GOULD POCKET PRONOUNCING MEDICAL DIC- TION/ 40,000 1 Round It cont; science, Nerves, Scales, and Vd GOULD MEDI 3d Edit Thumt Edited The pla facts of points 1 most re LANG < ARY By the vised t Hospit; Philadt Besides other s satisfy! GORDO1 TION By Alf Diseas' UNIVERSITY OF CALIFORNIA MEDICAL CENTER LIBRARY SAN FRANCISCO GIFT OF MRS. FERDINANDSEN A diet nunciation or eacn wora m ling, i and scles, letric cians OF fork, mtial s the t the ON- I Re- ewish tsary, land tirely [ental pro- 2-30 HUGHES PRACTICE OF MEDICINE, 14th RE- VISED EDITION 63 Illustrations. Cloth, $4.00 Postpaid Revised by R. J. E. Scott, M.A., B.C.L., M.D. Formerly Attending Physician to the Demilt Dispensary, New York. It is a reliable guide in the field of general medicine, giving practical discussions of diseases, synonyms, definitions, causes, symptoms, pathology, diagnosis, prognosis, treatment, etc., and contains additional, special sections on mental diseases, diseases of the skin, and ductless glandular diseases. TRUMPER MEMORANDA OF TOXICOLOGY 2d Edition. Fabrikoid, $1.50 By Max Trumper, Ph. D., Formerly Lecturer on Toxicology, Jefferson Medical College, Philadelphia. The author has had much hospital experience and has seen cases of poisoning in their symptomatic conditions. The book is a practical, authoritative guide to the emergency treatment of poisoning and most recent progress in toxicology. AUTENREITH LABORATORY MANUAL FOR THE DETECTION OF POISONS AND POWER- FUL DRUGS. Cloth, $6.00 6th American Edition, Based on the 5th German Edition, but Completely Revised with Extensive Additions. With Colored Plates and 60 Text Illustrations. By Dr. Wilhelm Autenreith, Prof, in University of Freiburg; Au- thorized Translation by Wm. H. Warren, Ph.D., Professor of Organic Chemistry, Clark University, Worcester. Many new substances and methods have been included in this edition. MORRIS HUMAN ANATOMY, 8th EDITION 1164 Illustrations, 515 in Colors. Cloth, $10.00 A systematic treatise prepared by collaboration of a number of anatomists and Edited by C. M. Jackson, M.S., M.D., Pro- fessor and Director, Department of Anatomy, University of Minnesota. ELLIS ELEMENTS OF PATHOLOGY 95 Illustrations. Cloth, $5.00 By Aller G. Ellis, M.Sc.. M.D. Rockefeller Foundation Visiting Professor of Pathology and Director of Studies, Medical Department, Chulalongkorn University, Bangkok, Siam. One- time Associated Professor of Pathology, Jefferson Medical College, Philadelphia. This book has been written for beginners in pathology. A special effort has been made to explain elementary principles and to limit the text to the essentials. It shows the close relation of pathology to problems of internal medicine and surgery. I EDGAR- VAUX OBSTETRICS, 6th EDITION 684 Illustrations, 38 Colored Prints, 5 Colored Plates. Cloth, $8.00 By J. Clifton Edgar, Revised by Norris W. Vaux, Clinical Pro- fessor of Obstetrics, Jefferson Medical College and Hospital, Philadelphia. This new Edgar- Vaux Obstetrics is a distinctly practical guide, illustrated in detail by handsome engravings. The descriptive text is concise. It has been the aim to make the work a useful clinical manual. ? COMPEND OF HUMAN ANATOMY COMPENDS Each Volume, Cloth $2.00. HUMAN ANATOMY. 8th Edition. 16 Plates, 139 Text Illustrations. By S. O. L. Potter, M. D. Revised by D. G. Metheny, M. D. PHYSIOLOGY. i6th Edition. 27 Illustrations. By A. P. Brubaker, M. D. OBSTETRICS. loth Edition. 80 Illustrations. By H. G. Landis, M. D. Revised by Dr. Clifford B. Lull, M. D. MATERIA MEDICA, THERAPEUTICS AND PRESCRIPTION WRITING. 9th Edition. Accord with U. S. Phar. X. By S. O. L. Potter, M. D. Revised by A. D. Bush, M. D. GYNECOLOGY. 5th Edition. 167 Illustrations. By Wm. H. Wells, M. D. Revised by W. G. Harer, M. D. DISEASES OF THE EYE AND REFRACTION. 4th Edition. 109 Illustrations. By G. M. Gould, M. D. and W. L. Pyle, M. D. SURGERY. Bandaging and Minor Surgery. 185 Illus- trations. By Benjamin Lipshutz, M. D. MEDICAL CHEMISTRY. 7th Edition. By Henry Leff- mann, M. D. and Max Trumper, A. M. PHARMACY. loth Edition. Based upon Remington's Pharmacy, U. S. Phar. and U. S. Formulary. By F. E. Stewart, M. D. Revised by H. W. Youngken, M. D. DISEASES OF THE SKIN. 7th Edition. 119 Illustra- tions. By J. F. Schamberg, M. D. GENITO-URINARY DISEASES AND SYPHILIS. 4th Edi- tion. 44 Illustrations. By C. S. Hirsch, M. D. BACTERIOLOGY. 4th Edition. 86 Illustrations. By R. L. Pitfield, M. D. P. BLAKISTON'S SON & Co. Philadelphia POTTER'S C O M P E N D OF HUMAN ANATOMY REVISED BY D. GREGG METHENY M. D., L. R. C. P. AND S. (EDTN.), L. F. P. S. (GLASGOW) ASSOCIATE IN ANATOMY, JEFFERSON MEDICAL COLLEGE, PHILADELPHIA EIGHTH EDITION WITH 139 ILLUSTRATIONS; ALSO NUMEROUS TABLES AND 16 PLATES OF THE ARTERIES AND NERVES PHILADELPHIA P. BLAKISTON'S SON & CO., INC 1012 WALNUT STREET COPYRIGHT, 1915, BY P. BLAKISTON'S SON & Co. PRINTED IN U. S. A. BY THE MAPLE PRESS COMPANY, YORK, PA. PREFACE TO THE EIGHTH EDITION After many years of wandering in the embryological minutiae of " trans- cendental anatomy," it has at last become apparent to most teachers and examiners in anatomy that the only kind of anatomy that could be of any practical value to a physician or surgeon, as such, is the anatomy that can be actually seen and handled. Consequently in this text, details of embryology, histology, and physiology have been largely left to the text- books dealing with those subjects, in order that gross human anatomy might be the more thoroughly explained. While all of the "recognized authorities" and the publications of the various anatomical associations have been freely consulted, these descrip- tions have been based entirely on the actual facts to be found in the human body and are not dominated by any one single authority. The many new discoveries and the changes in teaching methods that have been made in recent years, have made it necessary to make so many additions and changes in the text that the entire work had to be rewritten. Parts of the nomenclature of the German Anatomical Society are now being used so universally, that it became necessary to include it, in its entirety, in the Latin form. However, since comparative anatomy has been almost entirely ignored in the B.N.A., and as so many of its terms are not only inconsistent but also evidence personality rather than broad anatomical principles, it seems certain that it still requires much revision if it is to endure; therefore while the B.N.A. terms are given in the Latin form, only such of them as seem entitled to survival are given in the English form in preference to the older regular terms. It is confidently hoped that the student will find these descriptions not only accurate and up-to-date, but intelligible as well. D. GREGG METHENY. 4609 SPRUCE ST., PHILADELPHIA. 2.112.2, PREFACE TO THE SEVENTH EDITION The twenty years which have elapsed since this compend was first issued have brought many changes of nomenclature and description into the teaching of Anatomy. The present edition has been entirely re-written and brought into harmony with the latest text-books on this subject. The text has been expanded wherever greater detail seemed desirable, but in so doing the condensed form of statement heretofore adopted has been carefully followed. The total number of illustrations has been increased from 117 to 138, and many of the cuts used in former editions have been replaced by newer ones. The Tables and Plates, heretofore published in an appendix, have been thoroughly revised, and are now placed in their natural positions in the text. These changes have increased the size of the volume by 82 pages, and have made it practically a new book, which the author hopes will receive a continu- ance of the favor heretofore extended to the previous editions. Originally designed for the use of the medical student in preparing for the exercises of the quiz-room and for his examinations, the text is confined to the essentials of each structure treated of, which are arranged in such a manner as to facilitate their rapid acquirement. All super- fluities of description have been studiously avoided, and only such matter inserted as should be thoroughly known in order to pass a rigid examina- tion on any organ or structure of the human body. The descriptions will be found to closely follow Gray, though Morris, Quain, and other recog- nized authorities have been freely consulted during the preparation of the text. For many of the special arrangements the author is indebted to the lectures of Professor W. H. Pancoast, formerly of Jefferson Medical vii Vlll PREFACE TO THE SEVENTH EDITION College, and to the quizzes of Dr. Henry Morris, at one time assistant to the chair of Anatomy in the same school. While striving to carry out the object of this series in furnishing the medical student with a condensed manual of Anatomy, the author has endeavored, from a strong appreciation of the importance of the subject, to make this volume deserving of first rank among its kind; and believing that a judicious condensation, which does not slight the essential features of the subjects treated, cannot fail to be of benefit in any department of science, he again commits this compend to the teachers and students of Anatomy, in the hope that it may continue to be found worthy of a place alongside the more exhaustive and exhausting text-books. SAM'L O. L. POTTER. CONTENTS FACE OSTEOLOGY i BONES OF THE TRUNK. . . . 5 VERTEBRAL COLUMN 5 THORAX 7 PELVIS 9 BONES OF THE HEAD 14 ORBITS 35 FOSSAE 37 SUTURES AND FONTANELLES 39 FORAMINA AT THE BASE OF THE SKULL 41 POINTS AT THE BASE OF THE SKULL 44 BONES OF THE UPPER EXTREMITY 44 OF THE SHOULDER 44 OF THE ARM 47 OF THE FOREARM 48 OF THE HAND 50 BONES OF THE LOWER EXTREMITY 52 OF THE THIGH 52 OF THE LEG 54 OF THE FOOT 56 ARTICULATIONS 58 ARTICULATIONS OF THE TRUNK 60 OF THE UPPER EXTREMITY .* 64 OF THE LOWER EXTREMITY 68 MUSCLES AND FASCIAE 73 MUSCLES OF THE HEAD 75 OF THE EAR 79 OF THE NECK 80 ix X CONTENTS PAGE OF THE LARYNX AND EPIGLOTTIS 85 OF THE BACK 86 OF THE THORAX 93 OF THE ABDOMEN 95 OF THE PELVIC OUTLET 97 OF THE PERINEUM 98 OF THE UPPER EXTREMITY 99 OF THE LOWER EXTREMITY 107 FASCIA OF THE HAND 105 LUMBO-DORSAL 90 OF THE ILIAC REGION 107 OF THE THIGH 108 OF THE FOOT 115 THE BLOOD-VASCULAR SYSTEM 118 HEART 118 ARTERIES 122 PULMONARY ARTERY AND AORTA 122 ARTERIES OF THE HEAD AND NECK 124 CIRCLE OF WILLIS 128 TRIANGLES OF THE NECK 128 ARTERIES OF THE UPPER EXTREMITY 130 OF THE TRUNK 136 OF THE LOWER EXTREMITY 141 ARTERIAL ANASTOMOSES 145 TABLES AND PLATES OF THE ARTERIAL SYSTEM . 147 VEINS OF THE HEAD AND NECK 163 OF THE UPPER EXTREMITY 166 OF THE THORAX 167 OF THE LOWER EXTREMITY, PELVIS AND ABDOMEN. . . . 168 OF THE HEART 171 THE LYMPHATIC SYSTEM 171 LYMPHATICS OF THE HEAD AND NECK 172 OF THE UPPER AND LOWER EXTREMITIES 173 OF THE PELVIS, ABDOMEN, INTESTINES, THORAX . . . .174 CONTENTS XI PAGE THE NERVOUS SYSTEM 175 BRAIN 178 MENINGES 180 CEREBRUM 183 CEREBELLUM 206 MEDULLA OBLONGATA 208 NERVE-TRACTS IN THE BRAIN 212 SPINAL CORD 213 NERVE-TRACTS IN THE SPINAL CORD 214 CRANIAL NERVES 216 GANGLIA OF THE CRANIAL NERVES 223 SPINAL NERVES .' 226 CERVICAL NERVES 227 THORACIC NERVES ' 231 LUMBAR NERVES 232 SACRAL AND COCCYGEAL NERVES 233 SYMPATHETIC SYSTEM 236 GANGLIATED CORD 237 GREAT PLEXUSES 239 TABLES AND PLATES OF THE NERVOUS SYSTEM. . 243 ORGANS OF SPECIAL SENSE 270 SKIN 270 APPENDAGES OF THE SKIN . 272 TONGUE 273 NOSE 276 EYE 280 SCLEROTIC AND CORNEA 281 CHOROID, CILIARY BODY AND IRIS 283 RETINA 285 MUSCLES AND NERVES OF THE EYEBALL 289 VESSELS AND NERVES OF THE EYE 289 APPENDAGES OF THE EYE 293 EAR 296 EXTERNAL EAR 297 MEMBRANA TYMPANI 298 Xll CONTENTS PAGE TYMPANUM 300 EUSTACHIAN TUBE 303 INTERNAL EAR 304 AUDITORY NERVE 310 ORGANS OF DIGESTION 312 MOUTH 312 PALATE AND TONSILS 313 SALIVARY GLANDS 315 TEETH 317 PHARYNX . . '. 320 (ESOPHAGUS - 322 ABDOMEN 323 PERITONEUM 325 STOMACH 328 SMALL INTESTINE 33 o LARGE INTESTINE 333 LIVER 33 6 STRUCTURE . . .' 339 VESSELS 341 EXCRETORY APPARATUS. 342 PANCREAS 343 LESSER PANCREAS 344 DUCTLESS GLANDS 344 THYROID AND THYMUS GLANDS 345 SPLEEN 348 ORGANS OF VOICE AND RESPIRATION 350 LARYNX 350 TRACHEA AND BRONCHI 355 PLEURAE 356 MEDIASTINUM 356 LUNGS 357 THE URINARY ORGANS . . 360 CONTENTS Xlll PACE KIDNEYS 360 URETERS 363 SUPRA-RENAL CAPSULES 364 BLADDER 365 MALE URETHRA 3 68 FEMALE URETHRA 37 THE MALE ORGANS OF GENERATION 370 URETHRAL GLANDS IN THE MALE 370 PENIS 37i TESTES 372 APPENDAGES OF THE TESTES 375 THE FEMALE ORGANS OF GENERATION 377 VULVA 377 VAGINA 379 UTERUS 380 APPENDAGES OF THE UTERUS 382 MAMM.E 383 HSRNIA 384 INGUINAL HERNIA 385 FEMORAL HERNIA 388 THE PERINJEUM 39* PELVIC CAVITY AND FASCIA 391 MALE PERINEUM 393 ISCHIO-RECTAL REGION 394 FEMALE PERINEUM 395 LITHOTOMY 396 INDEX . 399 XIV ABBREVIATIONS EXPLANATION ABBREVIATIONS Anas. . . Ant. . . Art. or A. Asc. . . Br. . . . Cerv. . . Com. . . Commun. Desc. . . Ext. Anastomoses. Inf. . . . Inferior. Anterior. Int. . . . Internal. Artery. L Left. Ascending. M Middle. Branch. N Nerve. Cervical. PI Plexus. Common. Post.. . . Posterior. Communicating. R Right. Descending. Sup. . . . Superior. External. Superf . . . Superficial. Trans . . Transverse. EXPLANATION Figures or letters in parentheses, .thus (14), (a), refer to the same figures or letters on the adjoining illustration; except in the Tables of Arteries, in which figures in parentheses serve as cross-references to other divisions of the tables. A COMPEND OF HUMAN ANATOMY The term Anatomy is derived from the Greek a.va, through, and T\nvi,v, to cut, it strictly means dissection, but is technically applied to that science which treats of the structure of organized bodies. The divisions of Descriptive Human Anatomy are, Osteology, the anatomy of the bones; Syndesmology, of the joints; Myology, of the muscles; Angiology, of the vessels; Neurology, of the nerves; Splanchnology, of the internal viscera; Adenology, of the glands; Dermatology, of the skin; Genesiology, of the generative organs. OSTEOLOGY The number of Bones in the Adult Human Skeleton is variously stated by different anatomists. Excluding the teeth (which belong to the tegumentary system), the Wormian and the sesamoid bones, the number is 206. Excluding also the 6 ossicles of the middle ear the whole number would be 200. Leaving out also the 2 patellae and the hyoid bone, the number in the skeleton proper would be 197 bones. Of these, the vertebral column contains 26, the cranium 8, the face 14, the walls of the thorax (sternum and ribs) 25, the upper extremities 64, and the lower extremities 60. They are divisible into four classes, the long and short medullated, and the flat and irregular cancellous bones. Long Bones number 90, act as supports, or levers, and are known by having a medullary canal. in the centre of each, a shaft (diaphysis), and two extremities. They are developed by osseous deposit in cartilage, and include the clavicle, humerus, radius, ulna, femur, tibia, fibula, meta- carpal and metatarsal bones, and the phalanges. Short Bones number 30, and are found where strength is required, but limited motion. They are also developed by osseous deposit in cartilage and include the bones of the carpus and tarsus, the former having 16 and the latter 14. 2 HUMAN ANATOMY Flat Bones number 38, protect the viscera by forming walls around them, and afford extensive attachment for muscles. They are developed by osseous deposit in membranes, and consist of 2 dense layers, separated by a cellular or cancellous osseous tissue, the diploe. They include the oc- cipital (os occipitale), parietal (os parietale), and frontal (os frontale) '(bones of the cranium); the nasal (os nasale), lacrimal (os lacrimale), and vomer (bones of the face); the scapula, os innominatum (os coxae), sternum and ribs (costae). Irregular Bones are 39 in number, and include the vertebrae, sacrum, coccyx (coccygis), the temporal, ethmoid, and sphenoid bones, and the bones of the face, except the nasal (os nasale), lacrimal (os lacrimale), and vomer. Bones of the Head number 22, and comprise the Cranial Bones 8, the frontal, 2 parietal (ossa parietalia) , occipital (os occipitale), 2 temporal (ossa temporalia), the sphenoid and the ethmoid (os ethmoidale) . Facial Bones 14, 2 maxillary (maxillae), 2 malar (ossa zygomatica), 2 nasal (ossa nasalia), 2 lacrrmal (ossa lacrimalia), 2 palate (ossa palatina), 2 inferior turbinal (conchae nasales inferiores), vomer and mandible. Bones of the Trunk number 53, as follows, viz. Vertebra 24, 7 cervical, 12 thoracic, and 5 lumbar vertebrae. Thorax 25, 7 pairs of true ribs, 3 pairs of false ribs, 2 pairs of floating ribs (articulating with the bodies of the thoracic vertebrae), and the sternum. Pelvis 4, the sacrum, the coccyx (os coccygis), and 2 ossainnominata (ossa coxae) each os innominatum consisting of 3, the ilium (coxae), ischium, and pubis. Bones of each Upper Extremity number 32, as follows: Shoulder 2, the clavicle (clavicula) and scapula. Arm i, the humerus. Forearm 2, the radius and ulna. Hand 27, 8 carpal bones, the scaphoid (os naviculare), semilunar (os triquetrum), cuneiform, pisiform (os pisiforme), trapezium (os mul- tangulum majus), trapezoid (os multangulum minus), os magnum (os capitatum), and unciform (os hamatum), 5 metacarpal, and 14 phalanges. Bones of each Lower Extremity number 29, viz. Thigh i, the femur. Leg 2, the tibia and fibula. OSTEOLOGY 3 Foot 26, 7 tarsal bones, the astragalus (talus), os calcis (calcaneus), scaphoid, (naviculare pedis), cuboid (os cuboideum), external, (tertium) middle (secundum), and internal cuneiform (primum), 5 meta tarsal, 14 phalanges. Unclassified Bones are the Patella 2, which are sesamoid bones, each developed in the tendon of the quadriceps extensor femoris muscle. Hyoid Bone (os hyoideum) i, the tongue-bone not articulated to the skeleton. Malleus, Incus Stapes (3 pairs), the bones of the middle ear (ossicula auditis). Sesamoid Bones, of variable number, situated in the tendons of the gastrocnemius and peroneus longus muscles, and in the flexor tendons of the great toe and the thumb. Wormian Bones (ossa Suturarum), sometimes found in the cranial sutures, are not constant in number or size. Principal Eminences on Bones. Heads are convex and smooth, for articulation in movable joints. Condyles are irregularly shaped heads. Trochamers, when for turning the bone. Tuberosities are broad, uneven prominences. Tubercles are small tuberosities. Spines, or Spinous proc- esses, when sharp and slender. Apophysis (an excrescence), is a process or marked bony prominence which has never been separate from the bone. Epiphysis (an accretion), is a process which was developed sepa- rately and afterward became united to the bone by ossification of the intermediate tissue. Other Names given to Bony Prominences. There are several adject tives applied to them from their fancied resemblances, such as Azygod, without a fellow; Clinoid, like a bed; Coracoid, like a crow's beak; Coronoi,- hooked like a cow's horn; Hamular, hook-like; Malleolar, like a mallet; Mastoid, like a nipple; Odontoid, tooth-like; Pterygoid, wing-like; Rostrum, a beak; Spinous, thorn-like; Styloid, pen-like; Squamous, scaly; Vaginal, ensheathing, etc. Cavities of Bones. Articular cavities are called Cotyloid, cup-like; Ctenoid, shallow; Trochlear, pulley-like; Facet, if smooth; Alveolar or Alveoli, when socket-like. Non-articular cavities are named fossae, sinu- ses, aqueducts, foramina, canals, fissures, notches, cells, grooves, depres- sions, etc. Composition of Bone. Organic or animal matter, about ^, consisting of gelatin, vessels and fat. Inorganic, or mineral, about %, consisting of 4 HUMAN ANATOMY phosphate and carbonate of calcium (62^ per cent.), with fluoride of calcium, phosphates of magnesium, sodium, and chloride of sodium (4^ per cent.). Heat will remove the organic matter and leave the inorganic; dilute Nitric or Hydrochloric acid will remove the inorganic, and leave the organic. In old age the inorganic constituents predominate, and the bones are brittle; in youth the organic predominate, and epiphyseal dislocation is more common than fracture, especially in the long bones of the extremities. Structure of Bone. Bone is composed of an outer compact layer, and an inner cellular or spongy structure. It is surrounded, except at the articu- lar cartilages, by a vascular fibrous membrane, the Periosteum, which receives the insertions of all tendons, ligaments, etc.; and the central cavity of long bones is lined by a similar structure, the Endosteum. The trans- verse section of the bone, examined microscopically, shows Haversian Canals, diameter /^oo inch, for the passage of vessels. Canaliculi, diameter Keooo inch, radiating from the canals, and con- necting them with the lacunae. Lacuna, arranged circularly around the canals, and contain the bone-cells, appearing as irregular dark spaces. Haversian Spaces, connect the canals with the medullary spaces, and divide one Haversian system from another. An Haversian System comprises an Haversian canal with its lamellae, lacunae, and canaliculi. Concentric Lamella, of bone tissue, around the canals. Circumferential Lamella, are bone layers binding the canals together. ~j Interstitial Lamella, woven in between the concentric lamellae. The Marrow of Bone. In young bones it is a tenacious, transparent fluid, free from fat. In adult bones it is of a yellow color, and consists of fat in varying proportion and extractive matters. It is found in the medullary canal, the cancellous texture, and the large Haversian spaces. Vessels found in Bones. Arteries, veins, and some say lymphatics. The Arteries are, the nutrient, entering at the nutrient foramen; the articular, nourishing the cancellous structure; and the periosteal, which supply the periosteum and the compact structure. The Veins emerge from the ends, the shaft, and from the nutrient foramen. The process of Ossification. The site of bone is first occupied by a mucoid substance, which becomes temporary cartilage (blastema) in the second month of foetal life. The young bone-cells (osteo-blasts) are then deposited in the cartilage at certain points, and their deposition and subsequent pressure cause the absorption of the cartilage. In most of the bones of the head and face, ossification is intra-membranous instead THE VERTEBRAL COLUMN 5 of intra-cartilaginous. The first bones in which ossification appears are the clavicle and inferior maxillary (5th to 7th foetal week); the last is the pisiform bone (i2th year). Epiphyses ossify after birth and begin uniting to the bone from the age of puberty, and in the inverse order to that in which their ossification began, except the lower end of the fibula, which ossifies and is joined to the shaft earlier than its upper end. , THE BONES OF THE TRUNK A*- 3V THE VERTEBRAL COLUMN Characteristics common to the Vertebrae. Each of the 24 spinal vertebrae consists of a body and an arch, the latter being formed by 2 radix arcus vertebrae (pedicles) and 2 laminae, which support 7 processes. The Body (corpus vertebrae) is thick and spongy, convex in front (i) from side to side, concave vertically, and on the upper and lower surfaces, which are surrounded by a bony rim. PIG. i. Anteriorly are small foramina for nutrient vessels, posteriorly a large foramen for the exit of 5! the venae basis vertebrarum. Pedicles (radix arcus vertebrae) (7), project backward from the body, inclining outwardly. They are notched above and below (incisura vertebralis su- perior et inferior), thus form- ing, with the adjacent notches, the Inter vertebral Foramina (Foramina Intervertebralia) for the entrance of vessels and the exit of the spinal nerves. Lamina, are 2 broad plates, meeting in the spinous process behind, and rough on their upper and lower borders for the attachment of the ligamentum subflava. Transverse Processes (4), one on each side projecting outward; those of the first ten thoracic vertebrae have articular facets (5) for the tubercles of the ribs. Articular Processes (Zygapophyses) (6), two on each side, superior (6) and inferior, project from the junction of the laminae and pedicles, and articulate above and below with the articular processes of the HUMAN ANATOMY adjacent vertebrae. Their upper facets look backwards and upwards in the cervical region, backwards and outwards in the thoracic, and backwards and inwards in the lumbar. Spinous Process (3), projects backward from the junction of the laminae with each other, sometimes very obliquely. Spinal Foramen (foramen vertebrale) (2), is the space enclosed by the body, pedicles and laminae, and which, when the vertebrae are articu- lated, forms part of the spinal or neural canal. The Spinal Vertebrae are distinguished as cervical 7, thoracic 12, and lumbar 5. Each of these divisions has several peculiar features, but their especial characteristics are as follows: Cervical Vertebra, are pierced at the bases of their transverse processes by the costo-transverse foramina, which transmit the vertebral artery, vein, and plexus. The anterior boundary of a costo-transverse foramen is called the Costal process, it is a true cervical rib. Its termination is called anterior tubercle of the transverse process. The posterior tubercle is the tip of the true transverse process. The superior articular facets look backwards and upwards. Thoracic Vertebrae, have facets and demifacets on their bodies, for articulation with the heads of the ribs, these facets are called the foveae costales. The superior articular facets look backwards and outwards. Lumbar Vertebra, are marked by the absence of the foramina and facets which distinguish the other two classes. The superior articular facets look backwards and inwards. Peculiar Vertebrae are 9 in number, the Atlas or ist cervical, the Axis or 2d cervical (epistropheus), the Vertebra Prominens, or 7th cervical (the ist thoracic is nearly always more prominent), the ist, Qth, icth, nth, and i2th thoracic, and the 5th lumbar. The ^Jlas (3), is a bony ring sup- porting the head. A bony arch takes the place of a body, and its spinous process is a mere tubercle. Its Lat- eral Masses (i) form its chief bulk, supporting large Articular Processes (foveae articulares), which look inwards, the superior (2) articulating with the condyles of the occipital bone. FIG. 2. THE THORAX 7 Axis (9), is marked by its Odontoid Process (dens) (10) projecting up- ward from the body into the anterior part of the spinal foramen of the atlas, where it articulates with the anterior arch (3), and receives the occipito-axoid (ligamentum apicis dentis) and the check liga- ments (ligamenta alaria). Its transverse processes (8) are very small and are not bifid. Its inferior articular surfaces (7) have the same direction as those of the other cervical vertebrae. Vertebra Prominens, has a long and prominent spinous process which ends in a tubercle for the ligamentum nuchae. Thoracic Vertebra. The ist has one facet and a demifacet for the ist and 2d ribs. The gth has a demifacet only. The loth has but one facet on the body and one on the transverse process. The nth and 1 2th have each but one facet on the body, and none on the transverse processes. The i2th resembles a lumbar vertebra in size and shape. 5th Lumbar Vertebra, is much deeper in front than behind; its spinous process is small, but its transverse processes are large and thick, and point slightly upward. Important Relations of Certain Vertebrae. 3 inches in the male, all around. Outlet (apertura pelvis minor inferior), is bounded by the pubic arch above (n), the tip of the coccyx (os coccygis) behind, and the tuberosities of the ischia (9) laterally. Its axis, if prolonged, would touch the promontory of the sacrum. Its diameters in the female are each about 4^ inches, in the male about 3^ inches. Chief Differences between the male and female pelves. The male pelvis is marked by strength of the bones, prominence of the muscular impressions, a deep and narrow cavity, and large obturator foramina. The female pelvis has lighter bones, broader iliac fossae, the spines being further apart, greater diameters at every point, the sacrum less curved, and the pubic arch wider. The Sacrum, or sacred bone, is triangular, curved, with its convexity backward, and is situated, base upwards, between the ossa innominata (coxae) forming with the coccyx the posterior wall of the pelvis. The bone consists of a central portion (4) which consists of the coalesced bodies of five vertebrae, and on each side a pars lateralis (lateral mass) or ala (wing) THE PELVIS II FIG. 5. which is made by the fusion of the transverse processes and what might be called "pelvic ribs." Therefore the pars lateralis presents a trans- verse portion and a costal or alar portion. The sacrum presents the following points, viz. Ridges (cristae sacral es articulares) (4), four transversely across both surfaces, mark the union of its original seg- ments. Anterior Sacral Foramina, eight for the an- terior sacral nerves. Grooves (5), eight shallow and broad, for the aforesaid nerves. Promontory, at its junction with the last lum- bar vertebrae. Posterior Sacral Foramina, eight for the pos- terior sacral nerves. Tubercles, representing the spinous processes of the segments. Groove, posteriorly, on each side of the spinous tubercles. Cornua, two at the posterior inferior portion of the bone. Articular Surface (3), on each side, articulates with the ilium. Notch, laterally and inferiorly, for the 5th sacral nerve. Base (2), has all the characteristics of the lumbar vertebrae, with the last of which it articulates. Apex (16), has an oval surface for articulation with the coccyx. Sacral Canal, the continuation of the spinal canal, is incomplete pos- teriorly at its lower end. It transmits the Cauda Equina; into it open the sacral foramina laterally. The Coccyx consists of 4 (or 5) rudimentary caudal vertebrae coalesced FlG 6 into a triangular bone, the base (i) of which articu- lates with the apex of the sacrum. Its posterior sur- face is rough for muscles and ligaments, its anterior surface is smooth and marked by ridges at the junction of its constituent vertebrae. It presents the following points: Cornua (2), two superiorly,, articulating with the sacral cornua to form foramina for the 5th sacral nerves. Apex, is sometimes bifid and turned to one side. The Ossa Innominate (coxae), are placed one on each side of the osseous pelvis, and are each formed by the union, about puberty, 12 HUMAN ANATOMY of 3 bones, the ilium, ischium, and pubes. The innominate (os coxae) as a whole presents the following points, viz. It is a large flat bone, constricted in the middle, and twisted upon its long axis, so that the expanded portion (iliac) above the constriction is in a plane almost at right angles to that of the expanded portion (ischio- pubic) below. It presents an outer surface, an inner surface, and a con- tinuous border which is circumferential. Beginning at its upper part the border of the os coxae (innominate or hip bone), it presents a crest (i), and, continuing forwards and around, the anterior superior spine (2), a shallow notch, the anterior inferior spine (4), a smaller notch, the ilio- pectineal eminence (5), superior (ascending) ramus or body of the ossis pubis, pubic tubercle (spine) and crest of pubis (9), the symphysis ossis pubis, the ischio-pubic ramus (9), constituted in front by the inferior (hori- zontal or descending) ramus of the pubis and behind by the ramus of the ischium, the tuber ischiadicum (tuberosity of the ischium) 12, the lesser sciatic (sacro-sciatic) notch (13), the ischial spine 14, the greater sciatic (sacro-iliac) notch (16), the posterior inferior spine of the ilium (17), and lastly the posterior superior spine of the ilium. The inner surface is divided by the ilio-pectineal line into an upper portion and a lower portion. The upper portion (false pelvis) presents in front the iliac fossa, and behind, the articular (auricular) surface and a rough surface for the posterior sacro- iliac ligament. The lower part of the inner surface (true pelvis) presents the obturator groove and the obturator foramen (8). In addition to what is described with the ilium, ischium and pubes, the outer surface presents : Acetabulum, or cotyloid cavity, receives the head of the femur. It is situated at the junction of the 3 bones externally, the ilium and ischium each forming about two-fifths, and the pubic bone one-fifth of it. A depression in its centre lodges a mass of fat containing vessels for the nourishment of the synovial membrane. The Cotyloid Notch (Incisura Acetabuli) is a deficiency in its lower margin, trans- mitting nutrient vessels to the joint; to the edges of the notch is attached the ligamentum teres, and it is bridged over by the trans- verse ligament, a continuation of the cotyloid ligament (labrum glenoidale) which surmounts the brim of the acetabulum. Crossing the ischium horizontally, immediately below the acetabulum, is a deep groove for the obturator externus tendon. Obturator or Thyroid Foramen (8), on the anterior surface between the pubes and ischium, large and oval in the male, small and triangular in the female; is closed by the obturator membrane, except above THE PELVIS 13 at the obturator canal or groove where the obturator nerves and vessels pass through. The Ilium is the superior part of the innominate bone, its outer surface presents the following points, viz. Crest (i), along its upper border, having an outer and inner lip for muscular attachment, and ending in the superior spines. Anterior Superior Spine (2), to which are attached the sartorius and tensor fasciae (vaginae) femoris muscles and the inguinal (Poupart's) ligament. Anterior Inferior Spine (4), for the straight tendon of the rectus femoris. Notch, between the above-named spines, transmitting the external (lateral) cu- taneous nerve, and lodging some fibres of the sartorius. Posterior Superior Spine (19), for the at- tachment of the erector spinae muscle, and the oblique part of the sacro-iliac ligament. Posterior Inferior Spine (17), for the sacro- tuberous (great sacro-scia tic) ligament. Great Sciatic (Sacro-iliac) Notch (16), below the last-named spine, transmits the great sciatic, superior gluteal, and pudic (pudendal) nerves, the pyriformis muscle, and the sciatic, pudic (pudendal) and gluteal vessels, also a nerve supplying the obturator externus muscle. Gluteal ridges (Curved Lines) (21) posterior, anterior, and inferior, on the outer surface of the bone, from the spaces between which arise the glutei muscles. Groove, above the acetabulum, for the reflected tendon of the rectus femoris muscle. The Ischium is the lowermost portion of the os coxae (innominate bone), and presents the following points, viz. B ody (superior ramus), forms two-fifths of the acetabulum, and the external margin of the obturator foramen; on it is a broad groove for the tendon of the obturator externus muscle. Its posterior margin assists in forming the great sciatic (sacro-sciatic) notch. Spine (14), for the gemellus superior, coccygeus, and levator ani muscles, and the lesser sacro-sciatic ligament. Lesser Sciatic (Sacro-sciatic} Notch (13) below the spine, transmits the 14 HUMAN ANATOMY obturator muscle, its nerve, and the pudic vessels and nerve as they re-enter the pelvis, having crossed the spine of the ischium. The sacro-sciatic notches are converted into foramina by the sacro- sciatic ligaments; the greater notch by the lesser ligament (sacro- spinous), the lesser notch by the greater ligament (sacro-tuberous). Tuberosity (12), the lowest and most prominent part, gives attach- ment to the greater sacro-sciatic (sacro-tuberous) ligament, and to several muscles. On it one rests when sitting. Horizontal Ramus (inferior ramus), bounds the obturator foramen inferiorly, articulates with the (descending) (inferior) ramus of the pubes, and gives attachment to the obturator membrane and several muscles. The Pubes. The pubic or pectineal bone forms the anterior portion of the innominate. It presents the following points, viz. Body, with its fellow forms the Symphysis, giving origin to several muscles and ligaments. Crest (9), on the upper part of the body, terminates externally in the spine. Spine, affords attachment to one end of inguinal (Poupart's) ligament. (Linea Ilio-pectinea), (pecten ossis pubis) in part, gives attachment to the conjoined tendon, Gimbernat's (lacunar) ligament, and the tri- angular ligament. Horizontal Ramus, forms part of the margin of the obturator fora- men, and of the acetabulum. Pectineal Eminence (5), gives attachment to the psoas parvus muscle. Muscles attached to the hip bone number 36, comprising those of the abdomen, thigh, perineum, floor of the pelvis, and rotators of the hip-joint. THE BONES OF THE HEAD THE FRONTAL BONES (OS FRONTALE), (i, Fig. 8) Points on its Frontal (Vertical) Portion, are as follows: Externally, An upper angle (6), Lateral angles (12), Frontal Eminences (tuberosities) , one on each side of the median line. Depression, marking the site of the frontal (metopic) suture before obliteration. Superciliary Arches (Ridges), behind which are the frontal sinuses. Supraorbital Notches or Foramina, in the supraorbital arches, at about their inner third, for the supraorbital vessels and nerves. Nasal Eminence (24), at lower end of the frontal depression. THE FRONTAL BONE 15 External Angular, (Lateral or Zygomatic) Processes (13), articulate with the malar (zygomatic) bones and form the anterior part of the temporal ridges. Internal (Medial) Angular Processes, articulate with the lacrimal bones. Nasal (Frontal) Spine and Notch, between the internal angular processes. Internally, Sagittal Sulcus or Groove, for superior longitudinal sinus and the falx cerebri. Frontal Crest, for attachment of the falx cerebri. Foramen Coecum, for a small vein to the longitudinal sinus. FIG. 8. Depressions and Elevations, for convolutions of the brain. Between the two tables of the vertical portion in the adult are the Frontal Sinuses, two spaces at the anterior inferior part of the bone, which are lined with mucous membrane, and open into the middle meatus of the nose. The Orbital Plates (Pars Orbitalis). Each plate presents the following points, Fossa, for the lacrimal gland, near the external angular process. Fovea Trochlearis, a depression at the nasal margin for the pulley of the superior oblique muscle. 1 6 HUMAN ANATOMY Ethmoidal Notch, having the following foramina on its margin. Anterior Ethmoidal Foramen, for the anterior ethmoidal vessels and the naso-ciliary branch of the ophthalmic nerve. Posterior Ethmoidal Foramen, for posterior ethmoidal vessels. Grooves, on the cranial surface, for branches of the anterior and middle meningeal arteries. Articulations, Development, and Muscles. Each half of the frontal bone articulates from its upper angle to its lateral angle, with the parietal, from lateral angle to zygomatic process, with the front part of the apex of the Great Wing of the sphenoid, zygomatic process, with the malar, posterior border of orbital plate, with Lesser Wing of the sphenoid, mar- gins of ethmoidal notch with the ethmoid, medial border of the orbital plate from behind forwards, with orbital plate of ethmoid, lacrimal, nasal process of maxilla, frontal spine, with the nasal. It is developed by 2 centres in membrane, i for each lateral half. The muscles attached to it are 3 pairs, the temporal, corrugator supercilii, and orbicularis palpe- brarum. THE PARIETAL BONES, (2, Fig. 8) General Characteristics. They are 2 quadrilateral bones situated at the superior and lateral regions of the cranium. Each has a frontal (anterior superior) angle (6), anterior border, sphenoidal (anterior inferior) angle (10), a lower border, a truncated mastoid (posterior inferior) angle (9), a posterior border, an occipital (posterior superior) angle (7), and an upper border. The articulations are, the superior border of each joins the other by the Sagittal Suture; the anterior border joins the frontal bone forming the Coronal Suture (6) ; the posterior border articulates with the occipital, forming the Lambdoid Suture (7); the inferior border from before backwards with the great wing of the sphenoid (5), squamous and mastoid portions of the temporal (4). Forming the lateral walls of the skull they are named parietal, from paries, a wall. Points on each Parietal Bone. Externally the bone is convex and pre- sents for examination, Temporal Ridge (13), continuous with the same on the frontal bone, bounded above by the superior temporal line, and below by the in- ferior temporal line. Parietal Eminence (tuberosity) , the point where ossification com- menced. Parietal Foramen, close to the upper border, transmits an emissary THE OCCIPITAL BONE IJ vein to the superior longitudinal (sagittal) sinus. Is not constant. Internally, the bone is concave, and marked by Depressions, for the Arachnoideal Granulations (Pacchionian bodies), and for the cerebral convolutions. Furrows, for branches of the middle meningeal artery. Groove, for the lateral (transverse) sinus, at the posterior inferior angle. Half-groove, along the upper border, for the superior longitudinal (sagittal) sinus of the dura mater. Development. Each parietal bone is developed from i centre in mem- brane. The only muscle attached to it is the temporal. FIG. 9. THE OS OCCIPITALE, (3, Fig. 8) is a symmetrical bone. Its border presents an upper angle, and on each side, lateral angle, jugular process, jugular notch, petrosal process along the edge of the basilar proc- ess, and the apex of the basilar process. General Features and Surfaces. It is trapezoidal in form, curved upon itself, and placed at the pos- terior and inferior region of the cranium. Externally its surface is convex and presents for exami- nation the following, viz. External Occipital Protuberance (5), and Crest (4), for the at- tachment of the ligamentum nuchae. Superior and Inferior Nuchal (Curved} Lines, extending outward on each side of the external occipital crest; in one skull in every six there is to be seen a supreme nuchal line above the others. Foramen Magnum (2), transmitting the medulla oblongata and its membranes, the vertebral arteries, and the recurrent portions of the spinal accessory nerves. Condyles (6), two in number, for articulation with the atlas. Tubercles, i on each condyle, for the check ligaments. l8 HUMAN ANATOMY Anterior Condylar Foramina (canalis hypoglossi), two for the hypoglossal nerves. Posterior Condylar Foramina (canalis condyloideus posterior) (3), two (often absent) for emissary veins. Jugular Processes (7), two, each partly bounding the foramen lacerum posterius basis cranii. Jugular Fossa (8), each forming part of the foramen lacerum posterius basis cranii. Internally, the surface is concave, showing Fosses, four for the cerebellar and posterior cerebral lobes. Internal Occipital Protuberance, where 6 cranial sinuses meet to form the torcular (wine-press) Herophili. Crucial Ridge, the vertical portion for the falx cerebri and falx cerebelli; the transverse portion for the tentorium cerebelli, having also a groove for the lateral (transverse) sinus. Groove, for the lateral (transverse) sinus, and the inferior petrosal sinus, along the postero-lateral border. Internal Openings, of the foramina described above. Basilar Process (i) of the Occipital lies in front of the foramen mag- num (2), articulates with the body of the sphenoid bone, smooth and grooved in the mid-line for the medulla oblongata and pons varolii, which lie upon it, grooved laterally by the inferior petrosal sinuses; rough in- feriorly for the attachment of muscles, and presenting the Pharyngeal Tubercle or Spine, for the attachment of the superior con- strictor muscle of the pharynx and its tendinous raphe. Articulations and Development. The occipital articulates as follows. The condyles articulate with atlas, apex of the basilar process with body of sphenoid, side of basilar process and apex of jugular process with petrous portion of temporal, from jugular to lateral angle with mastoid portion of temporal, from lateral angle to upper angle with parietal. It is developed by 4 centres, i each for the posterior part, the basilar process, and the 2 condyles; its ossification being completed about the 6th year of age. Muscles attached to the Occipital Bone. There are 12 muscles at- tached on each side to the following portions, viz. Superior Nuchal Line 3, the occipito-frontalis, trapezius, and sterno- cleido-mastoid muscles. Space between the nuchal lines 2, the complexus and splenius. Space below the inferior nuchal line 3, the obliquus capitis superior, rectus capitis posticus major and rectus capitis posticus minor. THE TEMPORAL BONE Basilar Process 3, the superior constrictor of the pharynx, rectus capitis anticus major and rectus capitis anticus minor. Jugular Process i, the rectus capitis lateralis. FIG. 10. THE TEMPORAL BONES (OSSA TEMPORALIA), (4, Fig. 8) Situation and Divisions. They are situated at the inferior lateral portions of the skull, and contain the organs of hearing. Each bone is formed by the union of three parts, namely, the Squamous, Petro-mastoid, and Tympanic. The Squamous Portion is a semicircular plate, smooth externally, and grooved internally for the middle meningeal artery, with depres- sions for the cerebral convolu- tions. Externally are seen the Zygomatic Process (d\ or Zygoma, arising by 3 roots, and extending forward to articulate with the malar bone. Zygomatic Tubercle (e), at the base of the process, for the external lateral ligament of the lower jaw. Anterior Articular Ridge (emi- nentia articularis), formed by the anterior root of the zygoma. Mandibular (Glenoid) Fossa (g), between the anterior and posterior articular ridge (middle root of the zygoma) for articulation with the condyle of the lower jaw, and is covered with cartilage. Glaserian Fissure, divides the squamous from the tympanic; it trans- mits the laxator tympani muscle, the tympanic artery, and lodges the processus gracilis of the malleus and the inferior process of the petrous. Opening of the Canal of Hugier, lies in the angle between the squamous and petrous portions of the bone; and transmits the chorda tympani nerve. Temporal Ridge (/), in part, here known as the suprameatal ridge. THE PETRO-MASTOID, is usually described as consisting of a mastoid portion and a petrous portion. 20 HUMAN ANATOMY FIG. ii. The Mastoid Portion. Its cerebellar surface is grooved for the lateral sinus (9); externally it presents the following, Mastoid Foramen (h) y the largest of several foramina, for a vein. Mastoid Process, at the tip, for the sterno-cleido-mastoid, splenius, and trachelo-mastoid muscles. Digastric Fossa (j}, for the posterior belly of the digastric muscle. Occipital Groove (8), for the occipital artery. The Mastoid Cells, in the interior of the mastoid process, open on the posterior wall of the middle ear, and are lined with mucous membrane. The Petrous Portion is very hard, pyramidal in form, contains the in- ternal ear, projects inward and forward, and presents a base, an apex, a cerebral surface, cerebellar surface, tympanic surface, and basilar surface; upper border, anterior border, pos- terior border; the tympanic bone is blended with the inferior border and conceals it. On the Base are seen, the Meatus Auditor ius Externus (i), the external opening of the ear. Auditory Process of the Tympanic, a bony ring for the external car- tilage of the ear. Apex lies internally, at the base of the skull, forming the outer boundary of the foramen lacerum medium, and contains the internal carotid canal. CEREBRAL (Anterior) Surface, presents from within outward Inner Opening of the Carotid Canal (n), for the internal carotid artery and plexus. Depression, for the Gasserian ganglion of the 5th pair of cranial nerves. Hiatus Canalis Facialis or Hiatus Fallopii, for the great petrosal nerve, branch of the middle meningeal artery. Foramen, for the small petrosal nerve. Eminence, over the superior semicircular canal of the ear. Depression, over the tympanum. Cerebellar (Posterior) Surface presents, Meatus Auditorius Internus (12), transmits the yth and 8th pairs of cranial nerves and the auditory artery, and lodges a process of dura THE TEMPORAL BONE 21 Opening of the Aqu&ductus Vestibuli (13), transmits to the vestibule a small artery and vein, and lodges a process of dura mater. Basilar (Inferior) surface, presents from within outward Rough Quadrilateral Surface (19), for the origin of the tensor tympani and levator palati muscles. Opening of the Carotid Canal, transmitting the internal carotid artery, and the carotid plexus of the sympathetic nerve. Aqu&ductus Cochlea, transmitting an artery and vein to the cochlea. Jugular Fossa, a depression for the sinus of the internal jugular vein, forming with the occipital bone the foramen lacerum posterius, which transmits that vein and the 8th pair of cranial nerves, etc. Foramen for Jacobson's Nerve (tympanic branch of the glossopharyn- geal), in the ridge between the jugular fossa and the carotid canal. Foramen for Arnold's Nerve (auricular branch of the pneumogastric), in the outer wall of the jugular fossa. Jugular Surface, for articulation with the jugular process of the occi- pital bone. The Tympanic Surface can be seen by looking in the external auditory canal, forms most of the osseous wall of the middle ear or tympanum. It presents the Promontory of the Cochlea, Fenestra Vestibuli, and Fenestra Cochlea. The Tympanic Bone forms most of the external auditory canal. Its under surface is slightly concave, forming a fossa for part of the parotid gland. It presents a sharp ridge which projects downwards, and forms the, Vaginal Process (1), ensheathing the root of the styloid process. Styloid Process (14), a long projection for the stylo-pharyngeus, stylo- hyoid, and stylo-glossus muscles; and the stylo-hyoid and stylo- mandibular ligaments, which are attached thereto. Stylo-mastoid Foramen (15), between the styloid and mastoid processes, for the exit of the facial nerve, and the entrance of the stylo-mastoid artery. Auricular Fissure, for the exit of the auricular branch of the vagus (Arnold's nerve). In the angle between the petrous and squamous portions, are seen the Septum Tuba, a lamina separating the following canals. Its inner end projects into the tympanum, and is called iheProcessus cochleariformis. Opening, of the canal for the tensor tympani muscle. Osseous Opening, of the Eustachian tube (n) inferiorly. The Anterior Border articulates partly with the alar spine of the sphenoid bone. 22 HUMAN ANATOMY The Posterior Border assists in forming the jugular foramen, and is grooved for the inferior petrosal sinus. The Superior Border separates the anterior fossa of the skull from the middle fossa; to it is attached the tentorium cerebelli, and it is grooved for the superior petrosal sinus (10), and in infants it presents afloccular fossa. Articulations and Development. The temporal articulates as follows, Anterior border of the petrous and squamous with the great wing of the sphenoid, upper border of the squamous and mastoid with the parietal, posterior border of the petro-mastoid with the occipital, apex of zygo- matic process with malar, and indirectly the glenoid fossa with the mandible. It is developed by 4 principal centres, one each for the squamous portion, styloid process, and tympanic, and one for the petro-mastoid portions. Its ossification is completed about the 2d or 3d year. Muscles attached to it. There are 14 muscles attached to the following- named portions. To the Squamous Portion 2, the temporal and masseter. Mastoid Portion 6, the occipito-frontalis, sterno-cleido-mastoid, splen- ius capitis, trachelo-mastoid, digastric, and retrahens aurem. Petrous Portion 3, the tensor tympani, levator veli palatini (leva tor palati) and stapedius. Styloid Process 3, the stylo-glossus, stylo-hyoid, and stylo-pharyngeus. THE SPHENOID BONE, (5, Fig. 8) Position and Form. Wedged in between the bones of the skull ante- riorly, it resembles a bat with out-stretched wings. It is named from the Greek word ) and external or lateral (0), arising from the respective condyles. extending upward along the shaft. Lateral or External Condyle (m),- -gives attachment to the external lateral ligament and the extensor and supinator group of muscles. Medial or Internal Condyle (), lower and more promi- nent lhan the other, gives attachment to the internal lateral ligament and the flexor and pronator group of muscles of the forearm. Capitellum (&), forms the outer or lateral part of the inferior articular surface; for articulation with the radius, it is on the front of the lateral condyle, above it is the radial fossa. Trochlcar Surface (1), articulates with the greater sigmoid cavity (incisura semilunaris) of the ulna; is a deep depression between two borders and extends from the anterior to the posterior surface of the bone. Coronoid Fossa, above the front of- the trochlear sur- face, receives the coronoid process of the ulna when the forearm is flexed. Olecranon Fossa (q), above the back part of the trochlea, receives the tip of the olecranon process, when the forearm is extended. THE FOREARM The skeleton of the forearm is -composed of 2 bones. The Ulna, or elbow-bone, is the principal bone of the forearm. It is larger and longer than the radius, forming the greater portion of the articulation with the humerus. It does not enter into the formation of the wrist-joint, being excluded therefrom by an interarticular nbro-cartilage. It presents for examination a shaft and two extremities, on which are the following points: Olecranon Process (4), at the upper extremity, forming the elbow. It is curved forward, its apex being received into the olecranon .fossa of the humerus when the forearm is extended. Its posterior surface gives insertion to the tendon of the triceps. In its function and structure it resembles the patella. THE ULNA AND RADIUS 49 Coronoid Process (5), below the olecranon projects forward forming the Tuberosity (3), its apex being received into the coronoid fossa of the humerus when the forearm is flexed. Its upper surface is concave for articulation with the humerus, its lower surface rough for the insertion of the brachialis anticus muscle. Its inner surface has a margin for the internal lateral ligament, a tubercle for the flexor sublimis digitoium, and a ridge for the pronator radii teres. Greater Sigmoid Cavity, or Incisura Semilunaris (2), lies between the processes, and is divided by a vertical ridge into two unequal parts. It articulates with the _trochlear surface of the humerus. * IG - 29 ' Lesser Sigmoid Cavity or Incisura Radialis (3), lies external to the coronoid process; is oval and con- cave, articulating with the head of the radius, and giving attachment to the orbicular ligament. Shaft (i), large and prismatic above, smaller and rounded below, has the Nutrient Foramen (6) on its anterior surface (i), and a prominent margin ex- ternally, to which is attached the interosseous membrane (7). It gives attachment to 9 of the 12 muscles of the forearm. Head (8), at the carpal end, articulates with the lesser sigmoid cavity of the radius, and the fibro- cartilage of the wrist-joint. Styloid Processes (9), projecting from the head in- ternally and posteriorly, its apex gives attachment to the ulno carpal ligament and a depression at its root to the fibro-cartilage of the joint. Groove, for the tendon of the extensor carpi ulnaris The Radius lies externally to the ulna when the fore- arm is in supination; it is prismatic in form with the base below where it articulates with the carpus. The bone is curved outward and is shorter than the ulna, by the length of the olecranon. It presents the follow- ing points from above downward, viz. Head (n), cylindrical and cup-shaped, articulating with the capitellum of the humerus, and the lesser sigmoid cavity or radial notch, of the ulna, and playing within the orbicular ligament. Neck (12), the constricted part below the head. Bicipital or Radial Tuberosity (13), rough behind lor the inser- O HUMAN ANATOMY tion of the biceps, and smooth in front where it is covered by a bursa. Shaft (10), prismoid in form, presents a sharp border internally for the attachment of the interosseous membrane; the Nutrient Foramen is on its anterior surface. It gives attachment to 8 of the 1 2 muscles of the forearm. Ridge (14), for the insertion of the pronator radii teres muscle. Ulnar Notch or Sigmoid Cavity, at the ulnar side of the carpal end (15), is shallow, and articulates with the head of the ulna. Articular Surface, is divided by a ridge into 2 facets for articulation with the semilunar and scaphoid bones of the carpus. Styloid Process (16), gives attachment by its apex to the radio-carpal ligament, and by its base to the supinator longus muscle. Grooves, on the posterior surface of the lower extremity, for the tendons of the 8 extensor muscles of the thumb, and those of the radial side of the wrist, and fingers. THE HAND The Bones of the Hand are divided into the carpus 8, the metacarpus 5, and the phalanges 14. Total, 27 bones. FIG. 30. Bones of the Carpus. The 8 bones are. placed in 2 rows, one row in front of the other, with 4 bones in each row, as follows, the right hand being in supination, nam- ing from without inward, viz. i5/ or Proximal Row, Scaphoid, or Navicular (s), Semilunar, or Os Lunatum (L), Cuneiform, or Os Tri- quetrum (c), Pisiform (p). 2d, or Distal Row, Trapezium, or Greater Multangular (T), Trapezoid or Lesser Multangular (T), Os magnum, or Os Capitatum (M), Unciform, or Os Hamatum (u). Articulations in the Carpus are 34, as follows: the number after each bone representing the number of its articulations, viz. Scaphoid; 5. Semilunar, 5. Cuneiform 3. Pisiform, i. Trapezium, 4. Trapezoid, 4. Os-magnum, 7. Unciform, 5. CARPAL AND METACARPAL BONES 5! Peculiarities of the Carpal Bones. The first three enter into the forma- tion of the wrist-joint; the pisiform does not, but is wholly without it, and may be considered a mere appendage of the carpus. When the hand is in pronation The Scaphoid (navicular), or boat-shaped bone (S) has a tuberosity on, its outer side, its largest facet is uppermost and articulates with the lower end of the radius (R). A transverse groove crosses its posterior surface and serves for the attachment of ligaments. The Semilunar Bone (os lunatum) (L) has a crescentic facet externally, and a convex facet superiorly, where it articulates with the radius. The Cuneiform Bone (os triquetrum) (C) is wedge-shaped, its convex surface above, articulating with the interarticular nbro-cartilage of the wrist (F). It has an oval facet anteriorly for articulation with the pisiform. The Pisiform Bone (os pisiforme) (P) is the smallest, and has but one facet, which lies posteriorly when the bone is in position. The Trapezium (os multangulum majus) (T) has a deep groove for the tendon of the flexor carpi radialis, and a saddle-shaped facet, infe- riorly for the base of the ist metacarpal. The Trapezoid (os multangulum minus) (T) is small and quadrilateral, bent on itself, with a saddle-shaped facet looking downward, for the base of the 2d metacarpal bone. The Os-magnum (os capitatum) (M) has a head looking upward, a neck, and a body; is the largest bone of the carpus, and has 3 facets on the inferior surface for articulation with the 2d, 3d, and 4th metacarpal bones. The Unciform Bone (os hamatum) (U) is wedge-shaped, with a con- cavity which lies to the outer side, and the unciform process, long and curved, projecting from its palmar surface. OSSA METACARPALIA The Metacarpus consists of the 5 metacarpal bones which are placed between the carpus and the phalanges. They are long bones, and each has a head, shaft and base. Their heads articulate with the respective phalanges. The Thumb or ist Metacarpal Bone (i), articulates with the trapezium, (greater multangular}, is shorter than the others by one-third, and its base has but i articular facet. The Index or id Metacarpal Bone (2), articulates with 3 bones of the carpus, the trapezium, (gr"ater multangular} trapezoid (lesser mult- 52 HUMAN ANATOMY angular) and os-magnum (capitate) ; its base is large, and has 4 articu- lar facets. The Middle or 3^ Metacar pal Bone (3), articulates with i bone of the carpus, the os-magnum (capitate} ; its base has a projecting process on the radial side, and 2 small facets on the opposite side. The Ring or tfh Metacar pal Bone (4), articulates with 2 bones of the carpus and with the adjacent metacarpal bones; its base is small and has 2 circular facets i on each side. The Little or $th Metacarpal Bone (5), articulates with i carpal bone, the unciform (hamate}, its base has i lateral articular facet. The Phalanges DigitorumManus or finger-bones, are 14 in number, 3 to each finger, and 2 to the thumb. They are long bones, and each has a base, a shaft, and a digital extremity. The Bases of the first row articu- late with the heads of the metacarpal bones. The Digital Extremities of the first and second rows have each 2 small lateral condyles, while in the terminal row they are rough, for the attachment of the sensitive pulp of the fingers. THE THIGH The Femur or thigh-bone, is the longest, largest and strongest bone in the body, and is nearly cylindrical in the greater part of its extent. In the vertical position of the skeleton it forms one side of a triangle, of which the base is the breadth of the pelvis, and the apex at the knee-joints. The base of this triangle is longest in the female, and consequently that sex is usually knock-kneed. The Head (5), articulates with the acetabulum, forms about two-fifths of a sphere, and has an oval depression (6) below its centre for the attach- ment of the ligamentum teres. Neck (7), connects the head with the shaft, is pyramidal and flattened; its obliquity varies with age, being less before puberty, about 120 to 125 degrees in the adult, and nearly horizontal to the shaft in old or debilitated subjects, the cancellous bone forming the neck is condensed centrally into a hard core known as the calcar femorale. Great Trochanter (8), a broad, rough, quadrilateral process directed outward and backward from the summit of the shaft to within three- fourths of an inch of the level of the head. On its outer surface the tendon of the gluteus maximus plays over a bursa. It gives insertion to the obturator internus, two gemelli, pyriformis, and gluteus mini- mus and medius muscles. THE FEMUR 53 Trochanteric or Digital Fossa (9), on the inner or medial surface of the great trochanter, gives insertion to the obturator externus muscle. Lesser Trochanter (10), at the inferior root of the neck posteriorly, is small and conical, and affords insertion to the tendon of the psoas magnus muscle, the tendon of the iliacus being inserted immediately below it. Inter-lrochanteric Line, at the base of the neck in front runs from one trochanter to the other, to it is attached the front part of the capsule of the hip-joint. Inter-trochanteric Ridge or Crest, at the base of the neck behind, to its middle portion is attached the quadratus femoris muscle. Shaft, is slightly curved forward, broad and cylindrical at each end, and narrow and triangular in the centre. Its nutrient foramen perforates its posterior surface below the centre, and is directed toward the hip. From its anterior surface arise the crureus or vastus- intermedius, and subcrureus or articularis genu muscles. Linea Aspera (i),- a crest lying along the central third of the shaft posteriorly; bifurcating above (2) towards each trochanter, also below (4) towards the 2 condyles. To its outer lip is attached the vastus externus, or lateralis, to its inner lip, the vastus internus, or medi- an's; and between them, the pectineus, ad- ductor brevis, and gluteus maximus above the short head of the biceps below, and the adductors longus and magnus along the greater portion of the space. Groove, crossing the internal condylar ridge, lodges the femoral artery. Popliteal Space, triangular and smooth, lying between the condylar ridges, for the popliteal artery. Lateral or External Condyle (n), broader and shorter than the internal, so as to form a horizontal articulation, the bone being inclined towards the median line. It gives attachment to the external lateral liga- ment, the popliteus, and the lateral head of the gastrocnemius. Medial or Internal Condyle (12), the longer by half an inch; it gives 54 HUMAN ANATOMY attachment to the internal lateral ligament and medial head of the gastrocnemius muscle. Intercondylar Notch (13), lodges the crucial, or cruciate, ligaments. In front the condyles are continuous with each other, forming a concave depression or trochlea for the patella. Lateral Epicondyle or Outer Tuberosity (14), on the external condyle, for the attachment of the external lateral ligament. Groove, below the outer tuberosity, for the tendon of the popliteus muscle, terminating in a depression whence the muscle takes its origin. Medial Epicondyle or Inner Tuberosity (15), on the internal condyle, for the attachment of the internal lateral ligament. Adductor Tubercle, above the inner tuberosity, for the insertion of the tendon of the adductor magnus muscle. Depression, behind the tubercle, for the tendon of the inner head of the gastrocnemius. THE PATELLA The Patella is flat and triangularly ovoidal with its apex directed downward. Subcutaneous Surface, convex, presenting longitudinal ridges and many nutrient foramina. Apex, very rough on its deep surface for attachment of ligamentum patellae. Articular surface presents a longitudinal articular ridge flanked by concave facets of which the lateral one is the larger. The medial facet often presents a "third facet" along its medial border. THE LEG The skeleton of the leg consists of 3 bones, the tibia, the fibula, and the patella, the latter being a large, sesamoid bone placed in front of the knee. The Tibia, or shin-bone, ranks next to the femur in respect to size and length. Its form is prismoidal, the upper extremity being much larger than the lower. It presents the following points: Head, expands into two tuberosities, internal (2) and external (3) which articulate with the condyles of the femur. In spite of their being receiving cavities, the tuberosities of the tibia are sometimes called condyles. Spine or Eminentia Intercondyloidea (4), projects vertically between the 2 articular surfaces, is bifid, affording attachment to the semilunar fibro-cartilages (semilunar menisci), and by depressions in front and behind its base to the crucial ligaments of the joint. Extensor Tuberosity (5), on the head, anteriorly between the tuber- osities, for the insertion of the ligamentum patellae. THE TIBIA AND FIBULA 55 Popliteal Notch or Posterior Intercondylar Fossa, posteriorly between the tuberosities, affords attachment to the posterior crucial ligament. Groove, on the inner tuberosity (2) posteriorly, for the insertion of the tendon of the semi-membranosus muscle. Facet, on the outer tuberosity (3) posteriorly and looking downward, for articulation with the head of the fibula. Soleus Ridge or Popliteal Line, obliquely across the upper part of the shaft posteriorly, affords attach- ment to the soleus. Nutrient Canal, the largest in the skeleton, opens just below the popliteal line, and is directed down- ward. Shaft (i), has 3 sharp ridges, i in front, the Crest (6) or Shin, and i on either side, to the external of which is attached the interosseous membrane. Lower Extremity (7), is smaller than the upper, grooved posteriorly for the tendon of the flexor longus pollicis; externally has a rough triangular depression for articulation with the fibula, and for the attachment of the inferior interosseous liga- ment. Its inferior surface is concave and smooth for articulation with the upper surface of the astrag- alus or talus. Internal Malleolus (8), projects downward from the internal side of the lower extremity. It articulates with the astragalus (talus) , is grooved posteriorly for the tendons of the tibialis posticus and flexor longus digitorum muscles, and affords attachment to the internal lateral ligament. The Fibula, is a long slender bone, placed nearly parallel with the tibia on the outer side of the leg. It is also called the Peroneus, or peroneal bone. Head (10), articulates with the external tuberosity (lateral condyle) of the tibia by a flat facet. Externally, it has a prominence for the attachment of the long external lateral ligament of the knee-joint. Styloid Process, or Apex Capituli, projects upward from the head posteriorly, and gives insertion to the tendon of the biceps muscle, and the short external lateral ligament of the knee-joint. Shaft (9), is twisted about ninety degrees on its long axis. It is ften very irregular and may present numerous longitudinal ridges 56 HUMAN ANATOMY which seem to give it many surfaces. However, it always presents certain characteristics which are constant. On the outer or lateral surface at its distal end, it presents a long smooth subcutaneous triangle. The ridge running from the apex of this triangle to the front of the head of the bone, is the anterior border or crest. The very first ridge internal (medial) to anterior border, no matter how near or distant it may be, is the interosseous border or crest. This border runs upward from the rough interosseous triangle to the inner (medial) side of the head. It may, for part of its length, join the anterior border. Running spirally upward from the groove for the peroneal tendons to the styloid process (apex capituli), is the posterior border (lateral crest}. The interval between the anterior border and the interosseous border, however narrow it may be, is the extensor surface (anterior part of the medial surface), from above downward it gives attachment to extensor digitorum communis, extensor hallucis longus, and peroneus tertius. The interval be- tween the anterior border and the posterior border (lateral crest) is the peroneal surface (lateral surface). The upper third of this surface gives attachment to the peroneus longus, the middle third, to the peroneus brevis; lower third is free. The entire interval be- tween the posterior border and the interosseous border is the flexor surface. Running from the back of the head downward and forward and finally joining the interosseous border, is the oblique ridge (not border) also called the medial crest. This oblique ridge divides the flexor surface into two portions; one which is close to the interosseous border (posterior portion of the medial surface) for the tibialis posticus; the remainder of the flexor surface which is distant from the interosseous ridge (posterior surface), from above downward gives attachment to the soleus and flexor hallucis longus. Nutrient Canal, opens about the centre of the shaft posteriorly, its canal running downwards. External Malleolus (n), is the lower extremity of the bone. It is larger and longer than the internal, articulates with the astragalus by a triangular facet, and is grooved posteriorly for the tendons of the peroneus longus and peroneus brevis muscles. Its edge affords attach- ment to the external lateral ligaments of the ankle-joint. THE FOOT The Bones of the Foot are divided into those of the tarsus 7, metatarsus 5, and phalanges 14. Total, 26 bones. THE BONES OF THE FOOT FIG. 33. Bones of the Tarsus are placed in 2 rows side by side, 2 bones in the external row, 5 in the internal, as follows, viz. Internally, Astragalus or Talus (5). Scaphoid or Navicular (8). 3 Cuneiform (10, n, 12). Externally, Os calcis (i), or Calcaneum. Cuboid (6). (The illustration, Fig. 33, shows the plantar surface of the skeleton of the foot.) Articulations in the Tarsus are 28 in num- ber, each bone articulating with 4 others, except the os calcis (calcaneus), which articu- lates with 2, and the external (third) cunei- form with 6 bones. Peculiarities of the Tarsal Bones. They may be divided transversely at the astrag- al o-scaphoid-calcaneo-cuboid articulation , the site of Chopart's operation. The Astragalus or Talus (5), has a rounded head, a convex surface on which is a broad articular facet, and on its inferior surface a deep groove between 2 articu- lar facets. Os Calcis or Calcaneus (i), is a large bone, having on its upper surface a deep groove for the interosseous ligament, between 2 articular surfaces; anteriorly a large irregular portion, the head; and poste- riorly an elongated portion forming the Heel (2). On its internal surface is a projection, the Sustentaculum Tali, which supports the internal articulating surface; below which process the bone is deeply grooved for the plantar vessels and nerves and the flexor tendons. To the os calcis are attached 8 muscles and the plantar fascia. Navicular or Scaphoid Bone (8), is boat-shaped, has 3 facets anteriorly for the cuneiform bones, a concave surface posteriorly for the astrag- alus, and a facet externally for the cuboid bone. A tubercle (9) is situated on the lower surface internally, for the insertion of the tibialis posticus muscle. Cuboid Bone (6), has 3 articular surfaces, and a groove inferiorly for the tendon of the peroneus longus. Internal or First Cuneiform Bone (10), the largest of the 3, has a tubercle EJAL.9, 58 HUMAN ANATOMY on its plantar surface for the insertion of parts of the tendons of the tibialis anticus and tibialis posticus muscles. Middle or Second Cuneiform Bone (n), is small and wedge-shaped with the narrow end downward. Its anterior surface is considerably behind the line of the tarso-metatarsal articulation, thus forming a recess into which the base of the second metatarsal bone fits. External or Third Cuneiform Bone (12), is also wedge-shaped, but longer than the middle one; and affords origin to i muscle, the flexor brevis pollicis. The Metatarsus consists of 5 metatarsal bones, which are long bones, having each a shaft and two extremities. Their bases articulate with the tarsal bones and with each other; their heads with the first row of phalanges. ist Metatarsal (i3), : is large but shorter than^the others, and forms the inner border of the foot, articulating with the internal cuneiform. The head is large and has two grooved facets on its plantar surface, over which glide 2 sesamoid bones (19). 2d Metatarsal (14), is the longest; its base has 3 facets for articulation with the 3 cuneiform bones in the recess formed by the shortness of the middle or second cuneiform. $d Metatarsal (15), has 2 facets on the inner side of its base, besides the facets for the internal cuneiform and the 4th metatarsal bone. 4th Metatarsal (16), articulates with the cuboid bone, and also with the internal or first cuneiform. ^th Metatarsal (17), articulates obliquely with the cuboid bone, and has a tubercular projection (18) on the outer surface of its base, which forms the guide in Key's operation. The Phalanges of the Foot number 14 as in the hand, the great toe having two (20, 21), the other toes three each. They are long bones, each having a base, a shaft, and an anterior extremity. They are convex above, concave below, and articulate by the bases of the first row with the bones of the metatarsus. The anterior extremities of the distal phalanges (21, 23) are expanded into surfaces for the support of the nails and pulp of the toes. THE ARTICULATIONS An Articulation or Joint is a connection between two bones of the skele- ton, and has entering into its formation the following-named structures bone, cartilage, fibro-cartilage, ligament and synovial membrane. ARTICULATIONS Articulations are divided into three classes, Synarthrosu, immovable joint; Amphiarthrosis, mixed articulation, having limited motion; and Diarthrosis, movable joint, having free motion. Synarthroses are subdivided into Sutura, formed by processes and in- dentations; Schindy'lesis, by a plate of bone entering into a fissure of an- other; and Gompho'sis, by a conical process into a socket. The Sutura are again subdivided into S. dentata, having tooth-like processes; S. serrata, with serrated edges; S. limbosa, having beveled margins and dentated proc- esses; S. squamosa, with thin beveled margins overlapping each other; S. harmonia, contiguous rough surfaces opposed to each other. The first 3 are also named Sutura Vera (true sutures) having indented borders; the last 2 Sutura Notha (false sutures) being formed by rough surfaces. Amphiarthroses are subdivided into Symphysis, connected by fibro- cartilage and not separated by synovial membrane; Syndesmosis, united by an interosseous ligament. Diarthroses are subdivided into Ginglymus, hinge-joint; Trochoides, pivot-joint, formed by a ring surrounding a pivot; Condyloid, by an ovoid head in an elliptical cavity; Reciprocal Reception, saddle-joint, by surfaces inversely convex and concave; Enarthrosis, ball-and-socket joint; Arthrodia, gliding joint. Examples of each of the above-named articulations, as follows: Synarthrosis, joints of the cranium and face, except the lower jaw. Sutura Dentata, the inter-parietal suture. Sutura Serrata, the inter-frontal suture. Sutura Limbosa, the fronto-parietal suture. Sutura Squamosa, the temporo-parietal suture. Sutura Harmonia, the intermaxillary suture. Schindylesis, rostrum of sphenoid with the vomer. Gomphosis, the teeth in their alveoli. Amphiarthrosis, the joints between the bodies of the vertebras (sym- physes), the inferior tibio-fibular articulation (syndesmosis). Diarthrosis, movable joint, as follows: -Ginglymus, inter-pharyngeal joints and the elbow-joint. Trochoides, superior radio-ulnar, atlanto-axial joint. (Articulatio Atlanto-epistrophica.) Condyloid, the wrist-joint. Reciprocal Reception, the carpo-metacarpal joint of the thumb. Enarthrosis, the hip- and shoulder-joints. Arthrodia, the carpal and tarsal articulations. OO HUMAN ANATOMY Varieties of Motion in Joints are 4 in number, viz. gliding, angular movement (including adduction, abduction, flexion and extension), circumduction and rotation. These movements are often more or less combined in the various joints. Structures entering into the formation of Joints are 5, viz., the articular lamella of bone, cartilage, fibro-cartilage, ligaments and synovial membrane. Articular Lamella of Bone differs from ordinary bone tissue in being more dense, containing no Haversian canals nor canaliculi, and having larger lacunae. Cartilage, a non-vascular structure, is divisible into temporary and permanent varieties. The first forms the original frame-work of the skeleton, and becomes ossified. Permanent cartilage is not prone to ossification, and is divided into 4 groups, Articular, covering the ends of bones in joints; Inter articular, between the bones in a joint; Costal, forming part of the skeleton; and Membraniform. According to its minute structure, cartilage is divided into Hyaline Cartilage, White Fibro-cartilage and Yellow or Elastic Fibro-cartilage. Fibro-cartilages, in joints and osseous grooves are of the white variety and may be arranged in 4 groups, the Inter articular (menisci) , separat- ing the bones of a joint; Connecting, binding bones together; Circum- ferential, deepening cavities; Stratiform, lining grooves. Ligaments are bands of white fibrous tissue, except the ligamenta subflava and the ligamentum nuchse, which consist entirely of yellow elastic tissue. Synovial Membranes secrete the synovia, a viscid, glairy fluid, and resemble the serous membranes in structure. They are Articular, lubricating joints; Bursal, forming closed sacs (bursae), interposed between surfaces which move upon each other; Vaginal, ensheathing tendons. ARTICULATIONS OF THE TRUNK The Temporo-mandibular Articulation is a ginglymo-arthrodial joint between the condyle of the lower jaw and the anterior part of the glenoid cavity of the temporal bone. It has 2 synovial membranes with an interarticular fibro-cartilage between them, and 4 ligaments, viz. External Lateral, from the tubercle of the zygoma to the outer side of the neck of the condyle of the lower jaw. Spheno-mandibular or Internal Lateral (d), from the alar spine of the ARTICULATIONS OF THE TRUNK 6l PIG. 34- sphenoid to the mandibular spine or lingula on the margin of the dental foramen. Stylo-mandibular (/), from the styloid process of the temporal bone tc the angle and posterior border of the ramus of the lower jaw. Capsular (c), from the edge of the glenoid cavity and the eminentia articularis to the neck of the condyle of the lower jaw. Its Nerves are derived from the auriculo- temporal and masseteric branches of the mandibular. Arteries from the temporal branch of the external carotid. The Vertebral Articulations are formed by the adjacent surfaces of the bodies of the vertebrae and their processes, and are con- nected by the following ligaments, etc. ' Anterior Common Ligament (i), along the fronts of the bodies. f\\ Posterior Common Ligament, along the backs of the bodies. 2J Ligamenta Subflava, connect the laminae of adjacent vertebrae. If I Capsular (4), surround the articular processes and are lined by synovial membrane. ^j Supra-spinous and nter-spinous, FIG. 35. connect the spinous processes. In the cervical region they form what is called the Ligamentum Nuchae. Inter-transverse (3), connect the transverse processes. Intervertebral Substance, in lentic- ular disks between the bodies of the vertebrae, from the axis to the sacrum. The Atlanto-axial Articulation is a double arthrodia or gliding joint between the articular processes and a pivot articulation between the atlas and the odontoid process. It has 6 ligaments and 4 synovial membranes, as follows: Anterior 2, and Posterior i, Atlanto-axial, -continuations of the anterior and posterior common spinal ligaments. Capsular 2, surrounding the articular surfaces, each lined by a synoviai membrane. 62 HUMAN ANATOMY PIG. 36. Transverse Ligament, divides the spinal foramen of the atlas into two portions, stretching across between the tubercles on the inner sides of the articular processes. It holds the odontoid process in place, having a synovial membrane interposed. Another synovial membrane is situated between the process and the anterior arch. The transverse ligament sends two vertical slips, one upward, the other downward, from which it is often named the Cruciform Ligament. The Occipito-atlantal Articulation is a double condyloid formed by the condyles of the occipital bone with the superior articular surfaces of the atlas, and has 6 ligaments, viz. Anterior Occipito-atlantal (a), from the anterior margin of the fora- men magnum to the anterior arch of the atlas. Posterior Occipito-atlantal, from the posterior margin of the foramen magnum to the posterior arch of the atlas. It is perforated by the vertebral and suboccipital nerves. Lateral 2, from the jugular processes of the occipital bone to the bases of the transverse processes of the atlas. Capsular 2 (d), around the articular surfaces, lined by synovial mem- brane. The Occipito-axial Articulation is formed by the occipital bone and the odontoid process of the axis, which do not articulate with each other strictly, but are connected with 4 ligaments, the Occipito-axial (i) (Membrana Tectoria), a continuation of the posterior common spinal ligament to the basilar process of the occipital bone. Lateral Occipito-odontoid (5) (Check Ligaments} 2, from the head of the odontoid process to the inner sides of the occipital condyles. Middle Odontoid (Ligamentum Suspensorium), from the anterior mar- gin of the foramen magnum to the odontoid apex. The Costo-vertebral Articulations are each a double arthrodia between the head of the rib and the bodies of 2 adjacent vertebrae, except in the ist, roth, nth, and i2th ribs, which are single, as they articulate with but i vertebra each. Their ligaments are 3, viz. Anterior Costo-central (2), or Stellate Ligament, consists of 3 bundles, which fasten the anterior part of the head of the rib to the inter- vertebral disk and the 2 adjacent bodies. ARTICULATIONS OF THE TRUNK 63 Intra-articiilar, in the interior of the joint, from the crest on the head of the rib to the intervertebral disk; on each side there is a separate synovial membrane. In the ist, loth, nth and i2th ribs it does not exist, hence there is but one synovial membrane. Capsular, surrounding the articular surfaces. The Costo-transverse Articulations are 10 arthrodial articulations between the tubercles of the first 10 ribs and the transverse processes of the vertebrae next below. Their ligaments are 4, viz. Anterior superior, Middle (interosseous), Posterior Costo-transverse and Capsular. The Chondro-sternal Articulations are 7 in number, i of which (the first) is a synarthrodial and 6 are arthrodial articulations, between the costal cartilages and the margin of the sternum. The first has no synovial membrane, the second only has an intra-articular ligament. Each has 4 ligaments, the Anterior and Posterior Chondro-sternal, a Capsular, and an Inter articular. The Chondro-xiphoid Ligaments connect the xiphoid ap- pendix to the cartilage of the 6th or 7th rib. The Costo-chondral and Interchondral Articulations connect the costal cartilages with the ribs and with each other respectively. With the ribs by a depression on the end of each rib, strengthened by the blending together of the periosteum and the perichondrium. The 6th, 7th and 8th, and sometimes the pth and loth costal cartilages articulate with each other by their borders and each has a Capsular and an Inter- chondral ligament, with 3 synovial membranes for the 3 articulations between the 6th and the pth cartilages. The Ligaments of the Sternum are an Anterior Sternal and a Posterior Sternal ligament, with a layer of cartilage between the manubrium and the gladiolus. The Sacro-vertebral Articulation is similar to the other vertebral articulations, but has 2 additional ligaments on each side, the Lumbo-sacral, from the transverse process of the 5th lumbar vertebra .to the base of the sacrum laterally and anteriorly. Ilio-lumbar, from the apex of the transverse processes of the 5th lumbar vertebra to the crest of the ilium in front of the sacro-iliac articulation. The Sacro-coccygeal Articulation is an amphiarthrodial joint, and has 4 ligaments, viz. Anterior Sacro-coccygeal. Posterior Sacro-coccygeal. 6 4 HUMAN ANATOMY Two Lateral Sacro-coccygeal. Fibro-cartilage, interposed in the joint. The Sacro-iliac Articulation is an amphiarthrodial joint, formed by the lateral surfaces of the sacrum and ilium. Its ligaments on each side are the Anterior Sacro-iliac. Posterior Sacro-iliac (8), which consists of a short transverse part (8) and a long part known as the Oblique Sacro-iliac. The Sacro-ischiatic Articulation is an amphiarthrosis between the sa- crum and the ischium. Its liga- ments convert the sacro-sciatic notches into foramina, the greater notch (5) being crossed by the lesser ligament, the lesser notch (6) by the greater ligament. These foramina are described on page 13 ante. Posterior or Great Sacro-sciatic Ligament (1. sacrotuberosum) (13), is the divorced tendon of the biceps femoris muscle, it ex- tends from the posterior inferior spine of the ilium and the pos- terior surface and margins of the sacrum and coccyx (2), to the inner margin of the tuber- csity (4) and the ascending ramus (14) of the ischium, the latter por- tion being known as the Falciform Ligament. Anterior or Lesser Sacro-sciatic Ligament (1. sacrospinosum) (15), from the margins of the sacrum and coccyx, into the spine of the ischium (16). The Pubic Articulation or Symphysis Pubis, is an amphiarthrodial joint formed by the junction of the two pubic bones with each other. It has an interpubic disk and 4 ligaments, the Anterior Pubic. Posterior Pubic. Superior Pubic Sub-pubic, forming a fibrous arch between the rami. ARTICULATIONS OF THE UPPER EXTREMITY The Sterno -clavicular Articulation is an arthrodial joint, formed by the sternal end of the clavicle with the sternum and the cartilage of the ist ARTICULATIONS OF UPPER EXTREMITY the FIG. 38. rib. It has an interarticular fibro-cartilage, 2 synovial membranes and 5 ligaments, the Anterior Sterno-clavicidar. Inter clavicular. Posterior Ster no-clavicular. Costo-clavicular or Rhomboid. Capsular, Formed by the anterior and posterior. The Acromio-clavicular Articulation is an arthrodial joint, formed by the outer extremity of the clavicle and the acromion process of the scapula. It frequently has an interarticular fibro-cartilage and 2 synovial mem- branes (usually but i is present). It has 3 ligaments, the Superior Acromio-clavicular(i}. Coraco-clavicular(2) j Trapezoid, externally. Inferior Acromio-clavicular. divided into I. Conoid, internally. Proper Ligaments of the Scapula are 2, the Coraco-acromial, and the Transverse, as follows: Coraco-acromial (3), completes the vault partially formed by coracoid and acromion processes over the head of the humerus. Transverse (4), from the base of the coracoid process to the margin of the suprascapular notch, converting it into a foramen for the suprascapular nerve. The Shoulder- joint, Articulatio Humeri, is an enarthrodial or ball-and-socket joint, formed by the head of the humerus and the glenoid cavity of the scapula. It has a Synovial Membrane which is reflected upon the tendons of the biceps, subscapularis, and infraspinatus muscles, and communi- cates with bursae beneath the 2 latter ten- dons. Its Arteries are derived from the anterior and posterior circumflex and the suprascapular; its Nerves from the circum- flex (n. axillaris) and the suprascapular. It has 3 ligaments, the Capsular (5), from the margin of the glenoid cavity to the anatomical neck of the humerus; has 3 open- ings for the reflexions of the synovial membrane over the tendons. Coraco-humeral (6), intimately united with the capsular, extends from the coracoid process to the greater tuberosity of the humerus. Glenoid, a fibre-cartilaginous ring, continuous above with the tendon of the long head of the biceps (7), and attached around the margin of 66 HUMAN ANATOMY FIG. 39 the glenoid cavity in order to deepen the articular surface and pad its edge. The Elbow-joint, Articulatio Cubiti, is a ginglymus or hinge articulation, formed by the lower end of the humerus with the greater sigmoid cavity of the ulna (2) and the head of the radius (3). Its Synovial Membrane is reflected over the ligaments, and includes the superior radio-ulnar articulation. Its Arteries are derived from the anastomotica magna, brachial, radial, ulnar, and interosseous recurrent, superior and inferior profunda arteries. Its Nerves are branches of the ulnar, the musculo- cutaneous and the median. It has 4 ligaments, the Anterior, from the internal condyle (7) and anterior surface of the humerus to the orbicular ligament of the radius and the coronoid process of the ulna. Posterior (6), from the posterior surface of the humerus to the olecranon process of the ulna. External Lateral (1. collaterale radiale) (4), from the external condyle of the humerus passing obliquely downward and backward behind the orbicular ligament and the head of the radius to be attached strongly to the ulna at a point opposite the attach- ment of the internal lateral ligament. Internal Lateral (1. collaterale ulnare), from the in- ternal condyle of the humerus (7) to the inner side of the juncture of the coronoid and olecranon proc- ,ess^of the ulna. The Radio-ulnar Articulations are 3 in number, as follows: SUPERIOR RADIO-ULNAR ARTICULATION is a trochoid or pivot-joint, formed by the head of the radius and the lesser sigmoid cavity of the ulna. Its synovial mem- brane is a continuation of that in the elbow-joint. It has only one ligament, the Orbicular Ligament (5), consists of two distinct portions, the orbicular and the capsular. The orbicular portion is very thick, forms four-fifths of a circle and surrounds the neck of the radius. It is attached to the margins of the lesser sigmoid cavity of the ulna, and to the external lateral ligament of the elbow-joint. The Capsular portion is loose and thin, its fibres run from the lower margin of the true orbicular ligament to the neck of the radius. MIDDLE RADIO-ULNAR ARTICULATION is formed by the shafts of the ARTICULATIONS OF UPPER EXTREMITY 67 radius and ulna, which do not touch each other, but are connected by 2 ligaments, as follows: Oblique Ligament, from the tubercle at the base of the coronoid process of the ulna to the shaft of the radius. Its fibres run from the ulna obliquely downward to the radius, whereas the fibers of the inter- osseous membrane run from the radius downwards to the ulna. Interosseous Membrane (9), -obliquely downward from the interosseous ridge on the radius to that on the ulna. Through the interval between its upper border and the oblique ligament, the posterior interosseous vessels pass. INFERIOR RADIO-ULNAR ARTICULATION is a pivot-joint, formed by the head of the ulna and the sigmoid cavity of the radius. Its Synovial Membrane (membrana sacciformis) is very loose, and sometimes com- municates with that of the wrist-joint through an opening in the triangular fibro-cartilage which separates the head of the ulna from the wrist-joint. It is a capsule but is often considered as consisting of two portions which are then called, Anterior Radio-ulnar. Posterior Radio-ulnar. ++- The Radio-carpal Articulation, or Wrist-joint, is a condyloid articula- tion formed by the lower end of the radius and the triangular fibro-cartilage with the scaphoid (os naviculare), semilunar (os lunatum), and cuneiform, (os triquetrum) bones of the carpus. Its Arteries are the anterior and pos- terior carpal from both the radial and ulnar, the anterior and posterior interosseous and ascending branches from the deep palmar arch. Its Nerves are derived from the ulnar and posterior interosseous. It is lined by a synovial membrane, and is connected by a capsule, which is divided into the following-named 4 ligaments, the External Lateral (radio-carpal). Anterior Ligament. Internal Lateral (ulno-carpal). Posterior Ligament. The Carpal Articulations are in 3 sets, between the bones of the first row, between the bones of the second row, between the 2 rows of bones with each other. The scaphoid, semilunar, and cuneiform bones are connected together by Dorsal, Palmar (volar), and 2 Inter osseous Ligaments. The pisiform bone has a separate capsular ligament and synovial membrane and 2 Palmar Ligaments connecting it with the unciform and the 5th metacarpal. The 4 bones of the second row are connected together by Dorsal, Palmar and 3 Interosseous Ligaments. 68 HUMAN ANATOMY The two rows of bones are united to each other by Dorsal, Palmar, and 2 Lateral Ligaments, the last named being continuous with the lateral ligaments of the wrist-joint. The Carpo-metacarpal Articulations. That of the thumb with the trapezium is a joint of reciprocal reception, and has a Capsular Ligament and a separate synovial membrane. The 4 inner metacarpal bones form 4 arthrodial joints with the adjacent carpal bones by 6 Dorsal, 8 Palmar, and 2 Interosseous Ligaments, irregularly disposed. The Synovial Membranes of the Wrist are 5 in number, and are situated as follows: The First, or Membrana Sacciformis, between the head of the ulna, the sigmoid cavity of the radius, and the triangular interarticular fibro-cartilage. The Second, between the lower end of the radius, the triangular fibro- cartilage, and the scaphoid, semilunar, and cuneiform bones of the carpus. The Third, between all the carpal bones except the pisiform and between the bases of the inner 4 metacarpal bones; but it extends only halfway into the 2 intervals between the 3 proximal bones of the carpus. The Fourth, between the trapezium and the metacarpal bone of the thumb. The Fifth, between the cuneiform and pisiform bones. The Metacarpo-metacarpal Articulations. The 4 inner metacarpal bones are connected together at their bases by Dorsal, Palmar, and Inter, osseous Ligaments, and at their digital extremities by the Transverse Ligament, a narrow fibrous band which crosses them anteriorly. Remaining Articulations of the Hand. The metacarpo-phalangeal are condyloid joints formed by the rounded heads of the metacarpal bones and the shallow cavities in the extremities of the first phalanges. The phalangeal articulations are ginglymus joints. Both sets have for each joint an Anterior and 2 Lateral Ligaments, the former being lined each with a synovial membrane. There are no posterior ligaments to these articula- tions, the extensor tendons of the hand supplying their places. ARTICULATIONS OF THE LOWER EXTREMITY The Hip-joint is a true enarthrodial or ball-and-socket articulation, formed by the head of the femur with the acetabulum of the os innom- inatum. Its Synovial Membrane is extensive, investing most of the ARTICULATIONS OF LOWER EXTREMITY 69 head and neck of the femur, the capsular, cotyloid and teres ligaments, and the cavity of the acetabulum. Its Arteries are derived from the obturator, sciatic, internal circumflex, and gluteal. Its Nerves are branches from the sacral plexus, great sciatic, obturator, and accessory obturator. It has 5 ligaments as follows: the Capsular, from the margin of the acetabulum and the transverse liga- ment into the base of the neck of the femur above, the anterior inter- trochanteric line in front, and to the middle of the neck of the bone, behind. Superadded to and strengthening it are 3 auxiliary bands, the fibres of which form part of the capsule, the ilio-femoral (de- scribed below), the ischio-femoral and the pectineo- femoral bands. Ilio-femoral or Y -ligament, from the anterior inferior spine of the ilium, into the anterior inter-trochanteric line by two fasciculi. It is a dissected portion of the capsular ligament which is very strong anteriorly. Ligamentum Teres, from a depression on the head of the femur into the margins of the cotyloid notch of the acetabulum and into the trans- verse ligament, by two fasciculi. Cotyloid, a fibro-cartilaginous band surrounding the margin of the acetabulum in order to deepen its cavity and pad its edge. Transverse, that part of the cotyloid ligament which crosses over the cotyloid notch converting it into a foramen. The Knee-joint is a complicated articulation, formed by the condyles of the femur with the head of the tibia and the patella in front. It consists of 3 articulations in one; those between the condyles of the femur and the tuberositis of the tibia are condylar joints, while that between the patella and the femur is partly trochlear. Its Synomal Membrane is the largest in the body, being reflected for 2 or 3 inches over the anterior surface of the femur, where it is supported by the subcrureus muscle; also over its con- dyles, the patella, semilunar cartilages, crucial ligaments, and the head of the tibia; and it is prolonged through an opening in the capsular ligament beneath the tendon of the popliteus. Its Arteries are derived from the anastomotica magna, the articular branches of the popliteal, the recurrent branches of the anterior tibial and the external circumflex of the profunda. Its Nerves are derived from the obturator, anterior crural, external and internal popliteal. It has 14 ligaments, of which 6 are external and 8 internal, as follows: Anterior, or Ligamentum Patella, is the central portion of the common tendon of the extensor muscles of the thigh, continued from the patella to the tubercle of the tibia (9, Fig. 41). HUMAN ANATOMY Posterior, the oblique portion of which is often called Ligamentum Winslowii (i), from the upper margin of the intercondyloid notch of the femur to the posterior margin of the head of the tibia, being p IG . 4 o. partly derived from the tendon of the semi- membranosus muscle (2): Internal Lateral (1. collateral tibiale) (5), from the internal condyle of the femur to the inner tuberosity of the tibia and the internal semi- lunar cartilage. External Lateral 2, from the external condyle of the femur to the head of the fibula. These ligaments are a Long (1. collaterale fibulare) (6) is a divorced portion of the peroneus longus muscle. The short external lateral ligament (1. laterale externum breve seu posticum) (7) is often wanting, when present, it is behind the long external lateral and separated from it by the tendon of the biceps. Capsular, is a thin but very strong membrane, which fills in the intervals left between the preceding ligaments and is inseparably connected with them. The Internal Ligaments are as follows: Anterior Crucial (2), from the depression in front of the spine of the tibia to the inner side of the outer condyle of the femur. Posterior Crucial (3), from the depression behind the spine of the tibia and the popliteal notch, to the outer side of the inner condyle of the femur. [To remember the positions and insertions of these crucial ligaments, let the student cross his index fingers over each knee in succession; when over the right knee placing the right finger in front, when over the left knee the left finger in front. The positions of the fingers will in each case correspond with those of the respective crucial ligaments.] Semilunar Fibro-cartilages (menisci) 2, external (7) and internal (6), are situated between the articular surfaces, and attached to the depressions in front and behind the spine of the tibia. The external one forms nearly an entire circle and gives off posteriorly a strong PIG. 41. ARTICULATIONS OF LOWER EXTREMITY 71 fasciculus, the ligament of Wrisberg, which is inserted into the inner condyle of the femur. Transverse (4), is a connecting slip between the semilunar fibro-carti- lages anteriorly. Coronary or Coronal (7), are short bands connecting the outer margins of the fibro-cartilages with the margin of the head of the tibia. Ligamenium Mucosum (plica synovialis patellaris) , is a triangular fold of the synovial membrane which at the lower border of the patella is given off to the intercondylar notch of the femur. Ligamenta Alaria (plicae alares), are two fringe-like folds on the sides of the ligamentum mucosum, and are attached to the semilunar cartilages. Bursa, in the vicinity of this joint are 1 2 in number; 3 in front, 4 on the outer side, and 5 on the inner side. Some of these are expansions from others, some often communicate with the joint, and some are only occasionally present. That between the patella and the skin is the one implicated in the affection called "house-maid's knee." The Tibio-fibular Articulations are 3 in number, as follows, viz. SUPERIOR TIBIO-FIBULAR ARTICULATION, in an arthrodial joint, formed by the contiguous surfaces of the bones. It has a Synovial Membrane which is sometimes continuous with that of the knee-joint, and 3 liga- ments, the Capsular, a membranous bag surrounding the joint and much thicker in front than behind. Anterior and Posterior Superior Tibio-fibular (10), which connect the head of the fibula with the outer tuberosity of the tibia. MIDDLE TIBIO-FIBULAR ARTICULATION. The shafts of these bones do not touch each other, but are connected by an Interosseous Membrane extending between their contiguous borders, and perforated, above for the anterior tibial vessels, below for the anterior peroneal vessels. INFERIOR TIBIO-FIBULAR ARTICULATION, is an amphiarthrodial joint, of the subdivision syndesmosis, and is formed by the contiguous rough surfaces on the lower ends of these bones. Its Synovial Membrane is derived from that of the ankle-joint, and it has 4 ligaments, the Inferior Interosseous, continuous with the interosseous membrane. Anterior and Posterior Inferior Tibio-fibular, from the margins of the ex- ternal malleous to the front and back of the tibia. Transverse, posteriorly between the 2 malleoli. The Ankle-joint is a ginglymus or hinge-joint articulation, formed by the lower ends of the tibia and fibula and their malleoli, with the astragalus. 72 HUMAN ANATOMY Its Synovial Membrane is prolonged upward between the tibia and fibula for a short distance. Its Arteries are derived from the malleolar branches of the anterior tibial and peroneal arteries; and its Nerves from the anterior and posterior tibial nerves. It has 4 ligaments; the Anterior, connecting the anterior margins of the tibia and astragalus or talus. Posterior, a very thin band of transverse fibres, connecting the posterior margins of the tibia and astragalus. Internal Lateral or Deltoid Ligament (1. calcaneotibiale) , from the internal malleolus to the 3 adjacent tarsal bones. External Lateral, by anterior (1. talofibulare anterius), posterior (1. talofibulare posterius) and middle (1. calcaneofibulare) fasciculi, from the external malleolus to the astragalus and os calcis. The Tarsal Articulations are connected by the following-named liga- ments, viz., the Calcaneo-astragaloid 3, external, internal and posterior, connecting the os calcis with the astragalus. Calcaneo-cuboid 4, superior, internal, long and short, connecting the os calcis with the cuboid. Calcaneo-navicular 2, superior and inferior, connecting the os calcis with the scaphoid or navicular bone. Astragalo-navicular, superior, connecting the astragalus with the scaphoid or navicular bone. Dorsal and Plantar Ligaments, connecting the scaphoid with the three cuneiform and with the cuboid, the three cuneiform with each other, and the external cuneiform with the cuboid. Interosseous Ligaments, connecting the os calcis with the astragalus, the scaphoid with the cuboid, the cuneiform bones with each other, and the external cuneiform with the cuboid. Nerves. All the joints of the tarsus are supplied by the anterior tibial nerve. The Tarso-metatarsal Articulations are 5 arthrodial joints formed by the bases of the metatarsal bones with the adjacent bones of the tarsus, the 2d metatarsal bone articulating with all 3 cuneiform in the recess formed by the shortness of the second cuneiform. They are united by Dorsal, Plantar, and 3 Interosseous Ligaments. The 2d metatarsal bone has 3 dorsal ligaments, i from each cuneiform bone. The interosseous ligaments pass from the 2d and 3d metatarsal bones to the internal and external cuneiform. MUSCLES AND FASCIA 73 Synovial Membranes of the Tarsus and Metatarsus are 6 in number, and are situated as follows, viz. First, between the os calcis and the astra'galus, behind the interosseous ligament. Second, between the same bones in front of the interosseous ligament, also between the astragalus and the scaphoid. Third, between the os calcis and the cuboid. Fourth, between the scaphoid and the 3 cuneiform bones, running back- ward between the scaphoid and the cuboid, forward between the cuneiform bones, between the external cuneiform and the cuboid, between the middle and external cuneiform and the bases of the 2d and 3d metatarsal, passing also between the bases of these bones and the 4th metatarsal. Fifth, between the internal cuneiform and the base of the ist metatarsal bone. Sixth, between the cuboid and the 4th and 5th metatarsal bones, also running forward between their bases. The Metatarso -metatarsal Articulations. The metatarsal bones are connected together, except the first, at their bases by Dorsal, Plantar, and Interosseous Ligaments. The base of the first metatarsal is not connected with the base of the second by any ligaments, resembling the thumb in this respect. Remaining Articulations of the Foot. The metatarso-phalangeal and the phalangeal articulations are similar to those in the hand, each having a Plantar and 2 Lateral Ligaments. The extensor tendons supply the places of the posterior ligaments. THE MUSCLES AND FASCLE The Muscles are the active organs of locomotion, formed of bundles ol reddish fibres endowed with the property of shortening themselves upon irritation, which is called muscular contractility, and chemically consisting of 75 per cent, of water, 20 of proteids, 2 of fat, i of nitrogenous extractives and carbohydrates, and 2 per cent, of salts, mainly potassium phosphate and carbonate. The Muscles are divided into 2 great classes, Voluntary, Striped, or Muscles of animal life, comprise those which are under the control of the will. Involuntary, Unstriped, or Muscles of organic life, are those which are not under the control of the will. Voluntary Muscular Fibre consists of fasciculi enclosed in a delicate web, the perimysium, connected together by a delicate connective tissue, 74 HUMAN ANATOMY the endomysium, aggregated into muscular fibres, from ^ O o inch to ^oo inch in diameter, which are enclosed in tubular sheaths, the sarcolemma, and are marked by fine stria *passing around them transversely or some- what obliquely. The fasciculi are formed of longitudinal fibrillae or sarcostyles, made up of successive portions called sarcomeres, each of which consists of a central dark part the sarcous element, and a clear layer which is most visible when the fibre is extended (Schafer). Involuntary Muscular Fibre is made up of spindle-shaped cells, the contractile fibre-cells, averaging ^50 inch long and ^40 oo inch broad, col- lected into bundles and held together by a cement-like substance. These are aggregated into larger bundles or flattened bands, bound together by ordinary connective tissue. Involuntary muscular fibres are found in the walls of the alimentary canal, in the posterior wall of the trachea, in the bronchi, the ducts of certain glands, in the ureters, bladder, urethra, genitalia of both sexes, walls of all arteries and most veins and lymphatics, in the iris and ciliary muscle, and in the skin. *j 7 Tendons and Aponeuroses. Tendons are white, glistening cords or ' bands formed of white fibrous tissue almost entirely, have few vessels and no nerves in the smaller ones. They serve to connect the muscles with the structures on which they act. Aponeuroses are fibrous membranes, of similar structure and appearance, and serve the same purpose. Fasciae are laminae of variable thickness which invest (fascia, a bandage) the softer structures. The superficial fascia or subcutaneous tela consists of two layers, a superficial fatty layer (panniculus adiposus) which is closely adherent to the true skin, covering over almost the entire body. Except on the eyelids, penis, and scrotum, it contains much fat. The deep layer of the superficial fascia is a fibro-muscular layer (panniculus carnosus) it envelops the entire trunk. On the sides of the neck and upper part of the chest it is muscular and is there called the platysma, it is also muscular in the scrotum where it is called the dartos. The deep fascia is of aponeurotic structure, dense, inelastic, and fibrous, ensheathing the muscles and affording some of them attachment, it also forms the sheaths of the vessels and nerves, and binding down the whole into a shapely mass. Muscles are attached to the periosteum and perichondrium of bone and cartilage, to the subcutaneous areolar tissue, and to ligaments. In the latter case only are their tendons in direct contact with the tissue on which they are to act. Double-bellied Muscles are 4 in number, the occipito-frontalis, digastric, omo-hyoid, and the diaphragm. MUSCLES OF THE HEAD 75 MUSCLES OF THE HEAD CRANIAL REGION Occipito-frontalis (a) , arises/row the external two-thirds of the superior curved line of the occipital bone and the mastoid process of the temporal; also from the pyramidalis nasi, corrugator supercilii, and orbicularis pal- pebrarum fibres; and is inserted into an aponeurosis or "galea capitis," which covers the vertex of the skull. Action, chiefly as a muscle of facial expression. Nerves, the frontal portion (m. frontalis) by the facial nerve, the occipital portion (m. occipitalis) by the posterior auricular branch of the facial. AURICULAR REGION I Auricularis anterior, or Attrahens Auriculam, from the lateral cranial aponeurosis: into the helix of the ear anteriorly. Action, to draw the pinna forward. Nerve, temporal branch of the facial. ? Auricularis superior, or Attollens Auriculam, -from the occipito-frontalis aponeurosis: into thejginna of the ear superiorly. Action, to raise the pinna. Nerve, temporal branch of the facial. Auricularis posterior, or Retrahens Auriculam, from the mastoid process of the temporal bone: into the concha. Action, to retract the pinna. Nerve, posterior auricular branch of the facial. PALPEBRAL REGION Orbicularis Palpebrarum (m. orbicularis oculi), from the internal angular process of the irontal bone, the nasal process of the superior maxillary, and the borders of the tendo oculi; into the skin of the eyelids, forehead, temple, and cheek, blending with the occipito-frontalis and the corrugator supercilii. Action, to close the eyelids. Nerve, facial; perhaps also the 3d nerve. Corrugator Supercilii, /row the inner end of the superciliary ridge of the frontal bone: into the orbicularis palpebrarum. Action, to draw eye- brow downward and inward. Nerve, facial; perhaps by the 3d nerve. Tensor Tarsi (is classed by some as a portion (pars lacrimalis) of the orbicularis) it arises, from the crest of the lacrimal bone into the tarsal cartilages by two slips. Action, to compress the puncta lacri- malia against the globe of the eye and to compress the lacrimal sac. Nerve, facial; perhaps also the 3d nerve. 70 HUMAN ANATOMY ORBITAL REGION Levator Palpebrae Superioris (9), from the lesser wing of the sphenoid: into the upper tarsal cartilage. Action, to lift the upper lid. Nerve, 3d cranial, or motor oculi. The fibrous ring (annulus tendineus communis) from which arise the recti oculi muscles, is divisible into an upper common tendon and a lower common tendon. Rectus Superior (5), from the superior common tendon (ligament of Lock wood) : into the sclerotic coat. Action, to rotate the eyeball upward. Nerve, 3d cranial. Rectus Inferior (4), from the inferior common tendon (ligament of Zinn) : c. into the sclerotic coat. Ac- f Itj. 42. lion, to rotate the eyeball downward. Nerve, 3d cranial. Rectus Interims (3), from the inferior common ten- don (ligament of Zinn) : into the sclerotic coat. Action, to rotate the eyeball in- ward. Nerve, 3d cranial. Rectus Externus (or lateralis) (2), by 2 heads, the upper from the superior common tendon (ligament of Lock- wood), the lower from the inferior common tendon (ligament of Zinn) and a bony process at lower margin of the sphenoidal fissure: into the scle- rotic coat. Action, to rotate the eyeball outward. Nerve, 6th cranial, or abducens. Between the 2 heads of the external rectus pass the 3d, nasal branch of the 5th, and 6th cranial nerves, and the ophthalmic vein. Obliquus Oculi Superior (6), from about a line above the inner margin of the optic foramen, its tendon passing through a pulley (7) near the internal angular process of the frontal bone and thence beneath the rectus superior: into the sclerotic coat at right angles to the insertion of the rectus superior. Action, to rotate the eyeball on its antero-posterior axis. Nerve, 4th cranial, or patheticus. MUSCLES OF THE HEAD 77 FIG. 43. Obliquus Oculi Inferior (S),from the orbital plate of the maxilla: into the sclerotic coat below the insertion of the external rectus and at right angles thereto. Action, to rotate the eye on its antero-posterior axis. Nerve, 30! cranial. NASAL REGION Pyramidalis Nasi (m. procerus) (c), from the occipito-frontalis: into the compressor naris. Action, to depress the eyebrow. Nerve, facial. Levator Labii Superioris Alaeque Nasi (caput angulare of the m. quadratus labii superioris) (e), from the nasal process of the maxilla bone: into the cartilage of the ala of the nose and into the upper lip. Action, to elevate the upper lip, and dilate the nostril. Nerve, facial. Dilator Naris Anterior, from the car- tilage of the ala: into the border of its integument. Action, to dilate the nostril. Nerve, facial. Dilator Naris Posterior, from the nasal notch of the maxilla and the sesamoid cartilages: into the integu- ment a,t the margin of the nostril. Action, to dilate the nostril. Nerve, facial. Compressor Nasi (m. nasalis) ( popliteal (n. tibialis). Flexor Longus Hallucis (m. flexor hallucis longus) (9), from the lower two-thirds of the flexor surface of the shaft of the fibula, the interosseous membrane, fascia, and intermuscular septum, its tendon passing through grooves in the tibia, astragalus and os calcis: into the base of the last phalanx of the great toe. Action, to flex the great toe. Nerve, posterior tibial (n. tibialis). Flexor Longus Digitorum (m. flexor digitorum longus) (7) from the shaft of the tibia posteriorly and below the oblique line; its tendon passing behind the inner I? malleolus in a groove (13) with the tibialis posticus (m. tibialis posterior): into the bases of the last phalanges of the lesser toes by 4 tendons which per- forate the tendons of the flexor brevis digitorum. Action, to flex the phalanges and extend the foot. I Nerve, posterior tibial (n. tibialis). Tibialis Posti'cus (m. tibialis posterior) (8), by two processes between which pass the anterior tibial ves- sels, from the upper half of shaft of the tibia poste- riorly, the upper two-thirds of the flexor surface of the shaft of the fibula internally, the interosseous mem- brane, deep fascia, and intermuscular septa; its ten- don passes behind the inner malleolus in a groove (13) with the long flexor: into the tuberosity of the scaphoid and internal cuneiform bones. Action, to extend the tarsus and invert the foot. Nerve, posterior tibial (n. tibialis). MUSCLES OF THE LEG 115 Peroneus Longus (m. peronaeus longus) (io),from the head of the fibula, and the upper two-thirds of the peroneal surface of its shaft externally, the deep fascia and intermuscular septa, passes behind the outer malleo- lus in a groove with the peroneus brevis, through a groove in the cuboid bone: into the outer side of the base of the metatarsal bone of the great toe and the internal cuneiform bone, having crossed the sole of the foot obliquely. Action, to extend and evert the foot and flex the heel. Nerve, musculo-cutaneous branch of the external popliteal (n. peronaei superficialis). /Peroneus Brevis (m. peronaeus brevis) (n), from the middle third of the peroneal surface of the shaft of the fibula externally and the inter- muscular septa: its tendon passes behind the external malleolus in a groove with the long peroneal, into the dorsum of the base of the 5th metatarsal bone. Action, to extend the foot. Nerve, musculo-cutane- ous branch of the external popliteal (n. peronaei superficialis). FASCIA OF THE FOOT ANTERIOR ANNULAR LIGAMENT (11. transversum et cruciatum cruris) (12 Fig. 58), consists of vertical and horizontal portions, is attached to the lower ends of the fibula and tibia, the os calcis and the plantar fascia. It contains sheaths lined by synovial membranes for the ten- dons of the extensor muscles (that of the extensor proprius hallucis passing beneath it), as also the anterior tibial vessels and nerve. INTERNAL ANNULAR LIGAMENT (1. laciniatum), from the inner malleolus to the os calcis (calcaneus), converting 4 bony grooves into canals lined by synovial membranes for the flexor tendons and the posterior tibial vessels and nerves. EXTERNAL ANNULAR LIGAMENT (1. peronaei retinaculum superior), front the outer malleolus to the os calcis, binding down the peronei tendons in one synovial sac. i / PLANTAR FASCIA, the densest in the body, divided into a central and two lateral portions, and attached to the inner tuberosity of the os calcis, f divides into 5 processes, i for each toe, and several intermuscular septa. ^ DORSAL FASCIA, is a thin membranous layer continuous above with the anterior margin of the annular ligament, and becoming gradually lost opposite the heads of the metatarsal bones, and on each side blending with the plantar fascia. It forms a sheath for the tendons on the dorsum of the foot. MUSCLES or THE FOOT Extensor Brevis Digitorum (m. extensor digitorum brevis) (n Fig. 58), the only muscle on the dorsum of the foot, arises from the os calcis Il6 HUMAN ANATOMY externally, the calcaneo-astragaloid and the anterior annular ligaments (1. cruciatum cruris): by 4 tendons, i into the proximal phalanx of the great toe, and the others into the outer sides of the long extensor tendons of the 2d, 3d, and 4th toes. A ction, to extend the toes. Nerve, anterior tibial (deep peroneal). Muscles on the sole of the foot number 19; arranged by layers: ist Layer 3d Layer Abductor Hallucis. Flexor Brevis Hallucis (m. flexor hallu- cis brevis). Flexor Brevis Digitorum (m. Adductor Obliquus Hallucis (caput obli- flexor digitorum brevis). quum m. adductoris hallucis). Abductor Minimi Digiti (m. Flexcr Brevis Minimi Digiti (m. flexor abductor digiti quinti). digiti quinti brevis). 2d Layer Adductor Transfer sus Hallucis (caput Flexor Accessorius (m. quad- transversum m. adductoris hallucis). ratus plantae). 4th Layer Lumbricales, 4. Interossei (4 Dorsal, 3 Plantar). Abductor Hallucis,*- from the inner tubercle of the os calcis (calcaneus), the internal annular ligament (1. laciniatum), plantar fascia, and inter- muscular septum: into the inner side of the base of the ist phalanx of the great toe. Action, to abduct the great toe. Nerve, internal plantar (n. plantaris medialis). Flexor Brevis Digitorum (m. flexor digitorum brevis), from the inner tubercle of the os calcis (calcaneus) (n), the plantar fascia and inter- muscular septa: into the sides of the 2d phalanges of the lesser toes by 4 tendons (5) which are perforated for the long flexor tendons (2). Action, to flex the lesser toes. Nerve, internal plantar (n. plantaris medialis). Abductor Minimi Digiti (m. abductor digiti quinti), from the tubercles and under surface of the os calcis (calcaneus) (n), the plantar fascia and the intermuscular septum: into the base of the proximal phalanx of the little toe with the tendon of its short flexor. Action, to abduct the little toe. Nerve, external plantar (n. plantaris lateralis). Flexor Accessorius (m. quadratus plantae) (i), by 2 heads, from the os calcis (calcaneus) and the long plantar ligament : into the tendon of the flexor longus digitorum. Action, accessory flexor of the toes. Nerve, external plantar (n. plantaris lateralis). Lumbricales (4), iour,from the long flexor tendons: each into the dorsum of the proximal phalanx of the corresponding toe. Action, accessory MUSCLES OF THE FOOT 1 17 flexors of the toes and to dorsiflex the proximal phalanges. Nerves, in- ternal plantar (n. plantaris medialis) to the innermost lumbrical, external plantar (n. plantaris lateralis) to the other three. Flexor Brevis Hallucis (m. flexor hallucis brevis) (7), -from the cuboid and external cuneiform bones, and the prolonged tendon of the tibialis posticus (m. tibialis posterior) : into both sides of the base of the proximal phalanx of the great toe, by 2 portions, of which one blends with the abductor hallucis, the other with the adductor ob- liquus hallucis. Action, to flex the great toe. Nerve, internal plantar (n. plantaris medialis). Adductor Obliquus Hallucis (caput obliquum m. adductoris hallucis), from the tarsal ends of the three middle metatarsal bones, and the sheath of the tendon of the peroneus longus: into the base of the proximal phalanx of the great toe, externally. Action, to adduct the great toe. Nerve, external plantar (n. plantaris lateralis) . Flexor Brevis Minimi Digiti (m. flexor digiti quinti brevis) (6), from the base of the 5th metatarsal bone (9) and the sheath of the tendon of the pero- neus longus: into the base of the proximal phalanx of the little toe externally. Action, to flex the little toe. Nerve, external plantar (n. plantaris lateralis.) Adductor Transversus Hallucis (caput transversum m. adductoris hallucis) (Transversus Pedis), from the inferior metatarso-phalangeal ligaments of the three outer toes and the transverse ligament of the metatarsus: into the outer side of the proximal phalanx of the great toe, blending with the tendon of the adductor obliquus hallucis. Action, to adduct the great toe. Nerve, external plantar (n. plantaris lateralis). Dorsal Interossei (4), each by two heads from the adjacent sides of two metatarsal bones: into the base of the proximal phalanx of the corresponding toe. Action, to abduct the toes. Nerve, external plantar. Plantar Interossei 3, from the shafts of the 3d, 4th, and 5th metatarsai bones: into the bases of the proximal phalanges of the same toes. Ac- tion, to adduct the toes toward the median line. Nerve, external plantar (n. plantaris lateralis). Il8 HUMAN ANATOMY THE BLOOD-VASCULAR SYSTEM THE HEART OR COR The Pericardium is a conical membranous sac, containing the heart and the roots of the great vessels. It lies behind the sternum and between the plurae, its apex upward, its base attached to the central tendon of the dia- phragm. It is composed of an outer fibrous coat, and an inner serous one; the former is prolonged on the outer surfaces of the great vessels, except the inferior vena cava, and becomes continuous with the deep layer of the cervical fascia; the latter consists of a parietal layer, lining the inner sur- face of the fibrous coat, and a visceral layer, which is reflected over the heart and vessels. The serous portion secretes a thin fluid, about i drachm in quantity normally, for the lubrication of its surfaces. Arteries, are derived from the internal mammary and its musculo-phrenic branch, and from the descending thoracic aorta. Nerves, are branches from the vagus, the phrenic and the sympathetic. The Endocardium is a thin, smooth, transparent membrane, which lines the internal surface of the heart; assisting by its reduplications in forming the valves, and being continuous with the lining membrane of the great blood-vessels. JThe Heart (cor) is a hollow muscular organ, conoidal in shape, placed obliquely in the chest between the lungs, base upward, apex to the left and front, corresponding to the space between the 5th and 6th costal cartilages, % inch inside of and i^ inch below the left nipple. In the adult its size is about 5 inches by 3^ by 2%, and from 10 to 12 oz. in weight in the male, 8 to 10 oz. in the female. The Cavities of the Heart are 4 in number, an atrium and ventricle on each side of the heart; the cavities on one side being separated from those of the other side by a longitudinal muscular septum. The division into 4 cavities is indicated on the external surface of the organ by grooves, named, from their contiguous cavities, the auricula-ventricular groove transversely, and the inter-ventricular grooves longitudinally. Structure of the Heart. The muscular fibres forming the heart take origin from four fibrous rings at the auriculo-ventricular and aortic open- ings. The fibres of the auricles are arranged in two layers, a superficial and a deep one, the latter having looped fibres and annular fibres. In the ventricles the fibres are also superficial and deep, the latter being arranged circularly, the former spirally, coiling inward at the apex of the heart into a whorl-like form, the vortex. THE HEART IIQ FIG. 61. Vessels and Nerves. The Arteries are the right and left coronary from theTaorta. The Veins accompany the arteries and terminate in the right auricle. The Lymphatics, terminate in the thoracic and right lymphatic ducts. The N> / are derived from the cardiac plexuses, which are formed partly f vhe cranial nerves and partly from the sympathetic. THE RIGHT HEART The Right Auricle (atrium dextrum) is slightly larger than the left, its walls somewhat thinner, being about one line in thickness; its cavity con- tains about 2 fluidounces. It consists of two parts, a principal cavity, the sinus venosus (i) or atrium, situated posteriorly, and a smaller portion, the appendix auricula (auricula dextra) (2), situated anteriorly. It re- ceives the venous blood by the superior (3) and inferior (4) venae cavae and the coro- nary sinus, and presents in- teriorly the following points for examination: Appendix Auricula (auric- ula dextra) (n), a con- ical pouch projecting from the sinus to the front and left, its margins being dentq,ted. Openings of the superior and inferior venae cavae and the coronary sinus (7), the latter having a valve in two segments. foramina Thebesii (foramina venarum minimarum), several minute orifices, the mouths of veins from the substance of the heart. Auricula-ventricular Opening (ostium venosum dextrum) (9), com- municates with the right ventricle, is oval, about i% inch broad, surrounded by a fibrous ring, and is guarded by the tricuspid valve. Fossa Ovalis (5), a depression on the inner wall, corresponding to the situation of the foramen ovale in the foetus. Annulus Ovalis (limbus fossae ovalis [Vieussenii]), the oval margin of the fossa ovalis. Musculi Pectinatij muscular columns on the inner surface of the appen- dix and the inner wall of the auricle. 120 HUMAN ANATOMY Tubercle of Lower (tuberculum intervenosum [Lower!]), a very small projection on the right wall, supposed to influence the direction of the blood-current. Eustachian Valve (valvula venae cavae inferioris [Eustachii]) (6), at the anterior margin of the inferior vena cava; large in the foetus, to direct the blood to the foramen ovale. Coronary Valve (valvulae sinus coronarii [Thebesii]) (Valve of Thebe- sius) (8), a semicircular fold which protects the orifice of the coronary sinus and prevents regurgitation of blood into the sinus. The Right Ventricle (ventriculus dexter) (a) is triangular in form and extends from the right auricle to near the apex of the heart. Its anterior surface is rounded and convex and forms the larger part of the front of the heart. Its under surface is flattened and rests upon the diaphragm. Its cavity (b c) can contain about 3 fluidounces, and presents the following points for examination: Tricuspid Valve (valvula tricuspidalis) (e, /), consists of 3 triangular segments connected by their bases with the auriculo-ventricular ori- fice, and by their sides with each other, the largest being on the left side. Semilunar Valves (valvulse semilunares a. pulmonalis) (m), are 3 in number, and guard the orifice of the pulmonary artery; each about the middle of its free margin has a fibrocartilaginous nodule, the corpus Arantii (noduli valvarum semilunarum [Arantii]), which more perfectly closes the orifice. Opening of the Pulmonary Artery (ostium arteriosum pulmonis), at the superior and internal angle of the ventricle, the conus artericsus. It is circular in form, surrounded by a fibrous ring, and is guarded by three semilunar valves. Sinuses of Valsalva, are 3 pouches, one behind each valve, between it and the commencement of the pulmonary artery. Columns Ccrnece, (trabeculae carnae) (g), muscular columns projecting from the surface of the ventricle, of which 3 or 4, called musculi papillares, give attachment to the chordae tendinae. Chorda Tending (1), delicate tendinous cords which connect the mar- gins and lower surfaces of the tricuspid valve with the columnae. THE LEFT HEART The Left Auricle (atrium sinistrum) is smaller than the right, but has thicker walls, being about i^ line. Like the right auricle it consists of a principal cavity (i) or sinus (atrium) and an appendix auricula (auricula THE HEART 121 sinistra, (2), which overlaps the root of the pulmonary artery. Internally the auricle presents the following parts: Openings (3) of the Pulmonary Veins, are 4 in number, sometimes 3, as the two left veins (5) frequently end in a common opening. They have no valves. Left Auricula-ventricular Opening (ostium venosum ventriculi sinistri) (6), is smaller than the right one. Musculi Peciinati, on the inner surface of the appendix. Depression, corresponding to the fossa ovalis in the right auricle. FIG. 62. The Left Ventricle (ventriculus sin- ister) (8) is longer, thicker and more conical in shape than the right ven- tricle (/O, and it forms a small part of V- the anterior surface of the heart but a considerable part of its posterior surface. By its projection beyond the apex of the right ventricle it forms the apex of the heart. Its walls are the thickest of those in the heart, being thrice as thick as those of the right ventricle. Its interior (9) pre- sents the following: Left Auricula-ventricular Opening (ostium venosum ventriculi sin- istri), is surrounded by a dense fibrous ring (annulus fibrosus sin- ister) and is guarded by the mitral valve (valvula bicuspidalis). Aortic Opening (ostium arteriosum), is small and circular, placed in front and to the right of the auriculo-ventricular, a segment of the mitral (bicuspid) valve being between them. It is surrounded by a fibrous ring, and guarded by the semilunar valves (valvulae semi- lunares aortae). Mitral Valve (valvula bicuspidalis) (a), consists of two unequal- sized segments, and is attached to the fibrous ring which surrounds the auriculo-ventricular opening (ostium venosum ventriculi sinistri). Its margins are connected with the ventricular walls by chordae tendinae and musculi papillares. Semilunar Valves (valvulae semilunares aortae), 3 in number ggjuard the aortic orifice, and are larger and stronger than those on the right side. 122 HUMAN ANATOMY Sinus of Valsalva, a pouch in the wall of the aorta opposite each seg- ment of the semilunar valves. ColumncB Carnea (6), are smaller and more numerous than those on the right side; the musculi papillares are but two in number, one con- nected to the anterior, the other to the posterior wall. THE ARTERIES The Arteries are cylindrical tubular vessels which carry blood from the ventricles of the heart to every part of the body. The Aorta and its branches, together with the returning veins, constitute the greater or systemic circulation. The Pulmonary Artery and its branches to the lungs, together with the returning veins, constitute the lesser or pulmonic cir- culation. The arteries anastomose or communicate freely with each other everywhere throughout the body, permitting the establishment of collateral circulations. Structure of the Arteries. They are dense in structure, very elastic, preserving their cylindrical form, and are composed of 3 coats, an Internal or serous (tunica intima); a Middle (tunica media), composed of muscular and elastic tissue; and an External (tunica externa or adventitia), com- posed of connective tissue. They are generally included in a fibro- areolar investment, the Sheath, which also encloses the accompanying veins. The larger arteries are nourished by the Vasa Vasorum, blood-vessels which ramify in the external and middle coats; and are supplied with nerves, the Vaso-motor, derived from both the sympathetic and cerebro- spinal systems, and forming intricate plexuses on the larger trunks. The Capillaries are minute vessels forming a network throughout the tissues of the body between the terminating arteries and the commencing veins. Their average diameter is about the Hooo of an inch, average length ^o of an inch and their walls consist of a transparent homoge- neous membrane continuous with the innermost layer of the arterial and venous walls. THE PULMONARY ARTERY AND AORTA The Pulmonary Artery (a. pulmonalis) alone of the arteries carries venous blood, which it conveys from the right side of the heart to the lungs. It is i^-i inch in diameter and only about 2 inches long, and all within the pericardium; arising from the right ventricle in front of the ascending aorta, passing upward and backward to the under surface of the arch of the aorta, where it bifurcates, and is connected at its root to THE AORTA 123 the aorta by a fibrous cord, the remains of the ductus artcriosus of the foetus. Its terminal branches are the Right (ramus dexter a. pulmonalis) and Left (ramus sinister a. pulmonalis) Pulmonary Arteries, the latter being tne" shorter of the two; they pass horizontally outward to the roots of their respective lungs, where each divides into two branches, which again and again subdivide to ramify throughout the lung tissue and end in the capillaries of those organs. The Aorta (arteria magna) is the main trunk of the systemic arteries, commencing at the aortic opening of the left ventricle of the heart, it arches backward over the roof of the left lung into the thorax, where it descends on the left of the spinal column, and after passing through the aortic opening in the diaphragm, it terminates in the right and left common iliac arteries opposite the 4th lumbar vertebra. It is divided into the ^Ascending Aorta (aorta asc'ehdens) (5), the Arch (arcus aortae) (6), and the Ascending Aorta (aorta descendens) (12), the last-named being again divided into the Thoracic Aorta (aorta thoracalis) and the Abdominal Aorta (aorta abddnimalis) (described under Arteries of the Trunk). Th*e" upper border of the arch is generally situated about an inch below the upper margin of the sternum. The branches of the aorta are From the Ascending Aorta, 2 Coronary Arteries (4). From the Arch, Innominate (a. anonyma) (7). Left Common Carotid (10). Left Subclavian (n). From the Thoracic, Pericardia!. (Esophageal. 18 Intercostals. Bronchial. Posterior Mediastinal. From the Abdominal, 2 Phrenic. { Gastric. Cceliac Axis. { Hepatic. ( Splenic (a. lienalis). 2 Spermatic, in the male. 2 Ovarian, in female. Inferior Mesenteric. Superior Mesenteric. 8 Lumbar. 2 Supra-renal. Sacra Media. 2 Renal. 2 Common Iliac. The Coronary Arteries are 2 in number, a right and a left (4), arise from the aorta in the sinuses of Valsalva behind the semilunar valves, and run in the vertical grooves of the heart, the left artery in front, to supply the tissue of that organ. Each artery divides into 2 branches, the transverse and the descending, the latter anastomosing at the apex of the heart with its fellow of the opposite side. The descending branch of the right coro- 124 HUMAN ANATOMY FIG. 63. nary sends off a marginal branch along the margin of the right ventricle, and an infundibular branch to the conus ar- teriosus of the same ventricle. The Innominate Artery (a. anonyma) (7) arises from the summit of the arch of the aorta, is i^ inch long, and divides behind the right sternoclavicular joint into the Right Common Carotid (9) and Right Subdavian (8), these arteries on the left side of the body (10, n) arising directly from the arch of the aorta. It sometimes sends off a small branch, the Thyroidea ima, to the thyroid body; which vessel may arise from the arch of the aorta, the right common carotid, the subclavian, or the internal mammary. The Innominate artery is sometimes absent and not infre- quently varies in length from }$ inch to 2 inches. ARTERIES OF THE HEAD AND NECK The Common Carotid Arteries (Arterae Carotides Communes). Arising differently (see above) the two carotids are similarly described, except that the left is longer and deeper than the right one. Their course is indi- cated by a line drawn from a point midway between the angle of the lower jaw and the mastoid process to the sterno- clavicular articulation. At the lower part of the neck they are separated only by the width of the trachea, and they are each contained in a sheath of the deep cervical fascia with the internal jugular vein externally and the pneumogastric nerve (n. vagus) between the artery and vein. On the front of the sheath lies the descendens hypo- Pic. 64. ARTERIES OF THE HEAD AND NECK 125 glossi nerve (descending branch of the i2th or hypoglossal). The artery lies beneath the inner border of the sterno-cleido-mastoid muscle, and is crossed about its middle by the omo-hyoid muscle and the middle thyroid vein. It is also crossed above by the facial, lingual, and su- perior thyroid veins, below by the anterior jugular vein, and on the left side often by the internal jugular vein. It bifurcates, at the level of the upper border of the thyroid cartilage, into the External and Internal Carotids, of which the internal is the more remote from the median line. The External Carotid Artery (a. carotis externa) (2) (Fig. 64) commences opposite the upper border of the thyroid cartilage, and passes upward, forward and backward to the space between the neck of the condyle of the lower jaw and the external meat us, where it divides into the temporal and internal maxillary arteries. It has 8 branches, the Superior Thyroid (a. thyreoidea superior) (4), arising below the greater cornu of the hyoid bone; giving off Muscular. Hyoid. Superior Laryngeal. Glandular. Superficial Descending. Crico-thyroid. Lingual (a. lingualis) (5), under the hyo-glossus muscle to the tongue; giving off Hyoid. Dorsalis Linguae. Sublingual. Ranine. Facial (a. maxillaris externa), should be called superficial facial (6), crosses the lower jaw at the anterior border of the masseter; giving off- Inferior (Ascending) Palatine. Submental (7). 2 Coronary (aa. la- Tonsillar. Muscular. biales) (8, 9). Submandibular. Inferior Labial. Lateralis Nasi. Angular. Occipital (a. occipitalis) (10), lies in the occipital groove of the temporal bone. Muscular. Auricular. Arteria Princeps Cervicis Sterno-mastoid. Meningeal. (13) (ramus descen- dens a. occipitalis). Posterior Auricular (a. auricularis posterior) (14), ascends under cover of the parotid gland. Stylo-mastoid. Auricular. Mastoid. Muscular. Glandular. Ascending Pharyngeal, (a. pharyngea ascendens), lies on the rectus capitis anticus major. Prevertebral. Pharyngeal. Tympanic. Meningeal. 126 HUMAN ANATOMY FIG. 65. Superficial Temporal (a. temporalis superficialis) (15), the smallest of the termini of the external carotid, begins in the parotid gland, crosses the zygomatic arch, and divides into anterior (13) and posterior temporal (16). Its branches are the Parotid. Articular. Zygomatico-orbital. Frontal. Parietal. Transverse Facial (15). Middle Temporal (17). Anterior Auricular. Internal Maxillary (a. maxillaris in- terna), should be called deep facial (4), the other terminal branch of the external carotid (i), is di- vided into three portions, Maxil- lary (4), Pterygoid (5), and Spheno- maxillary (6), which re- spectively give off the following branches (Fig. 65): Maxillary Deep Auricular, to the tragus and canal. Anterior Tympanic (7), enter- ing the Glaserian (petro-tym- panic) fissure. Middle Meningeal (8). Small or Accessory Meningeal (9). Inferior Alveolar or Dental (10), divides into Incisor and Mental. Pterygoid Deep Temporal, ant. and poste- rior. Pterygoid Branches, to those muscles. Masseteric, to the masseter mus- cle. Buccal, to the buccinator muscle. S pheno-maxillary Posterior Superior Alveolar (n). Infra-orbital (12). Descend. Palatine (13). Vidian (a. canalis pterygoidea) (16). Pterygo-palatine (15). Spheno-palatine or Naso-paia- tine (14). Pharyngeal. The Internal Carotid Artery (a. carotis interna) commences at the bifurcation of the common carotid and ascends in front of the transverse processes of the three upper cervical vertebrae, and close to the tonsil, traverses the carotid canal in the temporal bone, and after piercing the INTERNAL CAROTID ARTERY 127 dura mater close by the anterior clinoid process, divides into its terminal (cerebral) branches. It curves remarkably in different parts of its course, in the carotid canal and alongside the body of the sphenoid bone it de- scribes a double curvature resembling the italic letter S placed horizon- . tally. In the cervical portion no branches are given off; in the petrous, cavernous and cerebral portions it gives off the following: Tympanic (a. carotico- tympanic), enters the tympanum from the carotid canal, and anastomoses on the membrana tympani with the tympanic branch of the internal maxillary and the stylo-mastoid. Arteries Receptaculi (aa. cavernosae), numerous small vessels going to the walls of the sinuses, the Gasserian (semilunar) ganglion and the pituitary body (hypophysis). Anterior Meningeal, a small branch to the dura mater of the anterior fossa, after passing over the lesser wing of the sphenoid. Ophthalmic^ arises from the cavernous portion, enters the orbit through the optic foramen, terminating at the inner angle of the eye into the frontal and nasal branches. It gives off the following branches: Ocular Group Orbital Group Art. Centralis Retinae. Lacrimal. Frontal. Muscular. Supra-orbital. Nasal. Anterior Ciliary. Posterior Ethmoidal. (the Short Ciliary. Anterior Ethmoidal. terminal. Long Ciliary. Internal Palpebral. branches). '**' Anterior Cerebral, joined to its fellow by the Anterior Communicating Artery, about 2 lines long; then runs alongside its fellow, terminating by anastomosis with the posterior cerebral arteries, and giving off the following branches: Antero-median Ganglionic or Basal. Inferior Internal or Medial Frontal. Ant. Internal or Medial Frontal. Middle Internal or Medial Frontal. Posterior Internal or Medial Frontal. Middle Cerebral (a. cerebri media), in the fissure of Sylvius; divides into: Antero-lateral Ganglionic or Basal. Ascending Frontal. Inferior External or Lateral Frontal. Ascending Parietal. Parieto-temporal. Posterior Communicating, anastomoses with the posterior cerebral, a branch of the basilar, and gives off the: 128 HUMAN ANATOMY Postero-median Ganglionic, branches supplying the optic thalami and the walls of the 3rd ventricle. Anterior Choroid,to the hippocampus major, corpus fimbriatum, etc. and ends in the choroid plexus. [The vertebral Artery, a branch of the Subclavian, and the Basilar Artery, formed by the junction of the two vertebrals, may be considered arteries of the head and neck, but they are most conveniently described as branches of the Subclavian Artery (see below.)] THE CIRCLE OF WILLIS The Circle of Willis (circulus arteriosus) is a remarkable anastomosis at the base of the brain, formed by the branches of the vertebral and in- ternal carotid arteries, and giving origin to the 3 trunks which supply each cerebral hemisphere. Posteriorly, the two Vertebral arteries unite to form the Basilar, which ends in the two Posterior Cerebral. Anteriorly, each Internal Carotid gives off the Anterior Cerebral, these latter being connected by the short Anterior Communicating artery. The circle is completed by the Posterior Communicating arteries, one on each side, which connect the posterior cerebral with the internal carotid. The Circle of Willis gives off, anteriorly, the anterior cerebral arteries; antero-laterally, the middle cerebral; and posteriorly, the posterior cerebral; each artery giving origin to two very different arterial systems: the Cen- tral Ganglionic System, supplying the central ganglia of the brain; the Cortical Arterial System, which ramifies the pia mater and supplies the cortex and subjacent medullary substance. The two systems, though having a common origin, do not communicate afterwards, and in their distribution are entirely independent of each other. Hence, between the parts supplied by each, there is a zone of diminished nutritive activity, where softening may be especially liable to occur in the brains of old people. By the Circle of Willis the cerebral circulation is equalized and provision made for carrying it on if one or more of the branches should be obliterated. THE TRIANGLES OF THE NECK Anterior Triangle of the Neck is bounded, in front, by a line extending from the chin to the sternum; behind, by the anterior margin of the sterno-mastoid muscle; its base, directed upward, is formed by the lower border of the body of the jaw and a line extending from the angle of the jaw to the mastoid process; its apex is below, at the sternum. It is crossed by the digastric muscle above and the anterior belly of the omo- hyoid below, dividing it into 3 smaller triangles, named from below up- TRIANGLES OF THE NECK I 29 ward the Inferior Carotid, the Superior Carotid, and the Submaxillary or Submandibular triangles. Inferior Carotid Triangle, situated below the anterior belly of the omo- hyoid, contains at it's posterior edge in a common sheath the lower portion of the common carotid artery, the pneumogastric nerve and the internal jugular vein, concealed by the sterno-mastoid muscle, also other structures, which with the former may be summarized as follows: Muscles, the sterno-hyoid and sterno-thyroid, covering the common carotid artery. Arteries, the common carotid and the inferior thyroid. Veins, the internal jugular, as described above. Nerves, the pneumogastric (n. vagus) recurrent laryngeal, and sympathetic, also filaments from the loop between the descendens and communicans hypoglossi. Other Structures, the trachea, thyroid gland, and the lower part of the larynx. Superior Carotid Triangle, situated above the anterior belly of the omo- hyoid, contains the upper part of the common carotid artery and its bifurcation into the internal and external carotid, also other structures, all summarized as follows: Muscles, parts of the thyro-hyoid, hyo-glossus, inferior and middle con- strictors of the pharynx. Vessels, the common carotid artery, the internal and external carotid arteries, and the internal jugular vein; the superior thyroid, lingual, facial (external maxillary), occipital and ascending pharyngeal branches of the external carotid and the veins accompanying them. Nerves, the pneumogastric (n. vagus), spinal accessory (n. accesso- rius), hypoglossal, descendens hypoglossi, sympathetic, internal and external laryngeal. Other Structures, the upper part of the larynx, and the lower part of the pharynx. Sub-mandibular or Sub-maxillary Triangle, immediately below the body of the jaw, and above the posterior belly of the digastric and the stylo-hyoid; contains the following: Muscles, the mylo-hyoid, hyo-glossus, stylo-glossus, and stylo- pharyngeus. Arteries, the external and internal carotid; also the facial (external maxillary), posterior auricular, temporal, internal maxillary, sub- mental, and mylo-hyoid arteries. Veins, the facial and internal jugular, o 130 HUMAN ANATOMY Nerves, the pneumogastric (n. vagus), glosso-pharyngeal, facial, and mylo-hyoid. Glands, the parotid and sub-maxillary (sub-mandibular). Posterior Triangle of the Neck is bounded, in front by the sterno- mastoid muscle; behind, by the trapezius; its base corresponds to the middle third of the clavicle, its apex is at the occiput. It is crossed by the posterior belly of the omo-hyoid muscle about an inch above the clavicle, subdividing it into two smaller triangles, the Occipital above, and the Subclavian below. Occipital Triangle, the larger division of the posterior triangle of the neck, above the posterior belly of the omo-hyoid muscle, contains the following: Muscles, the splenius, levator anguli scapulae (m. levator scapulae), middle and posterior scaleni. Vessels, the transversalis colli artery and vein. Nerves, the spinal accessory (n. accessorius), and descending branches of the cervical plexus. Glands, a chain of lymphatic glands. Subclavian Triangle, the smaller of the divisions of the posterior triangle of the neck, situated below the posterior belly of the omo-hyoid muscle, and above the middle third of the clavicle, contains the following: Vessels, the subclavian artery, the Subclavian vein occasionally, the transversalis colli and suprascapular arteries (a. transversa scapulae), and veins, the external jugular and transverse cervical veins. Nerves, the brachial plexus, descending branches of the cervical plexus. nerve to the subclavius muscle. Glands, a lymphatic gland. ARTERIES OF THE UPPER EXTREMITY The Subclavian Artery (Arteria Subclavia) arises on the right side from the innominate, of the left side from the arch of the aorta, and is divided into 3 portions by the scalenus anticus muscle, which crosses it just external to the origin of the thyroid axis, viz. the parts internal, behind, and external to that muscle. At the outer border of the ist rib, the sub- clavian becomes the Axillary Artery. Its upper border is a little above the clavicle, and it is separated from the subclavian vein by the scalenus anticus at its origin from the first rib. Its branches are all given from its first portion, except the Superior Intercostal, which on the right side arises from the second portion. Its branches are the SUBCLAVIAN ARTERY FIG. 66. VERTEBRAL (a. vertebralis) (6), passing up the neck, through the fora- mina in the transverse processes of six cervical vertebrae, enters the skull by the foramen magnum, where it joins its fellow to form the Basilar Artery. Its branches are- Lateral Spinal Branches. Muscular Branches. Posterior Meningeal. Anterior Spinal. Posterior Spinal. Posterior Inferior Cerebellar. Bulbar. The Basilar (a. basilaris), formed by the junction of the vertebrals, gives off on each side a transverse, anterior, and superior cerebellar, and ends in the two posterior cere- bral. (See Circle of Willis, pages 151 and 158.) THYROID Axis (truncus thyreocervi- calis) (8), at once divides into the three following branches. Inferior Thyroid (a. thyreoidea inferior) (7), to the thyroid gland, giving off Inferior Laryngeal. CEsophageal Branches. Tracheal. Muscular. Ascending Cervical (9). 2 Terminal. Suprascapular (a. transversa scapulae) (12), to the shoulder- joint and the dorsum of the scapula, anastomosing there with the pos- terior and subscapular. Transversalis Colli (n), divides beneath the margin of thetrapezius into Superficial Cervical (ramus ascendens). Posterior Scapular (ramus descendens). INTERNAL MAMMARY (a. mammaria interna) (13), arises opposite the thyroid axis, descends behind the costal cartilages, and ends at the 6th interval, in the musculo-phrenic and superior epigastric, the latter anastomosing with the deep epigastric branch of the external iliac. Its branches are the 132 HUMAN ANATOMY Comes Nervi Phrenici Paricardiac. Perforating, (pericardiaco-phrenic), Sternal. Musculo-phrenic. or Superior Phrenic. Anterior Intercostal. Superior Epigastric. / Mediastinal. '" SUPERIOR INTERCOSTAL (a. intercostalis suprema) (14), gives off branches in the intercostal spaces to the posterior spinal muscles and to the spinal cord. One branch, the Profunda Cervids (a. cervicalis profunda) (10), supplies the mus- cles of the back of the neck, and anastomoses with the arteria princeps cervicis (ramus descendens a. occipitalis) of the occipital. This vessel occasionally arises from the subclavian artery. 1 The Axillary Artery (a. axillaris) (5), the continuation of the subclavian, commences at the outer border of the first rib, and terminates at the lower border of the tendon of the teres major muscle, where it becomes the brachial artery. The pectoralis minor crosses it and marks its division into three portions, ist, above; 2nd behind, and 3rd below that muscle. The brachial plexus is in close relation with the artery, surrounding it on three sides in the second portion. Its branches are 7 in number as follows: Superior Thoracic (a. thoracalis suprema), from the first portion; supplies the pectoral muscles and the walls of the thorax. Acromial Thoracic (a. thoraco-acromialis), from the first portion; divides into the Thoracic (pectoral) Branches 2 or 3, to the serratus magnus (m. serratus anterior) and pectorals. Acromial Branches, to the deltoid muscles. Descending or Humeral (deltoid), to the pectoralis major and deltoid. Clavicular, a very small branch, to the subclavius muscle. Mar Thoracic, from the second portion; to the glands and theareolar tissue of the axilla. Long Thoracic (a. thoracalis lateralis or external mammary), from " tlie second portion; to the serratus magnus (m. serratus anterior), the pectoral muscles and the mammary gland. Subscapular (a. subscapularis), from the third portion; to the inferior angle of the scapula, where it anastomoses with the long thoracic, the intercostal and the posterior scapular (ramus descendens a. transversalis Colli) arteries. It gives off small branches to the del- toid and triceps muscles, and the Dorsalis Scapulae (a. circumflexa scapulae), a large branch, to the subscapular fossa and the axillary border of the scapula. ARTERIES OF THE UPPER EXTREMITY 133 Posterior Circumflex (a. circumflexa humeri posterior), from the third portion; winds around the neck of the humerus to the deltoid muscle and the shoulder-joint, anastomosing with the anterior circumflex and other arteries. Anterior Circumflex (a. circumflexa humeri anterior), from the third portion; winds around the neck of the humerus, to the head of that bone, the deltoid muscle and the shoulder-joint, anastomosing with the posterior circumflex. The Brachial Artery (a. Brachialis) is the continuation of the axillary from the lower margin of the teres major tendon to its bifurcation into the radial and ulnar, which is usually about half an inch below the bend of the elbow. The median nerve crosses it from the outside to the inside about its middle. Above its bifurcation it is crossed diagonally by the bicipital fascia (lacertus fibrosus). The basilic vein lies on its inner side but sepa- rated from it in the lower part of the arm by the deep fascia. Its branches are the Superior Profunda (a. profunda brachii), winds over the arm in the spiral groove (sulcus radialis), giving off the posterior articular to the elbow anastomosis, and a branch to anastomose with the recur- rent branch of the radial, and a nutrient artery to the bone. This artery supplies the triceps muscle. Nutrient Branch, enters the nutrient canal of the humerus. Inferior Profunda (a. collateralis ulnaris superior), to the elbow-joint anastomosis. - Anastomotica Magna (a. collateralis ulnaris inferior], anastomoses with the posterior articular, inferior profunda (superior ulnar col- lateral) anterior and posterior ulnar recurrent. Muscular Branches, to the muscles in the course of the artery. The Radial Artery (a. radialis) extends from the bifurcation of the brachial to the deep palmar arch, and gives off the following branches: In the Forearm, Radial Recurrent, to the supinators, the brachialis anticus and the elbow joint, anastomosing with the terminal branches of the superior profunda (a. profunda brachii). *'- Muscular Branches, to the muscles on the radial side of the forearm. Anterior Carpal (ramus carpeus volaris), anastomoses with the anterior carpal of the ulnar artery, forming the Anterior Carpal Arch (rete carpi volare). Superficialis Voice, to the muscles of the thumb. 134 HUMAN ANATOMY In the Wrist, Posterior Carpal (ramus carpeus dorsalis), anastomoses with the pos- terior carpal of the ulnar artery forming the Posterior Carpal Arch (rete carpi dorsale). Metacarpal, the first dorsal interosseous branch, divides into two dorsal digital branches, supplying the adjoining sides of the index and middle fingers. 7 Dor sales Pollicis 2, along the sides of the thumb. Dorsalis Indicis, along the radial side of the index finger. Ln the Hand, Princeps Pollicis, along the sides of the palmar aspect of the thumb by two branches forming an arch. Radialis Indicis (a. volaris indicis radialis), along the radial side of the index finger to anastomose with the collateral digital and the princeps pollicis, giving a communicating branch to the superficial palmar arch (arcus volaris superficialis). Perforating 3, backward from the deep palmar arch to anastomose with the dorsal interosseous arteries. Palmar Interosseous 3 or 4, from the deep palmar arch, on the inter- ossei muscles to anastomose with the digital branches of the super- ficial arch (arcus volaris superficialis). Palmar Recurrent, from the deep palmar arch to the carpal joints, anastomosing with the anterior carpal arch (rete carpi volare). The Ulnar Artery (a. ulnaris) extends from the bifurcation of the brachial just below the bend of the elbow along the ulnar border of the forearm to the wrist. Immediately beyond the pisiform bone it divides into two branches which enter into the formation of the superficial and deep palmar (volar) arches. Its branches are as follows: In the Forearm, Anterior Ulnar Recurrent (a. recurrentes ulnaris anterior), anastomoses in front of the inner condyle of the humerus with the anastomotica magna (inferior ulnar collateral) and the inferior profunda (superior ulnar collateral). Posterior Ulnar Recurrent (a. recurrentes ulnaris posterior), anasto- moses behind the inner condyle of the humerus with the anastomotica magna (inferior ulnar collateral), inferior profunda (superior ulnar collateral) and interosseous recurrent. Interosseous, about % inch long, divides into two branches. The Anterior Interosseous (volar interosseous) gives off the Median Artery to the median nerve and a Nutrient branch to both bones of the ARTERIES OF THE FOREARM AND HAND 135 forearm. The Posterior (dorsal) Interosseous gives off near its origin the Interosseous Recurrent to the elbow-joint anastomosis. Muscular,- to the muscles on the ulnar side of the forearm. In the Wrist, Anterior Carpal, (ramus carpeus volaris), anastomoses with a cor- responding branch of the radial artery in front of the carpus. Posterior Carpal (ramus carpeus dorsalis), anastomoses with a cor- responding branch of the radial artery forming the posterior carpal arch (rete carpi dorsale). In the Hand, Deep or Communicating (ramus volaris profunda), anastomoses with the termination of the radial artery, completing the deep palmar arch (arcus volaris profundus). Superficial Palmar Arch (arcus volaris superficialis), is the continua- tion of the trunk of the ulnar artery in the hand. Digital 4, given off by the superficial palmar arch (arcus volaris "superficialis). - S V THE CARPAL ARCHES The Anterior Carpal Arch (rete carpi volare) is formed by the anastomo- sis of the anterior carpal of the radial with the anterior (volar) carpal of the ulnar artery in front of the wrist. It is joined by branches from the anterior (volar) interosseous above and by recurrent branches from the deep palmar (volar) arch below, and gives off branches to supply the articulations of the wrist and carpus. The Posterior Carpal Arch (rete carpi dorsale) is formed by the anastomosis of the posterior (dorsal) carpal of the radial with the posterior (dorsal) carpal of the ulnar artery. It is joined by the termination of the anterior (volar) interosseous artery and gives off dorsal interosseous arteries for the third and fourth interosseous spaces, which divide into dorsal digital branches which supply the adjacent sides of the middle, ring and little fingers, and communicate with the digital arteries of the superficial palmar (volar) arch, and at their origin with the perforating branches from the deep palmar (volar) arch. THE PALMAR ARCHES The Superficial Palmar Arch (arcus volaris superficialis) is formed by the part of the ulnar artery which lies in the palm of the hand, and is completed by that artery anastomosing with a branch from theradialis indicis, at the root of the thumb; sometimes with the superficialis volae or the princeps pollicis of the radial. It gives off 4 Digital Collateral 136 HUMAN ANATOMY branches to the sides of the fingers, except the radial side of the index finger, which with the thumb is supplied from the radial artery. The Deep Palmar Arch (arcus volaris profundus) is formed by the palmar portion of the radial artery, and is completed by the anastomosis of that artery with the deep palmar (communicating) branch of the ulnar. It lies upon the carpal ends of the metacarpal bones and the interossei muscles, about ^ inch nearer to the carpus than the superficial palmar (volar) arch, from which it is separated by the transverse carpal ligament, the flexor brevis minimi digiti, (m. flexor digiti quinti brevis) the super- ficial flexor tendons and divisions of the median and ulnar nerves. From it are given off the radialis indicis, palmar (volar) interosseous, perforating and palmar (volar) recurrent branches of the radial artery. ARTERIES OF THE TRUNK THE DESCENDING AORTA (AORTA DESCENDENS) The Descending Aorta is divided into two portions, the Thoracic Aorta (aorta thoracalis) and the Abdominal Aorta (aorta abdominalis), cor- responding to the two great cavities of the trunk in which they are situated. The Thoracic Aorta (aorta thoracalis) commences at the lower border of the 4th thoracic vertebra on the left of the spine, and descends in the back part of the posterior mediastinum, terminating at the aortic opening in the diaphragm directly in front of the lower border of the last thoracic vertebra. Its branches are Pericardia!, irregular in origin, to the pericardium. Bronchial, vary in number and origin; generally one on the right side and two on the left. They nourish the lungs, bronchial glands and the oesophagus. (Esqpjiageal, 4 or 5, anastomose on the oesophagus with branches of the inferiorThyroid, phrenic, and gastric arteries. Posterior Mediastinal, numerous small vessels supplying the glands and the areolar tissue in the mediastinum. Intercostals, usuallvjj on each side, the two superior intercostal spaces being supplied by the superior intercostal branch of the subclavian. They run between the two layers of intercostal muscles, anastomose with the anterior intercostal branches of the internal mammary, and each gives off the following branches: Posterior or Dorsal, to the muscles and skin of the back. Spinal, to the spinal cord and its membranes. Collateral Intercostal, along the upper border of the rib below. ABDOMINAL AORTA 137 FIG. 67. .The Abdominal Aorta (aorta abdominalis) begins where the thoracic aorta ends (see p. 123) and terminates on the body of the 4th lumbar vertebra, where it divides into the two common iliac arteries. Its branches are as follows: 2 Inferior Phrenic (i), one on each side, but usually only one arises from the aorta, the other springing from either the coeliac axis or the renal artery. They go to the under surface of the diaphragm, where each a rtery divides into two branches, an external and an in- ternal, the former to the side the latter to the front of the thorax and the diaphragm. CCELIAC Axis (a. coeliaca) (2), arises from the aorta, close to the margin of the opening in the diaphragm, runs forward for half an inch, and divides into the Left Gastric, He- patic, and Splenic (a. lienalis) arte- ries, occasionally giving off one of the phrenics. The Js'ft Gastric (a. gastrica sinistra) (3), supplies the stomach along its lesser curvature, anastomosing with the aortic cesophageal, splenic (a lienalis), and hepatic branches. JIeatic (a. hepatica) (4), forms the lower boundary of the foramen of Winslow (foramen epiploicum), passes upward to the transverse fissure (porta hepatis) of the liver where it divides into two branches, right and left, supplying the corre- sponding lobes of that organ. Its branches are the Pyloric (a. gastrica dextra), to the pyloric end of the stomach and along the lesser curvature of that viscus. Gastro-duodenalis, giving off the Gastro-epiploica Dextra along the greater curvature of the stomach, and the Pancreatico-duo- 138 HUMAN ANATOMY denalis Superior to the contiguous margins of the duodenum and pancreas. Right Hepatic, to the right lobe of the liver, giving off the Cystic Artery to the gall-bladder. Left Hepatic, to the left lobe of the liver. Splenic (a. lienalis) (5), the largest, branch of the cceliac axis, passes by ^""a very tortuous course to the spleen, giving off the following: Pancreaticae Parvae. Gastric (VasaBrevia) (a.a. gastricae breves) to the stomach. Pancreatica Magna. Gastro-epiploica Sinistra, to the stomach. Terminal Branches, enter the hilum of the spleen. Superior Mewnteric (a. mesenterica superior) (9), supplies the small intestine, caecum, ascending and transverse colon. Arising about % inch below the cceliac axis it arches forward, downward, and to the left, giving off the Inferior Pancreatico-duodenal. Ileo-colic. Vasa Intestini Tenuis (aa. in- Colica Dextra and Media. testinales), 12 to 15. V " Supra-renal (a. supra-renalis media) (6), arise one on each side, opposite the origin of the superior mesenteric, passing to the supra- renal capsules. 2 Renal (aa. renales) (7), one from each side, just below the preceding, pass to the kidney, at its hilum having the middle place between the ureter behind and the renal vein in front. U. A. V. (you 'ave!) 2 Spermatic (aa. spermaticae internae) (10), one on each side, in the male through the inguinal canal to the testes; in the female it is called Ovarian (a. ovarica), going to the ovaries, uterus and skin of the labia and groins. Inferior Mesenteric (a mesenterica inferior) (n), supplies the descend- ing colon, sigmoid flexure, and most of the rectum, giving off the following branches: Colica Sinistra. Sigmoid (aa. sig- Superior Hemorrhoidal. moidece). Lumbar (aa. lumbales) (8), usually 4 on each side, analogous to the intercostals. They each divide into two branches, the Dorsal, giving off a spinal branch. Abdominal. Middle Sacral (a. sacralis media) (12), arises just at the bifurcation of / THE ILIAC ARTERIES 139 the aorta; it descends along the last lumbar vertebra and the front of the sacrum to the upper part of the coccyx, giving off numerous branches on each side to anastomose with the lateral sacral arteries. It terminates in a minute branch which goes to the coccygeal gland (Luschka), and sends off branches to the rectum. THE ILIAC ARTERIES (ARTERLE ILIAC.E) The Common Iliac Arteries (aa. iliacae communes) extend from the bifurcation of the aorta at the 4th lumbar vertebra to the lumbo-sacral articulation, where each divides into the External Iliac (15) and the Internal Iliac (a. hypogastrica) (14); the former supplying the lower extremity, the latter going to the viscera and walls of the pelvis. The common iliac arteries are about 2 inches in length, the right being a little longer than the left, and each is crossed by the ureter, just before its bifurcation. The Internal Iliac (arteria hypogastrica) (14) is about i% inches long, extending from the lumbo-sacral articulation to the great sacro-sciatic notch, where it divides into an anterior and a posterior trunk. From the Anterior Trunk are given off, from above downward, the Superior Vesical (a. vesicalis superior), the remaining previous part, of the fcEtal hypogastric artery. It sends branches to the bladder the vas deferens and the ureter; and one, the Middle Vesical, to the base of the bladder. Obturator (a. obturatoria), through the canal in the obturator mem- brane to the thigh, where it divides into an internal and external branch. Within the pelvis it gives off an iliac, a vesical, and a pubic branch. In one out of every 3^ cases this artery arises from the deep epigastric (a. epigastrica inferior), in 2 out of every 3 from the internal iliac (a. hypogastrica), in i out of 7^ by two roots from both vessels and in about the same proportion from the external iliac. Inferior Vesical (a. vesicalis inferior), to the bladder, prostrate gland, and vesiculae seminales. In the female this artery is called the Vaginal (a. vaginalis). Middle Hemorrhoidal (a. haemorrhoidalis medialis), to the anus and parts outside the rectum. Uterine (a. uterina), in the female, anastomosing with a branch (ramus ovarii) from the ovarian. It gives off cervical branches to the cervix uteri and the azygos arteries of the vagina. Internal Pudic (a. pudenda interna), the smaller of the terminal branches of the anterior trunk, supplies the external generative 140 HUMAN ANATOMY organs. Its muscular branches in the pelvis are numerous and small; in the perineum they are the Inferior Hemorrhoidal (a. Artery of the Bulb (a. bulbi haemorrhoidalis inferior). urethrae). Superficial Perineal (a. Urethral (a. urethralis). perinei). Artery of the Corpus Cavernosum Transverse Perineal (a. (a. profunda penis). trans versa perinei). Dorsal Artery of the Penis (a dor- salis penis). Sciatic (a. glutaea), the other terminal branch, supplies the muscles on the back of the pelvis. Its branches are the Muscular (internal), rami musculares. Hemorrhoidal Brs. Vesical Branches. Coccygeal. Cutaneous. Comes Nervi Ischiadici, (a. comitans n. ischiadici). Muscular (ext.), (rami musculares). Anastomotic. Articular. THE POSTERIOR TRUNK gives off the following: Ilio-lumbar (a. ilio-lumbalis), dividing into a lumbar and an ilica branch. Lateral Sacral (arteriae sacrales laterales), superior and inferior on each side. Gluteal (a. glutaea superior), the continuation of the posterior trunk, divides into a superficial and a deep branch, to the glutei muscles, the skin over the sacrum, and the hip-joint. Before dividing it gives a nutrient branch to the ilium, and some muscular branches. The External Iliac (a. iliaca externa) extends to beneath the centre of Poupart's ligament (l.inguinale), where it enters the thigh and becomes the Femoral Artery; lying between the femoral vein on the inside and the anterior crural nerve (n. femoralis) on the outside V.A.N. Its branches are small muscular and glandular, and the - Deep Epigastric (a. epigastrica inferior), which arises a few lines above Poupart's inguinal ligament, passes between the peritoneum and the transversalis fascia, to the sheath of the rectus which it enters and ascends behind that muscle, to anastomose by numerous branches with the terminal branches of the internal mammary and inferior intercostal. It gives off the THE FEMORAL ARTERY 141 Cremasteric (a. spermaticainthe male; a. ligament! teres uteri in the female). Pubic. Muscular Branches (rami musculares). Deep Circumflex Iliac (a. circumflexa ilium profunda), arises opposite to the epigastric, passes along 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, gluteal (a. glutaea superior), lumbar and epigastric ateries. ^'5*4 ARTERIES OF THE LOWER EXTREMITY The Femoral Artery (arteria femoralis) extends from Poupart's liga- ment (1. inguinale) to the opening in the adductor magnus, where it becomes the popliteal artery. Its course corresponds to a line drawn from a point midway between the anterior superior spine of the ilium and the spine of pubis, to the inner side of the inner condyle of the femur. It lies in a strong fibrous sheath with the femoral vein, but divided from the latter by a fibrous partition. It may be divided into two portions, the Common Femoral and the Superficial Femoral, for convenient de- scription, as follows: The Common Femoral Artery, about 2 inches long, is very superficial, rests on the inner margin of the psoas muscle, which separates it from the capsular ligament of the hip-joint, and is covered by the skin, superficial fascia, superficial inguinal glands, iliac portion of the fascia lata, and the anterior part of the sheath of the vessels. The Superficial Femoral Artery, is only superficial in Scarpa's triangle (femoral trigone), being deeper in Hunter's canal (adductor canal). It lies above on the femoral vein and the profunda artery and vein; below, on the adductor longus and adductor magnus muscles. The internal saphenous nerve crosses it from without inward. Branches of the Femoral Artery, are as follows: Superficial Epigastric (a. epigastrica superficialis) (c), through the saphenous opening (fossa ovalis) to ascend on the abdomen, giving off branches to the skin, the superficial fascia and the superficial inguinal glands. Superficial Circumflex Iliac (a. circumflexa ilium superficialis) (;'), to the crest of the ilium, supplying the skin of the groin, the superficial fascia, and the superficial inguinal glands. Superficial External Pudic (a. pudenda externa superficialis) (d), through the saphenous opening (fossa ovalis) to the skin of the abdomen, the penis and the scrotum (and the labium in the female). 142 HUMAN ANATOMY FIG. 68. Deep External Pudic (a. pundenda externa profunda) (d), to the skin of the scrotum and perinseum (and the labium in the female). Muscular (rami musculares). Profunda Femoris (Deep Femoral Artery) (e), arises posteriorly about i or 2 inches below Poupart's (inguinal) ligament, and descends to the lower third of the back of the thigh, giving off the following branches: Ext. Circumflex (a. circumflexa femoris lateralis) (g). Int. Circumflex (a. circumflexa femoris medialis) (/). 3 Perforating (aa. perforantes) (h). Terminal or 4th perforating. Muscular Branches (rami musculares) (&), to the sartorius and vastus internus. Anastomotica Magna (a. genu suprema), arises from the femoral in Hunter's (ad- ductor) canal and divides into a super- ficial and a deep branch, the latter anas- tomosing around the knee-joint with the superior external and internal articular arteries, and the recurrent branch of the aniecior tibial. Scarpa's Triangle (Trigonum Femorale) is a triangular space in the thigh which cor- responds to the depression seen immediately below the fold of the groin. Its apex is down- ward, its base formed by Poupart's (inguinal) ligament, and its sides externally by the sar- torious, internally by the adductor longus. Its floor is formed by the iliacus, psoas, pec- tineus and adductor longus muscles, from without inward. It is bisected vertically by the femoral vessels, which extend from the middle of its base to its apex. It also contains the anterior crural nerve (n. femoralis) external to the vessels, together with lymphatic vessels and glands and some fat. Hunter's Canal (Canalis Adductorius) is the interval between the ad- ductor magnus and the vastus internus (m. vastus medialis) in the middle third of the thigh, extending from the apex of Scarpa's triangle to the femoral opening in the adductor magnus muscle, and lying beneath the ARTERIES OF THE LEG 143 sartorius. It contains the femoral vessels in their sheath, the vein lying behind and to the outer side of the artery; also the long saphenous nerve, at first external to and then in front of the vessels. The Popliteal Artery (a. Poplitea), the continuation of the femoral, extends from the opening in the adductor magnus, passing behind the knee-joint, to the lower border of the popliteus muscle, where it divides into the Anterior and Posterior Tibial Arteries. It is crossed by the popliteal vein and the internal popliteal nerve (n. tibialis), and gives off the follow- ing-named branches, which are distributed around the knee-joint in a free anastomosis; except the Azygos Articular, which pierces the posterior ligament of the joint to reach the internal ligaments and the synovial membrane. Branches are named as follows: i Superior Muscular Branches. Inferior Muscular, or Sural. Cutaneous Branches. Superior Articular, internal (a. genu superior medialis) and external (a. genu superior lateralis). Azygos Articular (a. genu media). Inferior Articular, internal (a. genu inferior medialis) and external (a. genu inferior lateralis). The Anterior Tibial Artery (a. Tibialis anterior) extends from the bifurcation of the popliteal to the front of the ankle-joint, where it be- comes the Dorsal is Pedis. It passes between the two heads of the tibialis posticus (m. tibialis posterior) over the upper edge of the interosseous membrane and along its anterior surface, resting on the tibia for its lower third. It is accompanied by the anterior tibial nerve (n. peronaeus pro- fundus) close to it externally, and is crossed below by the tendon of the extensor proprius hallucis. Its branches are named the Posterior Recurrent Tibial (a. recurrens tibialis posterior). Superior Fibular. Anterior Recurrent Tibial (a. recurrens tibialis anterior). ^ Muscular (rami musculares). Internal Malleolar (a. malleolaris anterior medialis). External Malleolar (a. malleolaris anterior lateralis). The Dorsalis Pedis Artery, the continuation of the anterior tibial, ex- tends from the front of the ankle-joint along the tibial side of the foot, to the back part of the ist intermetatarsal space, where it terminates in the Dorsalis Hallucis and the Communicating (ramus plantaris profundus). The anterior tibial nerve lies close to its outer side. Its branches are as follows: 144 HUMAN ANATOMY * Tarsal (a. tarsalis lateralis), passing outward along the tarsus. -) Metatarsal (a. arcuata), giving off 3 Interosseous (aa. metatarseae dorsales), and the 7 Digital branched (aa. digitales dorsales). Dorsalis Hallucis, to the great toe and the inner side of the second toe by its 3 digital branches. ; Communicating (ramus plantaris profundus), dips down into the sole of the foot in the ist interosseous space of the metatarsus, to inosculate with the external plantar, completing the plantar arch. Its plantar digital branch, the arteria magna hallucis, supplies the inner side of the great toe and the adjacent sides of the great and second toes, on their plantar surfaces. The Posterior Tibial Artery (A. Tibialis Posterior) is a large vessel, extending from the bifurcation of the popliteal along the back of the tibia to the fossa below the inner malleolus, where it divides into the Internal (medial) and External (lateral) Plantar. The posterior tibial nerve crosses it a short way below its origin and then lies near its outer side for the rest of its course. Its branches are as follows: / Peroneal (a. peronaea) , along the fibular side, giving off the following : Muscular (rami musculares). Nutrient of the fibula (a. nutrica fibulae). Anterior Peroneal (ramus perforans). Communicating (ramus communicans). Posterior Peroneal. External Calcanean (ramus calcaneus lateralis). Nutrient of the Tibia (a. nutrica tibiae), the largest nutrient artery of bone in the body. Muscular Branches (rami musculares), to the posterior muscles of the leg. ' Communicating (ramus communicans), to join a similar branch of the peroneal artery. Internal Calcanean Branches (rami calcanei mediales), to the heel and sole of the foot. Internal Malleolar (a. malleolaris posterior medialis). The Internal Plantar Artery (a. plantaris medialis), the smallest of the terminal branches of the posterior tibial, passes along the inner side of the foot and great toe. The External Plantar Artery (a. plantaris lateralis) sweeps across the plantar aspect of the foot in a curve, the convexity of which is directed outward and forward; and at the interval between the bases of the ist and 2d metatarsal bones it inosculates with the communicating branch IMPORTANT ARTERIAL ANASTOMOSES 145 frortl the dorsalis pedis, completing the Plantar Arch (arcus plantaris") or the Stirrup Anastomosis. It gives off numerous muscular branches, and the Posterior Perforating (rami perforantes posteriores), 3 small branches which ascend through the 3 outer interosseous spaces between the heads of the dorsal interossei muscles. Digital Branches (aa. digitales plantares), 4, supplying the sides of the 3 outer toes and the outer side of the 2d toe; its inner side, together with the great toe, being supplied by the communicating branch of the dorsalis pedis. ARTERIAL ANASTOMOSES The Anastomosis around the Shoulder- joint is formed by the following 8 arteries, viz. Posterior Scapular (ramus descendens a. trans versa colli). Subscapular (a. circumflexa scapulae) br. of axillary. Dorsalis Scapula (a. circumflexa scapulae) br. of subscapular. Infraspinous, br. of dorsalis scapulae. S upr as ca pular (a. transversa scapulae), br. of thyroid axis. Ant. Circumflex (a. circumflexa humeri anterior), br. of axillary. Post. Circumflex (a. circumflexa humeri posterior), br. of axillary. Acromial, br. of acromial thoracic. The Anastomosis around the Elbow-joint is formed by the Superior Profunda, (a. profunda brachii), br. of brachial. Posterior Articular, br. of superior profunda. Radial Recurrent, br. of radial. Interosseous Recurrent, br. of posterior interosseous. Inferior Profunda (a. collateralis ulnaris superior), br. of brachial. Anastomotica Magna (a. collateralis ulnaris inferior), br. of brachial. A nterior Ulnar Recurrent, br. of ulnar. Posterior Ulnar Recurrent, br. of ulnar. The Anastomotica Magna is the vessel most engaged in this anastomosis, the only part in which it is not employed being that in front of the ex- ternal condyle of the humerus. The Anastomosis around the Hip-joint is formed by the Gluteal (superior gluteal), Ilio-lumbar, and Circumflex Iliac, with the Ex- ternal Circumflex. Obturator and Sciatic (inferior gluteal), with the Internal Circumflex. Comes Nervi Ischiadici, with the Perforating branches of the Profunda. 10 146 HUMAN ANATOMY The Arteries Anastomosing around the Knee-joint are the Descending, br. of ext. circumflex. Sup. Int. Articular, br. of popliteal. Anastomotica Magna (a. genu su- Inf. Ext. Articular, br. of popliteal. prema), br. of femoral. Inf. Int. Articular, br. of popliteal. Inferior Perforating, br. of profunda. Ant. Recurent, br. of anterior tibial. Superior Ext. Articular, br. of popliteal. This anastomosis is sometimes called the deep plexus of the Circum- patellar Anastomosis; a superficial arterial plexus being situated between the fascia and skin around the patella. .The Crucial Anastomosis is formed behind the junction of the neck of the femur with the great trochanter, between the adductor magnus and quadratus femoris muscles, by the anastomosis of the following-named arteries: Transverse branch of Ext. Circumflex (from profunda), externally. Terminal branch of Int. Circumflex (from profunda), internally. First Perforating branch of the Profunda Femoris, below. Anastomotic branch of the Sciatic (from. int. iliac), above. The Longest Anastomosis in the Body is that between the subclavian and the external iliac by the anastomosis of the Superior Epigastric, br. of the internal mammary, with the Deep Epigastric, br. of the external iliac. [The circle of Willis has been described on page 128; the palmar and plantar arches on pages 135 and 145 respectively; and the anastomosis of the membrana tympani on page 298.] The Collateral Circulation, after Ligature of the Common Carotid Artery, is established by the free communication existing between the carotid arteries of opposite sides both within and without the cranium, and by enlargement of the branches of the subclavian artery on the ligated side. Outside the skull the principal communication takes place by the following anastomoses: Superior Thyroid, br. of the external carotid, with the Inferior Thyroid, br. of the thyroid axis (from the subclavian). Arteria Princeps Cervicis, br. of the occipital (from the external carotid), with the Vertebral, br. of the subclavian, and the Profunda Cervicis, br. of the superior intercostal (from the subclavian). After Ligature of the Subclavian in its first part, the Collateral Circu- lation is carried on by the following anastomoses: i, that between the Superior and Inferior Thyroid arteries (see above); 2, that between the two Vertebrals; 3, that between the Internal Mammary, the Deep Epigastric and the Aortic Intercostals; 4, the Superior Intercostal with the Aortic ARTERIAL SYSTEM TABULATED 147 Intercoslals; 5, the Profunda Cervicis with the Princeps Cervicis; 6, the Scapular branches of the thyroid axis with branches of the Axillary; 7, the Thoracic branches of the Axillary with the Aortic Intercostals. TABLES AND PLATES OF THE ARTERIAL SYSTEM NOTE. The arteries in the following plates should be colored red, by painting them over with ordinary crimson ink, or water-color paint, using a fine camel's- hair brush for the purpose. Figures in parentheses in these tables refer to the number of another table, thus Ext. Carotid (3) means Table No. 3 of the External Carotid Artery. THE ARTERIAL SYSTEM i. .1 Numerous branches through- Pulmonary Artery. ^ p^Zv' A R T Pat 3 f Ut " PU ' m nary (Plate i.) 3) J carrying venous blood. HUMAN ANATOMY THE ARTERIAL SYSTEM. Continued R. CORONARY 1 2. Arch of Aorta. (Plate i.) L. CORONARY J INNOMINATE to the muscular tissue of the heart. R. COMMON CAROTID R. SUBCLAVIAN [ becomes Axillary (8) Ext. Carotid (3). Int. Carotid (4). Vertebral (5). Thyroid Axis (6). Int. Mammary (7). Sup. Intercostal. L. COMMON CAROTID, . . Same as R. Common Carotid. L. SUBCLAVIAN, . . Same as R., continuing as Axillary (8). External Carotid. (Plate i.) Superior Thyroid. Lingual Submental Facial or Ex- ternal Max- illary. Muscular and Glandular branches. Hyoid, along lower border of os hyoides. Superf. Descending, crosses Com. Carotid. Sup. Laryngeal, to larynx and epiglottis. Crico-thyroid, crosses Crico-thyroid membrane. ( Hyoid, along upper border of bone. I Dorsalis Linguae, to tongue, tonsil, palate, etc. I Sublingual, to gland, mouth, gums. ( Ranine, under surface of tongue, to tip. Inf. (Asc.) Palatine, to soft palate and tonsil. Tonsillar, to tonsil and root of tongue. Submandibular, to gland, skin, muscles. Superf. Br. anas. inf. labial. Deep Br. to the lip. Muscular, to pterygoid, masseter, buccinator. Inf. Labial, anas, with br. of ?th and sth N. Inf. Coronary or labial, anas, with br. of inf. dental art. Sup. Coronary, f Art. of Septum Nasi. or labial. \ Br. to ala of nose. Lateralis Nasi, to ala and dorsum of nose. A ngular, termination of facial trunk. Muscular, to digastric, stylo-hyoid, etc. Sterno-mastoid, to that muscle. Auricular, to back part of concha. Occipital ( Inf. Meningeal, to dura mater in post, fossa. Superf. Br. anas, superf. cervical, of trans, colli. Princeps Cervicis \ Deep Br. anas, vertebral, and deep cerv. br of sup. intercostal. ARTERIES OF THE HEAD AND NECK. Plate ' i GOHTINUED Potter, del.. T4Q 150 HUMAN ANATOMY THE ARTERIAL SYSTEM. Continued Post. A uricular. . Branches (small), to muscles and glands. Stylo-mastoid, to tympanum, mastoid cells, etc. Auricular, to cartilage of ear. Mastoid, to scalp above ear. j Prevertebral, brs. to muscles and nerves. Ascending I Tympanic, to inner wall of tympanum. Pharyngeal. ] Meningeal Branches, to dura mater. [ Pharyngeal Branches, 3 or 4 in number. 3- Superficial External Temporal. Carotid. (Contin- ued.) INTERNAL i. MAXILLARY. Divisions: i. Maxillary. 2. Pterygoid. 3. Spheno- maxillary. Transverse Facial, lies on the masseter. Anterior Auricular Branches, to pinna, etc. Middle Temporal, supplies that muscle. Anterior Temporal, to the forehead. Posterior Temporal, along side of head. _, . / to memb. tympani, anas, with Stylo- j. ympanic\ . , ,. __. -. ( mastoid and Vidian arteries. Deep Auricular, to outer surface of the mem- brana tympani. Mid. Meningeal, to dura and cranial bones. Small or Accessory Meningeal, to dura and Gas- serian gang. Inferior Dental L * n * Ual ' to m ' m ' of mouth " I Mylo-hyoid, in that groove. M^Tl l T ern " nal Brs - Mandibular j Deep Temporal, 2, under temporal muscle. I Pterygoid Brs., to pterygoid muscles. I Masseteric to deep surface of masseter. ( Buccal, a small br. to buccinator. A Iveolar Dental, to molars, bicuspids. Branches, to antrum, gums, etc. (several brs. to the orbit. Ant. Dental, to front teeth, an- trum. Post. (Desc.) Palatine, to palate, glands, etc. Vidian, to Eustachian tube and pharynx. Ptery go- palatine, to Eustach. tube and pharynx. Artery of Septum, to septum. External Branches 3, to the nares, antrum, ethmoid and sphenoid cells. Spheno- palatine ARTERIAL SYSTEM TABULATED THE ARTERIAL SYSTEM. Continued Tympanic, to tympanum by foramen in carotid canal. Arteria Receptaculi (several), in cavernous sinus. Ant. Meningeal, to dura mater of ant. fossa. r Lacrimal, to that gland, lid, etc. Supraorbital, the largest sub-branch. . , ,/ Meningeal, to dura. Post - Eihmotdal \NasalBrs., to nose. i. Ant. Ethmoidal, has same branches. Sup. Palpebral, arch on margin of lid. OPHTHALMIC. Inf. Palpebral, margin of lower lid. Groups: Frontal, to muscles, skin 1 i. Orbital. / Transverse, [Terminal Branches. 4. 2. Ocular. * \DorsolisNasi. J Internal (Plate 4. Carotid. Pig. 2.) Art. Centralis Retina, to the retina. (Plate i.) ( Ant. Ciliary, to the iris. Muscular \ Superior, to ocular muscles. 2. ' [ Inferior, to ocular muscles. Short Ciliary, 6 to 12, around optic n. Long Ciliary 2, to circles on iris. A nlerior Cerebral ( Ant. Communicating, 2 lines long. ' ' \ Ganglionic and Frontal branches. Middle Cerebral / Ganglionic, Frontal, Parietal, and Parieto- \ temporal branches. Posterior Communicating, anas, with Post. Cerebral of Basilar, to form the Circle of Willis. Anterior Choroid, to the choroid plexus, etc. BASILAR Post. Cerebral Post. Commun. THE CIRCLE OF WILLIS I ^ TERNAL CAROTID. Ant. Cerebral ral \ Post. Cerebral Post. Commun. Ant ' Cerebral Ant. Commun. 152 HUMAN ANATOMY THE ARTERIAL SYSTEM. Continued s. VERTEBRAL (Plate i.) Lateral Spinal Anterior Spinal Br. to spinal cord and membranes. Br. to bodies of Vertebras posteriorly. Muscular Branches, to deep cervical muscles. Post. Meningeal, ramify between dura mater and skull. joins its fellow to form Ant. Median Artery of the spinal cord. Posterior Spinal, to spinal cord and membranes, laterally. / Internal \ to cerebellum, and choroid plexus Post. Inf. Cerebellar s _ , > ,, .v-ir^-i ( External J of the 4th Ventricle. Bulbar, minute branches to the medulla oblongata. / to Pons Varolii, etc. Transverse s T . ,. , . ( Int. Auditory, to that canal. , /to the cerebellum, anas, with post. Ant. Inf. Cerebellar \ . , ... f ,, . , . ( inf. cerebellar of Vertebral. Superior Cerebellar, to pia mater, pineal gland, etc. Post. Choroid, to choroid plexus Ganglionic, to post, lobes. Posterior Cerebral { Ant. Temporal, n m I terminal Post. Temporal, } , _ . . . branches. Occipital, Inf. Laryngeal, to post, muscles of larynx. Tracheal Brs. to trachea, anas. Bronchial. (Esophageal Brs. to oesophagus. Ascending Cervical, to muscles, spinal cord. Muscular, to muscles of hyoid bone and of the pharynx. Superficial Cervical, beneath Trapezius. Posterior Scapular, along post, border. Supra-acromial, anas. Acromial Thoracic. Supra-scapular. . . . I Supra-sternal, to skin of the chest. 1 Muscular, to sterno-mastoid, etc. I Nutrient, to the clavicle. 6. THYROID Axis. (Plate i.) Inferior Thyroid. Transversalis Colli. Comes Nervi Phrenici (Superior Phrenic), to Diaphragm. Mediastinal Brs. to tissue and glands, ant. mediastinum. Pericardiac Brs. to upper part of pericardium. Sternal Brs. to sternum and Triangularis sterni. INTERNAL Anterior Intercostals, to 5 or 6 upper intercostal spaces. MAMMARY. Perforating, to Pectoralis major, mammary gland, etc. (Plate i.) *..,..! ^i.^ a ^;^ / Ant. Intercostals, to lower intercostal spaces. Brs. to lower pericardium, Diaphragm, etc. f anas, with deep Epigastric of Ext. Iliac. \ supplies abdominal muscles and skin. Musculo-phrenic Superior Epigastric ARTERIAL SYSTEM TABULATED Axillary. (Plate 2.) i from ist part, i " 2d " 3 " 3d " THE ARTERIAL SYSTEM. Continued j Superior Thoracic, to Pectoral muscles and wall of thorax. ( Brs. to Pectorals and Deltoid. [ Acromio Thoracic -| Descending, to both these muscles. [ Clavicular, to the Subclavius. ( Alar Thoracic, to glands of axilla. \ Long Thoracic, to Serratus, Pectorals and glands. Subscapular A nterior Circumflex [ Subscapular. Dorsalis Scapulce \ Infra-spinous. { Median. Main trunk to inf. angle of the scapula. f around neck of humerus, to Deltoid. 1 Br. to shoulder-joint. Posterior Circumflex \ around neck of humerus, to Deltoid \ muscle and shoulder-joint. Becomes BRACHIAL (10), at lower margin of tendon of the Teres major muscle. (Post. Articular, to elbow-joint anastomosis and inner side of arm. Main trunk, in spiral groove of the hu, merus, to Deltoid, Triceps, etc. 9. Nutrient, to nutrient canal of the humerus. Brachial. Inferior Profunda (sup. uln. collat.) to the elbow-joint anastomosis. (Plate 2.) Anastomotica Magna (inf. uln. collat.), transversely inward on Brachialis anticus muscles to the elbow, where it anastomoses with several arteries. Muscular, 3 or 4, to muscles in course of artery. Bifurcates into RADIAL (10) and ULNAR (n). ( Radial Recurrent, anas, branches of Sup. profunda. J Muscular Brs. to muscles on radial side of arm. Ant. Carpal, to wrist-joints, anas. Ant. Carpal of Ulnar. Superficialis Voice, to muscles of the thumb. Post. Carpal to wrist-joints, anas. Post. Carpal of Ulnar. Dorsal Interosseous, for 3d and 4th spaces. Metacarpal, is the First Dorsal Interosseous Branch. Dor sales Pollicis 2, laterally on dorsum of thumb. Dorsalis Indicts, on radial side of index dorsum. 10. Radial. (Plate 2.) 2. 1. In forearm. 2. In wrist. 3. In hand. Princeps Pollicis, 2 Brs. forming arch on last phalanx. Radialis Indicts, along radial side of index ringer. Perforating 3 between heads of last Dorsal Interossei. / 3 or 4 along Interossei muscles, given Palmar Interossea{ - . %> 1 \ off by Deep Palmar Arch. Palmar Recurrent, to the carpal articulations. Forms DEEP PALMAR ARCH in the hand, completed by inosculation with the Deep Palmar (Communicating) from the Ulnar Artery. 154 HUMAN ANATOMY THE ARTERIAL SYSTEM. Continued Anterior Ulnar Recurrent, ascends in front of inner condyle Posterior Ulnar Recurrent, ascends behind inner condyle. pierces Interosseous mem- brane, descending to back of wrist. Anterior Muscular Branches. Interosseous Nutrient, of both bones. Br. on Pronator quadratus. Interosseous \ [ Median, along median n. 11. Ulnar. (Plate 2.) 1. In forearm. 2. In wrist. 3. In hand. 3. Posterior Interosseous to back of wrist. Interosseous Recurrent, to elbow-joint anastomosis. Muscular, to muscles on ulnar side of arm. Anterior Carpal, to joints, anas. Carpal of Radial. | to joints of wrist, anas. Carpal of Radial. Posterior Carpal j forming the Post. Carpal Arch. [ Metacarpal, to little finger. !anas. with termination of Radial Artery, completing the Deep Palmar Arch. from convexity of Superf. Palmar Arch, to the sides of the fingers, except the radial side of the index finger and thumb (supplied from the radial). Digital 4 Forms SUPERFICIAL PALMAR ARCH in palm of hand, by inosculating with a branch from the Radialis Indicis of the Radial Artery. Pericardiac Branches, distributed to the pericardium. Bronchial Arteries 3 nutrient vessels of the lungs. 12. (Esophageal, 4 or 5, anas. brs. Inf. Thyroid, Phrenic, Gastric. Thoracic ^ Posterior Mediastinal, (several) to glands, etc., in mediastinum. Aorta. I Posterior (Dorsal), to muscles of back. (Plate 3). Intercostals. I Spinal, to the spinal cord and its membranes. 1 8. | Collateral Intercostal, along upper border of the 1 next rib below. ARTERIES OF THE UPPER EXTREMITY. \ Potter del 156 HUMAN ANATOMY THE ARTERIAL SYSTEM. Continued l Internal, to front of thorax and Diaphragm. Phrenic | External, to side of thorax. to cardiac orifice of stomach, cardiac end. - rin rfW f t then along lesser curvature to pylorus, where it anas, with Pyloric Br. of Hepatic Art. Pyloric, to pylorus, anas. Gastric Art. f Gastro-epiploica \ Dextra Gastro-duodenalis < D * , Pancreatico-duo- CcELIAC { denalis Superior. Axis. Hepatic TT ) to right lobe. Right Hepatic, < -, \ Cystic, to gall-bladder. Left Hepatic, to left lobe of liver. Pancreaticce Parva \ > to the pancreas. Pancreatic Magna ) Splenic Gastric Vasa Brevia, 5 to 7, to the greater or curvature of stomach. Lienal Gastro-epiploica Sinistra, along the greater curvature, from left to right. Terminal Brs. enter hilum of Spleen. 13- Inferior Pancreatico-duodenal, to those organs. Abdominal Vasa Intestini Tenuis 12 to 15, form arches in mesen- Aorta. tery, in several series, from terminal arches branches (Plate 3.) ramify on intestines. Superior Mesenteric. / Inferior, anas. Vasa intes. ten. Ileo-colic < . .. , , ^ Superior, anas. Colica dextra. / Desc. Br. \ Arches branching to ascend- Cohca Dextra \ . _ > . 1 Asc. Br. ) ing colon. / Right \ Arches, branching to trans- Colica Media < _ * > . \ Left ) verse colon. Supra-renal, to supra-renal capsule. . / Brs. to substance of kidney. Renal \ { Small Brs. to capsule, ureter, etc. Spermatic (or Ovarian) to testes or ovaries, uterus, etc. Inferior (Asc. \ Arches branching to descend- Colica Sinistra < ^ V [ Desc. J ing colon. Mesenteric. Sigmoid, across Psoas to that flexure of colon. (Plate A } ( KY tn ricrlit 1 ^i late 4v Sup. Hemorrhoidal, < ' ^ > side of rectum. to muscles, etc., of back. Spinal, to canal s ' \ Arches. Abdominal, between abdominal muscles. Middle Sacral, to coccyx, anas. Lateral Sacral. / RIGHT COM. ILIAC, R. Int. and Ext. Iliac (14, 15). Bifu.rc3.t6S s Bifurcation occurs at 4th Lumbar Vertebra, opposite Umbilicus. BRANCHES OF THE AORTA Plate 3. Potter.del 157 HUMAN ANATOMY THE ARTERIAL SYSTEM. Continued Superior Vesical Obturator. \ Art. of Vas Defer ens, to that organ. \ Middle Vesical, to base of bladder. 14 a. Internal Iliac or Uterine, < Hypogastric. , I ANTERIOR Vaginal, analog TRUNK. (Plate 4.) Internal Pudic, or Pudendal. Sciatic or Inf. Gluteal. Iliac, to iliac bone and Iliacus muscle. Vesical, backward to the bladder. Pubic, on the back of the pubic bone. Internal, along inner margin obturator foramen. External / outer mar g m obturator foramen. \ Br. to hip-joint by cotyloid notch. Inferior Vesical, to base of bladder, prostate gland, etc. Middle Hemorrhoidal, to anus, anas, other hem. arteries, f Br. to the bladder. ] Br. to the ureter. Cervical, to neck of uterus. Azygos, of the vagina. In the female. Inferior Hemorrhoidal, 2 or 3 to the anus. Superficial Perinaal, to the scrotum, etc. Transverse Perinceal, to muscle of same name. Artery of the Bulb, large but very short. Artery of the Corpus Cavernosum, to that body. Dorsal Artery of the Penis, or clitoris. Muscular Brs. within the pelvis. Hemorrhoidal Brs. to the rectum. Vesical Brs. to base and neck of bladder. Coccygeal, to back of coccyx. Inf. Gluteal 3 or 4, to Gluteus maximus. Comes Nervi Ischiadici, along sciatic nerve. Muscular Brs. to back of hip. Anastomotic, to the crucial anastomosis. Articular Brs. to capsule of the hip- joint. ARTERIES or THE PELVIS AND THIGH. Plate 4 FIG. 2 BRANCHES Ot OPHTHALMIC ARTtRY. Potter .del 159 i6o HUMAN ANATOMY THE ARTERIAL SYSTEM. Continued 14 b. Internal Iliac or Hypogastric. POSTERIOR TRUNK. (Plate 4.) Ilio-lumbar, Iliac, to Iliacus internus and Ilium. / to Psoas and Quad, lumborum. Lumbar, \ Spinal Br. to cord and membranes. Superior Lateral Sacral, to dorsum of sacrum. Inferior Lateral Sacral, to front of sacrum, and coccyx, anas with Sacra media, etc. Gluteal, Muscular Brs. within the pelvis. Nutrient, of the Ilium. Superficial, to Gluteus maximus, etc. Superior, to ant. sup. spine of Ilium. Inferior, to glutei and hip-joint. Deep Muscular Brs. several, to Psoas and glands. 15. [ Cremasteric, to cremaster muscle. External Iliac. Epigastric, -I Pubic, to inner side of femoral ring. (Plate 4.) ( Muscular, to abdominal muscles and skin. . ,, rf . \ between Transversalis and Int. oblique. Circumflex Iliac, < _ . . T , , _ . . ( Br. anas, with Lumbar and Epigastric. Becomes FEMORAL (16) at Poupart's Ligament. Superficial Epigastric, in superf. fascia, to umbilicus. Superf. Circumflex Iliac, outward to iliac crest. Superf. Ext. Pudic (pudendal) , inward to skin of penis, scrotum etc. Deep Ext. Pudic (pudendal), inward to skin of perineum, etc. Asc. Brs. outer side of hip. Ext. Circumflex, { Transverse, to back of hip. Descending, as far as knee. 16. Femoral. (Plate 4.) Profunda Femoris, I Ascending, to Adductors, etc. Int. Circumflex, -j Descending, to Adductors, etc. [ Articular, to head of femur, f Superior, pierces Adductor magnus. Perforating,^, Middle, < Nutrient of Femur. { Inferior, pierces Adductor magnus. Muscular 2 to 7, along artery, to Sartorius, Vastus internus, etc. j Superficial Br. to integument. Anastomotica Magna,} Deep Br. to inner side of knee and joint, or Genu Suprema. anas, with Sup. Articulars and Recur- [ rent br. of Anterior Tibial. Becomes POPLITEAL (17), at opening in Adductor magnus. ARTERIES OF THE LEG. | Plate 5 Potter.dei II 161 HUMAN ANATOMY THE ARTERIAL SYSTEM. Continued 17- Popliteal. (Plate 4.) Muscular / Superior Brs. to Vastus ext. and flexor muscles. \ Inferior or Sural 2, to Gastrocnemius and Plantaris. Cutaneous Brs. to integument of calf. Superior Internal Articular, to Vastus int. and joint. Superior External Articular, to Vastus ext. and joint. Azygos Articular, to synovial membrane of joint. Inferior Internal Articular, to head of tibia and joint. Inferior External Articular, to front of knee-joint. . , / ANTERIOR TIBIAL (i 8) \at lower border of Popliteus Bifurcates into | p OSTERIOR TlBIAL (lp) | musde Post. Recurrent Tibial, to the Popliteus muscle. Superior Fibular, to the Soleus and Peroneus longus. Ant. Recurrent Tibial, to the knee-joint anastomosis. 18. Muscular Brs. numerous to muscles of leg. Anterior I Internal Malleolar, beneath tendon of Tibialis anticus. Tibial. j External Malleolar, to outer ankle. (Plate 5.) Tar sal, to tarsal joints and Ext. brev. digit. 7 Digital branches. Dorsalis Pedis Metatarsal, < 3 Interossea, Dorsalis Hallucis Communicating, Ends in the PLANTAR ARCH. Brs. to great toe. Br. to inner side of 2d toe. anas. Ext. Plantar (Arch). 2 Digital Brs. Peroneal, Anterior Peroneal, pierces interosseous membrane. Posterior Peroneal, to the os calcis. Nutrient* Artery of the fibula. Muscular, several brs. in its course. / joins similar branch of the poste- Commumcating { \ nor Tibial. Ext. Calcanean, the terminal branches. 19. Muscular, to Soleus, etc., on back of leg. Posterior I Nutrient of Tibia, the largest nutrient artery of bone. Tibial. Communicating Br. to a similar br. of the Peroneal. (Plate 5.) Internal Calcanean Brs. to the heel, and sole of foot. Internal Plantar, along inner side of foot and great toe. ( Brs. to muscles, fascia and skin. Posterior Perforating 3 Branches. 4 Digital, { Ant. Perforating Branches. k I Ends as the PLANTAR ARCH, anas, with Commun. Br. of Dorsalis Pedis. External Plantar, THE VEINS 163 THE VEINS Veins are vessels which return the blood from the capillaries of the body to the heart. Their walls, like those of the arteries, are composed of 3 coats an internal serous (tunica intima), a middle muscular (tunica media), and an external one (tunica externa or adventitia) of connective tissue. Their middle coat is weaker than that of the arteries, so that they do not stand open when divided, as the arteries do. They all carry carbon- ized (venous) blood, except the pulmonary veins, which bring oxygenated blood to the left side of the heart. The deep veins accompany the arteries, generally in the same sheath, and are given the same names. The second- ary arteries, as the radial, ulnar, brachial, etc., have each two veins, called Vena Comites. The superficial veins are usually unaccompanied by arteries, and lie, as a rule, between the layers of the superficial fascia, terminating in the deep veins. Many veins are so irregular in their origin that they cannot be accurately described; they all anastomose with each other much more freely than do the arteries. Venous Sinuses are venous channels, differing from veins in structure, but answering the same purpose. Those of the cranium are formed by the separation of the layers of the dura mater. The Veins are divided into the Pulmonary, Systemic, and Portal Sys- tems; the latter being an appendage of the systemic, its capillaries ramify- ing in the liver. Veins having no valves are the venae cavae, hepatic, portal, renal, uterine, ovarian, cerebral, spinal, pulmonary, umbilical, and the very small veins. The Pulmonary Veins alone of the veins carry arterial blood, beginning in the capillaries of the lungs, forming a single trunk for each lobule, which, uniting into a single trunk for each lobe, form two main trunks from each lung which open separately into the left auricle. Sometimes the three lobe- trunks of the right lung remain separate to their termination in the auricle, and not infrequently a common opening serves for the two left pulmonary veins. VEINS OF THE HEAD AND NECK Exterior Veins of the Head and Face are as follows, Frontal Vein, begins on the anterior part of the skull by a venous plexus converging to a single trunk near the middle line of the forehead, which joins the supra-orbital vein at the root of the nose to form the angular vein. Supra-orbital Vein, begins on the forehead and joins the frontal (see above) to form the angular vein. 1 64 HUMAN ANATOMY Angular Vein, formed as described above, runs downward and outward on the side of the root of the nose, communicates with the ophthalmic vein, and ends in the Facial Vein, a direct continuation of the angular, begins at the side of the root of the nose, descends obliquely across the masseter muscle and over the body of the lower jaw to unite with the ant. division of the temporo-maxillary to form the common facial vein, which enters the internal jugular. Temporal Vein, begins on the vertex and side of the skull, by anterior and posterior branches which unite and are joined by the middle temporal above the zygoma to form the trunk, which descends through the parotid gland and unites with the internal maxillary to form the temporo- maxillary vein. Internal Maxillary Vein, is formed by branches corresponding to those of the internal maxillary artery, forming the pterygoid plexus. The trunk passes backward behind the neck of the lower jaw and unites with the temporal to form the Temporo-maxillary Vein, descends in the parotid gland and divides into an anterior branch, which joins the facial, and a posterior branch which is joined by the posterior auricular and becomes the external jugular. Posterior Auricular Vein, begins on the side of the head, descends behind the external ear and joins the posterior division of the temporo-maxillary, forming the external jugular. Occipital Veins, begin in a plexus at the back of the head and terminate in the internal jugular. Veins of the Diploe and Interior of the Cranium, - Veins of the Diploe, a number of tortuous canals lying between the two tables of the skull, and divided into frontal (empties into supra-orbital), anterior temporal (empties into either the spheno-parietal sinus or ante- rior deep temporal), posterior temporal and occipital branches which empty into either the occipital vein or the lateral sinus (sinus transversus) .^ Cerebral Veins, have no muscular coat and no valves. They are divided into superficial and deep sets. The deep cerebral are formed by the union of the vena cor ports striati (vena terminalis) and the choroid vein on either side, and receive the basilar vein, forming the great cerebral vein (veins of Galen). Ccrcbcllar Veins, on the surface of the cerebellum, are disposed in 3 sets, superior, inferior and lateral. Superior Longitudinal Sinus (sinus longitudinalis vel sinus sagittalis DURAL SINUSES 165 superior), occupies the attached margin of the falx cerebri, begins at the foramen caecum, and ends in the torcular Herophili (confluens sinuum), or confluence of the sinuses. Inferior. Longitudinal Sinus (sinus sagittalis inferior), in the free margin of the falx cerebri posteriorly, terminates in the Straight Sinus (sinus rectus or tentorial sinus), at the junction of the falx cerebri with the tentorium, terminates in the lateral sinus (sinus trans- versus) of the opposite side. Lateral Sinuses (sinus transversi), in the attached margin of the ten- torium cerebelli, terminate in the internal jugular vein. ,~" Occipital Sinuses (sinus occipital es), in the attached margin of the falx cerebri, terminate in the torcular Herophili. Cavernous Sinuses (sinus cavernosi), one on each side of the sella turcica, receive the ophthalmic vein and open behind into the petrosal sinuses. Circular Sinus (sinus circularis), is formed by two transverse vessels, the anterior and posterior intercavernous sinuses, connecting the two cavernous sinuses, and forming a venous circle around the pituitary body. Superior Petrosal Sinus, connects together the cavernous and lateral sinuses of each side. Inferior Petrosal Sinus, begins at the termination of the cavernous sinus, and joins the lateral sinus to form the internal jugular vein. Transverse or Basilar Sinus (plexus basilaris], connects the two inferior petrosal sinuses over the basilar process of the occipital bone. Emissary Veins (emissaria), pass through apertures in the cranial wall from the sinuses inside to the veins outside; the principal ones being 8 in number. 1. Frontal through foramen caecum. 2. Parietal (two) through parietal foramina. .3. Occipital through foramen in occipital protuberance (occasional). 4. Post-condylar (condyloid) through foramen behind occipital condyle. 5. Emissary plexus through foramen ovale. 6. Vein of Vesalius through foramen of Vesalius. 7. Plexus through internal carotid canal. 8. Plexus through anterior condylar canal (hypoglossal canal). Veins of the Neck, draining those above-mentioned, are the External Jugular (6), terminating in the subclavian vein (4). Posterior External Jugular, opens into the external jugular. Anterior Jugular (7), enters the subclavian vein near the external jugular. Internal Jugular (5), formed by the junction of the two last-named i66 HUMAN ANATOMY sinuses at the jugular foramen, and uniting with the subclavian vein to form the innominate, at the root of the neck. In its course it receives the facial, lingual, pharyngeal, superior and middle thyroid veins, and the occipital. Vertebral, descends the foramina in the transverse processes of the cervical vertebrae, and empties into the innominate vein. In its course it receives the anterior and posterior vertebral and many other veins. VEINS OF THE UPPER EXTREMITY Veins of the Hand, Forearm, and Arm are in two sets, superficial and deep. The superficial set lies in the superficial fascia, begin in the hand by external and internal dorsal and superficial galmar veins, and are continued as follows, the basilic continuing as the axillary, which receives the cephalic just below the clavicle. Radial (cephalic B.N.A.) ./i^.^ \ f . . > Cephalic Median Cephalic } Profunda Median Basilic Dorsal. Palmar. Dorsal. Median (median cubital) I Anat. Ulnar ! (basilic B.N.A. | Post. Ulnar { (basilic B.N.A. Common Ulnar (basilic B.N.A.) Basilic AXIL- LARY VEIN. The deep veins follow the arteries, generally as venae comites, beginning in the hand as Digital, Interosseous and Palmar veins, they unite in the Deep Radial and Deep Ulnar, which join to form the Vena Comites of the brachial artery at the bend of the elbow. The Brachial Veins lie one on each side of the brachial artery and join the Axillary Vein. These deep veins have numerous anastomoses, not only with each other but also with the superficial ones. Axillary Vein (v. axillaris), the continuation of the basilic, lies on the inside of the artery and terminates beneath the clavicle at the outer border of the ist rib, where it becomes the Subclavian Vein (v. subclavia), the continuation of the axillary, extends from the outer border of the ist rib to the inner end of the clavicle, where it unites with the internal jugular to form the in- nominate vein. At the angle of junction enters the thoracic duct on the left side of the body and the right lymphatic duct on the right side. In its course it receives the external and anterior jugular veins and a branch from the cephalic. The Innominate Vein (vena anonyma) is formed by the union of the VEINS OF THE THORAX i6 7 subclavian and the internal jugular. The two innominates unite just below the ist costal cartilage to form the superior vena cava. The Right Innominate (v. anonyma dextra) (3) is about i inch long, and receives, besides its FIG. 69. constituent branches, the right internal mam- mary, right inferior thyroid, and right superior intercostal veins. The Left Innominate (v. anonyma sinistra) (2) is about 2^ inches long; in its course it receives the vertebral, inferior thyroid, internal mammary, and superior inter- costal veins of the left side. VKIXS OF THE THORAX The Veins of the Thorax include the follow- ing vessels: ,* Internal Mammary, (mamariainterna), two to each artery, unite into a single trunk which terminates in the innominate vein. Inferior Thyroid (vv. thyreoideae inferiores), 2 to 4, form a plexus in front of the trachea, which gives off the left and right inferior thyroid veins, these receiving cesophageal, tracheal and inferior laryngeal veins and opening into the innominate veins. Superior Intercostal, the right vein (v. inter- costalis suprema dextra) opens into the vena azygos major, the left vein (v. intercostalis suprema sinistra) into the left innominate. Azygos Veins, are described below. * Bronchial, return the blood from the lung substance; the right one opens into the vena azygos major, the left into the left superior intercostal or the left upper azygos vein. Spinal, are described below. Vena Cavce^ are described below; the Superior Vena Cava under the Veins of the Thorax, the Inferior Vena Cava under the Veins of the Lower Extremity. The Azygos Veins supply the place of the venae cavae in the region where these trunks are deficient, being connected with the heart. Vena Azygos Major (v. azygos) (17), begins by a branch from the right lumbar veins usually, passes through the aortic opening in the l68 HUMAN ANATOMY diaphragm, and ends in the superior vena cava, having drained 10 right lower intercostals, the vena azygos minor, (v. hemiazygos), the right bronchial, cesophageal, mediastinal, and pericardial veins. Left Lower Azygos (vena azygos minor or v. hemiaz3'gos) (18), begins by a branch from the left lumbar or renal, passes through the left crus of the diaphragm, crosses the vertebral column and ends in the right azygos, having drained 4 or 5 lower intercostals. Left Upper Azygas (v. hemiazygos accessoria), drains 3 or 4 left intercostals and empties into either of the other two. It is often wanting, its place being filled by the left superioi intercostal vein (21). The Spinal Veins may be arranged in 4 sets, as follows: Qor si- spinal, form a plexus around the spines, processes, and laminae of all the vertebrae. They empty into the vertebral, intercostal, lumbar, and sacral veins in their respective regions. Meningo-rachidian, in two longitudinal plexuses, anterior and posterior, running the whole length of the spinal canal. The posterior join the dorsi-spinal veins, the anterior empty into the vertebral, intercostal, lumbar, and sacral veins in their various regions. Vena Basis Vertebrarumthe veins of the bodies of the vertebrae, are contained in large, tortuous channels in the substance of the bones, and join the transverse trunk connecting the anterior longitudinal veins. Medulli-spinale, the veins of the spinal cord, lie in plexus form between the pia mater and arachnoid. They unite into 2 or 3 small trunks near the base of the skull, which terminate in the inferior cerebellar veins or in the inferior petrosal sinuses. The Superior Vena Cava (i) is a short trunk about 2^ or 3 inches in length, formed by the union of the two innominate veins, thereby re- ceiving all the blood from the upper half of the body, and opening into the right auricle of the heart. It is half covered by the pericardium, and receives the vena azygos major and small pericardiac and mediastinal veins. VEINS OF THE LOWER EXTREMITY The Veins of the Lower Extremity are in two sets, superficial and deep. The superficial are the Internal or Long Saphenous (saphena magna), on the inside of the leg and thigh, enters the femoral at the saphenous opening i > inch below Poupart's ligament (1. inguinale). In its course it receives: Cutaneous Branches. Superficial Circumflex Iliac. Superficial Epigastric. Communicating Branches. Ext. Pubic, (venae pudendae externae). VEINS OF THE PELVIS AND ABDOMEN 1 69 External or Short Saphenous (v. saphena parva), formed by branches from the dorsum and outer side of the foot, it ascends behind the outer malleolus, up the middle of the back of the leg, and empties into the popliteal vein, between the heads of the gastrocnemius muscle. The deep veins are the vence comites of the arteries, beginning in the foot as the external (lateral) and internal (medial) Plantar, which unite to form the Posterior Tibial (venas tibiales posteriores). The vena comites of the dorsalis pedis artery continue upward as the Anterior Tibial veins (venae tibiales anteriores), which join the posterior tibial, forming the Popliteal, which becomes the Femoral, and it the External Iliac, in the same manner as the respectively named arteries. VEINS OF THE PELVIS AND ABDOMEN The Veins of the Pelvis, except the middle sacral, open into the internal iliac vein. The middle sacral opens into the left common iliac. The Internal Hiac Vein (vena hypogastrica) (10) is formed by the venae comites of the branches of the internal iliac artery, and terminates with the external iliac, at the sacro-iliac articulation, to form the common iliac vein (v. iliaca communis). It receives the following veins: From the exterior of the pelvis, the Gluteal, (v. glutaea superior). Sciatic (v. glutaea inferior). Internal Pudic (vv. pudendae internae). Obturator. From the organs in the pelvic cavity the Hemorrhoidal Plexus. \ . Uterine Plexus. \ . ,, . , J . , > in the male. ,,.,, > in the female. Vesico- pro static Plexus. J Vaginal Plexus. J The Dorsal Vein of the Penis enters the prostatic plexus. The Veins of the Abdomen include the Portal System, the Lumbar, Spermatic, Renal, Suprarenal, Phrenic, Hepatic, External Iliac, Common Iliac and the Inferior Vena Cava. The External Iliac Vein commences at the termination of the femoral beneath Poupart's ligament, and terminates opposite the sacro-iliac syn- chondrosis by uniting with the internal iliac to form the common iliac vein. It receives the Deep Epigastric (v. epigastrica inferior) and Deep Circumflex Iliac, also a small pudic vein. The Common Iliac Veins (n) are each formed by the union of the two iliac veins as above described, and unite between the 4th and 5th lumbar vertebras to form the inferior vena cava, the right common iliac being the shortest of the two, Each receives the Ilio-lumbar, sometimes the Lateral 1 70 HUMAN ANATOMY Sacral, and the left one in addition the Middle Sacral Vein, which some- times ends in the vena cava. The Inferior Vena Cava (8) extends from the junction of the two common iliac veins, passing along the front of the spine, through the tendin- ous centre of the diaphragm, to its termination in the right auricle of the heart. It receives the following veins: / Lumbar (12), 4 on each side, receive dorsal and abdominal tributaries, also veins from the spinal plexuses, and terminate in the inferior vena cava. They are connected together by the ascending lumbar, which passes in front of the transverse processes of the lumbar vertebrae. ;,, Right Spermatic (13). The spermatic veins arise from the testis and epididymis, forming the spermatic or pampiniform plexus, which forms the chief mass of the spermatic cord, and unite into 3 or 4 veins which enter the abdomen through the internal ring, form 2 veins, then a single one which opens on the right side into the inferior vena cava, on the left side into the left renal vein. In the female they are called Ovarian and terminate in the same way as in the male. ^ Renal (15), are large veins, placed in front of the renal arteries, and terminating in the inferior vena cava. The left is longer than the f right and passes in front of the aorta. T Supra-renal, on the right side ends in the vena cava, on the left side in f^ the left renal or phrenic vein. Phrenic 2, the superior ends in the internal mammary, the inferior ends oh "the right side in the vena cava, on the left side in the left renal vein. Hj&atic Veins (16), begin in the capillary terminations of the portal vein and hepatic artery in the substance of the liver, uniting into 3 large veins from the right and left lobes and the lobulus Spigelii, which open into the inferior vena cava. They have no valves. The Portal System is formed by the Superior and Inferior Mesenteric, Splenic, and Gastric Veins, which collect the blood from the digestive vis- cera, and by their union behind the head of the pancreas form the Portal Vein, which enters the transverse fissure of the liver, where it divides into 2 branches. These again subdivide, ramifying throughout the organ, therein receiving blood also from the branches of the hepatic artery. Its minute ramifications end in capillaries, from which the blood of the portal system, together with that brought by the hepatic artery, is carried by the hepatic veins to the inferior vena cava. The portal vein generally receives the Cystic Vein, which sometimes terminates in the right branch of the portaT THE LYMPHATIC SYSTEM 17 1 VEINS OF THE HEART ITSELF The Cardiac Veins return the blood from the tissue of the heart into the right auricle. They are the . Great Cardiac Vein, Right or Small Coronary Vein (v. coronaria ventriculi). Posterior Cardiac Vein. S Anterior Cardiac Veins. Coronary Sinus is a dilatation of the great cardiac vein, receiving the Left Cardiac Veins. -^ Ven(B Thebesii. Coronary Sinus is a dilatation of the great can * posterior cardiac and an oblique vein from the left auricle. THE LYMPHATIC SYSTEM Lymphatics are very delicate, transparent vessels; the larger having 3 coats like the arteries and veins, the smaller having 2 coats, the external and internal, but no middle muscular-elastic coat. Lymphatics are found in nearly every texture and organ of the body which contains blood- vessels, but are absent in the non-vascular structures, as cartilage, nails, cuticle and hair. They are nourished by blood-vessels distributed to their outer and middle coats, in which also many non-medullated nerve-fibres have been traced. They possess valves of semilunar form, placed at much shorter intervals than are the valves in the veins. They convey lymph to the blood, and possess the property of absorbing certain materials from the tissues and conveying them into the circulation; hence they are also called absorbents. They discharge their contents into the blood at two points, the junctions of the subclavian and internal jugular veins, on the left side by the thoracic duct, on the right side by the right lymphatic duct. Lacteals are the lymphatic vessels of the small intestine, conveying chyle to the blood during the process of digestion. Lymphatic Glands (lymphoglandulas) are small, solid, glandular bodies, placed in the course of the lymphatic and lacteal vessels, and found chiefly along the great blood-vessels, at the root of the lungs, in the lumbar and cceliac regions of the abdomen, in the mesentery, the mediastina, the head, neck, axilla, groin, and popliteal space. They are named after the respective regions in which they are situated, as axillary glands, the inguinal, cceliac, bronchial, mesenteric, etc. They consist of a fibrous capsule, from which trabecula are prolonged inward, dividing the gland into alveoli or open spaces containing lymphoid tissue, the proper gland- substance, which is so placed as to leave a channel (sinus), the lymph- 172 HUMAN ANATOMY path, all around it. The glands are nourished by blood-vessels supported on the trabeculae, and some fine nerve filaments are traced into them. Before entering a gland the lymphatic (or lacteal) divides into several small branches, the afferent vessels, of which the endothelial layer only enters the gland, to form in its lymph-sinuses a plexus of vessels which unite into a single efferent vessel. The external coat of the afferent vessels becomes continuous with the capsule of the gland, and is received upon the efferent vessel as it emerges. Haemal Lymph Glands, resemble ordinary lymph glands in all respects save that some of their sinuses contain blood. Haemal Glands, all of their sinuses contain blood, otherwise they do not differ from regular lymph glands. Both Haemal glands and Haemal Lymph glands are more numerous in the retro-peritoneal tela along the line of the aorta. f/ . 3^ The Thoracic Duct (ductus thoracicus) is the main channel for the lymph and chyle from the whole body except the right arm and lung, right side of the head, heart, neck, and thorax, and the convex surface of the liver. It begins in the abdomen by a triangular dilatation, the Receptaculum Chyli (cisternachyli), in front of the zd lumbar vertebra, passes through the aortic opening in the diaphragm, and opposite the 7th cervical vertebra it curves forward, outward and downward over the subclavian artery, so as to form an arch, and terminates in the left sub- clavian vein at its angle of junction with the left internal jugular vein. In the thorax it lies in the posterior mediastinum in front of the vertebral column, between the aorta on its left and the vena azygos major on its right. It has numerous valves throughout its course, and a pair of valves at its termination to prevent the passage of venous blood into its cavity. The Right Lymphatic Duct (ductus lymphaticus dexter) is a short trunk, about 2^2 inch in length and i% line in diameter. It terminates in the right subclavian vein at its angle of junction with the right internal jugular, its orifice being guarded by two semilunar valves against the passage of venous blood into its cavity. It receives lymph from those parts which are not connected with the thoracic duct, namely the right upper extremity, the right lung, the right side of the head, neck, heart and thorax, and part of the convex surface of the liver. LYMPHATICS OF THE HEAD AND NECK Lymphatic Glands of the Head and Neck, are as follows: Occipital (lymphoglandulae occipitales), i or 2, at the back of the head, close to the artery. LYMPHATICS OF THE UPPER EXTREMITY 173 Posterior Auricular or Mastoid (lymphoglandulae auriculares posteriores), 2, near the mastoid process. Anterior Auricular (lymphoglandulae auriculares anteriores), external to the parotid gland. Parotid (lymphoglandulae parotideae), some in and others around the parotid gland. Buccal, i or more, on the surface of the buccinator muscle. Submandibular (lymphoglandulae submaxillares), beneath the ramus of the jaw. Lingual (lymphoglandulae linguales), 2 or 3, on the hyo-glossus and genio-hyo-glossus muscles. Retro-pharyngeal (lymphoglandulae retropharyngeae) 2, one on each side of the middle line. Superficial Cervical (lymphoglandulae cervicales superficiales), consisting of the submaxillary, 8 to 10, the suprahyoid, i or 2, and the cervical (many) in the course of the external jugular vein. Deep Cervical (lymphoglandulae cervicales profundae superiores et infe- riores), forming a chain along the sheath of the carotid artery and in- ternal jugular vein, in two sets, an upper, 10 to 20, and a lower, 10 to 15. Lymphatic Vessels of the Head and Neck are the/ Temporal and ; Occipital, in the scalp, respectively accompanying the temporal jand oc- cipital arteries; the 'Meningeal an^ Cerebral, in the cranium; the Super- ficial and the Deep, in the face; also those of the orbit, the temporal and zygomatic fossae, the nose, tongue, pharynx, larynx and thyroid body. In the neck these vessels are continuations of those on the cranium and face. LYMPHATICS OF THE UPPER EXTREMITY Lymphatic Glands of the Upper Extremity (lymphoglandulae cubitales superficiales et profundae) are in two sets, the Superficial, which are few and small, and ih^Deep, in the forearm, the "arm and the axilla. The Axillary Glands, 10 to 12, are of large size, situated around the axillary vessels, in the tissue of the axilla, and in chains along the lower border of the pectoralis major muscle and the lower margin of the posterior wall of the axilla, they are grouped as follows: 1. Brachial or lateral. 2. Subscapular or posterior. 3. Pectoral or anterior. 4. Central. 5. Subpectoral. 174 HUMAN ANATOMY 6. Infraclavicular. 7. Interpectoral. 8. Deltopectoral. (Robinson.) Lymphatic Vessels of the Upper Extremity are the Superficial, beginning on the sides of the fingers and accompanying the veins; the^Deep, occurring in 4 sets corresponding with the radial, ulnar, and anterior and posterior interosseous arteries. LYMPHATICS OF THE LOWER EXTREMITY Lymphatic Glands of the Lower Extremity are the -Superficial Inguinal, 8 to 10, in two sets, an upper oblique set (lymphoglandulae inguinales) along Poupart's ligament (1. inguinale), and an inferior vertical set (lympho- glandulae subinguinales), 2 to 5, around the saphenous opening in the fascia lata; Deep Glands are the anterior tibial popliteal (lymphoglandulae popliteae), deep inguinal (lymphoglandulae subinguinales profundae), gluteal and ischiatic. Lymphatic Vessels of the Lower Extremity are in two sets, superficial and deep. The Superficial lie in the superficial fascia in two groups, an internal and an external, along the internal and external saphenous veins respectively. The Deep are few in number and accompany the deep blood- vessels. LYMPHATICS OF THE PELVIS AND ABDOMEN Lymphatic Glands are the external iliac, internal iliac, and sacral, in the pelvis; and the lumbar and cceliac glands in the abdomen. The Lumbar Glands are numerous, situated in front of the lumbar vertebrae, and sur- round the common iliac vessels, the aorta and the vena cava. The Cceliac Glands 20, surround the cceliac axis and lie in front of the aorta, receiving the lymphatic vessels from a large part of the liver, the spleen, pancreas and stomach. Lymphatic Vessels of the Pelvis and Abdomen are in 3 sets, the super- ficial, the deep, and those of the viscera. The Superficial follow the course of the superficial blood-vessels, and include the lymphatics of the gluteal region, the penis, scrotum and perinaeum. The Deep follow the course of the principal blood-vessels. Those of the Viscera are the lymphatics of the various organs contained in these cavities the bladder, rectum, uterus, kidney, liver, stomach, spleen and pancreas, and include those of the testicles. LYMPHATICS OF THE INTESTINES Lymphatic Glands of the Intestines are those of the large intestine, which are few in number, especially along the transverse colon; and those LYMPHATICS OF THE THORAX 175 of the small intestine, 100 to 150, which lie between the layers of the mesentery and are called the Mesenteric Glands (lymphoglandulae mesen- tericae). Lymphatic Vessels of the Intestines are those of the large intestine, some of which enter the mesenteric glands, others the lumbar glands; and those of the small intestine, called the Lacteals, from the milk-white fluid (chyle) which they usually contain. The lacteals are in two sets, super- ficial and deep, the latter occupying the submucous tissue and coursing transversely around the intestine. LYMPHATICS OF THE THORAX Lymphatic Glands of the Thorax are those of the thoracic walls (lym- phoglandulae sternales et intercostales) and those of the viscera. The former are the intercostal, the internal mammary, and the anterior and posterior mediastinal (lymphoglandulae mediastinales anteriores et posteriores) glands; the latter are the bronchial and the superior medias- tinal or cardiac glands. The Bronchial Glands (lymphoglandulae bronchiales), 10 to 12, are situated around the bifurcation of the trachea and the roots of the lungs. Superior Mediastinal or Cardiac Glands, are numerous and large, lie in front of the transverse aorta and the left innominate vein, and receive the lymph from the pericardium, the heart, and the thymus gland. Lymphatic Vessels of the Thorax are the superficial, the deep and those of the viscera in the thoracic cavity. The Superficial converge to the axillary glands; the Deep are the intercostal, the internal mammary and the diaphragmatic; those of the Viscera are the lymphatic vessels of the lungs, heart, thymus gland and oesophagus. THE NERVOUS SYSTEM / i. Brain. i. Central part < _. . . _ , [ 2. Spinal Cord. J i. Cranial Nerves. .. Penpheral part " \ 2. Sympathetic System ( '" anglia ' . ( 2. Communicating Branches. Nervous Tissue is formed of two different structures, viz. Gray or cineri- tious substance, in which nervous impressions and impulses originate; and White or fibrous substance, by which the impressions and impulses are conducted. Chemically, nervous tissue consists of proteids, neurokeratin, i 7 6 HUMAN ANATOMY nucleiii, protagon, lecithin, cerebrosides, cholesterin, nitrogenous ex- tractives and salts, with some gelatin and fat, and water; the latter varying in different parts of the system, from 60 per cent, in the sciatic nerve, to 70 per cent, in the white matter of the cerebrum, and 83 per cent, in the gray matter of the same region. Gray Nervous Substance, the essential constituent of all the ganglionic centres, is composed of nerve-cells or ganglionic corpuscles, containing nuclei FIG. 70. SHOWING SOME OF THE VARIETIES OF THE CELL-BODIES OF THE NEURONES OF THE HUMAN NERVOUS SYSTEM, INCLUDING THE DENDRITES AND SMALLL PORTIONS OF THE AXONES. AxoNE SHEATHS NOT INCLUDED. (Morris' Anatomy.) A, From spinal ganglion. B. From ventral horn of spinal cord. C. Pyramidal cell from cerebral cortex. D. Purkinje cell from cerebellar cortex. E. Golgi cell of type II from spinal cord. F. Fusiform cell from cerebral cortex. G. Sympathetic. a, axone; d, dendrites; c, collateral branches; ad, apical dendrites; bd, basal den- drites; c, central process ; p, peripheral process. and nucleoli. The cells are imbedded in a ground substance, neuroglia, which consists of fibres and cells, and is a connective tissue in function though not in development. A neurone is a nerve-cell together with all of its processes. Nerve-cells vary in size and shape, and possess one or more processes, according to the number of which they are grouped into unipolar, bipolar and multipolar cells. Of these processes one is called the THE NERVOUS SYSTEM 177 axone or axis-cylinder process, because it becomes the axis-cylinder of a nerve- fibre; the others are termed dendrltes or protoplasmic processes. White Nerve Substance or Nerve-fibre, contains two kinds of fibres, the medullated or white and the non-medullated or gray. Medullated Fibres contain a central core or axis-cylinder, the essential part of the nerve-fibre, and regarded as a direct prolongation of a nerve-cell. This is surrounded by the medullary sheath, or white substance of Schwann, com- posed of fatty matter in a fluid state, which insulates and protects the axis-cylinder. These are enclosed in the primitive sheath or neurilemma, sometimes called the tubular membrane or sheath of Schwann, which is absent in the fibres found in the brain and spinal cord. A bundle or funiculus, of such fibres, held together by endoneurium, is surrounded by perineurium, both formed of delicate connective tissue; and several funic- uli are collected into larger bundles, fasciculi, which are bound together by a common membrane, the epineurium, and then are called a Nerve, The whole arrangement is precisely analogous to that of a submarine tele- graph cable. The nerve is nourished by a minute system of capillary blood-vessels, and has certain medullated fibres in the epineurium, termed the nervi nervorum, or nerves of the nerves. The Non-medullated Fibres, also called gray or gelatinous nerve-fibres, or fibres of Remak, consist of a central core- or axis-cylinder enclosed in a nucleated sheath. They constitute most of the sympathetic nerves and include some of the cerebro-spinal. Terminations of Nerves. Their origin or central termination occurs from the nerve centre by one or two roots, in the latter case sometimes widely apart from each other. The efferent nerve-fibres originate in the cells of the gray substance, the afferent fibres branch among the cells without uniting with them. The peripheral termination of sensory nerves seems to be in minute primitive fibrilla or networks thereof; that of motor nerves in special terminal organs, variously named, as the end-bulbs of Krause, the tactile corpuscles of Wagner, the Pacinian corpuscles, the neuro-tendinous and neuro-muscular spindles, and the motorial end- plates of the striped or voluntary muscular fibre. Ganglia are separate small aggregations of nerve-cells, connected with each other, with the cerebro-spinal axis, and with nerves in various situations. They consist of a collection of nerve-cells and nerve-fibres, invested by a membranous envelope, which is continuous with the peri- neurium of the nerves, and sends processes into the interior of the ganglion to support the blood-vessels supplying its substance. They are found on the posterior roots of all the spinal nerves, on the posterior (sensory) root 12 178 HUMAN ANATOMY of the 5th cranial nerve; on the facial, auditory, glosso-pharyngeal and pneumogastric nerves; also in a connected series along each side of the vertebral column anteriorly, forming the trunk of the sympathetic, and on the branches of that nerve. THE BRAIN Development of the Brain. At an early period of embryonic life the cerebro-spinal axis consists of a thin-walled tube, the neural tube, which, while still open at its caudal end, becomes enlarged at its cephalic end, where constrictions appear, dividing this end into 3 primary vesicles, the anterior, middle and posterior. From these vesicles are developed the ventricles of the brain, the rest of the neural tube forming the central cavity of the spinal cord. Thickenings of the wall of the neural tube form the substance of the brain and spinal cord. The Anterior Primary Vesicle, Prosencephalon, divides into an anterior (telencephalon) and a posterior (diencephalon] secondary vesicles. From the telencephalon are developed the cerebral hemispheres; corpora striata; corpus callosum; fornix; lateral ventricles; olfactory lobe; front part of the third ventricle; front part of the tuber cinereum; infundibulum; and the posterior lobe of the pituitary body (hypophysis). From the diencephalon are developed, the optic thalami (thalamus); corpora geniculata (metathalamus) ; pineal body, the posterior part of the tuber cinereum; posterior part of the third ventricle; corpora mammillaria; optic nerve and optic tracts. Middle Primary Vesicle, Mesencephalon, its cavity becomes the aqueduct of Sylvius, and with the parts developed around it con- stitutes the mesencephalon or mid-brain. From the mesencephalon are developed, corpora quadrigemina; pedunculi (crura) cerebri; and aquaeductus cerebri (aquaeduct of Sylvius). The constricted communication between the middle primary vesicle and the posterior primary vesicle is known as the isthmus rhomben- cephali, from it are developed the superior cerebellar peduncles (brachia conjunctiva) and the valve of Vieussens (anterior medullary velum). Posterior Primary Vesicle, Rhombencephalon, by constriction forms an anterior secondary vesicle, metencephalon; and a posterior second- ary vesicle, myelenccphalon. From the metencephalon are developed the cerebellum; pons varolii (pons) ; and front part of the fourth ventricle. THE BRAIN 179 From the myelencephalon are developed the medulla oblongata and the posterior portion of the fourth ventricle. Structure of the Cerebrum. The cerebrum is composed of gray and white matter, the former disposed in two great groups, that of the cere- bral cortex and that in the basal ganglia. The Gray Matter of the Cortex is composed of 6 alternating white and gray layers. The cortex is made up of nerve-cells and nerve-fibres. The Nerve-cells are arranged in 5 layers, named, from the surface inward, as follows: the fmolecular layer, the outer layer /'.of polymorphous cells, the layer of small pyramidal cells, the layer of large pyramidal cells, the inner layer of polymorphous cells. In certain parts of the cortex this arrange- ment is variously departed from, as many as 9 layers being described in the cuneus. The Nerve-fibres are either medullated fibres or naked axis- cylinders embedded in a matrix of neuroglia. The Basal Ganglia are a series of gang! ionic masses in the base of each cerebral hemisphere, subjacent to the island of Reil, they and it constitut- ing the oldest part of the hemisphere, the first to appear in the order of development. They are semi-detached local thickenings of the gray cortex, and are named as follows: Corpus Striatum, composed of two nuclei, the caudate and the len- ticular (lentiform) (described on page 191). Closely associated with it are certain fasciculi of white matter, the / 3cr/ Internal Capsule (page 192). External Capsule (page 192). Anterior Commissure (page 192). Tania Semicircularis (stria terminalis) (page 190). Claustfum, a thin band of gray matter, described under the corpus striatum on page 191. Nucleus Amygdala, a thickening of the cortex of the apex of the temporal lobe, producing a bulge, the amygdaloid tubercle, in the roof of the extremity of the descending cornu of the lateral ventricle. The Optic Thalamus, though in close proximity to the corpus striatum, is not placed among the basal ganglia of the hemispheres, being considered part of the diencephalon or inter-brain. The White Matter consists of medullated fibres in bundles, arranged in the following 3 systems: PROJECTION FIBRES (peduncular), connecting the hemispheres with the medulla oblongata and the cord. They originate in the cells of the cerebral cortex from whence they proceed, forming the corona radiata as they converge to enter the internal capsule when they are l8o HUMAN ANATOMY collected into the several bundles which are continued as the crusta (basis) of the crura (pedunculi) cerebri. TRANSVERSE OR COMMISSURAL FIBRES, connect the two hemispheres. They are the transverse fibres of the corpus callosum, and the anterior and posterior commissures of the 3d ventricle. ASSOCIATION FIBRES, connect different structures in the same hemi- sphere; the short connecting adjacent convolutions; and the long, connecting distant structures, as follows, the Uncinate Fasciculus, from the frontal to the temporal lobe, across the bottom of the fissure of Sylvius, (fissura cerebri lateralis). Cingulum, antero-posteriorly in the convolution of the corpus callosum, from the anterior perforated substance to the hook of the uncinate gyrus (anterior end of the sup. occipito-temporal gyrus). Superior Longitudinal Fasciculus, connects the frontal lobe with the occipital and temporal lobes. Inferior Longitudinal Fasciculus, connects the temporal with the occipital'lobe. It runs the entire length of both lobes and con- nects their convolutions. Perpendicular Fasciculus, connects the inferior parietal lobule with the inferior occipito-temporal convolution (gyrus fusiformis). Fornix, connects the hippocampal convolution (superior occipito- temporal) with the corpora albicantia (corpora mammillaria) and the optic thalamus.. THE MENINGES Membranes of the Brain are the dura mater, the arachnoid membrane, and the pia mater. 3 7 The Dura Mater is a dense fibrous membrane lining the interior of the skull. It consists of two layers which are coalesced throughout the greater part of their extent. The inner layer which is produced into the intervals between parts of the brain forming partitions, and the outer layer which is strongly attached at the base of the cranial cavity and along the cranial sutures into which it sends processes. The outer layer forms the internal periosteum of the cranial bones. It is con- tinuous with the dura mater of the spinal cord, with the pericranium, and the periosteum of the orbit; being prolonged to the outer surface of the skull through the various foramina at its base. It sends 4 processes into the cavity of the skull for the support of the different parts of the brain, also several tubular processes and prolongations through orifices and THE MENINGES l8l foramina in the skull for the protection of nerve trunks and vessels. The Cerebral dura mater derives its nerve supply from the 4th and 5th cranial nerves, and from the sympathetic (Whitaker). It presents the following points for examination Tht Mcningeal Arteries, are on, or close to, the outer surface, whereas the veins are deeply placed between the two layers and form sinuses (see page 164). Falx Cerebri, an arched process into the longitudinal fissure of the brain vertically; contains in its upper and lower margins the superior and inferior longitudinal sinuses. Tentorium Cerebelli, a lamina of dura mater supporting the posterior lobes of the brain, and covering the upper surface of the cerebellum. It incloses the lateral and superior petrosal sinuses. Falx Cerebelli, projects between the lateral lobes of the cerebellum, from the tentorium to the foramen magnum. Diaphragma Sella, a horizontal process forming a small circular fold which almost covers the pituitary body and constitutes a roof for the sella turcica. Pacchionian Bodies (granulationes arachnoideales), clusters of white granulations situated on both the outer and inner surface of the dura mater near the larger sinuses, and in the interior of the larger sinuses (see page 182). The Arachnoid Membrane is a delicate single-layer envelope which covers the brain, lying between the dura mater and the pia mater, although throughout a large part of its extent it is not distinct from the pia mater. It is separated from the dura mater by the superficial cerebral veins. It dips into the great longitudinal fissure of the brain and into the interval between the cerebrum and cerebellum but it does not enter the fissures between the convolutions of the brain. Processes of it are prolonged around the cranial nerves as far as their points of exit from the skull. It is supplied probably by the 5th, 7th and nth cranial nerves (Whitaker). Subdural Space (cavum subdurale), is the space between the arach- noid and the dura mater. It contains a small amount of fluid of the nature of lymph. Subarachnoid Space (cavum subarachnoidalis), is the interval between the arachnoid and pia mater, forming the two large spaces, mentioned below, at the base of the brain, but small on the surface of the hemi- spheres. It is occupied by a spongy connective tissue, in the meshes of which the cerebro-spinal fluid is contained. It communicates with the genera] ventricular cavity of the brain by 3 openings, one of 1 82 HUMAN ANATOMY which, the foramen of Magendie (metapore), is in the middle line at the lower end of the roof of the 4th ventricle. Anterior Subarachnoidean Space (cisterna interpeduncularis), is the interval between the arachnoid and the pia mater at the base of the brain, where the former membrane extends across between the two temporal lobes. Posterior Subarachnoidean Space (cisterna cerebellomedullaris), is a similar interval between the hemispheres of the cerebellum and the medulla oblongata. These two spaces communicate with each other across the inferior cerebellar peduncles (corpores restiformes). Cerebro-spinal Fluid, occupies the subarachnoid space of the brain and spinal cord, and also the ventricular cavities of the brain. Its average quantity is about 2 oz., being most abundant in old persons. It forms a water-bed for the protection of the nervous centres from the effects of concussions. Granulationes Arachnoideales or Pacchionian bodies, are numerous, small, granulations, which are not glandular in structure but enlarged normal villi of the arachnoid; found on the outer and inner surfaces of the dura mater, in the superior longitudinal sinus, and on the pia mater. They are not usually found until after the 7th year of age, and are occasionally wanting. The Pia Mater is a vascular membrane, supplied by branches of the in- ternal carotid and vertebral arteries. It covers the surface of the brain, dipping down into all the sulci, and forms the velum interpositum (tela chorioidea ventriculi tertii) and choroid plexus (plexus chorioideus ventriculi lateralis) of the lateral and 4th ventricles. It consists of a minute plexus of blood-vessels, held together by a very fine areolar tissue; and contains numerous lymphatic vessels and nerves, the latter being derived from both the cerebro-spinal and sympathetic systems. Its nerve supply is derived from 3d, 5th, 6th, 7th and 8th cranial nerves and from the sympathetic (Whitaker). Weight of the Brain. Its average weight in the male adult is from 1360 (Smith) to 1400 (Spitzka) grammes; in the female 1250 grammes (Spitzka), of which the cerebrum is about seven-eighths. Divisions of the Brain. The Brain may be divided into the Cerebrum, the Cerebellum, the Pons Varolii (pons) and the Medulla Oblongata; but for the descriptive purposes it is best considered under the following 5 divisions, viz. the Cerebral Hemispheres or Telencephalon, comprising the various lobes, the lateral and 5th ventricles, and the basal ganglia. THE BRAIN 183 Inter-brain or Diencephalon, the region of the 3d ventricle, including also the optic thalami and the pineal gland. Mid-brain or Mesen-cephalon, comprising the crura cerebri, the corpora quadrigemina, the corpora geniculata, and the aqueduct of Sylvius (aquaeductus cerebri). Hind-brain or Melencephalon, comprising the pons Varolii, the cere- bellum, and the upper half of the 4th ventricle. Medulla Oblongata or Myelencephalon, including the lower half of the 4th ventricle. The Cerebrum or Telencephalon. The cerebrum presents an ex- ternal surface of gray matter called the cortex, the large upper part of which is called the Pallium or Mantle; the smaller lower or basilar part is called the Rhinencephalon. The surface of the brain presents numerous clefts; some of these clefts cause a corresponding projec- tion into the cavities of the interior of the brain and are called Fissures (fissurae) in order to distinguish them from the others called Sulci, which are those clefts which separate lobes (or lobules) from each other. Clefts that separate the lobes from each other are called inter-lobular sulci, while those that divide lobes into convolutions or gyri are known as intra-lobular sulci. The cerebrum is divided into two hemispheres by the Great Longitudinal fissure (fissura longi- tudinalis cerebri). THE CEREBRAL HEMISPHERES Lobes in each Hemisphere, are as follows: Frontal Lobe, bounded internally by the longitudinal fissure, below by the fissure of Sylvius (fissura cerebri lateralis), and posteriorly by the fissure of Rolando (sulcus cerebri centralis). Parietal Lobe, extending down to the fissure of Sylvius (fissura cerebri lateralis), and antero-posteriorly from the fissure of Rolando (sulcus cerebri centralis) to the external parieto-occipital fissure. Occipital Lobe, behind the parieto-occipital fissure. Temporal Lobe, lying in the middle fossa of the skull, and bounded in front by the fissure of Sylvius (fissura cerebri lateralis). Central Lobe, or Island of Reil (Insula), lies in the fissure of Sylvius (fissura cerebri lateralis) covered by the frontal and temporal lobes. Limbic Lobe, arches around the corpus callosum and the hippocampal fissure; is well developed in animals having a keen sense of smell. Olfactory Lobe, situated on the under surface of the frontal lobe, and divided into the olfactory bulb, the olfactory tract, the trigonum, and 184 HUMAN ANATOMY the posterior olfactory lobule (ant. perforated space or substantia per- forata anterior). Fissures of the Cerebrum are as follows: Longitudinal Fissure (fissura longitudinalis cerebri), extends from the front of the cerebrum to the back, separating it into two hemispheres, which are connected in the middle portion by the central commissure, the corpus callosum (10), forming the floor of the fissure in this part of its length. Syhian Fissure, or Fissure of Sylvius (fissura cerebri lateralis), on each side at the base and lateral side of the brain. Starting at the anterior perforated substance it passes outward to the external surface of the hemisphere, where it divides into a short anterior limb (ramus anterior horizontalis), a short ascending limb (ramus anterior ascendens), and a horizontal limb (ramus posterior). It lodges the middle cerebrav artery. Fissure of Rolando (sulcus cerebri centralis) (i), on the superior surface of each hemisphere, extending from the longitudinal fissure about it? centre, downward and forward toward the fissure of Sylvius, separating the frontal and parietal lobes. This fissure is said to be found only in man and the higher primates. Parieto-occipital Fissure, extends from the longitudinal fissure outward for about an inch between the parietal and occipital lobes. Calloso-marginal Fissure (sulcus cinguli), above the gyrus fornicatus (gyrus cinguli) on the inner surface of each hemisphere. Internal Parieto-occipital Fissure, extends downward and forward to join the calcarine fissure, on 'a level with the hinder end of the corpus cal- losum. Calcarine Fissttre (fissura calcarina), begins close to the posterior extrem- ity of the hemisphere, runs horizontally forward, joined by the parieto- occipital fissure, and terminates a little below the posterior end of the corpus callosum (u). Collateral Fissure, below and external to the preceding, runs forward from the posterior extremity of the brain nearly as far as the tip of the temporal lobe. Dentate or Hippccampal Fissure, commences behind the posterior end of the corpus callosum (n) and runs forward to the recurved part (uncinate gyrus) of the hippocampal gyrus (posterior horizontal part of the sup. occipi to- temporal convolution). Transverse Fissure, a horse-shoe shaped gap or cleft at the base of the brain, extending from the foramen of Munro on each side to the termina- THE BRAIN FIG. 71. tion of the descending cornu of the lateral ventricle. One-half the fissure is in each hemisphere, and it admits an invagination of the pia mater, which forms the choroid plexus in the lateral ventricle and the velum interpositum (tela chorioidea ventriculi tertii) in the 3d ventricle. It gives exit to the venae Galeni. Parallel Fissure, formerly called the first temporo-sphenoidalfisstire, on the lateral surface of the hemisphere below the fissure of Sylvius (fissura cerebri lateralis). Cerebral Convolutions. The superior and inner surfaces of each hemi- sphere are formed of convolutions (gyri) with intervening fissures and de- pressions (sulci) of various depths, the gyri and sulci being both formed of gray matter thus ar- ranged to enable it to present a great extent of surface. The con- volutions are not uniform in all brains as to arrangement, nor are they symmetrical in the two hemispheres. The principal con- volutions are the following- named : On the Frontal Lobe are 8, ex- t e r n a 1 1 y the ascending (gyrus centralis anterior) (2), superior (4), middle (5) and inferior (6) frontal; in- feriorly the internal, anterior and posterior orbital. The inferior frontal on the left side is named the convolution of Broca and is the language centre. On the Parietal Lobe., are 4, externally the ascending (gyrus centralis posterior) (3), superior and inferior parietal, and the quadrate or precuneus, internally. The inferior parietal is subdivided into the supramarginal, the angular, and postparietal gyri, the latter (2) lying around the posterior end of the superior temporal sulcus (parallel fissure) (see above). 1 86 HUMAN ANATOMY The Occipital Lobe has 4, externally the superior (7), middle (8) and inferior (9) occipital; and internally the cuneate lobule or cuneus. Temporal Lobe has 5 gyri, externally, the superior, mfddle, and inferior temporal gyri; below on the tentorial surface, the superior occipito-temporal (gyrus lingualis or subcalcarine), and the inferior occipi to- temporal (gyrus fusiformis). Part of the inferior temporal gyrus also shows on this surface. On the upper surface, two or three indefinite gyri can be seen. The superior occipito-temporal lobe is by some considered to be two lobes, in which case, its anterior, upwardly hooked portion is called the uncinate gyrus, the posterior horizontal portion being called the hippocampal gyrus. The Central Lobe or Island of Reil (insula), is subdivided by the sulcus centralis into the precentral lobe (pars frontalis) and the postcentral lobe (pars occipitalis). The insula is pyramidal in shape and consists of 5 or 6 convolutions called gyri operti. Under Surface of the Base of the Brain, from before backward, ex- cluding the vessels and the cranial nerves, shows the following points for examination. In the middle line are the Longitudinal Fissure, its anterior portion separating the frontal lobes, and its posterior portion between the occipital lobes. Corpus Callosum, the great transverse commissure, seen in the longi- tudinal fissure, and showing its peduncles, one on each side, to meet the corresponding outer root of the olfactory tract. Lamina Cinerea, a thin, triangular, gray layer, continuous with the anterior perforated space (locus perforatus anterior). In the mid- line it is divided into a right and a left portion by a very thin almost transparent portion the lamina terminalis, which forms the anterior and inferior boundary of the 3d ventricle. Optic Commissure, formed by the junction of the optic tracts. Tuber Cinereum (17) a gray lamina behind the optic commissure, form- ing part of the floor of the third ventricle. From it projects the Infundibulum, a hollow process, its canal connecting the pituitary cavity with the 3d ventricle in the foetus. Eminentia Saccularis, between the corpora albacantia or mammillaria and the tuber cinereum, it is a trefoil-shaped eminence homologous with the saccus vasculosus of the lower vertebrates. The Pituitary Body or Gland (Hypophysis Cerebri), is a small oval body depending by the infundibulum from the tuber cinereum in the floor of the third ventricle. It occupies the pituitary fossa (fossa hypo- physeos) in the sella turcica of the sphenoid bone. It consists of two THE BRAIN FIG. 72. 27 THE BASE OF THE BRAIN i. Olfactory Bulb. 2. Second, or Optic Nerves. 3. Anterior Perforated Space. 4. Optic Tract. 5- Crus Cerebri. 6. 3d Nerve. 7. 4th Nerve. 8. sth Nerve. 9. 6th Nerve. 10. Pyramid, n. Olivary Body. 12. Vertebral Artery. 13. Anterior Spinal Artery. 14. Anterior Cerebral Artery. 15. Lamina Cinerea. 16. Middle Cerebral Artery. 17. Tuber Cinereum. 18. Corpora Albicantia. 19. Posterior Perforated Space. 20. Posterior Cerebral Artery. 21. Superior Cerebral Artery. 22. Pons Varolii. 23. Inferior Cerebellar Artery. 24. 7th and Sth Nerves. 25. 9th, loth and nth Nerves. 26. I2th Nerve. 27. Cerebellum. 1 88 HUMAN ANATOMY lobes. Anterior (buccal or glandular) lobe is the larger, it secretes a colloid substance much like that of the thyroid gland (glandula thyreoidea). Its structure is much like that of the para-thyreoid bodies. It consists of compartments which are lined with cuboidal cells of two varieties. The principal cells are the more numerous; they are small cells with very granular cytoplasm. The large cells are chromophile cells. The anterior lobe is derived from the primitive buccal cavity (stomatodaeum). Posterior or cerebral lobe is the smaller and is connected by the infundibulum to the tuber cinereum, but is not known to be functional. It is composed chiefly of neu- rogliar connective tissue and blood-vessels, throughout which are interspersed numerous branched cells. It has no organized structure. It is derived from the hypophyseal diverticulum of the diencephalon. The hypophysis gets its blood supply from the hypophyseal branches of the internal carotid artery, it is classed as one of the ductless glands. Corpora Albicantia (corpora mammillaria) (18), two round, white eminences, united together; they are the anterior crura of the fornix folded on themselves. Posterior Perforated Space (Pans Tarini or Substantia Perforata Posterior} (19), perforated for vessels to the optic thalami; forms part of the floor of the 3d ventricle. Pons Varolii (pons) (22), a broad band of white fibres, passing from one cerebellar hemisphere to the other described on page 203. Medulla Oblongata (13), pyramidal in form, emerges from the posterior border of the pons Varolii. It is described on page 208, On each side of the middle line are seen the Frontal Lobe, its under surface (see ante, page 185); lying thereon is the Olfactory Lobe, consisting of the olfactory bulb (i), the olfactory tract, the trigonum olf actorium, and the posterior olfactory lobule or anterior perforated space (3). Anterior Perforated Space (substantia perforata anterior), (3) or pos- terior olfactory lobule, at the commencement of the fissure of Sylvius (fissura cerebri lateralis); is perforated for small arteries going to the corpus striatum. Fissure of Sylvius (fissura cerebri lateralis), is described on page 184. Optic Tract (4), runs obliquely across the crus cerebri as a flat band, and enters into the optic commissure. Crus Cerebri or Cerebral Peduncle (5), a thick bundle of white matter in front of the anterior border of the pons, passing forward and out- ward to enter the undfir surface of the hemisphere. The two crura THE BRAIN 189 connect the cerebrum with the cerebellum, medulla oblongata and spinal cord. With the optic tracts they form the boundaries of the inter -peduncular space. Temporal Lobe, its under surface (see page 186). Cerebellum (27), covering the occipital lobe of the cerebrum. It is described separately on page 206. Ventricles of the Brain are 5 in number, of which the two lateral and the 5th belong to the cerebral hemispheres, the 3d is the cavity of the interbrain, and the 4th belongs to the cerebellum and the medulla oblon- gata. They are situated as follows: Two Lateral Ventricles, (ventriculi laterales), within the substance of the hemisphere, one in each; they are connected with the 3d ventricle and indirectly with each other by the foramina of Munro (foramina interventricularia) and the 3d ventricle. Third Ventricle (ventriculus tertius), a narrow crevice between the optic thalami, lying below the lateral ventricles and communicating with them by the foramina of Munro (foramina interventricularia). It is connected with the 4th ventricle by the iter a tertio ad quartum ventriculum or aqueduct of Sylvius (aquaeductus cerebri). Fourth Ventricle (ventriculus quartus), between the cerebellum and the medulla oblongata. Fifth Ventricle (cavum septi pellucidi), between the two laminae of the septum lucidum (septum pellucidum), between the two lateral ventricles. It is not a true ventricle. The Lateral Ventricles are two irregular cavities in the cerebral hemi- spheres, separated from each other by a partition, the septum lucidum, (or pellucidum), and each having a central cavity and 3 prolongations or cornua, the anterior in the frontal lobe, the middle in the temporal lobe and the posterior in the occipital lobe. They communicate with each other and with the 3d ventricle by the foramina of Munro (foramina interventricularia). The central cavity (pars centralis) is situated in the parietal lobe and is bounded as follows: Roof, the under surface of the corpus callosum. Floor, from before backward, the caudate nucleus of the corpus striatum, taenia semicircularis (stria terminalis), optic thalamus, choroid plexus, the thin sharp free edge of the lateral half of the fornix and its posterior pillar. Internally, the septum lucidum (septum pellucidum), separating it from the opposite ventricle. Externally, in front and behind, brain-substance. 190 HUMAN ANATOMY Structures named above are briefly described as follows: Corpus Callosum, the great transverse commissure, arching backward to become continuous with the fornix, reflected below, forming the peduncles at the entrance of the fissure (lateral cerebral) of Sylvius; and marked above by a depression, the Raphe, and longitudinal ele- vations, the stria longitudinales, mediates and laterales, or nerves of Lancisi. Septum Lucidum (septum pellucidum), consists of 2 layers of white and gray matter, lined by epithelium; is placed vertically between the lateral ventricles, from the raphe of the corpus callosum above to the fornix below. The cavity in its centre is the 5th ventricle (or cavum septi pellucidi). Fornix, is a commissure situated beneath the corpus callosum, but continuous with it posteriorly, the septum lucidum (s. pellucidum) separating them in front. It is composed of association fibres which are axis-cylinder processes connecting different parts of the same hemisphere. It is of triangular form with the apex in front. Its anterior pillars curve downward to the base of the brain, are there reflected, forming the corpora atticantia (corpora mammillaria), and end in the optic thalami. Its posterior pillars (crura fornicis) pass down the descending horns of the lateral ventricles, along the concavities of the hippocampi majores, and are each continued as the corpus fimbrialum or t&nia hippocampi, into the uncus or hook of the hippocampal convolution. The Lyra (psalterium) is a series of markings on its under surface. Foramina of Munro (foramina inter ventricularia), together form a Y-shaped opening situated between the anterior pillars of the fornix in front and above and the anterior extremities of the optic thalami below and behind. Each is crescentic in outline and by it the lateral ventricles communicate with the 3d ventricle and with each other. Tania Semicircular is (Stria Terminalis), consists of commissural fibres passing between the corpus striatum and the optic thalamu?. Choroid Plexus of Veins, is the margin of a fold of pia mater which enters at the transverse fissure, passes up the descending cornu, through the foramen of Munro, and as the Velum Interpositum (tela chorioidea ventriculi tertii) spreads out over the roof of the 3d ventricle. Corpus Striatum, is described on page 191. Optic Thalamus, is described on page 193. Cornua of the Lateral Ventricles. The Anterior Cornu (cornu anterius) curves over the anterior end of the corpus striatum into the frontal lobe. THE BRAIN 191 The Posterior Cornu (cornu posterius) curves downward and inward in the occipital lobe, and contains a smooth eminence, the Hippocampus Minor, which is caused by the calcarine fissure; below thisis a slight eleva- tion called the calcar avis. As the calcar avis and the hippocampus diverge from each other they leave a triangular interval called the tri- gonum collaterals. The Middle Cornu (cornu inferius) descends into the temporal lobe to the transverse fissure at the base of the brain, curving backward, outward, downward, forward, and inward (initials of the directions form the mnemonic word BODFI). On its floor are the following: Hippocampus Major, a white eminence, about 2 inches long, formed by the infolding of the cerebral cortex to produce the dentate or hippo- campal fissure. Pes Hippocampi, the scolloped end of the hippocampus. Pes Accessorius (Eminentia Collateralis] , between the hippocampi, at the junction of the middle and posterior cornua, it is caused by the collateral fissure. Corpus Fimbriatum, a continuation of the posterior pillar of the fornix (crus fornicis). Choroid Plexus of Veins, a process of pia mater (see page 190). Dentate Convolution (fascia dentata), a band of gray matter, just below the fimbria, its free border is notched by the branches of the choroid artery. Transverse Fissure (fissura chorioidea), at the extremity of the cornu, extending to the foramena of Munro (foramena interventricularia). It is described on page 184. The Fifth Ventricle (cavum septi pellucidi) is a narrow chink situated between the layers of the septum lucidum (septum pellucidum), and there- fore lies between the lateral ventricles. In the ftetus it communicates with the 3d ventricle by an opening between the anterior pillars of the fornix (columnar fornicis). Originally it was part of the longitudinal fissure and was shut off by the union of the hemispheres in the formation of the corpus callosum above and the fornix below. It usually contains fluid, of the nature of lymph. The Corpus Striatum is a body of gray matter imbedded in the white substance of each hemisphere, and is partly seen in the lateral ventricle and its anterior cornu, this part being the Nucleus Caudatus (caudate nucleus), the intra-ventricular portion; a pear-shaped mass having its narrow end on the outer side of the optic thalamus. IQ2 HUMAN ANATOMY Nucleus Lentiformis (lenticular nucleus), the extra- ventricular por- tion, only seen in sections of the hemisphere. It is divided by the white external and internal laminae into three portions, the two medial portions together constitute the globus pallidus, the remaining part is much the larger and is called the putamen. Internal Capsule, a curved lamina of white matter separating the caudate nucleus from the lenticular (lentiform) posteriorly. It is formed by projection fibres from the crus cerebri, the corpus stria- turn and the optic thalamus. [Projection fibres are axis-cylinder processes connecting cells in the gray matter of the hemispheres with other cells at lower levels in the cerebro-spinal axis.] Its anterior limb (pars frontalis) is the portion in front of the curve or genu, its posterior limb (pars occipitalis) lying behind the genu. External Capsule, a lamina of white matter bounding the putamen of the lenticular (lentiform) nucleus externally, and made up of asso- ciation fibres from the anterior commissure and the subthalamic region. Claustrum, a thin layer of gray matter on the outer surface of the external capsule, regarded as a detached portion of the gray matter of the island of Reil (insula). THE INTER-BRAIN The Inter -brain or Thalamen-cephalon (Diencephalon) is the region of the 3d ventricle, and is connected in front and above with the cerebral hemispheres, behind with the mid-brain or mesencephalon. Its upper surface is covered by iheforrrix; inferiorly it reaches the base of the brain, it comprises the following structures, optic thalami, corpora geniculata (metathalamus), pineal body (corpus pineale), posterior part of the tuber cinereum, posterior part of the third ventricle, corpora albicantia (corpora mammillaria), optic nerve, and optic tract. The Third Ventricle (ventriculus tertius) is a mere fissure, situated in the mid-line, between the optic thalami. It communicates with the lateral ventricles above by the foramina of Munro (foramina interven- tricularia) and with the 4th ventricle behind by the iter a terio ad quartum ventriculum (aquaeductus cerebri). It is crossed by 3 bands, the anterior, middle, and posterior commissures, the middle one being of gray matter, the others of white. Anterior Commissure, is composed of commissural fibres, it appears to connect together the corpora striata; its fibres are traced into the temporal lobes, and include fibres from the olfactory tract of the THE BRAIN 193 opposite side. Commissural fibres are axis-cylinder processes which connect identical parts of the two hemispheres. Middle Commissure (massa intermedia), is composed of gray matter and connects the two optic thalami. Posterior Commissure, is composed of commissural fibres (see above); it stretches across from one optic thalamus to the other, and contains fibres connecting the two thalami, besides decussating fibres from various parts of the mid-brain. Boundaries of the Third Ventricle are as follows: Roof, the velum interpositum (tela chorioidea ventriculi tertii), and above it the fornix. Floor, the parts comprised in the interpeduncular space at the base of the brain, viz. the tuber cinereum, with its infundibulum and pituitary body, corpora albicantia (corpora mammilaria), posterior perforated space (substantia perforata posterior). Eminentia sac- cularis, and chiasma optica. Anteriorly, the anterior pillars of the fornix (columnae fornicis), and the lamina terminalis which joins the right and left half of the lamina ceneria. Posteriorly, the pineal gland (corpus pineale), posterior commissure and the iter a terio ad quartum ventriculum (cerebral aqueduct). Laterally, the optic thalami and the peduncles of the pineal body. The Optic Thalami are two large, oblong masses, composed mainly of gray matter and situated on either side of the 3d ventricle, between the diverging portions of the corpora striata. Their outer and inferior surfaces are blended with contiguous parts of the brain; their upper, inner and posterior surfaces are free. They are intimately connected, by com- municating fibres, with the tegmenta of the crura cerebri, the optic tract, the cerebral cortex, the corpora striata and the corpora albicantia (corpora mammillaria). Each optic thalamus terminates anteriorly as a rounded point Anterior Tubercle, containing the anterior nucleus. As they pass backwards the optic thalami diverge outwards from each other and each terminates as a rounded swelling, the Posterior Tubercle or Pulvinar to which is attached laterally the external geniculate body (corpus geniculatum laterale). Corpora Geniculata (metathalamus) four oval eminences, a pair of which is situated below and external to the pulvinar of the thalamus on each side of the brain. External Geniculate Body (corpus geniculatum laterale) the larger of the IQ4 HUMAN ANATOMY pair, is at a higher level and is slightly anterior as well as external or lateral to the internal geniculate body (corpus geniculatum mediale). The external geniculate body (corpus geniculatum laterale) belongs to and is properly a part of the optic thalamus, it receives the outer or lateral limb of the optic tract. Internal Geniculate Body (corpus geniculatum mediale) receives the outer part of the inner or medial limb of the optic tract. These fibres do not however enter the eye, they originate in one of the inferior corpora quadrigemina (colliculus inferior) on one side of the brain, run forwards, cross by way of the optic chiasm, and then run backwards to the internal (lateral) genicutate body and inferior colliculus of the side opposite to that of their origin, this constitutes what is known as the commissure of Gudden. Pineal Body (corpus pineale), or epiphysis cerebri, is a small oval, reddish vascular body (or gland), situated in front of the anterior corpora quadrigemina (colliculi superiores) in the mid-line, just over the opening of the aquaeductus cerebri (Sylvius) into the third ventricle. It derives its blood supply from the velum interpositum (tela chorioidea ventriculi tertii) to which it is firmly attached. It has two peduncles which run forwards, one on each side of the third ventricle, on the inner or medial surfaces of the optic thalami, to join the anterior pillars of the fornix (columnae fornicis). The pineal body, classed as one of the ductless glands, is not com- posed of nervous elements but consists of numerous follicles which are lined by epithelium. Some of the follicles are filled with a very viscid liquid containing many epithelial cells constituting what are known as corpora amylacea, some contain sabulous concretions of lime, magnesia, and ammonia salts (brain sand) constituting what is known as the acervulus cerebri. The pineal body is homologous to the so-called "pineal eye" of some reptiles and some of the other lower vertebrates. Trigonum Habenulae, a small triangular space with the apex pointing forward, and its base corresponding to one of the anterior corpora quadrigemina (colliculus superior). It is the interval between one of the crura or peduncles of the pineal body and the optic thalamus of the same side. In this triangle is a cluster of nerve cells forming the ganglion habenulce. The Mesencephalon or Mid-brain is the so-called isthmus cerebri. It is the constricted portion which connects the pons (varolii) with the diencephalon (inter-brain or thalamen-cephalon) and the cerebral hemi- spheres. Comprised in it, on its ventral surface are the two crura (pedun- THE BRAIN I 95 culi) cetebriy and on its dorsal surface are the four corpora quadrigemina (colliculi). It is traversed by the eqtusductus cerebri (Sylvius). Above and in front, it is continuous with the diencephalon or inter-brain, and below with the pons Varolii. The Crura Cerebri (pedunculi cerebri), two thick conical stalks which constitute the stems of the cerebral hemispheres, are the upward continuation of the medulla oblongata. Their parallel portions are blended and held together by a mesial raphe which is indicated in front or ventrally by a longitudinal groove. This portion is covered in front or ventrally by the pons Varolii. The crura (peduncles) as they emerge above the upper border of the pons Varolii, diverge laterally from each other, enlarging as they ascend. Each crus (pedunculus) then passes beneath the optic thalamus and enters a cerebral hemisphere and continues to the internal capsule. As seen from in front or ventrally, the interval between the divergent crura (pedunculi) cerebri is called the inter-peduncular space. In this space are the corpora albicantia (corpora mammillaria) . The floor of the space is formed by the substantia perforata posterior also called the posterior perforated space. The inner or medial sides of the crura (pedunculi) cerebri are grooved by the superficial origin of third or oculo-motor nerves. Winding forward around the outer or lateral sides of the crura (pedunculi) cerebri are the optic tracts and below them, the fourth or trochlear nerves. On the dorsal surface of the crura (pedunculi) cerebri are the corpora quadrigemina (colliculi) supported by the lamina quadrigemina covering in the aquaeductus cerebri (Sylvius). Upon cross section, each crus (peduncle) will be found to consist of two portions which are separated from each other by a darker colored portion called the substantia nigra, the portion that is in front of or ventral to the substantia nigra is the Crusta or Pes (Basis Pedunculi) Cerebri; the portion that is behind or dorsal to the substantia nigra is the Tegmentum. The Crusta (Basis Pedunculi) Cerebri constitutes the anterior or ventral part of the crura (pedunculi) cerebri. It is composed entirely of longi- tudinal fibres which descend from the cerebral hemisphere (corticifugal fibres) most of which are continuous with the pyramidal tracts of the medulla. Three principal tracts or bundles are recognized: ist, pyramidal tracts in the middle and inner portions of the crusta, the inner part being the geniculate fasciculus and the outer the pyramidal tracts proper; 2d f cortico-pontine; and 3d, caudate-cerebellar tracts. 196 HUMAN ANATOMY The pyramidal (cerebro-spinal) tracts are direct motor strands com- posed of descending cortico-spinal projection fibres which originate in the following way. As the axis-cylinder processes descend from cells in the precentral cerebral cortex, they form the corona radiata by converging as they approach the internal capsule. They then proceed through the genu and the anterior two-thirds of the posterior limb (pars ocdpitalis} of the internal capsule to be continued as the pyramidal tracts in the crusta (basis) of the crus (pedunculus) cerebri. Here they are differentiated into an inner and an outer portion. The inner portion is the part of the pyramidal tract that came down through the genu of the internal capsule, it is continued as the gen- iculate fasciculus, the fibres of which terminate in the nuclei of the 5th, yth, and i2th cranial nerves. The outer portion of the pyramidal tract is the part that traversed the anterior two-thirds of the pars ocdpitalis (posterior limb) of the in- ternal capsule, it is continued as the, i. Pyramidal Tract Proper through the pons Varolii into the anterior pyramid (ventral area) of the medulla where its fibres are differenti- ated into three strands, the crossed, the direct, and the uncrossed. Crossed Pyramidal Tract (fasciculus cerebro-spinalis lateralis). Most of the fibres of the pyramidal tract proper decussate in the medulla (inferior pyramidal motor decussation) and are then con- tinued downwards as the crossed pyramidal tract (lateral cerebro- spinal fasciculus) in the lateral column (funiculus lateralis) of the spinal cord (medulla spinalis), on the side opposite to that of their origin, to ultimately become connected with the anterior roots of the spinal nerves. Direct Pyramidal Tract (fasciculus cerebro-spinalis anterior) or fasciculus of Tiirck, is composed of fibres of the pyramidal tract proper which do not decussate in the medulla but continue downwards in anterior column (funiculus anterior) of the spinal cord (medulla spinalis), on the same side as that of their origin, where at various levels its fibres cross through the gray matter of the cord to become connected with anterior nerve roots of the opposite side. Uncrossed Pyramidal Tract comprises those fibres of the pyramidal tract proper which do not decussate either in the medulla or in the cord but continue downwards in the lateral column (funiculus lateralis) of the spinal cord (medulla spinalis), on the same side as that of their origin, where they mingle with the fibres of the crossed pyramidal tract (fasciculus cerebro-spinalis lateralis) and become connected with anterior nerve roots on the same side as that of their origin. THE BRAIN IQ7 2. The Cortico-pontine Tracts are the first link of the neurone chain constituting the indirect motor tract, the complete series being cerebral cortex; cortico-pontine tract; nucleus points; cerebellar cortex; dentate nucleus; superior peduncle (brachium conjunctevum) of cerebellum; red nucleus (nucleus ruber); rubro-spinal tract; spinal gray matter; spinal nerve to muscle. There are two groups of cortico-pontine fibres, Fr onto- p online tract, during its passage through the cerebral peduncle lies medial to the geniculate fasciculus of the pyramidal tract. Origi- nating in the mid-frontal cortex, its fibres pass through the back part of the anterior limb (pars frontalis) of the internal capsule con- tinuing by way of the crusta (basis) pedunculi cerebri to the nucleus pontis. Temporo-pontine tract which lies posterior and lateral to the principal portion of the pyramidal tract during its course through the crus (pedunculus) cerebri. Originating in the cortex of the two lowermost temporal gyri, its fibres pass inwards under the lenticular (lentiform) nucleus, traverse the postero-inferior part of the posterior limb (pars occipitalis) of the internal capsule, continuing by way of the crusta (basis) of the crus (pedunculus) cerebri to the nucleus pontis. 3. Caudate-cerebellar Tract (stratum intermedium) occupies the interval ""between the substantia nigra which is posterior, and the pyramidal and cortico-pontine tracts which surround it in front and laterally. It is made up of fibres running from the caudate nucleus to the cerebellum. Substantia Nigra, is a dark band of pigmented gray matter, semi- lunar in cross section. It divides the basilar (crusta) portion of the cerebral peduncle (crus) from the tegmental portion. Tegmentum, of the cerebral peduncle (crus) consists of network of transverse and longitudinal fibres among which are enmeshed many scattered nerve cells and two well-defined clusters of nerve cells. The gray matter (substantia grisea) of the tegmentum is continu- ous with the formatio reticularis of the pons and medulla, the prin- cipal nuclear clusters are, 1. Stratum Griseum Cenlrale, which is the gray matter surrounding the aquasductus cerebri (Sylvius). 2. Red Nucleus (nucleus tegmenti ruber), consists of multi-polar cells, it is situated beneath the anterior corpus quadrigeminum (colliculus superior). It is the termination of the superior cerebellar peduncles (brachia 198 HUMAN ANATOMY conjunctiva). Some of the fibres originating in it run up to the ventro-lateral nucleus of the thalamus, others descend in the rubro- spinal tract. While Matter (substantia alba), of the tegmentum consists both of transverse and longitudinal fibres. Its transverse fibres mostly enter into the formation of oculo-motor and trochlear nerves, q. v. Its longitudinal fibres are mostly sensory and ascend towards the brain cortex (corticipital). They are differentiated into the follow- ing main bundles. i. Medial Lemniscus (medial fillet). The tegmental and pontine portion consists of ascending (corticipital) sensory nerve fibres after they have emerged from the superior pyramidal sensor.y decussation which is just above the nucleus gracilis and nucleus cuneatus in the back part of the medulla oblongata. They convey sensory impulses from muscles, bones, and joints. The medial lemniscus is formed by the combination of fibres arising from the nuclei of the fasciculus gracilis and fasciculus cuneatus. They originate in the following way, The sense-organs in muscles, bones, and joints are connected by the peripheral processes (dendrites) to the ganglion cells (ist neurones of the chain) in the ganglia on the posterior roots of the spinal nerves, by way of which, the central processes (axones) of those cells enter and then run upwards in the posterior column (funiculus posterior) of the spinal cord (medulla spinalis) on the same side as that of their origin. All those coming from spinal nerves below the 8th thoracic, are combined to form the Fasciculus Gracilis (column of Goll) occupying the medial portion of the posterior column (funicu- lus posterior) of the cord, in which position it continues as it runs upwards to the medulla where it terminates in an expansion enclosing the nucleus gracilis, this upper portion being known as the clava. The Fasciculus Cuneatus (column of Burdach) originates in exactly the same way from all of the spinal nerves above the Qth thoracic. It runs upwards, laterally to the fasciculus gracilis, in the posterior column (funiculus posterior) of the cord until it reaches the medulla in which it terminates as an expansion enclosing the nucleus cuneatus. The 2d neurones of the chain after leaving the nucleus gracilis or nucleus cuneatus, may go by way of the inferior cerebellar peduncle (corpus restifcrme) to the cerebellar cortex of the opposite side, or they may decussate in the medulla (superior Pyramidal sensory decussation) and then proceed as medial lemniscus or fillet by way of the pons through the tegmentum of the crus (pediculus) cerebri of the side opposite to that of their origin; then through the thalamus, THE BRAIN 1 99 or through the posterior limb (pars occipitalis) of the internal capsule, to the cerebral cortex. 2. Lateral Lemniscus (lateral fillet), is the upward continuation of the cochlear division of the central auditory tract. Its fibres are derived in the following way, The cochlear nerve arises from the cen- tral processes of the T-shaped cells (ist neurone of the chain) in the spiral ganglion of the cochlea, it then passes backwards and enters the medulla, beneath the lower border of the pons on the outer side of the restiform body. Its fibres then divide into ascending and descending branches. The fibres of the ascending branch terminate in the cells of the ventral cochlear nucleus, which lies in front of the restiform body in the interval between the cochlear and vestibular divisions of the auditory nerve (n. acusticus). The fibres of the descending branch terminate in the cells of the dorsal cochlear nucleus, which lies beneath the trigonum acusticum, behind the restiform body and between it and the flocculus of the cerebellum. The axones of the cells (2d neurone) in the dorsal and ventral cochlear nuclei form two bundles, of which the dorsal bundle or striae medullares cross the floor of the 4th ventricle to the medial plane in which they penetrate the tegmentum and decussate, some of the fibres entering the lateral lemniscus of the opposite side, others enter- ing the trapezoid body (corpus trapezoideum). The axones in the ventral bundle (trapezia!) enter the trapezoid body where some of them terminate in the large cells (3d neurone) constituting the nucleus trapezoideus. Most of these trapezial axones decussate before terminating in the superior olive. The axones leaving the superior olive (4th neurone) are joined by the axones of the dorsal bundle (strife medul- lares) so constituting the lateral lemniscus (lateral fillet) which bends upwards and is again interrupted by the nucleus lemnisci lateralis (5th neurone) whence it proceeds by way of the tegmentum to the nucleus of the posterior quadrigeminal body (colliculus inferior) (6th neurone) and to the medial geniculate body (;th neurone) from which arise axones that pass through the sub-lenticular portion of the internal capsule, then by way of the temporal portion of the corona radiata to the auditory area in the cortex of the superior and transverse temporal gyri. A few fibres reach the posterior corpora quadrigemina (colliculi inferiores) without having decussated. 3. Ventral Longitudinal Fasciculus (tecto-spinal or mesencephalo- spinal tract, or sulco-marginal fasciculus), is composed of axones descending from the anterior corpora quadrigemina (colliculi supe- riores). These fibres immediately commence to decussate ( optic 200 HUMAN ANATOMY acoustic reflex path") and as they descend, continue to decussate through the medial raphe on each side of which they lie. During the course of this tract through the pons and medulla many of its fibres terminate in the nuclei of all of the motor cranial nerves, the tract it- self enters the anterior column (funiculus anterior medullas spinalis) of the cord on the side opposite to that of its origin. Continuing down- wards, between the direct pyramidal tract (ventral cerebro-spinal fasciculus) and the anterior medial fissure, its fibres terminate in cells of the anterior horn (columna anterior). 4. Medial Longitudinal Fasciculus (posterior longitudinal bundle), is composed mostly of short association fibres. It originates in a special nucleus of its own that is situated in that part of the floor of the 3d ventricle which is immediately behind, or above, the corpora albicantia (corpora mammillaria); it passes downwards, close to the mid-line, between the medial lemniscus (medial fillet) and the gray matter (substantia griesea centralis) of the aquaeductus cerebri (Sylvius), where it becomes intimately connected with the nuclei of the 3d, 4th, and 6th cranial nerves, and the cells of the anterior corpus quad- rigeminum (colliculus superior) It continues downwards close to the mid-line immediately in front of the gray matter forming the floor of the 4th ventricle where it becomes connected with the nuclei of the 7th and vestibular portion of the 8th cranial nerves. It gives off and receives many collaterals in the formatio (substantia) reticularis as it traverses the pons and medulla in order to enter the anterior column (funiculus anterior medullae spinalis) of the cord where its fibres terminate in the cells of the anterior horn (columnae anterior). This tract seems to be made up mostly of fibres which have decussated. Throughout its entire course it always lies close to the mid-line immediately in front of the central gray matter, of whatever structure it traverses. 5. Spino-thalamic Tract, is composed of direct ascending fibres which transmit sensation of pain, heat and cold, pressure and touch, from the skin on one side of the body to the opposite side of the brain. The sensory end-organs of the skin are connected with the peripheral processes (dendrites) of cells in the ganglia of the posterior roots of the spinal nerves. The central processes (axones) of these cells are connected with cells in the gray matter of the posterior horn (columna posterior) of the cord (medulla spinalis) from which axones pass forwards and cross by way of the anterior white commissure to the opposite side of the cord (medulla spinalis) where they ascend, at first loosely scattered, in the antero-lateral funiculus, they ultimately THE BRAIN 2OI become condensed into a distinct tract or fasciculus which ascends in the lateral side of the medulla, continues upwards through the pons, medial to the olivo-cerebellar and rubro-spinal tracts, then, along with the medial lemniscus, it traverses the tegmentum and the posterior limb (pars occipitalis) of the internal capsule to terminate in the thalamus. 6. Superior Peduncles (brachia conjunctiva) of the Cerebellum, consists of fibres originating in the dentate nuclei of the cerebellum. They are two white bands, a right and a left, which emerge, widely apart, from the front of the cerebellum. As they run upwards and for- wards they converge forming the lateral boundaries and a small por- tion of the roof of the front or upper half of the 4th ventricle. They join each other in the mid-line, decussate and then pass upwards under cover of the posterior pair of corpora quadrigemina (colliculi inferiores) each one terminating in the red nucleus (nucleus tegmenti ruber) of the side opposite to that of its origin. 7. Rubro-spinal tract (pre-pyramidal or Monakow's tract), is a descending crossed motor strand which seems to be the downward continuation of some of the fibres of the superior peduncles (brachia conjunctiva) of the cerebellum which having come from the dentate nucleus and crossed to the red nucleus of the opposite side, are by means of the rubro-spinal tract connected to their original side of the spinal cord. The fibres of the rubro-spinal tract originate in the red nucleus (nucleus tegmenti ruber) just beneath the anterior corpus quadrigeminum (colliculus superior) they cross the medial plane to the opposite side, descend close to the lateral lemniscus behind the trapezium in the pons, becoming superficial in the medulla, where they lie in the furrow of the lateral area or pyramid between the olive and the spinal tract of the trigeminal nerve, they enter the lateral column (funiculus lateralis) of the spinal cord (medulla spinalis) where they continue downwards immediately in front of the crossed pyramidal tract (fasciculus cerebro-spinalis lateralis) which is in- vaded by some of the fibres, the others terminating in the cells of the anterior horn (columna anterior). 8. Descending (Mesencephalic) Root of the Trigeminal Nerve, enters into the composition of the Masticator Nerve (motor portion of the fifth). Its fibres originate in the giant pyramidal cells in the lower part of the somaesthetic (sensory-motor) area of the cerebral cortex. These pyramidal fibres traverse the genu of the internal capsule, continue through the tegmentum, medial to the superior peduncle (brachium conjunctivum) of the cerebellum, then decussate before 202 HUMAN ANATOMY terminating in accessory motor nucleus of the fifth nerve. This nucleus is also known as the Mesencephalic Nucleus of the Masticator Nerve, it is a column of gray matter lateral to the gray matter (stra- tum griseum centrale) surrounding the cerebral aqueduct (Sylvius). 9. Olivary Fasciculus (thalamo-olivary or central tegmental tract), is composed of fibres that originate both in the lenticular (lentiform) nucleus and the thalamus, traverse the central portion of the tegmen- tum and continue in the pons, behind the medial lemniscus in the formatio reticularis to the inferior olivary nucleus, being continued from the olive to the opposite cerebellar hemisphere by way of the cerebello-olivary fibres. Corpora Quadrigemina (colliculi) are 4 rounded eminences placed in pairs, 2 in front and 2 behind, on the dorsal surface of the mid-brain (mesencephalon) immediately behind the 3d ventricle and beneath the posterior border of the corpus callosum. All 4 collectively are often called the Tectum or Tectum Mesencephali, e.g., in names such as u teclo-spinal. n The upper or anterior pair were called the nates (colliculi superiores), the lower pair the lestes (colliculi inferiores). They are connected by 4 bands, the brachia, with the corpora geniculata, those of the anterior corpora quadrigemina (colliculi superiores) being continued directly into the optic tract. They are composed of white matter externally and gray matter internally. The anterior pair contain the Stratum Zonale, a thin stratum of white matter on the surface. Stratum Cinereum (stratum griseum colliculi superioris), next below, a layer of gray matter. Stratum Opticum, the upper gray- white layer, having many fine nerve- fibres intersecting the gray matter. Stratum Lemnisci, the deep gray-white layer, consisting of nerve- fibres and nerve-cells of large size. Aqueduct of Sylvius, or Her a tertio ad quartum ventriculum (aquaeductus cerebri) is a narrow canal, about ^ inch long, connecting the 3d ventricle with the 4th, and situated between the corpora quadrigemina (colliculi) and the tegmentum. It is surrounded by a layer of gray matter (stratum griseum centrale) which is continuous with the gray matter of the 3d and 4th ventricles, and contains groups of cells which are connected with the roots of the 3d, 4th and 5th cranial nerves. The Hypo-thalamic Region (right or left), is the forward prolongation of the tegmentum becoming blended with the under surface of the thala- mus, it consists mainly of the upward and forward production of the red nucleus (nucleus tegmenti ruber), medial lemniscus (fillet), and the sub- THE BRAIN 203 stantia nigra which is here expanded laterally by an additional cluster of nerve cells forming the Nucleus Hypothalamicus. The Rhombencephalon morphologically comprises: i. isthmus rhom- bencephali, 2. metencephalon, and 3. myelencephalon. Isthmus Rhomb encephali (isthmus of the hind-brain) comprises: a. Superior Peduncles (brachia conjunctiva) of the cerebellum (see page 201). b. Superior Medullary Velum (valve of Vieussens) is triangular in shape with the apex pointing forwards. It forms the roof of the anterior or upper half of the 4th ventricle by filling up the interval between the two superior peduncles (brachia conjunctiva) of the cerebellum. It consists of a lamina of white matter which is crossed on its upper surface by several transverse bands of gray matter which collec- tively are known as the lingula cerebelli. The Metencephalon or the Hind-brain, comprises the pons Varolii, the Cerebellum, and the upper half of the 4th Ventricle. The latter is described with its lower half, under the Medulla Oblongata, in the next section. FIG. 73. 13 17 The Pons Varolii (6), is the bond of union of the various parts of the brain, connecting the cerebrum with the cerebellum (3) and the medulla oblongata (9). It is about i^ inch wide and i inch long and thick, and is situated between, the hemispheres of the cerebellum above the medulla oblongata and below the crura (pedunculi) cerebri. It consists of a ventral or anterior portion (pars ventralis) (7), containing layers of trans- ) 4 jj 4 2CH HUMAN ANATOMY verse and longitudinal fibres, also a small quantity of gray matter, a tegmental, dorsal, or posterior portion (pars dorsalis), which is a continua- tion of the reticular formation of the medulla, most of its constituents being continued into the tegmentum of the crura (pedunculi) cerebri. The Gray Matter of the Pons consists of the following important collections of nerve-cells: Superior Olivary Nucleus (nucleus olivarius superior), an isolated mass of gray matter situated on the dorsal surface immediately above the inferior olivary nucleus (nucleus olivarius inferior) of the medulla. Nuclei of the $th Nerve 2, one for the motor (12) and one for the sensory root (13), the latter external to the former. Nucleus of the 6th Nerve, beneath the floor of the 4th ventricle, close to the root of the facial nerve; its fibres pass through the pons and emerge at its lower margin (14). Nucleus of the Facial (jth) Nerve, situated deeply below the floor of the 4th ventricle; its roots follow a tortuous course in the pons, emerging at its lower border (15), external to those of the abducent nerve. Nuclei of the Auditory (Sth) Nerve 2, are dorsal and ventral, both lying chiefly in the medulla but prolonged into the pons; the roots emerging at its lower border (17), in the groove between the olivary body (oliva) and the restiform body (corpus restiforme). Nuclei Pontis, small masses of gray matter in the ventral or anterior portion of the pons. Substantia Gelalinosa (of Rolando), which is continuous with that of the spinal cord and medulla. Locus Cceruleus, a slate-colored bluish spot on the upper part of the floor of the 4th ventricle. The White Matter of the Pons consists of 4 sets of medullated nerve fibres, superficial transverse, superficial longitudinal, deep transverse and deep longitudinal. The Superficial Transverse Fibres, are on the ventral surface of the pons, they continue laterally into the middle peduncles (brachia pontis) of the cerebellum. The Superficial Longitudinal Fibres of the pons comprise, 1. Upward continuation of the anterior pyramids (ventral area) of the medulla (see page 209). 2. Cortico-pontine Tracts (see page 197). 3. Stratum Intermedium or Caudate-cerebellar Tract (see page 197). The Deep Transverse Fibres, form the trapezium (corpus trapezoideum) and then pass laterally into the middle peduncles (brachia pontis) THE BRAIN 205 of the cerebellum (see lateral lemniscus, page 199, and acoustic nerve, page 220). The Deep Longitudinal Fibres, of the pons constitute a portion of the reticular formation in which the following distinct bundles can be traced, 1. Olivary Fasciculus, Thalamo-olivary or Central Tegmental Tract (see page 202), lies in the reticular formation dorsal to the medial lemniscus. 2. Descending or Mesencephalic Root of the Trigeminal Nerve (see page 201). 3. Fasciculus Teres, is composed of fibres of the facial nerve which, by looping upwards behind the nucleus of the abducens nerve and then running forwards and upwards, forms the eminentia teres or medialis (colliculus facialis) which lies in the floor of the anterior or upper half of the 4th ventricle, immediately lateral to the mid-line. 4. Medial Lemniscus or Fillet (see page 198), which comprises the fasciculus gracilis (column of Goll) and the fasciculus cuneatus (column of Burdach). 5. Lateral Lemniscus or Fillet (see page 199), composed of the cochlear fibres of the central auditory path. 6. Ventral Longitudinal or Sulco-marginal Fasciculus (Tecto-spinal or Mesencephalo-spinal Tract) (see page 199). 7. Medial Longitudinal Fasciculus (Posterior Longitudinal Tract) (see page 200). 8. Rubro-spinal Fasciculus (Pre-pyramidal or Monakow's Tract) (see page 201). 9. Ascending Antero-lateral Tract of Cowers, comprises a direct and an indirect path through which sensation of pain, temperature, pressure, and touch reaches the brain. a. Spino-thalamic Tract is the direct path (see page 200). b. Ventral Spino-cerebellar Tract (Superficial Ventro-lateral Spino-cerebellar Fasciculus) is the indirect path. The term "Cowers' Tract" is limited by some to this tract only. It originates in the following way, the sensory end organs are con- nected with the peripheral processes (dendrites) of cells in the ganglia of the posterior roots of spinal nerves, the central proc- esses (axones) of these cells are connected with cells in the base of the lateral horn (columna lateralis), known as"Stillings' Nucleus," and with cells in the lateral horn (columna lateralis) of the spinal cord (medulla spinalis). The axones of these cells, both of the same and the opposite side, are agminated into a 206 HUMAN ANATOMY bundle, the Ventral Spino-cerebellar Tract (Superficial Ventro- lateral Spino-cerebellar Fasciculus) which travels upwards in the lateral column (funiculus lateralis) of the spinal cord (medulla spinalis). It maintains this position as it traverses the medulla until it reaches the pons where it runs forwards and upwards as high as the level of the trigeminal nerve, it then runs backwards and downwards, enters the superior peduncle (brachium conjunc- tivum) of the cerebellum, and terminates in the lingula of the superior vermis cerebelli of its own side. The Cerebellum consists of gray matter (substantia corticalis) on the surface and white matter (corpus medullare) in the interior. Its surface is not convoluted like that of the cerebrum, but is traversed by curved fissures and furrows (sulci), the latter separating the laminae (folia or gyri) of which it is composed. It lies in the inferior occipital fossae of the skull, beneath the occipital lobes of the cerebrum, from which it is separated by a process of dura mater, the tentorium cerebelli. It is divided into a cen- tral portion or lobe, the Vermis Cerebelli or Vermiform Process (i), and two lateral Hemispheres; all continuous with each other and- substantially the same in structure. It presents the following primary fissures: Great Horizontal Fissure (10), horizontally round the free margin, from the pons in front to the median line behind, giving origin to the secondary fissures. Incisura Cerebelli Anterior, or Anterior Cerebellar Notch, a broad, shallow, vertical notch, separating the hemispheres in front. Incisura Marsupialis (2), or Posterior Cerebellar Notch, a deep notch, separating the hemispheres from each other behind. Vallecula, a deep depression on the inferior surface, containing the lower extremity of the vermis (vermis inferior). Secondary Fissures of the Cerebellum are 8 in number, 4 superiorly and 4 inferiorly. They pass in a curved direction from side to side across the cerebellum, beginning (except one) and ending in the great horizontal fissure. They are named from before backward as follows: On the upper surface of the cerebellum, the Pre-central. Post-central. Anterior Semilunar or Pre-clival. Posterior Semilunar or Post-clival. On the lower surface of the cerebellum, the Post-nodular. Retro-tons illar or Pre- pyramidal. Anterior Inferior or Post-pyramidal. Posterior Inferior or Post-gracile. The post-gracile is a branch of the post-pyramidal, and ends in the great horizontal fissure. THE BRAIN 207 Lobes of the Cerebellum. The 3 primary lobes, the Vermis or Worm and the Hemispheres, are divided by the above-named secondary fissures into 19 lobes, named as follows: On the upper surface of the Worm (vermis superior), from before backward 5, the Lingula. Lobulus Centralis. Culmen Monticuli. Diclive or Clivus Monticuli. Folium Cacuminis or Commissura Simplex. On the upper surface of the Hemispheres, from before backward 5, the Vinculum Lingualce or Freenulum. Ala Lobuli Centralis. A nterior Semilimar or Crescentic Lobe. Posterior Semihmar or Crescentic Lobe. Superior Semilunar or Posterior Superior Lobe. On the lower surface of the Worm, from before backward 4, the Nodule. Uvula. Pyramid. Tuber Valvula. On the lower surface of the Hemispheres, from within outward 5, the Flocculus (5). Tonsil or Amygdala (4). Biventral Lobe (3). Cradle or Slender Lobe (3). Inferior Semilunar Lobe (3). White Matter (Corpus Medullare) of the Cerebellum includes the peduncular fibres and the fibres proper. The former are projection fibres and are arranged in 3 peduncles on each side, which arise from the anterior part of the hemispheres, and connect the cerebellum with itself and with the rest of the brain, as follows: Superior Peduncles (brachia conjunctiva), in part form the roof of the 4th ventricle; they pass from the corpus dentatum under the corpora quadrigemina, below which their fibres decussate, going to the red nucleus of the tegmentum, and by a relay through the optic thalamus to the cerebral cortex. Stretching from one peduncle to the other is the Valve of Vieussens, or Superior Medullary Velum (see page 203), a thin lamina of white matter, which with the superior peduncles forms part of the roof of the 4th ventricle (see page 211). Middle Peduncles (brachia pontis) (8), comprise most of the transverse fibres of the pons, and are chiefly commissural fibres connecting the cerebellar hemispheres with each other. All are connected with the nucleus pontis of the same or the opposite side, those that are not commissural are the continuation of the cortico-pontine tracts (see page 197). Inferior Peduncles (corpora restiformes), connect the cerebellum with the medulla oblongata. Fibra Proprice, the proper fibres of the cerebellum, are of 2 kinds; the 208 HUMAN ANATOMY commissural, connecting the hemispheres, and the association or arcuate fibres, connecting adjacent laminae. Cortical Gray Matter (Substantia Corticalis) of the Cerebellum is situated on the surface, forming the cortex, a section of which presents a characteristic foliated appearance, named the Arbor Vita, due to the branching of the laminae given off from the central white matter to the cortical portion. The gray matter of the cortex consists of three layers, as follows: Molecular or External Gray Layer, consists of fibres and cells. Middle Layer Containing the Cells of Purkinje, (the characteristic cells of the cerebellum), an incomplete stratum of flask-shaped cells, their bases resting on the granular layer, their necks giving off numerous dendrites to the molecular layer. Granular or Internal rust-colored Layer of Turner, contains numerous small nerve-cells or granules of reddish-brown color, also many nerve- fibrils, among which are the axones of the Purkinje cells. This layer also contains larger cells, known as the Golgi cells, situated in its outer part. Central Gray Matter of the Cerebellum is disposed on each side in 4 centres, one of which, the dentate nucleus is large; the others being of small size. They are situated in the middle of the white matter of the organ, and are as follows: the Dentate Nucleus, or Ganglion of the Cerebellum, an irregularly folded lamina of gray matter, having an opening anteriorly, the hilum, from which emerge most of the fibres of the superior peduncle (brachium conjunct! vum.) Nucleus Emboliformis, lies to the inner side of the dentate nucleus, partly covering its hilum. It is probably part of the dentate nucleus. Nucleus Globosus, an elongated mass on the inner side of the preceding. Nucleus Fastigii, or Roof Nucleus of Stilling, is close to the middle line at the anterior end of the vermiform process (vermis) and imme- diately over the roof of the 4th ventricle. The fibres of the ves- tibular nerve terminate in this nucleus after having decussated in the vermis. THE MEDULLA OBLONGATA The Medulla Oblongata, or Myelencephalon, formerly called the Spinal Bulb, is thelowermost division of the brain and is continuous with the spinal cord. It extends from the lower margin of the pons Varolii (5) to the inferior pyramidal (motor) decussation (12) corresponding to the lower mar- gin of the foramen magnum. Its ventral surface rests on the basilar THE BRAIN 209 groove of the occipital bone, its dorsal surface is in the fossa between the cerebellar hemispheres. It is i inch long, % inch broad above, and ^ inch thick; and of pyramidal form, its broad end upward. On its surface are the anterior and posterior median fissures; the former terminating just below the pons in a cul-de-sac, the foramen ccecum; the latter expanding into the 4th ventricle about the middle of the medulla. On each side the medulla presents the following parts: Pyramid (7), a bundle of white matter alongside the anterior median fissure, formed by the upward continuation of the direct tract (fas- ciculus cerebro-spinalis anterior) of the anterior column (funiculus anterior) and the crossed tract (fasciculus cerebro-spinalis lateralis) of the lateral column (funiculus lateralis) of the spinal cord. As the latter tract ascends it decussates with its fellow of the opposite side across the fissure, forming the inferior decussalion of the pyramids (8). Each pyramid is bounded by the antero-lateral sulcus which is continuous with that of the cord. Olive (Olivary Body) (9), an ovoid projection on the outer side of the pyramid and immediately below the pons. In the groove between the olive and pyramid, the hypoglossal nerve fibres (27) emerge; in that between the olive and restiform body (inferior cerebellar peduncle) emerge the glosso-pharyngeal (24), pneumogastric (n. vagus) (25) and spinal accessory (n. accessorius) (26) nerves. The Inferior Olivary Nucleus or corpus denlatum is a thin, wavy lamina of gray matter, open at its upper and inner part. Three accessory nuclei (dorsal, medial and lateral) are also situated in the olive. Fasciculus of Rolando (10), a slight, longitudinal prominence on the outer side of the olivary body. It corresponds to a mass of gray matter, substanlia gelatinosa, continuous with the posterior horn of the gray matter of the cord. Lateral Column, hidden above by the olivary body but showing below it; is the continuation of the lateral column (funiculus lateralis) of the cord in part. Restiform Body (inferior cerebellar peduncle), between the lateral 14 210 HUMAN ANATOMY column and the fasciculus cuneatus; contains the arcuate fibres, external and internal, and the dorsal spino-csr Cellar fasciculus (direct cerebellar tract). The two restiform bodies diverge as they ascend, assist in forming the lateral walls of the 4th ventricle, and enter the cerebellar hemispheres as the inferior peduncles of the cerebellum. Dorsal S pino-cerebellar Fasciculus (direct cerebellar tract of Flechsig), arises from cells in the dorsal nucleus (Clark's column) which occu- pies the base (cervix) of the posterior horn (columna posterior) of the cord from the level of the 3d lumbar to that of the 7th cervical nerve. The axones arising in these cells pass to the dorso-lateral periphery of the lateral column (funiculus lateralis) up which they continue until they reach the medulla, then they run up behind the origins of the Qth, loth and nth cranial nerves, and then bend out- wards and forwards, entering the restiform body (inferior cerebellar peduncle) in which they continue to the cells in the cortex of the cerebellar hemisphere of th2 same side as that of their origin. External or Superficial Arcuate Fibres, are in two sets. The anterior set of fibres are the more numerous, they arise from cells in the nucleus gracilis and nucleus cuneatus, run forwards, and decussate in the medial raphe, emerge in the anterior medial fissure and run outwards across the surface of the pyramid and lower part of the olive, then turn upwards and enter the restiform body (inferior cerebellar peduncle) of the side opposite to that of their origin. The posterior set of fibres also arise from the cells in the cuneate and gracile nuclei; they run outwards, forwards, and upwards directly into the restiform body (inferior cerebellar peduncle) of the same side as that of their origin. Internal or Deep Arcuate Fibres form an intricate network situated between the olives and behind the pyramids. Some of these fibres, the olivo-cerebellar and cerebello-olivary : , enter the restiform body (infe- rior cerebellar peduncle) . The remaining fibres are association or com- missural fibres connected with the nuclear cells in the formatio reticularis of the tegmentum and the nuclei of the sensory cranial nerves. Fasciculus Cuneatus, between the restiform body and the funiculus gracilis; is the continuation of the postero-lateral column of the cord (see lateral lemniscus, page 198). Fasciculus Gracilis (posterior pyramid), a narrow, white band, parallel to and alongside the posterior fissure; is the continuation of the pos- tero-median column of the cord. Its enlarged upper extremity is club-shaped and called the clava (see lateral lemniscus, page 198). THE BRAIN 211 Other Structures in the Medulla. Internally the medulla is composed of longitudinal bundles of nerve-fibres, masses of gray matter constituting nerve nuclei, and nerve-fibres originating from the nuclei. The Independent Nuclei, are those of the 5th, 8th, gih, loth, nth and i2th cranial nerves, which arise in or near the floor of the 4th ventricle; also the nucleus of the fasciculus teres (eminentia medialis or teres), that of the olivary body, the accessory olivary nuclei, and the tractus solitarius or trineural tract, the ascending root of the gth nerve. Raphe or Medial Septum, is situated in the middle line of the medulla above the decussation of the pyramids, and consists of fibres having different directions and of multipolar nerve-cells. Formatio Reticularis, is a coarse network, situated within the anterior and lateral regions of t^e medulla, and is formed by the breaking up of the anterior gray matter by the white fibres of the crossed pyramidal (cerebro-spinal) tracts. The Fourth Ventricle, or Ventricle of the Cerebellum, is a diamond- shaped cavity lying between the cerebellum and the posterior surface of the pons Varolii and medulla oblongata. Its upper angle is on a level with the upper border of the pons, it corresponds with the lower opening of the cerebral aqueduct of Sylvius, by which this ventricle communicates with the 3d ventricle. Its lower angle is on a level with the lower border of the olivary body (oliva), it is continuous with the central canal of the spinal cord, and is called the calamus scriptorius, from its resemblance to the point of a pen. The ventricle is closed posteriorly by a layer of pia mater, the tela choroidea inferior, with its choroid plexuses, in which layer are 3 openings; the foramen of Magendie (metapore), just above the calamus scriptorius in the median line, and the foramina of Key and Retzius at the extremities of the lateral angles. Through these foramina the ventricles of the brain communicate with the subarachnoid space of the brain and spinal cord. The fourth ventricle is bounded as follows: Roof, is tent-shaped and formed by superior peduncles of the cere- bellum, the superior medullary velum or valve of Vieussens, the tela choroidea inferior (see above) and its choroid plexus, the obex, and the inferior medullary velum. Floor, is formed by the posterior surface of the pons above and the medulla below. It contains the median furrow, on each side of which are the fasciculus teres (eminentia medialis or colliculus facialis), striae acusticae (striae medullares), conductor sonorus (striae obliquae), fovea superior, fovea inferior, alacinerea, tuberculum acusticum, locus caeruleus, taenia violacea, and the eminences of origin of certain nerves (seepages 212 and 213). 212 HUMAN ANATOMY Laterally, in the upper part are the superior peduncles of the cere- bellum; in the lower part, the inferior peduncles (restiform bodies) fringed by the funiculi graciles, their clavae and the ligulae. Parts named above, and heretofore undescribed, are the Sulcus Longitudinalis Medianus, the vertical median fissure; from the centre of which on each side emerge the Strife Medullares or Stria Acusticce, white fibres crossing the floor of the ventricle transversely, dividing it into two triangles, and passing outward to the auditory nerve. They are the axons of the nerve- cells of the tuberculum acusticum. Conductor Sonorus (striae obliquae), a whitish band of fibres in no way differing from the striae medullares except that they run from the mid- line obliquely outward and forward instead of transversely. They are not constant. Inferior Medullary Velum, a thin layer of white matter, stretching over the ventricle toward its lateral angles. Obex and Lingula, 79> tributed to the mucous membrane of the mouth, Wharton's duct (ductus sub-maxillaris), and thesub-mandibular or sub-maxillary gland. Geniculate Ganglion (ganglion gen- iculi) (2) or Intumescentia Ganglio- formis (Plate 8), is a reddish, gangli- form swelling on the yth or facial nerve, situated in the aquasductus Fallopii (canalis facialis), above the tympanum and near the Gasserian ganglion (ganglion semilunare). It communicates with the spheno-pala- tine ganglion, the otic ganglion and the meningeal plexus of the sympathetic, by the 3 superficial petrosal nerves, which are seen on removing the Gasserian ganglion (ganglion semi- lunare) (7), as follows: Large Superficial Petrosal (3), passes through the hiatus Fallopii (hiatus canalis facialis), thence across the foramen lacerum medium to the Vidian canal (canalis pterygoidei) where it joins the large deep petrosal from the carotid plexus, to form the Vidian nerve (n. canalis pterygoidei), as which it goes to Meckel's ganglion (ganglion spheno- palatinum) (page 224), forming its motor root. Small Superficial Petrosal (4), immediately external to the preceding, going from the geniculate ganglion of the yth to the otic ganglion, lying directly over the tensor tympani muscle. External Superficial Petrosal (5), going from the 7th nerve to the sympathetic plexus on the middle meningeal artery (6). IS 226 HUMAN ANATOMY The Vidian Nerve (n. canalis pterygoidei) (Plate 8), is a short nerve of communication, between the facial and sympathetic on the one hand, and the spheno-palatine ganglion on the other, supplying that ganglion with its motor and vaso-motor roots. It is formed by the junction of the Large Superficial Petrosal, br. of the facial (p. 220), with the Large Deep Petrosal, br. of the carotid plexus (p. 237), which tunnels the cartilage filling in the foramen lacerum medium (p. 41). It then en- ters the Vidian canal (canalis pterygoidei) (p. 25) in the pterygoid process of the sphenoid bone, passing through which it finally joins the posterior part of the spheno-palatine ganglion (p. 224). Ganglia of the pth Nerve (Plate 9). The Jugular Ganglion (ganglion superius) is regarded as a segmentation from the petrous ganglion (gan- glion inferius) below. The Petrous Ganglion (ganglion inferius) is situated in a depression on the lower border of the petrous portion of the temporal bone. From it arise the filaments which connect the gth nerve with the loth and the sympathetic; and it communicates also with the yth nerve. Its branches of distribution are the tympanic, carotid, pharyngeal, muscu- lar, torisillar, and lingual branches of the gth nerve (see page 221). Ganglia of the loth Nerve (Plate 9). The Ganglion of the Root (gan- glion jugulare) is connected by filaments with the accessory portion (ramus internus) of the nth nerve, with the petrous (inferior) ganglion of the 9th, with the yth, and with the sympathetic. The Ganglion of the Trunk (ganglion nodosum) involves all the fibres of the nerve, as also the accessory portion (ramus internus) of the nth, which passes through it. It is connected with the 1 2th nerve, the superior cervical ganglion of the sympathetic, and the loop between the ist and 2d cervical nerves. THE SPINAL NERVES (NERVI SPINALES) The Spinal Nerves number 31 pairs, of which the cervical number 8, the thoracic 12, the lumbar 5, the sacral 5, and the coccygeal i. All the cervical nerves escape above the corresponding vertebrae except the 8th which emerges between the jth cervical and ist thoracic vertebrae, each of the others below the corresponding vertebrae, through the intervertebral foramina. Each nerve arises by 2 roots, an anterior motor root (effer- ent), and a posterior sensory one (afferent), the latter having a ganglion on it, the spinal ganglion, situated in the intervertebral foramen. The roots unite, and the spinal nerve thus formed divides into 2 divisions (rami), each having motor and sensory fibres. Just before this division takes THE SPINAL NERVES 227 place, each nerve gives off a minute gray ramus communicans, which after being joined by a branch of the sympathetic, re-enters the spinal canal and is distributed to the spinal cord (medulla spinalis) and its meninges, these are called recurrent meningeal nerves. The posterior divisions (rami) are small and generally unimportant; they supply the muscles and integument of the back. The anterior divisions (rami) supply the neck, front, and sides of the trunk, and the extremities; unit- ing in various regions to form plexuses, from which important nerve- trunks originate. Each anterior division (ramus), from 2d thoracic to 2d lumbar inclusive, is connected by a slender filament with the sympathetic. These are called splanchnic branches or "white rami communicantes ; there is a second set of them given by the 2d and 3d or by the 3d and 4th sacral nerves. THE CERVICAL NERVES The Cervical Nerves (Plate n), are 8 in number. The anterior divi- sions of the 4 upper form the cervical plexus; the anterior divisions of the lower 4, together with the ist thoracic, form the brachial plexus. The posterior division (ramus) of the ist cervical, the suboccipital nerve, differs from the others in not dividing into internal and external branches. It gives off a communicating branch, to the second cervical, and 5 muscular branches. The posterior division (ramus) of the 2d cervical is much larger than the anterior, it is called the Great Occipital (n. occipitalis magnus), a cutaneous nerve. The Cervical Plexus (plexus cervicalis) (Plate n), is formed by the anterior divisions of the upper 4 cervical nerves. It is situated opposite the upper 4 cervical vertebrae, resting on the levator anguli scapulae (m. levator scapulae) and scalenus medius muscles and covered in by the sterno- mastoid. Its branches number 10, of which the first 4 are superficial and the last 6 are deep, as follows: Occipitalis Minor (n. occipitalis minimus), ascending to the back of the side of the head. ( Facial, to the skin over the parotid gland. Auricularis Magnus \ Auricular, to the skin of the pinna, concha, etc. I Mastoid, to the integument behind the ear. Superficial Cervical (n. cutaneous colli), by 2 branches to the skin of the neck. 228 HUMAN ANATOMY Supraclavicular Suprasternal (nn. supraclaviculares anteriores), to the skin of that region. Supraclavicular (nn. supraclaviculares medii), to the skin over the pectoral and deltoid. Supra-acromial (nn. supraclaviculares posteriores), to the skin of the shoulder. Communicating, brs. to the loth (vagus), i2th (hypoglossal) and sympathetic nerves. Muscular, to the anterior recti and rectus lateralis muscles. Communicantes Hypoglossi 2, join the descendens hypoglossi nerve. Phrenic, is described below. Deep Communicating, to the spinal accessory nerve. Deep Muscular, to the sterno-mastoid, trapezius, levator anguli - ^scapulas (m. levator scapulae) and scalenus medius muscles. The Phrenic Nerve (nervus phrenicus), or Internal Respiratory of Bell, arises by 3 heads from the 3d, 4th, and 5th cervical, descends across the front of the scalenus anticus (m. scalenus anterior), crossing the sub- clavian and internal mammary arteries in the middle mediastinum, and is distributed to the inferior surface of the diaphragm. It sends filaments to the pericardium and pleura, and communicates with the solar and phrenic plexuses of the sympathetic in the abdomen. On the right side of the body it is situated more deeply, and is shorter and more vertical in direction than on the left side. In the thorax each phrenic nerve is accompanied by the comes nervi phrenici artery, a branch of the internal mammary. The Brachial Plexus (plexus brachialis) (Plate 12), is formed by the union of the anterior division of the four lower cervical nerves and the first thoracic. The 5th, 6th and 7th cervical unite into one trunk externally to the scalenus medius, as also do the 8th cervical and ist thoracic behind the same muscle. Below the line of the clavicle both these trunks bifur- cate; the two adjacent branches unite behind the axillary artery making the Posterior Cord, and the remaining 2 form the Outer (lateral) and Inner (medial) Cords, as referred to the artery. Each of these cords bifurcates, but the 2 adjacent branches of the outer and inner cords unite over the artery, to form the Median Nerve, leaving 4 other branches, the Ulnar, derived from the inner cord, iheMusculo-cutaneous (n. musculocutaneus), from the outer cord, and the Musculo-spiral (n. radialis) and Circumflex (n. axillaris) from the posterior cord. (See Plate 12.) THE BRANCHES of the brachial plexus are as follows: Above the clavicle are given off 4, the THE SPINAL NERVES 2 29 /J Communicating, completing the phrenic nerve. * / Musctttar, to The longus colli, scaleni, rhomboidei, and subclavius / muscles. The branch actuating the rhombcidei and levator anguli scapulae (n. levator scapulae) is sometimes called the posterior . scapular (n. dorsalis scapulae). / Posterior, or Long Thoracic (n. thoracalis longus), external respiratory ' nerve of Bell, -to the serratus magnus, arising from the 5th, 6th and . 7th cervical. / Suprascapular, from the ist trunk of the plexus, to the supra- and in- fra-spinatus muscles and the shoulder-joint. Below the clavicle are 12, namely, the /) Anterior Thoracic 2, external (lateral) and internal (medial) from the outer (lateral) and inner (medial) cords, to the pectoral muscles. Subsca pular 3, from the posterior cord, to the subscapularis, teres major and latissimus dorsi muscles. The long sw&scapular is also called nervus thoracodorsalis. 2, j Circumflex (n. axillaris), from the posterior cord, to the muscles and integument of the shoulder, and the shoulder-joint. JMusculo-cutaneous (n. musculocutaneus), from the outer cord, to the forearm externally, piercing the coraco-brachialis muscle. Its cutaneous branch is also called nervus cutaneus antibrachii lateralis. ' Internal Cutaneous (n. cutaneus antibrachii medialis), from the inner cord, to the arm and forearm. Lesser Internal Cutaneous (n. cutaneus brachii medialis) nerve of Wris- berg, from the inner cord, to the back of the arm. Is sometimes . wanting, sometimes connected with the intercosto-humeral. V : Median (n. medianus), from outer (lateral) and inner (medial) cords, passes between the two heads of the pronator radii teres (m. pronator teres), supplying the pronators, flexors, first 2 lumbricales, and the integument of the thumb, 2^ fingers, and the radial side of the palm. Its branches are all in the forearm, except its terminals in the palm of the hand, and are named the Muscular. Anterior Interosseous (n. interosseus antibrachii volaris). Palmar Cutaneous (n. ramus cutaneus palmaris n. mediani). . f Br. to thumb muscles. \ Digital, (nn. digitales volares communes) to thumb and index. J Digital (nn. digitales volares proprii) to thumb, and 2^ lntcrn.3,1 \ /. ( fingers. Ulnar, from the inner (medial) cord, passes between the two heads of 230 HUMAN ANATOMY the flexor carpi ulnaris at the inner condyle of the humerus, supplying the elbow- and wrist-joints, several muscles, and the palmar and dorsal integument of the little finger and half of the ring finger. Branches are the Articular (elbow). Dorsal Cutaneous. Superficial Palmar. Muscular. Articular (wrist). Deep Palmar. Cutaneous. . I Musculo-spird (n. radialis), from the posterior cord, accompanies the / superior profunda artery and vein in the spiral groove of the humerus, and in front of the outer (lateral) condyle it divides into the radial (ramus superficialis n. radialis) and posterior interosseous (ramus prof undus n. radialis) nerves. Its branches are Muscular (rami musculares n. radialis) divided into internal (medial) posterior, and external (lateral). Cutaneous (rami collaterals n. radialis) one internal (n. cutaneus brachii posterior) and two external (n. cutaneous brachii posterior, ramus proximalis et ramus distalis). Radial (ramus superficialis n. radialis) divides into an external and an internal branch, the latter giving off 4 digital, to the ulnar side of the thumb and the adjacent sides of 2^ fingers. Communicating branch to ulnar (ramus anastomoticus ulnaris). Posterior Interosseous (ramus prof undus n. radialis), supplies all the muscles of the radial side and back of the arm, except 3, also the liga- ments and articulations of the carpus. TABLE OF THE CORDS OF THE BRACHIAL PLEXUS Outer or Lateral Cord (superior) Musculo-cutaneous (n. musculotaneus) . derivation 5, 6, C. External (lateral) Anterior Thoracic derivation 5, 6, 7, C. Outer (lateral) head of Median 'derivation 6, 7, C. Inner or Medial Cord (inferior) Inner (medial) head of median derivation 8, C. i, T. Internal (medial) Anterior Thoracic.. . .derivation 8, C. i, T. Internal Cutaneous (n. cutaneus anti- brachii medialis) derivation 8, C. i, T. Lesser Internal Cutaneous (n. cutaneus brachii medialis) derivation i, T. Ulnar derivation 8, C. i, T. THE SPINAL NERVES 231 Posterior Cord Upper Subscapular derivation 5, 6, C. Long Subscapular (n. thoraco-dorsalis). derivation 5, 6, 7, C. Lower Subscapular derivation 5, 6, C. Circumflex (n. axillaris) derivation 5, 6, C. Musculo-Spiral (n. radialis) derivation 5,6, 7,8.C. (i, 7\). THE THORACIC NERVES (NERVI THORACALES) The Thoracic Nerves (Plate 12) are 12 in number on each side. Their posterior divisions pass backward beneath the transverse processes, and divide into internal and external branches, supplying the muscles and in- tegument of the back. Their anterior divisions, the intercostal nerves, are distributed to the walls of the thorax and abdomen, separately from each other, without plexiform arrangement. The upper 6, except the ist and the intercosto-humeral (intercosto-brachial) branch of the 2d, are lim- ited in their distribution to the parietes of the chest. The lower 6 supply the walls of the chest and abdomen, the last one sending a cutaneous fila- ment to the buttock. The Lateral Cutaneous nerves are derived from the intercostals, midway between the vertebrae and the sternum; they pierce the external intercostal and serratus magnus (m. serratus anterior) mus- cles, and divide into anterior and posterior branches. Peculiar among the thoracic nerves and their branches are the First Thoracic, divides into 2 branches, one entering into the brachial plexus, the other forming the ist intercostal nerve. Intercosto-humeral (n. Intercostobrachialis), is the lateral cutaneous branch of the 2d intercostal (anterior division of the 2d thoracic); it pierces the external intercostal muscle and crosses the axilla, joining with a filament from the lesser internal cutaneous (n. cutaneus brachii medialis) (nerve of Wrisberg), supplying the skin of the upper half of the inside and back of the arm, and communicating with the internal cutaneous (n. cutaneus brachii posterior) branch of the mus- culo-spiral nerve (n. radialis). Last Thoracic, is larger than the other thoracic nerves. Its anterior division runs along the lower border of the last rib, and communicates with the first lumbar nerve by the thoraco-lumbar branch, also with the ilio-hypogastric branch of the lumbar plexus. One of its branches, the Lateral Cutaneous- of the i2th Thoracic, is also of large size, and is dis- tributed to the integument over the front part of the gluteal region, some of its filaments extending as low as the trochanter major of the femur. 232 HUMAN ANATOMY THE LUMBAR NERVES The Lumbar Nerves are 5 in number on each side. Their roots are large and descend vertically in the spinal canal to reach their respective inter- vertebral foramina of exit. Their posterior divisions pass backward between the transverse processes, and divide into internal (medial) branches, supplying the deep muscles of the back; and external (lateral) branches are mostly cutaneous. Their anterior divisions pass outwardly behind the psoas magnus muscle or between its fasciculi. The anterior divisions of the upper 4 nerves are connected by anastomotic loops, form- ing the lumbar plexus; that of the 5th with a branch of the 4th forms the lumbo-sacral cord (truncus lumbosacralis), which joins with the anterior divisions of the upper 3 sacral nerves and part of the 4th to form the sacral plexus. (See Plate 14.) The Lumbar Plexus (plexus lumbalis) (Plate 14), is formed by loops from the 1 2th thoracic and the upper 4 lumbar nerves. It is situated in the substance of the psoas magnus muscle in front of the transverse processes of the lumbar vertebrae. Its branches are given off by the connecting loops, and are as follows: Ilio-hypo gastric, from the ist lumbar nerve, to the integument of the gluteal and hypogastric regions. Ilio-inguinal, from the ist lumbar nerve, gives off muscular branches to the internal oblique as it pierces it. It then accompanies the spermatic cord, or round ligament, divides into anterior scrotal or anterior labial to the integument of the upper and inner thigh and to the scrotum or labium majus. Genito-crural (genito-f emoral) , from the ist and 26. lumbar nerves, gives off genital branch (n. spermaticus externus), to the cremaster muscle or round ligament, and a femoral branch (n. lumbo-inguinalis) to the integument over the anterior superior part of the thigh. External Cutaneous (n. cutaneus femoris lateralis), from the 2nd and 3rd lumbar nerves, to the integument of the anterior, outer and pos- terior parts of the thigh. Obturator (n. obturatorius), from the 2nd, 3rd, and 4th lumbar nerves, through the obturator foramen, to the obturator externus and adduc- tor muscles of the thigh, the hip- and knee-joints, and occasionally the integument of the thigh and leg. Accessory Obturator (n. obturatorius accessorius) (often absent), from the 3rd and 4th lumbar nerves, to the pectineus muscle and the hip-joint. THE SPINAL NERVES 233 Anterior Crural (n. femoralis), from the 2nd, 3rd, and 4th lumbar nerves, to the iliacus and pectineus muscles, all the muscles on the front of the thigh except the tensor fasciae femoris, the hip- and knee- joints, and the integument on the front and inner side of the thigh. It descends through the psoas magnus muscle, passing beneath Pou- part's inguinal ligament to the thigh, where it divides into an interior and a posterior division. Its branches are Muscular, within the abdomen, to the iliacus muscle. Arterial, within the abdomen, to the femoral artery. Middle Cutaneous, to the skin on the front of the thigh. Internal Cutaneous, to the skin on the knee and leg. Muscular, to the pectineus and sartorius muscles. Long Saphenous (n. saphenus), to the skin over the patella and that on the front and inner side of the leg. Muscular, to the quadriceps extensor muscle. Articular Branches, to the hip- and knee-joints. THE SACRAL AND COCCYGEAL NERVES The Sacral Nerves number 5, the Coccygeal i, on each side. Their roots are long and descend vertically in the spinal canal as the cauda equina or horse's tail, to reach their respective foramina of exit. Their posterior divi- sions are small; they supply the multifidus spinae muscles and the skin of the gluteal region; those of the lower 2 sacral and the coccygeal supplying the extensor coccygis and the skin over the coccyx. Their anterior divisions communicate with the sacral ganglia of the sympathetic; those of the 3 upper sacral, with the lumbo-sacral cord (truncus lumbo-sacralis) and a branch from the 4th sacral, unite to form the sacral plexus. The anterior division of the 4th sacral divides into visceral and muscular branches, the former supplying the pelvic viscera, the latter the levator ani, sphincter ani, and coccygeus muscles. The anterior division of the 5th sacral and the coccygeal supply the coccygeus muscle and the skin over the coccyx. The Sacral Plexus (Plexus Sacralis) (Plate 14), is formed by the union of the anterior divisions of the upper 3 and part of the 4th sacral nerves (c), with the lumbo-sacral cord (truncus lumbo-sacralis) (a) derived from the 4th and 5th lumbar nerves. The plexus lies upon the pyriformis muscle, is covered by the pelvic fascia, communicates with the sympathetic, and gives off 2 great nerve-trunks or cords, the upper cord being prolonged as the great sciatic nerve, the lower cord becoming the pudic nerve, both passing out of the pelvis by the great sacro-sciatic foramen. The branches of the sacral plexus are as follows: 234 HUMAN ANA10MY FIG. 80. Muscular Branches, to the pyriformis, obturator interims, the 2 gemelli and the quadratus femoris. Superior Gluleal (n. glutaeus superior) (b), from the lumbo-sacral cord, to the gluteus medius and minimus muscles and the tensor fasciae femoris. Inferior Gluleal (n. glutaeus inferior), from the lumbo-sacral cord and the ist and 26. sacral nerves, to the gluteus (glutaeus) maximus muscle. Small Sciatic (n. cutaneus femoris posterior) (/), from the 2d and 3d sacral nerves, to the integu- ment of the perineum and back part of the thigh and leg, by gluteal, perineal and femoral cuta- neous branches. Perforating Cutaneous (n. clunium inferior medialis), sometimes classed as a branch of the "pudendal plexus," from the 2d and 3d sacral nerves, perforating the great sacro-sciatic (sacro-tu- berous) ligament, to the skin over the gluteus maximus muscle. Pudic (n. pudendus), sometimes classed as a branch of the "pudendal plexus" (e), from the 3d and 4th sacral nerves, escapes by the great sacro- sciatic foramen, crosses the spine of theischium, and re-enters the pelvis through the lesser sacro- sciatic foramen, to supply the perineum, anus and genitalia. Its branches are the Inf. Hemorrhoidal (n. haemorrhoidalis inferior). Perineal (n. perinei), dividing into 2 super- ficial perineal cutaneous branches and mus- cular branches to all of the perineal muscles. Dorsal Nerve of the Penis (n. dorsalis penis vel clitoridis). Great Sciatic (n. ischiadicus) (g), the largest ner- vous cord in the body, and the continuation of the upper cord of the sacral plexus, arises from the lumbo-sacral cord and the upper 4 sacral nerves, and escapes by the great sacro-sciatic foramen to the back of the thigh, giving off Articular Branches (rami articulares), to the hip-joint. Muscular Branches (rami musculares), to the flexor muscles of the THE SPINAL NERVES 235 leg, viz. the biceps, semitendinosus and semimembranosus, also to the adductor magnus. External (n. peronaeus communis) (K) and Internal (n. tibialis) (i) Popliteal, the terminal branches, generally arising at the lower third of the thigh. The Internal Popliteal Nerve (n. tibialis) (i), the larger of the two ter- minal branches of the great sciatic, descends along the back of the lower thigh and the middle of the popliteal space, to the lower part of the popliteus muscle, where it becomes the Posterior Tibial Nerve (&). Its branches are the Articular (rami articulares) 3, supplying the knee-joint. Muscular (rami musculares) (j), 4 or 5, to the gastrocnemius, plantaris, soleus and popliteal muscles. Communicant Tibialis (ramus anastomoticus tibialis), joins the com- municans peronei from the external popliteal nerve to form the External or Short Saphenous (n. cutaneus surae medialis) (/), descends to the outer malleolus and is distributed to the skin of the outer side of the foot and the little toe. The Posterior Tibial Nerve (&), the continuation of the internal popliteal descends along the back of the leg to behind the inner malleolus, where it divides into the External (lateral) and Internal (medial) Plantar nerves (/). Its branches are the Muscular (rami musculares), to the soleus, tibialis posticus, flexor longus digitorum and flexor longus hallucis. Calcaneo- plantar or Internal Calcaneal (rami calcanei mediales), to the skin of the heel and inner side of the sole of the foot. Articular (ramus articularis ad articulationem talocrualem), to the ankle-joint. Internal Plantar (n. plantaris medialis), to the inner plantar muscles, sole of the foot, and the plantar integument of the inner 3^ toes (nn. digi tales plantares communes). External Plantar (n. plantaris lateralis), to the external plantar mus- cles, and the plantar integument of the outer ij^j toes (nn. digitales plantares communes). The External Popliteal or Peroneal Nerve (n. peronaeus communis) (h), the smaller of the two terminal branches of the great sciatic (n. ischiadicus), descends from the bifurcation of the latter nerve, obliquely along the outer side of the popliteal space, winds around the neck of the fibula, and about an inch below the head of that bone it divides into the Anterior Tibial or Deep Peroneal (n. peronaeus profundus) (m) and Musculo-cutaneous or 236 HUMAN ANATOMY Superficial Peroneal (n. peronaeus superficialis) (n) nerves. Its branches are Articular (rami articulares), 3, to the front and outer side of the knee. Cutaneous (n. cutaneus surae lateralis), 2 or 3, to the integument along the back and outer side of the leg. One of these branches, the Communicant Peronei (ramus anastomoticus peronaeus), joins with the communicans tibialis (ramus anastomoticus tibialis) (see above) to form the external saphenous nerve (n. cutaneus surae medialis). Anterior Tibial or Deep Peroneal (n. peronaeus profundus) (m), sup- plying the extensor muscles, the ankle-joint, and the integument of the adjacent sides of the great and 26. toes. Musculo-cutaneous or Superficial Peroneal (n. peronaeus superficialis) (n), by 2 branches (0) (internal and external) to the peroneal muscles, the integument of the ankles, and the dorsal integument (n. cutaneous dorsalis medialis) and sides of all the toes, except the outer side of the little toe and the adjoining sides of the great and 2d toes, the former being supplied by the external saphenous (n. cuta- neus surae medialis), and the latter by the internal (medial) branch of the anterior tibial. THE SYMPATHETIC SYSTEM The Sympathetic Nervous System consists of a series of ganglia, connected together by intervening cords, one series on each side of the median line of the body, partly in front and partly on each side of the vertebral column, beginning in the ganglion of Ribes on the anterior com- municating artery and ending in the ganglion impar in front of the coccyx; three great gangliated plexuses, situated in the thoracic, abdominal, and pelvic cavities respectively; smaller ganglia, in relation with the abdominal viscera; and numerous communicating and distributing nerve fibres. (See Plate 16.) Ganglia in the Cranium. Besides the ganglia of the cranial nerves (described on page 223), all of which are connected with the sympathetic, there are in the cranium or in its immediate vicinity certain ganglia belong- ing to the sympathetic system, as follows: Carotid Ganglion, on the internal carotid artery. Ganglion of Bochdalek, above the canine tooth at the junction of a branch from the spheno-palatine ganglion with the middle superior alveolar and anterior superior alveolar nerves. Ganglion of Valent ine, situated at the juncture of the middle superior alveolar and the posterior superior alveolar nerves. THE SYMPATHETIC SYSTEM 237 The Carotid Plexus is situated on the outer side of the internal carotid artery, as it lies by the side of the body of the sphenoid bone, and is formed by filaments from the outer branch of the superior cervical ganglion. It communicates with the Gasserian ganglion (ganglion semilunare) and the 6th nerve; also with the tympanic branch of the gth by two branches, the small deep petrosal and the carotko-tympanic; and with the spheno-pala- tine ganglion by the large deep petrosal, which joins the great superficial petrosal to form the Vidian nerve (n. canalis pterygoidei) before entering the ganglion (see page 226). The Cavernous Plexus is situated in the upper portion of the cavernous sinus, below the last bend of the internal carotid artery, and is formed chiefly by the internal division of the ascending branch from the superior cervical ganglion. It communicates with the 3rd, 4th, ophthalmic divi- sion of the $th, and the 6th nerves, also with the ophthalmic ganglion. It sends filaments to the wall of the internal carotid artery, which are pro- longed into plexuses around the cerebral and ophthalmic arteries. The filaments on the anterior communicating artery form the ganglion of Ribes, which here connects the sympathetic of the two sides of the body. tf THE GANGLIATED CORD (TRUNCUS SYMPATHETICUS) " ' The Cervical Ganglia are 3 in number on each side of the neck, the supe- rior, middle and inferior cervical; of which the superior is the largest and is probably formed by the coalescence of four ganglia corresponding to the upper four cervical nerves. They are as follows: Superior Cervical Ganglion, of fusiform shape, situated behind the carotid sheath opposite the transverse processes of the 2d and 3d cervical vertebrae. Its branches form the carotid, cavernous, and pharyngeal plexuses; one of its internal branches unites with the superior laryngeal nerve, and another is the superior cervical cardiac nerve going to the cardiac plexuses. Middle Cervical Ganglion, on the inferior thyroid artery, opposite the 6th cervical vertebra gives off the middle cardiac nerve to the deep cardiac plexus, also many communicating branches. Inferior Cervical Ganglion, on the superior intercostal artery, between the neck of the ist rib and the transverse process of the 7th cervical vertebra. It gives off several communicating branches and the inferior cardiac nerve to the deep cardiac plexus. The Thoracic Ganglia are 1 1 or 1 2 in number on each side of the spine, resting against the heads of the ribs and covered by the pleura costalis, 238 HUMAN ANATOMY except the last two, which are placed on the side of the bodies of the nth and 1 2th thoracic vertebrae. Occasionally two ganglia coalesce into one, and the first is frequently blended with the last cervical ganglion. They are connected together by cords prolonged from their substance. They receive branches (white rami communicantes) from the thoracic nerves. They give off central branches (gray rami communicantes) connecting with the thoracic spinal nerves; and peripheral branches from the upper 5 or 6 ganglia to the thoracic aorta, etc., from the 3rd and 4th ganglia to the posterior pulmonary plexus, and from the lower 6 or 7 ganglia to form by their union the three splanchnic nerves, as follows: Great Splanchnic, from branches of the 5th to the loth inclusive, con- necting with the upper 5, passes through the posterior mediastinum, perforates the crus of the diaphragm, to the semilunar (coeliac) ganglion of the solar (cceliac) plexus. Lesser Splanchnic, from the loth and nth, passes through the dia- phragm with the great splanchnic, to the renal and solar (cceliac) plexuses. Least or Renal Splanchnic, from the last thoracic ganglion, also per- forates the diaphragm, and ends in the renal plexus; it is not always present. The Lumbar Ganglia consist usually of 4 small ganglia on each side, connected together by intervening cords, and situated in front of the ver- tebral column. Their central branches (gray rami communicantes) com- municate with the lumbar spinal nerves. Of their peripheral branches some help to form the aortic plexus, others go to the hypogastric plexus, and all give off numerous filaments to the bodies of the lumbar vertebrae and the ligaments connecting them. The lumbar ganglia receive branches (white rami communicantes) from the ist, 2d and sometimes 3d lumbar nerves. The Pelvic Ganglia are 4 or 5 small ganglia on each side, connected to- gether by intervening cords, and situated in front of the sacrum. The lower cords of each side converge below and unite on the front of the coccyx in the coccygeal ganglion or ganglion coccygeum impar. Their central branches (gray rami communicantes), 2 from each ganglion, communicate with the sacral nerves. Of the peripheral branches, some pass to the pelvic plexus, others go to a plexus on the middle sacral artery and all communi- cate on the front of the sacrum with the corresponding branches of the other side. The sacral portion of the sympathetic trunk receives one with rami communicantes. THE SYMPATHETIC SYSTEM 239 THE GREAT PLEXUSES (Plate 16) The Great Plexuses of the Sympathetic are large aggregations of nerves and ganglia, situated in the tkpracic, abdominal, and pelvic cavities, and named the Cardiac Plexus, the Coeliac or Solar Plexus, and the Hypo- gastric Plexus. Their branches form secondary plexuses which supply the viscera of the cavities, as described below. The Cardiac Plexus is situated at the Jjase of the heart, and is divided into a superficial portion and a deep portion, both of which are closely con- nected with each other. They form by their branches the anterior and posterior coronary plexuses and the anterior pulmonary plexus. The Superficial Cardiac Plexus is formed by the left superior cardiac nerve, the left inferior cervical cardiac branches of the pneumogastric, and filaments from the deep cardiac plexus. At the junction of these nerves a small ganglion, the cardiac ganglion of Wrisberg, is occasionally found, situ- ated immediately beneath the arch of the aorta on the right side of the ductus arteriosus (ligamentum arteriosum). This plexus lies in the con- cavity of the arch of the aorta, and in front of the right pulmonary artery. Branches from it pass to the i Right Anterior Coronary Plexus, formed chiefly from the preceding, also from the deep cardiac plexus. It passes forward between the aorta and the pulmonary artery. It follows the ramifications of the right coronary artery on the anterior surface of the heart. Right and Left Anterior Pulmonary Plexuses, are formed by filaments from the superficial and deep cardiac plexuses and the anterior pul- monary branches of the vagus nerve. Branches from them accompany the ramifications of the bronchial tubes throughout the lungs. The Right and Left Posterior Pulmonary Plexuses are formed by the pos- terior pulmonary branches of the vagus and branches from the 3rd and 4th thoracic ganglia of the sympathetic. They are not con- nected with the cardiac plexuses. They are situated on the pos- terior aspect of the roots of the lungs, and their branches accompany the ramifications of the bronchial tubes. The Deep Cardiac Plexus is formed by the cardiac nerves derived from the cervical ganglia of the sympathetic and the cardiac branches of the recurrent laryngeal and pneumogastric nerves. The only cardiac nerves which do not enter into its formation are those forming the super- Seta! cardiac plexus, namely the left superior cardiac and the inferior . cervical cardiac branches of the vagus. This plexus lies in front of the bifurcation of the trachea and behind the arch of the aorta. Its branches 240 HUMAN ANATOMY on the right side pass in front and behind the right pulmonary artery to the anterior pulmonary plexuses, the anterior (right) and posterior (left) coronary plexuses, and the right auricle; those on the left side give filaments to the superficial cardiac and anterior pulmonary plexuses and the left auricle, and then form the greater part of the Left or Posterior Coronary Plexus, is formed by filaments from both sides of the deep cardiac plexus. It surrounds the branches of the left coronary artery at the back of the heart, and its filaments are distributed with those vessels to the muscular substance of the ventricles. Ganglia, are found on the cardiac nerves, both on the surface of the heart and in its muscular substance. ' The Epigastric (Cceliac) or Solar Plexus, sometimes called the abdomi nal brain, consists of a great network of nerves and ganglia, situated behind the stomach and in. front of the aorta and the crura of the diaphragm, surrounding the cceliac axis and the root of the superior mesenteric artery. Its principal ganglia are the two Semilunar (coeliac) Ganglia, irregular gangliform masses, formed by the aggregation of smaller ganglia with interspaces between them, situated one on each side of the plexus, and in front of the crura of the diaphragm, close to the supra-renal capsules. This plexus and its connected ganglia receive the great and small splanch- jiic nerves of both sides, and some filaments from the right pneumogastric. It distributes filaments over all the branches from the front of the abdominal aorta, forming the following plexuses: / Phrenic or Diaphragmatic Plexus, arises from the upper part of the semilunar ganglion, and receives one or two branches from the phrenic nerve. It accompanies the phrenic artery and supplies the dia- phragm, some filaments going to the supra-renal capsule. At its junction with the phrenic nerve on the right side is the Ganglion Diaphragmaticum, a small ganglion at the juncture with the right phrenic nerve, it is situated on the under surface of the diaphragm, near the right supra-renal capsule. . Supra-renal Plexus, is formed by branches from the solar plexus, the semilunar ganglion, the phrenic and great splanchnic nerves. Its branches are large, and supply the supra-renal capsule. Renal Plexus, is formed by filaments from the solar plexus, the serai- lunar ganglion, the aortic plexus, and the lesser and smallest splanch- nic nerves, some 15 or 20 in all, which have numerous ganglia on them. They accompany the branches of the renal artery into the kidney, some filaments going to the inferior vena cava and to the spermatic plexus. THE SYMPATHETIC SYSTEM 241 Spermatic Plexus is derived from the renal plexus and receives fila- ments from the aortic plexus. It accompanies the spermatic vessels to the testes. In the female it is called the Ovarian Plexus, and is distributed to the ovaries and the fundus of the uterus. Superior Gastric or Coronary Plexus, joins with branches from the left pneumogastric nerve, and accompanies the gastric left artery along the lesser curvature of the stomach, being distributed to that viscus. Hepatic Plexus, receives filaments from the left pneumogastric and the right phrenic nerves, accompanies the hepatic artery, and ramifies in the substance of the liver upon the branches of that artery and those of the portal vein. It gives off branches to all the divisions of the hepatic artery, forming pyloric, gastro-duodenal, gastro-epiploic (inferior gastric), and cystic plexuses, on the arteries similarly named. /Splenic or Lienal Plexus, is formed by branches from the cceliac plexus, the left semilunar ganglion, and the right pneumogastric nerve. It accompanies the splenic artery and its branches to the substance of the spleen, and gives off filaments to the pancreas and the left gastro-epiploic plexus. Superior Mesenteric Plexus, is a continuation of the solar plexus, and receives a branch from the right pneumogastric nerve. It surrounds the superior mesenteric artery, and divides into pancreatic, intes- tinal, ileo-colic, right colic, and middle colic branches, which are distributed to all the parts supplied by that artery. Its nerves have numerous ganglia upon them near their origin. Aortic Plexus, on the sides and front of the aorta, between the origins of the superior and inferior mesenteric arteries; is formed by branches from the solar (cceliac) plexus and semilunar (cceliac) ganglia, and receives filaments from the lumbar ganglia. It sends branches to the spermatic, inferior mesenteric, and hypogastric plexuses, also some filaments to the inferior vena cava. A part of it is the Inferior Mesenteric Plexus, divides into left colic, sigmoid, and superior haemorrhoidal plexuses, and supplies the descending colon and the rectum. The Hypogastric Plexus is formed by filaments from the aortic plexus and the lumbar ganglia, and is situated in front of the promontory of the sacrum between the two common iliac arteries. It contains no evident ganglia, and bifurcates into two lateral divisions, the Pelvic or Inferior Hypogastric Plexuses, one on ea,ch side of the rectum, which receive branches from the 2nd, 3rd, and 4th sacral nerves, and the first two sacral ganglia. They give off numerous branches along the branches of the internal iliac 16 242 HUMAN ANATOMY arteries to the pelvic viscera, forming the following secondary plexuses, viz. Inferior Hamorrhoidal Plexus, to the rectum. Vesical Plexus, to the bladder, vesiculae seminales, and vas deferens. Prostatic Plexus, to that gland and the vesiculae seminales, also to the erectile tissue of the penis as the large and small cavernous nerves. Vaginal Plexus, to the vagina, gives off anteriorly the cavernous plexus of the clitoris from which arise the greater and lesser cavernous nerves of the clitoris. Uterine Plexus, to the uterus and Fallopian tube. TABLES AND PLATES OF THE NERVOUS SYSTEM NOTE. The folio-wing Tables are of original arrangement, and are designed to show the origin, formation and distribution of each nerve. They are self-explana- tory with the aid of the accompanying Plates. 244 HUMAN ANATOMY THE CRANIAL NERVES I Ethmoidal foramina, 20, ist NERVE, Olfactory. Function, smell. Exit, < in cribriform plate of (See page 216) [ Ethmoid bone. Ext. Root, Posterior division of the Rhin- | encephalon or "Limbic lobe." istN. Mid. Root, Optic thalamus. [ and Int. Root, Posterior division of the Rhin- | Bulb. encephalon or "Limbic lobe." Ext. Filaments, to Schneiderian membrane over sup. turbin- al and ethmoid bones. Int. Filaments, to Septum (upper third). Exit, Optic foramen. 2nd NERVE, Optic. Function, sight. (See page 217) This table is too long for the width of the page, and breaks at the Optic Commissure, which is repeated again where the table continues below. Optic thalamus Ext. geniculate Corp. quad. ant. Corp. quad. ant. | Optic thalamus J | Longitudinal Fibres -j Decussating [ Commissural \ Commissural Left Optic Tract ( Longitudinal J OPTIC COMMISSURE or CHIASM. OPTIC COMMISSURE or CHIASM. [ Longitudinal, to temporal li of retina Optic N. \ Decussating, fr. opp. tract to nasal Yt of ret. \ L. Eye. [ Inter-retinal, fr. opp. retina to retina. 2d f Inter-retinal, fr. opp. retina to retina. Optic N. \ Decussating, fr. opp. tract to nasal te of ret. } R. Eye. [ Longitudinal, to temporal J-i of retina. 3d NERVE, Motor Oculi. (See page 217) Nucleus in 1 floor of the 1 . . Aqued.ofSyl. j 3 Crus cerebri. J Function, motion. Exit, Sphenoidal fissure. fSup. Branch, to Lev. palp, sup., Rectus superior. . / to Rectus int., Rect. Inf., Inf. oblique. Inf. Branch s L ' ... ' ( motor root to Ciliary Ganglion. Supplies all the muscles of the orbit (except the superior oblique and ext. rectus) , also the sphincter of the iris and the ciliary muscle through the ciliary ganglion. Function, motion. Exit, Sphenoidal fissure. 4th NERVE, Trochlear. (See page 217) f to Sup. Oblique on upper (orbital) surface. 4th N. \ Branch to Cavernous Plexus of Sympathetic. I Recurrent Branch, to lateral sinus. Aq. of Sylvius. Crus cerebri. Is the smallest cranial nerve, with the longest nerve-course in the cranial cavity. THE CRANIAL NERVES Plate 6 longitudinal Fibres Decussating Fibres Conuni&sura/Fibres _. fnter-reiinul Fibr&r PoKerdeL 245 246 HUMAN ANATOMY $th NERVE, Trigeminus. (See page 218.) Functions, Sensation, Motion. (i) OPHTHALMIC by Sphenoidal fissure. Frontal < Lacrimal, to Supraorbital. Supratrochlear. gland, etc. Ganglionic. Long Ciliary. Nasal. Infratrochlear. Int. Nasal. Ext. Nasal. Meningeal. Origin. Nucleus and /-> i'A t / Temporal. Orbital, < ,, [ Malar. Locus Cae- Spheno-palatine. rul. in the (2) MAXILLARY Post. Sup. Denial. medulla oblongata by For. rotund. Mid Sup. Denial. \ . Ant. Sup. Denial. / ' n canal - for the Palpebral, } Sensory Root. Nuclei in floor of 4th Ven- 5th N. Trigeminus or Trifacial. Nasal, > on the face. Labial, J Recurrent. tricle, and ( Ant. Br. * Aq. of Syl- Int.Pterygoid, j pQgt B ^. vius, for the Masseteric. * Motor Root or ( Ant. Br. * Masticator Deep Temporal j p os ^ ]} r> Nerve. Buccal. Ext. Plerygoid.* Br. to facial n. (3) MANDIBU- LAR. (including masticator) by For. Ovale. A uriculo- Temporal. Br. to otic g. Ant. Auricular. to Meat. Aud. to articulation. Parotid. Sup. Temporal. Lingual Br. of Comm'n. Br. of Distrib'n. Mylo-hyoid. * Inferior Dental Brs. Dental. Incisive. \ . . . A , > terminal Mental. J Motor Branches (Masticator Nerve), going to the muscles of mastication. T r XT Plate7 THE CRANIAL NERVES. 5 l . h Nerve,-Trigeminus. iotter.del 247 248 HUMAN ANATOMY 7th NERVE, Facial, or Portio Dura. (See page 220.) Function, Motion, Special Sense (taste) In auditory ' canal. > Br. to Auditory nerve. Large Superf. Petrosal, to Meckel's ganglion. . Small Superf. Petrosal, to otic .0 In Aqueduct ganglion. 1 of Fallopius. Ext. Superf. Petrosal, to menin- '% geal plex. a Br. to Auricular of pneumogas- g tric. o O Origin. Nucleus in floor of the 8 1 At exit from the Stylo- Br. to Great Auricular (cerv. plex.). Br. to Auriculo-Temporal (sth). 4th Ventricle, and groove o a rt Foramen. Br. to Pneumogastric. Br. to Glosso-pharyngeal. between Olivary and 7th N. Facial W Behind the ear. > Br. to small Occipital. Restiform facial On the face. Brs. to 3 divisions of the sth nerve. bodies of medulla In the neck. Br. to Superficial Cervical. oblongata. Solitary Tympanic Nerve, to Stapedius Tract. In Aqueduct ^ muscle. e of Fallopius. Chorda Tympani Nerve (glosso- | palatine) , to the tongue and palate. s . "o Near Stylo- 1 mastoid < Foramen. '/ Auricular. Post. A uncular < _ . . . \ Occipital. Br. to Digastric muscle. Br. to Stylo-hyoid muscle. C/3 0) S ( Temporal. d 2 f Temporo-facial < Malar. pq 1 { Infra-orbital. On the face. * \ (Buccal. I Mandibular. r Cervical. * Forming the Pes A nserinus, or Goose's-foot, as these branches are named. THE CRANIAL NERVES. 7 1 ' 1 Nerve -Facial, or Portia Dura. PlateS References 1 LargeSuperf. Petrosal.toform VJlan wit 2 Small Supe^ PetrosaUo Optic Ganghor 3 External Superf. Fetrosal, to Plaus on M 4 Tympanic Br to Stapedius.etc. 3 Br n-om Carotid Plexus.Making Vidia^with NOf ). 7. Eirs to Aur.culo -Temporal 5 V Br to Auricular of 24Q 250 HUMAN ANATOMY 9th NERVE, Glossopharyngeal. Functions, Sensation, Special Sense. (See page 221.) Communica- j Large Petrosal. Small Petrosal. ting Brs. to 1 Carotid Plexus. Clrioiti ^ 1 ympantc or LJrigin. Tractus soli- tarius and floor pth Nerve Glosso- Jacobson's N. Distributing I Fenestra vestibuli. Fenestra cochlea?. of 4th vent. pharyn- Brs. to Eustachian tube. and the geal, by Carotid Branches, along Int. Carotid artery. medulla oblong. Jugular Pharyngeal Br. to Pharyngeal Plexus. behind the Foramen. Muscular Br. to Stylo-pharyngeus. olivary body. Tonsillar Brs. to Tonsillar Plexus. Lingual Brs. to base and posterior ^ of tongue; nerve of taste. loth NERVE, Pneumogastric, or Vagus. Function, Motion, Sensation. (See page 221.) Meningeal, to dura mater. Auricular (Arnold's Nerve), to external ear. Pharyngeal, to that plexus. Origin. Funic. soli- Sup. Laryngeal < T Xt ' T aryng ' ( Int. Laryng. crico-thyroid). supplies all the tarius, nucleus laryngeal ambiguus, floor loth Nerve Recurrent Larynpf-f-l muscles except of 4th ventricle Vagus, by Cervical Car- crico-thyroid and and the medulla Jugular diac. to cardiac arytenoideus. oblongata be- Foramen. Thoracic Car- plexus. tween olivary diac. and restiforn bodies. Ant. Pulmonary. \ -. , /-to pulmonary plexus. Post. Pulmonary. } (Esophageal, to that plexus. Gastric Brs., to the stomach. Hepatic, to the hepatic plexus. terminal brs. Gives sensation to external ear and larynx, motion to other parts, also vaso- motor, inhibitory, trophic and secretory influences. A nerve of deglutition, phona- tion, respiration, circulation, and digestion. The Auriculo-Laryngo-Pharyngo- CEsophago-Tracheo-Pulmono-Cardio-Gastro-Hepatic Nerve. nth NERVE, Spinal Accessory (N. ACCESSORIUS). (See page 222.) Function, Motion. Origin. Floor of 4th ventricle, and gray horn of cord, down to 6th Cervical N. nth Nerve, by Jugu- lar Fora- men. Branches, to Pharyngeal and Sup. Laryngeal of Vagus. Internal, anastomosing with Vagus, is probably the Recurrent Laryngeal Br. of the latter nerve. / Sterno-mastoid. External, or Muscular, tos _ ^ Trapezius. A motor nerve to the muscles named, and probably to the larynx also. Plate 9 a, THE CRANIAL NERVES. 9'.* or Glosso- pharyngeal, I0 l . h or Pneumo gastric, II fc . h or Spinal Accessory. References. IJugular Ganglion of 3 th Nerve Z.Petroui Ganglion of 9 th Nerve 3.Ganglion of the Vagu5 Rook. 4. Ganglion of the Vagus Trunk. 5. Medullary part OF IP* Nerve. 6.Spinal part of ||f." Nerve. 7 Sup Cardiac Br JOINING Cardiac of 5ympafhetic 8.5ubclavian Artery on right side, Arch of the Aorla on left side of the body. 9.Foramcn Magnum, receiving 5pinaf part of the Spinal Accessory. 10. Jugular Foramen.transmitl'ng all three Nerves II Branches to the Hypooloisal Sympathetic cervical fierves ' 12. Olivary body, (in broken line). Potter.del. 251 252 HUMAN ANATOMY 6th NERVE, Abducens (see page 219). Origin. A nucleus in floor of 4th ven- tricle, and the ^6th Nerve, Abducens. pyramid of the medulla oblongata. Function, Motion. Exit by sphenoidal fissure to the Ext. Rectus muscle of the eyeball. Branch, to the sympathetic. 8th NERVE, Auditory, OR ACUSTIC. Function, Special Sense. Origin. Striae in floor of the 4th ventricle, and groove between the pons and medulla. 8th Nerve, Auditory. f 2 Semi-circ. canals. Vestibular, toj Utricle. [ Saccule. J Post. Semi-circ. canal. Cochlear, to \ Saccule and Utricle. 1 Cochlea, and Organ of Corti. A nerve of special sense (hearing), described on page 220, ante. It goes by the Internal Auditory Meatus, through the Internal Auditory Canal, to the internal ear. It is the only cranial nerve which does not leave the cranial wall. i2th NERVE, Hypoglossal (NONUS OR QTH OF WILLIS). (See page 222.) Function, Motor of tongue, etc. Brs. to Origin. Floor of 4th ventricle, and groove between the pyramid and olivary body of medulla. J 1 2th Nerve, Hypoglossal. Descendens Hypoglossi. / Lingual of 5th. Communicating I Symphatic. I i, 2 Cervical. ( Vagus. IBr. to Sterno-hyoid. Br. to Sterno-thyroid. Br. to Omo-hyoid. Joins Communicans Hypo- glossi. Thyro-hyoid, to that muscle. Muscular, to j Stylo-glossus. I Hyo-glossus. I Genio-hyoid. [ Genio-hyo-glossus. Exit, by Ant. Condylar foramen (Canalis hypoglossi). THE CRANIAL NERVES. 6 th Nerve,- Abducens. to RectErter Plate 10 r ia al .Nerve^ of ^ J& ^ 1 2** Nerve, - Hypoglossal (Nonus or 9^ of Willis) .5**' Infra. . 3upnz-, , 4 Aunculo-temporal.SW 5 Lachry 7. ., 9. Ibstertor Auricular??* V Rjtter del 253 and 0mo- 254 HUMAN ANATOMY THE SPINAL NERVES 8 CERVICAL, 12 THORACIC, 5 LUMBAR, 5 SACRAL, i COCCYGEAL N. B. Read from the Black Type outwards to left and right Brs 3, to Recticap. Muscles. Post Div. of 2d N. 2 Cerv. N. Post M. of head, etc. POST. ] ist Cerv cal | ANT. Commun'g Vagus N. Complexus Muscle. Div. \ Nerve. j Div. Brs. to | Hypogl. N. Skin of occiput. J Sub-occij pital ( Sup. Cerv. Gang. Br. to Occip-atloid artic'n. Splenius Cerv. ascendens Transv.-colli Ext. Branch Br. to Spinal accessory Trach-mastoid supplying Fil.to Sterno-mastoidM. Complexus POST. . ANT. Cervical Asc. Br. to ist Cerv. N. Desc. Br. to 3d Cerv. N. to ist Cerv. N. )lnt. Br. or Nerve. Fil. to Commun. Hyp. Skin of occiput. Great Occip. Occipitalis Minor N. Auricular. Auric. Magnus N. Splenius A seen Superf. Cervical N. Cerv. ascend. Ext. Br. Br. Br. to 2d Cerv. N. Trans, colli supplies Br. to Spinal-ac. Trach-mast. POST. 1 . 3d n.,, Cervic , ANT. al I Div. Fil. to 4th Nerve. ] Int. Br. ""' 1 Nerv Integument 1 of occiput. J J supply e. J Descen. Fil. to Lev. ang. scap. Br. Supra-clavicular. Fil. to Com. Hypogl. Fil. to Phrenic N. Fil. to 3d Cerv. N. . / POST. \ 4th Cervi Muscles of the Back, f ^_ > XT -al f ANT FU " tO 5th CerV ' N> D.v 1 FiL to Phrenic N " ^ i-iv. j nerve. Fil. to Scalenus medius. I Fil to Supra-clavic. N. A nterior Divisions of ist Cerv. N. 2d Cerv. N. 3d Cerv. N. 4th Cerv. N. Cervical Plexus. Superficial Deep Brs. (See page 227.) Occipitalis Minor, to head. I Facial. Auricularis Magnus j Auricular. ( Mastoid. Superficialis Colli, has 2 branches. I Vagus. Communicating to j Hypoglossus. | Sympathetic. Muscular, to ant. rectus and rect. later. Communicans Hypoglossi N. 2. Phrenic Nerve, to the diaphragm. Muscular 4, to Sterno-mastoid, etc. [ Communicating, to Spinal accessory. THE SPINAL NERVES. Hate 11 Cervical Plexus. Potter .del /lCfo/r/fff{ The Cervical Plexus i... iu ( Scalenus Medius and \ . lies upon the Muscles ILevator anguli Scapulae I is covered by the Sterno-Cleido-Mastoid Muscle 255 256 HUMAN ANATOMY o THE BRACHIAL PLEXUS (See page 228.) Communicating Br. to phrenic nerve. Post, or Long Thoracic, I to the Ext. Respiratory I Serrat. N. of Bell. { mag. , f Supra-spinatus. Supra-scapular, T , . ^ < Infra-spmatus. I Shoulder-joint. Rhomboidei (5, 6, Cerv.) Subclavius (5, 6. Cerv.) Scaleni (6, 7, Cerv.) Long, colli (6, 7, Cerv.) Lev. ang. scap. (5, Cerv.) Ant. Div. 5th Cervical Nerve. Ant. Div. 6th Cervical Nerve. Ant. Div. 7th Cervical Nerve. Ant. Div. 8th Cervical Nerve. Ant. Div. ist Thoracic Nerve. UPPER PRI- MARY CORD. LOWER PRI- MARY Brach- ial Plexus, i OUTER or LAT- ERAL CORD. to Muscu- lar, to POSTERIOR CORD. INNER or MEDIAL CORD. f Br. to Post. Cord of Brachial Plexus. External Ant. Thoracic, to Pect. major. f Muscular. Musculo-cutaneous. I Anterior. (No. 2.) | Posterior. [ Articular. Median Nerve (outer head) (No. 3). ist Sub scapular, to Subscap. M. 2d Subscapular, to Lat. dorsi. 3d Scapular, to Teres major. Circumflex, to Deltoid and skin. (n. Axillaris.) Musculo-spiral f Muscular < (No. 6). (n. Radialis.) Cutaneous. Muscular, to Post. Interosseous. [ Scaleni (8, Cerv.) | Long, colli (8 Cerv.) I Above Clavicle. Br. to Post. Cord of Brachial Plexus. Int. Ant. Thoracic, to Pectoral muscles. Internal Cutaneous (No. 8) (medial Anti-brachial cutaneous). Lesser Int. Cutan. (N. of Wrisberg) (medial brachial cutaneous). Median Nerve (inner head) (No. 3). Ulnar Nerve (No. 10). Note. Nos. i, 2, 3, etc., refer to the next two tables. THE SPINAL NERVES Brachial Plexus Ulament from Plate 12 Cv /. Three > Int. Brs. costal*. Anterior ( Recti M. Cutane- j Skin of ous. Abdomen. 1 2th Thoracic ANT. Div. /Also sends a branch to 1 the Lumbo-sacral Cord. 262 HUMAN ANATOMY THE LUMBAR AND SACRAL NERVES (See page 232) (DISTRIBUTION SHOWN ON THE NEXT TWO TABLES) An | 1 [ Nos. ^^ Branch, g Ist Lumbar / Ant. i, 2, 3, sending filaments > [ Div. | Comm. Br. to the Erector g J ( to 2d Lum. spinae and o Intertransversales JB 1 Nos. muscles, and the ^ skin of the gluteal ^ Lumba, . f Ant. 3, 4, 7, \ Div. Comm. Br. region, posteriorly. ^ J to 3d Lum. Lumbar Plexus. 3 Branches: 1 1 {Part of (i) Ilio-hypogastric. 5, 6. 7, (2) Ilio-inguinal. Internal Branch, -J3 | 3 Comm. Br. (3) Genito- crural. sending filaments Q J to 4th Lum. (4) Ext. Cutaneous. to the Multifid. ^ (5) Obturator. spinae, and Inter- -g f Part of (6) Accessory spinales, and the -g skin over spinal j- 4th Lumba /Ant. r 5 'V r. < ^. Lumbo- Obturator. (7) Anterior Crural. vertebras. I to Multifidus Spinae S | 3d 2d Sacral and part (3) Muscular. (4) Articular. and skin of the J [ of the 4th. (5) Small Sciatic. gluteal region; the % (6) Pudic. lower nerve to g Br. to (7) Great Sciatic. Extensor Coccygis & f Ant PleXUS> and skin over the jg 4th Sacral. i Div Visc ' Brs - coccyx. Mus. Brs. J Fil. to 5th. . Join together in loops over back Post. \ of sacrum, Div./ 5 * SaCraL / Ant. ( Br. to skin of coccyx. \ Div. j Br. to Coccygeus M. sending fila- [ Br. to Cocc. Nerve. ments to skin over coccyx Post. \ _ f Ant. / A delicate filament, going to skin and Extensor Div. / \ Div. \ over coccyx. Coccygis. Plate 14 THE SPINAL NERVES. lumbar & Sacral Plexuses. The lumbar Plexus lies in the Substance of the Psoas Muscle ( Lies upon the Pyr iformis Muscle in the Pelvis The Sacral Plexus {and is covered by the Pelvic Fascia, and the V Sciatic and Pudic Arteries. Potter, del 264 HUMAN ANATOMY ILIO-HYPOGASTRIC, from ist Lumbar. DISTRIBUTION OF THE BRANCHES FROM THE 7 GREAT TRUNKS OF THE LUMBAR PLEXUS (A CONTINUATION OF THE TABLE ON PAGE 261) f Iliac, to skin of gluteal region. j Hypogastric, to skin of that region. ( Communicating Br., with I2th thoracic nerve. ILIO-INGUINAL, from ist Lumbar. Branch, to ilio-hypogastric nerve. to Internal Oblique muscle. to skin of upper and inner thigh, scrotum. GENITO-CRURAL, \ Genital, to Cremaster, scrotum, round ligament, or GENITO-FEMORAL within abdomen. ANTERIOR Mid. Cutaneous. to Sartorius, and skin of ant. thigh as low as the knee. FEMORAL or Ant. Ext. Br. to skin, lateral of knee. CRURAL, Div. Int. Cutaneous. Post. Br. to skin of inner thigh and from 2d, 3d, leg. 4th Lumbar. Long Saphenous. to skin of knee and of front and inner leg and foot. p | Muscular Brs. to the 4 parts of the Quadriceps Extensor *T j muscle. V ' [ Articular Brs. 2, to capsules of knee- and hip-joints. The Lumbar Plexus lies in the substance of the Psoas muscle, in front of the trans- verse processes of the lumbar vertebrae. THE SPINAL NERVES. Plate 15 Potter, del 266 HUMAN ANATOMY DISTRIBUTION OF THE BRANCHES OP THE SACRAL PLEXUS [CONTINUATION OF TABLE ON PAGE 261] SUPERIOR GLUTEAL, from Lumbo-sacral cord. I Inf. Br. Sup. Br. to the Gluteus medius muscle. to the Gluteus medius and minimus, to the Tensor vaginae femoris. INFERIOR GLUTEAL,. .to the Gluteus maximus muscle. MUSCULAR BRANCHES, to Pyriformis, Obturator internus, the two Gemelli, and the Quadratus femoris muscles. ARTICULAR BRANCHES, to the hip- joint. SMALL SCIATIC, or POSTERIOR FEMORAL CUTANEOUS, from 2d, 3d Sac- ral. Gluteal Cutaneous, to skin over Gluteus maximus. Perineal Cutaneous, * ^ * " P f ^ and f inner thigh ' [ Inf. Pudendal, skin of scrotum. Femoral Cutaneous back f thigh, popliteal space, and upper part of the leg. PERFORATING f CUTANEOUS, 1 to skin covering lower part of Gluteus maximus muscle: passes from 2d, 3d Sac- ] through the sacro-sciatic ligament. ral. PUDIC or PUDENDAL, from 3d, 4th Sacral. GREAT SCIATIC (n. ischiadicus), from lumbo-sac- ral cord, 4 upper sacral. Inferior Hemorrhoidal, to Sphincter ani muscle, to skin of anal region. (to Skin of anus, scrotum, Superficial Perineal, -j penis and labia, and the ( Sphincter ani muscle. Muscular, to perineal muscles, and corpus spongio- sum of penis. Dorsal of Penis, Skin of dorsum of penis. Br. to Corpora cavernosa. Articular,, .to the hip-joint. Adductus magnus, Biceps. Muscular, to Semi-mem branosus, Semi-tendinosus. External Popliteal or Peroneal. \ terminal branches. Internal Popliteal or Tibial Nerve. } (See next page.) The Sacral Plexus lies in the pelvis upon the Pyriformis muscle, and is covered by the Pelvic fascia, and the Sciatic and Pudic arteries. NERVES OF THE LEG AND FOOT 267 INTERNAL POPLITEAL or TIBIAL NERVE. NERVES OF THE LEG AND FOOT TERMINAL BRANCHES OF THE GREAT SCIATIC NERVE] Articular 3, to knee-joint. Muscular, to Gastrocnemius, Plantaris, Soleus, and Popliteus. Communicans Tibialis, to form the Ext. Saphenous nerve. I formed by a filament from each of the External or Short Saphenous, j Popliteal nerves, to skin of outer 1 side of the foot and little toe. Continues as the POSTERIOR TIBIAL. Muscular, to Flexor longus pollicis. Flexor longus digitorum. Tibialis posticus. Soleus. Calcaneo-Plantar, to skin of heel and sole of the foot. Articular, to the ankle-joint. I Digital, to skin, 3^ inner toes. Internal I Muscular, to flexors, etc. Plantar. J Articular, to tarsal joints. I Cutaneous, to sole of foot. External Plantar. Muscular, to Flexor accessorius. f to I ^j outer toes. Superficial, < Flexor brevis min. digiti. [ 4th Interosseous. Deep Br. to the 3d and 4th Lumbricales. rest of Interossei. EXTERNAL POPLITEAL or COMMON PERONEAL NERVE. Articular 3, distributed to the knee-joint. Cutaneous 2, to skin of leg, exteriorly and posteriorly. Communicans Peronei, to form the Ext. Saphenous nerve. / front muscles of leg. Anterior Tibial cr Deep Pero- neal Musculo- cutaneous or Superficial Peroneal. Muscular, to External Br. \ Peroneus tertius. / Extensor brevis digitorum. \ Tarsal articulations. Internal Br. to skin of sides of great and 2nd toes. External Br. Peroneus longus and brevis muscles. Skin, outer side of foot and ankle. Skin, contig. sides, 3d, 4th, 5th toes. [ Skin, inner side of foot and ankle. Internal Br. -j Skin, contig. sides, ad and 3d toes [ and inner side of great toe. 268 HUMAN ANATOMY Begins in the 1 Ganglio / of Ribes External Sup. Branches Brs. to join the ist, 2d, Superior 3d, 4th Cervical Anter Cervical Ganglion. Nerves. THE SYMPATHETIC SYSTEM n f on the Anterior Communicating artery, at the base of es. \ the brain. [ Some to Pneumogastric, Glossopharyngeal, and Hypoglossal Nerves. (Ext. Br. forms Carotid Plexus. Int. Br. forms Cavernous Plex. along Int. Carotid Artery. Anterior Branches, to Plexus on Ext. Carotid Artery. f Pharyngeal, to Pharyngeal Plexus. Int. I Superior Cardiac Nerve, to Cardiac Plexus; goes Brs. I to Deep PI. on right side, to Superficial PI. [ left side of body. Ext. Brs. to f Middle 5th and 6th j Cervical Cerv. N. [ Ganglion. Ext. Brs. to f Inferior 7th and 8th X Cervical Cerv. N. [ Ganglion. Int. Brs. (Filaments along Inf. Thyroid Art. to Thyroid j body and Larynx. [ M id. Cardiac Nerve, to Deep Cardiac Plexus. Int. ( Filaments along Vertebral Art. to cranium. Brs. \ Inf. Cardiac Nerve, to Deep Cardiac Plexus. Ext. Brs. to Thoracic N. f " 1 j Thoracic j- [ Ganglia. J Int. Brs. Upper 5 or 6 to Aorta and Vertebral column. 3d and 4th to Post. Pulmonary Plexus. Lower 6 form the 3 Splanchnic Nerves, thus 6-10, Great Splanchnic, to Semi-lunar Gang. 10, ii. Lesser Splanchnic, to Cceliac Plexus. 12, Smaller Splanchnic, to Renal and Solar Plexuses. Ext. Brs. to Lumbar N. 4 Lumbar Ganglia. lnt. 1 Some to Aortic Plexus. Brs. \ Some to Hypogastric Plexus. Ext. Brs. to Sacral N. 4 or 5 Sacral Ganglia. Int Brs '. f to Pelvic Plexus. rs. \ to Plexus on Middle Sacral Artery. {Coccygeal ) G., or I In which ends the double chain of gangliated cords Ganglion j enumerated above, and called THE SYMPATHETIC NERVE. Impar. . [FOR THE VARIOUS CONNECTED GANGLIA, ETC., SEE PAGES 223 TO 22?.] THE SYMPATHETIC SYSTEM OF NERVES Plate 16 tcG.ofRootofPncu toftlrvas G. Glasso-pha from &Cervica 2 G^GANGLIOTJ umogastric toflypoylos&al N. br. cfxt. Carotid A . toPharyntjeal P. to Inf. 'Thyroid 4* Cardiac bT.Jr.PneumogastTic f?= PLEXUS . and Rec. Larynyeal "Nerves AJ=ARTERY. "Cardiac Fiexns Mexua duodenal /. Sup. HemorrhoidaL P. 2.Spcrmatic Plexus rpoaa&tric Plexus Pelvic or Inf. ' ffypcyra&tnc Plexn* Oarujlumlmpar. ^ Twtr del. 26<) 2 7 o HUMAN ANATOMY FIG. 81. ORGANS OF SPECIAL SENSE The Special Senses are those of touch, taste, smell, sight and hearing. The Skin is the principal seat of the sense of touch, the Tongue is the organ of taste, the Nose is the peripheral organ of smell, the Eye of sight and the Ear of hearing. THE SKIN AND ITS APPENDAGES The Skin consists of the Epidermis or Cuticle, the scarf-skin, com- posed of 3 superficial and 2 deep layers; and the Derma, Corium, or Cutis Vera, the true skin, composed of a papillary layer above and a reticular layer below. The Epidermis, Cuticle or Scarf- skin, is an unorganized epithelial structure, having neither vessels nor nerves. Its constituent epithelial cells are agglutinated together in a laminated arrangement, are flat and dry on the surface, round and softer in the central portion, columnar and softest in the deepest layers. They are arranged in the following layers, from above downward, viz. Stratum Corneum (i), horny epi- thelial cells, without nuclei. Stratum Lucidum, closely packed, scaly cells. Stratum Granulosum, flat, spin- dle-shaped cells, containing granules of eleidin, an interme- diate substance in the forma- tion of horn. Rete Mucosum or Stratum Mal- pighii (2), contains pigment cells. Basilar Layer or Stratum Germinativum, composed of columnar epithelial cells placed perpendicularly on the surface of the derma, and separated from the papillae by a homogeneous basement membrane. The Derma, Corium or Cutis Vera (4), the true skin, is a highly organized, tough yet elastic tissue, and serves to protect the parts beneath, to perform APPENDAGES OF THE SKIN 271 the functions of excretion and absorption, and as the chief seat of the sense of touch. It consists of felted connective tissue, elastic fibres, blood- vessels, lymphatics, and nerves; also unstriped muscular fibres in various situations. It is formed in two layers, as follows: Papillary Layer (3), situated next to the epidermis, is covered with minute conical elevations (papillae), H^oo inch high, ^50 inch in diameter at their base, very numerous and arranged in parallel curved lines wherever sensibility is greatest. Each papilla contains a capillary loop or plexus, the termination of one or more sensory nerves, and in highly sensitive parts, an oval-shaped body, the Tactile Corpuscle, a special sensory nerve ending. Reticular Layer, the deep layer, is composed chiefly of interlacing bun- dles of white fibrous tissue, in which are mingled some yellow elastic fibres; also plain muscular fibres wherever hairs are found, and lym- phatic vessels, blood-vessels, and nerves in plexiform arrangement. Below this the elements of the skin become blended with the sub- cutaneous tela or areolar tissue (5), which contains fat, except in a few situations. Mucous Membrane is a soft, velvety structure, analogous to the skin, and found as the lining of the gastro-intestinal, pulmonary and genito- urinary tracts. It is composed of Epithelium of various forms, in- cluding the squamous, columnar, and ciliated, often arranged in several layers; and Corium, analogous to the derma of the skin, consists of con- nective tissue, blood-vessels, lymphatics, nerves, and unstriped muscle cells; and is separated from the epithelium by a transparent basement membrane. The mucous membrane has numerous glands embedded in it, which secrete mucus to cover the surface for its protection from foreign substances. Projecting from it in certain parts are villi and papilla. processes which are analogous to the papillae of the skin. Structures lying in the Skin, and directly beneath it, include the follow- ing, viz. Sensitive Papilla, containing Tactile Corpuscles in very sensitive parts, in the papillary layer of the derma. Hair Follicles, in the reticular layer of the derma, perforating the derma and the epidermis: sometimes extending into the subcutaneous tissue. Sebaceous Glands (6), in the reticular layer of the derma; their ducts (8, 9) opening usually into the hair-follicles, but occasionally on the surface of the epidermis. Sudoriferous or Sweat Glands, usually in the subcutaneous areolar 272 HUMAN ANATOMY FIG. 82. tissue; their ducts perforating the derma and epidermis, to open on the surface of the latter. Fat Cells, in the subcutaneous areolar tissue. Organs of Touch are the various sensory nerve- endings in the skin or its vicinity and in mucous membranes. They include minute, primitive fibrilla or networks thereof, and certain special terminal organs, as follows: End-bulbs of Krause, minute bodies, Moo inch in diameter, consisting of a capsule surrounding a soft core, in which the axis- cylinder of the nerve terminates, in a bulbous expansion or in a coiled plexiform mass. They are found chiefly in mucous mem- branes, the genital organs, and the synovia] membranes of the finger-joints. Tactile Corpuscles, are oval bodies, ^oo inch long, formed of connective tissue, and con- sisting of a capsule and imperfect septa, which penetrate the interior. The axis-cylinders of the nerve fibres (N) terminate within the corpuscle in a globular enlargement. They are found in papillae of the derma of the hand, foot, forearm, lips, nipple, etc. Other tactile corpuscles, in the papillae of parts devoid of hair, consist of a capsule, containing two or more granular cells, between which the nerve- fibre is supposed to terminate. Pacinian Corpuscles, are composed of lamellae (d), consisting of connective tissue fibres, arranged concentrically around a central clear space (ni), in which the nerve-fibre (n) terminates at the distal extremity in a rounded end (a), which is often bifid or even trifid. They are found chiefly on the nerves of the palm of the hand and the sole of the foot, the ends of the fingers, and the genital organs, lying in the subcutaneous tissue. APPENDAGES or THE SKIN The Nails (Ungues) are curved, horny structures, a modification of the epidermis, molded upon the derma at the dorsal surface of the terminal FIG. 83. THE TONGUE 273 phalanges of the fingers and toes. Each nail is convex on its outward surface, and is embedded by its Root (radix unguis) into a fold of the skin. Its Matrix, is that portion of the derma directly beneath the nail. It is covered with highly vascular papillae. The Lunula, is a white crescentic portion of the nail nearest to its root, produced by the diminution in number and size of the papillae beneath. The Hairs (Pili) are also a modified form of the epidermis, found over nearly the whole surface of the body, much varied in size and color. Each hair consists of a Root and a Shaft. The Root (radix pili), is lodged in an involution of the epidermis called the Hair-follicle, which sometimes extends into the subcutaneous cellular tissue. The root rests on a vascular papilla, at the bottom or Bulb of the follicle, which supplies it with material for its growth. Shaft (scapus pili), is the projecting portion of the hair. It consists of a medulla in the centre, next a fibrous portion, externally a cortex of thin, flat scales. The finest hairs have no medulla. Point (apex pili), consists of the fibrous portion and the cortex, the medulla being wanting. Sebaceous Glands (Glandulae Sebaceae) are small, glandular bodies situated in the corium over most of the body, but not in that of the palmar surface of the hands nor on the plantar surface of the feet. Each gland consists of a single sacculated duct, usually opening into a hair-follicle, but sometimes ending on the surface of the epidermis. They are most abundant in the scalp, the face, around the anus, and the apertures of the nose, mouth and external ear. The largest are the Meibomian Glands, situated in the eyelids. Sudoriferous or Sweat Glands (Glandulae Sudoriferae) consist each of a single convoluted tube, situated usually in the subcutaneous cellular tissue, and opening on the surface of the integument by a spiral duct which pierces the derma and the epidermis. The duct has two coats, an external fibro-cellular, which is continuous with the corium, and an epithelial lining, continuous with the epidermis. These glands are estimated as varying, in different parts of the integument, from 417 to 2800 to the square inch, giving for the whole body a total number of nearly two millions and a half, representing an evaporating surface of about 8 square inches. They are most numerous on the palm of the hand. THE TONGUE (LINGUA) The Tongue is the organ of taste. It is composed of siriated muscle, is covered with mucous membrane, and is supplied with blood-vessels, 18 274 HUMAN ANATOMY lymphatics and nerves. Its base (radix linguae) is connected with the hyoid bone by the hyo-glossi and genio-hyo-glossi (mm. genioglossi) muscles and the hyo-glossal membrane; with the epiglottis, by the 3 gJosso-epiglottic folds of mucous membrane; with the soft palate, by the anterior pillars (arci glosso-palatini) of the fauces; and with the pharynx, by the superior constrictor muscles and the mucous membrane. Its tip (apex linguae), thin and narrow, is free in the mouth, and rests when quiet against the lower incisor teeth. Its wider surface (facies inferior linguae) is connected with the lower jaw by PIG the genio-hyo-glossi (mm. genioglossi) mus- cles. Its mucous covering is reflected later- ally on the inner surface of the gums, form- ing in front the frjEnum lingua (frenulum lin- guae), a vertical fold below the tip. The tongue presents the Raphe (sulcus medianus linguae), a ver- tical, fibrous septum, in the median line, dividing the tongue into two symmet- rical halves, and terminating behind in a depression, the foramen ctzcum, about an inch from the base of the organ. Papillcs V dilates (i) (circumvallate), 8 to 12 in number, in two rows on the dorsum of the tongue, the rows forming a V and meeting in front of the foramen cacum. Papilla Fungiformes (2) (lenticular), scattered irregularly over the dorsum, chiefly at its sides and apex. Papilla Filiformes (conical), cover the anterior two- thirds of the dorsum and' have numerous filiform processes or secondary papillae projecting from their apices. Taste-buds, flask-shaped bodies, found in the epidermis of the circum- vallate papillae, and in some of the fungifqrm (described below). Glands of Blandin or Nuhn, mucous glands, one on either side of the fraenum, having 4 to 6 ducts which open on the under surface of the apex. Racemose Serous Glands of Ebner, at the back of the tongue, their ducts opening into the fossae of the vallate papillae. Hyo-glossal Membrane, a strong, fibrous lamina, connecting the under surface of the base of the tongue to the bod> of the hyoid bone. Extrinsic Muscles of the Tongue, are the stylo-, hyo-, chondro-, genio- THE TONGUE 275 hyo-, palato-glossi muscles, and part of the superior constrictors of the pharynx (pharyngeo-glossi). These have been described on page 82. Intrinsic Muscles of the Tongue, are the various fibres of the lingualis muscle, superior, inferior, transverse and vertical. (See page 83.) Taste-buds are flask-shaped bodies, situated in the epidermis (e) of the vallate and some of the fungiform papillae; also found at the sides of the base of the tongue, on the epiglottis and the soft palate. Each bud has a broad base, which rests on the corium, and a neck opening on the mucous surface by an orifice, the gustatory pore (0). The buds are formed by sup- porting cells, mostly arranged like the staves of a cask; and spindle-shaped, nucleated gustatory cells in the central portion, each terminating at the gustatory pore in a fine filament, the gustatory hair. Terminal nerve-fibrils ramify between the gustatory cells, and others are found between the cortical cells. Vessels of the Tongue. The Arteries are de- rived from the lingual, facial, and ascending pharyngeal, branches of the external carotid. The^ Veins open into the internal jugular. The Lymphatics of the posterior half of the tongue pass to one or two small glands on the hyo-glossus muscle, and thence to the deep glands of the neck; those of the anterior half are connected with the sub-mandibular lymphatics. Nerves of the Tongue are as follows: the Lingual Branch of the Mandibular Division of the $th, to the papillae of the fore part and sides of the tongue, endowing the anterior two-thirds of the organ with ordinary sensibility. Chorda Tympani is the continuation of the glosso-palatine nerve (n. inter- medius) or "pars intermedia, " the sensory root of the facial, it runs in the sheath of the lingual nerve and is distributed to the same region, being the nerve of taste for the anterior two-thirds of the tongue. Lingual Branches of the gth or Glosso- pharyngeal, to the mucous membrane of the base and sides and the circumvallate papillae, being the nerves of taste and ordinary sensation for the posterior third of the tongue. Hypo-glossal or j 2th Nerve, the motor nerve of the tongue, distributed to the intrinsic and extrinsic muscles, 276 HUMAN ANATOMY Superior Laryngeal Branch of the loth or Vagus, sends a few filaments, by way of its internal laryngeal branch, to the root of the tongue. Sympathetic Filaments, from the nervi molles on the lingual and other arteries supplying the organ (Spitzka). Special Nerves of Taste in the Tongue, are the- Chorda Tympani, the continuation of the sensory root (glosso-palatine nerve or n. inter medius) of the Facial, for its anterior two- thirds; perceiving saline, acid and styptic qualities (Flint). Lingual Branches of the Glosso-pharyngeal, for its posterior third; appre- ciating alkaline, metallic, sweet and bitter tastes (Flint). Sapolini's view of the Chorda Tympani Nerve. From repeated dis- sections, Dr. Sapolini, of Milan, believes the chorda tympani to be a separate cranial nerve, a continuation of the pars intermedia of Wrisberg (glosso-palatine nerve or n. intermedius) which has its deep origin in the upper end of the nucleus of the glosso-pharyngeal nerve in the floor of the 4th ventricle and the solitary or "trineural" tract in the medulla, joins the facial in the internal auditory meatus, and terminates in a dense plexus with the lingual branch of the th in the muscular substance of the tongue. He further concludes that the chorda tympani is the nerve governing the movements of the tongue in speech, and that the nerves of taste are the Lingual Branches of the 5th and gth nerves. THE NOSE (NASUS) The Nose is the peripheral organ of smell, and consists of the outer nose (nasus externus) and the nasal fossae (cavum nasi). The Outer Nose projects from the centre of the face, and is composed of a framework of bones and cartilages, covered by skin, lined by mucous membrane, and supplied with vessels and nerves. At its base it presents two elliptical orifices, the nostrils or anterior nares, separated by a septum, the columna (septum mobile nasi), and guarded at their margins by numerous stiff hairs, the mbrissoe. The Bony Framework, is formed by the nasal bones and the nasal processes of the maxillae (see page 27). Cartilages (cartilagines nasi) are 5, two upper lateral (cartilago nasi latralis), two lower lateral (cartilago alaris nasi major), and the cartilage of the septum (cartilago septi nasi), connected together and to the bones by a tough, fibrous membrane, which permits of free movement between them. Septum Nasi, the nasal septum, is formed anteriorly by the cartilage THE NOSE 277 of the septum, posteriorly by the perpendicular plate of the ethmoid bone above and the vomer below. The Nasal Fossae (cavum nasi) are two irregular cavities in the middle of the face, separated by the septum nasi, opening in front by the anterior nares, behind by the posterior nares (choanae) into the naso-pharynx. Their osteological description has been given on page 37. Each fossa is divided into an olfactory portion (regio olfactoria), containing the upper part of the septum and the superior turbinal process and a respiratory portion (regio respiratoria), comprising the rest of the fossa. It is further divided, from above downward, into the superior, middle and 16 H 12 inferior meatuses of the nose, which are separated from each other by the middle (concha nasalis media) (2) and inferior turbinal (concha nasalis inferior) bones. Each fossa presents the Vestibule (9), a slight dilatation inside the aperture of the nostril, extending as a small pouch, the ventricle, toward the point of the nose. Spheno-ethmoidal Recess, on the outer wall, above the superior tur- binal process into which the sphenoidal sinus (4) opens. Bulla Ethmoidalis, an elevation on the outer wall of the middle meatus, on or above which are the orifices of the middle ethmoidal cells. Hiatus Semilunaris, a narrow groove in the outer wall, in front of the bulla ethmoidalis, into which open the anterior ethmoidal cells and the antrum (sinus maxillaris) of Highmore (i) . Infundibulum (3), the superior prolongation of the middle meatus, 278 HUMAN ANATOMY leading into anterior ethmoidal cells and the frontal sinus (see page 38). Atrium (atrium meatus medii nasi) (5), a depressed area above the vestibule, forming the anterior extremity of the middle meatus. Orifice of the Nasal Duct (ductus naso-lacrimalis) (7), on the outer wall, in the anterior part of the inferior meatus. Naso-palatine Recess, a depression at the lower edge of the cartilage of the septum; near it a minute orifice leads into a blind pouch, the rudimentary organ of Jacobson (organon vomero-nasale). The Schneiderian or Pituitary Membrane is the mucous membrane lining the nasal fossae, thick and vascular over the septum and the turbinal processes, but very thin elsewhere. On it, in the upper portion of the fossae, are distributed the terminal filaments of the olfactory nerve, the FIG. 87. special nerve of the sense of smell. It is continuous with the mucous lin- ing of the pharynx, Eustachian tube (tuba auditiva), tympanum and mastoid cells; also with that of the frontal, ethmoidal and sphenoidal sinuses, the maxillary antrum, nasal duct, and the conjunctiva. It is covered with columnar epithelium, which is ciliated throughout most of its extent, contains much adenoid tissue, is provided with mucous and serous glands, and in the olfactory region it contains the Olfactory Cells of Schultze, spindle-shaped, epithelial cells, grouped around and between the columnar cells of the epithelium, having at THE NOSE 279 one end hair-like processes, the olfactory hairs, and joined together by other processes, forming an intricate plexus on which the terminal fibres of the olfactory nerves are supposed to end. Glands of Bowman, are tubular, often branched, serous glands, in a layer beneath the epithelium, extending through the thickness of the mucous membrane, in the olfactory region. Nerves supplying the Outer Nose are branches from the facial nerve to the muscles; branches from the infraorbital and infratrochlear, and the nasal branch of the ophthalmic, supplying the integument. Those supplying the Nasal Fossa are the Olfactory or ist Nerve (a), over the upper third of the septum (i), the superior turbinal process and the surface of the ethmoid in front of it. Nasal Branch of the Ophthalmic (d}, to the septum and outer walls. Anterior Dental or Alveolar Branch of the Maxillary, to the inferior meatus of the nose and the inferior turbinal bone. Vidian Nerve (n. canalis pterygoidei), to the septum and the inferior turbinal bone. Naso-palatine (e), from the spheno-palatine ganglion, to the middle of the septum; thence through the anterior palatine foramen (/). Anterior Palatine (h), from the spheno-palatine ganglion, to the middle and lower turbinal bones, by its inferior nasal branches. Superior Nasal Branches, from the spheno-palatine ganglion, to the septum and the superior and middle turbinal bones. Arteries of the Nose. The arteries supplying the Outer Nose are the lateralis nasi branch of the facial (a. maxillaris externa); the inferior artery of the septum, from the superior coronary branch of the facial (a. maxillaris externa); and the nasal branch of the ophthalmic and the infraorbital, which go to the dorsum and sides of the nose. The Arteries of the Nasal Fosses form a close, plexiform network beneath and in the mucous membrane, and are the Ant. and Post. Ethmoidal, from the ophthalmic, to the roof. Spheno-palatine, branch of the internal maxillary, to the mucous mem- brane over the turbinal bones, the meatuses, and the septum. Infraorbital and Alveolar, branches of the internal maxillary, to the mucous lining of the antrum. Inferior Artery of the Septum, from the superior coronary branch of the facial (a. maxillaris externa), to the mucous membrane of the septum. . Veins of the Nose. Those of the outer nose terminate in the facial and ophthalmic veins. Those of the nasal fossa form a close, cavernous-like 280 HUMAN ANATOMY network beneath the mucous membrane, and terminate in the facial and ophthalmic veins, a few going to the veins in the interior of the skull. THE EYE [For an osteological description of the Orbit, see page 35.] The Eyeball (bulbus oculi) is situated in the anterior part of the orbital cavity, on a cushion of connective tissue and fat, where it is retained by its muscles, the optic nerve, the conjunctiva, etc., and protected in front by the eyelids and eyebrows. It is composed of segments of two spheres of different sizes; the anterior segment being the smaller, forming about Y of the eyeball, and named the cornea; the posterior and larger segment, is formed by the sclerotic coat (tunica fibrosa oculi), and constitutes the remaining % of the globe. It is surrounded by a thin, membranous sac, the capsule (fascia bulbi oculi) of Tenon, and has the following '< Diameters, in the adult, antero-pos- terior and transverse, nearly an inch, vertical about %o of an inch. Anterior Pole, the central point of the anterior curvature. Posterior Pole, the central point of the posterior curvature. Sagittal Axis (axis optica), a line joining the two poles. The Capsule of Tenon (fascia bulbi oculi) (3) is a thin membrane which en- velops the eyeball from the optic nerve to the ciliary region, where it blends with the ocular conjunctiva. Its smooth, inner surface is in contact with the outer surface of the scler- otic coat (tunica fibrosa oculi), with which it is connected by delicate bands of connective tissue. Posteriorly it is continuous with the sheath (17) of the optic nerve, and from it tubular sheaths are prolonged over the muscles which move the eyeball, giving off slips to the bones of the orbit. The Check Ligaments, internal and external, are expansions from the sheaths of the internal and external recti muscles, and are attached to the lacrimal and malar bones respectively. THE EYE 28l Suspensory Ligament of the Eye (Lock wood's), is a thickening of the lower part of the capsule, slung like a hammock below the eyeball, and attached to the lacrimal and malar bones. Peri-sclerotic Lymph-space, intervenes between the capsule and the sclerotic, and is continuous with the subdural and subarachnoid spaces. Tunics of the Eyeball are 3 in number, named from without inward as follows: the ; Sclerotic (fibrosa) (3) and Coronea (i), the external, fibrous, and protective tunic. Choroid (choroidea) (4), Ciliary Body (corpus ciliare) (5), and Iris (8), the vascular tunic, sometimes called the Uveal Tract. Retina (tunica interna) (13), the innermost, nervous tunic. Refracting Media are 3 in number, and are named as follows: the Aqueous Humor (humor aqueus) (2), ^fills the anterior (2) and posterior (9) chambers (camerae). Vitreous Body (corpus vitreum) (18), fills the concavity of the retina. Crystalline Lens (lens crystallina) (15), in front of the vitreous body. THE SCLEROTIC AND CORNEA The Sclerotic, or hard coat (tunica fibrosa oculi), is the posterior five- sixths of the jjx.trnal iunic of the eyeball, the anterior one-sixth being the Cornea. Externally it is of a whita-color, covered anteriorly by the conjunctival mucous membrane, posteriorly being continuous with the fibrous sheath of the optic nerve. Internally its color is brown, and its surface marked by grooves for the ciliary nerves. The optic nerve pierces it posteriorly, also the long and short ciliary arteries, posterior ciliary veins and short ciliary nerves. In the equatorial region it is pierced obliquely by the venae vorticosae, and around the corneal border by the anterior ciliary arteries and veins. It is composed of white fibrous tissue, intermixed with elastic fibres, and of flattened connective-tissue corpuscles, some of which are pigmented. The Sclerotic presents for consideration the following points: Thickness, ^5 inch posteriorly, %o inch anteriorly. Lamina Fusca, a layer of very fine pigmented connective tissue, con- necting the sclerotic with the outer surface of the choroid. Lamina Cribrosa (lamina cribrosa sclerae), the posterior perforated portion of the sclerotic, which at this point is a thin, cribriform lamina. Its largest opening transmits the arteria centralis retinae. 282 HUMAN ANATOMY Arteries, from the ciliary, are few and in a coarse network, the capillaries uniting at long and wide intervals. Nerves, from the ciliary, their mode of ending unknown. The Cornea, or horny body, is the anterior transparent projecting portion of the external tunic of the eyeball, forming about one-sixth thereof. It is set into the sclerotic as a watch-crystal into its case, is of nearly circular base, and its curvature varies in degree in different persons, and in the same person at different ages, becoming flattened in advanced life. It consists of 4 layers, centrally the true fibrous corneal tissue, having in ^ront the conjunctival epithelium; behind, a homogeneous elastic lamina and thyepithelial lining of the anterior chamber. The Conjunctival Epithelium, consists of several layers of epithelial cells, the deepest being columnar, the central polyhedral with processes and the superficial scaly with flattened nuclei. Jj Proper Corneal Substance, a transparent, firm, fibrous structure, con- tinuous with the sclerotic, and composed of about 60 lamella of modified connective tissue, superimposed one on the other, and connected by a cement, in which are spaces of stellate shape, each containing a cell, the corneal corpuscle. The anterior layer of the corneal substance was called by Bowman the anterior elastic lamina. Posterior Elastic Lamina, Membrane of Descemet, or Demours, is a structureless basement membrane, of extreme thinness and trans- parency, the latter being unaffected by water, alcohol or acids; very brittle, exceedingly elastic, and curls up inwardly upon itself, when detached from the true cornea. At the corneal margin it breaks up into fibres, some of which are continuous with the ligamentum pectinatum of the iris. Fontana' s Spaces (spatia anguli iridis), are small, cavernous spaces between the fibres which go to form the ligamentum pectinatum. In some animals, as the ox, they form regular canals. They com- municate with the anterior chamber and with the X j Canal of Schlemm, or Sinus Venosus Sclerce, a minute canal at the internal corneo-sclerotic junction, extending around the circumfer- ence of the attached border of the iris. It. communicates with the anterior chamber through the spaces of Fontana, also with the scleral v veins. Posterior Endothelial Layer (endothelium cameras anterioris), a single layer of flattened, polygonal, transparent, nucleated cells, covers the posterior surface of the elastic lamina, lines the anterior chamber and the spaces of Fontana, and is reflected on to the front of the iris. THE EYE 283 Vessels, none, the capillary vessels terminating in loops at its circum- ference, so that it is practically a non-vascular structure. ^ j Nerves, are numerous; 24 to 36 twigs from the Ciliary nerves form an intricate plexus throughout its laminated substance. THE CHOROID, CILIARY BODY AND IRIS The Middle Tunic (Tunica Vasculosa Oculi) of the Eye is formed from behind forward by the Choroid, the Ciliary Body and the Iris; the former being the vascular ami pigmented tunic; the latter a circular, muscular curtain or septum, with the pupil, an opening in its centre; while the ciliary body connects the choroid with the iris. The Choroid is a thin, vascular membrane, of dark-brown or chocolate color, which invests the posterior ^ of the globe, extending from the optic nerve entrance behind to the ora serrata of the retina. It is loosely connected externally by the lamina fusca to the sclerotic, the space be- tween being the peri-choroidallymph-space, and is covered by a thin mem- brane, the lamina superchoroidea, containing spaces between its constituent lamellae. Internally it is connected with the pigmentary layer of the retina by the lamina basalis or membrane of Bruch, a very thin, structureless membrane. The Choroid terminates anteriorly in the ciliary processes (see below), and is composed of 2 layers, as follows: Lamina Vasculosa, the external layer, consists chiefly of the venae vorticosae, the larger branches of the short ciliary arteries, and dark pigment cells. Lamina Chorio-capillaris or Tunica Ruyschiana, the internal layer, consists of a very fine capillary plexus, formed by the short ciliary vessels. Tapelum, is the name applied to the iridescent appearance seen in the outer and posterior part of the choroid of many animals. Arteries, are the short ciliary and recurrent branches from the long and anterior ciliary arteries. Veins (2), unite into 4 or 5 trunks (4), which pass out through the sclerotic near its equator. Nerves (3), are derived from thej^d, $th and sympathetic, through the long ciliary and the ciliary branches of the ophthalmic ganglion. The Ciliary Body (corpus ciliare) (5), comprises the orbiculus ciliaris, (annulus ciliaris), the ciliary processes, and the ciliary muscle. It con- nects the choroid with the circumference of the iris. The Orbiculus Ciliaris (annulus ciliaris), is a zone about ^ inch wide, directly continuous with the anterior part of the choroid. 284 HUMAN ANATOMY Ciliary Processes, are 60 to 80 folds, formed by the plaiting of the choroid and its lamina basalis at their anterior margin, and are received into corresponding folds of the suspensory ligament of the lens. They form a sort of plaited frill behind the iris, around the margin of the lens, and are similar in structure to the choroid. Ciliary Muscle or Muscle of Bowman (m. ciliaris) , is a ring of un- striped muscular fibres on the outer surface of the anterior part of the choroid, and consists of radiating (fibrae meridianales) and cir- cular fibres (fibrae circulares). The former arise from the corneo- sclerotic junction and pass backward to the choroid in front of the PIG. 89. Nerves Sclera retina. The circular fibres are internal to the radiating ones, have a circular course around the attachment of the iris, and by drawing on the ciliary processes they relax the suspensory ligament of the lens, permitting the lens to become more convex by its own elasticity. It is supplied by the 3d nerve. The Iris (6) is a perforated contractile curtain, suspended in the aqueous humor behind the cornea and in front of the lens, and is the anterior portion of the middle tunic of the eyeball, being continuous with the ciliary body and the choroid. It is about % inch wide, K o o inch thick, and is composed of radiating and circular muscular fibres, a fibrous stroma and pigment cells, covered by a layer of endothelial cells continuous with those of the posterior elastic lamina of the cornea. The THE EYE 285 Pupil (pupilla), is the central opening in the iris, situated a little to the nasal side of the centre, diameter >^2 to Y inch. Ligamentum Pectinatum Iridis, or Dollinger's band, is the suspensory ligament of the iris, connecting its ciliary margin with the posterior elastic lamina of the cornea. Pars Iridica Retina or Uvea, pigmented epithelium of deep purple color, on the posterior surface of the iris. Sphincter Pupillce, a layer of circular muscular fibres around the pupil- lary margin, supplied by the 3d nerve. Dilator Pupilla, radiating muscular fibres from the pupillary margin toward the ciliary border, supplied by fibres of the sympathetic from the ciliary ganglion. Membrana Pupillaris, a vascular membrane which covers the pupil in the foetus, disappearing about the eighth month, occasionally perma- nent. Arteries, are derived from the long and anterior ciliary, forming the circulus major at the ciliary border, and the circulus minor near the pupillary margin. Veins, empty into those of the ciliary processes and the anterior ciliary veins. Nerves of the Iris, are derived from the 3d, 5th and the sympathetic, through the long and short ciliary nerves. The 3d supplies the circular fibres, the sympathetic the radiating ones, the 5th being nerves of common sensation. THE RETINA (TUNICA INTERNA) The Retina, the innermost or nervous tunic of the eye, is a delicate, grayish, transparent membrane, about ^75 of an inch thick at the fundus, 3^oo inch at the anterior margin. It is formed by a membranous ex- pansion of the optic nerve elements, and extends from the termination of that nerve nearly as far forward as the ciliary processes, terminating in a jagged margin, the or a serrata, though its fibrous stroma is continued as the pars ciliaris retina over the ciliary body. The Retina presents for examination the following points: Macula LiUea, or Yellow Spot, situated on the retina, exactly in the visual axis; in an elevated oval spot where vision is very acute, the retina being very thin and full of nerve elements closely packed together at the expense of its connective tissue. No rods, no nerve- fibre layer here, but the cones and ganglion-cells are very numerous. Fovea Centralis, a depression at the centre of the macula lutea, M 25 to Ko inch in diameter, in which the sense of vision is most acute. 286 HUMAN ANATOMY Porus Opticus or Optic Disk, the point where the optic nerve enters, lies about % inch internal to the yellow spot. It is often called the blind spot, being the only part of the fundus from which the power of vision is absent. Cotticulus Nervi Optici or Optic Papilla, is a slight eminence of the nervous substance at the porus opticus; the central artery of the retina pierces its centre which is depressed slightly, forming the Optic Cup (excavatio papillae nervi optici). Pars Ciliaris Retina, is that portion of the retinal stroma which is prolonged over the ciliary body, and continued over the back of the iris as the pars iridica retina. It is destitute of nerve-elements. Arteries of the Retina, arise from the arteria centralis retinas (branch of the ophthalmic artery), just behind the porus opticus; run chiefly upward and downward, accompanied by veins, to terminate in a minute capillary plexus. They do not anastomose with each other, being terminal arteries. No vessels exist in the fovea centralis, and only the finest capillaries in the macula lutea. Structure of the Retina. The retina is composed of nervous elements, blood-vessels, pigmented epithelium, and modified connective tissue re- sembling the neuroglia of the brain; the latter being called the radiating fibres or fibres of Mutter, which form the two limiting membranes and stretch between them, passing through all the nervous layers except Jacob's membrane. The structures are arranged in 10 layers, as follows: Membrana Limitans Interna, derived from the supporting frame-work and shown in the cut by the lowest line. Layer of Nerve-fibres (stratum opticum) (i), formed by the expansion of the optic nerve, the fibres of which, as simple axis-cylinders, pass through all the succeeding layers of the retina. Ganglionic Layer (2), a single layer of large ganglion-cells, which give off their axons into the preceding layer and their dendrites into the inner molecular layer. Inner Plexiform Layer (3), is made up of a dense reticulum of minute fibrils, formed by the interlacement of the dendrites of the ganglion- cells with those of the cells of the next layer. Inner Nuclear or Granular Layer (4), consists of closely packed cells of 3 kinds, bipolar, amacrine, and cells connected with the fibres of Miiller. Outer Plexiform Layer (5), a dense network of minute fibrils derived from the processes of the cells in the adjoining layers. Outer Nuclear or Granular Layer (6), contains several strata of oval nuclear bodies, named rod-granules and cone granules, which are THE EYE 287 FIG. 90. respectively continuous with the rods and cones of Jacob's membrane. Membrana Limitans Externa, derived from the supporting frame- work of the retina, is shown in the cut by a horizontal line between layers 6 and 7. Jacob's Membrane, or Layer of Rods and Cones (7), the perceptive portion of the retina, is composed of a palisade-like arrangement of rods and cones, the terminal organs probably of the optic nerve fibres. Pigmentary Layer, or Tapetum Nigrum (8), formerly described as a part of the choroid, consists of a single layer of hexagonal epithelial cells, loaded with pigment-granules. It extends with the retinal stroma as the pars ciliaris retina, (see page 285), beyond the ora serrata, where the nervous layers terminate. REFRACTING MEDIA The Aqueous Humor (humor aqueus) is a clear, alkaline, serous fluid, composed of water 96.7, albumen o.i, chloride of sodium and extractive matters 3.2, weighing 4 to 5 grains, and filling the anterior (camera oculi anterior) and posterior aqueous chambers (camera oculi posterior) which communicate with each other when the pupil is dilated sufficiently to remove the pupillary margin of the iris from the surface of the lens. The Anterior Chamber (camera oculi anterior) of the Eyeball, has the cornea in front and the iris behind. The peripheral angle of this chamber is called the Fil- tration Angle (angulus iridis). Posterior Chamber (camera oculi posterior) of the Eyeball, is a narrow chink between the peripheral part of the iris, the suspensory ligament of the lens, and the ciliary processes. The Vitreous Body (corpus vitreum) is a transparent jelly-like sub- stance, composed of an albuminous fluid enclosed in a delicate membrane, 288 HUMAN ANATOMY also transparent and named the hyaloid membrane (membrana hyaloidea). It is apparently structureless, has neither vessels nor nerves, and is situated in the concavity of the retina, which it fills, forming about Y of the entire globe. Running antero-posteriorly in its centre is a canal, filled with fluid, and lined by a prolongation of the hyaloid membrane, called the Canal of Stilling (canalis hyaloideus), which in the foetus conveyed the hyaloid artery to the membrana pupillaris. It extends from the entrance of the optic nerve, forwards directly through the centre of the vitreous humor to the back of the crystalline lens. Fossa Patellaris, is a deep concavity on the front of the vitreous, for the posterior convex surface of the lens. Hyaloid Membrane, is the delicate capsule which encloses the vitreous humor, and has been supposed to give off delicate septa into its sub- stance. In front of the ora serrata it is thickened and is termed the Zonula Ciliaris or Zonule of Zinn, presents a series of furrows, radially arranged, for the reception of the ciliary processes. It splits into 2 layers, one of which lines the fossa patellaris, the other is the Suspensory Ligament of the Lens, passes over the ciliary body to be attached to the capsule of the lens. Canal of Petit (spatia zonularia), a sacculated canal, behind the suspensory ligament, encircles the equator of the lens, and lies between the two layers into which the zonule of Zinn is split. The Crystalline Lens (lens crystallina) is a bi-convex, elastic, trans- parent body, enclosed in a capsule, held in place by a suspensory ligament, and situated immediately behind the pupil and in front of the vitreous body, in the fossa patellaris of which its posterior and most con- vex surface rests. The ciliary processes en- circle it and slightly overlap its margin. It consists of concentric layers formed of minute parallel fibres, which are hexagonal prisms with dentated edges fitting accurately into each other. Faint lines, six or more in number, radiate from the anterior and posterior poles to the circumference and correspond to the free edges of septa in the lens. The external layers are soft, the deeper are firmer, and the central ones form a hard nucleus, the nucleus lentis. The lens is unorganized, having neither vessels nor nerves, but is nourished by imbibition from neighboring structures, possibly from the aqueous humor. Its Capsule (capsula lentis), is transparent, elastic, iHjooo i ncn thick antreiorly, Hooo inch posteriorly; has a layer of flat cells between its THE EYE 289 anterior portion and the lens, which, after death, break down into a fluid, the liquor morgagni. Suspensory Ligament, connects the capsule with the ciliary body, and is the anterior of the two layers formed by the splitting of the zonule of Zinn (zonula ciliaris) (see p. 287). It is shown exaggerated in the cut. Canal of Petit, (spatia zonularia), is a triangular space around the circumference of the lens, formed by the separation of the two por- tions of the zonule of Zinn (zonula ciliaris) (shown inflated in the cut). MUSCLES AND NERVES OF THE EYEBALL Muscles of the Eyeball, are 6 in number, 4 Recti and 2 Oblique, which are inserted into the sclerotic coat (tunica fibrosa), just behind the margin of the cornea. The insertions of the superior, inferior, internal and ex- ternal recti correspond to the ends of the four FIG. 92. , .... arms of an equal-armed cross, imagined to exist behind the corneo-sclerotic junction. The inser- tion of the superior oblique (14) lies between the insertions of the superior and external rect, that of the inferior oblique (13) somewhat behind the insertion of the superior oblique. These muscles are described on page 76. The tendon of the superior oblique passes through a pulley or trochlea on the internal angular process of the frontal bone, before being inserted into the eyeball: (see Fig. 92). Nerves supplying the muscles of the eyeball are the 3d, 4th and 6th cranial nerves; the 3d supplies the superior, inferior and internal recti and the inferior oblique, the 4th supplies the superior oblique, and the 6th supplies the external rectus. VESSELS OF THE EYE Arteries supplying the eye and its appendages are, the Ophthalmic and Anterior Cerebral branches of the internal carotid artery; and the Infra-orbital branch of the internal maxillary, from the external carotid. The Ophthalmic Artery arises from the cavernous portion of the internal carotid, enters the optic foramen to the orbit, and gives off the following branches to the eye and its appendages: Arteria Centralis Retina (2), pierces the optic nerve (i) obliquely, and is distributed to the retina. Muscular Branches, 2, superior and inferior, supply the muscles of the eyeball, and give off the anterior ciliary (see below). 2QO HUMAN ANATOMY Lacrintal, to the lacrimal gland, the eyelids, and the conjunctiva, anastomosing with the palpebral. Supra-orbital, supplies the superior rectus and levator palpebrae muscles. Internal Palpebral (aa. palpebrales mediales), superior and inferior, to the eyelids. Nasal, (a. dorsalis nasi), to the lacrimal sac, and the nose. Short Ciliary (aa. ciliares posteriores breves), 6 to 12, pierce the sclerotic at the lamina cribrosa, supplying the choroid and the ciliary processes. Long Ciliary (aa. ciliares posteriores longag), 2, pierce the sclerotic, and pass forward between it and the choroid, to supply the iris, forming two arterial circles thereon, the circulus major at the ciliary border, and the circulus minor near the pupillary margin. Anterior Ciliary (aa. ciliares anteriores) (3), arise from the muscular branches, form a zone beneath the conjunctiva, then pierce the sclerotic, and join the circulus major on the iris. Anterior Cerebral, branch of the Internal Carotid, sends nutrient capillaries to the optic nerve. Infra-orbital, branch of the Internal Maxillary artery, sends branches to the inferior rectus and inferior oblique muscles, and to the lac- rimal gland. Veins of the Eye are collected into two main trunks, the Superior and Inferior Ophthalmic Veins, which empty into the cavernous sinus, after collecting the blood from the smaller venous channels through the Vena Vorticosa of the choroid. The veins of the eye anastomose freely with the facial veins, thus permitting the escape of venous blood in either direction. Lymph-spaces of the Eye. The principal lymph-spaces found in the eyeball and its connected structures are the Canal of Schlemm (sinus venosus sclerae), around the circumference of the iris. Peri-choroidal Space, between the choroid and the sclerotic (tunica fibrosa). Peri-sclerotic Space, between the sclerotic (tunica fibrosa) and the capsule of Tenon (fascia bulbi), is continuous with the subdural and subarachnoid spaces. Vaginal Spaces, have been described as existing between the sheaths of the optic nerve. NERVES OF THE EYE Nerves of the Eye. Besides the 3d, 4th and 6th nerves, already men- tioned as supplying the muscles of the eyeball, the eye is supplied with THE EYE 291 common sensation by branches from the ophthalmic division of the 5th and the ophthalmic ganglion, also motor filaments from the 5th, and its special sense of sight, from the 2d or optic nerve. The Sympathetic Branches, arise from the medulla, and the cavernous and carotid plexuses, and join the 3d, 4th, 5th, and 6th nerves, send- ing filaments to the dilator fibres of the iris, to the muscles of the orbit and lids, to the ophthalmic ganglion, and to the walls of the arteries. Short Ciliary, some 6 to 10 in number, arise from the ophthalmic ganglion (see page 224), pierce the sclerotic and go to the ciliary muscle, iris, cornea, and to the sheath of the optic nerve. Ascending, from Meckel's (spheno-palatine) ganglion (see page 224). enter the orbit by the spheno-maxillary fissure, going to the 'optic nerve, the 6th nerve, and the ciliary ganglion. FIG. 93. CILIARY GANGLION The Optic Nerve, 2d Cranial (Plate 6, page 244), begins at the anterior part of the optic commissure, passes into the orbit by the optic foramen in company with the ophthalmic artery, is pierced by the central artery of the retina, and enters the eyeball posteriorly % inch inwardly from its axis, piercing the sclerotic (tunic fibrosa) and choroid coats, and finally expanding in the retina. f It is surrounded by a tubular process of dura mater, which as the nerve enters the orbit, subdivides to form both the sheath of the nerve and the periosteum of the orbit. The two nerves are connected together at the commissure, from the back of which most of their fibres may be traced through the optic tracts to the lower visual centres 2Q2 HUMAN ANATOMY of the brain, viz. the external (lateral) geniculate body, the upper quadrigeminal body, (colliculus superior), and the pulvinar of the optic thalamus. The Optic Commissure or Chiasma (Plate 6, page 244), is seen at the base of the brain in front of the tuber cinereum and behind the lamina cinerea. It contains four sets of fibres, one of which decussates in the commissure with its fellow set of the opposite side. The four sets of fibres are arranged in the following manner: Crossed or Decussating Fibres (i), are the most numerous; lying in the centre of the commissure, they pass from the optic tract of one side to the optic nerve of the other side, con- necting the retina of each eye with the op- FlG * posite hemisphere of the brain. Uncrossed or Longitudinal Fibres (2), occupy the outer sides of the commissure and tracts, passing from the tracts to the nerves of the same sides, and connecting the tem- poral side of each retina with the cerebral hemisphere of its own side. Inter-retinal Fibres (3), in the anterior portion of the commissure, pass from one optic nerve to the other, connecting the nasal sides of the retinas of both eyes with each other. Commissural Fibres (4) or Commissure of Gudden, in the posterior por- tion of the commissure, have nothing to do with vision, but pass from one internal (medial) geniculate body to the other, or to the op- posite posterior quadrigeminal body (colliculus inferior) (Whitaker). The Optic Tract arises from the brain by two bands, an external and an internal. The external (lateral) band arises from the external (lateral) geniculate body, the upper quadrigeminal body (colliculus superior) and the pulvinar of the optic thalamus, the lower visual centres. The internal (medial) band arises from the internal (medial) geniculate body and the inferior quadrigeminal body (colliculus inferior), most of its fibres being commissural between the two internal (medial) geniculates. The two bands wind around the crus (cerebral peduncle) and join together opposite its centre in a flattened band, which becomes cylindrical and continues on to connect with the tract of the opposite side in the optic commissure. In its course the tract is attached to the surface of the crus by its anterior margin, and receives some fibres from the tuber cinereum and the lamina cinerea (lamina terminalis). Meynert's Commissure (fasciculus retroflexus), consists of the fibres THE EYE 293 from the epithalamic habenular nucleus, which cross in the optic commissure and enter the crus (cerebral peduncle) on the opposite side, passing obliquely through the red nucleus into the hypothalamic nucleus. It is concerned with olfactory impulses. Visual Centres in the Brain. The lower visual centres are the external (lateral) geniculate body, the upper quadrigeminal body (colliculus superior), and the pulvinar of the optic thalamus, to which the optic nerve fibres are traced. From these nuclei other fibres go to the cortical visual centre, which is located in the cuneus of the occipital lobe, and probably also in the adjacent lingual lobule of the temporal lobe, APPENDAGES OF THE EYE The Tutamina Oculi (organa oculi accessoria) or appendages of the eye, include the eyebrows, the eyelids, the conjunctiva, the lacrimal gland, the lacrimal sac, and the nasal duct (ductus naso-lacrimalis). The Eyebrows, or Supercilia, are two arched eminences of thickened integument over the supra-orbital arches, and connected beneath with the orbicularis palpebrarum, corrugator supercilii and occipito-frontalis mus- cles. They are covered with short, thick hairs, and are drawn downward and inward by the corrugator supercilii: (see page 75). The Eyelids, or Palpebrae, are two thin, movable folds, placed in front of the eye, for its protection. The upper lid is the more movable one, having its own levator muscle, the levator palpebrae superioris. They are composed externally of skin, internally of mucous membrane (the palpebral conjunctiva), and between these lie areolar tissue, the orbicularis muscle, tarsal cartilage, fibrous membrane, Meibomian glands (glandulae tarsales), vessels and nerves. The upper lid has, in addition, the aponeurosis of the levator palpebrae. Eyelashes, or Cilia, are a double or triple row of short hairs, situated on the free margins of the lids; their follicles lying in the connective tissue beneath the tarsal cartilages. Glands of Moll (glandulae ciliares), are enlarged and modified sweat- glands, the openings of which are in several rows, near the attachment of the eyelashes. Palpebral Fissure (rima palpebrarum), is the space between the free margin of the lids, its outer and inner angles being termed respect- ively the external (commissura palpebrarum lateralis) and internal (commissura palpebrarum medialis) canthus. Lacus Lacrimalis, is a small triangular space at the internal canthus, between the lids and the globe. 294 HUMAN ANATOMY Lacrimal Papilla, on the edge of each lid, about 34 inch from the internal canthus. Punctum Lacrimale, a minute orifice on each papilla, and the beginning of the lacrimal canal. Tar sal Plates (tarsi), are two thin, elongated plates of dense connect- ive tissue, about an inch in length, placed one in each lid, giving it form and support. The upper one is crescentic in shape, the lower one is elliptical and smaller. Tar sal Ligaments, external (ligamentum palpebralis laterale), con- nects the outer angle of the tarsal plate to the malar bone. The internal (ligamentum palpebralis mediale) connects the inner angle of the plate to the nasal process of the maxilla. The internal one is often called the tendo oculi. Meibomian Glands (glandulae tarsales) (i), are sebaceous glands em- bedded in grooves in the inner surface of the tarsal plates, about 30 in the upper eyelid, less in the lower one. Their ducts open on the inner FlG- 95- edge of the free margin of the lids by minute foramina, through which their secretion is furnished to pre- vent the lids adhering to each other. Muscles, the palpebral portion of the orbicularis muscle is very thin and pale; the tensor tarsi compresses the punctum lacrimale and the lacrimal sac: (see page 75). Arteries, are the palpebral branches of the ophthalmic artery, forming the superior and inferior tarsal arches, and anastomosing with the orbital branch of the temporal, the lacrimal, transverse facial, and angular arteries. Nerves y the 3d, facial, and sympathetic to the muscles; the 5th to the skin and conjunctiva. The Conjunctiva (Tunica Conjunctiva) is the mucous membrane lining the inner surface of the eyelids, and reflected over the front of the sclerotic and cornea. It is continuous with the mucous lining of the Meibomian glands (glandulae tarsales), lacrimal ducts, lacrimal sac,naso-lacrimal duct, duct and lacrimal gland. The Palpebral Conjunctiva (tunica conjunctiva palpebrarum), consists of connective tissue covered by epithelium, is traversed by furrows, and has papillae, follicular glands, and lymphoid tissue. THE EYE 295 Ocular Conjunctiva (tunica conjunctiva bulbi), is very thin and transparent, loosely attached on the sclerotic, firmly adherent over the cornea, where it has no vessels in its structure. It has very few papillae, and no glands. Palpebral Folds, superior and inferior, are where the conjunctiva is reflected over the globe, the fornix conjunctiva lying between them, and containing mucous glands and trachoma glands, the latter being analogous to lymphoid follicles. Plica Semilunaris, or Semi-lunar Fold, a crescentic fold of conjunctiva at the inner canthus, considered to be the rudiment of the membrana nidi tans or 3d eyelid of birds. Caruncula lacrimalis, is a small, red, conical body, situated in the lacus lacrimalis, at the inner canthus of the eye; consisting of a small island of skin, containing sebaceous and sweat glands, and a few slender hairs. It is the source of the whitish secretion which collects at the inner angle of the eye. It is connected by tendinous fibres to the capsule (fascia bulbi) of Tenon and to the rectusinternus muscle. The Lacrimal Gland (i) is an oval gland situated in a depression on the orbital portion of the frontal bone, at the outer angle of the orbit, its inferior surface resting on the eyeball, its lower margin or lobe being covered by conjunctiva. Its front portion is separated from the rest of the gland by a fibrous septum, and is called the accessory gland of Rosenmiillcr (glandula lacrimalis inferior). Its ducts, from 6 to 12 in number, open by a row of orifices on the upper and outer por- tion of the palpebral conjunctiva. Its secretion, the tears, lubricates the sur- face of the eyeball; the excess evapo- rating or being collected in the lacus, from which it passes through the puncta (2) into the canaliculi (3) and the lacrimal sac (4), and thence by the naso-lacrimal duct (5) to the inferior meatus of the nose. The Canaliculi (3) or lacrimal canals are two minute canals, ^5 inch in diameter and Y$ inch long, which extend from the punctum (2) in each lid to the lacrimal sac (4). They are lined with mucous membrane, and enveloped by fibres of the tensor tarsi muscle. FIG. 96. 296 HUMAN ANATOMY The Lacrimal Sac (4) is the superior dilated extremity of the nasal duct (5), and is situated in the groove formed by the lacrimal bone and the nasal process of the maxilla. Its form is oval, flattened antero- posteriorly; its dimensions about % inch long and % inch wide. Its fundus is crossed by the tarsal ligament, and by the tensor tarsi muscle. Its junction with the nasal duct may be interrupted by folds of the lining mucous membrane. The Nasal Duct (ductus naso-lacrimalis) (5) is a membranous canal extending from the lacrimal sac to the inferior meatus of the nose. It is about % inch long, ^ inch in diameter, is contained in the osseous lacrimal canal, curving downward, backward and outward, and its calibre is narrowest about its middle. Its mucous lining is thick, and continuous with the Schneiderian membrane of the nasal cavity. The Valve of Hamer (plica lacrimalis), is an imperfect valve at the terminal ' orifice (6) of the naso-lacrimal duct, and is formed by a fold of mucous membrane. THE EAR (AURIS OR ORGANON AUDITUS) The Organ of Hearing is divisible into 3 parts the external ear (auris externa), the middle ear (auris media) or tympanum, and the internal ear or labyrinth (auris interna) ; which are situated in or upon the mastoid and petrous portions of the temporal bone (described on page 20): The External Ear (auris externa), consists of the auricle or pinna, and the auditory canal (meatus acusticus externus), which extends to the membrana tympani. Middle Ear or Tympanum (auris media), consists of the atrium or tympanic cavity proper (cavum tympani), and the attic or epitym- panic recess; it contains the membrana tympani, the ossicles of the tympanum (ossicula auditus) and the tympanic orifice of the Eus- tachian tube (tuba auditiva). Internal Ear or Labyrinth (auris interna), consists of the osseous labyrinth (labyrinthus osseus) and the membranous labyrinth (labyrinthus membranaceus), the latter being contained within the former, which comprises the vestibule (vestibulum), the semicircular canals (canales semicirculares ossei), and the cochlea. The mem- branous labyrinth (labyrinthus membranaceus) consists of the utricle (utriculus), the saccule (sacculus), and the membranous semicircular canals (ductus semicirculares), and contains the terminal filaments of the auditory nerve (n. acusticus). THE EAR 297 THE EXTERNAL EAR (AURIS EXTERNA) The Auricle or Pinna (auricula) is the external irregularly shaped appendage, fastened to the malar and temporal bones by ligaments. It consists of a thin plate of yellow fibro-cartilage, deficient in places where its parts are joined together by fibrous tissue, and is covered by peri- chondrium and integument, the latter containing sebaceous and sweat glands, and provided with short, downy hairs. The Auricle presents several elevations and depressions, which are due to the folding of its cartilage, and are named as follows: Helix, the outer curved edge of the pinna, beneath which is a deep groove, the fossa navicularis (scapha) or fossa of the helix. Anti-helix, a curved ridge, parallel with and in front of the helix, bifur- cating above forming the crura antihelicis which enclose a triangular depression, the fossa triangularis auriculae. Concha Auricula, the central cavity leading into the auditory canal (meatus acusticus externus). Tragus,-^-& conical eminence in front of the concha, usually covered with hair along its inferior border. Anti-tragus, a smaller projection facing the tragus, from which it is separated by a deep fissure, the incisura intertragica. Tubercle (tuberculum auricula} of Darwin, a small tubercle frequently seen, where the helix turns downward. Lobe or Lobule Auricula, the soft, pendulous portion, composed of integumentary, adipose and connective tissues. Muscles of the Auricle. The extrinsic muscles are the Attollens, Attrahens and Retrahens Auriculam, described on page 75. The intrinsic muscles are very slightly developed (see page 79) and are the / Musculus Hdicis Major, vertically on the anterior border of the helix. ^_ Musculus Helicis Minor, on the lateral surface of the root of the helix. Musculus Tragicus, lies vertically on the outer surface of the tragus. Musculus Anti-tragicus, on the^posterior wall of the auditory canal. Musculus Transversus Auricula, on the posterior surface of the auricle, radiating outward from the convexity of the concha. Musculus Obliquus Auricula, also on the posterior surface, radiating upward from the convexity of the concha. The Auditory Canal (meatus acusticus externus) is an osseo-cartilaginous tube, about i finches long, extending from the concha to the membrana tympani, and curved irregularly in its course. The cartilaginous, or external portion, is about ^ inch long, and deficient posteriorly and above, where it is filled by strong fibrous tissue. The canal is lined with integu- 298 HUMAN ANATOMY ment, having numerous hair follicles, sebaceous and ceruminous glands. Its relations are in front, the condyle of the lower jaw; below and in front, the parotid gland; behind, the mastoid cells and the lateral sinus, separated from it by a very thin bony plate; above, the mastoid cells and the dura mater of the brain, separated from it by a thin osseous plate. The Sulcus Tympanicus, is a circumferential groove at the bottom of the canal for the insertion of the membrana tympani. It is interrupted above by a notch, the incisura Rivinii. Vessels and Nerves. The Arteries of the auricle are derived from the external carotid artery, viz. the anterior and posterior auricular, and the auricular branch of the occipital. Those of the auditory canal are branches from the posterior auricular, internal maxillary, and temporal arteries. The Nerves of the canal are derived from the temporo-auricular branch of the maxillary division of the 5th, and the auricular branch of the Vagus. Those of the auricle are the Auricularis Magnus, from the cervical plexus. Auricular, branch of the vagus (also called Arnold's nerve). Auriculo-iemporal, branch of the mandibular div. of the 5th. Occipitalis Major, from the post, division of the 2nd cervical nerve. Occipitalis Minor,' from the cervical plexus. Posterior Auricular, branch of the facial, to the muscles. THE MEMBRANA TYMPANI The Membrana Tympani, or Drumhead, is an oval, inelastic, semi- transparent membrane, about ^50 inch in thickness, situated obliquely at the bottom of the auditory canal, inclined inward and forward, so as to form almost a continuation of the posterior wall of the canal. As seen through the canal, it is of a delicate blue-gray color, arched inward, and presents for consideration the following points: Malleolar Eminence, white in color at the upper border, made by the short process of the malleus behind. Malleolar Stripe, also white, running downward from the eminence and formed by the handle of the malleus behind. Light-spot, a triangular reflection, its apex at the tip of the malleus handle, its base extending to the periphery of the membrane. It is due to the concavity of the exterior surface of the membrane. Umbo, or Navel, is the dark, central, depressed part of the membrane. ShrapnelVs Membrane (pars flaccida), is the upper posterior part of the drumhead, where it is somewhat flaccid. THE EAR 2Q9 Structure. The Membrana Tympani is composed of 3 layers, an ex- ternal or cuticular layer (stratum cutaneum), a middle or fibrous (mem- brana propria), and an internal or mucous layer (stratum mucosum). Its circumference is thickened to form an incomplete ring (annulus fibrocartilagineus), which is received into the sulcus tympanicus at the inner end of the auditory canal. The anterior and posterior ends of this ring are shown by (z>) and (h) in the figure. The External or Cuticular Layer (stratum cutaneum), is derived from the integument lining the audi- tory canal (meatus acusticus externus). Middle or Fibrous Layer (membrana propria), consists of an outer layer of fibres which radiate from the handle of the malleus; and an inner layer of circular fibres, most numerous around the circumference. Between these two sets of fibres are situated the short process and handle of the malleus. Internal or Mucous Layer (stratum mucosum), is continuous with the mucous lining of the tympanum. The Internal Surface of the Membrana Tympani is convex, and presents the curved handle of the malleus pointing downward between its layers, also the chorda tympani nerve passing along the upper margin to the iter chordae anterius in the Glaserian (tympano-squamous) fissure. Nerves and Vessels. The Membrana Tympani receives its nervous supply from the auriculo-temporal branch of the mandibular, the auricular branch of the vagus and the tympanic branch of the glosso-pharyngeal. The Veins open into the external jugular, except those on the inner surface, which drain partly into the lateral sinus and veins of the dura mater, and partly into a plexus on the Eustachian tube (tuba auditiva). The Arteries are the Deep A uricular, branch of the internal maxillary, supplies the external layer, and forms with the tympanic branches a capillary plexus in the middle layer. Tympanic Branches, of the internal maxillary and internal carotid arte- ries, supply the internal layer, the former with the stylo-mastoid artery forming a vascular circle around the membrane, and both anastomosing on the membrane with the Vidian (a. canalis pterygoidea), branch of the internal maxillary, and the Stylo-mastoid, from the posterior auricular branch of the external carotid. 3OO HUMAN ANATOMY THE MIDDLE EAR OR TYMPANUM (AURIS MEDIA) The Tympanum, or Drum (auris media), is an irregular cavity within the petrous portion of the temporal bone, lying between the membrana tympani and the tympanic surface of the petrous bone and communicating with the naso-pharynx by the Eustachian tube (tuba auditiva). It contains the ossicles (ossicula auditus) of the tympanum, part of the chorda tympani nerve, and air. Its average diameters are about % inch antero-posteriorly, ^ to % inch vertically, and 3-f 2 to ^ inch transversely. It consists of two parts, the atrium or tympanic cavity proper (cavum tympani), opposite the tympanic membrane; and the-fl&ix; or epitympanic recess above, containing the upper half of the malleus and the greater part of the incus. Its roof and floor are formed by thin osseous laminae, the floor separating it from the jugular fossa and vein, and presenting, near the inner wall, a small aperture for, Jacol 'son's nerve (tympanic branch of the glosso-pharyngeal). The other walls cf the tympanum present for examination the following points: OUTER WALL (paries membranacea), is formed by the membrana tympani and presents the Her Chorda Posterius, opens close to the posterior edge of the drum- head, for the passage of the chorda tympani nerve. Her Chorda Anterius (canal of Huguier), opens just in front of the drumhead, for the passage of the chorda tympani nerve. Glaserian (tympano-squamous) Fissure, opens above and in front of the drumhead, receiving the long process (processus gracilis or anterior) of the malleus, the anterior ligament of the malleus, (laxator tympani tendon) and the tympanic branch of the internal maxillary artery. INNER WALL (paries labyrinthica), is the outer wall of the labyrinth, presents the Fenestra Vestibuli or Ovalis, an oval opening, leading into the vestibule, and closed by a membrane, to which is attached the base of the stapes. Fenestra Cochlea or Rotunda, a smaller opening, below the fenestra vestibuli, leading into the scala tympani of the cochlea, and closed by the membrana tympani secundaria, a membrane of 3 layers. Promontory, an elevation corresponding to the first turn of the cochlea, situated between the fenestras and in front of them. It is grooved by the tympanic plexus. Ridge of the Aquceductus Fallopii (prominentia canalis facialis), above the fenestra vestibuli, behind which it curves downward along the posterior wall. POSTERIOR WALL (paries mastoidea), separates it from the mastoid cells, and presents the THE EAR 301 Opening of the Tympanic or Mastoid Antrum, which in turn com- municates with the mastoid cells. Pyramid (eminentia pyramidalis), a hollow conical eminence, behind the fenestra vestibuli, contains the stapedius muscle, and a minute canal communicating with the aquaeductus Fallopii (canalis facialis) and transmitting a nerve to the stapedius. ANTERIOR WALL (paries carotica), separates it from the carotid canal, and presents the Opening of Canal (semicanalis m. tensoris tympani) for the Tensor Tympani Muscle, above, situated on a small projection, sometimes called the anterior pyramid. Opening of the Eusiachian Tube (semicanalis tubae auditivae), next below, the two canals being separated from each other by a thin, horizontal, bony plate, the processus cochleariformis (septum canalis musculotubarii) . The Ossicles (ossicula auditus) of the Tympanum are three small bones, which form a chain across the tympanic cavity, connecting the mem- brana tympani with the fenestra vestibuli, and named the Malleus, or Hammer (A), consists of a head, neck, short process (processus lateralis), long process or processus gracilis (processus anterior), and handle or manubrium. The short process and handle are fastened to the middle layer of the drumhead. The long process (never found in adults) is received into the Glaserian (tympano-squamous) fissure, and the head articulates with the head of the incus. Incus, or Anvil (B), resembles a two-pronged tooth; it has a head, also a long and a short process. The head articulates with the head of the malleus, the short process with the fossa incudis in the epitym- panic recess, the long process with the head of the stapes, by the os orbictdare, its convex extremity. Stapej,.or Stirrup (C), presents a head, neck, base and two crura. Its head articulates with the incus, its base rests on the membrane clos- ing the fenestra vestibuli, its neck receives the tendon of the stapedius muscle. Ligaments of the Ossicles are 5 in number, besides the capsular ligaments of their articulations, 3 for the malleus, i for the incus, and i for the stapes, as follows: 3O2 HUMAN ANATOMY Anterior Ligament of the Malleus, is the degenerated laxator tympani muscle, from the neck of the malleus through the tympano-squamous fissure or its petro-tympanic subdivision to the base of the alar spine of the sphenoid. It is an active muscle in most infants and about 75 per cent, of adults. Superior of the Malleus, from the head of the malleus to the roof of the epitympanic recess. External of the Malleus, from the short process of the malleus to the posterior part of the notch in the tympanic ring. Posterior of the Incus, from the end of the short process of the incus to the posterior part of the epitympanic recess. [The so-called supe- rior ligament of the incus is merely a fold of mucous membrane.] Annular Ligament of tfte Stapes (ligamentum annulare baseos stapedis), around the circumference of the base of the stapes, connecting it to the margin of the fenestra vestibuli. Muscles of the Tympanum are 2, the Tensor Tympani Stapedius and the laxator tympani. Tensor Tympani, arises from the under surface of the petrous portion of the temporal bone, the cartilaginous Eustachian tube (pars car- tilaginea tubae auditivae), and its own osseous canal (semicanalis m. tensoris tympani); and is inserted into the handle of the malleus. It draws the membrana tympani inward and tense. Its nerve is a branch from the trigeminal, through the otic ganglion. Stapedius, arises from a conical cavity in the interior of the pyramid; its tendon emerges from the orifice at the apex of the pyramid, and is inserted into the neck of the stapes. It draws the head of the stapes backward, and probably compresses the contents of the vestibule. Its nerve is the tympanic branch of the facial. Laxator Tympani, see anterior ligament of malleus (see page 80). Vessels of the Tympanum. The Veins terminate in the pterygoid plexus and in the superior petrosal sinus. The Arteries are 6 in number, as follows: Tympanic, branch of the internal maxillary, entering by the petro tympanic fissure, anastomosing on the membrana tympani, in a vascular circle with the Stylo-mastoid and Vidian arteries, and the Tympanic br. of the internal carotid. Stylo-mastoid, br. of the posterior auricular br. of the external carotid entering at the stylo-mastoid foramen. Petrosal; br. of middle meningeal artery, entering by the hiatus Fallopii. Tympanic, br. from the internal carotid artery. THE EAR 303 Branch from tJie Ascending Pharyngeal,-^irom the external carotid; also accompanying the Eustachian tube. Nerves of the Tympanum. Besides the nerves supplying the two muscles (see above), the Chorda Tympani Nerve enters the tympanum by the iter chordae posterius, crosses the cavity between the handle of the malleus and the long process of the incus, and makes its exit by the iter chordae anterius, after passing close along the upper part of the membrana tympani. The mucous membrane lining the tympanum is supplied by the branches of distribution of the Tympanic Plexus, which lies on the inner wall around the promontory, and is formed by the Tympanic Branch of the Glosso-pharyngeal, also known as Jacobson's nerve, enters by an aperture in the floor near the inner wall. Small Deep Petrosal, from the carotid plexus of the sympathetic, enters from the carotid canal. Small Superficial Pelrosal, from the otic ganglion, enters near the canal for the tensor tympani muscle. Branch from the Great Superficial Pelrosal, enters through the inner wall, just in front of the fenestra vestibuli. The Eustachian or Auditory Tube (tuba auditiva) is an osseo-car- tilaginous canal, about i% inches long, ^2 to ^3 inch in diameter, which forms a channel of communication between the tympanum and the pharynx. It passes obliquely downward, forward and inward, from the anterior wall of the tympanum to the naso-pharynx, where it ends in an oval orifice on the side wall of the pharynx just behind the inferior meatus of the nose. The osseous part (pars ossea tubae auditivae), ^ inch long, terminates at the retiring angle of junction of the petrous and squamous portions of the temporal bone, in a jagged margin, to which the cartilaginous part (pars cartilaginea tubae auditivae) is attached. The latter, i inch long, is formed by a triangular plate of elastic fibro-cartilage, folded on itself above so as to leave a deficiency below, which is filled by fibrous tissue. This portion of the tube expands as it descends into a trumpet-shaped lower extremity. The tube is lined by ciliated mucous membrane, con- tinuous with that of the tympanum and pharynx, and containing mucous glands, also adenoid tissue near its lower end. The Tube-tonsil of Gerlach, is formed by the adenoid tissue in the mucous lining near the pharyngeal orifice. Isthmus, is the narrowest part of the tube, at the junction of the osseous and cartilaginous portions. Muscles, are the dilator tubae fibres of the tensor palati (m. tensor 304 HUMAN ANATOMY veli palatini), which open the tube during deglutition, aided by the salpingo-pharyngeus when present. The levator palati closes the pharyngeal orifice. For these muscles see page 80. Arteries, are the ascending pharyngeal, from the external carotid, and the Vidian (a. canalis pterygoidea) from the internal maxillary. Nerves, are pharyngeal branches from the glosso-pharyngeal, pneumo- gastric and sympathetic, through the pharyngeal plexus, also the upper posterior nasal branches of Meckel's (spheno-palatine) ganglion. The otic ganglion lies on the outer side of the cartilaginous portion of the tube (pars cartilaginea tubae auditivae), and supplies the tensor palati muscle (m. tensor veli palatini). THE INTERNAL EAR OR LABYRINTH (AURIS INTERNA) The Internal Ear or Labyrinth is the essential part of the organ of hearing. It lies internal to the tympanum, within the petrous portion of the temporal bone, and consists of a series of osseous chambers, the Osseous Labyrinth, containing a fluid, the perilymph, in which lies a mem- branous reproduction of the chambers, the Membranous Labyrinth, which also contains a fluid, the endolymph. Within the membranous labyrinth are distributed the terminal filaments of the auditory nerve, which being suspended between two fluids, are not only protected from injury, but enabled to receive the most delicate vibrations communicated to the fluids surrounding them. The Internal Ear comprises the following-named structures: f Vestibule (4), the central cavity. Osseous Labyrinth { Semicircular Canals, behind the vestibule. [ Cochlea (8), in front of the vestibule. Utricle, a membranous sac, in the recessus ellipticus of the vestibule. I Membranous Semicircular Canals (ductus semicirculares), in the osseous canals. Membranous Labyrinth. \ _ . Saccule, a membranous sac, in the recessus sphaericus of the vestibule. Membranous Cochlea (ductus cochlearis), a spiral tube, enclosed in the osseous cochlea. Auditory Nerve (n. acusticus), the 8th cranial nerve, Portio Mollis of the yth pair. Organ of Corti (organon spirale), the terminal auditory apparatus, in the membranous cochlea (ductus cochlearis). THE EAR 305 Internal Auditory Meatus (meatus acusticus interims), by which the auditory nerve enters from the brain. The Vestibule (4) is the central common cavity of communication be- tween the osseous parts of the internal ear, and measures in vertical diam- eter about 3-15 inch, laterally about ^fo inch. It is situated internal to the tympanum, behind the cochlea (8), and in front of the semicircular canals (2), communi- cating in front with the scala vestibuli of the cochlea, and behind by five openings with the semicircular canals. It contains a fluid, the perilymph, also the utricle and saccule of the membranous labyrinth, and presents the fal- lowing points: Fenestra Vestibuli (fenestra ovalis), on i l s outer wall, closed by the base of the stapes and its annular ligament. Recessus Sphcericus (fovea hemisphaerica) (7), a small circular depression on the inner wall, for the saccule, medially, it presents a small area, macula cribrosa media, which is perforated by 12 to 15 minute orifices for filaments of the acoustic nerve. Crista Vestibuli, a vertical ridge on the inner wall behind the recessus sphaericus. It bifurcates below to enclose the Recessus Cochlearis, a small depression, perforated for the passage of about 8 filaments of the acoustic nerve. Aquceductus Vestibuli, opens behind the crista, ending on the posterior surface of the petrous portion of the temporal bone. It transmits a small vein, and contains the ductus endo-lymphaticus, a tubular pro- longation of the lining membrane of the vestibule, which ends in a cul-de-sac between the layers of the dura mater in the cranial cavity. Recessus Ellipticus or Fovea Semi-elli plica (6), a transverse oval de- pression on the roof for the utricle; behind it are the 5 orifices of the semicircular canals, and in front is the opening into the scala vestibuli of the cochlea. The Semicircular Canals (canales semicirculares ossei) are three C- shaped bony tubes, each about >^o inch in diameter, situated above and behind the vestibule, into which they open by 5 apertures. Each canal lies at a right angle with the other two. The external (lateral) canals of both ears are virtually in the same plane, while the superior canal of one ear is in a plane parallel to that of the posterior canal of the other ear 306 HUMAN ANATOMY (Crum Brown). The superior and posterior canals are each nearly an inch long, and are placed vertically; they join together behind in the crus commune, which opens into the vestibule. The external canal is about ^o inch long, placed horizontally, its arch being directed outward and back- ward. The canals contain the perilymph, and the membranous semicircu- lar canals. The Ampulla, is a flask-shaped dilatation of each canal at one extremity, having a diameter of about Ko inch. The Cochlea is a spiral canal situated in the eburnated (ivory-like) portion of the petrous bone, diametrically opposite to the internal auditory canal (meatus acusticus internus). The depth at which it lies from the cerebral surface of the bone varies, in different individuals, from ^4 to of an inch. The promontory in the tympanum is the only part of the cochlea that is exposed, elsewhere it is completely imbedded in solid bone. It is about iM inches long, tapering from Ho to J^o inch in diameter, coiled around a central conical axis for 2% turns. By removal of surrounding bone, in conformity with its interior, the cochlea can be made to resemble a snail-shell in appearance with its apex pointing forward and outward. Its first turn is separated from the carotid canal in front by a thin wall. Its central axis, the modiolus, is of conical shape, and is channeled by small canals for the passage of arteries and nerves, and by a central one, the^canalis centralis modioli. Its apex is the last coil of the cochlea, and is expanded into a funnel- shaped lamella, iheJHfrmdibidum. The Canalis Spiralis Modioli, or Spiral Canal, is the space between the modiolus and the outer wall of the cochlea. It makes 2 ; 3 4 turns ; from left to right in the right ear, from right to left in the left ear, or in other words, that of the right ear corresponds to a " right hand " screw; and terminates in the cupola, a cul-de-sac at the apex of the cochlea. It presents 3 openings, the fenestra cochlea (fenestra rotunda), communicating with the tympanum; the opening into the vestibule, and the orifice of the aquaeductus cochleae (see below). Lamina .Spiralis (6), is a thin, osseous plate, projecting from the modiolus half way across the spiral canal, and winding around the modiolus terminates near the apex in a hook-like process, the Jtajnidus^ Its deficiency in the last half turn of the cochlea forms the Helicotrema. a space in which the two scalae unite. It consists of two laminae, THE 'EAR 307 between which pass the filaments of the cochlear nerve. From its free edge the structures composing the membranous cochlea pass to their attachment on the opposite wall of the cavity. It partially divides the spiral canal into 2 passages, the scala vestibuli above and the scala tympani below. Aquceductus Cochlea, is a minute funnel-shaped canal which begins by a small orifice in the lower wall of the scala tympani near the promontory, and runs in the inner wall of the jugular fossa, ending in the small deep triangular depression on the posterior border of the basilar surface of the petrous portion of the temporal bone. It transmits a vein from the cochlea to the jugular vein, or to the inferior petrosal sinus, and forms a communication between the perilymph in the scala tympani and the subarachnoidean space of the brain. The Membranous Labyrinth (labyrinthus membranaceus) is situated within the osseous labyrinth, and consists of two membranous sacs, the Utricle (utriculus) (i) and Saccule (sacculus) (2), together with the Mem- branous Semicircular Canals (ductus FlG - IOI> semicirculares) (6), and the Membranous Cochlea (ductus cochlearis) (5). The utricle and saccule communicate with each other indirectly by a small canal contained in the aquaeductus vestibuli. The saccule communicates with the membranous cochlea by the canalis reuniens of Hensen (4), and the mem- Acastof^fUabyrmthasseen ^^ ^^^ canals Qpen into the utricle; so that the membranous labyrinth affords an uninterrupted channel for the endolymph which it contains. The walls consist of 3 layers, an outer fibrous coat, a middle one resembling the hyaloid membrane, and an inner layer, formed of polygonal, nucleated epithelial cells. In the walls of the utricle and saccule are contained 2 small gelatinoid bodies, the Macula Acusticce which contain flask-shaped Hair Cells and Otoliths (otoconia), minute crystals of calcium carbonate, held ta gether in a mesh of delicate fibrous tissue in which ramify many minute fibres of the acoustic nerve. The Utricle (utriculus) (i) is a flattened, oblong membranous sac, fastened to the inner wall of the vestibule in the fovea semi-elliptica (recessus ellipticus). It is filled with endolymph, nearly surrounded by perilymph, and communicates with the saccule through the small tube in 308 HUMAN ANATOMY the aquaeductus vestibuli. The membranous semicircular canals open into its cavity behind by 5 orifices. The Macula Acustica Utricularis, is a thickened spot in the wall where it is lodged in the fovea (recessus), receiving the utricular filaments of the acoustic nerve. Ductus Utriculosaccularis, is given off from the medial wall; it is joined by a similar duct coming from the saccule; together they form the Ductus Endolymphaticus which passes through the aquaeductus vestibuli. The Saccule (sacculus) (2) is the smaller of the two membranous sacs, about Hs inch in diameter, attached at one point to the utricle, and also to the fovea hemispherica (recessus sphaericus) of the vestibule, being else- where surrounded by perilymph, and containing endolymph. It com- municates with the utricle through the ductus endolymphaticus in the aquaeductus vestibuli, and also with the membranous cochlea by the Canalis Reuniens of Hens en (4), about ^5 inch long and K 20 inch in diameter,- connects the cavity of the saccule and the vestibular end of the membranous cochlea (ductus cochlearis) (3). Macida Acustica Saccularis, is a circular area, ^2 inch in diameter, on the wall of the saccule, where the saccular filaments of the acoustic nerve originate. FIG. 102. The Membranous Semicircular Canals (ductus semicirculares) have the same shape as the osseous ones in which they are contained but are Yz their diameter. They are fastened thereto by the convex curves, and are elsewhere surrounded by perilymph, except at the ampullary enlarge- THE EAR 309 ments, where they fill the osseous canals and present a thickened fiddle- shaped elevation projecting into the cavity and called the septum trans- versum, in which the nerves end. They are held in position by numerous fibrous bands, connecting them to the walls of the osseous canals. They constitute the Organ of Orientation and Equilibration. The Membranous Cochlea, also called the Ductus Cochlearis or Scala Media, is a spiral tube enclosed in the spiral canal of the osseous cochlea (16), lying along its outer wall, to which it is attached, being also attached to the lamina spiralis (10) on the opposite side of the cavity. It is formed by the membrana or lamina basilaris (8) below, the vestibular membrane of Reissner (18) above, and the periosteum of the cochlear wall on the outer side, its cross-section being of triangular form. It is filled with endolymph, and contains the organ of Corti (organon spirale) (n) overhung by the membrana tectoria (7). The Limbus Lamina Spiralis (10), is the soft structure of periosteum on the edge of the lamina spiralis, and lies in the membranous cochlea. It has two lips, an upper, the labium vestibulare, and a lower, the labium tympanicum, with a C-shaped concavity, the sulcus spiralis internus, between them. Vestibular Membrane of Reissner (18), extends from the edge of the lamina spiralis to the outer cochlear wall, separating the membranous cochlea from the scala vestibuli (2). Membrana or Lamina Basilaris (8), is the tympanic- wall of the mem- branous cochlea, extending from the labium tympanicum of the lamina spiralis to the outer cochlear wall, where its insertion is called the ligamentum spirale (5), or muscle of Todd and Bowman. On it rests the Spiral Organ of Corti (n), covered by the mem- brana tectoria. Membrana Tectoria (7), extends parallel to the membrana or lamina basilaris from the 'abium vestibulare, over the spiral organ of Corti, to be attached externally to the outer row of Deiters' cells (see below). Vas Spirale (9), a vessel in the vascular connective tissue of the mem- brana or lamina basilaris, below the spiral organ of Corti. Zona Arctuala, is the inner area, and the zona pectinata is the outer area, of the membrana or lamina basilaris. The Organ of Corti (organon spirale) (n),or Papilla Spiralis, is situated on the inner surface of the membrana or lamina basilaris (8), is overlapped by the free edge of the membrana tectoria (7), and appears as a papilla winding spirally throughout the length of the membranous cochlea. It is an arrangement of cells, some of which are rod-like in form, and others 3 10 HUMAN ANATOMY are epithelial hair-cells, the whole being supposed to be the essential organ of hearing. The Rods of Corti, are arranged in two rows, resting, by their pedestals, on the lamina basilaris, and uniting with each other by their heads, so as to form an arched tunnel, the tunnel of Corti, between them and the membrana basilaris all along the length of the cochlea. Number of rods in inner row about 6,000, in outer row 4,000. Average di- ameter of the rods, from Msooo to Hsooo inch. Head-plates, are attached to the heads of the inner rods, for the recep- tion of the rods of the opposite row. FIG. 103. Lamina Reticularis (i), a delicate perforated membrane which extends from the articulations of the rods outward to the external row of the outer hair-cells. Auditory Cells (2), are epithelial structures covering the inner surfaces of the walls and the floor of the membranous cochlea. Those which cover the inner rods by a single row number about 3,500, are nucleated, covered with tufts of cilia, and called the inner hair-cells. On the outer rods are 3 or 4 rows of similar cells, numbering about 12,000, and named the outer hair-cells. Between the latter are rows of sup- porting cells, called the cells of Deiters, and outside them are 5 or 6 rows of columnar cells, the cells of Hensen, beyond which are the cells of Claudius, covering the outer part of the zona pectinata of the membrana or lamina basilaris. The Auditory Nerve (n. acusticus), the 8th or Portio Mollis of the ;th pair, arises by two roots from the same groove in the medulla as does the facial nerve which is in front and separated from it by the pars intermedia, or glosso-palatine nerve (n. intermedius), the medial or vestibular root from the area acustica or trigonum acusticum in the floor of the 4th ventricle, the lateral or cochlear root from the accessory nucleus and the tuberculum acusticum, in the medulla, close to the restiform body. It emerges from the medulla at the lower border of the pons Varolii, in company with the facial nerve, from which it receives one or two filaments, both nerves THE EAR 311 passing into the internal auditory meatus, at the bottom of which the auditory divides into two branches, vestibular and cochlear. The Vestibular Nerve, has a ganglion, the vestibular ganglion of Scarpa, on it in the internal auditory meatus; it then divides into 3 branches, which pass through minute orifices in the bottom of the meatus, and entering the vestibule, are distributed to the utricle and the ampullae of the external and superior semicircular canals respectively. This nerve has nothing to do with hearing, it is purely a nerve of orientation and equilibration. Cochlear Nerve, is the true nerve of hearing, it gives off branches to the saccule and the ampulla of the posterior semicircular canal, and then divides at the base of the modiolus of the cochlea into numerous filaments (14), which pass through the little foramena in the tractus spiralis foramenosus at the bottom of the internal acoustic meatus, then between the lamellae of the lamina spiralis, and through the central canal of the modiolus, to the hair-cells of the spiral organ of Corti (Fig. 101). On it in the spiral canal of the modiolus is the Ganglion S pirate (13), consisting of bipolar nerve-cells, which are 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 spiral organ (see lateral lemniscus, page 199). The Internal Auditory Meatus (meatus acusticus internus) is a large orifice on the cerebellar surface of the petrous portion of the temporal bone, leading into a short canal, which runs outward for % inch, and is closed by a vertical plate, thefundus or lamina cribrosa, divided by a crest, the crista falciformis (crista transversa), into 4 depressions, which are perforated by foramina for the passage of the branches of the auditory nerve into the labyrinth. The Tractus Spiralis Foraminosus, is the anterior lower depression; has a number of foramina spirally arranged and opening into the central canal of the cochlea, transmitting the nerves to the cochlea. Area Cribrosa Media (area vestibularis inferior), just below the posterior part of the crest, transmits the nerves to the saccule. Foramen Singulare, behind the preceding area, for the nerve to the posterior semicircular canal. Area Cribrosa Superior (area vestibularis superior), above the crest posteriorly, for the filaments to the utricle and the superior and external semicircular canals. Opening of the Aquaductus Fallopii (area n. facialis) above and in front, for the passage of the facial nerve. HUMAN ANATOMY Vessels of the Internal Ear. The Veins accompany the arteries, and uniting at the base of the modiolus empty into the superior petrosal sinus or into the lateral sinus. The Arteries are the Internal Auditory, br. of the basilar (from the vertebral), accompanies the acoustic nerve into the internal auditory meatus, where it divides into vestibular and cochlear branches. Stylo-mastoid, br. of the posterior auricular (from the external carotid), sends some small branches to the cochlea. ORGANS OF DIGESTION (APPARATUS DIGESTORIUS) The Alimentary Canal is a musculo-membranous tube, about 30 feet in length, extending from the mouth to the anus, lined throughout with mucous membrane, furnished with several accessory organs, and perform- ing the functions of ingestion, mastication, insalivation, deglutition, digestion, assimilation, and egestion. Its subdivisions are named the Mouth, Pharynx, (Esophagus, Stomach, Small Intestine (duodenum, jejunum and ileum) and Large Intestine (caecum, colon and rectum). The first three lie above the diaphragm, the rest below it. The portion from the pharynx down is the "tubus digestorius." Accessory Organs of Digestion are the Teeth, Salivary glands (pa- rotid, sub-mandibular, sub-lingual), Liver, and Pancreas. THE MOUTH (CAVUM ORIS) The Mouth is an oval-shaped cavity, placed at the commencement of the alimentary canal, and consists of the vestibule, and the cavity proper. The vestibule (vestibulum oris) is a slit-like aperture between the lips and cheeks externally and the gums and teeth internally. It is partially interrupted in front in the mid-line by ihejrenula which attach the lips to the gums, the frenulum of the upper lip being the more developed of the two. The cavity proper (cavum oris proprium) extends from the alveolar arches and their teeth in front and laterally to the isthmus of the fauces behind, by which constricted aperture it communicates with the pharynx. Its roof is formed by the palate, its floor by the tongue and its mucous membrane reflected to the lower gum. The lips (labia oris) are the two fleshy folds, which surround the orifice (rima oris) of the mouth, the cheeks (buccae) forming its sides and being continuous with the lips in front; both are formed of skin externally, and mucous membrane internally; between which are muscle, fat, areolar- tissue, vessels, nerves and glands. The THE PALATE 313 mouth presents for examination the tongue (see page 272), the gums and teeth (described separately), the palate, fauces, tonsils, and openings of ducts from the salivary glands. Special anatomical features presented by the mouth are the Hamular Process of the Medial Pterygoid Lamina of the Sphenoid Bone, may be felt behind the last upper molar tooth; also the internal ptery- goid plate (medial pterygoid lamina), and part of the pterygoid fossa. Coronoid Process, of the lower jaw, at its anterior border. Posterior Palatine Artery, at the inner side of the last upper molar tooth, and in front of the hamular process. Pterygo-mandibular Ligament, is felt as a fold posteriorly to the last lower molar tooth. Lingual Branch of the $th, the gustatory nerve, passes over the inner side of the ramus of the lower jaw, close to the last lower molar tooth. Openings of Stenson's Ducts, from the parotid glands, in the vestibule, one on each cheek, opposite the 2nd upper molar tooth. Openings of Wharton's Ducts, from the submandibular or submaxillary glands, in the cavity proper, one on each side of the f raenum (frenu- lum linguae) of the tongue. Openings of the Ducts of Rivinus, from the sublingual glands, 8 to 20 on each side, open into the cavity proper, on either side of the fraenum (freiiulum linguae) of tbe tongue. THE PALATE (PALATUM) AND TONSILS (TONSILL.E "PALATINE) The Palate forms the roof of the mouth, and consists of the hard palate (palatum durum) in front, and the soft palate (palatum molle) behind. The Hard Palate (palatum durum) is formed by the palate process of the maxilla and the horizontal plate of the palate bone, is covered with mucous membrane, which is closely adherent to the periosteum, and presents along the median line, a linear ridge orjaphe, which terminates anteriorly in a papilla corresponding to the inferior opening of the anterior palatine fossa. The Soft Palate (palatum molle) is a movable fold suspended from the posterior border of the hard palate, and forming an incomplete septum between the mouth and the pharynx. It consists of a fold of mucous membrane, enclosing muscular fibres, an aponeurosis, adenoid tissue, vessels, nerves and mucous glands; and is formed by fibres of the following Muscles, 5 on each side, the levator palati, tensor veli palati, palato- glossus (m. glosso-palatinus) , palato-phafyngeus (m. pharyngo- palatinus), and the azygos uvulae (m. uvulae); the latter forming with its fellow the " 314 HUMAN ANATOMY Uvula, a conical-shaped, pendulous process, which hangs down from the middle of the free border of the soft palate. Glosso- palatine Arch or Anterior Pillar of the Fauces, arches downward and forward to the base of the tongue, and contains the glosso-palatine muscle. Pharyngo-palatine Arch or Posterior. Pillar of the Fauces, arches down- ward and backward to the sides of the pharynx, and contains the palato-pharyngei (m. pharyngo-palatinus) muscle. Isthmus Faucium, the space bounded by the glosso-palatine arches of both sides, the free border of the palate, and the base of the tongue. It communicates with the mouth anteriorly and with the pharynx posteriorly. The Tonsils (tonsillae palatinae) or A mygdalee, are two prominent bodies, situated one on each side, in the sinus tonsillaris between the anterior and posterior pillars (glosso-palatine and pharyngo-palatine arches) of the fauces, and nearly an inch in front of the internal carotid artery. Their inner surfaces show 12 to 15 orifices, leading into recesses, from which follicles branch out into the substance of the gland. The follicles are numerous, and are surrounded by a layer of closed capsules of adenoid tissue, and a plexus of lymphatic vessels communicating with the deep cervical glands. The Fossa Supra-tonsillaris, is a recess above the tonsil, and is covered by the plica semilunaris, a fold of mucous membrane. Arteries, as usually given, are the dorsalis linguae, from the lingual; the ascending palatine and tonsillar, from the facial (a. maxillaris externa); the ascending pharyngeal, from the external carotid; the descending palatine; from the internal maxillary; and a twig from the small meningeal. As a matter of fact, in 95 per cent, of all cases none of these arteries that surround the tonsillar fossa (sinus tonsillaris) and form a plexus around it, actually penetrate directly through the wall and capsule into the tonsil. The ascending palatine branch of the facial (external maxillary) and the^escendin^ palatine branch of the internal maxillary arteries form a plexiform anastomosis which is quite outside of the fossa (sinus tonsillaris) and well above and behind it. The True Tonsillar Artery is formed by this anastomosis, it passes downwards between the capsule and muscular aponeurosis for a distance of about % inch before penetrating the capsule to reach the tonsil (J. Leslie Davis). Veins, accompanying the true tonsillar artery is a vein which runs THE SALIVARY GLANDS 315 upwards to the palatine plexus, a smaller vein emerges from the tonsil in company with the other vein, then turns downwards and runs be- tween the capsule and the wall of the fossa (sinus tonsillaris) to reach the pharyngeal plexus (J. Leslie Davis). Nerves, are derived from the spheno-palatine ganglion, and from the glosso-pharyngeal. THE SALIVARY GLANDS (GLANDULE SALIVALES) The Salivary Glands, communicating with the mouth, are the Parotid, the Stibmandibular, and the Sublingual glands. They are compound, race- mose glands, consisting of numerous lobes, made up of smaller lobules connected together by dense areolar tissue, vessels and ducts. Each lobule consists of the ramifications of a duct, the branches terminating in dilated ends or alveoli, on which the capillaries are distributed, and which are enclosed by a reticulated basement membrane. The alveoli are lined by cells, which secrete a mucous secretion in the sublingual gland, or a serous fluid in the parotid gland; the submandibular producing both kinds. Mucous Glands are also found in the mouth, in the tongue, the tonsil, and the soft palate. The Parotid Gland (glandula parotis) (i) is the largest of the three salivary glands, and weighs from % oz. to i oz. Superficially, it lies upon the side of the face, below and in front of the external ear, and passes over the masseter muscle anteri- orly. Deeply, it lies on the tym- panic plate of the temporal bone behind the articulation of the lower jaw. The parotid is sur- rounded by a capsule which blends deeply with the back of the stylo- mandibular ligament. The super- ficial portion of this capsule is the parotid fascia (fascia parotideo- masseterica). The capsule is de- rived from the deep cervical fascia, it is strongly attached to the lower border of the zygoma, the acoustic meatus, anterior border of the sterno-mastoid muscle, stylo-mandibular ligament, and the bucco-pharyngeal fascia. It is tenaciously adherent to the gland itself. Passing through it are the following Structures, the external carotid artery and its terminal branches, the posterior auricular, temporal, and internal maxillary; the vein formed HUMAN ANATOMY by the union of the temporal and internal maxillary veins, the facial nerve and its branches, branches of the great auricular nerve, and the auriculo-temporal branch of the mandibular nerve. The internal carotid artery and the internal jugular vein lie close to its deep surface. Stenson's Duct (ductus parotideus) (2), is the duct of the parotid gland, and is about 2^ inches long. It begins by numerous branches from the anterior part of the gland, crosses the masseter muscle, pierces the buccinator, and opens on the inner surface of the cheek by a small orifice opposite the 2nd molar tooth of the upper jaw. Soda Parotidis, is a small, detached portion of the gland, which occasionally exists as a separate lobe, just beneath the zygomatic arch. Its duct empties into Stenson's duct, where the latter crosses the masseter muscle. Arteries, are derived from the external carotid. Veins, empty into tributaries of the external jugular. Lymphatics, terminate in the superficial and deep cervical glands. Nerves, are derived from the carotid plexus of the sympathetic, the facial, auriculo-temporal and great auricular nerves. % The Submandibular Gland (glandula submaxillaris) (3) lies below the jaw, in the anterior part of the submandibular triangle, and upon the mylo-hyoid, hyo-glossus, and stylo-glossus muscles, the facial artery (a. maxillaris externa) lying embedded in a groove in its upper, posterior border. Its duct Wharton's Duct (ductus submaxillaris) (4), is about 2 inches long, and opens on the summit of a papilla at the side of the fraenum of the tongue. Arteries, are branches of the facial (external maxillary) and the lingual; the veins following the course of the arteries. Nerves, are branches of the submandibular or submaxillary ganglion, and are derived through the ganglion from the chorda tympani, the lingual, and the sympathetic. The Sublingual Gland (glandula sublingualis) (5) is the smallest of the salivary glands, and is situated beneath the mucous lining of the floor of the mouth, at the side of the fraenum (frenulum linguae) of the tongue, and in contact with the inner surface of the lower jaw. Its ducts, the Ducts of Rivinus (ductus sublinguales minores), from 8 to 20 in num- ber; some join Wharton's duct (ductus submaxillaris), others open on the side of the frenulum linguae. THE TEETH 317 Duct of Bartholin, is a tube formed by one or more of the preceding ducts; it opens into Wharton's duct (ductus submaxillaris). Arteries, are derived from the sublingual and submental. Nerves, are branches from the lingual nerve. THE TEETH (DENTES) The Teeth are 32 organs of digestion, situated 16 in each jaw, where they are implanted within the alveoli, and are partly surrounded by the gums. In each half of each jaw there are Deciduous or Temporary Teeth (dentes dicidui) (5) 2 Incisors, i Canine, 2 Milk-molars. Permanent Teeth (dentes permanentes) (8) 2 Incisors, i Canine, 2 Premolar, 3 Molars. The Gums (gingivae) are composed of dense fibrous tissue, closely connected to the periosteum of the alveolar processes, and surrounding the necks of the teeth. They are covered with mucous membrane, presenting numerous fine papillae around the dental margin, and reflected into the alveoli, where it is continuous with the periosteal lining membrane. Characteristics of the Teeth. Each tooth consists of a crown (corona dentis) or body, projecting above the gum; root or fang (radix dentis), embedded within the alveolus; and the neck (collum dentis), the constricted portion between the crown and the fang. The roots are entirely con- cealed within their alveoli, and are covered by the pericementum (perios- teum alveolare), a reflection of the periosteum lining the alveoli, which becomes continuous with the fibrous structure of the gums. The pulp- cavity (cavum dentis) occupies the centre of the tooth, opening (foramen apicis) at the apex of the fang for the passage of vessels and nerves to the pulp (pulpa dentis) . Each class of teeth presents the following charac- teristics: HUMAN ANATOMY FIG. 107. Incisors, or Cutters (denies incisivi) (i), Crown chisel-shaped, beveled posteriorly. Fang single, long, thickest antero-posteriorly. Canines, or Tearers (dentes canini) (2), Crown thick and conical. Fang longest and thickest of all the teeth, forming a projection on the alveolar arch. The 2 upper canines are the "eye-teeth." Premolars, or Bicuspids (dentes prasmolares) (3), Crown has 2 cusps (tubercles). Fang single but grooved deeply, showing a marked tendency to bifurcate. Molars, or Grinders (dentes molares) (4), Crown large, low and cuboid in shape, has 4 cusps on upper molars, 5 on the lower ones. Fangs multiple, usually 3 on the first two upper molars, 2 on the first two lower ones. The third molar (dentes serotini) (5) is called the "wisdom-tooth," from its late eruption; its fangs are usually fused together into a grooved cone. Structure of the Teeth. A tooth consists of 3 structures, the dentine, or ivory (substantia eburnea) the proper dental substance, forming the larger portion; the enamel or adamant (sub- stantia adamantina), a layer covering the crown; and the cement (substantia ossea), a thin layer on the surface of the fang. A central chamber, the pulp-cavity (cavum dentis), occupies the in- terior, and contains the pulp (pulpa dentis), a soft, vascular, and sensitive organ, surrounded by a layer of cells the odonto-blasts or dentine- forming cells. The Pulp-cavity (cavum dentis), has a process ex- tending down each root, and opening at the apex by a minute orifice (foramen apicis) which transmits vessels and nerves to the pulp. Pulp (pulpa dentis), is made up of myxoma- tous tissue, and contains numerous blood- vessels and nerves, but no lymphatics. Dentine, or Ivory (substantia eburnea) (2), consists of tubules (can- aliculi dentales) surr< unded by the inter-tubular tissue or matrix, and opening into the pulp cavity (cavum dentis). It resembles compact bone in appearance and in composition, consisting of 28 parts animal matter and 72 earthy matter. THE TEETH 3 19 Dentinal Tubidi (canaliculi dentales), in the dentine, are delicate, wavy canals, diameter about M 5 o o of an inch, which branch outwardly and anastomose with each other, forming concentric shadings called Schreger's lines. They contain slender prolongations from the proc- esses of the cells of the pulp-tissue. Enamel (substantia adamantina) (3), covers the crown; consists of very dense tissue, containing but 3^ per cent, of animal matter. Its earthy matter, 96 ^ per cent., is composed chiefly of the phos- phate and carbonate of calcium. It is covered by a delicate epithelial cuticle, Nasmyth's Membrane (cuticula dentis), which when intact withstands the action of acids. Crusta Petrosa (substantia ossea) or Cement (i), the enamel of the fang; is a thin layer of true bony tissue, containing lacunae, canaliculi, and occasionally Haversian canals. Development of the Teeth. The teeth are evolved from the dermoid system, not from the skeleton. They are developed from two of the primi- tive layers of the embryo, the epiblasl producing the enamel (adamant) and the mesoblast giving rise to the dentine (ivory) pulp, cement (sub- stantia ossea), and pericementum (periosteum alveolare). About the 7th week of foetal life, two parallel ridges arise along the summit of each jaw, and a corresponding epithelial lamina sinks into the mesoblastic tissue beneath. This lamina sends off 10 cords, one for each tooth, from its inner edge; the cords expand into flask-like forms, and gradually assume the forms of the teeth, constituting their enamel-organs. They meet and enclose papilla, which arise from the mesoblastic tissue, forming a series of sacs, which with their contents are the dental follicles, having fibrous septa between them. In each follicle the vascular papilla has on its surface a layer of cells, named odontoblasts, from which the dentine (ivory) is developed by calcification, the remainder of the papilla forming the pulp of the tooth. The cement (adamant) is produced later by the tissue of the dental sac, in the same manner as bone is produced by periosteum. When calcification has advanced sufficiently, the pressure of the teeth causes the absorption of the gum above them, the teeth erupt, and the fibrous septa ossify, forming the alveoli, which embrace the necks of the teeth in a firm hold. The 10 permanent teeth, which replace the temporary ones in each jaw, are developed from special germs (enamel-organs) which arise from the lamina behind the germs for the temporary teeth, and recede into the tissue, to enclose mesoblastic papillae, and go through the same process as described for the temporary teeth. These germs appear about the i6th 320 HUMAN ANATOMY week. The 6 superadded permanent teeth arise from successive back- ward extensions of the lamina, projected from the back of that tor each preceding tooth, and thus forming a special dental germ for each added tooth. Eruption of the Teeth. The temporary teeth begin to appear through the gum at the 7th month after birth, the lower central incisors appearing first. Their eruption ends with the appearance of the second molars, about the age of two years. The lower teeth slightly antedate the upper. Their formula is as follows : Mo. Mo. Ca. In. In. In. In. Ca. Mo. Mo. f Upper. ,.i i i i i i i i i i = 10 1 j \. = 20 [ Lower. .. i i 1111111 i =ioJ 24 12 18 9 7 7 9 18 12 24 months. Of the permanent teeth, the first molars appear about the end of the 6th year, followed by the incisors about the 7th or 8th year, the bicuspids from the 9th to the loth year, the canines about the nth or i2th year, the second molars from the i2th to the i3th year, and the third molars from the i7th to the 2ist year. Those of the lower jaw are slightly in advance of the corresponding upper ones. Their formula is as follows: Wis.Mo.Mo.Pm.Pm.Ca.In.In.In.In.Ca.Pm.Pm.Mo.Mo.Wis. r Upper, i i i i i i iiiiii i i i 1=16] f 32 I Lower, i i i i i 1111111 i i i i = 16 J 19 12 6 10 9 ii 8 7 7 8 n 9 10 6 12 19 years. The greatest number of teeth at one time in the jaws is 48, including all the temporary and permanent teeth except the third molars, if none have been lost. This occurs between the 5th and 7th years of age. THE PHARYNX The Pharynx is a conical, musculo-membranous tube, about 4^ inches long, hung base up from the basilar process of the occipital bone, and extending to the lower border of the cricoid cartilage posteriorly, or the 5th cervical vertebra, where it becomes continuous with the oesophagus (5). It forms that part of the alimentary canal which lies behind the mouth, being incomplete in front where it opens into that cavity. From above downward it may be divided into the naso-pharynx (pars nasalis), above the level of the soft palate; the oral part (pars oralis), between THE PHARYNX 321 FIG. 108. the levels of the soft palate and the hyoid bone; and the laryngeal part (pars laryngea), below the latter level. It is connected with Anteriorly, the internal pterygoid plate, pterygo-mandibular ligament, lower jaw, base of the tongue, cornua of the hyoid bone, stylo-hyoid ligament, thyroid and cricoid cartilages of the larynx. Posteriorly, the longus colli and recti capitis anticus muscles, and by loose areolar tissue to the first 5 cervical vertebrae. Laterally, the styloid processes and their muscles, and is in contact with the common and internal carotid arte- ries, the internal jugular vein, the Qth, loth, 1 2th and sympathetic nerves, and above with a small part of the internal pterygoid muscles. Above, it is limited by the body of the sphenoid bone, and the basilar process of the occipital bone. Openings into the Pharynx, are 7 in number; the 2 posterior nares, (choanse), the 2 Eustachian tubes (tubae audi- tivae), the mouth, the larynx and the oesophagus. The Naso -pharynx (pars nasalis pharyn- gis) is that portion of the pharynx lying be- hind the nose and above the level of the soft palate. Its cavity, unlike the rest of the pharynx, always remains open. The Eustachian Tube (tuba auditiva), opens on its lateral wall, by a cleft-like orifice (ostium pharyngeum tubae auditivae), behind the inferior meatus of the nose, and just above the level of the floor of the nasal fossa. Pharyngeal Tonsil, a mass of lymphoid tissue, in the back wall of the pharynx, between the two Eustachian tubes (tubae auditivae). Bursa Pharyngea, an irregular depression of the mucous membrane in the jniddle line of the pharynx, above the pharyngeal tonsil. Cushion (torus tubarius) or Tubal Prominence, immediately behind 322 HUMAN ANATOMY the orifice of the Eustachian tube (ostium pharyngeum tubae auditivae), due to the pressure of the extremity of the cartilage of the tube. Fossa ofRosenmiiller, a deep recess, behind the cushion (torus tubarius). Structure of the Pharynx. The pharynx is composed of 3 coats, a mucous, a muscular and a fibrous, the latter lying between the other two, and called the pharyngeal aponeurosis (fascia pharyngo-basilaris) (4). The mucous coat is covered with ciliated columnar epithelium above the level of the floor of the nares below that level with squamous epithelium; and contains racemose mucous glands, especially around the orifices of the Eustachian tubes (ostia pharyngea tubarum auditivarum), also numerous crypts or recesses, surrounded by lymphoid tissue. The Pharyngeal Aponeurosis (fascia pharyngo-basilaris) (4), is thick above, where it is firmly attached to the basilar process of the occipital bone, and the petrous portion of the temporal bone. Pos- teriorly it presents a fibrous band or raphe in the median line, which gives attachment to the constrictor muscles. Muscles, are the inferior (i), middle (2), and superior (3) constrictors of the pharynx, the stylo-pharyngeus and the palato-pharyngeus (m. pharyngo-palatinus), which have been described on page 83. Vessels and Nerves. The Arteries of the pharynx are the superior thyroid and ascending pharyngeal, also the pterygo-palatine and descend- ing palatine branches of the internal maxillary; all from the external carotid. The nerves are branches from the Pharyngeal Plexus, formed by the pharyngeal branches of the vagus, glosso-pharyngeal, external br. of the superior laryngeal, and superior cervical ganglion of the sympathetic. ? *> !?*y THE (ESOPHAGUS OR GULLET The (Esophagus is a musculo-membranous tube, about 9 inches long, extending from the 5th cervical vertebra and the upper border of the cricoid cartilage of the larynx, through the cesophageal opening (hiatus oesophageus) in the diaphragm to the cardiac orifice (cardia ventriculi) of the stomach, where it terminates opposite the loth thoracic vertebra. In the neck it lies between the trachea and the vertebral column, resting in part on the longus colli muscle; then inclining to the left side it reaches the posterior mediastinum behind the left bronchus, and descends in that mediastinum, at first in front of the thoracic duct, lower down to its left. The (Esophagus is composed of 3 coats, as follows: Muscular Coat (tunica muscularis), has longitudinal fibres externally, circular fibres internally, which are continuous with the fibres of the THE ABDOMEN 323 stomach below, and with those of the inferior constrictor muscle above. Areolar Coat (tela submucosa), forms a loose connection between the other two coats, and contains the cesophageal vessels. Mucous Coat (tunica mucosa), in thick longitudinal folds, covered with a layer of stratified pavement epithelium. The oesophagus is loosely surrounded by an additional areolarcoat (tunica adventitia) which loosely connects it to the surrounding structures. (Esophageal Glands (glandulae cesophageas), are compound racemose glands, situated in the submucous tissue throughout the tube, but most numerous at the lower end, close to the cardiac orifice (cardia ventriculi) of the stomach. Arteries, are chiefly branches from the thoracic aorta. Veins, empty into the vena azygos minor. Nerves, are branches from the cesophageal plexus (plexus gullae), which is formed by branches from the vagus and the cervical sympathetic. THE ABDOMEN The Abdomen is a large, oval-shaped cavity, situated between the thorax above and the pelvis below, and bounded above, by the diaphragm; below, by the brim of the pelvis; posteriorly, by the vertebral column, and the fasciae covering the psoaeand quadrati lumborum muscles; anteriorly and laterally, by the transversalis fascia, the lower ribs and the venter of the ilium. It is invested internally by the Peritoneum, and it contains the Stomach. Pancreas. Abdominal Aorta. Intestines. Kidneys and Ureters. Inferior Vena Cava. Liver. Supra-renal Capsules. Receptaculum Chyli. Gall-bladder. Bladder (when distended). Thoracic Duct. Spleen. Uterus (during pregnancy). Solar Plexus, etc. Regions of the Abdomen (Regiones Abdominis). The abdomen is divided into 9 regions by two horizontal planes, one at the level of the cartilages of the loth ribs (sub-costal plane), another at the level of the highest points of the crests of the ilia, and 2 vertical or lateral planes from the cartilages of the 8th ribs to the centre of Poupart's inguinal liga- ment. The 9 regions thus formed are named the Right Hypochondriac. Epigastric. Left Hypochondriac. Right Lumbar. Umbilical. Left Lumbar. Right Inguinal or Iliac. Hypogastric. Left Inguinal or Iliac. 324 HUMAN ANATOMY Parts contained in each region are as follows: Right Hypochondriac Region, contains the right lobe of the liver, hepatic flexure of the colon, and part of the right kidney. Epigastric Region, contains the right two-thirds of the stomach, left lobe and part of the right lobe of the liver, gall-bladder, duodenum, cceliac axis, solar plexus, pancreas, parts of the aorta, inferior vena cava, vena azygos, and thoracic duct, the supra-renal capsules and parts of the kidneys. Left Hypochondriac Region, con- tains the fundus of the stomach, spleen, tail of the pancreas, splenic flexure of the colon, and part of the left kidney. Right Lumbar Region, contains the ascending colon, lower half of the right kidney, and part of the small intestine. Umbilical, contains the transverse colon, transverse duodenum, part of the great omentum and mesentery, and part of the small intestine. Left Lumbar Region, contains the descending colon, lower half of the left kidney, and part of the small intestine. Right Inguinal or Iliac Region, contains the right ureter, caecum, ap- pendix vermiformis, and the spermatic vessels of that side. Hypogastric Region, contains convolutions of the small intestine, the bladder in children and in adults when distended, and the uterus dur- ing pregnancy. Left Inguinal or Iliac Region, contains the left ureter and spermatic vessels, and the sigmoid flexure of the colon. Apertures in the Walls of the Abdomen are 8 in number, for the trans- mission of structures to or from it, as follows: the Opening for the Vena Cava (foramen venae cavae), in the diaphragm. Aortic Opening (hiatus aorticus), behind the diaphragm, for the aorta, vena azygos minor, thoracic duct, and occasionally the left sympathetic nerve (see page 94). (Esophageal Opening (hiatus cesophageus), in the diaphragm, for the cesophagus, and the pneumogastric nerves (see page 94). Umbilical Opening, in the anterior wall, transmitting the umbilical vessels in the foetus, but obliterated after birth, leaving a puckered depression, named the umbilicus. THE PERITONEUM 325 FIG. no. Internal Abdominal Ring (annulus inguinalis abdominis), on each side, half an inch above Poupart's ligament, for the passage of the sper- matic cord in the male, and the round ligament of the uterus in the female (see page 384). Femoral or Crural Ring (annulus femoralis), on each side, just below Poupart's inguinal ligament; for the passage of the femoral vessels. This opening is closed by the crural or femoral septum (see page 388). THE PERITONEUM The Peritoneum (peritonaeum) is a large serous membrane, which forms in the male a closed sac, the parietal layer (peritonaeum parietale) of which lines the abdominal walls, its visceral layer (peritonaeum vis- cerale) being reflected more or less completely over all the abdominal and pelvic viscera. Its free surface is covered with endothelium, and is smooth, moist, and shining. Its attached surface is con- nected to the viscera and the 11 parietes of the abdomen by the sub-peritoneal tela or areolar tissue (tela subserosa). In the female it is not a closed sac, the free extremities of the Fallopian tubes opening di- rectly into its cavity. The peritoneum is divided by a constricted portion of its tis- sue, at the foramen of Winslow (foramen epiploicum) (9), into 2 sacs, the Greater Sac (cavum peri- tonaei), extends over the anterior two-thirds of the liver (i), behind and above the stomach (3); below, behind, and in front of the great omentum, and below the meso-colon (12). Lesser Sac (bursa omentalis) or Cavity of the Great Omentum, extends behind and below the liver and stomach, above the meso-coion, 326 HUMAN ANATOMY within the great omentum, and behind the small or gastro-hepatic omentum (ligamentum hepatogastricum) (2). The Foramen of Winslow (foramen epiploicum) (9) is an opening which connects the two peritoneal sacs with each other. It is formed by an hour- glass constriction of the peritoneum caused by the hepatic artery in its curved passage forward and upward from the coeliac axis to the transverse fissure of the liver. It is situated behind the free border of the lesser or gastro-hepatic omentum (ligamentum hepatogastricum) (2), immedi- ately below the caudate lobe of the liver, and is bounded as follows: Anteriorly, the lesser or gastro-hepatic omentum (ligamentum hepato- gastricum) (2), containing the hepatic artery, portal vein, and the ductus communis choledochus. Posteriorly, the inferior vena cava, and the right crus of the diaphragm. Superiorly, the caudate lobe (processus caudatus) of the liver. Inferiorly, the duodenum, and the hepatic artery. The Omenta are peritoneal folds which pass from the external surface of the stomach (3) to various other organs, and are named the lesser or gastro-hepatic, the great or gastro-colic, and the gastro- splenic omentum. The "B.N.A." disregards this distinction and classes them with the true ligaments. Lesser or Gastro-hepatic Omenlum (ligamentum hepatogastricum) (2), consists of two layers of peritoneum, the anterior layer belonging to the greater sac (cavum peritonaei), the posterior to the lesser sac (bursa omentalis). It ascends from the lesser curvature of the stomach (3) to the transverse fissure of the liver (porta hepatis) (i) and the end of the resophagus. Its right margin is free and rounded, and contains between its layers the Hepatic Artery and Portal Vein. Ductus Communis Choledochus. Hepatic Plexus of Nerves. Lymphatics. Great or Gastro-colic Omentum (omentum majus), consists of 4 layers of peritoneum, the most anterior and superior of which belong to the greater sac (cavum peritonaei), the two internal to the lesser sac (bursa omentalis). The two anterior layers descend from the stomach and spleen over the small intestines (6), and then ascend as the posterior layers to enclose the transverse colon (4). Castro-splenic Omentum (ligamentum gastrolienale), connects the stomach with the spleen, and is continuous by its lower border with the great omentum. It contains the vasa brevia vessels (aa. gastricae breves). THE PERITONEUM 327 The Mesenteries (mesenteria) are folds of peritoneum connecting the various parts of the intestinal canal (except the duodenum) to the posterior abdominal wall. Each one contains the vessels of the part which it sup- ports. They are the Mesentery proper (mesenterium commune) (5), connects the convolu- tions of the jejunum (6) and ileum to the posterior abdominal wall, and contains between its layers the mesenteric vessels and nerves, the lacteals, and the mesenteric glands. Transverse Mesa-colon (mesocolon transversum) (12) connects the transverse colon to the posterior abdominal wall, and is formed by the two posterior layers of the great omentum (omentum ma jus). Sigmoid Meso-colon (mesocolon sigmoideum), connects the sigmoid flexure of the colon to the left iliac fossa. Meso-rectum, connects the upper part of the rectum (14) to the front of the sacrum, and contains the superior hemorrhoidal vessels. Ligaments formed by the Peritoneum are 1 7 folds of peritoneum which support certain organs, viz. Castro-splenic (lig. gastrolienale), from the stomach to the spleen. Hepatic (ligamenta hepatis), the longitudinal (lig. falciformehepatis), coronary (lig. coronarium hepatis), and 2 lateral ligaments of the liver (lig. triangulare dextrum et lig. triangulare sinistrum). Splenic (lig. lienorenale), the suspensory ligament of the spleen. Vesical, the false ligaments of the bladder, 5 in number. Uterine, 2 vesico-uterine, 2 recto-uterine, and 2 lateral or broad liga- ments of the uterus. Pouches formed by the Peritoneum, as it passes over the rectum (14), vagina, uterus (7) and bladder (8), are as follows: the Recto-vesical Pouch (excavatio rectovesicalis), in the male, between the rectum and the bladder. Recto-vaginal or Douglas' Pouch (excavatio rectouterina or cavum Douglasi), in the female, between the rectum and the posterior vaginal wall. Utero-vesical Pouch (excavatio vesicouterina), in the female, between the anterior wall of the uterus and the posterior wall of the bladder. Retro -peritoneal Fossae are recesses of the peritoneum, forming small pouches in certain parts of the abdominal cavity; any one of which may be the site of a retro-peritoneal hernia, and hernia of the vermiform appendix (processus vermiformis) frequently occurs into one of the pericaecal group. The lesser sac of the peritoneum may be regarded as a recess of 328 HUMAN ANATOMY peritoneum through the epiploic foramen of Winslow. The others are divided into 3 groups, as follows : Duodenal Fosses, 9 have been described, of which 3 are fairly constant, viz.; the inferior, and superior,. both on the left side of the ascending portion of the duodenum (n); and the duodeno-jejunal (recessus duodenojejunalis), bounded above by the pancreas (10), below by the left renal vein, to the right by the aorta (13), and to the left by the left kidney. Periccecal Fossa, are the ileo-colic (recessus ileocecalis anterior), in front of the caecum; the ileo-cacal (recessus ileocecalis posterior), behind the angle of junction of the ileum and caecum; and the sub- ccBcal (recessus ileocecalis inferior), immediately behind the caecum. Intersigmoid Fossa, lies behind the sigmoid meso-colon, and in front of the parietal peritoneum, on the external iliac vessels. It is con- stant in the foetus and during infancy, but disappears in a certain percentage of cases as age advances. ^Appendices Epiploica, are small pouches of peritoneum situated along the colon and upper third of the rectum, and filled with fat. They are chiefly found along the transverse colon. Viscera invested by Peritoneum are the following-named: Liver (i) (almost wholly). ' Transverse Colon (4). Stomach (3) (almost wholly). Sigmoid Flexure. Spleen. Rectum (upper ^). Duodenum (n) (first part). Ovaries. Small Intestine (6). Uterus (7). Those partially invested by peritoneum are the Duodenun (descending and Descending Colon. transverse portions). Rectum (14) (middle third). Ccecum. Vagina (upper part). Ascending Colon. Bladder (8) (posterior wall). Those having no peritoneal investment are the - Pancreas (10). Kidneys. Supra-renal Capsules (glandulae suprarenales) (see page 324). THE STOMACH (VENTRICULUS) The Stomach, the principal organ of digestion, is a dilated part of the alimentary canal, situated between the termination of the oesophagus and the beginning of the small intestine. It is somewhat pyriform in shape, of musculo-membranous structure, about 12 inches long by 4 inches in average diameter, held in position by the lesser omentum, and situated diagonally across the upper abdomen, in the epigastric and left hypochon- THE STOMACH 329 driac regions, above the transverse colon, below the liver and diaphragm It presents for examination a Fundus or Upper End (c), connected to the spleen by the gastro- splenic omentum (see under PERITONEUM). Pyloric or Lower End, lies in contact with the anterior wall of the ab- domen, the under surface of the liver, and the neck of the gall-bladder, its position being near the end of the cartilage of the 8th rib. Greater Curvature (curvatura ventriculi major) (d), is convex and is connected to the colon by the great omentum. Lesser Curvature (curvatura ventriculi minor) (i), is concave, and connected to the liver by the lesser omentum, and to the dia- phragm by the gastro- phrenic ligament. (Esophageal Orifice (cardia) (b), is situated between the fundus and the lesser curvature. It is funnel-shaped, and the highest part of the organ. Pyloric Orifice (pylorus) (k), opens into the duodenum (/), and is guarded by the circular muscular fibres of the pylorus, which are ag- gregated into a circular ring, projecting into the cavity, and with its covering fold of mucous membrane, forming the Pyloric valve. Structure of the Stomach. Its wall consists of 4 coats, the serous, muscular, areolar, and mucous; together with vessels and nerves. The Serous Coat (tunica serosa), is derived from the peritoneum, and covers the whole external surface, excepting the points where the gastro- splenic, great and lesser omenta are attached, and where the stomach is in contact with the diaphragm. Muscular Coat (tunica muscularis) (/), consists of longitudinal (stratum longitudinale) external, circular (stratum circulare) middle, and oblique (fibrae obliquae) internal. The longitudinal fibres radiate from the cardiac orifice, are continuous with the longitudinal fibres of the oesophagus and the small intestine, and are the most superficial. The circular fibres lie deeper, form a layer over the whole organ, and 330 HUMAN ANATOMY are aggregated into a circular ring at the pyloric end, which, with its lining mucous fold forms the pyloric valve. The oblique fibres lie deepest, and are arranged in two sets around the cardiac end. Areolar or Sub-mucous Coat (tela submucosa), consists of loose areolar tissue, connecting the muscular and mucous coats, and contains the gastric vessels. Mucous Coat (tunica mucosa) (g), lined with columnar non-ciliated epithelium, covered with polygonal alveoli, H 50 of an i ncn in diameter, containing the orifices of the gastric glands. When the stomach is contracted the mucous membrane lies in longitudinal folds or ruga (h), one of which aids in forming the valve at the pyloric orifice. Gastric Glands (glandular gastricae) are of 3 kinds, named pyloric, cardiac and fundus glands, all tubular in character, and formed by a deli- cate basement membrane, lined by epithelium. The Pyloric Glands, are most numerous at the pyloric end; each consists of 2 or 3 short, closed tubes, opening into a common duct, the orifice of which is situated at the bottom of an alveolus. They are lined with columnar epithelium throughout. Cardiac Glands, situated close to the cesophageal opening (cardia) of the stomach, are tubules lined part way with columnar epithelium, and filled with nucleated cells in their deepest parts. Fundus Glands, are most numerous at the fundus and resemble the pyloric glands. L"( cJc Vessels and Nerves. The Arteries of the stomach are the gastric (a. gastrica sinistra), the pyloric (a. gastrica dextra) and right gastro- epiploic branches of the hepatic, the left gastro-epiploic and vasa brevia from the splenic (a. lienalis). The Veins, terminate either in the splenic (v. lienalis) and superior mes- enteric veins, or directly in the portal vein. Nerves, are terminal branches of the right and left pneumogastrics (nn. vagi), and branches of the semilunar ganglia (ganglia coeliaca) of the sympathetic, forming the gastric plexus (see page 241). THE SMALL INTESTINE The Small Intestine (intestinum tenue) is a convoluted, tubular, digestive organ, about 20 feet in length, extending from the pylorus to the ileo-caecal valve, where it terminates in the large intestine. It is connected to the spinal column by the mesenteric portion of the perit- oneum, and divided into 3 parts, the THE SMALL INTESTINE 331 FIG. 112. Duodenum (d), about 10 inches long, the first part (pars superior) ascends for 2% inches to the under surface of the liver and the neck of the gall-bladder, the second part (pars descendens) descends for 3^ inches in front of the right kidney, and the third part (pars hori- zontalis inferior) passes transversely for 4 inches to the left, across the spinal column, to the left side of the second lumbar vertebra, where the superior mesenteric artery crosses its junction with the jejunum. The last inch of the duodenum is described as the fourth or ascending portion (pars ascendens). The duodenum has no mesentery, is partially covered with peritoneum, and surrounds the head of the pancreas. Into its descending portion open the ductus communis choledochus and the pancreatic duct. Jejunum (intestinum jejunum), about two-fifths of the rest of the small intestine, its coils lying around the umbilical region. It is named from the fact that it was formerly supposed to be found empty (jejunus} after death. Ileum (intestinum ileum) (i), com- prises the remainder of the small intestine; is named from its twisted course, lying below the umbilicus, and terminating in the right iliac fossa, at the ileo-cacal valve, or valve of Bauhin. Meeker s Diverticulum (diverticulum ilei), is a blind tube occasionally found connected with the ileum, about 3^ feet above its termination; it represents the remains of the vitelline duct of early foetal life. Structure of the Small Intestine, is arranged in 4 coats, like that of the stomach, a serous, muscular, areolar, and mucous coat. The Serous Coat (tunica serosa), is derived from the peritoneum, which partially invests the duodenum, and completely invests the jejunum 332 HUMAN ANATOMY and ileum, except for a small space along their mesenteric border, where the vessels and nerves pass in. Muscular Coat (tunica muscularis), consists of external longitudinal (stratum longitudinale) and internal circular (stratum circulare) fibres, the former being thinly distributed along the bowel, the latter forming a thick layer, but not making complete rings. Areolar Coat (tela submucosa), contains the vessels of the intestine, and connects the muscular and mucous coats together. Mucous Membrane (tunica mucosa), is covered with columnar non- ciliated epithelium, and thrown into crescentic transverse folds, the valvulce conniventes (plicae circulares), or valves of Kirkring. It pre- sents also numerous vascular projections or Villi (villi intestinales), simple follicles, and three kinds of glands (all described below). Villi (villi intestinales) (/) are minute, vascular processes, which project from the mucous membrane of the small intestine throughout its whole extent, giving to its surface a velvety appear- ance. They are most numerous in the duode- num and jejunum, and altogether number about 4 millions for the whole length of the intestine. Each villus consists of a lacteal vessel, a plexus of capillary blood-vessels, epithelium, basement membrane, and mus- cular tissue, supported and held together by retiform lymphoid tissue. The Lacteal Vessel, is situated in the axis of the villus, and commences by dilated extrem- ities near its summit. Blood-vessels, form a plexus between the lacteal and the basement membrane, enclosing the cells of the villus in their interstices. Basement Membrane, surrounds the preceding, and is made up of a stratum of endothelial cells, upon which is a layer of columnar epithelium. Muscular Tissue, consists of longitudinal fibres prolonged into the vil- lus from the muscular tissue of the mucosa. Simple Follicles, or Crypts of Lieberkiihn (glandulae intestinales), are minute, tubular depressions of the mucous membrane, opening be- tween the villi, their orifices appearing as minute dots on the surface of the mucous membrane. Glands of the Small Intestine. The mucous membrane of the small intestine contains the following glands: THE LARGE INTESTINES 333 Duodenal or Brunner's Glands (glandulae duodenales), are small, com- pound glands, found only in the duodenum and the first part of the jejunum, being most numerous near the pylorus. In structure they are identical with the racemose glands of the mouth. Solitary Glands (noduli lymphatici solitarii), are lymphoid organs, situated throughout the intestine, though most numerous at the lower portion of the ileum. They are agminated into some 20 or 30 oval patches, named Peyer's Patches or Glands (noduli lymphatici aggregati), on the sur- face opposite to the mesenteric attachments, some of which are as much as 4 inches in length. They are most numerous and largest in the ileum, are few and small in the jejunum, and are occasionally seen in the duodenum. Vessels and Nerves. The Arteries of the jejunum and ileum are branches of the superior mesenteric artery, forming an intricate plexus in the areolar tissue, which gives off minute vessels to the glands and villi. The duodenum is supplied by the pyloric (a. gastrica dextra) and pan- creatico-duodenal branches of the hepatic, and the inferior pancreatico- duodenal from the superior mesenteric. The Veins, accompany the arteries and have a similar course and arrange- ment. Lymphatics, are in two sets, one for the mucous membrane and one for the muscular coat. Nerves, of the duodenum are derived from the solar plexus (plexus cceliacus); those of the rest of the intestine from the sympathetic plexuses around the superior mesenteric artery. THE LARGE INTESTINE (INTESTINUM CRASSUM) The Large Intestine (intestinum crassum) extends from the termination of the ileum to the anus. It is about five feet long, of large calibre, and consists of the same coats as the small intestine, the mucous being smooth and without villi, the muscular having its longitudinal fibres collected into 3 narrow bands (taeniae coli) producing a sacculation (pouching) of its wall. In its course it describes an arch around the convolutions of the small intestine, and is divided into 3 portions, the Caecum, the Colon, and the Rectum. The Caecum (intestinum caecum) is a large blind pouch, about 2% inches long and 3 inches broad, situated in the right iliac fossa, immediately behind the abdominal wall, above the outer half of Poupart's ligament (liga- mentum inguinale), and below the ileo-caecal valve, which opens into it. 334 HUMAN ANATOMY It lies free in the abdominal cavity, its closed end downward, its open end upward and continuous with the commencement of the colon. It is usu- ally enveloped entirely by peritoneum, and presents for examination the Vermiform Appendix (processus vermiformis), a narrow, worm-like, blind tube, averaging 3 inches in length, directed upward behind the caecum, or to the left behind the ileum, or downward and inward into the true pelvis. Its canal communicates with the caecum by an orifice situated below and behind the ileo-caecal opening. Sometimes the orifice of the vermiform process is partially guarded by a crescentic fold of mucous membrane (valvula processus vermiformis) which is produced on its upper border. Its proximal % is retained in position by a triangular mesentery, its distal ^quamous epithelial cells, on a delicate supporting membrane, closely surrounding the convolutions of the glomerulus and dipping in between them. 362 HUMAN ANATOMY The Tubuli Renales, or Uriniferous Tubules, begin at the capsule of Bowman in the Malpighian bodies, and open into the sinus of the kidney by orifices on the surface of the papillae. During their course they leave the cortical portion, enter the medullary portion, return to the cortical and again to the medullary, in which they continue to their termination. In their course they become first convoluted, then spiral, then looped, again spiral and convoluted, curved and finally straight; and have received the following names: Proximal Convoluted Tube, the first portion, below the neck at Bow- man's capsule, in the cortical zone. Epithelium lining the tube is polyhedral and of striated appearance. Spiral Tube of Schachowa, in the cortical zone. Epithelium polyhedral and striated. Henle's Loop, in the medullary zone, consists of a descending limb, a loop, and an ascending limb, the latter becoming spiral- as it ascends into the cortical zone. Epithelium flat in the descending limb, poly- hedral and striated in the ascending one. Irregular Tubule, in the cortical zone. Epithelium angular and stri- ated. Distal Convoluted Tubule, in the cortical zone. Epithelium polyhedral. Curved Tube, in the cortical zone. Epithelium varied, angular, spindle-shaped, polyhedral. Straight or Collecting Tube, partly in the cortical zone, descends through the medullary portion and joins with others, forming the pyramids of Fcrrein (apices outward) in the cortical zone, and the pyramids of Malpighi (apices inward) in the medullary substance. Epithelium more or less columnar. Connective Tissue or Stroma, binds the tubules firmly together. Arteries of the Kidney arise from the renal artery, a large branch of the abdominal aorta. It divides into 4 or 5 branches, which enter the kidney at the hilum (hilus renis), giving off small branches to the supra- renal capsules, the ureter, etc. These again divide and end in the Arteries Pro price Renales, the renal arteries proper, which enter the kidney substance in the columns of Bertin (see page 360), form arterial arches over the bases of the pyramids, and divide into ascending and descending branches. The Ascending or Interlobular Branches, pass to the capsule and end in the capillary network of that part of the cortex, giving off in their course the afferent vessels to the Malpighian tufts (see page 360). Descending or Arteriolce Reclce, supply the medullary pyramids and end at their apices in the venous plexuses there situated. ' THE URETERS 363 Veins of the Kidney arise from 3 sources, the stellate veins beneath t he i -upside of the organ, the venous radicles in the Malpighian tufts, and the venous plexuses at the apices of the pyramids of Malpighi. Those from the stellate plexuses on the surface of the kidney join together, form- ing the Interlobular Veins, which pass inward between the pyramids of Ferrein, receive branches from the plexuses on the convoluted urinif erous tubes, and join with the vence recta from the apices of the pyramids of Mal- pighi, to form the Vence Propice Renales, the renal veins proper, accompany the arteries of the same name, receive the efferent vessels from the Malpighian bodies adjacent, and join with corresponding veins in the sinus to form the Renal Vein, emerges at the hilum and opens into the Jnferior vena cava; the left vein being longer than the right, having to cross in front of the abdominal aorta. Nerves of the Kidney are derived from the renal plexus, which is formed by branches from the solar plexus (plexus cceliacum), the aortic plexus, the semilunar ganglion, and the lessei and smallest splanchnic nerves. They have small ganglia upon them, and communicate with the spermatic plexus. Lymphatics consist of a superficial and a deep set, and terminate in the lumbar glands. THE URETERS The Ureter, the excretory duct of the kidney, is a musculo-membranous tube, which conducts the urine from the kidney to the bladder. It com- mences within the sinus of the kidney by 7 to 13 short tubes or calices, which encircle the apices of the pyramids of Malpighi, and converge into 2 or 3 tubular divisions or infundibula, these by their junction forming the pelvis or upper dilated extremity of the duct. The Ureter Proper, begins at the lower end of its pelvis, is about 16 inches long, and of the diameter of a small goose-quill. It descends, through the lumbar region of the abdomen and the pelvic cavity, to the base of the bladder, and opens into the cavity of that organ about 2 inches from its fellow. Course of the Ureter. In its course the ureter passes obliquely down- ward and inward through the lumbar region, and downward, inward and forward through the pelvic cavity, enters the posterior false ligament of the bladder, passes obliquely between the muscular and mucous coats of 364 HUMAN ANATOMY that organ for nearly an inch, and ends by a constricted orifice at one of the posterior angles of the trigone at the base of the bladder. Relations of the Ureter. The junction of the renal pelvis and the ureter proper is opposite the spinous process of the first lumbar vertebra, about 2 inches from the middle line of the back. The ureter lies upon the psoas muscle and behind the peritoneum; behind the ileum on the right side and the sigmoid flexure of the colon on the left side. It crosses the common or the external iliac artery; and is crossed by the spermatic vessels, and the branches of the mesenteric arteries, also by the vas deferens in the male. The right ureter lies close to the outer side of the inferior vena cava. In the female the ureters pass along the sides of the neck of the uterus and the upper part of the vagina, and beneath the root of the broad ligament. Structure of the Ureter. It is composed of 3 coats, fibrous, muscular, and mucous. The fibrous coat (tunica adventitia) is continuous with the capsule of the kidney and with the fibrous structure of the bladder. The Muscular Coat (tunica muscularis), consists of longitudinal fibres ex- ternally (stratum externum), and circular fibres internally (stratum medium). A third layer (stratum internum), consisting of longi- tudinal fibres, is found internal to the circular layer, in the neighbor- hood of the bladder. Mucous Coat, is prolonged over the papillae of the kidney, and is con- tinuous with the mucous lining of the bladder. Its epithelium re- sembles that of the bladder, and is known as' 'transitional epithelium, consisting of 3 layers of cells, the innermost of which are quadrilateral in shape. Vessels and Nerves. The Arteries of the ureter are branches from the renal, spermatic, internal iliac, and inferior vesical. The Nerves are de- rived from the inferior mesenteric, spermatic, and pelvic plexuses. THE SUPRA-RENAL GLANDS OR CAPSULES (GLANDULE SUPRARENALES) The Supra-renal Glands are properly classed with the ductless glands of. the chromaphiL^and cortical systems (see page 344). They are two small, yellowish bodies, situated one above each kidney, behind the perit- oneum, and in the posterior portion of the abdomen. They vary in size in different individuals, but are usually i^ inches long and wide, and from 2 to 3 lines in thickness. Each capsule has a small furrow, the hilum, on its anterior surface, in which the vessels enter the organ, and in structure consists of a THE BLADDER 365 Fibrous Capsule, which is very thin, closely adherent, and sends numer- ous septa inward. Cortical Substance, composed of columnar masses of polyhedral cells, held together in layers by a fibrous stroma. Medullary Substance, is darker than the cortical portion, and pulpy. It consists of granular cells, supported by a delicate stroma, and believed by some anatomists to be prolonged into the nerve fibres of a very intricate plexus. Relations of the Supra-renal Glands. Their surface is surrounded by ireolar tissue containing much fat; their bases rest on the upper front parts of the kidneys, theiVgpsterior surfaces on the crura of the diaphragm, about the level of the loth thoracic vertebra. The A nterior Surface, of the right gland is covered by the liver; that of the Ic-ft one by the spleen and pancreas. Superior Surface, of each is in relation internally with the great splanch- nic nerve and semilunar ganglion. Vessels and Nerves. The Arteries are the Supra-renal branches of the aorta, renal, and phrenic arteries, forming a dense capillary plexus in the cortical portion of the organ. Veins, of each open into a single trunk, the Supra-renal Vein, which on the right side of the body empties into the inferior vena cava, on the left side into the left renal vein. Lymphatics, open into the lumbar glands. Nerves, are derived from the solar (cceliac) and renal plexuses, with some filaments from the phrenic and vagus nerves, forming a compli- cated network in the medullary substance of the organ, and having numerous small ganglia developed upon them. THE BLADDER (VESICA URINARIA) The Bladder, the reservoir for the urine, is a musculo-membranous sac, situated in the anterior portion of the pelvis, behind the. pubes, and in front of the rectum in the male, in front of the cervix uteri and Vagina in the female. When empty and contracted, or when slightly distended, it is contained in the pelvic cavity; when greatly distended it is ovoid in shape, and rises into the abdominal cavity, often extending nearly as high as the umbilicus. When moderately distended it measures about 5 by 3 inches, and holds about a pint. The Summit, is connected to the umbilicus by the urachus (ligamentum umbilicale medium) and the obliterated hypogastric arteries (liga- 366 HUMAN ANATOMY FIG. 127. menta umbilicales laterales) of the foetus, forming three fibrous cords, the Superior Ligament of the bladder. Superior or Abdominal Surface, is free, and is covered by peritoneum. Anterior or Pubic Surface, is partly covered by peritoneum above, and is in relation below with the internal obturator muscles, the recto- vesical fascia, and the anterior true ligaments of the bladder. Posterior Surface, is covered by peritoneum, and is in relation with the rectum in the male, with the uterus and upper part of the vagina in the female. Lateral Surfaces, are partly covered by peritoneum behind and above; each is crossed obliquely by the obliterated hypogastric artery and the vas deferens (c), the first passing from below forward, the latter from below backward. Fundus or Base, is partly covered by peritoneum, and rests on the second portion of the rectum in the male, on the lower part of the cervix uteri and adherent to the anterior wall of the vagina in the female. Cervix or Neck, is constricted and contin- uous with the urethra (f). It is sur- rounded in the male by the prostate gland (h), and is directed downward and forward. Ligaments of the Bladder are 10 in num- ber, of which 5 are true ligaments, and 5 formed by folds of peritoneum. The true ligaments are the Anterior or Pubo-prostatic, 2, are formed by the recto-vesical fascia, and extend from the neck of the bladder, over the prostate gland, to the back of the pubic bone. Lateral, 2, also formed by the recto-vesical fascia, are attached to the sides of the base of the bladder, and the prostate gland. Urachus, the superior ligament (ligamentum umbilicale medium), connects the summit of the bladder with the umbilicus. It is the obliterated remains of a canal, which in the embryo connects the bladder with the allantois and is situated between the two obliter- ated hypogastric arteries (ligamenta umbilicales laterales). False Ligaments, folds of peritoneum, are the Posterior False Ligaments (plicae vesico-uterinae) female, (plicae recto- vesicalis) male, 2, pass from the postero-lateral parts of the bladder. are false ligaments, being THE BLADDER 367 to the sides of the rectum in the male, to the sides of the uterus in the female. Lateral False Ligaments (plicae umbilical es laterales), 2, from the iliac fossae and lateral walls of the pelvis to the sides of the bladder. Superior, or Suspensory Ligament (plica umbilicalis media), from the summit of the bladder to the umbilicus, being peritoneum carried off from the bladder by the urachus and the obliterated hypogastric arteries. Interior of the Bladder is lined by mucous membrane, which forms folds or ruga when the viscus is empty, being loosely connected to the muscular coat, except at the trigone and the uvula, where it is closely ad- herent. The floor of the bladder presents the Trigonum Vesica, or Vesical Trigone (i, Fig. 127), a pale-colored, tri- angular space, extending from the urethral opening in front to a line connecting the orifices of the ureters behind; and characterized by its smooth surface and the intimate adhesion between its mucous and muscular coats. Uvula Vesicce (3, Fig. 127), is a small elevation of mucous membrane projecting from the floor of the bladder into the urethral orifice. It is said to be lifted by the anterior fibres of the levator ani muscle. Orifices of the Ureters (2, Fig. 127), about 2 inches apart, at the base of the trigone, and i ^ inches from the urethral opening. Structure of the Bladder. The bladder has 4 coats, serous or perit- oneal, muscular, sub-mucous, and mucous. The peritoneal coat is a partial one, investing only the superior and posterior surfaces, and the upper portion of the lateral surfaces. The Muscular Coat, consists of unstriped muscular fibres, arranged in 3 layers; an external layer, chiefly longitudinal, the so-called detrusor urines muscle; a middle layer, mostly circular, and forming a sphincter vesicfg around the neck; and an internal layer, chiefly longitudinal. Muscles of the Ureters, are two bands of oblique fibres, extending from behind the orifices of the ureters to the middle lobe of the prostate gland. Sub-mucous Coat, is a layer of areolar tissue, connecting the muscular with the mucous coat. Mucous Coat, is thin, smooth, of a pale rose color, and is continuous with the lining membrane of the ureters and the urethra. Its epithe- lium is of the transitional variety, consisting of an inner layer of poly- hedral, flattened, nucleated cells; beneath which are two layers of club-shaped and spindle-shaped cells, wedged together. It contains no mucous glands. 368 HUMAN ANATOMY Vessels and Nerves. The Arteries of the bladder are the superior middle, and inferior Vesical in the male, with additional branches from the uterine and vaginal in the female; all from the anterior trunk of the internal iliac. The Veins, form a plexus around the neck, sides, and base of the bladder, and terminate in the internal iliac vein. Lymphatics, terminate in the internal iliac glands. Nerves, are derived from the pelvic plexus to the upper part of the organ, from the 3d and 4th sacral nerves to its base and neck. THE MALE URETHRA The Urethra is the urinary canal from the neck of the bladder to the meat us urinarius; in the male it is chiefly within the penis, is from 8 to 9 inches in length, and is divided into three parts, the pr astatic, membranous, and spongy portions of the urethra. The Prostatic Portion (pars prostatica) of the Urethra is that part of the canal which pierces the prostate gland (4), is about i finches in length, of spindle shape, and the widest and most dilatable part of the urethra. Its floor presents the Verumontanum, or Caput Gallinaginis (colliculus seminalis) (6), an elevation of the mucous membrane (crista urethralis) and its adjacent tissue, Y inch long, and supposed to contain muscular and erectile tissue. Prostatic Sinus (7), one on each side of the verumontanum, containing the orifices of the prostatic ducts. Sinus Pocularis, or Uterus Masculinus (utriculus prostaticus) (5), is a small cul-de-sac situated at the front part of the verumontanum. It extends for ^ inch upward and backward into the prostate gland beneath its middle lobe. Orifices of the Ejaculatory Ducts (8), open on the margins of the sinus pocularis. The Membranous Portion (pars membranacea) (9) is % inch long above, and Yz inch along its floor, being that part of the canal lying between the superior and inferior layers of the triangular ligament of the perinaeum. Its walls are very thin, and almost destitute of erectile tissue. It is surrounded by the deep transversus perinei or compressor urethras muscle, and except the orifice, is the narrowest part of the urethral canal. On its sides are the Ducts of Cowper's Bulbo-urethral Glands (n), on their way to open into the bulb of the urethra. THE URETHRA 369 FIG. 128. The Cavernous or Spongy Portion (pars cavernosa) (16) is about 6 inches long, and has two dilatations, one at each end, named respectively the Bulb and the Fossa Navicularis. The Bulb' of the Urethra (13), is the upper end of the cavernous portion, projects backward for Y inch, and contains the orifices (15) of the ducts of the bulbo-urethral or Cowper's glands. Fossa Navicularis, is the lower dilatation of the urethra, and is situated within the glans penis. Lacuna Magna (lacuna ure- thralis of Morgagni), the largest of several orifices of mucous follicles, situated on the roof of the fossa navicu- laris. Glands of Littre (glandulae ure- thrales), are numerous mu- cous glands and follicles, opening into the urethral canal, their orifices being directed forwards. Meatus Urinarius, the exter- nal orifice; is the most con- tracted portion of the ure- thra, and presents a vertical slit, about 3 lines long, bounded laterally by two small labia. Structure of the Urethra. It is composed of a continuous mucous membrane, continuous with the mucous lining of the bladder, ureters, and kidneys, and pro- longed into the ducts opening into the urethra. The mucous membrane is supported by a submucous tissue, which connects it with the various structures through which it passes. The Submucous Tissue, consists of a vascular erectile layer, outside which is a circular layer of unstriped muscular fibres. Voluntary Muscles of the Urethra, are the deep transversus perinei or 24 . 37O HUMAN ANATOMY compressor urethrae and the bulbo-cavernosus or accelerator urinae, described on page 98. Epithelium, is of the columnar variety, except near the meatus where it is squamous. THE FEMALE URETHRA The Urethra in the female is only about i ^ inches long, imbedded in the anterior wall of the vagina, perforating the triangular ligament, and sur- rounded by fibres of the deep transversus perinei or compressor urethras muscle. Its diameter is about % inch, but it is capable of considerable dilatation, being surrounded by softer structures than are those around the male urethra. The Meatus Urinarius, is situated directly in front of the vaginal opening and about an inch behind the glans clitoridis. ORGANS OF GENERATION THE MALE ORGANS OF GENERATION THE URETHRAL GLANDS The Prostate Gland (prostata) is a musculo-glandular organ, which surrounds the neck of the male bladder and the beginning of the male urethra. It is situated in the pelvic cavity, behind the lower part of the symphysis pubis, and above the deep layer of the triangular ligament, its posterior surface resting on the rectum. It is perforated by the urethra and the common seminal ducts, but its own ducts open into the prostatic portion of the urethra. It measures about i% inches by i)^ inches by i inch, weighs about % oz., resembles a horse-chestnut in size and shape, and consists of three lobes, two being lateral and of equal size, the third or middle lobe being a small prominence situated in the notch between the lateral lobes. Its Position, is maintained by the anterior or pubo-prostatic ligaments of the bladder, the deep layer of the triangular ligament, and the anterior portions of the levator ani muscles. Structure, is glandular substance arranged in follicular pouches, and dense muscular tissue, the whole being invested by a firm fibrous capsule, which gives off thin trabeculae into the substance of the gland. Ducts, are 1 2 to 20 in number, lined by columnar epithelium, and open on the floor of the prostatic portion of the urethra. Arteries, are derived from the internal pudic, vesical and haemorrhoidai arteries. THE PENIS 371 Veins, terminate in the internal iliac vein. Nerves, are branches from the pelvic or hypo-gastric plexus. Cowper's Glands (glandulae bulbo-urethrales) are two small, rounded bodies, about the size of peas, situated between the two layers of the triangular ligament, one on each side of the membranous portion of the urethra, close above the bulb, and enclosed by the transverse fibres of the compressor urethrae muscle. The Excretory Duct, of each gland opens by a minute orifice on the floor of the bulbous part of the cavernous portion of the urethra, after tra- versing the wall of the urethra for about i inch, beneath its mucous coat. THE PENIS The Penis is composed of a mass of erectile tissue enclosed in three cylindrical compartments, each surrounded by a fibrous sheath which is prolonged inward, forming numerous bands or trabeculae, which divide the compartments into a number of spaces. The compartments are the two corpora cavernosa and the corpus spongiosum (corpus 5 cavernosum urethrae) (6), the latter lying between and beneath the former, like the ramrod of a double-barreled gun. The Erectile Tissue, is lodged in the interspaces between the trabeculae of the fibrous structure, and consists of an intricate venous plexus, supplied by afferent arteries and emptied by efferent veins. The Corpora Cavernosa lie side by side, forming the upper and lateral parts of the penis. They are joined together along their anterior three- fourths, their posterior one-fourth forming the Crura, which arise from the tuberosities of the ischia and their rami, and meet beneath the sym- physis pubis, forming two grooves, one above for the dorsal vessels (i), and nerves (3), the in- ferior one for the corpus spongiosum (6). Suspensory Ligament (lig. suspensorium penis), a fibrous membrane which connects the root of the organ to the symphysis pubis. Septum Pectiniforme (5), is the front portion of the fibrous septum between the corpora cavernosa. This septum extends but two-thirds along the penis, and is wanting for its anterior third. The Corpus Spongiosum (corpus cavernosum urethras) (6) is an erectile tube lying in the inferior groove between the two corpora cavernosa, having within it the urethra, and expanded at both ends to form the glans 372 HUMAN ANATOMY penis and the bulb. It is composed of trabecular (band-like) structure, derived from a fibrous sheath, and containing erectile tissue. The Bulb of the Corpus Spongiosum (bulbus urethras), receives the urethra and is surrounded by the (bulbo-cavernosus) or accelerator urinas muscle. Glans Penis, is the external expansion of the corpus spongiosum (corpus cavernosum urethras) and covers by its base the ends of the two corpora cavernosa. Its base presents a rounded border, called the corona glandis, behind which is a deep sulcus, the cervix (collum glandis). Glands of Tyson, small lenticular sebaceous glands opening on the corona and cervix of the glans, and secreting an odorous sebaceous matter, the smegma. Meatus Urinarius, the external orifice of the urethra, is situated at the summit of the glans penis. Prepuce (praeputium), a prolongation of the integument of the penis, covering or partly covering the glans penis. Franum Pmputii (fraenulum praeputii), a fold of mucous membrane lying along the raphe of the glans penis, and connecting the prepuce with the glans. Vessels and Nerves. The Arteries are branches of the internal pudic, named as follows: the artery of the bulb, to the bulb of the corpus spongio- sum; the arteries of the corpora cavernosa, to that structure; and the dorsal artery of the penis, to the integument and fibrous sheath of the corpora cavernosa, the glans and prepuce. The Helicine Arteries, are vine-like branches, which project into the cavern- ous spaces, and are most abundant in the back part of the corpora cavernosa. Veins, empty into the dorsal vein of the penis and the prostatic venous plexus. They form intricate and well-developed plexuses in the erectile tissue. Lymphatics, the superficial terminate in the inguinal glands; the deep join the deep lymphatics of the pelvis. Nerves, are derived from the internal pudic nerve, and the pelvic or hypogastric plexus of the sympathetic. THE TESTES The Testes or Testicles are the glandular organs which secrete the seminal fluid, two oval bodies suspended obliquely in the scrotum by the spermatic cords, each measuring about an inch in diameter, and weighing THE TESTES 373 Their coverings, from without inward, are 6 in number, Scrotum (see Fig. 131). FIG. 130. % oz. to an ounce, as follows: Skin (4), of the scrotum. Dartos (5), the vascular tunic. Inter columnar Fascia, the external spermatic fascia (6, Fig. 131). Cremasteric Fascia (7, Fig. 131), muscular fibres, the cremaster muscle, derived from the lower border of the internal oblique muscle. Infundibuliform Fascia (9, Fig. 131), internal spermatic fascia, or fascia propria; a continuation downward of the transversalis fascia. Tunica Vaginalis, the serous covering, originally a process of the perit- oneum (see below). The Scrotum is a cutaneous pouch, consisting of 2 layers the in- tegument and the Dartos; the latter being a contractile vascular tunic, continuous with the superficial fascia of the thighs and perinaeum, and forming a septum in the scrotum between the two cavities for the testes. The Epididymis is an appendix to the testicle, lying along its posterior border, and consists of a single 'duct about 20 feet in length when unraveled, but which is wound upon itself so as to occupy a very small space. The Head or Globus Major (7), is formed by the coni vasculosi, or efferent ducts (6) of the testis, which therein open into the single duct which forms the epididymis. Body (8), is formed by the convolutions of the tube, held together by fine connective tissue. Tail or Globus Minor (9), the lower expanded portion, similarly formed, and connected to the testis by cellular tissue. Vas or Ductus Aberrans (n), a narrow tube, sometimes found opening into the canal of the epididymis near its lower end, and ending in a blind extremity. Hydatids of Morgagni (appendices testis), small pedunculated bodies, found attached to the epididymis or to the upper end of the testicle. One of them is believed to be the remains of the duct of Muller. Tunics of the Testis are 3 in number, the tunica vaginalis, or serous covering, externally; the tunica albuginea, or fibrous covering, in the middle; and the tunica vasculosa, or pia mater testis, internally. The 374 HUMAN ANATOMY FIG. 131. Tunica Vaginalis, the serous covering, has a visceral layer (n) (tunica vaginalis propria) and a parietal layer (8) (tunica vaginalis reflexa). Originally a part of the peritoneum, its upper end becomes oblit- erated, and the lower end remains as a closed sac, the space between the layers being the cavity (10) of the tunica vaginalis. It forms a pouch, the digital fossa (13), between the epididymis and the testicle. Tunica Albuginea (12), the fibrous covering, consists of white fibrous tissue, and forms ari incomplete vertical septum within the gland, the corpus Highmorianum or medi- astinum testis (2), from which fibrous bands (trabeculae) cross the gland, dividing its interior into spaces for the lobules of the organ. Tunica Vasculosa, the vascular covering, lies beneath the preceding, and lines the septa in the interior of the gland. It consists of a plexus of blood-vessels, held together by a delicate areolar tissue. Structure of the Testis. The glandular structure consists of 250 to 400 olbules, which are each con- tained in one of the spaces formed by the trabeculae, and formed of i to 3 or more minute, convoluted tubes, the tubuli seminiferi. The latter consist of a basement mem- brane, lined by several layers of cells, from which the spermatozoa are developed. In the apices of the lobules the tubuli become straight, and join to form 20 or 30 ducts, the Vasa Recta (4, Fig. 130), are each about 3^o mcn in diameter; then enter the mediastinum, passing upward and backward, and forming the Rete Testis (5), a network of anastomosing tubes or channels in the fibrous stroma of the mediastinum; they end in the Vasa E/erentia (6), 12 to 20 ducts, which perforate the tunica albu- ginea of the testis, and form a number of conical masses, the coni vasculosi which together constitute the globus major (7) of the Epididymis (see Fig. 130). APPENDAGES OF THE TESTES 375 Descent of the Testis. In early foetal life the testes are situated in the abdominal cavity, just below the kidneys, and are connected to the dartos of the scrotum and the tissues about the inguinal canal by a cord named the gubtrnaculum testis, which prevents the testicle rising with the growth of the foetus, and the testicle is drawn first into the inguinal canal and eventually into the scrotum, the cord itself becoming shortened as development proceeds. The descent begins about the commencement of the 5th month; during the 7th month the testicle enters the inguinal canal, and ordinarily arrives in the scrotum by the end of the 8th month. A process of peritoneum is carried down in front of the testis; which process, by obliteration of the canal, becomes a separate structure, the tunica vaginalis. The structures of the inguinal canal are also brought down with the testicle, and constitute some of its coverings. Vessels and Nerves. The Arteries are the Spermatic, from the aorta to the testicle itself; its coverings are supplied by the superficial and deep External Pudic from the femoral, the superficial Perineal branch of the Internal Pudic from the internal iliac, and the Cremasteric branch of the epigastric from the external iliac. Veins. The spermatic veins emerge at the back of the testis, receive branches from the epididymis, and unite into the convoluted pampini- form plexus, which forms the chief mass of the spermatic cord. From this plexus 3 or 4 veins arise, they unite into 2, and these join into a single trunk, which on the right side empties into the inferior vena cava, on the left side into the left renal vein. Lymphatics, of the testis terminate in the lumbar glands; those of its coverings in the inguinal glands. Nerves, of the testes are derived from the spermatic plexus, joined by filaments from the pelvic plexus; those of their coverings are the ilio- inguinal branch of the lumbar plexus, the superficial perineal branches of the internal pudic, the inferior pudendal branch of the small sciatic, and the genital branch of the genito-crural. APPENDAGES OF THE TESTES The Vas Deferens (ductus deferens) is the continuation of the epididymis, and the excretory duct of the testicle. Beginning at the globus minor it ascends along the back of the spermatic cord to the in- guinal canal, and enters the abdominal cavity through the internal ab- dominal ring. It curves around the outer side of the epigastric artery, crosses the external iliac vessels, and descends into the pelvis at the side of the bladder, crossing to the inner side of the ureter and the inner border of the vesicula seminalis. At the base of the prostate gland it 376 HUMAN ANATOMY joins the duct of the seminal vesicle to form the ejaculatory duct. The vas deferens is about 2 feet long, and has a canal of only half a line in diameter. Its walls are very dense, making it feel like a piece of wire or whip-cord when grasped between the fingers. In structure it consists of three coats, the Areolar Coat, externally, beneath which is the Muscular Coat, in 2 layers of unstriped fibre, the outer longitudinal, and the inner circular; but a third longitudinal layer is found at the commencement of the vas, internal to the circular layer. Mucous Coat, internally, is pale and in longitudinal folds; its epi- thelium is columnar. Artery of the Vas or Ductus Deferens, a branch of the superior vesical, ramifies on its coats and anastomoses with the spermatic artery. The Spermatic Cord (funiculus spermaticus) extends from the internal abdominal ring to the globus minor of the epididymis, and is about 4 inches long. At the external abdominal ring it rests upon the inguinal or Poupart's ligament, having the aponeurosis of the external oblique muscle in front, and the conjoined tendon behind it. It is composed of arteries, veins, lymphatics, nerves, and the vas deferens, bound together by areolar tissue, and invested by the layers brought down by the descent of the testicle. The structures, composing the spermatic cord, are 12 in number, and are named as follows: the Vas or Ductus Deferens. Spermatic Plexus of Nerves. Spermatic Artery. Branch of the Ileo-inguinal nerve. Cremasteric Artery. Branch of the Genito-crural (genito- Artery of the Vas Deferens. femoral) Nerve. Deferential Veins. Obliterated Processus Vaginalis of the Spermatic Veins. peritoneum (ligament of Cloquet). Internal Cremaster Muscle. Lymphatics. Coverings of the Cord, from within outward, are the Infundibuliform Fascia, from the transversalis fascia. Cremasteric Fascia, from the internal oblique muscle. Intercolumnar Fascia, the external spermatic fascia. Superficial Fascia, and the Skin, of the scrotum. The Vesiculae Seminales (d, Fig. 127) are two lobulated membranous pouches, which serve as reservoirs for the semen, and secrete a fluid to be added to the secretion of the testicles. They are about 2^2 inches long, and are situated externally to the lower ends of the vasa or ductus defer- entia, between the base of the bladder and the rectum. They are com- posed of 3 coats, an external areolar, a middle muscular, and an internal THE VULVA 377 mucous coat, lined with columnar epithelium. Their anterior extremities converge toward the base of the prostate gland, where a duct from each joins with the corresponding vas or ductus deferens to form Ejaculatory Ducts (ductus ejaculatorii), one on each side, are formed by the junction of the vasa or ductus deferentia with the ducts of the vesiculae seminales. They are about % inch in length, and terminate in the prostatic portion of the urethra, by orifices on the sides of the verumontanum (colliculus seminalis). Arteries, are derived from the middle and inferior vesical, and the middle haemorrhoidal; they are accompanied by veins and lymphatics. Nerves, are branches from the pelvic or hypogastric plexus. THE FEMALE ORGANS OF GENERATION (Organa Genital ia Muliebria) THE VULVA The Vulva, or Pudendum Muliebre, are the external genital organs of the female, viz., the mons Veneris, the labia majora and minora, the clitoris, and the orifice of the vagina. The Mons Veneris (commissura labiorum anterior), is the rounded eminence in front of the pubic symphysis, formed of fatty tissue beneath the skin, and covered with hair after puberty. The Labia Majora Pudendi (i) are two prominent longitudinal folds extending from the mons Veneris to the perinaeum. They are formed of hairy integument externally and modified skin internally, between which are areolar and dartoid tissues, fat, vessels, nerves, and glands. They meet in front, forming the anterior commissure (10), and nearly meet behind in the posterior commissure at the anterior boundary of the peri- naeum. They correspond to the scrotum of the male. The Fourchette (commissura labiorum posterior) (2), is the curved anterior edge of the perinaeum, and between it and the hymen (8) there is a depression, the fossa navicularis. Nerves, the superficial perineal from the pudic, and the inferior pudendal from the small sciatic. The Labia Minora Pudendi (3), or Nymphce, are two small folds, situated internally to the labia majora, and extending from the prepuce of the clitoris (praeputium clitoridis) (4) obliquely backward for i% inches on each side ot the vaginal orifice, where they are lost on the inner surface of the labia majora. They are composed of modified skin, and have 378 HUMAN ANATOMY FIG. 132. sebaceous follicles (glandulaa vestibulares minores) on their internal surface. Clitoris, is situated beneath the anterior commissure, its glans (4) only appearing externally as a small rounded tubercle between the anterior extremities of the labia minora. It is a diminutive penis, in all but the corpus spongiosum and urethra; having two corpora cavernosa, two crura, a glans, prepuce, suspensory ligament and - muscles, the erectores clitoridis (ischio-cavernosi) . Vestibule (vestibulum vaginae) (6), is a triangular depression in front of the vaginal orifice, bounded laterally by the labia minora. Meatus Urinarius (orificium urethras externum) (5), situated in the vestibule, about an inch below the clitoris, and close to the vaginal orifice. Bulbi Vestibuli, are two oblong erec- tile bodies, situated one on either side of the vestibule, and consist- a. ing of a venous plexus surrounded by a fibrous membrane. They are the analogues of the bulb of the corpus spongiosum in the male. Pars Intermedia, is a small venous plexus situated between the glans clitoridis and the bulbi vestibuli. It is the analogue of the corpus spongiosum. Orifice of the Vagina (7), is surrounded by the sphincter vaginae muscle, and in the virgin is sometimes partly closed by the hymen. ^H^men (8), a fold of mucous membrane situated across the lower part of the vaginal orifice, of various shapes, usually a ring, but often semilunar, the concavity upward. It is frequently absent in virgins. Its cicatrization after rupture gives rise to small eminences along the margin of the vaginal orifice, named the caruncula myrtiformes (carunculae hymenales). Glands of Bartholin (glandulae vestibulares majores), one on each side of the vaginal orifice^ their ducts opening (9) near the inner sides of THE VAGINA 379 the labia minora. They are the analogues of Cowper's glands (glandulae bulbo-urethrales) in the male. Nerves, to the labia minora as to the labia majora; the bulbi vestibuli and other erectile structures are supplied by filaments from the dorsal nerve of the clitoris, superficial perineal, and hypogastric plexus. THE VAGINA The Vagina is a curved canal extending from the vulva to the ute ', placed between the bladder in front and the rectum behind. Its len is about 2^ inches along the anterior wall (paries anterior), 3^ inc* along the posterior wall (paries posterior), and its walls are usually in co tact with each other. It is very dilatable, especially near its upper em. which surrounds the vaginal portion of the cervix uteri, its attachment extending higher up on the posterior wall of the uterus than on the anterior wall. Its relations are Anteriorly, the urethra and the base of the bladder. Posteriorly, the anterior wall of the rectum, and the recto-vaginal fold of peritoneum which forms Douglas' pouch (excavatio recto-uterina) behind its upper fourth. Laterally, are attached the levatores ani muscles, and the recto-vesical portion of the pelvic fascia. Structure of the Vagina. The vaginal wall consists of a muscular coat (tunica muscularis) externally, a layer of erectile tissue, and a mucous lining (tunica mucosa) covered with squamous epithelium, and furnished with mucous crypts and follicles, but has no glands. The vagina is par- tially covered laterally by the recto-vesical portion of the pelvic fascia. Columns of the Vagina (columnae rugarum anterior et posterior), are two longitudinal raphes situated along its inner surface, one anteriorly, the other posteriorly, which are connected by numerous transverse ridges or ruga vaginales. Sphincter Vagina Muscle, surrounds the lower end of the vagina; it is described on page 99. Vessels and Nerves. The Arteries of the vagina are the Vaginal branches of the internal iliac, and branches of the uterine artery, which form in front and behind a longitudinal vessel, the azygos arteries of the vagina. The Veins, are disposed similarly to the arteries, form a rich plexus in the muscular and mucous coats, and terminate in the vaginal and uterine trunks. Lymphatics, terminate in the pelvic and inguinal glands. 380 HUMAN ANATOMY Nerves, are derived from the hypogastric plexus, the fourth sacral nerve, and the pudic nerve (n. pudendus), forming a vaginal plexus. THE UTERUS The Uterus is a hollow, pear-shaped, muscular organ, measuring about 3 inches long, 2 inches broad, and i inch thick, flattened from before back- ward, placed base upward, forming ah angle with the vagina, which par- tially receives its cervix, and situated in the pelvic cavity, between the bladder in front and the rectum behind. Its Fundus uteri (A), is broad, convex, having walls % inch thick, and is covered by peritoneum. Body (corpus uteri), is about i% inches long, walls % inch thick, flat anteriorly, convex posteriorly, concave laterally, and joined to the bladder by its lower anterior fourth. It is invested by peritoneum posteriorly, and in front for its upper three-fourths. FIG. 133. Cervix Uteri or Neck, is the lower constricted portion, about i % inches long, walls Y inch in thickness, and is embraced for % to % inch by the upper extremity of the vagina. Cavity of the Body (cavum uteri) (B), is small and triangular, flattened from before backward, about i% inches in length, and has two lateral cornua above, and a constricted orifice, the os internum (orificium in- ternum uteri), at its lower angle, opening into the cavity of the cervix. Cavity of the Cervix (canalis cervicis uteri), is spindle-shaped, about i% inches long, and presents on its inner surf ace transverse folds of mucous membrane proceeding from a longitudinal fold, giving an appearance named the arbor vitce (plicae palmatae) (o). Os Uteri (orificium externum uteri), is a transverse orifice at the lower THE UTERUS 381 end of the cervical cavity, opening into the vagina, and having an anterior (labium anterius) and a posterior lip (labium posterius). Ligaments of the Uterus are 8 in number, i anterior, i posterior, 2 lateral or broad ligaments, 2 sacro-uterine, and 2 round ligaments, all except the last-named being formed of peritoneum. The Anterior Ligament, utero-vesical, is reflected from the front of the uterus on to the bladder. It forms the floor of the utero-vesical pouch (excavatio vesico-uterina). Posterior Ligament, recto-vaginal, passes from the posterior wall of the uterus over the upper fourth of the vagina, and thence on to the rectum and sacrum, forming Douglas' pouch (excavatio recto-uterina) behind the upper portion of the vagina. Lateral or Broad Ligaments (ligamenta lata uteri) 2, pass from the sides of the uterus to the lateral walls of the pelvis, and form a septum across the pelvic cavity. They contain, between the two folds of peritoneum of which they are composed, the Fallopian tubes (tubae uterinas) the round ligaments, the ovaries, the parovaria or organs of Rosenmiiller, connective tissue, unstriped muscular fibre, blood- vessels, and nerves. Sacro-uterine Ligaments (plicae recto-uterinae) 2, pass from the sides of the uterus to the sides of the rectum, and thence to the sacrum. Round Ligaments (ligamenta teres uteri) 2 (G), are two cords, about 4 or 5 inches long, composed of muscular tissue prolonged from the uterus, also areolar and fibrous tissue, vessels and nerves, extending one on each side, from the lateral aspects of the fundus uteri, through the inguinal canals, to the labia majora, where they are lost. Each ligament lies, for a part of its course, between the two layers of the broad ligament, and is covered by a process of peritoneum. The Canal of Nuck, is the extension of the above-mentioned process of peritoneum into the inguinal canal. It exists in the foetus, but is usually obliterated in the adult. Structure of the Uterus. The wall of the uterus is composed of 3 coats, an External serous, a middle muscular, and an internal mucous coat. The muscular coat (tunica muscularis) forms the chief bulk of the organ, and consists of bundles of unstriped muscular fibres, disposed in 3 layers interlaced together; circular fibres predominating in the cervix, longi- tudinal fibres in the body of the uterus. The Peritoneal or Serous Coat (tunica serosa), invests the body of the organ, except its lower anterior fourth. Mucous Coat (tunica mucosa), is very thick, ^(2 to 3^ inch, and closely 382 HUMAN ANATOMY adherent to the muscular tissue, having no basement layer of con- nective tissue. It is covered with ciliated columnar epithelium, and studded with mucous follicles and tubular glands (glandulse uterinae), which are most numerous in the cervix. Vessels and Nerves. The Arteries of the uterus are the Uterine from the internal iliac, and the Ovarian from the aorta; the two meeting on the side of the body and forming an anastomotic trunk, from which lateral branches are given off to the uterus. They are remarkably tortuous and anastomose freely. The Veins, accompany the arteries, and in the impregnated state become sinuses. They end in the uterine plexuses. Lymphatics, those of the cervix end in the pelvic glands, those of the body in the lumbar glands. Nerves, are derived from the inferior hypogastric and ovarian plexuses, and from the 3d and 4th sacral nerves. APPENDAGES OF THE UTERUS The Fallopian Tubes, or Oviducts (tubas uterinae) (D), are two tubes, each about 4 inches in length, and i H 6 inch in calibre, situated in the free margin of the broad ligament, and extending from the superior angles of the uterus (&) outward, to terminate in free, trumpet-shaped ends. They open by one end into the uterus at its cornua, by the other end into the peritoneal cavity. Their structure is similar to that of the uterus, the mucous lining being continuous with the uterine mucous membrane and with the peritoneum, and lined with ciliated columnar epithelium. Their Isthmus Tubes Uterines, is the inner constricted third of the tube. Ampulla Tubes Uterines, is the outer dilated portion, curving over the ovary. Infundibulum Tubes Uterince, the trumpet-shaped outer end, with its open mouth, the ostium abdominale tubce uterince, surrounded by Fimbrice Tubes Uterines (E), fringe-like processes, one of which, the fimbria ovarica, is attached to the ovary. Hydatids of Morgagni (appendices vesiculosi) (see page 372), one or more small vesicles floating on a long stalk of peritoneum, are fre- quently found in connection with or near the fimbriae. Vessels and Nerves, The vessels are those of the ovaries; the nerves are branches from one of the uterine nerves. The Ovaries (ovaria) (F) are two oval bodies, of grayish-pink color, situated in the broad ligament, behind and below the Fallopian tubes, ( tubae uterinae,) one on each side of the uterus, to which they are attached THE MAMMAE 383 by the ligament of the ovary. They each measure about i % inches by % by H, and are invested by peritoneum, except posteriorly. They are composed of a vascular stroma containing the Graafian vesicles (folliculi oophori vesiculosi) in various stages of development, and are surrounded by the tunica albuginea, a condensed layer of the stroma. The Graafian Vesicles (folliculi oophori vesiculosi) are the ovisacs containing the ova, are very numerous (about 70,000 in each ovary), vary in diameter from Hoo to %o inch, but after puberty a few are found of from Ho to ^ inch or more. Each vesicle has an external fibro-vascular coat, and an internal coat (tunica externa) or ovicapsule, (theca folliculi) which is lined by the membrana granulosa (stratum granulosum) and contains a transparent fluid of albuminous character, containing the immature ovum. The Membrana Granulosa (stratum granulosum), is a layer of nucleated cells, lining the ovicapsule; at one point the cells are heaped up in a mass, the discus proligerus (cumulus oophorus), in which the ovum is embedded. Corpus Luteum, is a puckered yellow spot in the substance of the ovary, produced as a result of the rupture of a Graafian vesicle and the discharge of an ovum, probably by the organization of the extrava- sated blood, forming lutein cells. In old age the corpus luteum undergoes involution, loses its yellow color, and is then called the corpus albicans. Vessels and Nerves. The Arteries are the Ovarian, from the aorta, which also supply the Fallopian tubes, and anastomose with the uterine arteries. The Veins, accompany the arteries, and form a plexus, the pampiniform plexus, near the ovary. Nerves, are derived from the inferior hypogastric or pelvic plexus, and from the ovarian plexus. The Parovarium, or Organ of Rosenmuller, is a group of tubules, situated in the broad ligament, between the ovary arid the Fallopian tube, and con- verging to a large duct, the duct of Gartner, which ramifies in the broad ligament, descends along the side of the uterus, and terminates in a bulb- ous enlargement. It is the atrophied remains of the Wolffian Body of fcetal life. THE MAMMAE The Mammae, or Breasts, are two hemispherical eminences, situated one on each antero-lateral aspect of the chest, extending from the sternum to the axilla, and from the 3d rib to the 7th. Each breast contains the 384 HUMAN ANATOMY Mammary Gland (corpus mammae) and is surmounted by the nipple (papilla mammae), around the base of which is a zone of colored cutaneous tissue, the areola mamma, pink in virgins, darker in women who have borne children. In the male the mammae .r IG 134" are rudimentary organs, but capable of development under special circumstances. Structure of the Mammary Gland. Is composed of 15 or 20 lobes (lobi mammae) and their ducts (i), with a packing of areolar and adipose tissue (subcutaneous tela), enveloped by a thin fibrous capsule or stroma which forms septa between the lobes. Each lobe is made up of lobules (2), and these again are formed by the aggregation of alveoli, terminal vesicles by which the milk is secreted. The Tubuli Lactiferi (ductus lactiferi) (i), are the excretory ducts of the lobes, one for each. They are formed by the junction of the ducts from each lobule, and converge towards the areola, beneath which they form ampulla or dilatations, and thence, piercing the nipple, open on its summit by separate orifices. Vessels and Nerves. The Arteries are derived from the thoracic branches of the axillary, the intercostals, and the internal mammary arteries. Veins, form the circulus venosus, an anastomotic venous circle around the base of the nipple, from which larger veins run outward, and ter- minate in the axillary and internal mammary veins. Lymphatics, terminate in the axillary glands; a few going to the anterior mediastinal glands. Nerves, are derived from the lateral cutaneous branches of the 4th, 5th, and 6th intercostal nerves and from the thoracic portion of the sympathetic cord. HERNIA A Hernia is a protrusion of any viscus from its natural cavity. The term, when unqualified as to the viscus, is understood to mean a protrusion of the intestines or mesentery, or both, from the abdominal cavity. Ana- tomically the most important hernias are INGUINAL HERNIA 385 Oblique Inguinal Hernia, in which the protrusion follows the spermatic cord through the inguinal canal; passing to the outer side of the epi- gastric artery, and through both the internal and external abdominal rings. Direct Inguinal Hernia, occurs at Hesselbach's triangle, escaping to the inner side of the epigastric artery, and through the subcutaneous inguinal or external abdominal ring only. Femoral Hernia, in which the protrusion descends through the femoral or crural canal. H INGUINAL HERNIA The Inguinal Canal is a passage in the abdominal wall, parallel to the inguinal or Poupart's ligament, and just above it. It commences at the abdominal inguinal or internal abdominal ring and ends at the subcu- taneous inguinal or external abdominal ring (i), being about i^ inches in length. It serves for the passage of the spermatic cord in the male, and the round ligament of the uterus in the female; is directed downward and inward, and is bounded as follows: Anteriorly, the skin, superficial fascia, (camper's) external oblique muscle for its entire length, and the internal oblique (the part attached to the inguinal ligament) for the outer third of the canal. Posteriorly, the conjoined tendon of the internal oblique and trans- versalis, transversalis fascia, triangular fascia (5) for the medial two-thirds, sub-peritoneal tissue, transversalis fascia, and peritoneum for its entire length. Above, the arched fibres of the internal oblique and transversalis muscles. Below, the union of the transversalis fascia (5) with Poupart's (in- guinal) ligament (10). The Internal or Deep Abdominal Ring (annulus inguinalis abdo minis), is an oval opening in the transversalis fascia, formed by the prolongation of this fascia around the cord, as the infundibuliform fascia. It lies Y 2 inch above Poupart's (inguinal) ligament (10) and midway between the anterior superior spine of the ilium and the spine of the pubes (8). It is bounded above and externally by the arched fibres of the transversalis muscle; below and internally by the epigastric vessels. The Deep Epigastric Artery, lies between the transversalis fascia and the peritoneum, passing obliquely upward and inward along the lower and inner margins of the internal ring. Infundibuliform Fascia, or infundibuliform process of the transversalis fascia, is a thin, funnel-shaped membrane, arises from the circum- 25 386 HUMAN ANATOMY ference of the internal ring, and is continued (internal spermatic fascia) around the cord and testis, enclosing them in a distinct pouch. The External or Superficial Abdominal Ring (annulus inguinalis sub- cutaneous) (i), is a somewhat triangular opening in the aponeurosis of the external oblique muscle, situated just above and external to the crest of the pubes. It is about i inch long, and ^ inch wide, and is bounded laterally by its own margins, called the external (crus inferius) (2) and internal (crus superius) (3) pillars of the ring. It may be easily felt in 10 the living male, by invaginating the skin of the scrotum with the finger, and feeling up along the spermatic cord (9). It is much larger in men than in women. The Inter columnar or External Spermatic Fascia (fibrae intercrurales) (6), is formed by tendinous fibres which arch across the lower part of the aponeurosis of the external oblique, between the pillars of the ex- ternal ring, and are connected together by delicate fibrous tissue. It is continued downward as a tubular prolongation around the cord and testis, enclosing them in a distinct sheath. Cremasteric Fascia (fascia cremasterica), passes through the external ring, and consists of a series of muscular loops, united by areolar tissue, forming a thin covering over the spermatic cord and testis. INGUINAL HERNIA 38? The muscular fibres (Cremaster muscle) are supposed to have been originally part of the internal oblique muscle, carried down by the testicle in its descent to the scrotum. It does not exist in the female. FIG. 136. Poupart's Ligament (ligamentum inguinale), or the Crural Arch, is that portion of the aponeurosis of the external oblique muscle which extends from the anterior supe- rior spine of the ilium to the spine of the pubes. Its lower portion (3) forms the external pillar of the external abdominal ring, and its reflection along the pectineal line is called Gimbernafs ligament (ligamentum lacunare) (2). Other fibres, reflected be- hind the internal pillar of the ring (4), upward to the linea alba, are termed the triangular fascia (ligamentum inguinale re- flexum) (i). Gimbernat's Ligament (liga- mentum lacunare) (2), is that portion of the aponeu- rosis of the external oblique which is reflected upward and outward from the spine of the os pubis to be inserted into the pectineal line. Its> anterior margin is continuous with Poupart's (inguinal) ligament. Triangular Fascia (ligamentum inguinale reflexum) (i), is a tri- angular band, attached by its apex to the pectineal line, where it ia continuous with Gimbernat's (lacunar) ligament; passes inward beneath the spermatic cord, behind the internal pillar (crus superius) of the external or subcutaneous inguinal ring, and in front of the conjoined tendon, to interlace with its fellow of the opposite side at the linea alba (see 5, Fig. 134). It is often undeveloped or wanting. Hesselbach's Triangle is a small triangular space on the lower ab- dominal wall, bounded externally by the deep epigastric artery, internally by the margin of the rectus muscle, below by Poupart's (inguinal) liga- 388 HUMAN ANATOMY ment. Its inner ^ is crossed by the conjoined tendon. Through this space a direct inguinal hernia forces its way. The Inguinal Peritoneal Fossce, are 3 depressions of peritoneum in the in- guinal region above Poupart's (inguinal) ligament. The internal (fovea supravesicalis) and middle (fovea inguinalis medialis) ones lie in Hesselbach's triangle, the external fossa (fovea inguinalis lateralis) usually corresponds to the internal abdominal or abdominal inguinal ring. Coverings of Inguinal Hernia depend, in the oblique form, upon the extent to which the hernia descends in or through the inguinal canal. When it has escaped from the external abdominal or subcutaneous in- guinal ring, and is therefore complete, its coverings, from without inward, are 7 in number, as follows: 1. Skin. 2. Superficial Fascia, 2 layers. 3. Inter columnar Fascia, from the external abdominal ring. 4. Cremasteric Fascia, from the inguinal canal. 5. Infundibuliform Fascia, from the internal abdominal ring. 6. Subserous Areolar Tissue, almost inappreciable. 7. Peritoneum, the hernial sac proper. Direct Inguinal Hernia has the same coverings, except that the Conjoined Tendon is substituted for the cremasteric fascia, and the Transversalis Fascia for the infundibuliform. FEMORAL HERNIA The Femoral or Crural Canal is a narrow interval, % to % inch long, between the femoral vein (4) and the inner wall of the femoral sheath (fascia cruris), extending from Gimbernat's (lacunar) ligament to the saphenous opening (fossa ovalis). It exists as a distinct canal only when the sheath has been separated from the vein by the pressure of a hernia or tumor, or by dissection. It lies beneath Poupart's (inguinal) ligament (i), is closed above by the septum crurale of Cloquet (septum femorale), below by the cribriform fascia (fascia cribrosa), and is bounded as follows: Anteriorly, by a continuation downward, under Poupart's (inguinal) ligament, of the transversalis fascia, covered by the falciform process (margo falciformis) of the fascia lata. Posteriorly, by a downward continuation of the iliac fascia, covering the pubic portion of the fascia lata. Externally, by the fibrous septum separating it from the inner side of the femoral vein. FEMORAL HERNIA 389 FIG. 137. Internally, by the outer edge of Gimbernat's (lacunar) ligament, and the junction of the processes of the transversalis fascia and the iliac fascia, which form the inner side of the femoral sheath. The Femoral or Crural Ring (annul us femoralis), the upper opening of the femoral canal, is an oval-shaped opening, about ^ inch in diameter (larger in the female), situated below the internal abdominal or subcutaneous inguinal ring (7) and Poupart's (inguinal) ligament (i), and between the inner side of the femoral vein and the margin of Gimbernat's (lacunar) ligament (5). It is closed by the septum crurale (septum femorale) and a small lymphatic gland. The arrow in the figure points into the fem- oral ring. The Femoral Vein (4), lies next on its outer side. Deep Epigastric Artery (a. epi- gastrica inferior), crosses its upper and outer angle. Obturator Artery, when arising from a common trunk with the epi- gastric, as it does once in 3^ subjects, may lie close along its internal and superior margins. Communicating Branch, between the deep epigastric and obturator arteries, lies in front of the ring. Spermatic Cord (funiculus spermaticus), in the male, lies directly above its anterior margin, replaced by the round ligament in the female. Septum Crurale, or Fascia of Cloquet (septum femorale), is a layer of condensed areolar tissue, supporting a lymphatic gland, and per- forated for the passage of lymphatic vessels. It lies across the femoral ring, and forms one of the coverings to any hernia escaping thereby. The Saphenous Opening (fossa ovalis), the lower orifice of the femoral canal, is an oval-shaped aperture, i^ by ^ inch in diameter, formed by a reflection of the fascia lata inward, around and under the end of the in- ternal saphenous vein (3). It is situated below the inner third of Pou- part's (inguinal) ligament, and is covered by the cribriform fascia (fascia cribrosa). Its inner margin curves upward behind the saphenous vein and under the outer margin, and is blended with the pubic portion of the HUMAN ANATOMY fascia lata over the pectineus muscle. Its outer margin curves over the inner to the spine of the pubes, as a Falciform Process, or Superior Cornu (margo falciformis), is thin but strong, sharply defined, and lies on a plane anterior to the inner margin. It ascends in front of the femoral vessels, and curving inward is attached toPoupart's (inguinal) ligament, the spine of theos pubis, and the pectineal line, where it is continuous with the pubic portion. It is sometimes named the ligament of Burns, its pubic end is called the ligament of Hey. Cribriform Fascia (fascia cribrosa) (n, Fig. 134), is the portion of the deep layer (Scarpa's) of the superficial fascia which covers the saphenous opening (fossa ovalis). It is perforated by the internal saphenous vein and by numerous blood-vessels and lymphatics. The Femoral or Crural Sheath, the investing sheath of the femoral ves- sels, is a funnel-shaped prolongation of the lining fasciae of the abdomen, the transversalis fascia in front, and the iliac fascia behind. The sheath is divided by two septa into 3 compartments, the external of which contains the femoral artery, the middle one the femoral vein, the internal one being the femoral canal. The sheath is perforated anteriorly by the genito-crural nerve, internally by the internal saphenous vein, and forms one of the coverings of a femoral hernia. The Deep Crural Arch, is the thickened border of the transversalis fascia, which arches across the front of the crural sheath, and is intimately connected to it. Externally it is attached to the centre of Poupart's (inguinal) ligament, internally it is inserted into the pectineal line /behind the conjoined tendon. Coverings of Femoral Hernia depend upon whether the hernia has or has not escaped from the saphenous opening (fossa ovalis) , and is therefore complete or incomplete. In the latter case, the covering, from without inward would be skin, superficial fascia, cribriform fascia, femoral sheath, septum crurale, subserous areolar tissue (fascia propria of Sir Astley Cooper), and peritoneum. The coverings of a complete femoral . Jifitnia. axe. as follows: i. Skin. I 2. Superficial Fascia, its superficial layer (subcutaneous tela). 3. Cribriform Fascia, from the saphenous opening. 4. Femoral Sheath, from the transversalis fascia. 5. Septum Crurale, from the femoral ring. 6. Subserous Areolar Tissue, the fascia propria of Cooper. 7. Peritoneum, the proper hernial sac. THE PELVIC CAVITY 39 1 THE PERINEUM, PROPER The Perinaeum is a triangular space containing the structures which close the inferior outlet of the pelvic cavity anterior to a line drawn be- tween the tuberosities of the ischia. Posteriorly to thisline the correspond- ing space is named the I schio-rectal Region. The Perinaeum is bounded laterally by the rami of the pubes and ischia, anteriorly by the symphysis pubis, and posteriorly by the line above mentioned, which averages about 2% inches in length. For the Muscles of the Perinaeum, see page 98. THE PELVIC CAVITY The Pelvic Cavity is that portion of the abdominal cavity which lies below the level of the ilio-pectineal line and the promontory of the sacrum. The osseous pelvis is described on page 9. The boundaries of the pelvic cavity are as follows: Anteriorly and Laterally, the pubes and ischia, covered by the obturator muscles. Posteriorly, the sacrum and coccyx, the pyriformis muscles, and the great sacro-sciatic ligaments (lig. sacro-tuberosa). Floor, is formed by the recto-vesical fascia, covering the levator ani and coccygeus muscles of each side, and the triangular ligament (diaphragma-urogenitale) of the urethra. Contents of the Pelvic Cavity are the bladder, rectum, some convolu- tions of the small intestine, and some of the organs of generation. They are partially covered by peritoneum, and supplied with vessels and nerves. THE PELVIC FASCIA The Pelvic Fascia lines the pelvic cavity and is continuous with the iliac and transversalis fascia above. At the level of a line drawn from the back of the symphysis pubis to the spine of the ischium, it is thickened into a white line or band (arcus tendineus), where it gives origin to the levator ani muscle, and divides into 2 layers, the recto-vesical fascia or visceral layer, and the obturator fascia or parietal layer. The Recto-vesical Fascia, visceral layer of the pelvic fascia, descends from the white line (arcus tendineus) over the upper or pelvic surface of the levator ani muscle, and is prolonged over the prostate gland, rectum, vesiculae seminales, and the bladder, forming the lateral true ligaments of the latter organ. Obturator Fascia, the parietal layer of the pelvic fascia, descends from the white line along the wall of the pelvis, and covers the obturator 392 HUMAN ANATOMY interims muscle, near the lower border of which it forms a canal be- tween its layers, Alcock's canal) for the pudic vessels and nerve. Above this canal it gives off a thin membrane, the ischio-rectal or anal fascia over the lower or perineal surface of the levator ani muscle; also a process, which with its fellow of the opposite side forms the deep (superior) layer of the triangular ligament (diaphragma urogenitale). Illustration of the Pelvic Fascia. The capital letter K, having a hori- zontal arm added to it, thus K, will illustrate the pelvic fascia of the right side, seen from the front in vertical section. The vertical line of the K represents the pelvic fascia above, the obturator fascia below. The upper arm represents the lateral ligament of the bladder, the horizontal arm the recto-vesical fascia, and the lower arm the ischio-rectal fascia. The space between the lower arm and the vertical line represents the ischio-rectal fossa. THE MALE PERINEUM The Male Perinaeum, in the adult, varies in breadth on the base line, from 2 to 3^ inches, the average FIG. 138. being 2% inches. Its middle line is convex, corresponds to the bulb of the urethra, and presents a prominent raphe, which is con- tinuous in front with the raphe of the scrotum. Its muscles are described on page 98. Fasciae of the Perinaeum are superficial and deep, each con- sisting of two layers; the deep fascia being usually called the triangular ligament of the urethra. The Superficial Layer of the Super- ficial Fascia (subcutaneous tela), is thick, loaded with fat, and continuous with the subcutaneous fascia of the thighs. Deep Layer of the Superficial Fascia, Colics' Fascia, is thin but strong, continuous in front with the dartos of the scrotum, and attached on each side to the rami of the pubes and ischium; posteriorly it joins the deep perimeal fascia under the superficial transversus perinaei muscle. THE MALE PERINEUM 393 Superficial Layer of the Deep Perinaal Fascia (fascia diaphragmatis urogenitalis inferior), is triangular in shape, and extends from the sides of the pubic arch and the sub-pubic ligament, laterally to the rami of the pubes and ischia, and posteriorly to the central tend- inous portion of the perinaeum, where it becomes blended with Colic's fascia and the deep layer of the deep fascia. It embraces the anterior part of the membranous portion of the urethra. Deep Layer of the Deep Perinceal Fascia (fascia diaphragmatis urogenitalis superior), has the same attachments as the superficial layer above described, in its course it embraces the posterior part of the mem- branous portion of the urethra, and is in connection with the apex of the prostate gland. Buck's Fascia is a continuation of the deep layer of the superficial fascia of the perinaeum, extending forward upon the penis, which itinvests com- pletely as far as the glans. It is continuous above with the suspensory ligament of the penis, and is held by some anatomists to prove that the deep layer aforesaid is not continuous in front with the dartos of the scrotum. This fascia was named from Dr. Buck, an American surgeon, who, in 1846, first insisted on the importance of this structure. It modifies the direction of urinary infiltration of the perinaeum, until perforated. The Superficial Perin&al Interspace or Fossa is the interval between the deep layer of the superficial fascia (Colles' fascia) and the triangular ligament or urogenital diaphragm. It contains the following structures: Crura of the Penis (4). 1 ' schio-cavernosus or Erector Penis Corpus Spongiosum (corpus Muscle (10). cavernosum urethrae). Superficial Transversus Pcrincei Bulb of the Urethra. Muscle (14). Bulbo-cavernosus or Accelerator Superficial Transversus Perinai Urines Muscle (8). Artery. Superficial Perinaal Vessels and Nerves (5). The Deep Perinceal Interspace or Fossa is the interval between the two layers of the triangular ligament or urogenital diaphragm. It contains the following structures: Membranous Urethra. Dorsal Vein of the Penis. Deep Transversus Perinai or Com- Artery of the Bulb, pressor Urethrce Muscle. Nerve of the Bulb. Pudic Vessels and Nerve (n). Plexus of Veins. Cowper's Glands (glandula bulbo- yrethrales) and Ducts. 394 HUMAN ANATOMY Central Tendinous Point is a fibrous point in the middle line of the perinaeum, internal to the deep layer of the superficial fascia and about % inch in front of the anus. It corresponds to the centre of the posterior margin or base of the triangular ligament or urogenital diaphragm (12), and is the point of attachment for 4 converging muscles, the external sphincter (16), bulbo-cavernosus or accelerator urinae (8), and two super- ficial transverse perinaeal (14). ISCHIO-RECTAL REGION The Ischio-rectal Space is the horse-shoe-shaped space behind and above the perinaeum. It is somewhat triangular in cross-section. It extends posteriorly to the tip of the coccyx, laterally to the tuberosities and rami of the ischia and anteriorly, on each side, it presents an Anterior Exten- sion which extends forwards as far as the body of the pubis. In fat sub- jects this extension is distended with fat, in which case it is triangular FIG. 139. in cross -section, the floor being formed by the deep layer of the trian- gular ligament (uro-genital diaphragm), outer wall by obturator fascia and muscle, and the inner wall by the leva tor an i muscle and its fascia. In the middle line it presents the anal orifice, and deeply on each side, the Ischio-rectal Fossa, which contains the lower part of the rectum, areolar tissue and fat. The fossa is about i inch broad at its base and about 2 THE FEMALE PERINEUM 395 inches deep; its apex, directed upward, corresponds to the junction of the obturator fascia and the ischio-rectal fascia. It contains the Superficial Fascia (subcutaneous tela), is thick, areolar in texture, with much fat in its meshes, also branches of the perforating cu- taneous nerve. It is a single layer. Muscles, the corrugator cutis ani, external and internal sphincters (16), and the levator ani (18). Rectum, surrounded by areolar tissue and fat. Internal Pudic (pudenda!) Artery (n), with its veins and the two divisions of the nerve, about ^ inch above the margin of the tuber- osity of the ischium. Inferior Hemorrhoidal Vessels and Nerves (13), cross the space trans- versely. Superficial Perinceal Vessels (5) and Nerves (3), in the front part of the space for a short distance. Branch of the ^th Sacral Nerve, at the back of the space, near the coccyx. Ischio-rectal or Anal Fascia, a thin membrane given off from the obtu- rator fascia over the levator ani muscle, at the apex of the fossa (see pages 390-391). Obturator Fascia, covering the obturator internus muscle, at the outer side of the fossa (see page 390). Recto-vesical Fascia, invests the internal surface of the levator ani muscle, near the base of the fossa; also the rectum at the inner side of the fossa (see page 390). THE FEMALE PERINEUM The Female Perinaeum performs the special function of supporting the posterior wall of the vagina, and thereby aiding materially in the support of the whole vagina, the uterus and the bladder. The PerincBal Body, is the pyramidal-shaped prolongation of the female perinaeum upward between the vagina and the rectum. It measures about \Y inches antero-posteriorly, and extends laterally from one ischial tuberosity to the other. In it are situated the muscles of the external organs of generation. Differences between the Female and Male Perinsea are chiefly due to the perforation of the structures in the median line of the female perinaeum by the vulvo-vaginal passage. The Superficial Fascia, is incomplete, by reason of its perforation by the orifice of the vulva, but consists of two layers, subcutaneous tela and Colics' fascia, as in the male. 396 HUMAN ANATOMY Deep Perinaal Fascia (urogenital diaphragm), being also perforated by the vagina is less apparent than in the male, though presenting two layers, with the urethra perforating them, as in the other sex. Bulbi Vestibuli and Paries Intermediates, represent the corpus spongio- sum of the male, divided into two lateral segments. Prostate Gland, is absent in the female, but its place is occupied by a number of minute glands disposed around the neck of the bladder. Muscles, The Sphincter Vaginae in the female, takes the place of the bulbo-cavernosus or accelerator urinse in the male; the Superficial Transversus Perinaei is similar in both sexes; the Erector Clitoridis is smaller than the erector penis, but differs in no other respect; both are called ischio-cavernosus; the Deep Transversi Perinaei or Compressores Urethras are separate and attenuated in the female, their anterior fibres passing in front of the urethra, the middle fibres to the sides of the vagina, the posterior fibres to the central tendinous point of the perinaeum. Structures Divided in Lithotomy. In the Lateral Operation the knife is inserted deeply i^ inches in front of the anus, a little to the left of the median line, and the incision is carried obliquely backward and outward, becoming more superficial as it is extended, to a point midway between the anus and the tuberosity of the left ischium, dividing the Skin and Superficial Fascia (first layer of the latter). Inferior Hemorrhoidal Vessels and Nerves (13). Deep Layer of the Superficial Fascia (6). Superficial Perinaal Vessels (5) and Nerves (3). Bulbo-cavernosus (Accelerator Urinae) Muscle (8) (posterior fibres). Superficial Transversus Ferincei Muscle (14) and Artery. Inferior Layer of the Triangular Ligament (12). Deep Transversus Perin&al (Compressor Urelhrce) Muscle (a few fibres). Levator Ani Muscle (18) (anterior fibres). Membranous and Prostatic Portions of the Urethra (2). Superior Layer of the Triangular Ligament (Urogenital diaphragm) (12). Prostate Gland (part of the left lobe). Neck of the Bladder (in part). In Median Lithotomy, the incision, i}-^ inches long, is made transversely through the central tendinous point and raphe, dividing the Skin and Superficial Fascia. Sphincter Ani Muscle (16) (some of its anterior fibres). Branches of the Transverse Perinceal Vessels and Nerves. Base of the Triangular Ligament (Urogenital diaphragm) (12). LITHOTOMY 3Q7 Membranous Portion of the Urethra (2). Bulbo-Cavernosus (Compressor Urethra) Muscle. Structures to be Avoided in Lithotomy. In the Lateral Operation the structures to be remembered and avoided in making the incision are the Bulb, its Artery, and the Rectum, inwardly and in front; avoided by not making the primary incision too near the middle line nor too far forward. Pudlc Artery di), externally; avoided by not carrying the incision too far outwardly. Prostrate Gland and Veins, behind; avoided by not carrying the deep incision too far backward, so as to cut through the entire lobe of the prostate gland, permitting the urine to infiltrate into the loose areolar tissue around the rectum, instead of escaping externally. INDEX ABDOMEN, 323 Regions of, 323 Abdominal Brain, 240 Cavity, 323 Openings of, 324 Rings, 385, 386 Acervulus Cerebri, 194 Acetabulum, 12 Achillis, Tendo, 113 Adenology, i Ala Cinerea, 212 Ala Lobuli Centralis, 207 Alcock's Canal, 392 Alveoli, 3, 29, 33 of Lungs, 359 of Mammary Gland, 384 Amphiarthrosis, 59 Ampulla of Fallopian Tube, 382 of Milk Ducts, 384 of Semicircular Canals, 306 of Tubae Uterinae, 382 Amygdala, 207, 3M Anastomosis, 145 Circumpatellar, 146 Crucial, 146 Elbow, 145 Hip, 145 Knee, 146 Shoulder, 145 Stirrup, 145 Tonsillar, 314 of Willis, 128, 151 Anatomy, i Angiology, i Angle, Filtration, 287 of Iris, 287 of Jaw, 35 Ankle-joint, 71 Annulus, Ciliaris, 146 Femoralis, 389 Fibrosus Sinister, 121 Inguinalis Abdominalis, 385 Subcutaneous, 386 Ovalis, 119 Anterior Extension (ischio-rectal fossa), 393 Anti-helix, 297 Anti-tragus, 297 Antrum of Highmore, 27 Mastoideum, 301 Tympanicum, 301 Anus, 335 Aorta. 123 Abdominal, 137. 156 Arch of, 123, 449 Thoracic, 136, 154 Aortic Bodies, 345 Apertura Pyraformis, 44 Apertures in Abdominal Wall, 324 Apex Capituli, 55 Appendices Epiploicae, 328, 335 Testis. 373 Appendix Auriculae, 119 Ensiform, 8 Ventriculae, 354 Vermiform, 334 Xiphoid, 8 Aponeuroses, 74 Aponeurosis, Pharyngeal, 322 Vertebral, 90 Apophysis, 3 Aquaeduct of Sylvius, 202 Aquaeductus Cerebri, 202 Cochleae, 21, 43, 306 Fallopii, 220, 225 Vestibuli, 21, 42, 305 Arachnoid of Brain, 181 of Cord, 213 Granulations, 181, 182 Arbor Vitae, 208, 380 Arch, Carpal, 135 Crural, 387, 39O Glosso-palatine, 314 Lumbo-costal, 107 Palmar, 135 Pharyngo-palatine, 314 Plantar, 145 Superciliary, 14 Volar, 135 Arcuate Fibres, Cerebellar, 208 Medullary, 210 Area Cribrosa, 311 n. Facialis, 311 Vestibularis, 311 Areola Mammae, 384 Arm, 47 Arnold's Ganglion, 224 Nerve, 221, 250 Arterias Cavernosae, 127 Propriae Renales, 362 Receptaculi, 127 Arterial Anastomoses, 145 System Tabulated, 147 Arteriolae Rectae, 362 Artery or Arteries, 122, 147 Acromio-trmracic, 132, 153 Alar-thoracic, 132, 153 Alveolar, Inferior, 126, 150 Superior, 126, 150 Anastomoses of, 145 Anastomotica Magna (arm) , 133. 1 53 (thigh), 142, 1 60 399 400 INDEX Artery, Angular, 125, 148 of Ankle-joint, 71 Anonyma, 124, 148 Antero-lateral Ganglionic, 127, 151 Antero-medial Ganglionic, 127, 151 Aorta, 123 Abdominal, 137, 156 Arch of, 123, 148 Thoracic, 136, 154 Arch, Palmar (volar), Deep, 136, 153 Superficial, 135, 154 Plantar, 145, 162 Arcuata, 144, 162 Ascending Pharyngeal, 125, 150 of Auditory Canal, 298 Auditory, Internal, 312 of Auricle, 298 Auricular, 125, 148 Anterior, 126, 150 Deep, 126, 150 Posterior, 125, 150 Axillary, 132, 153 Axis, Coeliac, 137, 156 Thyroid, 131, 152 Azygos of Knee, 143, 162 of Vagina, 139, 379 Basal, 127 Basilar, 131, 151, 152 of Bladder, 368 Brachial, 133, 136, 153 of Brain, Cortical, 128 of Bones, 4 Bronchial, 136, 154, 356 Buccal, 126, 150 Bulbar, 131, 152 Bulbi Urethras, 140, 158 Calcanean, 144, 162 Canalis Pterygoidea, 126, 150 Carotid, Common, 124, 148, 150 External, 125, 148, 150 Internal, 126, 151 Carotico-tympanic, 127, 151 Carpal, Arch, Anterior, 135 Posterior, 135 Radial, Anterior, 133, 153 Posterior, 134, 153 Ulnar, Anterior, 135, 154 Posterior, 135, 154 Cavernosae, 127, 151 Centralis Retinas, 127, 289 Cerebellar, Anterior-inferior, 131, 152 Posterior-inferior, 131, 152 Superior, 131, 152 Cerebral, Anterior, 127, 151 Middle, 127, 151 Posterior, 128, 152 Cervical, Ascending, 131, 152 Deep, from Sup. Intercostal, 132 Superficial, 131, 152 Transverse, 131, 152 Choroid, Anterior, 128, 151, 283 Posterior, 128, 152 Ciliary, Anterior, 127, 290 Long, 127, 290 Short, 127, 290 Circle of Willis, 128, 151 Artery, Circulus Major and Minor, 285 Circumflex, Femoral, Lateral, 142, 160 Medial, 142, 160 Humeral, Anterior, 133, 153 Posterior, 133, 153 Iliac, Deep, 141, 160 Superficial, 141, 160 Scapulae, 132, 153 Coccygeal, 140, 158 Cochlear, 312 Coeliac Axis, 137, 156 Colic, Left (sinistra), 138, 156 Middle (media), 138, 156 Right (dextra), 138, 156 Comes Nervi Ischiadici, 140, 158 Phrenici, 132, 152 Communicating, Cerebral, Ante- rior, 127, 152 Posterior, 127, 151 of Palmar Arches, 135, 154 of Plantar Arch, 144, 162 Coronary, of Heart, 123, 148 of Lips, 125, 148 of Corpus Cavernosum, 130, 158 Cortical System of Brain, 128 Cremasteric, 141, 160 Cricq-thyro'd, 125, 148 Cystic, 138, 156 Dental, Inferior, 126, 150 Superior, 126, 150 Digital, Palmar Collateral, 135, 154 Plantar Collateral, 145, 162 Dorsalis Clitoridis, 140, 158 Hallucis, 144, 162 Indicis, 134, 153 Linguae, 125, 148 Nasi, 127, 151 Pedis, 143, 162 Penis, 140, 158 Pollicis, 134, 153 Scapulae, 132, 153 of Ear, 301, 312 of Elbow, 66, 145 Epigastric, Deep, 140, 160 Inferior, 140, 160 Superficial, 141, 160 Superior, 132, 152 Ethmoidal, Anterior, 127, 151 Posterior, 127, 151 of Eustachian Tube, 304 of Eye, 289 Facial, Deep, 126, 151 Superficial, 125, 148 Transverse, 126, 150 Femoral, Common, 141 Deep (profounda), 142, 160 Superficial, 141, 160 Fibular, 144, 162 of Foot, 143, 144 of Forearm, 133, 153 Frontal, from Ant. Cerebral, 127, 151 Mid. Cerebral, 127, 151 Ophthalmic, 127, 151 Temporal, 126, 150 Ganglionic, Antero-lateral, 127, 151 Postero-lateral, 128, 152 Antero-medial, 127,151 INDEX 4OI Artery, Ganglionic, Postero-medial, 128, 152 System of Brain, 128 Gastric, 137, 150 Gastric, Left, 137, 156 Right, 137, 156 Gastricae Breves, 138, 156 Gastro-duodenal, 137, 156 Gastrp-epiploica Dextra, 137, 156 Sinistra, 138, 156 Genu Suprema, 142, 160 Gluteal, Inferior, 140, 158 Superior, 140, 160 Haemprrhoidal, Inferior, 140, 158 Middle, 139, 158 Superior, 138, 156 of Hand, 135 of Head, 124 of Heart, 119 Helicine, 371 Hepatic, 137, 138, 158, 340 Left, 138, 156 Right, 138, 156 of Hip-joint, 68, 145 Hyoid, from Lingual, 125, 148 from Superior Thyroid, 125, 148 Hypogastric, 139, 158, 160 Ileo-colic, 138, 156 Iliac, Circumflex, Deep, 141, 160 Superficial, 141, 160 Common, 139 External, 140, 160 Internal, 139, 158, 160 Ilio-lumbar, 140, 160 Incisor, 126, 150 Infra-orbital, 126, 150 Innominate, 124, 148 Intercostal, 136, 154 Anterior, 132, 152 Perforating, 132, 152 Superior, 132 Intercostalis Suprema, 132 Internal Auditory, 312 Interosseous, Common, 134 of Foot, 144, 162 of Forearm, 134, 154 of Hand, 134, 152 Ulnar, 134, 154 Intestines, 333, 336 Intestini Tenuis, 138, 156 of Iris, 285 of Kidney, 364 of Knee, 69, 143, 145, 162 Labial, Coronary, 125, 148 Inferior, 125, 148 Labiales, 125 of Labyrinth, 312 Lacrimal, 127, 151 Laryngeal, Inferior, 131, 152 Superior, 125, 148 of Larynx, 354 Lateralis Nasi, 125, 148 Lenticulo-striate (ant.-lat. gang- lionic), 127 Lienal, 138, 156 Lingual, 125, 148 Dorsal, 125, 148 of Liver, 341 20 Artery, of Lower Extremity, 141 Lumbar, 138, 156, 160 of Lungs, 359 Magna, 153 Malleolar, Lateral, 143 Medial, 143 Mammary, External, 132 Internal, 131, 152 of Mammary Gland, 384 Mandibular (inf. dental), 126, 150 Masseteric, 126, 150 Mastoid, 125, 150 Maxillary, External, 125, 148 Internal, 126, 150 Median, 134 Mediastinal, 132, 152 Posterior, 136, 154 of Membrana Tympani, 299 Meningeal, Anterior, 127, 151 Middle, 126, 150 from Occipital, 125, 148 from Pharyngeal, 125, 150 Posterior, 131, 152 Small, 126, 150 from Vertebral, 131, 152 Mental, 126, 150 Mesenteric, Inferior, 138, 156 Superior, 138, 156 Metacarpal, 134, 153 Metatarsal, 144, 162 Musculo-phrenic, 132, 152 Mylo-hyoid, 126, 150 Nasal, Dorsal, 127, 151 Lateral, 125, 148 from Ophthalmic, 127, 151 of Nasal Fossae, 279 of Neck, 124 of Nose, 279 Nutrient of Clavicle, 131, 152 of Femur, 142, 160 of Fibula, 144, 162 of Humerus, 133, 153 of Tibia, 144, 162 Obturator, 139, 158, 389 Occipital, 125, 148 CEsophageal, 131, 136, 152, 154 of (Esophagus, 323 Ophthalmic, 127, 151 Orbital, 127, 151 Ovarian, 138, 156 of Ovaries, 383 Palatine, Ascending, 125, 148 Descending, 126, 150 Inferior, 125, 148 Posterior, 126, 150 Palmar (volar) Arch, Deep, 136 Superficial, 135 Recurrent, 134, 153 Palpebral, 127, 151 of Pancreas, 344 Pancreaticae magnae, 138 Parvae, 138 Pancreatico-duodenal, Inferior, 138, 156 Superior, 137, 156 Parietal, 126, 151 Parieto- temporal, 127. 151 of Parotid Gland, 126, 316 402 INDEX Artery, of Pelvis, 139 of Penis, 372 Perforating, Anterior Intercostal, 132, 152 of Foot, 145, 162 of Hand, 134, 153 of Thigh, 142, 1 60 Pericardiac, 132, 152 Pericardia!, 136, 15,1 Pericardio-phrenic, 132 of Pericardium, 118 Perinaeal, Superficial, 140, 158 Transverse, 140, 158 of Perineum, 140 Peroneal (fibular), 144, 162 Pharyngeal, 125, 126, 150 Ascending, 125, 150 of Pharynx, 322 of Pia Mater, 182 Plantar, Lateral, 144, 162 Medial, 14.4, 162 Popliteal, 143, 162 Postero-lateral Ganglionic, 128, 152 Postero-medial Ganglionic, 128, 152 Prevertebral, 125, 150 Princeps Cervicis, 125, 148 Polhcis, 134, 153 Profunda Brachii, 133, 153 Cervicis, 132 Femqris, 142, 160 Inferior (arm), 133, 153 Penis, 140, 158 Superior (arm), 133, 153 of Prostate Gland, 370 Pterygoid, 126, 150 Pterygo-palatine, 126, 150 Pubic, 141, 160 Pudendal, 139, 158 Pubic, External, Deep, 142, 160 Superficial, 141, 160 Internal, 139, 158 Pulnumary, 122, 147 Pyloric, 137, 156 Radial, 133, 153 Radialis Indicis, 134, 153 Radial Recurrent, 133, 153 Ranine, 125, 148 Receptaculi, 127, 151 Recurrent, Palmar (volar), 134,153 Radial, 133, 153 Tibial, Anterior, 144, 162 Posterior, 144, 162 Ulnar, Anterior, 134, 154 Posterior, 134, 154 Volar (palmar), 134, 153 Renal, 138, 156 Rete Carpi Dorsale, 135 Volare, 135 of Retina, 286 Sacral, Lateral, 140, 160 Middle, 138, 156 Scapular, Circumflex. 132, 153 Dorsal, 132, 153 Posterior, 131, 152 Transverse, 131 Sciatic, 140, 158 of Shoulder-joint, 65, 145 Sigmoid, 138, 156 Artery, Spermatic, 138, 156 of Spermatic Cord, 377 Spheno-maxillary, 126, 150 Spheno-palatine, 126, 150 Spinal, Anterior, 131, 152 Lateral, 131, 152 Posterior, 131, 152 of Spleen, 349 Splenic, 138, 156 Sternal, 132, 152 Sterno-mastoid, 125, 148 of Stomach, 330 Stylo-mastoid, 125, 150 Subclavian, 130 Subcostal, 136 Sublingual, 125, i/>8 Submandibular, 125, 148 Submental, 125, 148 Subscapular, 132, 153 Superficialis Volas, 133, 153 Supra-orbital, 127, 151 Supra-renal, 138, 156 of Supra-renal Gland, 365 Supra-scapular, 131, 152 Sural, 143 Tables of the Arterial System, 147 Tarsal, 144 Temporal, Deep, Anterior, 126, 150 Posterior, 126, 150 Middle, 126, 150 Superficial, 126, 150 of Testicle, 375 of Thigh, 141, 1 60 Thoracalis Lateralis, 132 Suprema, 132 Thoracic, Acromio, 132, 153 Alar, 132, 153 Axis, 131, 153 Long, 132, 153 Superior, 132, 153 Thoraco-acromial, 132 of Thymus Gland, 346 Thyroid. Axis, 131 Inferior, 131, 152 Superior, 125, 148 of Thyroid Gland, 346 Thyroidea Ima, 124 Tibial, Anterior, 143, 16^ Posterior, 144, 162 Recurrent, Anterior, 143, 162 Posterior, 143, 162 of Tongue, 275 Tonsillar, 125, 148 True, 314 of Tonsils, 314 of Trachea, 356 Tracheal, 131, 152 Transversalis Colli, 131, 152 Scapulae, 131 True Tonsillar, 314 Truncus Thyreo-cervicalis, 131 of Trunk, 136 Tympanic from Ascending Pharyngeal, 125, 150 from Internal Carotid, 127, 151 Maxillary, 126, 150 of Tympanic membrane, 299 of Tympanum, 302 INDEX 403 Artery, Ulnar, 134, IS4 Carpal, 134, 154 Collateral, 133 Interosseous, 134 Recurrent, Anterior, 134, 154 Posterior, 134, 154 of Upper Extremity, 130 Urethral, 140 Uterine, 139, 158 of Uterus, 382 of Vagina, 379 Vaginal, 139, 158 Vasa Brevia, 138, 156 Intestinales, 138 Intestini Tenuis, 138, 156 Vasorum, 122 of Vas Deferens, 139, 158 Vertebral, 131, 152 Vesical, Inferior, 139, 158 Middle, 139, 158 Superior, 139, 158 of Vesiculae Seminales, 377 Vidian, 126, 150 Volar, Superficial, 133, 153 Willis, Circle of, 128, 251 Zygomatico-orbital, 126 Arthrodial joints, 59 Articulations, 59 Acromio-clavicular, 65 Ankle, 71 Astragalo-navicular, 72 Atlanto-axial, 58 Atlanto-epistrophica, 61 Calcaneo-astragaloid, 72 Calcaneo-cuboid, 72 Calcaneo-navicular, 72 Carpal, 50, 67 Carpo-metacarpal, 68 Chondro-sternal, 62 Costo-chrondal, 62 Costo-transverse, 62 Costo-vertebral, 62 Elbow, 66 Hip, 68 Intercarpal, 67 Interchondral, 62 Knee, 69 Metacarpo-metacarpal, 68 Metatarso-metatarsal, 73 Motion in, 60 Occipito-atlantal, 62 Occipito-axial, 62 Phalangeal of Foot, 73 of Hand, 68 Pubic, 64 Radio-carpal, 67 Radio-ulnar, 66 Sacro-C9ccygeal, 63 Sacro-iliac, 64 Sacro-ischiatic, 64 Sacro- vertebral, 63 Scapulo-clavicular, 65 Shoulder, 65 Sterno-clavicular, 64 Structure of, 60 Tarsal, 57, 72 Tarso-metatarsal, 72 Ternporo-mandibular, 6q Articulations, Tibio-fibular, 71 of the Trunk, 60 Vertebral, 61 Arytenoid Cartilages, 351 Astragalus (talus), 57 Atic, 300 Atlas, 6 Atrium Meatus Medii Nasi, 278 Tympani, 300 Auricle of Ear, 297 of Heart, 119 Auris Externa, 296 Interna, 304 Media, 300 Axis, 7 Caeliac, 137, 156 Thyroid, 131, 152 Axis-cylinders, 177 Axones, 177 Azygos, 3 BAND, Bellinger's, 285 Naso-labial, 78 Bartholin, Duct of, 317 Glands of, 378 Basal Ganglia, 179 Base of the Brain, 186 , of the Skull, 41 Basi-hyal, 41 Basis Pedunculi Cerebri, 195 Bauhin, Valve of, 334 Bell, Sir Charles, Nerve of, 229, 256 Bertin, Columns of, 361 Bladder, Gall, 193 - *J f J Urinary, 365 Blandin, Glands, of, 274 Blastema, 4 Blood- vascular System, 118 Body or Bodies, Aortic, 345 Carotid, 345 Chromaphil, 345 Ciliary, 283 Coccygeal, 349 Gemculate, 193 Malpighian, 349, 361 Mammillary, 188 Olivary, 209 Perinseal, 395 Pineal, 194 Pituitary, 186 Quadrigeminal, 202 Restiform, 207, 209 Vitreous, 287 Wolffian, 383 Bone or Bones, i Astragalus (talus), 57 Atlas, 6 Axis (epistropheus), 6 Calcaneus, 57 Cancellous Bones, 2 Capitate (Magnum), 51 Cavities of, 3 Clavicle, 45 Classification of, i Coccyx, ii Composition of, 3 Costae, 8 Coxae or Coxal , 1 1 404 INDEX Bones, Cuboid, 57 Cuneiform (carpal), 51 (tarsal), 57 Eminences of, 3 Enumeration of, i Epistrqpheus (axis), 6 Ethmoid, 26 Femur, 52 Fibula, 55 Flat Bones, 2 Frontal, 14 Hamate (unciform), 51 Histology of Bone, 3 Humerus, 47 Hyoid, 41 Ilium, 13 Incus, 301 Innominate (coxal), II Irregular Bones, 2 Ischmm, 13 Lacrimal, 29 Long Bones, i Lunate (Semilunar), 51 Malar, 30 Malleus, 301 Mandible, 33 Marrow of Bones, 4 Maxilla, 27 Medullated Bones, i Metacarpals, 51 Metatarsals, 58 Multangular, Great, 51 Small, 51 Nasal, 27 Navicular (carpal), 51 (tarsal), 57 Occipital, 17 Orbicular, 301 Os Calcis, 57 Os Capitatum, 51 Os Coccygis, 1 1 Os Coxae, n Os Hamatum, 51 Os Innominatum, n Os Lunatum, 51 Os Magnum, 51 Os Multangulum Majus, 51 Minus, 51 Os Nayiculare, 51 Os Orbiculare, 301 Os Triquetrum, 51 Ossa Suturarum, 40 Ossification of Bones, 4 Palate, 31 Parietal, 16 Patella, 54 Pectineal, 14 Peroneal, 55 Petro-mastoid, 19 Phalanges of Foot, 58 of Hand, 52 Pisiform, 51 Prominences of Bones, 3 Pubic, 14 Radius, 49 Ribs (costse), 18 Sacral, 10 Scaphoid (carpal), 51 Bones, Scaphoid (tarsal), 57 Scapula, 45 Semilunar, 51 Sesamoid, 3 Short Bones, i Squamous, 19 Stapes, 301 Sternum, 8 Structure of Bone, 4 Talus, 57 Temporal, 19 Tibia, 54 Trapezium, 51 Trapezoid, 51 Triquetral (cuneiform), 51 Turbinal, 32 Tympanic, 19 Ulna, 48 Unciform, 51 Unclassified Bones, 3 Vertebrae, 5 Vomer, 33 Wormian, 3, AO Zygomatic, 30 Bowman's Capsule, 361 Glands, 279 Muscle (ciliary), 284 (cochlear), 309 Brachia Conjunctiva, 201, 207 Pontis, 204, 207 Brain, 178 Abdominal, 240 Basal Ganglia of, 179 Cerebellum, 206 Cerebrum, 183 Convolutions of, 185 Cortex of, 179 Development of, 178 Diencephalon, 178 Divisions of, 178, 182 Fissures of, 184 Gray Matter of, 179 Hind-brain, 203 Hypophysis Cerebri. 186 Island of Reil, 183 Isthmus Cerebri, 194 Isthmus Rhombencephali, 178, 203 Lobes of, 183 Medulla Oblongata, 208 Meninges of, 180 Mesencephalon, 178, 194 Metencephalon, 178, 203 Mid-brain, 178, 194 Myelencephalon, 178, 208 Points on Under Surface, 186 Pons Varolii, 203 Prosencephalon, 178 Rhombencephalon, 192 Telencephalon, 178 Thalamencephalon, 192 Under Surface of, 186 Weight of Average Brain, 182 White Matter of, 179 Ventricles of, 189 Vesicles of, 178 Breasts, 383 Broca's Area or Convolution, 185 Bronchi, 355 INDEX 405 Bruch's Membrane, 283 Brunner's Glands, 333 Buccae, 312 Buck's Fascia, 393 Buds, Taste, 274 Bulb of Corpus Spongiosum, 372 Olfactory, 183 Spinal, 208 Urethra], 369 Bulbus Oculi, 280 Vestibuli, 378 Bulla Ethmoidalis, 277 Bundle, Ground, 215 Posterior Longitudinal, 200 Burns' Ligament, 390 Bursa Omentalis, 325 Pharyngea, 321 Bursae of Knee-joint, 71 Calamus Scriptorius, 211 Calcaneus, 57 Calcar Avis, 191 Calcar Femorale, 53 Calices of Kidney, 361 Cameras Oculi, 287 Camper's Fascia, 108, 385 Canal, or Canalis, Adductor, no, 142 Alcock's, 392 Alimentary, 312 Anal, 335 of Arnold's Nerve, 21 Carotid, 20 Central of the Cord, 214 Centralis Modioli, 306 Cervicis Uteri, 380 Condyloideus Posterior, 18 Crural, 388 Dental, 27 Facial, 220, 225 Femoral, 388 Haversian, 4 of Huguier, 19 Hunter's, no, 142 Hyaloid, 288 Hypoglossi, 1 8 Infra-orbital, 28 Inguinal, 385 of Jacobson's Nerve, 21 Lacrimal, 295 of Laxator Tympani, 19, 43 Malar, 30, 36 Mandibular, 34 of the Modiolus, 306 of Nuck, 381 Palatine, 28 Petit's, 288, 289 Pharyngeal, 32 Pterygoideus, 25 Ptery go-palatine, 28 Reuniens, 307, 308 Sacral, n of Schlemm, 282 Semicircular, 305, 308 Spheno-palatine, 32 Spiral of Cochlea, 306 Stilling's, 288 for Tensor Tympani, 301 Canal, Vidian, 25 Zygomatico-facial, 30, 36 Zygomatico-temporal, 36 Canaliculi Dentales, 319 Lacrimal, 295 Canthus (eye), 293 Capillaries, Biliary, 340 Blood, 122 Capitellum Humeri, 48 Capsule or Capsula, Bowman's, 361 External, 192 of Glisson, 340 Glomeruli, 361 Internal, 192 Lentis, 288 Tenon's, 280 Supra-renal, 364 Caput Gallinaginis, 368 Cardia, 329 Carpus, 50 Cartilage or Cartilage, 60 Arytenoid, 351 Corniculata, 352 Cricoid, 351 Cuneiform, 352 Epiglottica, 352 of Larynx, 350 Santorini's, 352 Thyroid, 350 Triticea, 353 Varieties of, 60 Wrisberg's, 352 Carunculae Humenales, 378 Lacrimal, 295 Myrtiformes, 378 Cauda Equina, 216 Cavity or Cavum Abdominal, 323 Acetabular, 12 Cotyloid, 12 Dentis, 318 Glenoid, 47 Omental, 325 Oris, 312 Pelvic, 391 Peritonaei, 325 Pulp, 318 Septi Pellucidi, 191 Sigmoid of Radius, 50 of Ulna, 49 Subarachnoidalis, 181 Subdurale, 181 Tympanic, 300 Uteri, 380 Cells, Air, 359 Auditory, 310 Claudius', 310 Deiters', 310 . Ethmoidal, 26 Golgi's, 176, 208 Hair, 307, 310 Hensen's, 310 Hepatic, 340 Mastoid, 20 Nerve, 176 Olfactory, 278 Purkinje's, 176, 208 Reticular, 349 406 INDEX Cells, Sustentacular, 349 Cement, 319 Cerato-hyal, 41 Cerebellum, 206 (see Brain) Cerebro-spinal System, 175 Cerebrum, 179 (see Brain) Cervic Penis, 372 Cervix Uteri, 380 Chambers (camerae) of the Eye, 287 Chiasm, Optic, 292 Chorda Tympani, 220, 248, 276 Chordae Tendinae, 120 Choroid, 283 Plexus, 190, 211 Chromaffin System, 344 Chromaphil System, 344 Cilia, 293 Ciliary Body, 283 Cingulum, 180 Circle of Willis, 128, 151 Circulation, Collateral, 146 Circulus Major of Iris, 285 Minor of Iris, 285 Venosus, 384 Cisterna Chyli, 172 Cerebello-medullaris (magna), 182 Inter-peduncularis, 182 Magna (cerebello-medullaris) , 182 Clarke's Column, 210, 216 Claudius' Cells, 310 Claustrum, 192 Clava, 198 Clavicle, 45 Clinoid, 3 Clitoris, 378 Clivus Monticuli, 207 Cloquet's Fascia, 389 Coccygis, ii Coccyx, ii Cochlea, 306, 309 Collar-bone, 45 Collateral Circulation, 146 Colics' Fascia, 392 Colliculi (quadrigemina), 202 Colliculus Nervi Facialis, 212 Optici, 286 Semmalis, 368 Colloid, 346 Collum Glandis, 372 Colon, 334 Column or Columns Antero-lateral of Cord, 214 Bertin's, 361 Burdach's, 198, 210, 215 Clarke's, 210, 216 Coil's, 198, 210, 215 Lateral of Medulla, 209 Posterior of Cord, 214 Vesicular (Clarke's), 216 Postero-lateral of Cord, 214 Postero-median of Cord, 214 of Spinal Cord, 213 of Vagina, 379 Columnae Carneae, 120, 122 Rugarum, 379 Commissura or Commissure Anterior (yhite) of 3d Ventricle, 192 Commissura, Gray (middle) of 3d Ven- tricle, 193 Gudden's, 194, 292 Labiorum Pudendi, 377 Meynert's, 292 Middle (gray) of 3d Ventricle, 193 Optic, 1 86, 292 Palpebrarum, 293 Posterior (white) of 3d Ventricle, 193 Concha or Conchae Auriculas, 297 Nasalis, 26, 32 Sphenoidal, 24 Conductor Sonorus, 212 Condyle, 3 Condyloid Articulations, 59 Confluens Sinuum, 165 Coni Vasculosi, 374 Conjoined Tendon, 95 Conus Arteriosus, 120 Elasticus, 353 Convolution of Broca, 185 Convolutions of the Cerebrum, 185 Cooper's (Sir Astley) Fascia, 390 Cor, 118 Coracoid, 3 Cord, Gangliated, 237 Spermatic, 376 Spinal, 213 .Vocal, 353 Conum, 270, 271 Cornea, 282 Cornicula Laryngis, 352 Cornua of Hyoid, 41 Uteri, 380 Ventricular, 190 Corona Glandis, 372 Radata, 196 Coronoid, 3 Corpora Albicantia, 188 Amylacea, 194 Cavernosa, 371 Geniculata, 193 Mammillaria (albicantia), 188 Quadrigemina (colliculi), 202 Restiformes, 207, 209 Corpus Albicans, 383 Callosum, 190 Cayernosum Urethras, 371 Ciliare, 283 Dentatum, 209 Fimbriatum, 190, 191 Highmorianum, 374 Luteum, 383 Mammae, 384 Medullare, 206 Pineale, 194 Striatum, 191 Trapezoideum, 204 Uteri, 380 . Vitreum, 287 Corpuscles, Cprneal, 282 Ganglionic, 176 Pacinian, 272 Tactile, 272 Cortex, Cerebellar, 208 Cerebral, 179 Renal, 361 INDEX 407 Corti, Organ of, 309 Cortical System, 345 Costae (ribs), 8 Cotyloid. 3 Cavity, 12 Notch, 12 Coverings of Brain, 180 of Femoral Hernia, 390 of Inguinal Hernia, 388 of Testicles, 373 of Spinal Cord, 213 Cowper's Glands, 371 Coxal or Hip-bone, n Crest, Conchal, 27, 31 of Ilium, 13 Infra-temporal, 24 Inter-trochanteric, 53 Nasal, 29 Nuchal, 17 of Pubis, 17 Sphenoidal, 23 Tibial, 55 Turbinal, 27, 31 Cribriform Fascia, 108, 390 Plate, 26 Cricoid Cartilage, 351 Crista Falciformis, 311 Galli, 26 Transversa, 311 Urethrae, 368 Vestibuli, 305 Crucial Anastomosis, 146 Ridge, 1 8 Crura of Abdominal Ring, 386 Cerebri, 195 Clitoridis, 378 of Diaphragm, 95 of Penis, 371 Crus Commune, 306 Crusta Cerebri, 195 Petrosa, 319 Crypts, of Lieberkuhn, 332 Cuboid, 57 Culmen Monticuli, 207 Cuneus, 186 Cupola Cochleae, 306 Cushion, Pharyngeal, 321 Cuticle, 268 Cuticuta Dentis, 319 Cutis Vera, 270 DARTOS, 373 Darwin's Tubercle, 297 Decussation, Inferior Pyramidal, 209 Motor, 209 Sensory, 198 Superior Pyramidal, 198 Deiter's Cells, 310 Dendrites, 177 Dentes, 317 Dentine, 318 Derma, 270 Dermatology, I Descemet's Membrane, 282 Diaphragm, 94 Urogenital, 393 Diaphragma Sellae, 181 Diaphysis, 9 Diarthrosis, 59 Diclive, 207 Diencephalon, 178, 192 Discus Proligerus, 383 Disk, Intervertebral, 61 Optic, 286 Diverticulum Ilei, 331 Meckel's, 331 Dollinger's Band, 285 Dorsum Sellae, 23 Douglas' Pouch, 327 Semilunar Fold, 96 Drum of the Ear, 300 Drum-head, 298 Duct, Ducts, or Ductus Aberrans, 373 Arteriosus, 123 Bartholin's, 317 Biliary, 342 Cochlearis, 307 Communis Choledochus, 342 Cowper's, 368 Cystic, 343 Deferens, 375 Ejaculatory, 368, 376 Endo-lymphaticus, 308 Gartner's, 383 Hepatic, 342 Lactiferi, 384 Lymphatic, 172 Lymphaticus Dexter, 172 Nasal, 28, 296 Naso-lacrimal, 296 Pancreatic, 344 Parotideus, 316 Prostatic, 370 Rivinius", 316 Santorini's, 344 Semicirculares, 307, 308 Stenson's, 316 Sublinguales Minores, 316 Sublingualis, 316 Submaxillaris, 316 Thoracic, 172 Wharton's, 316 Wirsung's, 344 Utriculo-saccularis, 308 Ductless Glands, 344 Duodenum, 331 Dural Sinuses, 164, 165 Dura Mater Cerebri, 180 Spinalis, 213 EAR, 296 External, 297 Internal, 304 Middle, 300 Elbow-joint, 66 Eleidin, 270 Eminence, Frontal, 14 Hypothenar, 106 Malleolar, 298 Nasal, 14 Eminence Parietal, 16 Pectineal, 14 Thenar, 196 Eminentia Articularis, 19 Cinprea . v i INDEX Eminentia Collateralis, 191 Inter-cpndyloidea, 54 Pyramidalis, 301 Saccularis, 186 Teres, 212 Enamel, 319 Enarthrosis, 59 End-bulbs of Krause, 177, 272 Endocardium, 118 Endolymph, 304 Endomysmm, 74 Endoneurium, 177 End-organs of Nerves, 177 Endosteum, 4 Ensiform (xyphoid), 8 Epidermis, 270 Epididymis, 373 Epigastric Region, 324 Epiglottis, 352 Epineurium, 177 Epiphysis, 3 Cerebri, 194 Epistropheus (axis), 6, 7 Equilibration, Organ of, 309 Ethmoid, 26 Eustachian Tube, 303 Eye, 280 Eyebrows, 293 Eyelashes, 293 Eyelids, 293 Eye-socket (orbit), 35 Excavatio Papillae Nervi Optici, 286 Recto-uterina, 327 Recto- vesicalis, 327 Vesico-uterina, 327 Extension, Anterior of Ischio-rectal Fossa, 394 FACET, 3 Fallopian Tubes, 382 Fallopius, Aquseduct of, 220, 225 Hiatus of, 20 Falciform Process, 390 Falx Aponeurotica Inguinalis, 95 Cerebelli, 181 Cerebri, 181 Fascia, Anal, 392 Bicipital, 133 Buck's, 393 Bulbi Oculi, 280 Camper's, 108, 385 Cloquet's, 389 Colles', 392 Cooper's, 390 Cremasteric, 386 Cribriform, 108, 390 Deep, 74 Dentate, 191 Diaphragmatis Urogenitalis, 393 Dorsal, 90 Infundibuliform, 385 Iliac, 107 Intercolumnar, 386 Ischio-rectal, 392 Lata, 1 08, 199 Lumbar, 90 Fascia, Lumbo-dorsal, 90 Naso-labial Band, 78 Obturator, 391 Palmar, 105 Parotid, 315 Parotideo-masseteric, 315 Pelvic, 391 Perinaeal, Deep, 393 Superficial, 392 Pharyngo-basilar, 322 Plantar, 115 Recto- vesical, 391 Scarpa's, 108, 390 Spermatic, 386 Superficial, 74 Trartsversalis, 107, 390 Triangular, 387 Fasciae, 74 of the Back, 90 of the Foot, 115 of the Hand, 105 of the Pelvis, 391 of the Perinaeum, 392 of the Thigh, 108 Fasciculus, see also Tract Anterior Cerebro-soplina, 96, 214 Cerebello-olivary, 211 Cerebro-spinalis Anterior, 196, 214 Lateralis, 196, 214 Crossed Pyramidal, 196, 214 Cuneatus (Burdach's), 198, 210, 215 Direct Cerebellar, 210 Direct Pyramidal, 196, 214 Dorsal Spino-cerebellar, 210 Fillet, 198 Flechsig's, 210 Geniculate, 196 Geniculate, 196 Gower's, 205 Gracilis (Coil's column), 198, 210, 215 Inferior Longitudinal, 180 Lateral Cerebro-spinal, 196, 214 Lemniscus, 199 Lemniscus, (fillet), 198 Medial Lemniscus, 198 Longitudinal, 200 Meynert's, 292 Olivary, 202 Olivo-cerebellar, 210 Perpendicular, 180 Posterp-lateral, 215 Proprii, 215 Proprius Anterior, 215 Dorsalis, 215 Posterior, 215 Ventralis, 215 Retroflexus (Meynert's), 29 Rolando's, 209 Rubro-Spinal, 201 Solitary, 211, 221 Spino-cerebellar, Anterior, 205, 210, 214 Dorsal, 210, 215 Sulco-marginal, 199 Superficial Ventro-lateral (Gower's) 295, 206 Superior Longitudinal, 180 INDEX 409 Fasciculus, Teres, 205 Tri-neural, 211 Tiirck's, 196 Uncinate, 180 Ventral Cerebro-spinal, 196 Longitudinal, 199 Fauces, 314 Femur, 52 Fenestra Cochleae, 21, 300 Ovalis, 300 Rotunda, 300 Vestibuli, 21, 300 Ferrein's Pyramids, 362 Fibrae Propriae, 207 Fibres, Arcuate of Cerebellum, 208 of Medulla, 210 Association, 180 Commissural, 180 Medullated, 17? Miiller's, 286 Nerve, 177 Non-medullated, 177 Peduncular, 179, 207 Projection, 179, 192 Transverse, 180 Fibro-cartilage, 60, 70 Fibula, 55 Fillet, Lateral, 199 Medial, 198 Filum Terminale, 213 Fimbria Ovarica. 382 Fimbriae Tubae Uterinas, 382 Fissure, Auricular, 21, 43 Ethmoidal, 41 Glaserian, 19, 43 Orbital, 25, 36, 39, 41 Palpebral, 293 Pterygo-maxillary, 39 Rolando's, 184 Sphenoidal, 25, 36, 41 Spheno-maxillary, 37, 39 Squamo-tympanic, 44 Sylvius', 184 Fissures of Cerebellum, 206 of Cerebrum, 184 of Liver, 337 of Spinal Cord, 213 Flexure, Sigmoid, 334 Flocculus, 207 Fluid. Cerebro-spinal, 182 Fold, Aryteno-epiglottidean, 352 Glosso-epiglottidean, 353 Palpebral, 295 Semilunar, 295 of Douglas, 96 Folium Cacuminis, 207 Folliciles, Hair, 271 Simple, 332, 335 Folliculi Oophori Vesiculosi, 383 Fontana's Spaces, 282 Fontanelles, 40 Foot, 56 Foramen for Arnold's Nerve, 21, 43 Caecum, 15, 43, 274 Carotid, 43 Condylar, 18, 42 Costo-transverse, 6 Epiploicum, 326 Foramen for Ethmoidal, 16, 37, 41 Incisive, 29, 42 Infraorbital, 28 Interventricular, 190 Intervertebral, 5 for Jacobson Nerve, 21, 43 Jugular, 42 of Ke [ey and Retzius, 211 Lacerum Anterius, 25, 36, 41 Medium, 41 Posterius, 17, 42 Magendie's, 182, 211 Magnum, 17, 42 Mandibular, 34 Mastoid, 20, 42 Mental, 31 Munro's, 190 Obturator, 12 Olfactory, 38, 41 Ovale, 24, 41 Optic, 25, 37, 41 Orbital, 24 Palatine, 32, 42 Parietal, 16 Pterygo-palatine, 42 Rotundum, 24, 41 Sacral, n Scarpa's, 29, 42 Singulare, 311 Spheno-palatine, 31 Spinal, 6 Spinosum, 24, 41 Stenson's, 29, 42 Stylo-mastoid, 21, 43 Supraorbital, 14 Suprascapular, 45 Thyroid, 12 Vertebrale, 6 Winslow's, 326 Foramina at the Base of the Skull, 41 Interventricularia, 190 Olfactory, 41 Orbital, 35 Spheno-maxillary, 42 Thebesii, 119 Venarum Minimarum, 119 Forearm, 48 Formatio Reticularis, 211 Fornix Cerebri, 190 Conjunctivas, 295 Fossa of the Auricle, 297 Canine, 28 Cochlearis (recessus), 305 C9ronoid, 48 Digastric, 20, 34 Digital (femoris), 53 (testis), 374 Duodenal, 327 Duodeno-jejunal, 327 Floccular, 22 Glenoid, 19 Hypophyses, 22 Ileq-colic, 328 Incisive, 28, 34 Incudis, 301 Infraspinous, 45 Inguinal, 388 Intercondylar, 55 4io INDEX Fossa of the Intersigmoid, 328 Ischio-rectal, 394 Jugular, 1 8, 21 Lacrimal, 15, 36 Mandibular, 19 Nasal, 37, 277 Navicularis Auriculae, 297 Penis, 369 Pudendi, 377 Olecranon, 48 Ovalis Cordis, 108, 119 Femoralis, 389 Patellaris, 288 Pericascal, 328 Perinaeal, 393 Peritoneal, 327, 388 Pterygoid, 25 Radial, 48 Rosenmuller's, 322 Scaphoid, 25 Spheno-maxillary, 39 Spheno-palatine, 39 Sublingual, 34 Submandibular, 34 Subscapular, 45 Supraspinous, 45 Supra-tonsillaris, 314 Temporal, 38 Triangularis Auriculae, 297 Trochanteric, 53 Venae Cavae Hepatis, 338 Vesicae Felleae, 338 Zygomatic, 39 Fossae, Inguinal, 388 Nasal, 37, 277 Perinaeal, 393 Retro-peritoneal, 327 of the Skull, 41, 42 Fourchette, 377 Fovea Articularis, 6 Centralis, 285 Hemispherica, 305 Inferior of 4th Ventricle, 212 Semi-elliptica, 305 Superior of dth Ventricle, 212 Fraenulum Cerebelli, 207 Praeputii, 372 Fraenum Linguae, 223 Frenula Oris, 312 Frontal Bone, 14 Sinuses, 15 Fundus Oculi, 285, 286 Uteri, 380 Funiculus, Antero-lateral of Cord, 213 Cuneatus of Medulla, 210 Gracilis of Medulla, 210 Lateralis of Medulla, 209 Posterior of Cord, 213, 215 Postero-lateral of Cord, 214 Postero-median of Cord, 214 Rolando's, 209 Teres, 205 Solitarius, 211, 221 GALL-BLADDER, 343 Gartner's Duct, 383 Ganglia, 177 Ganglia, Basal, 179 Cervical, 237, 268 of the Cranial Nerves, 223 Lumbar, 238, 268 of Ninth Cranial Nerve, 226 Pelvic, 238 Sacral, 268 Semilunar, 240 Spinal, 216, 226 Sympathetic, 268 of Tenth Cranial Nerve, 226 Thoracic, 237, 268 Gangliated Cord of Sympathetic, 237 Ganglion, Arnold's, 224 Bochdalek's, 236 Cardiac of Wrisberg, 239 Carotid, 236 Cerebellar, 208 Ciliary, 224 Coccygeal, 238, 268 Cceliac, 240 Diaphragmatic, 240 Gasserian, 223 Geniculate, 225 Habenulae, 194 Impar, 236, 268 Inferius, 226 Jugular, 226 Jugulare, 226 Lenticular, 224 Meckel's, 224 Nodosum, 226 Ophthalmic, 224 Otic, 224 Petrous, 226 Ribes', 236, 237. 268 of Root of Tenth Nerve, 226 Scarpa's, 311 Semilunar, 223, 240 Spheno-palatine, 224 Spinal, 216 Spirale, 311 Submandibular, 225 Submaxillare, 225 Superius, 226 of Trunk of the Tenth Nerve, 226 Valentines', 236 Wrisberg's, 239 Gasser's Ganglion, 223 Genesiology, i Geniculate Bodies, 193 Gimbernat's Ligament, 387 Gingivae, 317 Girdle, Pelvic, 44 Shoulder, 44 Gladiolus, 8 Gland or Glands Adrenal, 364 Aortic Bodies, 345 Axillary, 173 Barth9lin's, 378 Blandin's, 274 Bowman's, 279 Bronchial, 175 Brunner's, 333 Bulbp-urethral, 371 Cardiac, 330 Carotid Bodies, 345 INDEX 411 Giands of Chromaffin System, 344 of Chromaphil System, 344 Ciliary, 293 Coccygeal, 349 Cceliac, 174 of Cortical System, 345 Cowper's, 371 Ductless, 344 Duodenal, 333 Gastric, 329, 330 Glomus Caroticum, 345 Coccygeum, 349 Ebner's, 274 Entodermal, 345 Fundus, 330 Haemal, 172 Lymph, 172 Intestinal, 332, 335 Kidney, 360 Lacrimal, 295 Lien, 275 Littr6's, 369 Liver, 336 Lumbar, 174 Lymphatic, 171 Mammary, 383 Mediastinal, 175 Meibomian, 294 Mesenteric, 175 Moll's, 293 Mucous, 315 Nuhn's, 274 CEsophageal, 323 Ovary, 382 Pancreas, 343 Paraganglia, 345 Parathyroid, 346 Parovarium, 383 Partiod, 315 Peyer's, 333 Phaerochrome, 344 Pineal, 194 Pituitary, 186 Prostate, 370 Pyloric, 330 Racemose Serous, 274 Rosenmuller's, 295 Salivary, 315 Sebaceous, 271, 273 Seminal, 372 Serous, 274 Smegma, 372 Solitary, 333 Spleen, 375 Sublingual, 316 Submandibular, 316 Submaxillaris, 316 Sudoriferous, 271, 273 Supra-renal, 364 Sweat, 270, 273 Testicle, 372 Thymus, 347 Thyroid. 345 Tracheal, 355 Tonsil, 314 Tyson's, 372 Urethral, 369, 370 of Vascular System, 348 Glands, Vestibulares, 378 Glans Clitoridis, 378 Penis, 372 Glaserian Fissure, 19, 43 Glenoid, 3 Glisson's Capsule, 3.36 Globus Major Epididymis, 273 Minor Epididymis, 273 Glomus Caroticum, 345 Coccygeum, 349 Glottis, 353 Golgi's Cells, 176, 208 Gomphosis, 59 Graafian Vesicles, 383 Granulationes Arachnoideales, 181, 182 Gray Matter (substantia grisea), 176 of Aquaeduct of Sylvius, 202 of Cerebellum, 208 of Cerebrum, 179 of Medulla Oblongata, 209 of Pons Varolii, 204 of Spinal Cord, 215 Nervous Tissue, 176 Rami Communicantes, 227, 238 Groove, Alar, 24 Auriculo- ventricular, 118 Bicipital, 47 Infraorbital, 27 Intertubercular, 47 Interventricular, 118 Lacrimal, 29 Musculo-spiral, 47 Mylo-hyoid, 35 Naso : palatine, 33 Nervi Radialis, 47 Occipital, 20 Optic, 22 Pterygo-palatine, 24, 28 Gubernaculum Testis, 375 Gudden's Commissure, 194, 292 Gullet, 322 Gums, 317 Gyrus, see Convolution or Lobe HABENULAR Ganglion, 194 Trigone, 194 Haemal Glands, 172 Lymph Glands, 172 Hair Cells, Auditory, 310 Hairs, 273 Olfactory, 279 Hamstrings, 112 Hamular, 3 Hamulus, 306 Hand, 50, 105 Hasner's Valve, 296 Haversian Canals, 4 Spaces, 4 System, 4 Head-plates, Auditory, 310 Heart, 118 Heel, 57 Helicotrema, 306 Helix, 297 Hemispheres, Cerebral, 183 Henle's Loops, 362 Hensen's Canal, 307 Cells. 307 412 INDEX Hepar, 336 Hernia, 384 Femoral, 388 Coverings of, 390 Inguinal, 385 Coverings of, 388 Herophilus' Torcular, 18 Hesselbach's Triangle, 387 Key's Ligament, 390 Hiatus Canalis Facialis, 20 Falk>pii, 20, 42 Semilunaris, 277 Highmore (Nathaniel), Antrum of, 27 Hilton's Sac, 354 Hilum or Hilus of the Kidney, 360 of the Lung, 358 of the Spleen, 348 of the Supra-renal Gland, 364 Hind-brain, 203 Hip-joint, 68 Hippocampus Major i 191 Minor, 191 Horner's Muscle (tensor-tarsi), 75 Houston's Valves, 335 Huguier's Canal, 19, 300 Humerus, 47 Humor, Aqueous, 287 Hunter's Canal, no, 142 Hyal, Basi-, 41 Cerato-, 41 Stylo- (styloid process), 21 Thyro-, 41 Tympano- (vaginal process), 21 Hydatid's of Morgagni, 373, 382 Hyoid Pone, 41 Hymen, 378 Hypochondrium, 324 Hypogastrium, 324 Hypothalamus, 202 Hypothenar Eminence, 106 Hypophysis Cerebri, 186 ILEUM, 331 Iliac Regions, 324 Ilium, 13 Incisura Acetabuli, 12 Cerebelli, 206 Intertragica, 297 Marsupialis, 206 Radialis, 49 Rivini, 298 Semilunaris, 49 Thyroidea, 350 Incus, 301 Infundibula of the Kidney, 361 Infundibulum, 26, 277 Cerebri, 186 Cochleas, 306 Nasal, 277 Tubae, Uterinae, 382 Inguinal Regions, 324, 385 Insula Cerebri, 183 Inter-brain, 192 Interspaces, Perinatal, 393 Intestine, Large, 333 Small, 330 Intestinum Crassum, 333 Tenue, 330 Intumescentia Ganglioformis, 225 Iris, 284 Ischio-pubic Ramus, 12 Ischio-rectal Fossa, 394 Anterior Extension of, 394 Region, 394 Space 394 Ischmm, 13 Island of Reil, 183 Isthmus Cerebri, 194 of Fallopian Tube, 382 Faucium, 314 of Hind-brain, 203 Rhombenecephali, 178, 203 of Thyroid Gland, 345 Tubas Auditivae, 303 Uterinae, 382 Iter Chordae Anterius, 19, 300 Posterius, 300 a Tertio ad Quartum Ventriculum, 202 Ivory, 318 JACOB'S Membrane, 287 Jacobson's Nerve, 221, 250, 303 Organ, 278 Joint, see Articulations Ankle, 71 Elbow, 66 Hip, 68 Rotators of the Hip- joint, 112 Knee, 69 Shoulder, 65 Wrist, 67 Joints, Motion in, 60 Structure of, 60 Jugular, Foramen, 42 Fossa, 1 8, 21 Ganglia, 226 Process, 18 Surface, 21 Vein, 165 KNEE-JOINT, 69 Kidney, 360 Kirkring's Valves, 332 Krause's End-bulbs, 177. 272 LABI A Oris, 312 Pudendi Majora, 377 Minora, 377 Labium Tympanicum, 309 Vestibulare, 309 Labyrinth, 304 Membranous, 304, 307 Osseous, 304, 305 Lacertus Fibrosus, 133 Lachrymal, see Lacrimal Lacrimal Apparatus, 295 Bone, 29 Canaliculi, 295 Canals, 295 Carunci, 295 Fossa, 15, 36 Glands, 300 Groove, 24 Nerve, 218, 246 Papilla, 294 INDEX 413 Lacrimal Punctum, 294 Sac, 296 Lacteals, 171, 332 Lacuna Magna Urethrae, 369 Lacunae, 4 Lacus Lacrimalis, 293 Lamina Basilaris, 309 Chorio-capillaris, 283 Cinerea, 186 Cribrosa Auris, 311 Scleraj, 281 Elastica, 282 Pusca, 281 Papyracea, 26 Reticularis, 310 Spiralis, 306 Superchoroidea, 283 Terminalis, 186 Vasculosa, 283 Laminae, 5 Lancisi's Nerves, 190 Larynx, 350 Layer, Basilar (skin), 270 Ganglionic (retinal), 286 Granular (cerebellar), 209 Molecular (cerebellar), 209 (retinal), 286 Nuclear (retinal), 286 Papillary (skin), 271 Pigmentary (retinal), 287 of Rods and Cones (retinal), 286 Rust-colored (cerebellar), 208 Turner's (cerebellar), 208 Leg, 54 Lemniscus, Lateral, 199 Medial, 198 Lens, Crystalline, 288 Lieberkuhn's Crypts, 332 Ligament, 60 Ligament or Ligaments Acromio-clavicular, 65 Alar, 71 of Ankle-joint, 72 Annular, Anterior, 105 Posterior, 105 Anterior Common, 61 Arcuate, 107 Astragalo-navicular, 72 Atlanto-axial, 61 Atlo-axoid, 61 of the Bladder, 366 Broad of Liver, 338 of 'Uterus, 381 Burns', 390 Calcaneo-astragaloid, 72 Calcaneo-cuboid, 72 Calcaneo-navicular, 72 Capsular, see Individual Joints Carpo-metacarpal, 68 of Carpus, 67 Check, 62, 80 Chondro-sternal, 63 Chondro-xyphoid, 63 Coccygeal, 63 Conoid, 65 Coraco-acromial, 65 Coraco-clavicular, 65 Coraco-humeral, 65 Ligaments, Coronal, 71 Coronary, 71, 327 Costo-clavicular, 65 Costo-central, 62 Costo-transverse, 63 Costo-yertebral, 62 Cotyloid, 69 Crico-arytenoid, 353 Crico-thyroid Capsular, 353 Crico-tracheal, 353 Crucial, 70 Cruciform, 62 Deltoid, 72 Dentate, 213 Dorsal, see Individual Joints of Elbow- joint, 66 of Eye, 280 Falciform, 64, 339 of Fingers, 68 of Foot, 72 Gimbernat's. 387 Glenoid, 65 Glosso-epiglottic, 353 of Hand, 68 Key's, 390 of Hip-joint, 69 Hyo-epiglottic, 352 Ilio-femoral, 69 Ilio-lumbar, 63 Ilio-pectineal, 107 of Incus, 302 Inguinal, 387 Interarticular, 62 Interchondral, 63 Interclavicular, 65 Interosseous, see Individual Joints Interspinous, 61 Intertransverse, 61 Intervertebral, 61 Ischio-fempral, 69 of Knee-joint, 69 of Larynx, 352 of Larynx, 352 Lateral, see Individual Joints Lieno-renal, 348 of Liver, 338 Lockwood's, 76, 281 Lumbo-sacral, 63 of the Lung, 356 of Malleus, 302 Metacarpal, 68 Metacarpo-phalangeal, 68 Metatarsal, 73 Metatarso-phalangeal, 73 Nuchal. 6 1, 88 Occipito-atlantal, 62 Occipito-axial, 62 Occipito-odontoid, 62 of the Odontoid Process, 62 Orbicular of Radius, 66 of the Ossicles, 302 of the Ovary, 383 Palpebral, 294 Patellar, 69 Pectineo-femoral, 69 Peritoneal, 326, 327 Phreno-colic, 335 Plantar, 72 4 i4 INDEX Ligaments, Posterior Common, 61 Poupart's, 108, 387 Pterygo-mandibular, 78 Pubic, 64 Pubo-prostatic, 366 Pubo-vesical, 366 Radio-carpal, 67 Radio-ulnar, 67 Recto- vaginal, 381 Rhomboid, 65 Round of Hip- joint, 69 of Liver, 339 of Uterus, 381 Sacro-C9ccygeal, 64 Sacro-iliac, 64 Sacro-sciatic, 64 Sacro-spinous, 64 Sacro-tuberous, 64 Sacro-uterine, 381 of the Scapula, 65 of Shoulder, 65 Spiral of Cochlea, 309 or Spleen, 348 Spleno- phrenic, 348 Spheno-mandibular, 65 of Stapes, 302 Stellate, 62 Sterno-clavicular, 65 of the Sternum, 63 Stylo-hyoid, 21, 41 Stylo-mandibular, 61 Subpubic, 64 Supra-pubic, 64 Supra-spinous, 61 Suspensory of Bladder, 366 of Eye, 281 of Incus, 302 of Lens, 288, 289 of Liver, 339 of Odontoid, 62 of Ovary, 383 of Penis, 393 of Spleen, 348 Tarsal of Eye, 294 Temporo-mandibular, 60 Thyro-arytenoid, 353 Thyro-epiglottic, 353 Thyro-hyoid, 353 Tibio-fibular, 71 Transverse of Atlas, 61 Cotyloid, 69 of Knee, 71 of Scapula, 46 Trapezoid, 65 Triangular, 393 Ulno-carpal, 67 Utero-sacral, 381 Utero-vesical, 381 of the Uterus, 381 of Vertebrae, 61 of Winslow, 70 of Wrisberg, 71 Y-ligament, 69 of Zinn, 76 Ligamentum or Ligamenta Alaria, 71 Arcuata, 107 Calcaneo-fibulare, 72 Ligamenta, Calcaneo-tibiale, 72 Carpi Dorsale, 105 Transversum, 105 Collaterale, Fibulare, 70 Radiale, 66 Tibiale, 70 Ulnare, 66 Coronaria Hepatis, 327, 339 Cruciata Cruris, 115 Denticulatum, 213 Falciforme Hepatis, 339 Gastro-lienale, 326 Hepato-gastricum, 326 Hyo-thyreoidea, 353 Inguinale, 387 Reflexum, 387 Laciniatum, 115 Lacunare, 387 Lata Uteri, 381 Latum Pulmonis, 356 Lieno-renale, 327 Mucosum, 71 Nuchae, 61, 88 Patellae, 69 Pectinatum Iridis, 285 Peronaei Retinaculum, 115 Sacro-spinosum, 64 Sacro-tuberosum, 64 Spirale Cochleae, 309 Suspensorium Dentis, 62 Talo-fibulare, 72 Teres Femoris, 69 Hepatis, 339 Umbilicale, 365 Uteri, 381 Thyreo-epiglotticum, 353 Transversum Cruris, 115 Triangulare Hepatis, 339 Light Spot, 298 Limbus Fossae Ovalis, 119 Laminae Spiralis, 309 Line, Inter-trochanteric, 53 Popliteal, ss Linea Aspera, 53 Ilio-pectinea, 14 Quadrati (inter-trochanteric ridge), Lines, Schreger's, 319 Lingua, 273 Lingula Cerebelli, 203 Lips, 312 Liquor Morgagni, 289 Lithotomy, Structures Concerned, 396 Littr6's Glands, 369 Liver, 336 Structure of, 339 Lobe of the Ear, 297 Lobes and Gyri of the Brain Ala Lobuli Centralis, 207 Amygdala, 207 Angular, 185 Biventral, 207 Broca's, 185 Buccal, 188 Centralis, Anterior, 185 Posterior, 185 Clivus Monticuli, 207 Commissura Simplex, 207 INDEX 415 Lobes, Cresenctic, 207 Culmen Monticuli, 207 Cuneus, 186 Dentate, 191 Diclive, 207 Flocculus, 207 Folium Cacuminis, 207 Fraenulum, 207 Frontal, 185 Fusiformis, 186 Glandular, 188 Gracile, 207 Hippocampal, 186 Limbic, 183 Lingualis, 186 Lingula, 207 Lobulus Centralis, 207 Occipital, 186 Occipito-temporal, 186 Olfactory, 183 Operti, 1 86 Orbital, 185 Parietal, 185 Postcentral, 186 Postparietal, 185 Precentral, 186 Precuneus, 185 Pyramid, 207 Semilunar, 207 Slender, 207 Subcalcarine, 186 Supramarginal, 185 Temporal, 183, 186 Tonsil, 207 Tuber Valvulae, 207 Uncinate, 186 Uvula, 207 Vermis, 206, 207 Vinculum Lingulae, 207 Worm, 206, 207 Lobes of the Cerebellum, 207 of the Cerebrum, 183 of the Liver, 338 of the Prostate Gland, 370 of the Thyroid Gland, 345 Lobule of the Ear, 297 Lobules of Liver, 340 of the Lung, 359 of the Mammary Gland, 384 Lobus Caudatus, 338 Quadratus, 338 Spigelii, 338 Lockwood's Ligament, 76 Locus Caeruleus. 20 a, 212 Perforatus, 186 Loops of Henle, 362 Lower's Tubercle, 120 Lumbar Regions, 324 Lumbo-dorsal Fascia, 90 Lungs, 357 Lunula, 273 Lymphatic System, 171 Vessels, 171 Lymph Glands, 171 Haemal, 172 Space, Peri-choroidal, 283 Peri-sclerotic, 281 Spaces of Eye, 290 Lymphatics of the Abdomen, 174 Auricular Region, 173 Bladder, 368 Bronchi, 175, 356 Buccal Region, 173 Cardiac Region, 175 Cervical Region, 173 Head, 172 Inguinal Region, 174 Intestine, 333, 336 Larynx, 354 Liver, 341 Lower Extremity, 174 Lung, 359 Kidney, 363 Mammary Gland, 384 Mastoid Region, 173 Mediastinum, 175 Mesentery, 175 Neck, 172, 173 Pancreas, 344 Parotid Regi9n, 173 Pectoral Region, 174 Pelvis, 174 Occipital Region, 172 Spleen, 349 Submandibular Region, 173 Supra-renal Gland, 365 Testicle, 375 Thymus Gland, 347 Thyroid Gland, 346 Tongue, 275 Trachea, 356 Upper Extremity, 173 Uterus, 382 Vagina, 379 Lympho-glandulae, 171 Auriculares, 173 Bronchiales, 175, 356 Ceryicales, 173 Cubitales, 173 Linguales, 173 Mesentericae, 175 Occipitales, 172 Parotidae, 173 Submaxillares, 173 Lyra, 190 MACULA Acustica, 307 Lutea, 285 Saccularis, 308 Utricularis, 308 Malar Bone, 30 Malleolus, 55. 56 Malleus, 301 Malpighi's Bodies, 349, 361 Pyramids, 361 Malpighian Tufts, 361 Mammary Gland, 383 Mandible, 33 Manubrium of Malleus, 301 of Sternum, 8 Marrow of Bones, 4 Massa Intermedia, 193 Masses, Lateral of Ethmoid, 26 Mastoid, 3 Cells, 20 4 i6 INDEX Mastoid, Foramen, 20 Process, 20 Matrix of Nail, 273 Maxilla, 27 Meatus Acusticus Externus, 297 Interims, 311 Auditorius Externus, 20, 297 Internus, 20, 42, 311 Nasi, 3.8, 277 Urinarius, 369, 370 Meckel's Diverticulum, 331 Ganglion, 224 Media, Refracting of Eye, 287 Mediastinum Testis, 374 Thoracis, 356 Medulla Oblongata, 208 Spinalis, 213 Membrana Basilaris, 309 Crico-thyroidea, 353 Granulosa, 383 Limitans Externa, 287 Interna, 286 Nictitans, 295 Pupillaris, 285 Sacciformis, 67 Tectoria, 309 Tympani, 298 Secundaria, 300 Membrane or Membranes Brain, 180 Bruch's, 283 Demour's, 282 Descemet's, 282 Hyaloid, 288 Hyo-glossal, 274 Hyo-thyroid, 353 Interosseous, 67, 71 Jacob's, 287 Limiting, 286, 287 . Meningeal, 180, 213 Mucous, 271 Nasmyth's, 319 Obturator, 12 Pituitary, 278 Reissner's, 309 Schneiderian, 278 Shrapnell's, 298 of Spinal Cord, 213 Synovial, 60 Carpal, 67 Tarsal, 72 Thyro-hyoid, 353 Thyroid, 12 Vestibular, 309 Meninges of Brain, 180 of Spinal Cord, 213 Menisci of Knee-joint, 70 Mesenteries, 327 Mesencephalon, 178, 203 Mesencephalic Root of Fifth Nerve, Meso-colon, 327, 334 Meso-rectum, 327 Meso-sigmoid, 327 Metacarpus, 51 Metapore, 182, 211 Metatarsus, 58 Metathalamus, 193 Metencephalon, 178, 203 Meynert's Commissure, 292 Mid-brain, 178, 194 Modiolus Cochleae, 306 Moll's Glands, 293 Mons Veneris, 377 Morgagni's Hydatids, 373, 382 Lacuna, 360 Sinus, 359 Mouth, 312 Miiller's Fibres, 286 Munro's Foramen, 190 Muscle or Muscles, 73 Abdominal, 95 Abductor Digiti Quinti (hand), 106 .(foot), 116 Indicis (ist dorsal interosseous), 107 Minimi Digiti (foot), 116 Digiti (hand), 106 Pollicis, 106 Brevis, 106 Longus, 105 Accelerator Urinae, 98 Accessories ad Ilio-costalem, 91 of Acromial Region, 100 Adductor Brevis (femoris), no Longus (femoris), no Magnus (femoris), no Obliquus Hallucis, 117 Ppllicis, 106 Pollicis, 106 Transyersus Hallucis, 117 Pollicis, 106 Ancpneus, 104 Anti-tragicus, 80, 297 Appendicular, 86, 87 of Arm, 100 Articularis Genu, 109 Aryteno-epiglottideus Inferior, 86 Superior, 86 Arytenoideus, 86 Attollens Auriculam, 75 Attrahens Auriculam, 75 of Auricle, 297 Auricularis Anterior, 75 Posterior, 75 Superior, 75 Axial. 87 ygos UT of Back, 86 Azygos Uvulae, 84 Biceps, ip i Femoris, 112 Flexor Cubiti, 101 Biventer Cervicis, 92 of the Bladder, 367 Bowman's (ciliary), 284 (Cochlear), 309 Brachialis, 101 Anticus, loi Brachio-radialis, 104 of Buccal Region, 78 Buccinator, 78 Bulbocavernosus, 98 Caninus, 77 of Cervical Region, 80, 84 Cervicalis Ascendens, 91 Chondro-glossus, 81 Ciliary, 284 INDEX 417 Muscles, Circumflexus (tensor) Palati, 83 Coccygeus, 98 Complexus, 92 Compressor Narium Minor, 77 Nasi, 77 Sacculi Laryngis of Hilton (ary- teno-epiglottideus inf.), 86 Urethrae (female), 99 (male), 98 Constrictor Isthmi Paucium, 84 Pharyngis In Middle, 83 is Inferior, 83 Superior, 83 Coraco-brachialis, 101 of Cranial Region, 75 Corrugator Cutis Ani, 97 Supercilii, 75 Cremaster, 95 Crico-arytenoid, Lateral, 86 Posterior, 85 Crico-thyroid (thyreoideus), 85 Crureus, 109 Cursor Ani (latissimus dorsi), 88 Deltoid (deltpideus), 100 Depressor Ali Nasi, 77 Anguli Oris, 78 Labii Inferioris, 78 Septi Nasi, 77 Detrusor Urinse (outer muscular coat of the bladder), 367 Diaphragm, 94 Digastric, 82 Dilator Naris Anterior, 77 Posterior, 77 Pupillae, 285 Tubae Auditivae, 303 of Dorsal Region, 86 of the Ear, 75. 79, 297 Ejaculator Seminis (bulbo-caverno- sus), 98 U rinse (bulbo-cavernosus), 98 of the Epiglottis, 85, 354 Erector Clitoridis (ischio-caverno- sus), 09 Penis (ischio-cavernosus), 99 SpinEB, 90 of the Eustachian Tube, 303 of Expression, 77, 79 Extensor Brevis Digitorum, 115 Pollicis, 1 05 Carpi Radialis Brevoir, 104 Longior, 104 Ulnaris, 104 Coccygis, 93 Communis Digitorum, 104 Digiti Quinti Proprius, 104 Hallucis Longus, 113 Indicis, 105 Longus Digitorum, 113 Hallucis, 113 Pollicis, ip$ Minimi Digiti, 104 Ossis Metacarpi Pollicis, 105 Extensor, Primi Internodii Pollicis, 105 Proprius Hallucis, 113 Secundi Internodii Pollicis, 105 External Oblioue (abdomen), 95 Muscles of Eyeball, 76, 289 of Eyelid, 75, 294 of the Face, 77, 79 of the Femoral Region, 108, no, 112 of the Fibular Region, 115 Flexor Accessorius, 116 Brevis Digitorum, 116 Hallucis, 117 Minimi Digiti (foot), 117 (hand), 106 Pollicis, 106 Carpi Radialis, 102 Ulnaris, 103 Digiti Quinti Brevis (foot), 117 (hand), 106 Digitorum Brevis, 106 Hallucis Brevis, 117 Longus Digitorum, 114 Hallucis, 114 Pollicis, 103 Ossis Metacarpi Pollicis (oppo- nens), 106 Pollicis Brevis, 106 Longus, 103 Profundus Digitorum, 103 Sublimis Digitorum, 103 of the Forearm, 102 of the Foot, 115 Frontalis, 75 Gastrocnemius, 113 Gamellus Inferior, in Superior, in Genio-glossus, 82 Genio-hyo-glossus, 82 Genio-hyoid, 82 Glosso-palatinus, 84 of the Gluteal Region, no Glutaeus or Gluteus Maximus, no Medius, no Minimus, ill Gracilis, 109 Hamstring, 112 of the Hand, 106 of the Head, 75 Helicis Major, 79, 297 Minor, 80, 297 Hilton's (aryteno-epiglottideus in- ferior), 86 of the Hip, 1 10 Hip Rotators, 112 Homer's (tensor tarsi), 75 of Humeral Region, 101 Hyo-glossus, 82 Hyppthenar, 106 of Iliac Region, 107, no Iliacus, 108 Ilio-capsularis (outer fibres of iliacus), 108 Ilio-coccygeus (posterior fibres of levator ani), 98 Ilio-costales, 91 Lumborum, 91 Infra-cost ales, 94 Infra-hyoid Region, 81 Infraspinatus, 101 Intercostal, External, 93 Internal, 93 Internal Oblique (abdomen), 95 4*8 INDEX Muscles, Interossei of foot, 117 Inter-spinales, 93 Inter-transversaTes, 92 Iritertransversarii, 93 Involuntary, 74 Ischio-cavernosus, 98, 99 of Ischio-rectal Region, 97, 395 Kerato-cricoideus, 85 Labial Region, 77 of Larynx, 85, 354 Latissimus Dorsi, 88 Laxator Tympani, 80 of the Leg, 112 Levator Anguli Oris, 78 Scapulae, 88 Ani, 98 Glandulae Thyroideae, 346 Labii Superioris, 77 Alasque Nasi, 77 Menti, 78 Palati, 83 Palpebrae Superioris, 76 Prostatae (pre-anal fibres of levator am), 98 Scapulae, 88 Urethrae (pre-anal fibres of levator ani), 98 Veli Palatini, 83 Levatores Costarum, 94 Lingualis, 83 Lingual, Longitudinal, 83 Transverse, 83 Vertical, 83 of Lingual Region, 82 Longitudinalis Linguae Inferior, 83 Superior, 83 Longissimus Capitis, 91 Cervicis, 91 Dorsi, 91 Longus Capitis, 84 Colli, 84 of Lower Extremity, 107 Lumbricales of foot, 116 of hand, 107 Mandibular Region, 78 Masseter, 79 of Mastication, 79 of Maxillary Region, 77 Mentalis, 78 Multifidus, 92 Spinae, 92 Mylo-hyoid, 82 Nasalis, 77 of Nasal Region, 77 Naso-labialis (upper medial fibres of orbiculans oris), 78 of Neck, 80 Obliquus Abdominis Externus, 95 Internus, 95 Auriculae, 80, 297 Capitis Inferior, 93 Superior, 93 Oculi Inferior, 77 Obliquus Oculi, Superior, 76 Obturator Externus, 112 Internus, 112 Occipitals, 75 Occipito-frontalis, 75 Muscles, Omo-hyoid, 81 Opponens Digiti Quinti, 107 Minimi Digiti, 107 Ppllicis, 106 Orbicularis Oculi, 75 Oris, 78 Palpebrarum, 75 of Orbital Region, 76, 289 of Palatal Region, 83, 313 Palato-glossus, 8j Palato-pharyngeus, 84 of Palmar Region, 106 Palmaris Brevis, 106 Longus, 102 of Palpebral Region, 75 Fectineus, no of Pectoral Region, 99 Pectoralis Major, 99 Minor, 99 of Pelvic Outlet, 97 Perforans, 103 Perforatus, 103 of Perinaeum, female, 99, 396 Male, 98, 393 of Peroneal Region, 115 Peroneus (peronasus) Brevis, 115 Longus, 115 Tertius, 113 of Pharyngeal Region, 83, 322 Pharyngo-glossus (superior con- strictor), 83 Pharyngo-palatinus, 84 of Pinna, 79 of Plantar Region, 116 Plantaris, 114 Platysma-myoides, 80 Popliteus, 114 Prevertebral of Head and Neck, 84 Procerus, 77 Pronator Quadratus, 103 Radii Teres, 102 Teres, 102 Psoas Magnus, 107 Major, 107 Minor, 108 Parvus, 108 of Pterygo-mandibular Region, 79 Pterygoid, External, 79 Internal, 79 Pubo-coccygeus (medial fibres of levator ani), 98 Pyrarnidalis, 97 Nasi, 77 Pyraformis, in Quadratus FenKms, 112 Labii Inferioris, 78 Superioris, 78 Lumborum, 97 Menti, 78 Plantae, 116 Quadriceps Extensor, 108 Femons, 108 Radial Region, 102 Recti Oculi, 76 Recto-urethralis (pre-anal fibres of levator ani), 98 Recto-uterinus (sacro-uterine liga- ment), 381 INDEX 419 Muscles, Rectus Abdominis, 96 Capitis Anticus Major, 84 Minor, 84 Lateralis, 84, 93 Posticus Major, 93 Minor, 93 Femoris, 109 Oculi Externus, 76 Inferioris, 76 Internus, 76 Lateralis, 76 Medialis, 76 Superioris, 76 Retrahens Auriculam, 75 Rhomboideus Major, 89 Minor, 88 Risorius, 79 Rotatores, 92 Spinse, 92 Rotators of the Hip, no Sacro-lumbalis, 91 Sacro-spinalis, 90 Salpingo-pharyngeus, 84 Santorini's (risorius), 79 Sartorius, 108 Scalenus Anticus (anterior), 85 Medius, 85 Posticus (posterior), 85 of the Scalp, 75 of Scapular Region, 100 Semi-membranosus, 112 Semi-spinalis Capitis, 92 Cervicis, 92 Colli, 92 Dorsi, 92 Serratus, Anterior, 100 Magnus, 100 Posticus (posterior) Inferior, 90 Superior, 89 of the Shoulder, 100 Skeletal (voluntary), 73, 74 Sphincter Ani Externus, 97 Internus, 97 Tertius, 97 Pupillae, 285 Vaginae, 99 Vesicae, 367 Spinalis Cervicis, 92 Colli, 92 Dorsi, 92 Splenius Capitis, 90 Cervicis, 90 Colli, 90 Stapedius, 80, 302 Striated Muscle, 73, 74 Striped Muscle, 73, 74 Structure of Muscle, 73 Stylo-glossus, 82 Stylo-hyoid, 82 Stylo-pharyngeus 83 Sub-anconeuc, 102 Subclavius, 100 Subcrureus, 109 of Suboccipital Region, 93 Subscapularis, 100 Supinator, 105 Brevis, 105 Longus, 104 Muscles of Supra-hyoid Region, 82 Supraspinatus, 101 Temporal, 79 of Temporo-mandibular Region, 79 Tensor Fasciae Femoris, 108 Latae, 108 Palati, 83 Tarsi, 75 Tympani, 80, 302 Vaginae Femoris, io3 Veli Palatini, 83 Teres Major, 101 Minor, 101 Thenar, 106 of Thigh, 108 of Thorax, 93, 99 Thyro-(thyreo) Arytenoideus, 86 Thyro-(thyreo) Epiglottideus, 86 Thyro-(thyreo) Hyoid, 81 Tibialis Anticus (anterior), 112 Posticus (posterior), 114 of Tibio-fibular Region, 112 Todd's (cochlear), 309 of the Tongue, Extrinsic, 82, 274 Intrinsic, 83, 275 Trachelo-Mastoid, 91 Tragicus, 80, 297 Transversalis Abdominis, 96 Cervicis, 91 Colli, 91 Transversus Auriculae, 80, 297 Linguae, 83 Pennaei Profundus, 98, 99 Superficialis, 98, 99 Trapezitts, 88 Triangularis Menti, 78 Sterni, 94 Triceps, 102 Extensor Cubitis, 102 Triticeo-glossus, 86 of the Trunk, 86 Turner's (Kerato-cricoideus), 85 of Tympanum, 80, 302 of Ulnar Region, 102 Unstriated Muscle, 73, 74 Unstriped Muscle, 73. 74 of Upper Extremity, 99 Urethral, 369 Uvulae, 84 Vastus Externus, 109 Intermedius, 109 Internus, 109 Lateralis, 109 Medialis, 109 Vertical is Linguae, 83 Voluntary Muscle, 73, 74 Zypomaticus, 78 Major, 78 Minor, 78 Muscular Fibre, 73 Musculi Papillares, 120, 122 Myencephalon, 177. 208 Myelology, NAILS, 272 Nares, 276 Nasal Bones, 27 Conchae, 26, 32 Fossa, 277 420 INDEX Nasal Meatus, 26, 277 Septum, 276 Nasmyth's Membrane, 319 Naso-labial Band, 78 Nasopharynx, 321 Nates, 202 Navel, 298 Navicular Bone, 57 Neck of the Bladder, 366 of the Femur, 52 of the Humerus, 47 Surgical Triangles of, 128 of the Uterus, 398 Nerve or Nerves Abducent, 219, 252 Accessorius, 222, 250 Acustic, 220, 310 Alveolar, 219, 246 Anastomoticus Tibialis, 235, 236 of Ankle-joint, 235 of the Arm, 229 Arnold's, 221, 250 Auditory, 220, 310 of Auditory Canal, 219, 246 of Auricle, 298 Auricular, Anterior, 219, 246 Great, 227, 254 from Pneumogastric, 221, 250 Posterior, 220, 248 Auricularis Magnus, 227 Axillaris, 229 Bell's, 229 of Bladder, 368 of Bronchi, 356 Buccal, of Facial, 220, 248 Long, 219 of ME [andibular, 219, 246 Buccinator, 219, 246 Calcaneal, Lateral, 235, 267 Medial, 235, 267 Calcaneo-plantar, 235, 267 Canalis Pterygoidei, 226 Cardiac, 119 Cervical, 222, 237, 250, 268 Inferipr, 222 Superior, 222, 237, 268 Thoracic, 222, 250 Carotico-tympanic, 237 Carotid, 221 Cavernus, 242 Cells, 176 Cerebral, 216 Cervical, 220, 227 Cervico-facial, 220, 248 Chorda Tympani, 220, 248, 276 Ciliary, Long, 218, 246 Short, 224 Circumflex, 229, 260 Clunium Inferioris Medialis, 234 Coccygeal, 233, 262 Cochlear, 221, 252, 311 Communicantes, Gray Rami, 227 Fibular, 236 Hypoglossi, 228, 254 * Peronei, 236, 267 Tibial, 235, 267 'White Rami, 227, 238 Cranial, 216 Nerves, Crural, Anterior, 233, 264 Genito-, 232, 264 Cutaneous, Abdominal, 231 Antibrachii Medialis, 229 Posterior, 229 Brachii Medialis, 229 Posterior, 230 C9lli, 227 Digitales Plantares, 235 Volares, 229 Dorsal, 230 Antibrachial, 229 Femoral, 234 External Femoral, 232, 264 Internal, 229, 256 Femoral, 233 Lateral Brachial, 229 Femoral, 232 Lesser Internal. 229, 256 Medial Antibrachial, 229 Brachial, 229 Femoral, 233, 264 Palmar, 229 Perforating 234, 266 Plantar, Lateral, 235 Medial, 236 Posterior Antibrachial, 229 Femoral, 234 Surae Lateralis, 236 Medialis, 235 Dental, Anterior Superior, 219, 246 Inferior, 219, 246 Middle Superior, 219, 246 Posterior Superior, 219, 246 Descendens Hypoglossi, 222, 252 Digastric of Facial, 220, 248 of Mylo-hyoid, 219, 246 Digital (foot), 235 (hand), 229 Digitales Plantares, 235 Volares, 229 Dorsal of Clitoris, 234, 266 of Penis, 234, 266 of the Ear, see Individual Portions Eighth Cranial, 220, 252, 311 of Elbow-joint, 230 Eleventh Cranial, 222, 250 of Equilibration (vestibular), 221, 252, 319 Endings, 177 of Eustachian Tube, 304 of Eyeball, 218, 219, 289 of Eyelids, 218, 219, 289 Eye-muscles, 218, 219, 289 Facial, 220, 248 Femoral, 233 Fibres, 177 Fifth Cranial, 218, 2^6 First Cranial, 216, 244 Fourth Cranial, 217, 244 Frontal, 218, 246 Gastric, 222 Genital, 232, 264 Genito-crural, 232, 264 Genito-femoral, 232, 264 Glosso-palatine, 220, 248, 310 Glosso-pharyngeal, 221, 250 Gluteal, Inferior, 234, 266 INDEX 421 Nerves, Gluteal, Superior, 234, 266 Gustatory, 219, 246 Haemorrhoidal, 234, 266 of Heart, 119 Hepatic, 340 of Hip-joint, 234 Hypo-glossal, 222, 252 Ilio-hypqgastric, 232, 264 Ilio-inguinal, 232, 264 Incisive, 219, 246 Infra-orbital, 218, 220, 246 Infra-trochlear, 218, 246 Intercostal, Abdominal, 231, 261 Thoracic, 231, 261 Intercosto-brachial, 231 Intercosto-humeral, 231 Intermedius (glosso-palatine), 220, 248, 310 Interosseous. Anterior from Median, 229, 258 from Anterior Tibial, 236 Antibrachii Dorsalis, 230 Volaris, 229 Posterior from Musculo-spiral, 230, 258 of the Intestines, 333, 336 of the Iris, 28$ Ischiadicus, 234 Jacobson's, 221, 250, 303 of the Kidney, 363 of the Knee-joint, 235 Labial, 219, 246 Lacrimal, 218, 246 Lancisi's, 190 Laryngeal, External, 221, 250 Inferior, 222, 250 Internal, 221, 250 Recurrent, 222, 250 Superior, 221, 250 of the Larynx, 354 Lingual from Mandibular, 219, 246, from Glosso-pharyngeal, 221, 250 of the Liver, 340 Lumbar, 232, 262 Malar, 219, 220 of the Mammary Gland, 384 Mandibular, 219, 246 Masseteric, 219, 246 Masticator, 201, 219, 246 Mastoid, 227 Maxillary, 218, 246 Median, 229, 258 of Membrana Tympani, 299 Meningeal, from sth, 219, 246 from loth, 221, 250 from I2th, 222, 250 of the Cord, 227 Recurrent, 227 Mental, 219 Motor-oculi, 217, 244 Musculo-cutaneous of Arm, 229, 258 of leg, 236, 267 Musculo-spiral, 230, 255 Mylo-hyoid, 219, 246 Nasal, 218, 219, 246 Posterior Inferior, 224 Superior. 224 Nerves, Nasal, Superior, 224 Naso-ciliary, 218 Naso-palatine, 224 Ninth Cranial, 221, 250 of the Nose, 279 Obturator, 232, 244, 264 Accessory, 232, 264 Occipital, Great, 227, 254 Small, 227, 254 Occipitalis Magnus, 227 Minimus, 227 Oculo-motor, 217, 244 Oesophageal, 222, 250 Olfactory, 216, 244 Ophthalmic, 218, 246 Optic, 217, 244, 291 Orbital, 219, 224, 246 of Orientation (vestibular) , 221, 252, 311 of the Ovary, 383 Palatine, Anterior, 224 External, 224 Large, 224 Medial, 224 Middle, 224 Posterior, 224 Small, 224 Palmar, 229, 230, 258, 260 Palpebral, 219, 246 of the Parotid, 219, 246 Pars Intermedia (glosso-palatine), 220, 248, 310 Patheticus, 217 Path, Optic-acustic Reflex, 199, 200 of the Penis, 372 Peronaeus Profundus, 236 Superficials, 236 Petrosal, Deep, 237 Great Superficial, 225 Small Superficial, 225 Pharyngeal, 224 from Ninth Cranial, 221, 250 from Tenth Cranial, 221, 250 Phrenic, 228, 254 Plantar, 235, 267 Plexuses, see Plexus Pneumogastric, 221, 250 Popliteal, External, 235, 267 Internal, 235, 267 Portio Dura, 220 Mollis, 220 of the Prostate Gland, 371 Pterygoid, External, 219, 246 Internal, 219. 246 Pterygo-palatine, 224 Pudenda! Inferior, 234 Long, 234 Pudendus, 234 Pudic, 234, 266 Pulmonary, 222, 250 Radial, 230, 256 Radialis, 230, 256 Rami Communicantes, Gray, 227, 238 White, 227. 238 Respiratory, of Bell, 229 External, 229 422 INDEX Nerves, Respiratory, Internal, 228 Sacral, 233, 262 Saphenous, External, 235, 267 Internal, 233, 264 Long, 233, 264 Short, 235, 266 Sciatic, Great, 234, 266 Small, 234, 266 Scrotal, 232 Second Cranial, 217, 244, 291 Seventh Cranial, 220, 248 of Shoulder-joint, 65 Sixth Cranial, 219, 252 of the Spermatic Cord, 377 Spheno-palatine, 219, 246 Spinal, 216, 226, 254 Accessory, 222, 250 Splanchnic, Great, 227, 238, 268 Small, 227 of the Spleen, 241, 349 of the Stomach, 330 Stylo-hyoid, 220, 248 Stylo-pharyngeal, 221, 250 Suboccipital, 227, 254 Subscapular, 229, 260 Superficialis Colli, 227, 254 Supra-aero mial, 228 Supra-clavicular, 228 Supra-orbital, 218, 2^6 of the Supra-renal Gland, 365 Suprascapular, 229 Suprasternal, 228 Supratrochlear, 218, 246 Sural, 235, 236 Sympathetic, 236, 268 of Taste, 275, 276 Temporal, Deep, 219, 246 Superficial, 220, 248 Superior, 219, 246 Temporo-facial, 220, 248 Temporo-malar, 219 Tensoris Tympani, 225 Veli Palatim, 225 Tenth Cranial, 221, 250 Terminations of, 177 of Testicle, 375 Third Cranial, 217, 244 Thoracic, 231 Anterior, 229, 258, 260 Intercostals, 261 Long, 229, 256 Posterior, 229, 256 Thoraco-dorsalis, 229 of Thymus Gland, 347 Thyro-hyoid, 222, 252 of Thyroid Gland, 346 Tibial, Anterior, 236, 267 Posterior, 235, 267 Tibialis, 235 of the Tongue, 275, 276 Tonsillar, 221, 250, 315 of Trachea, 356 Trifacial, 218, 246 Trigeminal, 218, 246 Trochlear, 217, 244 Trancus Lumbo-sacralis, 233 Twelfth Cranial, 222, 252 Tympanic, 220, 248, 303 Nerves of Tympanic Membrane, 299 of Tympanum, 303 Ulnar, 229, 256, 260 of the Ureters, 364 of the Uterus, 382 of the Vagina, 380 Vagus, 221, 250 Vaso-motor, 122 Vedian, 226 of the Vesiculse Seminales, 377 of the Vulva, 379 Wrisberg's, 229 of Wrist-joint, 230 Zygomatic, 219 Zygomatico-facial, 219 Zygomatico-temporal, 219 Nervous System, 175, 242 Tables and Plates, 242 Neurilemma, 177 Neuroglia, 176, 214 Neurology, i Neurones, 176 Nipple, 384 Nodule, 207 Noduli Lymphatici Agregati, 333 Lienalis, 349 Valvarum Semilunarum, 120 Nose, 276 Vestibule of, 176 Notch, Cerebellar, 206 Cotyloid, 12 Ethmoidal, 16 Frontal, 15 Great Sciatic, 13 Interclavicular, 8 Intercondylar, 54 Lesser Sciatic, 13 Nasal, 15 Popliteal, 53 of Rivini, 298 Sacro-iliac, 13 Sacro-sciatic, 13 Sigmoid, 34 Supraorbital, 14, 37 Suprascapular, 46 Thyroid, 350 Ulnar, 50 Nuchal Crest, 17 Ligament, 61, 88 Lines, 17 Nuck's Canal, 381 Nucleus or Nuclei, Abducent, 204 Amygdalae, 179 Anterior, 193 Auditory, 204 Caudatus, 191 Cerebellar, 208 Cuneatus, 198 Dentate, 208 Dorsal, 210, 216 Emboliformis, 208 Facial, 204 Fastigii, 208 Fourth Ventricle, 212 Globosus, 208 'Gracilis, 198 Habenulse, 194 Hypo-thalamicus, 203 INDEX 423 Nucleus, Lenticular, 192 Lentiformis, 192 Lentis, of Crystalline Lens, 288 Mesencephalic of Masticator, 202 Olivary, Accessory, 209 Inferior, 209 Superior, 204 Pontis, 204 Red, 197 Roof, 208 Stilling's, 208 Tegmenti Ruber, 197 Trigeminal, 204 Nuhn's Glands, 274 Nymphae, 377 OBEX, 212 Occipital Bone, 17 Odontoblasts, 319 Odontoid, 3 Process, 7 (Esophagus, 322 Olive, 209 Omenta, 326 Omentum, Gastro-colic, 326 Gastro-hepatic, 326 Gastro-splenic, 326 Great, 326 Lesser, 326 Opening, Saphenous, 108, 389 Optic Thalamus, 193 Ora Serrata, 285 Orbiculus Ciliaris, 283 Orbit, 35 Organ or Organa Accessoria Oculi, 293 Auditus, 296 of Corti, 309 of Digestion, 312 of Equilibration, 309 of Generation, Female, 377 Male, 370 of Hearing, 296 of Jacobson, 278 of Orientation, 309 of Rosenmuller, 383 of Sight, 280 of Smell, 276 of Special Sense, 270 Spirale, 309 of Taste, 273 of Touch, 272 Urinary, 360 of Voice and Respiration, 350 Vomero-nasale, 278 Orientation, 309 Orificium Uteri, 380 Os or Ossa, see Bones Ossicula Auditus, 301 Ossification, 4 Osteology, i Ostium Arteriosum, 121 Pulmonis, 120 Venosum Ventriculi Sinistri, 121 Ptoconia, 307 Otoliths, 307 Ovaries, 382 Ovicapsule, 383 Oviducts, 382 PACCHIONIAN Bodies, 181, 182 Paccinian Corpuscles, 177, 272 Palate, 313 Bone, 31 Pampiniform Plexus, 375, 383 Pancreas, 3*13 Lesser, 344 Panniculus Adiposus, 74 Carnosus, 74 Papilla, Lacrimal, 294 Optic, 286 Spiralis, 309 Papillae Circumvallate, 274 Filiformes, 274 of Kidney, 361 of Mammae, 384 of Skin, 271 of Tongue, 274 Vallatae, 274 Paraganglia, 345 Parathyroid Glands, 346 Parietal Bone, 16 Parotid Gland, 315 Parovarium, 383 Pars Ciliaris Retinae, 285 Flaccida Membranae Tympani, 298 Intermedia, 220, 276 Iridica Retinae, 285 Patella, 54 Path, Optic-acustic Reflex, 199, 200 Pecten Ossis Pubis, 14 Pedicles, 5 Peduncles of Cerebellum, Inferior,2O7, 209 Middle, 204, 207 Superior, 201, 207 of Cerebrum, 195 Pelvis, 9 Cavity of, 391 Fasciae of, 391 of the Kidney, 363 Penis, 371 Pericardium, n8 Pericementum, 319 Perilymph, 304 Perinaeal, Body, 395 Fossae, 393 Interspaces, 393 Perinaeum, Proper, 391 Female, 395 Male, 392 Perineurium, 177 Periosteum, 4 Peritoneum, 325 Peroneal Bone, 55 Peroneus, 55 Pes Accessorius, 191 Anserinus, 220 Hippocampi, 191 Petiolus Epiglottidis, 352 Petit's Canal, 288, 289 Petro-mastoid Bone, 19 Peyer's Glands, 333 Phaerochrome System, 344 Phalanges, 52, 58 Pharyngeal Cushion, 321 424 INDEX Pharynx, 320 Pia Mater, 182, 213 Pillars of the Fauces, 314 of the Abdominal Ring, 386 Pjlli, 273 Pineal Gland, 194 Pinna of the Ear, 297 Pituitary Body, 186 Plate, Cribriform, 26 Orbital of Ethmoid, 26 of Frontal, 15 Perpendicular, 26 Tarsal, 294 Pleurae, 356 Plexus, Aortic, 2JT, 268 Brachial, 228, 256 Tabulated, 230 Cardiac, 239 ' Cartoid, 237, 268 Cavernous, 237, 268 of the Clitoris, 242 Cervical, 227 Choroid, 190 Cceliac, 240 Colic, Left, 241 Coronary, 239, 241 Cystic, 241 Diaphragmatic, 240 Epigastric, 240 Gastric, Inferior, 241 Superior, 241, 250 Gastro-duodenal, 241 Gastro-epiploic, 241 Gullae (oesqphageal) , 323 Haemorrhoidal, Inferior, 242 Superior, 241 Hepatic, 241, 300 Hypogastric, 241, 268 Interlobular, 342 Lienal, 241, 349 Lumbalis, 232 Lumbar, 232, 262 Mesenteric, Inferior, 241 Superior, 241 (Esophageal, 222, 250, 323 Olfactory, 279 Ovarian, 2^10, 241 Palatine, 315 Pampiniform, 375, 383, Pelvic, 2di, 268 Pharyngeal, 237, 268, 315, 322 Phrenic, 240 Prostatic, 242 Pudendal, 234 Pulm9nary, 239, 268, 358 Pyloric, 2A I Renal, 2^0, 263 Sacral, 233, 262 Sigmoid, 241 Solar, 240 Spermatic, 2di Spinosus, 219 Splenic, 241, 349 Supra-renal, 240 Tympanic, 303 Uterine, 2J2 Vaginal, 242, 380 Vesical, 242 Plexuses of the Sympathetic, 239, 268 Plica or Plicae Alares, 70 Arytaeno-epiglotticae, 352 Glosso-epiglotticae, 353 Lacrimalis, 296 Palmatse, 380 Recto-uterinae, 381 Semilunaris, 295, 314 Syriovialis Patellaris, 71 Transyersales Recti, 335 Ventriculares, 353 Vocales, 353 Point, Central Tendinous of Perinaeum, 394 Pomum Adami, 350 Pons Hepatis, 338 Tarini, 188 Varolii, 203 Porta Hepatis, 338 Portal System, 170 Porus Opticus, 286 Pouch, Douglas, 327 Laryngeal, 354 Peritoneal, 327 Recto-vaginal, 327, 366 Recto-vesical, 327, 366 Utero-vesical, 327, 366 Umbilical, 367 Poupart's Ligament, 108, 387 Praeputium, 372 Precuneus, 185 Prepuce of the clitoris, 377 of the Penis, 372 Process, Acromion, 46 Alveolar, 29 Angular, 15 Articular, 5 Auditory, 25 Basilar, 18 Clinoid, 22, 24 Condylar, 34 Coracoid, 46 Coronoid, 34, 49 Ethmoidal, 22 Falciform, 390 Frontal, 28 Fronto-sphenoidal, 30 Hamular, 25, 29 Jugular, 1 8 Lacrimal, 32 Malar, 28 Mastoid, 20 Maxillary, 32 Mental (mentum; chin), 33 Nasal, 28 Odontoid, 7 Olecranon, 48 Olivary, 22 Orbital, 30, 32 Palatine, 29 Pterygoid, 25 Pyramidal, 32 Sphenoidal, 32 Spinous, 6 Styloid, 21, 49, 50, 55 Transverse, 5 Turbinal, 26 INDEX 425 Process, Unciform, 26 Uncinate, 26 Vaginal, 21 Vermiform, 206, 334 Zygapophyseal, 5 Zygomatic, 19, 28 Processes, Ciliary, 284 Clinoid, 23 of Ingrassias, 24 Processus, Anterior, 301 Cochleariformis, 21, 301 Gracilis, 301 Lateralis, 301 Prominence, Laryngeal, 350 Tuhal, 321 Promontory, of Cochlea, 300 of the Facial Canal, 300 of the Sacrum, n of the Tympanum, 300 Prosencephalon, 178 Prostate Gland, 370 Protuberance, Occipital, 17, 1 8 Psalterium, 190 Pterygoid, 3, 25 Pubes, 14 Pudendum Muliebre, 377 Pulmones, 357 Pulpa Dentis, 318 Lienis, 349 Pulvinar, 193 Punctum Lacrimale, 294 Pupil or Pupilla, 285 Purkinje's Cells, 176, 208 Pylorus, 329 Pyramid of the Cerebellum, 207 of the Medulla, 209 Posterior, 210 of the Thyroid Gland, 345 of the Tympanum, 301 Pyramids of Ferrein, 362 of Malpighi, 362 of Wistar (sphenoidal turbinals), 24 QUADRATE Lobe, 338 Lobule (cuneus), 186 Quadratus Femoris, 112 Labii, 78 Lumborum, 97 Menti, 78 Suadriceps Femoris, 108 uadrigeminal Bodies, 202 RADIUS, 49 Rami, Communicantes, 227, 238 Ramus, Ischio-pubic, 12 mandibular, 34 Raph6 of Medulla, 211 of the Perinaeum, 392 of the Tongue, 274 Receptaculum Chyli, 172 Recess or Recessus Atic, 300 Cochlearis, 305 Duodeno-jejunalis, 328 Ellipticus, 305 Epitympanic, 300 Ileo-caecalis, 328 Incudis, 300 Recess, Naso-palatine, 278 Sphaericus, 305 Spheno-ethmoidal, 277 Rectum, 335 Region or Regions, Abdominal, 95, 323 of the Arm, 100 Buccal, 78 Cervical, 80, 84 Cranial, 75 Dorsal, 86 of the Ear, 86 Epigastric, 324 of the Forearm, 102 Gastric, 324 Gluteal, no of the Hand, 105 Hyoid, 8 1 Hypo-chondriac, 324 Hypo-gastric, 324 Hypo-thalamic, 202 Iliac, 324 Inguinal, 324, 385 Ischio-rectal, 97 Laryngeal, 86, 88 Lingual, 82 Lumbar, 324 Mandibular, 78 Maxillary, 77 Nasal, 77 Orbital, 76 Palatal, 183 Palmar, 105 Palpebral, 75 Pelvic, 97 Perineal, 98, 99 Pharyngeal, 83 Plantar, 116 Pre vertebral, 84 Pterygoid, 79 of Shoulder, 100 Suboccipital, 88, 93 Temporo-mandibular, 79 Thoracic, 93, 99 of Thigh, 112 Tympanic. 80 Umbilical, 324 Vertebral, 84, 85 Reil, Island of, 183 Renes, 360 R6te. Carpi, 135 Mucosum, 270 Testis, 374 Rcticular Formation, 211 Retina, 285, 286 Rhombencephalon, 203 Ribes, Ganglion of, 236, 268 Ribs (costae), 8 Ridge, of Aquseductus Fallopii, 300 Articular of Temporal. 19 Condylar of Humerus, 48 Crucial, 18 Gluteal, 13 Infra-temporal, 24 Inter-trocnanteric, 53 Mylo-hyoid, 34 Nuchal, 17 Pterygoid, 24 Suprameatal, 19 426 INDEX Ridge, Temporal, 16 Rima Glottidis, 353 Palpebrarum, 293 Ring, Abdominal, Deep, 385 External, 386 Internal, 385 Superficial, 386 Crural, 389 Femoral, 389 Inguinalis Abdominalis, 385 Subcutaneous, 386 Rivinius, Duct of, 316 Notch of, 298 Rods and Cones, 287 of Corti, 310 Rolando, Fasciculus of, 209 Fissure of, 184 Root, Descending or Mesencephalic of the Trigeminal Nerve, 201 Rosenmiiller's Fossa, 322 Gland, 295 Organ, 383 Rostrum, 3 of the Sphenoid, 24 Rugae Vaginales, 379 SAC of Hilton, 354 Lacrimal, 296 Peritoneal, 325 Saccule, 304 Sacculus Laryngis, 354 Sacro-sciatic Foramen, 64 N9tch, 13 Santorini's Cartilages, 352 Muscle (risorius), 79 Saphenous Opening, 108, 389 Sapolini, on the Chorda Tympani, 276 Scala Media, 309 Tympani, 307 Vestibuli, 307 Scapha Auriculae, 297 Scaphoid Bone, 51, 57 Scapula, 45 Scarf-skin, 270 Scarpa's Fascia, 108, 385 Foramen, 29 Ganglion, 311 Triangle, 142 Schachowa's Tubes, 362 Schreger's Lines, 319 Schindylesis, 59 Schlemm's Canal, 282 Schultze's Olfactory Cells, 278 Schwann, Substance of, 177 Sclerotic, 281 Scrotum, 373 Sella Turcica, 22 Sense, Special, 270 Septum Canalis Musculo-tubarii, 301 Crurale, 389 Femorale, 389 Lucidum, 190 Narium, 276 Nasi, 276 Pectiniforme, 371 Pellucidum, 190 Transversum, 309 Tubae, 21 Sheath, Crural, 390 Femoral, 390 Shin-bone, 54 Shoulder, 44, 65 Shoulder-blade, 45 Shrapnell's Membrane, 298 Sight, Organ of, 280 Sigmoid Flexure, 334 Sinus, Coronary, 171 Maxillaris, 27 of Morgagni, 354 Pocularis, 368 Prostatic, 368 Renis, 361 Tonsillaris, 314 Venosus, 119, 282 Sinuses, of the Dura Mater, 164 Frontal, 15 Meningeal, 164 Sphenoidal, 23 of Valsalva, 120 Venous, 163 Skin, 270 Appendages of, 272 Skull, Base of, 41 Fossse of, 41, 42 Slit, Nasal (ethmoidal fissure), 38, 41 Smell, Organ of, 276 Socia Parotid is, 316 Space, Haversian, 4 Inter-peduncular, 189 Ischio-rectal, 394 Perforated, 186, 188, 193 Perinaeal, 393 Popliteal, 54 Subarachnoid, 181 Subdural, 181 Spaces of the Eyeball, 290 Fontana's, 282 Spatia Anguli Iridis, 282 Zonularia, 288, 289 Spermatic Cord, 376 Sphenoid Bone, 22 Sphincter Pupillae, 285 Vaginae, 99 Vesicae, 367 Spinal Cord, 213 Spine, Alar, 24 Ethmoidal, 22 Frontal, 15 of the Ilium, 13 of the Ischium, 13 Mandibular, 34 Nasal, 15, 29, 31 Pharyngeal, 18 of the Pubis, 14 of the Scapula, 45 of the Sphenoid, 22 of Spix (mandibular), 34 of the Tibia, 54 Spinous, 3 Splanchnology, i Spleen, 348 Spot, Blind, 286 Yellow, 285 Squamous, 3 Bone, 19 Stapes, 301 INDEX 427 Stenson's Duct, 316 Foramen, 29 Sternum, 8 Selling's Canal, 288 Roof Nucleus, 208 Stomach, 328 Stratum Cinereum, 202 Corneum, 270 Germinativum, 270 Granulosum, 270 Griseum Centrale, 197 Colliculi Superioris, 202 Intermedium, 197 Lemnici, 202 Lucidum, 270 Malpighii, 270 Opticum, 202, 286 Zonale, 202 Stria Terminalis, 190 Striae Acusticae, 212 Longitudinales, 190 Medullares, 212 Obliquae, 212 Stripe, Malleolar, 298 Styloid, 3 Process, 21 Submaxillary, now called Submandibu- lar Substantia Adamantina, 319 Alba, see White Matter, 177 Eburnea, 319 Gelatinosa (Rolandi), 204, 209 Grisea, see Gray Matter, 176 Ossea, 319 Perforata, 186, 188, 193 Sulci, 183, see also Grooves and Fissures Sulcus Cerebri Centralis, 184 Chiasmatis, 22 Longitudinalis Medianus, 212 Medianus Linguae, 274 Nervi Oculo-motorii, 22 Radialis, 47 Sagittalis, 15 Spiralis Internus, 309 Tympanicus, 298 Supercilia, 293 Sustentaculum Tali, 57 Sutura, 59 Suture or Sutures Coronal, 16, 40 Cranial, 40 Facial, 40 Lambdoid, 16 Metppic, 14 Orbital, 37 Sagittal, 16, 40 Sylvius, Aquaeduct of, 202 Fissure of, 184 Sympathetic System, 236, 268 Symphysis, 33, 59, 64 Synarthrosis, 59 Synovia, 60 Synovial Membranes, 60 Syndesmology, i, 58 Syndesmosis, 59 System, Arterial, 122 Cerebro-spinal Nervous, 178 Chromaffin, 344 System, Chromaphil, 344 Haversian, 4 Lymphatic, 171 Nervous, 175 Phaerochrome, 344 Portal, 170 Sympathetic Nervous, 236, 268 Vascular, 118 Venous, 163 TAPETUM, 283, 286 Tarsi, 294 Tarsus, 57 Taste, Nerves of, 275 Taste-buds, 275 Taenia Hippocampi, 190 Semicircularis, 190 Tectum, 202 Mesencephali, 202 Teeth, 31? Development of, 319 Eruption of, 320 Tegmentum, 197 Tela Choroidea Inferior, 211 Ventriculi Tertii, 190 Subcutaneous, 74 Telencephalon, 178 Temporal Bone, 19 Tendo Oculi, 294 Tendon of Achilles, 113 Conjoined, 95 Tendons, 74 Tenon's Capsule, 280 Tentqrium Cerebelli, 181 Terminal Organs, 177 Testes, 392 Appendages of, 375 Coverings of, 373 Descent of, 375 Quadrigeminal, 202 Testicle, 392 Thalamencephalon, 192 Thalamus Opticus, 193 Thebesius, Foramena of, 119 Thenar Eminence, 106 Thigh, 112 Thorax, 7, 93, 99 Thymus Gland, 347 Thyro-hyal, 41 Thyroid (or thyreoid) Axis, 131, 152 Cartilage, 350 Gland, 345 Tibia, 54 Tissue, Erectile, 371 Gray Nervous, 176 White Nervous, 177 Todd and Bowman, Muscle of, 309 Tongue, 273 Muscles of, 82, 83 Tonsil, Cerebcllar, 207 Palatine, 314 Pharyngeal, 321 . Tubal, 303 Torcular Herophili, 18, 165 Torus Tubarius, 321 Trabeculse Lienis, 349 Trachea, 355 Tract, see also Fasciculus 428 INDEX Tract, Anterior (or direct) Pyramidal, 196, 214 Ascending Antero-lateral (Gower's), 205, 214 Caudate-cerebellar, 197 Central Tegmental, 202 Cerebro-spinal, 196, 214 Cortico-pontine, 19? Crossed Pyramidal, 196, 214 Descending Root of Trigeminus, 201 Direct Cerebellar (Flechsig's), 210, 215 Direct (or anterior) Pyramidal, 196, 214 Flechsig's, 210, 215 Fronto-pontine, 197 Gower's, 205, 214 Indirect Motor, 197 Lissauer's, 215 Mesencephalic Root of Trigeminus, 2OI Mesencephalo- (or tecto-) Spinal, 199 Monakow's, 201 Motor, Direct, 196 Indirect, 197 Postero-lateral, 215 Pre-pyramidal, 201 Pyramidal, 196 Rolando's, 209 Rubro-spinal, 201 Solitary, 211. 221 Spino-cerebellar, 205, 214 Spino-thalamic, 200 Tecto- (or mesencephalo-) Spinal, 199 Temporo-pontme, 197 Thalamo-olivary, 202 Transverse Peduncular, 180 Uncrossed Pyramidal, 196 Uveal, 281 Ventral Spino-cerebellar, 205, 206 Ventro-lateral Spino-cerebellar, 205, 206 Tractus Spiralis Foraminosus, 311 Tragus, 297 Trapezium Medullas Oblpngatae, 204 Triangle, Anterior, Cervical, 128 Carotid, 129 Femoral, 142 Habenular, 194 Hesselbach's, 387 Interosseous of Fibula, 56 Occipital, 130 Posterior Cervical, 130 Scarpa's, 142 Subclavian, 130 Subcutaneous of Fibula, 56 Submandibular, 129 Submaxillary, 129 Triangles of the Neck, 128 Trigonum Acustici, 212 Collaterale, 191 Femorale, 142 Habenulae, 194 Hypoglossi, 212 Olfactorium, 217 Trigonum Vagi, 212 Vesicse, 367 Triquetrum (cuneiform), 51 Trochanters, 3 of Femur, 53 Trochlea, of Humerus, 48 of the Orbit, 289 Trochlear, 3 Nerve, 217, 244 Trochoides, 59 Tuba Auditiva, 303 Tuba? Uterinae, 382 Tube or Tubes Eustachian, 303 Fallopian, 382 Neural, 178 of Shachowa, 362 Tube-tonsil, 303 Tuber Cinereum, 186 Valvulas, 207 Tubercle or Tubercles, 3 Adductor, 54 Amygdaloid, 179 Anterior of the Thalamus, 193 Bicipital, 49 Darwin's, 297 Genial, 34 of Humerus, 47 of Lower, 120 Pharyngeal, 18 Zygomatic, 19 Tuberculum, Acusticum, 212 Auriculae, 297 Intervenosum, 120 Sellse, 22 Tube^sity or Tuberosities, 3 Bicipital, 49 of Femur, 54 of Humerus, 47 of Ischium, 14 Malar, 30 Maxillary, 28 of Palate, 32 of Radius, 49 of Tibia, 54 of Ulna, 49 Tubules or Tubuli Convoluted, 362 Dentinal, 319 Lactiferi, 384 Renales, 362 Seminiferi, 374 Spiral, 362 Uriniferi, 362 Tuft, Malpighian, 361 Tunica Albugenia, 374 Conjunctiva, 294 Fibrosa Oculi, 281 Interna Oculi, 285 Ruyschiana, 283 Vaginalis Testis, 374 Vascu^sa Oculi, 283 Testis, 374 Tunics of the Eyeball, 281 of the Testicle, 374 Turbinals, 32 Sphenoidal, 24 Tutamina Oculi, 293 INDEX 429 Tympanic Bone, 21 Tympanum, 300 Tyson's Glands, 372 ULNA, 48 Umbilical Region, 324 Umbilicus, 324 Umbo, 298 Unciform, 3 Uncinate Gyrus, 186 Ungues. 272 Urachus, 366 Ureters, 363 Urethra, Female, 370 Male, 368 Urogenital Diaphragm, 393 Uterus, 380 Appendages of, 382 Masculinus, 368 Utricle, 307 Utriculus Prostaticus, 368 Uvea, 285 Uveal Tract, 281 Uvula, 313 Cerebelli, 207 Vesicae, 367 VAGINA, 379 Vaginal, 3 Process, 21 Vallecula, 206 Valsalva, Sinuses of, 120, 122 Valve of Bauhin, 331, 334 Coronary, 120 Eustachian, 120 of Hasner, 296 Ileo-caecal, 331, 334 Mitral, 121 Pyloric, 329 of Thebesius, 120 Tricuspid, 120 of Vieussens, 203, 207 Valves, Aortic Semilunar, 121 of Houston, 335 of Kirkring, 332 Pulmonary, 120 Semilunar, 120, 122 Valvulae Coli, 334 Conniventes, 332 Sinus Coronarii, 120 Venae Cavae Inferioris, 120 Vas Aberrans, 373 Deferens, 375 Spirale, 309 Vasa Efferentia, 374 Recta, 374 Vasorum, 122 Vein or Veins, 163 Angular, 164 Auricular, 164 Axillary, 166 Azygps, 167 Basilic. 166 Bronchial, 356 Cardiac, 171 Cephalic, 166 Cerebellar, 164 Cerebral, 164 Veins, Choroid, 283 Cystic, 170 Emissary, 165 Facial, 164 Femoral, 168 Frontal, 163 Gastric, 170 Hepatic, 170, 3 2 Iliac, 169 Innominate, 166 Intercostal, 167 Interlobular, 342 Intralobular, 342 ugular, 165 ienal (splenic), 170 Lobular, 342 Lumbar, 170 Mammary, 167 Maxillary, 164 Median, 166 Mesenteric, 170 Occipital, 164 Ovarian, 170 Phrenic, 170 Popliteal, 1 68 Portal, 170, 341 Pulmonary, 163 Radial, 166 Renal, 170, 363 Saphenous. 168, 169 Spermatic, 170 Spinal, 168 Splenic, 170. 349 Subclavian, 166 Sublobular, 342 Supraorbital, 163 Supra-renal, 170 Temporal, 164 Thyroid, 167 Ulnar, 166 Uterine, 382 Vertebral, 166 Veins of the Abdomen, 169 Bladder, 368 Bone, 4 Diploe, 164 Ear, 312 Head and Neck, 163 Heart, 171 Intestine, 333, 336 Kidney, 363 Larynx, 354 Liver, 341, 342 Lower Extremity, 168 Lung, 359 Mammary Gland, 384 Membrana Tympani, 299 Neck, 165 Nose, 279 (Esophagus, 323 Ovaries, 383 Pancreas, 344 Pelvis, 169 Penis, 372 of Pharynx, 322 Prostate Gland, 37 Rectum, 336 Stomach, 330 43 C INDEX Veins, Supra-renal Glands, 365 Testicle, 375 Thorax, 167 Thymus Gland, 347 Thyroid Gland, 346 Tongue, 275 Tonsil, 314 Trachea and Bronchi, 356 Tympanic Membrane, 299 Tympanum, 302 Upper Extremity, 166 Uterus, 382 Vagina, 379 Without Valves, 163 Velum, Inferior Medullary, 212 Interpositum, 190 Superior Medullary, 203, 207 Vena Cava, Inferior, 170 Superior, 168 Venae Comites, 163 Galense, 185 Proprise Renales, 363 Rectae, 363 Vorticosae, 290 Venous Sinuses, 163 System, 163 Portal, 170 Pulmonary, 163 Systemic, 163 Ventricle of Cerebellum, 211 Lateral, 189 Fifth, 191 Fourth, 211 Laryngeal, 354 Nasal, 277 Third, 189, 192 Ventriculus, 328 Vermis Cerebelli, 206 Superior, 207 Vertebrae, 5 Important Relations of, 7 Vertebral Aponeurosis, 90 Verumontanum, 368 Vesica Fellea, 3^3 Urinaria, 365 Vesicle, Graafian, 383 Vesicles of the Brain, 178 Seminal, 376 Vestibule of the Ear, 305 of the Larynx, 353 of the Mouth, 312 of the Nose, 277 of the Vulva, 378 Vidian Canal, 25 Vieussens, Valve of, 203, 207 Villi of the Intestine, 332 Vinculum Lingua?, 207 Viscera covered by Peritoneum, 327 Vocal Cords, 353 Vomer, 33 Vortex of the Heart, 118 Vulva, 377 WAGNER'S Corpuscles, 177 Wharton's Duct, 316 White Matter of the Brain, 179 Rami Communicantes, 227 Willis, Circle of, 128, 151 Winslow's Foramen, 326 Ligament, 70 Wirsung's Duct, 344 Worm, 207 Wormian Bones, 3, 40 Wrisberg's Cartilage, 352 Ganglion, 239 Ligament, 71 Nerve, 229 XYPHOID Appendix, 8 YELLOW Spot, 285 ZINN, Ligament of, 76 Zonule, 288 Zona Arcuata, 309 Pectinate, 309 Zonula Ciliaris, 288 Zonule of Zinn, 288 Zygapophyses, 5 Zygoma, 19 Zygomatic Bone, 30 2A>V0J^ cp&. (T ;WU ,) / o