosed in three cylindrical fibrous compartments. Of these, two, the corpora 
 
1456 
 
 THE MALE ORGANS OF OENEMATION 
 
 cavernosa, are placed side by side along the upper part of the organ; the third, or 
 corpus spongiosum, encloses the urethra and is placed below. 
 
 The Two Corpora Cavernosa (corpora cavernosa penis)(Figs. 1062 and 1063). — The 
 two corpora cavernosa form the chief part of the body of the penis. They consist of 
 two fibrous cylindrical tubes, placed side by side, and intimately connected along 
 the median line for their anterior three- 
 fourths, whilst at their back part they 
 separate from each other to form the 
 crura penis, which are two strong taper- 
 ing fibrous processes or roots firmly -<r --^^ in . « 
 connected to the rami of the os pubis (f K^ ( uTV \ , / f-" 
 and ischium -(Figs. 1058, 1062, and ^^Aa,J3 \:%^J, 
 1063). Each crus commences by 
 
 VAS 
 DEFERENS 
 
 CORONA. 
 GLANDIS 
 
 Fig. 1062. — The penis, with the pubic bones, seen 
 from before and below. (Toldt.) 
 
 EXTERNAL ORIFICE 
 OF URETHRA 
 
 Fig. 1063. — The penis, with the urethra, Cowper s 
 glands, the ijrostate gland, and the seminal vesicles, 
 seen from below and behind. (Toldt). 
 
THE PENIS 
 
 1457 
 
 blunt-pointed process in front of the tuberosity of the ischium, and before its junc- 
 tion with its fellow to foi'in the body of the penis it presents a slight enlargement, 
 named by Kobelt the bulb of the corpus cavemosum. Just beyond this point they 
 become constricted, and retain an e(|ual diameter to their anterior extremity, where 
 they form a single rounded end which is received into a fossa in the base of the glans 
 penis (Figs. 1060 and 1062). A median groove on the upper surface lodges the 
 dorsal arteries, nerves, and veins of the penis (Figs. 1066, 1067, and 1068), and the 
 groove on the under surface receives the corpus spongiosum (Fig. 1062). The root 
 of the penis is connected to the symphysis pubis by the suspensory ligament. 
 
 Structure (Fig. 1068). — Each corpus cavernosum is composed of erectile tissue. 
 The erectile tissue is surrounded by a strong fibrous envelope, the tunica albuginea, 
 corporum cavernosum, consisting of two sets of fibres — the one, longitudinal in direc- 
 tion, being common to the two corpora cavernosa, and investing them in a com- 
 mon covering; the other, internal, circular in direction, and being proper to each 
 corpus cavernosum. The internal circular fibres of the two corpora cavernosa 
 form, by their junction in the mesial plane, an incomplete partition or septum, 
 the septum penis, between the two bodies. 
 
 SUSPENSORY 
 LIGAMtNT 
 
 Fig. 1064. — The dartos. (Poirier and Charpy.) 
 
 Fifi. 1065. — From the peripheral portion of the corpus 
 cavernosum penis under a low magnifying power. 1, o, 
 capillar.y network; 6, cavernou.s spaces; 2, connection of 
 the arterial twigs (a) with the cavernous spaces. (Copied 
 from Langer.) 
 
 The septum between the two corpora cavernosa is thick and complete behind, 
 but in front it is incomplete, and consists of a number of vertical bands, which are 
 arranged like the teeth of a comb, whence the name which it has received, septum 
 pectiniforme. These bands extend between the dorsal and the urethral surface 
 of the corpora cavernosa. The fibrous investment of the corpora cavernosa is 
 extremely dense, of considerable thickness, and consists of bundles of shining 
 white fibres, with an admixture of well-developed elastic fibres, so that it is pos- 
 sessed of great elasticity. 
 
 From the interna! surface of the fibrous envelope, as well as from the sides of 
 the septum, are given off a number of bands or cords which cross the interior of 
 each crus in all directions, subdividing it into a number of separate compart- 
 
 U2 
 
1458 THE MALE ORGANS OF GENERATION 
 
 ments, and giving the entire structure a spongy appearance. These bands and 
 cords are called trabeculae corporum cavemosum, and consist of white fibrous 
 tissue, elastic fibres, and plain muscular fibres. In them are continued numer- 
 ous arteries and nerves. 
 
 The component fibres of which the trabeculae are composed are larger and 
 stronger around the circumference than at the centre of the corpora cavernosa; 
 they are also thicker behind than in front. The interspaces, on the contrary, are 
 larger at the centre than at the circumference, their long diameter l)eing directed 
 transversely; they are largest anteriorly. They are called cavernous spaces and 
 are occupied by venous blood, and are lined by a layer of flattened cells similar 
 to the endothelial lining of veins (Fig. 1065). 
 
 The whole of the structure of the corpora cavernosa contained within the 
 fibrous sheath consists, therefore, of a sponge-like tissue the areolar spaces of 
 which freely communicate with each other and are filled with venous blood. 
 The spaces may therefore be regarded as large cavernous veins. 
 
 The arteries bringing the blood to these spaces are the arteries of the corpora 
 cavernosa and branches from the dorsal artery of the penis, which perforate the 
 fibrous capsule, along the upper surface, especially near the forepart of the organ. 
 
 These arteries on entering the cavernous structure divide into branches which 
 are supported and enclosed by the trabeculae. Some of these terminate in a 
 capillary network, the branches of which open directly into the cavernous spaces 
 (Fig. 1065) ; others assume a tendril-like appearance, and form convoluted and 
 somewhat dilated vessels, which were named by Miiller helicine arteries (arteriae 
 helicinae). They project into the spaces, and from them are given off small 
 capillary branches to supply the trabecular structure. They are bound down in 
 the spaces by fine fibrous processes, and are more abundant in the back part of the 
 corpora cavernosa. 
 
 The blood from the cavernous spaces is returned by a series of vessels, some of 
 which emerge in considerable numbers from the base of the glans penis and con- 
 verge on the dorsum of the organ to form the deep dorsal vein; others pass out on the 
 upper surface of the corpora cavernosa and join the dorsal vein; some emerge from 
 the under surface of the corpora cavernosa, and, receiving branches from the corpus 
 spongiosum, wind around the sides of the penis to terminate in the dorsal vein; 
 but the greater number pass out at the root of the penis and join the prostatic plexus. 
 
 The Corpus Spongiosum (corpus cavemosum urethrae) (Figs. 1060, 1062, and 
 1063). — The corpus spongiosum encloses the urethra, and is situated in the groove 
 on the under surface of the corpora cavernosa penis. It commences posteriorly 
 below the superficial layer of the triangular ligament of the urethra, between 
 the diverging crura of the corpora cavernosa, where it forms a rounded enlarge- 
 ment, the bulb of the urethra (hulhus urethrae), and terminates anteriorly in another 
 expansion, the glans penis (Figs. 1059, 1060, 1062, and 1063), which overlaps the 
 anterior rounded extremity of the corpora cavernosa. The central portion, or body 
 of the corpus spongiosum, is cylindrical, and tapers slightly from behind forward. 
 
 The Bulb of the Urethra (Figs. 1058, 1062, and 1063) varies in size in different 
 subjects; it receives a fibrous investment from the superficial layer of the triangular 
 ligament, and is surrounded by the Accelerator urinae muscle. The urethra enters 
 the bulb nearer its upper than its lower surface, being surrounded by a layer of 
 erectile tissue, a thin prolongation of which is continued backward around the 
 membranous and prostatic portions of the canal to the neck of the bladder, lying 
 between the two layers of muscular tissue. The portion of the bulb below the 
 urethra presents a partial division into two lobes (hemisphaeria hulhi urethrae), 
 being marked externally by a linear raphe, whilst internally there projects, for a 
 short distance, a thin fibrous median septum {septum hulhi urethrae), which is more 
 distinct in earlv life. 
 
THE PENIS 
 
 1459 
 
 Structure. — The corpus spongiosum consists of a strong fibrous envelope 
 enclosing a trabecular structure, which contains in its meshes erectile tissue. The 
 fibrous envelope is thinner, whiter in color, and more elastic than that of the corpora 
 
 CAVERNOUS 
 BRANCH 
 
 DORSAL ARTCRV 
 
 CORPUS CAVERNOSUM 
 
 
 INTERNAL PUDIC 
 
 '^i-'V^ 
 
 Fig. 1066. — Diagram of the arteries of the penis. (Testut.) 
 
 cavernosa of the penis. The trabeculae are more delicate, more nearly uniform 
 in size, and the meshes between them smaller than in the corpora cavernosa, 
 their long diameter, for the most part, corresponding with that of the penis. 
 The external envelope or outer coat of the corpus spongiosum is formed partly 
 of unstriped muscular fibre, and a 
 layer of the same tissue immediately 
 surrounds the canal of the urethra. 
 
 Ligaments of the Penis. — The sus- 
 pensory ligament (ligamentum siis- 
 'pensorium 'penis) (Fig. 1061) is firm 
 and fibrous. It passes from the front 
 of the symphysis pubis to the tunica 
 albuguinea of the corpora cavernosa. 
 The ligamentum fundiforme penis 
 (P'ig. 1058), formerly called the sus- 
 pensory ligament, arises from the 
 linea alba, sheath of the rectus, 
 superficial fascia, and symphysis 
 pubis, and surrounds the penis in 
 a loop, being attached more distal- 
 w^ard than is the suspensory liga- 
 ment, and usually passes into the 
 scrotum. It is composed of elastic 
 tissue. 
 
 Vessels and Nerves of the Penis. — 
 The arteries (Fig. 1066) of the penis 
 come from branches of the internal 
 pudic artery. The deep arteries of 
 the penis give the chief supply to 
 the erectile tissue of the corpora 
 cavernosa, and the dorsal artery also 
 sends branches to it ; the artery of 
 the bulb (p. 691) supplies the erectile 
 
 tissue of the corpus spongiosum. The chief blood-supply of the glans is from 
 the dorsal artery (p. 692). In the trabeculae the arteries are very small and often 
 twisted. The twisted vessels are called helicine arteries. The small arteries 
 open directly into the venous spaces. The veins of the penis empty directly into 
 
 UPERFICIAL DORSAL VEIN 
 EXTERNAL PUDIC VEIN 
 
 OBTURATOR VEIN 
 
 Fig. 1067.— Veins of the penis. (Testut.) 
 
1460 THE MALE ORGANS OF GENERATION 
 
 the prostatic plexus or into the deep dorsal vein, which empties into the prostatic 
 plexus. On each side of the deep dorsal vein is a dorsal artery and external 
 to each dorsal artery is a dorsal nerve (Fig. 106S). The superficial dorsal vein 
 (Figs. 1067 and 1068), receiving small veins from the prepuce, passes back 
 beneath the skin, reaches the symphysis and divides into two branches, each of 
 which passes to the corresponding superficial external pudic vein. 
 
 The lymphatics of this region have been studied carefully by Poirier, Cun^o, 
 and ITelamare,^ which book I have freely used. 
 
 The lymphatics of the skin of the penis and prepuce are continuous (Fig. 501). 
 Those on the internal surface of the prepuce are continuous with those of the glans. 
 The trunks of the cutaneous lymphatics anastomose with each other, ascend by 
 the dorsal vein, and terminate in the inguinal glands. The trunks from the glans 
 
 converge toward the frsenum ; they 
 
 'sVL^JEl'N"""' then ascend to the median part of 
 
 the corona, and the vessels of the two 
 
 /^<^;;^|^^^^^\ sides unite. Several collectors as- 
 
 so PE R F?c\TCZTi^. ^^fe^J^^^^i^r tIssu e" ccud ou thc dorsum to the inguinal 
 
 and femoral glands. 
 *RTEHY T¥v^5f^/^§|^fM??Pii/ii;i I The superior wall of the anterior 
 
 portion of the urethra is drained by 
 the lymphatic trunks from the glans. 
 From the rest of the penile urethra 
 
 SUPERFICIAL DOR- 
 SAL VEIN 
 DORSAL ARTERY | .DEEP DORSAL VEIN 
 
 CORPUS cavernosum: 
 
 DEEP 
 FASCIA 
 
 ""'"-ANTER^R'sifANc"''^'' ^PuRETHRA thc lymphatlcs uultc with the trunks 
 
 SPONGIOSUM from the penis, and most of them ter- 
 
 FiG. 1068.— The penis in transverse section, showing minatc ill the Same WaV, althoUffh 
 
 the blood-vessels. (Testut.) <• i i i 
 
 one or them passes between the 
 Recti muscles and terminates in the deeper external iliac glands or in the 
 "internal retro-crural gland. "^ 
 
 The trunks from the bulb and membranous urethra terminate in the external 
 iliac glands, the "internal retro-crural gland," and the glands along the internal 
 pudic artery (Poirier, Cuneo, and Delamare). The trunks from the prostatic 
 urethra join the trunks from the prostate gland. 
 
 The nerves are derived from the internal pudic nerve and the pelvic plexus. On 
 the glans and bulb some filaments of the cutaneous nerves have Pacinian bodies 
 connected with them, and, according to Krause, many of them terminate in a 
 peculiar form of end-bulb. 
 
 Surgical Anatomy. — It is occasionally necessary to remove a penis for malignant disease. 
 Usually, removal of the ante-scrotal portion is all that is necessary, but sometimes it is requisite 
 to remove the whole organ from its attachment to the rami of the ossa pubis and ischia. The 
 former operation is performed either by cutting off the whole of the anterior part of the penis 
 with one sweep of the knife, or, what is better, cutting through the corpora cavernosa from the 
 dorsum, and then separating the corpus spongiosum from them, dividing it at a level nearer the 
 glans penis. The mucous membrane of the urethra is then slit up, and the edges of the flap 
 attached to the external skin, in order to prevent contraction of the orifice, which would other- 
 wise take place. The vessels which require ligature are the two dorsal arteries of the penis, the 
 arteries of the corpora cavernosa, and the artery of the septum. When the entire organ requires 
 removal the patient is placed in the lithotomy position, and an incision is made through the 
 skin and subcutaneous tissue around the root of the penis, and carried down the median line of 
 the scrotum as far as the perinaeum. The two halves of the scrotum are then separated from 
 each other, and a catheter having been introduced into the bladder as a guide, the spongy por- 
 tion of the urethra below the triangular ligament is separated from the corpora cavernosa and 
 divided, the catheter having been withdrawn just behind the bulb. The suspensory ligament 
 is now severed, and the crura separated from the bone with a periosteum scraper, and the whole 
 penis removed. The membranous portion of the urethra, which has not been removed, is now 
 to be attached to the skin at the posterior extremity of the incision in the perinseum. The 
 remainder of the wound is to be brought together, free drainage being provided for. 
 
 1 Translated and edited by Cecil H. Leaf. 
 
 * The Lymphatics. By Poirier, Cun6o, and Delamare. Translated and edited by Cecil H. Leaf. 
 
DESCENT OF THE TESTIS 
 
 1461 
 
 THE TESTICLES (TESTES) AND THEIR COVERINGS (Figs. 1071, 1072). 
 
 The testicles are two glandular organs, which secrete the semen; they are situ- 
 ated in the scrotum, being suspended by the spermatic cords. At an early period 
 of foetal life the testes are contained in the abdominal cavity, behind the peri- 
 toneum, but they subsequently descend into the scrotum. 
 
 DESCENT OF THE TESTIS (DESCENDUS TESTIS). 
 
 Each testis at an early period of foetal Ufe is placed at the back part of the 
 abdominal cavity, behind the peritoneum, in front and a little below the kidney. 
 The anterior surface and sides are invested by peritoneum. At about the third 
 month of intra-uterine life a peculiar structure, the gubemaculum testis, makes its 
 appearance. This structure is at first a slender band which extends from the 
 situation of the internal ring to the epididymis and body of the testicle, and is 
 then continued upward in front of the kidney toward the Diaphragm. As devel- 
 opment advances the peritoneum covering the testicle encloses it and forms a 
 mesentery, the mesorchium, which also encloses the gubemaculum and forms two 
 folds — one above the testicle, and the other below it. The one above the testicle is 
 
 STOMOSIS 
 VEINS 
 
 Fig. 1069. — Vaginal tunics of the testicle. 
 (Poirier and Charpy.) 
 
 Fig. 1070. — Ligament of the scrotum. 
 (Poirier and Charpy.) 
 
 the plica vascularis, and contains ultimately the spermatic vessels; the one below, 
 the plica gubernatrix, contains the lower part of the gubemaculum, which has now 
 grown into a thick cord ; it terminates below at the internal ring in a tube of peri- 
 toneum, the processus vaginalis, which now lies in the inguinal canal. The lower 
 part of the gubemaculum by the fifth month has become a thick cord, whilst the 
 upper part has disappeared. The lower part can now be seen to consist of a cen- 
 tral core of unstriped muscle-fibre, and outside this of a firm layer of striped 
 elements, connected, behind the peritoneum, with the abdominal wall. Later on, 
 about the sixth month, the lower end of the gubemaculum can be traced into the 
 inguinal canal, extending to the pubes, and, at a later period, to the bottom of 
 the scrotum. The fold of peritoneum constituting the processus vaginalis pro- 
 jects itself downward into the inguinal canal, forming a gradually elongating 
 depression or cul-de-sac, which eventually reaches the bottom of the scrotum. This 
 cul-de-sac is now invaginated by the testicle, as the body of the foetus grows, for the 
 gubemaculum does not grow commensurately with the growth of other parts, and 
 therefore the testicle, being attached by the gubemaculum to the bottom of the 
 
1462 THE MALE ORGANS OF GENERATION 
 
 scrotum, is prevented from rising as the body grows, and is drawn first into the 
 inguinal canal, and eventually into the scrotum. By the eighth month the tes- 
 ticle has reached the scrotum, preceded by the lengthened pouch of peritoneum, 
 the processus vaginalis, which communicates by its upper extremity with the 
 peritoneal cavity. Just before birth the upper part of the pouch usually becomes 
 closed, and this obliteration extends gradually downward to within a short dis- 
 tance of the testis. The process of peritoneum surrounding the testis, which is now 
 entirely cut off from the general peritoneal cavity, constitutes the tunica vaginalis.^ 
 
 Mr. Jacobson^ says that the attachments of the gubernaculum above are to 
 the vas, the epididymis, and afterward to the testicle. The lower attachments 
 of the gubernaculum, some of which are temporary, are the abdominal wall, 
 pubes and root of the scrotum, Scarpa's triangle, perina:^um and scrotum. The 
 remains of the scrotal fibres constitute a so-called ligament of the scrotum or 
 the mesorchium, which causes adhesion between the testicle and skin (Fig. 1070). 
 
 In the female, a small cord, corresponding to the gubernaculum in the male, 
 descends to the inguinal region and ultimately forms the round ligament of the 
 uterus. A pouch of peritoneum accompanies it along the inguinal canal, analogous 
 to the processus vaginalis in the male ; it is called the canal of Nuck. 
 
 Surgical Anatomy. — Abnormalities in the formation and in the descent of the testicle may 
 occur. The testicle may fail to be developed, or it may be fully developed and the vas deferens 
 may be undeveloped in whole or in part; or, again, both testicle and vas deferens may be fully 
 developed, but the duct may not become connected to the gland. The testicle may fail in its 
 descent (cryptorchismus) or it may descend into some abnormal position (ectopia testis) . Thus it 
 may be retained in the position where it was primarily developed, below the kidney; or it may 
 descend to the internal abdominal ring, but fail to pass through this opening; it may be retained 
 in the inguinal canal, which is perhaps the most common position; or it may pass through the 
 external abdominal ring and remain just outside it, failing to pass to the bottom of the scrotum. 
 On the other hand, it may get into some abnormal position; it may pass the scrotum and reach 
 the perinseum, or it may fail to enter the inguinal canal, and may find its way through the fem- 
 oral ring into the crural canal, and present itself on the thigh at the saphenous opening. Ectopia 
 testis is due to the absence, overdevelopment or malposition of some portion of the gubernacu- 
 lum. There is still a third class of cases of abnormality in the position of the testicle, where the 
 organ has descended in due course into the scrotum, but is malplaced. The most common form 
 of this is where the testicle is inverted; that is to say, the organ is rotated, so that the epididymis 
 is connected to the front of the scrotum, and the body, surrounded by the tunica vaginalis, is 
 directed backward. In these cases the vas deferens is to be felt in the front of the cord. The 
 condition is of importance in connection with hydrocele and haematocele, and the position of 
 the testicle should always be carefully ascertained before performing any operation for these 
 affections. Again, more rarely, the testicle may be reversed. This is a condition in which the 
 top of the testicle, indicated by the globus major of the epididymis, is at the bottom of the 
 scrotum, and the vas deferens comes off from the summit of the organ. 
 
 THE COVERINGS OF THE TESTICLE (Fig. 1073). 
 The coverings of the testicle are the following: 
 
 Skin ] a * 
 T-. - y Scrotum. 
 Dartos j 
 
 Intercolumnar or External spermatic fascia. 
 
 Cremasteric fascia. 
 
 Infundibuliform or Fascia propria (Internal spermatic fascia). 
 
 Tunica vaginalis. 
 
 The Testicular Bag or Scrotum (Figs. 1071 and 1072).— The testicular bag or 
 scrotum is a cutaneous pouch which contains the testes and part of the spermatic 
 cords. It is divided on its surface into two lateral portions by a median line or 
 
 1 The obliteration of the process of peritoneum which accompanies the cord, and is hence called the funicular 
 ■process, is often incomplete. See section on Inguinal Hernia. 
 ^ Diseases of the Male Organs of Generation. 
 
THE COVERINGS OF THE TESTICLE 
 
 1463 
 
 raph^ {raphe scroti), which is continued forward to the under surface of the penis 
 and backward along the middle line of the perinseum to the anus. Of these two 
 lateral portions, the left is usually longer than the right, and corresponds with the 
 usual greater length of the spermatic cord on the left side. Its external aspect varies 
 under different circumstances: thus under the influence of warmth and in old and 
 debilitated persons it becomes elongated and flaccid, but under the influence of cold 
 and in the young and robust it is short, corrugated, and closely applied to the 
 testes. The wrinkles in the scrotum are called rugae. 
 
 The scrotum consists of two layers, the integument and the dartos. 
 
 RIGHT INGUINAL CANAL 
 
 (opened; 
 
 CREMASTERIC MUSCLE- 
 AND FASCIA 
 INTERCOLUMNAR 
 FASCIA 
 
 fpERSJSTENT SEROUS 
 — ■< CAVITY AROUND 
 
 (^OORO EXCEPTIONAL 
 
 TUNICA VAGINALIS 
 
 PARIETAL LAYER 
 INFUNOIBULIFORM 
 
 FASCIA 
 NO N- PEDUNCULATED 
 HYDATID 
 
 RIGHT HALF OF SCROTUM SKIN 
 
 LEFT HALF OF SCROTUM 
 
 Fig. 1071. — The scrotum. On the left side the cavity of the tunica vaginalis has been opened ; on the 
 right side only the layers superficial to the cremaster have been removed. (Testut.) 
 
 The Integument. — The integument is very thin, of a brownish color, and gen- 
 erally thrown into folds or rugae. It is provided with sebaceous follicles, the 
 secretion of which has a pecidiar odor, and is beset with thinly-scattered, crisp 
 hairs, the roots of which are seen through the skin. 
 
 The Dartos {tunica dartos) (Figs. 1064 and 1071). — The dartos is a thin layer of 
 loose tissue, endowed with contractility; it forms the proper tunic of the scrotum, 
 is continuous around the base of the scrotum, with the two layers of the super- 
 ficial fascia of the groin and perinaeum, and sends inward a distinct septum, 
 the septum of the scrotum {septum scroti) (Fig. 1071), which divides it into two 
 cavities for the two testes, the septum extending between the raphe and the 
 under surface of the penis as far as its root. 
 
 The dartos is closely united to the skin externally, but connected with the 
 
1464 
 
 THE MALE ORGANS OF GENERATION 
 
 subjacent parts by delicate areolar tissue, upon which it glides with the greatest 
 facility. The dartos is very vascular, and consists of a loose areolar tissue con- 
 taining unstriped muscular fibre, but no fat. Its contractibility is slow, and 
 excited by cold and mechanical stimuli, but not by electricity. 
 
 The Intercolumnar or Spermatic Fascia (Fig. 1071). — The intercolumnar 
 fascia is a thin membrane derived from the margin of the pillars of the external 
 abdominal ring, during the descent of the testis in the foetus, which is prolonged 
 downward around the surface of the cord and testis. It is separated from the 
 
 EXTERNAL 
 
 ABDOMINAL 
 
 RING 
 
 ACCESSORY 
 
 SLIP OF 
 
 ORIGIN OF- 
 
 CREMASTER 
 
 MUSCLE 
 
 SPERMATIC 
 CORD 
 
 CREMASTER. 
 MUSCLE 
 
 SEPTUM 
 SCROTUM 
 
 AS 
 DEFERENS 
 
 SPERMATIC 
 ARTERY 
 
 NERVE-FILAMENTS 
 OF SPERMATIC 
 PLEXUS 
 
 DEFERENTIAL 
 ARTCRY 
 
 INFUNDIBULIFORM 
 FASCIA 
 
 SPERMATIC 
 PLEXUS 
 
 EPIDIDYMIS 
 PARIETAL 
 LAYER OF 
 TUNICA 
 VAGINALI 
 
 Fig. 1072.— The scrotum. The penis has been turned upward, and the anterior wall of the scrotum has been 
 removed. On the right side, the spermatic cord, the infundibuliform fascia and the Cremaster muscle are dis- 
 played; on the left side, the infundibuliform fascia has been divided by a lonRitudinal incision passing along the 
 front of tlie cord and the testicle, and a portion of the parietal layer of the tunica vaginalis has been removed to 
 display the testicle and a portion of the head of the epididymis, which are covered by the visceral layer of the 
 tunica vaginalis. (Toldt.) 
 
 dartos by loose areolar tissue, which allows of considerable movement of the 
 latter upon it, but is intimately connected with the succeeding layers. 
 
 The Cremasteric Fascia (jascia cremasterica) (Figs. 1071 and 1072).— The 
 cremasteric fascia consists of scattered bundles of muscular fibres, the Cremaster 
 muscle (m. cremaster) (Figs. 1071 and 1072) connected together into a continuous 
 covering by intermediate areolar tissue. The muscular fibres are continuous 
 with the lower border of the Internal oblique muscle. 
 
THE COVERINGS OF THE TESTICLE 
 
 1465 
 
 The Infundibuliform Fascia {tunica vaginalis communis [testis et funiculi sper- 
 maiici])(F'igs. 1071 and 1071). — The infundibuliform fascia is a thin membranous 
 
 Skin. 
 
 Dartos. 
 
 External spermatic fascia. 
 
 Cremasteric fascia. 
 
 Infundibuliform fascia. 
 
 Parietal tunica vaginalis. 
 
 Visceral tunica vaginalis. 
 
 Tunica vascnlosa.. 
 
 Tunica albuginea. 
 
 A lobule of the testicle.. Am 
 
 A septum. 
 
 Mediastinum. 
 
 Digital fossa. 
 
 Spermatic vein. 
 
 Epididymis. 
 
 Vas deferens. 
 
 Artery to vas. 
 
 Spermatic artery. 
 
 Internal cremastev 
 
 muscle. 
 
 Fig. 1073. — Transverse section through the left side of the scrotum and the left testicle. The sac of the 
 tunica vaginalis is represented in a distended condition. (Del6pine.) 
 
 layer, which loosely invests the surface of the cord. It is a continuation downward 
 of the fascia transversalis. Beneath it is a quantity of loose connective tissue which 
 connects this layer of fascia with the spermatic cord and posterior parts of the tes- 
 
 SPERMATIC 
 ARTERY 
 
 ANTERIOR 
 
 GROUP OF 
 
 VEINS 
 
 .CREMASTERIC 
 ARTERY 
 
 deferential 
 'artery 
 
 SEMINAL 
 
 "duct 
 
 POSTERIOR 
 -GROUP OF 
 VEINS 
 
 STOMOSIS 
 NS 
 
 Fig. 1074. — The arteries of the testicle and the cord. (Poirier and Charpy.) 
 
 tide. This connective tissue is continuous above with the subserous areolar tissue of 
 the abdomen. These two layers, the infundibuliform fascia and the tissue beneath 
 
1466 
 
 THE MALE ORGANS OF GENERATION 
 
 it, are known collectively as the fascia propria. The infundibuliform fascia com- 
 pletely encloses the testicle and epididymis and is fused with the parietal lamina 
 of the tunica vaginalis propria testis. 
 
 The Tunica Vaginalis {tunica vaginalis propria testis). — The tunica vagi- 
 nalis is described with the testis (p. 1469.) 
 
 Vessels and Nerves. — The arteries supplying the coverings of the testis are: 
 the superficial and deep external pudic, from the femoral; the superficial perineal 
 branch of the internal pudic; and the cremasteric branch from the deep epigastric. 
 The veins follow the course of the corresponding arteries. The lymphatics term- 
 inate in the inguinal glands. The nerves are: the ilio-inguinal branch of the 
 lumbar plexus, the two superficial perineal branches of the internal pudic nerve, 
 the inferior pudenal branch of the small sciatic nerve, and the genital branch of 
 the genito-crural nerve. 
 
 TRANSVERSALIS 
 FASCIA 
 
 DEEP 
 
 EPIGASTRIC 
 
 ARTERY 
 
 LIGAMENT 
 OF CLOQUET 
 
 SPERMATIC 
 ARTERY 
 
 PAMPINIFORM 
 PLEXUS 
 
 SPERMATIC 
 CORD 
 
 Fig. 1075. — The spermatic cord and the ligament of Cloquet. (Poirier and Charpy.) 
 
 THE SPERMATIC CORD (FUNICULUS SPERMATICUS) 
 
 (Figs. 1071, 1072, 1075, 1076). 
 
 The spermatic cord extends from the internal abdominal ring, where the 
 structures of which it is composed converge, to the back part of the testicle. In 
 the abdominal wall the cord passes obliquely along the inguinal canal, lying at 
 first beneath the Internal oblique muscle and upon the fascia transversalis ; but 
 nearer the pubes it rests upon Poupart's ligament, having the aponeurosis of 
 the External oblique in front of it and the conjoined tendon behind it. It then 
 escapes at the external ring, and descends nearly vertically into the scrotum. The 
 left cord is usually rather longer than the right, consequently the left testis 
 generally hangs somewhat lower than its fellow. 
 
 Structure. — The spermatic cord contains the spermatic duct, the deferential 
 artery and veins, the spermatic artery, the pampiniform plexus of veins, the sper- 
 matic plexus, and the deferential plexus of the sympathetic nerve, lymphatics, and 
 the cord-like remnant of the funicular process of peritoneum called the ligament 
 
THE SPERMATIC COBD 
 
 1467 
 
 of Cloquet (Fig. 1075) . All the above structures are held together by connective 
 tissue. These structures are ensheathed by the infundibuliform process of the trans- 
 versalis fascia {tunica vaginalis communis [testis et funiculi spermatid]) (Fig. 1075 
 and p. 1064) . This fascia is thin above and thicker below, and encloses the testicle 
 and epididymis, as well as the cord, being firmly adherent to the parietal layer of 
 the vaginal tunic of the testicle and with the posterior portion of the testicle and 
 epididymis. Upon this fascia are the fibres of the Cremaster muscle, which spring 
 from the internal oblique, and in this fascia are the cremasteric artery, the genital 
 branch of the genito-crural nerve, and external spermatic veins. This fascia is 
 surrounded by the intercolumnar or spermatic fascia (fascia or emasterica[Cooperi]), 
 which is distinct above, but not below. 
 
 Vessels and Nerves of the Spermatic Oord.^The arteries (Figs. 1074 and 1080) of 
 the cord are: the spermatic, from the aorta; the artery of the vas deferens, from 
 the superior vesical; the cremasteric, from the deep epigastric. 
 
 VAS 
 DEFERENS 
 
 SPERMATIC 
 CORD 
 
 Fig. 1076. — The spermatic cord in the inguinal canal. (Poirier and Charpy.) 
 
 The spermatic artery (a. spermatica interna) arises from the abdominal aorta 
 below the renal artery, descends by the Psoas muscle, crosses the ureter and 
 external iliac vessels, meets the vas deferens at the internal abdominal ring, 
 escapes from the abdomen at the internal or deep abdominal ring, and lying in 
 front of the vas deferens accompanies the other constituents of the spermatic cord 
 along the inguinal canal and through the external abdominal ring into the scrotum. 
 It then descends to the testicle,* and, becoming tortuous, divides into several 
 branches, two or three of which, the epididymal branches, accompany the vas 
 deferens and supply the epididymis, anastomosing with the artery of the vas 
 deferens and the cremasteric artery; others, the glandular branches, pierce the back 
 of tlie tunica albuginea and supply the substance of the testis. 
 
 The artery of the vas deferens, a branch of the superior vesical, is a long slender 
 vessel which accompanies the vas deferens, ramifying upon the coats of that duct, 
 and anastomosing with the spermatic artery and the cremasteric artery near the 
 testis. 
 
1468 
 
 THE MALE ORGANS OF GENERATION 
 
 The cremasteric artery (a. spermatica externa) is a branch of the deep epigas- 
 tric artery. It accompanies the spermatic cord and suppHes the Cremaster 
 muscle and other coverings of the cord, anastomosing with the spermatic and 
 deferential arteries. 
 
 The spermatic veins (Figs. 1074, 1075, 1076, and 1077) emerge from the back of 
 the testis and receive tributaries from the epididymis; they unite and form a con- 
 voluted plexus, the pampiniform plexus {plexus pampiniformis) , which forms the 
 chief mass of the cord ; the vessels composing this plexus are very numerous, and 
 ascend along the cord in front of the vas deferens ; below the external or super- 
 
 FiG. 1077. — Spermatic veins. (Testut.) 
 
 ficial abdominal ring they unite to form three or four veins, which pass along the 
 inguinal canal, and, entering the abdomen through the internal or deep abdominal 
 ring, coalesce to form two veins. These again unite to form a single vein, which 
 opens on the right side into the inferior vena cava at an acute angle, and on the 
 left side into the renal vein at a right angle. 
 
 The lymphatic vessels of the scrotum terminate in the superficial inguinal 
 glands. The lymphatics of the testicle join the lymphatics of the epididymis and of 
 the visceral layer of the vaginal tunic of the testicle, and ascend in the spermatic 
 cord. They reach the lumbar region along the spermatic blood-vessels and ter- 
 minate in the juxta-aorta glands, and sometimes in the glands in front of the 
 aorta. The lymphatics of the seminal duct pass to the external iliac glands. 
 
THE TESTICLES 1469 
 
 The nerves are the spermatic plexus from the sympathetic, joined by filaments 
 from the pelvic plexus which accompany the artery of the vas deferens. 
 The Ligament of the Scrotum.— See Fig. 1070 and p. 1462. 
 
 Surgical Anatomy. — The scrotum forms an admirable covering for the protection of the 
 testicle. This body, lying suspended and loose in the cavity of the scrotum, and surrounded by 
 a serous membrane, is capable of great mobility, and can therefore easily slip about within the 
 scrotum, and thus avoid injuries from blows or squeezes. The skin of the scrotum is very 
 elastic and capable of great distention, and on account of the looseness and amount of subcu- 
 taneous tissue the scrotum becomes greatly enlarged in cases of cedema, to which this part is 
 especially liable on account of its dependent position. The scrotum is frequently the seat of 
 epithelioma; this is no doubt due to the rugae on its surface, which favor the lodgement of dirt, 
 and this, causing irritation, is the exciting cause of the disease. Cancer was especially common 
 in chimney-sweeps from the lodgement of soot. The scrotum is also the part most frequently 
 affected by elephantiasis. 
 
 On account of the looseness of the subcutaneous tissue considerable extravasations of blood 
 may take place from very slight injuries. It is therefore generally recommended never to apply 
 leeches to the scrotum, since they may lead to considerable ecchymosis, but rather to puncture 
 one or more of the superficial veins of the scrotum in cases where local bloodletting from this 
 part is judged to be desirable. The muscular fibre in the dartos causes contraction and consider- 
 able diminution in the size of a wound of the scrotum, as after the operation of castration, and 
 is of assistance in keeping the edges together and covering the exposed parts. 
 
 THE TESTICLES (TESTES) (Figs. 1069, 1071, 1072, 1078, 1079). 
 
 The testicles are suspended in the scrotum by the spermatic cords. As the left 
 spermatic cord is rather longer than the right one, the left testicle hangs somewhat 
 lower than its fellow. Each gland is of an oval form, compressed laterally, and 
 having an oblique position in the scrotum, the upper extremity (extremitiis superior) 
 being directed forward and a little outward, the lower extremity (extremitus infe- 
 rior), backward and a little inward; the anterior convex border (margo anterior) 
 looks forward and downward; the posterior or straight border (margo posterior), 
 to which the cord is attached, backward and upward. 
 
 The anterior border and lateral surfaces (fades lateralis et fades medialis), as well 
 as both extremities of the organ, are convex, free, smooth, and invested by the 
 visceral layer of the tunica vaginalis. The posterior border, to which the cord is 
 attached, receives only a partial investment from that membrane. Lying upon 
 the outer edge of this posterior border is a long, narrow, flattened body, named, 
 from its relation to the testis, the epididymis (ocdopio^, testis) (Figs. 1078 and 1079). 
 The curve of the epididymis is convex outward and backward. It consists of 
 a central portion or body (corpus epididymidis) ; an upper enlarged extremity, the 
 head or globus major (caput epididymidis) ; and a lower pointed extremity, the tail 
 or globus minor (cauda epididymidis). The globus major is directed inward and 
 is intimately connected with the upper end of the testicle by means of its efferent 
 ducts, and the globus minor is connected with its lower end by cellular tissue and a 
 reflection of the tunica vaginalis. The globus minor bends suddenly and passes 
 into the seminal duct, the direction of which is upward and backward. The outer 
 surface and upper and lower ends of the epididymis are free and covered by 
 serous membrane; the body is also completely invested by it, excepting along its 
 posterior border, and between the body and the testicle is a pouch or cul-de-sac, 
 named the digital fossa (sinus epididymidis). Above this fossa is a fold of the 
 timica vaginalis, which is called the ligamentum epididymidis superior, and below 
 it is another fold, the ligamentum epididymidis inferior. The epididymis is con- 
 nected to the back of the testis by a fold of the serous membrane. Attached to 
 the upper end of the testis, close to the globus major, is a small body. It is oblong 
 in shape and has a broad base. Attached to the globus major of the epididymis 
 is another small body, which is pear-shaped and has a stalk. These bodies are 
 
1470 
 
 THE MALE ORGANS OF GENERATION 
 
 believed to be the remains of the upper extremity of the Miillerian duct, and are 
 termed the hydatids of Morgagni; some observers, however, regard the stalked 
 hydatid as being a rudiment of the pronephros. The body with a broad base is 
 the non-pedunculated hydatid (appendix testis [Morgagnii]) (Figs. 1071 and 1078} ; 
 
 Spermatic cord. 
 
 Artery of 
 cord. 
 
 Tunica vaginalis, 
 parietal layer. 
 
 Non-pedunculated 
 hydatid 
 Digital 
 foasa. 
 
 Fig. 1078. — The testis in situ, the tunica vaginalis 
 having been laid open. 
 
 MEDIASTINUM 
 TESTIS 
 
 ALBUGINEA 
 
 Fig. 1079. --Frontal section of the testicle and 
 epididymis. (Poirier and Charpy.) 
 
 Tunica Vaffinaiit. 
 Timica Albuginea. 
 
 Ductidi 
 efferentes. 
 
 Tubuli 
 
 seminiferi 
 
 recti. 
 
 the pear-shaped body is the 
 pedunculated hydatid (appendix 
 epididymidis) . When the tes- 
 ticle is removed from the body, 
 the position of the vas deferens, 
 on the posterior surface of the 
 testicle and inner side of the 
 epididymis, marks the side to 
 which the gland has belonged. 
 
 Size and Weight. — The aver- 
 age dimensions of this gland 
 are from one and a half to two 
 inches in length, one inch in 
 breadth, and an inch and a 
 quarter in the antero-postcrior 
 diameter, and the weight varies 
 from six to eight drachms, the 
 left testicle being a little the 
 larger. 
 
 The Tunics of the Testicle.— 
 The testis is invested by three tu- 
 nics — the tunica vaginalis, tunica 
 albuginea, and tunica vasculosa. 
 The Proper Sheath of the Testicle or the Tunica Vaginalis (tunica vaginalis propria 
 testis) (Figs. 1069, 1071, 1072, 1073, and 1080) is the serous covering of the testicle 
 and epididymis. It is a pouch of serous membrane, derived from the peritoneum 
 (processus vaginalis peritonaei) during the descent of the testis in the foetus from 
 the abdomen into the scrotum. After its descent that portion of the pouch which 
 
 Fig. 1080. 
 
 -Vertical section of the testicle, to show the arrange- 
 ment of the ducts. 
 
THE TESTICLES 1471 
 
 extends from the internal ring to near the upper part of the gland, the funicular 
 process, becomes obliterated, the lower portion remaining as a shut sac {tunica 
 vaginalis propria testis), which invests the outer surface of the testis, and is reflected 
 on to the internal surface of the scrotum; hence it may be described as consisting 
 of a visceral and parietal portion. 
 
 The Visceral Portion (lamina visceralis) of the tunica vaginalis propria covers 
 the outer surface of the testis, as well as the epididymis, connecting the latter to 
 the testis by means of a distinct fold. From the posterior border of the gland it 
 is reflected on to the internal surface of the infundibuliform process of the trans- 
 veisalis fascia, and between the tunic and the fascia is a layer of unstriated 
 muscle fibres, the Internal cremaster muscle (Fig. 1073). 
 
 The Parietal Portion {lamina parietalis) of the tunica vaginalis propria is the 
 reflected portion. It is far more extensive than the visceral portion, extending 
 upward for some distance in front and on the inner side of the cord, and reaching 
 below the testis. The inner surface of the tunica vaginalis is free, smooth, and 
 covered by a layer of endothelial cells. The interval between the visceral and 
 parietal layers of this membrane constitutes the cavity of the tunica vaginalis and 
 contains a small amount of serous fluid. 
 
 The obliterated portion of the pouch may generally be seen as a fibro-cellular 
 thread, the ligament of Cloquet {rudimentum processus vaginalis) (Fig. 1075), lying in 
 the loose areolar tissue around the spermatic c«rd ; sometimes this may be traced 
 as a distinct band from the upper end of the inguinal canal, where it is connected 
 with the peritoneum, down to the tunica vaginalis; sometimes it gradually becomes 
 lost on the spermatic cord. Occasionally no trace of it can be detected. In some 
 eases it happens that the pouch of peritoneum does not become obliterated, but 
 the sac of the peritoneum communicates with the tunica vaginalis. This may 
 give rise to one of the varieties of oblique inguinal hernia; or in other cases the 
 pouch may contract, but not become entirely obliterated ; it then forms a minute 
 canal leading from the peritoneum to the tunica vaginalis.^ 
 
 The Tunica Albuginea (Figs. 1073, 1079, and 1080j. — The tunica albuginea is 
 the fibrous covering of the testis. It is a dense fibrous membrane, of a bluish-white 
 color, composed of bundles of white fibrous tissue, which interlace in every direc- 
 tion. Its outer surface is covered by the tunica vaginalis, except at the points of 
 attachment of the epididymis to the testicle, and along its posterior border, wiiere 
 the spermatic vessels enter the gland. This membrane surrounds the glandular 
 structure of the testicle, and at its posterior border forms a projection, triangular 
 in shape and cellular in structure, which is reflected into the interior of the gland, 
 forming an incomplete vertical septum, called the mediastinum testis. 
 
 The Mediastinum Testis (corpus Highmori) (Figs. 1073, 1079, and 1080) extends 
 from the upper, neaily to the lower, extremity of the gland, and is wider above 
 than below\ From the front and sides of this septum numerous slender fibrous 
 cords and imperfect septa, called the trabeculae {septula testis) (Fig. 1080), are 
 given ofi^, which radiate toward the surface of the organ, and are attached to the 
 inner surface of the tunica albuginea. This scaffolding of connective tissue divides 
 the parenchyma (parenchyma testis) of the organ into a number of incomplete 
 spaces, which are somewhat cone-shaped, being broad at their bases at the sur- 
 face of the gland, and becoming narrower as they converge to the mediastinum. 
 The mediastinum supports the blood-vessels, lymphatics, and ducts of the testis 
 in their passage to and from the substance of the gland, and contains numerous 
 fine canals, into which open the very small tubules of the proper substance of 
 the testicle. 
 
 ' It is recorded that in the post-mortem examination of Sir Astley Cooper a minute funicular canal was found 
 on each side of the body. Sir Astley Cooper states that when a student he suffered from inguinal hernia ; prpb- 
 ablv this was of the congenital variety, and the canal found after death was the remains of the one down which 
 the" hernia travelled (Lancet, 1824, vol. ii. p. 116.). — Ed. of 15th English edition. 
 
1472 THE MALE ORGANS OF GENERATION 
 
 The Tunica Vasculosa (Fig. 1073). — The tunica vasculosa is the vascular layer -jI 
 the testis, and consists of a plexus of blood-vessels held together by a delicate 
 areolar tissue. It covers the inner surface of the tunica albuginea and the dif- 
 ferent septa in the interior of the gland, and therefore forms an internal invest- 
 ment to all the spaces of which the gland is composed. 
 
 Structure of the Testicle and Epidid3nms (Fig. 1080).— The glandular struc-' 
 ture of the testis consists of numerous lobules {lohvli testis). Their number, in a 
 single testis, is estimated by Berres at 250, and by Krause at 400. They differ in size 
 according to their position, those in the middle of the gland being larger and longer. 
 The lobules are conical in shape, the base of each being directed toward the circum- 
 ference of the organ, the apex toward the mediastinum. Each lobule is contained in 
 one of the intervals between the fibrous cords and vascular processes which extend 
 between the mediastinum testis and the tunica albuginea, and consists of from one 
 to mree or more minute convoluted tubes, which anastomose with each other, the 
 tubuli seminiferi contort!. The contorted tubes imite at the apex of the lobules and 
 form the straight tubes (tuhuli seminiferi recti). The straight tubes pass into the 
 mediastinum testis and form the network known as the rete testis of Haller (Fig. 
 1080). The rete testis is lined with flattened epithelium. The tubes are lined with 
 columnar ciliated epithelium. The efferent ducts (ducti efferentes testis) (Fig. 1080), 
 about twelve to fifteen in number, arise from the rete. The contorted tubes may 
 be separately unravelled by careful dissection under water, and may be seen to 
 commence either by free caecal ends or by anastomotic loops. The total number of 
 tubes is considered by Munro to be about 300 and the lengtii of each about sixteen 
 feet; by Lauth their number is estimated at 840, and their average length two feet 
 and a quarter. The diameter varies from -^^ to yir of an inch. The tubuli are 
 pale in color in early life, but in old age they acquire a deep-yellow tinge from 
 containing much fatty matter. Each tube consists of a basement layer, formed 
 of epithelioid cells united edge to edge, outside of which are other layers of 
 flattened cells arranged in interrupted laminae, which give to the tube an appear- 
 ance of striation in cross-section. The cells of the outer layers gradually pass 
 into the interstitial tissue. Within the basement-membrane are epithelial cells 
 arranged in several irregular layers, which are not always clearly separated , but 
 which may be arranged in three different groups. Among these cells may be seen 
 the spermatozoids in different stages of development. 1. Lining the basement- 
 membrane and forming the outer zone is a layer of cubical cells, with small 
 nuclei; these are known as the lining cells or spermatogonia. The nucleus of some 
 of them may be seen to be in the process of indirect division {karyokinesis) , and 
 in consequence of this daughter cells are formed, which constitute the second zone. 
 2. Within this first layer is to be seen a number of larger cells with clear nuclei, 
 arranged in two or three layers; these are the intermediate cells or spermatocytes. 
 Most of these cells are in a condition of karyokinetic division, and the cells which 
 result from this division form those of the next layer, the spermatoblasts or sperma- 
 tids. 3. The third layer of cells therefore consists of the spermatoblasts or sperma- 
 tids, and each of these, without further subdivision, becomes a spermatozoid. Tliey 
 are ill-defined granular masses of protoplasm, of an elongated form, with a nucleus 
 which becomes the head of the future spermatozoid. In addition to these three 
 layers of cells others are seen, which are termed the supporting cells, or cells of 
 Sertoli. They are elongated and columnar, and project inward from the basement- 
 membrane toward the lumen of the tube. They give off numerous lateral branches, 
 which form a reticulum for the support of the three groups of cells just described. 
 As development of the spermatozoids proceeds the latter group themselves around 
 the inner extremities of the supporting cells. The nuclear part of the sperma- 
 tozoid, which is partly embedded in the supporting cell, is differentiated to form the 
 head of the spermatozoid, while the cell protoplasm becomes lengthened out to 
 
THE TESTICLES I473 
 
 form the middle piece and tail, the latter projecting into the lumen of the tube. 
 Ultimately the heads are separated and the spermatozoids are set free. 
 
 Spermatogenesis. — The stages in the development of the spermatozoids are as 
 follows: The spermatogonia become enlarged to form the spermatocytes, and 
 each spermatocyte subdivides into two cells, and each of these again divides into 
 two spermatids or young spermatozoids, so that the spermatocyte gives origin to 
 four spermatozoids. 
 
 The process of spermatogenesis bears a close relation to that of maturation of 
 the ovum. The spermatocyte is equivalent to the immature ovum. It undergoes 
 subdivision, and ultimately gives origin to four spermatozoids, each of which con- 
 tains, therefore, only one-fourth of the chromatin elements of the nucleus of the 
 spermatocyte. In the process of maturation of the ovum its nucleus divides, one- 
 half being extended as the first polar body. The remaining half of the nucleus 
 again subdivides, one-half being extended as the second polar body. The portion 
 of the nucleus which is retained to form the female pronucleus of the now matured 
 ovum contains, therefore, only one-fourth of the chromatin elements of the 
 original nucleus, and thus the spermatozoid and the matured ovum, so far as 
 their nuclear elements are concerned, may be regarded as of the same morpho- 
 logical value. 
 
 The tubules are enclosed in a delicate plexus of capillary vessels, and are held 
 together by an intertubular connective tissue, which presents large interstitial 
 spaces lined by endothelium, which are believed to be the rootlets of lymphatic 
 vessels of the testis. 
 
 The Aberrant Ducts of the Epididymis {ductuli aherrantes) are tortuous and end 
 in blind extremities. The superior aberrant duct {ductus aherrans superior) is in the 
 globus major and joins the rete testis. The inferior aberrant duct (ductus aherrans 
 inferior) (Fig. 1080) is in the tail of the epididymis, and takes origin from the 
 duct of the epididymis or the seminal duct. It is a persistent canal of the Wolffian 
 body. It extends up the cord for two or three inches and terminates by a blind 
 extremity, which is occasionally bifurcated. It may be as much as fourteen 
 inches in length. Its structure is similar to that of the seminal duct. 
 
 The Seminal Duct or Vas Deferens {ductus deferens) (Figs. 1074, 1075, 1076, 1080, 
 1081, and 1118). — The seminal duct or vas deferens, the excretory duct of the testis, 
 is the continuation of the epididymis. Commencing at the lower part of the globus 
 minor, it ascentls along the posterior border of the testis and inner side of the epi- 
 didymis, and along the back part of the spermatic cord, through the inguinal canal 
 to the internal or deep abdominal ring. From the ring it curves around the outer 
 side of the internal epigastric artery and vein, crosses the external iliac vessels, and 
 descends into the pelvis at the side of the bladder; it arches backward and down- 
 ward to its base, crossing over the obliterated hypogastric artery and to the inner 
 side of the ureter. At the base of the bladder it lies between that viscus and the 
 rectum, nmning along the inner border of the seminal vesicle. Behind the bladder 
 it becomes enlarged and sacculated, forming the ampulla (ampulla ductus deferentis) 
 (Fig. 1081), and then, becoming narrowed at the base of the prostate, unites with 
 the duct of the seminal vesicle to form the ejaculatory duct (Fig. 1082) . From the 
 internal abdominal ring to the middle of the ampulla the seminal duct is beneath 
 the peritoneum. The vas deferens offers a hard and cord -like sensation to the 
 fingers; it is about two feet in length, of cylindrical form, and about a line and 
 a quarter in diameter. Its walls are dense, measuring one-third of a line, and its 
 canal is extremely small, measuring about half a line. 
 
 Structure. — The vas deferens consists of three coats: 1. An external or areolar 
 coat (tunica adventitia). 2. A muscular coat (tunica muscularis) , which in the 
 greater part of the tube consists of two layers of unstriped muscular fibre : an inner 
 layer of thin longitudinal fibres (stratum, internum) existing only at the beginning, 
 
 93 
 
1474 TJJE 31 ALE ORGANS OF GENERATION 
 
 a thick layer of circular fibres {stratum medium), and a thick external layer of 
 longitudinal fibres {stratum externum). 3. An internal or mucous coat {tunica 
 mucosa), which is pale, and arranged in longitudinal folds; its epithelial cells are 
 of the columnar variety. 
 
 Organ of Giraldes {paradidymis). — This term is applied to a small body of 
 rounded shape in the lower end of the spermatic cord, in front of the blood- 
 vessels. It consists of a small collection of minute vesicles and a small collection 
 of convoluted tubules. These tubes are lined with columnar ciliated epithelium, 
 and probably represents the remains of a part of the Wolffian body. 
 
 Surgical Anatomy. — Abnormalities in the descent and position of the testicle have been 
 discussed (p. 1462). The testicle may require removal for malignant disease, tuberculous disease, 
 cystic disease, in cases of large hernia testis, and in some instances of incompletely descended or 
 misplaced testicles. The operation of double castration has also been, during the last few years, 
 performed for enlargement of the prostate gland; for it has been found that removal of the tes- 
 ticles is followed by very rapid and often considerable diminution in the size of the prostate. 
 The operation is, however, one of severity, and is frequently followed by death in these cases, 
 performed, as it necessarily is, in old men. Reginald Harrison has proposed to substitute for it 
 excision of a portion of each vas deferens {vasectomy). The operation of castration is a com- 
 paratively simple one. An incision is made into the cavity of the tunica vaginalis from the 
 external ring to the bottom of the scrotum. The coverings are shelled off the organ, and the 
 mesorchium, stretching between the back of the testicle and the scrotum, divided. The cord is 
 then isolated, and an aneurism needle, armed with a double ligature, passed under it, as high 
 as is thought necessary, and the cord tied in two places, and divided between the ligatures. 
 Sometimes, in cases of malignant disease, it is desirable to open the inguinal canal and tie the 
 cord as near the internal abdominal ring as possible. 
 
 A collection of serous fluid in the sac of the vaginal tunic of the testicle is known as an ordinary 
 or testicular hydrocele. In congenital hydrocele a communication remains between the tunica 
 vaginalis testis and the peritoneal cavity. This communication should have closed during 
 development. In infantile hydrocele the tunica vaginalis and part of the funicular process are 
 distended with fluid, but the funicular process is closed above and the cavity of the hydrocele 
 does not communicate with the peritoneal cavity. In encysted hydrocele of the cord the funicular 
 process is closed above and below, but between these points is not obliterated. In funicular 
 hydrocele the funicular process is closed below and open above. Congenital hydrocele can 
 usually be cured by the application of a truss. This obliterates the upper end of the funicular 
 process, and the obliteration once begun may proceed to completion. If it does not, the condi- 
 tion has become an infantile hydrocele. An infantile hydrocele can usually be cured by multiple 
 punctures or tapping. The same is true of encysted hydrocele of the cord. In hydrocele of the 
 funicular process wear a truss for a time and then tap. In ordinary testicular hydrocele incise 
 and pack, or incise and suture, the cut edge of the parietal layer of the tunic to the skin, or extir- 
 pate the parietal layer of the tunic. A successful method is that of Longuet. He makes an 
 incision, pulls out the testicle, and allows all the coats except the skin to fall behind and make 
 a sheath for the cord. These coats are held behind by one catgut suture. A bed is made for 
 the testicle beneath the skin toward the septum of the scrotum. The testicle is rotated on its 
 long axis and placed in the bed, and the skin is sutured above it. This operation is known 
 as extraserous transposition. If a portion of bowel enters an open vaginal process the condition 
 is congenital hernia. 
 
 In infantile hernia the funicular process is closed above but not below, and the hernia descends 
 in a special sac back of the vaginal tunic. If the hernia pushes down on the vaginal process and 
 causes it to double on itself the condition is encysted infantile hernia. 
 
 The Semen and the Spermatozoids. — Semen consists of spermatozoids with liquids 
 and solids. Part of the semen comes from the testicles, most of it from accessory 
 glands — that is, from the glands of the seminal ducts, the seminal vesicles, the pros- 
 tate gland, and Cowper's glands. Semen is a viscid, whitish fluid, of alkaline 
 reaction and characteristic odor. It contains water and about 18 per cent, of 
 solid matter. In this solid matter are fat, cholesterin, lecithin, proteids, nuclein, 
 xanthin, chlorides, sulphates, and phosphates of sodium and potassium. Bott- 
 cher's crystals, which can be obtained from semen, are composed of phosphate of 
 spermine. Spermine is a nitrogenous substance. The fluid portion of semen 
 carries and probably nourishes the living cells known as spermatozoids. 
 
THE SEMINAL VESICLES 
 
 1475 
 
 The spermatozoids (Fig. 1081) are minute, thread-like bodies, which constitute the 
 essential elements of the semen. Each consists of a head, a middle piece or body, 
 and an elongated filament or tail. The head, on surface view, appears oval in shape, 
 but if seen in profile it is narrow and pointed at its free end. It represents the 
 modified nucleus of the spermatid, and consists chiefly of chromatin, and so 
 stains readily with nuclear reagents; it is covered by a thin cap of protoplasm. 
 The body is a short cylindrical or conical piece, inter- 
 vening between the head and tail, and is therefore 
 sometimes spoken of as the intermediate segment. 
 The tail is about four times the combined lengths of 
 the head and body; its terminal part is extremely fine, 
 and is named the end-piece. Contained within the 
 body and tail is an axial filament, surrounded, except 
 in the end-piece, by a thin layer of protoplasm; this 
 axial filament terminates just below the head in a 
 rounded knob or button. In virtue of their tails, 
 w'hich act as propellers, the spermatozoids, in the 
 fresh condition, are capable of free movement, and 
 if placed in favorable surroundings {e. g., in the 
 female passages) may retain their vitality for some 
 davs or even weeks. 
 
 .Head 
 
 3iiddle 
 ' piece 
 
 'Main piece 
 
 Head' 
 
 Middle 
 piece 
 
 of 
 the 
 tail 
 
 ..^End piece J 
 
 THE SEMINAL VESICLES (VESICULAE 
 SEMINALES) (Figs. 1082, 1083). 
 
 The seminal vesicles are two lobulated membran- 
 ous pouches placed between the base of the bladder 
 
 J ,1 , • • i! J.1 Fig. 1081. — Spermatozoid of man. 
 
 and the rectum, serving as reservoirs tor the semen, At the left a surface view is shown ; 
 and secreting a fluid to be added to the secretion of S;y^^o1.f4%!'af[er SiusV'"''- 
 the testicles. Each sac is somewhat pyramidal in 
 
 form, the broad end being directed backward and the narrow end forward toward 
 the prostate. It measures about two and a half inches in length, about five lines 
 in breadth, and two or three lines in thickness. They vaiy, however, in size, not 
 only in different individuals, but also in the same individual on the two sides. The 
 upper surface is in contact with the base of the bladder, extending from near the 
 termination of the ureters to the base of the prostate gland. The under surface 
 rests upon the rectum, from which it is separated by the recto- vesical fascia. 
 Their posterior extremities diverge from each other. Their anterior extremities 
 are pointed, and converge toward the base of the prostate gland, where each joins 
 with the corresponding seminal duct to form the ejaculatory duct. Along the 
 inner margin of each vesicle runs the enlarged and convoluted vas deferens. The 
 inner border of the vesicle and the corresponding seminal duct form the lateral 
 boundaries of a triangular space, limited behind by the recto-vesical peritoneal 
 fold; the portion of the bladder included in this space rests on the rectum. 
 
 Each vesicle consists of a single tube, coiled upon itself and j^iving off several 
 irregular caecal diverticula (Fig. 1082) , the separate coils, as well as the diverticula, 
 being connected together by fibrous tissue. When uncoiled this tube is about the 
 diameter of a quill, and varies in length from four to six inches; it terminates pos- 
 teriorly in a cul-de-sac; its anterior extremity becomes constricted into a narrow 
 straight duct, the excretory duct (ductus excretorius) (Fig. 1083), which joins vvith 
 the corresponding seminal duct, and forms the ejaculatory duct. 
 
 The Ejaculatory Ducts (ductus ejaculatorii) (Fig. 1083). — The ejaculatory ducts 
 are two in number, one on each side. Each duct is formed by the junction of the duct 
 of the seminal vesicle with the seminal duct. Each duct is about three-quarters of 
 
1476 
 
 THE 3fALE ORGANS OF GENERATION 
 
 MUSCULAR 
 TUNIC 
 
 VA3 
 
 DCFEi^ENS 
 
 an inch in length; it commences at the base of the prostate, and runs forward and 
 downward between the middle and lateral lobes of that gland, and along the side of 
 
 the sinus pocularis, to termi- 
 nate by a separate slit-like 
 orifice close to or just within 
 the margins of the sinus. The 
 ductsdiminish insizeand also 
 converge toward their termi- 
 nation. 
 
 Structure. — The seminal 
 vesicles are composed of three 
 coats: an external or areolar 
 {tunica adventitia) ; a middle 
 or muscular coat {tunica mus- 
 cM/an'.s), which is thinner than 
 m the seminal duct, and is 
 arranged in two layers, an 
 outer, longitudinal, and inner, 
 circular; an internal or mucous 
 coat (tunica mucosa), which 
 is pale, of a whitish-brown 
 color, and presents a delicate 
 reticular structure, like that 
 seen in the gall-bladder, but 
 the meshes are finer. The 
 epithelium is columnar. 
 
 The coats of the ejacula- 
 tory ducts are extremely thin. 
 They are: an outer fibrous 
 
 COWPER'S 
 GLANDS 
 
 EXCRETORY 
 DUCT 
 
 Fig. 1082. — The urinary bladder, distended, with surrounding struc- 
 tures, viewed from behind. (Spalteholz.) 
 
 layer, which is almost entirely 
 lost after the entrance of the 
 duct into the prostate; a 
 layer of muscular fibres, con- 
 sisting of an outer thin circu- 
 lar and an inner longitudinal 
 layer; and the mucous mem- 
 brane. 
 
 Vessels and Nerves. — The 
 arteries supplying the vesic- 
 ulae seminales are derived 
 from the middle and inferior 
 vesical and middle haemor- 
 rhoidal. The veins and lym- 
 phatics accompany the arte- 
 ries. The lymphatics anas- 
 tomose on the surface of the 
 vesicle. The trunks from this 
 network anastomose with the 
 lymphatics of the bladder 
 and prostate, and [)ass to the 
 external and internal iliac glands. The nerves are derived from the pelvic plexus. 
 
 Surgical Anatomy. — The vesiculae seminales are often the seat of an extension of the dis- 
 ease in cases of tuberculosis of the testicle, and should always be examined through the rectum 
 before coming to a decision with regard to castration in this affection. The vesicles have been 
 deliberately extirpated for local tuberculosis. In gonorrhoea the seminal vesicles may become 
 acutely inflamed {acute seminal vesiculitis). Chronic seminal vesiculitis may follow the acute 
 form or may arise insidiously during gonorrhoea. 
 
 XCRETORY 
 DUCT 
 
 EJACULATORY 
 DUCT 
 
 SINUS 
 POCULARIS 
 
 Fig. 1083. — The ejaculatory ducts viewed from in front and above. 
 (Spalteholz.) 
 
THE FEMLE ORGANS OE GENERATION. 
 
 EXTERNAL ORGANS (PARTES GENITALES EXTERNAE MULIEBRES). 
 
 THE external organs of generation in the female are: the mons Veneris, the 
 labia majora and minora, the clitoris, the meatus urinarius, and the orifice of 
 the vagina. The term vulva {pudendum muliebre), as generally applied, includes 
 all of these parts. 
 
 FALLOPIAN TUBE 
 
 INFUNDIBULUM OF 
 FALLOPIAN TUBE 
 
 PAVILION OF. 
 FALLOPIAN TUBE 
 
 ORGAN OF 
 ROSENMULLER 
 
 VESTIBULE OF VAGINA 
 
 Fig. 1084.— Diagrammatic representation of the female reproductive organs and their relations to the bladder 
 
 and urethra, lateral view. (Toldt.) 
 
 THE MONS VENERIS (MONS PUBIS) (Figs. 1085, 1086). 
 
 The mons Veneris is the rounded eminence in front of the pubic symphysis, 
 formed by a collection of fatty tissue beneath the integument. It becomes covered 
 with hair at the time of puberty. 
 
 THE LARGE LIPS OR LABIA MAJORA (LABIA MAJORA PUDENDI) 
 
 (Figs. 1085, 1086, 1087). 
 
 The large lips or labia majora are two prominent longitudinal cutaneous folds 
 extending downward from the mons Veneris to the anterior boundary of the 
 perinseum, and enclosing the common urino-sexual opening. Each labium ma jus 
 {labium majus pudendi) has two surfaces, an outer, which is pigmented and 
 
 (1477) 
 
1478 
 
 THE FEMALE ORGANS OF GENERATION 
 
 covered with strong, crisp hairs; and an inner, which is smooth and is beset with 
 large sebaceous follicles and is continuous with the genito-urinary mucous tract; 
 between the two there is a considerable quantity of areolar tissue, fat, and a 
 tissue resembling the dartos of the scrotum, besides vessels, nerves, and sweat and 
 sebaceous glands. Between the labia majora is the pudendal slit {rima pudendi). 
 The labia are thicker in front, where they form by their meeting the anterior 
 commissure (commissura labiorum anterior). Posteriorly they are not really 
 joined, but appear to become lost in the neighboring integument, terminating 
 close to, and nearly parallel with, each other. Together with the connecting skin 
 between them, they form the posterior commissure (commissura labiorum posterior), 
 or posterior boundary of the vulval orifice. The interval between the posterior 
 
 MONS VENERIS 
 
 PREPUCE OF 
 CLITORIS 
 
 POSTERIOR 
 
 COMMISSURE- 
 
 OF VULVA 
 
 ANTERIOR 
 COMMISSURE 
 
 PERINEUM 
 
 POST-ANAL. 
 FURROW 
 
 Fig. 1085. — The female pudendum or vulva with the labia majora. (Toldt.) 
 
 commissure and the anus, about an incli to an inch and a quarter in length, 
 constitutes the obstetric perinseum. The fourchette (frenulum labiorum pudendi) 
 (Fig. 1086) is the anterior edge of the perinseum, and between it and the hymen 
 is a depression, the fossa navicularis of the vulva or the vestibule of the vagina (fossa 
 navicularis vestibuli vaginae) (Fig. 1086). The labia majora correspond to the 
 scrotum in the male. 
 
 THE SMALL LIPS, NYMPHAE OR LABIA MINORA (LABIA MINORA PUDENDI) 
 
 (Figs. 1085, 1086, 1087). 
 
 The small lips are two small cutaneous folds, situated within the labia 
 majora, and extending from the clitoris obliquely downward, outward, and back- 
 
THE CLITORIS 
 
 1479 
 
 ward for about an inch and a half on each side of the orifice of the vagina, 
 between which and the labia majora they are lost in women who have borne 
 children. In women who have not borne children they unite behind and usually 
 form a fold {frenulum lahiorum piuiendi). Behind this fold is the fossa navicularis. 
 Anteriorly, each lip divides into two limbs. The external limbs unite over the 
 
 VVONS VENERIS 
 
 ORIFICE % 
 OF VAGINA 
 
 rossA 
 
 NAVICULARIS 
 
 FiQ. 1086. — The vulva. External female organs of generatign. 
 
 glans clitoris to form the prepuce of the clitoris (praepuiium clitoridis) (Fig. 1086). 
 The internal limbs meet and unite beneath the glans clitoris and are attached 
 to the under surface of the glans to form the fraenum (frenulum clitoridis). The 
 nymphae are really modified skin. Their internal surfaces have numerous seba- 
 ceous follicles (glandulae vestibidares minores). 
 
 THE CLITORIS (Figs. 1086, 10S7, 1089). 
 
 Tlie clitoris is an erectile structure analogous to the corpora cavernosa of the 
 penis. It is situated beneath the anterior commissure, partially hidden between 
 the anterior extremities of the labia minora. It is connected to the rami of the 
 OS pubis. It consists of two corpora cavernosa, each of which {corpus cavernosum 
 
1480 
 
 THE FEMALE ORGAN^S OF GENERATION 
 
 clitoridis) passes behind into the eras {cms clitoridis). Each crus is attached 
 to the ramus of the pubis and ischium; the body (corpus clitoridis) is short 
 and concealed beneath tlie labia; the free extremity (glans clitoridis) is a small 
 rounded tubercle, consisting of spongy erectile tissue, and is highly sensitive. It 
 is provided, like the penis, with a suspensory ligament (ligamentum suspensorium 
 clitoridis), and with two small muscles, the Erectores clitoridis, which are inserted 
 into the crura of the clitoris. The two corpora cavernosa are composed of erectile 
 
 POSTERIOR 
 Vo R N I X 
 
 ANTERIOR 
 FORNIX 
 
 Fig. 1087. 
 
 -Sagittal section of the lower part of a female trunk, right segment, 
 intestine. (Testut.) 
 
 SM. INT.. small 
 
 tissue enclosed in a dense layer of fibrous membrane, united together along their 
 inner surfaces by an incomplete fibrous pectiniform septum. 
 
 To each crus of the clitoris goes a branch from the internal pudic artery, which 
 branch is known as the deep artery of the clitoris. The dorsal arteries of the clitoris 
 (arteriae dorsalis clitoridis) from the internal pudic send branches to the glans. 
 The nerves of the clitoris consist of the dorsal nerves of the clitoris from the 
 internal pudic nerve and sympathetic fibres from the hypogastric plexus. 
 
THE HYMEN 
 
 1481 
 
 THE VESTIBULE (VESTIBULUM VAGINAE). 
 
 The vestibule of English and American writers is a triangular smooth surface 
 between the clitoris and the entrance of the vagina (Fig. 1086). It is bounded 
 on each side by the nymphae. The vestibule of the vagina is understood by the 
 Germans to be the space at the sides of the vaginal orifice enclosed by the labii 
 minora, as well as the space in front of the vagina.^ 
 
 Seclum 
 
 Ovary, 
 
 Fig. 1088. — Female pelvic organs in situ, seen from above. (Bardeleben.) 
 
 rail- 
 
 ORIFICE OF THE URETHRA OR THE MEATUS URINARIUS (ORIFICIUM 
 URETHRAE EXTERNUM) (Figs. 1086, 1089). 
 
 The external orifice of the urethra or the meatus urinarius is situated at the 
 back part of the vestibule, about an inch below the clitoris and near the margin 
 of the vagina, surrounded by a prominent elevation of the mucous membrane. 
 Below the meatus urinarius is the orifice of the vagina (orificium vaginae) (Fig. 1086) , 
 more or less closed in the virgin by a membranous fold, the hymen (Fig. 1086). 
 
 THE HYMEN (Figs. 1086, 1090). 
 
 The hymen varies much in shape. Its commonest form is that of a ring, 
 generally broadest posteriorly; sometimes it is represented by a semilunar fold, 
 with its concave margin turned toward the pubes. A complete septum stretched 
 across the lower part of the vaginal orifice is called an imperforate hymen. Occa- 
 
 1 See note 89 by Dr. M. Eden Paul, in vol. iv. of Toldt's Atlas. 
 
1482 
 
 THE FEMALE ORGANS OF GENERATION 
 
 sionally the hymen is cribriform, or its free margin forms a membranous fringe, 
 or it may be entirely absent. It may persist after copulation, so that it cannot 
 be considered as a test of virginity. After rupture of the hymen the small rounded 
 elevations known as the canmculae myrtiformes are found as the remains of the 
 structure. 
 
 GLANDS OF BARTHOLIN (GLANDULA VESTIBULARIS MAJOR 
 [BARTHOLINIp (Fig. 1089). 
 
 On each side of the posterior part of the commencement of the vagina is a 
 round or oblong body, of a reddish-yellow color, and of the size of a horse-bean, 
 
 SUSPENSORY LIGAMENT 
 OF CLITORIS 
 
 CLANS OF 
 CLITORIS 
 
 SPHINCTER 
 VAGINAE 
 MUSCLE 
 
 ERECTOR 
 
 CLITORIDIS 
 
 MUSCLE 
 
 ORIFICE OF 
 
 URETHRA 
 
 LABIA, 
 MINORA 
 
 CARUNOULAE 
 MYRTIFORMES 
 SPHINCTER 
 VAGINAE- 
 MUSCLE 
 
 TRANSVERSE 
 PERINEI 
 MUSCLE 
 
 EXCRETORY 
 DUCT 
 
 G LA N D OF 
 BARTHOLIN 
 
 OMPRESSOR 
 URETHRAE MUSCLE 
 
 TRANSVERSE 
 PERINEI MUSCLE 
 
 Fig. 1089. — The female external organs of generation dissected. (Spalteholz.) 
 
 analogous to Cowper's gland in the male. It is called the gland of Bartholin, the 
 gland of Duvemey, the vulvo-vaglnal gland or the suburethral gland (glandula vestibu- 
 laris major [Bartholini]). Bartholin's gland lies partly in the inferior or anterior 
 leaf of the triangular ligament. The posterior portion of the bulbous vestibuli 
 and the Bulbo-cavernous muscle partly cover it. Each gland opens by means of 
 a long single duct immediately external to the hymen, in the angle or groove 
 between it and the nympha (Fig. 1090). 
 
THE VAGINA 
 
 1483 
 
 CRESCENTIC FRrNGED BILABIAL BIPERFORATE 
 
 Fig. 1090. — Varieties of hymen. (Testut, after Roze.) 
 
 CRIBRIFORM 
 
 THE VAGINAL BULB OR BULB OF THE VESTIBULE (BULBUS VESTIBULI) 
 
 (Fig. 1089). 
 
 Extending from the clitoris, along either side of the vestibule (the term vestibule 
 being used according to the German nomenclature) (p. 1481), and lying a 
 little behind the nymphae, are two large oblong masses, about an inch in length, 
 consisting of a plexus of veins enclosed in a thin layer of fibrous membrane. 
 This plexus is superficial to the triangular ligament, and it is covered externally 
 and inferiorly by the Bulbo-cavernous muscle. These bodies are narrow in front, 
 rounded below, and are connected with the crura of the clitoris and rami of the 
 pubes; they are termed by Kobelt the bulbi vestibuli, and he considers them 
 analogous to the bulb of the corpus spongiosum in the male. Immediately in 
 front of these bodies is a smaller venous plexus, continuous with the bulbi ves- 
 tibuli behind and the glans clitoridis in front; it is called by Kobelt the pars inter- 
 media, and is considered by him as analogous to that part of the body of the corpus 
 spongiosum which immediately succeeds the bulb. The bulb receives its blood 
 from the artery of the bulb {arteria bulbi vestibuli), which is a branch of the internal 
 pudic. 
 
 INTERNAL ORGANS (PARTES GENITALES INTERNAE MULIEBRIS). 
 
 The internal organs of generation are — the vagina, the uterus and its appendages, 
 the Fallopian tubes, the ovaries and their ligaments. 
 
 THE VAGINA (Figs. 1084, 1087, 1093). 
 
 The vagina extends from the vulva to the uterus. It is situated in the cavity 
 of the pelvis, behind the bladder and in front of the rectum. Its direction is 
 curved upward and backward, at first in the line of the pelvic outlet, and afterward 
 in that of the axis of the cavity of the pelvis. Its walls are ordinarily in contact, 
 and its usual shape on transverse section is that of an H, the transverse limb 
 being slightly curved forward or backward, whilst the lateral limbs are somewhat 
 convex toward the median line. Its length is about two and a half inches along 
 its anterior wall (paries anterior), and three and a half inches along its posterior 
 wall {paries posterior). It is constricted at its commencement, and becomes 
 dilated medially, and narrowed near its uterine extremity; it surrounds the vaginal 
 
1484 THE FEMALE ORGANS OF GENERATION 
 
 portion of the cervix uteri, a short distance from the os, its attachment extending 
 higher up on the posterior than on the anterior wall of the uterus (Fig. 1096). 
 
 The vaginal axis forms with the uterine axis an obtuse angle opening forward, 
 and, as a rule, a little greater than a right angle (Fig. 1094). The fact that the 
 attachment of the vagina to the cervix is above the external os causes the formation 
 of a recess between the cervix and vaginal wall, known as the vaginal fornix {fornix 
 vaginae). This recess is deeper posteriorly than it is laterally or in front. The 
 anterior portion of the fornix is called the anterior fornix (Fig. 1087). The pos- 
 terior portion is called the posterior fornix (Fig. 1087). The right and left portions 
 are called the right and left lateral fomices. The vagina opens into the uro-genital 
 cleft, between the labia minora and back of the urethra and clitoris. It opens by 
 the vaginal orifice (orijicium vaginae) (Fig. 1086). In the virgin the opening is 
 partly closed by the hymen (p. 1481). After rupture of the hymen atrophied 
 fragments of the torn membrane remain around the vaginal orifice, and are 
 known as the carunculie myrtiformes (carunculae hymenales). 
 
 Relations (Fig^. 1084 and 1087). — The upper part of the anterior wall of the 
 vagina is in relation with the base of the bladder, being separated from that viscus 
 by lax connective tissue. Lower down the middle line of the anterior wall and 
 closely joined to it is the urethra. The upper part of the posterior wall, near 
 the middle line, is covered for a quarter of an inch or more with peritoneum, 
 which forms the anterior wall of the depths of the recto-vaginal pouch of perito- 
 neum or pouch of Douglas {excavatio rectouterina [Douglasi]) (Fig. 1096), between 
 the uterus and vagina and the rectum. The portion of the posterior wall below 
 the level of the pouch of Douglas is placed close to the rectum, a layer of pelvic 
 fascia intervening. As the vaginal orifice is neared, the rectum and vagina 
 separate, and interposed between them is a mass of fibro-fatty tissue called the 
 perinseum or perineal body. Its sides are enclosed between the Levatores ani 
 muscles. The ureter toward its termination (Fig. 1097) lies near the lateral wall 
 of the vagina, passing at this point in a direction downward, inward, and slightly 
 forward to reach the bladder. The vagina near its termination passes through 
 the triangular ligament, and upon its sides are the bulbs of the vestibule, the 
 glands of Bartholin, and the Bulbo-cavernous muscle. 
 
 Structure. — The vagina consists of an internal mucous lining, of a muscular coat, 
 and between the two of a layer of erectile tissue. 
 
 The Mucous Membrane (tunica mucosa) (Fig. 1093). — The mucous membrane is 
 continuous above with that lining the uterus. Its inner surface presents, along 
 the anterior and posterior walls, a longitudinal ridge or raphd, called the rugous 
 columns of the vagina (columna rugarum anterior et posterior). The anterior 
 column extends downward as far as the external orifice of the urethra, forming the 
 carina urethralis vaginae. Numerous transverse ridges or rugae {rugae vaginales) 
 extend outward from the raph^ on either side. These rugae are divided by fur- 
 rows of variable depth, giving to the mucous membrane the appearance of being 
 studded over with conical projections or papillae; they are most numerous near 
 the orifice of the vagina, especially in females before parturition. The epithelium 
 covering the mucous membrane is of tlie squamous variety. The submucous tissue 
 is very loose and contains numerous large veins, which by their anastomoses 
 form a plexus, together with smooth muscular fibres from the muscular coat; it 
 is regarded by Gussenbauer as an erectile tissue (see p. 1485). It contains a 
 number of mucous crypts, but no true glands. 
 
 The Muscular Coat {tunica muscularis). — The muscular coat consists of two 
 layers: an external longitudinal, which is far the stronger, and an internal circular 
 layer. The longitudinal fibres are continuous with the superficial muscular fibres 
 of the uterus. The strongest fasciculi are those attached to the recto-vesical fascia 
 on each side. The two layers are not distinctly separable from each other, but 
 
THE VAGINA 
 
 1485 
 
 are connected by oblique decussating fasciculi which pass from the one layer to 
 the other. Above the triangular ligament the fibres are non-striated ; in the region 
 of the ligament they show striations. In addition to this the vagina at its lower 
 end is surrounded by a band of striped muscular fibres, the sphincter vaginae 
 (p. 461). External to the muscular coat is a layer of connective tissue containing 
 a large plexus of blood-vessels. 
 
 The Erectile Tissue. — The erectile tissue consists of a layer of loose connective 
 tissue situated between the mucous membrane and the muscular coat; embedded 
 in it is a plexus of large veins, and numerous bundles of unstriped muscular fibres 
 derived from the circular muscular layer. The arrangement of the veins is 
 similar to that found in other erectile tissues. 
 
 EXTERNAL 
 ILIAC GLANDS 
 
 INTERNAL 
 ILIAC GLANDS 
 
 LATERAL 
 SACRAL GLANDS 
 
 AFFERENTS 
 TO EXTERNAL 
 ILIAC GLANDS 
 
 AFFERENTS 
 TO INTERNAL 
 LIAC GLANDS 
 
 RETROVAGINAL 
 NODULES 
 
 Fig. 1091. — The lymphatics of the vagina. Schematic. (Poirier and Charpy.) 
 
 Blood-vessels, Nerves, and Lymphatics, — The arteries of the vagina are branches 
 of the vesico-vaginal artery; the vaginal branch of the uterine artery (p. 687), and 
 branches of the internal pudic and middle haemorrhoidal. The veins form an abund- 
 ant plexus around the wall of the vagina and pass to the internal iliac veins. The 
 lymphatics (Fig. 1091) arise from the two communicating networks, one of which is 
 below the mucous membrane, the other in the muscular wall. There is a third net- 
 work around the vaginal wall, from which the collectors arise. The trunks from the 
 upper third of the vagina pass to the external iliac glands ; those from the middle 
 third pass to the internal iliac glands ; those from the lower third terminate in the 
 glands at the promontory of the sacrum or in the lateral sacral glands.^ The nerves 
 come from the third and fourth sacral nerves and from the utero-vaginal and 
 vesical plexuses of the ssrmpathetic. 
 
 1 The Lymphatics. By Poirier, Cuneo, and Delamare. Tran.slated and edited by Cecil H. Leaf. 
 
1486 
 
 THE FEMALE ORGANS OF GENERATION 
 
 THE WOMB OR UTERUS (Figs. 1084, 1087, 1088, 1092, 1097). 
 
 The uterus is the organ of gestation, receiving the fecundated ovum in its cavity, 
 retaining and supporting it during the development of the foetus, and becoming 
 the principal agent in its expulsion at the time of parturition. It is a hollow 
 muscular organ. The non-pregnant uterus is contained in the cavity of the pelvis 
 betvi^een the bladder and rectum (Figs. 1087 and 1088). It is rarely placed exactly 
 in the mid-line, but inclines to one side or the other, more often to the left than 
 to the right. The walls of the organ are extremely thick. The uterus is movable 
 as a whole, and the body of the uterus is movable upon the neck. Its position 
 varies with the condition of adjacent parts, especially the bladder and rectum. 
 The cervix is more firmly fixed than the body and fundus, and hence the latter 
 vary more in position than the former. Normally, in an erect individual, with the 
 bladder and rectum empty, the external os is at the level of the upper surface of 
 the pubic symphysis (Fig. 1084) and in a frontal plane passing through the ischiatic 
 spines. The long axis of the uterus is directed forward and upward (Fig. 1084), 
 and is angled where the body and cervix join. Hence, normally, with the bladder 
 
 MESOVARIUM 
 
 ANTERIOR ISTHMUS . 
 BORDER OF FALLOPIAN 
 OVARY TUBE 
 
 FALLOPIAN 
 TUBE 
 
 OVARIAN 
 FIMBRIA 
 
 ABDOMINAL 
 ORIFICE 
 
 LIGAMENT 
 OF OVAHV 
 
 OF OVARY UTERINE 
 
 EXTREMITY 
 
 OF OVARY 
 
 VAGINAL 
 PORTION OF 
 CERVIX 
 
 ANTERIOR LIP 
 OF CERVIX 
 
 Fig. 1092.— The uterus, the left Fallopian tube and the left ovary in their connection with the broad ligament of 
 the uterus, which has been fully unfolded. Seen from behind. From a virgin, aged nineteen years. (Toldt.) 
 
 empty, the uterus is anteverted and anteflexed. When the bladder fills the ante- 
 version and anteflexion are almost abolished. If the bladder is overdistended and 
 the rectum is empty, the uterus is pushed strongly backward, so that its long axis 
 corresponds to the long axis of the vagina; in other words, it is retroverted. 
 
 In the virgin state it is pear-shaped, flattened from before backward, and 
 is retained in its position by the round and broad ligaments on each side, and 
 projects into the upper end of the vagina below (Figs. 1092 and 1093). Its upper 
 end, or base, is directed upward and forward; its lower end, or apex, downward 
 and backward, in the line of the axis of the inlet of the pelvis. It therefore 
 forms an angle with the vagina, since the direction of the vagina corresponds to 
 the axis of the cavity and outlet of the pelvis. The non-pregnant adult uterus 
 measures about three inches in length, two inches in breadth at its upper part, and 
 nearly an inch in thickness, and it weighs from an ounce to an ounce and a half. 
 
 It consists of two parts (Fig. 1092) : (1) An upper and larger portion, consisting 
 of the body and fundus. This portion is flattened from before backward. (2) A 
 lower, smaller, and cylindrical portion, the cervix. 
 
THE WOMB OB UTEBUS 
 
 1487 
 
 The Fundus (fundus uteri) (Fig. 1092). — The fundus is the upper broad 
 extremity of the uterus. If a line is drawn from the uterine opening of one 
 Fallopian tube to the other, the portion above the line is the fundus. The 
 fundus is directly continuous with the body. 
 
 The Body of the Uterus (corpus uteri) (Fig. 1092). — The body of the uterus is 
 below and continuous with the fundus. In outline, when seen from in front or 
 behind, it resembles a triangle, the base being above and the point being absent. 
 
 GLANS 
 CLITORIDIS 
 
 EXTERNAL 
 ORIFICE OF 
 URETHRA 
 
 PARA-URETHRAL 
 DUCT 
 
 URETHRAL 
 RIDGE 
 
 POSTERIOR 
 VAGINAL 
 COLUMN 
 
 ANTERIOR 
 VAGINAL 
 COLUMN 
 
 TRANSVE 
 RU 
 
 VAGINAL 
 
 PORTION OF 
 
 CERVIX 
 
 SUPRAVAGINAL 
 PORTION OF- 
 CERVIX 
 
 Fig. 1093. — The female external genital organs of a virgin attached to the vagina, which has been isolated 
 anci opened, and a portion of the cervix uteri. (Toldt.) 
 
 The anterior surface (fades vesicalis) passes on each side into the posterior surface 
 (fades intestinalis) by the lateral border (margo lateralis) . 
 
 The body gradually narrows from the fundus to the neck. Its anterior surface is 
 so slightly rounded as to appear flattened. It is covered by peritoneum (Fig. 1092), 
 which becomes separated from it at its union with the cervix, in order to form the 
 utero-vesical pouch, which lies between the uterus and bladder (Fig. 1096). Its pos- 
 terior surface is more rounded than the anterior, being convex transversely. It is 
 
1488 
 
 THE FEMALE OBGAJ)^^. OF GENERATION 
 
 covered by peritoneum throughout (Fig. 1097), and separated from the rectum by 
 some convolutions of the small intestine (Fig. 1087). The peritoneum which covers 
 the posterior surface forms most of the anterior wall of Douglas's cul-de-sac 
 (Figs. 853, 1096 and 1097, and p. 1248). Its lateral margins (Figs. 1092 and 
 1097) are concave, and each gives attachment to the Fallopian tube above, the 
 round ligament below, and in front of this the ligament of the ovary; these 
 structures lie between the layers of the broad ligament. The division between the 
 
 GARTNER'S 
 "DUCT 
 
 Fig. 1094. — The parovarium. The mesosalpinx is partly removed. (Poirier and Charpy.) 
 
 the body and the cervix is indicated externally by a slight constriction, and by the 
 reflection of the peritoneum from the anterior surface of the uterus on to the bladder, 
 and internally by a narrowing of the canal called the internal os (Fig. 1095). 
 
 The Neck or Cervix Uteri (Figs. 1092 and 1095). — The neck or cervix uteri is 
 the lower constricted segment of the uterus; around its circumference is attached 
 the upper end of the vagina (Figs. 1087, 1092, 1093, and 1096), which extends 
 upward a greater distance behind than in front. The neck is spindle-shaped in 
 those who have had no children, cylindrical in those who have had children. 
 
 UTERINE 
 
 ORIFICE OF 
 
 FALLOPIAN TUBE 
 
 ABDOMINAL 
 ORIFICE 
 
 HYDATID OF 
 MORGAQNI 
 
 UTEROVAGINAL 
 
 VENOUS 
 
 PLEXUS 
 
 \VAGINAL 
 FORNIX 
 OS UTERI 
 EXTERNUM 
 
 Fig. 1095. — The uterus and the right Fallopian tube opened from behind. (Toldt.) 
 
 The Supravaginal Portion (por^io supravaginalis[cervicis]) (Figs. 1092 and 1096).— 
 The supravaginal portion is not covered by peritoneum in front; a pad of cellular 
 tissue is interposed between it and the bladder. Behind, the peritoneum is extended 
 over it. 
 
 The Vaginal Portion (portio vaginalis cervicis) (Figs. 1087, 1092, 1093, and 1096). 
 — The vaginal portion is the lower end projecting into the vagina. It is round or 
 
THE WOMB OR UTERUS 
 
 1489 
 
 elliptical, the long axis of the elliptical figure being transversely placed. On its 
 surface is a small aperture, the external mouth of the womb, or os uteri, or external os 
 (orificium uteri externum) (Figs. 1092, 1093, 1095, and 1096), generally circular in 
 shape, but sometimes oval or almost linear. If a woman has borne children the 
 opening is transverse and the margins are irregular. The margin of the opening is, 
 in the absence of past parturition or 
 disease, quite smooth. This aperture 
 divides the vaginal portion of the cervix 
 into two lips, an upper or posterior lip 
 (labium posterius) and a lower or an- 
 terior lip (labium anierius). On each 
 side of the cervix and upper portion of 
 the vagina there is a space containing 
 bloodvessels and filled with loose cellu- 
 lar tissue. This loose tissue passes 
 upward between the layers of the broad 
 ligament and is called parametrium. 
 On each side of the cervix and three- 
 quarters of an inch away is the termi- 
 nal portion of thecorresponding ureter. 
 Folds and Ligaments. — The liga- 
 ments of the uterus are eight in number. Some are simple folds of peritoneum; 
 others contain connective tissue and muscle. The ligaments are as follows : one 
 
 RECTAL PERITONEUM 
 CTOVAGINAL POUCH 
 
 ERIOR AND POS- 
 IIOR LAYERS OP 
 OAD LIGAMENT 
 
 VESICAL 
 'ERITONEUM 
 
 UTERO-VESICAL 
 POUCH 
 
 SUPRA-VAGINAL 
 PORTION OF 
 CERVIX 
 
 Fig. 1096. — The cervix uteri and upper end of the 
 vagina, .showing their relations to the peritoneum. 
 Diagrammatic. (Testut.) 
 
 ROUND 
 
 LIGAMENT. 
 
 al iliac 
 tery. 
 
 artery. 
 Fig. 1097. — Douglas's pouch. (From a preparation in the Museum of the Royal College of Surgeons of England.) 
 
 anterior, one posterior, two lateral or broad, two sacro-uterine — all these being formed 
 of peritoneum — and, lastly, two round ligaments. 
 
 94 
 
1490 
 
 THE FEMALE ORGANS OF GENERATION 
 
 The Anterior Ligament or the Utero-vesical Fold or Vesico-uterine Ligament is 
 reflected on to the bladder from the front of the uterus, at the junction of the 
 cervix and body. It forms the utero-vesical pouch (excavatio vesicouterina) (Figs. 
 1096 and 1097). 
 
 The Posterior Ligament or the Recto-vaginal Fold passes from the posterior wall 
 of the uterus over the upper fourth of the vagina, and thence on to the rectum and 
 sacrum. It thus forms a pouch, called the recto-vaginal pouch or Douglas's pouch 
 (Figs. 853, 1096, and 1097), the boundaries of which are, in front, the posterior 
 wall of the uterus, the supravaginal portion of the cervix, and the upper fourth of 
 the vagina; behind, the rectum and sacrum; above, the small intestine; and, 
 laterally, the folds of Douglas or recto-uterine folds, which contain the sacro- 
 uterine ligaments. 
 
 The Lateral or Broad Ligament (ligamenhim latum uteri) (Figs. 1088, 1098, 
 and 1104) is a peritoneal fold which passes from each side of the uterus to the 
 lateral wall of the pelvis as high as the external iliac vein. From this region 
 comes the peritoneal fold called the suspensory ligament of the ovary (Fig. 1088) . 
 The two broad ligaments form a septum across the pelvis, which divides that 
 cavity into two portions. In the anterior part are contained the bladder, urethra, 
 and vagina; in the posterior part, the rectum. In the uterus normally placed the 
 anterior surface of the broad ligament faces forward and downward, and the pos- 
 terior surface faces upward and backward. The ligament is more nearly vertical 
 
 GRAAFIAN 
 FOLLICLE 
 
 MCSOMCTRIUM' 
 
 GRAAFIAN 
 FOLLICLE 
 
 STROMA or 
 
 Fig. 1098.— The broad ligament of the uterus, with 
 the mesovarium, the mesosalpinx, the ovary, and 
 the Fallopian tube in transverse section. (Toldt.) 
 
 Fig. 1099. — Longitudinal section through the ovary. 
 CToldt.) 
 
 at its pelvic insertion. The two layers of the broad ligament are mostly near 
 to each other, to the side and below they separate and pass into the peritoneum 
 of the lateral pelvic wall, the bladder and the rectum. Between the two layers 
 of each broad ligament are contained — (1) the Fallopian tube superiorly; (2) the 
 round ligament; (3) the ovary and its ligament; (4) the parovarium or organ of 
 Rosenmiiller, and the paro-ophoron ; (5) loose connective tissue, which is called 
 parametrium; (6) unstriped muscular fibre; and (7) blood-vessels and nerves. The 
 Fallopian tube is in the free edge of the broad ligament, and is contained in a 
 special fold, which is attached to the part of the ligament near the ovary, and is 
 known by the name of the mesosalpinx (Figs. 1094, 1098, and 1104). If the 
 mesosalpinx is spread out, it is seen to be roughly triangular; the base of the 
 triangle is outward, the apex at the upper and outer angle of the uterus; the 
 upper boundary is the Fallopian tube, and the lower boundary is the ovary and 
 its ligament. Between the two layers of the mesosalpinx are the parovarium and 
 the paro-ophoron. Between the fimbriated extremity of the tube and the lower 
 attachment of the broad ligament is a concave rounded margin, called the infun- 
 dibulo-pelvic ligament (Fig. 1103). 
 
THE WOMB OB UTEBU8 I49I 
 
 The ovary lies in a depression of the broad ligament called the ovarian bursa 
 {bursa ovarii) (Figs. 1098 and 1104), and is joined to the ligament by a short fold, 
 the mesovarium (Fig. 1104). 
 
 The mesovarium passes upward from the posterior surface of the broad liga- 
 ment (Fig. 1098). Beneath the mesovarium is a larger and thicker portion of 
 the broad ligament, called the mesometrium (Fig. 1098). 
 
 The Sacro-uterine or Utero-sacral Ligaments {plicae rectouterinae) are contained 
 in the peritoneal folds of Douglas. They pass from the second and third bones 
 of the sacrum, downward and forward on the lateral aspects of the rectum to be 
 attached one on each side of the uterus at the junction of the supravaginal cervix 
 and the body, this point corresponding internally to the position of the os 
 internum. They contain fibrous tissue and unstriated muscle-fibre. Muscular 
 fibres from the uterine wall to the rectal wall constitute the Recto-uterinus muscle 
 {musculus rectouterinus) . This muscle is part of the sacro-uterine ligaments. 
 
 A Round Ligament {ligamentum teres) (Figs. 1088, 1097, 1100, and 1104) is 
 attached on each side of the uterus. The two ligaments are rounded cords, 
 between four and five inches in length, each situated between the layers of the 
 broad ligament in front of and below the Fallopian tube. Commencing at the 
 superior angle of the uterus, this ligament passes forward, upward, and outward 
 through the internal abdominal ring, along the inguinal canal, to the labium 
 majus, in which it becomes lost. The round ligament consists principally of 
 muscular tissue prolonged from the uterus ; also of some fibrous and areolar tissue, 
 besides blood-vessels and nerves, enclosed in a duplicature of peritoneum, which 
 in the foetus is prolonged in the form of a tubular process for a short distance into 
 the inguinal canal. This process is called the canal of Nuck. It is generally oblit- 
 erated in the adult, but sometimes remains pei-vious even in advanced life. It 
 is analogous to the peritoneal pouch which precedes the descent of the testis. 
 
 The Cavity of the Uterus {cavum uteri) (Fig. 1095) . — The cavity of the uterus 
 is small in comparison with the size of the organ, because of the great thickness of 
 the wall. That portion of the cavity which corresponds to the body is triangular, 
 flattened from before backward , so that its anterior and posterior walls are closely 
 approximated, and having its base directed upward toward the fundus. At each 
 superior angle is a funnel-shaped cavity, which constitutes the remains of one 
 division of the body of the uterus into two cornua, and at the bottom of each cavity 
 is the minute orifice of the Fallopian tube. At the inferior angle of the uterine 
 cavity is a small constricted opening, smaller and more nearly circular than the 
 external os uteri, the internal orifice of the uterus or internal os uteri {orificium 
 internum uteri) (Fig. 1095), which leads into the cavity of the cervix. 
 
 The Cavity of the Cervix or Cervical Canal {canalis cervicis uteri) (Fig. 1095). 
 — The cavity of the cervix or cervical canal extends from the internal os uteri to 
 the external os uteri. It is somewhat fusiform, flattened from before backward, 
 broader at the middle than at either extremity, and communicates below with the 
 vagina. The wall of the canal presents, anteriorly and posteriorly, a longitudinal 
 column, from which proceed a number of small oblique columns, giving the appear- 
 ance of branches from the stem of a tree ; and hence the name uterine arbor vitae 
 {plicae palmatae) applied to it. These folds usually become very indistinct after 
 the first labor. 
 
 Structure.— The uterus is composed of three coats: an external or serous coat, a 
 middle or muscular coat, and an internal mucous or coat. 
 
 The Serous Coat or Perimetrium {tunica serosa) (Figs. 1087, 1092, 1096, and 1097). 
 — The serous coat is derived from the peritoneum; it invests the fundus and the 
 whole of the posterior surface of the uterus; but covers the anterior surface only as 
 far as the junction of the body and cervix. In the lower fourth of the posterior 
 surface the peritoneum, though covering the uterus, is not closely connected with 
 
1492 THE FEMALE ORGANS OF GENERATION 
 
 it, being separated from it by a layer of loose cellular tissue and some large veins. 
 At the lateral margins of the uterus the serous coat passes on to the broad liga- 
 ments. The serous coat adheres closely to the uterus, and it is very difficult to 
 separate it from the muscle. 
 
 The Muscular Coat {tunica muscularis) (Fig. 1095) . — The muscular coat forms the 
 chief bulk of the substance of the uterus. In the unimpregnated state it is dense, 
 firm , of a grayish color, and cuts almost like cartilage. It is thick opposite the middle 
 of the body and fundus, and thin at the orifices of the Fallopian tubes. It consists 
 of bundles of unstriped muscular fibres, disposed in layers, intermixed with areolar 
 tissue, blood-vessels, lymphatic vessels, and nerves. The muscular tissue is dis- 
 posed in three layers — external, middle, and internal. 
 
 The external layer is placed beneath the peritoneum, disposed as a thin plane 
 on the. anterior and posterior surfaces. It consists of fibres which pass trans- 
 versely across the fundus, and, converging at each superior angle of the uterus, 
 are continued on the Fallopian tube, the round ligament, the ligament of the 
 ovary; some passing at each side into the broad ligament, and others running 
 backward from the cervix into the sacro-uterine ligaments. The fibres of the 
 external portion of the outer layer (stratum suhserosum) are longitudinal. The 
 fibres of the inner portion of the outer layer {stratum supravasculare) are partly 
 circular and partly longitudinal. 
 
 The middle layer of fibres {stratum vasculare), which is thickest, presents bundles 
 of circular fibres closely connected with blood-vessels. In this layer are most of 
 the blood-vessels. The circular fibres about the internal os form a distinct 
 sphincter. Those which surround the orifices of the Fallopian tubes are arranged 
 in the form of two hollow cones, the apices of which surround the orifices of the 
 Fallopian tubes, their bases intermingling with one another on the middle of the 
 body of the uterus. 
 
 The internal or deep layer {stratum mucosum) consists of longitudinal fibres. 
 Some consider the deeper portion of the muscular tissue of the uterus to be the 
 muscularis mucosae. But the deep portion of the muscular substance is con- 
 tinuous with the more superficial portion, and there is no submucous coat between 
 the muscle and the mucous membrane. The deeper layer of muscular fibres of 
 the uterus contains connective tissue and elastic fibres. The muscular tissue of 
 the cervix contains more connective and elastic tissue than does the body of the 
 uterus; hence, the cervix is harder and stiffer than the body. 
 
 The Mucous Membrane {tunica mucosa) (Fig. 1095). — The mucous membrane 
 is thin, smooth, and closely adherent to the subjacent muscular tissue. It is 
 continuous, through the fimbriated extremity of the Fallopian tubes, with the 
 peritoneum, and through the os uteri with the lining of the vagina. 
 
 In the body of the uterus it is smooth, soft, of a pale-red color lined with columnar 
 ciliated epithelium, and presents, when viewed with a lens, the orifices of numer- 
 ous tubular follicles arranged perpendicularly to the surface. It is unprovided 
 with any submucosa, but is intimately connected with the innermost layer of 
 the muscular coat. In structure its corium differs from ordinary mucous membrane, 
 consisting of an embryonic nucleated and highly cellular form of connective tissue, 
 in which run numerous large lymphatics. In it are the tube-like uterine glands 
 {glandulae uterinae), which are of small size in the unimpregnated uterus, but 
 shortly after impregnation become enlarged and elongated, presenting a contorted 
 or waved appearance toward their closed extremities, which reach into the mus- 
 cularis, and may be single or bifid. The uterine glands consist of a delicate 
 membrane, lined with epithelium, which becomes ciliated toward the orifices. 
 
 In the cervix the mucous membrane is sharply difi'erentiated from that of the 
 uterine cavity. It is thrown into numerous oblique ridges, which diverge from an 
 anterior and posterior longitudinal raphe, presenting an appearance which has 
 
THE W03IB OR UTERUS I493 
 
 received the name of axbor vitae. In the upper two-thirds of the canal the mucous 
 membrane is provided with numerous deep glandular follicles (glandulae cervicales 
 uteri), which secrete a clear viscid alkaline mucus; and in addition, extending 
 through the whole length of the canal, are a variable number of little cysts, pre- 
 sumably follicles, which have become occluded and distended with retained secre- 
 tion. They are called the ovules of Naboth. The mucous membrane covering the 
 lower half of the cervical canal presents numerous papillae. The epithelium of 
 the upper two-thirds is cylindrical and ciliated, but below this it loses its cilia, and 
 gradually changes to squamous epithelium close to the external os. 
 
 The Uterus at Different Ages. — The uterus of the foetus is in the abdominal cavity 
 projecting above the brim of the pelvis. The cervix is considerably larger than 
 the body. At birth the cervix is larger relatively than in the adult; there is no dis- 
 tinct internal os distinguishing the cavity of the body of the uterus from the cavity of 
 the cervix, and " the arbor vitae extends throughout the whole length of the uterus."^ 
 The growth of the uterus is slow until puberty is almost reached, when for a time 
 the growth is rapid. The growth of the uterine body causes the mucous mem- 
 brane of this part to lose its folds, hence the arbor vitae disappears from the body. 
 In a woman who has had children the uterine cavity is larger than in a woman 
 who has never borne a child. In advanced years the uterine wall becomes paler 
 and hard and rigid from atrophic fibrous changes. A more distinct constriction 
 separates the body and cervix. The internal os frequently and the external os 
 occasionally are obliterated in old age. 
 
 Abnormalities. — Very rarely the uterine cavity is divided into two by a septum. 
 Occasionally the condition known as bicomate uterus exists. In this condition 
 each lateral angle is prolonged into a horn or cornu. The uterus is formed by the 
 union of the two ducts of Miiller, and failure of fusion of these ducts makes a 
 double uterus or a bicornate uterus. 
 
 Changes at a Menstrual Period. — For several days before the menstrual flow 
 begins the mucous membrane increases in thickness and vascularity and its sur- 
 face is cast into folds. After these preparatory changes the superficial portions 
 of the mucous membrane break down and are cast off, and bleeding begins. At 
 the termination of menstruation the mucous membrane rapidly regenerates. At 
 each menstrual period from 100 to 200 grammes of blood are discharged. The 
 meaning of menstruation is uncertain. Pfliiger believes the wall of the uterus is 
 made raw, so that if an impregnated ovum arrives it will adhere. Reichert believes 
 that menstruation means that no impregnated ovum has arrived in the womb, and 
 hence no bed is needed for one. 
 
 Changes Induced by Pregnancy. — The muscular fibres hypertrophy enormously 
 and become vastly longer and broader. There is a great increase in connective 
 tissue, and new connective-tissue fibres pass between bundles of muscle. The 
 peritoneal coat undergoes hyperplasia. It remains closely adherent to the uterus, 
 except over the lower segment, from which region it can be easily stripped. The 
 blood-vessels become large ancl tortuous. The nerves are increased in length and 
 new filaments form. The lymphatics undergo hypertrophy and hyperplasia 
 (Prof. Barton Cooke Hirst). The uterus becomes spherical, and after the fourth 
 month ovoidal. Early in pregnancy the increase in weight causes the uterus 
 to descend in the pelvis. After the third month it rises progressively, and during 
 the ninth month the fundus reaches the epigastrium. "Before term (four weeks 
 in primiparae, ten days or one week in multiparae) the fundus sinks again, as 
 the presenting part and lower uterine segment become engaged in the pelvic 
 cavity. This phenomenon is explained by contraction of the overstretched 
 abdominal walls."^ The womb is acutely anteflexed during the first three months 
 
 I Prof. Francis A. Dixon in Prof. Cunningham's Text-book of Anatomy. 
 « A Text-book of Obstetrics. By Prof. Barton Cooke Hirst, 
 
1494 
 
 THE FEMALE ORGANS OF GENERATION 
 
 of pregnancy. After this period, as the womb rises, the anteflexion is diminished, 
 but some degree remains, because the abdominal walls are too lax to hold the 
 organ straight. The uterus passes somewhat to the right side and undergoes a 
 rotation on its longitudinal axis, so that the anterior surface looks front and to the 
 
 - ^^g^^'j^^^^r^'-^ Branches to tube. 
 Branches to fundus. 
 
 Fig. 1100. 
 
 Vaginal arteries. 
 -The arteries of the internal organs of generation of the female, seen from behind. (After Hyrtl.) 
 
 right. These changes in position are caused by fecal distention of the sigmoid. 
 The intestines are above and back of the uterus. During the first four months the 
 cervix softens and enlarges somewhat. The length of the cervical canal is not 
 
 VESSELS FROM 
 BODY OF FUNDUS 
 
 VE88E 
 FROM TUB 
 
 ^, 
 
 VESSELS OF 
 ROUND LIGAMENT 
 
 ANASTOMOSIS E V 
 
 OF VESSELS 
 
 VAGINAL, 
 LYMPHATICS 
 
 Fig. 1101. — The lymphatic vessels of the uterus. (Poirier and Charpy.) 
 
 altered during pregnancy, and the canal does not dilate until labor begins. During 
 pregnancy the cervical glands secrete thick mucus, which coagulates and occludes 
 the cervical canal ; the round ligaments become stronger, and the layers of the 
 broad ligament are separated toward their inner portions by the enlarging womb. 
 
THE W03IB OB UTERUS 
 
 1495 
 
 After parturition the uterus nearly regains its former size, usually weighing 
 something over one and a half ounces; but its cavity is larger than in the virgin 
 state, the external orifice is more marked, its edges present a fissured surface, its 
 vessels are very tortuous, and its muscular layers are more defined. 
 
 Vessels and Nerves (Fig. 1100). — The arteries of the uterus are the uterine, from 
 the internal iliac, and the ovarian, from the aorta. They are remarkable for their 
 tortuous course in the substance of the organ and for their frequent anastomoses. 
 The uterine artery reaches the lower part of the uterus at the side and is pro- 
 
 JUXTA-»On^ 
 GLAN 
 
 VESSELS FROM 
 BODY OF UTERUS 
 
 VESSELS FRO 
 
 NECK OF UTERU 
 
 TO LATERA 
 
 SACRAL GLAN 
 
 VESSELS FRO 
 
 NECK OF UTEPU 
 
 VESSELS 
 ROUND LIGAME 
 
 XTA-AORTIC 
 DS 
 
 ELOF 
 LLOPIAN TUBE 
 
 Fig. 1102.— The lymphatics of the internal organs of generation in the female. (Poirier and Charpy.) 
 
 longed as a large artery to the body and fundus, which ascends between the 
 layers of the broad ligament. The uterine artery gives off a smaller branch, the 
 cervical, which descends to supply the cervix and sends cervico-vaginal branches 
 to the vagina. The azygos arteries of the vagina come from the cervico-vaginal 
 reinforced by branches of the vaginal arteries (Fig. 1104). A median longitudinal 
 vessel is formed in front and behind, which descends in the vaginal wall. The 
 termination of the ovarian artery meets the termination of the uterine artery, 
 and forms an anastomotic trunk from which branches are given off to supply 
 the uterus. Dr. Byron Robinson, instead of describing the uterine and ovarian 
 
1496 THE FE3IALE OBOANS OF GENERATION 
 
 arteries as two vessels, describes them as parts of one vessel, the arteria uterina 
 ovarica (p. 558). The veins are of large size, and correspond with the arteries. 
 In the impregnated uterus these vessels form the uterine sinuses, consisting of 
 the lining membrane^ of the veins adhering to the walls of the canals channelled 
 through the substance of the uterus. They terminate in the uterine plexuses, 
 which empty into the internal iliac veins. The lymphatics (Figs. 1101 and 1102) 
 originate from three networks, a muscular network, a peritoneal network, and a 
 network in the stroma. The trunks from these networks anastomose, and thus 
 form another network beneath the peritoneum, and from the fourth network the 
 collectors arise. The network of the cervix is continuous with that of the body. 
 The collecting trunks from the cervical region number from five to eight. Some 
 terminate in the external iliac glands, some in the internal iliac glands, some in the 
 lateral sacral glands, or the glands of the promontory. The collecting trunks from 
 the body terminate chiefly in the juxta-aortic or pre-aortic glands, but some termi- 
 nate in the external iliac glands, and some in the inguinal glands.^ The nerves come 
 chiefly from the utero-vaginal plexus, which continues into the hypogastric plexus 
 and receives filaments from the third and fourth sacral nerves. The uterus also 
 receives direct fibres from the hjrpogastric plexus and from the vesical plexus. 
 
 Surgical Anatomy. — Pelvic cellulitis {parametritis) is inflammation of the pelvic cellular 
 tissue. It is due to sepsis, and its usual antecedent is uterine sepsis. A laceration of the cervix 
 may admit bacteria. An abscess may form. If it points in the vagina it should be incised through 
 the vaginal wall. The uterus may require removal {hysterectomy) in cases of malignant disease 
 or for fibroid tumors. Carcinoma is the most common form of malignant disease of the uterus, 
 though cases of sarcoma do occur. Carcinoma may show itself either as a columnar carcinoma 
 or as a squamous carcinoma ; the former commencing either in the cervix or body of the uterus, the 
 latter always commencing in the epithelial cells of the mucous membrane covering of the vaginal 
 surface of the cervix. The columnar form may be treated in the early stage, before fixation has 
 taken place, by removal of the uterus, either through the vagina or by means of abdominal 
 section. The former operation is attended by the smaller death-rate. Vaginal hysterectomy 
 may be performed in any case in which the uterus or the uterus and tumor are not too large to be 
 withdrawn through the vagina. It is difficult in this operation to deal with adhesions and other 
 complications in the upper part of the pelvis, and for this reason many surgeons prefer the abdom- 
 inal operation. Vaginal hysterectomy is performed by placing the patient in the lithotomy position 
 and introducing a large duckbill speculum into the vagina. The cervix is then seized with a vol- 
 sellum and pulled down as far as possible and the mucous membrane of the vagina incised around 
 the cervix as near to it as the disease will allow, especially in front, where the ureters are in 
 danger of being wounded. A pair of dressing forceps are then pushed through into Douglas's 
 pouch and opened sufficiently to allow of the introduction of the two forefingers, by means of 
 which the opening is dilated laterally as far as the sacro-uterine ligaments. A somewhat similar 
 proceeding is adopted in front, but here the bladder has to be separated from the anterior wall 
 of the uterus for about an inch before the vesico-uterine fold of peritoneum can be reached. 
 This is done by carefully burrowing upward with a director and stripping the tissues off the 
 anterior uterine wall. When the vesico-uterine pouch has been opened and the opening dilated 
 laterally, the uterus remains attached only by the broad ligaments, in which are contained the 
 vessels that supply the uterus. Before division of the ligaments, these vessels have to be dealt 
 with. The forefinger of the left hand is introduced into Douglas's pouch and an aneurism 
 needle, armed with a long silk ligature, is inserted into the vesico-uterine pouch, and is pushed 
 through the broad ligament of one side about an inch above its lower level and at some distance 
 from the uterus. One end of the ligature is now pulled through the anterior opening, and in this 
 way we have the lowest inch of the broad ligament, in which is contained the uterine artery, 
 enclosed in a ligature. This is tied tightly, and the operation is repeated on the other side. The 
 broad ligament is then divided on either side, between the ligature and the uterus, to the extent 
 to which it has been constricted. By traction on the volsellum which grasps the cervix, the uterus 
 can be pulled considerably farther down in the vagina, and a second inch of the broad ligament 
 is treated in a similar way. This second ligature will embrace the pampiniform plexus of veins 
 and, when the broad ligament has been divided on either side, it will be found that a third liga- 
 ture can be made to pass over the Fallopian tube and top of the broad ligament, after the uterus 
 has been dragged down as far as possible. After the third ligature has been tied and the struc- 
 tures between it and the uterus divided, this organ will be freed from all its connections and can 
 be removed from the vagina. This canal is then sponged out and lighUy dressed with gauze, 
 
 1 The Lymphatics. By Poirier, Cun6o, and Delamare. Translated and edited by Cecil H. Leaf. 
 
THE FALLOPIAN TUBE I497 
 
 no sutures being used. The gauze may be removed at the end of the second day. In squamous 
 epitheHoraa, amputation of the cervix is done by some in those cases where the disease is recog- 
 nized before it has invaded the walls of the vagina or the neighboring broad ligaments. The 
 operation consists in removing a wedge-shaped piece of the uterus, including the cervix, through 
 the vagina and attaching the cut surfaces of the stump to the anterior and posterior vaginal walls, 
 so as to prevent retraction. In view, however, of the continuity of the lymphatic network of the 
 cervix with the lymphatics of the body, the operation is insufficient and should be condemned. 
 Complete abdominal hysterectomy is rarely necessary, except for malignant disease. In this opera- 
 tion the entire uterus is removed. The preliminary introduction of bougies into the ureters as 
 practised by Kelly and Clark enables the surgeon to readily recognize the situations of these tubes. 
 After the abdomen has been opened the uterine vessels are secured and the broad ligaments 
 divided in a similar manner to that employed in vaginal hysterectomy, except that the proceeding 
 is commenced from above. When the first two ligatures have been tied and the broad ligament 
 divided, it will be found that the uterus can be raised out of the pelvis. A transverse incision 
 is now made through the peritoneum, where it is reflected from the anterior surface of the uterus 
 on to the back of the bladder and the serous membrane peeled from the surface of the uterus 
 until the vagina is reached. The anterior wall of this canal is cut across. The uterus is now 
 turned forward and the peritoneum at the bottom of Douglas's pouch incised transversely, and 
 the posterior wall of the vagina cut across until it meets the incision on the anterior wall. The 
 uterus is now almost free, and is held only by the lower part of the broad ligament on either 
 side, containing the uterine artery. A third ligature is made to encircle this, and, after having 
 been tied, the structures are divided between the ligature and the uterus. The organ can now 
 be removed. The vagina is plugged with gauze, and the external wound closed in the usual 
 way. The vagma acts as a drain, and therefore the opening into it is usually left unsutured. In 
 some cases of uterine fibroid the abdomen is opened and the tumor is removed, but the uterus is 
 not taken away. This operation is called myomectomy. This operation is suited only to solitary 
 subperitoneal or interstitial tumors (Penrose). 
 
 The common operation for uterine fibroids is supravaginal amputation. The uterus is 
 cut away and the cervical flaps are sutured. Before the technique of hysterectomy was per- 
 fected and before myomectomy was devised the favorite operation for uterine fibroids was 
 salpinrp-oophorectomy, and by it a large majority of cases operated upon were cured. When it 
 succeeds a premature menopause is induced and the tumor shrinks. The operation is useless if 
 a woman is past the menopause, and is apt to fail if the tumor is very soft or very large. 
 
 THE ADNEXA OR APPENDAGES OF THE UTERUS. 
 
 The appendages of the uterus are the Fallopian tubes, the ovaries and ovarian 
 ligaments, and the round ligaments. They are placed in the following order: in 
 front is the round ligament; the Fallopian tube occupies the upper margin of the 
 broad ligament; the ovary and its ligament are behind and below both. 
 
 THE FALLOPIAN TUBE (TUBA UTERINA [FALLOPII]) 
 
 (Figs. 1092, 1097, 1098, 1103, 1104). 
 
 The Fallopian tubes or oviducts convey the ova from the ovaries to the cavity 
 of the uterus. They are two in number, one on each side, situated in the upper 
 margin of the broad ligament, extending from each superior angle of the uterus to 
 the sides of the pelvis. Each tube is about four inches and a quarter in length, 
 and is placed in a fold of peritoneum, which is part of the broad ligament and is 
 called the mesosalpinx (Fig. 1098). Each tube is described as consisting of four 
 portions: (1) the isthmus (isthmus tubae uterinae) (Fig. 1103), or inner constricted 
 third; (2) the ampulla (ampulla tubae uterinae) (¥\g. 1103), or outer dilated portion, 
 which curves over the ovary ; and (3) the infundibulum, the funnel-like expansion of 
 the tube, at the bottom of which is the abdominal orifice or pavilion (ostium abdom- 
 inale tubae uterinae) (Fig. 1103). The abdominal orifice has a small diameter (2 
 mm. when relaxed to its full extent). The margin of the infundibulum is rendered 
 irregular by the presence of numerous small processes, the fimbriae (fimbriae tubae). 
 This end of the tube is called the fimbriated extremity (Fig. 1103), because of these 
 processes. The surfaces of the fimbriae looking into the cavity of the infundi- 
 bulum are covered with mucous membrane continuous with the tubal mucous 
 
1498 
 
 THE FEMALE ORGANS OF GENERATION 
 
 membrane. The outer surfaces are covered with peritoneum. One of the fimbriae 
 is attached to the ovary and is called the ovarian fimbria {fimbria ovarica) (Fig. 
 1103). (4) The uterine portion of the tube (pars uterina) (Fig. 1095) is in the uterine 
 wall. The opening into the uterus {ostium uterinum tubae) is even smaller than 
 the abdominal opening, and will admit only a small bristle. The general direc- 
 tion of the Fallopian tube is outward, backward, and downward. In connec- 
 tion with the fimbriae of the Fallopian tube or with the broad ligament close to 
 them there is frequently one or more small vesicles floating on a long stalk of 
 peritoneum. These are termed the hydatids of Morgagni (appendices vesiculosi). 
 They are representative of small portions of the upper extremity of the Wolffian 
 duct. 
 
 Course Pursued by the Fallopian Tube (Figs. 1088 and 1103). — The tube on each 
 side begins at the upper and outer angle of the uterus and passes outward in a 
 horizontal direction toward the uterine extremity of the ovary. It then bends 
 almost to a right angle and ascends close to the pelvic wall and in front of the 
 anterior margin to the tubal extremity of the ovary. At this point it turns sharply 
 
 Fimbria ovutica. 
 
 Fig. 1103. — Uterine appendages, seen from behind. (Henle.) 
 
 downward and a little backward, and the inner surface of the infundibulum comes 
 to lie upon the free margin and the posterior portion of the inner surface of the 
 ovary, "The fimbria ovarica thus ascends in a recurrent direction to the extrem- 
 itas tubaria."^ 
 
 Structure. — ^The Fallopian tube consists of three coats — serous, muscular, and 
 mucous. 
 
 The external or serous coat (tunica serosa) (Fig. 1098) is peritoneal. Beneath 
 this lies the tunica adventitia, composed of lax connective tissue. 
 
 The middle or muscular coat (tunica muscularis) consists of an external longi- 
 tudinal layer (stratum longitudinale) , and an internal circular layer (stratum cir- 
 culare) of muscular fibres continuous with those of the uterus. 
 
 The internal or mucous coat (tunica mucosa) is continuous with the mucous lining 
 of the uterus and, at the free extremity of the tube, with the peritoneum. It is 
 thrown into longitudinal folds (plicae tubariae), which in the outer, larger part of 
 the tube or ampulla (plicae ampullares) are much more extensive than in the 
 narrow canal of the isthmus (plicae isthmicae). The lining epithelium is columnar 
 and ciliated. This form of ephithelium is also found on the inner surface of the 
 
 1 Spalteholz's Atlas. English edition by Barker. 
 
THE OVABY 
 
 1499 
 
 fimbriae, while on the outer or serous surfaces of these processes the epithelium 
 gradually merges into the endothelium of the peritoneum. 
 
 Vessels and Nerves. — The chief artery of the tube is the tubal branch of the 
 uterine artery (ramus tuharius) (Fig. 1100). It also receives branches from the 
 ovarian (Fig. 1100). Some of the tubal veins empty into the uterine veins, some 
 into the ovarian veins. The lymphatics (Figs. 1101 and 1102) coming from the 
 tube unite with the trunks coming from the uterus and ovary and terminate in 
 the juxta-aortic glands. The nerves come from the same plexuses that send 
 branches to the uterus and ovary. 
 
 The Epo-ophoron, Parovarium or Organ of Rosenmiiller (Figs. 1094, 1095, and 
 1103) is placed in the mesosalpinx, between the ovary and tube. It consists of a 
 number of epithelial-lined closed tubes. This structure can be readily seen if the 
 mesosalpinx is stretched and held in front of the light. One of these tubes runs 
 parallel to the Fallopian tube and is called Gartner's duct {ductus epoophori longitu- 
 dinalis). A number of tubes (ductuli transversi) ascend from near the ovary and 
 
 Fimbrinted extremity 
 of fiihe 
 
 Fallopian tube 
 
 Broad ligament, 
 upper part. 
 
 \ 
 
 Artery 
 vein. 
 
 Vagina, anterior wall. 
 
 Fig. 1104. — The uterus and its appendages. Posterior view. The parts have been somewhat displaced from 
 their proper position in the preparation of the specimen; thus the right ovary has been raised above the Fallo- 
 pian tube, and the fimbriated extremities of the tubes have been turned upward and outward. (From a prepa- 
 ration in the Museum of the Royal College of Surgeons of England.) 
 
 each empties into Gartner's duct at a right angle. Gartner's duct is a portion of 
 the Wolffian duct, which has persisted and is represented in the male by the canal 
 of the epididymis. The tubules which join the duct "are derived from the meso- 
 nephros and represent the vasa efferentia and coni vasculosi of the testis, and 
 probably also the ductuli aberrantes of the canal of the epididymis."' 
 
 The Paro-ophoron is within the mesosalpinx, but is nearer to the uterus than 
 is the epo-ophoron. It consists of several small tubules, which can be seen in an 
 adult only by the aid of a pocket lens. They are visible to the naked eye in a child 
 at birth. It represents the organ of Girald^s in the male and is derived from the 
 mesonephros. 
 
 THE OVARY (Figs. 1088, 1092, 1094, 1095, 1097, 1098, 1099, 1103, 1104). 
 
 The ovaries (ovaria) , the testes muliebres of Galen, are two in number and are 
 analogous to the testes in the male. They are oval-shaped bodies of an elongated 
 
 ' Prof. Cunningham's Text-book of Human Anatomy. 
 
1500 THE FEMALE ORGANS OF GENERATION 
 
 form, flattened from above downward, situated one on each side of the uterus, 
 in the posterior layer of the broad ligament behind and below the Fallopian tube. 
 Each ovary is connected by its anterior straight margin to the broad ligament; 
 by its lower extremity to the uterus by a proper ligament, the ligament of the 
 ovaxy (ligamentum ovarii proprium) (Fig. 1103); and by its upper end to the 
 fimbriated extremity of the Fallopian tube by the ovarian fimbria (fimbria ovarica) 
 (Fig. 1103), its mesial and lateral surfaces and posterior convex border are free 
 (Fig. 1104). The ovaries are of a grayish-pink color, and present either a smooth 
 or a puckered, uneven surface. They are each about an inch and a half in 
 length, three-quarters of an inch in width, and about a third of an inch thick, 
 and weigh from one to two drachms. 
 
 The exact position of the ovary has been the subject of considerable difference 
 of opinion, and writers are in conflict as to what is to be regarded as the normal 
 position. The fact appears to be that the ovary is differently placed in different 
 individuals. The two ovaries are seldom placed in absolutely identical positions. 
 Hasse has described the ovary as being situated with its long axis transverse, or 
 almost transverse, to the pelvic cavity. Schultze, on the other hand, believes that 
 its long axis is antero-posterior. Kolliker asserts that the truth lies between 
 these views, and that the ovary is placed obliquely in the pelvis, its long axis 
 lying parallel to the external iliac vessels, with its surface directed inward and out- 
 ward , and its convex free border upward. His has made some important observa- 
 tions on this subject, and his views are largely accepted. He teaches that the 
 uterus rarely lies symmetrically in the middle of the pelvic cavity, but is generally 
 inclined to one or other side, most frequently to the left, in the proportion of three 
 to two. The position of the two ovaries varies according to the inclination of the 
 uterus. When the uterus is inclined to the left, the ovary of this side lies with 
 its long axis vertical and with one side closely applied to the outer wall of the 
 pelvis, while the ovary of the opposite side, being dragged upon by the inclina- 
 tion of the uterus, lies obliquely, its outer extremity being retained in close appo- 
 sition to the side of the pelvis by the infundibulo-pelvic ligament. When, on 
 the other hand, the uterus is inclined to the right, the position of the two 
 ovaries is exactly reversed, the right being vertical and the left oblique. In 
 whichever position the ovary is placed, the Fallopian tube forms a loop around it, 
 the uterine half ascending obliquely over it, and the outer half, including the 
 dilated extremity, descending and bulging freely behind it. From this extremity 
 the fimbriae pass upward on to the ovary and closely embrace it. 
 
 Waldeyer^ states, as the result of the examination of fifty female subjects, 
 ranging from early childhood to advanced age, that the ovary "lies on the lateral 
 pelvic wall and vertically when the woman takes the erect posture." Its tubal 
 extremity is near the external iliac vein; its uterine end is directed downward, 
 while the Fallopian tube overlies it so as to cover it on its medial face entirely or 
 nearly so. Its convex margin looks downward and backward toward the pelvic 
 cavity and rectum, while its straight margin or hilum lies laterally on the pelvic 
 wall attached to the mesosalpinx. He also finds that it lies in a distinct but 
 shallow groove (fossa ovarii) limited above by the hypogastric artery and below 
 by the ureter, in such a manner that the ureter lies along the convex margin 
 of the ovary, and the hypogastric artery passes near the hilum or straight margin. 
 
 The ovary possesses two poles or extremities: (1) An outer, superior or tubal 
 extremity (extremitas tubaria ovarii). (2) An inner, inferior or uterine extremity 
 (extremitas uterina ovarii). The ovary has two surfaces, an inner surface (]acies 
 medialis), which is also upper; an outer surface (facies lateralis), which is also 
 lower. The posterior or free border (margo liber) is markedly convex. The anterior 
 
 1 Journal of Anatomy and Physiology, vol. xxxii. 
 
THE DESCENT OF THE OVAltY 1501 
 
 border (margo mesovaricus) is almost straight and is narrow. The anterior border 
 is not free, but is joined to the posterior layer of the broad Ugament by a peritoneal 
 fokl known as the mesovarium. There is a groove in the anterior border called the 
 hilum (hilus ovarii), through which vessels and nerves to pass, and emerge from 
 the ovary. 
 
 Supports and Connections of the Ovary. 
 
 From its upper extremity a peritoneal fold is continuous with the peritoneum 
 over the iliac vessels and Psoas muscle. It is called the ovario-pelvic fold or the 
 suspensory ligament (ligamenium suspensorium ovarii) (Fig. 1088). It is in reality 
 a portion of the broad ligament, and within it are the ovarian vessels and nerves. 
 The vessels (Fig. 1104) and nerves go to the anterior border of the ovary and are 
 surrounded by a peritoneal sheath derived from the posterior layer of the broad 
 ligament ; it is thus evident that the anterior border of the ovary is connected to 
 the posterior portion of the broad ligament by a very short mesentery, the meso- 
 varium^ (Fig. 1098). The ligament of the ovary or ovarian ligament (Figs. 1088 
 and 1103) is a round, cord-like structure, composed chiefly of non-striated muscle- 
 fibres, which passes between the two folds of the broad ligament from the lower 
 extremity of the ovary to the lateral angle of the uterus. The ovarian fimbria 
 (Fig. 1103), as previously stated, passes to the upper extremity of the ovary 
 from the extremity of the Fallopian tube. 
 
 The Descent of the Ovary. 
 
 In the female there is a gubernaculum which effects a considerable change in 
 the position of the ovary, though not so extensive a change as is effected upon the 
 male testicle. The gubernaculum in the female, as it lies on either side in con- 
 tact with the fundus of the uterus formed by the union of the Miillerian ducts, 
 contracts adhesions to this organ and thus the ovary is prevented from descending 
 below this level. The remains of the gubernaculum — that is to say, the part 
 between the attachment of the cord to the uterus to its termination in the labium 
 majus — ultimately forms the round ligament of the uterus. A pouch of peri- 
 toneum accompanies it along the inguinal canal, analogous to the funicular process 
 in the male; it is called the canal of Nuck. In rare cases the gubernaculum fails 
 to contract adhesions to the uterus, and then the ovary descends through the 
 inguinal canal into the labium majus, extending down the canal of Nuck. 
 Under these conditions, the position of the ovary resembles the position of the 
 testicle in the male. 
 
 The Ovary at Different Ages. — The ovary of childhood is smooth and 
 even. The rupture of Graafian follicles, repeated many times, causes the surface 
 of the ovary to become pitted, puckered, fibrous, and uneven in old age. The sur- 
 face of the ovary is grayish-red in color. The corpus luteum of a non-pregnant 
 woman slowly degenerates and disappears. The corpus luteum of an impreg- 
 nated woman enlarges during pregnancy. 
 
 Structure (Figs. 1098, 1099, 1105, and 1106).— The ovary consists of a number 
 of Graafian follicles or vesicles embedded in the meshes of a stroma or framework, 
 and invested by a serous covering derived from the peritoneum. 
 
 Serous Covering. — Though the investing membrane of the ovary is continuous 
 with the peritoneum near the hilum of the ovary (the point of junction being 
 indicated by a narrow white line), it differs essentially from the peritoneum, 
 inasmuch as it is an epithelial st-^ucture and consists of a single layer of columnar 
 epithelial cells, instead of the flattened endothelial cells of other parts of the 
 
 1 Prof. Cunningham's Text-book of Anatomy. 
 
1502 THE FEMALE ORGANS OF GENERATION 
 
 membrane; this has been termed the germinal epithelium of Waldeyer, and gives 
 to the surface of the ovary a dull-gray aspect instead of the shining smoothness 
 of serous membranes generally. 
 
 Stroma.— The stroma is a peculiar soft tissue, abundantly supplied with blood- 
 vessels, consisting for the most part of spindle-shaped cells, with a small amount 
 of ordinary connective tissue. These cells have been regarded by some anatomists 
 as unstriped muscle-cells, which, indeed, they most resemble (His) ; by others as 
 connective-tissue cells (Waldeyer, Henle, and Kolliker). On the surface of the 
 organ this tissue is much condensed, and forms a layer composed of short connec- 
 tive-tissue fibres, with fusiform cells between them. This was formerly regarded 
 as a distinct fibrous covering, and was termed the tunica albuginea, but is nothing 
 more than a condensed layer of the stroma of the ovary. 
 
 Graafian Follicles or Vesicles (folliculi oophori vesiculori [Graafi]) (Figs. 1105 and 
 1106). — Upon making a section of an ovary numerous round transparent vesicles 
 of various sizes are to be seen ; they are the Graafian vesicles or ovisacs containing 
 the ova. Immediately beneath the superficial covering is a layer of stroma, in 
 which are a large number of minute vesicles of uniform size, about y^^ of an 
 inch in diameter. These are the Graafian vesicles in their earliest condition, and 
 the layer where they are found has been termed the cortical layer. They are 
 especially numerous in the ovary of the young child. After puberty and during the 
 whole of the child-bearing period large and mature, or almost mature. Graafian 
 
 vesicles are also found in the cortical 
 layer in small numbers, and also 
 corpora lutea, the remains of vesicles 
 which have burst and are undergoing 
 atrophy and absorption. Beneath 
 this superficial stratum other large 
 and mature Graafian vesicles are 
 
 Granular zone. 
 
 Ovum. 
 
 Peritoneum. 
 
 Fig. 1105. — Section of the ovary. 1, outer covering; 
 1', attached border; 2, central stroma; 3, peripheral 
 stroma; 4, blood-vessels; 5, Graafian follicles in their 
 earliest stage; 6, 7, 8, more advanced follicles; 9, an almost 
 mature follicle; 9', follicle from which the ovum has 
 escaped; 10, corpus luteum. (After Schron.) 
 
 / \ J I j Coats of the 
 Stroma of the ovary ' ( Graafian vesicle 
 w ith blood vessels. Membrav a 
 (iranulma. 
 
 Fig. 1106. — Section of the Graafian vesicle. 
 (After von Baer.) 
 
 found embedded in the ovarian stroma. These increase in size as they recede 
 from the surface toward a highly vascular stroma in the centre of the organ, 
 termed the medullary substance {zona vasculosa [Waldeyeri]). This stroma forms 
 the tissue of the hilum by which the ovary is attached, and through which the 
 blood-vessels enter; it does not contain any Graafian vesicles. 
 
 The larger Graafian follicles consist of an external fibro- vascular coat connected 
 with the surrounding stroma of the ovary by a network of blood-vessels; and an 
 internal coat, named the ovicapsule, which is lined by a layer of nucleated cells, 
 called the membrana granulosa. The fluid contained in the interior of the vesicles 
 is transparent and albuminous, and in it is suspended the ovum. In that part of 
 the mature Graafian vesicle which is nearest the surface of the ovary the cells 
 of the membrana granulosa are collected into a mass which projects into the 
 cavity of the vesicle. This is termed the discus proligerus, and in this the ovum 
 is embedded. 
 
 The ova are formed from the germinal epithelium on the surface of the ovary. 
 
THE DESCENT OF THE OVARY 1503 
 
 This becomes thickened, and in it are seen some cells which are larger and more 
 rounded than the rest; these are termed the primordial ova. The germinal epi- 
 thelium grows downward in the form of tubes or columns, termed the %gg tubes 
 of Pfliiger, into the ovarian stroma, which grows outward between the tubes, and 
 ultimately cuts them off from the germinal epithelium. These tubes are further 
 subdivided into rounded nests or groups, each containing a primordial ovum which 
 undergoes further development and growth, while the surrounding cells of the nest 
 form the epithelium of the Graafian follicle. 
 
 The development and maturation of the Graafian vesicles and ova continue 
 uninterruptedly from puberty to the end of the fruitful period of woman's life, 
 while their formation commences before birth. Before puberty the ovaries are 
 small, the Graafian vesicles contained in them are disposed in a comparatively 
 thick layer in the cortical substance; here they present the appearance of a large 
 number of minute closed vesicles, constituting the early condition of the Graafian 
 vesicle; many, however, never attain full development, but shrink and disappear. 
 At puberty the ovaries enlarge and become more vascular, the Graafian vesicles 
 are developed in greater abundance, and their ova are capable of fecundation. 
 
 Discharge of the Ovum. — The Graafian vesicles, after gradually approaching 
 the surface of the ovary, burst; the ovum and fluid contents of the vesicles are 
 liberated, and escape on the exterior of the ovary, passing thence into the Fallopian 
 tube. This is effected either by application of the tube to the ovary, or by a 
 curling upward of the fimbriated extremity, so that the ovum is caught as it falls. 
 
 In the foetus the ovaries are situated, like the testes, in the lumbar region, near 
 the kidneys. They may be distinguished from those bodies at an early period by 
 their elongated and flattened form, and by their position, which is at first oblique 
 and then nearly transverse. They gradually descend into the pelvis. 
 
 The Round Ligament (p. 1491). 
 
 Vessels and Nerves. — The arteries of the ovaries (Figs. 1100 and 1104) are the 
 ovarian from the aorta, corresponding to the spermatic arteries in the male. The 
 ovarian artery on each side enters the pelvis in the fold of broad ligament known 
 as the suspensory ligament of the ovary and enters the attached border, or hilum, 
 of the ovary. The ovarian vessels anastomose about the hilum with branches of 
 the uterine artery. The veins follow the course of the arteries; they form a plexus 
 near the ovarj, the pampiniform plexus, corresponding to a like structure near the 
 male testicle. The lymphatics (Figs. 1101 and 1102) terminate in the glands to 
 the corresponding side of the aorta, and they anastomose in their course with 
 trunks from the uterine fundus and Fallopian tube. The nerves come from the 
 ovarian plexus, which is a continuation of the renal plexus along the ovarian artery, 
 and from the aortic plexus. 
 
 Surgical Anatomy of the Appendages.— Ea-fra-uferme pregnancy most commonly occurs 
 in the ampulla of the tube. The product of the conception may escape through the ostium 
 abdominale or the walls of the tube may rupture, a violent hemorrhage resulting. 
 
 Pelvic peritonitis is a not uncommon 'sequence of tubal disease. Salpingitis is inflarnmation 
 of the mucous coat of the tube— interstitial salpingitis of the middle coat, perisalpingitis of the 
 peritoneal coat. 
 
 If inflammation closes the uterine and the abdominal ends of the tube, mucus gathers and dis- 
 tends the tube {hydrosalpinx). If purulent matter gathers, the condition is known as pyosalpinx. 
 
 An ovary may fail to descend and remain well above the pelvic brim ; it may prolapse mto 
 Douglas's pouch; it may enter the sac of a hernia; it may inflame; a turnor or cyst may arise from 
 it. A solid tumor of the ovarv may be a fibroma, a sarcoma, or a carcinoma. " Cysts may orig- 
 inate in anv part of the tubo-ovarian structure; as the cortical, medullary, or parenchymatous 
 portions of' the ovary; in the structure between the tube and ovary known as the Rosenmuller 
 organ or parovarian'structures; and in the hydatid of Morgagni."i Cysts may be simple, pro- 
 liferating, or dermoid; unilocular or multildcular. Glandular proliferous cysts, papillary pro- 
 
 1 Text-book of Gynecology. By E. E. Montgomery. 
 
1504 THE FE3IALE ORGANS OF GENERATION 
 
 Hferous cysts, dermoid cysts, and parovarian cysts may attain a large or even an enormous size. 
 The operation for the removal of an ovarian cyst is one of the most successful of the major 
 procedures of surgery. 
 
 THE MAMMARY GLAND (MAMMA) (Figs. 1107, 1108, 1109, 1110). 
 
 The breasts, mammaxy glands or mammae secrete the milk, and are accessory 
 glands of the generative system. They develop fully in the female, but remain 
 permanently rudimentary in the male. There are two of these glands, and 
 they are situated in the superficial fascia of the anterior portion of the thorax. 
 Between the two glands and in front of the sternum is a groove, the bosom. 
 
 Description of a Well-developed Breast. — Each gland appears as a hemispher- 
 ical body projecting from the front of the thorax beneath the skin and lying over 
 a portion of the Pectoralis major muscle and a smaller portion of the Serratus 
 magnus muscle. The hemispherical projection extends usually from the margin 
 of the sternum to the axilla and from the level of the second rib to the level of 
 the sixth rib, or from the third rib to the seventh rib, but this does not represent 
 the real size of the gland. The gland is much larger than this, being rendered 
 so by tails or prolongations of breast tissue, which will be described later (p. 1505). 
 
 The Nipple (papilla mammae) (Figs. 1107, 1108, 1109, an;l 1110).— The nipple 
 projects from a little below and to the median side of the summit of the hemi- 
 sphere at or above the level of the fifth rib, and is covered with thin skin. The 
 right nipple may not exactly correspond in situation and direction to the left 
 nipple. The nipple varies considerably in height and shape. In the virgin it is 
 usually cylindrical and is directed forward and slightly upward and outward. 
 The apex of the nipple is rendered rough by fissures (Fig. 1107), it exhibits a 
 depression in which are the openings of the milk ducts (Fig. 1109), and its cir- 
 cumference is thrown into concentric ridges (Fig. 1109). The nipple is surrounded 
 by a darker circular wrinkled area, the areola (areola mammae) (Figs. 1107 and 
 1108), in which are sweat-glands and on which are twelve or fifteen small 
 rounded elevations. These elevations are caused by cutaneous sebaceous glands 
 which in structure represent a transition betvveen sebaceous and mammary glands. 
 They are probai)ly rudimentary portions of the mammary gland and are known 
 as the glands of Montgomery (glandulae areolares) (Fig. 1109). The color of the 
 nipple and areola varies with the complexion of the individual. In brunettes it is 
 darker than in blondes. The usual color of the nipple in a young woman is rosy- 
 pink, the areola being of a darker shade. During the early months of pregnancy 
 the nipple and areola become dark brown in color, the areola becomes larger in 
 circumference and the glands of Montgomery increase in size (Fig. 1110). The 
 nipple contains non-striated muscle and mechanical irritation or sexual excitement 
 makes it stiff and erect. The skin covering the breast is clear, soft, and delicate, 
 and subcutaneous veins are often visible. The skin of the nipple and areola is 
 particularly delicate. 
 
 Variations in the Mammae. — Before puberty the glands are small, of the infantile 
 type, grow slowly, and differ but slightly from the male organs. The nipple is 
 small and flat and pale. At puberty the increase in the size of the breast is rapid 
 and considerable, due to growth of gland tissue and of subcutaneous fat. During 
 pregnancy the breasts enlarge greatly and remain very large throughout lactation. 
 This enlargement is due to new gland tissue and increased vascularity. Numerous 
 blue veins are visible in the skin, the areola darkens, and the glands of Mont- 
 gomery enlarge (Fig. 1110). During lactation the associated lymphatic glands may 
 enlarge (A. Marmaduke Sheild). After the termination of lactation the breasts 
 diminish in size. They do not become as small as the virgin breast, are apt to lose 
 their hemispherical outlines, and cease to be soft. They droop as flaccid pendulous 
 
THE 3fA3IMABY GLAND 
 
 1505 
 
 masses, the subcutaneous fat is largely gone, and the outlines of the lobular breast 
 tissue can be seen and felt. The nipple is long and hangs down like a teat. At 
 the menopause the breast usually shrinks. In some cases, however, it actually 
 increases in size. In such a case, although the gland atrophies, there is an exten- 
 sive deposit of fat. In old age the glands undergo atrophy and largely disappear, 
 the skin is flabby and thrown into wrinkles, and the breasts contain very little 
 glandular structure, and are hard from the presence of fibrous tissue. The nipples 
 become pigmented and corrugated. Women vary greatly in the development of 
 the breasts. In some women they are large, firm, and well proportioned; in others 
 they are small, flat, or atrophy occurs in the course of certain bodily diseases, as 
 phthisis, and certain mental diseases, as melancholia. If the ovaries are ill- 
 developed the breasts remain flat and small. In newly married women, even 
 though pregnancy does not exist, the breasts often develop decidedly and rapidly. 
 The outline and direction of the breast and also of the nipple may be altered by 
 corsets. The left mamma is usually somewhat larger than the right. 
 
 Nipple. 
 
 ■Areola. 
 
 Lactiferous 
 duct. 
 
 Lobule unravelled 
 
 Ampulla. 
 
 / 
 Lobule 
 
 Locidi in connective tissue. 
 Fig. 1107. — Dissection of the lower half of the female breast during the period of lactation. (From Luschka.) 
 
 One gland or both glands may be entirely absent, the nipple being also absent. 
 One or both glands may be absent, one or both nipples being present. When there 
 is only one nipple, it is apt to be the left. The term polymazia (mammae acces- 
 soriae muliehris) means the presence of supernumerary breasts, with or without 
 nipples. Polythelia means the presence of supernumerary nipples, the associated 
 glandular structure being rudimentary. There may be one, two, or several super- 
 numerary breasts, and when more than one exists, are usually asymmetrical. If 
 one is functionally active, it enlarges during pregnancy and furnishes milk. 
 
 Supernumerary mammae may secrete milk or may be without function. The 
 most common situation is on the part of the chest below and to the inner side of 
 the normally placed gland. They may also exist in the axilla, the abdomen, the 
 groin, the back, and the thigh. Many cases of supposed supernumerary glands 
 have been really instances in which moles, warts, or sebaceous cysts have been 
 mistaken for breast tissue, but some cases are undoubted. 
 
 95 
 
1506 THE FEMALE ORGANS OF GENERATION 
 
 Prolongations of Mammary Tissue. — As previously stated, the outlines of 
 the breast are not regular, but here and there tails, prolongations, or cusps come off 
 
 CLAVICLC- 
 
 PCCTORAUIS MAJOR 
 
 FIBROUS SEPTUM 
 GLAND SUBSTANCE 
 
 ADIPOSE TISSUE 
 
 THIRD RIB 
 
 AREOLAR TISSUE 
 
 FIRST 
 RIB 
 
 SECOND 
 
 RIB 
 ECTORALIS 
 MINOR 
 INTERCOSTALES 
 SHEATH OF PEC- 
 TORALIS MAJOR 
 
 UPERFICIAL 
 FASCIA 
 
 LUNG 
 
 ADIPOSE TISSUE 
 HORIZONTAL PLANE 
 OF NIPPLE 
 
 FIFTH RIB 
 
 SIXTH RIB 
 
 Fig. 1108. — Right breast in sagittal section, inner surface of outer segment. (Testut.) 
 
 from and are true portions of the gland. Two or even more prolongations pass to 
 the edge of the sternum; others pass toward the axilla, the clavicle, and the origin 
 
 SECONDARY ARLOLA 
 
 CONCENTRIC , 
 RIDGES I 
 
 Fig 1109. — Nipple and areola of a virgin. (Testut.) 
 
 Fig. 1110. — Nipple and areolae of a preg- 
 nant woman. (Testut.) 
 
 of the external oblique muscle from the ribs. Underneath the mammary gland 
 prolongations of mammary tissue penetrate the pectoral fascia (Heidenhain). 
 
THE MAM3IABY GLAND 
 
 1507 
 
 If one of the glandular cusps is of considerable size it is called an outlying 
 lobule. 
 
 Structure of Mammary Gland and Nipple (Figs. 11 07 and 1 108) .—The glands of 
 the breast ( cor p?^« mammae) rest by a smooth posterior surface upon the loose pectoral 
 fascia, which fastens the breast to the muscle beneath, but so loosely that the breast 
 is movable. The mamma consists of gland-tissue; of fibrous tissue, connecting its 
 lobes, of fatty tissue in the intervals between the lobes, of retinacula, and of skin. 
 The gland-tissue, when freed from fibrous tissue and fat, is of a pale reddish color, 
 firm in texture, in general circular in form, with prolongations here and there, flat- 
 tened from before backward, thicker in the centre than at the circumference, and 
 presenting several inequalities on its surface, especially in front. On the anterior 
 surface there are many irregular elevated processes with deep spaces between 
 them. From the summits of the elevations connective-tissue strands (retinacula 
 evils) pass to the true skin. The glandular structure consists of numerous lobes 
 (lohi mammae), and these are composed of lobules (lobuli mammae), connected 
 together by areolar tissue, blood-vessels, and ducts. The smallest lobules con- 
 sist of a cluster of rounded alveoli (Fig. 1107), which open into the smallest 
 branches of the excretory ducts; these ducts, uniting, form larger ducts, which 
 terminate in single canals. Each canal is called a lactiferous, galactophorus or 
 mammillary duct (ductus lactiferu^) (Fig. 1107). Each lobe possesses one lac- 
 tiferous duct. This passes to the apex of the lobe and then into the nipple. 
 The lactiferous ducts are white and cord-like, and contrast with the yellowish- 
 red tissue of the gland itself. The number of excretory ducts varies from fifteen 
 to twenty. They converge toward the areola, beneath which each duct forms 
 a spindle-shaped dilatation, the ampulla (sinus lactiferans) (Fig. 1107). The 
 ampullae serve as reservoirs for the milk. At the base of the nipple the ducts 
 become contracted and pursue a straight course to its summit, perforating it by 
 separate orifices considerably narrower than the ducts themselves. Each orifice 
 (porus lactiferu^) is the orifice of a tube which drains an individual lobe. The 
 ducts are composed of areolar tissue, with longitudinal and transverse elastic 
 fibres; muscular fibres are entirely absent; their mucous lining is continuous, at 
 the point of the nipple, with the integument. The epithelium of the mammary 
 gland differs according to the state of activity of the organ. In the gland of a woman 
 who is not pregnant or nursing the alveoli are very small and solid, being filled 
 with a mass of granular polyhedral cells. During pregnancy the alveoli enlarge 
 and the cells undergo rapid multiplication. At the commencement of lactation 
 the cells in the centre of an alveolus undergo fatty degeneration, and are elim- 
 inated in the first milk as colostrum-corpuscles. The peripheral cells of the alveolus 
 remain, and form a single layer of granular, short columnar cells lining the limit- 
 ing membrana propria. The single nucleus of each cell divides and forms two. 
 In the protoplasm, especially in the end of the cells toward the alveolus, 
 drops of fat appear, and the nucleus toward this end of the cell also becomes 
 fatty. 
 
 The end of the cell toward the alveolus breaks down, and the liberated mate- 
 rial constitutes " the albuminous ingredients of the milk, while the drops of fat 
 become the milk-globules. The portion of the cell which remains forms new 
 cytoplasm, and the same process is repeated over and over again. The cells 
 also secrete water and the salts which are found in the milk."^ 
 
 The fibrous tissue (Fig. 1108) invests the entire surface of the breast, and sends 
 down septa between its lobes, connecting them together. 
 
 The fatty tissue (Figs. 1107 and 1108) surrounds the surface of the gland and 
 occupies the interval between its lobes. It usually exists in considerable abun- 
 
 1 Human Physiology. By Joseph Howard Raymond. 
 
1508 
 
 THE FEMALE ORGANS OF GENERATION 
 
 dance, and determines the form and size of the gland. There is no fat immediately 
 beneath the areola and nipple. 
 
 Fig. 1111. — The lymphatic vessels of the anterior surface of the bieast; the subareolar plexus and the 
 trunks which run from it. (tjappey.) 
 
 DELTA- PECTORAL HUMERAL CHAIN 
 
 — MAMMARY LYMPHATIC 
 ENDING IN SUB- 
 CLAVIAN GLANDS 
 
 THORACIC 
 CHAIN 
 
 MAMMARY COL- 
 LECTING TRUNKS 
 
 SUBAREOLAR 
 
 PLEXUS 
 
 CUTANEOUS COLLECTING 
 
 TRUNK FROM THE 
 
 THORACIC WALL 
 
 CUTANEOUS COL- ^^ "VV- COLLECTING TRUNKS 
 
 LECTING TRUNKS \ V PASSING TO INTERNAL 
 
 MAMMARY GLANDS 
 
 Fig. 1112. — Lymphatics of the breast and axillary glands. (Poirier and Charpy.) 
 
 Vessels and Nerves. — The arteries supplying the mammary gland are derived 
 from the perforating branches of the internal mammary, long thoracic branches of the 
 
THE MAM3IARY GLAND 1509 
 
 axillary, and branches from the intercostals. The veins describe an anastomotic 
 circle around the base of the nipple, called by Haller the circulus venosus. From 
 this large branches transmit the blood to the circumference of the gland and end 
 in the axillary and internal mammary veins. The lymphatics of the mammary 
 gland (Figs. 1111 and 1112) and mammary region have been previously described 
 (pp. 812,813, and 814). The nerves are derived from the fourth, fifth, and sixth 
 intercostal nerves, and sympathetic filaments from the dorsal cord pass to the breast 
 along the branches of the intercostal nerves. 
 
 Surgical Anatomy. — Occasionally the mammary gland undergoes enormous hypertrophy. 
 This may occur at any age, even in the virgin. The physiological enlargement of puberty may 
 become excessive or the physiological enlargement of pregnancy and lactation may continue 
 and increase after the termination of lactation. The chief elements in the enlargement are fat 
 and connective tissue, and it is doubtful if there is extensive reproduction of glandular tissue. 
 
 Abscess of the breast may occur at any age, but is most common by far in nursing women. 
 The portals are opened to infection by a crack in the nipple and bacteria are carried inward 
 by the lymph- vessels. In some cases the pus gathers beneath the skin (supra-mammary abscess), 
 in others in the breast tissue (intra-mammary abscess). In rare cases pus gathers beneath the 
 breast (^retro-mammary abscess). In intra-mammary abscess the pus burrows through the 
 fibrous septa or fascia and forms numerous channels, and such a channel is constricted at the 
 point where it passes through fascia or a fibrous septum, as an hour-glas,'' is constricted. 
 
 In every patient suffering from abscess the nipple should be examined for a sore or crack, and 
 the area when found should be treated antiseptically. A supra-mammary abscess should be 
 opened by an incision radiating from the nipple. 
 
 In intra-mammary abscess follow the advice of Sheild: open the abscess by an incision radiating 
 from the nipple, insert the index finger, and when possible pass it to the bottom of the abscess 
 and carry the tip from the depths of the abscess to as near the surface as possible. At this point 
 make a counter opening. The finger breaks down septa which cause constriction and thus con- 
 verts the tracking sinuses into one large cavity.' Drain by tubes. 
 
 A retro-mammary abscess is opened by an incision, following the outline of the breast at the 
 thoraco-mammary junction, the finger being pushed through the incision and up under the gland. 
 
 Tuberculosis of the breast may occur, and if it does, cold abscess is apt to form. The best 
 treatment is removal of the gland and the associated lymph glands. 
 
 Chronic mastitis is a condition of mammary fibrosis, most common in neurotic single women, 
 and apt to be associated with ovarian or uterine disease. 
 
 Malignant dermatitis or Paget's disease of the nipple is a chronic condition consisting of 
 epithelial proliferation, induration, desquamation, and ulceration, and it is apt to be followed 
 by epithelioma. 
 
 Chancre of the nipple is occasionally met with. 
 
 Secondary and tertiary syphilitic lesions are seen upon the skin of the breast, the nipple, and 
 the areola. 
 
 Cysts and tumors are common in the breast. 
 
 There may be cystic degeneration of the gland in women near the menopause (involution 
 cysts); a lacteal cyst; a hydatid cyst; an adenoma may become cystic. 
 
 The nipple may suffer from epithelioma, myoma, myxoma, angioma, papilloma, or fibroma. 
 
 The innocent tumors of the breast are fibro-adenoma, cystic adenoma, myxoma, and angioma. 
 
 The skin of the breast may suffer from any form of growth or cyst which could arise from 
 the skin of another part. Malignant tumors of the glandular structure are ten times as frequent 
 as innocent tumors. Sarcoma is rare; carcinoma is very common. 
 
 Carcinoma of the breaM has occupied much of the attention of surgeons during recent years. 
 The old operation was uniformly followed by recurrence. The modern radical operation has 
 been evolved from the studies of Moore, the younger Gross, Heidenhain, Stiles, Banks, Halsted, 
 and others. The modern operation always removes at least the skin and subcutaneous tissue 
 over the hemispherical portion of the breast, the outlying lobules of the breast, the pectoral fascia, 
 and the sternal portion of the great Pectoral muscle, the lymphatic tracts from the breast, the 
 lymphatic glands and cellular tissue from the axilla, and from beneath the latissimus dorsi muscle. 
 The pectoral fascia and the sternal portion of the great Pectoral muscle must come away in eveiy 
 case, because breast tissue may pass through the fascia. The entire breast must be removed, 
 because even in a recent case the entire breast is regarded as infected. The clavicular portion 
 of the great Pectoral muscle is anatomically distinct from the sternal portion arid its removal is 
 not imperative. Some operators remove the lesser Pectoral muscle. To leave it is of no value to 
 the arm, and it frequently causes an annoying rigid band anterior to the axilla. To take it away 
 
 1 Diseases of the Breast. By A. Marmaduke Sheild. 
 
1510 THE FEMALE ORGANS OF GENERATION 
 
 gives ready access to the axillary vessels at a desirable point above. The sheath of the axillary 
 vein should be removed with the glands and cellular tissue of the axilla. The glands receiving 
 lymph from the cancerous area must be removed, of course. In view of the fact that in an 
 undetermined percentage of cases a lymph tract passes direct to the subclavian glands, it is 
 evident that these glands may become infected by this route instead of, as is more usual, secondarily 
 to axillary infection; hence it seems wiser in every case to remove the cellular tissue and glands 
 from the subclavian triangle. All of these structures should be removed as one piece, in order 
 to avoid cutting across lymph tracts and flooding the wound with carcinoma cells which might 
 adhere, grow, and reproduce cancer. 
 
 Halsted's operation is the method adopted by most surgeons. The wound cannot be com- 
 pletely closed, and the raw spot is covered at once or later with Thiersch skin grafts. (For sur- 
 gical considerations regarding the lymphatics in mammary carcinoma see page 814.) 
 
 The Male Breast {mamma virilis). — The male breast is a small flat struc- 
 ture, consisting chiefly of connective tissue, but containing some branched tubules. 
 Un 'er normal circumstances it remains permanently of the infantile type. It 
 possesses a nipple which is much smaller than that of the female breast, and 
 which usually lies over the fourth intercostal space, but may lie over the fourth or 
 fifth rib. The nipples of the two sides are rarely placed quite symmetrically. 
 Accessory glands and accessory nipples are as common among males as females. 
 The male breast may exhibit some evidence of temporary functional activity at birth 
 and at puberty. Cases have been recorded of actual lactation by the male breast. 
 
 Surgical Anatomy. — The male breasts may undergo enormous hypertrophy (gynaecomazia). 
 In these cases the penis is often small and the testicles may be atrophied. The breasts may 
 be absent in the male. Disease of the male breast is not nearly so frequent as disease of the 
 female breast. The organ may be the seat of syphilis, tuberculosis, acute or chronic mastitis, 
 abscess or tumor. A number of cases of cancer of the male breast have been recorded. 
 
THE SUEGICAL ANATOMY OF INGUINAL 
 HEKNIA AND FEMORAL HEENIA. 
 
 Dissection (Fig. 288). — For dissection of the parts concerned in inguinal hernia a male 
 subject, free from fat, should always be selected. The liody should be placed in the supine 
 position, the abdomen and pelvis raised by means of blocks placed beneath them, and the lower 
 extremities rotated outward, so as to make the parts as tense as possible. If the abdominal walls 
 are flaccid, the cavity of the abdomen should be inflated through an aperture made at the umbil- 
 icus. An incision should be made along the middle line from a little below the umbilicus to 
 the symphysis pubis, and continued along the front of the scrotum, and a second incision from 
 the anterior superior spine of the ilium to just below the umbilicus. These incisions should 
 divide the integument, and the triangular-shaped flap included between them should be reflected 
 downward and outward, when the superficial fascia will be exposed. 
 
 The Superficial Fascia of the Abdomen (p. 433). — This, over the greater part of 
 the abdominal wall, consists of a single layer of fascia, which contains a variable 
 amount of fat ; but as it approaches the groin it is easily divisible into two layers, 
 between which are found the superficial vessels and nerves and the superficial 
 inguinal lymphatic glands. 
 
 The Superficial Layer of the Superficial Fascia or the Fascia of Camper is thick, 
 areolar in texture, containing adipose tissue in its meshes, the quantity of which 
 varies in different subjects. Below, it passes over Poupart's ligament, and is con- 
 tinuous with the outer layer of the superficial fascia of the thigh. In the male this 
 fascia is continued over the penis and over the outer surface of the cord to the 
 scrotum, where it helps to form the dartos. As it passes to the penis, and over the 
 cord to the scrotum it changes its character, becoming thin, destitute of adipose 
 tissue, and of a pale reddish color; and in the scrotum it acquires some involuntary 
 muscular fibres. From the scrotum it may be traced backward, to be continuous 
 with the superficial fascia of the perinseum. In the female this fascia is continued 
 into the labia majora. 
 
 The hypogastric branch of the ilio-hjrpogastric nerve perforates the aponeurosis 
 of the External oblique muscle about an inch above and a little to the outer side of 
 the external abdominal ring, and is distributed to the integument of the hypogas- 
 tric region. 
 
 The ilio-inguinal nerve escapes at the external abdominal ring, and is distributed 
 to the integument of the upper and inner part of the thigh, to the scrotum in the 
 male and to the labium in the female. 
 
 The superficial epigastric artery arises from the femoral about half an inch 
 below Poupart's ligament, and, passing through the saphenous opening in the fascia 
 lata, ascends on to the abdomen, in the superficial fascia covering the External 
 oblique muscle, nearly as high as the umbilicus. It distributes branches to the 
 superficial inguinal lymphatic glands, the superficial fascia, and the integument, 
 anastomosing with branches of the deep epigastric and internal mammary 
 arteries. 
 
 The superficial circumflex iliac artery, the smallest of the cutaneous branches, 
 arises close to the preceding, and, piercing the fascia lata, runs outward, parallel 
 with Poupart's ligament, as far as the crest of the ilium, dividing into branches 
 which supply the superficial inguinal lymphatic glands, the superficial fascia, and 
 
 ( 1511 ) 
 
1512 
 
 THE SURGICAL ANATOMY OF HERNIA 
 
 the integument, anastomosing with the deep circumflex iliac and with the gluteal 
 and external circumflex arteries. 
 
 POUPART-S INTERCOLUMNAR 
 
 LIGAMENT FIBRES 
 
 FEMORAL 
 RING 
 
 GIMBERNAT-S. 
 LIGAMENT 
 
 SAPHENOUS 
 
 OPENING 
 
 FEMORAL 
 
 VEIN 
 
 LONG- 
 
 SAPHENOUS 
 
 VEIN 
 
 EXTERNAL 
 •ABDOMINAL 
 RING 
 
 _CRUS 
 SUPERIOR 
 
 Fig. 1113. — Right external abdominal ring and saphenous opening in the male. (Spalteholz.) 
 
 , EXTERNAL OBLIQUE 
 
 vreflected downward) 
 
 EXTERNAL OBLIQUE 
 
 (reflected inward) 
 
 POSTERIOR WALL OF 
 INGUINAL CANAL 
 
 INTERNAL ORIGIN 
 OF CRENASTER 
 
 Fig. 1114.— Right inguinal canal in the male. Second layer viewed from in front. (Spalteholz.) 
 
APONEUROSIS OF THE EXTERNAL OBLIQUE MUSCLE 1513 
 
 The superficial external pudic (superior) artery arises from the inner side of 
 the femoral artery close to the preceding vessels, and, after passing through the 
 saphenous opening, courses inward across the spermatic cord, to be distributed to 
 the integument on the lower part of the abdomen, the penis and scrotum in the male, 
 and the labium in the female, anastomosing with branches of the internal pudic. 
 
 The Superficial Veins. — The veins accompanying these superficial vessels are 
 usually much larger than the arteries; they terminate in the internal saphenous vein. 
 
 The superficial inguinal lymphatic glands are placed immediately beneath the 
 integument, are of large size, and vary from ten to twenty in number (p. 793). 
 
 INTERNAL OBLIQUE 
 
 (reflected inward) 
 
 INTERNAL 
 OBLIQUE 
 
 EXTERNAL OBLIQUE 
 
 (reflected inward) 
 
 POSTERIOR 
 WALL 
 
 triangular 
 "fascia 
 
 Fig. 1115.— The right inguinal canal in the male. Third layer viewed from in front. (Spalteholz.) 
 
 The Deep Layer of the Superficial Fascia, the Fascia of Scarpa or the Fascia of Cooper 
 (p. 433) is thinner and more membranous in character than the superficial layer. 
 In the middle line it is intimately adherent to the linea alba; above, it is continuous 
 with the superficial fascia over the rest of the trunk ; below, it blends with the fascia 
 lata of the thigh a little below Poupart's ligament ; below and internally, in the male, 
 it is continued over the penis and over the outer surface of the cord to the scrotum, 
 where it helps to form the dartos. From the scrotum it may be traced backward 
 to be continuous wath the base of the triangular ligament of the urethra. In the 
 female it is continuous with the labia majora. 
 
 The scrotum is a cutaneous pouch which contains the testes and part of the 
 spermatic cords, and into which an inguinal hernia frequently descends. 
 
 The Aponeurosis of the External Oblique Muscle (Fig. 1113). — This is a thin 
 but strong membranous aponeurosis, the fibres of which are directed obliquely 
 downward and inward. That portion of the aponeurosis which extends between 
 
1514 1HE SURGICAL ANATOMY OF HERNIA 
 
 the anterior superior spine of the ilium and the spine of the os pubis is a broad 
 band, folded inward and continuous below with the fascia lata; it is called Poupart's 
 ligament (Figs. 289, 1113, 1116, 1117, 1119, 1124, 1125). The portion which is 
 reflected from Poupart's ligament at the spine of the os pubis, along the pectineal 
 line, is called Gimbemat's ligament (Fig. 297, 340, 1113, 1124, 1125). A thin fibrous 
 band extends from the inner end of Poupart's ligament and Gimbernat's ligament 
 upward and inward behind the inner pillar of the external ring to the anterior 
 layer of the rectus sheath. The fibres diverge as they ascend. This band is 
 known as the triangular fascia or Co lies 's fascia or the triangular ligament of CoUes 
 (Figs. 1115 and 1119). 
 
 The External or Superficial Abdominal Ring {anmilus inguinalis subcutaneus) 
 (Figs. 289 and 1113). — Just above and to the outer side of the crest of the os pubis 
 an interval is seen in the aponeurosis of the External oblique, called the external 
 abdominal ring. This aperture is oblique in direction, somewhat triangular in 
 form, and corresponds with the course of the fibres of the aponeurosis. It usually 
 measures from base to apex about an inch, and transversely about half an inch. 
 It is bounded below by the crest of the os pubis; above, by a series of curved 
 fibres, the intercolumnar fibres, which pass across the upper angle of the ring, so as 
 to increase its strength; and on either side by the margins of the opening in the 
 aponeurosis, which are called the columns or pillars of the ring. 
 
 The External Pillar, which at the same time is inferior {crus injerius), from the 
 obliquity of its direction, is the stronger; it is formed by that portion of Poupart's 
 ligament which is inserted into the spine of the os pubis ; it is curved, so as to form 
 a kind of groove, upon which the spermatic cord rests. 
 
 The Internal or Superior Pillar {criis superius) is a broad, thin, flat band, which 
 is attached to the front of the body of the os pubis, interlacing with its fellow of 
 the opposite side in front of the symphysis pubis, that of the right side being 
 superficial. 
 
 The external abdominal ring gives passage to the spermatic cord in the male 
 and round ligament in the female; it is much larger in men than in women, on 
 account of the large size of the spermatic cord, hence the great frequency of inguinal 
 hernia in men. 
 
 The Intercolumnar Fibres (fibrae intercrurales) (Fig. 1113) are a series of curved 
 tendinous fibres which arch across the lower part of the aponeurosis of the Exter- 
 nal oblique. They have received their name from stretching across between the 
 two pillars of the external ring ; they increase the strength of the lower part of the 
 aponeurosis and prevent the divergence of the pillars from one another. They 
 are thickest below, where they arise from Poupart's ligament, and they are 
 inserted into the linea alba, describing a curve, with the convexity downward. 
 They are much thicker and stronger at the outer angle of the external ring than 
 internally, and are more strongly developed in the male than in the female. 
 These intercolumnar fibres, as they pass across the external abdominal ring, are 
 themselves connected together by delicate fibrous tissue, thus forming a fascia 
 which, as it is attached to the pillars of the ring, covers it in, and is called the 
 intercolumnar fascia. This intercolumnar fascia is continued downward as a 
 tubular prolongation around the outer surface of the cord and testis, and encloses 
 them in a distinct sheath; hence, it is also called the external spermatic fascia. 
 The sac of an inguinal hernia in passing through the external abdominal ring 
 receives an investment from the intercolumnar fascia. 
 
 If the finger is introduced a short distance into the external ring and the limb 
 is then extended and rotated outward, the aponeurosis of the External oblique, 
 together with the iliac portion of the fascia lata, will be felt to become tense and 
 the external ring much contracted; if the limb is, on the contrary, flexed upon the 
 pelvis and rotated inward, this aponeurosis will become lax, and the external ring 
 
THE TRIANGULAR FASCIA OF THE ABDOMEN 1515 
 
 sufficiently enlarged to admit the finger with comparative ease; hence the patient 
 should always be put in the latter position when the taxis is applied for the reduc- 
 tion of an inguinal hernia, in order that the abdominal walls may be relaxed as 
 much as possible. 
 
 The aponeurosis of the External oblique should be removed by dividing it across in the same 
 direction as the external incisions, and reflecting it downward and outward; great care is requisite 
 in separating it from the aponeurosis of the muscle beneath. The lower part of the Internal 
 obHque and the Cremaster are then exposed, together with the inguinal canal, which contains 
 the spermatic cord (Fig. 1116). The mode of insertion of Poupart's and Gimbernat's ligaments 
 into the os pubis should also be examined. 
 
 Poupart's Ligament (ligamentum inguinale [Pouparti]) (Figs. 289, 1113,1116,1117, 
 1 1 19, 1 124, and 1 125) or the crural arch is the lower border of the aponeurosis of the 
 External oblique muscle, which extends from the anterior superior spine of the ilium 
 to the spine of the os pubis. From this latter point it is reflected outward to be 
 attached to the pectineal line for about half an inch, forming Gimbernat's ligament. 
 Its general direction is curved down- 
 ward toward the thigh, where it is con- 
 tinuous with the fascia lata. Its outer 
 half is rounded and oblique in direc- 
 tion; its inner half gradually widens at 
 its attachment to the os pubis, is more 
 horizontal in direction, and lies be- 
 neath the spermatic cord. 
 
 Gimbernat's Ligament (ligamentum 
 lacunare [Gimbernati]) (Figs. 289, 297, 
 340, 1113, 1124, and 1125) is that por- 
 tion of the aponeurosis of the External 
 oblique muscle which is reflected up- 
 ward and outward from the spine of 
 the OS pubis to be inserted into the 
 pectineal line. It is about half an 
 inch in length, larger in the male than 
 in the female, almost horizontal in 
 direction in the erect posture, and of a 
 triangular form, with the base directed 
 outward. Its base or outer margin is 
 concave, thin, and sharp, and lies in 
 contact with the femoral sheath, form- 
 ing the inner boundary of the femoral 
 ling (Fig. 1124). Its apex corresponds 
 to the spine of the os pubis. Its pos- 
 terior margin is attached to the pec- 
 tineal line, and is continuous with the 
 pubic portion of the fascia lata. Its anterior margin is continuous with Poupart's 
 ligament. 
 
 The Triangular Fascia of the Abdomen, CoUes's Fascia or the Triangular Ligament 
 of Colles (ligamentum inguinale reflexum [Collesi]) (Fig. 1115, 1116, and 1119) is a 
 band of tendinous fibres, of a triangular shape, which is attached by its apex to 
 the inner end of Poupart's ligament and to Gimbernat's ligament. It passes 
 inward beneath the spermatic cord, and expands into a somewhat fan-shaped 
 fascia, lying behind the inner pillar of the external abdominal ring and in front 
 of the conjoined tendon, and interlaces with the ligament of the other side at the 
 linea alba in the anterior layer of the sheath of the Rectus muscle. 
 
 Fig. 1116. — Inguinal hernia. Dissection showing the 
 Internal oblique and Cremaster. 
 
1516 THE SURGICAL ANATOMY OF HERNIA 
 
 The Ligament of Cooper.— See Fig. 297 and p. 437. 
 
 The Internal Oblique Muscle (Figs. 1114, 1115, and 1116) has been previously- 
 described (p. 437). The part which is now exposed is pardy muscular and partly 
 tendinous in structure. Those fibres which arise from Poupart's ligament, few in 
 number and paler in color than the rest, arch downward and inward across the 
 spermatic cord, and, becoming tendinous, are inserted, conjointly with those of 
 the Transversalis, into the crest of the os pubis and pectineal line, forming what 
 is known as the conjoined tendon of the Internal oblique and Transversalis (Figs. 
 1116 and 1117). This tendon is inserted immediately behind the inguinal canal 
 and external abdominal ring, serving to protect what would otherwise be a weak 
 point in the abdominal wall. The conjoined tendon is sometimes divided into 
 an outer and an inner portion, the former being called the ligament of Hessel- 
 bach (ligamentum interjoveolare) (Fig. 292), and the latter the ligament of Henle 
 (Fig. 292). Sometimes the conjoined tendon is insufficient to resist the pressure 
 from within, and is carried forward in front of the protrusion through the exter- 
 nal ring, forming one of the coverings of direct inguinal hernia, or the hernia 
 forces its way through the fibres of the conjoined tendon. 
 
 The Oremaster (Figs. 1114 and 1116) is derived from the lower margin of the 
 Internal oblique, of which muscle it is in reality a portion. It is a thin muscular 
 layer composed of a number of fasciculi. It arises by a thick external bundle of 
 fibres from the upper portion of Poupart's ligament, being connected with the 
 Internal oblique muscle and also occasionally with the Transversalis. It arises 
 also by a thin inner bundle of fibres from the anterior layer of the rectus 
 sheath. 
 
 The thick bundle of origin is on the lateral surface; the thin bundle is on the 
 medial surface of the spermatic cord. The Cremaster passes along with the 
 spermatic cord, and descends with it through the external ring. Upon the front and 
 sides of the cord both bundles spread out upon the vaginal tunic of the testicle 
 and epididymis, and form a series of loops which differ in thickness and length 
 in different subjects. These loops are united together by areoh:r tissue, and 
 form a thin covering over the cord and testis, the cremasteric fascia (fascia 
 cremasterica) . 
 
 It will be observed that the Cremaster is a separated portion of the Internal 
 oblique. This fact affords an easy explanation of the manner in which the testicle 
 and cord are invested by this muscle. At an early period of foetal life the testis is 
 placed at the lower and back part of the abdominal cavity, but during its descent 
 toward the scrotum, which takes place before birth, it passes beneath the arched 
 border of the Internal oblique. In its passage beneath this muscle some fibres 
 are derived from its lower part, which accompany the testicle and cord into the 
 scrotum. 
 
 It occasionally happens that the loops of the Cremaster surround the cord, some 
 lying behind as well as in front. It is probable that under these circumstances 
 the testis in its descent passes through, instead of beneath, the fibres of the Internal 
 oblique. 
 
 In the descent of an oblique inguinal hernia, which takes the same course as 
 the spermatic cord, the Cremaster muscle forms one of its coverings. This muscle 
 becomes largely developed in cases of hydrocele and large old scrotal herniae. No 
 such muscle exists in the female, but an analogous structure is developed in those 
 cases where an oblique inguinal hernia descends beneath the margin of the Internal 
 oblique. 
 
 The Internal oblique should be detached from Poupart's ligament, separated from the Trans- 
 versalis to the same extent as in the previous incisions, and reflected inward on to the sheath 
 of the Rectus (Fig. 1117). The deep circumflex iliac vessels, which lie between these two muscles, 
 form a valuable guide to their separation. 
 
THE INGUINAL OB SPERMATIC CANAL 
 
 1517 
 
 The Transversalis Muscle (Figs. 1115 and 1117) has been previously described 
 (p. 442). The part which is now exposed is partly muscular and partly tendinous 
 in structure ; it arises from the outer third of Poupart's ligament, its fibres curve 
 downward and inward, and are inserted, together with those of the Internal 
 oblique, into the lower part of the linea alba, into the crest of the os pubis and 
 the pectineal line, forming what is known as the conjoined tendon of the Internal 
 oblique and Transversalis (Figs. 1116 and 1117). The falx aponeurotica [inguinalis] 
 is a collection of fibres of tendinous consistence in the inner side of the Trans- 
 versalis insertion. Between the lower border of this muscle and Poupart's 
 ligament a space is left in which is seen the transversalis fascia. 
 
 The Inguinal or Spermatic Canal {canalis inguinalis) (Figs. 1114, 1115, and 1117) 
 contains the spermatic cord in the male and the round ligament in the female. It 
 is an oblique canal, about an inch and a half in length, directed downward and 
 inward and placed parallel with, and a little above, Poupart's ligament. It com- 
 mences above at the internal or deep abdominal ring, which is the point where 
 
 Epigastric artery. 
 
 Fig. 1117. — Inguinal hernia. 
 
 Dissection showing the Transversalis muscle, the transversalis fascia, 
 and the internal abdominal ring. 
 
 the cord enters the inguinal canal, and terminates below at the external or super- 
 ficial ring. It is bounded, in front, by the integument and superficial fascia, by 
 the aponeurosis of the External oblique throughout its whole length, and by the 
 Internal oblique for its outer third; behind, by the triangular fascia, the conjoined 
 tendon of the Internal oblique and Transversalis, transversalis fascia, and the 
 subperitoneal fat and peritoneum; above, by the arched fibres of the Internal 
 oblique and Transversalis; below, by the union of the transversalis fascia with 
 Poupart's ligament. That form of hernia in which the intestine follows the course 
 of the spermatic cord along the inguinal canal is called oblique inguinal hernia. 
 
 On the posterior wall of the inguinal canal is seen the band of fibres known as 
 the ligament of Hesselbach (ligamentum interfoveolare [Hesselbachi]) (Fig. 292). 
 It is placed in front of the deep epigastric artery. The fibres come from the 
 external portion of the lower fibres of the conjoined tendon (Fig. 1116) and pass 
 
1518 THE SURGICAL ANATOMY OF HERNIA 
 
 downward for a distance, some of them then passing outward and upward, some 
 of them downward and inward to the inner surface of Poupart's Hgament. 
 
 The Transversalis Fascia (Figs. 297, 1117, and 1125) is a thin aponeurotic mem- 
 brane which lies between the inner surface of the Transversalis muscle and the 
 peritoneum. It forms part of the general layer of fascia whicli lines the interior 
 of the abdominal and pelvic cavities, and is directly continuous with the iliac 
 and pelvic fasciae. 
 
 In the inguinal region the transversalis fascia is thick and dense in structure, 
 and joined by fibres from the aponeurosis of the Transversalis muscle; but it 
 becomes thin and cellular as it ascends to the Diaphragm. Below, it has the 
 following attachments; external to the femoral vessels it is connected to the 
 posterior margin of Poupart's ligament, and is there continuous with the iliac 
 fascia. Internal to the vessels it is thin, and attached to the os pubis and pectineal 
 line behind the conjoined tendon, with which it is united; and, corresponding to 
 the points where the femoral vessels pass into the thigh, this fascia descends in 
 front of them, forming the anterior wall of the femoral sheath. The spermatic cord 
 in the male and the round ligament in the female pass through this fascia; the 
 point where they pass through is called the internal or deep abdominal ring. This 
 opening is not visible externally, owing to a prolongation of the transversalis fascia 
 on the structures forming the infiindibuliform fascia. 
 
 The Internal or Deep Abdominal Ring (annulus inguinalis ahdcminalis) (Figs. 297 
 and 1117j is situated in the transversalis fascia, midway between the anterior superior 
 spine of the ilium and symphysis pubis, and about half an inch above Poupart's 
 ligament. It is of an oval form, its long diameter being directed upward and 
 downward; it varies in size in different subjects, and is much larger in the male 
 than in the female. It is bounded above and externally by the arched fibres of 
 the Transversalis muscle, below and internally by the deep epigastric vessels. It 
 transmits the spermatic cord in the male and the round ligament in the female. 
 From its circumference, a thin, funnel-shaped membrane, the infundibuliform fascia, 
 is continued around the cord and testis, enclosing them in a distinct pouch (Fig. 
 1117). When the sac of an oblique inguinal hernia passes through the internal or 
 deep abdominal ring, the infundibuliform fascia constitutes one of its coverings. 
 
 The Subperitoneal Areolar Tissue or the Fascia Propria of Cooper. — Between the 
 transversalis fascia and the peritoneum is a quantity of loose areolar tissue. In 
 some subjects it is of considerable thickness and loaded with adipose tissue. 
 Opposite the internal ring it is continued around the surface of the cord, forming 
 a loose sheath for it. 
 
 The Deep Epigastic Artery (Figs. 292 and 1118) arises from the external iliac 
 artery a few lines above Poupart's ligament. It at first descends to reach this liga- 
 ment, and then ascends obliquely along the inner margin of the internal or deep 
 abdominal ring, lying between the transversalis fascia and the peritoneum, and 
 passing upward pierces the transversalis fascia and enters the sheath of the Rectus 
 muscle by passing over the semilunar fold of Douglas. Consequently the deep 
 epigastric artery bears a very important relation to the internal abdom.inal ring 
 as it passes obliquely upward and inward from its origin from the external iliac. 
 In this part of its course it lies along the lower and inner margin of the internal 
 ring and beneath the commencement of the spermatic cord. At its commence- 
 ment it is crossed by the vas deferens in the male and by the round ligament in 
 the female. 
 
 The Peritoneum (Fig. 1118), corresponding to the inner surface of the internal 
 ring, presents a well-marked depression, the depth of which varies in different 
 subjects. A thin fibrous band is continued from it along the front of the cord 
 for a variable distance, and becomes ultimately lost, the ligament of Cloquet. 
 This is the remains of the pouch of peritoneum which, in the foetus, precedes 
 
THE PERITONEUM 
 
 1519 
 
 the cord and testis into the scrotum, the obliteration of which commences soon 
 after birth. In some cases the fibrous band can only be traced a short distance, 
 but occasionally it may be followed, as a fine cord, as far as the upper end of the 
 tunica vaginalis. Sometimes the tube of peritoneum is closed only at intervals 
 and presents a sacculated appearance, or a single pouch may extend along the 
 whole length of the cord, which may be closed above, or the pouch may be directly 
 continuous with the peritoneum by an opening at its upper part. 
 
 In the female foetus the peritoneum is also prolonged in the form of a tubular 
 process for a short distance into the inguinal canal. This process is called the 
 canal of Nuck. It is generally obliterated in the adult, but sometimes it remains 
 pervious even in advanced life. 
 
 M. iliacus 
 
 External 
 inguinal 
 fossa. 
 
 iliac ^^^^Kl_2i;^_^ r, xStSi^Mi^^T^l^f^ fn 
 
 vein. ^^^■■H^.v-.^ 6 t.ADDER\ -..>r*7'»^ ^ ■' , 
 
 I nor vesical 
 
 artery. 
 
 ^Middle inguinal 
 
 fossa. 
 
 J.ntenial iiKjuim' 
 
 fo 
 
 Fig. 1118. — Posterior view of the anterior abdominal wall in its lower half. The peritoneum is in place, 
 and the various cords are shining through. (After Joessel.) 
 
 In order to understand the relation of the peritoneum to inguinal hernia, it is 
 necessary to view the anterior abdominal wall from its internal aspect, when it will 
 be seen as shown in Fig. 1 1 18. Between the upper margin of the front of the 
 pelvis and the umbilicus, the peritoneum, when viewed from behind, will be seen 
 to be raised into five vertical folds, with intervening depressions, by more or less 
 prominent bands which converge to the umbilicus. One of these is situated in the 
 median line, and is caused by the urachus, the remnant of the allantois; it extends 
 from the summit of the bladder to the umbilicus. The fold of peritoneum covering 
 it is known as the fold of the urachus or the plica urachi (plica umbilicalis media). 
 On either side of this is a prominent band, caused by the obliterated hypogastric 
 artery, which extends from the side of the bladder obliquely upward and inward 
 to the umbilicus. This is covered by a fold of peritoneum which is known as the 
 
1520 THE SURGICAL ANATOMY OF HEBNIA 
 
 hypogastric fold or the plica hypogastrica {'plica umhilicalis lateralis). To either 
 side of these three cords is the deep epigastric artery, which ascends obliquely 
 upward and inward from a point midway between the symphysis pubis and the 
 anterior superior spine of the ilium to the semilunar fold of Douglas, in front of 
 which it disappears. It is covered by a fold of peritoneum which is known as the 
 plica epigastrica. Between these raised folds are depressions of the peritoneum, 
 constituting so-called fossae. The most internal, between the plica urachi and the 
 plica hypogastrica, is known as the internal inguinal fossa {fovea supravesicalis). 
 The middle one is situated between the plica hypogastrica and the plica epigas- 
 trica, and is termed the middle inguinal fossa {fovea inguinalis mesialis). The 
 external one is external to the plica epigastrica, and is known as the external 
 inguinal fossa {fovea inguinalis lateralis). Occasionally the deep epigastric artery 
 corresponds in position to the obliterated hypogastric artery, and then there is but 
 one fold on each side of the middle line, and the two external fossae are merged 
 into one. In the usual condition of the parts the floor of the external inguinal 
 fossa corresponds to the internal abdominal ring, and into this fossa an oblique 
 inguinal hernia descends. To the inner side of the plica epigastrica are the 
 two internal fossae, and through either of these a direct hernia may descend, as 
 will be explained in the sequel (p. 1523). The whole of this space, that is to 
 say, the space between the deep epigastric artery, the margin of the Rectus and 
 Poupart's ligament, is commonly known as Hesselbach's triangle. These three 
 depressions or fossae are situated above the level of Poupart's ligament, and in 
 addition to them is another below the ligament, corresponding to the position of 
 the femoral ring, and into which a femoral hernia descends. 
 
 INGUINAL HERNIA. 
 
 Inguinal hernia is that form of protrusion which makes its way through the 
 abdomen in the inguinal region. 
 
 There are two principal varieties of inguinal hernia — external or oblique, and 
 internal or direct. 
 
 External or oblique inguinal hernia, the more frequent of the two, takes the 
 same course as the spermatic cord. It is called external from the neck of the sac 
 being on the outer or iliac side of the deep epigastric artery. 
 
 Internal or direct inguinal hernia does not follow the same course as the cord, 
 but protrudes through the abdominal wall on the inner or pubic side of the deep 
 epigastric artery. 
 
 Oblique Inguinal Hernia. 
 
 In oblique inguinal hernia (Fig. 1118) the intestine or omentum escapes from the 
 abdominal cavity at the internal ring. Before it is a pouch of peritoneum, which 
 forms the hernial sac (Fig. 1119, A). This pouch of peritoneum is invested by the 
 subserous areolar tissue, and is enclosed in the infimdibuliform process of the trans- 
 versalis fascia, which it receives as it enters the inguinal canal. In passing along the 
 inguinal canal the hernia displaces upward the arched fibres of the Transversalis and 
 Internal oblique muscles, and is imperfectly surrounded by the fibres of the Cre- 
 master muscles, the coat being completed by the cremasteric fascia. It then passes 
 along the front of the cord, and escapes from the inguinal canal at the external 
 ring, receiving an investment from the intercolumnar fascia. Lastly, it descends 
 into the scrotum, receiving coverings from the superficial fascia and the integument. 
 ^ The coverings of this form of hernia, after it has passed through the external 
 ring, are, from without inward, the integument, superficial fascia, intercolumnar 
 
OBLIQUE INGUINAL HEBNIA 
 
 1521 
 
 fascia, Cremaster muscle and fascia, infundibuliform fascia, subserous areolar 
 tissue, and peritoneum. 
 
 This form of hernia lies in front of the vessels of the spermatic cord and seldom 
 extends below the testis, on account of the intimate adhesion of the coverings 
 of the cord to the tunica vaginalis (Fig. 1120, A). 
 
 The seat of stricture in a strangulated oblique inguinal hernia is either at the 
 external ring, in the inguinal canal, caused by the fibres of the Internal oblique 
 or Trans versalis; or at the internal ring, most frequently in the latter situation. 
 If it is situated at the external ring, the division of a few fibres at one point of 
 its circumference is all that is necessary for the replacement of the hernia. If 
 in the inguinal canal or at the internal ring, it may be necessary to divide the 
 
 Fig. 1119. 
 
 -Oblique inguinal hernia, showing its various coverings. (From a preparation in the 
 Museum of the Royal College of Surgeons.) 
 
 aponeurosis of the External oblique so as to lay open the inguinal canal. In 
 dividing the stricture the direction of the incision should be upward. 
 
 When the hernia passes along the inguinal canal and escapes from the external 
 ring into the scrotum, the condition is called complete oblique inguinal or scrotal 
 hernia (Fig. 1120, A). If the hernia does not escape from the external ring, but is 
 retained in the inguind canal, the condition is called incomplete inguinal hernia or 
 bubonocele. In each of these cases the coverings which invest the intestine cr 
 omentum will depend upon the extent to which it descends in the inguinal canal. 
 
 There are some other varieties of oblique inguinal hernia depending upon con- 
 genital defects in the processus vaginalis. The testicle in its descent from the 
 abdomen into the scrotum is preceded by a pouch of peritoneum, which about 
 
 96 
 
1522 
 
 THE SURGICAL ANATOMY OF HERNIA 
 
 the period of birth becomes shut off from the general peritoneal cavity by a closure 
 of that portion of the pouch which extends from the internal abdominal ring to 
 
 — 1 Sac of hernia. 
 
 Tallica 
 vaginalis.'' 
 
 A. Common scrotal hernia. 
 
 Tunica 
 ■—-vaginalis. 
 
 B Congenital hernia. 
 
 Sac of ^__ 
 hernia. 
 
 --Sac of hernia. 
 
 Tunica 
 'vaginalis. 
 
 Tunica vaginalis.~\~-M^^ 
 
 )f hernia. 
 
 E. Hernia into the funicular process. 
 Fig. 1120. — Varieties of oblique inguinal hernia 
 
 near the upper part of the testicle, the lower portion of the pouch remaining per- 
 sistent as the tunica vaginalis. It would appear that this closure commences at 
 
DIRECT INGUINAL HERNIA 
 
 1523 
 
 two points — viz., at the internal abdominal ring and at the top of the epididymis 
 — and gradually extends until, in the normal condition, the whole of the inter- 
 vening portion is converted into a fibrous cord. From failure in the completion 
 of this process variations in the relation of the hernial protrusion to the testicle 
 and tunica vaginalis are produced, which constitute distinct varieties of inguinal 
 hernia, and which have received separate names and are of surgical importance. 
 These are congenital, infantile, encysted, and hernia of the funicular process. 
 
 Congenital Hernia (Fig. 1120, B). — Where the congenital pouch of peritoneum 
 which precedes the cord and testis in its descent remains patent throughout and 
 is unclosed at any point, the cavity of the tunica vaginalis communicates directly 
 with the cavity of the peritoneum. The intestine descends along this pouch into 
 the cavity of the tunica vaginalis, which constitutes the sac of the hernia, and the 
 gut lies in contact with the testicle. 
 
 Infantile and Encysted Hernia.— Where the congenital pouch of peritoneum 
 is occluded at the internal ring only, but remains patent throughout the rest of 
 its extent, two varieties of oblique inguinal hernia may be produced, which have 
 received the names of infantile and encysted hernia. In the infantile form (Fig. 
 1120, C) the septum which closed the congenital sac above and the peritoneum 
 in its immediate neighborhood yields and forms a sac, which descends behind the 
 tunica vaginalis, so that in front of the bowel there are three layers of perito- 
 neum, the two layers of the tunica vaginalis and the layer of the proper hemial 
 sac. In the encysted form (Fig. 1120, D) yielding occurs in the same position as 
 in the infantile form — namicly, at the occluded spot in the pouch — and a sac forms 
 which projects into and not behind the tunica vaginalis, as in the infantile form, 
 and thus it constitutes a sac within a sac, so that in front of the bowel there are two 
 layers of peritoneum — one layer of the tunica vaginalis and one of true hemial sac. 
 
 Hernia into the Funicular Process (Fig. 1120, £).— Where the congenital 
 pouch of peritoneum is occluded at the lower point only — that is, just above the 
 testicle — the intestine descends into the pouch of peritoneum as far as the testicle, 
 but is prevented from entering the sac of the tunica vaginalis by the septum which 
 has formed between it and the pouch, so that it resembles the congenital form in 
 all respects, except that, instead of enveloping the testicle, that body can be felt 
 below the rupture. 
 
 Direct Inguinal Hernia. 
 
 In direct inguinal hernia the protrusion makes its way through some part of 
 the abdominal wall internal to the epigastric artery. 
 
 At the lower part of the abdominal wall is a triangular space, Hesselbach's 
 triangle, bounded externally by the deep epigastric artery, internally by the 
 margin of the Rectus muscle, below by Poupart's ligament (Fig. 1118). The con- 
 joined tendon is stretched across the inner two-thirds of this space, the remaining 
 portion of the space having only the subperitoneal areolar tissue and the trans- 
 versalis fascia between the peritoneum and the aponeurosis of the External oblique 
 muscle. 
 
 In some cases the hernial protrusion escapes from the abdomen on the outer 
 side of the conjoined tendon, pushing before it the peritoneum, the subserous 
 areolar tissue, and the trans versalis fascia. It then enters the inguinal canal, 
 passing along nearly its whole length, and finally emerges from the external ring, 
 receiving an investment from the intercolumnar fascia. The coverings of this 
 form of hernia are precisely similar to those investing the oblique form, with the 
 insignificant difference that the infundibuliform fascia is replaced by a portion 
 derived from the general layer of the transversalis fascia. 
 
 In other cases — and this is the more frequent variety — the hernia is either forced 
 through the fibres of the conjoined tendon or the tendon is gradually distended in 
 
1524 ^^^ SURGICAL ANATOMY OF HERNIA 
 
 front of it so as to form a complete investment for it. The intestine then enters 
 the lower end of the inguinal canal, escapes at the external ring lying on the 
 inner side of the cord, and receives additional coverings from the superficial fascia 
 and the integument. This form of hernia has the same coverings as the oblique 
 variety, excepting that the conjoined tendon is substituted for the Cremaster, and 
 the infundibuliform fascia is replaced by a portion derived from the general layer 
 of the trans versalis fascia. 
 
 The difference between the position of the neck of the sac in these two forms 
 of direct inguinal hernia has been referred, with some probability, to a difference 
 in the relative positions of the obliterated hypogastric artery and the deep epi- 
 gastric artery. When the course of the obliterated hypogastric artery corre- 
 sponds pretty nearly with that of the deep epigastric the projection of these 
 arteries toward the cavity of the abdomen produces two fossae in the peritoneum. 
 The bottom of the external fossa of the peritoneum corresponds to the position of 
 the internal abdominal ring, and a hernia which distends and pushes out the peri- 
 toneum lining this fossa is an oblique hernia. When, on the other hand, the 
 obliterated hypogastric artery lies considerably to the inner side of the deep epi- 
 gastric artery, corresponding to the outer margin of the conjoined tendon, it divides 
 the triangle of Hesselbach into two parts, so that three depressions will be seen on 
 the inner surface of the lower part of the abdominal wall — viz., an external one on 
 the outer side of the deep epigastric artery; a middle one, between the deep epi- 
 gastric and the obliterated hypogastric arteries; and an internal one, on the inner 
 side of the obliterated hypogastric artery (pp. 1519 and 1520). In such a case 
 a hernia may distend and push out the peritoneum forming the bottom of either 
 fossa. These fossae are the inguinal fossae. When the hernia distends and 
 pushes out the peritoneum forming the botton of the external fossa, it is an 
 oblique or external inguinal hernia. 
 
 When the hernia distends and pushes out the peritoneum forming the bottom 
 of either the middle or the internal fossa, it is a direct or internal hernia. 
 
 The anatomical difference between these two forms of direct or internal inguinal 
 hernia is that, when the hernia protrudes through the middle fossa — that is, 
 the fossa between the deep epigastric and the obliterated hypogastric arteries — 
 it will enter the upper part of the inguinal canal ; consequently its coverings will be 
 the same as those of an oblique hernia, with the insignificant difference that the 
 infundibuliform fascia is replaced by a portion derived from the general layer of 
 the transversalis fascia, whereas when the hernia protrudes through the internal 
 fossa it is either forced through the fibres of the conjoined tendon or the tendon is 
 gradually distended in front of it so as to form a complete investment for it. The 
 intestine then enters the lower part of the inguinal canal, and escapes from the 
 external abdominal ring lying on the inner side of the cord. 
 
 This form of hernia has the same coverings as the oblique variety, excepting 
 that the conjoined tendon is substituted for the Cremaster, and the infundibuli- 
 form fascia is replaced by a portion derived from the general layer of the fascia 
 transversalis. 
 
 The seat of stricture in strangulation in both varieties of direct hernia is most 
 frequently at the neck of the sac or at the external ring. In that form of hernia 
 which perforates the conjoined tendon it not unfrequently occurs at the edges of 
 the fissure through which the gut passes. In dividing the stricture the incision 
 should in all cases be directed upward.^ 
 
 If the hernial protrusion passes into the inguinal canal, but does not escape 
 
 1 In all cases of inguinal hernia, whether oblique or direct, it is proper to divide the stricture directly upward: 
 the reason of this is obvious, for by cutting in this direction the incision is made parallel to the deep epigastric 
 artery — either external to it in the oblique variety, or internal to it in the direct form of hernia — and thus all 
 chance of wounding the vessel is avoided. If the incision was made outward, the artery might be divided if the 
 hernia was direct; and if made inward, the vessel would stand an equal chance of injury if the case was one of 
 oblique inguinal hernia. — Ed. of 15th English edition. 
 
FEMORAL HERNIA 
 
 1525 
 
 from the external abdominal ring, it forms what is called incomplete direct hernia. 
 This form of hernia is usually of small size, and in corpulent persons is very 
 difficult of detection. 
 
 Direct inguinal hernia is of much less frequent occurrenee than the oblique, 
 their comparative frequency being, according to Cloquet, as one to five. It occurs 
 far more frequently in men than in women, on account of the larger size of the 
 external ring in the former sex. It differs from the oblique in its smaller size and 
 globular form, dependent most probably on the resistance offered to its progress 
 by the transversalis fascia and conjoined tendon. It differs also in its position, 
 being placed over the os pubis and not in the course of the inguinal canal. The 
 deep epigastric artery runs on the outer or iliac side of the neck of the sac, and the 
 spermatic cord along its external and posterior side, not directly behind it, as in 
 oblique inguinal hernia. 
 
 FEMORAL HERNIA. 
 
 The dissection of the parts comprised in the anatomy of femoral hernia should be performed, 
 if possible, upon a female subject free from fat. The subject should lie upon the back; a block 
 is first placed under the pelvis, the thigh everted, and the knees slightly bent and retained in 
 this position. An incision should then be made from the anterior superior spinous process of 
 the ilium along Poupart's ligament to the symphysis pubis; a second incision should be carried 
 transversely across the thigh about six inches beneath the preceding; and these are to be con- 
 nected together by a vertical one carried along the inner side of the thigh (Fig. 340). These 
 several incisions should divide merely the integument; this is to be reflected outward, when the 
 superficial fascia will be exposed. 
 
 The Superficial Fascia forms a continuous layer over the whole of the thigh, 
 consisting of areolar tissue, containing in its meshes much fat, and capable of being 
 separated into two or more layers, between which are found the superficial vessels 
 and nerves. It varies in thickness in different parts of the limb. In the groin 
 it is thick, and the two layers are separated from one another by the superficial 
 inguinal lymphatic glands, the internal saphenous vein, and several smaller 
 vessels. One of these layers, the superficial, is continuous with the superficial 
 fascia of the abdomen. 
 
 The superficial layer should be detached by dividing it across in the same direction as the 
 external incisions; its removal will be facilitated by commencing at the lower and inner angle of 
 the space, detaching it at first from the front of the internal saphenous vein, and dissecting it 
 off from the anterior surface of that vessel and its tributaries; it should then be reflected out- 
 ward in the same manner as the integument. The cutaneous vessels and nerves and superficial 
 inguinal glands are then exposed, lying upon the deep layer of the superficial fascia. These are 
 the internal saphenous vein and the superficial epigastric, superficial circumflex iliac, and super- 
 ficial external pudic vessels, as well as numerous lymphatics, ascending with the saphenous vein 
 to the inguinal glands. 
 
 The internal or long saphenous vein (Figs. 1121, 1122, and 1123) ascends along 
 the inner side of the thigh, and, passing through the saphenous opening in the 
 fascia lata, terminates in the femoral vein about an inch and a half below Poupart's 
 ligament (Fig. 1113). This vein receives at the saphenous opening the superficial 
 epigastric, the superficial circumflex iliac, and the superficial external pudic veins. 
 
 The superficial external pudic artery (superior) arises from the inner side of 
 the femoral artery, and, after passing through the saphenous opening, courses 
 inward across the spermatic cord, to be distributed to the integument on the 
 lower part of the abdomen, the penis and scrotum in the male and the labium in 
 the female, anastomosing with branches of the internal pudic. 
 
 The superficial epigastric artery arises from the femoral about half an inch 
 below Poupart's ligament, and, passing through the saphenous opening in the 
 fascia lata, ascends on to the abdomen, in the superficial fascia covering the 
 External oblique muscle, nearly as high as the umbilicus. It distributes branches 
 
1526 
 
 THE SURGICAL ANATOMY OF HERNIA 
 
 to the superficial inguinal lymphatic glands, the superficial fascia, and the integu- 
 ment, anastomosing with branches of the deep epigastric and internal mammary 
 arteries. 
 
 The superficial circumflex iliac artery, the smallest of the cutaneous branches, 
 arises close to the preceding, and, piercing the fascia lata, runs outward, parallel 
 with Poupart's ligament, as far as the crest of the ilium, dividing into branches 
 which supply the superficial inguinal lymphatic glands, the superficial fascia, and 
 the integupient of the groin, anastomosing with the deep circumflex iliac, and with 
 the gluteal and external circumflex arteries. 
 
 The Superficial Veins (Fig. 1121). — The veins accompanying these superficial 
 arteries are usually much larger than the arteries; they terminate in the internal 
 or long saphenous vein at the saphenous opening. 
 - The superficial inguinal lymphatic glands. — See p. 793. 
 
 Fig. 1121. — Femoral hernia. Superficial dissection. 
 
 The ilio-inguinal nerve arises from the first lumbar nerve. It escapes at the 
 external abdominal ring, and is distributed to the integument of the upper and 
 inner part of the thigh — ^to the scrotum in the male and to the labium in the 
 female. The size of this nerve is in inverse proportion to that of the ilio-hypo- 
 gastric nerve. Occasionally it is very small, and ends by joining the ilio-hypogastric ; 
 in such cases a branch of the ilio-hypogastric takes the place of the ilio-inguinal, 
 or the latter nerve may be altogether absent. The crural branch of the genito- 
 crural nerve passes along the inner margin of the Psoas muscle, beneath Poupart's 
 ligament, into the thigh, entering the sheath of the femoral vessels, and lying 
 
FEMORAL HERNIA 
 
 1527 
 
 superficial and a little external to the femoral artery. It pierces the anterior layer 
 of the sheath of the vessels, and, becoming superficial by passing through the fascia 
 lata, it supplies the skin of the anterior aspect of the thigh as far as midway 
 between the pelvis and knee. On the front of the thigh it communicates w^ith 
 the outer branch of the middle cutaneous nerve, derived from the anterior crural. 
 The Deep Layer of the Superficial Fascia is a very thin fibrous layer, best marked 
 on the inner side of the long saphenous vein and below Poupart's ligament. It is 
 placed beneath the subcutaneous vessels and nerves, and upon the surface of the 
 fascia lata, to which it is intimately adherent at the lower margin of Poupart's 
 ligament. It covers the saphenous opening in the fascia lata, is closely united to 
 its circumference, and is connected to the sheath of the femoral vessels corre- 
 
 FiG. 1122. — Femoral hernia, showing fascia lata and saphenous opening. 
 
 sponding to its under surface. The portion of fascia covering this aperture is 
 perforated by the internal saphenous vein and by numerous blood- and lymphatic 
 vessels; hence it has been termed the cribriform fascia, the openings for these 
 vessels having been likened to the holes in a sieve. The cribriform fascia adheres 
 closely both to the superficial fascia and to the fascia lata, so that it is described 
 by some anatomists as a part of the fascia lata, but it is usually considered (as in 
 this work) as belonging to the superficial fascia. It is not till the cribriform fascia 
 has been cleared away that the saphenous opening is seen, so that this opening 
 does not in ordinary cases exist naturally, but is the result of dissection (p. 513). A 
 femoral hernia in passing through the saphenous opening receives the cribriform 
 fascia as one of its coverings. 
 
1528 
 
 THE SURGICAL ANATOMY OF HERNIA 
 
 The deep layer of superficial fascia, together with the cribriform fascia, having 
 been removed, the fascia lata is exposed. 
 
 The Fascia Lata has been already described with the muscles of the front of 
 the thigh (p. 513). At the upper and inner part of the thigh, a little below 
 Poupart's ligament, a large oval-shaped aperture is observed after the superficial 
 fascia has been cleared away; it transmits the internal saphenous vein and other 
 smaller vessels, and is called the saphenous opening (Fig. 1113). In order the 
 more correctly to consider the mode of formation of this aperture, the fascia lata in 
 this part of the thigh is described as consisting of two portions, an iliac portion and 
 a pubic portion. 
 
 Fig. 1123. — Femoral hernia. Iliac portion of fascia lata removed, and sheath of femoral vessels and 
 
 femoral canal exposed. 
 
 The iliac portion (Fig. 11 22) is all that part of the fascia lata on the outer side of 
 the saphenous opening. It is attached externally to the crest of the ilium and its 
 anterior superior spine; to the whole length of Poupart's ligament; and to the 
 pectineal line in conjunction with Gimbernat's ligament. From the spine of the 
 OS pubis it is reflected downward and outward, forming an arched margin, the 
 outer boundary or falciform process or superior comu (cornu superius) (Fig. 1122) 
 of the saphenous opening. This margin overlies and is adherent to the anterior 
 layer of the sheath of the femoral vessels; to its edge is attached the cribriform 
 fascia, and below it is continuous with the pubic portion of the fascia lata. 
 
 The pubic portion of the fascia lata or the pectineal fascia (Fig. 1122) is situated 
 at the inner side of the saphenous opening; at the lower margin of this aperture 
 it is continuous with the iliac portion; traced upward, it covers the surface of 
 the Pectineus, Adductor longus, and Gracilis muscles; and, passing behind the 
 
FEMORAL HERNIA I529 
 
 sheath of the femoral vessels, to which it is locsely united, is continuous with 
 the sheath ot the Psoas and Iliacus muscles, and is attached above to the ilio- 
 pectmeal hne, where it becomes continuous with the fascia covering the Iliacus 
 muscle From the description it may be observed that the iliac portion of the 
 fascia lata passes m front of the femoral vessels and the pubic portion behind 
 them, so that an apparent aperture consequently exists between the two, through 
 which the internal saphenous vein joins the femoral vein. 
 
 The Saphenous Opening {jossa ovalis) (Figs. 1113, 1121, 1122, and 1123) is an 
 oval-shaped aperture measuring about an inch and a half in length and half an 
 inch in width. It is situated at the upper and inner parts of the front of the 
 thigh, below Pouparts ligament, and is directed obliquely downward and out- 
 ward. It is covered by the cribriform fascia {jascia- cribrosa), a portion of the 
 deep layer of the superficial fascia of the thigh, and which extends from the 
 falciform margin to the pubic portion of the fascia lata or the pectineal fascia. 
 
 The outer margin of the saphenous opening is of a semilunar form, thin, strong, 
 sharply defined, and lies on a plane considerably anterior to the inner margin! 
 If this edge is traced upward, it will be seen to form a curved elongated process, 
 the falciform process or superior comu (Fig. 1122), which ascends in front of the 
 femoral vessels, and, curving inward, is attached to Poupart's ligament and to the 
 spine of the os pubis and pectineal line, where it is continuous with the pubic por- 
 tion. If traced downward, it is found continuous with another curved margin, 
 the concavity of which is directed upward and inward; this is the inferior cornu 
 of the saphenous opening, and is blended with the pubic portion of the fascia 
 lata covering the Pectineus muscle. 
 
 The inner boundary of the opening (Figs. 1113 and 1122) is on a plane posterior 
 to the outer margin and behind the level of the femoral vessels; it is much less 
 prominent and defined than the outer, from being stretched over the subjacent 
 Pectineus muscle. It is through the saphenous opening that a femoral hernia 
 passes after descending along the crural canal. 
 
 If the finger is introduced into the saphenous opening while the limb is moved 
 in different directions, the aperture will be found to be greatly constricted on 
 extending the limb or rotating it outward, and to be relaxed on flexing the limb 
 and inverting it; hence the necessity for placing the limb in the latter position in 
 employing the taxis for the reduction of a femoral hernia. 
 
 The iliac portion of the fascia lata, but not its falciform process, should now be removed by 
 detaching it from the lower margin of Poupart's ligament, carefully dissecting it from the sub- 
 jacent structures, and turning it inward, when the sheath of the femoral vessels is exposed, 
 descending beneath Poupart's ligament (Fig. 1123). 
 
 Poupart's Ligament (ligamentum inguinale [Pouparti]) (Figs. 289, 1113, 1116, 
 1117, 1119,1122, 1123, 1124, and 1125) is the lower border of the aponeurosis 
 of the External oblique muscle, which extends from the anterior superior spine 
 of the ilium to the spine of the os pubis. From this latter point it is reflected 
 outward, to be attached to the pectineal line for about half an inch, forming 
 Gimbemat's ligament. Its general direction is curved downward toward the thigh, 
 where it is continuous with the fascia lata. Its outer half is rounded and 
 oblique in direction. Its inner half gradually widens at its attachment to the 
 OS pubis, is more horizontal in direction, and lies beneath the spermatic cord. 
 Nearly the whole of the space included between Pcupart's ligament and the 
 innominate bone is filled in by the parts which descend from the abdomen into 
 the thigh (Figs. 297, 340, and 1124). The outer half of the space (lacuna muscu- 
 lorum) is occupied by the Iliacus and Psoas muscles, together with the external 
 cutaneous and anterior crural nerves. The pubic half of the space (lacuna 
 vasorum) is occupied by the femoral vessels included in their sheath, a small oval- 
 shaped interval existing between the femoral vein and the inner wall of the sheath, 
 
1530 
 
 THE SURGICAL ANATOMY OF HERNIA 
 
 which is occupied merely by a little loose areolar tissue, a few lymphatic vessels, 
 and occasionally by a small lymphatic gland; this is the femoral ring, through 
 which the gut descends in femoral hernia. The part of Poupart's ligament in 
 front of the femoral or crural ring is called the superficial crural arch. 
 
 Gimbemat's Ligament (ligamentum lacunare [Gimbernati]) (Figs. 297,340, 1113, 
 1124, an 1 1125) is that part of the aponeurosis of the External oblique muscle 
 which is reflected backward and outward from the spine of the os pubis, to be 
 inserted into the pectineal line. It is about half an inch in length, larger in the 
 male than in the female, almost horizontal in direction in the erect posture, and 
 of a triangular form, with the base directed outward. Its base or outer margin 
 is concave, thin, and sharp, and lies in contact with the femoral sheath. Its 
 apex corresponds to the spine of the os pubis. Its posterior margin is attached to 
 the pectineal line, and is continuous with the pubic portion of the fascia lata. Its 
 anterior margin is continuous with Poupart's ligament. 
 
 External 
 Crural 
 
 branch Anterior crural, 
 of genito- 
 
 Poupart's ligament 
 
 cutaneous nerve. 
 
 Iliac portion of 
 fascia lata 
 
 Femoral vein. 
 Femoi al t ing. 
 
 Gtmbet naf s 
 liqament 
 
 Femoral arte^-T 
 Fig. 1124. — Structures which pass beneath the crural arch. 
 
 Femoral Sheath (Fig. 1124) . — The femoral or crural sheath is a continuation down- 
 ward of the fasciae that line the abdomen, the transversalis fascia passing down in 
 front of the femoral vessels, and the iliac fascia descending behind them; these 
 fasciae are directly continuous on the iliac side of the femoral artery, but a small 
 space exists between the femoral vein and the point where they are continuous on 
 the pubic side of that vessel,which constitutes the femoral or crural canal (Fig. 11 13). 
 The femoral sheath is closely adherent to the contained vessels about an inch 
 below the saphenous opening, being blended with the areolar sheath of the vessels, 
 but opposite Poupart's ligament it is much larger than is required to contain them; 
 hence the funnel-shaped form which it presents. The outer border of the sheath 
 
FEMORAL HERNIA 
 
 1531 
 
 is perforated by the genito-cniral nerve. Its inner border is pierced by the internal 
 saphenous vein and numerous lymphatic vessels. In front it is covered by the 
 iliac portion of the fascia lata; and behind it is the pubic portion of the same 
 fascia. 
 
 If the anterior wall of the sheath is removed (Fig. 1113), the femoral artery and 
 vein are seen lying side by side, a thin septum separating the two vessels, while 
 another septum may be seen lying just internal to the vein, and cutting off a small 
 space between the vein and the inner wall of the sheath. The septa are stretched 
 between the anterior and posterior walls of the sheath, so that each vessel is 
 enclosed in a separate compartment. The interval left between the vein and the 
 inner wall of the sheath is not filled up by any structure, excepting a little loose 
 areolar tissue, a few lymphatic vessels, and occasionally by a small lymphatic 
 gland; this is the femoral or crural canal (Fig. 1113), through which the intestine 
 descends in femoral hernia. 
 
 Deep Crural Arch, — Passing across the front of the femoral sheath on the abdom- 
 inal side of Poupart's ligament, and closely connected with it, is a thickened band 
 of fibres of the transversalis fascia, called the deep crural arch. It is apparently a 
 thickening of the transversalis fascia, joining externally to the centre of Poupart's 
 ligament, and arching across the front of the crural sheath, to be inserted by a 
 broad attachment into the pectineal line behind the conjoined tendon. In some 
 subjects this structure is not very prominently marked, and not infrequently it is 
 altogether wanting. The superficial crural arch is the portion of Poupart's liga- 
 ment in front of the femoral ring. 
 
 The Femoral or Crural Canal (canalis femoralis) (Figs. 297, 340, and 1113) is the 
 narrow interval between the femoral vein and the inner wall of the femoral sheath. 
 It exists as a distinct canal only when the sheath has been separated from the vein 
 by dissection or by the pressure of a hernia or tumor. Its length is from a quarter 
 to half an inch, and it extends from the femoral ring to the upper part of the 
 saphenous opening. 
 
 Its anterior wall is very narrow, and formed by a continuation downward of 
 the transversalis fascia, under Poupart's ligament, covered by the falciform 
 process of the fascia lata. 
 
 Its posterior wall is formed by a continuation downward of the iliac fascia cover- 
 ing the pubic portion of the fascia lata. 
 
 Its outer wall is formed by the fibrous septum separating it from the inner side 
 of the femoral vein. 
 
 Its inner wall is formed by the junction of the processes of the transversalis 
 and iliac fasciae, which form the inner side of the femoral sheath, and lies in 
 contact at its commencement with the outer edge of Gimbernat's ligament. 
 
 This canal has two orifices— an upper one, the femoral or crural ring, closed by 
 the septum crurale; and a lower one, the saphenous opening, closed by the cribri- 
 form fascia. 
 
 The femoral or crural ring (annulus femoralis) (Figs. 1113, 1124, and 1125) is 
 the upper opening of the femoral canal, and leads into the cavity of the abdomen. 
 It is bounded in front by Poupart's ligament and the deep crural arch; behind, 
 by the os pubis, covered by the Pectineus muscle and the pubic portion of the fascia 
 lata; internally, by the base of Gimbernat's ligament, the conjoined tendon, the 
 transversalis fascia, and the deep crural arch; externally, by the fibrous septum 
 lying on the inner side of the femoral vein. The femoral ring is of an oval form; 
 its long diameter, directed transversely, measures about half an inch, and it is 
 larger in the female than in the male, which is one of the reasons of the greater 
 frequency of femoral hernia in the former sex. 
 
 Position of Parts around the Ring. — The spermatic cord in the male and 
 round ligament in the female lie immediately above the anterior margin of the 
 
1532 
 
 THE SURGICAL ANATOMY OF HERNIA 
 
 femoral ring, and may be divided in an operation for femoral hernia if the incision 
 for the relief of the stricture is not of limited extent. In the female this is of little 
 importance, but in the male the spermatic artery and vas deferens may be divided. 
 
 The femoral vein lies on the outer side of the ring. 
 
 The deep epigastric artery in its passage upward and inward from the external 
 iliac artery passes across the upper and outer angle of the crural ring, and is 
 consequently in danger of being wounded if the stricture is divided in a direction 
 upward and outward. 
 
 The communicating branch between the deep epigastric and obturator lies in 
 front of the ring. 
 
 The circumference of the ring is thus seen to be bounded by vessels in every 
 part, excepting internally and behind (Fig. 1125). It is in the former position that 
 the stricture is divided in cases of strangulated femoral hernia. 
 
 The obturator artery (p. 688), when it arises by a common trunk with the deep 
 epigastric (p. 689), which occurs once in every three subjects and a half, bears 
 a very important relation to the crural ring. In most cases it descends on the 
 
 Fig. 1125.— Hernia. 
 
 The relations of the femoral and internal abdominal rings, seen from within the 
 abdomen. Right side. 
 
 inner side of the external iliac vein to the obturator foramen, and will consequently 
 lie on the outer side of the crural ring, where there is no danger of its being 
 wounded in the operation for dividing the stricture in femoral hernia (Fig. 427 A, 
 p. 689). Occasionally, however, the obturator artery curves along the free margin 
 of Gimbernat's ligament in its passage to the obturator foramen; it would conse- 
 quently skirt along the greater part of the circumference of the crural ring, and 
 could hardly avoid being wounded in the operation (Fig. 427 B, p. 689). 
 
 The Crural Septum or Septum Crurale (septum femorale muscuhis) (Fig. 297). — 
 The femoral ring is closed by a thin process of transversalis fascia containing fat 
 and called, by J. Cloquet, the septum crurale. This serves as a barrier to the 
 protrusion of a hernia through this part. Its upper surface is slightly concave, 
 and supports a small lymphatic gland (Fig. 1125), by which it is separated from 
 the subserous areolar tissue and peritoneum. Its under surface is turned toward 
 the femoral canal. The septum crurale is perforated by numerous apertures for 
 the passage of lymphatic vessels connecting the deep inguinal lymphatic glands 
 with those surrounding the external iliac artery. 
 
FEMORAL HERNIA I533 
 
 The size of the femoral canal, the degree of tension of its orifices, and conse- 
 quently the degree of constriction of a hernia, vary according to the position of 
 the limb. If the leg and thigh are extended, abducted, or everted, the femoral 
 canal and its orifices are rendered tense from the traction on these parts by Pou- 
 part's ligament and the fascia lata, as may be ascertained by passing the finger 
 along the canal. If, on the contrary, the thigh is flexed upon the pelvis, and at 
 the same time adducted and rotated inward, the femoral canal and its orifices 
 become considerably relaxed; for this reason the limb should always be placed in 
 the latter position when the application of the taxis is made in attempting the 
 reduction of a femoral hernia. 
 
 The subperitoneal areolar tissue is continuous with the subserous areolar tissue 
 of surrounding parts. It is usually thickest and most fibrous where the iliac ves- 
 sels leave the abdominal cavity. It covers over the femoral ring, the small interval 
 on the inner side of the femoral vein. In some subjects it contains a considerable 
 amount of adipose tissue. In such cases, where it is protruded foi-ward in front 
 of the sac of a femoral hernia, it may be mistaken for a portion of omentum. The 
 peritoneum lining the portion of the abdominal wall between Poupart's ligament 
 and the brim of the pelvis is similar to that lining any other portion of the abdom- 
 inal wall, being very thin. Here there is no natural aperture for the escape of 
 intestine. 
 
 Descent of the Hernia. — From the preceding description it follows that the 
 femoral ring must be a w^eak point in the abdominal wall; hence it is that when 
 violent or long-continued pressure is made upon the abdominal viscera a portion 
 of intestine may be forced into it, constituting a femoral hernia; and the changes 
 in the tissues of the abdomen which are produced by pregnancy, together with the 
 larger size of this aperture in the female, serve to explain the frequency of this 
 form of hernia in women. 
 
 When a portion of the intestine passes through the femoral ring, a pouch of 
 peritoneum lies before it, which forms what is called the hernial sac; it is cov- 
 ered by the subserous areolar tissue, receives an investment from the septum 
 crurale, and descends vertically along the crural canal in the inner compartment of 
 the sheath of the femoral vessels as far as the saphenous opening; at this point it 
 changes its course, being prevented from extending farther down the sheath on 
 account of the narrowing of the sheath and its close contact with the vessels, and 
 also from the close attachment of the superficial fascia and crural sheath to the 
 lower part of the circumference of the saphenous opening; the hernia is conse- 
 quently directed forward, pushing before it the cribriform fascia, and then curves 
 upward on to the falciform process of the fascia lata and lower part of the tendon 
 of the External oblique, being covered by the superficial fascia and integument. 
 Wliile the hernia is contained in the femoral canal it is usually of small size, 
 owing to the resisting nature of the surrounding parts; but when it has escaped 
 from the saphenous opening into the loose areolar tissue of the groin, it becomes 
 considerably enlarged. The direction taken by a femoral hernia in its descent is 
 at first downward, then forward and upward; this should be borne in mind, as 
 in the application of the taxis for the reduction of a femoral hernia pressure should 
 be directed in the reverse order. 
 
 Coverings of the Complete Hernia. — The coverings of a femoral hernia, from 
 within outward, are— peritoneum, subserous areolar tissue, the septum crurale, 
 crural sheath, cribriform fascia, superficial fascia, and integument.* 
 
 immedi 
 
 SUrglCail V , lly in iiiiiy»/i I emu Li/ » t.»»iv,iii.^»^* ,...w ^-..■ — ^ '"' '' ~ '• ' 7 ' 1 Ltr • c iL -i' I ~ 1 * I, 
 
 account of the ease with which an inexperienced operator may mistake the fascia for the peritoneal sac and the 
 contained fat for omentum. Anatomically, this fascia appears identical with what is called m the text sub- 
 serous areolar tissue," the areolar tissue being thickened and caused to assume a membranous appearance by 
 the pressure of the hernia. — Ed. of 15th English edition. 
 
1534 THE SURGICAL ANAT03IY OF HERNIA 
 
 Varieties of Femoral Hernia. — If the hernia descends along the femoral canal only 
 as far as the saphenous opening, and does not escape from this aperture, the con- 
 dition is called incomplete femoral hernia. The small size of the protrusion in this 
 form of hernia, which is due to the firm and resisting nature of the canal in 
 which it is contained, renders it an exceedingly dangerous variety, from the 
 extreme difficulty of detecting the existence of the swelling, especially in corpulent 
 subjects. The coverings of an incomplete femoral hernia, named from without 
 inward, are as follows : the integument, superficial fascia, iliac portion of fascia lata, 
 crural sheath, septum crurale, subserous areolar tissue, and peritoneum. When, 
 however, the hernia protrudes through the saphenous opening and directs itself 
 forward and upward, it forms a complete femoral hernia, the coverings of which 
 have been given (p. 1533). Occasionally the hernial sac descends on the iliac 
 side of the femoral vessels or in front of these vessels, or even sometimes behind 
 them. 
 
 The seat of stricture in a strangulated femoral hernia varies ; it may be in the 
 peritoneum at the neck of the hernial sac; in the greater number of cases it w^ould 
 appear to be at the point of junction of the falciform process of the fascia lata 
 with the lunated edge of Gimbernat's ligament, or at the margin of the saphenous 
 opening in the thigh. The stricture should in every case be divided in an inward 
 direction, or upward and inward, and the extent of the necessary cut in the 
 majority of cases is about two or three lines. By these means all vessels or 
 other structures of importance in relation with the neck of the hernial sac will 
 be avoided. 
 
SUEGICAL ANATOIIY OF THE PERINJIUM. 
 
 Dissection. — The student should select a well-developed muscular subject, free from fat, 
 and the dissection should be commenced early, in order that the parts may be examined in as 
 recent a state as possible. A staff having been introduced into the bladder and the subject 
 placed in the position shown in Fig. 1126, the scrotum should be raised upward, and retained in 
 that position, and the rectum moderately distended with tow. 
 
 The Perinaeum corresponds to the inferior aperture or outlet of the pelvis. Its 
 deep boundaries are, in front, the pubic arch and subpubic ligament; behind, 
 the tip of the coccyx; and on each side, the rami of the os pubis and ischium, the 
 tuberosities of the ischium, and great sacro-sciatic ligaments. The space included 
 by these boundaries is somewhat lozenge-shaped, and is limited on the surface of 
 
 Fig. 1126. — Dissection of perinseum and ischio-rectal region. 
 
 the body by the scrotum in front, by the buttocks behind, and on each side by the 
 inner side of the thigh. A line drawn transversely between the anterior parts of 
 the tuberosities of the ischium, on each side, in front of the anus, divides this space 
 into two portions. The anterior portion contains the penis and urethra, and is 
 called the perinaeum proper or genito-urinary region. The posterior portion con- 
 tains the termination of the rectum, and is called the ischio-rectal or anal region. 
 
 ISCHIO-REOTAL REGION. 
 
 The ischio-rectal region contains the termination of the rectum and a deep fossa, 
 filled with fat, on each side of the intestine, between it and the tuberosity of the 
 ischium; this is called the ischio-rectal fossa. 
 
 The ischio-rectal region presents in the middle line the aperture of the'anus; 
 around this orifice the integument is thrown into numerous folds, which are 
 obliterated on distention of the anus. The integument is of a dark color, con- 
 tinuous with the mucous membrane of the rectum, and is provided with numerous 
 
 ( 1535 ) 
 
1536 SURGICAL ANATOMY OF THE PERINEUM 
 
 follicles, which occasionally inflame and suppurate, and may be mistaken for 
 fistulae. The veins around the margin of the anus are occasionally much dilated, 
 forming a number of hard pendent masses, of a dark bluish color, covered partly 
 by mucous membrane and partly by the integument. These tumors constitute the 
 disease called external piles. 
 
 Dissection (Fig. 1126). — Make an incision through the integument, along the median line, 
 from the base of the scrotum to the anterior extremity of the anus: carry it around the margins 
 of this aperture to its posterior extremity, and continue it backward to about an inch behind 
 the tip of the coccyx. A transverse incision should now be carried across the base of the scrotum, 
 joining the anterior extremity of the preceding; a second, carried in the same direction, should 
 be made in front of the anus; and a third at the posterior extremity of the first incision. These 
 incisions should be sufficiently extensive to enable the dissector to raise the integument from 
 the inner side of the thighs. The flaps of skin corresponding to the ischio-rectal region should 
 now be removed. In dissecting the integument from this region great care is recfuired, otherwise 
 the Corrugator cutis ani and External sphincter will be removed, as they are intimately adherent 
 to the skin. 
 
 The Superficial Fascia is exposed on the removal of the skin; it is very thick, 
 areolar in texture, and contains much fat in its meshes. In it are found ramifying 
 two or three branches of the perforating cutaneous nerve; these turn around the 
 inferior border of the Gluteus maximus and are distributed to the integument 
 around the anus. 
 
 In this region, and connected with the lower end of the rectum, are four muscles: 
 the Corrugator cutis ani; the two Sphincters, External and Internal; and the 
 Levator ani. 
 
 These muscles have been already described (p. 449). 
 
 The Ischio-rectal Fossa {fossa ischiorectalis) (P'igs. 300 and 304) is situated 
 between the end of the rectum and the ischial tuberosity. It is triangular in shape; 
 its base, directed to the surface of the body, is formed by the integument of the 
 ischio-rectal region; its apex, directed upward, corresponds to the point of division 
 of the obturator fascia and the thin membrane given off from it, which covers the 
 outer surface of the Levator ani (ischio-rectal or anal fascia). Its dimensions are 
 about an inch in breadth at the base and about two inches in depth, being deeper 
 behind than in front. It is bounded, internally, by the Sphincter ani, Levator 
 ani, and Coccygeus muscles; externally, by the tuberosity of the ischium and the 
 obturator fascia, which covers the inner surface of the Obturator internus muscle; 
 in front, it is limited by the line of junction of the superficial fascia with the base 
 of the triangular ligament; and behind, by the margin of the Gluteus maximifs 
 muscle and the great sacro-sciatic ligament. This space is filled with a large mass 
 of adipose tissue, which explains the frequency with which abscesses in the neigh- 
 borhood of the rectum burrow to a considerable depth. 
 
 If the subject has been injected, on placing the finger on the outer wall of this 
 fossa the internal pudic artery, with its accompanying veins and the two divisions 
 of the nerve, will be felt about an inch and a half above the margin of the ischiatic 
 tuberosity, but approaching nearer the surface as they pass forward along the 
 inner margin of the pubic arch. These structures are enclosed in a sheath, the 
 fascial canal or canal of Alcock (Figs. 304 and 1131), formed by the obturator fascia, 
 the pudic nerve lying below the artery and the dorsal nerve of the penis above it. 
 Crossing the space transversely, about its centre are the inferior hemorrhoidal 
 vessels and nerves, which are distributed to the integument of the anus and to the 
 muscles of the lower end of the rectum. These vessels are occasionally of large 
 size, and may give rise to troublesome hemorrhage when divided in the operation 
 of lithotomy or in that for fistula in ano. At the back part of this space, near 
 the coccyx, may be seen a branch of the fourth sacral nerve, and at the forepart of 
 the space the superficial perineal vessels and nerves can be seen for a short distance. 
 
THE PERINEUM PROPER IN THE MALE 1537 
 
 THE PERIN-fflUM PROPER IN THE MALE. 
 
 The perineal space is of a triangular form; its deep boundaries are limited, 
 laterally, by the rami of the pubic bones and ischia, meeting in front at the pubic 
 arch; behmd, by an imaginary transverse line extending between the anterior 
 parts of the tuberosities of the ischia. The lateral boundaries are, in the adult, 
 from three inches to three inches and a half in length, and the base from two to 
 three inches and a half in breadth, the average extent of the space being two 
 inches and three-quarters. 
 
 The variations in the diameter of this space are of extreme interest in connection with the 
 operation of hthotomy and the extraction of a stone from the cavity of the bladder. In those 
 cases where the tuberosities of the ischia are near together it would be necessary to make the 
 incisions in the lateral operation of hthotomy less obhque than if the tuberosities were widely 
 separated, and the perineal space consequently wider. The perinseum is subdivided by the 
 median raphe into two equal parts. Of these, the left is the one in which the operation of lith- 
 otomy is performed. 
 
 In the middle line the perinseum is convex, and corresponds to the bulb of the 
 urethra. The skin covering it is of a dark color, thin, freely movable upon the 
 subjacent parts, and covered with sharp crisp hairs, which should be removed 
 before the dissection of the part is commenced. In front of the anus a prominent 
 line commences, the raph^, continuous in front with the raphd of the scrotum. 
 The skin of the raphe is adherent to the deep layer of the superficial fascia. 
 
 Upon removing the skin and the superficial layer of the superficial fascia, in the 
 manner shown in Fig. 1126, a plane of fascia will be exposed, covering in the 
 triangular space and stretching across from one ischio-pubic ramus to the other. 
 This is the deep layer of the superficial fascia or fascia of CcUes (fascia superficialis 
 perinaei). It has already been described (p. 456). It is a layer of considerable 
 strength, and encloses and covers a space in which are contained muscles, vessels, 
 and nerves. It is continuous in front with the fascia of the penis and the dartos 
 of the scrotum ; on each side it is firmly attached to the margin of the ischio-pubic 
 ramus and to the tuberosity of the ischium; and posteriorly it curves down behind 
 the Transversalis perinaei muscles to join the base of the triangular ligament. 
 
 It is between this layer of fascia and the triangular ligament of the urethra that extravasa- 
 tion of urine most frequently takes place in cases of rupture of the urethra. The triangular 
 ligament of the urethra (p. 459) is attached to the ischio-pubic rami, and in front to the subpubic 
 ligament. It is clear, therefore, that when extravasation of fluid takes place between these 
 two layers, it cannot pass backward, because the two layers are continuous with each other 
 around the Transversi perinaei muscles: it cannot extend laterally, on account of the connection 
 of both these layers to the rami of the os pubis and ischium ; it cannot find its way into the pelvis 
 because the opening into this cavity is closed by the triangular ligament, and, therefore, so 
 long as these two layers remain intact, the only direction in which the fluid can make its way 
 is forward into the areolar tissue of the scrotum and penis, and then on to the anterior wall of 
 the abdomen. 
 
 \^^len the deep layer of the superficial fascia is removed (Fig. 1127), a space is 
 exposed, between this fascia and the triangular ligament, in which are contained the 
 superficial perineal vessels and nerves and some of the muscles connected with the 
 penis and urethra— viz., in the middle line, the Accelerator urinae; on each side, 
 the Erector penis; and behind, the transversus perinaei; together with the_ crura 
 of the corpora cavernosa and the bulb of the corpus spongiosum. Here also is seen 
 the central tendinous point of the perinaeum. This is a fibrous point in the middle 
 line of the perineum between the urethra and the rectum, being about half an inch 
 in front of the anus. At this point four muscles converge and are attached— viz., 
 the External sphimjter ani, the Accelerator urinae, and the two Transversi perinaei 
 
 97 
 
1538 
 
 SURGICAL ANAT03IY OF THE PERINEUM 
 
 muscles; so that by the contraction of these muscles, which extend in opposite 
 directions, it serves as a fixed point of support. 
 
 The Accelerator urinae, the Erector penis, and the Superficial transversus 
 perinaei muscles have been already described (p. 457). They form a triangular 
 space (Fig. 1127), bounded, internally, by the Accelerator urinae; externally, by 
 the Erector penis; and behind, by the Transversus perinaei. The floor of this 
 space is formed by the triangular ligament of the urethra; and running from, 
 behind forward in it are the superficial perineal vessels and nerves, and the 
 transverse perineal artery coursing along the posterior boundary of the space, 
 on the Transversus perinaei muscle. 
 
 The Accelerator urinae and Erector penis should now be removed, when the triangular liga- 
 ment of the urethra will be exposed, stretching across the front of the outlet of the pelvis. The 
 urethra is seen perforating its centre, just behind the bulb; and on each side is the crus penis, 
 connecting the corpus cavernosum with the rami of the ischium and os pubis. 
 
 Transversus perinei 
 superfidalis. 
 
 GREAT SACRO- 
 SCIATIC LIGAMENT. 
 
 Superficial perineal artery. 
 Superficial perineal nerve. 
 Internal piidic nerve. 
 Internal pudic artery. 
 
 Fig. 1127. — The superficial muscles and vessels of the perinsRum. 
 
 The Triangular Ligament or the Deep Perineal Fascia (trigonum urogenitale or 
 diaphragma urogenitale) (Figs. 309, 310, and 1128), which has been already 
 described (p. 459), consists of two layers, the inferior anterior or superficial layer 
 (fascia trigoni urogenitalis inferior) of which is now exposed. It is united to the 
 superior or deep layer behind, but is separated in front by a subfascial space in 
 which are contained certain structures. 
 
 The inferior layer of the triangular ligament (Figs. 305 an 1 310) consists of a 
 strong fibrous membrane, the fibres of which are disposed transversely, which 
 stretches across from one ischio-pubic ramus to the other and completely fills in 
 the pubic arch; it is attached in front to the subpubic ligament, except just in the 
 centre, where a small interspace is left for the dorsal vein of the penis. In the erect 
 position of the body it is almost horizontal. It is perforated by the urethra in the 
 middle line, and on each side of the urethral opening by the ducts of Cowper's 
 glands and by the arteries of the bulb; in front, and external to this, by the artery 
 
THE PERINEUM PROPER IN THE MALE 1539 
 
 of the corpus cavernosum, immediately before this vessel enters the crus penis 
 Near its apex the ligament is perforated by the termination of the pudic artery and 
 by the dorsal nerve of the penis. The apex of the triangular ligament is known as 
 the transverse perineal ligament. The crura penis are exposed, lying superficial to 
 this ligament. They will be seen to be attached by blunt-pointed processes to the 
 rami of the os pubis and ischium, in front of the tuberosities, and passing forward 
 and inward, joining to form the body of the penis. In the middle line the bulb and 
 corpus spongiosum are exposed by the removal of the Accelerator urinae muscle. 
 If the inferior layer of the triangular ligament is detached on either side, 
 the deep perineal interspace will be exposed and the following parts will be seen 
 between it and the deep layer of the ligament: the subpubic ligament in front, 
 close to the symphysis pubis; the dorsal vein of the penis; the membranous por- 
 tion of the urethra and the Compressor urethrae muscle; Cowper's glands and 
 their ducts; the pudic vessels and the dorsal nerve of the penis; the artery and 
 nerve of the bulb and a plexus of veins. 
 
 Anterior layer of 
 
 deep perineal fascia removed, 
 
 showing 
 
 .^COMPRESSOR URETHR>E. 
 
 Jnternal pudic artery. 
 Artery of the bulb. 
 Cowper's gland. 
 
 Fig. 1128. — Deep perineal fascia. On the left side the anterior layer has been removed. 
 
 The superior, deep, or posterior layer of the triangular ligament or deep perineal 
 fascia (fascia trigoni urogenitalis superior) {iig. 305) is derived from the obturator 
 fascia, and is continuous with it along the pubic arch. Behind, it joins with the 
 inferior layer of the triangular ligament, and is continuous with the anal fascia. 
 Above it is the prostate gland (Fig. 1129), supported by the anterior fibres of 
 the Levator ani, which act as a sling for the gland and form the Levator prostatae 
 muscle. The superior layer of the triangular ligament is continuous around the 
 anterior free edge of this muscle with the layer of recto-vesical fascia covering 
 the prostate gland. The superior layer of the triangular ligament is perforated 
 by the urethra. Between the two layers of the triangular ligament are situated 
 the membranous part of the urethra, enveloped by the Compressor urethrae 
 muscle (Fig. 309); the ducts of Cowper's glands; the arteries to the bulb; the 
 pudic vessels and the dorsal nerve of the penis. The membranous part of the 
 urethra is about three-quarters of an inch in length, and passes downward and 
 
1540 
 
 SURGICAL ANATOMY OF THE PERINEUM 
 
 forward behind the symphysis pubis, from which it is distant about an inch. It 
 is the narrowest part of the tube, and is enveloped, as has already been stated, 
 by the Compressor urethrae muscle. 
 
 The Compressor urethrae has already been described (p. 460). In addition to 
 this muscle, and immediately beneath it, circular muscular fibres surround the 
 membranous portion of the urethra from the bulb in front to the prostate behind, 
 and are continuous with the muscular fibres of the bladder. These fibres are 
 involuntary. 
 
 Cowper's glands (Figs. 303, 1128, and 1129) are situated immediately below 
 the membranous portion of the urethra, close behind the bulb, and below the 
 artery of the bulb. 
 
 The Pudic Vessels (Figs. 1128 and 1129) and Dorsal Nerve of the Penis (Fig. 310) 
 are placed along the inner margin of the pubic arch (p. 1536). 
 
 The Artery of the Bulb (Figs. 1128 and 1129, and p. 691) passes transversely 
 inward, from the internal pudic artery (p. 689) along the base of the triangular 
 
 Avtery of corpus cavernosum. 
 Dorsal artery of penis. 
 
 Artery of bulb. 
 Internal pudic artery, 
 
 Cowper's gland. 
 
 Fig. 1129. — A view of the position of the viscera at the outlet of the pelvis. 
 
 ligament, between its two layers, accompanied by a branch of the pudic nerve. 
 If the superior layer of the triangular ligament is removed and the crus penis of 
 one side detached from the bone, the under or perineal surface of the Levator 
 ani muscle, covered by the anal fascia, is brought fully into view (Figs. 302, 
 303, and 304). This muscle, with the triangular ligament in front and the Coc- 
 cygeus and Pyriformis behind, closes the outlet of the pelvis. 
 
 The Levator ani and Coccygeus muscles have already been described (p. 451). 
 
 Position of the Viscera at the Outlet of the Pelvis.— Divide the central tendinous point 
 of the perinseum, separate the rectum from its connections by dividing the fibres of the Levator 
 ani, which descend upon the sides of the prostate gland, and draw the gut backward toward the 
 coccyx, when the under surface of the prostate gland, the neck and base of the bladder, the 
 vesiculse seminales, and the vasa deferentia will be exposed. 
 
 The Prostate Gland (p. 1129) is a pale, firm, glandular body A^hich is placed 
 immediately below the neck of the bladder, around the commencement of the 
 
THE PERINEUM PROPER IN THE MALE 1541 
 
 urethra. It is placed in the pelvic cavity, behind the lower part of the sym- 
 physis pubis, above the superior layer of the triangular ligament, and rests upon 
 the rectum, through which it may be distinctly felt, especially when enlarged. In 
 shape and size it resembles a chestnut. Its base is directed upward toward the 
 neck of the bladder. Its apex is directed downward to the deeper layer of the 
 triangular ligament, which it touches. 
 
 Its posterior surface is smooth, marked by a slight longitudinal furrow, and rests 
 on the second part of the rectum, to which it is connected by areolar tissue. Its 
 anterior surface is flattened, marked by a slight longitudinal furrow, and placed 
 about three-quarters of an inch below the pubic symphysis. It measures about 
 an inch and a half in its transverse diameter at the base, an inch in its antero- 
 posterior diameter, and three-quarters of an inch in depth. Hence the greatest 
 extent of incision that can be made in it without dividing its substance completely 
 across is obliquely backward and outward. This is the direction in which the 
 incision is made in it in the lateral operation of lithotomy. The prostate has a 
 sheath derived from the recto-vesical fascia (p. 1449). 
 
 Above the prostate a small triangular portion of the bladder is seen (Fig. 1129), 
 bounded, in front and below, by the prostate gland; above, by the recto-vesical fold 
 of the peritoneum; on each side, by the seminal vesicle and the vas deferens. It is 
 separated from direct contact with the rectum by the recto-vesical fascia. The 
 relation of this portion of the bladder to the rectum is of extrem.e interest to the 
 surgeon. In cases of retention of urine this portion of the organ is found pro- 
 jecting into the rectum, between three and four inches from the margin of the 
 anus, and may be easily perforated without injury to any important parts. This 
 portion of the bladder was consequently selected in the old days for the perform- 
 ance of the now obsolete operation of tapping the bladder. 
 
 Surgical Anatomy. Median Lithotomy. — As the incision is in the raph^, the hemor- 
 rhage is trivial, and there is but slight risk of injuring the pelvic fascia. But the operation gives 
 little room for manipulation and is inadmissible in children, because in them dilatation of the 
 wound may tear the bladder loose from the urethra. A risk of median lithotomy is division of 
 the artery of the bulb. 
 
 In median lithotomy a grooved staff is introduced, the groove being median. The knife is 
 introduced in the mid-line, just in front of the anal m.argin, and hits the staff near the apex 
 of the prostate; the entire length of the membranous urethra is cut as the instrument is with- 
 drawn. 
 
 Parts Divided. — Skin,' superficial fascia, sphincter ani muscle, central tendon of the 
 perinseum, inferior leaf of the triangular ligament, membranous urethra, and the Compressor 
 urethrae muscle. 
 
 Lateral Lithotomy.— The operation is performed on the left side of the perinseum, as this 
 is most convenient for the right hand of the operator. A grooved staff having been introduced 
 into the bladder, the first incision is commenced midway between the anus and the back of 
 the scrotum {i. e., in an ordinary adult perinseurn about an inch and a half in front of the anus) 
 a litde on the left side of the raphe, and is carried obliquely backward and outward to midway 
 between the anus and tuberosity of the left ischium. The incision divides the integument and 
 superficial fascia, the inferior hemorrhoidal vessels and nerves, and the superficial and trans- 
 verse perineal vessels. If the forefinger of the left hand is thrust upward and forward inlo 
 the wound, pressing at the same time the rectum inward and backward, the staff may be felt in 
 the membranous portion of the urethra. The finger is fixed upon the staff", and the structures 
 covering the staff are divided with the point of the knife, which must be directed along the groove 
 toward the bladder, the edge of the knife being turned outward and backward, dividing in its 
 course the membranous portion of the urethra and part of the left lobe of the prostate gland 
 to the extent of about an inch. The knife is then withdrawn, and the forefinger of the left hand , 
 passed along the staff into the bladder. The position of the stone having been ascertained, the 
 staff is to be withdrawn, and the forceps is introduced over the finger into the bladder. If the 
 stone is very large, the opposite side of the prostate may need to be notched before the forceps 
 is introduced; the finger is now withdrawn, and the blades of the forceps opened and made to 
 grasp the stone, which must be extracted by slow and cautious undulating movements. 
 
 Parts Divided in the Operation.— The various structures divided in this operation are as 
 follows: the integument, superficial fascia, inferior hemorrhoidal vessels and nerves, and prob- 
 
1542 SURGICAL ANATOMY OF THE PERINEUM 
 
 ably the superficial perineal vessels and nerves, the posterior fibres of the Accelerator urinae 
 muscle, the Transversus perinaei muscle and artery, the triangular ligament, the anterior fibres of 
 the Levator ani muscle, part of the Compressor urethrae muscle, the membranous and pros- 
 tatic portions of the urethra, and part of the prostate gland. 
 
 Parts to be Avoided in the Operation. — In making the necessary incisions in the perinseum for 
 the extraction of a calculus the following parts should be avoided: The primary incision should 
 not be made too near the middle line, for fear of wounding the bulb of the corpus spongiosum 
 or the rectum ; nor too far externally, otherwise the internal pudic artery may be implicated as it 
 ascends along the inner border of the pubic arch. If the incisions are carried too far forward, 
 the artery of the bulb may be divided ; if carried too far backward, the entire breadth of the pros- 
 tate and neck of the bladder may be cut through, which allows the urine to become infiltrated 
 behind the pelvic fascia into the loose areolar tissue between the bladder and rectum, instead 
 of escaping externally; diffuse inflammation is consequently set up, and peritonitis, from the 
 close proximity of the recto-vesical peritoneal fold, is the result. If, on the contrary, only the 
 anterior part of the prostate is divided, the urine makes its way externally, and there is less 
 danger of infiltration taking place. 
 
 During the operation it is of great importance that the finger should be passed into the bladder 
 before the staff is removed; if this is neglected, and if the incision made in the prostate and neck 
 of the bladder is too small, great difficulty may be experienced in introducing the finger afterward; 
 and in the child, where the connections of the bladder to the surrounding parts are very loose, 
 the force made in the attempt is sufficient to displace the bladder upward into the abdomen, 
 out of the reach of the operator. Such a proceeding has not unfrequently occurred, producing 
 the most embarrassing results and total failure of the operation. 
 
 It is necessary to bear in mind that the arteries in the perinseum occasionally take an abnormal 
 course. Thus the artery of the bulb, when it arises, as sometimes happens, from the pudic 
 opposite the tuber ischii, is liable in its passage forward to the bulb to be wounded in the 
 operation of lithotomy. The accessory pudic may be divided near the posterior border of the 
 prostate gland, if this gland is completely cut across; and if the prostatic veins are of large size, 
 and give rise, when divided, to troublesome hemorrhage. In men advanced in years the pros- 
 tatic veins are very apt to be enlarged. 
 
 Extravasation of Urine. — Extravasation most commonly occurs from urethral rupture, 
 between Colles's fascia and the triangular ligament of the urethra (extravasation in front of 
 the triangular ligament). The adherence of these two fascial layers posteriorly prevents the 
 urine from passing backward. The urine cannot find a way laterally, because both layers on 
 each side are attached to the rami of the pubes and ischium. It cannot reach the pelvis, because 
 the triangular ligament bars the way. It can only go forward if the two fascial layers remain 
 intact, and consequently the urine passes into the areolar tissue of the scrotum beneath the 
 superficial fascia of the penis and of the anterior abdominal wall. 
 
 Pus and blood would pursue the same course in this space. Effusions in this space causes 
 much pain, because the space contains the three long scrotal nerves. 
 
 In rupture of the urethra between the two layers of the triangular ligament, the urine remains 
 in this situation as long as fascia remains intact. If suppuration occurs, destruction of fascia 
 liberates the urine. 
 
 In rupture behind the superior layer of the triangular ligament (extravasation back of the 
 triangular ligament), the urine passes intD the ischio-rectal fossa and upward and backward 
 into the pelvis. 
 
 THE FEMALE PERINiEUM. 
 
 The female perinseum presents certain differences from that of the male, in 
 consequence of the whole of the structures which constitute it being perforated 
 in the middle line by the vulvo-vaginal passage. 
 
 The Superficial Fascia, as in the male, consists of two layers, of which the 
 superficial one is continuous with the superficial fascia over the rest of the body, 
 and the deep layer, corresponding to the fascia of Colles in the male, is, like it, 
 attached to the ischio-pubic rami, and in front is continued forward through 
 the labia majora to the inguinal region. It is of less extent than in the male, 
 in consequence of being perforated by the aperture of the vulva. 
 
 On removing this fascia the muscles of the female perinjeum, which have 
 already been described (p. 461), are exposed (Figs. 311 and 1130). The Sphincter 
 vaginae, corresponding to the Accelerator urinae in the male, consists of an atten- 
 
THE FEMALE PERINJEUM 
 
 1543 
 
 uated plane of fibres, forming an orbicular muscle around the orifice of the 
 vagina, instead of being united in a median raphe, as in the male. The Erector 
 clitoridis is proportionately reduced in size, but differs in no other respect from 
 the erector penis, and the Transversus perinaei is similar to the muscle of the 
 same name in the male. 
 
 The triangular ligament (Fig. 1130) is not strongly marked as in the male. 
 It transmits the urethra and the tube of the vagina. 
 
 The Compressor Urethrae corresponds with the Compressor urethrae in the male. 
 It arises from the ischio-pubic ramus, and, passing inward, its anterior fibres blend 
 with the muscle of the opposite side, in front of the urethra; its middle fibres, the 
 most numerous, are inserted into the side of the vagina, and the posterior fibres 
 join the central point of the perinseum. 
 
 Suspensoi-p ligavmit 
 of clitoris 
 
 Glans clitoris 
 
 Erector 
 
 clitoridie 
 
 muscle 
 
 Sphincter 
 
 vaginae 
 
 muscle 
 
 Deep perineal 
 muscle, with, 
 its under 
 layer of fascia 
 {the triangular 
 iigament) 
 
 External 
 obturator 
 muscle 
 
 Sacro- 
 sciatic 
 ligament 
 
 Gluteus mazimus 
 
 muscle ^^ ^^'^'^y^ 
 
 Fig. 1130. — The female perinsDum after removal of the skin and superficial fascia 
 
 External sphincter 
 ani muscle 
 
 (Bardeleben.) 
 
 The distribution of the internal pudic artery is the same as in the male (p. 1540), 
 and the pudic nerve has also a similar arrangement, the dorsal nerve being, 
 however, very small and supplying the clitoris. 
 
 The corpus spongiosum is divided into two lateral halves, which are represented 
 by the bulbi vestibuli and partes intermediales. 
 
 The Perineal Body fills up the interval between the lower part of the vagina 
 and the rectum. Its base is covered by the skin lying between the anus and 
 
1544 
 
 SURGICAL ANATOMY OF THE PERINEUM 
 
 vagina on what is called the perinseum. Its anterior surface Hes behind the pos- 
 terior vaginal wall, and its posterior surface lies in front of the anterior rectal 
 wall and the anus. It measures about an inch and a quarter from before back- 
 ward, and laterally extends from one tuberosity of the ischium to the other. In it 
 are situated the muscles belonging to the external organs of generation. Through 
 its centre runs the transverse perineal septum, which is of great strength in women, 
 and forms on either side, behind the posterior commissure, a hard, ill-defined 
 body, consisting of connective tissue, with much yellow elastic tissue and inter- 
 lacing bundles of involuntary muscular fibres, in which the voluntary muscles of 
 the perineum are inserted. 
 
 The Pelvic Fascia (fascia pelvis) (Figs. 304 and 1131). — The pelvic fascia 
 strengthens the floor of the pelvis, fastens pelvic structures together, and supports 
 the nerves, blood-vessels, and lymphatics. It is connected above with the trans- 
 
 Internal pudic vessels 
 and nerve. 
 
 Tuberosity of 
 ischium. 
 
 Fig. 1 131. — A transverse section of the pelvis, showing the pelvic fascia from behind. 
 
 versalis fascia and the iliac fascia. It is at first a thin membrane and covers the 
 inner surface of the pelvis, being attached to the brim for a short flistance at the 
 side of the cavity and to the inner surface of the bone around the attachment of 
 the Obturator internus. At the posterior portion of this muscle it is continued 
 backward as a very thin membrane in front of the Pyriformis muscle to the front 
 of the sacrum. In front, as it descends, it gives off the parietal layer of the pelvic 
 fascia, which continues as the obturator fascia. It then becomes thicker and covers 
 the inner and upper surface of the Diaphragm of the pelvis as far as the white 
 line (arcus tendineus fasciae pelvis). The portion covering the superior and upper 
 surface of the pelvic Diaphragm is the inner sheath of the T^evator ani muscle and 
 is called the visceral layer of the pelvic fascia or the recto-vesical fascia (fascia 
 diaphragmatis pelvis superior). The white line is a rough band of fascial thick- 
 ening, seen in the pelvic fascia of each side. It indicates the line of separation 
 between the pelvic cavity and the ischio-rectal fossa. It passes from the lower 
 
THE FEMALE PEBINJEUM 
 
 1545 
 
 portion of the symphysis pubis outward and. backward to the spine of the ischium. 
 It makes the attachment of the levator ani muscle to the pelvic fascia. At the white 
 line the chief mass of the pelvic fascia passes upon the pelvic viscera and is known 
 as the fascia endo-pelvica. It covers portions of the vagina, rectum, and urinary 
 bladder, becomes thinner and thinner, and is gradually lost. Other bands of fascia 
 begin at the white line, descend on the inner surface of the recto-vesical fascia, and 
 in the male pass to the tip of the prostate and become the prostatic fascia. Between 
 the anterior ends of the two white lines the level of the fascia is lower, and it forms 
 a fossa, bounded on the sides in the male by the pubo-prostatic ligaments {liga- 
 menta p-uboprostatica lateralia), and in the female by the pubo-vesical ligaments 
 (ligamenta jmbovesicalia lateralia). These ligaments are called the lateral true 
 ligaments of the bladder. In the base of this fossa in the male runs the anterior true 
 ligament of the bladder or the pubo-prostatic ligament (ligamentum puboprostaticum 
 
 Fig. 1132. — Side view of the pelvic viscera of the male subject, showing the pelvic and perineal fasciae. 
 
 medium), and in the female the anterior true vesical ligament (ligamentum pubo- 
 vesicale medium). These ligaments arise from the lowest portion of the symphysis 
 and pass to the urinary bladder and prostate in the male, and urinary bladder and 
 urethra in the female (Spalteholz). The outer surface of the pelvic Diaphragm is 
 covered by the anal fascia or the ischio-rectal fascia (fascia diaphragmatis pelvis 
 inferior). ^ It is the lower or outer sheath of the Levator ani muscle, and is derived 
 from the obturator fascia. The space between the obturator fascia and the anal 
 fascia is pyramidal and is called the ischio-rectal fossa (fossa ischiorectalis). 
 
 The pelvic fascia does not completely invest the bladder, although the neck and 
 lateral walls lie upon the Levator ani muscles, and the lateral true ligaments and 
 the anterior ligament ascend upon the sides and front of the bladder and are lost 
 upon the fibrous coat of that viscus. The sides and anterior wall have a fascial 
 investment. The sheath of the prostate has already been discussed (p. 1449). It is 
 
1546 SURGICAL ANATOMY OF THE PERINEUM 
 
 continuous with the recto-vesical fascia and the anterior true hgament of the 
 bladder. 
 
 The pelvic fascia is composed, according to Hughes, of: 1. The fibrous cap- 
 sules of the pelvic viscera. 2. The sheaths of the Levator ani and Coccygei 
 muscles (recto-vesical and anal fasciae). 3. The sheath of the Obturator internus 
 (obturator fascia). 4. Sheath of the Compressor urethrae muscle (the triangular 
 ligament). 5. The sheath of the pelvic aspect of the Pyriformis muscle. The 
 sacral plexus is outside this sheath, the internal iliac vessels inside of it.^ As pre- 
 viously stated, the pelvic fascia gives off the obturator fascia and the recto-vesical 
 fascia. 
 
 The Obturator Fascia {fascia ohturatoria) descends and covers the Obturator 
 internus muscle. It is a direct continuation of the parietal pelvic fascia below 
 the white line above mentioned, and is attached to the pelvic arch, the ischial 
 tuberosities, and to the margin of the great sacro-sciatic ligaments. This fascia 
 forms a canal for the pudic vessels and nerve in their passage forward to the 
 perinaeum, and gives off a thin membrane which covers the perineal aspect of the 
 Levator ani muscle, and is called the anal or ischio-rectal fascia. It forms the inner 
 boundary of the ischio-rectal fossa. From its attachment to tlie rami of the os 
 pubis and ischium a process is given off which is continuous with a similar process 
 from the opposite side, so as to close the front part of the outlet of the pelvis, form- 
 ing the deej) layer of the triangular ligament. 
 
 The Recto-vesical Fascia or the Visceral Layer of the Pelvic Fascia 
 (fascia endopelvica) descends into the pelvis upon the upper surface of the Levator 
 ani muscle, and invests the prostate, bladder, and rectum. From the inner sur- 
 face of the symphysis pubis a short rounded band is continued, on each side of 
 the middle line, to the upper surface of the prostate and neck of the bladder, form- 
 ing the pubo-prostatic or anterior true ligaments of the bladder. At the side this 
 fascia is connected to the side of the prostate, enclosing this gland and the vesico- 
 prostatic plexus of veins, and is continued on to the side of the bladder, forming 
 the lateral true ligaments of the organ. Another prolongation invests the seminal 
 vesicle, and passes across between the bladder and rectum, being continuous 
 with the same fascia of the opposite side. Another thin prolongation is reflected 
 around the surface of the lower end of the rectum. The Levator ani muscle arises 
 from the point of division of the pelvic fascia, the visceral layer of the fascia 
 descending upon and being intimately adherent to the upper surface of the muscle, 
 while the under surface of the muscle is covered by a thin layer derived from the 
 obturator fascia, called the ischio-rectal or anal fascia. In the female the vagina 
 perforates the recto-vesical fascia and receives a prolongation from it. 
 
 1 A Manual of Practical Anatomj'. By Prof. Alfred W. Hughes; edited and completed by Dr. Arthur Keith. 
 
CHEONOLOGIOAL TABLE 
 
 OF 
 
 THE DEVELOPMENT OF THE FCETUS. 
 
 (From Beaunis and Bouchard.) 
 
 First Week. — During this period the ovum is in the Fallopian tube. Having been fertilized in 
 the upper part of the tube, it slowly passes down, undergoing segmentation, and reaches 
 the uterus probably about the end of the first week. During this time it does not undergo 
 much increase in size. 
 
 Second Week. — The ovum rapidly increases in size and becomes imbedded in the decidua, so 
 that it is completely enclosed in the decidua reflexa by the end of this period. An ovum 
 believed to be of the thirteenth day after conception is described by Reichert. There was 
 no appearance of any embryonic structure. The equatorial margins of the ovum were beset 
 with villi, but the surface in contact with the uterine wall and the one opposite to it were 
 bare. In another ovum, described by His, believed to be of about the fourteenth day, 
 there was a distinct indication of an embryo. There was a medullary groove bounded by 
 folds. In front of this a slightly prominent ridge, the rudimentary heart. The amnion 
 was formed and the embryo was attached by a stalk, the allantois, to the inner surface of 
 the chorion. It may be said, therefore, that these parts, the amnion and the allantois, and 
 the first rudiments of the embryo, the medullary groove, and the heart, are formed at the 
 end of the second week. 
 
 Third Week. — By the end of the third week the flexures of the embryo have taken place, so 
 that it is strongly curved. The protovertebral disks, which begin to be formed early in the 
 third week, present their full complement. In the nervous system the primary divisions 
 of the brain are visible, and the primitive ocular and auditory vesicles are already formed. 
 The primary circulation is established. The alimentary canal presents a straight tube com- 
 municating with the yolk-sac. The branchial arches are formed. The limbs have appeared 
 as short buds. The Wolffian bodies are visible. 
 
 Fourth Week. — The umbilical vesicle has attained its full development. The caudal extremity 
 projects. The upper and the lower limbs and the cloacal aperture appear. The heart sep- 
 arates into a right and left heart. The special ganglia and anterior roots of the spinal 
 nerves, the olfactory fossae, the lungs and the pancreas can be made out. 
 
 lYfth Week. — The allantois is vascular in its whole extent. The first traces of the hands and 
 feet can be seen. The primitive aorta divides into aorta and pulmonary artery. The duct 
 of Miiller and genital gland are visible. The ossification of the clavicle and the lower jaw 
 commences. The cartilage of Meckel occupies the first post-oral arch. 
 
 Sixth Week. — The activity of the umbilical vesicle ceases. The pharyngeal clefts disappear. 
 The vertebral column, primitive cranium, and ribs assume the cartilaginous condition. The 
 posterior roots of the nerves, the membranes of the nervous centres, the bladder, kidney, 
 tongue, larynx, thyroid body, the germs of teeth, and the genital tubercle and folds 
 are apparent. 
 
 Seventh Week. — The muscles begin to be perceptible. The points of ossification of the ribs, 
 scapula, shaft of humerus, femur, tibia, palate, and uiiper jaw appear. 
 
 Eighth Week. — The distinction of arm and forearm, and of tnigh and leg, is apparent, as well as 
 the interdigital clefts. The capsule of the lens and pupillary membrane, the interventricu- 
 lar and commencement of the interauricular septum, the salivary glands, the spleen, and 
 suprarenal capsules are distinguishable. The larynx begins to become cartilaginous. All 
 the vertebral bodies are cartilaginous. The points of ossification for the ulna, radius, fibula, 
 and ihum make their appearance. The two lialvcs of the hard i)alate unite. The 
 sympathetic nerves are now for the first time to be discerned. 
 
 * [Eternod {Anat. Anzeiger, Band xv., ]898) described an ovum which he reconstructed. It 
 had a precise history, from which he concluded that it must have belonged to the end of the second 
 or the beginning of the third week. Including the villi it measured 10X8.2X6 mm. It was 
 flattened on its embryonal side, and the embryo measured 1.3 mm. The amnion was completely 
 formed and the allantois existed as a long canal. The vitelline circulation was established and the 
 villi of the chorion were beginning to be vascularized. The blastopore still opened into the amniotic 
 cavity, with the primitive groove behind it and the rudimentary groove in front. The notochord 
 was closing in and all three layers of the blastoderm were disiinct, except around the blastopore, where 
 they formed an undivided mass. — Ed. of 1.5th English edition.] 
 
 1547 
 
1548 THE FCETUS. 
 
 Ninth Week. — The corpus striatum and the pericardium are first apparent. The ovarj' and 
 testicle can be distinguished from each other. The genital furrow appears. The osseous 
 nuclei of the bodies and arches of the vertebrae, of the frontal, vomer, and malar bones of the 
 shafts of the metacarpal and metatarsal bones, and of the phalanges appear. The union of 
 the hard palate is completed. The gall-bladder is seen. 
 
 Third Month. — The formation of the fcetal placenta advances rapidly. The projection of the 
 caudal extremity disappears. It is possible to distinguish the male and female organs from 
 each other. The cloacal aperture in divided into two parts. The cartilaginous arches on the 
 dorsal region of the spine close. Tlie points of ossification for the occipital, sphenoid, 
 lachrymal, nasal, squamous portion of temporal and ischium appear, as well as the orbital 
 centre of the superior maxillary. The pons Varolii and fissure of Sylvius can be made out. 
 The eyelids, the hair, and the nails begin to form. The mammary gland, the epiglottis, 
 and prostate are beginning to develop. The union of the testicle with the canals of the 
 Wolffian body takes place. 
 
 Fourth Month. — The closure of the cartilaginous arches of the spine is complete. Osseous 
 points for the first sacral vertebra and os pubis appear. The ossification of the malleus and 
 incus takes place. The corpus callosum, the membrana lamina spiralis, the cartilage of 
 the Eustachian tube, and the tympanic ring are seen. Fat is first developed in the sub- 
 cutaneous cellular tissue. The tonsils are seen, and the closure of the genital furrow and 
 the formation of the scrotum and prepuce take place. 
 
 Fifth Month. — The two layers of the decidua begin to coalesce. Osseous nuclei of the axis and 
 odontoid process, of the lateral points of the first sacral vertebra, of the median points of 
 the second, and of the lateral masses of the ethmoid make their appearance. Ossification 
 of the stapes and the petrous bone and ossification of the germs of the teeth take place. 
 The germs of the permanent teeth and the organ of Corti appear. The eruption of hair on 
 the head commences. The sudoriferous glands, Brunner's glands, the follicles of the tonsil 
 and base of the tongue, and the lymphatic glands appear at this period. The difiierentiatioa 
 between the uterus and vagina becomes apparent. 
 
 Sixth Month. — The points of ossification for the anterior root of the transverse process of the 
 seventh cervical vertebra, the lateral points of the second sacral vertebra, the median points 
 of the third, the manubrium sterni and the os calcis appear. The sacro-vertebral angle 
 forms. The cerebral hemispheres cover the cerebellum. The papillae of the skin, the 
 sebaceous glands, and Peyer's patches make their appearance. The free border of the 
 nail projects from the corium of the dermis. The walls of the uterus thicken. 
 
 Seventh Month. — The additional points of the first sacral vertebra, the lateral points of the 
 third, the median point of the fourth, the first osseous point of the body of the sternum, 
 and the osseous point for the astragalus appear. Meckel's cartilage disappears. The 
 cerebral convolutions, the island of Reil, and the tubercula quadrigemina are apparent. The 
 pupillary membrane atrophies. The testicle passes into the vaginal process of the 
 peritoneum. 
 
 Eighth Month. — Additional points for the second sacral vertebra, lateral points for the fourth 
 and median points for the fifth sacral vertebrae, can be seen. 
 
 Ninth Month. — Additional points for the third sacral vertebra, lateral points for the fifth, 
 osseous points for the middle turbinated bone, for the body and great cornu of the hyoid, 
 for the second and third pieces of the body of the sternum, and for the lower end of the 
 femur appear. Ossification of the bony lamina spiralis and axis of the cochlea takes place. 
 The eyelids open, and the testicles are in the scrotum. 
 
INDEX. 
 
 Abdomen, 1231 
 
 boundaries of, 1231 
 fascia of, deep, 433 
 superficial, 433, 1511 
 triangular, 1515 
 lymphatics of, 797, 800 
 muscles of, 432 
 
 actions of, 445, 449 
 deep, 449 
 dissection of, 432 
 superficial, 432 
 surface form of, 448 
 nerves of, cutaneous, 996 
 regions of, 1233 
 veins of, 755 
 viscera, 1234 
 
 walls of, apertures in, 1233 
 of, lymphatic vessels of, 
 deep, 801 
 superficial, 801 
 Abdominal aorta, 668 
 branches of, 671 
 relations of, 669 
 surface marking of, 670 
 surgical anatomv of, 670 
 aortic plexus, 1080, 1085 
 intercostal nerves, 996 
 muscles, 432 
 
 portion of oesophagus, 1223 
 ring, external, 436, 1514 
 internal, 446, 1518 
 pillars of, 1514 
 sacs, 1236 
 
 surface of bladder, 1433 
 
 viscera, position of, 1234 
 
 Abdomino-aortic glands, 799 
 
 -thoracic arch, 165 
 Abducent nerve, 1043 
 branches of, 1043 
 relations of, 1043 
 surgical anatomy of, 1044 
 Abductor hallucis muscle, 544 
 relations of, 544 
 indicis nauscle, 499 
 minimi digiti muscle, foot, 545 
 relations of, 545 
 hand, 498 
 
 relations of, 498 
 pollicis muscle, 495 
 relations of, 496 
 Aberrant ducts of epididymis, 
 
 1472 
 Absorbent glands, 774 
 Absorbents, 772 
 Accelerator urinse muscle, 457 
 Accessorius ad ilio-costalem mus- 
 cle, 419 
 pedis, 546 
 Accessorv anterior crural nerve 
 of Winslow, 1004 
 auditory nuclei, 950 
 chains to deep cervical glands, 
 
 787 
 cuneate nucleus, 948 
 
 Accessory descending palatine 
 canals, 116 
 gland of Rosenmiiller, 1141 
 ligament of atlas, 276 
 nucleus of eightli nerve, 1051 
 obturator nerve, 1004 
 olivary nuclei, 951 
 parotid gland, 1215 
 posterior palatine canals, 116, 
 
 135 
 processes, 57 
 quadrate cartilage, 1097 
 suprarenal glands, 1430 
 thyroid glands, 1403 
 veins, 731 
 Acervulus cerebri, 906 
 Acetabulum, 213 
 fossa of, 213 
 
 ligaments of, transverse, 330 
 Acoustic canal, external, 1148 
 
 tubercle, lateral, 950 
 Acromial angle, 176 
 region, fascia of, 470 
 muscles of, 470 
 actions of, 471 
 surgical anatomy of, 471 
 thoracic artery, 651 
 Acromio-clavicular articulation, 
 299 
 surface form of, 311 
 surgical anatomy of, 301 
 ligament, inferior, 299 
 superior, 299 
 Acromion process, 174 
 Additus glottidis inferior, 1371 
 Adductor brevis muscle, 520 
 relations of, 520 
 canal, 698 
 longus muscle, 519 
 
 relations of, 519 
 
 magnus muscle, 520 
 
 relations of, 521 
 
 minimus muscle, 520 
 
 obliquus hallucis muscle, 546 
 
 pollicis muscle, 497 
 
 relations of, 497 • 
 transversus hallucis muscle, 
 548 
 relations of, 548 
 pollicis muscle, 497 
 relations of, 497 
 tubercle, 225 
 Adipose tissue, pads of, 263 
 Aditus ad antrum, 87, 1150 
 Adminiculum linea* albae, 437 
 Afferent nerve tract, 961 
 
 vessels of kidneys, 1423 
 Agminated glands, 1296 
 Air cells, 1396 
 
 sinus, 82 
 Ala cinerea, 945 
 
 lobuli centralis, 928 
 nasi, 1096 
 
 artery of, 607 
 Alse of cerebellum, 928 
 of ethmoid, 99 
 
 Alae of sacrum, 64 
 
 of vomer, 121, 143 
 Alar cartilage, greater, 1097 
 lesser, 1097 
 ligaments, 278 
 thoracic artery, 651 
 Alcock's canal, 1011, 1536 
 Alimentary canal, 1193 
 
 development of, 1236 
 Alveolar artery, 615 
 inferior, 614 
 superior, 615 
 ducts, 1378 
 hare-lip. 111 
 processes, 140 
 
 of superior maxillary, 109 
 Alveoli, mucous, 1218 
 pulmonary, 1378 
 serous, 1218 
 of stomach, 1278 
 of teeth, development of, 1207 
 Alveus, 896 
 
 Amacrine cells of retina, 1125 
 Ameoblasts, 1206 
 Amphiarthrosis, 264. 
 AmpuUise of Fallopian tube, 1497 
 membranaceae, 1170 
 ossea, 1165 
 tubuli lactiferi, 1507 
 of Vater, 1345 
 Amygdalfv, 1213 
 
 of cerebellum, 931 
 Amygdaloid nucleus, 891 
 Anal canal, 1315 
 
 areolar coat of, 1318 
 mucous membrane of, 1318 
 muscular coat of, 1317 
 relations of, 1316 
 serous coat of, 1316 
 structure of, 1316 
 submucous coat of, 1318 
 fascia, 454, 1546 
 pockets, 1319 
 valves, 1319 
 Anastomosis of arteries, 583 
 
 circumpatellar, 711 
 Anastomotic vein of Trolard, 735 
 Anastomotica magna of brachial, 
 656 
 of femoral, 707 
 Anatomical neck of humerus, 177 
 
 of scapula, 175 
 Anconeus muscle, 487 
 
 relations of, 487 
 Andersch, ganglion cf, 1056 
 Angle, acromial, 176 
 cephalo-auricular, 1144 
 of jaw, 124 
 lateral, inferior, 63 
 of Ludwig, 165 
 nasal, 105 
 of OS pubis, 212 
 of ribs,, 161 
 Rolandic, 867 
 sacro- vertebral. 61 
 of sternum, 157 
 
 ( 1549 ) 
 
1550 
 
 INDEX 
 
 Angle, subscapular, 172 
 Angular artery, 607 
 convolution, 876 
 gyrus, 876 
 process, external, 80, 140 
 
 internal, 80, 140 
 vein, 726 
 Ankle bone, 244 
 bursse of, 543 
 
 -joint, articulations of, 347 
 ligaments of, 347 
 surface form of, 351 
 surgical anatomy of, 351 
 Annectant gyrus, deep, 867 
 first, 876 
 fourth, 877 
 second, 876 
 third, 877 
 Annular ligament of ankle, an- 
 terior, 541 
 external, 542 
 internal, 542 
 of radius and ulnar, 314 
 of stapes, 1161 
 of wrist, anterior, 491 
 posterior, 493 
 plexus, 1111 
 Annulus ciliaris, 1115 
 
 ovalis, 567 
 Ano-coccygeal body of Syming- 
 ton, 1316 
 Ansa hypoglossi, 1066 
 lenticularis, 915 
 peduncularis, 892 
 of Vieussens, 1076 
 Ante-cubital glands, 789 
 Anterior angle of ribs, 161 
 
 annular ligament of ankle, 541 
 
 of wrist, 491 
 atlanto-axial ligament, 274 
 atlo-axoid ligament, 274 
 auricular artery, 611 
 
 nerves, 1038 
 bicipital ridge, 179 
 branches of superior cervical 
 
 ganglion, 1076 
 cardiac plexus, 1081 
 carpal arch, 659 
 of ulnar, 663 
 cerebellar notch, 926 
 cerebral artery, 626 
 chamber of eye, 1129 
 chondro-sternal ligament, 288 
 
 -xiphoid ligament, 288 
 choroid artery, 628 
 ciliary arteries, 625 
 clinoid process, 131 
 commissure of cerebrum, 896 
 
 of cord, 839 
 common ligament, 269 
 communicating artery of ul- 
 nar, 662 
 condyloid foramen, 73, 133, 
 136 
 fossa, 136 
 cornu of lateral ventricle, 889 
 coronary plexus, 1081 
 costo-vertebral ligament, 284 
 
 -xiphoid ligament, 288 
 crescentic lobe, 928 
 crucial ligament, 337 
 crural nerve, 1004 
 
 accessory, of Winslow, 
 1004 
 deep cervical vein, 733 
 divisions of cervical nerves, 
 971 
 of coccygeal nerves, 1009 
 of dorsal nerves, 993 
 of lumbar nerves, 998 
 of thoracic nerves, 993 
 
 Anterior dental canal, 107 
 ethmoidal canal, 82, 100 
 
 cells, 101 
 
 foramen, 82, 130, 141 
 
 sinuses, 101 
 extremity of ribs, 161 
 facial vein, 726 
 femoral region, muscles of, 512 
 fontanelle, 78, 103 
 fossa of skull, 130 
 gluteal line, 207 
 humeral region, muscles of, 
 
 474 
 inferior cerebellar artery, 640 
 
 spinous process of ilium, 210 
 intercostal arteries, 644 
 
 veins, 752 
 internal frontal artery, 627 
 interosseous artery of ulnar, 
 662 
 
 nerve, 987 
 intersternal ligament, 290 
 intertrochanteric line, 223 
 jugular vein, 728 
 ligament of Helmholtz, 1160 
 
 of malleus, 1160 
 
 of wrist, 318 
 longitudinal ligament, 269 
 
 spinal veins, 754 
 mediastinal glands, 811 
 mediastinum, 1389 
 medullary velum, 943 
 meningeal artery, 622 
 nares, 142, 1098 
 nasal spine. 111, 139, 143 
 occipito-atlantal ligament, 276 
 olfactory lobule, 880 
 orbital convolution, 874 
 palatine canal, 143 
 
 fossa, 110, 133 
 
 nerve, 1035 
 perforated space, 881 
 perforating arteries, 644 
 peroneal artery, 718 
 pillars of fornix, 895 
 
 of soft palate, 1212 
 pubic ligament, 296 
 pulmonary nerves, 1061 
 
 plexus, 1059, 1061, 1082 
 radial carpal artery, 659 
 radio-ulnar ligament, 315 
 
 region, muscles of, 479 
 recurrent tibial artery, 713 
 region of skull, 139 
 root of spinal nerves, 965 
 sacral foramina, 62 
 sacro-coccygoal ligament, 294 
 
 -iliac ligament, 292 
 
 -sciatic ligament, 293 
 scapular region, muscles of, 
 
 471 
 spinal artery, 638 
 sterno-clavicular ligament, 298 
 
 -costal ligament, 288 
 subarachnoid space, 853 
 superior dental nerve, 1033 
 
 ligament, 285 
 
 spinous process of ilium, 210 
 surface of liver, 1327 
 
 of stomach, 1269 
 temporal artery, 611, 640 
 
 diploic vein, 734 
 thoracic nerve, 984 
 tibial arterv, 711 
 
 gland, 795 
 
 nerve, 1016 
 
 veins, 758 
 tibio-fibular region, muscles of, 
 531 
 
 -tarsal ligament, 347 
 triangle of neck, 616 
 
 Anterior tubercle of cervical ver- 
 tebra, 50 
 of optic thalamus, 904 
 tympano-malleolar ligament. 
 
 1156 
 ulnar recurrent artery, 662 
 
 vein, 745 
 vertebral region, muscles of, 
 406 
 vein, 733 
 wall of tympanum, 1153 
 Antero-lateral fissure, 838 
 fontanelle, 103 
 ganglionic arteries, 628 
 tract of cord, 842 
 -median fissure, 837 
 
 ganglionic arteries, 627 
 -posterior diameter of pelvis, 
 217 
 Antihehx, 1144 
 fossa of, 1144 
 Antitragicus muscle, 1147 
 Antitragus, 1145 
 Antrum of Highmore, 108 
 mastoid, 87 
 opening of, 1153 
 of pylorus, 1271 
 tympanic, 87 
 Anus, 1315 
 
 arteries of, 1320 
 lymphatics of, 809, 1321 
 nerves of, 1322 
 veins of, 1321 
 Aorta, 587 
 
 abdominal, 668 
 arch of, 591 
 
 branches of, 593 
 peculiarities of, 591, 593 
 relations of, 591 
 surgical anatomy of, 592 
 ascending, 588 
 descending, 665 
 sinus of, great, 589 
 thoracic, 665 
 transverse, 590 
 Aortic isthmus, 591 
 
 opening of diaphragm, 429 
 
 of heart, 566 
 semilunar valves, 572 
 sinus of Valsalva, 573 
 spindle, 591 
 vestibule of Sibson, 572 
 Apertura scaliE vestibuli cochleae, 
 1165 
 tympanica canaliculi chorda;, 
 1153 
 Aperture of nose, cartilage of, 
 
 1097 
 Apical coil of cochlea, 1167 
 
 glands, 1091 
 Aponeurosis of external oblique, 
 434, 1513 
 of internal oblique, 439 
 palatine, 404 
 pharyngeal, 402, 1223 
 Sibson's, 1385 
 of soft palate, 1212 
 supra-hyoid, 394 
 vertebral, 411, 416 
 Apophysis, 34 
 Appendages of eye, 1137 
 of skin, 1185 
 of uterus, 1497 
 Appendices epiploic^, 1260 
 Appendicular artery, 676 
 
 vein, 768 
 Appendiculo-ovarian ligament of 
 
 Clado, 1304 
 Appendix of auricle, left, 568 
 right, 565 
 ensiform, 158 
 
INDEX 
 
 1551 
 
 Anoendix, vermiform, 1303 
 
 -viphoid, 158 
 Aqueduct of Sylvius, 912 
 Atjuaeductus coclileai, 89, 136, 
 1167 
 Fallopii, 89 
 
 eminence of, 1152 
 vestibuli, 89, 133, 1165 
 Aqueous chamber, 1128 
 
 humor, 1128 
 Arachnoid of brain, 851 
 structure of, 853 
 of cord, 834 
 
 structure of, 835 
 vilH, 854 
 Arangi, body of, 571 
 Arantius, ventricle of, 944 
 Arbor vitae of cerebellum, 931 
 
 of uterus, 1492 
 Arch of aorta, 591 
 branches of, 593 
 peculiarities of, 591, 593 
 relations of, 591 
 surgical anatomy of, 592 
 of atlas, 51 
 
 axillary, 413, 464, 646 
 carpal, anterior, 659 
 
 posterior, 659 
 crural, deep, 44S, 1531 
 
 superficial, 436, 1529 
 palmar, deep, 658 
 superficial, 664 
 plantar, 720 
 pubic, 217 
 supraorbital, 80 
 tarsal, inferior, 623 
 
 superior, 623 
 of vertebra, 48 
 zygomatic, 138 
 Arciform fibres of medulla, 942 
 Arcuate fibres of medulla, 942 
 ligaments, external, 427, 449 
 internal, 427 
 middle, 427 
 Areus senilis, 1110 
 Area of Broca, 881 
 cribrosa media, 89 
 
 superior, 89 
 vestibularis, inferior, 1176 
 superior, 1176 
 Areolae of bone, primary, 44 
 secondary, 45 
 of mamma, 1504 
 Areolar coat of anal canal, 1318 
 of intestine, large, 1318 
 
 small, 1290 
 of liver, 1337 
 of cEsophagus, 1229 
 of rectum, 1318 
 of stomach, 1274 
 tissue, subcutaneoas, 1180 
 subserous, 1245 
 Arm, arteries of, 637 
 bones of, 177 
 fascise of, 474 
 deep, 470 
 superficial, 470 
 lymphatics of, 789 
 muscles of, 470, 474 
 dissection of, 470, 474 
 surgical anatomy of, 478 
 nerves of, 977 
 veins of, 744 
 Arnold's ganglion, 1039 
 branches of, 1039 
 nerve, 1060 
 
 canal for, 90 
 ponticulus of, 939 
 Arteria centralis retinae, 626 
 
 magna, 587 
 Artcrise hallucis, 716 
 
 Arteriae priuceps cervicis, 609 
 receptaculi, 622 
 uterina ovarica, 688 
 Artery or arteries, 583 
 alveolar, 615 
 
 inferior, 614 
 
 superior, 615 
 anastomosis of, 583 
 anastomotica magna of brach- 
 ial, 656 
 of feinoral, 707 
 angular, 607 
 antero-lateral ganglionic, 628 
 
 -median ganglionic, 627 
 aorta, 587 
 
 abdominal, 668 
 
 arch of, 591 
 
 ascending, 588 
 
 descending, 665 
 
 thoracic, 665 
 appendicular, 676 
 arteriae receptaculi, 622 
 articular, of knee, 710, 711 
 auditory, 639 
 auricular, anterior, 611 
 
 posterior, 609 
 axillary, 647 
 azygos, of knee, 711 
 
 of vagina, 687 
 basilar, 639 
 brachial, 652 
 of brain, cortical, 631 
 bronchial, 666 
 buccal, 615 
 of bulb, 691 
 bulbar, 639 
 calcanean, external, 718 
 
 internal, 719 
 carotid, common, 595 
 
 external, 600 
 
 internal, 619 
 carpal arch, anterior, 659 
 posterior, 657 
 
 radial, anterior, 659 
 posterior, 659 
 
 ulnar, anterior, 663 
 posterior, 663 
 centralis retinae, 626 
 cerebellar, anterior inferior, 
 640 
 
 posterior inferior, 639 
 
 superior, 640 
 cerebral, anterior, 626 
 of cerebral hemorrhage, 628 
 
 middle, 627 
 
 posterior, 640 
 cervical, ascending, 641 
 
 deep, 646 
 
 superficial, 642 
 
 transverse, 642 
 choroid, anterior, 628 
 
 posterior, 640 
 ciliary, 625 
 circle of Willis, 640 
 circumflex, of arm, 651 
 
 iliac, deep, 697 
 superficial, 704 
 
 of thigh, 705 
 cochlear, 1176 
 coccygeal, 692 
 cccliac, 671 
 colic, left, 678 
 
 middle, 676 
 
 right, 675 
 comes nervi ischiadic!, 693 ' 
 mediana, 663 
 phrenici, 644 
 communicating, anterior cere- 
 bral. 627 
 
 to deep palmar arch, 664 
 
 posterior cerebral, 628 
 
 Artery or arteries, communicat- 
 ing, of ulnar, anterior, 662 
 coronary, 671 
 
 of heart, 590 
 
 of Up, inferior, 607 
 superior, 607 
 of corpus cavernosum, 691 
 cremasteric, 696 
 crico-thyroid, 602 
 cystic, 674 
 dental, anterior, 605 
 
 inferior, 614 
 
 posterior, 615 
 digital, plantar, 659 
 
 of uhiar, 664 
 dorsalis hallucis, 716 
 
 indicis, 659 
 
 linguae, 603 
 
 nasi, 625 
 
 pedis, 714 
 
 pollicis, 659 
 
 scapulffi, 651 
 of dura mater of brain, 848 
 epigastric, deep, 696 
 
 internal, 696 
 
 superficial, 704 
 
 superior, 645 
 ethmoidal, 623 
 facial, 604 
 
 transverse, 611 
 femoral, 697 
 
 common, 699 
 
 deep, 704 
 fibular, superior, 713 
 frontal, 611 
 
 from anterior cerebral, 628 
 
 from middle cerebral, 628 
 
 from ophthalmic, 625 
 ganglionic, postero-lateral, 640 
 
 postero-median, 640 
 gastric, 671, 674 
 gastro-duodenalis, 673 
 
 -epiploica dextra, 673 
 sinistra, 674 
 gluteal, 694 
 
 inferior, 693 
 hemorrhoidal, inferior, 690 
 
 middle, 687 
 
 superior, 678 
 of head, 595 
 of heart, 577 
 hepatic, 672 
 histology of, 584 
 hyoid branch of lingual, 603 
 of superior thyroid, 602 
 hypogastric, 683 
 
 in foetus, 684 
 ileo-colic, 675 
 iliac, circumflex, deep, 697 
 superficial, 704 
 
 common, 681 
 
 external, 694 
 
 internal, 683 
 ilio-lumbar, 693 
 infra-hyoid branch of superior 
 
 thyroid, 602 
 infraorbital, 615 
 innominate, 593 
 inosculation of, 583 
 intercostal, 667 
 
 anterior, 644 
 
 superior, 645 
 interlobar, 1423 
 interosseous, of foot, 715 
 of hand, 660 
 ulnar, 662 
 anterior, 662 
 posterior, 663 
 labial, inferior, 607 
 lachrymal, 623 
 laryngeal, inferior, 641 
 
1552 
 
 INDEX 
 
 Artery or arteries, laryngeal, 
 
 superior, 602 
 lateralis nasi, 607 
 lenticulo-striate, 628 
 lingual, 603 
 
 deep, 604 
 of lower extremity, 697 
 lumbar, 680 
 lymphatics of, 586 
 malar from lachrymal, 623 
 malleolar, 713, 7i9 
 mammary, internal, 643 
 mandibular, 614 
 marginal, 590 
 masseteric, 615 
 mastoid, 609, 670 
 maxillary, external, 604 
 
 internal, 612 
 mediastinal, 644 
 
 posterior, 666 
 meningeal, 609, 610 
 
 anterior, 622 
 
 middle, 613 
 
 from occipital, 609 
 
 from pharyngeal, 610 
 
 posterior, 638 
 
 small, 614 
 
 from vertebral, 638 
 mesenteric, inferior, 677 
 
 superior, 675 
 metatarsal, 715 
 musculo-phrenic, 644 
 mylo-hyoid, 614 
 nasal, from ophthalmic, 625 
 
 of septum, inferior, 607 
 superior, 615 
 naso-palatine, 616 
 of neck, 595 
 nerves of, 586 
 nutrient, of femur, 707 
 
 of fibula, 718 
 
 of humerus, 656 
 
 of tibia, 718 
 obturator, 688 
 occipital, 608 
 cfisophageal, 641, 666 
 ophthalmic, 622 
 orbital, 611 
 
 internal, 627 
 ovarian, 680 
 palatine, ascending, 606 
 
 descending, 615 
 
 inferior, 606 
 
 posterior, 615 
 palmar arch, deep, 658 
 
 superficial, 664 
 palpebral, external, 623 
 
 internal, 623 
 pancreatic, 674 
 pancreatico-duodenalis, infe- 
 rior, 675 
 superior, 674 
 parietal, 611 
 
 ascending, 628 
 parieto-sphenoidal, 628 
 
 -temporal, 628 
 of penis, dorsal, 689, 1458 
 perforating, anterior, 644 
 
 of foot, 720 
 
 of hand, 660 
 
 of thigh, 706 
 pericardiae, 644, 666 
 of pericardium, 561 
 perineal, superficial, 690 
 
 transverse, 691 
 peroneal, 717 
 
 anterior, 718 
 
 posterior, 718 
 pharyngeal, ascending, 610 
 phrenic, inferior, 680 
 
 superior, 644 
 
 Artery or arteries of pia mater 
 
 of brain, 856 
 plantar, digital, 720 
 
 external, 720 
 
 internal, 719 
 popliteal, 707 
 
 postero-median ganglionic, 628 
 prevertebral, 610 
 princeps cervicis, 610 
 
 hallucis, 716 
 
 pollicis, 660 
 profunda of arm, inferior, 656 
 superior, 655 
 
 femoris, 704 
 pterygo-palatine, 616 
 pterygoid, 614 
 pudic, accessory, 690 
 
 external, deep. 704 
 superficial, 704 
 
 internal, in female, 692 
 in male, 689 
 pulmonary, 587 
 pyloric, inferior, 673 
 
 superior, 673 
 radial, 657 
 radialis indicis, 660 
 ranine, 604 
 recurrent, palmar, 660 
 
 radial, 659 
 
 tibial, anterior, 713 
 posterior, 713 
 
 ulnar, anterior, 662 
 posterior, 662 
 renal, 678 
 
 inferior, 1423 
 of round ligament, 688 
 sacral, lateral, 693 
 
 middle, 681 
 scapular, posterior, 642 
 sciatic, 692 
 sigmoid, 678 
 spermatic, 679 
 spheno-palatine, 616 
 spinal, anterior, 638 
 
 lateral, 638 
 
 posterior, 639 
 splenic, 674 
 sternal, 644 
 
 sterno-mastoid, 602, 609 
 stylo-mastoid, 610 
 subclavian, 631 
 subcostal, 667 
 sublingual, 604 
 submaxillary, 606 
 submental, 606 
 subscapular, 651 
 superficialis vola?, 659 
 supra-acromial, 642 
 
 -hyoid, 603 
 supraorbital, 623 
 suprarenal, 678 
 suprascapular, 641 
 suprasternal, 642 
 sural, 710 
 tarsal, 715 
 temporal, 61 1 
 
 anterior, 611, 640 
 
 deep, 614 
 
 middle, 611 
 
 posterior, 611, 640 
 thoracic, acromial, 651 
 
 alar, 651 
 
 long, 651 
 
 superior, 650 
 thyroid axis, 640 
 
 inferior, 641 
 
 superior, 601 
 of thyroid gland, 602 
 thyroidea ima, 594 
 tibial, anterior, 711 
 
 posterior, 716 
 
 Artery or arteries, tibial, recui- 
 rent, anterior, 713 
 posterior, 713 
 tonsillar, 606 
 tracheal, 641 
 transversalis colli, 642 
 
 humeri, 641 
 of trunk, 665 
 
 tympanic, from ascending 
 pliaryngeal, 610 
 from internal carotid, 622 
 from internal maxillarv, 613 
 ulnar, 660 
 
 recurrent, anterior, 662 
 posterior, 662 
 umbilical, in foetus, 579, 685 
 of upper extremity, 631 
 uterine, 687 
 vaginal, 687 
 of vas deferens, 686 
 vasa brevia, 674 
 
 intestini tenuis, 675 
 vasorum of, 586 
 vertebral, 637 
 vesical, inferior, 686 
 middle, 686 
 superior, 686 
 Vidian, 616 
 Arteriolae recta;, 1423 
 Arthrodia, 266 
 Arthrology, 259 
 
 Articular arteries of knee, azygos, 
 711 
 inferior, 711 
 superior, 710 
 cartilage, 259 
 circumference of ulna, 189 
 eminence of temporal bone, 84 
 lamella of bone, 259 
 processes of a vertebra, 49 
 synovial membrane, 262 
 Articulations, 259 
 
 acromio-clavicular, 299 
 of ankle-joint, 347 
 astragalo-scaphoid, 354 
 atlanto-axial, 276 
 of atlas with axis, 274 
 
 with occipital bone, 276 
 biaxial, 265 
 
 calcaneo-astragaloid, 352 
 -cuboid, 353 
 -scaphoid, 353 
 carpo-metacarpal, 321 
 of carpus, 319 
 first row, 319 
 second row, 319 
 chondro-sternal, 288 
 coccygeal, 294 
 condyloid, 265 
 costo-central, 283 
 -chondral, 290 
 -sternal, 287 
 -transverse, 285 
 -vertebral, 283 
 crico-arytenoid, 1367 
 
 -thyroid, 1367 
 of cuboid with cuneiform, 355 
 
 with scaphoid, 355 
 of elbow-joint, 308 
 femoro-tibial, 335 
 of hip, 325 
 immovable, 264 
 interchondral, 289 
 interneural, 272 
 of knee, 334 
 of lower extremit}', 325 
 
 jaw, 280 
 metacarpo-phalangeal, 324 
 metatarso-phalangeal, 359 
 mixed, 264 
 movable, 265 
 
INDEX 
 
 1553 
 
 Articulations, occipito-atlantal, 
 276 
 
 -axial, 278 
 of ossa pubis, 296 
 of ossicles of t3^mpanum, 1160 
 of pelvis, 292 
 of phalanges of foot, 359 
 
 of hand, 325 
 radio-carpal, 317 
 
 -ulnar, 313 
 inferior, 315 
 middle, 314 
 superior, 314 
 by reciprocal reception, 265 
 of ribs with vertebrcD, 283 
 sacro-coccygeal, 294 
 
 -iliac, 292 
 
 -sciatic, 292 
 
 -vertebral, 290 
 of sacrum with coccyx, 294 
 
 and ilium, 292 
 
 and iscliium, 292 
 scapulo-clavicular, 299 
 of shoulder-joint, 303 
 of spine with cranium, 276 
 sterno-clavicular, 297 
 of sternum, 290 
 tarso-metatarsal, 357 
 of tarsus, 352 
 temporo-mandibular, 280 
 
 -maxillary, 138 
 tibio-fibular, 345 
 
 -tarsal, 347 
 of trunk, 269 
 of upper extremity, 297 
 of vertebral column, 269 
 
 with pelvis, 290 
 of wrist, 317 
 Aryteno-epiglottidean folds, 
 
 1365 
 -epiglottideus muscle, 1373 
 Arj'tenoid cartilages, 1364 
 
 apex of, 1365 
 
 base of, 1365 
 
 surfaces of, 1364 
 glands, 1375 
 muscles, 1372 
 Arytenoideus muscle, 1372 
 Ascending aorta, 588 
 
 branches of, 590 
 
 relations of, 589 
 cervical artery, 641 
 colon, 1309 
 
 flexure of, hepatic, 1309 
 frontal artery, 628 
 
 convolution, 872 
 lumbar vein, 753, 765 
 
 right, 752 
 mesocolon, 1258 
 nerve tract, 961 
 oblique muscle of abdomen, 
 
 437 
 palatine artery, 606 
 parietal artery, 628 
 
 convolution, 876 
 pharjTigeal artery, 610 
 ramus of ischium, 212 
 
 of pubis, 213 
 root of fifth nerve, 948, 1026 
 vena cava, 764 
 Association fibres of cerebrum, 
 
 916 
 Astragalo-scaphoid articulation, 
 354 
 
 ligament, superior, 354 
 Astragalus, 244 
 
 articulations of, 245 
 body of, 244 
 head of, 244 
 neck of, 244 
 surfaces of, 244, 245 
 
 Asterion, 75, 138 
 Atlanto-axial ligament, anterior, 
 274 
 posterior, 275 
 -odontoid joint of Cruveilhier, 
 274 
 Atlas, 50 
 
 arches of, 51 
 
 attachment of muscles to, 60 
 development of, 59 
 lateral masses of, 51 
 ligament of, transverse, 275 
 processes of, 51 
 Atlo-axoid ligament, anterior, 
 274 
 posterior, 275 
 Atrabiliary capsules, 1430 
 Atria of left bronchus, 1378 
 Atrium, 1150 
 
 of nasal fossae, 1100 
 meatus, 145 
 Attic, 1150 
 
 tympanic, 87 
 AttoUens auric ulam muscle, 369 
 
 relations of, 369 
 Attrahens auriculam muscle, 369 
 
 relations of, 369 
 Auditory arteries, 1176 
 internal, 639 
 canal, external, 1148 
 meatus, external, 138, 1148 
 arteries of, 1149 
 cartilaginous portion of, 
 
 1148 
 lymphatics of, 1150 
 nerves of, 1150 
 osseous portion of, 1149 
 relations of, 1149 
 skin of, 1149 
 surface form of, 1150 
 veins of, 1150 
 internal, 133 
 fundus of, 1168 
 nerve, 1050 
 nuclei of, 925 
 origin of, 1050 
 roots of, 1050, 1051 
 surgical anatomy of, 1054 
 nuclei, 950 
 
 accessory, 950 
 dorsal, 950 
 inner, 950 
 ventral, 950 
 paths, 1053 
 process, 88 
 teeth, 1173 
 veins, 1176 
 Auerbach's plexus, 1299 
 Auricle of ear, 1144 
 of heart, fibres of, 575 
 left, 568 
 
 sinus of, 568 
 right, 565 
 sinus of, 565 
 Auricular appendices, 565 
 appendix, left, 568 
 
 right, 565 
 artery, anterior, 611 
 posterior, 609 
 branches of, 610 
 branch of pneumogastric nerve, 
 
 1060 
 fissure, 90, 136 
 nerves, anterior, 1038 
 great, 972 
 posterior, 1047 
 region, muscles of, 369 
 action of, 369 
 dissection of, 369 
 surface of sacrum, 63 
 vein, anterior, 726 
 
 98 
 
 Auricular vein, posterior, 727 
 Auriculo-temporal nerve, 1037 
 -ventricular groove of heart, 
 565 
 opening, left, 569 
 right, 566 
 Axes of pelvis, 218 
 Axilla, dissection of, 463 
 
 ligament of, suspensory, 464 
 surgical anatomy of, 645 
 Axillary arch, 413, 464, 646 
 artery, 646 
 
 branches of, 650 
 peculiarities of, 649 
 relations of, 648 
 surface marking of, 649 
 surgical anatomy of, 649 
 border of scapula, 174 
 fascia, 463, 646 
 •glands, 790 
 space, 645 
 veins, 747 
 
 surgical anatomy of, 748 
 Axis, 52 
 apex of, 52 
 
 attachment of muscles to, 60 
 body of, 52 
 cerebro-spinal, 832 
 coeliac, 671 
 cylinder of nerve-fibre, 822 
 
 of Purkinje, 822 
 development of, 59 
 ligament of malleus, 1161 
 odontoid process of, 52 
 cptic, 1106 
 pedicles of, 52 
 processes of, 53 
 thoracic, 651 
 thyroid, 640 
 visual, 1106 
 Axone of nerve-cells, 821 
 Azygos arteries, articular, 711 
 of vagina, 687 
 uvulsB muscle, 405 
 
 relations of, 405 
 veins, 752 
 larger, 752 
 left lower, 753 
 upper, 753 
 right, 752 
 smaller, 753 
 surgical anatomy of, 753 
 
 B 
 
 Back, fascia of, deep, 411 
 superficial, 411 
 muscles of, dissection of, 420 
 fifth layer, 420 
 first layer, 410 
 fourth layer, 417 
 second layer, 414 
 surface forms of, 424 
 third layer, 415 
 Baillarger, nerve-fibres of, 920 
 Band of Gennari, 918 
 of Giacomini, 879 
 of Meckel, 1160 
 Bartholin, duct of, 1217 
 
 glands of, 1482 
 Base of brain 881 
 of sacrum, 64 
 of skull, 130 
 surfaces of, 130 
 Basi-hyal of hyoid bone, 153 
 Basil coil of cochlea, 1167 
 Basilar artery, 639 
 branches of, 639 
 groove, 75 
 lymph-sinus, 1306 
 
1554 
 
 INDEX 
 
 Basilar membrane of cochlea, 
 1167 
 
 process, 71 
 
 sinus, 743 
 
 suture, 128 
 
 vein, 735 
 Basilic vein, 746 
 median, 746 
 Basis vertebranum, ven», 753 
 Basion, 73 
 
 Basket-cells of cerebellum, 936 
 Bauhin, valve of, 1308 
 Beak of corpus callosum, 886 
 Beaunis et Bouchard, table of 
 
 development of foetus from, 
 
 1547 
 Bechterew, nerve-fibres of, 920 
 
 nucleus of, 926, 1050 
 Bell, respiratory nerve of, exter- 
 nal, 983 
 internal, 974 
 Bertin, bones of, 97 
 
 columns of, 1416 
 
 ligament of, 328 
 Biaxial articulation, 265 
 Biceps flexor cubiti muscle, 475 
 
 muscles, 475, 529 
 bursa of, 476 
 relations of, 476, 530 
 Bichat, fissure of, 900 
 Bicipital fascia, 476, 746 
 
 groove, 179 
 
 ridges, 179 
 
 tuberosity, 190 
 Bicornate uterus, 1493 
 Bicuspid teeth, 1198 
 
 valve, 672 
 cusps of, 572 
 Bigelow, ligament of, 328 
 Bile, 1346 
 
 canaliculi, 1341 
 
 -capillaries, 1341 
 
 -duct, common, 1344 
 arteries of, 1346 
 dimensions of, 1345 
 lymphatics of, 806, 1346 
 nerves of, 1346 
 structure of, 1345 
 surgical anatomy of, 1347 
 veins of, 1346 
 
 papilla, 1288 
 Bipenniform muscles, 363 
 Bipolar cells, 820 
 Biventer cervicis muscle, 420 
 Biventral lobe of cerebellum, 931 
 Bladder, 1431 
 
 apex of, 1435 
 
 arteries of, 1439 
 
 base of, 1435 
 
 body of, 1435 
 
 cervix of, 1435 
 
 female, 1446 
 
 fundus of, 1435 
 
 ligaments of, 1435 
 
 lymphatics of, 802, 1439 
 
 mucous coat of, 1437 
 membrane of, 1438 
 
 muscular coat of, 1437 
 
 neck of, 1435 
 
 nerves of, 1440 
 
 serous coat of, 1437 
 
 structure of, 1437 
 
 submucous coat of, 1437 
 
 summit of, 1435 
 
 surface form of, 1440 
 
 surfaces of, 1433 
 inner, 1438 
 
 surgical anatomy of, 1440 
 
 trigone of, 1438 
 
 veins of, 1439 
 Blade bone, 171 
 
 Blind spot, 1121 
 Blood supply of cord, 840 
 Blood-vascular system, 555 
 Blood-vessels of bone, 39 
 Bochdalek, ganglion of, 1033 
 Body, carotid, 1409 
 
 cavernous, artery of, 691 
 
 coccygeal, 1410 
 
 pituitary, 882 
 
 thyroid, 1401 
 
 of a vertebra, 49 
 Bones, acetabulum, 213 
 
 apophysis of, 34 
 
 areolae of, primary, 44 
 secondary, 45 
 
 astragalus, 244 
 
 atlas, 50 
 
 axis, 52 
 
 of Bertin, 97 
 
 blood-vessels of, 39 
 
 breast, 155 
 
 calcaneum, 242 
 
 canalicuh of, 46 
 
 cancellous, 35 
 
 carpus, 193 
 
 chemical composition of, 41 
 
 clavicle, 167 
 
 coccyx, 65 
 
 compact, 35 
 
 cranial, 71 
 
 cuboid, 245 
 
 cuneiform of, foot, 247 
 of hand, 197 
 
 diploe of, 34 
 
 ear, 1158 
 
 eminences and depressions of, 
 34 
 
 epactal, 103 
 
 epicteric, 103 
 
 epiphysis of, 34 
 
 ethmoid, 98 
 
 of face, 104 
 
 femur, 221 
 
 fibula, 237 
 
 flat, 34 
 
 of foot, 239 
 
 frontal, 79 
 
 growth of, 42 
 of hand, 193 
 
 Haversian canals of, 38 
 systems of, 38 
 
 humerus, 177 
 
 hvoid, 153 
 
 ilium, 207 
 
 incus, 1158 
 
 inter-maxillary, 110 
 
 irregular, 34 
 
 ischium, 210 
 
 of jaw, upper, changes pro- 
 duced in, by age, 112 
 
 lachrymal, 112 
 
 lacuniB of, 38 
 
 lamella of, 38 
 articular, 259 
 
 of leg, 230 
 
 lingual, 153 
 
 long, 33 
 
 lymphatics of, 41 
 
 malar, 113 
 
 malleus, 1158 
 
 marrow of, 36 
 
 maxillary, inferior, 122 
 superior, 105 
 
 medullary spaces of, 45 
 
 metacarpal, 200 
 
 metatarsal, 249 
 
 mixed, 34 
 
 nasal, 104 
 
 navicular, 195, 246 
 
 nerves of, 41 
 
 occipital, 71 
 
 Bones, orbicular, 1159 
 OS calcis, 242 
 
 innominatum, 207 
 
 magnum, of carpus, 199 
 ossification of, 42 
 
 intracartilaginous, 43 
 
 intramembranous, 43 
 palate, 115 
 parietal, 76 
 patella, 230 
 pelvic, 215 
 periosteum of, 37 
 phalanges of foot, 252 
 
 of hand, 204 
 pisiform, 197 
 ploughshare, 120 
 pre-maxillary, 110 
 pubis, 212 
 radius, 190 
 ribs, 159 
 sacrum, 61 
 scaphoid, of foot, 246 
 
 of hand, 195 
 scapula, 171 
 semilunar, 196 
 sesamoid, 257 
 short, 33 
 sphenoid, 92 
 
 spongy, 97 
 sternum, 155 
 structure of, 34 
 supernumerary, 103 
 surface of, 34 
 sutural, 103 
 tarsus, 242 
 temporal, 83 
 thigh, 221 
 tibia, 233 
 trapezium, 198 
 trapezoid, 198 
 turbinated, inferior, 119 
 
 middle, 101 
 
 sphenoidal, 143 
 
 superior, 101 
 tvmpanic 91 
 ulna, 184 
 unciform, 199 
 veins of, 41 
 
 vertebra prominens, 53 
 vertebrae, cervical, 49 
 
 dorsal, 53 
 
 lumbar, 56 
 
 thoracic, 53 
 vomer, 120 
 wedge, 247 
 Wormian, 103 
 Bony canal of cochlea, 1167 
 Bosom, 1503 
 Bowman's capsule, 1418 
 glands of, 1101 
 membrane, 1109 
 muscle, 1115 
 Brachiaof corpora quadrigemina, 
 
 911 
 Brachial artery, 652 
 
 branches of, 655 
 
 peculiarities of, 653 
 
 relations of, 652 
 
 surface marking of, 654 
 
 surgical anatomy of, 654 
 lymphatic glands, 788 
 plexus, 977 
 
 branches of, 981 
 
 relations of, 980 
 
 surgical anatomy of, 991 
 region, anterior, muscles of ,479 
 
 posterior, muscles of, 486 
 veins, 747 
 Brachialis anticus muscle, 476 
 
 relations of, 476 
 Brachio-cephalic vein, 750 
 
INDEX 
 
 1555 
 
 IJrachium, 904 
 Brain, 857 
 
 arteries of, cortical, 631 
 
 base of, 881 
 
 blood-vessels of, 629 
 
 capsule of, external, 894 
 internal, 894 
 
 commissures of, 903 
 
 communication of the parts of, 
 863 
 
 convolutions of, 865 
 
 development of, 857 
 
 dissection of, 847 
 
 dura mater of, 847 
 
 ganglionic vessels of, central, 
 630 
 
 general considerations and di- 
 visions of, 864 
 
 gyri of, 865 
 
 hemispheres of, 864 
 surfaces of, under, 881 
 
 infundibulum of, 882 
 
 little, 926 
 
 lobes of, 872 
 
 membranes of, arachnoid, 861 
 
 meninges of, 847 
 
 pia mater of, 854 
 
 sand, 906 
 
 ventricle of, fifth, 897 
 lateral, 888 
 third, 901 
 Vergas, 896 
 
 weight of, 951 
 Breast bone, 155 
 Bregma, 129 
 Bregmatic fontanelle, 103 
 Breschet, canals of, 733 
 Brim of pelvis, 217 
 Broad ligaments of liver, 1333 
 
 of uterus, 1490 
 Broca, area of, 881 
 
 "cap" of, 874 
 
 convolution of, 874 
 Bronchi, 1376 
 
 relations of, 1376 
 Bronchial arteries, 666 
 
 branch of innominate, 594 
 
 glands, 1380 
 
 septum, 1380 
 
 veins, 753 
 Bronchus, left, 1378 
 
 right, 1376 
 Brown striae of Retzius, 1204 
 Bruch, membrane of, 1114 
 Brunner's glands, 1295 
 Bruns, falciform margin of, 515 
 
 space of, 388 
 Bubonocele, 1521 
 Buccal artery, 615 
 
 cavity, 1193 
 
 glands, 1195 
 
 lymphatic glands, 782 
 
 nerve, 1037, 1049 
 Buccinator crest, 124 
 
 glands, 782 
 
 muscle, 380 
 
 relations of, 380 
 
 nerve, 1037 
 Bucco-pharvngeal fascia, 380, 
 
 388, 401, "1222 
 Bulb, artery of, 691 
 
 surgical anatomy of, 691 
 
 of corpus cavernosum, 1456 
 spongiosum, 1457 
 
 of internal jugular vein, 729 
 
 nerve to, 1013 
 
 olfactory, 880, 1019 
 
 spinal, 938 
 
 of urethra, male, 1458 
 
 vaginal, 1483 
 Bulbar arteries, 639 
 
 Bulbar portion of conjunctiva, 
 1140 
 
 of spinal accessory nerve, 
 1063 
 Bulbi vestibuli, 1483 
 Bulbo-cavernous muscle, 457 
 Bulla ethmoidalis, 145, 1099 
 Bundle of Vicq d'Azvr, 883 
 Burdach, tract of, 839, 843 
 Bursse of ankle, 543 
 anserina, 530 
 of biceps muscle, 476 
 of coraco-brachialis muscle, 
 
 475 
 of elbow, 311 
 of extensor carpi radialis bre- 
 
 vior muscle, 486 
 of foot, 543 
 
 of gastrocnemius muscle, 534 
 of great trochanter, 331 
 gluteo-femoral, 331 
 of hand, 492 
 of hip, 330 
 
 iliac, subtendinous, 331 
 ilio-pectineal, 330 
 infrapatellar, deep, 340 
 infraspinatus, 305, 473 
 ischio-gluteal, 331 
 of knee, 340 
 
 of latissimus dorsi muscle, 474 
 obturator, 331 
 
 intemus muscle, 525 
 olecranon, 311 
 
 subcutaneous, 477 
 ovarian, 1490 
 patellar, 518 
 pharyngeal, 1224 
 prepatellar, 340 
 of pyriformis muscle, 525 
 of semimembranous muscle, 
 
 531 
 of shoulder, 305 
 stemo-hyoid, 391 
 subacromial, 305, 471 
 subcutanea prominentise larvn- 
 
 gese, 1362 
 subcutaneous acromial, 305 
 
 trochanteric, 331 
 subdeltoid, 305, 471 
 subscapular, 305, 472 
 suprapatellar, 340 
 synovial, subcutaneous, 263 
 
 subtendinous, 263 
 of tendo Achillis, 535 
 tibial, subcutaneous, 340 
 of tibialis anticus muscle, 532 
 wrist, 492 
 Bursal synovial membrane, 263 
 
 C-ECAL fold, inferior, 1264 
 
 superior, 1263 
 Csecum, 1300 
 
 arterieg of, 1305 
 
 interior of, 1303 
 
 lymphatics of, 1306 
 
 supports of, 1302 
 
 veins of, 1306 
 
 vestibulare, 1170 
 Cffilum, 1236 
 Cajal, horizontal cells of, 1125 
 
 neurones of, 919 
 Calamus scriptorius, 943 
 Calcaneal nerves, external, 1014 
 
 internal, 1015 
 Calcanean artery, external, 718 
 
 internal, 719 
 Calcaneo-astragaloid ligament, 
 
 external, 352 
 
 Calcaneo-astragaloid ligament, 
 internal, 352 
 posterior, 352 
 
 -cuboid ligament, internal, 353 
 long, 353 
 short, 353 
 superior, 353 
 
 -navicular ligament, 353 
 
 -plantar nerve, 1015 
 
 -scaphoid ligament, external, 
 353 
 inferior, 354 
 internal, 354 
 superior, 353 
 Calcaneus, 242 
 
 anterior extremity of, 242 
 
 articulations of, 244 
 
 attachment of muscles to, 244 
 
 body of, 242 
 
 posterior extremity of, 242 
 
 process of, greater, 243 
 lesser, 243 
 
 surfaces of, 242, 243 
 
 tuberosity of, 243 
 Calcar avis, 889 
 
 femorale, 227 
 Calcarine fissure, 870 
 Calf bone, 237 
 Calices of kidney, 1415 
 Callosal convolution, 879 
 
 sulcus, 879, 885 
 Calloso-marginal sulcus, 870 
 Calvaria, 71 
 Camper, fascia of, 433 
 Canalis centralis cochlea;, 89 
 
 reuniens of Hensen, 1170 
 
 spiralis modioli, 1169 
 Canaliculi of bone, 46 
 Canaliculus tympanicus, 1151 
 Canals, acoustic, external, 114& 
 
 adductor, 698 
 
 Alcock's, 1011, 1536 
 
 alimentary, 1193 
 
 anal, 1315 
 
 of appendix, 1304 ,. 
 
 for Arnold's nerve, 90 
 
 auditory, 1148 
 
 of Breschet, 733 
 
 carotid, 136 
 
 central, of cord, 840 
 
 cervical, 1491 
 
 for chorda tympani, 8 
 
 of Cloquet, 1129 
 
 of cochlea, 1167 
 membranous, 1172 
 
 crural, 1531 
 
 dental, 1202 
 anterior, 107 
 inferior, 324 
 posterior, 106 
 
 diploic, 733 
 
 ethmoidal, 82, 100 
 
 for Eustachian tube, 1154 
 
 fascial, 1536 
 
 femoral, 509, 1531 
 
 Haversian, 38 
 
 of Huguier, 84, 1047 
 
 Hunter's, 521, 698 
 
 hyaloid, 1129 
 
 incisor, 110 
 
 infraorbital, 107, 140 
 
 inguinal, 448, 1517 
 
 for Jacobson's nerve, 90 
 
 lachrymal, 1142 
 
 malar, 114 
 
 medullary, 857 
 
 naso-palatine, 121 
 
 neural, 857 
 
 neurenteric, 1242 
 
 of Nuck, 1462, 1501 
 
 obturator, 525 
 
1556 
 
 INDEX 
 
 Canals, palatine, anterior, 143 
 posterior, 107, 116 
 accessory, 116, 135 
 palato-maxillary, 107 
 of Petit, 1130 
 pterygo-palatine, 135 
 pterygoid, 135 
 sacral, 64 
 
 «f Schlemm, 1108, 1111 
 semicircular, 1165 
 spermatic, 448, 1517 
 spinal, 69 
 of Stilling, 1129 
 for tensor tympani, 91, 1153 
 -vertebral, 49 
 A^idian, 96, 135 
 Volkmann's, 38 
 of Wirsung, 1351 
 Cancellous bone, 35 
 
 lamella; of, 39 
 'Canine eminence, 106 
 fossa, 106, 140 
 teeth, 1197 
 Canthi of eyelids, 1138 
 ■"Cap" of Broca, 874 
 Capillaries, liistology of, 584 
 Capitellum of humerus, 181 
 Capsula extrema, 894 
 Capsular ligaments. See Indi- 
 vidual joints. 
 Capsules, atrabiliary, 1430 
 Bowman's, 1418 
 of brain, external, 894 
 internal, 892 
 fibres of, 892 
 cartilage, 260 
 of Glisson, 770, 1256, 1337 
 of kidneys, fatty, 1411 
 
 true, 1415 
 of lens, 1130 
 parotid, 1216 
 of prostate gland, 1449 
 suprarenal, 1428 
 of Ttoon, 1103 
 Caput, cornu of cord, 839 
 
 gallinaginis, 1442 
 Cardia, 1270 
 
 Cardiac depression of liver, 1327 
 ganglion of Wrisberg, 1081 
 glands, 1278 
 lymphatics, 815 
 muscular fibres, 361 
 nerve, cervical, 1061 
 great, 1077 
 inferior, 1077 
 middle, 1077 
 minor, 1077 
 superior, 1076 
 thoracic, 1061 
 orifice of stomach, 1270 
 plexus of nerves, 1081 
 anterior, 1081 
 deep, 1081 
 great, 1081 
 superficial, 1081 
 portion of stomach, 1269 
 veins, 770 
 anterior, 771 
 great, 770 
 left, 771 
 middle, 771 
 posterior, 771 
 right, 771 
 Cardio-motor nerves, 1071 
 Carina uretii rails vagina;, 1484 
 Carotico-tympanic nerve, 1073 
 Carotid arteries, common, 595 
 
 branches of, occasional, 
 
 598 
 peculiarities of, 598 
 relations of, 596 
 
 Carotid arteries, common, sur- 
 face form of, 598 
 surgical anatomy of, 598 
 external, 600 
 branches of, 601 
 relations of, 600 
 surface fonn of, 601 
 surgical anatomy of, 601 
 internal, 619 
 
 branches of, 621 
 cavernous portion, 621 
 cerebral portion, 621 
 cervical portion 620 
 peculiarities of, 621 
 petrous portion, 620 
 relations of, 620 
 surgical anatomy of, 621 
 
 body, 1409 
 
 canal, 136 
 
 foramen, external, 89 
 internal, 88 
 
 ganglion, 1073 
 
 gland, 786, 1409 
 
 surgical anatomy of, 1409 
 
 groove, 93 
 
 nerves, 1057 
 
 plexus, 1073 
 
 sheath, 388 
 
 triangle, inferior, 616 
 superior, 394, 617 
 
 tubercle, 51 
 Carpal arch, anterior, 659 
 posterior, 659 
 
 artery, radial, anterior, 659 
 posterior, 659 
 ulnar, anterior, 663 
 posterior, 663 
 
 bones, development of, 205 
 Carpo-metacarpal articulations, 
 
 321 
 Carpus, 193 
 
 articulations of, 319 
 first row, 319 
 second row, 319 
 
 common characters of, 193 
 
 ligaments of, 319 
 
 surface form of, 204 
 
 surgical anatomy of, 204 
 Cartilage, 259 
 
 accessory quadrate, 1097 
 
 alar, 1097 
 
 of aperture of nose, 1097 
 
 articular, 259 
 
 arytenoid, 1364 
 
 capsule, 260 
 
 costal, 164 
 
 cricoid, 1363 
 
 cuneiform, 1365 
 
 of ear, 1146 
 
 elastic, 260 
 
 ensiform, 155 
 
 of epiglottis, 1365 
 
 epiphysial, 36, 44 
 
 fibro-, 260 
 
 hyaline, 259 
 
 intrathyroid, 1363 
 
 of Jacobson, 1097 
 
 of larynx, 1362 
 
 of nose, 1096 
 
 permanent, 259 
 
 of pinna, 1146 
 
 of Santorini, 1365 
 
 sesamoid, 1097 
 
 spaces, 260 
 
 temporarv, 259 
 
 thyroid, 1362 
 
 of trachea, 1378 
 
 triangular, of septum of nose, 
 1097 
 
 vomerine, 1097 
 
 of Wrisberg, 1365 
 
 Cartilage, xiphoid, 155 
 Cartilaginous isthmus of pinna, 
 1146 
 
 portion of Eustachian tube, 
 1154 
 of external auditory meatus 
 1148 
 Cartilago triticea, 1365 
 Caruncle, lachrymal, 1142 
 Caruncula lacrimalis, 1140 
 
 major of Santorini, 1288 
 
 minor of Santorini, 1288 
 Carunculse mystiforma-, 1482 
 Casserius, perforating nerve of, 
 
 985 
 Cauda equina, 1006 
 
 helicis, 1146 
 Caudal gut, 1242 
 Caudate lobe of liver, 1333 
 
 nucleus, 891 
 bulb of, 891 
 head of, 891 
 surcingle of, 891 
 tail of, 891 
 Cava, ascending, 764 
 
 inferior, 764 
 
 peculiarities of, 764 
 
 superior, 752 
 Cave of Meckel, 848 
 Cavernous body, artery of, 691 
 
 groove, 93 
 
 nerves of penis, 1086 
 
 plexus, 1073 
 
 portion of internal carotid 
 artery, 621 
 of urethra, 1443 
 
 sinus, 739 
 
 surgical anatomy of, 740 
 Cavity, buccal, 1193 
 
 of cervix uteri, 1491 
 
 cotyloid, 213 
 
 glenoid, 175 
 
 of larynx, 1368 
 
 of Meckel, 848 
 
 of mouth, 143 
 
 nasal, 142 
 
 oral, 1193 
 
 of pelvis, 1431 
 
 pericardiothoracic, 1236 
 
 of pleura, 1382 
 
 pleuroperitoneal, 1236 
 
 sigmoid, of radius, 191 
 of ulna, 186 
 
 of thorax, 556 
 
 of tunica vaginalis, 1470 
 
 tympanic, 1150 
 
 of uterus, 1491 
 Cavum concha?, 1145 
 
 Meckelii, 1027 
 
 oris proprium, 1193 
 Cells, amacrino, 1125 
 
 basket, 936 
 
 bipolar, 820 
 
 centro-acinar, of Langerhans, 
 1352 
 
 of Claudius, 1175 
 
 column, lateral, 846 
 
 of Deiters, 1175 
 
 enamel, 1206 
 
 ethmoidal, 82, 100 
 posterior, 145 
 
 of Golgi, 821 
 
 gustatory, 1091 
 
 of Hensen, 1175 
 
 hepatic, 1338 
 
 horizontal, of Cajal, 1125 
 
 of Martinotti, 921 
 
 mastoid, 86 
 
 multipolar, 820 
 
 nerve, 820 
 axone of, 821 
 
Cells, nerve, dendrites of, 821 
 development of, 823 
 epitheliuni, 830 
 olfactory, 1101 
 oxyntic, 1277 
 parietal, 1277 
 peptic, of glands, 1277 
 prickle, 1109 
 of Purkinje, 925 
 of Sertoli, 1472 
 sphenoidal, 94 
 unipolar, 820 
 Cementum of teeth, 1204 
 development of, 1207 
 Central canal of cord, 840 
 coil of cochlea, 1167 
 ganglionic vessels of brain, 630 
 lobe of cerebrum, 878 
 sulcus of Rolando, 867 
 tendon of diaphragm, 429 
 Centrifugal projection fibres of 
 
 cerebrum, 914 
 Centripetal projection fibres of 
 
 cerebrum, 914 
 Centro-acinar cells of Langer- 
 
 hans, 1352 
 Centrum ovale majus of Vieus- 
 sens, 886 
 minus, 885 
 vertebra, 48 
 Cephalic vein, 747 
 
 median, 746 
 Cephalo-auricular angle, 1144 
 Cerato-hyals of hyoid bone, 154 
 Cerebellar arteries, anterior in- 
 ferior, 640 
 posterior inferior, 639 
 superior, 640 
 columns, 843 
 notch, anterior, 926 
 
 posterior, 926 
 tract, antero-lateral, ascend- 
 ing, 842 
 descending, 843 
 direct, 843 
 dorso-lateral, 843 
 path of, 963 
 veins, deep, 736 
 superficial, 736 
 inferior, 736 
 superior, 736 
 Cerebellum, 926 
 amygdala of, 931 
 corpus dentatum of, 937 
 cortex of, 936 
 fibres of, 932 
 proper, 936 
 fissures of, 927 
 fra^nulum of, 928 
 ganglion of, 937 
 gray matter of, 936 
 hemispheres of, 885, 926 
 lamina of, 927 
 lobes of, 926, 928 
 nodules of, 930 
 peduncles of, 932, 943 
 
 superior, 910 
 structure of, internal, 931 
 surfaces of, inferior, lobes on, 
 930 
 under, 929 
 upper, 927 
 tonsil of, 931 
 uvula of, 931 
 vallecula of, 926 
 vermiform process of, 926 
 weight of, 938 
 white matter of, 931 
 Cerebral artery, anterior, 626 
 branches of, 626 
 middle, 627 
 
 INDEX 
 
 Cerebral arterv, middle, branches 
 of, 628"^ 
 posterior, 640 
 convolutions, 857 
 cranium, 71 
 
 hemorrhage, arteries of, 628 
 localization, 953 
 lymphatic vessels, 779 
 nerves, 1019 
 peduncles, 906 
 portion of internal carotid 
 
 artery, 621 
 veins, 734 
 cortical, 735 
 deep, 735 
 inferior, 735 
 median, 735 
 superficial, 735 
 superior, 735 
 ventricles, 888 
 Cerebro-cortico-pontal nerve 
 
 paths, 960 
 Cerebro-spinal axis, 832 
 
 nervous system, structure 
 of, 817 
 Cerebrum, commissure of, ante- 
 rior, 896 
 fibres of, 914 
 fissures of, longitudinal, 865, 
 
 882 
 gray matter of, 918 
 hemispheres of, 864 
 
 constituent parts of, 864 
 general considerations of, 
 
 864 
 surface of, 865 
 
 external, lobes on, 869 
 mesial, fissures of, 869 
 
 sulci of, 869 
 outer, fissures of, 865 
 
 sulci of, 865 
 tentorial, fissures of, 869 
 sulci of, 869 
 interior of, 885 
 parts composing, 885 
 peduncles of, 882, 884 
 structure of, 913 
 ventricles of, 888, 900, 901 
 white matter of, 913 
 Ceruminous glands, 1149 
 Cervical artery, ascending, 641 
 deep, 646 
 superficial, 642 
 transverse, 642 
 canal, 1491 
 cardiac nerves, 1061 
 fascia, deep, 387 
 superficial, 386 
 surgical anatomy of, 389 
 ganglion, inferior, 1077 
 
 branches, central commu- 
 nicating, 1077 
 peripheral, 1077 
 middle, 1076 
 
 branches of, central com- 
 municating, 1076 
 peripheral, 1077 
 superior, 1072 
 branches of, 1073 
 central, 1073 
 • communicating, 1073 
 peripheral, 1073 
 surgical anatomy of, 1077 
 glands, deep, 786 
 
 accessory chains to, 787 
 lower, 787 
 upper, 786 
 superficial, 784 
 anterior, 784 
 nerves, 968 
 
 divisions of, anterior, 971 
 
 1557 
 
 Cervical nerves, divisions of, 
 dorsal, 968 
 
 from facial nerve, 1049 
 posterior, 968 
 roots of, 968 
 superficial, 973 
 pleura, 1385 
 plexus, 972 
 
 branches, deep, 974 
 
 superficial, 972 
 posterior, 970 
 surgical anatomy of, 977 
 portion of internal carotid 
 artery, 620 
 of oesophagus, 1226 
 region, superficial, muscles of, 
 
 386 
 rib, 53 
 veins, anterior deep, 733 
 
 posterior deep, 733 
 vertebra, seventh, 53 
 vertebrae, 49 
 laminae of, 49 
 body of, 49 
 pedicles of, 49 
 processes of, 50 
 Cervicalis ascendens muscle, 419 
 Cervico-facial nerve, 1049 
 Cervix of bladder, 1435 
 comu of cord, 839 
 uteri, 1488 
 
 cavity of, 1491 
 Chassaignac's tubercle, 69 
 Check ligaments, 278 
 
 of eye, 1105 
 Cheeks, 1195 
 
 mucous membrane of, 1195 
 surgical anatomy of, 1224 
 Chemical composition of bone, 
 41 
 of nervous tissue, 824 
 Chest, 155 
 
 articulations of, 159 
 attachment of muscles to, 159 
 boundaries of, 155 
 development of, 158 
 structure of, 158 
 surface form of, 156 
 surgical anatomy of, 165 
 Chiasma or optic commissure, 
 
 1021 
 Chink of glottis, 1369 
 Choanse, 146 
 
 Chondro-glossus muscle, 397 
 -sternal ligament, anterior, 
 288 
 interarticular, 288 
 posterior, 288 
 -xiphoid ligament, anterior, 
 ^ 288 
 
 "^posterior, 288 
 Chorda tympani nerve, 1047 
 Chordae tendineae of left ventri- 
 cle, 573 
 of right ventricle, 570 
 Willisi, 737 
 Choroid arteries, anterior, 628 
 posterior, 640 
 coat of eye, 1111 
 
 structure of, 1112 
 fissure, 890, 900 
 nerves of, 1120 
 plexus, 899 
 
 of body of ventricle, 900 
 of fourth ventricle, 901 
 of lateral ventricle, 900 
 of third ventricle, 901 
 vein, 735 
 Chromatophile granules, 820 
 Chyli receptaculum, 624 
 Cilia, or eyelashes, 1137 
 
1558 
 
 INDEX 
 
 Ciliary arteries, anterior, 623 
 long, 625 
 short, 625 
 body, 1115 
 ganglion, 1031 
 
 long root of, 1030 
 glands, 1190 
 ligament, 1116 
 margin, 1117 
 muscles, 1115 
 nerves, long, 1030 
 
 short, lOaO 
 processes of eye, 1115 
 structure of, 1115 
 Cingulum, 879, 918 
 Circle of Willis, 629, 640 
 Circular sinus, 742 
 Circulus of iris, major, 625 
 minor, 625 
 tonsillaris, 1036 
 Circumanal glands, 1190 
 Circumduction, 274 
 Circumflex arteries of arm, 651 
 of thigh, 705 
 iliac artery, deep, 697 
 superficial, 704 
 vein, deep, 759 
 nerve, 984 
 
 lower branch, 985 
 upper branch, 985 
 vein, deep, 758 
 superficial, 756 
 Circumflexus muscle, 404 
 
 relations of, 404 
 Circumpatellar anastomosis, 711 
 Circumvallate papillae of tongue, 
 
 1089 
 Cistern of Pecquet, 775 
 Cisterna basalis, 852 
 magna, 853 
 pontis, 853 
 Clado, appendiculo-ovarian lig- 
 ament of, 1304 
 Clarke, vesicular column of, 
 
 843 
 Claudius, cells of, 1175 
 Claustrum, 894 
 Clava of fasciculus gracilis, 941 
 Clavicle, 167 
 
 articulations of, 170 
 attachment of muscles to, 
 
 170 
 development of, 170 
 peculiarities of, in sexes and 
 
 individuals, 170 
 structure of, 170 
 surface form of, 170 
 surgical anatomy of, 170 
 Clavicular facet, 157 
 Clavi-pectoral fascia, 467 
 Clinoid process, anterior, 131 
 middle, 93, 132 
 posterior, 93, 132 
 Clitoris, 1479 
 arteries of, 1480 
 crus of, 1480 
 fraenum of, 1479 
 muscles of, 461 
 nerves of, 1480 
 dorsal, 1013 
 prepuce of, 1479 
 Clivus, 93 
 
 monticuli of cerebellum, 928 
 Cloquet, canal of, 1129 
 gland of, 795, 798 
 ligament of, 1466 
 septum crurale of, 509 
 Coccygeal artery, 693 
 body, 1410 
 gland, 1410 
 ligament, 833 
 
 Coccygeal nerve, divisions of, an- 
 terior, 1009 
 posterior, 1008 
 Coccygeus muscle, 455 
 Coccyx, 65 
 
 apex of, 66 
 
 articulation of, 67 
 
 attachment of muscles to, 67 
 
 base of, 66 
 
 borders of, 66 
 
 cornua of, 66 
 
 development of, 66 
 
 surfaces of, 66 
 Cochlea, 1165 
 
 canal of, bony, 1167 
 membranous, 1172 
 spiral, 1167 
 
 lamina spiralis of, 1167 
 
 ligament of, spiral, 1172 
 
 nerve, 1053 
 Cochlear artery, 1126 
 
 path, 1053 
 
 root of eighth nerve, 1051 
 
 window, 1152 
 Coeliac artery, 671 
 
 axis, 671 
 
 glands, 800 
 
 plexus, 1061, 1084 
 Colic area of kidneys, 1414 
 
 artery, left, 678 
 middle, 676 
 right, 675 
 
 glands, 808 
 
 impression of liver, 1329 
 
 plexus, 1085 
 Collar bone, 167 
 Collateral fissure, 871 
 
 intercostal artery, 668 
 Colles' fascia, 456, 1515 
 
 ligament, 437 
 CoUiculus nervi optici, 1364 
 Colloid material, 1404 
 Colon, 1309 
 
 ascending, 1309 
 
 descending, 1309 
 
 pelvic, 1311 
 
 sigmoid, 1311 
 
 surgical anatomy of, 1326 
 
 transverse, 1309 
 Colostrum corpuscles, 1507 
 Columella cochleae, 1166 
 Column of Marchi and Lowen- 
 
 thal, 843 
 Columna nasi, 1096 
 ColumniE cameae of left ventricle, 
 573 
 of right ventricle, 570 
 Columns of Bertin, 1416 
 
 cerebellar, 843 
 
 of Morgagni, 1319 
 
 of spinal cord, 838 
 
 of vagina, 1484 
 Comes nervi ischiadic! artery, 693 
 mediana artery, 663 
 phrenici artery, 644 
 Comma tract, descending, 844 
 Commissura hippocampi, 896 
 Commissural fibres of cerebrum, 
 
 916 
 Commissure of brain, anterior, 896 
 gray, 903 
 middle, 903 
 posterior, 903 
 soft, 903 
 
 Gudden's, 912, 1021 
 
 of habenula, 904 
 
 of Mevnert, 908 
 
 optic," 131, 882, 1021 
 
 of spinal cord, 839 
 anterior, 839 
 gray, 839 
 
 Commissure of spinal cord, gray, 
 anterior, 839 
 posterior, 839 
 posterior, 839 
 white, 839 
 Common carotid artery, 595 
 facial vein, 726 
 femoral artery, 699 
 iliac arteries, 681 
 glands, 799 
 vein, 764 
 temporal vein, 727 
 ulnar vein, 745 
 Communicantes hypoglossi nerve, 
 
 974 
 Communicating arteries, ante- 
 rior cerebral, 627 
 posterior cerebral, 628 
 of ulnar, anterior, 662 
 Compact bone, 35 
 
 longitudinal section of, 39 
 transverse section of, 38 
 Complexus muscle, 420 
 
 relations of, 420 
 Compressor narium minor mus- 
 cle, 376 
 sacculi laryngis, 1373 
 urethrse muscle in female, 462 
 in male, 460 
 Conarium, 905 
 
 Concentric lines of Schreger, 1203 
 Concha auricula?, 1145 
 Conducting tracts of cord, 841 
 Conductor sonorus, 945 
 Condyles of bones. See Bones. 
 Condylic portion of occipital 
 
 bone, 71 
 Condyloid articulation, 265 
 foramen, anterior, 73, 133, 136 
 
 posterior, 73, 133, 136 
 fossa, anterior, 136 
 
 posterior, 136 
 glands of Leaf, 795 
 process, 125 
 Cone-bipolars, 1125 
 
 -granules of retina, 1126 
 Cones of retina, 1126 
 Congenital hernia, 1523 
 Conglobate glands, 774 
 Conical papillte, 1090 
 Conjugate diameter of pelvis, 217 
 Conjunctiva, 1140 
 
 bulbar portion of, 1140 
 fornix of, 1140 
 glands of, 1140 
 nerves of, 1140 
 palpebral portion of, 1140 
 surgical anatomy of, 1144 
 Connective tissue, subserous, 
 
 1246 
 Conoid ligament, 300 
 
 tubercle, 168 
 Constriction lobe of liver, 1336 
 Constrictor isthmi faucium mus- 
 cle, 398, 405 
 muscles, inferior, 400 
 middle, 401 
 superior, 401 
 urethrse muscle in female, 462 
 in male, 460 
 Conus arteriosus, 569 
 
 terminalis, 837 
 Convolutions, angular, 876 
 of brain, 865 
 of Broca, 874 
 callosal, 879 
 dentate, 879 
 frontal, 872 
 hippocampal, 879 
 of limbic lobe, 879 
 marginal, 873 
 
INDEX 
 
 1559 
 
 Convolutions, occipital, 877 
 occipito-temporal, 878 
 orbital, internal, 873 
 parietal, 876 
 
 ascending, 876 
 post-parietal, 876 
 precuneus, 877 
 quadrati, 877 
 subcalcarine, 877 
 subcollateral, 878 
 supramarginal, 876 
 temporal, 877 
 uncinate, 879 
 Cooper, ligament of, 437, 448 
 Coraco-acromial ligament, 301 
 -brachialis muscle, 475 
 bursa of, 475 
 relations of, 475 
 -clavicular ligaraient, 300 
 -humeral ligament, 304 
 Coracoid ligament, 302 
 
 process, 175 
 Cord, gangliated, 1071 
 
 cervical portion of, 1071 
 lumbar portion of, 1079 
 pelvic portion of, 1080 
 sacral portion of, 1080 
 thoracic portion of, 1078 
 spermatic, 1466 
 spinal. Sec Spinal cord, 
 vocal, 1370 
 Cordiform tendon of diaphragm, 
 
 429 
 Corium, 1180 
 
 corpus papillare of, 1181 
 of tongue, 1089 
 Cornea, 1108 
 arteries of, 1111 
 nerves of, 1111 
 structure of, 1109 
 Corneal endothelium, 1111 
 
 spaces, 1110 
 Comical tubercle of Sairtibrini, 
 
 1368 
 Cornicula laryngis, 1365 
 Cornu ammonis, 897 
 commissural tract, 844 
 of lateral ventricle, 889 
 Cornua of coccyx, 66 
 of hyoid bone, 154 
 sacral, 62 
 Corona ciliaris, 1115 
 
 glandis, 1454 
 Coronal suture, 78, 127 
 Coronarv artery, 671 
 of heart, 590 
 descending, 590 
 infundibular, 590 
 marginal, 590 
 peculiarities of, 591 
 transverse, 590 
 of lip, inferior, 607 
 
 superior, 607 
 of stomach, 671 
 ligament of knee, 340 
 
 of liver, 1334 
 plexus, 1085 
 anterior, 1081 
 left, 1081 
 posterior, 1081 
 right, 1081 
 sinus, 567, 771 
 valve, 567 
 vein, 768 
 left, 770 
 small, 771 
 Coronoid fossa, 181 
 process of jaw, 125 
 of ulna, 186 
 Corpora albicantia, 883 
 bigemina, 911 
 
 Corpora cavernosa, 1455 
 arteries of, 1458 
 bulb of, 1456 
 structure of, 1457 
 trabeculae of, 1457 
 veins of, 1458 
 geniculata, 911 
 mammillaria, 883 
 
 peduncles of, 883 
 quadrigemina, 907, 911 
 brachia of, 119 
 structure of, 911 
 Corpus albicans, 895 
 Arantii, 571, 573 
 callosum, 882, S86 
 beak of, 886 
 body of. 886 
 pad of, 886 
 
 peduncles of, 882, 886 
 rostrum of, 886 
 spleuium of, 886 
 cavernosum, artery of, 691 
 dentatum of cerebellum, 937 
 
 of olive, 951 
 fimbriatum, 890, 896, 898 
 of olivary body, 951 
 papillare of corium, 1181 
 spongiosum, 1458 
 
 structure of, 1458 
 striatum, 890 
 Corpuscles of Ilerbst, 829 
 Malpighian, of kidney, 1417 
 
 of spleen, 1358 
 Pacinian, 828 
 of Purkinje, 936 
 tactile, 827 
 of Vater, 828 
 Corrugator cutis ani muscle, 
 449 
 supercilii muscle, 371 
 relations of, 371 
 Cortex of cerebellum, 936 
 of cerebrum, cells of, 919 
 gray matter of, 918 
 nerve-fibres of, 920 
 Corti, ganglion of, 1053 
 membrane of, 1175 
 organ of, 1173 
 rods of, 1174 
 tunnel of, 1174 
 Cortical arteries of brain, 631 
 cerebral veins, 735 
 portion of kidney, 1416 
 
 of suprarenal capsule, 1430 
 of thymus gland, 1408 
 substance of teeth, 1204 
 Costal cartilages, 164 
 
 attachment of muscles to, 
 
 164 
 borders of, 164 
 extremities of, 164 
 surfaces of, 164 
 facet, 169 
 pleura, 1385 
 process, 50 
 surface of lungs, 1391 
 Costo-axillary vein, 748 
 -central articulations, 283 
 -chondral articulations, 290 
 -clavicular ligament, 298 
 -coracoid ligament, 467 
 
 membrane, 467 
 -mediastinal sinus, 1386 
 -sternal articulations, 287 
 -transverse articulations, 285 
 foramen, 50 
 ligament, long, 285 
 middle, 286 
 posterior, 286 
 -vertebral articulations, 283 
 ligament, anterior, 284 
 
 Costo-xiphoid ligament, ante- 
 rior, 288 
 posterior, 288 
 Cotunnis, nerve of, 1036 
 Cotyloid cavity, 213 
 ligament, 329 
 notch, 213 
 Cowper's glands, 1453 
 
 structure of, 1453 
 Cranial bones, 71 
 fossa, 143 
 nerves, 1019 
 
 path of, 962 
 reflex, 963 
 
 region, dissection of, 366 
 fascia of, superficial, 366 
 lymphatics of, 779 
 vessels of, 782 
 sutures, 127 
 Cranio-cerebral topography, 954 
 Cranium, 71 
 cerebral, 71 
 development of, 102 
 differences in size and form of, 
 
 146 
 fasciae of, 365 
 lymphatics of, 779 
 membranous, 102 
 muscles of, 365 
 Cremaster muscle, 439, 1516 
 Cremasteric arterv, 696 
 
 fascia, 1464, 1516 
 Crescentric lobe, anterior, 928 
 
 posterior, 928 
 Crescents of Gianuzzi, 1218 
 Crest, buccinator, 124 
 ethmoidal, 94 
 falciform, 89 ■ 
 frontal, 80, 130 
 incisor, 111 
 infratemporal, 95 
 lachrymal, 113 
 
 bone, 141 
 nasal, 111, 116 
 obturator, 213 
 occipital, external, 72, 136 
 
 internal, 74, 133 
 sphenoidal, 94 
 supramastoid, 84, 137 
 temporal, 76, 80, 84 
 of tibia, 234 
 
 turbinated, inferior, 107, 117 
 superior, 117 
 Cribriform fascia, 512, 1527 
 lamina, 1108 
 plate, 130 
 
 of ethmoid, 99 
 Crico-arytenoid articulation, 
 1367 
 ligaments, 1367 
 muscle, lateral, 1373 
 posterior, 1372 
 -thyroid artery, 602 
 articulation, 1367 
 membrane, 1367 
 muscle, 1372 
 -tracheal ligament, 1368 
 Cricoid cartilage, 1 363 
 borders of, 1364 
 surfaces of, 1364 
 Crista falciformis, 89 
 galli, 99, 130 
 terminalis, 565 
 vestibuli, 1164 
 Crossed descending tract, 842 
 
 pyramidal tract, 842 
 Crucial ligaments of knee, 337 
 Cruciform ligament, 275 
 Crura ad cerebrum, 932 
 ad medullam, 934 
 ad posterior, 934 
 
1560 
 
 INDEX 
 
 Crura cerebri, 884 
 of diaphragm, 427 
 of penis, 1454 
 Crural arch, deep, 448, 1531 
 superficial, 436, 1529 
 canal, 509, 1531 
 nerve, anterior, 1004 
 ring, 437, 509, 1532 
 septum, 1532 
 sheath, 509 
 Crureus muscle, 517 
 nerve to, 1006 
 relations of, 517 
 Crus cerebri, tegmentum of, 
 885 
 of helix, 1145 
 Crusta of crus cerebri, 907 
 
 petrosa of teeth, 1204 
 Cruveilhier, atlanto-odontoid 
 joint of, 274 
 glenoid ligament of, 359 
 Crypts of Lieberkiihn, 1295 
 
 of Morgagni, 1319 
 Crystalline lens, 1130 
 capsule of, 1130 
 substance of, 1130 
 structure of, 1131 
 Cuboid bone, 245 
 
 articulations of, 246 
 attachment of muscles to, 
 
 246 
 surfaces of, 245, 246 
 tuberosity of, 245 
 Culmen monticuli cerebelli, 
 
 928 
 Cuneate funiculus, 941 
 lobe, 877 
 
 nucleus, accessory, 948 
 tubercle, 941 
 Cuneiform bone, foot, 247 
 external, 248 
 
 articulations of, 249 
 attachment of muscles 
 
 to, 249 
 surfaces of, 248 
 internal, 247 
 
 articulations of, 247 
 attachment of muscles 
 
 to, 247 
 surfaces of, 247 
 middle, 248 
 
 articulations of, 248 
 attachment cif muscles 
 
 to, 248 
 surfaces of, 248 
 of hand, 197 
 
 articulations of, 197 
 surfaces of, 197 
 cartilages, 1365 
 tubercle of Wrisberg, 1368 
 Cuneus, 875 
 
 Cupola of cochlea, 1167, 1172 
 Cushion of epiglottis, 1365 
 Cusps of bicuspid valve, 572 
 
 of tricuspid valve, 570 
 Cutaneous nerve, external, 985, 
 1003 
 internal, 986, 1004 
 middle, 1004 
 palmar, 987 
 perforating, 1011 
 Cuticle of skin, 1181 
 Cutis vera, 1180 
 Cuvier, duct of, 561 
 Cymba conchffi, 1145 
 Cystic artery, 674 
 duct, 1344 
 
 plexus of nerves, 1085 
 vein, 769 
 Czermak, interglobular spaces of, 
 1202 
 
 Dacryon, 141 
 Dartos of scrotum, 1463 
 Uarwin, tubercle of, 1.145 
 Deciduous teeth, 1196 
 Decussatio nervorum trochlea- 
 
 rium, 1025 
 Decussation of fillet, 949 
 
 of pyramids, 947 
 Deep annectant gyrus, 867 
 anterior thoracic nerve, 984 
 branches of cervical plexus, 
 
 974, 976 
 cardiac plexus, 1081 
 cerebral veins, 735 
 cervical artery, 646 
 fascia, 387 
 glands, 786 
 circumflex iliac artery, 697 
 
 vein, 759 
 crural arch, 448, 1531 
 dorsal vein of penis, 762 
 epigastric artery, 696 
 
 vein, 759 
 external pudic artery, 704 
 fascia, 364 
 
 of arm, 470, 474 
 
 of back, 411 
 
 of femoral region, anterior, 
 
 513 
 of forearm, 478 
 of leg, 532 
 of shoulder, 470 
 of thoracic region, anterior, 
 463 
 femoral artery, 704 
 
 lymphatic glands, 795 
 inguinal lymphatic glands, 795 
 lymphatic glands of upper ex- 
 tremity, 790 
 vessels of abdominal wall, 
 801 
 of lower extremity, 797 
 of upper extremity, 792 
 muscles of abdomen, 449 
 palmar arch, 658 
 fascia, 493 
 veins, 747 
 parotid lymphatic glands, 782 
 patellar bursa, 518 
 pectoral fascia, 464 
 perineal fascia, 1538 
 petrosal nerve, 1073 
 radial veins, 747 
 superficial external pudic ar- 
 tery, 704 
 temporal artery, 614 
 nerves, 1037 
 veins, 727 
 transverse fascia of leg, 537 
 ulnar veins, 747 
 veins of foot, 758 
 
 of lower extremity, 758 
 of upper extremity, 747 
 Deiters, cells of, 1175 
 nucleus of, 926, 1050 
 process, 817 
 Deltoid eminence, 179 
 impression, 179 
 muscle, 470 
 
 relations of, 471 
 tubercle, 168 
 Demilunes of Heidenhain, 1218 
 Demours, membrane of, 1110 
 Dendraxones, 821 
 Dendrites of nerve-cells, 821 
 Dental artery, inferior, 614 
 posterior, 615 
 band, 1205 
 canal, 1202 
 
 Dental canal, anterior, 107 
 inferior, 124 
 posterior, 106 
 fibres, 1202 
 follicle, 1206 
 
 lamina, 1205 » 
 
 nerves, anterior superior, 1033 
 inferior, 1039 
 middle superior, 1033 
 posterior superior, 1032 
 periosteum, 1204 
 plexus, superior, 1033 
 pulp, 1200 
 sac, 1206 
 tubuh, 1202 
 Dentate convolution, 879 
 gray matter of, 921 
 fascia, 879, 898 
 fissure, 871, 879 
 ligament, 835 
 Dentinal sheath of Neumann, 
 1203 
 tubuli, 1202 
 Dentine, 1202 
 
 development of, 1207 
 papilla, 1205 
 Depression, pterygoid, 125 
 
 trigeminal, 88 
 Depressions of bone, 34 
 Depressor ala; nasi muscle, 37S 
 anguli oris muscle, 378 
 relations of, 378 
 labii inferioris muscle, 378 
 relations of, 378 
 Dermic coat of hair-follicle, 1 188 
 Dermis, 1180 
 
 Descemet, membrane of, 1110 
 Descendens hypoglossi nerve, 
 
 1066 
 Descending aorta, 665 
 
 branch of superior cervical 
 
 ganglion, 1074 
 colon, 1309 
 comma tract, 844 
 cornu of lateral ventricle, 890 
 mesocolon, 1258 
 nerve tract, 959 
 oblique muscle of abdomen, 
 
 433 
 palatine artery, 615 
 ramus of ischium, 211 
 
 of pubis, 213 
 root of fifth nerve, 1026 
 Descent of ovary, 1501 
 of testicles, 1461 
 
 surgical anatomy of, 1462 
 Detrusor urinse muscle, 1437 
 Development of alimentary ca- 
 nal, 1236 
 of alveoli of teeth, 1207 
 of atlas, 59 
 of axis, 59 
 of brain, 857 
 of carpal bones, 205 
 of cementum, 1207 
 of clavicle, 170 
 of coccyx, 66 
 of cranium, 102 
 of dentine, 1207 
 of enamel, 1206 
 of ethmoid bone, 101 
 of femur, 228 
 of fibula. 238 
 of foot, 253 
 of frontal bone, 82 
 of humerus, 182 
 of hyoid bone, 154 
 of inferior turbinated bone, 
 
 120 
 of lachrymal bone, 113 
 of liver, 1243 
 
INDEX 
 
 1561 
 
 Development of maxillary bone, 
 inferior, 125 
 
 of mesentery, 1237 
 
 of metacarpal bones, 205 
 
 of metatarsal bones, 253 
 
 of organs, clironological table 
 of, 1547 
 
 of nasal bones, 105 
 
 of nerve-cells, 823 
 -fibres, 823 
 
 of occipital bone, 75 
 
 of omentum, 1238 
 
 of OS innominatum, 214 
 
 of palate bone, 119 
 
 of pancreas, 1244 
 
 of parietal bone, 78 
 
 of patella, 231 
 
 of peritoneal cavitv, 1242 
 
 of peritoneum, 1234, 1242 
 
 of permanent teeth, 1208 
 
 of phalanges of foot, 254 
 of hand, 206 
 
 of radius, 192 
 
 of ribs, 163 
 
 of sacrum, 64 
 
 of scapula, 175 
 
 of sphenoid bone, 97 
 
 of spleen, 1245 
 
 of sternum, 158 
 
 of superior maxillary bones, 
 112 
 
 of tarsal bones, 253 
 
 of teeth, 1204 
 
 of temporal bone, 91 
 
 of tibia, 236 
 
 of tongue, 1242 
 
 of tonsils, 1243 
 
 of ulna, 189 
 
 of vertebrse, 58 
 
 of viscera, 1234 
 
 of vomer, 122 
 
 Wormian, 103 
 Diagonal sulcus, 868 
 Diameter of pelvis, 217 
 Diaphragm, 427 
 
 actions of, 430 
 
 crura of, 427 
 
 lymphatics of, 810 
 
 nerves of, 430 
 
 openings of, 429 
 aortic, 429 
 oesophageal, 430 
 for vena cava, 430 
 
 of pelvis, 1231 
 
 pillars of, 427 
 
 serous membranes of, 430 
 
 tendons of, central, 429 
 Diaphragma selliE, 851, 882 
 Diaphragmatic ganglion, 1084 
 
 hernia, 427 
 
 lymphatic, 810 
 
 pleura, 1386 
 
 portion of a?sophagus, 1226 
 Diaphysis, 34 
 Diarthrosis, 265 
 Diaxonic cells, 821 
 Digastric branch of facial nerve, 
 1048 
 
 fossa, 86, 123, 136 
 
 lobe of cerebellum, 931 
 
 muscle, 393 
 
 relations of, 394 
 
 nerve, from facial, 1048 
 Digestion, organs of, 1193 
 Digital arteries, dorsal, 659 
 of ulna, 664 
 
 fossa, 223 
 
 nerves of foot, 1015 
 hand, 987 
 Dilator naris anterior muscle, 376 
 posterior muscle, 376 
 
 Dilator tubse muscle of Rudinger, 
 
 1155 
 Diploe, 34 
 
 veins of, 733 
 Diploic canals, 733 
 veins, frontal, 734 
 occipital, 734 
 parietal external, 734 
 temporal, anterior, 734 
 posterior, 734 
 Direct cerebellar tract, 843 
 inguinal hernia, 1523 
 pyramidal tract, 842 
 Disk, interpubic, 296 
 intervertebral, 270 
 optic, 1121 
 Dissection of axilla, 463 
 of brain, 847 
 
 of internal oblique muscle, 437 
 of muscles of abdomen, 432 
 of arm, 470 
 
 of auricular region, 369 
 of back, 410, 414, 415, 417 
 of cranial region, 366 
 of femoral region, anterior, 
 512 
 internal, 519 
 posterior, 529 
 of fibular region, 539 
 of forearm, 478, 482 
 of gluteal region, 522 
 of hand, 491 
 of iliac region, 508 
 of infra-hyoid region, 391 
 of intermaxillary region, 378 
 of lingual region, 396 
 of mandibular region, 377 
 of orbital region, 372 
 of palatal region, 403 
 of palpebral region, 370 
 of pectoral region, 463 
 of pharyngeal region, 400 
 of plantar region, 544, 545, 
 
 546 
 of pterygo-mandibular re- 
 gion, 383 
 of radial region, 484 
 of scapular region, anterior, 
 471 
 posterior, 472 
 of shoulder, 470 
 of superficial cervical region 
 
 386 
 of supra-hyoid region, 393 
 of tibio-fibular region, ante- 
 rior, 532 
 posterior, 534, 537 
 of pancreas, 1348 
 of perinseum, 1535 
 of popliteal space, 707 
 of rectus abdominis muscle, 442 
 of sole of foot, 542 
 of spinal cord, 832 
 of temporal muscle, 382 
 of trans versalis muscle, 441 
 Diverticulum, Meckel's, 1290 
 Dorsal artery of penis, 692 
 auditory nuclei, 950 
 digital arteries, 659 
 
 veins, 745 
 divisions of cervical nerves, 
 
 968 
 interosseous arteries, 659, 715 
 nerves, 993 
 
 of clitoris, 1013 
 divisions of, anterior, 993 
 
 posterior, 993 
 of penis, 1013 
 roots of, 993 
 region, muscles of, 543 
 root of eighth nerve, 1051 
 
 Dorsal root of spinal nerves, 96S 
 ulnar vein, 745 
 veins of penis, deep, 762 
 
 superficial, 762 
 vertebrse, 53 
 bodies of, 53 
 lamina of, 54 
 peculiar, 55 
 pedicles of, 54 
 processes of, 54 
 Dorsalis hallucis artery, 716 
 indicis artery, 659 
 linguae artery, 603 
 nasi artery, 625 
 pedis artery, 714 
 
 branches of, 715 
 peculiarities of, 715 
 relations of, 714 
 surface marking of, 715 
 surgical anatomy of, 715 
 pollicis arteries, 659 
 scapulae artery, 651 
 Dorsi-lumbar nerve, 996 
 
 -spinal veins, 753 
 Dorso-lateral cerebellar tract, 84$ 
 -median fissure, 838 
 -ventral fibres of cord, 841 
 Dorsum ephippii, 93, 152 
 of penis, 1455 
 of scapula, 172 
 sella;, 93 
 Douglas, fold of, semilunar, 439,. 
 444 
 pouch, 1490 
 Drumhead, 1155 
 Duct or ducts, aberrant, of epi- 
 didymis, 1472 
 alveolar, 1378 
 of Bartholin, 1217 
 biliary, 1341 
 
 of Cuvier, 561 ^ 
 
 cystic, 1344 
 ejaculatory, 1476 
 galactophorus, 1507 
 Gartner's, 1499 
 hepatic, 1342 
 interlobular, 1341 
 of kidney, 1420 
 lactiferous, 1507 
 of liver, 1341 
 lymphatic, right, 778 
 mammillary, 1507 
 nasal, 1142 
 pancreatic, 1351 
 parotid, 1215 
 of Rivinus, 1217 
 seminal, 1472 
 Stenson's, 1215 
 of submaxillary gland, 121ft 
 thoracic, 775 
 thyroglossal, 1090, 1401 
 Wharton's, 1216 
 Ductless glands, 1401 
 Ductus arteriosus, 579 
 
 communis choledoclms, 1344 
 endolymphaticus, 89, 1165 
 venosus, fissure of, 1331 
 fossa of, 1331 
 Duodenal area of kidney, 1414 
 folds, 1260 
 inferior, 1261 
 superior, 1261 
 fossse, 1260 
 inferior, 1260 
 superior, 1261 
 glands, 1295 
 impression of liver, 1329 
 Duodeno-jejunal fossa, 1261 
 -mesocolic ligaments, 1261 
 -renal ligament, 1255 
 Duodenum, 1282 
 
1562 
 
 INDEX 
 
 13uodenum, arteries of, 1288 
 ascending portion of, 1286 
 descending portion of, 1285 
 first portion of, 1284 
 flexure of, superior, 1285 
 fourth portion of, 1286 
 horizontal portion of, 1285 
 interior of, 1288 
 lymphatics of, 1288 
 muscular coat of, 1288 
 nerves of, 1288 
 peritoneal coat of, 1288 
 pre-aortic portion of, 1285 
 «econd portion of, 1285 
 structure of, 1288 
 submucous coat of, 1288 
 superior portion of, 1284 
 surgical anatomy of, 1325 
 suspensory muscle of, 1286 
 tliird portion of, 1285 
 transverse portion of, 1285 
 veins of, 1288 
 Dura mater of brain, 847 
 arteries of, 848 
 lymphatics of, 849 
 nerves of, 849 
 proctesses of, 849 
 structure of, 848 
 veins of, 849 
 sinuses of, 736 
 of spinal cord, 832 
 structure of, 834 
 Duverney, gland of, 1482 
 
 E 
 
 Ear, 1144 
 
 auditory meatus, external, 
 
 1148 
 auricle, 1144 
 bones of, 1158 
 cartilages of, 1146 
 cochlea, 1165 
 -drum membrane, secondary, 
 
 1152 
 -external, 1144 
 auricle of, 1144 
 lobule of, 1145 
 internal, 1163 
 labyrinth, 1163 
 
 membranous, 1169 
 osseous, 1164 
 middle, 1150 
 muscles of auricle, 1 147 
 
 of tympanum, 1157 
 ossicula of, 1158 
 pinna of, 1144 
 semicircular canals of, 1165 
 surgical anatomy of, 1176 
 trumpet, 1153 
 tympanum, 1150 
 ^. Ebner, glands of, 1091 
 Efferent nerve tract, 959 
 Egg tubes, 1502 
 Eighth nerve, 1050 
 origin of, 1050 
 roots of, 1050 
 svirgical anatomy of, 1054 
 Ejaculator seminis muscle, 457 
 
 urinse muscle, 457 
 Ejaculatory ducts, 1476 
 Elastic cartilage, 260 
 tissue, yellow, 261 
 Elbow, bend of, surgical anatomv 
 of, 653 
 bone, 184 
 bursa of, 311 
 
 -joint, articulations of, 308 
 surface form of, 312 
 surgical anatomy of, 312 
 
 Elbow, ligament of, anterior, 
 309 
 posterior, 309 
 Eleventh nerve, 1063 
 
 surgical anatomy of, 1063 
 Ellipsoid of Krause, 1127 
 Elliptical recess, 1164 
 Eminence, articular, of temporal 
 bone, 84 
 
 of bone, 34 
 
 canine, 106 
 
 deltoid, 179 
 
 frontal, 79 
 
 ilio-pectineal, 210, 213 
 
 of Jacobson, 1100 
 
 nasal, 79 
 
 olivary, 93 
 
 parietal, 76 
 Eminentia articularis, 84, 135 
 
 collate rails, 890 
 
 conchae, 1146 
 
 fossa; triangularis, 1046 
 
 teres, 945 
 Emissary veins, 743 
 
 surgical anatomy of, 743 
 Emulgent vein, 766 
 Enamel cells, 1206 
 
 cuticle, 1204 
 
 fibres, 1203 
 
 jelly, 1206 
 
 -organ of tooth, 1205 
 
 prisms, 1203 
 
 of teeth, 1203 
 
 development of, 1206 
 Enarthrosis, 266 
 Encephalon, 857 
 Encysted hernia, 1523 
 End-bulb of Krause, 827 
 Endocardium, 574 
 Endo-gnathion, 111 
 Endolymph, 1169 
 Endoneurium, 825 
 Endosteum, 36 
 Endothelium, corneal, 1111 
 Endothoracic fascia, 1385 
 Ensiform appendix, 158 
 surfaces of, 158 
 
 cartilage, 155 
 Eosinophiles, 56 
 Epactal bones, 103 
 Eparterial branch of bronchus, 
 
 1377 
 Epencephalon, 857 
 E])endyma, 888 
 Epicondyles, 181 
 Epicondylic ridge, 179 
 Epicteric bone, 103 
 Epidermic coat of hair-follicle, 
 
 1188 
 Epididymis, 1469 
 
 aberrant ducts of, 1472 
 
 structure of, 1471 
 Epidural space, 833, 847 
 Epigastric artery, deep, 696, 
 1518 
 peculiarities of, 696 
 surgical anatomy of, 697 
 internal, 696 
 superficial, 704 
 superior, 645 
 
 glands, superior, 802 
 
 plexus, 1083 
 
 vein, deep, 759 
 Epiglottis, 1365 
 
 cartilage of, 1365 
 
 cushion of, 1365 
 
 surfaces of, 1365 
 Epimysium, 361 
 Epineurium, 825 
 Epiotic portion of temporal bone, 
 
 91 
 
 Epiphysial cartilage, 36 
 Epiphysis of bone, 34 
 
 cerebri, 905 
 Epithelium. See Various organs, 
 germinal, of Waldeyer, 1501 
 lens, 1130 
 transitional, 1428 
 Epitrochlea, 181 
 Epitympanic recess, 87, 1150 
 
 space, 87 
 Epo-ophoron, 1499 
 Erectile tissue of penis, 1457 
 
 of vagina, 1485 
 Erector clitoridis muscle, 461 
 penis muscle, 458 
 spinas muscle, 417 
 relations of, 420 
 Ethmo-frontal suture, 130 
 
 -sphenoidal, 130 
 Ethmoid bone, 98 
 
 articulations of, 102 
 cribriform plate of, 99 
 development of, 101 
 horizontal lamina of, 99 
 infundibulum of, 101 
 lateral mass of, 100 
 OS planum of, 100 
 perpendicular plate of, 
 
 100 
 unciform process of, 100 
 Ethmoidal arteries, 623 
 canals, 82, 100 
 cells, 82, 100 
 
 posterior, 145 
 crest, 94 
 foramina, 82 
 
 anterior, 130, 141 
 posterior, 130 
 notch, 82 
 process of inferior turbinated, 
 
 120 
 sinuses, 101 
 spine, 93, 130 
 Eustachian cushion, 1221 
 tube, 1153 
 
 canal for, 1154 
 cartilaginous portion of, 
 
 1154 
 osseous portion of, 1154 
 valve, 567 
 in foetus, 578 
 Excretory apparatus of liver, 
 
 1342 
 Exo-gnathion, 111 
 Expiration, muscles of, 432 
 Expression, muscles of, 385 
 Exsanguinated renal zone of 
 
 Hyrtl, 679, 1423 
 Extensor brevis digitorum mus- 
 cle, 543 
 pollicis muscle, 489 
 carpi radialis brevior muscle, 
 485 
 bursa of, 486 
 longior muscle, 485 
 ulnaris muscle, 487 
 coccygeus muscle, 422 
 communis digitorum muscle, 
 486 
 relations of, 487 
 indicis muscle, 490 
 longus digitorum muscle, 533 
 
 pollicis muscle, 489 
 minimi digiti muscle, 487 
 ossis metacarpi pollicis, 489 
 primi internodii pollicis mus- 
 cle, 489 
 proprius hallucis muscle, 532 
 
 relations of, 533 
 secundi internodii pollicis mus- 
 cle, 489 
 
INDEX 
 
 1563 
 
 External abdominal ring, 436, 
 1514 
 acoustic canal, 1148 
 angular process, 80, 140 
 annular ligament, 542 
 anterior thoracic nerve, 984 
 arcuate ligament, 427, 449 
 auditory canal, 1148 
 
 meatus, 138, 1148 
 bicipital ridge, 179 
 ■calcaneal nerves, 1014 
 ■calcanean artery, 718 
 •calcaneo-astragaloid ligament, 
 352 
 
 -scaphoid ligament, 353 
 ■capsule of brain, 894 
 carotid artery, 600 
 
 foramen, 89 
 circumflex arterj' of thigh, 705 
 condyle of femur, 226 
 crucial ligament, 337 
 cutaneous nerve, 985, 1003 
 car, 1144 
 cpicondyle, 181 
 geniculate body, 904, 912 
 hiemorrhoidal veins, 760 
 iliac artery, 694 
 
 glands, 797 
 
 vein, 759 
 inguinal fossa, 1520 
 
 hernia, 1520 
 interchondral ligament, 290 
 intercostal muscle, 425 
 jugular vein, 728 
 lateral ligament, 280, 310 
 malleolus, 238 
 
 ligament of, 1160 
 mammary artery, 651 
 maxillary artery, 604 
 oblique line, 123 
 
 muscle, 433 
 
 aponeurosis of, 1513 
 occipital crest, 72, 136 
 
 protuberance, 71, 136 
 orbital foramina, 95 
 OS, 1489 
 
 palatine nerve, 1035 
 palpebral arteries, 623 
 parietal diploic vein, 734 
 parieto-occipital sulcus, 867 
 plantar artery, 720 
 
 nerve, 1016 
 popliteal nerve, 1016 
 ptervgoid muscle, 383 
 
 nerve, 1037 
 
 plate, 96 
 pudic artery, deep, 704 
 superficial, 704 
 deep, 704 
 saphenous gland, 795 
 
 vein, 756 
 semicircular canal, 1165 
 semilunar fibrocartilage, 339 
 spermatic fascia, 436, 1514 
 sphincter ani muscle, 450 
 supracondylar ridge, 179 
 tarsal ligament, 370 
 tuberosity of tibia, 233 
 lilxtracranial lymphatics, 780 
 Extrinsic muscles of tongue, 398 
 Eye, 1103 
 
 appendages of, 1137 
 aqueous humor of, 1128 
 choroid, 1111 
 ciliary muscle, 1115 
 conjunctiva, 1140 
 cornea, 1108 
 crystalline lens, 1130 
 globe of, arteries of, 1132 
 
 lymphatics of, 1133 
 
 nerves of, 1134 
 
 Eye, globe of, veins of, 1133 
 
 iris, 1117 
 
 lachrymal apparatus, 1141 
 glands, 1141 
 sac, 1142 
 
 nasal duct, 1142 
 
 pupil of, 1117 
 
 refracting media of, 1128 
 
 retina, 1120 
 
 sclera, 1107 
 
 surgical anatomy of, 1134 
 
 -teeth, 1197 
 
 tunics of, 1107 
 
 uvea of, 1118 
 
 vitreous body of, 1129 
 Eyeball, coverings of, 375 
 Eyebrow, 1137 
 Eyelashes, 1138 
 
 surgical anatomy of, 1143 
 Eyelid, 1137 
 
 Meibomian glands of, 1139 
 
 orbital portion, 1137 
 
 structure of, 1138 
 
 surface form of, 1143 
 
 surgical anatomy of, 1143 
 
 tarsal portion, 1137 
 Erythroblasts, 36 
 
 Face, arteries of, 604 
 bones of, 104 
 exterior of, veins of, 725 
 fasciae of, 365 
 lymphatics of, 779 
 muscles of, 365 
 
 surface form of, 385 
 nerves of, 1044 
 veins of, 726 
 Facet, clavicular, 157 
 
 costal, 169 
 Facial artery, 604 
 
 branches of, 605 
 
 relations of, 605 
 
 surgical anatomy of, 607 
 
 transverse, 611 
 bones, 104 
 nerve, 1044 
 
 branches of, 1046 
 
 nucleus of, 925 
 
 surgical anatomy of, 1049 
 suture, transverse, 128 
 vein, anterior, 726 
 
 common, 726 
 
 transverse, 727 
 
 surgical anatomy of, 726 
 Falciform crest, 89 
 ligament, 293 
 
 of liver, 1333 
 process of fascia lata, 515 
 Fallopian tube, 1497 
 
 ampulla of, 1497 
 
 artery of, 1498 
 
 course pursued by, 1498 
 
 fimbriae of, 1497 
 
 infundibulum of, 1497 
 
 isthmus of, 1497 
 
 lymphatics of, 804, 1498 
 
 nerve of, 1499 
 
 structure of, 1498 
 
 uterine portion of, 1497 
 
 vein of, 1498 
 False pelvis, 215 
 ribs, 159 
 
 vocal cords, 1370 
 Falx cerebelli, 850 
 cerebri, 849 
 inguinalis, 448 
 Fascia or fasciae, 361 
 of abdomen, deep, 433 
 
 Fascia or fasciae, of abdomen, 
 superficial, 433, 1511 
 
 triangular, 1515 
 of acromial region, 470 
 anal, 454, 1546 
 of arm, 474 
 
 deep, 470 
 
 superficial, 470 
 axillary, 463, 646 
 of back, deep, 411 
 
 superficial, 411 
 bicipital, 476, 746 
 bucco-pharyngeal, 380, 388, 
 
 401, 1222 
 of Camper, 433 
 cervical, deep, 387 
 
 superficial, 386 
 clavi-pectoral, 467 
 of CoUes, 456, 1515 
 costo-coracoid, 467 
 of cranium, 365 
 cremasteric, 1464, 1516 
 cribriform, 512, 1527 
 deep, 364 
 dentate, 879, 898 
 endo-pel-vica, 1544 
 endothoracic, 1385 
 of face, 365 
 
 of femoral region, anterior, 
 deep, 513 
 superficial, 512 
 of foot, 541 
 of forearm, 478 
 of hand, 491 
 of hip, 522 
 ihac, 508 
 infraspinatus, 472 
 infundibulifomi, 446, 1464 
 intercolumnar, 436, 1463, 1514 
 intercostal, 424 
 ischio-rectal, 454, 1546 
 lata, 513, 1527 
 
 falciform process of, 1528 
 
 iliac portion, 514, 1528 
 
 pubic portion, 514, 1528 
 of leg, 532 
 
 transverse, 537 
 of lo-wer extremity, 507 
 masseteric, 381 
 of neck, 385 
 obturator, 1546 
 of orbit, 374 
 palmar, deep, 493 
 palpebral, 1139 
 parotid, 388, 1215 
 parotideo-masseterica, 388 
 pectoral, deep, 464 
 pelvic, 1544 
 
 of perinaeum in male, deep, 
 458, 1538 
 superficial, 455 
 phrenico-pleural, 1386 
 plantar, 542 
 pre-tracheal, 388 
 prevertebral, 388 
 of quadratus lumborum, 449 
 recto- vesical, 1546 
 retro-renal, 1412 
 salpingopharyngea of Troltsch 
 
 1155 
 of Scarpa, 433 
 semilunar, 476 
 of shoulder, deep, 470 
 
 superficial, 470 
 spermatic, 1463 
 
 external, 436, 1514 
 internal, 446 
 middle, 440 
 subscapular, 471 
 superficial, 364 
 
 of cranial region, 366 
 
1564 
 
 INDEX 
 
 Fascia or fasciae, supraspinatus, 
 472 
 temporal, 381 
 of thigh, 512 
 
 of thoracic region, anterior, 
 deep, 463 
 superficial, 463 
 of thorax, 424 
 transversalis, 445, 1517 
 triangular, 437 
 of trunk, 410 
 of upper extremity, 462 
 Fascial canal, 1536 
 Fasciculi, 261 
 Fasciculus cuneatus, 941 
 gracilis, 941 
 
 clava of, 941 
 longitudinal, inferior, 918 
 
 superior, 918 
 occipito-frontal, 918 
 perpendicular, 918 
 rectus, 918 
 of Rolando, 941 
 teres, 945 
 of Turck, 842 
 uncinate, 917 
 Fasciola cinerea, 879 
 Fauces, isthmus of, 1212 
 
 pillars of, 1211 
 Female bladder, 1446 
 
 organs of generation, 1477 
 perinaeum, 1542 
 urethra, 1446 
 Femoral artery, 697 
 
 anastomotica magna of, 707 
 branches of, 704 
 common, 699 
 deep, 704 
 
 peculiarities of, 701 
 superficial, 700 
 surface marking of, 701 
 surgical anatomy of, 701 
 canal, 509, 1531 
 cutaneous nerves, 1011 
 hernia, 1525 
 complete, 1534 
 coverings of, 1533 
 descent of, 1533 
 incomplete, 1533 
 varieties of, 1533 
 ligament, 515 
 
 lymphatic glands, deep, 795 
 region, anterior, fascia of, deep, 
 513 
 superficial, 512 
 surgical anatomy of, 515 
 muscles of, 512 
 dissection of, 512 
 surgical anatomy of, 518 
 internal, muscles of, 519 
 dissection of, 519 
 surgical anatomy of, 522 
 posterior, muscles of, 529 
 dissection of, 529 
 surgical anatomy of, 531 
 ring, 437, 509, 1532 
 sheath, 509, 1530 
 spur, 227 
 vein, 758 
 Femur, 221 
 
 articulations of, 228 
 attachment of muscles to, 229 
 condyles of, 225 
 development of, 228 
 lower extremity of, 225 
 shaft of, 224 
 borders of, 225 
 linea aspera, 224 
 surfaces of, 225 
 spiral line of, 223 
 structure of, 226 
 
 Femur, surface form of, 229 
 surgical anatomy of, 229 
 trochlea of, 225 
 tubercle of, 223 
 tuberosities of, 226 
 upper extremity of, 221 
 head of, 221 
 neck of, 222 
 trochanters of, 223 
 Fenestra ovalis, 1152 
 rotunda, 1152, 1167 
 Fenestrated membrane of Henle, 
 
 585 
 Ferrein, pyramids of, 1417 
 Fibre-baskets, 1127 
 Fibres of auricles of heart, 575 
 of cerebellum, peduncular, 932 
 projection, 932 
 proper, 936 
 of cerebrum, association, 916 
 commissural, 916 
 peduncular, 914 
 projection, 914 
 transverse, 916 
 of cord, dorso-ventral, 841 
 longitudinal, 841 
 oblique, 841 
 transverse, 841 
 dental, 1202 
 enamel, 1203 
 
 inter-cerebral, of optic com- 
 missure, 1021 
 intercolumnar, 436 
 of internal capsule of brain, 
 
 892 
 lens, 1130 
 of medulla, arciform, 942 
 
 arcuate, 942 
 of pons Varolii, 923 
 longitudinal, 923 
 transverse, 923 
 preanal, of levator ani, 453 
 prd-rectales, 454 
 of Remak, 823 
 of Sharpey, 37 
 sustentacular, 1121 
 of tegmentum, 908 
 of ventricles of heart, 575 
 Fibro-cartilage, 260 
 
 circumferential, 261 
 connecting, 261 
 interarticular, 281, 298, 300 
 
 triangular, 315 
 intervertebral, 270 
 semilunar, 337 
 stratiform, 261 
 -elastic coat of spleen, 1356 
 -muscular coat of gall-bladder, 
 1343 
 Fibrous band of Baillarger, 920 
 of Bechterew, 920 
 coat of liver, 1337 
 of pharynx, 1223 
 of ureter, 1427 
 membrane of trachea, 1379 
 rings of heart, 574 
 septum of tongue, 398 
 sheaths of flexor tendons, 545 
 tissue, white, 261 
 Fibula, 237 
 
 articulations of, 238 
 attachment of muscles to, 239 
 development of, 238 
 lower extremity of, 23*8 
 nutrient artery of, 718 
 oblique line of, 237 
 shaft of, 237 
 borders of, 237 
 surfaces of, 238 
 styloid process of, 237 
 surface form of, 239 
 
 Fibula, surgical anatomy of, 239 
 
 upper extremity of, 237 
 Fibular artery, superior, 713 
 region, muscles of, 539 
 actions of, 540 
 dissection of, 539 
 surgical anatomv of, 541 
 Fifth nerve, 1026 
 nuclei of, 925 
 root of, ascending, 948 
 semilunar ganglion of, 1027 
 surface marking of, 1041 
 surgical anatomy of, 1041 
 ventricle, 897 
 Filiform papilla; of tongue, 109O 
 Fillet, decussation of, 949 
 
 of gyrus fornicatus, 879, 918 
 interoUvary, 909, 949 
 lateral, 885, 910 
 lower, 910 
 median, 910 
 mesial, 910 
 superior, 910 
 upper, 910 
 Filtrum ventriculi of Merkel, 
 
 1368 
 Fimbria, 898 
 Fimbriae of Fallopian tube, 1497 
 
 of ovary, 1499 
 Fimbrio-dentate fissure, 898 
 Finger, index, metacarpal bone 
 of, 202 
 ligaments of, 322 
 
 superficial transverse, 494 
 little, metacarpal bone of, 203 
 middle, metacarpal bone of, 
 
 202 
 ring, metacarpal bone of, 203 
 veins of, superficial, 745 
 First nerve, 1019 
 Fissura antitragohelicina, 1146 
 prima, 881 
 vestibuli, 1168 
 Fissure or fissures, antero-lateral, 
 838 
 antero-median, 837 
 antitragohelicina, 1146 
 auricular, 90, 136 
 of Bichat, 900 
 of brain, 865 
 calcarine, 870 
 callosal, 879 
 of cerebellum, 927, 930 
 of cerebrum, longitudinal, 865 
 
 882 
 choroid, 890, 900 
 collateral, 871 
 of cord, 837 
 lateral 838 
 dentate, 871, 879 
 dorso-median, 838 
 of ductus venosus, 1331 
 fimbrio-dentate, 898 
 of gall-bladder, 1331 
 Glaserian, 84, 1152 
 hippocampal, 871, 879 
 of liver, 1331 
 
 longitudinal, 1331 
 transverse, 1332 
 of lung, 1392 
 mammary, prolongations of, 
 
 1505 
 orbital, 96 
 
 petro- tympanic, 84, 1152 
 portal, 1332 
 posterior median, 838 
 post-clival, 928 
 -limbic, 871 
 -nodular, 930 
 -pvramidal, 930 
 pre-cHval, 928 
 
INDEX 
 
 1565 
 
 Fissure or fissures, pre-pvra- 
 midal, 930 
 pterygoid, 96 
 ptervgo-maxillarv, 139 
 of Rolando, 867 " 
 sphenoidal 96, 132 
 spheno-maxillarv, 115, 138 
 of Santorini, 1146, 1148 
 of spinal cord, 837 
 of Sylvius, 866, 884 
 of tragus, 1146 
 umbilical, 1331 
 ventro-median, 837 
 Flat bones, 34 
 
 Flechsig, fibrous systems of, 915 
 Flexor accessorius muscle, 546 
 brevis digitorum muscle, 544 
 hallucis muscle, 546 
 minimi digiti m.uscle, foot, 
 547 
 hand, 498 
 pollicis muscle, 497 
 carpi radialis muscle, 479 
 
 ulnaris muscle, 480 
 longus digitorum muscle, 538 
 hallucis muscle, 538 
 pollicis muscle, 482 
 ossis metacarpi pollicis mus- 
 cle, 497 
 profundus digitorum muscle, 
 
 482 
 sublimis digitorum muscle, 481 
 tendons, fibrous sheaths of, 545 
 Flexure of colon, hepatic, 1309 
 sigmoid, 1311 
 splenic, 1309 
 of duodenum, superior, 1285 
 of large intestine, hepatic, 1300 
 sigmoid, 1300 
 splenic, 1300 
 Floating lobe of hver, 1336 
 Floccular fossa, 89, 133 
 Flocculus, 931 
 
 peduncle of, 931 
 Flood's ligament, 304 
 Foetal circulation, 579 
 
 lung, 1394 
 Fold of Douglas, semilunar, 439, 
 444 
 duodenal, 1260 
 hypogastric, 1519 
 ovario-pelvic, 1500 
 recto-vaginal, 1490 
 of urachus, 1519 
 utero- vesical, 1490 
 of uterus, 1489 
 Folia linguae, 1087 
 Folium cacuminis, 929 
 Follicle, dental, 1206 
 simple, 1295, 1319 
 Follicular lymph-sinus, 1306 
 Fontana, spaces of, 1110 
 Fontanelles, 102 
 
 anterior, 78 
 Foot, arteries of, 714 
 bones of, 239 
 bursfB of, 543 
 development of, 253 
 fascia; of, 541 
 ligaments of, 541 
 muscles of, 541 
 nerves of, 1015 
 phalanges of, 252 
 
 articulations of, 359 
 sole of, dissection of, 542 
 surface form of, 255, 360 
 surgical anatomy of, 256, 360 
 veins of, 758 
 Foramen, 96 
 
 Cfficum, 80, 130, 1087 
 carotid, external, 89 
 
 Foramen, carotid, internal, 88 
 condyloid, anterior, 73, 133, 
 136 
 
 posterior, 73, 133, 136 
 costo-transverse, 50 
 dental, inferior, 124 
 diaphragmatis sellse, 883 
 ethmoidal, anterior, 130, 141 
 
 posterior, 130, 141 
 of Huschke, 92 
 infraorbital, 106, 140 
 jugular, 73, 133 
 of Key and Retzius, 853 
 lacerum anterius, 96, 132 
 
 medium, 132 
 
 posterius, 133 
 of Langer, 464, 646, 791 
 magnum, 72, 133 
 of Majendie, 834, 853 
 malar, 113 
 mastoid, 85, 138 
 mental, 123, 140 
 of Monro, 889 
 obturator, 214 
 optic, 93, 131, 142 
 ovale, 95, 132, 567 
 
 in foetus, 578 
 palatine, great, 116 
 
 posterior, 135 
 parietal, 76 
 pterygo-palatine, 95 
 quadratum of diaphragm, 430 
 rotund um, 95, 132 
 sacro-sciatic, great, 211, 294 
 singulare, 89, 1169 
 of Sommerring, 1121 
 spheno-palatine, 119, 143 
 spinal, 49, 132 
 sternal, 157 
 stylo-mastoid, 90, 135 
 supratrochlear, 181 
 supraorbital, 80, 140 
 temporo-malar, 115 
 thyroid, 214 
 vertebral, 49 
 vertebrarterial, 50 
 Vesalii, 95, 132 
 Foramina of diaphragm, 430 
 ethmoidal, 82 
 incisor, 110 
 intervertebral, 49 
 of Key and Retzius, 834 
 malar, 113 
 olfactory, 143 
 orbital, external, 95 
 sacral, anterior, 62 
 
 posterior, 63 
 of Scarpa, 110, 135, 1036 
 of Stenson, 110 
 Thebesii, 567, 568, 771 
 Fore-gut, 1236 
 Forearm, arteries of, 657 
 bones of, 184 
 fasciae of, 478 
 interosseous veins of, 747 
 lymphatics of, 788 
 muscles of, 478 
 
 dissection of, 478, 482 
 nerves of, 984 
 veins, 744 
 Fore-brain, 857 
 Forel, occipito-frontal fasciculus 
 
 of, 918 
 Form of bones, 33 
 Formatio reticularis, 845, 948 
 
 alba, 949 
 
 grisea, 949 ' 
 Fornix, 895 
 body of, 895 
 of conjunctiva, 1140 
 lyra of, 896 
 
 Fornix, pillars of, anterior, 895 
 
 posterior, 896 
 vaginal, 1484 
 Fossa or fossae of acetabulum,213 
 of antihelix, 1144 
 canine, 106, 140 
 condyloid, anterior, 136 
 
 posterior, 136 
 coronoid, 181 
 cranial, 143 
 digastric, 86, 123, 136 
 digital, 223 /- 
 
 duodenal, 1260 
 duodeno-jejunal, 1261 
 floccular, 89, 133 
 glenoid, 84, 135 
 of heUx, 1145 
 ileo-appendicular, 1263 
 
 -Cffical, 1263 
 
 -colic, 1262 
 iliac, 209 
 
 incisive, 106, 123, 139 
 incudis, 1153 
 infraspinous, 172 
 inguinal, 1248, 1520 
 
 external, 1520 
 
 internal, 1520 
 
 middle, 1520 
 intersigmoid, 1312 
 ischio-rectal, 1536 
 jugular, 91 
 lachrymal, 81 
 of Landzert, 1262 
 longitudinal, of liver, 1331 
 mandibular, 84 
 mastoid, 86 
 mesocolic, 1261 
 myrtiform, 106 
 nasal, 142, 1098 
 navicularis of urethra, 1444 
 
 of vulva, 1478 
 occipital, 133 
 olecranon, 181 
 orbital, 143 
 ovalis, 567 
 
 palatine, anterior, 110, 133 
 paraduodenal, 1262 
 patellaris, 1129 
 pericaecal, 1262 
 pituitary, 93 
 pterygoid, 96, 115 
 radial, 181 
 retro-caecal, 1263 
 
 -colic, 1263 
 
 -duodenal, 1262 
 
 -peritoneal, 1260 
 rhomboid, inferior, 840 
 of Rosenmiiller, 1221 
 of Scapha, 1145 
 scaphoid, 97, 135, 1145 
 sigmoid, 86 
 of skull, anterior, 130 
 
 infratemporal, 138 
 
 middle, 130 
 
 orbital, 140 
 
 pterygo-palatine, 139 
 
 posterior, 132 
 
 spheno-maxillary, 139 
 
 temporal, 137 
 
 zygomatic, 138 
 spheno-maxillary, 115 
 sublingual, 123 
 submaxillary, 123 
 subscapulus, 171 
 supra-tonsillar, 1213 
 supraspinous, 172 
 temporal, 76 
 of Treitz, 1260 
 trochanteric, 223 
 trochlear, 82 
 umbilical, 1331 
 
1566 
 
 INDEX 
 
 Fossula inferior, 1168 
 
 superior, 1168 
 Fourchette, 1478 
 Fourth nerve, 1025 
 ventricle, 942 
 
 lining membrane of, 945 
 roof of, 943 
 triangles of, 945 
 wall of, anterior, 944 
 posterior, 943 
 Fovea centralis retinae, 1121, 
 1128 
 hemielliptica, 1164 
 hemispherica, 1164 
 inguinalis lateralis, 1520 
 
 mesialis, 1520 
 oblonga, 1364 
 superior, 945 
 supra- vesicularis, 1520 
 triangularis, 1364 
 Foveolas, Howship's, 38 
 Fraenulum of cerebellum, 928 
 
 of ileo-csecal valve, 1308 
 Fraenum of clitoris, 1479 
 
 labii superioris et inferioris, 
 
 1194 
 linguae, 1087 
 of penis, 1455 
 Frontal air sinus, 82 
 artery, 611 
 
 from anterior cerebral, ante- 
 rior internal, 627 
 inferior internal, 627 
 middle internal, 627 
 posterior internal, 627 
 from middle cerebral, as- 
 cending, 628 
 inferior external, 628 
 from ophthalmic, 625 
 bone, 79 
 
 horizontal portion of, 81 
 articulations of, 83 
 attachment of muscles 
 
 to, 83 
 border of, 82 
 development of, 82 
 structure of, 82 
 orbital portion of, 81 
 articulations of, 83 
 attachment of muscles 
 
 to, 83 
 border of, 82 
 development of, 82 
 structure of, 82 
 vertical portion, 79 
 border of, 81 
 structure of, 81 
 convolutions, ascending, 872 
 inferior, 873 
 middle, 873 
 superior, 873 
 crest, 80, 130 
 diploic vein, 734 
 eminence, 79 
 
 horn of lateral ventricle, 889 
 lobe, 872, 884 
 nerve, 1030 
 operculum, 866, 874 
 process of malar, 114 
 spine, 80 
 sulci, 868, 873 
 suture, 79, 127 
 vein, 725 
 Frontalis muscle, 368 
 Fron to-parietal suture, 127 
 -malar suture, 128 
 -sphenoidal suture, 128 
 Fundamental plexus, 1111 
 Fundiform ligament of Retzius, 
 
 541 
 Fundus glands, 1277 
 
 Fundus of internal auditory 
 meatus, 1168 
 
 tympani, 1151 
 
 of uterus, 1487 
 Fungiform papillae of tongue, 
 
 1090 
 Funicular process, hernia of, 
 
 1523 
 Funiculus, cuneate, 941 
 
 gracilis, 941 
 
 of Rolando, 941 
 
 slender, 941 
 
 teres, 945 
 
 wedge-shaped, 941 
 Furcula, 1242 
 Furrow, interarticular, 565 
 
 sternal, 165 
 Fusiform muscles, 362 
 
 G 
 
 Galactophorus duct, 1507 
 Galen, testes muUebres of, 1499 
 
 veins of, 735, 771 
 Gall-bladder, 1342 
 
 arteries of, 1346 
 
 body of, 1343 
 
 fibro-muscular coat of, 1343 
 
 fissure for, 1331 
 
 fundus of, 1343 
 
 lymphatics of, 1346 
 
 mucous coat of, 1343 
 
 neck of, 1343 
 
 nerves of, 1346 
 
 notch of, 1331 
 
 relations of, 1343 
 
 serous coat of, 1343 
 
 structure of, 1343 
 
 surgical anatomy of, 1347 
 
 veins of, 1346 
 Ganglia of nerves, 831 
 
 semilunar, of abdomen, 1084 
 of spinal nerves, 966 
 Gangliated cord, 1071 
 
 cervical portion of, 1071 
 
 lumbar portion of, 1079 
 
 pelvic portion of, 1080 
 
 sacral portion of, 1080 
 
 thoracic portion of, 1078 
 Ganglion of Andersch, 1056 
 Arnold's, 1039 
 of Bochdalek, 1033 
 cardiac, of Wrisberg, 1081 
 carotid, 1073 
 cephalic, 1031 
 of cerebellum, 937 
 cervical, inferior, 1077 
 
 middle, 1076 
 
 superior, 1072 
 ciliarv, 1031 
 
 long root of, 1030 
 of Corti, 1053 
 diaphragmatic, 1084 
 of facial nerve, 1045 
 of fifth nerve, 1031 
 Gasserian, 1027 
 geniculate, 1034, 1045 
 of glosso-pharvngeal, 1056 
 impar, 1068 
 inferior, 1056 
 interpeduncular, 910 
 jugular, 1056 
 lenticular, 1031 
 lumbar, 1080 
 Meckel's, 1034 
 mesenteric, 1085 
 ophthalmic, 1031 
 otic, 1039 
 petrous, 1056 
 pharyngeal, 1073 
 
 Ganglion, phrenic, 1084 
 of pneumogastric, 1059 
 of portio dura, 1045 
 radicis cochlearis, 950 
 of Ribes, 1067 
 semilunar, of abdomen, 1084 
 
 of fifth nerve, 1027 
 spheno-palatinc, 1034 
 of spinal nerves, 966 
 submaxillary, 1040 
 superior, 1056 
 of sympathetic nerves, 107L 
 thoracic, 1078 
 thvroid, 1076 
 of Valentin, 1033 
 vestibular, 1053 
 Ganglionar gray matter, 922 
 Ganglionic arteries, postero- 
 lateral, 640 
 postero-median, 640 
 branch of nasal nerve, 1030 
 vessels of brain, central, 630 
 Gartner's duct, 1499 
 Gasserian ganglion, 1027 
 
 branches of, 1027 
 Gastric area of kidnej^ 1414 
 artery, 671, 674 
 glands, 800, 1277 
 
 true, 1277 
 impression, 1333 
 nerves, 1061 
 plexus, 1085 
 surface of liver, 1329 
 
 of spleen, 1354 
 veins, 768 
 Gastro-colic omentum, 1256 
 -duodenal plexus, 1085 
 -duodenalis artery, 673 
 -epiploic plexus, 1085 
 left, 1085 
 vein, 768 
 -epiploica dextra arter}', 673 
 
 sinistra artery, 674 
 -hepatic omentum, 1254 
 -splenic ligament, 1256 
 omentum, 1256 
 Gastrocnemius muscle, 534 
 
 bursa of, 534 
 Gemellus muscle, inferior, 527 
 
 superior, 526 
 Generation, organs of, develop- 
 ment of, 1547 
 female, 1477 
 male, 1447 
 Genial gland, 782 
 
 tubercles, 123 
 Geniculate body, external, 904. 
 912 
 internal, 904, 912 
 ganglion, 1034, 1045 
 Genio-glossus muscle, 396 
 -hyo-glossus muscle, 396 
 -hyoid muscle, 395 
 Genito-crural nerve, 1000 
 crural branch, 1000 
 genital branch, 1000 
 Germ of corpus callosum, 886 
 Gerlach, valve of, 1303 
 Germinal epithelium of Wal- 
 
 deyer, 1501 
 Giacomioni, band of, 879 
 Gianuzzi, crescents of, 1218 
 Gimbernat's ligament, 437, 1515 
 Gingival branches of dental 
 
 nerves, 1032 
 Ginglymus, 265 
 Giraldes, organ of, 1473 
 Girdle, pelvic, 207 
 
 shoulder, 207 
 Glabella of frontal bone, 80, 139 
 Gladiolus, 157 
 
INDEX 
 
 1567 
 
 Gladiolus, borders o', 157 
 
 surfaces of, 157 
 Glands, absorbent, 774 
 agminated, 1296 
 apical, 1091 
 arytenoid, 1375 
 of Bartholin, 1482 
 of biliary duets, 1342 
 of Bowman, 1101 
 Brunner's, 1295 
 buccal, 1195 
 cardiac, 1278 
 carotid, 1409 
 ceruminous, 1149 
 ciliary, 1190 
 circumanal, 1190 
 coccygeal, 1410 
 conglobate, 774 
 Cowper's, 1453 
 ductless, 1401 
 duodenal, 1295 
 of Duvemey, 1482 
 epiglottis, 1374 
 fundus, 1277 
 gastric, 1277 
 intestinal, 1295, 1319 
 labial, 1195 
 lachrymal, 1141 
 of larynx, 1374 
 lenticular, of stomach, 1277 
 of Lieberkiihn, 1295, 1319 
 lingual, 1091 
 of Littr^, 1444 
 Luschka's, 1410 
 lymphatic, 774 
 mammary, 1503 
 
 lymphatics of, 812 
 Meibomian, 1139 
 molar, 1195 
 of Moll, 1138 
 of Montgomery, 1504 
 mucilaginous, 262 
 mucous, 1218 
 
 of Nuhn and Blandin, 1091 
 odoriferae, 1454 
 oesophageal, 1230 
 oxvntic, 1277 
 of Pacchioni, 737, 854 
 palatal, 1211 
 parotid, 1214 
 peptic, 1277 
 Peyer's, 1296 
 pharyngeal, 1224 
 pineal, 905 
 
 peduncles of, 895 
 prostate, 1447 
 
 lymphatic vessels of, 803 
 pyloric, 1277 
 of Rosenmiiller, accessory, 
 
 1141 
 salivary, 1214 
 sebaceous, 1138, 1191 
 solitary, 1295, 1320 
 sublingual, 1217 
 submaxillary, 1216 
 subparotid, 1215 
 suburethral, 1482 
 sudoriferous, 1190 
 suprarenal, 1428 
 sweat, 1190 
 tarsal, 1139 
 thymus, 1407 
 thyroid, 1401 
 
 arteries of, 602 
 
 lymphatic vessels of, 782 
 
 veins of, 731 
 of tongue, 1091 
 tracheal, 1380 
 of Tyson, 1454 
 of V. Ebner, 1091 
 vulvo-vaginal, 1482 
 
 Glandulse Pacchioni, 737, 854 
 
 Tysonii odoriferae, 1454 
 Glans clitoridis, 1480 
 
 penis, 1454 
 Glaserian fissure, 84, 1152 
 Gleno-humeral ligament, 305 
 Glenoid cavitv, 175 
 fossa, 84, 135 
 ligament, 175 
 
 of Cruveilhier, 359 
 tuberosity, 175 
 Glisson, capsule of, 770, 1256, 
 
 1337 
 Globus of epididymis major, 
 1469 
 minor, 1469 
 Glosso-epiglottic ligament, 1365 
 -epiglottidean folds, 1366 
 -pharyngeal nerve, 1054 
 nuclei of, 950 
 surgical anatomy of, 1057 
 Glottis, cliink of, 1369 
 false, 1369 
 respiratoria, 1369 
 true, 1369 
 vocalis, 1369 
 Gluteal artery, 694 
 inferior, 693 
 cutaneous nerve, 1011 
 glands, 797 
 line, anterior, 207 
 inferior, 208 
 posterior, 207 
 nerve, inferior, 1011 
 
 superior, 1010 
 region, Ivmphatic vessels of, 
 801 ' 
 muscles of, 522 
 dissection of, 522 
 surgical anatomy of, 528 
 ridge, 224 
 veins, 761 
 Gluteo-femoral bursa, 331 
 Gluteus maximus muscle, 522 
 medius muscle, 523 
 minimus muscle, 523 
 Golgi, cells of, 821 
 
 organ of, 829 
 GoU, tract of, 839, 843 
 Gomphosis, 264 
 Gonion, 124 
 Graafian vesicles, 1502 
 
 membrana granulosa of, 
 
 1502 
 ovicapsule of, 1502 
 Gracilis muscle, 519 
 Grande lobe limbique, 878 
 Grandy's corpuscles, 827 
 Granular sheath of Tomes, 1202 
 Gray commissure of brain, 903 
 of cord, 839 
 anterior, 839 
 posterior, 839 
 matter, central, 922 
 of cerebellum, 936 
 of cerebrum, 918 
 of cortex, 918 
 of ganglia, 922 
 of medulla, 945 
 of pons, 924 
 ventricular, 922 
 nerve-fibres, 823 
 substance of cord, 845 
 anterior horn, 845 
 dorsal horn, 845 
 lateral horn, 845 
 nerve-cells of, 845 
 
 -fibres of, 845 
 posterior horn, 845 
 ventral horn, 845 
 Great auricular nerve, 972 
 
 Great cardiac nerve, 1077 
 plexus, 1081 
 vein, 770 
 
 deep petrosal nerve, 1034 
 
 occipital nerve, 969 
 
 omentum, 1256 
 
 sacro-sciatic foramen, 294 
 ligament, 292 
 
 sciatic nerve, 1013 
 
 sinus of aorta, 589 
 
 superficial petrosal nerve, 1034 
 Greater alar cartilage, 1097 
 
 wings of sphenoid, 95 
 Grooves, auriculo- ventricular of 
 heart, 565 
 
 basilar, 75 
 
 bicipital, 179 
 
 caroti^, 93 
 
 cavernous, 93 
 
 of cord, 837 
 
 infraorbital, 107, 141 
 
 interventricular, 568 
 of heart, 565 
 
 intervertebral, 49 
 
 lachrymal, 107, 109, 141, 143: 
 
 musculo-spiral, 179 
 
 mylo-hyoidean, 124 
 
 naso-palatine, 121 
 
 obturator, 211, 213 
 
 occipital, 86 
 
 optic, 93, 130, 131 
 
 peroneal, 245 
 
 popliteal, 226 
 
 pterygopalatine, 116 
 
 sacral, 63 
 
 of spinal cord, 837 
 
 subclavian, 169 
 
 subcostal, 162 
 
 ulnar, 182 
 
 vertebral, 155 
 Gubemaculum testis, 1461 
 Gudden's commissure, 912, 1021 
 Guerin, valve of, 1444 
 Gulf of internal jugular vein, 72ft 
 Gullet, 1225 
 Gums, 1195 
 
 surgical anatomy of, 1224 
 Gustatory cells, 1091 
 
 hair, 1091 
 
 nerve, 1038 
 
 branches of, 1038 
 
 path, 1057 
 
 pore, 1090 
 Gyri of brain, 865 
 
 brevis insulse, 878 
 Gyrus, angular, 876 
 
 annectant, deep, 867 
 
 cinguli, 879 
 
 fomicatus, fillet of, 879, 91S 
 
 lingual, 877 
 
 longus insulse, 870 
 
 marginal, 875 
 
 occipi to-temporal, 877 
 
 post-central, 876 
 
 prsecentral, 872 
 
 rectus, 874 
 
 subcallosus, 882 
 
 supra-callosus, 88V 
 
 HABENTJIiA, 904 
 
 commissure of, 904 
 trigone of, 904 
 Hsemorrhoidal artery, inferior, 
 690 
 middle, 687 
 superior, 678 
 gland, middle, 799 
 nerve, inferior, 1011 
 
1568 
 
 INDEX 
 
 Hacmorrhoidal plexus, inferior, 
 1086 
 superior, 1085 
 veins, external, 760 
 inferior, 760, 1011 
 middle, 760 
 superior, 768 
 surgical anatomy of, 761 
 Hair, 1187 
 
 bloodvessels of, 1189 
 -bulb, 1187 
 
 coats of, dermic, 1188 
 of, epidermic, 1188 
 cortical substance of, 1189 
 -follicle, 1187 
 gustatory, 1091 
 nerves of, 1189 
 olfactory, 1101 
 -papilla, 1187 
 root of, 1187 
 shaft of, 1189 
 stem of, 1189 
 -streams, 1187 
 -whirlpools, 1187 
 Haller, rete testis of, 1471 
 Hamstring muscles, 529 
 Hamular process of lachrymal, 
 113 
 of sphenoid, 96 
 Hamulus, 1168 
 Hand, arteries of, 660 
 bones of, 193 
 
 development of, 205 
 bursa of, 492 
 fasciae of, 491 
 ligaments of, 319 
 muscles of, 491 
 
 dissection of, 491 
 nerves of, from median, 987 
 from radial, 991 
 from ulnar, 989 
 phalanges of, 204 
 veins of, 745 
 Hard palate, 1210 
 Harmonia, 264 
 Hasner, valve of, 1142 
 Haustra coli, 1317 
 Haversian canal, 38 
 Head, arteries of, 595 
 exterior of, veins of, 725 
 lymphatic glands of, 780 
 muscles of, surface form of, 
 
 385 
 veins of, 724 
 Heart, 562 
 
 arteries of, 577 
 auricles of, fibres of, 575 
 left, 568 
 
 sinus of, 568 
 right, 565 
 cavities of, capacity of, 564 
 circular fibres of, 575 
 component parts of, 565 
 endocardium, 574 
 fat upon, 564 
 fibrous rings of, 574 
 grooves of, auriculo-ventricu- 
 lar, 565 
 interventricular, 565 
 infundibulum of, 569 
 lymphatics of, 577 
 
 muscular fibres of, 575 
 myocardium, 574 
 nerves of, 577 
 position of, 562 
 size of, 564 
 spiral fibres of, 575 
 structure of, 574 
 muscular, 575 
 surface form of, 577 
 surgical anatomy of, 578 
 
 Heart, veins of, 577 
 
 ventricle of, fibres of, 575 
 
 right, 569 
 ventricular portion of, 568 
 vortex of, 575 
 weight of, 564 
 Heel bone, 242 
 
 Heidenhain, demilunes of, 1218 
 Helicine arteries, 1458 
 Helicis major muscle, 1147 
 
 minor muscle, 1147 
 Helicotrema of cochlea, 1167 
 Helix, 1144 
 crus of, 1145 
 fossa of, 1145 
 muscles of, 1147 
 spine of, 1146 
 Helmholtz, ligaments of, 1160 
 Helwig, tract of, triangular, 843 
 
 951 
 Hemispheres of brain, surface of, 
 under, 881 
 of cerebellum, 885, 926 
 of cerebrum, 864 
 
 constituent parts of, 864 
 general considerations of, 
 
 864 
 surfaces of, 865 
 
 external, lobes on, 869 
 mesial, fissures of, 869 
 
 sulci of, 869 
 outer, fissures of, 865 
 
 sulci of, 865 
 tentorial, fissures and 
 sulci of, 869 
 Henle, fenestrated membrane of, 
 585 
 ligament of, 438, 442 
 loop of, 1419 
 spine of, 88 
 Hensen, canalis reuniens of, 1170 
 cells of, 1175 
 node, 857 
 stripe, 1175 
 Hepatic area of kidneys, 1414 
 artery, 672 
 cells, 1338 
 ducts, 1342 
 flexure of colon, 1309 
 
 of large intestine, 1300 
 glands, 801 
 plexus, 1085 
 veins, 767 
 Hepato-colic ligament, 1255 
 -duodenal ligament, 1255 
 -gastric ligament, 1254 
 Herbst, corpuscles of, 829 
 Hernia, congenital, 1523 
 diaphragmatic, 427 
 encysted, 1523 
 femoral, 1525 
 of funicular process, 1523 
 infantile, 1523 
 inguinal, 1520 
 direct, 1523 
 external, 1520 
 obhque, 1517, 1520 
 scrotal, 1521 
 
 surgical anatomy of, 1511 
 Hesselbach, ligament of, 438, 
 442, 1517 
 triangle, 1520 
 Hey, ligament of, 515 
 Hiatus Fallopii, 88 
 sacralis, 62 
 semilunar, 747, 1099 
 tendineus, 521 
 Highmore, antrum of, 108 
 Hilton, compressor sacculi laryn- 
 gis muscle of, 1373 
 white line of, 1319 
 
 Hilum of kidney, 1415 
 of ovary, 1500 
 of spleen, 1354 
 Hind-brain, 922 
 
 -gut, 1236 
 Hinge-joint, 265 
 Hip, articulations of, 325 
 bursa of, 330 
 fascise of, 522 
 ligaments of, 326 
 muscles of, 522 
 surface form of, 333 
 surgical anatomy of, 333 
 Hippocampal convolution, 879 
 
 fissure, 871, 879 
 Hippocampus major, 889, 897 
 
 gray matter of, 921 
 His, sulcus terminalis of, 566 
 Histology of arteries, 584 
 
 of capillaries, 584 
 Hook bone, 199 
 Horizontal cells of Cajal, 1125 
 lamina of ethmoid, 99 
 plate of palate bone, 116 
 semicircular canal, 1165 
 Horner's muscle, 371 
 Homy layer of skin, 1181 
 Horseshoe kidney, 1424 
 Houston's valves, 1318 
 Howship's lacuna?, 38 
 Huguier, canal of, 84, 1047 
 Humeral region, anterior, mus- 
 cles of, 474 
 posterior muscles of, 477 
 Humerus, 177 
 
 articulations of, 183 
 attachment of muscles to, 
 
 183 
 capitellum of, 181 
 development of, 182 
 lower extremity of, 181 
 nutrient canal of, 180 
 shaft of, 179 
 structure of, 182 
 surface form of, 183 
 surgical anatomy of, 183 
 trochlea of, 181 
 tuberosities of, 179 
 upper extremity of, 177 
 Humors of eye, 1128 
 Hunter's canal, 521, 698 
 Huschke, foramen of, 92 
 Hyaline cartilage, 259 
 Hyaloid canal of eye, 1129 
 
 membrane of eye, 1129 
 Hydatids of Morgagni, 1469 
 non-pedunculated, 1469 
 pedunculated, 1469 
 Hymen, 1481 
 
 imperforate, 1481 
 Hyo-epiglottic ligament, 1365 
 -glossus muscle, 397 
 -thyroid membrane, 1366 
 Hyoid artery of lingual, 603 
 of superior thyroid, 602 
 bone, 153 
 
 attachment of muscles to, 
 
 154 
 basi-hyal of, 153 
 body of, 153 
 borders of, 154 
 surfaces of, 153 
 cornua of, greater, 154 
 
 lesser, 154 
 development of, 154 
 region, infra-, muscles of, 
 391 
 supra-, muscles of, 393 
 surface form of, 154 
 surgical anatomy of, 154 
 tubercle of, 153 
 
INDEX 
 
 1569 
 
 Hvparterial branch of bronchus, 
 
 1377 
 Hypochondriac region, 1233 
 Hypogastric artery, 683 
 in fcEtus, 684 
 
 fold, 1519 
 
 nerve, 999 
 
 plexus, 1080, 1085 
 
 region, 1233 
 
 vein, 760 
 JHvpoglossal nerve, 1064 
 
 branches of, 1065, 1066 
 surgical anatomy of, 1066 
 
 nucleus, 949 
 JHvrtl, exsanguinated renal zone 
 
 of, 679, 1423 
 
 Ileo-appendicular fold, 1263 
 fossa, 1263 
 -caecal fossa, 1263 
 inferior, 1263 
 superior, 1262 
 valve, 1308 
 
 frajnulum of, 1308 
 -colic arterv, 675 
 fold, 1262 
 fossa, 1262 
 Ileum, 1289 
 
 Iliac arteries, circumflex, deep, 
 697 
 superficial, 704 
 common, 681 
 branches of, 682 
 compression of, 683 
 peculiarities of, 682 
 surface marking of, 682 
 surgical anatomy of, 682 
 external, 694 
 
 branches of, 696 
 relations of, 694 
 surface marking of, 682, 
 
 695 
 surgical anatomy of, 695 
 internal, 683 
 
 branches of, 686 
 peculiarities of, 685 
 relations of, 683 
 surface form of, 694 
 surgical anatomy of, 685, 
 694 
 bursa, subtendinous, 331 
 fascia, 508 
 fossa, 209 
 furrow, 220 
 glands, 797 
 common, 799 
 external, 797 
 internal, 799 
 Tierve, 999 
 
 portion of fascia lata, 1528 
 region, muscles of, 508 
 
 surgical anatomy of, 511 
 vein, circumflex, deep, 759 
 common, 764 
 
 peculiarities of, 764 
 external, 759 
 internal, 760 
 Tliacus muscle, 510 
 
 relations of, 511 
 Ilio-capsularis muscle, 511 
 -coccygeus muscle, 454 
 -costalis muscle, 419 
 -femoral ligament, 328 
 -hypogastric nerve, 999 
 -inguinal nerve, 999 
 -lumbar artery, 693 
 ligament, 291 
 veins, 764 
 
 Ilio-pectineal bursa, 330 
 eminence, 210, 213 
 ligament, 508 
 line, 209 
 -pelvic glands, 797 
 -sciatic notch, 210 
 -tibial band, 234, 514 
 -trochanteric ligament, 329 
 Ilium, 207 
 
 borders of, 210 
 crest of, 210 
 dorsum of, 207 
 ])rocesses of, 210 
 spine of, 210 
 surfaces of, 207, 208 
 venter of, 209 
 Impar ganglion, 1068 
 Imperforate hj^men, 14S1 
 Impression, deltoid, 179 
 
 gastric, 1333 
 Incisive fossa, 106, 123, 139 
 Incisor canal, 110 
 crest, 111 
 foramina, 110 
 nerve, 1039 
 teeth, 1196 
 Incisura cardiaca, 1392 
 inter-arytaenoidea, 1368 
 marsupialis, 926 
 pancreatis, 1348 
 semilunaris, 926 
 Incremental lines of dentine, 
 
 1203 
 Incus, 1159 
 body of, 1159 
 ligaments of, 1161 
 processes of, 1159 
 Infantile hernia, 1523 
 Inferior acromio-clavicular liga- 
 ment, 299 
 alveolar artery, 614 
 branch of superior cervical 
 
 ganglion, 1074 
 calcaneo-scaphoid ligament, 
 354 
 surgical anatomy of, 354 
 cardiac nerve, 1077 
 carotid triangle, 616 
 central nucleus, 949 
 cerebral veins, 735 
 cervical ganglion, 1077 
 constrictor muscle, 400 
 
 relations of, 401 
 coronary artery of lip, 607 
 dental artery, 614 
 canal, 124 
 foramen, 124 
 nerve, 1039 
 ethmoidal turbinate bone, 101 
 external frontal artery, 628 
 frontal convolution, 873 
 gemellus muscle, 527 
 gluteal artery, 693 
 line, 208 
 nerve, 1011 
 hsemorrhoidal artery, 690 
 nerve, 1011 
 plexus, 1086 
 veins, 760 
 internal frontal arteries, 627 
 labial artery, 607 
 lachrymal gland, 1141 
 laryngeal artery, 641 
 
 veins, 751 
 lateral angle, 63 
 lingualis muscle, 399 
 longitudinal fasciculus, 918 
 
 sinus, 738 
 maxilla bone, 122 
 
 horizontal portion of, 122 
 surfaces of, 122 
 
 99 
 
 Inferior maxillary bone, articula- 
 tions of, 125 
 attachment of muscles to, 
 
 125 
 development of, 125 
 horizontal portion of, bor- 
 ders of, 124 
 perpendicular portion of, 
 124 
 borders of, 124 
 processes of, 125 
 surfaces of, 124 
 nerve, 1036 
 meatus of nose, 145 
 medullary velum, 943 
 mesenteric artery, 677 
 plexus, 1085 
 vein, 768 
 nuchal line, 72 
 obliquus oculi rrmscle, 374 
 occipital convolution, 877 
 fossa}, 133 
 sulcus, 877 
 ophthalmic vein, 741 
 orbito-palpebral sulcus, 1137 
 palatine artery, 606 
 pancreatico-duodenal artery, 
 
 675 
 parietal convolution, 876 
 petrosal sinus, 742 
 phrenic arteries, 680 
 
 veins, 767 
 post-central sulcus, 875 
 profunda artery, 656 
 pubic ligament, 296 
 pudendal nerve, 1011 
 pyloric artery, 673 
 radio-ulnar articulation, 315 
 ramus of ischium, 212 
 
 of pubis, 213 
 rectus oculi muscle, 373 
 renal artery, 1423 
 rhomboid fossa, 840 
 sacro-sciatic foramen, 294 
 semilunar lobe of cerebellum, 
 
 931 
 stephanion, 76 
 
 superficial cerebellar veins, 736 
 tarsal arch, 623 
 temporal convolution, 877 
 
 sulcus, 870 
 thyroid artery, 641 
 
 veins, 751 
 transverse ligament, 302 
 triangle of fourth ventricle, 945 
 turbinated bone, 119 
 
 articulations of, 120 
 borders of, 120 
 development of, 120 
 processes of, 120 
 surfaces of, 120 
 crest, 107, 117 
 vena cava, 764 
 
 vermiform process of cerebel- 
 lum, 929 
 vesical artery, 686 
 
 plexus, 762 
 vocal cords, 1370 
 Infraclavicular plexus, 792 
 Infracostales muscle, 425 
 Infraglenoid margin of tibia, 234 
 
 tubercle, 174 
 Infrahyoid artery, 602 
 
 region, muscles of, 391 
 Infralaryngeal glands, 787 
 Inframandibular nerve, 1049 
 Inframaxillarv glands, 782 
 
 nerve, 1049 
 Infraorbital arterv, 615 
 canal, 107, 140 
 foramen, 106, 140 
 
1570 
 
 INDEX 
 
 Infraorbital groove, 107, 141 
 
 nerves, plexus of, 1049 
 Infrapatellar bursa, 340 
 Infraspinatus bursa, 315 
 muscle, 472 
 bursa of, 473 
 Infraspinous fascia, 472 
 
 fossa, 172 
 Infrasternal depression, 163 
 Infratemporal crest, 95 
 
 fossa, 138 
 Infratrochlear nerve, 1031 
 Infundibula of kidney, 1415 
 Infundibular artery, 590 
 Infundibuliform fascia, 446, 1464 
 Inf undibulo-pelvic ligament, 1490 
 Infundibulum of brain, 882 
 of ethmoid, 101 
 of Fallopian tube, 1497 
 of heart, 569 
 Ingrassias, processes of, 96 
 Inguinal canal, 448, 1517 
 fossa, 1248 
 
 external, 1520 
 internal, 1520 
 middle, 1520 
 hernia, 1520 
 direct, 1523 
 
 incomplete, 1524 
 oblique, 1517, 1520 
 lymphatic gland, deep, 795 
 superficial, 793 
 
 surgical anatomy of, 
 794 
 region, 1233 
 Inion, 71 
 
 Inlet of pelvis, 217 
 Innominate artery, 593 
 branches of, 594 
 peculiarities of, 594 
 relations of, 593 
 surgical anatomy of, 594 
 bone, 207 
 vein, 750 
 left, 750 
 
 peculiarities of, 750 
 right, 750 
 Inosculation of arteries, 583 
 Insertion of muscles, 363 
 Inspiration, muscles of, 432 
 ■ Insula, 867, 878 
 opercula of, 878 
 Integument of scrotum, 1463 
 Inter-alveolar cell islets, 1352 
 Interarticular chondro-sternal 
 ligament, 288 
 fibro-cartilage, 281, 298, 300 
 
 triangular, 315 
 furrow, 565 
 ligament, 284, 329 
 septum, 565 
 
 stemo-costal ligament, 288 
 Inter-brain, 901 
 Intercarotid body, 600 
 Intercavernous sinus, 742 
 Intercerebral fibres of optic com- 
 missure, 1021 
 Intercellular biliary passages, 
 
 1341 
 Interchondral articulations, 289 
 ligament, external, 290 
 internal, 290 
 Interclaviculer ligament, 298 
 Intercolumnar fascia, 436, 1463, 
 1514 
 fibres, 436 
 Intercondyloid notch, 225 
 Intercostal arteries, 667 
 anterior, 644 
 collateral, 668 
 superior, 645 
 
 Intercostal arteries, surgical ana- 
 tomy of, 668 
 fascia, 424 
 glands, 810 
 muscles, 425 
 
 external, 425 
 relations of, 425 
 
 internal, 425 
 relations of, 425 
 nerves, 993 
 
 abdominal, 996 
 
 first, 995 
 
 pectoral, 995 
 
 surgical anatomy of, 996 
 space, 155, 160 
 veins, 752 
 
 anterior, 752 
 
 posterior, 752 
 
 superior, left, 752 
 right, 752 
 Intercosto-humeral nerve, 995 
 Interglobular spaces of Czermak, 
 
 1202 
 Interlobar arteries, 1423 
 biliary plexus, 1338 
 ducts, 1341 
 Inter-maxillary bone, 110 
 
 region, muscles of, 378 
 
 suture, 139 
 Intermediate crusta nerve path, 
 
 960 
 glands, 791 
 zone of kidney, 1416 
 Internal abdominal ring, 446, 
 
 1518 
 angular process, 80, 140 
 annular ligament, 542 
 anterior thoracic nerve, 984 
 arcuate ligament, 427 
 auditory artery, 639 
 
 meatus, 133 
 bicipital ridge, 179 
 branches of superior cervical 
 
 ganglion, 1076 
 calcaneal nerve, 1015 
 calcanean artery, 719 
 calcaneo-astragaloid ligament, 
 352 
 
 -cuboid ligament, 353 
 
 -scaphoid ligament, 354 
 capsule of brain, fibres of, 892 
 carotid artery, 619 
 
 foramen, 88 
 
 plexus, 1073 
 circumflex artery of thigh, 705 
 condyle of femur, 226 
 crucial Ugament, 337 
 cutaneous nerve, 986, 1004 
 ear, 1163 
 epicondyle, 181 
 epigastric artery, 696 
 femoral region, muscles of, 519 
 geniculate body, 904, 912 
 iliac arterv, 683 
 
 glands, '799 
 
 vein, 760 
 inguinal hernia, 1520 
 interchondral ligament, 290 
 intercostal muscle, 425 
 jugular glands, 786 
 
 vein, 729 
 bulb of, 729 
 lateral hgament, 280, 310 
 malleolar artery, 719 
 malleolus, 235 
 mammary artery, 643 
 
 vein, 750 
 maxillary artery, 612 
 
 Ivmphatic glands, 782 
 
 vein, 727 
 oblique line, 123 
 
 Internal oblique mu&cles, 437,, 
 1516 
 occipital crest, 74, 113 
 
 protuberance, 73 
 orbital arteries, 627 
 convolution, 873 
 OS, 1488 
 
 palpebral arteries, 623 
 parieto-occipital sulcus, 867,. 
 
 870 
 plantar artery, 719 
 
 nerve, 1015 
 popliteal nerve, 1014 
 pterygoid muscle, 383 
 relations of, 384 
 ner\^e, 1037 
 plate, 96 
 pudic artery in female, 692 
 in male, 689 
 vein, 760 
 rectus oculi muscle, 373 
 respiratory nerve of Bell, 974 
 saphenous nerve, 1005 
 
 vein, 756 
 semilunar fibrocartilage, 338 
 spermatic fascia, 446 
 sphincter ani muscle, 451 
 structure of cerebellum, 931 
 supracondylar ridge, 180 
 tarsal ligament, 370 
 tuberosity of tibia, 233 
 wall of tympanum, 1152 
 Intemasal suture, 139 
 Intemeural articulations, 272 
 Internodia or phalanges, 204 
 Interolivary fillet, 909, 949 
 Interossci muscles of foot, 548 
 dorsal, 548 
 plantar, 548 
 of hand, 499 
 Interosseous artery*' of ulnar, 662* 
 anterior, 662 
 posterior, 663 
 arteries, dorsal, 659, 715 
 
 palmar, 660 
 ligament, 286 
 nerve, anterior, 987 
 
 posterior, 991 
 sacro-iliac ligament, 292 
 veins of forearm, 747 
 Interpalpebral slit, 1138 
 Interparietal suture, 127 
 Interpeduncular ganglion, 910 
 
 space of brain, 882, 906 
 Interpleural space, 1387 
 Interpubic disk, 296 
 Intersigmoid fossa, 1312 
 Interspinales muscle, 421 
 Interspinous ligaments, 273 
 
 venous plexus, 732 
 Intersternal ligament, anterior, 
 290 
 posterior, 290 
 Intertransversales muscle, 422 
 laterales muscle, 422 
 mediales muscle, 422 
 Intertransverse ligaments, 273.. 
 
 295 
 Intertrochanteric line, anterior,. 
 223 
 posterior, 223 
 Intertubular cell-masses, 1352 
 
 tissue, 1203 
 Interventricular grooves, 568 
 of heart, 565 
 septum, 569 
 Intervertebral disks, 270 
 structure of, 271 
 fibro-cartilages, 270 
 
 structure of, 271 
 foramina, 49 
 
INDEX 
 
 1571 
 
 Intervertebral grooves, 49 
 notches, 49 
 substances, 270 
 
 structure of, 271 
 veins, 755 
 Intestinal glands, 1295, 1319 
 Intestine, large, 1299 
 
 areolar coat of, 1318 
 arteries of, 1320 
 flexure of, hepatic, 1300 
 sigmoid, 1300 
 splenic, 1300 
 lymphatic glands of, 808, 
 1321 
 vessels of, 809 
 mucous membrane of, 1318 
 muscular coat of, 1317 
 serous coat of, 1316 
 structure of, 1316 
 submucous coat of, 1318 
 veins of, 1321 
 innervation of, 1323 
 movements of, 1322 
 small, 1282 
 
 areolar coat of, 1290 
 arteries of, 1296 
 lymphatic glands of, 807, 
 1297 
 vessels of, 808 
 mucous membrane of, 1290 
 muscular coat of, 1290 
 nerves of, 1299 
 serous coat of, 1290 
 structure of, 1290 
 submucous coat of, 1290 
 veins of, 1297 
 villi of, 1292 
 surface form of, 1323 
 surgical anatomy of, 1324 
 Intestinum tenue mesenteriale, 
 
 1289 
 Intracapsular fracture, 229 
 Intracartilaginous ossification, 43 
 Intraepithelial plexus, 1111 
 Intralobular veins, 767 
 Intramembranous ossification, 43 
 Intraparietal sulcus of Turner, 
 
 875 
 Intrathyroid cartilage, 1363 
 Intrinsic muscles of tongue, 398 
 Intumescentia ganglioformis, 
 
 1045 
 Involuntarv muscles, 361 
 Iris, 1117 "^ 
 
 arteries of, 1120 
 muscular fibres of, 1118 
 nerves of, 1120 
 pigment of, 1119 
 stroma of, 1118 
 structure of, 1118 
 Irregular bones, 34 
 Ischiatic lymphatic glands, 797 
 Ischio-capsular ligament, 328 
 -gluteal bursa, 331 
 -rectal fascia, 454, 1546 
 fossa, 1536 
 
 region, muscles of, 449 
 surgical anatomy of, 1535 
 Ischium, 210 
 body of, 210 
 ramus of, ascending, 212 
 
 descending, 211 
 spine of, 211 
 tuberosity of, 211 
 Island of^Langerhans, 1352 
 
 of Reil, 867, 878 
 Isthmus, aortic, 591 
 
 of auditory canal, 1148 
 cerebri, 906 
 of Fallopian tube, 1497 
 of fauces, 1212 
 
 Isthmus, faucium, 1194 
 of pharynx, 1221 
 of prostate gland, 1451 
 rhombencephali, 857 
 of thyroid gland, 1403 
 
 Iter a tertio ad quartum ven- 
 triculum, 903, 912 
 chordse anterius, 1152 
 posterius, 1151 
 
 Ivory of teeth, 1202 
 
 Jacob's membrane, 1126 
 Jacobson, cartilage of, 1097 
 eminence of, 1100 
 nerve, 1056 
 
 canal for, 90 
 organ of, rudimentary, 1100 
 Jaw, angle of, 124 
 bones, upper, 105 
 lower, articulations of, 280 
 changes produced in, by age, 
 125 
 upper. See Maxillary Bone. 
 Jejunum, 1289 
 Joints. See Articulations. 
 Jugular foramen, 73, 133 
 fossa, 91 
 ganglion, 1056 
 glands, internal, 786 
 lymphatic trunk, 787 
 nerve, 1073 
 process, 73 
 tubercle, 74 
 vein, anterior, 728 
 external, 728 
 
 sinus of, 728 
 internal. 729 
 bulb of, 729 
 sinus of, 729 
 
 surgical anatomy of, 732 
 posterior external, 728 
 Juxta-aortic glands, left, 800 
 right, 800 
 -cervical lymphatic knot, 803 
 
 Kerkhinq, valves of, 1291 
 Key and Retzius, foramina of, 
 
 834, 853 
 Kidneys, 1411 
 
 abnormalities of, 1424 
 areas of, 1414 
 arteries of, 1422 
 calices of, 1415 
 capsule of, fatty, 1411 
 
 true, 1415 
 connective tissue of, 1424 
 cortical substance of, 1416 
 ducts of, 1420 
 hilum of, 1415 
 infundibula of, 1415 
 intermediate zone of, 1416 
 lymphatic vessels of, 804, 1424 
 Malpighian bodies of, 1417 
 
 capsule, 1417 
 
 tuft of, 1417 
 medullary substance of, 1416 
 minute anatomy of, 1417 
 nerves of, 1424 
 papillffi of, 1417 
 pelvis of, 1415 
 pyramids of Ferrein, 1417 
 
 of Malpighi, 1416 
 sinus of, 141.5 
 structure of, 1415 
 surface form of, 1425 
 
 Kidneys, surfaces of, 1412 
 
 surgical anatomy of, 1425 
 
 tubuli uriniferi, 1418 
 
 variations of, 1424 
 
 veins of, 1424 
 Knee, bursae of, 340 
 
 -cap, 230 
 
 -joint, surface form of, 343 
 surgical anatomy of, 343 
 
 ligaments of, 334 
 KoUiker, membrane of, 1175 
 Krause, ellipsoid of, 1127 
 
 end-bulbs of, 827 
 
 Labia pudendi majora, 1477 
 
 minora, 1478 
 Labial arterv, inferior, 607 
 glands, 1194 
 nerves, 1034 
 Labii cerebri, 885 
 Labium tympanicum, 1172 
 
 vestibulare, 1172 
 Labyrinth, 1163 
 arteries of, 1176 
 membranous, 1169 
 nerves of, 1176 
 osseous, 1164 
 veins of, 1176 
 Lachrymal apparatus, 1141 
 artery, 623 
 
 peculiarities of, 623 
 bone, 112 
 
 articulations of, 113 
 attachment of muscles to, 
 
 113 
 borders of, 113 
 crests of, 141 
 development of, 113 
 lesser, 113 
 surfaces of, 113 
 canaliculi, 1142 
 canals, 1142 
 caruncle, 1142 
 crest, 113 
 fossa, 81 
 glands, 1141 
 
 structure of, 1141 
 surface form of, 1143 
 surgical anatomy of, 1144 
 groove, 107, 109, 141, 143 
 nerve, 1028 
 notch, 107 
 papilla, 1138, 1142 
 process of inferior turbinated, 
 
 120 
 sac, 1142 
 
 structure of, 1142 
 surface form of, 1143 
 surgical anatomy of, 1144 
 sulcus, 113 
 tubercle, 109 
 Lactiferous duct, 1507 
 Lacuna magna, 1444 
 Lacunae, 1110 
 of bone, 38 
 Howship's, 38 
 Lacus lacrimalis, 1138 
 Lagena, 1172 
 
 Lalouette, pyramid of, 1403 
 Lambda, 129 
 
 Lambdoid suture, 75, 7S, 128 
 Lamella of bone, articular, 259 
 Lamina basalis, 1114 
 of cerebellum, 927 
 cinerea, 882 
 of cornea, 1109 
 cribrosa, 89 
 cribriform, 1108 
 
1572 
 
 INDEX 
 
 Lamina, cribriform, of sclerotic, 
 1108 
 dental, 1205 
 
 of ethmoid, horizontal, 99 
 perpendicular, 100 
 vertical, 100 
 fusca, 1108 
 
 posterior perforated, 910 
 reticularis, 1175 
 septi pellucidi, 889 
 spiralis ossea of cochlea 1167 
 suprachorioidea, 1112 
 terminalis, 882 
 vasculosa, 1112 
 of vertebra, 34 
 Lancisi, nerve of, 887 
 Landzert, fossa of, 1262 
 Langer, foramen of, 464, 646, 791 
 
 lines of cleavage of, 1180 
 Langerhans, centro-acinar cells 
 of, 1352 
 islands of, 1352 
 Lantermann, segments of, 823 
 Large, deep petrosal nerve, 1034, 
 1073 
 intestine, 1299 
 palatine nerve, 1035 
 superficial petrosal nerve, 1034 
 Laryngeal artery, inferior, 641 
 superior, 602 
 nerve, superior, 1060 
 external, 1060 
 internal, 1060 
 pouch, 1371 
 saccule, 1371 
 sinus, 1371 
 
 surface of epiglottis, 1365 
 veins, 751 
 Larynx, 1361 
 
 aperture of, superior, 1368 
 arteries of, 1375 
 cartilages of, 1362 
 cavity of, 1368 
 compartments of, 1368 
 lower, 1371 
 middle, 1369 
 glands of, 1374 
 joints of, 1366 
 ligaments of, 1366 
 lymphatics of, 782, 1375 
 membranes of, 136 
 mucous membrane of, 1374 
 muscles of, 1371 
 
 action of, 1374 
 nerves of, 1376 
 rima glottidis, 1369 
 structure of, 1365 
 veins of, 1375 
 ventricle of, 1371 
 vocal cords of, false, 1370 
 true, 1369 
 Lateral acoustic tubercle, 950 
 angle, inferior, 63 
 cell column, 846 
 column of medulla, 945 
 fillet, 885 
 
 fissures of cord, 838 
 ligament, external, 280 
 internal, 280 
 of liver, 1334 
 of wrist, 318 
 masses of atlas, 51 
 of ethmoid, 100 
 odontoid ligaments, 278 
 patellar ligaments, 335 
 region of skull, 136 
 root of eighth nerve, 1051 
 sacral artery, 693 
 
 veins, 760 
 sacro-coccygeal ligament, 295 
 sinus, 738 
 
 Lateral sinus, surgical anatomy 
 of, 739 
 spinal arteries, 638 
 surface of liver, 1329 
 thoracic region, muscles of, 
 
 468 
 tract of medulla, 945 
 ventricle of brain, 888 
 body of, 889 
 central cavity of, 889 
 cornu of, anterior, 889 
 descending, 890 
 middle, 890 
 posterior, 889 
 horn of, frontal, 889 
 occipital, 889 
 temporal, 890 
 vertebral region, muscles of, 
 408 
 Lateralis nasi artery, 607 
 Latissimus dorsi muscle, 413 
 
 bursa of, 474 
 Leaf, condyloid glands of, 795 
 
 supracondyloid glands of, 795 
 Left bronchus, 1378 
 cardiac vein, 771 
 colic artery, 678 
 
 plexus, 1085 
 coronary artery, 590 
 plexus, 1081 
 vein, 770 
 gastro-epiploic plexus, 1085 
 innominate vein, 750 
 juxta-aortic glands, 800 
 lobe of liver, 1333 
 lower azygos vein, 753 
 marginal vein, 771 
 superior intercostal vein, 752 
 upper azygos vein, 753 
 Leg, arteries of, 711 
 bones of, 230 
 fascise of, 531 
 ligaments of, 325 
 muscles of, 531 
 nerves of, 1006 
 veins of, 755 
 Lemniscus, 909, 949 
 Lens, crystalline, 1130 
 epithelium, 1130 
 fibres, 1130 
 
 suspensory ligament of, 1129 
 Lenticular ganglion, 1031 
 
 nucleus, 891 
 TiCnticulo-striate arteries, 628 
 Lesser internal cutaneous nerve, 
 986 
 omentupi, 1254 
 sacro-sciatic foramen, 294 
 
 ligament, 293 
 sciatic nerve, 1011 
 wing of sphenoid, 96 
 Levator anguli oris muscle, 377 
 scapulae muscle, 414 
 ani muscle, 451 
 
 preanal fibres of, 453 
 glanduliB thyroidese muscle, 
 
 1403 
 labii inferioris muscle, 378 
 superior alseque nasi muscle 
 
 375 
 superioris muscle, 376 
 menti muscle, 378 
 palati muscle, 403 
 palpebrae muscle, 371 
 
 superioris muscle, 372 
 prostatas, 454 
 urethrse, 454 
 Levatores costarum muscle, 426 
 Lieberkiihn, crvpts of, 1295 
 
 glands of, 1295, 1319 
 Lieno-renal ligament, 1252, 1355 
 
 Ligamenta alaria, 340 
 
 sacro-coccygea, anterior, 452 
 subflava, 272 
 
 suspensoria of mamma, 463 
 Ligamentous action of muscles, 
 
 268 
 Ligaments, 261 
 
 accessory, of atlas, 276 
 of acetabulum, transverse, 330 
 acromio-clavicular, inferior, 
 299 
 superior, 299 
 of ankle, 347 
 annular, anterior, 541 
 external, 542 
 internal, 542 
 of radius, 314 
 of stapes, 1161 
 anterior common, 269 
 longitudinal, 269 
 superior, 285 
 appendiculo-ovarian of Clado, 
 
 1304 
 arcuate, external, 427, 449 
 internal, 427 
 middle, 427 
 astragalo-scaphoid, 354 
 atlanto-axial, anterior, 274 
 
 posterior, 275 
 atlo-axoid, anterior, 274 
 
 posterior, 275 
 of axilla, suspensory, 464 
 of Bertin, 328 
 of Bigelow, 328 
 of bladder, false, 1436 
 
 true, 1436 
 broad, of liver, 1333 
 
 of uterus, 1490 
 calcaneo-astragaloid, external, 
 352 
 internal, 352 
 posterior, 352 
 -cuboid, internal, 353 
 long, 353 
 short, 353 
 superior, 353 
 -navicular, 353 
 -scaphoid, external, 353 
 inferior, 354 
 internal, 354 
 superior, 353 
 capsular. &ee Individual Joints, 
 carpo-metacarpal, 313 
 of carpus, 319 
 central, of spinal cord, 835 
 check, 278, 1105 
 chondro-sternal, anterior, 288 
 interarticular, 288 
 posterior, 288 
 -xiphoid, anterior, 288 
 posterior, 288 
 ciliarv, 1116 
 of Cloquet, 1466 
 coccvgeal, 833 
 Colles', 437 
 conoid, 300 
 of Cooper, 437, 448 
 coraco-acromial, 301 
 -clavicular, 300 
 -humeral, 304 
 coracoid, 302 
 costo-clavicular, 298 
 -coracoid, 467 
 -transverse, long, 285 
 middle, 286 
 posterior, 286 
 -vertebral, anterior, 284 
 -xiphoid, anterior, 288 
 posterior, 288 
 cotyloid, 329 
 crico-arytenoid, 1367 
 
INDEX 
 
 1573 
 
 Ligaments, crico-tracheal, 1368 
 cruciform, 275 
 deltoid, 348 
 dentate, 835 
 
 dorsal. iSee Individual Joints, 
 duodeno-mesocolic, 1261 
 
 -renal, 1255 
 of elbow, anterior, 309 
 
 posterior, 309 
 femoral, 515 
 of fingers, 322 
 
 superficial, transverse, 494 
 Flood's, 304 
 of foot, 547 
 
 fundiform of Retzius, 541 
 gastro-splenic, 1256 
 Gimbernat's, 437, 1515 
 gleno-humeral, 305 
 glenoid, 175, 305 
 
 of Cruveilhier, 359 
 glosso-epiglottic, 1366 
 of hand, 319 
 of Helmholtz, 1160 
 of Henle, 438, 442 
 hepato-colic, 1255 
 
 -duodenal, 1255 
 
 -gastric, 1254 
 of Hesselbach, 438, 442, 1517 
 of Hev, 515 
 of hip, 326 
 hyo-epiglottic, 1365 
 ilio-femoral, 328 
 
 -lumbar, 291 
 
 -pectineal, 508 
 
 -trochanteric, 329 
 of incus, 1161 
 infundibulo-pelvic, 1490 
 interarticular, 284, 329 
 interchondral, external, 290 
 
 internal, 290 
 interclavicular, 298 
 interosseous. See Individual 
 
 joints, 
 interspinous, 273 
 intersternal, anterior, 290 
 
 posterior, 290 
 intertransverse, 273, 295 
 intervertebral, 270 
 ischio-capsular, 328 
 of jaw, 280 
 of knee, 334 
 
 alar, 340 
 
 anterior, 345 
 
 coronary, 340 
 
 crucial, 337 
 
 mucosum, 334 
 
 posterior, 335 
 
 transverse, 340 
 of larynx, 1366 
 lateral. See Individual Joints. 
 lieno-renal, 1252, 1355 
 of liver, 1333 
 
 coronary, 1334 
 
 falciform, 1333 
 
 lateral, of, 1334 
 left, 1334 
 right, 1.334 
 
 round, 1334 
 
 suspensory, 1333 
 lumbo-sacral, 291 
 of Luschka, 558 
 of malleus, 1160 
 metacarpal, 324 
 metacarpo-phalangeal, 324 
 metatarsal, 359 
 metatarso-pharyngeal. 359 
 nuchse, 273, 413 
 oblique, 314 
 obturator, 296 
 
 occipito-atlantal, anterior, 276 
 posterior, 276 
 
 Ligaments, occipito-axial, 278 
 odontoid, lateral, 278 
 
 middle, 279 
 orbicular, 314 
 orbito-tarsal, 1139 
 of ossicula, 1160 
 palpebral, 1139 
 of patella, 335 
 pelvis, falciform, 293 
 
 transverse, 459 
 of penis, 1458 
 
 suspensory, 437 
 perineal, transverse, 459 
 of peritoneum, 1254 
 of phalanges of foot, 359 
 
 of hand, 325 
 phreno-colic, 1259 
 -pericardial, 559 
 plantar, long, 353 
 
 short, 353 
 posterior common, 270 
 
 longitudinal, 270 
 Poupart's, 436, 1515 
 pterygo-mandibular, 380 
 
 -maxillary, 380 
 pubic, anterior, 296 
 inferior, 296 
 posterior, 296 
 superior, 296 
 pubo-capsular, 328 
 -femoral, 328 
 -prostatic, 1435, 1451 
 -vesical, 1435 
 radio-carpal, 319 
 -ulnar, annular, 314 
 anterior, 315 
 oblique, 314 
 orbicular, 314 
 round, 314 
 posterior, 315 
 rhomboid, 298 
 
 sacro-coccygeal, anterior, 294 
 lateral, 295 
 posterior, 294 
 -iliac, anterior, 292 
 interosseous, 292 
 long, 292 
 obUque, 292 
 posterior, 292 
 short, 292 
 -sciatic, anterior, 293 
 great, 292 
 lesser, 293 
 posterior, 292 
 -uterine, 1490 
 -vertebral, 291 
 of scapula, 301 
 Schlemm's, 305 
 of shoulder, 303 
 spino-glenoid, 302 
 spiral, of cochlea, 1172 
 spleno-phrenic, 1256 
 sterno-clavicular, anterior, 298 
 posterior, 298 
 -costal, anterior, 288 
 interarticular, 288 
 posterior, 288 
 -costo pericardial, 559 
 -pericardiac, 558 
 of stapes, 1161 
 of sternum, 290 
 stylo-hyoid, 394 
 
 -mandibular, 281, 388 
 -maxillary, 281 
 subpubic, 296 
 suprascapular, 302 
 supraspinous, 273 
 suspensory, of clitoris, 437 
 of eye, 1105 
 of incus, 1161 
 of lens, 1129 
 
 Ligaments, suspensory, of liver, 
 
 1333 
 
 of mamma, 463 
 
 of ovary, 1501 
 
 of penis, 437 
 
 of Treitz, 1286 
 sutural, 259 
 synovial, 262 
 tarsal, external, 370 
 
 internal, 370 
 of thumb, 321 
 thyro-epiglottic, 1367 
 
 -hyoid, 1366 
 tibio-tarsal, anterior, 347 
 
 posterior, 347 
 transverse, of atlas, 275 
 
 humeral, 305 
 
 inferior, 302 
 
 of knee, 340 
 
 superior, of scapula, 302 
 trapezoid, 300 
 tympano-malleolar, 1156 
 utero-sacral, 1490 
 of uterus, 1489 
 
 round, 1491 
 of vertebra;, 270 
 vertebro-pericardial, 558 
 
 -pleural, 1385 
 vesico-uterine, 1490 
 of Winslow, 335 
 of Wrisberg, 339 
 of wrist, 318 
 
 anterior, 318 
 
 dorsal, 318 
 
 lateral, external, 318 
 internal, 318 
 
 posterior, 318 
 
 volar, 318 
 xipho-pericardial, 559 
 Y-, 328 
 of Zinn, 373 
 Ligamentum arcuatum exter- 
 num, 427, 449 
 
 internum, 427 
 arteriosurn, 587 
 conjugale, 284 
 corniculopharyngpum, 1.368 
 crico-pharyngeum, 1368 
 denticulatum, 835 
 epididymidis, 1469 
 hepatoduodenale, 1250 
 latum pulmonalis, 1385 
 mucosum, 340 
 nuchse, 273, 413 
 patella;, 335 
 
 posticum Winslowii, 335 
 pulmonale, 1385 
 spirale, 1172 
 suspensorium, 279 
 teres, 329 
 ventriculare, 1366 
 Light stimuli, path of, 1127 
 Ligula, 944 
 Limbic lobe, 878 
 
 convolutions of, 879 
 Limbus alveolaris, 124 
 laminae spiralis, 1172 
 Limen insulse, 878 
 Limiting sulcus of Reil, 867 
 Linea alba, 444 
 aspera, 224 
 
 external lip of, 224 
 
 internal lip of, 224 
 quadrati, 224 
 splendens, 835 
 Linse semilunares, 445 
 
 transverse, of abdomen, 445 
 Line, gluteal, anterior, 207 
 
 inferior, 208 
 
 posterior, 207 
 ilio-pectineal, 209 
 
1574 
 
 INDEX 
 
 Line, nuchal, inferior, 72 
 
 superior, 72 
 temporal, 76, 80 
 Lingual artery, 603 
 
 branches of, 603 
 
 deep, 604 
 
 relations of, 603 
 
 surgical anatomy of, 604 
 bone, 153 
 gyrus, 877 
 nerve, 1038, 1057 
 
 branches of, 1038 
 region, muscles of, 396 
 
 dissection of, 396 
 tonsil, 1088 
 veins, 729 
 Lingualis muscle, inferior, 399 
 
 superior, 399 
 
 transverse, 399 
 
 vertical, 399 
 Lingula, 93, 280, 928, 944 
 
 pulmonis, 1392 
 Lips, 1194 
 
 surgical anatomy of, 1224 
 Liquor Cotunnii, 1164 
 Lissauer, tract of, 843 
 Little brain, 926 
 Littr6, glands of, 1444 
 Liver, 1326 
 
 abnormalities of, 1335 
 accessory, 1335 
 areolar coat of, 1337 
 arteries of, 1336 
 development of, 1243 
 ducts of, 1341 
 
 excretory apparatus of, 1342 
 fibrous coat of, 1337 
 fissures of, 1330 
 hepatic arteries, 1336 
 
 ducts, 1336 
 
 vein, 1336 
 figaments of, 1333 
 lobes of, 1332 
 lobules of, 1337 
 lymphatics of, 80S, 1341 
 margins of, 1330 
 movabihty of, 1334 
 nerves of, 1342 
 portal vein, 1336 
 serous coat of, 1337 
 structure of, 1337 
 support of, 1334 
 surface relations of, 1346 
 surfaces of, 1327, 1329 
 surgical anatomy of, 1346 
 veins of, 1336 
 Lobe or lobes, biventral, 931 
 of brain, 872 
 central, 878 
 
 of cerebellum, 926, 928, 930, 931 
 crescentic, anterior, 928 
 
 posterior, 928 
 cuneate, 877 
 •digastric, 931 
 frontal, 872, 884 
 of kidney, 1415 
 limbic, 878 
 of liver, 1332 
 of lungs, 1392 
 occipital, 876 
 olfactory, 880 
 orbital, 874 
 parietal, 875 
 post-central, 878 
 pre-central, 878 
 of prostate gland, 1451 
 quadrate, 876 
 semilunar, inferior, 931 
 slender, 931 
 temporal, 877, 885 
 temporo-sphenoidal, 877 
 
 Lobe or lobes, of testicle, 1472 
 of thymus gland, 1407 
 of thyroid gland, 1403 
 Lobule of ear, 1145 
 of kidney, 1415 
 of liver, 1337 
 of lungs, 1395 
 of mamma, 1506 
 Lobuli testis, 1472 
 Lobulus centralis, 928 
 Locus ca>ruleus, 945 
 Long bones, 33 
 
 calcaneo-cuboid ligament, 353 
 ciliary arteries, 625 
 
 nerves, 1030 
 plantar ligament, 353 
 sacro-iliac ligament, 292 
 saphenous nerve, 1005 
 
 vein, 756 
 scrotal nerve, 1011 
 subscapular nerve, 984 
 thoracic artery, 651 
 nerve, 983 
 vein, 748 
 Longissimus dorsi muscle, 419 
 Longitudinal fasciculus, inferior, 
 918 
 superior, 918 
 fibres of cord, 841 
 of pons, 923 
 dorsal, 924 
 deep, 924 
 middle, 924 
 superficial, 924 
 ventral, 924 
 deep, 924 
 fissure of cerebrum, 865, 882 
 sinus, inferior, 738 
 superior, 78, 130, 736 
 Longus capitis muscle, 406 
 
 colli muscle, 407 
 Looped tubes of Henle, 1419 
 Louis, angle of, 157 
 Lower deep cervical glands, 787 
 extremity, arteries of, 697 
 articulations of, 325 
 bones of, 206 
 fasciae of, 507 
 ligaments of, 325 
 lymphatic vessels of, 797 
 deep, 797 
 superficial, 797 
 muscles of, 507 
 
 surface form of, 549 
 surgical anatomy of, 551 
 nerves of, 997 
 veins of, 755 
 deep, 758 
 superficial, 756 
 jaw, articulation of, 280 
 subscapular nerve, 984 
 visual centre, 1022 
 Ludovic, angle of, 157 
 Lumbar arteries, 680 
 fascia, 416 
 ganglia, 1085 
 glands, 799 
 nerves, 997 
 
 divisions of, anterior, 998 
 
 posterior. 997 
 roots of, 997 
 plexus, 998 
 branches, 999 
 surgical anatomy of, 1017 
 portion of gangliated cord, 
 
 1079 
 region, 1233 
 veins, 765 
 
 ascending, 753, 765 
 right, 752 
 vertebrae, 56 
 
 Lumbar vertebrae, body of, 56 
 
 fifth, 57 
 
 laminai of, 56 
 
 pedicles of, 56 
 
 processes of, 57 
 Lumbo-iliac ligament, 291 
 -sacral ligament, 291 
 
 plexus, 998 
 Lumbricales muscle, foot, -546 
 
 hand, 499 
 Lungs, 1390 
 
 air-cells of, 1396 
 apex of, 1390 
 arteries of, 1396 
 base of. 1391 
 borders of, 1392 
 bronchus of, 1395 
 capillaries, 1396 
 color of, 1394 
 fissures of, 1392 
 foetal, 1394 
 lobes of, 1392 
 lobules of, 1395 
 lymphatics of, 1396 
 nerves of, 1397 
 parenchyma of, 1395 
 root of, 1394 
 serous coat of, 1394 
 structure of, 1394 
 subserous areolar coat of, 1394 
 substance of, 1394 
 surface form of, 1397 
 surfaces of, 1391, 1394 
 surgical anatomy of, 1397 
 veins of, 1396 
 weight of, 1394 
 Lunula of nails, 1185 
 Luschka, gland of, 1410 
 ligament of, 558 
 vilU of, 854 
 Luys, nucleus of, 908, 910 
 Lymph canalicular system, 772 
 -capillaries, 772 
 -glands, parotid, 1215 
 -nodes, 774 
 
 perivascular, 772 
 -spaces, 772 
 Lymphatic or lymphatics, 772 
 of arm, 788 
 of arteries, 586 
 of bone, 41 
 of cord, 840 
 of cranial region, 779 
 duct, right, 778 
 
 tributaries of, 779 
 of dura mater of brain, 848 
 extracranial, 780 
 of face, 779 
 glands, 774 
 
 of abdomen, 797 
 
 abdomino-aortic, 799 
 
 along mesenteric arteries, 
 800 
 
 of anus, 809 
 
 axillarv, 790 
 
 brachial, 788 
 
 bronchial, 1380 
 
 buccal, 782- 
 
 buccinator, 782 
 
 carotid, 786 
 
 cervical, deep, 786 
 superficial, 784 
 
 of Cloquet. 795, 798 
 
 ccpliac, 800 
 
 colic, 808 
 
 condyloid of Leaf, 795 
 
 connected with ccBliac axis 
 and branches, 800 
 
 diaphragmatic, 810 
 
 epigastric, superior, 802 
 
 of face, 780 
 
INDEX 
 
 1575 
 
 IL ymphatic or lymphatics, glands, 
 
 femoral, deep, 795 
 gastric, 800 
 genial, 782 
 gluteal, 797 
 
 haemorrhoidal, middle, 799 
 of head, 780 
 hepatic, 800 
 hypogastric, 799 
 iliac, 797 
 
 common, 799 
 
 external 797 
 
 internal, 799 
 ilio-pelv-ic, 797 
 infralaryngeal, 787 
 inframaxillary, 782 
 inguinal, deep, 795 
 
 superficial, 793 
 intercostal, 810 
 intermediate, 791 
 of intestine, large, 808 
 
 small, 807 
 ischiatic, 797 
 jugular, external, 784 
 
 internal, 786 
 juxta-aortic, left, 800 
 
 right, 800 
 of lower extremity, 793 
 lumbar, 799 
 malar, 782 
 
 mammary, internal, 810 
 mastoid, 780 
 maxillary, internal, 782 
 mediastinal, anterior, Sll 
 
 posterior, 812 
 middle, of Stahr, 784 
 of neck, 784 
 obturator, 798 
 occipital, 780 
 paramammary, 813 
 parietal, 810 ' 
 parotid, 781 
 
 deep, 782 
 
 superficial, 781 
 pectoral, 790 
 of pelvis, 797 
 peritracheo-bronchial, 812 
 posterior auricular retro- 
 auricular, 780 
 post-pharyngeal, 785 
 pre-aortic, 800 
 pre-auricular, 781 
 prelaryngeal, 787 
 pretracheal, 787 
 popliteal, 795 
 rectal, 809 
 retro-aortic, 800 
 
 -crural, 798 
 
 -pharyngeal, 785 
 of Ilosenmiiller, 795 
 ■ sacral, 799 
 saphenous, external, 795 
 scapular, 790 
 splenic, 800 
 stemo-raastold, 786 
 subclavian, 791 
 submaxillary, 784 
 submental, 785 
 suboccipital, 780 
 suborbital, 782 
 subparotid, 782 
 substerno-mastoid, 786 
 supraclavicular, 787 
 supracondyloid of Leaf, 
 
 795 
 supraepitrochlear, 789 
 suprahyoid, lateral, 784 
 
 median, 785 
 supramaxillary, 782 
 ■supratrochlear, 789 
 surgical anatomy of, 774 
 
 Lymphatic or lymphatics, glands, 
 of thoracic wall, 810 
 tibial, anterior, 795 
 tracheal, 787 
 of upper extremity, 788 
 
 deep, 790 
 
 superficial, 788 
 visceral, 811 
 zygomatic, 782 
 pharyngeal ring, 1224 
 vessels of abdomen, 801 
 walls of, deep, 801 
 
 superficial, 801 
 of bile-ducts, 806 
 of bladder, 802 
 cardiac, 815 
 cerebral, 779 
 of cranial region, 782 
 of face, 782 
 of Fallopian tube, 804 
 of gluteal region, 801 
 of head, 782 
 of heart, 577 
 of intestines, large, 809 
 
 small, 808 
 of kidney, 804 
 of larynx, 782 
 of leg. 797 
 of liver, 805 
 of lower extremity, 797 
 
 deep, 797 
 
 superficial, 797 
 of lung, 815 
 meningeal, 779 
 of mouth, 782 
 of neck, 779, 787 
 of nose, interior of, 782 
 of ffisophagus, 815 
 of ovary, 804 
 of pancreas, 807 
 of pelvis, 801 
 of penis, 801 
 of perinaium, 801 
 of peritoneum, 802 
 of pharynx, 782 
 pleural, 815 
 of prostate gland, 803 
 pulmonary, 815 
 of scrotum, 801 
 of seminal vesicles, 804 
 of spleen, 807 
 of stomach, 806 
 of suprarenal capsule, 804 
 of testicle, 804 
 of thoracic trachea, 815 
 
 wall, 812 
 thymic, 815 
 of thyroid gland, 782 
 of tongue, 782 
 of umbilicus, 802 
 of upper extremity, 792 
 
 deep, 792 
 
 superficial, 792 
 of ureter, 804 
 of urethra, female, 803 
 
 male, 803 
 of uterus, 803 
 of vagina, 804 
 of vas deferens, 804 
 Lyra of fornix, 896 
 
 M 
 
 Macui.a acustica sacculi, 1170 
 
 cribrosa, 1164 
 
 lutea, 1128 
 Magnum of carpus, 199 
 Majendie, foramen of, 834, 853 
 Malar bone, 113 
 
 articulations of, 115 
 
 Malar bone, attachment of mus- 
 cles to, 115 
 borders of, 115 
 development of, 115 
 processes of, 114 
 surfaces of, 113 
 canal, 114 
 foramen, 113 
 glands, 782 
 nerve, 1032, 1049 
 process of superior maxillary, 
 109 
 Male breast, 1509 
 
 surgical anatomy of, 1509 
 organs of generation, 1447 
 perinseum, 1537 
 urethra, 1441 
 Malleolar artery, 713, 719 
 Malleolus, external, 238 
 
 internal, 235 
 Malleus, 1158 
 handle of, 1158 
 head of, 1158 
 ligaments of, 1160 
 manubrium of, 1158 
 neck of, 1158 
 processes of, 1158 
 spur of, 1158 
 Malpighi, pyramids of, 1416 
 Malpighian bodies of kidney, 
 1417 
 of spleen, 1358 
 capsule, 1417 
 layer of skin, 1182 
 tuft, 1417 
 Mamma, 1503 
 areola of, 1504 
 arteries of, 1508 
 ligament of, suspensory, 463 
 lobule of, 1506 
 lymphatics of, 1508 
 nerves of, 1508 
 variations in, 1504 
 veins of, 1508 
 Mammary artery, external, 651 
 internal, 643 
 branches of, 644 
 surgical anatomy of, 645 
 glands, 1503 
 
 description of, 1503 
 internal, 810 
 lymphatics of, 812 
 
 surgical anatomy of, 814 
 structure of, 1505 
 surgical anatomy of, 1508 
 tissue, prolongations of, 1505 
 vein, internal, 750 
 Mammillary duct, 1507 
 
 process of lumbar vertebra, 57 
 Mandible, 122 
 Mandibular artery, 614 
 fossa, 84 
 nerve, 1036 
 
 region, muscles of, 377 
 dissection of, 377 
 Manubrium of malleus, 1158 
 
 of sternum, 157 
 Marchi and Lowenthal, column 
 
 of, 843 
 Marginal artery, 500 
 convolution, 873 
 gyrus, 875 
 lobe, 857 
 tract of Spitzka and Lissauer, 
 
 843 
 vein, left, 771 
 Marrow of bone, 36 
 Marshall, vein of, oblique, 771 
 
 vestigial fold of, 561 
 Martinotti, cells of, 921 
 Masseter muscle, 381 
 
1576 
 
 INDEX 
 
 Masseteric artery, 615 
 fascia, 381 
 nerve, 1037 
 vein, 727 
 Mast-cells, 36 
 Mastoid air-cells, 1153 
 antrum, 87 
 arterv, 609, 610 
 cells,'86 
 
 foramen, 85, 138 
 fossa, 86 
 
 lymphatic glands, 780 
 nerves, 973 
 process, 86, 138 
 vein, 728 
 Masto-occipital suture, 75, 128 
 
 -parietal suture, 128 
 Matrix of nails, 1185 
 Maxillary antrum, orifice of, 145 
 artery, external, 604 
 
 internal, 612 
 bone, inferior, 122 
 
 articulation of, 125 
 attachment of muscles to, 
 
 125 
 development of, 125 
 horizontal portion of, 122 
 borders of, 124 
 surfaces of, 122 
 perpendicular portion of, 
 124 
 borders of, 124 
 processes of, 125 
 surfaces of, 124 
 superior, 105 
 
 articulations of, 112 
 attachment of, 112 
 body of, 105 
 
 surfaces of, 106 
 development of, 112 
 processes of, 109 
 hiatus, 107 
 
 l3Tnphatic glands, internal, 782 
 nerve, inferior, 1036 
 superior, 1031 
 
 branches of, 1032 
 process of inferior turbinated, 
 120 
 of malar, 115 
 of palate bone, 117 
 region, superior muscles of, 376 
 sinus, 108 
 tuberosity, 106 
 vein, internal, 727 
 McBurney's point, 1303 
 Meatus, auditory, external, 88, 
 138, 1148 
 internal, 89, 133 
 of nose, inferior, 145 
 middle, 145 
 superior, 101, 144 
 urinarius, male, 1444 
 female, 1481 
 Meckel, band of, 1160 
 cavity of, 848 
 diverticulum, 1290 
 ganglion, 1034 
 
 branches of, 1034, 1035 
 Median nerve, 986 
 branches of, 987 
 vein, 745 
 basilic, 746 
 cephalic, 746 
 cerebral, 735 
 Mediastinal arteries, 644 
 posterior, 666 
 glands, anterior, 811 
 
 posterior, 812 
 pleura, 1385 
 
 subpleural, 644 
 space, 1387 
 
 Mediastinal surface of lungs, 
 
 1391 
 Mediastinum, 1388 
 anterior, 1389 
 arteries of, 1390 
 lymphatics of, 1390 
 middle, 1389 
 posterior, 1389 
 superior, 1388 
 testis, 1471 
 veins of, 1390 
 Medio-tarsal joint, 350, 355 
 Medulla oblongata, 884, 938 
 
 fibres of, 942 
 
 fissures of, 939 
 
 formatio reticularis of, 947 
 
 funiculus cuneatus, 941 
 gracilis of, 941 
 of Rolando, 941 
 
 gray matter of, 945 
 
 lateral column of, 940 
 tract of, 945 
 
 oUvary body of, 941 
 
 pyramid of, 939 
 raph6 of, 951 
 
 restiform body of, 941 
 
 structure of, internal, 945 
 
 surfaces of, posterior, 941 
 
 veins of, 736 
 spinalis, 884 
 Medullary canal, 857 
 
 portion of suprarenal capsule, 
 1431 
 
 of thymus gland, 1408 
 spaces of bone, 45 
 substance of kidneys, 1416 
 tube, 857 
 velum, anterior, 943 
 
 inferior, 943 
 
 posterior, 943 
 
 superior, 943 
 Medullated nerve-fibres, 822 
 Medulli-spinal veins, 755 
 Meibomian glands, 1139 
 
 structure of, 1140 
 
 surgical anatomy of, 1143 
 Membrana basilaris, 1172 
 
 cochlea ductus cochlearis, 1172 
 elastica laryngis, 1367 
 flaccida of Shrapnell, 1156 
 Umitans externa of retina,1126 
 
 interna, 1122 
 nictitans, 1140 
 pupillaris, 1120 
 quadrangularis, 1366 
 sacciformis, 317 
 tectoria, 1175 
 tympani, 1155 
 
 arteries of, 1157 
 
 lymphatics of, 1158 
 
 nerves of, 1158 
 
 secundaria, 1167 
 
 structure of, 1157 
 
 veins of, 1157 
 Membrane, basilar, 1172 
 Bowman's, 1109 
 of brain, arachnoid, 851 
 
 meningeal, 847 
 of Bruch, 1114 
 of choroid, 1112 
 of Corti, 1175 
 costo-coracoid, 467 
 crico-thyroid, 1367 
 of Demours, 1110 
 of Descemet, 1110 
 fenestrated, of Henle, 585 
 hyaloid, 1129 
 hyo-thyroid, 1366 
 of Jacobs, 1126 
 of Kolliker, 1175 
 Nasmyth's, 1204 
 
 Membrane, obturator, 525 
 
 occipito-atlantal, anterior, 276- 
 posterior, 276 
 
 otolith, 1172 
 
 of Reissner, 1172 
 
 of Scarpa, 1152 
 
 of Shrapnell, 1156 
 
 of spinal cord, 832 
 arachnoid, 834 
 surgical anatomv of, 836- 
 
 sutural, 264, 847 
 
 synovial, 262 
 
 tiiyro-hyoid, 1366 
 Membranous canal of cochlea,, 
 1172 
 
 cranium, 102 
 
 labyrinth, 1169 
 
 portion of urethra, 1442 
 
 semicircular canals, 1170- 
 Meningeal artery, 609, 610 
 anterior, 622 
 middle, 613 
 
 surgical anatomy of, 614r 
 posterior, 638 
 small, 614 
 
 lymphatic vessels, 779 
 
 membranes of brain, 847 
 
 nerve, 1032 
 
 veins, 730, 734 
 Meninges of brain, 847 
 Meningo-rachidian veins, 754, 
 
 833 
 Menisco-femoral joint, 342 
 
 -tibial joint, 342 
 Meniscus, 281 
 Mental foramen, 123, 140 
 
 nerve, 1039 
 
 process, 122, 140 
 
 protuberance, 122 
 
 spines, 123 
 
 tubercles, 122 
 Merkel, filtrum ventriculi of, 
 
 1368 
 Mesencephalon, 906 
 Mesenteric arteries, glands along, 
 800 
 
 artery, inferior, 677 
 superior, 675 
 
 ganglion, 1085 
 
 plexus, inferior, 1085 
 superior, 1085 
 
 vein, inferior, 768 
 superior, 768 
 Mesenterico-mesocolic fold, 1262 
 
 -parietal fold, 1264 
 Mesentery, 1257 
 
 development of, 1237 
 
 glands, 807 
 
 of vermiform appendix, 1260 
 Mesoappendix, 1260 
 Mesoblastic somites, 1235 
 Mesoca?cum, 1301 
 Mesochorium, 1461 
 Mesocolic area of kidnev, 1414 
 
 band, 1317 
 
 fossa, 1261 
 Mesocolon, ascending, 1258 
 
 descending, 1258 
 
 sigmoid, 1259 
 
 transverse, 1259, 1309 
 Mesogastrium, 1237 
 Mesognathion, 111 
 Mesorectum, 1259 
 Mesosalpinx, 1490 
 Mesosternum, 159 
 Mesovarium, 1490, 1500 
 Metacarpal bones, 200 
 
 ligament, transverse, 324 
 
 spaces, 201 
 Metacarpo-phalangeal articula- 
 tions, 324, 359 
 
INDEX 
 
 1577 
 
 Metacarpo-phalangeal articula- 
 tions, surface form of, 325 
 Metacarpus, 200 
 
 articulations of, 20-1 
 common character of, 200 
 development of, 205 
 peculiar characters of, 201 
 Metasternum, 159 
 Metatarsal artery, 715 
 bones, 249 
 fifth, 252 
 first, 249 
 fourth, 251 
 
 peculiar characters of, 249 
 second, 250 
 third, 251 
 ligament, transverse, 359 
 Metatarsus, 249 
 
 articulations of, 252 
 common characters of, 249 
 development of, 253 
 Metencephalon, 858 
 Jkletopic suture, 83, 127 
 Mevnert, commissure of, 908 
 Mid-brain, 906 
 
 Middle arcuate ligament, 427 
 cardiac nerve, 1077 
 cerebellar peduncles, 934 
 cerebral artery, 627 
 cervical ganglion, 1076 
 clinoid processes, 93, 132 
 colic arterj^, 676 
 commissure, 903 
 constrictor muscle, 401 
 cornu of lateral ventricle. 
 
 890 
 costo-transverse ligament, 2S6 
 cutaneous nerve, 1004 
 ear, 1150 
 fossa of skull, 130 
 frontal convolution, 873 
 haemorrhoidal artery, 687 
 gland, 799 
 veins, 760 
 inguinal fossa, 1520 
 internal frontal arterj^, 627 
 meatus of nose, 145 
 mediastinum, 1389 
 meningeal artery, 613 
 
 veins, 734 
 occipital convolution, 877 
 
 sulcus, 876 
 odontoid ligament, 52, 279 
 palatine nerve, 1035 
 peduncle of cerebellum, 922 
 sacral artery, 681 
 
 veins, 764 
 spermatic fascia, 440 
 subscapular nerve, 984 
 superior dental nerve, 1033 
 temporal artery, 611 
 convolution, 877 
 vein, 727 
 thyroid vein, 730 
 turbinated bone, 107 
 vesical arterv, 686 
 Mid-gut, 1236 " 
 Milk teeth, 1196 
 Minor cardiac nerve, 1077 
 Mitral orifice, 568 
 Mixed bones, 34 
 Mobile septum, 1097 
 Moderator band, 570 
 Modiolus, 1167 
 Molar glands, 1195 
 
 teeth, 1198 
 Moll, glands of, 1138 
 Monoaxonic cells, 821 
 Monro, foramen of, 889 
 Mons Veneris, 1477 
 Montgomery, glands of, 1504 
 
 Monticulus cerebelli, 927 
 Morgagni, columns of, 1319 
 crvpts of, 1319 
 hydatids of, 1469 
 sinus of, 402 
 valves of, 1319 
 Motor oculi nerve, 1024 
 
 surgical anatomy of, 
 1025 
 projection fibres of cerebrum 
 914 
 tract, 939 
 Mouth, 1193 
 angle of, 1193 
 aperture of, 1193 
 cavity of, 143 
 proper, 1194 
 floor of, Ivmphatic vessels of, 
 
 782 
 mucous membranes of, 1194 
 muscles of, 376 
 surface form of, 1219 
 surgical anatomy of, 1224 
 vestibule of, 1194 
 Movable spleen, 1356 
 Movements admitted in joints, 
 
 266 
 Mucilaginous glands, 262 
 Mucous alveoli, 1218 
 coat of bladder, 1437 
 of gall-bladder, 1343 
 of oesophagus, 1229 
 of pharynx, 1223 
 of urethra, 1444, 1446 
 glands of tongue, 1218 
 Miiller's muscle, 374 
 
 "ring" muscle, 1116 
 Multifidus spinae muscle, 421 
 Multipolar cells, 820 
 Muscle or muscles, 361 
 of abdomen, 432 
 deep, 449 
 superficial, 432 
 abductor hallucis, 544 
 indicis, 499 
 minimi digiti, foot, 544 
 
 hand, 498 
 pollicis, 495 
 accelerator urinse, 457 
 accessorius ad ilio-costalem, 
 419 
 pedis, 546 
 of acromial region, 470 
 adductor brevis, 520 
 longus, 519 
 magnus, 520 
 minimus, 520 
 obliquus hallucis, 546 
 
 pollicis, 497 
 transversus hallucis, 548 
 pollicis, 497 
 anconeus, 487 
 antitragicus, 1147 
 of arm, 470, 474 
 arytenoid, 1375 
 aryteno-epiglottideus, 1373 
 arytenoideus, 1372 
 attoUens auriculam, 369 
 attrahens auriculam, 369 
 of auricular region, 369 
 azvgos uvula?, 405 
 of "back, 410 
 biceps, arm, 475 
 flexor cubiti, 475 
 thigh, 520 
 bipenniform, 363 
 biventer cervicis, 420 
 Bowman's, 1115 
 braehialis anticus, 476 
 buccinator, 380 
 bulbo-cavernous, 557 
 
 Muscle or muscles, cervicalis as- 
 cendens, 419 
 chondro-glossus, 397 
 ciliary of eye, 1115 
 circumflexus, 404 
 coccygeus, 455 
 complexus, 420 
 compressor narium minor, 376 
 nasi, 376 
 
 sacculi laryngis, 1373 
 urethral in female, 462 
 in male, 460 
 constrictor, istlimi faucium, 
 398, 405 
 pharyngeus, inferior, 400 
 middle, 401 
 superior, 401 
 urethrse in female, 462 
 in male, 460 
 coraco-brachialis, 475 
 corrugator cutis ani, 449 
 
 supercilii, 371 
 of cranium, 365 
 cremaster, 439, 1516 
 crico-arytenoid, posterior, 1372 
 
 -thyroid, 1372 
 crureus, 517 
 deltoid, 470 
 depressor alse nasi, 376 
 anguli oris, 378 
 labii inferioris, 378 
 detrusor urinse, 1437 
 diaphragm, 427 
 digastric, 393 
 dilator naris anterior, 376 
 
 posterior, 376 
 of dorsal region, 543 
 ejaculator seminis, 457 
 
 urinse, 457 
 erector clitoridis, 461 
 penis, 458 
 spina^, 417 
 of expression, 385 
 of expiration, 432 
 extensor brevis digitorum, 543 
 pollicis, 489 
 carpi radialis brevior, 485 
 longior, 485 
 ulnaris, 487 
 coccygis, 422 
 communis digitorum, 486 
 indicis, 490 
 longus digitorum, 533 
 
 polhcis, 489 
 minimi digiti, 487 
 ossis metacarpi pollicis, 489 
 primi intemodii pollicis, 489 
 proprius hallucis, 532 
 secundi intemodii pollicis, 
 489 
 of face, 365 
 
 of femoral region, anterior, 512 
 
 internal, 519 
 
 posterior, 529 
 
 of fibular region, 539 
 
 flexor accessorius, 546 
 
 brevis digitorum, 544 
 
 hallucis, 546 
 minimi digiti, foot, 547 
 
 hand, 498 
 pollicis, 497 
 carpi radialis, 479 
 
 ulnaris, 480 
 longus digitorum, 538 
 hallucis, 538 
 pollicis, 482 
 ossis metacarpi, 498 
 
 pollicis, 496 
 profundus digitorum, 482 
 sublimis digitorum, 481 
 of forearm, 478 
 
1578 
 
 INDEX 
 
 Muscle or muscles, of foot, 541 
 frontalis, 368 
 fusiform, 362 
 gastrocnemius, 534 
 gemellus, inferior 527 
 
 superior, 526 
 genio-glossus, 396 
 
 -hvo-glossus, 396, 
 
 -hyoid, 395 
 of gluteal region, 522 
 gluteus maxiraus, 522 
 
 medius, 523 
 
 minimus, 523 
 gracilis, 519 
 hamstring, 529 
 of hand, 491 
 of head, 385 
 helicis major, 1147 
 
 minor, 1147 
 Hilton's, 1373 
 of hip, 522 
 Horner's, 371 
 
 of humeral region, anterior, 
 474 
 posterior, 477 
 Ihyo-glossus, 397 
 of iliac region, 508 
 "iiiacus, 510 
 ilio-capsularis, 511 
 
 -coccygeus, 454 
 
 -costalis, 419 
 infracostales, 425 
 of infra-hyoid region, 391 
 infraspinatus, 472 
 insertion of, 363 
 of inspiration, 432 
 intercostal, 425 
 
 external, 425 
 
 internal, 425 
 of intermaxillary region, 378 
 interossei of foot, 548 
 
 of hand, 499 
 interspinales, 421 
 intertransversales, 422 
 
 lateralis, 422 
 
 mediales, 422 
 involuntary, 361 
 of ischio-rectal region, 449 
 labial, 378 
 of larynx, 1373 
 latissimus dorsi, 413 
 of leg, 531 
 
 levator anguli oris, 377 
 scapulse, 414 
 
 ani, 451 
 
 ■glandula; thyroidea?, 1403 
 
 labii inferioris, 378 . 
 
 inenti, 378 
 
 superioris, 376 
 ala?que nasi, 375 
 
 palati, 403 
 
 palpebrse, 371 
 superioris, 372 
 
 prostata;, 454 
 
 urethrte, 454 
 levatores costarum, 426 
 ligamentous action of, 268 
 of lingual region, 396 
 lingualis, inferior, 399 
 
 superior, 399 
 
 transverse, 399 
 
 vertical, 399 
 longissimus dorsi, 419 
 longus capitis, 407 
 
 colli, 407 
 of lower extremity, 507 
 lumbricales, foot, 546 
 
 hands, 497 
 of mandibular region, 377 
 masseter, 381 
 of maxillary region, 376 
 
 Muscle or muscles, Miiller's, 374 
 multifidus spinae, 421 
 mylo-hyoid, 394 
 of nasal region, 375 
 naso-labialis, 380 
 of neck, 385 
 oblique, ascending, 437 
 
 descending, 433 
 
 external, 433 
 
 internal, 437, 1516 
 obUquus auriculae, 1147 
 
 capitis inferior, 422 
 superior, 422 
 
 oculi, inferior, 374 
 
 superior, 373 
 
 obturator externus, 528 
 
 internus, 525 
 occipitalis, 368 
 occipito-frontalis, 367 
 omo-hyoid, 393 
 opponens minimi digiti, 498 
 
 pollicis, 496 
 orbicular, 363 
 orbicularis oris, 378 
 
 palpebrarum, 370 
 orbital, 374 
 
 region, 372 
 of palatal region, 403 
 palato-glossus, 398, 405 
 
 -pharyngeus, 405 
 of palmar region, middle, 499 
 palmaris brevis, 498 
 
 longus, 480 
 of palpebral region, 370 
 pectineus, 519 
 pectoralis major, 464 
 
 minor, 468 
 of pelvic outlet, 449 
 penniform, 363 
 of perinseum in female, 460 
 
 in male, 455 
 peroneus brevis, 540 
 
 longus, 539 
 
 tertius, 534 
 of pharjmgeal region, 400 
 pharyngo-glossus, 398 
 of plantar region, 544 
 plantaris, 536 
 platysma myoides, 386 
 popliteus, 537 
 pronator quadratus, 483 
 
 radii teres, 479 
 psoas magnus, 509 
 
 parvus, 510 
 of pterygo-mandibular region, 
 
 383 
 pterygoid, external, 383 
 
 internal, 383 
 pubococcygeus, 452 
 pyramidalis abdominis, 444 
 
 nasi, 375 
 pyriformis, 524 
 quadratus femoris, 527 
 
 lumborum, 449 
 
 menti, 378 
 quadriceps extensor, 516 
 quadrilateral, 362 
 of radial region, 484, 495 
 of radio-ulnar region, poste- 
 rior, 486 
 recto-urethralis, 454 
 
 -uterinus, 1491 
 rectus abdominis, 442 
 
 capitis anticus major, 406 
 minor, 407 
 lateralis, 407 
 posticus major, 422 
 minor, 422 
 
 femoris, 516 
 
 oculi, external, 373 
 inferior, 373 
 
 Muscle or muscles, rectus oculi, 
 internal, 373 
 superior, 373 
 retrahens auriculum, 369 
 rhomboidal, 363 
 rhomboideus major, 414 
 
 minor, 414 
 "ring" of Miiller, 1116 
 risorius, 380 
 rotatores spinse, 421 
 sacro-lumbalis, 419 
 salpingo-pharyngeus, 405 
 Santorini's, 380 
 sartorius, 516 
 scalenus anticus, 408 
 
 medius, 408 
 
 posticus, 409 
 of scapular region, anterior, 
 471 
 posterior, 472 
 semicircular, of rectum, 1317 
 semimembranosus, 530 
 semispinalis colli, 421 
 
 dorsi, 421 
 semitendinosus, 530 
 serratus magnus, 468 
 
 posticus inferior, 415 
 superior, 415 
 of shoulder, 470 
 skeletal, 361 
 of sole of foot, 544 
 soleus, 535 
 sphincter, 363 
 
 ani, external, 450 
 internal, 451 
 
 vaginae, 461 
 spinalis colli, 420 
 
 dorsi, 419 
 splenius, 416 
 
 capitis, 416 
 
 colh, 416 
 , sterno-cleido-mastoid, 389 
 
 -hyoid, 391 
 
 -mastoid, 389 
 
 -thvroid, 392 
 striated, 361 
 striped, 361 
 stylo-glossus, 397 
 
 '-hyoid, 394 
 
 -pharyngeus, 403 
 subanconeus, 478 
 subclavius, 468 
 subcrureus, 518 
 subscapularis, 471 
 of superficial cervical region, 
 
 386 
 supinator longus, 484 
 
 radii brevis, 487 
 of supra-hyoid region, 393 
 supraspinales, 421 
 supraspinatus, 472 
 suspensory, of duodenum, 1286 
 temporal,' 382 
 of temporo-mandibular region 
 
 381 
 tensor fascia? fenioris, 515 
 
 palati, 404 
 
 tarsi, 371 
 
 tympani, 1161 
 teres major, 474 
 
 minor, 473 
 of thigh, 512 
 
 of thoracic region, anterior, 
 463 
 lateral, 468 
 of thorax, 424 
 Ihyro-arytenoid, 1373 
 
 -epiglottideus, 1373 
 
 -hyoid, 392 
 tibialis anticus, 532 
 
 posticus, 538 
 
INDEX 
 
 1579 
 
 Muscle or muscles, of tibio- 
 fibular region, 531 
 of tongue, 400 
 extrinsic, 398 
 intrinsic, 391 
 trachelo-mastoid, 419 
 tragic us, 1147 
 
 transversalis abdominis, 442, 
 1516 
 cervicis, 419 
 colli, 419 
 trans versus auriculje, 1147 
 menti, 378 
 
 perinei superficialis, in fe- 
 male, 460 
 in male, 457 
 trapezius, 411 
 triangular, 362 
 triangularis menti, 378 
 
 stern i, 425 
 triceps, 477 
 
 - extensor cubiti, 477 
 of trunk, 410 
 of ulnar region, 498 
 unstriated, 361 
 unstriped, 361 
 of upper extremity, 462 
 of ureters, 1437 
 vastus externus, 517 
 
 internus, 517 
 of vertebral region, anterior, 
 406 
 lateral, 408 
 voluntary, 361 
 zygomaticus major, 377 
 minor, 377 
 Muscular coat of anal canal, 1317 
 of bladder, 1437 
 of duodenum, 1288 
 of intestine, large, 1317 
 
 small, 1290 
 of oesophagus, 1228 
 of rectum, 1317 
 of stomach, 1273 
 of vermiform appendix, 1305 
 portion of urethra, 1442 
 structure of heart, 575 
 substance of tongue, 398 
 MuscuU papillares of ventricle, 
 left, 571 
 right, 570 
 pectinati of auricle, left, 511 
 
 right, 566 
 pubo-vesicalis, 1437 
 Musculo-cutaneous nerve, 985, 
 1017 
 -phrenic artery, 644 
 -spiral groove, 179 
 nerve, 989 
 branches of, 990 
 Myelencephalon, 938 
 Mylo-hyoid artery, 614 
 muscle, 394 
 ridge, 123 
 -hyoidean groove, 124 
 Myocardium, 574 
 Myrtiform fossa, 106 
 
 N 
 
 Naboth, ovules of, 1492 
 Nails, 1185 
 
 body of, 1185 
 
 edge of, 1185 
 
 lunula of, 1185 
 
 matrix of, 1185 
 
 ridges of, 1185 
 
 ungual fold of, 1185 
 wall of, 1185 
 Nares, anterior, 142, 1098 
 
 Nares, posterior, 142, 1098 
 
 septum of, 142 
 Nasal angle, 105 
 
 artery from internal maxil- 
 lary, 616 
 
 from ophthalmic, 625 
 
 of septum, 607 
 
 transverse, 625 
 bones, 104 
 
 articulations of, 105 
 
 attachment of muscles to, 
 105 
 
 borders of, 105 
 
 development of, 105 
 
 surfaces of, 105 
 cartilages, 1096 
 cavity, 142 
 crest. 111, 116 
 duct, 1142 
 fossae, 142, 1098 
 
 arteries of, 1101 
 
 atrium of, 1100 
 
 inner wall of, 1100 
 
 lymphatics of, 1102 
 
 mucous membrane of, 1100 
 
 nerves of, 1102 
 
 outer wall of, 1099 
 
 surgical anatomy of, 1102 
 
 veins of, 1101 
 groove, 105 
 nerve, 1030 
 
 branches of, 1030 
 notch, 80 
 
 portion of pharynx, 1221 
 process, 80 
 
 of superior maxillary, 109 
 region, muscles of, 375 
 slit, 143 
 spine, 80 
 
 anterior. 111, 139, 143 
 
 posterior, 116, 135, 143 
 venous arch, 725 
 Nasion, 80, 139 
 Nasmyth's membrane, 1204 
 Naso-frontal vein, 740 
 -labial ridge, 377 
 -labialis muscle, 380 
 -maxillary suture, 139 
 -palatine artery, 616 
 
 canal, 121 
 
 groove, 121 
 
 nerve, 1036 
 
 -pharynx, 1221 
 
 Navicular bone, 246 
 
 articulations of, 247 
 
 attachment of muscles to, 
 247 
 
 surfaces of, 246 
 
 tuberosity of, 246 
 Neck, arteries of, 595 
 fasciae of, 385 
 lymphatic glands of, 779, 784 
 
 vessels of, 787 
 muscles of, 385 
 triangles of, posterior, 618 
 
 surgical anatomy of, 616 
 veins of, 724, 728 
 N^laton's fine, 229 
 Nerve or nerves, abducent, 1043 
 ansa hypoglossi, 1066 
 of arm, 977 
 Arnold's, 1060 
 of arteries, 586 
 articular, of anterior tibial, 
 1017 
 
 of auriculo-temporal, 1038 
 
 of great sciatic, 1013 
 
 of internal plantar, 1015 
 popliteal, 1014 
 
 of peroneal, 1016 
 
 of posterior tibial, 1015 
 
 Nerve or nerves, articular, of 
 
 ulnar, 988 
 auditory, 1050 
 auricular, anterior, 1038 
 
 of pneumogastric, 1060 
 
 posterior, 1047 
 auriculo-temporal, 1037 
 of bones, 41 
 buccal, 1037 
 
 from facial, 1049 
 buccinator, 1037 
 calcaneal, external, 1014 
 
 internal, 1015 
 calcaneo-plantar, 1015 
 cardiac, cervical, 1061 
 
 great, 1077 
 
 inferior, 1077 
 
 middle, 1077 
 
 minor, 1077 
 
 superior, 1076 
 
 thoracic, 1061 
 cardio-motor, 1071 
 carotico-tympanic, 1073 
 carotid, 1057 
 cavernous, large, 1086 
 
 small, 1086 
 -cells, 818 
 
 axone of, 821 
 
 dendrites of, 821 
 
 development of, 823 
 cerebral, 1019 
 cervical, 968, 1049 
 
 superficial, 973 
 cervico-facial, 1049 
 chorda tympani, 1038, 1047 
 ciliary, long, 1030 
 
 short, 1031 
 circumflex, 984 
 coccygeal, 1006 
 cochlear, 1053 
 
 communicantes hypoglossi, 974 
 communicating, fibular, 1014 
 
 tibial, 1014 
 of Cotunnius, 1036 
 cranial, 1019 
 
 first, 880 
 crural, 'anterior, 1004 
 
 accessory of Winslow, 
 1004 
 cutaneous, of abdomen, 996 
 
 external, 985, 1003 
 
 internal, 986, 1004 
 
 of internal plantar, 1015 
 
 middle, 1004 
 
 of musculo-cutaneous, 1017 
 -spiral, 991 
 
 of obturator, 1003 
 
 palmar, 986 
 
 of perineal, 1013 
 
 of peroneal, 1016 
 
 of small sciatic, femoral, 
 1011 
 gluteal, 1011 
 perineal, 1011 
 
 of supraorbital, 1030 
 
 of thorax, 995 
 
 of ulnar, 988 
 dorsal, 989 
 palmar, 988 
 dental, anterior superior, 1033 
 
 inferior, 1039 
 
 middle superior, 1033 
 
 posterior superior, 1032 
 descendens hypoglossi, 1066 
 
 noni, 1066 
 digastric, from facial, 1048 
 digital, foot, 1015 
 
 hand, 987 
 dorsal, 993 
 
 of clitoris, 1013 
 
 of penis, 1013 
 
1580 
 
 INDEX 
 
 Nerve or nerves, dorsi-lumbar,996 
 of dura mater of brain, 849 
 eighth, 1050 
 eleventh, 1063 
 -endings, Ruffini's, 828 
 -epithelium cells, 830 
 of eyeball, 1021 
 facial, 1044 
 
 -fibre, axis-cylinder of, 822 
 -fibres, 822 
 
 development of, 823 
 
 medullated, 822 
 
 non-medullated, 823 
 
 of retina, 1122 
 fifth, 1026 
 first, 1019 
 of foot, 1015 
 fourth, 1025 
 frontal, 1030 
 ganglia of, 831 
 gastric, 1061 
 genito-c rural, 1000 
 glosso-pharyngeal, 1054 
 gluteal, inferior, 1011 
 
 superior, 1010 
 gustatory, 1038 
 hsemorrhoidal, inferior, 1011 
 of heart, 577 
 hypogastric, 999 
 hypoglossal, 1064 
 iliac, 999 
 ilio-hypogastric, 999 
 
 -inguinal, 999 
 incisor, 1039 
 inframandibular, 1049 
 inframaxillary, 1049 
 infraorbital, 1049 
 infratrochlear, 1031 
 intercostal, 993 
 intercosto-humeral, 995 
 interosseous, anterior, 987 
 
 of anterior tibial, 1017 
 
 posterior, 991 
 Jacobson's, 1056 
 jugular, 1073 
 labial, 1034 
 of labyrinth, 1176 ' 
 lachrymal, 1028 
 of Lancisi, 887 
 
 laryngeal, inferior, of pneumo- 
 gastric, 1060 
 
 superior, 1060 
 external, 1060 
 internal, 1060 
 lingual of fifth, 1038, 
 
 of glosso-pharyngeal, 1057 
 lumbar, 997 
 malar, 1049 
 
 of superior maxillary, 1032 
 mandibular, 1036 
 masseteric, 1037 
 mastoid, 973 
 maxillary, inferior, 1036 
 
 superior, 1031 
 median, 986 
 meningeal, 1032 
 
 from hypoglossal, 1066 
 
 of internal maxillary, 1036 
 
 of pneumogastric, 1059 
 mental, 1039 
 motor oculi, 1024 
 muscular, of anterior tibial, 
 1017 
 
 of external plantar, 1016 
 
 of great sciatic, 1013 
 
 of hypoglossal, 1066 
 
 of internal plantar, 1015 
 popliteal, 1014 
 
 of musculo-cutaneous, 1017 
 -spiral, 990 
 
 of perineal, 1013 
 
 Nerve or nerves, muscular, of 
 posterior tibial, 1014 
 
 of sciatic plexus, 1010 
 
 of ulnar, 988 
 musculo-cutaneous, 985, 1017 
 
 -spiral, 989 
 mylo-hyoid, 1039 
 nasal, 1030 
 
 from Meckel's ganglion, 1034 
 
 ganglionic branch of, 1030 
 naso-palatine, 1036 
 ninth, 1054 
 obturator, 1003 
 
 accessory, 1004 
 occipital, from facial, 1048 
 
 great, 969 
 
 small, 972 
 oesophageal, 1061 
 olfactorv, 880, 1019 
 ophthalmic, 1028 
 optic, 1021 
 orbital, of superior inaxillary, 
 
 1032 
 origin of, 826 
 palatine, anterior, 1035 
 
 external, 1035 
 
 large, 1035 
 
 middle, 1035 
 
 posterior, 1035 
 
 small, 1035 
 palmar, of ulnar, deep, 989 
 
 superficial, 989 
 palpebral, 1034 
 parotid, 1038 
 -paths, 959 
 
 auditory, 1053 
 
 cochlear, 1053 
 
 gustatory, 1057 
 
 vestibular, 1054 
 perforating, of Casserius, 985 
 of pericardium, 561 
 pericranial, 1030 
 perineal, 1013 
 peroneal, 1016 
 petrosal, deep, 1073 
 
 great deep, 1034 
 superficial, 1034 
 
 large deep, 1034, 1073 
 superficial, 1034 
 pharyngeal, 1036, 1057, 1060 
 phrenic, 974 
 
 of pia mater of brain, 856 
 plantar, external, 1016 
 
 internal, 1015 
 plexus of, abdominal aortic, 
 1085 
 
 annular, 1111 
 
 brachial, 977 
 
 cardiac, 1081 
 
 carotid, internal, 1073 
 
 cavernous, 1073 
 
 cervical, 972 
 
 cceliac, 1061, 1084 
 
 coUc, left, 1085 
 
 coronary, 1081, 1085 
 
 cystic, 1085 
 
 of dental, superior, 1033 
 
 epigastric, 1083 
 
 fundamental, 1111 
 
 gastric, 1085 
 
 gastro-duodenal, 1085 
 -epiploic, 1085 
 left, 1085 
 
 hsemorrhoidal, inferior, 1086 
 superior, 1085 
 
 hepatic, 1085 
 
 hypogastric, 1085 
 
 infraorbital, 1049 
 
 intra-epithelial, 1111 
 
 lumbar, 998 
 
 mesenteric, inferior, 1085 
 
 Nerve or nerves, plexus of. mes- 
 enteric, superior, 1085 
 
 oesophageal, 1059, 1061, 
 1082 
 
 ovarian, 1084 
 
 pancreatic, 1085 
 
 patellar, 1004 
 
 peKdc, 1086 
 
 pharyngeal, 1057 
 
 phrenic, 1084 
 
 prostatic, 1086 
 
 pudendal, 1009 
 
 pudic, 1009 
 
 pulmonary, 1081 
 anterior, 1059, 1061 
 posterior, 1059, 1061 
 
 pyloric, 1085 
 
 renal, 1061, 1084 
 
 sacral, 1009, 1086 
 
 sciatic, 1009 
 
 sigmoid, 1085 
 
 solar, 1083 
 
 spermatic, 1084 
 
 splenic, 1061, 1085 
 
 subclavian, 1077 
 
 subepithelial, 1111 
 
 suprarenal, 1084 
 
 thoracic aortic, 1079 
 
 tympanic, 1057 
 
 uterine, 1086 
 
 utero-vaginal, 1086 
 
 vaginal, 1086 
 
 vertebral, 1077 
 
 vesical, 1086 
 pneumogastric, 1057 
 popliteal, external, 1016 
 
 internal, 1014 
 portio dura, 1044 
 
 mollis, 1045 
 pterygoid, external, 1037 
 
 internal, 1037 
 pterygo-palatine, 1036 
 pudendal, inferior, 1011 
 pudic, 1011 
 pulmonary, anterior, 1061 
 
 posterior, 1061 
 radial, 991 
 
 recurrent, of internal maxil- 
 lary, 1036 
 
 laryngeal, of pneumogastric, 
 1060 
 respiratorv, of Bell, external, 
 983 
 internal, 974 
 sacral, 1006 
 saphenous, external, 1014 
 
 internal, 1005 
 
 long, 1005 
 
 short, 1014 
 scapular, posterior, 982 
 of Scarpa, 1036 
 sciatic, great, 1013 
 
 small, 1011 
 scrotal, long, 1011 
 second, 1021 
 seventh, 1044 
 sixth, 1043 
 spheno-palatine, 1032 
 sphenoidal, 1039 
 spinal, 964 
 
 accessory, 1063 
 -spindles, 829 
 splanchnic, 1079 
 
 renal, 1079 
 stylo-hyoid, 1048 
 subcutaneous maliB, 1032 
 suboccipital, 968 
 subscapular, 984 
 superficialis colli, 973 
 supra-acromial, 974 
 I supraclavicular, 974 
 
INDEX 
 
 1581 
 
 Nerve or nerves, supramandib- 
 ular, 1049 
 
 supramaxillary, 1049 
 
 supraorbital, 1030 
 
 suprascapular, 983 
 
 suprasternal, 974 
 
 supratrochlear, 1030 
 
 sural, 1016 
 
 sympathetic, 1066 
 
 temporal, of auriculo-tempo- 
 ral, 1038 
 deep, 1037 
 from facial, 1049 
 of superior maxillary, 1032 
 
 temporo-malar, 1032 
 
 tenth, 1057 
 
 termination of, 826 
 peripheral, 826 
 
 third, 1024 
 
 thoracic, 993 
 anterior, 984 
 long, 983 
 posterior, 983 
 
 thyro-hvoid, 1066 
 
 thvroid, 1077 
 
 tibial, 1014 
 anterior, 1016 
 posterior, 1014 
 
 tonsillar, 1057 
 
 trifacial, 1026 
 
 trigeminal, 1026 
 
 trochlear, 1025 
 
 twelfth, 1064 
 
 tympanic, 1056 
 from facial, 1047 
 
 ulnar, 988 
 
 -unit, 818 
 
 vagus, 1057 
 
 vasomotor, 1071 
 
 vestibular, 1053 
 
 Vidian, 1034 
 Nervi nervorum, 825 
 Nervous papillae, 1181 
 
 system, 817 
 
 cerebro-spinal, structure of, 
 817 
 
 tissue, chemical composition 
 of, 824 
 
 cutaneous patelliB, 1005 
 
 superficialis cordis, 1076 
 Neumann, dentinal sheath of, 
 
 1203 
 Neural arch, 34 
 
 canal, 857 
 
 tube, 857 
 Neurenteric canal, 1242 
 Neurilemma of cord, 822 
 Neuroblasts, 823 
 Neuro-central suture, 59 
 
 -muscular spindles, 829 
 
 -tendinous spindles, 829 
 Neuroglia of cord, 840 
 Neurokeratin, 823 
 Neurones, 818 
 
 of Cajal, 919 
 
 cell-bodies of, 818 
 
 theory of, 821 
 Nexal root of eighth nerve, 1050 
 Nidus avis of cerebellum, 931 
 Ninth nerve, 1054 
 
 surgical anatomy of, 1057 
 Nipple, 1504 
 
 structure of, 1505 
 Nissl's bodies, 820 
 Nodal point, 1106 
 Nodules of cerebellum, 930 
 Non-medullated nerve-fibres, 823 
 Nose, 1095 
 
 aperture of cartilage of, 1097 
 
 arteries of, 1098 
 
 cartilage of, 1096 
 
 Nose, dorsum of, 1096 
 fossae of, 142, 1098 
 integument of, 1097 
 interior of, lymphatic vessels 
 
 of, 782 
 lymphatics of, 1098 
 meatus of, inferior, 145 
 middle, 145 
 superior, 101, 144 
 mucous membrane of, 1098 
 muscles of, 1097 
 nerves of, 1098 
 outer, 1096 
 septum of, 142 
 
 cartilage of, triangular, 1097 
 structure of, 1096 
 veins of, 1098 
 Notch cerebellar, anterior, 926 
 posterior, 926 
 cotyloid, 213 
 ethmoidal, 82 
 ilio-sciatic, 210 
 intercondyloid, 225 
 intervertebral, 49 
 lachrymal, 107 
 nasal, 80 
 popliteal, 234 
 pre-sternal, 157 
 pre-occipital, 869 
 pterygoid, 96 
 of Rivinus, 1151 
 sacro-sciatic, 217 
 great, 210 
 lesser, 211 
 scapular, great, 173 
 sigmoid, 125 
 spheno-palatine, 118 
 supraorbital, 80, 140 
 suprascapular, 174 
 suprasternal, 409 
 thyroid, 1362 
 Nuchal line, inferior, 72 
 superior, 72 
 plane, 72 
 Nuck, canal of, 1462, 1501 
 Nucleated sheath of Schwann, 
 
 822 
 Nuclei, auditory, 950 
 of auditory nerve, £25 
 of fifth nerve, 925 
 of glosso-pharyngeal nerve, 950 
 of optic thalamus, 904 
 of vagus nerve, 950 
 Nucleus, accessory, of eighth 
 nerve, 1051 
 amygdaloid, 891 
 ambiguus, 950, 1056 
 of Bechterew, 926, 1050 
 caudate, 891 
 cuneate, accessorv, 948 
 of Deiters, 926, 1050 
 emboliformis, 938 
 of facial nerve, 925 
 fasciculi gracilis, 941 
 fastigii, 938 
 globosus, 938 
 hypoglossal, 949 
 inferior central, 949 
 lentis, 1132 
 lenticular, 890 
 of Luys, 908, 910 
 of olivary body, 951 
 accessory, 951 
 superior, 925 
 of optic thalamus. 904 
 of sixth nerve, 925 
 of spinal accessorv nerve, 950 
 of Stilling, red, 938 
 of tegmentum, red, 908 
 vagi, 1057 
 Nuel, space of, 1175 
 
 Nuhn and Blandin, glands of, 
 
 1091 
 Nutrient arterv of femur, 707 
 
 of fibula, 718 
 
 of humerus, 656 
 
 of tibia, 719 
 Nymphse, 1478 
 
 Obelion, 129 
 Obex, 944 
 
 Oblique diameter of pelvis, 217 
 fibres of cord, 841 
 inguinal hernia, 1517, 1520 
 complete, 1521 
 incomplete, 1521 
 ligament, 314 
 line of clavicle, 168 
 of fibula, 237 
 of radius, 190 
 of tibia, 235 
 muscles, ascending, 437 
 aponeurosis of, 439 
 descending, 433 
 external, 433 
 
 aponeurosis of, 434 
 internal, 437, 1516 
 aponeurosis of, 439 
 dissection of, 437 
 ridges of scapula, 171 
 of trapezium, 198 
 of ulna, 188 
 sacro-iliac ligament, 292 
 sinus of pericardium, 560 
 vein of Marshall, 771 
 Obliquus auriculse muscle, 1147 
 capitis inferior muscle, 422 
 
 superior muscle. 422 
 oculi muscle, inferior, 374 
 superior, 373 
 Obstetric perinseum, 1478 
 Obturator artery, 688 
 peculiarities of, 689 
 bursa, 331 
 canal, 525 
 crest, 213 
 
 externus muscle, 528 
 fascia, 1546 
 foramen, 214 
 groove, 211, 213 
 internus muscle, 525 
 
 bursa of, 525 
 ligament, 296 
 membrane, 525 
 nerve, 1003 
 
 accessory, 1004 
 vein, 761 
 Occipital artery, 608, 640 
 branches of, 609 
 bone, 71 
 
 angles of, 75 
 articulations of, 76 
 attachment of muscles to, 76 
 borders of, 75 
 development of, 75 
 structure of, 75 
 surfaces of, 71 
 convolution, inferior, 877 
 middle, 877 
 superior, 877 
 crest, external, 72, 136 
 
 internal, 74, 133 
 diploic vein, 734 
 fossae, inferior, 133 
 groove, 86 
 
 horn of lateral ventncle, 889 
 lobe, 876 
 
 gray matter of, 921 
 lymphatic glands, 780 
 
1582 
 
 INDEX 
 
 Occipital nerve, branch of facial, 
 1048 
 great, 969 
 small, 972 
 protuberance, external, 71, 136 
 
 internal, 73 
 sinus, 739 
 sulci, 868, 876 
 triangle, 618 
 vein, 727 
 Occipitalis muscle, 368 
 Occipito-atlantal ligament, ante- 
 rior, 276 
 » posterior, 276 
 
 -axial ligament, posterior, 278 
 -frontal fasciculus, 918 
 -frontalis, muscle, 367 
 
 surgical anatomy of, 368 
 -parietal suture, 128 
 -temporal convolution, 878 
 gyrus, 877 
 sulcus, 870 
 Occiput, arteries of, 608 
 Odontoblasts, 1206 
 
 of Waldeyer, 1201 
 Odontoclasts, 1209 
 Odontoid ligaments, lateral, 278 
 middle, 52, 279 
 process of axis, 52 
 Esophageal arteries, 641, 666 
 nerves, 1061 
 opening of diaphragm, 430 
 
 of stomach, 1270 
 plexus, 1059, 1061, 1082 
 veins, 751 
 CEsophagus, 1225 
 
 abdominal portion, 1226 
 anomalies of, 1228 
 areolar coat of, 1229 
 arteries of, 1229 
 cervical portion, 1226 
 diaphragmatic portion, 1226 
 innervation of, 1230 
 lymphatics of, 815, 1230 
 movements of, 1230 
 mucous coat of, 1229 
 muscular coats of, 1228 
 nerves of, 1230 
 relations of, 1227 
 structure of, 1228 
 submucous coat of, 1229 
 surgical anatomy of, 1230 
 thoracic portion, 1226 
 veins of, 1229 
 Olecranon bursa, 311 
 subcutaneous, 477 
 fossa, 181 
 process, 186 
 Olfactory bulb, 880, 1019 
 gray matter of, 921 
 cells, 1101 
 fasciculus, 895 
 foramina, 143 
 hair, 1101 
 lobe, 880 
 
 anterior, 880 
 posterior, 881 
 nerve, 880, 1019 
 
 surgical anatomy of, 1021 
 path, 1020 
 sulcus, 870, 874 
 tract, 880, 1019 
 tubercle, 881, 1019 
 OUvary body of medulla oblon- 
 gata, 941 
 corpus of,. 951 
 nucleus of, 951 
 peduncles of, 951 
 bundle of cord, 843 
 eminence, 93 
 fasciculus, 910 I 
 
 Olivary nucleus superior, 925 
 
 process, 93, 131 
 Omenta, 1254 
 Omental band, 1317 
 
 tuberosity, 1329 
 Omentum, development of, 1238 
 gastro-colic, 1256 
 -hepatic, 1254 
 -splenic, 1256 
 great, 1256 
 lesser, 1254 
 Omo-hyoid muscle, 393 
 Opercula of insula, 878 
 Operculum, frontal, 866, 874 
 fronto-parietal, 866, 874 
 orbital, 866, 874 
 Ophryon, 80 
 Ophthalmic artery, 622 
 branches of, 622 
 ganglion, 1031 
 nerve, 1028 
 
 branches of, 1028 
 veins, 740 
 inferior, 741 
 superior, 740 
 Opisthotonic portion of temporal 
 
 bone, 91 
 Opponens minimi digiti muscle, 
 foot, 547 
 hand, 498 
 pollicis muscle, 496 
 Optic axis, 1106 
 chiasma, 882 
 commissure, 131, 882, 1021 
 
 inter-cerebral fibres of, 1021 
 cup, 1121 
 disk, 1121 
 
 foramen, 93, 96, 131, 142 
 groove, 93, 130, 131 
 lobes, 911 
 nerve, 1021 
 
 surgical anatomy of, 1022 
 papilla, 1121 
 path, 1022 
 radiations, 905 
 recess, 902 
 thalamus, 903 
 
 connections of, 905 
 nuclei of, 904 
 stalk of, 905 
 tubercle of, 904 
 tract, 884, 1021 
 Ora serrata, 1120 
 Oral cavity, 1193 
 
 portion of pharynx, 1221 
 of tongue, 1087 
 Orbicular bone, 1159 
 ligament, 314 
 muscles, 363 
 Orbicularis oris muscle, 378 
 palpebrarum muscle, 370 
 external portion of, 370 
 internal portion of, 370 
 orbital portion of, 370 
 palpebral portion of, 370 
 Orbiculus ciliaris, 1115 
 Orbit, 140 
 
 arteries of, 623 
 fasciae of, 374 
 margin of, 106 
 muscles of, 374 
 Orbital arterv, 611 
 internal," 627 
 branch of facial nerve, 1032 
 cavities, 140 
 
 convolution, anterior, 874 
 internal, 873 
 posterior, 874 
 fascia, 375 
 fissure, 96 
 foramina, 95 
 
 Orbital fossie, 140, 143 
 lobe, 874 
 muscle, 374 
 nerve, 1032 
 operculum, 866, 874 
 plates, 81 
 
 process of malar, 114 
 of palate bone, 118 
 region, muscles of, 372 
 action of, 374 
 dissection of, 372 
 surgical anatomy of, 375 
 septum, 1139 
 sinus, 118 
 sulcus, 870, 874 
 vein, 727 
 Orbito-palpebral sulcus, inferior,, 
 1137 
 superior, 1137 
 -tarsal ligament, 1139 
 Orbits, 140 
 Organ of Corti, 1173 
 of Jacobson, 1100 
 Organs of digestion, 1193 
 of generation, female, 1477 
 
 male, 1447 
 of Giraldes, 1473 
 of Golgi, 829 
 of respiration, 1361 
 of Rosenmiiller, 1499 
 of special sense, 1087 
 of voice, 1361 
 Orifice, mitral, 568 
 
 of prostatic ducts, 1442 
 tricuspid, 567 
 of ureters, 1438 
 Os acetabulum, 213 
 external, 1489 
 incfe, 76 
 
 innominatum, 207 
 articulations of, 215 
 attachment of muscles to, 
 
 215 
 development of, 214 
 ilium, 207 
 ischion, 210 
 pubis, 212 
 structure of, 214 
 internal, 1488 
 magnum of carpus, 199 
 articulations of, 199 
 attachment of muscles to,. 
 
 199 
 surfaces of, 199 
 planum of ethmoid, 100 
 trigonum, 245 
 uteri, 1489 
 Ossa pubis, articulations of, 296- 
 angle of, 212 
 unguis, 113 
 Osseous labyrinth, 1164 
 
 portion of Eustachian tube, 
 1154 
 of external auditory meatus,. 
 1149 
 Ossicles of tympanum, 1158 
 articulations of, 1160 
 ligaments of, 1160 
 movements of, 1161 
 Ossification of bone, 42 
 centre of, 44 
 intracartilaginous, 43 
 intramembranous, 43 
 of spine, 60 
 Osteo-dentine of Owen, 1204 
 Osteoclasts, 36 
 Osteology, 33 
 Ostium abdominale of Fallopian. 
 
 tube, 1497 
 Otic ganglion, 1039 
 branches of, 1039 
 
INDEX 
 
 158a 
 
 Otokonien, 1171 
 Otolith, 1169 
 
 membrane, 1172 
 Outlet of pelvis, 217 
 Ova, primordial, 1502 
 Ovarian arteries, 680 
 
 bursa, 1490 
 
 plexus, 1084 
 
 veins, 766 
 Ovario-pelvic fold, 1500 
 Ovary, 1499 
 
 arteries of, 1503 
 
 at different ages, 1501 
 
 connections of, 1500 
 
 descent of, 1501 
 
 fimbria of, 1499 
 
 hilum of, 1500 
 
 lymphatics of, 1503 
 
 lymphatic vessels of, 804 
 
 nerves of, 1503 
 
 serous covering of, 1501 
 
 stroma of, 1501 
 
 structure of, 1501 
 
 supports of, 1500 
 
 surgical anatomy of, 1503 
 
 veins of, 1503 
 Ovicapsule of Graafian follicles 
 
 1502 
 Ovules of Naboth, 1492 
 Ovum, discharge of, 1503 
 Oxvntic cells, 1277 
 
 glands, 1277 
 
 Pacchion'Iax depressions, 78 
 
 glands, 737, 854 
 Pacinian corpuscles, 828 
 Pads of adipose tissue, 263 
 
 corpus callosum, 886 
 Palatal region, muscles of, 403 
 dissection of, 403 
 surgical anatomy of, 406 
 Palate, 1210 
 bone, 115 
 
 articulations of, 119 
 attachment of muscles to, 
 
 119 
 development of, 119 
 horizontal plate of, 116 
 borders of, 116 
 surfaces of, 116 
 perpendicular plate of, 117 
 borders of, 117 
 surfaces of, 117 
 processes of, 118 
 tuberosity of, 117, 135 
 vertical plate of, 117 
 borders of, 117 
 surfaces of, 117 
 hard, 1210 
 muscles of, 403 
 soft, 1211 
 
 surgical anatomy of, 1224 
 vail of, 1211 
 Palatine aponeurosis, 404 
 artery, ascending, 606 
 descending, 615 
 inferior, 606 
 posterior, 615 
 surgical anatomy of, 615 
 canal, anterior, 143 
 posterior, 107, 116 
 accessory, 116, 135 
 foramen, great, 116 
 
 posterior, 135 
 fossa, anterior, 110, 133 
 glands, 1211 
 nerve, anterior, 1035 
 external, 1035 
 
 Palatine nerve, large, 1035 
 middle 1035 
 posterior, 1035 
 small, 1035 
 process of superior maxiilarv, 
 
 120 
 spine, 116 
 Palato-glossus muscle, 398, 405 
 -maxillary canal, 107 
 -pharyngeiLs muscle, 405 
 Palmar arch, deep, 658 
 superficial, 664 
 surface marking of, 665 
 surgical anatomy cf, 665 
 cutaneous nerve, 987 
 fascia, deep, 493 
 
 surgical anatomy of, 494 
 interosseous arteries, 660 
 plexus of nerves, 745 
 recurrent arteries, 660 
 region, middle, muscles of, 499 
 veins, 747 
 Palmaris brevis muscle, 498 
 
 longus muscle, 480 
 Palpebral arteries, external, 623 
 internal, 623 
 cartilages or plates, 1139 
 fascia?, 1139 
 ligaments, 1139 
 nerves, 1034 
 
 portion of conjunctiva, 1140 
 region, muscles of, 370 
 dissection of, 370 
 Pampiniform plexus of veins, 765 
 Pancreas, 1348 
 arteries of, 1352 
 body of, 1350 
 borders of, 1350 
 development of, 1244 
 dissection of, 1348 
 head of, 1348 
 lymphatic vessels of, 807 
 lymphatics of, 1352 
 neck of, 1350 
 nerves of, 1353 
 peritoneal relations of, 1351 
 structure of, 1352 
 surface form of, 1353 
 surfaces of, 1350 
 surgical anatomy of, 1353 
 tail of, 1350 
 veins of, 1352 
 Pancreatic area of kidney, 1414 
 artery, 674 
 duct, 1351 
 juice, 1353 
 
 plexus of nerves, 1085 
 of veins, 768 
 Pancreatic a magna artery, 674 
 Pancreatico-duodenal artery, 
 inferior, 675 
 superior, 674 
 plexus of nerves, 1085 
 vein, 768 
 Papilla, bile, 1288 
 dentine, 1205 
 lachrj'mal, 1142 
 spiralis, 1173 
 PapillsB circumvallate, 1089 
 conical, 1090 
 filiform, 1090 
 fungiform, 1090 
 raaximse, 1089 
 media;, 1090 
 minimsB, 1090 
 of tongue, 1089 
 simple, 1090 
 structure of, 1090 
 Papillary layer of skin, 1187 
 Paracentral lobule, 875 
 Paraduodenal fossa, 1262 
 
 Paramastoid process, 73 
 Paramedians sulcus, 868 
 Parametrium, 1489 
 Paramammary gland, 813 
 Paranucleus, 1352 
 Parathyroids, 1406 
 
 structure of, 1406 
 Parenchyma of lungs, 1395 
 
 of testicle, 1471 
 Paries carotica, 1153 
 jugularis, 1151 
 labyrinthica. 1152 
 mastoidea, 1152 
 tegmentalis, 1151 
 Parietal artery, 611 
 
 arteries, ascending, 628 
 bone, 76 
 
 articulations of, 79 
 attachment of muscles to, 
 
 79 
 development of, 78 
 surfaces of, 76 
 borders of, 78 
 cells of gastric glands, 1277 
 convolution, ascending, 876 
 inferior, 876 
 superior, 876 
 diploic vein, external, 734 
 eminence, 76 
 foramen, 76 
 layer of pleura, 1385 
 lobe, 875 
 lymphatics, 810 
 peritoneum, 1247 
 portion of tunica vaginalis, 
 
 1470 
 surface of liver, 1330 
 of stomach, 1269 
 Parieto-colic fold, external, 1263 
 internal, 1264 
 -occipital sulcus, 867 
 external, 867 
 internal, 867, 870 
 • -sphenoidal artery, 628 
 
 -temporal artery, 628 
 Paro-ophoron, 1499 
 Parotid capsule, 1216 
 duct, 1215 
 
 structure of, 1216 
 surface form of, 1215 
 fascia, 388, 1215 
 gland, 1214 
 
 accessory, 1215 
 arteries of, 1216 
 duct of, 1215 
 lymph, 1215 
 lymphatics of, 1216 
 nerves of, 1216 
 veins of, 1216 
 lymphatic glands, 781 
 deep, 782 
 superficial, 781 
 nerves, 1038 
 recess, 1215 
 Paratideo-masseterica fascia, 388 
 Parovarium, 1499 
 Pars ciliaris retinae, 1115, 1120 
 intermedia of Wrisberg, 1045 
 iridica retinae, 1120 
 Patella, 230 
 apex of, 231 
 articulations of, 231 
 attachment of muscles to, 231 
 borders of, 231 
 development of, 231 
 ligaments of, 335 
 structure of, 231 
 surfaces of, 231 
 form of, 231 
 surgical anatomy of, 231 
 Patellar bursa, deep, 518 
 
1584 
 
 INDEX 
 
 Patellar plexus, 1004 
 Path of light stimuli, 1127 
 Paths, nerve, auditory, 1053 
 cochlear, 1053 
 gustatory, 1057 
 vestibular, 1054 
 olfactory, 1020 
 optic, 1022 
 Pecquet, reservoir of, 775 
 Pecten ossis pubis, 212 
 Pectineus muscle, 519 
 
 nerve to, 1005 
 Pectoral fascia, deep, 464 
 gland, 790 
 
 intercostal nerve, 995 
 region, dissection of, 463 
 ridge, 179 
 Pectoralis muscle, major, 464 
 
 minor, 468 
 Peduncles of cerebellum, 932 
 inferior, 935 
 middle, 922, 934 
 superior, 910, 932, 943 
 cerebral, 906 
 of cerebrum, 882, 884 
 ■of corpus callosum, 882, 886 
 ■of flocculus, 931 
 of mammillary body, 883 
 of olive, 951 
 
 of perineal gland, 895, 906 
 Peduncular fibres of cerebellum, 
 932 
 of cerebrum, 914 
 Pelvic colon, 1311 
 fascia, 1544 
 girdle, 207 
 
 ligament, transverse, 459 
 plexus, 1086 
 
 portion of gangliated cord, 1080 
 Pelvis, 215 
 axes of, 218 
 brim of, 217 
 cavity of, 217, 1431 
 boundaries of, 1431 
 contents of, 1431 
 ■diameters of, 217 
 diaphragm of, 1231 
 ■differences between male and 
 
 female, 219 
 false, 215 
 ■of kidney, 1415 
 lower circumference of, 217 
 lymphatic vessels of, 801 
 lymphatics of, 797 
 muscles of, 449 
 ■outlet of, 217 
 position of, 218 
 surface form of, 220 
 surgical anatomy of, 220 
 true, 216 
 
 inlet of, 217 
 
 superior circumference of, 
 217 
 veins of, 755 
 Pendulous portion of urethra, 
 
 1443 
 Penile portion of urethra, 1443 
 Penis, 1453 
 
 arteries of, 1459 
 
 dorsal, 692 
 body of, 1455 
 
 corpora cavernosa of, 1455 
 corpus spongiosum, 1458 
 crura of, 1454 
 dorsum of, 1455 
 frsenum of, 1455 
 ligaments of, 1459 
 lymphatics of, 1459 
 
 vessels of, superficial, 801 
 nerves of, 1013, 1460 
 dorsal, 1013 
 
 Penis, prepuce of, 1455 
 root of, 1454 
 septum of, 1457 
 structure of, 1455 
 surgical anatomy of, 1460 
 veins of, 1459 
 dorsal, deep, 762 
 superficial, 762 
 Penniform muscles, 363 
 Peptic cells of glands, 1277 
 
 glands, 1277 
 Perforating arteries, anterior, 
 644 
 of hand, 660 
 of thigh, 706 
 cutaneous nerve, 1011 
 nerve of Casserius, 985 
 Pericajcal folds, 1262 
 
 fossa}, 1262 
 Pericardiac arteries, 644, 666 
 Pericardial pleura, 1385 
 
 sac, 1236 
 Pericardiothoracic cavity, 1236 
 Pericardium, 557 
 arteries of, 561 
 fibrous layer of, 558 
 nerves of, 561 
 serous, 560 
 sinus of, oblique, 560 
 
 transverse, 560 
 structure of, 558 
 surgical anatomy of, 561 
 vestigial fold of, 561 
 Pericementum, 1196 
 Perichondrium, 260 
 Perichoroidal space, 1108 
 Pericranial nerves, 1030 
 Perilymph, 1164 
 
 space, 1164 
 Perimysium, external, 361 
 
 internal, 361 
 Perineal artery, superficial, 690 
 transverse, 691 
 body, 1314, 1484, 1543 
 cutaneous nerve, 1011 
 fascia, deep, 1538 
 ligament, transverse, 459 
 nerve, 1013 
 Perineum, 1314, 1484 
 dissection of, 1535 
 in female, 1542 
 
 muscles of, 460 
 lymphatic vessels of, super- 
 ficial, 801 
 in male, 1537 
 
 central tendinous point of, 
 
 1537 
 fascise of, 455 
 muscles of, 455 
 obstetric, 1478 
 surgical anatomy of, 1535 
 Perineurium, 825 
 Periosteum, 37 
 dental, 1204 
 Peripheral branches of lumbar 
 portion of gangliated cord, 
 1080 
 of middle cervical ganglion, 
 
 1077 
 of pelvic portion of gangli- 
 ated cord, 1080 
 of sacral portion of gangli- 
 ated cord, 1080 
 of superior cervical gan- 
 glion, 1073 
 of thoracic portion of gan- 
 gliated cord, 1079 
 terminations of nerves, 826 
 Peritoneal coat of duodenum, 
 1288 
 of stomach, 1273 
 
 Peritoneal relations of pancreas, "I 
 
 1351 
 Perisclerotic lymph-space, 1103 
 Peritoneum, 1245 
 
 development of, 1235, 1242 
 ligaments of, 1254 
 lymphatic vessels of, 802 
 
 surgical anatomy of, 802 
 mesenteries of, 1257 
 omenta of, 1254 
 parietal, 1247 
 structure of, 1245 
 surgical anatomy of, 1264 
 visceral, 1247 
 Peritracheo-bronchial glands, 
 
 812 
 Perivascular lymph-spaces, 772 
 Permanent teeth, 1196 
 development of, 1208 
 eruption of, 1209 
 superadded, 1208 
 Peroneal artery, 717 
 anterior, 718 
 branches of, 718 
 peculiarities of, 718 
 posterior, 718 
 relations of, 718 
 groove, 245 
 nerve, 1016 
 spine, 243 
 tubercle, 243 
 vein, 578 
 Peroneus brevis muscle, 540 
 longus muscle, 539 
 tertius muscle, 534 
 Perpendicular line of ulna, 188 
 plate of ethmoid, 100 
 of palate bone, 117 
 Pes accessorius, 890 
 anserinus, 1045 
 of crus cerebri, 907 
 hippocampi, 890 
 Petit, canal of, 1130 
 
 triangle of, 435 
 Petro-mastoid portion of tem- 
 poral bone, 91 
 -occipital fissure, 128 
 
 suture, 75, 133 
 -sphenoidal fissure, 128 
 
 suture, 136 
 -squamous sinus, 739 
 
 suture, 88 
 -tympanic fissure, 84, 1152 
 Petrosal nerve, deep, 1073 
 great deep, 1034 
 
 superficial, 1034 
 large deep, 1034, 1073 
 superficial, 1034 
 process, 93 
 sinus, inferior, 742 
 superior, 742 
 Petrous, ganglion, 1056 
 branches of, 1056 
 portion of internal carotid 
 artery, 620 
 of temporal bone, 136 
 Peyer's glands, 1296 
 
 patches, 1296 
 Phalanges of foot, 252 
 
 articulations of, 252, 359 
 attachment of muscles of, 
 
 252 
 development of, 254 
 of hand, 204 
 
 articulations of, 204, 325 
 attachment of muscles to, 
 
 204 
 development of, 206 
 ligaments of, 325 
 Pharyngeal aponeurosis, 402, 
 1223 
 
INDEX 
 
 1585 
 
 Pharyngeal artery, ascending, 
 610 
 branches of, 610 
 surgical anatomy of, 611 
 branch of pneumogastric nerve 
 
 1060 
 bursa, 1224 
 glands, 1222 
 nerve, 1036, 1057 
 
 plexus, 1057 
 portion of tongue, 1087 
 region, muscles of, 400 
 
 dissection of, 400 
 ring, lymphatic, 1224 
 spine, 73, 135 
 tonsil, 1221, 1224 
 tubercle, 73 
 veins, 730 
 
 plexus of, 730 
 Fharyngo-epiglottic fold, 1222 
 
 -glossus muscle, 398 
 Pharynx, 1220 
 
 aponeurosis of, 1223 
 arteries of, 610 
 fibrous coat of, 1223 
 isthmus of, 1221 
 laryngeal part, 1222 
 lymphatic vessels of, 782 
 mucous coat of, 1223 
 muscles of, 400 
 nasal part, 1221 
 oral part, 1221 
 structure of, 1222 
 surgical anatomy of, 1224 
 vault of, 1221 
 Philtrum, 380 
 Phleboliths, 762 
 Piirenic arteries, inferior, 680 
 superior, 644 
 ganglion, 1084 
 hernia, 427 
 
 nerve, 974 • 
 
 plexus of nerves, 1084 
 surface of spleen, 1354 
 veins, 767 
 Plirenico-costal sinus, 1386, 1414 
 
 -pleural fascia, 1386 
 Phreno-colic ligament, 1259 
 -pericardial ligament, 559 
 Physiological retina, 1120 
 Pia mater of brain, 854 
 arteries of, 856 
 nerves of, 857 
 veins of, 856 
 of cord, 835 
 
 structure of, 835 
 Pigmentary layer of retina, 1127 
 Pillars of fauces, 1211 
 of fornix, anterior, 895 
 posterior, 896 
 Pineal body, 905 
 gland, 905 
 
 peduncles of, 895, 906 
 structure of, 906 
 recess, 903 
 stria;, 904 
 Pinna of ear, 1144 
 arteries of, 1147 
 cartilage of, 1146 
 integument of, 1146 
 ligaments of, 1146 
 lymphatics of, 1147 
 muscles of, 1147 
 nerves of, 1148 
 structure of, 1146 
 veins of, 1147 
 Pisiform bone, 197 
 
 articulations of, 197 
 attachment of muscles to, 
 
 197 
 surfaces of, 197 
 
 Pit of stomach, 165 
 Pituitary body, 882 
 structure of, 883 
 fossa, 93 
 membrane, 1100 
 Pivot-joint, 265 
 Plane, nuchal, 72 
 Plantar arch, 719 
 
 arteries, external, 720 
 brandies of, 720 
 surface marking of, 720 
 surgical anatomy of, 720 
 internal, 719 
 
 branches of, 720 
 surface marking of, 720 
 surgical anatomy of, 720 
 fascia, 542 
 
 surgical anatomy of, 543 
 ligaments, long, 353 
 superficial, 353 
 short, 353 
 nerves, external, 1016 
 
 internal, 1015 
 region, muscles of, 544 
 
 dissection of, 544, 
 veins, 758 
 Plantaris muscle, 536 
 Planum temporale, 76 
 Plate, cribriform of ethmoid, 99 
 horizontal, of palate bone, 116 
 perpendicular, of ethmoid, 100 
 
 of palate bone, 117 
 pterygoid, external, 96 
 
 internal, 96 
 vertical, of ethmoid, 100 
 of palate bone, 117 
 Platysma myoides muscle, 386 
 Pleura;, 1382 
 
 arteries of, 1387 
 cavity of, 1382 
 cervical, 1385 
 costal, 1385 
 diaphragmatic, 1386 
 dome of, 1385 
 lymphatics of, 1387 
 mediastinal, 1385 
 nerves of, 1387 
 parietal layer of, 1385 
 pericardial, 1385 
 pulmonary, 1385 
 reflections of, 1384 
 structure of, 1387 
 surgical anatomy of, 1387 
 veins of, 1387 
 visceral layer of, 1382 
 Pleural lymphatics, 815 
 
 sacs, 1236 
 Pleuroperitoneal cavity, 123G 
 riexus, Auerbachi, 1299 
 interlobular, 1338 
 of nerves, abdominal aortic, 
 1080, 1085 
 annular, 1111 
 brachial, 977 
 cardiac, 1081 
 anterior, 1081 
 deep, 1081 
 great, 1081 
 superficial, 1081 
 carotid, internal, 1073 
 cavernous, 1073 
 cervical, 972 
 
 posterior, 900 
 choroid, 899 
 cceliac, 1061, 1084 
 colic, left, 1085 
 coronarv, 1085 
 cystic, i085 
 dental, superior, 1033 
 diaphragmatic, 1086 
 epigastric, 1083 
 
 100 
 
 Plexus of nerves, fundamental, 
 1111 
 gastric, 1085 
 gastro-duodenal, 1085 
 -epiploic, 1085 
 left, 1085 
 hajmorrhoidal, inferior, 1086 
 
 superior, 1085 
 hepatic, 1085 
 hypogastric, 1080, 1085 
 infraorbital, 1049 
 intra-epithelial, 1111 
 lumbar, 998 
 lumbo-sacral, 998 
 magnus profunda, 1081 
 mesenteric, inferior, 1085 
 
 superior, 1085 
 oesophageal, 1059, 1061, 
 
 1082 
 ovarian, 1084 
 pancreatic, 1085 
 pancreatico-duodenal, 1085 
 patellar, 1004 
 pelvic, 1086 
 pharyngeal, 1057 
 phrenic, 1084 
 prostatic, 1086 
 pudendal, 1009 
 pudic, 1009 
 pulmonary, 1059 
 anterior, 1082 
 posterior, 1081 
 pyloric, 1085 
 renal, 1061, 1084 
 sacral, 1009, 1086 
 sciatic, 1009 
 sigmoid, 1085 
 solar, 1083 
 spermatic, 1084 
 splenic, 1061, 1085 
 subclavian, 1077 
 subepithelial, 1111 
 suprarenal, 1084 
 thoracic aortic, 1079 
 tympanic, 1057 
 uterine, 1086 
 utero-vaginal, 1086 
 vaginal, 1086 
 vertebral, 1077 
 vesical, 1086 
 of veins, infraclavicular, 792 
 palmar, 745 
 pharyngeal, 730 
 prostatic, 761 
 prostatico-vesical, 761 
 pterygoid, 727 
 spermatic, 765 
 spinal, 753 
 
 subpleural mediastinal, 644 
 uterine, 763 
 vaginal, 763 
 venous, interspinous, 732 
 
 on thyroid body, 751 
 vesical, inferior, 762 
 superior, 761 
 Plica, epigastrica, 1520 
 fimbriata, 1087 
 gubernatrix, 1461 
 hypogastrica, 1519 
 salpingopalatine, 1221 
 salpingopharyngea, 1221 
 semilunaris, 1140 
 sublingualis, 1217 
 triangularis, 1213 
 urachi, 1519 
 vascularis, 1461 
 Pneumatic spaces, 1103 
 Pneumogastric nerve, 1057 
 ganglion of root of, 1059 
 surgical anatomy of, 1062 
 of trunk of," 1059 
 
1586 
 
 INDEX 
 
 Polyaxonic cells, 821 
 Polymazia, 1505 
 Polythelia, 1505 
 Pomum Adami, 1362 
 Pons Tariiii, 883 
 Varolii, 883, 922 
 base of, 922 
 fibres of, 923 
 gray matter of, 924 
 structure of, 922 
 surfaces of, 922 
 veins of, 736 
 Pontal arteries, 639 
 Ponticulus, 1146 
 of Arnold, 939 
 Popliteal artery, 707 
 branches of, 710 
 contents of, 708 
 peculiarities of, 709 
 position of contained parts, 
 
 708 
 surface marking of, 709 
 surgical anatomy of, 709 
 groove, 226 
 line, 235 
 
 lymphatic glands, 795 
 nerve, external, 1016 
 internal, 1014 
 branches, 1014 
 notch, 234 
 space, 707 
 
 boundaries of, 707 
 dissection of, 707 
 vein, 758 
 Popliteus muscle, 537 
 Pore, gustatory, 1090 
 Portal sinus, 769 
 vein, 769 
 
 system of, 768 
 Portio-dura of seventh nerve, 
 1044 
 ganglia of, 1045 
 -mollis of auditory nerve, 1045 
 Post-anal gut, 1242 
 -central gyrus, 876 
 lobes, 878 
 sulcus, inferior, 875 
 superior, 875 
 -clival, fissure, 928 
 -glenoid process, 84 
 -gracile fissure, 930 
 -limbic fissure, 871 
 -nodular fissure, 930 
 -parietal convolution, 876 
 -pharyngeal gland, 785 
 -pyramidal fissure, 930 
 Posterior auricular artery, 609 
 nerve, 1047 
 vein, 727 
 bicipital ridge, 179 
 calcaneo-astragaloid ligament, 
 
 352 
 carpal arch, 659 
 
 artery of ulnar, 663 
 cerebellar notch, 926 
 cerebral artery, 640 
 cervical plexus, 970 
 chondro-stemal ligament, 288 
 
 -xiphoid ligament, 288 
 choroid artery, 640 
 clinoid process, 93, 132 
 commissure of brain, 903 
 
 of cord, 839 
 common ligament, 270 
 condyloid foramen, 73, 133, 
 136 
 fossa, 136 
 comu of lateral ventricle, 889 
 
 bulb of, 889 
 coronary plexus, 1081 
 costo-transverse ligament, 286 
 
 Posterior costo-xiphoid ligament, 
 288 
 crescentic lobe, 928 
 crucial ligament, 337 
 deep cervical vein, 733 
 dental canals, 106 
 divisions of cervical nerves, 968 
 of coccygeal nerve, 1008 
 of dorsal nerves, 993 
 
 branches, cutaneous, 
 993 
 external, 993 
 internal, 993 
 of lumbar nerves, 997 
 
 branches, external, 998 
 internal, 998 
 of sacral nerves, 1006 
 lower, 1007 
 upper, 1006 
 
 branches, external, 
 1006 
 internal, 1006 
 ethmoidal canal, 82, 100 
 cells, 101, 145 
 foramen, 82, 130, 141 
 sinuses, 101 
 external jugular vein, 728 
 of thoracic nerves, 993 
 branches, cutaneous, 
 993 
 external, 993 
 internal, 993 
 extremity of ribs, 160 
 head of, 160 
 neck of, 160 
 tuberosity of, 161 
 femoral region, muscles of, 529 
 fontanelle, 75, 103 
 fossa of skull, 132 » 
 
 gluteal line, 207 
 humeral region, muscles of,477 
 inferior cerebellar artery, 639 
 
 spinous process of ilium, 210 
 intercostal veins, 752 
 internal frontal artery, 627 
 interosseous artery of ulna, 663 
 
 nerve, 991 
 intersternal ligament, 290 
 intertrochanteric line, 223 
 ligament of incus, 1161 
 of Winslow, 335 
 of wrist, 318 
 longitudinal ligament, 270 
 
 spinal veins, 755 
 median fissure, 838 
 
 ganglionic arteries, 640 
 mediastinal arteries, 666 
 
 glands, 812 
 mediastinum, 1389 
 medullary velum, 943 
 meningeal artery, 638 
 nares, 142, 1098 
 nasal spine, 116, 135, 143 
 occipito-atlantal ligament, 276 
 
 -axial ligament, 278 
 olfactory lobule, 881 
 orbital convolution, 874 
 palatine arterv, 615 
 canal, 107, 116 
 canals, accessory, 116, 135 
 foramen, 135 
 nerve, 1035 
 perforated lamina, 910 
 
 space, 883 
 peroneal artery, 718 
 pillar of soft palate, 1212 
 pillars of fornix, 896 
 pubic ligament, 296 
 pulmonary nerves, ]061 
 
 plexus, 1059, 1061, 1081 
 radial carpal artery, 659 
 
 Posterior, radio-ulnar ligament, 
 315 
 region, muscles of, 486 
 recurrent tibial artery, 713 
 root of spinal nerves, 965 
 sacral foramina, 63 
 sacro-coccygeal ligament, 2^4: 
 -iliac ligament, 292 
 -sciatic ligament, 292 
 scapular artery, 642 
 nerve, 982 
 
 region, muscles of, 472 
 semicircular canal, 1165 
 spinal artery, 639 
 sterno-clavicular ligament, 29S 
 
 -costal ligament, 288 
 subarachnoid space, 852 
 surface of liver, 1329 
 of stomach, 1270 
 superior dental nerves, 1032 
 
 spinous process of ilium, 21(> 
 temporal artery, 611, 640 
 
 diploic vein, 734 
 thoracic nerve, 983 
 tibial artery, 716 
 nerve, 1014 
 veins, 758 
 tibio-fibular region, muscles of, 
 534 
 -tarsal ligament, 347 
 triangle of neck, 618 
 tubercle of cervical vertebra, 
 
 50 
 tympano-malleolar ligament, 
 
 1156 
 ulnar recurrent artery, 662 
 
 vein, 745 
 vertebral vein, 733 
 wall of tympanum, 1152 
 Postero-lateral fontanelles, 103 
 ganglionic arteries, 640 
 tract, 843 
 -median ganglionic arteries, 
 628 
 tract, 843 
 Pouch, Douglas's, 1490 
 of Prussak, 1162 
 recto-vaginal, 1490 
 utero-vesical, 1487, 1490 
 Poupart's ligament, 436, 1515 
 Prsecentral gyrus, 872 
 Pre-anal fibres of levator ani, 453 
 -aortic glands, 800 
 -auricular lymphatic glands, 
 
 781 
 -central lobe, 878 
 sulci, 868 
 sulcus, 872 
 inferior, 872 
 superior, 872 
 -clival fissure, 928 
 -laryngeal glands, 787 
 -maxillarj' bones, 110 
 -occipital notch, 869 
 -patellar bursa, 340, 518 
 Precuneus of lobe of brain, 87ft 
 Prepatellar bursa, 518 
 Prepuce of clitoris, 1479 
 
 of penis, 1455 
 Pre-occipital notch, 869 
 -pyramidal fissure, 930 
 -sternal notch, 157 
 -sternum, 157 
 -tracheal fascia, 388 
 
 glands, 787 
 -vertebral fascia, 388 
 Prickle cells, 1109 
 Primitive fibrillar of Schultze, 822 
 
 sheath of Schwann, 822 
 Primordial ova, 1502 
 Princeps hallucis artery, 716 
 
INDEX 
 
 1587 
 
 Princeps pollicis artery, 660 
 Process or processes, acromion, 
 
 174 
 alveolar, 140 
 angular, 80 
 
 external, 140 
 
 internal, 140 
 of atlas, 51 
 auditory, 88 
 basilar, 73 
 of calcaneous, greater, 243 
 
 lesser, 243 
 clinoid, anterior, 131 
 
 middle, 93, 132 
 
 posterior, 93, 132 
 cochleariform, 91, 1153 
 condyloid of lower jaw, 125 
 coracoid, 175 
 
 of jaw, 125 
 
 of ulna, 186 
 costal, 50 
 
 ethmoidal, of inferior turbin- 
 ated, 120 
 falciform, 515 
 hamular, of lachr\'Tnal, 113 
 
 of sphenoid, 96 
 of inferior turbinated bone, 120 
 of Ingrassias, 96 
 jugular, 73 
 
 lachrymal, of inferior turbin- 
 ated, 120 
 of malar bone, 114 
 mammillary, of lumbar verte- 
 
 brje, 57 
 mastoid, 86, 138 
 mental, 122, 140 
 nasal, 80 
 
 odontoid, of axis, 52 
 olecranon, 186 
 olivary, 93, 131 
 orbital, 118 
 
 of malar, 114 
 of palate bone, 117 
 petrosal, 93 
 post-glenoid, 84 
 pterygoid, of palate bone, 117 
 
 of sphenoid bone, 96 
 sphenoidal, 1097 
 
 of palate, 118 
 spinous, of ilium, 210 
 
 of sphenoid, 95 
 
 of tibia, 233 
 stylohyal, 92 
 styloid, of fibula, 237 
 
 of temporal bone, 90 
 
 of ulna, 189 
 of superior maxillary, 109, 110 
 tympanohyal, 92 
 unciform, 200 
 
 of ethmoid, 100 
 vaginal, of sphenoid, 95 
 
 of temporal bone, 89 
 of vertebrae, articular, 49 
 zygomatic, 84 
 Processus brevis of malleus, 1159 
 cochleariformis, 91, 1153 
 gracilis of malleus, 1158 
 tubarius, 1155 
 vaginalis, 1461 
 Proctodseum, 1242 
 Profunda artery, inferior, 656 
 
 superior, 655 
 femoris artery, 704 
 
 vein, 759 
 Projection fibres of cerebrum, 
 914, 932 
 centrifugal, 914 
 centripetal, 914 
 motor, 914 
 sensory, 914 
 Prominentia styloidefE, 1153 
 
 Promontory of sacrum, 61 
 
 of tympanum, 1152 
 Pronator quadratus muscle, 483 
 radii teres muscle, 479 
 
 surgical anatomy of, 
 479 
 ridge, 188 
 Pro-otic portion of temporal 
 
 bone, 91 
 Prosencephalon, 864 
 Prostate gland, 1447 
 apex of, 1451 
 arteries of, 1452 
 base of, 1451 
 capsule of, 1449 
 isthmus of, 1451 
 lobes of, 1451 
 lymphatics of, 1452 
 
 vessels of, 803 
 nerves of, 1452 
 sheath of, 1449 
 structure of, 1452 
 surfaces of, 1451 
 surgical anatomy of, 1452 
 veins of, 1452 
 Prostatic ducts, orifices of, 1442 
 plexus of nerves, 1086 
 
 of veins, 761 
 portion of rectvun, 1313 
 
 of urethra, 1441 
 secretion, 1452 
 sinus, 1442 
 vesicle, 1442 
 Prostatico-vesical plexus, 761 
 
 surgical anatomy of, 762 
 Protovertebrse, 1235 
 Protuberance, mental, 122 
 occipital, external, 71, 136 
 internal, 73 
 Prussak, pouch of, 1162 
 Psalterium, 896 
 Pseudostomata, 1246 
 Psoas magnus muscle, 509 
 
 parvus muscle, 500 
 Pterion, 137 
 
 ossicle, 83, 103 
 Pterygoid artery, 614 
 canal, 135 
 depression, 125 
 fissure, 96 
 fossa of jaw, 115 
 of sphenoid, 96 
 muscles, external, 383 
 
 internal, 383 
 nerve, external, 1037 
 
 internal, 1037 
 notch, 96 
 plate, external, 96 
 
 internal, 96 
 plexus of veins, 727 
 process of palate bone, 117 
 
 of sphenoid bone, 96 
 ridge, 95, 137 
 tubercle, 97 
 Pterygo-mandibular ligament, 
 380 
 region, dissection of, 383 
 muscles of, 383 
 
 actions of, 384 
 nerves of, 384 
 -maxillary fissure, 139 
 
 ligament, 380 
 -palatine artery, 616 
 canals, 135 
 fossa, 139 
 groove, 116 
 nerve, 1036 
 Pubic arch, 217 
 
 ligament, anterior, 296 
 inferior, 296 
 posterior, 296 
 
 Pubic ligament, superior, 296 
 portion of fascia lata, 1528 
 surface of bladder, 1434 
 Pubis, 212 
 angle of, 212 
 body of, 212 
 ramus of, ascending, 213 
 
 descending, 213 
 spine of, 
 Pubo-capsular ligament, 328 
 -coccygeus muscle, 452 
 -femoral ligament, 328 
 -prostatic ligament, 1435, 
 
 1451 
 -vesical ligament, 1435 
 muscle, 1437 
 Pudendal nerve, inferior, 1011 
 plexus of nerves, 1009 
 sht, 1478 
 Pudendum, 1477 
 Pudic artery, accessory, 690 
 external, deep, 704 
 superficial, 704 
 internal, in female, 692^ 
 in male, 689 
 
 branches of, 690 
 pecuUarities of, 690 
 surgical anatomy of, 
 690 
 nerve, 1011 
 
 plexus of, 1009 
 vein, internal, 760 
 Pulmonary alveoli, 1378 
 artery, 587 
 left, 587 
 opening of, 569 
 right of, 587 
 branches of thoracic portion 
 
 of gangliated cord, 1079 
 lymphatics, 815 
 nerves, anterior, 1061 
 
 posterior, 1061 
 pleura, 1385 
 plexus, 1081 
 
 anterior, 1059, 1061, 1082 
 posterior, 1059, 1061, 1081 
 sinuses of Valsalva, 571 
 veins, 723 
 Pulmonic semilunar valves, 571 
 Pulp, dental, 1200 
 Pulvinar of optic thalamus, 904 
 Puncta lacrimalia, 1142 
 
 vasculosa, 885 
 Punctum jJacrimale, 1138 
 Pupil of eye, 417 
 Pupillary margin, 1117 
 Purkinje, axis-cylinder of, 822 
 cells of, 825 
 corpuscles of, 936 
 Putamen, 892 
 
 Pyloric artery, inferior, 673 
 superior, 673 
 glands, 1277 
 orifice of stomach, 1270 
 plexus, 1085 
 
 portion of stomach, 1269 
 sphincter, 1272 
 valve, 1272 
 Pylorus, 1270 
 
 antrum of, 1271 
 Pyramids of Ferrein, 1417 
 of Lalouette, 1403 
 lobe of cerebellum, 931 
 of Malpighi, 1417 
 of medulla, 939 
 of tympanum, 1153 
 of vestibule of ear, 1164 
 Pyramidal decussation, 947 
 tract, crossed, 842 
 direct, 842 
 luicrossed, 842 
 
1588 
 
 INDEX 
 
 Pyramidalis, muscle, 444 
 
 nasi muscle, 375 
 Pyriformis muscle, 524 
 bursa of, 525 
 
 Quadrate lobe of liver, 1332 
 
 lobule, 875 
 Quadratus femoris muscle, 527 
 
 lumborum, fascia of, 449 
 muscle, 449 
 
 Tnenti muscle, 378 
 relations of, 378 
 Quadriceps extensor muscle, 516 
 Quadrigeminal bodies, 911 
 Quadrilateral, muscles, 362 
 
 Radial artery, 657 
 branches of, 659 
 peculiarities of, 658 
 relations of, 657 
 ^surface marking of, 658 
 surgical anatomy of, 658 
 ifossa, 181 
 
 head of humerus, 181 
 nerve, 991 
 
 recurrent artery, 659 
 region, muscles of, 484, 495 
 
 dissection of, 484 
 vein, 745 
 Radialis indicis artery, 660 
 Radiations, optic, 905 
 Radio-carpal articulations, 317 
 surface form of, 318 
 surgical anatomy of, 318 
 -ulnar articulation, 313 
 inferior, 315 
 
 surface form of, 317 
 middle, 314 
 superior, 314 
 
 surface form of, 314 
 surgical anatomy of, 
 314 
 ligaments, annular, 314 
 anterior, 315 
 oblique, 314 
 orbicular, 314 
 posterior, 315 
 round, 314 
 region, anterior, muscles of, 
 479 
 surgical anatomy of, 
 484 
 posterior, muscles of, 486 
 surgical anatomy of, 
 491 
 Radius, 190 
 
 articulations of, 192 
 attachment of muscles to, 
 
 192 
 development of, 192 
 lower extremitv of, 191 
 shaft of, 190 
 
 borders of, 190, 191 
 surfaces of, 191 
 sigmoid cavity of, 191 
 structure of, 192 
 .surface form of, 192 
 surgical anatomy of, 192 
 upper extremity of, 190 
 Rami of lower jaw, 124 
 Ramus of ischium, ascending, 
 212 
 descending, 211 
 of pubis, ascending, 213 
 descending, 213 
 
 Ranine artery, 604 
 
 vein, 729 
 Raph6 of corpus callosum, 887 
 of medulla, 951 
 of palate, 1211 
 of perineum, 1537 
 of scrotum, 1463 
 of tongue, 1087 
 Receptaculum chyli, 775 
 Recess, epitympanic, 87 
 Recessus cochlearis of Reichert, 
 
 1164 
 Reciprocal reception, articula- 
 tion by, 265 
 Rectal columns, 1319 
 glands, 809 
 valves, 1318 
 Recto-urethralis muscle, 454 
 -uterinus muscle, 1491 
 -vaginal fold, 1490 
 
 pouch, 1314, 1490 
 -vesical fascia, 1546 
 pouch, 1314 
 Rectum, 1312 
 
 areolar coat of, 1318 
 arteries of, 1320 
 curves of, 1313 
 lymphatics of, 809, 1321 
 mucous membrane of, 1318 
 muscular coat of, 1317 
 nerves of, 1322 
 prostatic portion of, 1313 
 sacrococcygeal portion of, 
 
 1313 
 serous coat of, 1316 
 submucous coat of, 1318 
 surface form of, 1323 
 surgical anatomy of, 1325 
 supports of, 1315 
 structure of, 1316 
 veins of, 1321 
 Rectus abdominis muscle, 442 
 capitis anticus major muscle, 
 406 
 minor muscle, 407 
 lateralis muscle, 407 
 posticus major muscle, 422 
 minor muscle, 422 
 femoris muscle, 516 
 oculi muscle, external, 373 
 inferior, 373 
 internal, 373 
 superior, 373 
 Recurrent artery, palmar, 660 
 radial, 659 
 tibial, anterior, 713 
 
 posterior, 713 
 ulnar, anterior, 662 
 posterior, 662 
 laryngeal nerve, 1060 
 Red nucleus nerve-path, 960 
 Reflections of pleura;, 1384 
 Reflex nerve-paths, 963 
 Refracting media of eye, 1128 
 Reichert, recessvis cochlearis of, 
 
 1164 
 Reil, island of, 867, 878 
 
 sulcus of, limiting, 867, 878 
 Reissner, membrane of, 1172 
 Remak, fibres of, 823 
 Renal artery, 678 
 inferior, 1423 
 blood-vessels, 1422 
 impression of liver, 1329 
 plexus, 1061, 1084 
 surface of spleen, 1354 
 veins, 767 
 
 zone of Hvrtl, exsanguinated, 
 1423 
 Reservoir of Pecquet, 775 
 Respiration, muscles of, 431 
 
 Respiration, organs of, I36I 
 Respiratory nerve of Bell, ex- 
 ternal, 983 
 internal, 974 
 Restiform body of medulla, 941 
 Rete testis of Haller, 1471 
 Retina, 1120 
 
 nerve-fibres of, 1122 
 physiological, 1120 
 
 pigmentary layer of, 1127 
 
 rods of, 1125 
 structure of, 1121 
 supporting framework of, 1127 
 Retinacula of capsular ligament 
 of hip, 327 
 
 patellae mediale, 517 
 Retrahens auriculam muscle, 309 
 Retro-aortic glands, 800 
 
 -csecal fossa, 1263 
 
 -colic fossa?, 1263 
 
 -crural glands, 798 
 
 -duodenal fossa, 1262 
 
 -peritoneal fossa;, 12C0 
 space, 1247 
 
 -pharyngeal glands, 785 
 space, 388, 1220 
 
 -rectal space, 1314 
 
 -renal fascia, 1412 
 
 -sternal glands, 810 
 Retzius, brown stria? of, 1204 
 
 fundiform Ugament of, 541 
 
 space of, 1434 
 Rhinencephalon, 880 
 Rhodopsin, or visual purple, 1120 
 Rhombencephalon, 922 
 Rhomboid fossa, inferior, 840 
 
 impression, 169 
 
 ligament, 298 
 Rhomboidal muscles, 363 
 Rhomboideus major muscle, 414 
 
 minor muscle, 414 
 Ribes, ganglion of, 1067 
 Ribs, 159 
 
 anterior extremity of, 161 
 
 articulations of, 283 
 
 attachment of muscles to, 164 
 
 cervical, 53 
 
 common characters of, 160 
 
 development of, 163 
 
 false, 159 
 
 floating, 160 
 
 peculiar, 162 
 
 posterior extremity of, 160 
 
 shaft of, 161 
 
 structure of, 163 
 
 true, 159 
 Ridges, bicipital, 179 
 
 epicondvlic, 179 
 
 gluteal, '224 
 
 mylo-hyoid, 123 
 
 naso-labial, 377 
 
 obUque, of trapezium, 198 
 of ulna, 188 
 
 pectoral, 179 
 
 pronator, 188 
 
 pterygoid, 95, 137 
 
 superciliary, 80 
 
 supracondylar, external, 179 
 internal," 180 
 
 supraorbital, 140 
 
 temporal, 76, 80 
 
 trapezoid, 169 
 Riedel's lobe of liver, 1336 
 Right ascending lumbar vein, 
 752 
 
 azygos vein, 752 
 
 bronchus, 1376 
 
 cardiac vein, 771 
 
 colic artery, 675 
 
 coronary artery, 590 
 plexus, 1081 
 
INDEX 
 
 1589 
 
 Right innominate vein, 750 
 
 juxta-aortic glands, 800 
 
 lobe of liver, 1332 
 
 lymphatic duct, 778 
 
 superior intercostal vein, 752 
 Rima glottidis, 1369 
 Ring, abdominal, internal, 446 
 
 crural, 437, 1532 
 
 femoral, 437, 509, 1532 
 
 fibrous, of heart, 574 
 
 muscle of Miiller, 1116 
 Risorius muscle, 380 
 Risus sardonicus, 381 
 Rivinus, ducts of, 1217 
 
 notch of, 1151 
 Rod-bipolars, 1125 
 
 -cells, 1126 
 
 -fibre, 1126 
 
 -granules, 1125 
 Rolandic angle, 867 
 Rods of Corti, 1174 
 
 of retina, 1125 
 Rolando, fasciculus of, 941 
 
 fissure of, 867 
 
 funiculus of, 941 
 
 sulcus of, central, 867 
 
 tubercle of, 941 
 Roots of auditory nerve, 1050 
 
 of cervical nerves, 968 
 
 of dorsal nerves, 993 
 
 of eighth nerve, 1050 
 
 of fifth nerve, ascending, 948, 
 1026 
 descending, 1026 
 
 of lumbar nerve, 997 
 
 of lung, 1394 
 
 of penis, 1454 
 
 of pneumogastric nerve, gan- 
 glion of, 1059 
 
 of sacral nerves, 1006 
 
 of spinal nerves, 965 
 anterior, 965 
 dorsal, 965 
 posterior, 965 
 ventral, 965 
 
 of thoracic nerves, 993 
 
 of tongue, 1087 
 Rosenmiiller, fossa of, 1221 
 
 gland of, 795 
 accessory, 1141 
 
 organ of, 1499 
 Rostrum of corpus callosum, 
 886 
 
 of sphenoid bone, 94, 135 
 Rotary joint, 265 
 Rotatores spiiue muscle, 421 
 Round ligament, artery of, 688 
 of liver, 1334 
 of uterus, 1491 
 Roux's amputation of foot, 256 
 Rudimentary organ of Jacobson, 
 
 1100 
 Rudinger, dilator tubie mascle 
 
 of, 1155 
 Ruffini's nerve-endings, 828 
 Rugfe of scrotum, 1462 
 
 of stomach, 1275 
 
 of vagina, 1484 
 Ruysch, tunic of, 1113 
 
 S 
 
 Sacs, abdominal, 1236 
 
 dental, 1206 
 
 lachrymal, 1142 
 
 pericardial, 1236 
 
 pleural, 1236 
 Saccule of vestibule. 1170 
 Sacculi alveolares, 1378 
 Sacculus laryngis, 1371 
 
 Sacral arterv, lateral, 693 
 middle," 681 
 canal, 64 
 cornua, 62 
 foramina, anterior, 62 
 
 posterior, 63 
 groove, 63 
 
 lymphatic glands, 799 
 nerve, 1006 
 
 division of, anterior, 1007 
 
 posterior, 1006 
 roots of, 1006 
 plexus, 1009, 1086 
 portion of gangliated cord, 
 
 1080 
 veins, lateral, 760 
 middle, 764 
 Sacro-coccygeal ligament, ante- 
 rior, 294 
 lateral, 295 
 posterior, 294 
 portion of rectum, 1313 
 symphisis, 66 
 -ihac ligament, anterior, 292 
 interosseous, 292 
 long, 292 
 obUque, 292 
 posterior, 292 
 short 292 
 -lumbalis muscle, 419 
 -sciatic foramen, great, 211, 
 294 
 inferior, 294 
 lesser, 211, 294 . 
 superiorj 294 
 ligament, anterior, 293 
 great, 292 
 lesser, 293 
 posterior, 292 
 notches, 217 
 great, 210 
 lesser, 211 
 -uterine ligaments, 1490 
 -vertebral angle, 61 
 Sacrum, 61 
 ala of, 64 
 apex of, 64 
 articulations of, 65 
 attachment of muscles to, 65 
 base of, 64 
 development of, 64 
 differences in the male and 
 
 female, 64 
 peculiarities of, 64 
 promontory of, 61 
 structure of, 64 
 surfaces of, 61 
 tuberosity of, 63 
 Saddle-joint, 265 
 Sagittal axis, 1106 
 sulcus, 73, 80 
 suture, 78, 127 
 Salivary glands, 1214 
 structure of, 1217 
 surgical anatomy of, 1224 
 Salpingo-palatine fold, 1221 
 -pharyngeal fold, 1221 
 -pharyngeus muscle, 405 
 Salter, incremental lines of, 
 
 1203 
 Santorini, cartilages of, 1365 
 comical tubercle of, 1368 
 fissures of, 1146, 1148 
 muscle of, 380 
 Saphenous gland, externa,!, 795 
 opening, 514, 1529 
 nerve, internal, 1005 
 
 long, 1005 
 vein, external, 756 
 internal, 756 
 long, 756 
 
 Saphenous vein, short, 756 
 
 surgical anatomy of, 757 
 Sarcolemma, 361 
 Sardonic laugh, 381 
 Sartorius muscle, 516 
 
 nerve to, 1005 
 Scala media, 1172 
 
 tympani of cochlea, 1168 
 vestibuli of cochlea, 1168 
 Scalenus muscles, anticus, 408 
 medius, 408 
 posticus, 409 
 Scalp, skin of, 366 
 Scapha, fossa of. 1145 
 Scaphoid bone of foot, 246 
 articulations of, 247 
 attachment of muscles to, 
 
 247 
 surfaces of, 246 
 tuberositv of, 246 
 of hand, 195 
 
 articulations of, 196 
 attachment of muscles to, 
 
 196 
 surfaces of, 196 
 fossa, 97, 135, 1145 
 Scapula, 171 
 angles of, 174 
 articulations of, 176 
 attachment of muscles to, 176 
 base of, 174 
 borders of, 174 
 development of, 175 
 dorsum of, 172 
 head of, 174 
 Ugaments of, 301 
 spine of, 172 
 structure of, 175 
 surface form of, 176 
 surgical anatomy of, 177 
 venter of, 171 
 Scapular arteries, posterior, G42 
 glands, 790 
 nerve, posterior, 982 
 notch, great, 173 
 region, anterior, muscles of, 
 471 
 dissection of, 471 
 posterior, muscles of, 472 
 dissection of, 472 
 Scapulo-clavicular articulation, 
 
 299 
 Scarf skin, 1181 
 Scarpa, fascia of, 433 
 
 foramina of, 110, 135, 1036 
 membrane of, 1152 
 nerve of, 1036 
 triangle of, 516, 697 
 Schachowa, spiral tube of, 1419 
 Schindylesis, 264 
 Schlemm, canal of, 1108, 1111 
 
 ligament, 305 
 Schneiderian membrane, 1100 
 Schreger, concentric lines of, 1203 
 ScKultze, primitive fibrillae of, 822 
 Schwann, nucleated sheath of, 
 822 
 primitive sheath of, 822 
 white substance of, 822 
 Sciatic artery, 692 
 nerve, great, 1013 
 
 branches of, 1013 
 small, 1011 
 
 branches of. 1011 
 notch, great, 210 
 plexus, 1009 
 veins, 761 
 Sclera, 1107 
 
 structure of, lipS 
 Scleral sulcus, 1 105 
 Sclerotic coat, 1107 
 
1590 
 
 INDEX 
 
 Scrotal hernia, 1521 
 nerve, long, 1011 
 Scrotum, 1462 
 arteries of, 1465 
 dartos of, 1463 
 integument of, 1463 
 lymphatic vessels of, 801 
 lymphatics of, 1466 
 nerves of, 1466 
 raphe of, 1463 
 rugiB of, 1462 
 septum of, 1463 
 surgical anatomy of, 1469 
 veins of, 1466 
 Sebaceous glands, 1138, 1191 
 Second nerve, 1021 
 Secondary ear-drum membrane, 
 
 1152 
 Segments of Lantermann, 823 
 Sella turcica, 93, 131 
 Semen, 1474 
 
 Semicircular canals, 1165 
 external, 1165 
 horizontal, 1165 
 membranous, 1170 
 posterior, 1165 
 superior, 1165 
 muscles of rectum, 1317 
 Semilunar bone, 196 
 
 articulations of, 197 
 surfaces of, 196 
 fascia, 476 
 fibro-cartilages, 337 
 external, 339 
 internal, 338 
 folds of colon, 1317 
 
 of Douglas, 439, 444 
 ganglion of abdomen, 1084 
 
 of fifth nerve, 1027 
 hiatus, 145, 747 
 lobe of cerebellum, inferior, 
 
 931 
 valves, aortic, 572 
 pulmonic, 571 
 Semimembranosus muscle, 530 
 
 bursa of, 531 
 Seminal duct, 1472 
 vesicles, 1475 
 arteries of, 1476 
 lymphatic vessels of, 804 
 lymphatics of, 1476 
 nerves of, 1476 
 structure of, 1476 
 surgical anatomy of, 1476 
 veins of, 1476 
 Semispinalis colli muscle, 421 
 
 dorsi muscle, 421 
 Semitendinosus muscle, 530 
 Sensory decussation, 947 
 nerve tract, 961 
 projection fibres of cerebrum, 
 914 
 Septo-marginal tract, 844 
 Septum atriorum, 567 
 bronchial, 1380 
 crurale, 1532 
 
 of Cloquet, 509 
 interarticular, 565 
 interventricular, 569 
 lucidum, 889, 896 
 of nose, 142 
 
 cartilage of, triangular, 1097 
 orbital, 1139 
 pectiniforme, 1457 
 of scrotum, 1463 
 of tongue, fibrous, 398 
 trans versum, 1170 
 Serous coat of anal canal, 1316 
 of bladder, 1437 
 of gall-bladder, 1343 
 of large intestine, 1316 
 
 Serous coat of lungs, 1354 
 of rectum, 1316 
 of small intestine, 1290 
 of spleen, 1356 
 of stomach, 1273 
 of vermiform appendix, 
 1304 
 
 covering of ovary, 1501 
 
 pericardium, 560 
 Scrratus magnus muscle, 468 
 
 posticus inferior muscle, 415 
 superior muscle, 415 
 Sertoli, cell of, 1472 
 Sesamoid bones, 257 
 
 cartilage, 1097 
 Seventh nerve, 1044 
 
 surgical anatomy of, 1049 
 Shaft of bone, its structure, 33 
 
 of hair, 1189 
 
 of ribs, 161 
 Sharpey, fibres of, 37 
 Shrapnell, membrana flaccida of, 
 
 1156 
 Sheath, carotid, 388 
 
 dentinal, of Neumann, 1203 
 
 femoral, 509, 1530 
 
 of flexor tendons, fibrous, 545 
 
 granular, of Tomes, 1 202 
 
 nucleated, of Schwann, 822 
 
 primitive, of Schwann, 822 
 
 of prostate, 1449 
 
 of rectus muscles, 443 
 Shin bone, 233 
 Short bones, 33 
 
 calcaneo-cuboid .ligament, 353 
 
 ciliary arteries, 625 
 
 fibre nerve path, 960, 963 
 
 plantar ligament, 353 
 
 sacro-iliac ligament, 292 
 
 saphenous vein, 756 
 Shoulder, fascia of, deep, 470 
 superficial, 470 
 
 girdle, 167 
 
 -joint, articulations of, 303 
 bursai of, 305 
 surface form of, 307 
 surgical anatomj^ of, 307 
 
 muscles of, 470 
 Sibson, aortic vestibule of, 572 
 
 aponeurosis, 1385 
 Sigmoid arteries, 678 
 
 cavity of radius, 191 
 of ulna, 186 
 
 colon, 1311 
 
 flexure of colon, 1311 
 of large intestine, 1300 
 
 fossa, 86 
 
 mesocolon, 1259 
 
 notch of lower jaw, 125 
 
 plexus, 1085 
 
 sinus, 739 
 
 sulcus, 86 
 Sinus or sinuses, air, 82 
 
 ala; parvse, 740 
 
 of aorta, great, 589 
 
 basilar, 743 
 
 cavernous, 739 
 
 circular, 742 
 
 confluence of, 737 
 
 coronary vein, 567, 771 
 
 costo-mediastinal, 1386 
 
 of dura mater, 736 
 
 ethmoidal, 101 
 
 frontal, 80 
 
 of heart, auricle of, left, 568 
 right, 565 
 
 intercavernous, 742 
 
 of jugular vein, external, 728 
 internal, 729 
 
 of kidney, 1415 
 
 laryngeal, 1371 
 
 Sinus or sinuses, lateral, 738 
 longitudinal, inferior, 738 
 
 superior, 78, 130, 736 
 maxillary, 108 
 of Morgagni, 402 ' 
 
 of nose, 80 
 occipital, 739 
 orbital, 118 
 petro-squamous, 739 
 petrosal, inferior, 742 
 
 superior, 742 
 of pericardium, oblique, 560 
 
 transverse, 560 
 phrenico-costal, 1386, 1414 
 pocularis, 1442 
 portal, 769 
 prostatic, 1442 
 pyriformis, 1222, 1368 
 sigmoid, 739 
 spheno-parietal, 740 
 sphenoidal, 94, 143 
 straight, 738 
 tonsillaris, 1222 
 transverse, 743 
 
 pericardial, 560 
 utricularis sacculi, 1170 
 of Valsalva, aortic, 573 
 
 pulmonary, 571 
 venosus, 565 
 Sixth nerve, 1043 
 
 branches of, 1043 
 
 nucleus of, 925 
 
 relations of, 1043 
 
 surgical anatomy of, 
 1044 
 Skeletal muscles, 361 
 Skin, 1178 
 
 appendages of, 1185 
 
 arteries of, 1184 
 
 bone, 233 
 
 cuticle of, 1181 
 
 epidermis, 1181 
 
 folds of, 1178 
 
 furrows, 1179 
 
 horny layer of, 1181 
 
 lymphatics of, 1184 
 
 Malpigliian laj'er of, 1182 
 
 nerves of, 1184 
 
 papillary layer of, 1181 
 
 pigmentation of, 1182 
 
 ridges, 1179 
 
 of scalp, 366 
 
 scarf, 1181 
 
 stratum cylindricum, 1182 
 
 germinativum, 1182 
 
 granulosum, 1182 
 
 lucidum, 1182 
 
 mucosum, 1182 
 
 spinosum, 1182 
 true, 1180 
 veins of, 1184 
 Skull, anterior region of, 139 
 base of, 130 
 at different ages, 102 
 fixed point for measurement of, 
 
 149 
 fossa of, anterior, 130 
 
 infratemporal, 138 
 
 middle, 130 
 
 orbital, 140 
 
 posterior, 132 
 
 pterygo-palatine, 139 
 
 spheno-maxillary, 139 
 
 temporal, 137 
 
 zygomatic, 138 
 lateral regions of, 136 
 sexual differences in, 102 
 surface form of, 147 
 surgical anatomy of, 149 
 tables of, 33 
 
 vitreous, 34 
 
INDEX 
 
 1591 
 
 Skull, vertex of, 129 
 Slender funiculus, 941 
 
 lobe of cerebellum, 931 
 Small coronary vein, 771 
 intestine, 1282 
 
 lymphatic glands of, 807 
 vessels of, 808 
 occipital nerve, 972 
 palatine nerve, 1035 
 sciatic nerve, 1011 
 Socia parotidis, 1215 
 Soft commissure of brain, 903 
 palate, 1211 
 
 aponeurosis of, 1212 
 arches of, 1211 
 arteries of, 1212 
 .xnucoas membrane of, 1212 
 muscles of, 1212 
 nerves of, 1213 
 pillars of, 1211 
 veins of, 1213 
 Solar plexus, 1083 
 Soleus muscle, 535 
 Solitary glands, 1295, 1320 
 Somatopleure, 1236 
 Sommerring, foramen of, 1121 
 
 yellow spot of, 1121 
 Space or spaces, axillary, 645 
 of Bruns, 388 
 -cartilage, 260 
 corneal, 1110 
 epitympanic, 87 
 of Fontana, 1110 
 intercostal, 160 
 interglobular, of Czermak, 
 
 1202 
 Interpeduncular, 882 
 interpleural, 1387 
 mediastinal, 1387 
 ■of Nuel, 1175 
 perichoroidal, 1108 
 perisclerotic, 1103 
 pneumatic, 1103 
 popliteal, 707 
 retro-peritoneal, 1247 
 
 -pharyngeal, 388, 1220 
 of Retzius, 1434 
 suprascleral, 1104 
 suprasternal, 388 
 Special sense, organs of, 1087 
 Spermatic arteries, 679 
 canal, 448, 1517 
 cord, 1466 
 
 arteries of, 1467 
 lymphatics of, 1468 
 nerves of, 1468 
 structure of, 1466 
 surgical anatomy of, 1468 
 veins of, 1467 
 iascia, 1463 
 
 external, 1436, 1514 
 internal, 446 
 middle, 440 
 plexus of nerves, 1084 
 
 of veins, 765 
 vein, 765 
 
 surgical anatomy of, 766 
 ■Spermatids, 1472 
 ^Spermatoblasts, 1472 
 Spermatocytes, 1472 
 Spermatogenesis, 1472 
 Spermatogonia, 1472 
 Spermatozoid, 1472, 1474 
 Spheno-ethmoidal recess, 145 
 -maxillary fLssure, 115, 138 
 
 fossa, 115, 139 
 -palatine arterv, 616 
 foramen, 119, 143 
 ganglion, 1034 
 ner\es, 1032 
 notch, 118 
 
 Spheno-parietal sinus, 740 
 suture, 128 
 -phrenic ligament, 1256 
 Sphenoid bone, 92 
 
 articulations of, 98 
 attachment of muscles to, 
 
 98 
 body of, 92 
 
 surfaces of, 93 
 development of, 97 
 greater wings of, 95 
 circumference of, 95 
 surfaces of, 95 
 hamular process of, 96 
 lesser wings of, 96 
 pterygoid process of, 96 
 rostrum of, 94, 135 
 Sphenoidal cells, 94 
 crest, 94 
 fissure, 96, 132 
 process, 1097 
 
 of palate bone, 118 
 sinuses, 94, 143 
 spine, 95 
 spongy bones, 97 
 turbinated bones, 143 
 Spherical recess, 1164 
 Sphincter ani muscle, external, 
 450 
 internal, 451 
 muscles, 363 
 pyloris, 1272 
 vaginae muscle, 461 
 Spigelian lobe of liver, 1330 
 Spina tympanica major, 1151 
 
 minor, 1151 
 Spinal accessory nerve, 1063 
 accessory portion, 1063 
 bulbar portion, 1063 
 nucleus of, 950 
 spinal portion, 1063 
 surgical anatomy of, 1063 
 arteries, anterior, 638 
 lateral, 638 
 posterior, 639 
 bulb, 938 
 canal, 69 
 column, 48 
 cord, 836 
 
 arachnoid membrane of, 
 
 834 
 blood supply of, 840 
 central canal of, 840 
 columns of, 838 
 commissure of, 839 
 comu of, caput, 839 
 
 cervix, 839 
 dissection of, 832 
 dura mater of, 832 
 fibres of, 841 
 fissures of, 837 
 gray substance of, 845 
 grooves of, 837 
 lymphatics of, 840 
 membranes of, 832 
 minute anatomy of, 840 
 neuroglia of, 840 
 olivary bundle of, 843 
 pia mater of, 835 
 structure of, 839 
 tracts of, conducting, 841 
 
 functions of, 844 
 veins of, 755 
 white substance of, 841 
 cranial reflexes, 963 
 foramen, 49 
 nerves, 964 
 
 accessory, 1063 
 distribution of, 967 
 ganglia of, 966 
 origin of, 847 
 
 Spinal nerves, points of emer- 
 gence of, 967 
 roots of, 965 
 
 reflexes, 963 
 
 veins, 753 
 
 longitudinal, anterior, 754 
 
 posterior, 755 
 plexus of, 753 
 Spinalis colli muscle, 420 
 
 dorsi muscle, 419 
 Spindle, aortic, 591 
 Spindles, neuro-muscular, 829 
 
 neuro-tendinous, 829 
 Spine, articulations of, 276 
 
 ethmoidal, 93, 130 
 
 frontal, 80 
 
 of helix, 1146 
 
 of Henle, 88 
 
 of ischium, 211 
 
 mental, 123 
 
 nasal, 80 
 
 anterior. 111, 139, 143 
 posterior, 116, 135, 143 
 
 palatine, 116 
 
 peroneal, 243 
 
 pharyngeal, 73, 135 
 
 progress of ossification in, 60 
 
 of pubis, 212 
 
 of scapula, 172 
 
 sphenoidal, 95 
 
 suprameatal, 88 
 Spino-glenoid ligament, 302 
 Spinous processes of ilium, 210 
 of tibia, 233 
 of vertebriB, 49 
 Spiral canal of cochlea, 1167 
 
 ligament of cochlea, 1172 
 
 line of femur, 223 
 
 tube of Schachowa, 1419 
 Splanchnic nerv^es, 1079 
 Splanchnopleure, 1236 
 Spleen, 1353 
 
 accessory, 1355 
 
 arteries of, 1357 
 
 development of, 1245 
 
 fibro-elastic coat of, 1356 
 
 hilum of, 1354 
 
 lymphatics of, 807, 1359 
 
 Malpighian bodies of, 807, 1358 
 
 movability of, 1356 
 
 movable, 1356 
 
 nerves of, 1359 
 
 serous coat of, 1356 
 
 structure of, 1356 
 
 support of, 1356 
 
 surface form of, 1359 
 
 surgical anatomy of, 1359 
 
 veins of, 1359 
 Splenic artery, 674 
 
 flexure of colon, 1309 
 of large intestine, 1300 
 
 glands, 800 
 
 plexus, 1061, 1085 
 
 pulp, 1356 
 
 vein, 768 
 Splenium of corpus callosum, 
 
 886 
 Splenius muscle, 416 
 Spongy portion of urethra, 1443 
 
 tissue of bone, 33 
 Spur, femoral, 227 
 Squamo-parietal suture, 128 
 
 -sphenoidal suture, 128 
 Squamous portion of occipital 
 bone, 71 
 
 suture, 85, 128 
 Square lobe of liver, 1332 
 Stahr, middle gland of, 784 
 Stapedius muscle, 1160 
 Stapes, 1160 
 
 base of, 1160 
 
1592 
 
 INDEX 
 
 Stapes, crura of, 1160 
 
 foot-plate, 1160 
 
 head of, 1160 
 
 ligament of, 1161 
 
 neck of, 1160 
 Statoliths, 1171 
 Stellate ligament, 284 
 
 reticulum, 1206 
 Stenson, duct of, 1215 
 
 foramina of, 110 
 Stephanion, 137 
 
 inferior, 76 
 
 superior, 76 
 Sternal arteries, 644 
 
 foramen, 157 
 
 furrow, 165 
 
 glands, 810 
 
 ribs, 159 
 Stemo-clavicular articulations, 
 297 
 surface form of, 299 
 surgical anatomy of, 297 
 
 -cleido-mastoid muscle, 389 
 
 -costal ligament, anterior, 
 288 
 interarticular, 288 
 posterior, 288 
 
 -costo pericardial ligament, 
 559 
 
 -hyoid muscle, 391 
 
 -mastoid artery, 602, 609 
 glands, 786 
 muscle, 389 
 
 surface form of, 391 
 surgical anatomy of, 391 
 
 -pericardiac ligaments, 558 
 
 -thyroid muscle, 392 
 Sternum, 155 
 
 angle of, 157 
 
 articulations of, 159, 290 
 
 attachment of muscles to, 159 
 
 development of, 158 
 
 ensiform appendix of, 158 
 
 gladiolus, 157 
 
 ligaments of, 290 
 
 manubrium of, 157 
 
 structure of, 158 
 
 surface form of, 165 
 
 surgical anatomy of, 165 
 
 xiphoid appendix of, 158 
 Stigmata, 1246 
 Stilling, canal of, 1129 
 
 nucleus of, red, 938 
 Stomach, 1268 
 
 alterations in position of, 1271 
 
 areolar coat of, 1274 
 
 arteries of, 1278 
 
 body of, 1269 
 
 cardiac orifice of, 1270 
 portion of, 1269 
 
 chamber, 1269 
 
 curvatures of, 1270 
 
 fundus of, 1269 
 
 innervation of, 1280 
 
 IjTnphatic vessels of, 806, 1279 
 
 movements of, 1280 
 
 mucous membrane of, 1275 
 
 muscular coat of, 1273 
 
 nerves of, 1279 
 
 oesophageal opening of, 1270 
 
 peritoneal coat of, 1273 
 
 pit of, 165 
 
 pyloric orifice of, 1270 
 portion of, 1269 
 
 relations of, 1269 
 
 rugae of, 1275 
 
 serous coat of, 1273 
 
 structure of, 1273 
 
 submucous coat of, 1274 
 
 supports of, 1272 
 
 surface form of, 1280 
 
 Stomach, surfaces of, 1269 
 surgical anatomy of, 1280 
 -teeth, 1197 
 vascular coat of, 1274 
 veins of, 1279 
 Stomata, 1246 
 Straight sinus, 738 
 Stria vascularis, 1172 
 Striated muscle, 361 
 Striped muscle, 361 
 Stroma of iris, 1118 
 of ovarj% 1501 
 plexus of, 1111 
 Stylo-glossus muscle, 397 
 -hyal process, 92 
 -hyoid ligament, 394 
 muscle, 394 
 
 nerve, from facial, 1048 
 -mandibular ligament, 281, 388 
 -mastoid artery, 610 
 
 foramen, 90, 135 
 -maxillary ligament, 281 
 -pharyngeus muscle, 403 
 Styloid process of fibula, 237 
 of temporal bone, 90 
 of ulna, 189 
 Subacromial bursa, 305, 471 
 Subanconeus muscle, 478 
 Subarachnoid cisternge, 852 
 
 space, 834, 852 
 Subarachnoidean areolar tissue, 
 851 
 space, 834 
 Subcalcarine convolution, 877 
 Subcallosal gyrus, 882 
 Subclavian artery, 631 
 branches of, 637 
 first part of, left, 633 
 
 right, 632 
 peculiarities of, 635 
 second part of, 633 
 surface form of, 635 
 surgical anatomy of, 635 
 third part of, 633 
 glands, 791 
 groove, 169 
 loop, 1076 
 muscle, 468 
 plexus of nerves, 1077 
 triangle, 618 
 vein, 749 
 Subclavius muscle, 468 
 Subcollateral convolution, 878 
 Subcostal artery, 667 
 
 groove, 162 
 Subcrureus mviscle, 518 
 Subcutaneous acromial bursa, 
 30B 
 areolar tissue, 1180 
 olecranon bursa, 477 
 sjmovial bursa, 263 
 tibial bursa, 340 
 trochanteric bursa, 331 
 Subdeltoid bursa, 305, 471 
 Subdural space, 834, 847 
 Subepithelial plexus, 1111 
 Sublingual artery, 604 
 fossa, 123 
 gland, 1217 
 Sublobular veins, 767 
 Submaxillary artery, 606 
 fossa, 123 
 ganglion, 1040 
 arteries of, 1217 
 branches of, 1040 
 ducts of, 1216 
 glands, 784, 1216 
 lymphatics of, 1217 
 nerves of, 1217 
 veins of, 1217 
 triangle, 394, 617 
 
 Submaxillary vein, 727 
 Submental artery, 606 
 
 glands, 785 
 
 vein, 727 
 Suboccipital Ij'mphatic glands, 
 780 
 
 nerves, 968 
 
 triangle, 423 
 Suborbital glands, 782 
 Subparotid glands, 1215 
 
 lymphatic glands, 782 
 Subpleural mediastinal plexus, 
 
 644 
 Subpubic ligament, 296 
 Subscapular angle, 172 
 
 artery, 651 
 
 bursa, 305 
 
 fascia, 471 
 
 fossa, 171 
 
 nerves, 984 
 Subscapularis muscle, 471 
 Subserous areolar coat of lungs, 
 1394 
 tissue, 1245 
 
 connective tissue, 1246 
 Substantia cinerea glutinosa, 841 
 
 ferruginea, 945 
 
 glutinosa centralis, 840 
 
 nigra, 910 
 
 propira of cornea, 1110 
 Substerno-mastoid glands, 785 
 Subtendinous iliac bursa, 331 
 
 synovial bursa, 26.3 
 Subthalamic region, 905, 913 
 
 tegmental region, 885 
 Suburethral gland, 1482 
 Sucking pad, 380 
 Suctorial pad, 380 
 Sudoriferous glands, 1190 
 Sulci, occipital, 876 
 Sulcus, callosal, 879, 885 
 
 calloso-marginal, 868, 870 
 
 diagonalis, 8G8 
 
 dorso-median, 838 
 
 frontal, 873 
 
 frontalis, inferior, 868 
 medius, 868, 873 
 superior, 868 
 
 interparietalis, 868 
 
 intraparietal, of Turner, 875 
 
 lachrymal, 113 
 
 lateralis mesencephali, 885 
 
 nervi oeulo-motorii, 885 
 
 occipitalis transversus, 868 
 
 occipito-temporal, 870 
 
 oculomotorius, 906 
 
 olfactory, 870, 874 
 
 orbital, 870, 874 
 
 orbito-palpebral, inferior, 1137 
 superior, 1137 
 
 paramedians, 868, 873 
 
 parieto-occipital, 867 
 internal, 870 
 
 post-central, 875 
 inferior, 868 
 superior, 868 
 
 posterior median, 838 
 
 precentral, 872 
 inferior, 868 
 superior, 868 
 
 of Reil, limiting, 867, 878 
 
 of Rolando, central, 867 
 
 sagittal, 73, 80 
 
 scleral, 1105 
 
 sigmoid, 86 
 
 spiralis extemus, 1172 
 intemus, 1172 
 
 temporal, 877 
 inferior, 868, 870 
 superior, 868 
 
 terminalis of His, 566, 1087 
 
INDEX 
 
 1593 
 
 Sulcus, tri-radiate, 874 
 tympanic, 1149 
 tympanicus, 1151 
 Superciliary ridge, 80 
 Superficial anterior thoracic 
 
 nerve, 984 
 branches of cervical plexus, 
 
 972 
 cardiac plexus, 1081 
 cerebellar veins, 736 
 cerebral veins, 735 
 cervical artery, 642 
 
 fascia, 386 
 
 glands, 784 
 
 nerve, 973 
 
 region, inuscles of, 386 
 circumflex iliac artery, 704 
 
 vein, 756 
 crural arch, 436, 1529 
 dorsal veins of penis, 762 
 epigastric artery, 704 
 external pudic artery, 704 
 fascia, 364 
 
 of abdomen, 433, 1511 
 
 of arm, 470 
 
 of back, 411 
 
 of cranial region, 366 
 
 of femoral region, 512 
 
 of periniEura in male, 455 
 
 of shoulder, 470 
 
 of thoracic region, 463 
 femoral artery, 700 
 inguinal lymphatic glands, 793 
 long plantar ligament, 353 
 lymphatic glands of upper ex- 
 tremity, 788 
 
 vessels of gluteal region, 801 
 of lower extremity, 797 
 of penis, 801 
 of perinseum, 801 
 of scrotum, 801 
 of upper extremity, 792 
 of walls of abdomen, 801 
 muscles of abdomen, 432 
 palmar arch, 664 
 parotid lymphatic glands, 781 
 perinea] artery, 690 
 sural artery, 710 
 Sylvian vein, 735 
 temporal artery, 611 
 
 nerves, 1038 
 
 vein, 727 
 transverse ligament of fingers, 
 
 494 
 veins of fingers, 745 
 
 of foot, 756 
 
 of hand, 745 
 
 of lower extremity, 756 
 
 of upper extremity, 745 
 Superficialis colli nerve, 973 
 
 volje artery, 659 
 Superior acromio-clavicular lig- 
 ament, 299 
 astragalo-scaphoid ligament, 
 
 354 
 branch of superior cervical 
 
 ganglion, 1073 
 calcaneo-cuboid ligament, 353 
 
 -scaphoid ligament, 353 
 cardiac nerve, 1076 
 carotid triangle, 394 
 cerebellar artery, 640 
 
 peduncles, 932 
 cerebral veins, 735 
 cervical ganglion, 1072 
 constrictor muscle, 401 
 coronary artery of lip, 607 
 dental plexus, l033 
 epigastric artery, 645 
 
 glands, 802 
 fibular artery, 713 
 
 Superior flexure of duodenum, 
 
 1285 
 frontal convolution, 873 
 gemellus muscle, 526 
 gluteal nerve, 1010 
 hsemorrhoidal artery, 678 
 
 plexus of nerves, 1085 
 
 veins, 768 
 intercostal artery, 645 
 
 veins, 752 
 lachrymal gland, 1141 
 
 nerve, 1060 
 laryngeal artery, 602 
 ligament of incus, 1061 
 
 of malleus, 1160 
 lingualis muscle, 399 
 longitudinal fasciculus, 918 
 
 sinus, 78, 130, 736 
 maxillary bones, 105 
 
 nerve, 1031 
 
 region, muscles of, 376 
 meatus of nose, 101, 144 
 mediastinum, 1388 
 medullary velum, 943 
 mesenteric artery, 675 
 
 plexus of nerves, 1085 
 
 vein, 768 
 nuchal line, 72 
 obliquus oculi, muscle, 373 
 occipital convolution, 877 
 
 sulcus, 876 
 olivary nucleus, 925 
 ophthalmic vein, 740 
 orbito-palpebral svdcus, 1137 
 parietal convolution, 876 
 peduncle of cerebellum, 910, 
 
 943 
 petrosal sinus, 742 
 phrenic artery, 644 
 
 veins, 767 
 post-central sulcus, 875 
 profunda artery, 655 
 pubic ligament, 296 
 pyloric artery, 673 
 radio-ulnar articulation, 314 
 ramus of ischium, 211 
 
 of pubis, 213 
 rectus oculi muscle, 373 
 sacro-sciatic foramen, 294 
 semicircular canal, 1165 
 stephanion, 76 
 superficial cerebellar veins, 736 
 
 external pudic artery, 704 
 surface of Uver, 1327 
 tarsal arch, 623 
 temporal convolution, 877 
 thoracic artery, 650 
 thvroid artery, 601 
 
 vein, 730 
 transverse ligament, 302 
 triangle of fourth ventricle, 945 
 turbinated bone, 101 
 
 crest, 117 
 vena cava, 752 
 
 vermiform process of cerebel- 
 lum, 927 
 vesical artery, 686 
 
 plexus of veins, 761 
 vocal cords, 1370 
 Supernumerary bones, 103 
 
 spleens, 1355 
 Supinator longus muscle, 484 
 
 radii brevis muscle, 487 
 Supporting cells of Hensen, 1175 
 Supra-acromial artery, 642 
 
 nerves, 974 
 Supracallosal gyrus, 887 
 Supraclavicular glands, 787 
 
 nerves, 974 
 Supracondylar ridge, external, 
 179 
 
 Supracondylar ridge, internal, 
 
 180 
 Supracondvloid glands of Leaf, 
 
 795 
 Supraepitrochlear glands, 789 
 Supraglenoid tubercle, 175 
 Suprahj'oid aponeurosis, 394 
 artery, 603 
 glands, lateral, 784 
 
 median, 785 
 region, muscles of, 393 
 Supramandibular nerves, 1049 
 Supramarginal convolution, S76. 
 Supramastoid crest, 84, 137 
 Supramaxillary lymphatic 
 glands, 782 
 nerves, 1049 
 Suprameatal spine, 88 
 
 triangle, 85 
 Supraorbital arch, 80 
 artery, 623 
 foramen, 80, 140 
 nerve, 1030 
 notch, 80, 140 
 ridge, 140 
 vein, 726 
 Suprapatellar bursa, 340, 518- 
 Suprarenal artery, 678 
 capsule, 1428 
 arteries of, 1431 
 left, 1429 
 
 lymphatic vessels of, 804 
 lymphatics of, 1431 
 nerves of, 1431 
 relations of, 1428 
 right, 1428 
 structure of, 1430 
 veins of, 1431 
 glands, 1428 
 
 accessory, 1430 
 impression of liver, 1332 
 plexus of nerves, 1084 
 veins, 767 
 Suprascapular artery, 641 
 ligament, 302 
 nerve, 983 
 notch, 174 
 Suprascleral lymph-space, 1104- 
 Supraspinales muscle, 421 
 Supraspinatus fascia, 472 
 
 muscle, 472 
 Supraspinous fossa, 172 
 
 Ugament, 273 
 Suprasternal artery, 642 
 nerves, 974 
 notch, 409 
 space, 388 
 Supratonsillar fossa, 1213 
 Supratrochlear foramen, 181 
 glands, 789 
 nerve, 1030 
 Supravaginal portion of uterus,. 
 
 1488 
 Surface form of abdominal aorta,. 
 670 
 of acromio-clavicular artic- 
 ulation, 301 
 of ankle-joint, 351 
 of axillary arterv, 649 
 of bladde'r, 1440 
 of bones, 34 
 of brachial artery, 654 
 of carotid arteries, common, 
 598 
 external, 601 
 of carpus, 204 
 of clavicle, 170 
 of common iliac arteries, 
 
 682 
 of dorsalis pedis artery, 715» 
 of elbow-joint, 312 
 
1594 
 
 INDEX 
 
 Surface form of external audi- 
 tory meatus 1050 
 iliac artery, 682, 695 
 
 of eyelids, 1142 
 
 of femoral artery, 701 
 
 of femur, 229 
 
 of fibula, 239 
 
 of fifth nerve, 1041 
 
 of foot, 255, 360 
 
 of heart, 577 
 
 of hip, 333 
 
 of humerus, 183 
 
 of hyoid bone, 154 
 
 of inferior radio-ulnar artic- 
 ulation, 317 
 
 of internal iliac artery, 694 
 
 of intestines, 1323 
 
 of kidney, 1425 
 
 of knee-joint, 343 
 
 of lachrymal gland, 1143 
 sac, 1143 
 
 of liver, 1346 
 
 of lungs, 1397 
 
 of metacarpo-phalangeal ar- 
 ticulation, 325 
 
 -of mouth, 1219 
 
 •of muscles of abdomen, 448 
 of back, 424 
 of face, 385 
 of head, 385 
 of lower extremity, 549 
 of upper extremit3% 500 
 of vertebral region, 409 
 
 ■of pancreas, 1353 
 
 of parotid duct, 1215 
 
 of patella, 231 
 
 of pelvis, 220 
 
 •of plantar arteries, 720 
 
 of popliteal arterj', 709 
 
 of radial artery, 658 
 
 •of radio-carpal articulation, 
 318 
 
 ■of radius, 192 
 
 of rectum, 1323 
 
 •of scapula, 176 
 
 of shoulder-joint, 307 
 
 of skull, 147 
 
 of spleen, 1359 
 
 of sterno-clavicular articu- 
 lation, 299 
 -mastoid muscle, 391 
 
 of sternum, 165 
 
 of stomach, 1280 
 
 of subclavian artery, 635 
 
 of superior radio-ulnar ar- 
 ticulation, 314 
 
 of temporo-mandibular ar- 
 ticulations, 282 
 
 of tibial artery, anterior,712 
 posterior, 717 
 
 of trachea, 1380 
 
 of trifacial ners^e, 1041 
 
 of trigeminal nerve, 1041 
 
 of ulnar artery, 661 
 
 of vermiform appendix, 1323 
 
 of vertebral column, 69 
 ISurgical anatomy of abdominal 
 aorta, 670 
 
 of abducent nerve, 1044 
 
 of acromio-clavicular articu- 
 lation, 301 
 
 of ankle-joint, 351 
 
 of arch of aoria, 592 
 
 of artery of bulb, 691 
 
 of ascending pharyngeal ai- 
 tery, 611 
 
 of auditory nerve, 1054 
 
 of axilla, 645 
 
 of axillary artery, 649 
 vein, 748 
 
 •of azygos veins, 753 
 
 Surgical anatomy of bend of 
 
 elbow, 653 
 oi bile-duct, 1347 
 of bladder, 1440 
 of brachial artery, 654 
 
 plexus, 991 
 of carotid arteries, common, 
 598 
 external, 601 
 internal, 621 
 
 gland, 1049 
 of carpus, 205 
 of cavernous sinus, 740 
 of cervical fascia, 389 
 
 ganglion, 1077 
 
 plexus, 977 
 of cheeks, 1224 
 of clavicle, 170 
 of colon, 1326 
 of common iliac arteries, 
 
 682 
 of conjunctiva, 1144 
 of deep epigastric artery, 
 
 697 
 of descent of testicles, 1462 
 of dorsalis pedis artery, 715 
 of duodenum, 1325 
 of ear, 1176 
 of eighth nerve, 1054 
 of elbow-joint, 312 
 of eleventh nerve, 1063 
 of emissary veins, 743 
 of external iliac artery, 695 
 of eye, 1134 
 of eyelashes, 1143 
 of eyelids, 1143 
 of facial artery, 607 
 
 nerve, 1049 
 
 veins, 726 
 of fascia of femoral region, 
 
 anterior, 515 
 of femoral artery, 701 
 of femur, 229 
 of fibula, 239 
 of foot, 256, 360 
 of gall-bladder, 1347 
 of glosso-pharvngeal nerve, 
 
 1057 
 of gums, 1224 
 of hemorrhoidal veins, 76 1 
 of heart, 578 
 of hernia, 1511 
 of hip, 333 
 of humerus, 183 
 of hyoid bone, 154 
 of hypoglossal nerve, 1066 
 of inferior calcaneo-scaphoid 
 ligament, 354 
 
 thyroid artery, 641 
 of innominate artery, 594 
 of intercostal artery, 668 
 
 nerves, 996 
 of internal iliac artery, 685, 
 694 
 
 jugular vein, 732 
 
 mammary artery, 645 
 
 pudic artery in male, 690 
 of intestines, 1324 
 of ischio-rectal region, 1535 
 of kidney, 1425 
 of knee-joint, 343 
 of lachrymal gland, 1144 
 
 sac, 1144 
 of lateral sinus, 739 
 of ligaments of vertebra,279 
 of lips, 1224 
 of lingual artery, 604 
 of liver, 1346 
 of lumbar plexus, 1017 
 of lungs, 1397 
 of lymphatic glands, 774 
 
 Surgical anatomy of lymphatics 
 of mammary gland, 814 
 of neck, 787 
 
 of upper extremity, 792 
 vessels of peritoneum, 802 
 of stomach, 806 
 of male breast, 1509 
 of mammary gland, 1508 
 of maxillary arterj-, exter- 
 nal, 607 
 of Meibomian glands, 1143 
 of membranes of cord, 836 
 of middle meningeal arterj-, 
 
 614 
 of motor oculi nerve, 1025 
 of mouth, 1224 
 of muscles of acromial re- 
 gion, 471 
 of arm, 478 
 
 of femoral region, anterior, 
 518 
 internal, 522 
 posterior, 531 
 of gluteal region, 528 
 of iliac region, 511 
 of lateral thoracic region, 
 
 469 
 of leg, 541 
 
 of lower extremity, 551 
 of orbital region, 375 
 of palatal region, 406 
 of radio-ulnar region, an- 
 terior, 484 
 posterior, 491 
 of tongue, 400 
 of upper extremity, 503 
 of nasal fossae, 1102 
 of ninth nerve, 1057 
 of occipito-frontalis muscle, 
 
 368 
 of tt'sophagus, 1230 
 of olfactory nerve, 1021 
 of optic nerve, 1022 
 of ovary, 1503 
 of palate, 1224 
 of palatine artery, 615 
 of palmar fascia, deep, 494 
 of pancreas, 1353 
 of patella, 231 
 of pelvis, 220 
 of penis, 1460 
 of pericardium, 561 
 of perinffium, 1535 
 of peritoneum, 1264 
 of pharynx, 1224 
 of phrenic nerve, 976 
 of plantar arteries, 720 
 
 fascia, 543 
 of pleura, 1387 
 of pneumogastric nerve, 
 
 1062 
 of popliteal artery, 709 
 of pronator radii teres mus- 
 cle, 479 
 of prostate gland, 1452 
 of prostatico-vesical plexus, 
 
 762 
 of radial artery, 658 
 of radio-carpal articulation, 
 
 318 
 of radius, 192 
 of rectum, 1325 
 of salivarj' glands, 1224 
 of saphenous veins, 757 
 of scapula, 177 
 of scrotum, 1469 
 of seminal vesicles, 1476 
 of seventh nerve, 1049 
 of shoulder-joint, 307 
 of sixth nerve, 1044 
 of skull, 149 
 
INDEX 
 
 1595 
 
 ^Surgical anatomy of spennatic 
 cord, 1468 
 veins, 766 
 of spinal accessory nerve, 
 
 1063 
 of spleen, 1359 
 of sternum, 165 
 of ste mo-clavicular artic- 
 ulation, 299 
 -mastoid muscle, 391 
 of stomach, 1280 
 of subclavian artery, 635 
 of superficial fascia of cra- 
 nial region, 367 
 inguinal Ivmphatic glands, 
 794 
 of superior radio-ulnar artic- 
 ulation, 314 
 of synovial tendons at wrist, 
 
 492 
 of tarsal joint, 356 
 of tarsus, 256 
 of temporal artery, 612 
 of temporo-mandibular ar- 
 ticulations, 282 
 of tenth nerve, 1062 
 of testicles, 1473 
 of thoracic aorta, 666 
 of thvroid artery, superior, 
 603 
 gland, 1405 
 of tibia, 239 
 of tibial artery, 717 
 
 anterior, 712 
 of tongue, 1093 
 of tonsils, 1224 
 of trachea, 1381 
 of triangles of neck, 616 
 of trochlear nerve, 1026 
 of twelfth nerve, 1066 
 of ulna, 192 
 of ulnar artery, 661 
 of ureter, 1428 
 of urethra, male, 1445 
 of utero-ovarian artery, 688 
 of uterus, 1496 
 _ of vermiform appendix, 
 1325 
 of vertebral artery, 639 
 column, 69 
 neck of humerus, 177 
 of scapula, 172 
 ^Suspensory ligament of axilla, 
 464 
 of clitoris, 437 
 of eve, 1105 
 of lens, 1129 
 of liver, 1333 
 of malleus, 1160 
 of mamma, 463 
 of ovary, 1501 
 of penis, 437 
 of Treitz, 1286 
 muscle of duodenum, 1286 
 Sustentacular cells of spleen,1356 
 
 fibres, 1121 
 Sustentaculum lienis, 1259 
 
 tali, 255 
 •Sutura, 264 
 dentata, 264 
 harmonia, 264 
 limbosa, 264 
 notha, 264 
 serrata, 264 
 squamosa, 264 
 vera, 264 
 '.Sutural bones, 103 
 ligament, 259 
 membrane, 264, 847 
 'Suture or sutures, basilar, 128 
 coronal, 78, 127 
 
 Suture or sutures, cranial, 126 
 ethmo-frontal, 130 
 -sphenoidal, 130 
 frontal, 79, 127 
 fronto-malar, 128 
 -parietal, 127 
 -sphenoidal, 128, 130 
 intermaxillary, 139 
 internasal, 139 
 interparietal, 127 
 lambdoid, 75, 78, 128 
 masto-occipital, 75, 128 
 
 -parietal, 128 
 metopic, 83, 127 
 naso-maxillary, 139 
 occipi to-parietal, 128 
 petro-occipital, 75, 128, 133 
 -sphenoidal, 128, 136 
 -squamous, 88 
 sagittal, 78, 127 
 spheno-parietal, 128 
 squamo-parietal, 128 
 
 -sphenoidal, 128 
 
 squamous, 85, 128 
 
 transverse, 128 
 
 facial, 128 
 
 Sweat-glands, 1190 
 
 Sylvian point, 866 
 
 vein, superficial, 735 
 Sylvius, aqueduct of, 912 
 
 "fissure of, 866, 884 
 Symington, ano-coccygeal body 
 
 of, 1316 
 Sympathetic nerve, 1066 
 ganglion of, 1078 
 plexuses of, 1080 
 structure of, 1068 
 Svmphysis, 264, 267 
 of jaw, 122 
 sacro-coccygeal, 66 
 Synarthrosis, 264 
 Synchondrosis, 264 
 Syndesmo-odontoid joint, 274 
 Syndesmosis, 265 
 Synovial bursa, 263 
 ligaments, 262 
 membranes, 262 
 articular, 262 
 bursal, 263 
 
 of flexor tendon at wrist, 
 492 
 surgical anatomy of, 
 492 
 vaginal, 263. -See also Indi- 
 vidual joints, 
 sheaths, 263 
 viUi, 262 
 Systemic arteries, 583 
 " veins, 724 
 
 Tables of skull, 33 
 
 Tabular portion of occipital bone, 
 
 71 
 Tactile corpuscle, 827 
 Tffinia fornicis, 896, 898 
 
 hippocampi, 896 
 
 pontis, 8S3 
 
 semicircularis, 891, 894 
 
 thalami, 904 
 Tapetum of choroid, 1114 
 
 lucidum, 1127 
 
 nigrum, 1127 
 Tarsal arch, 623 
 
 artery, 715 
 
 bones, development of, 253 
 
 glands, 1139 
 
 joint, surgical anatomy of, 356 
 
 ligament, external, 370 
 internal, 370 
 
 Tarsal plates of eyelid, 1139 
 Tarso-metatarsal articulations, 
 
 357 
 Tarsus, 242 
 
 articulations of, 352 
 surface form of, 255 
 surgical anatomy of, 256 
 synovial membrane of, 352 
 Tast«-buds, 1090 
 Teeth, 1195 
 
 arrangement of, 1198 
 
 auditory, 1173 
 
 bicuspid, 1138 
 
 canine, 1197 
 
 cementum of, 1204 
 
 cortical substance of, 1204 
 
 deciduous, 1196 
 
 development of, 1204 
 
 enamel of, 1203 
 
 eruption of, 1208 
 
 eye, 1197 
 
 general characters of, 1195 
 
 grinders, 1198 
 
 incisors, 1196 
 
 ivory of, 1202 
 
 milk, 1196 
 
 molar, 1198 
 
 permanent, 1196 
 
 superadded, 1208 
 premolars, 1198 
 roots of, 1196 
 soUd portion of, 1201 
 stomach, 1197 
 structure of, 1200 
 surfaces of, 1195 
 temporary, 1196 
 Tegmen tympani, 87 
 Tegmental region, subthalamic, 
 
 885 
 Tegmentum, 908 
 of crus cerebri, 885 
 fibres of, 908 
 nucleus of, red, 908 
 Tela chorioidea inferior, 856, 943 
 
 superior, 854, 901 
 subcutanea, 1180 
 Temporal artery, 611 
 
 anterior, 611, 640 
 
 from internal maxillary, 614 
 
 middle, 611 
 
 posterior, 611, 640 
 
 surgical anatomy of, 612 
 bone, 83 
 
 articulations of, 92 
 
 attachment of muscles to, 
 92 
 
 development of, 91 
 
 mastoid portion of, 85 
 
 petrous portion of, 88, 136 
 
 squamous portion of, 83 
 convolution, 877 
 crest, 76, 80, 84 
 diploic vein, 734 
 fascia, 381 
 fossa, 76, 137 
 
 horn of lateral ventricle, 890 
 lines, 76, 80 
 lobe, 885 
 muscle, 382 
 
 nerves, from auriculo-tempo- 
 ral, 1038 
 
 deep, 1037 
 
 from facial, 1032, 1049 
 ridges, 76, 80 
 sulci, 868 
 sulcus, first, 877 
 
 fourth, 878 
 
 inferior, 870 
 
 second, 877 
 
 third. 878 
 veins, 727 
 
1596 
 
 INDEX 
 
 Temporary teeth, 1196 
 
 eruption of, 1209 
 Temporo-facial nerve, 1032, 1049 
 -malar filaments, 115 
 foramen, 115 
 nerve, 1032 
 mandibular articulations, 280 
 surface form of, 282 
 surgical anatomy of, 282 
 region, muscles of, 381 
 -maxillarv articulation, 138 
 
 vein, 727 
 sphenoidal lobe, 877 
 Tendo Achillis, 535 
 bursa of, 535 
 oculi, 370 
 Tendons, 363 
 
 of diaphragm, central, 429 
 
 cordiform, 429 
 flexor, fibrous sheaths of, 545 
 T6non, capsule of, 1103 
 Tensor fasciae femoris muscle, 515 
 palati muscle, 404 
 tarsi m.uscle, 371 
 tympani muscle, 1161 
 canal for, 1153 
 Tenth nerve, 1057 
 
 surgical anatomy of, 1062 
 Tentorium, 900 
 cerebelli, 850 
 Teres major muscle, 474 
 
 minor muscle, 473 
 Testes gubernaculum, 1461 
 muliebres of Galen, 1499 
 Testicles, 1460, 1469 
 coverings of, 1462 
 descent of, 1461 
 gubernaculum testis, 1461 
 lobes of, 1472 
 lymphatic vessels of, 804 
 mediastinum testis, 1471 
 parenchyma of, 1471 
 rete testis, 1471 
 sheaths of, proper, 1469 
 size of, 1469 
 structure of, 1471 
 surgical anatomy of, 1473 
 trabeculse of, 1471 
 tubuli seminiferi of, 1471 
 tunica albuginea, 1471 
 vaginalis, 1470 
 vasculosa, 1471 
 tunics of, 1469 
 weight of, 1469 
 Testicular bag, 1462 
 Thalamencephalon, 901 
 Thalmic radiation, 905 
 Thebesian valve, 567, 771 
 Thigh, bones of, 221 
 fascia of, 512 
 muscles of, 512 
 Third nerve, 1024 
 
 ventricle of brain, 901 
 Thoracic aorta, 665 
 branches of, 666 
 surgical anatomy of, 666 
 artery, acromial, 651 
 alar, 651 
 long, 651 
 superior, 650 
 axis, 651 
 
 cardiac nerves, 1061 
 duct, 775 
 
 structure of, 778 
 gangUon, 1078 
 nerves, 993 
 plexus, 1079 
 
 divisions of, anterior, 993 
 
 posterior, 993 
 long, 983 
 posterior, 983 
 
 Thoracic plexus, roots of, 993 
 portion of gangliated cord, 
 1078 
 of oesophagus, 1226 
 region, anterior, fascia of, deep, 
 463 
 superficial, 463 
 muscles of, 463 
 lateral, muscles of, 468 
 
 surgical anatomy of,469 
 surface of lungs, 1391 
 trachea, lymphatic vessels of, 
 
 815 
 vein, long, 748 
 vertebrae, 53 
 bodies of, 53 
 laminae of, 54 
 pedicles of, 54 
 processes of, 54 
 wall, lymphatic glands of, 810 
 vessels of, 812 
 Thoracico-epigastric vein, 748 
 Thorax, 155 
 
 boundaries of, 155 
 cavity of, 556 
 fasciffi of, 424 
 lymphatics of, 810 
 muscles of, 424 
 nerves of, cutaneous, 995 
 openings of, lower, 556 
 
 upper, 556 
 veins of, 744 
 Thumb, ligaments of, 321 
 metacarpal bone of, 201 
 muscles of, 484 
 Thymic artery, 594 
 
 lymphatic vessels, 815 
 Thymus gland, 1407 
 arteries of, 1408 
 lobes of, 147 
 lymphatics of, 1048 
 nerves of, 1408 
 structure of, 1408 
 veins of, 1408 
 Thyro-arytenoid ligament, infe- 
 rior, 1370 
 superior, 1370 
 muscle, 1373 
 -epiglottic ligament, 1367 ' 
 -epiglottideus muscle, 1373 
 -glossal duct, 1090, 1401 
 -hyals of hyoid bone, 154 
 -hj'oid ligaments, 1366 
 membrane, 1366 
 muscle, 392 
 nerve, 1066 
 Thyroid artery, inferior, 641 
 
 surgical anatomy of, 641 
 superior, 601 
 
 surgical anatomy of, 603 
 axis, 640 
 body, 1401 
 
 venous plexus on, 751 
 cartilage, 1362 
 foramen, 214 
 ganglion, 1076 
 gland, 1401 
 
 accessory, 1403 
 arteries of, 602, 1404 
 color of, 1401 
 isthmus of, 1403 
 lobes of, 1403 
 lymphatic vessels of, 782 
 lymphatics of, 1405 
 nerves of, 1405 
 structure of, 1403 
 surgical anatomv of, 1405 
 veins of, 731, 1405 
 weight of, 1401 
 nerve, 1077 
 notch, 1362 
 
 Thyroid veins, accessory, 731 
 inferior, 751 
 middle, 730 
 superior, 730 
 Thyroidea ima artery, 594 
 
 vein, 751 
 Tibia, 233 
 
 articulations of, 236 
 attachment of muscles to, 236 
 crest of, 234 
 development of, 236 
 lower extremit}' of, 235- 
 
 surfaces of, 235 
 nutrient artery of, 719, 
 oblique line of, 235 
 shaft of, 234 
 
 surfaces of, 234 
 spinous process of, 233; 
 structure of, 236 
 surface form of, 236 
 tubercle of, 234 
 tuberosities of, 233 
 upper extremity of, 233' 
 Tibial artery, anterior, 711 
 branches of, 712 
 peculiarities of, 712 
 relations of, 711 
 surface marking of, 712 
 surgical anatomy of, 712 
 posterior, 716 
 branches of, 717 
 peculiarities of, 717 
 relations of, 716 
 surface marking of, 717 
 surgical anatomy of, 717 
 recurrent, anterior, 713 
 posterior, 713 
 bursa, subcutaneous, 340 
 gland, anterior, 795 
 nerve, 1014 
 anterior, 1016 
 posterior, 1014 
 veins, anterior, 758 
 posterior, 758 
 Tibialis anticus muscle, 532 
 bursa of, 532 
 posticus muscle, 538 
 Tibio-fibular articulation, 345 
 region, anterior, muscles of, 
 
 531 
 posterior, muscles of, 534 
 -tarsal ligament, anterior, 347 
 posterior, 347 
 Tissue, adipose, pads of, 263 
 areolar, subserous, 1245 
 connective, subserous, 1246 
 elastic, yellow, 261 
 fibrous, white, 261 
 intertubular, 1203 
 Tomes 's fibres, 1203 
 
 granular sheath of, 1202 
 Tongue, 1087 
 
 anterior portion of, 1087 
 apex or tip of, 1087 
 arteries oi, 1092 
 base or root of, 1087 
 body of, 1087 
 corium of, 1089 
 development of, 1242 
 dorsum of, 1087 
 fibrous septum of, 398 
 fraenum of, 1087 
 glands of, 1091 
 -like lobe of liver, 1336 
 lymphatics of, 1093 
 lymphatic vessels of, 7?2 
 margin of, 1087 
 mucous membrane of, 1088 
 muscles of, 398, 1092 
 extrinsic, 398 
 fntrinsic, 398 
 
INDEX 
 
 1597 
 
 Tongue, muscles of, surgical ana- 
 tomy of, 400 
 nerves of, 1093 
 oral portion of, 1087 
 papillae of, 1089 
 pharyngeal portion of, 1087 
 posterior portion of, 1087 
 raph6 of, 1087 
 structure of, 1088 
 surface of, 1087 
 surgical anatomy of, 1093 
 veins of, 1092 
 Tonsil, 1213 
 
 arteries of, 1213 
 of cerebellum, 931 
 development of, 1243 
 lingua, 1088 
 lymphatics of, 1213 
 nerves of, 1213 
 pharyngeal, 1221, 1224 
 surgical anatomy of, 1224 
 veins of, 1213 
 Tonsillar artery, 606 
 
 nerves, 1057 
 Tooth germ, 1206 
 Torcular Herophili, 74. 737 
 Trabeculaj corpus cavernosum, 
 1457 
 of spleen, 1356 
 of testicle, 1471 
 Trachea, 1376 
 
 arteries of, 641, 1380 
 cartilages of, 1378 
 fibrous membrane of, 1379 
 lymphatics of, 1380 
 mucous membrane of, 1380 
 muscular fibres of, 1378 
 nerves of, 1380 
 relations of, 1376 
 structure of, 1378 
 surface form of, 1380 
 surgical anatomy of, 1381 
 thoracic, lymphatic vessels of, 
 
 815 
 veins of, 751, 1380 
 Tracheal arteries, 641 
 glands, 787, 1380 
 veins, 751 
 Trachelo-mastoid muscle, 419 
 Tract of Burdach, 839, 843 
 
 cerebellar, antero-lateral, as- 
 cending, 842 
 descending, 843 
 direct, 843 
 dorso-lateral, 843 
 of cord, conducting, 841 
 
 functions of, 844 
 cornu, commissural, 844 
 descending comma, 844 
 
 crossed, 842 
 of Goll, 839, 843 
 of Gowers, 842 
 of Helwig, triangular, 951 
 lateral, of medulla, 945 
 marginal, of Spitzka and Lis- 
 
 sauer, 843 
 nerve, afferent, 961 
 ascending, 961 
 descending, 959 
 efferent, 959 
 motor, 959 
 sensory, 961 
 olfactory, 880, 1019 
 optic, 1021 
 postero-lateral, 843 
 
 -median, 843 
 pyramidal, crossed, 842 
 'direct, 842 
 uncrossed, 842 
 ■septo-marginal, 844 
 triangular, of Helwig, 843 
 
 Tractus spiralis foraminosus, 89 
 Tragicus muscle, 1147 
 Tragus, 1145 
 
 Transitional epithelium, 1428 
 Transversalis cervicis muscle, 419 
 colli artery, 642 
 
 muscle, 419 
 fascia, 445, 1517 
 humeri artery, 641 
 muscle, 442, 1516 
 
 relations of, 442 
 Transverse cervical artery, 642 
 colon, 1309 
 
 flexure of, splenic, 1309 
 diameter of pelvis, 217 
 facial artery, 611 
 
 suture, 128 
 
 vein, 727 
 fibres of cerebrum, 916 
 
 of coid, 841 
 
 of pons, 923 
 foramen, 50 
 humeral ligament, 305 
 ligament of acetabulum, 330 
 
 of atlas, 275 
 
 inferior, 302 
 
 of knee, 340 
 
 superior, 302 
 lingualis muscle, 399 
 mesocolon, 1259, 1309 
 metacarpal ligament, 324 
 pelvic ligament, 459 
 perineal arter}"-, 691 
 
 ligament, 459 
 processes of a vertebra, 49 
 sinus, 743 
 
 of pericardium, 560 
 suture, 128 
 Transversus auricula; muscle, 
 
 1147 
 menti muscle, 378 
 perinei superficialis muscle, 
 
 457, 460 
 Trapezium bone, 198 
 
 articulations of, 198 
 
 attachment of muscles to, 
 198 
 
 surfaces of, 198 
 Trapezius muscles, 411 
 Trapezoid bone, 198 
 
 articulations of, 199 
 
 surfaces of, 198 
 ligament, 300 
 ridge, 168 
 Treitz, fossa r f, 1260 
 
 suspensory ligament of, 1286 
 Triangle of elbow, 653 
 of election, 617 
 
 of fourth ventricle, 945 
 Hesselbach's, 1520 
 of necessity, 616 
 of neck, anterior, 616 
 
 posterior, 618 
 
 surgical anatomy of, 616 
 occipital, 618 
 Petit's, 435 
 Scarpa's, 516, 697 
 subclavian, 618 
 submaxillary, 394, 617 
 suboccipital, 423 
 suprameatal, 85 
 Triangular cartilage of septum of 
 
 nose, 1097 
 fascia of abdomen, 437, 1155 
 
 of urethra, 458 
 interarticular fibro-cartilage, 
 
 315 
 muscles, 362 
 tract of Helwig, 843, 951 
 Triangularis menti muscle, 378 
 sterni muscle, 425 
 
 Triceps extensor cubiti muscle, 
 
 477 
 Tricuspid orifice, 567 
 
 valve, 570 
 Trifacial nerve, 1026 
 
 surface marking of, 1041 
 surgical anatomy of, 1041 
 Trigeminal depression, 88 
 
 nerve, 1026 
 
 surface marking of, 1041 
 surgical anatomy of, 1041 
 Trigoid bodies, 820 
 Trigone of bladder, 1438 
 
 of habenula, 904 
 Trigonum acustici, 945 
 
 nervi hj'poglossi, 945 
 
 olfactoriiun, 881 
 
 vagi, 945 
 
 ventriculi, 890 
 
 vesicae, 1438 
 Tri-radiate sulcus, 874 
 
 carotid, inferior, 616 
 superior, 394, 617 
 Trochanter, great, 223 
 bursa of, 331 
 
 lesser, 223 
 
 rudimental, third, 224 
 Trochanteric fossa, 223 
 Trochlea of femur, 225 
 
 of humerus, 181 
 Trochlear fossa, 82 
 
 nerve, 1025 
 
 surgical anatomy of, 1026 
 
 surface of astragalus, 244 
 Trochoid, 265 
 
 Trolard, anastomotic vein of, 735 
 Troltsch, recessus of, 1162 
 True vocal cords, 1370 
 Trunk, arteries of, 665 
 
 articulations of, 269 
 
 fasciae of, 410 
 
 muscles of, 410 
 
 of pneumogastric nerve, gan- 
 glion of, 1059 
 Tube or tubes, bronchial, 1376 
 
 Eustachian, 1153 
 
 Fallopian, 1497 
 
 lymphatic vessels of, 804 
 
 medullary, 857 
 
 neural, 857 
 
 spiral, of Schachowa, 1419 
 
 tonsil, 1155 
 Tuber annulare, 922 
 
 cinereum, 882 
 Tubercle, acoustic, lateral, 950 
 
 adductor, 225 
 
 carotid, 51 
 
 of cervical vertebra, anterior, 
 50 
 posterior, 50 
 
 Chassaignac's, 69 
 
 conoid, 168 
 
 comical, of Santorini, 1368 
 
 cuneate, 941 
 
 cuneiform, of Wrisberg, 13G8 
 
 of Darwin, 1145 
 
 deltoid, 168 
 
 egg, 1502 
 
 of epiglottis, 1365 
 
 of femur, 223 
 
 genial, 123 
 
 of hyoid bone, 153 
 
 infragleniod, 174 
 
 jugular, 74 
 
 lachrymal, 109 
 
 mental, 122 
 
 of navicular bone, 246 
 
 olfactory, 881, 1019 
 
 of optic thalamus, anterior, 904 
 
 peroneal, 243 
 
 pharyngeal, 73 
 
1598 
 
 INDEX 
 
 Tubercle, pterygoid, 97 
 of quadratus, 225 
 of ribs, 161 
 of Rolando, 941 
 of scaphoid, 196 
 supraglenoid, 175 
 of tibia, 234 
 of ulna, 186 
 of zygoma, 84 
 Tubercula quadrigemina, 911 
 Tuberculum acusticum, 945, 1051 
 caudatum, 1333 
 impar, 1242 
 Tuberosity, bicipital, 195 
 of calcaneus, 243 
 of cuboid, 245 
 of femur, inner, 226 
 
 outer, 226 
 glenoid, 175 
 of humerus, 179 
 of ischium, 211 
 maxillary, 106 
 of navicular bone, 246 
 of palate bone, 117, 135 
 of radius, 190 
 of ribs, 161 
 of sacrum, 63 
 of scaphoid bone, 246 
 of tibia, external, 233 
 internal, 233 
 Tubuli, lactiferi, 1507 
 seminiferi, 1471 
 uriniferi, 1418 
 Tunic of Ruysch, 1113 
 Tunica adventitia, 1228 
 albuginea, 373, 1457, 1471 
 interna, 1120 
 propria, 1180 
 
 vaginalis, 1462, 1465, 1469 
 cavity of, 1470 
 parietal portion of, 1470 
 visceral portion of, 1470 
 vasculosa testis, 1471 
 Tunics of eye, 1107 
 
 of testicle, 1469 
 Turbinated bone, inferior, 119 
 articulations of, 120 
 development of, 120 
 surfaces of, 120 
 middle, 101 
 sphenoidal, 143 
 superior, 101 
 crest, 107, 117 
 Turck, fasciculus of, 842 
 Turner, intraparietal sulcus of, 
 
 875 
 Twelfth nerve, 1064 
 
 surgical anatomy of, 1066 
 Tympanic antrum, 87 
 aperture, 1151 
 
 artery from ascending pharyn- 
 geal, 610 
 from internal carotid, 622 
 maxillary, 613 
 attic, 87 
 cavity, 1150 
 nerve, 1056 
 
 from facial, 1047 
 plexus of, 1057 
 sulcus, 1149 
 Tympanohyal process, 92 
 Tvmpanomalleolar ligaments, 
 
 1156 
 Tympanum, 1150 
 arteries of, 1162 
 cavity of, 1150 
 floor of, 1151 
 fundus of, 1151 
 mucous membrane of, 1162 
 muscles of, 1161 
 nerves of, 1163 
 
 Tympanum, ossicles of, 1158 
 pyramid of, 1153 
 roof of, 1151 
 veins of, 1163 
 walls of, 1153 
 
 Ulna, 184 
 
 articulations of, 189 
 
 attachment of muscles to, 189 
 
 development of, 189 
 
 lower extremity of, 189 
 
 shaft of, 188 
 
 structure of, 189 
 
 surface form of, 189 
 
 surgical anatomy of, 192 
 
 tubercle of, 186 
 
 upper extremity of, 184 
 
 coronoid process of, 186 
 olecranon process of, 186 
 sigmoid cavities of, 186 
 Ulnar artery, 660 
 
 peculiarities of, 661 
 surface marking of, 661 
 surgical anatomy of, 661 
 groove, 182 
 nerve, 988 
 
 region, muscles of, 498 
 veins, 745 
 Umbilical arteries in fcBtus, 579, 
 685 
 fissure of liver, 1331 
 fossa of liver, 1331 
 notch, 1331 
 
 region, contents of, 1234 
 Umbilicus, lymphatic vessels of, 
 
 802 
 Umbo, 1157 
 Unciform bone, 199 
 
 articulations of, 200 
 attachment of muscles to, 
 200 
 process of ethmoid, 100 
 Uncinate convolution, 879 '• 
 fasciculus, 917 
 process of Winslow, 1348 
 Uncrossed pyramidal tract, 842 
 Uncus, 879 
 
 Ungual phalanges, 204 
 Unipolar cells, 820 
 Unstriated muscle, 361 
 Unstriped muscle, 361 
 Upper deep cervical glands, 786 
 extremity, arteries of, 631 
 articulations of, 297 
 bones of, 167 
 fascige of, 462 
 lymphatic glands of, 788 
 
 vessels of, 792 
 muscles of, 462 
 veins of, 744 
 subscapular nerve, 984 
 Urachus, 1435 
 fold of, 1519 
 Ureter, 1426 
 
 arteries of, 1428 
 fibrous coat of, 1427 
 Ureteral folds, 1439 
 Ureters, lymphatic vessels of,804 
 muscular coat of, 1428 
 mucous coat of, 1428 
 nerves of, 1428 
 orifices of, 1438 
 relations of, 1427 
 structure of, 1427 
 surgical anatomy of, 1428 
 Urethra, female, 1446 
 
 lymphatic vessels of, 803 
 mucous coat of, 1446 
 
 Urethra, female, muscular coat 
 of, 1446 
 orifice of, 1481 
 structure of, 1446 
 submucoxis coat of, 1446 
 
 male, 1441 
 bulb of, 1458 
 
 cavernous portion of, 1443 
 crest of, 1442 
 fossa navicularis of, 1444 
 lymphatic vessels of, 803 
 membranous portion of, 
 
 1442 
 mucous coat of, 1444 
 muscular layer of, 1445 
 
 portion of, 1442 
 pendulous portion of, 1443 
 penile portion of, 1443 
 prostatic portion of, 1441 
 spongy portion of, 1443 
 structure of, 1444 
 submucous tissue of, 1445 
 surgical anatomy of, 1445 
 Urinary bladder. See Bladder. 
 
 organs, 1411 
 Uterine artery, 687 
 
 portion of Fallopian tube, 
 1497 
 
 plexus of nerves, 1086 
 
 veins, 763 
 
 plexus of, 763 
 Utero-sacral ligaments, 1490 
 
 -vaginal plexus, 1086 
 
 -vesical fold, 1490 
 pouch, 1487, 1490 
 Uterus, 1486 
 
 abnormalities of, 1493 
 
 after parturition, 1494 
 
 appendages of, 1497 
 
 arbor vitaj of, 1492 
 
 arteries of, 1494 
 
 bicornate, 1493 
 
 body of, 1487 
 
 cavity of, 1491 
 
 changes induced bj' pregnancv 
 1493 
 at menstrual period, 1493 
 
 at different ages, 1493 
 
 folds of, 1489 
 
 fundus of, 1487 
 
 ganglia of, 1086 
 
 ligainents of, 1489 
 
 lymphatic vessels of, 803, 1495 
 
 masculinus, 1442 
 
 mucous membrane of, 1492 
 
 muscular coat of, 1491 
 
 neck of, 1488 
 
 nerves of, 1086, 1496 
 
 structure of, 1491 
 
 supravaginal portion of, 148S 
 
 surgical anatomy of, 1496 
 
 vaginal portion of, 1488 
 
 veins of, 1495 
 Utricle of vestibule, 1169 
 Uvea, 1118 
 Uvula of cerebellum, 931 
 
 of throat, 1211 
 
 vesicae, 1439 
 
 Vagina, 1483 
 arteries of, 1485 
 azygos arteries of, 687 
 columns of, 1484 
 erectile tissue of, 1485 
 lymphatic vessels of, 804. 1485 
 mucosa intertubercularis, 304 
 
 membrane of, 1484 
 muscular coat of, 1484 
 nerves of. 1485 
 
INDEX 
 
 1599> 
 
 Vagina, orifice of, 1481 
 
 relations of, 1484 
 
 rugae of, 1484 
 
 structure of, 1484 
 
 veins of, 1485 
 
 vestibule of, 1481 
 Vaginal artery, 687 
 
 bulb, 1483 
 
 fornix, 1484 
 
 plexus of nerves, 1086 
 
 portion of uterus, 1488 
 
 process of temporal bone, 89 
 
 synovial membrane, 263 
 
 veins, 763 
 
 plexuses of, 763 
 Vagus nerve, nuclei of, 950 
 Valentin, ganglion of, 1033 
 Vallecula of cerebellum, 926 
 
 epiglottica, 1365 
 
 Sylvii, 856 
 Valley of cerebellum, 926 
 Valsalva, sinuses of, aortic, 573 
 
 pulmonary, 571 
 Valve or valves, anal, 1319 
 
 of Bauhin, 1308 
 
 bicuspid, 572 
 
 coronary, 567 
 
 Eastacliian, 567 
 in foetus, 578 
 
 of Gerlach, 1303 
 
 of Guerin, 1444 
 
 of Hasner, 1142 
 
 Houston's, 1318 
 
 ileo-cffical, 1308 . 
 
 of Kerkring, 1291 
 
 of Morgagni, 1319 
 
 pvloric, 1272 
 
 rectal, 1318 
 
 semilunar, 1319 
 aortic, 572 
 pulmonic, 571 
 
 Thebesian, 567, 771 
 
 tricuspid, 570 
 
 of Vieussens, 910, 933 
 Valvulaj conniventes, 1291 
 Vas deferens, 1472 
 artery of, 686 
 lymphatic vessels of, 804 
 structure of, 1473 
 
 spirale, 1173 
 Vasa brevia arteries, 674 
 
 intestini tenuis artery, 675 
 
 vasorum of arteries, 586 
 Vascular papillae, 1181 
 
 system at birth, changes in, 
 581 
 in foetus, 578 
 Vasomotor nerves, 1071 
 Vastus extemus muscle, 517 
 
 internus muscle, 517 
 Vater, ampulla of, 1345 
 
 corpuscles of, 828 
 Veins, 721 
 
 of abdomen, 755 
 
 anastomotic, of Troland, 735 
 
 angular, 726 
 
 appendicular, 768 
 
 of arm, 744 
 
 auricular, 727 
 
 axillary, 747 
 
 azygos, 752 
 larger, 752 
 left lower, 753 
 
 upper, 753 
 right, 752 
 smaller, 753 
 
 basilar, 735 
 
 basilic, 746 
 median, 746 
 
 brachial, 747 
 
 brachio-cephalic, 750 
 
 Veins of bones, 41 
 bronchial, 753 
 buccal, 726 
 cardiac, 770 
 cava, inferior, 764 
 
 superior, 752 
 cephaUc, 747 
 
 median, 746 
 cerebellar, 736 
 cerebral, 734 
 cervical, anterior, deep, 733 
 
 posterior, deep, 733 
 choroid, 735 
 circumflex, iliac, 759 
 
 superficial, 756 
 companion, 747 
 coronary, 768 
 costo-axillary, 748 
 cystic, 769 
 digital, hand, 745 
 of diploe, 733 
 dorsal, of penis, 762 
 dorsi-spinal, 753 
 of dura mater of brain, 849 
 emissary, 743 
 emulgent, 766 
 epigastric, deep, 759 
 
 superficial, 756 
 of face, exterior of, 725 
 facial, 726 
 femoral, 758 
 
 of fingers, superficial, 745 
 of foot, 758 
 frontal, 725 
 of Galen, 735 
 gastric, 768 
 gluteal, 761 
 haemorrhoidal, external, 760 
 
 inferior, 760 
 
 middle, 760 
 
 superior, 768 
 of hand, superficial, 745 
 of. head, 724 
 of heart, 577 
 hepatic, 767 
 histology of, 722 
 hypogastric, 760 
 iliac, circumflex, deep, 759 
 
 common, 764 
 
 external, 759 
 
 internal, 760 
 ilio-lumbar, 764 
 innominate, 750 
 intercostal, 752 
 interosseous, of forearm, 747 
 intervertebral, 755 
 intralobular, 767 
 jugular, 728 
 laryngeal, inferior, 751 
 lingual, 729 
 
 longitudinal, inferior, 738 
 of lower extremity, 755 
 lumbar, 765 
 
 ascending, 753, 765 
 right, 752 
 mammary, internal, 750 
 masseteric, 726 
 maxillary, internal, 727 
 median, 745 
 medulli-spinal, 755 
 meningeal, 730, 734 
 meningo-rachidian, 754, 833 
 mesenteric, 768 
 naso-frontal, 740 
 of neck, 725 
 obturator, 761 
 occipital, 727 
 oesophageal, 751 
 ophthalmic, 740 
 orbital, 727 
 ovarian, 766 
 
 Veins, palatine, 727 
 palmar, deep, 747 
 pancreatic, 769 
 of pelvis, 755 
 peroneal, 758 
 pharyngeal, 730 
 phrenic, 767 
 
 of pia mater of brain, 856 
 plantar, 758 
 plexus of, palmar, 745 
 
 pampinniform, 765 
 
 pharyngeal, 730 
 
 prostatic, 761 
 
 prostatico-vesical, 761 
 
 pterygoid, 727 
 
 spermatic, 765 
 
 spinal, 753 
 
 on thyroid body, 751 
 
 uterine, 763 
 
 vaginal, 763 
 
 vesical, inferior, 763- 
 superior, 761 
 popliteal, 758 
 portal, 769 
 
 system of, 768 
 profunda femoris, 759- 
 pterygoid plexus, 727 
 pudic, 760 
 pulmonary, 723 
 pyloric, 768 
 radial, 745 
 
 deep, 747 
 ranine, 729 
 renal, 767 
 sacral, lateral, 760 
 
 middle, 764 
 saphenous, 756 
 sciatic, 761 
 spermatic, 765 
 spinal, 753 
 splenic, 768 
 stylo-mastoid, 725 
 subclavian, 749 
 sublobular, 767 
 submaxillary, 727 
 submental, 727 
 supraorbital, 726 
 suprarenal, 767 
 sylvian, superficial, 735 
 systemic, 724 
 temporal, 727 
 temporo-maxillary, 727 
 thoracic, long, 748 
 thoracico-epigastric, 748 
 of thorax, 744 
 thyroid, accessory, 731 
 
 gland, 731 
 
 inferior, 751 
 
 middle, 730 
 
 superior, 730 
 thvroidea ima, 751 
 tibial, 758 
 tracheal, 751 
 ulnar, 745 
 
 of upper extremity, 744 
 uterine, 763 
 vaginal, 763 
 ventricular, 735 
 vermian, 735 
 
 of vertebrae, bodies of, 755 
 vertebral, 732, 751 
 Vidian, 730 
 Velum interpositum, 854, 901 
 medullary, 943 
 pendulum palati, 1211 
 Vena azygos major, 752 
 minor, 753 
 
 basis vertebrae, 49, 755 
 cava, ascending, 764 
 inferior, 764 
 
 peculiarities of, 764 
 
1600 
 
 INDEX 
 
 Vena cava, superior, 752 
 
 magna Galeni, 735 
 Venae basis vertebrarum, 755 
 comites, 723, 747 
 corporis striati, 735 
 interlobulares of kidney, 1423 
 Thebesii, 771 
 vorticosse, 1113 
 Venesection, 746 
 Venous arch, nasal, 725 
 plexus, interspinous, 732 
 on thyroid body, 751 
 Venter ilii, 209 
 
 of scapula, 171 
 Ventral auditory nuclei, 950 
 root of eighth nerve, 1050 
 of spinal nerve, 965 
 Ventricle of Arantius, 944 
 of brain, fifth, 897 
 fourth, 943 
 third, 901 
 Verga's, 896 
 of heart, fibres of, 575 
 
 left, chordse tendineae of, 573 
 
 columna; carnea; of, 573 
 right, 568 
 
 chordae tendinese of, 570 
 columnse carnese of, 570 
 of larynx, 1371 
 lateral, 888 
 Ventricular gray matter, 922 
 portion of heart, 568 
 veins, 735 
 Ventro-median fissure, 837 
 Verga's ventricle, 896 
 Vermian vein, 735 
 Vermiform appendix, 1303 
 arteries of, 1305 
 canal of, 1304 
 lymphatics of, 1306 
 mesentery of, 1260 
 mucous membrane of, 1305 
 muscular coat of, 1305 
 serous coat of, 1304 
 structure of, 1304 
 submucous coat of, 1305 
 surface form of, 1323 
 surgical anatomy of, 1325 
 veins of, 1306 
 process of cerebellum, 926 
 Vertebrae, 48 
 
 bodies of, veins of, 755 
 centrum of, 48 
 cervical, 49 
 
 sev-enth, 53 
 coccygeal, 61 
 development of, 58 
 •dorsal, 53 
 false, 61 
 
 general characters of, 48 
 immovable, 61 
 ligaments of, 270 
 lumbar, 56 
 
 process of, articular, 49 
 spinous, 49 
 transverse, 49 
 prominens, 53 
 sacral, 61 
 structure of, 58 
 thoracic, 53 
 Vertebral aponeurosis, 411, 416 
 artery, 637 
 
 surgical anatomy of, 639 
 border of scapula, 174 
 canal, 49 
 column, 48 
 
 articulations of, 269 
 surface form of, 69 
 surgical anatomy of, 69 
 foramen, 49 
 groove, 155 
 
 Vertebral, ligaments of, 270 
 
 plexus of nerves, 1077 
 
 region, anterior, muscles of, 406 
 lateral, muscles of, 408 
 muscles of, 409 
 
 ribs, 160 
 
 vein, 732, 751 
 Vertebrarterial foramen, 50 
 Vertebro-chondral ribs, 160 
 
 -pericardial ligaments, 558 
 
 -pleural ligament, 1385 
 
 -sternal ribs, 159 
 Vertex of skull, 129 
 Vertical lingualis muscle, 399 
 
 plate of palate bone, 117 
 Verumontanum, 1442 
 Vesical arteries, 686 
 
 plexus of nerves, 1086 
 of veins, inferior, 762 
 superior, 761 
 
 trigone, 1438 
 Vesicle, prostatic, 1442 
 Vesicles, Graafian, 1502 
 
 seminal, 1475 
 Vesico-uterine ligament, 1490 
 Vesicula prostatica, 1441 
 Vesicular column of Clark, 846 
 Vestibular artery, 1176 
 
 ganglion, 1053 
 
 nerve, 1053 
 path, 1054 
 
 root of eighth nerve, 1050 
 
 window, 1152 
 Vestibule, aortic, of Sibson, 572 
 
 of ear, 1164 
 
 of mouth, 1194 
 
 of nose, 1099 
 
 of vagina, 1481 
 Vestigial fold of pericardium, 561 
 Vibrissa, 1096 
 Vicq d'Azyr, bundle of, 883 
 Vidian artery, 616 
 
 canal, 96, 135 
 
 nerve, 1034 
 
 veins, 730 
 Vieussens, ansa of, 1076 
 
 centrum ovale majus of, 881 
 
 valve of, 910, 933 
 Villi of small intestine, 1292 
 
 S3movial, 262 
 Viscera, development of, 1235 
 Visceral cranium, 71 
 
 layer of pleura, 1382 
 
 lymphatics, 811 
 
 peritoneum, 1247 
 
 portion of tunica vaginalis, 
 1470 
 
 surface of liver, 1329 
 of stomach, 1270 
 Visual axis, 1106 
 
 centres, 1022 
 
 purple, 1120 
 Vitreous bod.y, 1129 
 
 humor of eye, 1129 
 
 table of skull, 34 
 Vocal cords, false, 1370 
 true, 1370 
 
 process, 1365 
 Voice, organs of, 1361 
 Volkmann's canals, 38 
 Voluntary muscle, 361 
 Vomer, 120 
 
 alffi of, 121, 143 
 
 articulations of, 122 
 
 development of, 122 
 
 surfaces of, 121 
 Vomerine cartilage, 1097 
 Vortex of heart, 575 
 Vulva, fossa navicularis of, 
 
 1478 
 Vulvo-vaginal gland, 1482 
 
 Waldeyer, germinal epithelium 
 of, 1501 
 odontoblasts of, 1201 
 Wedge bones, 247 
 
 -shaped funiculus, 941 
 Wharton's duct, 1216 
 White commissure of cord, 839 
 fibrous tissue, 261 
 line of Hilton, 1319 
 matter of cerebellum, 931 
 
 of cerebrum, 913 
 nerve fibres, 822 
 substance of cord, 841 
 of Schwann, 822 
 Willis, circle of, 629, 640 
 Winslow, accessory anterior cru- 
 ral nerve of, 1004 
 ligament of, posterior, 335 
 uncinate process of, 1348 
 Wirsung, canal of, 1351 
 Womb, 1486 
 Worm of cerebellum, 926 
 Wormian bones, 103 
 
 development of, 103 
 Wrisberg, cardiac ganglion of, 
 1081 
 cartilages of, 1365 
 cuneiform tubercle of, 1368 
 ligament of, 339 
 nerve of, 986 
 pars intermedia of, 1045 
 Wrist, articulations of, 317 
 bursa of, 492 
 -joint, 317 
 
 ligament of, 318 
 surface form of, 318 
 surgical anatomy of, 318 
 
 XiPHo-PERicARDiAL, ligament, 
 
 559 
 Xiphoid appendix, 158 
 surfaces of, 158 
 
 cartilage, 155 
 
 Y-LIGAMENT, 328 
 
 Yellow elastic tissue, 261 
 spot of Sommerring, 1121 
 
 Zinn, ligament of, 373 
 
 zonule of, 1129 
 Zona arcuata, 1173 
 
 fasciculata, 1430 
 
 glomerulosa, 1430 
 
 incerta, 910 
 
 orbicularis, 327 
 
 pectinata, 1173 
 
 reticularis, 1430 
 
 tecta, 1173 
 Zonula ciliaris, 1129 
 Zonule of Zinn, 1129 
 Zygoma, 84 
 Zygomatic arch, 138 
 
 fossa, 138 
 
 lymphatic glands, 782 
 
 process of malar, 115 
 of temporal bone, 84 
 Zygomaticus major muscle, 377 
 
 minor muscle, 377 
 Zymogen granules, 1352 
 
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